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Sample records for total dissolved concentrations

  1. Concentration and flux of total and dissolved phosphorus, total nitrogen, chloride, and total suspended solids for monitored tributaries of Lake Champlain, 1990-2012

    Science.gov (United States)

    Medalie, Laura

    2014-01-01

    Annual and daily concentrations and fluxes of total and dissolved phosphorus, total nitrogen, chloride, and total suspended solids were estimated for 18 monitored tributaries to Lake Champlain by using the Weighted Regressions on Time, Discharge, and Seasons regression model. Estimates were made for 21 or 23 years, depending on data availability, for the purpose of providing timely and accessible summary reports as stipulated in the 2010 update to the Lake Champlain “Opportunities for Action” management plan. Estimates of concentration and flux were provided for each tributary based on (1) observed daily discharges and (2) a flow-normalizing procedure, which removed the random fluctuations of climate-related variability. The flux bias statistic, an indicator of the ability of the Weighted Regressions on Time, Discharge, and Season regression models to provide accurate representations of flux, showed acceptable bias (less than ±10 percent) for 68 out of 72 models for total and dissolved phosphorus, total nitrogen, and chloride. Six out of 18 models for total suspended solids had moderate bias (between 10 and 30 percent), an expected result given the frequently nonlinear relation between total suspended solids and discharge. One model for total suspended solids with a very high bias was influenced by a single extreme value; however, removal of that value, although reducing the bias substantially, had little effect on annual fluxes.

  2. Factors influencing concentrations of dissolved gaseous mercury (DGM) and total mercury (TM) in an artificial reservoir

    International Nuclear Information System (INIS)

    Ahn, Myung-Chan; Kim, Bomchul; Holsen, Thomas M.; Yi, Seung-Muk; Han, Young-Ji

    2010-01-01

    The effects of various factors including turbidity, pH, DOC, temperature, and solar radiation on the concentrations of total mercury (TM) and dissolved gaseous mercury (DGM) were investigated in an artificial reservoir in Korea. Episodic total mercury accumulation events occurred during the rainy season as turbidity increased, indicating that the TM concentration was not controlled by direct atmospheric deposition. The DGM concentration in surface water ranged from 3.6 to 160 pg/L, having a maximum in summer and minimum in winter. While in most previous studies DGM was controlled primarily by a photo-reduction process, DGM concentrations tracked the amount of solar radiation only in winter when the water temperature was fairly low in this study. During the other seasons microbial transformation seemed to play an important role in reducing Hg(II) to Hg(0). DGM increased as dissolved organic carbon (DOC) concentration increased (p-value < 0.01) while it increased with a decrease of pH (p-value < 0.01). - Long-term in-situ monitoring of TM and DGM concentrations with various factors was executed in a large artificial reservoir in this study.

  3. Total dissolved carbohydrate in Mahi river estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Rokade, M.A.; Zingde, M.D.

    Total dissolved carbohydrate varied from 4.37-15 mg l-1 and 3.71-15.95 mg l-1 in the surface and bottom samples respectively. Highest concentration of carbohydrate was observed at station 1 which decreased downward upto Station 6 which showed...

  4. Inter-relationship between major ions, total dissolved solids and ...

    African Journals Online (AJOL)

    Sulphate and magnesium concentrations were highest in station 7 while other parameters (potassium, chloride, calcium, alkalinity, conductivity and total dissolved solids (T. D. S.)) were highest in station 6. The ponds belong to class 1 of the African waters since they all have electrical conductance of less than 600 s cm-1.

  5. Accuracy of different sensors for the estimation of pollutant concentrations (total suspended solids, total and dissolved chemical oxygen demand) in wastewater and stormwater.

    Science.gov (United States)

    Lepot, Mathieu; Aubin, Jean-Baptiste; Bertrand-Krajewski, Jean-Luc

    2013-01-01

    Many field investigations have used continuous sensors (turbidimeters and/or ultraviolet (UV)-visible spectrophotometers) to estimate with a short time step pollutant concentrations in sewer systems. Few, if any, publications compare the performance of various sensors for the same set of samples. Different surrogate sensors (turbidity sensors, UV-visible spectrophotometer, pH meter, conductivity meter and microwave sensor) were tested to link concentrations of total suspended solids (TSS), total and dissolved chemical oxygen demand (COD), and sensors' outputs. In the combined sewer at the inlet of a wastewater treatment plant, 94 samples were collected during dry weather, 44 samples were collected during wet weather, and 165 samples were collected under both dry and wet weather conditions. From these samples, triplicate standard laboratory analyses were performed and corresponding sensors outputs were recorded. Two outlier detection methods were developed, based, respectively, on the Mahalanobis and Euclidean distances. Several hundred regression models were tested, and the best ones (according to the root mean square error criterion) are presented in order of decreasing performance. No sensor appears as the best one for all three investigated pollutants.

  6. Ultraviolet absorbance as a proxy for total dissolved mercury in streams

    International Nuclear Information System (INIS)

    Dittman, Jason A.; Shanley, James B.; Driscoll, Charles T.; Aiken, George R.; Chalmers, Ann T.; Towse, Janet E.

    2009-01-01

    Stream water samples were collected over a range of hydrologic and seasonal conditions at three forested watersheds in the northeastern USA. Samples were analyzed for dissolved total mercury (THg d ), DOC concentration and DOC composition, and UV 254 absorbance across the three sites over different seasons and flow conditions. Pooling data from all sites, we found a strong positive correlation of THg d to DOC (r 2 = 0.87), but progressively stronger correlations of THg d with the hydrophobic acid fraction (HPOA) of DOC (r 2 = 0.91) and with UV 254 absorbance (r 2 = 0.92). The strength of the UV 254 absorbance-THg d relationship suggests that optical properties associated with dissolved organic matter may be excellent proxies for THg d concentration in these streams. Ease of sample collection and analysis, the potential application of in-situ optical sensors, and the possibility for intensive monitoring over the hydrograph make this an effective, inexpensive approach to estimate THg d flux in drainage waters. - Ultraviolet absorbance measurements are a cost-effective proxy to estimate dissolved mercury concentration in stream water.

  7. Measuring and understanding total dissolved gas pressure in groundwater

    Science.gov (United States)

    Ryan, C.; Roy, J. W.; Randell, J.; Castellon, L.

    2009-05-01

    Since dissolved gases are important to a number of aspects of groundwater (e.g. age dating, active or passive bioremediation, greenhouse gas fluxes, understanding biogeochemical processes involving gases, assessing potential impacts of coal bed methane activities), accurate concentration measurements, and understanding of their subsurface behaviour are important. Researchers have recently begun using total dissolved gas pressure (TGP) sensor measurements, more commonly applied for surface water monitoring, in concert with gas composition analyses to estimate more accurate groundwater gas concentrations in wells. We have used hydraulic packers to isolate the well screens where TDP is being measured, and pump tests to indicate that in-well degassing may reduce TDG below background groundwater levels. Thus, in gas-charged groundwater zones, TGPs can be considerably underestimated in the absence of pumping or screen isolation. We have also observed transient decreased TGPs during pumping that are thought to result from ebullition induced when the water table or water level in the well is lowered below a critical hydrostatic pressure.

  8. Total Dissolved Gas Monitoring in Chum Salmon Spawning Gravels Below Bonneville Dam

    Energy Technology Data Exchange (ETDEWEB)

    Arntzen, Evan V.; Geist, David R.; Panther, Jennifer L.; Dawley, Earl

    2007-01-30

    At the request of the U.S. Army Corps of Engineers (Portland District), Pacific Northwest National Laboratory (PNNL) conducted research to determine whether total dissolved gas concentrations are elevated in chum salmon redds during spring spill operations at Bonneville Dam. The study involved monitoring the total dissolved gas levels at egg pocket depth and in the river at two chum salmon spawning locations downstream from Bonneville Dam. Dissolved atmospheric gas supersaturation generated by spill from Bonneville Dam may diminish survival of chum (Oncorhynchus keta) salmon when sac fry are still present in the gravel downstream from Bonneville Dam. However, no previous work has been conducted to determine whether total dissolved gas (TDG) levels are elevated during spring spill operations within incubation habitats. The guidance used by hydropower system managers to provide protection for pre-emergent chum salmon fry has been to limit TDG to 105% after allowing for depth compensation. A previous literature review completed in early 2006 shows that TDG levels as low as 103% have been documented to cause mortality in sac fry. Our study measured TDG in the incubation environment to evaluate whether these levels were exceeded during spring spill operations. Total dissolved gas levels were measured within chum salmon spawning areas near Ives Island and Multnomah Falls on the Columbia River. Water quality sensors screened at egg pocket depth and to the river were installed at both sites. At each location, we also measured dissolved oxygen, temperature, specific conductance, and water depth to assist with the interpretation of TDG results. Total dissolved gas was depth-compensated to determine when levels were high enough to potentially affect sac fry. This report provides detailed descriptions of the two study sites downstream of Bonneville Dam, as well as the equipment and procedures employed to monitor the TDG levels at the study sites. Results of the monitoring at

  9. Refractometric total protein concentrations in icteric serum from dogs.

    Science.gov (United States)

    Gupta, Aradhana; Stockham, Steven L

    2014-01-01

    To determine whether high serum bilirubin concentrations interfere with the measurement of serum total protein concentration by refractometry and to assess potential biases among refractometer measurements. Evaluation study. Sera from 2 healthy Greyhounds. Bilirubin was dissolved in 0.1M NaOH, and the resulting solution was mixed with sera from 2 dogs from which food had been withheld to achieve various bilirubin concentrations up to 40 mg/dL. Refractometric total protein concentrations were estimated with 3 clinical refractometers. A biochemical analyzer was used to measure biuret assay-based total protein and bilirubin concentrations with spectrophotometric assays. No interference with refractometric measurement of total protein concentrations was detected with bilirubin concentrations up to 41.5 mg/dL. Biases in refractometric total protein concentrations were detected and were related to the conversion of refractive index values to total protein concentrations. Hyperbilirubinemia did not interfere with the refractometric estimation of serum total protein concentration. The agreement among total protein concentrations estimated by 3 refractometers was dependent on the method of conversion of refractive index to total protein concentration and was independent of hyperbilirubinemia.

  10. DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS

    Energy Technology Data Exchange (ETDEWEB)

    NA

    2004-11-22

    The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of elements with radioactive isotopes under probable repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, field measurements, and laboratory experiments. The scope of this modeling activity is to predict dissolved concentrations or solubility limits for 14 elements with radioactive isotopes (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium) important to calculated dose. Model outputs for uranium, plutonium, neptunium, thorium, americium, and protactinium are in the form of tabulated functions with pH and log (line integral) CO{sub 2} as independent variables, plus one or more uncertainty terms. The solubility limits for the remaining elements are either in the form of distributions or single values. The output data from this report are fundamental inputs for Total System Performance Assessment for the License Application (TSPA-LA) to determine the estimated release of these elements from waste packages and the engineered barrier system. Consistent modeling approaches and environmental conditions were used to develop solubility models for all of the actinides. These models cover broad ranges of environmental conditions so that they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, and activity coefficients have been quantified or otherwise addressed.

  11. Analysis of total and dissolved heavy metals in surface water of a Mexican polluted river by total reflection X-ray fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Zarazua, G. [Instituto Nacional de Investigaciones Nucleares, Gerencia de Ciencias Ambientales, Apartado Postal 18-1027, Mexico D.F., C.P. 11801 (Mexico)]. E-mail: gzo@nuclear.inin.mx; Avila-Perez, P. [Instituto Nacional de Investigaciones Nucleares, Gerencia de Ciencias Ambientales, Apartado Postal 18-1027, Mexico D.F., C.P. 11801 (Mexico); Tejeda, S. [Instituto Nacional de Investigaciones Nucleares, Gerencia de Ciencias Ambientales, Apartado Postal 18-1027, Mexico D.F., C.P. 11801 (Mexico); Barcelo-Quintal, I. [Universidad Autonoma Metropolitana, Unidad Azcapotzalco, Mexico, D.F. (Mexico); Martinez, T. [Universidad Nacional Autonoma de Mexico, Facultad de Quimica, Mexico, D.F. (Mexico)

    2006-11-15

    The present area of study is located in the Upper Course of the Lerma River (UCLR). The Lerma is one of the most important rivers of Mexico, where it drains highly populated and industrialized regions. The aim of the present study is to determine the heavy metal concentration of Cr, Mn, Fe, Cu and Pb in dissolved and total phases of the UCLR by means of Total Reflection X-ray Fluorescence Spectrometry (TXRF). The surface water samples were collected at 8 sites distributed following the stream flow direction of the river. Four sampling campaigns were carried out in each site in a 1-year period. A sample preparation method was applied in order to obtain the total and dissolved fraction and to destroy the organic matter. The total heavy metal average concentration decrease in the following order: Fe (2566 {mu}g/L) > Mn (300 {mu}g/L) > Cu (66 {mu}g/L) > Cr (21 {mu}g/L) > Pb (15 {mu}g/L). In general, the heavy metal concentrations in water of the UCLR are below the maximum permissible limits.

  12. Analysis of total and dissolved heavy metals in surface water of a Mexican polluted river by total reflection X-ray fluorescence spectrometry

    Science.gov (United States)

    Zarazua, G.; Ávila-Pérez, P.; Tejeda, S.; Barcelo-Quintal, I.; Martínez, T.

    2006-11-01

    The present area of study is located in the Upper Course of the Lerma River (UCLR). The Lerma is one of the most important rivers of Mexico, where it drains highly populated and industrialized regions. The aim of the present study is to determine the heavy metal concentration of Cr, Mn, Fe, Cu and Pb in dissolved and total phases of the UCLR by means of Total Reflection X-ray Fluorescence Spectrometry (TXRF). The surface water samples were collected at 8 sites distributed following the stream flow direction of the river. Four sampling campaigns were carried out in each site in a 1-year period. A sample preparation method was applied in order to obtain the total and dissolved fraction and to destroy the organic matter. The total heavy metal average concentration decrease in the following order: Fe (2566 μg/L) > Mn (300 μg/L) > Cu (66 μg/L) > Cr (21 μg/L) > Pb (15 μg/L). In general, the heavy metal concentrations in water of the UCLR are below the maximum permissible limits.

  13. Analysis of total and dissolved heavy metals in surface water of a Mexican polluted river by total reflection X-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    Zarazua, G.; Avila-Perez, P.; Tejeda, S.; Barcelo-Quintal, I.; Martinez, T.

    2006-01-01

    The present area of study is located in the Upper Course of the Lerma River (UCLR). The Lerma is one of the most important rivers of Mexico, where it drains highly populated and industrialized regions. The aim of the present study is to determine the heavy metal concentration of Cr, Mn, Fe, Cu and Pb in dissolved and total phases of the UCLR by means of Total Reflection X-ray Fluorescence Spectrometry (TXRF). The surface water samples were collected at 8 sites distributed following the stream flow direction of the river. Four sampling campaigns were carried out in each site in a 1-year period. A sample preparation method was applied in order to obtain the total and dissolved fraction and to destroy the organic matter. The total heavy metal average concentration decrease in the following order: Fe (2566 μg/L) > Mn (300 μg/L) > Cu (66 μg/L) > Cr (21 μg/L) > Pb (15 μg/L). In general, the heavy metal concentrations in water of the UCLR are below the maximum permissible limits

  14. Concentration, flux, and the analysis of trends of total and dissolved phosphorus, total nitrogen, and chloride in 18 tributaries to Lake Champlain, Vermont and New York, 1990–2011

    Science.gov (United States)

    Medalie, Laura

    2013-01-01

    Annual concentration, flux, and yield for total phosphorus, dissolved phosphorus, total nitrogen, and chloride for 18 tributaries to Lake Champlain were estimated for 1990 through 2011 using a weighted regression method based on time, tributary streamflows (discharges), and seasonal factors. The weighted regression method generated two series of daily estimates of flux and concentration during the period of record: one based on observed discharges and a second based on a flow-normalization procedure that removes random variation due to year-to-year climate-driven effects. The flownormalized estimate for a given date is similar to an average estimate of concentration or flux that would be made if all of the observed discharges for that date were equally likely to have occurred. The flux bias statistic showed that 68 of the 72 flux regression models were minimally biased. Temporal trends in the concentrations and fluxes were determined by calculating percent changes in flow-normalized annual fluxes for the full period of analysis (1990 through 2010) and for the decades 1990–2000 and 2000–2010. Basinwide, flow-normalized total phosphorus flux decreased by 42 metric tons per year (t/yr) between 1990 and 2010. This net result reflects a basinwide decrease in flux of 21 metric tons (t) between 1990 and 2000, followed by a decrease of 20 t between 2000 and 2010; both results were largely influenced by flux patterns in the large tributaries on the eastern side of the basin. A comparison of results for total phosphorus for the two separate decades of analysis found that more tributaries had decreasing concentrations and flux rates in the second decade than the first. An overall reduction in dissolved phosphorus flux of 0.7 t/yr was seen in the Lake Champlain Basin during the full period of analysis. That very small net change in flux reflects substantial reductions between 1990 and 2000 from eastern tributaries, especially in Otter Creek and the LaPlatte and Winooski

  15. Attenuated total reflection UV spectroscopy for simultaneous analysis of alkali, sulphide and dissolved lignin in pulping liquors

    International Nuclear Information System (INIS)

    Chai, X.S.; Zhu, J.Y.; Luo, Q.; Li, J.

    2003-01-01

    This study experimentally demonstrated attenuated total reflection (ATR) ultraviolet (UV) spectroscopy for rapid and simultaneous determination of the concentrations of hydroxide, sulphide and dissolved lignin in kraft pulping liquors. A multivariate partial least squares fitting procedure (using commercially available software) was employed to obtain the species concentrations from the measured absorption spectra of the pulping liquors. Good agreements between ATR-UV measured species concentrations and those obtained by reference methods (titration for hydroxide and sulphide and conventional UV absorption for dissolved lignin) were achieved. (author)

  16. Ultraviolet absorbance as a proxy for total dissolved mercury in streams

    Science.gov (United States)

    Dittman, J.A.; Shanley, J.B.; Driscoll, C.T.; Aiken, G.R.; Chalmers, A.T.; Towse, J.E.

    2009-01-01

    Stream water samples were collected over a range of hydrologic and seasonal conditions at three forested watersheds in the northeastern USA. Samples were analyzed for dissolved total mercury (THgd), DOC concentration and DOC composition, and UV254 absorbance across the three sites over different seasons and flow conditions. Pooling data from all sites, we found a strong positive correlation of THgd to DOC (r2 = 0.87), but progressively stronger correlations of THgd with the hydrophobic acid fraction (HPOA) of DOC (r2 = 0.91) and with UV254 absorbance (r2 = 0.92). The strength of the UV254 absorbance-THgd relationship suggests that optical properties associated with dissolved organic matter may be excellent proxies for THgd concentration in these streams. Ease of sample collection and analysis, the potential application of in-situ optical sensors, and the possibility for intensive monitoring over the hydrograph make this an effective, inexpensive approach to estimate THgd flux in drainage waters. ?? 2009 Elsevier Ltd.

  17. Dissolved Concentration Limits of Radioactive Elements

    Energy Technology Data Exchange (ETDEWEB)

    Y. Chen; E.R. Thomas; F.J. Pearson; P.L. Cloke; T.L. Steinborn; P.V. Brady

    2003-06-20

    The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of radioactive elements under possible repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, and measurements made in laboratory experiments and field work. The scope of this modeling activity is to predict dissolved concentrations or solubility limits for 14 radioactive elements (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium), which are important to calculated dose. Model outputs are mainly in the form of look-up tables plus one or more uncertainty terms. The rest are either in the form of distributions or single values. The results of this analysis are fundamental inputs for total system performance assessment to constrain the release of these elements from waste packages and the engineered barrier system. Solubilities of plutonium, neptunium, uranium, americium, actinium, thorium, protactinium, lead, and radium have been re-evaluated using the newly updated thermodynamic database (Data0.ymp.R2). For all of the actinides, identical modeling approaches and consistent environmental conditions were used to develop solubility models in this revision. These models cover broad ranges of environmental conditions so that they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, activity coefficients, and selection of solubility controlling phase have been quantified or otherwise addressed. Moreover, a new blended plutonium solubility model has been developed in this revision, which gives a mean solubility that is three orders of magnitude lower than the plutonium solubility model used for the Total System Performance Assessment for the Site Recommendation. Two alternative neptunium solubility models have also been

  18. Dissolved Concentration Limits of Radioactive Elements

    International Nuclear Information System (INIS)

    Y. Chen; E.R. Thomas; F.J. Pearson; P.L. Cloke; T.L. Steinborn; P.V. Brady

    2003-01-01

    The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of radioactive elements under possible repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, and measurements made in laboratory experiments and field work. The scope of this modeling activity is to predict dissolved concentrations or solubility limits for 14 radioactive elements (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium), which are important to calculated dose. Model outputs are mainly in the form of look-up tables plus one or more uncertainty terms. The rest are either in the form of distributions or single values. The results of this analysis are fundamental inputs for total system performance assessment to constrain the release of these elements from waste packages and the engineered barrier system. Solubilities of plutonium, neptunium, uranium, americium, actinium, thorium, protactinium, lead, and radium have been re-evaluated using the newly updated thermodynamic database (Data0.ymp.R2). For all of the actinides, identical modeling approaches and consistent environmental conditions were used to develop solubility models in this revision. These models cover broad ranges of environmental conditions so that they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, activity coefficients, and selection of solubility controlling phase have been quantified or otherwise addressed. Moreover, a new blended plutonium solubility model has been developed in this revision, which gives a mean solubility that is three orders of magnitude lower than the plutonium solubility model used for the Total System Performance Assessment for the Site Recommendation. Two alternative neptunium solubility models have also been

  19. Reactive Transport Modeling Investigation of High Dissolved Sulfide Concentrations in Sedimentary Basin Rocks

    Science.gov (United States)

    Xie, M.; Mayer, U. K.; MacQuarrie, K. T. B.

    2017-12-01

    Water with total dissolved sulfide in excess of 1 mmol L-1is widely found in groundwater at intermediate depths in sedimentary basins, including regions of the Michigan basin in southeastern Ontario, Canada. Conversely, at deeper and shallower depths, relatively low total dissolved sulfide concentrations have been reported. The mechanisms responsible for the occurrence of these brackish sulfide-containing waters are not fully understood. Anaerobic microbial sulfate reduction is a common process resulting in the formation of high sulfide concentrations. Sulfate reduction rates depend on many factors including the concentration of sulfate, the abundance of organic substances, redox conditions, temperature, salinity and the species of sulfate reducing bacteria (SRB). A sedimentary basin-specific conceptual model considering the effect of salinity on the rate of sulfate reduction was developed and implemented in the reactive transport model MIN3P-THCm. Generic 2D basin-scale simulations were undertaken to provide a potential explanation for the dissolved sulfide distribution observed in the Michigan basin. The model is 440 km in the horizontal dimension and 4 km in depth, and contains fourteen sedimentary rock units including shales, sandstones, limestones, dolostone and evaporites. The main processes considered are non-isothermal density dependent flow, kinetically-controlled mineral dissolution/precipitation and its feedback on hydraulic properties, cation exchange, redox reactions, biogenic sulfate reduction, and hydromechanical coupling due to glaciation-deglaciation events. Two scenarios were investigated focusing on conditions during an interglacial period and the transient evolution during a glaciation-deglaciation cycle. Inter-glaciation simulations illustrate that the presence of high salinity brines strongly suppress biogenic sulfate reduction. The transient simulations show that glaciation-deglaciation cycles can have an impact on the maximum depth of

  20. Development and application of the diffusive gradients in thin films technique for the measurement of total dissolved inorganic arsenic in waters

    Energy Technology Data Exchange (ETDEWEB)

    Panther, Jared G.; Stillwell, Kathryn P.; Powell, Kipton J. [Chemistry Department, University of Canterbury, Private Bag 4800, Christchurch (New Zealand); Downard, Alison J. [Chemistry Department, University of Canterbury, Private Bag 4800, Christchurch (New Zealand)], E-mail: alison.downard@canterbury.ac.nz

    2008-08-01

    The diffusive gradients in thin films (DGT) technique, utilizing an iron-hydroxide adsorbent, has been investigated for the in situ accumulation of total dissolved inorganic As in natural waters. Diffusion coefficients of the inorganic As{sup V} and As{sup III} species in the polyacrylamide gel were measured using a diffusion cell and DGT devices and a variety of factors that may affect the adsorption of the As species to the iron-hydroxide adsorbent, or the diffusion of the individual As species, were investigated. Under conditions commonly encountered in environmental samples, solution pH and the presence of anions, cations, fulvic acid, Fe{sup III}-fulvic acid complexes and colloidal iron-hydroxide were demonstrated not to affect uptake of dissolved As. To evaluate DGT as a method for accumulation and pre-concentration of total dissolved inorganic As in natural waters, DGT was applied to two well waters and a river water that was spiked with As. For each sample, the concentration obtained with use of DGT followed by measurement by hydride generation atomic absorption spectrometry with a Pd modifier (HG-AAS) was compared with the concentration of As measured directly by HG-AAS. The results confirmed that DGT is a reliable method for pre-concentration of total dissolved As.

  1. Development and application of the diffusive gradients in thin films technique for the measurement of total dissolved inorganic arsenic in waters

    International Nuclear Information System (INIS)

    Panther, Jared G.; Stillwell, Kathryn P.; Powell, Kipton J.; Downard, Alison J.

    2008-01-01

    The diffusive gradients in thin films (DGT) technique, utilizing an iron-hydroxide adsorbent, has been investigated for the in situ accumulation of total dissolved inorganic As in natural waters. Diffusion coefficients of the inorganic As V and As III species in the polyacrylamide gel were measured using a diffusion cell and DGT devices and a variety of factors that may affect the adsorption of the As species to the iron-hydroxide adsorbent, or the diffusion of the individual As species, were investigated. Under conditions commonly encountered in environmental samples, solution pH and the presence of anions, cations, fulvic acid, Fe III -fulvic acid complexes and colloidal iron-hydroxide were demonstrated not to affect uptake of dissolved As. To evaluate DGT as a method for accumulation and pre-concentration of total dissolved inorganic As in natural waters, DGT was applied to two well waters and a river water that was spiked with As. For each sample, the concentration obtained with use of DGT followed by measurement by hydride generation atomic absorption spectrometry with a Pd modifier (HG-AAS) was compared with the concentration of As measured directly by HG-AAS. The results confirmed that DGT is a reliable method for pre-concentration of total dissolved As

  2. Total dissolved atmospheric nitrogen deposition in the anoxic Cariaco basin

    Science.gov (United States)

    Rasse, R.; Pérez, T.; Giuliante, A.; Donoso, L.

    2018-04-01

    Atmospheric deposition of total dissolved nitrogen (TDN) is an important source of nitrogen for ocean primary productivity that has increased since the industrial revolution. Thus, understanding its role in the ocean nitrogen cycle will help assess recent changes in ocean biogeochemistry. In the anoxic Cariaco basin, the place of the CARIACO Ocean Time-Series Program, the influence of atmospherically-deposited TDN on marine biogeochemistry is unknown. In this study, we measured atmospheric TDN concentrations as dissolved organic (DON) and inorganic (DIN) nitrogen (TDN = DIN + DON) in atmospheric suspended particles and wet deposition samples at the northeast of the basin during periods of the wet (August-September 2008) and dry (March-April 2009) seasons. We evaluated the potential anthropogenic N influences by measuring wind velocity and direction, size-fractionated suspended particles, chemical traces and by performing back trajectories. We found DIN and DON concentration values that ranged between 0.11 and 0.58 μg-N m-3 and 0.11-0.56 μg-N m-3 in total suspended particles samples and between 0.08 and 0.54 mg-N l-1 and 0.02-1.3 mg-N l-1 in wet deposition samples, respectively. Continental air masses increased DON and DIN concentrations in atmospheric suspended particles during the wet season. We estimate an annual TDN atmospheric deposition (wet + particles) of 3.6 × 103 ton-N year-1 and concluded that: 1) Atmospheric supply of TDN plays a key role in the C and N budget of the basin because replaces a fraction of the C (20% by induced primary production) and N (40%) removed by sediment burial, 2) present anthropogenic N could contribute to 30% of TDN atmospheric deposition in the basin, and 3) reduced DON (gas + particles) should be a significant component of bulk N deposition.

  3. Removal of two polycyclic musks in sewage treatment plants: Freely dissolved and total concentrations

    NARCIS (Netherlands)

    Artola-Garicano, E.; Borkent, I.; Hermens, J.L.M.; Vaes, W.H.J.

    2003-01-01

    In the current study, the removal of slowly degradable hydrophobic chemicals in sewage treatment plants (STPs) has been evaluated with emphasis on the combination of free and total concentration data. Free and total concentrations of two polycyclic musks were determined in each compartment of four

  4. DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS

    Energy Technology Data Exchange (ETDEWEB)

    P. Bernot

    2005-07-13

    The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of elements with radioactive isotopes under probable repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, field measurements, and laboratory experiments. The scope of this activity is to predict dissolved concentrations or solubility limits for elements with radioactive isotopes (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium) relevant to calculated dose. Model outputs for uranium, plutonium, neptunium, thorium, americium, and protactinium are provided in the form of tabulated functions with pH and log fCO{sub 2} as independent variables, plus one or more uncertainty terms. The solubility limits for the remaining elements are either in the form of distributions or single values. Even though selection of an appropriate set of radionuclides documented in Radionuclide Screening (BSC 2002 [DIRS 160059]) includes actinium, transport of Ac is not modeled in the total system performance assessment for the license application (TSPA-LA) model because of its extremely short half-life. Actinium dose is calculated in the TSPA-LA by assuming secular equilibrium with {sup 231}Pa (Section 6.10); therefore, Ac is not analyzed in this report. The output data from this report are fundamental inputs for TSPA-LA used to determine the estimated release of these elements from waste packages and the engineered barrier system. Consistent modeling approaches and environmental conditions were used to develop solubility models for the actinides discussed in this report. These models cover broad ranges of environmental conditions so they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, and activity coefficients have been quantified or

  5. DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS

    International Nuclear Information System (INIS)

    P. Bernot

    2005-01-01

    The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of elements with radioactive isotopes under probable repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, field measurements, and laboratory experiments. The scope of this activity is to predict dissolved concentrations or solubility limits for elements with radioactive isotopes (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium) relevant to calculated dose. Model outputs for uranium, plutonium, neptunium, thorium, americium, and protactinium are provided in the form of tabulated functions with pH and log fCO 2 as independent variables, plus one or more uncertainty terms. The solubility limits for the remaining elements are either in the form of distributions or single values. Even though selection of an appropriate set of radionuclides documented in Radionuclide Screening (BSC 2002 [DIRS 160059]) includes actinium, transport of Ac is not modeled in the total system performance assessment for the license application (TSPA-LA) model because of its extremely short half-life. Actinium dose is calculated in the TSPA-LA by assuming secular equilibrium with 231 Pa (Section 6.10); therefore, Ac is not analyzed in this report. The output data from this report are fundamental inputs for TSPA-LA used to determine the estimated release of these elements from waste packages and the engineered barrier system. Consistent modeling approaches and environmental conditions were used to develop solubility models for the actinides discussed in this report. These models cover broad ranges of environmental conditions so they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, and activity coefficients have been quantified or otherwise

  6. Linking CDOM spectral absorption to dissolved organic carbon concentrations and loadings in boreal estuaries

    DEFF Research Database (Denmark)

    Asmala, Eero; Stedmon, Colin A.; Thomas, David N.

    2012-01-01

    concentrations across the salinity gradient and ranged from 1.67 to 33.4 m−1. The link between DOC and CDOM was studied using a range of wavelengths and algorithms. Wavelengths between 250 and 270 nm gave the best predictions with single linear regression. Total dissolved iron was found to influence......The quantity of chromophoric dissolved organic matter (CDOM) and dissolved organic carbon (DOC) in three Finnish estuaries (Karjaanjoki, Kyrönjoki and Kiiminkijoki) was investigated, with respect to predicting DOC concentrations and loadings from spectral CDOM absorption measurements. Altogether 87...... the prediction in wavelengths above 520nm. Despite significant seasonal and spatial differences in DOC–CDOM models, a universal relationship was tested with an independent data set and found to be robust. DOC and CDOM yields (loading/catchment area) from the catchments ranged from 1.98 to 5.44gCm−2yr−1, and 1...

  7. Importance of Dissolved Neutral Hg-Sulfides, Energy Rich Organic Matter and total Hg Concentrations for Methyl Mercury Production in Sediments

    Science.gov (United States)

    Drott, A.; Skyllberg, U.

    2007-12-01

    brackish waters (palgae and bacteria) in the sediment and a high annual temperature sum, resulted in high methylation rates. In conclusion, concentrations of neutral Hg-sulfides and availability of energy rich organic matter, but also total Hg concentrations in sediments are important factors behind net production and accumulation of MeHg . References: (1) Drott et. al. submitted, (2) Drott, A.; Lambertsson, L.; Björn, E.; Skyllberg, U. Importance of dissolved neutral mercury sulfides for methyl mercury production in contaminated sediments. Environmental Science & Technology 2007, 41, 2270-2276.

  8. Effects of dissolved organic matter from a eutrophic lake on the freely dissolved concentrations of emerging organic contaminants.

    Science.gov (United States)

    Xiao, Yi-Hua; Huang, Qing-Hui; Vähätalo, Anssi V; Li, Fei-Peng; Chen, Ling

    2014-08-01

    The authors studied the effects of dissolved organic matter (DOM) on the bioavailability of bisphenol A (BPA) and chloramphenicol by measuring the freely dissolved concentrations of the contaminants in solutions containing DOM that had been isolated from a mesocosm in a eutrophic lake. The abundance and aromaticity of the chromophoric DOM increased over the 25-d mesocosm experiment. The BPA freely dissolved concentration was 72.3% lower and the chloramphenicol freely dissolved concentration was 56.2% lower using DOM collected on day 25 than using DOM collected on day 1 of the mesocosm experiment. The freely dissolved concentrations negatively correlated with the ultraviolent absorption coefficient at 254 nm and positively correlated with the spectral slope of chromophoric DOM, suggesting that the bioavailability of these emerging organic contaminants depends on the characteristics of the DOM present. The DOM-water partition coefficients (log KOC ) for the emerging organic contaminants positively correlated with the aromaticity of the DOM, measured as humic acid-like fluorescent components C1 (excitation/emission=250[313]/412 nm) and C2 (excitation/emission=268[379]/456 nm). The authors conclude that the bioavailability of emerging organic contaminants in eutrophic lakes can be affected by changes in the DOM. © 2014 SETAC.

  9. Geographical differences in the relationship between total dissolved ...

    African Journals Online (AJOL)

    on the Department of Water Affairs water quality database. ... Keywords: conversion factors, electrical conductivity, field instruments, rivers, total dissolved solids, water quality ... of a number of TDS:EC ratios in samples where both measure-.

  10. Bulk metal concentrations versus total suspended solids in rivers: Time-invariant & catchment-specific relationships.

    Science.gov (United States)

    Nasrabadi, Touraj; Ruegner, Hermann; Schwientek, Marc; Bennett, Jeremy; Fazel Valipour, Shahin; Grathwohl, Peter

    2018-01-01

    Suspended particles in rivers can act as carriers of potentially bioavailable metal species and are thus an emerging area of interest in river system monitoring. The delineation of bulk metals concentrations in river water into dissolved and particulate components is also important for risk assessment. Linear relationships between bulk metal concentrations in water (CW,tot) and total suspended solids (TSS) in water can be used to easily evaluate dissolved (CW, intercept) and particle-bound metal fluxes (CSUS, slope) in streams (CW,tot = CW + CSUS TSS). In this study, we apply this principle to catchments in Iran (Haraz) and Germany (Ammer, Goldersbach, and Steinlach) that show differences in geology, geochemistry, land use and hydrological characteristics. For each catchment, particle-bound and dissolved concentrations for a suite of metals in water were calculated based on linear regressions of total suspended solids and total metal concentrations. Results were replicable across sampling campaigns in different years and seasons (between 2013 and 2016) and could be reproduced in a laboratory sedimentation experiment. CSUS values generally showed little variability in different catchments and agree well with soil background values for some metals (e.g. lead and nickel) while other metals (e.g. copper) indicate anthropogenic influences. CW was elevated in the Haraz (Iran) catchment, indicating higher bioavailability and potential human and ecological health concerns (where higher values of CSUS/CW are considered as a risk indicator).

  11. Dissolved gas concentrations of the geothermal fluids in Taiwan

    Science.gov (United States)

    Chen, Ai-Ti; Yang, Tsanyao Frank

    2010-05-01

    Taiwan, a geologically active island, is located on the boundary of the Philippine Sea Plate and the Eurasian Plate. High heat flow and geothermal gradient generated by the complex collision and orogeny, warm up the meteoric water and/or the ground water. The heated water becomes geothermal fluids. In previous studies, researchers tried to categorize hot springs based on the appearance, chemical compositions and lithological areas. Because of the chemical inertness, the concentrations and isotopic composition of dissolved noble gases are good indicators of the mantle degassing, geothermal conditions, and so on. In this study, 55 hot springs were collected from different tectonic units. It is the first time to systematically study the hot springs in Taiwan in terms of dissolved gases. Hot spring water is sampled and stored in pre-evacuated glass bottles for analyzing gas compositions. The abundances of noble gases were determined by a quadrupole mass spectrometer based on the isotope dilution technique. Samples with glass vials are introduced to RAD 7 and GC for dissolved Rn and major dissolved gases analyses. Furthermore, helium isotopic ratios and helium-neon ratios are measured on a conventional noble gas mass spectrometer. For hydrochemistry analysis, water samples are analyzed by IC, ICP-MS and titration. We can classify the hot springs samples into three major groups from main anion concentration data; and then, subdivide them into nine minor groups by cation concentration data. Moreover, according to major dissolved gases compositions, three major gas components: CH4, N2 and CO2, are identified. Dissolved noble gases provided more detailed clues about hot springs sources in Taiwan, such as the degree of mixing between meteoric water and deep-source water, which will be further discussed in this study.

  12. Seasonal variations of total 234Th and dissolved 238U concentration activities in surface water of Bransfield Strait, Antarctica, from March to October 2011

    International Nuclear Information System (INIS)

    Lapa, Flavia V.; Oliveira, Joselene de; Costa, Alice M.R.; Braga, Elisabete S.

    2013-01-01

    In this study the naturally occurring radionuclides 234 Th and 238 U were used to investigate the magnitude of upper ocean particulate organic carbon export in Bransfield Strait, Southern Ocean. This region is the largest oceanic high-nitrate low-chlorophyll (HNLC) area in the world and is known to contribute to regulate of the atmospheric CO 2 via the biological pump. Due to its different geochemical behavior in seawater, the resulting U/Th disequilibria can be easily used to constrain the transport rates of particles and reaction processes between solution and particulate phases. Sampling occurred during the summer (March and November) 2011. Total 234 Th activities in surface seawater samples ranged from 1.3 to 3.7 dpm L -1 (station EB 011) during March/11 campaign, while in October/11 total 234 Th activity concentrations varied from 1.4 to 2.9 dpm L -1 . Highest total 234 Th activities were found late in the austral summer season. Activity concentrations of dissolved 238 U in surface seawater varied from 2.1 to 2.4 dpm L -1 . Taking into account all sampling stations established in March and October/11 the relative variability of total 234 Th distribution was 22%. (author)

  13. Linking CDOM spectral absorption to dissolved organic carbon concentrations and loadings in boreal estuaries

    Science.gov (United States)

    Asmala, Eero; Stedmon, Colin A.; Thomas, David N.

    2012-10-01

    The quantity of chromophoric dissolved organic matter (CDOM) and dissolved organic carbon (DOC) in three Finnish estuaries (Karjaanjoki, Kyrönjoki and Kiiminkijoki) was investigated, with respect to predicting DOC concentrations and loadings from spectral CDOM absorption measurements. Altogether 87 samples were collected from three estuarine transects which were studied in three seasons, covering a salinity range between 0 and 6.8, and DOC concentrations from 1572 μmol l-1 in freshwater to 222 μmol l-1 in coastal waters. CDOM absorption coefficient, aCDOM(375) values followed the trend in DOC concentrations across the salinity gradient and ranged from 1.67 to 33.4 m-1. The link between DOC and CDOM was studied using a range of wavelengths and algorithms. Wavelengths between 250 and 270 nm gave the best predictions with single linear regression. Total dissolved iron was found to influence the prediction in wavelengths above 520 nm. Despite significant seasonal and spatial differences in DOC-CDOM models, a universal relationship was tested with an independent data set and found to be robust. DOC and CDOM yields (loading/catchment area) from the catchments ranged from 1.98 to 5.44 g C m-2 yr-1, and 1.67 to 11.5 aCDOM(375) yr-1, respectively.

  14. Riverine dissolved carbon concentration and yield in subtropical catchments, Taiwan

    Science.gov (United States)

    Chen, Pei-Hao; Shih, Yu-ting; Huang, -Chuan, Jr.

    2017-04-01

    Dissolved carbon is not highly correlated to carbon cycle, but also a critical water quality indicator and affected by interaction of terrestrial and aquatic environment at catchment scale. However, the rates and extent of the dissolved carbon export are still poorly understood and scarcely quantified especially for typhoon events. In this study, regular and events' data of riverine dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) were monitored to estimate the export. Meanwhile, the hydrological model and mixing model were used for determination of DOC and DIC flow pathways at 3 sites of Tsengwen reservoir in southern Taiwan in 2014-2015. Results showed that the mean DOC concentration was 1.5 - 2.2 mg l-1 (flow weighted) without seasonal variation. The average DOC yield was 3.1 ton-C km-2 yr-1. On the other hand, DIC concentration ranged from 15 to 25.8 mg l-1, but DIC concentration in dry season was higher than wet season. Mean annual DIC yield was 51 ton-C km-2 yr-1. The export-ratio of DOC:DIC was 1:16.5, which was extremely lower than that of worldwide large rivers (DOC:DIC=1:4.5 in average) and other mountainous rivers (DOC:DIC=1:4.6 in average). Both DOC and DIC concentration showed the dramatically discrepant change in typhoon events. The DOC concentration increased to 4-8 folds rapidly before the flood peak. However, DIC concentration was diluted to one third with discharge simultaneously and returned slowly to base concentration in more than a week. According to the hydrological model, events contributed 14.6% of the annual discharge and 21.9% and 11.1% of DOC and DIC annual flux, respectively. Furthermore, 68.9% of events' discharge derived from surface runoff which carried out 91.3% of DOC flux and 51.1% of DIC flux. It implied that increases of surface runoff transported DOC form near soil surface, but diluted DIC concentration likely implied the contribution of groundwater. Our study characterized the specialty of dissolved carbon

  15. Reducing surface water total and methyl mercury concentrations and bioavailability using a coagulation-wetland system

    Science.gov (United States)

    Kraus, T. E.; Fleck, J.; Henneberry, Y. K.; Stumpner, E. B.; Krabbenhoft, D. P.; Bachand, P.; Randall, P.

    2013-12-01

    With the recent passage of laws regulating concentrations and loads of mercury (Hg) in surface waters, there is a need to develop management practices that will reduce the export of Hg from both point and non-point sources. Coagulation with metal based salts to remove particles and dissolved organic matter (DOM) from solution is a practice commonly employed by drinking water utilities. Because dissolved Hg is associated with particles and DOM, it follows that Hg should also be removed during the coagulation process and end up associated with the organo-metal precipitate, termed flocculate (floc). The effectiveness of iron- and aluminum-based coagulants for removing both inorganic and methyl mercury (IHg and MeHg, respectively) from solution was demonstrated in laboratory studies conducted on agricultural drainage waters of the Sacramento-San Joaquin Delta: dissolved concentrations of MeHg decreased by 80% while IHg decreased by 97% following coagulation. To test the field application of this technology, samples were collected from the inflows and outflows of wetland treatment cells constructed in the central Delta of California. This replicated field experiment includes three replicates each of three inflow waters treatments: (1) iron sulfate addition, (2) polyaluminum chloride addition, and (3) untreated controls. Water entering and exiting the nine treatment cells was sampled approximately monthly over a 1-year period for total Hg and MeHg in both the dissolved and particulate aqueous phases. Initial results confirm that coagulant addition is removing Hg (total and methyl, particulate and dissolved) from solution and sequestering it in the floc. Seasonal effects on DOM concentration and other factors appear to effect whether passage through the wetland cells alters surface water dissolved organic carbon (DOC) and Hg concentrations. Related studies will examine whether the presence of the floc affects the production and fate of MeHg within the wetland cells. If

  16. Geographical differences in the relationship between total dissolved ...

    African Journals Online (AJOL)

    The practical application of these findings is that users of EC meters should not simply apply a blanket conversion factor, but need to select an applicable factor for the river system in which they are measuring. Keywords: conversion factors, electrical conductivity, field instruments, rivers, total dissolved solids, water quality ...

  17. Predicting dissolved lignin phenol concentrations in the coastal ocean from chromophoric dissolved organic matter (CDOM absorption coefficients

    Directory of Open Access Journals (Sweden)

    Cédric G. Fichot

    2016-02-01

    Full Text Available Dissolved lignin is a well-established biomarker of terrigenous dissolved organic matter (DOM in the ocean, and a chromophoric component of DOM. Although evidence suggests there is a strong linkage between lignin concentrations and chromophoric DOM (CDOM absorption coefficients in coastal waters, the characteristics of this linkage and the existence of a relationship that is applicable across coastal oceans remain unclear. Here, 421 paired measurements of dissolved lignin concentrations (sum of 9 lignin phenols and CDOM absorption coefficients (ag(λ were used to examine their relationship along the river-ocean continuum (0-37 salinity and across contrasting coastal oceans (sub-tropical, temperate, high-latitude. Overall, lignin concentrations spanned four orders of magnitude and revealed a strong, non-linear relationship with ag(λ. The characteristics of the relationship (shape, wavelength dependency, lignin-composition dependency and evidence from degradation indicators were all consistent with lignin being an important driver of CDOM variability in coastal oceans, and suggested physical mixing and long-term photodegradation were important in shaping the relationship. These observations were used to develop two simple empirical models for estimating lignin concentrations from ag(λ with a +/- 20% error relative to measured values. The models are expected to be applicable in most coastal oceans influenced by terrigenous inputs.

  18. Bubble growth as a means to measure dissolved nitrogen concentration in aerated water

    Science.gov (United States)

    Ando, Keita; Yamashita, Tatsuya

    2017-11-01

    Controlling the amount of dissolved gases in water is important, for example, to food processing; it is essential to quantitatively evaluate dissolved gas concentration. The concentration of dissolved oxygen (DO) can be measured by commercial DO meters, but that of dissolved nitrogen (DN) cannot be obtained easily. Here, we propose a means to measure DN concentration based on Epstein-Plesset-type analysis of bubble growth under dissolved gas supersaturation. DO supersaturation in water is produced by oxygen microbubble aeration. The diffusion-driven growth of bubbles nucleated at glass surfaces in contact with the aerated water is first observed. The observed growth is then compared to the extended Epstein-Plesset theory that considers Fick's mass transfer of both DO and DN across bubble interfaces; in this comparison, the unknown DN concentration is treated as a fitting parameter. Comparisons between the experiment and the theory suggest, as expected, that DN can be effectively purged by oxygen microbubble aeration. This study was supported in part by the Mizuho Foundation for the Promotion of Science and by a MEXT Grant-in-Aid for the Program for Leading Graduate Schools.

  19. Seasonal variations of total {sup 234}Th and dissolved {sup 238}U concentration activities in surface water of Bransfield Strait, Antarctica, from March to October 2011

    Energy Technology Data Exchange (ETDEWEB)

    Lapa, Flavia V.; Oliveira, Joselene de; Costa, Alice M.R., E-mail: fvlapa@ipen.br, E-mail: jolivei@ipen.br, E-mail: lice_mrc@hotmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil). Laboratorio de Radiometria Ambiental; Braga, Elisabete S., E-mail: edsbraga@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Inst. Oceanografico. Lab. de Nutrientes, Micronutrientes e Tracos nos Oceanos

    2013-07-01

    In this study the naturally occurring radionuclides {sup 234}Th and {sup 238}U were used to investigate the magnitude of upper ocean particulate organic carbon export in Bransfield Strait, Southern Ocean. This region is the largest oceanic high-nitrate low-chlorophyll (HNLC) area in the world and is known to contribute to regulate of the atmospheric CO{sub 2} via the biological pump. Due to its different geochemical behavior in seawater, the resulting U/Th disequilibria can be easily used to constrain the transport rates of particles and reaction processes between solution and particulate phases. Sampling occurred during the summer (March and November) 2011. Total {sup 234}Th activities in surface seawater samples ranged from 1.3 to 3.7 dpm L{sup -1} (station EB 011) during March/11 campaign, while in October/11 total {sup 234}Th activity concentrations varied from 1.4 to 2.9 dpm L{sup -1}. Highest total {sup 234}Th activities were found late in the austral summer season. Activity concentrations of dissolved {sup 238}U in surface seawater varied from 2.1 to 2.4 dpm L{sup -1}. Taking into account all sampling stations established in March and October/11 the relative variability of total {sup 234}Th distribution was 22%. (author)

  20. Total dissolved gas, barometric pressure, and water temperature data, lower Columbia River, Oregon and Washington, 1996

    Science.gov (United States)

    Tanner, Dwight Q.; Harrison, Howard E.; McKenzie, Stuart W.

    1996-01-01

    Increased levels of total dissolved gas pressure can cause gas-bubble trauma in fish downstream from dams on the Columbia River. In cooperation with the U.S. Army Corps of Engineers, the U.S. Geological Survey collected data on total dissolved gas pressure, barometric pressure, water temperature, and dissolved oxygen pressure at 11 stations on the lower Columbia River from the John Day forebay (river mile 215.6) to Wauna Mill (river mile 41.9) from March to September 1996. Methods of data collection, review, and processing are described in this report. Summaries of daily minimum, maximum, and mean hourly values are presented for total dissolved gas pressure, barometric pressure, and water temperature. Hourly values for these parameters are presented graphically. Dissolved oxygen data are not presented in this report because the quality-control data show that the data have poor precision and high bias. Suggested changes to monitoring procedures for future studies include (1) improved calibration procedures for total dissolved gas and dissolved oxygen to better define accuracy at elevated levels of supersaturation and (2) equipping dissolved oxygen sensors with stirrers because river velocities at the shoreline monitoring stations probably cannot maintain an adequate flow of water across the membrane surface of the dissolved oxygen sensor.

  1. Bench-Scale and Pilot-Scale Treatment Technologies for the Removal of Total Dissolved Solids from Coal Mine Water: A Review

    Science.gov (United States)

    Coal mine water (CMW) is typically treated to remove suspended solids, acidity, and soluble metals, but high concentrations of total dissolved solids (TDS) have been reported to impact the environment at several CMW discharge points. Consequently, various states have establishe...

  2. Dissolved Platinum Concentrations in Coastal Seawater: Boso to Sanriku Areas, Japan.

    Science.gov (United States)

    Mashio, Asami Suzuki; Obata, Hajime; Gamo, Toshitaka

    2017-08-01

    Platinum, one of the rarest elements in the earth's crust, is now widely used in a range of products, such as catalytic converters in automobiles and anticancer drugs. Increasing use and dispersal of platinum has the potential to affect aquatic environments. Platinum concentrations in open ocean seawater have been found to be very low (approximately 0.2 pmol/L); however, Pt distributions and biogeochemical cycles in coastal areas are unknown. In this study, we investigated Pt concentrations in coastal waters between the Boso and Sanriku areas, Japan, after the 2011 tsunami. We determined sub-picomolar levels of dissolved Pt using isotope-dilution Inductively coupled plasma mass spectrometry after column preconcentration with an anion exchange resin. Dissolved Pt concentrations were found to be in the range 0.20-1.5 pmol/L, with the highest concentration in bottom water of the Boso coastal area, and at stations close to Tokyo Bay. Assuming thermodynamical equilibrium, Pt was determined to be present in the form PtCl 5 (OH) 2- , even in low-oxygen coastal waters. Vertical profiles indicated Pt levels increased toward seafloors near coastal stations and were similar to those of the open ocean at trench stations. High concentrations of dissolved Pt are thought to be derived from coastal sediments.

  3. Characterization of Urban Runoff Pollution between Dissolved and Particulate Phases

    Science.gov (United States)

    Wei, Zhang; Simin, Li; Fengbing, Tang

    2013-01-01

    To develop urban stormwater management effectively, characterization of urban runoff pollution between dissolved and particulate phases was studied by 12 rainfall events monitored for five typical urban catchments. The average event mean concentration (AEMC) of runoff pollutants in different phases was evaluated. The AEMC values of runoff pollutants in different phases from urban roads were higher than the ones from urban roofs. The proportions of total dissolved solids, total dissolved nitrogen, and total dissolved phosphorus in total ones for all the catchments were 26.19%–30.91%, 83.29%–90.51%, and 61.54–68.09%, respectively. During rainfall events, the pollutant concentration at the initial stage of rainfall was high and then sharply decreased to a low value. Affected by catchments characterization and rainfall distribution, the highest concentration of road pollutants might appear in the later period of rainfall. Strong correlations were also found among runoffs pollutants in different phases. Total suspended solid could be considered as a surrogate for particulate matters in both road and roof runoff, while dissolved chemical oxygen demand could be regarded as a surrogate for dissolved matters in roof runoff. PMID:23935444

  4. Characterization of urban runoff pollution between dissolved and particulate phases.

    Science.gov (United States)

    Wei, Zhang; Simin, Li; Fengbing, Tang

    2013-01-01

    To develop urban stormwater management effectively, characterization of urban runoff pollution between dissolved and particulate phases was studied by 12 rainfall events monitored for five typical urban catchments. The average event mean concentration (AEMC) of runoff pollutants in different phases was evaluated. The AEMC values of runoff pollutants in different phases from urban roads were higher than the ones from urban roofs. The proportions of total dissolved solids, total dissolved nitrogen, and total dissolved phosphorus in total ones for all the catchments were 26.19%-30.91%, 83.29%-90.51%, and 61.54-68.09%, respectively. During rainfall events, the pollutant concentration at the initial stage of rainfall was high and then sharply decreased to a low value. Affected by catchments characterization and rainfall distribution, the highest concentration of road pollutants might appear in the later period of rainfall. Strong correlations were also found among runoffs pollutants in different phases. Total suspended solid could be considered as a surrogate for particulate matters in both road and roof runoff, while dissolved chemical oxygen demand could be regarded as a surrogate for dissolved matters in roof runoff.

  5. Decadal-scale changes in dissolved-solids concentrations in groundwater used for public supply, Salt Lake Valley, Utah

    Science.gov (United States)

    Thiros, Susan A.; Spangler, Larry

    2010-01-01

    Basin-fill aquifers are a major source of good-quality water for public supply in many areas of the southwestern United States and have undergone increasing development as populations have grown over time. During 2005, the basin-fill aquifer in Salt Lake Valley, Utah, provided approximately 75,000 acre-feet, or about 29 percent of the total amount of water used by a population of 967,000. Groundwater in the unconsolidated basin-fill deposits that make up the aquifer occurs under unconfined and confined conditions. Water in the shallow unconfined part of the groundwater system is susceptible to near-surface contamination and generally is not used as a source of drinking water. Groundwater for public supply is withdrawn from the deeper unconfined and confined parts of the system, termed the principal aquifer, because yields generally are greater and water quality is better (including lower dissolved-solids concentrations) than in the shallower parts of the system. Much of the water in the principal aquifer is derived from recharge in the adjacent Wasatch Range (mountain-block recharge). In many areas, the principal aquifer is separated from the overlying shallow aquifer by confining layers of less permeable, fine-grained sediment that inhibit the downward movement of water and any potential contaminants from the surface. Nonetheless, under certain hydrologic conditions, human-related activities can increase dissolved-solids concentrations in the principal aquifer and result in groundwater becoming unsuitable for consumption without treatment or mixing with water having lower dissolved-solids concentrations. Dissolved-solids concentrations in areas of the principal aquifer used for public supply typically are less than 500 milligrams per liter (mg/L), the U.S. Environmental Protection Agency (EPA) secondary (nonenforceable) drinking-water standard. However, substantial increases in dissolved-solids concentrations in the principal aquifer have been documented in some

  6. Mercury, monomethyl mercury, and dissolved organic carbon concentrations in surface water entering and exiting constructed wetlands treated with metal-based coagulants, Twitchell Island, California

    Science.gov (United States)

    Stumpner, Elizabeth B.; Kraus, Tamara E.C.; Fleck, Jacob A.; Hansen, Angela M.; Bachand, Sandra M.; Horwath, William R.; DeWild, John F.; Krabbenhoft, David P.; Bachand, Philip A.M.

    2015-09-02

    Coagulation with metal-based salts is a practice commonly employed by drinking-water utilities to decrease particle and dissolved organic carbon concentrations in water. In addition to decreasing dissolved organic carbon concentrations, the effectiveness of iron- and aluminum-based coagulants for decreasing dissolved concentrations both of inorganic and monomethyl mercury in water was demonstrated in laboratory studies that used agricultural drainage water from the Sacramento–San Joaquin Delta of California. To test the effectiveness of this approach at the field scale, nine 15-by-40‑meter wetland cells were constructed on Twitchell Island that received untreated water from island drainage canals (control) or drainage water treated with polyaluminum chloride or ferric sulfate coagulants. Surface-water samples were collected approximately monthly during November 2012–September 2013 from the inlets and outlets of the wetland cells and then analyzed by the U.S. Geological Survey for total concentrations of mercury and monomethyl mercury in filtered (less than 0.3 micrometers) and suspended-particulate fractions and for concentrations of dissolved organic carbon.

  7. Concentration and characterization of dissolved organic matter in the surface microlayer and subsurface water of the Bohai Sea, China

    Science.gov (United States)

    Chen, Yan; Yang, Gui-Peng; Wu, Guan-Wei; Gao, Xian-Chi; Xia, Qing-Yan

    2013-01-01

    A total of 19 sea-surface microlayer and corresponding subsurface samples collected from the Bohai Sea, China in April 2010 were analyzed for chlorophyll a, dissolved organic carbon (DOC) and its major compound classes including total dissolved carbohydrates (TDCHO, including monosaccharides, MCHO, and polysaccharides, PCHO) and total hydrolysable amino acids (THAA, including dissolved free, DFAA, and combined fraction, DCAA). The concentrations of DOC in the subsurface water ranged from 130.2 to 407.7 μM C, with an average of 225.9±75.4 μM C, while those in the surface microlayer varied between 140.1 and 330.9 μM C, with an average of 217.8±56.8 μM C. The concentrations of chlorophyll a, DOC, TDCHO and THAA in the microlayer were, respectively correlated with their subsurface water concentrations, implying that there was a strong exchange effect between the microlayer and subsurface water. The concentrations of DOC and TDCHO were negatively correlated with salinity, respectively, indicating that water mixing might play an important role in controlling the distribution of DOC and TDCHO in the water column. Major constituents of DCAA and DFAA present in the study area were glycine, alanine, glutamic acid, serine and histidine. Principal component analysis (PCA) was applied to examine the complex compositional differences that existed among the sampling sites. Our results showed that DFAA had higher mole percentages of glycine, valine and serine in the microlayer than in the subsurface water, while DCAA tended to have higher mole percentages of glutamic acid, aspartic acid, threonine, arginine, alanine, tyrosine, phenylalanine and leucine in the microlayer. The yields of TDCHO and THAA exhibited similar trends between the microlayer and subsurface water. Carbohydrate species displayed significant enrichment in the microlayer, whereas the DFAA and DCAA exhibited non-uniform enrichment in the microlayer.

  8. The dynamics of dissolved oxygen concentration for water quality monitoring and assessment in polder ditches

    NARCIS (Netherlands)

    Veeningen, R.

    1983-01-01

    This study deals with the use of the dynamics of dissolved oxygen concentration for water quality assessment in polder ditches. The dynamics of the dissolved oxygen concentration, i.e. the temporal and spatial variations in a few polder ditches under a range of natural, pollution and management

  9. Characterization and biotoxicity assessment of dissolved organic matter in RO concentrate from a municipal wastewater reclamation reverse osmosis system.

    Science.gov (United States)

    Sun, Ying-Xue; Gao, Yue; Hu, Hong-Ying; Tang, Fang; Yang, Zhe

    2014-12-01

    Reverse osmosis (RO) concentrate from municipal wastewater reclamation reverse osmosis (mWRRO) system containing organic compounds may associate with toxic risk, and its discharge might pose an environmental risk. To identify a basis for the selection of feasible technology in treating RO concentrates, the characteristics and biotoxicity of different fractions of dissolved organic matter (DOM) in RO concentrates from an mWRRO system were investigated. The results indicated that the hydrophilic neutrals (HIN), hydrophobic acids (HOA) and hydrophobic bases (HOB) accounted for 96% of the dissolved organic carbon (DOC) of the total DOM in the RO concentrate. According to the SEC chromatograph detected at 254 nm wavelength of UV, the DOM with molecular weight (MW) 1-3 kDa accounted for the majority of the basic and neutral fractions. The fluorescence spectra of the excitation emission matrix (EEM) indicated that most aromatic proteins, humic/fulvic acid-like and soluble microbial by-product-like substances existed in the fractions HOA and hydrophobic neutrals (HON). The genotoxicity and anti-estrogenic activity of the RO concentrate were 1795.6 ± 57.2 μg 4-NQOL(-1) and 2.19 ± 0.05 mg TAM L(-1), respectively. The HIN, HOA, and HOB contributed to the genotoxicity of the RO concentrate, and the HIN was with the highest genotoxic level of 1007.9 ± 94.8 μg 4-NQOL(-1). The HOA, HON, and HIN lead to the total anti-estrogenic activity of the RO concentrate, and HOA occupied approximately 60% of the total, which was 1.3 ± 0.17 mg TAM L(-1). Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Influence of the dissolved oxygen concentration on the penicillin biosynthetic pathway in steady-state cultures of Penicillium chrysogenum

    DEFF Research Database (Denmark)

    Henriksen, Claus Maxel; Nielsen, Jens Bredal; Villadsen, John

    1997-01-01

    The influence the of dissolved oxygen concentration on penicillin biosynthesis was studied in steady-state continuous cultures of a high-yielding strain of Penicillium chrysogenum operated at a dilution rate of 0.05 h-l. The dissolved oxygen concentration was varied between 0.019 and 0.344 m...... penicillin productivity decreases, and a value of 17 (mu mol/g of DW)/h was obtained when the dissolved oxygen concentration was 0.042 mM. A further lowering of the dissolved oxygen concentration to 0.019 mM resulted in the loss of penicillin production. However, penicillin productivity was instantly...

  11. Effect of TCE concentration and dissolved groundwater solutes on NZVI-promoted TCE dechlorination and H2 evolution.

    Science.gov (United States)

    Liu, Yueqiang; Phenrat, Tanapon; Lowry, Gregory V

    2007-11-15

    Nanoscale zero-valent iron (NZVI) is used to remediate contaminated groundwater plumes and contaminant source zones. The target contaminant concentration and groundwater solutes (NO3-, Cl-, HCO3-, SO4(2-), and HPO4(2-)) should affect the NZVI longevity and reactivity with target contaminants, but these effects are not well understood. This study evaluates the effect of trichloroethylene (TCE) concentration and common dissolved groundwater solutes on the rates of NZVI-promoted TCE dechlorination and H2 evolution in batch reactors. Both model systems and real groundwater are evaluated. The TCE reaction rate constant was unaffected by TCE concentration for [TCE] TCE concentration up to water saturation (8.4 mM). For [TCE] > or = 0.46 mM, acetylene formation increased, and the total amount of H2 evolved at the end of the particle reactive lifetime decreased with increasing [TCE], indicating a higher Fe0 utilization efficiency for TCE dechlorination. Common groundwater anions (5mN) had a minor effect on H2 evolution but inhibited TCE reduction up to 7-fold in increasing order of Cl- TCE reduction but increased acetylene production and decreased H2 evolution. NO3- present at > 3 mM slowed TCE dechlorination due to surface passivation. NO3- present at 5 mM stopped TCE dechlorination and H2 evolution after 3 days. Dissolved solutes accounted for the observed decrease of NZVI reactivity for TCE dechlorination in natural groundwater when the total organic content was small (< 1 mg/L).

  12. Distribution of dissolved carbohydrates and uronic acids in a tropical estuary, India

    Digital Repository Service at National Institute of Oceanography (India)

    Khodse, V.B.; Bhosle, N.B.; Matondkar, S.G.P.

    , concentrations of total dissolved carbohydrate (TCHO), dissolved polysaccharide (PCHO), dissolved monosaccharide (MCHO), and dissolved uronic acid (URA) were measured in the Mandovi estuary, west coast of India during the monsoon and premonsoon seasons...

  13. Time series models for prediction the total and dissolved heavy metals concentration in road runoff and soil solution of roadside embankments

    Science.gov (United States)

    Aljoumani, Basem; Kluge, Björn; sanchez, Josep; Wessolek, Gerd

    2017-04-01

    Highways and main roads are potential sources of contamination for the surrounding environment. High traffic rates result in elevated heavy metal concentrations in road runoff, soil and water seepage, which has attracted much attention in the recent past. Prediction of heavy metals transfer near the roadside into deeper soil layers are very important to prevent the groundwater pollution. This study was carried out on data of a number of lysimeters which were installed along the A115 highway (Germany) with a mean daily traffic of 90.000 vehicles per day. Three polyethylene (PE) lysimeters were installed at the A115 highway. They have the following dimensions: length 150 cm, width 100 cm, height 60 cm. The lysimeters were filled with different soil materials, which were recently used for embankment construction in Germany. With the obtained data, we will develop a time series analysis model to predict total and dissolved metal concentration in road runoff and in soil solution of the roadside embankments. The time series consisted of monthly measurements of heavy metals and was transformed to a stationary situation. Subsequently, the transformed data will be used to conduct analyses in the time domain in order to obtain the parameters of a seasonal autoregressive integrated moving average (ARIMA) model. Four phase approaches for identifying and fitting ARIMA models will be used: identification, parameter estimation, diagnostic checking, and forecasting. An automatic selection criterion, such as the Akaike information criterion, will use to enhance this flexible approach to model building

  14. Novel Apparatus for the Real-Time Quantification of Dissolved Gas Concentrations and Isotope Ratios

    Science.gov (United States)

    Gupta, M.; Leen, J.; Baer, D. S.; Owano, T. G.; Liem, J.

    2013-12-01

    Measurements of dissolved gases and their isotopic composition are critical in studying a variety of phenomena, including underwater greenhouse gas generation, air-surface exchange, and pollution migration. These studies typically involve obtaining water samples from streams, lakes, or ocean water and transporting them to a laboratory, where they are degased. The gases obtained are then generally measured using gas chromatography and isotope ratio mass spectrometry for concentrations and isotope ratios, respectively. This conventional, off-line methodology is time consuming, significantly limits the number of the samples that can be measured and thus severely inhibits detailed spatial and temporal mapping of gas concentrations and isotope ratios. In this work, we describe the development of a new membrane-based degassing device that interfaces directly to Los Gatos Research (cavity enhanced laser absorption or Off-Axis ICOS) gas analyzers (cavity enhanced laser absorption or Off-Axis ICOS analyzers) to create an autonomous system that can continuously and quickly measure concentrations and isotope ratios of dissolved gases in real time in the field. By accurately controlling the water flow rate through the membrane degasser, gas pressure on the outside of the membrane, and water pressure on the inside of the membrane, the system is able to generate precise and highly reproducible results. Moreover, by accurately measuring the gas flow rates in and out of the degasser, the gas-phase concentrations (ppm) could be converted into dissolved gas concentrations (nM). We will present detailed laboratory test data that quantifies the linearity, precision, and dynamic range of the system for the concentrations and isotope ratios of dissolved methane, carbon dioxide, and nitrous oxide. By interfacing the degassing device to a novel cavity-enhanced spectrometer (developed by LGR), preliminary data will also be presented for dissolved volatile organics (VOC) and other

  15. Control systems for the dissolved oxygen concentration in condensate- and feed-water systems in nuclear power plants

    International Nuclear Information System (INIS)

    Mikajiri, Motohiko; Hosaka, Seiichi.

    1981-01-01

    Purpose: To surely prevent the generation of corrosion products and contaminations in the systems thereby decreasing the exposure dose to operators in BWR type nuclear power plants. Constitution: Dissolved oxygen concentration in condensates is measured by a dissolved oxygen concentration meter disposed to the pipeway down stream of the condensator and the measured value is sent to an injection amount control mechanism for heater drain water. The control mechanism controls the injection amount from the injection mechanism that injection heater drain water from a feed-water heater to the liquid phase in the hot wall of the condensator. Thus, heater drawin water at high dissolved oxygen is injected to the condensates in the condensator which is de-airated and reduced with dissolved oxygen concentration, to maintain the dissolved oxygen concentration at a predetermined level, whereby stable oxide films are formed to the inner surface of the pipeways to prevent the generation of corrosion products such as rusts. (Furukawa, Y.)

  16. Dissolved organic carbon concentration controls benthic primary production: results from in situ chambers in north-temperate lakes

    Science.gov (United States)

    Godwin, Sean C.; Jones, Stuart E.; Weidel, Brian C.; Solomon, Christopher T.

    2014-01-01

    We evaluated several potential drivers of primary production by benthic algae (periphyton) in north-temperate lakes. We used continuous dissolved oxygen measurements from in situ benthic chambers to quantify primary production by periphyton at multiple depths across 11 lakes encompassing a broad range of dissolved organic carbon (DOC) and total phosphorous (TP) concentrations. Light-use efficiency (primary production per unit incident light) was inversely related to average light availability (% of surface light) in 7 of the 11 study lakes, indicating that benthic algal assemblages exhibit photoadaptation, likely through physiological or compositional changes. DOC alone explained 86% of the variability in log-transformed whole-lake benthic production rates. TP was not an important driver of benthic production via its effects on nutrient and light availability. This result is contrary to studies in other systems, but may be common in relatively pristine north-temperate lakes. Our simple empirical model may allow for the prediction of whole-lake benthic primary production from easily obtained measurements of DOC concentration.

  17. Dissolved-solids sources, loads, yields, and concentrations in streams of the conterminous United States

    Science.gov (United States)

    Anning, David W.; Flynn, Marilyn E.

    2014-01-01

    Recent studies have shown that excessive dissolved-solids concentrations in water can have adverse effects on the environment and on agricultural, domestic, municipal, and industrial water users. Such effects motivated the U.S. Geological Survey’s National Water Quality Assessment Program to develop a SPAtially-Referenced Regression on Watershed Attributes (SPARROW) model that has improved the understanding of sources, loads, yields, and concentrations of dissolved solids in streams of the conterminous United States.

  18. Concentration, flux, and trend estimates with uncertainty for nutrients, chloride, and total suspended solids in tributaries of Lake Champlain, 1990–2014

    Science.gov (United States)

    Medalie, Laura

    2016-12-20

    The U.S. Geological Survey, in cooperation with the New England Interstate Water Pollution Control Commission and the Vermont Department of Environmental Conservation, estimated daily and 9-month concentrations and fluxes of total and dissolved phosphorus, total nitrogen, chloride, and total suspended solids from 1990 (or first available date) through 2014 for 18 tributaries of Lake Champlain. Estimates of concentration and flux, provided separately in Medalie (2016), were made by using the Weighted Regressions on Time, Discharge, and Season (WRTDS) regression model and update previously published WRTDS model results with recent data. Assessment of progress towards meeting phosphorus-reduction goals outlined in the Lake Champlain management plan relies on annual estimates of phosphorus flux. The percent change in annual concentration and flux is provided for two time periods. The R package EGRETci was used to estimate the uncertainty of the trend estimate. Differences in model specification and function between this study and previous studies that used WRTDS to estimate concentration and flux using data from Lake Champlain tributaries are described. Winter data were too sparse and nonrepresentative to use for estimates of concentration and flux but were sufficient for estimating the percentage of total annual flux over the period of record. Median winter-to-annual fractions ranged between 21 percent for total suspended solids and 27 percent for dissolved phosphorus. The winter contribution was largest for all constituents from the Mettawee River and smallest from the Ausable River. For the full record (1991 through 2014 for total and dissolved phosphorus and chloride and 1993 through 2014 for nitrogen and total suspended solids), 6 tributaries had decreasing trends in concentrations of total phosphorus, and 12 had increasing trends; concentrations of dissolved phosphorus decreased in 6 and increased in 8 tributaries; fluxes of total phosphorus decreased in 5 and

  19. Role of natural dissolved organic compounds in determining the concentrations of americium in natural waters

    International Nuclear Information System (INIS)

    Nelson, D.M.; Orlandini, K.A.

    1985-01-01

    Concentrations of 241 Am, both in solution and bound to suspended particulate matter, have been measured in several North American lakes. Dissolved concentrations vary from 0.4 μBq/L to 85 μBq/L. The 241 Am in these lakes originated solely from global fallout and hence entered all lakes in the same physiocochemical form. The observed differences in solubility behavior must, therefore, be attributable to chemical and/or hydrological differences among the lakes. Concentrations of dissolved 241 Am are highly correlated with the corresponding concentrations of /sup 239, 240/Pu(III,IV), suggesting that a common factor is responsible for maintaining both in solution. The K/sub D/ values for 241 Am and /sup 239, 240/Pu(III,IV) are highly correlated with the concentrations of dissolved organic carbon (DOC) in the waters, suggesting that the common factor is the formation of soluble complexes with natural DOC for both elements. This hypothesis was tested in a series of laboratory experiments in which the DOC from several of the lakes was isolated by ultrafiltration. Plots of K/sub D/, as a function of DOC concentration, show K/sub D/ to be very high (approx.10 6 ) at low DOC concentrations. Above critical concentrations (a few mg/L DOC) the K/sub D/ values begin a progressive decrease with increasing DOC. We conclude that in most surface waters, the dissolved 241 Am concentration is regulated by an adsorption/desorption equilibrium with the sediments (and suspended solids) and the value of K/sub D/ that characterizes this equilibrium is largely determined by the concentration of natural DOC in the water. 11 refs., 3 figs., 2 tabs

  20. Water quality and processes affecting dissolved oxygen concentrations in the Blackwater River, Canaan Valley, West Virginia

    Science.gov (United States)

    Waldron, M.C.; Wiley, J.B.

    1996-01-01

    The water quality and environmental processes affecting dissolved oxygen were determined for the Blackwater River in Canaan Valley, West Virginia. Canaan Valley is oval-shaped (14 miles by 5 miles) and is located in the Allegheny Mountains at an average elevation of 3,200 feet above sea level. Tourism, population, and real estate development have increased in the past two decades. Most streams in Canaan Valley are a dilute calcium magnesium bicarbonate-type water. Streamwater typicaly was soft and low in alkalinity and dissolved solids. Maximum values for specific conductance, hardness, alkalinity, and dissolved solids occurred during low-flow periods when streamflow was at or near baseflow. Dissolved oxygen concentrations are most sensitive to processes affecting the rate of reaeration. The reaeration is affected by solubility (atmospheric pressure, water temperature, humidity, and cloud cover) and processes that determine stream turbulence (stream depth, width, velocity, and roughness). In the headwaters, photosynthetic dissolved oxygen production by benthic algae can result in supersaturated dissolved oxygen concentrations. In beaver pools, dissolved oxygen consumption from sediment oxygen demand and carbonaceous biochemical oxygen demand can result in dissolved oxygen deficits.

  1. Characterization of Urban Runoff Pollution between Dissolved and Particulate Phases

    OpenAIRE

    Wei, Zhang; Simin, Li; Fengbing, Tang

    2013-01-01

    To develop urban stormwater management effectively, characterization of urban runoff pollution between dissolved and particulate phases was studied by 12 rainfall events monitored for five typical urban catchments. The average event mean concentration (AEMC) of runoff pollutants in different phases was evaluated. The AEMC values of runoff pollutants in different phases from urban roads were higher than the ones from urban roofs. The proportions of total dissolved solids, total dissolved nitr...

  2. Correlation between conductivity and total dissolved solid in various type of water: A review

    Science.gov (United States)

    Rusydi, Anna F.

    2018-02-01

    Conductivity (EC) and total dissolved solids (TDS) are water quality parameters, which are used to describe salinity level. These two parameters are correlated and usually expressed by a simple equation: TDS = k EC (in 25 °C). The process of obtaining TDS from water sample is more complex than that of EC. Meanwhile, TDS analysis is very important because it can illustrate groundwater quality, particularly in understanding the effect of seawater intrusion better than EC analysis. These conditions make research in revealing TDS/EC ratios interesting to do. By finding the ratio value, TDS concentration can be measured easily from EC value. However, the ratio cannot be defined easily. Previous research results have found that the correlation between TDS and EC are not always linear. The ratio is not only strongly influenced by salinity contents, but also by materials contents. Furthermore, the analysis of TDS concentration from EC value can be used to give an overview of water quality. For more precision, TDS concentrations need to be analyzed using the gravimetric method in the laboratory.

  3. Mesocosm validation of the marine No Effect Concentration of dissolved copper derived from a species sensivity distribution

    NARCIS (Netherlands)

    Foekema, E.M.; Kaag, N.H.B.M.; Kramer, K.J.M.; Long, K.

    2015-01-01

    The Predicted No Effect Concentration (PNEC) for dissolved copper based on the species sensitivity distribution (SSD) of 24 marine single species tests was validated in marine mesocosms. To achieve this, the impact of actively maintained concentrations of dissolved copper on a marine benthic and

  4. Mesocosm validation of the marine No Effect Concentration of dissolved copper derived from a species sensitivity distribution.

    Science.gov (United States)

    Foekema, E M; Kaag, N H B M; Kramer, K J M; Long, K

    2015-07-15

    The Predicted No Effect Concentration (PNEC) for dissolved copper based on the species sensitivity distribution (SSD) of 24 marine single species tests was validated in marine mesocosms. To achieve this, the impact of actively maintained concentrations of dissolved copper on a marine benthic and planktonic community was studied in 18 outdoor 4.6m(3) mesocosms. Five treatment levels, ranging from 2.9 to 31μg dissolved Cu/L, were created in triplicate and maintained for 82days. Clear effects were observed on gastropod and bivalve molluscs, phytoplankton, zooplankton, sponges and sessile algae. The most sensitive biological endpoints; reproduction success of the bivalve Cerastoderma edule, copepod population development and periphyton growth were significantly affected at concentrations of 9.9μg Cu/L and higher. The No Observed Effect Concentration (NOEC) derived from this study was 5.7μg dissolved Cu/L. Taking into account the DOC concentration of the mesocosm water this NOEC is comparable to the PNEC derived from the SSD. Copyright © 2015. Published by Elsevier B.V.

  5. The role of phytoplankton in the modulation of dissolved and oyster cadmium concentrations in Deep Bay, British Columbia, Canada

    International Nuclear Information System (INIS)

    Cassis, David; Lekhi, Priyanka; Pearce, Christopher M.; Ebell, Nadene; Orians, Kristin; Maldonado, Maria T.

    2011-01-01

    We previously identified dissolved cadmium (Cd diss ) as the main source of this metal in cultured Pacific oysters, Crassostrea gigas, in Deep Bay, British Columbia, Canada (Lekhi et al., 2008). Total suspended particulate Cd (Cd part ) was not found to be a significant source of oyster Cd (Cd oys ), with Cd part > 20 μm negatively correlated with Cd oys concentration. High phytoplankton abundance in spring and summer was hypothesized to reduce Cd oys indirectly by drawing down Cd diss and increasing oyster growth. In the present study we expanded on these results by examining specifically how the phytoplankton community composition modulates both Cd diss and Cd oys concentrations in Deep Bay. Based on calculations of nutrients and Cd diss drawdown, phytoplankton accounted for approximately 90% of the overall summer reduction in Cd diss in the bay. Diatoms were the dominant phytoplankton group, being correlated negatively with Cd oys and positively with Cd part . This suggests that diatom growth mediates the transfer of Cd from the dissolved to the particulate phase, resulting in lower Cd oys . Spring blooms and sporadic harmful algal blooms may mediate a large flux of Cd part to the sediments. Thus, phytoplankton act as a sink, rather than a source, of Cd to oysters in Deep Bay and have a crucial role in the seasonality of Cd oys by reducing the concentration of Cd diss during the summer. Based on environmental variables, two descriptive models for annual Cd oys concentrations were developed using multiple linear regression. The first model (R 2 = 0.870) was created to explain the maximum variability in Cd oys concentrations throughout the year, while the second (R 2 = 0.806) was based on parameters that could be measured easily under farm conditions. Oyster age heavily affected both models, with the first model being secondarily affected by temperature and the second one being more sensitive to changes in salinity. - Highlights: → Phytoplankton and

  6. Measurement of total dissolved solids using electrical conductivity

    International Nuclear Information System (INIS)

    Ray, Vinod K.; Jat, J.R.; Reddy, G.B.; Balaji Rao, Y.; Phani Babu, C.; Kalyanakrishnan, G.

    2017-01-01

    Total dissolved solids (TDS) is an important parameter for the disposal of effluents generated during processing of different raw materials like Magnesium Di-uranate (MDU), Heat Treated Uranium Peroxide (HTUP), Sodium Di-uranate (SDU) in Uranium Extraction plant and Washed and Dried Frit (WDF) in Zirconium Extraction Plant. The present paper describes the use of electrical conductivity for determination of TDS. As electrical conductivity is matrix dependent property, matrix matched standards were prepared for determination of TDS in ammonium nitrate solution (AN) and mixture of ammonium nitrate and ammonium sulphate (AN/AS) and results were found to be in good agreement when compared with evaporation method. (author)

  7. Warming and organic matter sources impact the proportion of dissolved to total activities in marine extracellular enzymatic rates

    KAUST Repository

    Baltar, Federico

    2017-04-19

    Extracellular enzymatic activities (EEAs) are the rate-limiting step in the degradation of organic matter. Extracellular enzymes can be found associated to cells or dissolved in the surrounding water. The proportion of cell-free EEA constitutes in many marine environments more than half of the total activity. This high proportion causes an uncoupling between hydrolysis rates and the actual bacterial activity. However, we do not know what factors control the proportion of dissolved relative to total EEA, nor how this may change in the future ocean. To resolve this, we performed laboratory experiments with water from the Great Barrier Reef (Australia) to study the effects of temperature and dissolved organic matter sources on EEA and the proportion of dissolved EEA. We found that warming increases the rates of organic matter hydrolysis and reduces the proportion of dissolved relative to total EEA. This suggests a potential increase of the coupling between organic matter hydrolysis and heterotrophic activities with increasing ocean temperatures, although strongly dependent on the organic matter substrates available. Our study suggests that local differences in the organic matter composition in tropical coastal ecosystems will strongly affect the proportion of dissolved EEA in response to ocean warming.

  8. Tidally driven export of dissolved organic carbon, total mercury, and methylmercury from a mangrove-dominated estuary

    Science.gov (United States)

    Bergamaschi, B.A.; Krabbenhoft, D.P.; Aiken, G.R.; Patino, E.; Rumbold, D.G.; Orem, W.H.

    2012-01-01

    The flux of dissolved organic carbon (DOC) from mangrove swamps accounts for 10% of the global terrestrial flux of DOC to coastal oceans. Recent findings of high concentrations of mercury (Hg) and methylmercury (MeHg) in mangroves, in conjunction with the common co-occurrence of DOC and Hg species, have raised concerns that mercury fluxes may also be large. We used a novel approach to estimate export of DOC, Hg, and MeHg to coastal waters from a mangrove-dominated estuary in Everglades National Park (Florida, USA). Using in situ measurements of fluorescent dissolved organic matter as a proxy for DOC, filtered total Hg, and filtered MeHg, we estimated the DOC yield to be 180 (??12.6) g C m -2 yr -1, which is in the range of previously reported values. Although Hg and MeHg yields from tidal mangrove swamps have not been previously measured, our estimated yields of Hg species (28 ?? 4.5 ??g total Hg m -2 yr -1 and 3.1 ?? 0.4 ??g methyl Hg m -2 yr -1) were five times greater than is typically reported for terrestrial wetlands. These results indicate that in addition to the well documented contributions of DOC, tidally driven export from mangroves represents a significant potential source of Hg and MeHg to nearby coastal waters. ?? 2011 American Chemical Society.

  9. Distribution of Total Suspended Solids Concentration in a River

    Directory of Open Access Journals (Sweden)

    Ahmad Hanif Asyhar

    2012-08-01

    Full Text Available Disposal of either industrial or nonindustrial wastewater into a river has a potential to cause riverpollution. Because each load of wastewater discharged into a river contains physical, chemical, and biological parametersthat determine water quality, so that it can affect the dissolved oxygen concentration in a river. Therefore the conductedresearch was aimed to determine the pattern of pollutant dispersion in Surabaya River within the section that is closed tothe Karang Pilang Monitoring Station - Surabaya. Parameter used in this research was Total Suspended Solids (TSS. Themethod used was the finite volume method with Quadratic Upwind Interpolation Convective Kinematics (QUICK schemeby means of developing models of dispersion water pollutants in a river. The governing equation was controlled by the lawsof mass conservation, momentum conservation, and pollution transport equation. Further, these equations were solvedusing numerical calculation and followed by numerical simulation. From the numerical simulation results, it can beconcluded that the magnitude of pollutant dispersion is determined by the initial discharged TSS concentrations into theriver, however the longitudinal direction is more dominantly influenced than in lateral directions.

  10. The role of phytoplankton in the modulation of dissolved and oyster cadmium concentrations in Deep Bay, British Columbia, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Cassis, David, E-mail: dcassis@telus.net [Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC, Canada V6T 1Z3 (Canada); Lekhi, Priyanka [Department of Chemistry, University of British Columbia, Vancouver, BC, Canada V6T 1Z3 (Canada); Pearce, Christopher M. [Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC, Canada V9T 6N7 (Canada); Ebell, Nadene [Ministry of Agriculture, Nanaimo, BC, Canada V9T 6J9 (Canada); Orians, Kristin [Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC, Canada V6T 1Z3 (Canada); Department of Chemistry, University of British Columbia, Vancouver, BC, Canada V6T 1Z3 (Canada); Maldonado, Maria T. [Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC, Canada V6T 1Z3 (Canada)

    2011-09-15

    We previously identified dissolved cadmium (Cd{sub diss}) as the main source of this metal in cultured Pacific oysters, Crassostrea gigas, in Deep Bay, British Columbia, Canada (Lekhi et al., 2008). Total suspended particulate Cd (Cd{sub part}) was not found to be a significant source of oyster Cd (Cd{sub oys}), with Cd{sub part} > 20 {mu}m negatively correlated with Cd{sub oys} concentration. High phytoplankton abundance in spring and summer was hypothesized to reduce Cd{sub oys} indirectly by drawing down Cd{sub diss} and increasing oyster growth. In the present study we expanded on these results by examining specifically how the phytoplankton community composition modulates both Cd{sub diss} and Cd{sub oys} concentrations in Deep Bay. Based on calculations of nutrients and Cd{sub diss} drawdown, phytoplankton accounted for approximately 90% of the overall summer reduction in Cd{sub diss} in the bay. Diatoms were the dominant phytoplankton group, being correlated negatively with Cd{sub oys} and positively with Cd{sub part}. This suggests that diatom growth mediates the transfer of Cd from the dissolved to the particulate phase, resulting in lower Cd{sub oys}. Spring blooms and sporadic harmful algal blooms may mediate a large flux of Cd{sub part} to the sediments. Thus, phytoplankton act as a sink, rather than a source, of Cd to oysters in Deep Bay and have a crucial role in the seasonality of Cd{sub oys} by reducing the concentration of Cd{sub diss} during the summer. Based on environmental variables, two descriptive models for annual Cd{sub oys} concentrations were developed using multiple linear regression. The first model (R{sup 2} = 0.870) was created to explain the maximum variability in Cd{sub oys} concentrations throughout the year, while the second (R{sup 2} = 0.806) was based on parameters that could be measured easily under farm conditions. Oyster age heavily affected both models, with the first model being secondarily affected by temperature and the

  11. Dissolved petroleum hydrocarbon concentrations in some regions of the northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    SenGupta, R.; Qasim, S.Z.; Fondekar, S.P.; Topgi, R.S.

    Dissolved petroleum hydrocarbons were measured in some parts of the Northern Indian Ocean using UV bsorbance technique with a clean up step. The concentration of oil ranged from 0.6 to 26.5 mu gl. Higher values were recorded along the oil tanker...

  12. COMMUNITY SCALE STREAM TAXA SENSITIVITIES TO DIFFERENT COMPOSITIONS OF EXCESS TOTAL DISSOLVED SOLIDS

    Science.gov (United States)

    Model stream chronic dosing studies (42 d) were conducted with three total dissolved solids (TDS) recipes. The recipes differed in composition of major ions. Community scale emergence was compared with single-species responses conducted simultaneously using the whole effluent tox...

  13. Trends in concentrations of nitrate and total dissolved solids in public supply wells of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins, San Bernardino County, California: Influence of legacy land use

    Science.gov (United States)

    Kent, Robert; Landon, Matthew K.

    2013-01-01

    Concentrations and temporal changes in concentrations of nitrate and total dissolved solids (TDS) in groundwater of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins of the Upper Santa Ana Valley Groundwater Basin were evaluated to identify trends and factors that may be affecting trends. One hundred, thirty-one public-supply wells were selected for analysis based on the availability of data spanning at least 11 years between the late 1980s and the 2000s. Forty-one of the 131 wells (31%) had a significant (p relations of nitrate trends to depth, lateral position, and VOCs imply that increasing nitrate concentrations are associated with nitrate loading from historical agricultural land use and that more recent urban land use is generally associated with lower nitrate concentrations and greater VOC occurrence. Increasing TDS trends were associated with relatively greater current nitrate concentrations and relatively greater amounts of urban land. Decreasing TDS trends were associated with relatively greater amounts of natural land use. Trends in TDS concentrations were not related to depth, lateral position, or VOC occurrence, reflecting more complex factors affecting TDS than nitrate in the study area.

  14. The relationship of metals, bifenthrin, physical habitat metrics, grain size, total organic carbon, dissolved oxygen and conductivity to Hyalella sp. abundance in urban California streams.

    Science.gov (United States)

    Hall, Lenwood W; Anderson, Ronald D

    2013-01-01

    The objectives of this study were to determine the relationship between Hyalella sp. abundance in four urban California streams and the following parameters: (1) 8 bulk metals (As, Cd, Cr, Cu, Pb, Hg, Ni, and Zn) and their associated sediment Threshold Effect Levels (TELs); (2) bifenthrin sediment concentrations; (3) 10 habitat metrics and total score; (4) grain size (% sand, silt and clay); (5) Total Organic Carbon (TOC); (6) dissolved oxygen; and (7) conductivity. California stream data used for this study were collected from Kirker Creek (2006 and 2007), Pleasant Grove Creek (2006, 2007 and 2008), Salinas streams (2009 and 2010) and Arcade Creek (2009 and 2010). Hyalella abundance in the four California streams generally declined when metals concentrations were elevated beyond the TELs. There was also a statistically significant negative relationship between Hyalella abundance and % silt for these 4 California streams as Hyalella were generally not present in silt areas. No statistically significant relationships were reported between Hyalella abundance and metals concentrations, bifenthrin concentrations, habitat metrics, % sand, % clay, TOC, dissolved oxygen and conductivity. The results from this study highlight the complexity of assessing which factors are responsible for determining the abundance of amphipods, such as Hyalella sp., in the natural environment.

  15. Mitomycin C dissolved in a reversible thermosetting gel: target tissue concentrations in the rabbit eye.

    Science.gov (United States)

    Ichien, K; Yamamoto, T; Kitazawa, Y; Oguri, A; Ando, H; Kondo, Y

    1997-01-01

    To determine whether a new, reversible thermosetting gel enhances mitomycin C transfer to target ocular tissues in the rabbit eye. A 0.1 ml solution of mitomycin C containing 0.22 microgram, 2.9 micrograms, or 28 micrograms of the agent dissolved in a reversible thermosetting gel consisting of methylcellulose, citric acid, and polyethylene glycol was injected subconjunctivally in 30 New Zealand albino rabbits. Scleral and conjunctival tissues were excised at 0.5, 1, 2, 4, or 24 hours after the injection and mitomycin C concentrations in these tissues were determined by high performance liquid chromatography. The concentration over time was approximated to a single exponential curve, and initial mitomycin C concentrations, time constants, and half life values were determined. Finally, the areas under the curves (AUCs) between 0.5 and 24 hours were calculated. The mitomycin C concentrations in the target tissues were dose dependent and decreased rapidly over 24 hours. Both the initial mitomycin C concentrations as well as AUCs in these eyes treated with mitomycin C, dissolved in a reversible thermosetting gel, were higher than those in eyes treated similarly in a previous study in which the gel was not used. Applied subconjunctivally in the rabbit eye, mitomycin C dissolved in the reversible thermosetting gel enhanced transfer of the agent to the sclera and the conjunctiva.

  16. Evaluation of dissolved oxygen and organic substances concentrations in water of the nature reserve Alluvium Zitavy

    International Nuclear Information System (INIS)

    Palaticka, A.; Noskovic, J.; Babosova, M.

    2007-01-01

    In 2006 concentrations of dissolved oxygen and organic substances were evaluated in water in the Nature Reserve Alluvium Zitavy (indirect method based on their oxidation by K 2 Cr 2 0 7 was used). The results are represented in mg of O 2 · dm -3 . Taking of samples took place in 6 sampling sites in regular month intervals. Based on obtained data and according to the standard STN 75 7221 (Water quality -The classification of the water surface quality) water in individual sampling sites was ranked into the classes of the .water surface quality. From the data it is clear that the concentrations of dissolved oxygen and organic substances in the Nature Reserve Alluvium Zitavy changed in dependence on sampling sites and time. The highest mean concentrations of dissolved oxygen in dependence on sampling time were found out in spring months and the lowest concentrations in summer months. They ranged from 1.6 mg 0 2 · dm -3 (July) to 9.0 mg O 2 · dm -3 (March). Falling dissolved oxygen values can be related to successive increase of water temperature, thus good conditions were created for decomposition of organic matter by microorganisms in water and sediments in which they use dissolved oxygen. In dependence on sampling place the highest mean concentration of dissolved oxygen was in sampling site No. 4 (6.0 mg 0 2 · dm -3 ) which is situated in the narrowest place in the NR. The lowest value was in sampling site No. 2 (3.6 mg 0 2 · dm -3 ) which is a typical wetland ecosystem. High mean values of COD Cr in dependence on sampling time were determined in summer months and low values during winter moths. Dependence of COD Cr values on sampling site was also manifested. The lowest mean value was obtained in sampling site No. 4 (59.5 mg · dm -3 ) and the highest value in sampling site No. 5 (97.1 mg · dm -3 ) which is also a typical wetland. Based on the results and according to the STN 75 7221 we ranked water in all sampling sites into the 5 th class of the water

  17. Elevated concentrations of dissolved Ba, Fe and Mn in a mangrove subterranean estuary: Consequence of sea level rise?

    Science.gov (United States)

    Sanders, Christian J.; Santos, Isaac R.; Barcellos, Renato; Silva Filho, Emmanoel V.

    2012-07-01

    Groundwater underlying a mangrove habitat was studied to determine the geochemical nature of Ba, Fe and Mn as related to dissolved organic carbon (DOC), SO4 and salinity (Sepetiba Bay, Brazil). Wells were placed across geobotanic facies and sampled monthly for a year. We observed non-conservative behavior and elevated concentrations of dissolved metals relative to local end-members (i.e., fresh river water and seawater). Average Ba concentrations were near 2000 nM in an area with low salinity (˜5.3). Dissolved Fe (up to 654 μM) was two orders of magnitude greater in fresh groundwater than in the seaward sampling stations. Manganese concentrations were greatest (112 μM) in the high salinity (˜65) zone, being directly influenced by salinity. Groundwater Ba, Fe and Mn showed differing site specific concentrations, likely related to ion exchange processes and redox-controlled cycling along distinct mangrove facies. The results of this work show that metal concentrations are altered relative to conservative mixing between terrestrial and marine endmembers, illustrating the importance of mangrove subterranean estuaries as biogeochemical reactors. Roughly-estimated submarine groundwater discharge-derived dissolved Ba, Fe and Mn fluxes were at least one order of magnitude greater than river-derived fluxes into Sepetiba Bay.

  18. Prediction of Dissolved Gas Concentrations in Transformer Oil Based on the KPCA-FFOA-GRNN Model

    Directory of Open Access Journals (Sweden)

    Jun Lin

    2018-01-01

    Full Text Available The purpose of analyzing the dissolved gas in transformer oil is to determine the transformer’s operating status and is an important basis for fault diagnosis. Accurate prediction of the concentration of dissolved gas in oil can provide an important reference for the evaluation of the state of the transformer. A combined predicting model is proposed based on kernel principal component analysis (KPCA and a generalized regression neural network (GRNN using an improved fruit fly optimization algorithm (FFOA to select the smooth factor. Firstly, based on the idea of using the dissolved gas ratio of oil to diagnose the transformer fault, gas concentration ratios are also used as characteristic parameters. Secondly, the main parameters are selected from the feature parameters using the KPCA method, and the GRNN is then used to predict the gas concentration in the transformer oil. In the training process of the network, the FFOA is used to select the smooth factor of the neural network. Through a concrete example, it is shown that the method proposed in this paper has better data fitting ability and more accurate prediction ability compared with the support vector machine (SVM and gray model (GM methods.

  19. [Sources of dissolved organic carbon and the bioavailability of dissolved carbohydrates in the tributaries of Lake Taihu].

    Science.gov (United States)

    Ye, Lin-Lin; Wu, Xiao-Dong; Kong, Fan-Xiang; Liu, Bo; Yan, De-Zhi

    2015-03-01

    Surface water samples of Yincungang and Chendonggang Rivers were collected from September 2012 to August 2013 in Lake Taihu. Water temperature, Chlorophyll a and bacterial abundance were analyzed, as well as dissolved organic carbon (DOC) concentrations, stable carbon isotope of DOC (Δ13C(DOC)), specific UV absorbance (SUVA254 ) and dissolved carbohydrates concentrations. Δ13C(DOC) ranged from -27.03% per thousand ± 0.30% per thousand to -23.38%per thousand ± 0.20% per thousand, indicating a terrestrial source. Both the autochthonous and allochthonous sources contributed to the carbohydrates pool in the tributaries. Significant differences in PCHO (polysaccharides) and MCHO (monosaccharides) concentrations were observed between spring-summer and autumn-winter (P carbohydrates. PCHO contributed a major fraction to TCHO (total dissolved carbohydrates) in autumn and winter, which could be explained by the accumulation of undegradable PCHO limited by the low water temperature; MCHO contributed a major fraction to TCHO in spring and summer, which might be caused by the transformation from PCHO by microbes at high water temperature.

  20. Spatiotemporal variation of dissolved carbohydrates and amino acids in Jiaozhou Bay, China

    Science.gov (United States)

    Shi, Di; Yang, Guipeng; Sun, Yan; Wu, Guanwei

    2017-03-01

    Surface seawater samples were collected from Jiaozhou Bay, China, during six cruises (March-May 2010, September-November 2010) to study the distribution of dissolved organic matter including dissolved organic carbon (DOC), total dissolved carbohydrates, namely monosaccharides (MCHO) and polysaccharides (PCHO) and total hydrolysable amino acids. These included dissolved free amino acids (DFAA) and combined amino acids (DCAA). The goal was to investigate possible relationships between these dissolved organic compounds and environmental parameters. During spring, the concentrations of MCHO and PCHO were 9.6 (2.8-22.6) and 11.0 (2.9-42.5) μmol C/L, respectively. In autumn, MCHO and PCHO were 9.1 (2.6-27.0) and 10.8 (2.4-25.6) μmol C/L, respectively. The spring concentrations of DFAA and DCAA were 1.7 (1.1-4.1) and 7.6 (1.1-31.0) μmol C/L, respectively, while in autumn, DFAA and DCAA were 2.3 (1.1-8.0) and 3.3 (0.6-7.2) μmol C/L, respectively. Among these compounds, the concentrations of PCHO were the highest, accounting for nearly a quarter of the DOC, followed by MCHO, DCAA and DFAA. The concentrations of the organic compounds exhibited a decreasing trend from the coastal to the central regions of the bay. A negative correlation between concentrations of DOC and salinity in each cruise suggested that riverine inputs around the bay have an important impact on the distribution of DOC in the surface water. A significant positive correlation was found between DOC and total bacteria count in spring and autumn, suggesting bacteria play an important role in the marine carbon cycle.

  1. Impact of solute concentration on the electrocatalytic conversion of dissolved gases in buffered solutions

    KAUST Repository

    Shinagawa, Tatsuya; Takanabe, Kazuhiro

    2015-01-01

    . These alterations of the electrolyte properties associated with the solute concentration are universally applicable to other aqueous gas-related electrochemical reactions because the currents are purely determined by mass transfer of the dissolved gases. © 2015

  2. Vertical distribution and temporal dynamics of dissolved 137Cs concentrations in soil water after the Fukushima Dai-ichi Nuclear Power Plant accident.

    Science.gov (United States)

    Iwagami, Sho; Onda, Yuichi; Tsujimura, Maki; Hada, Manami; Pun, Ishwar

    2017-11-01

    Radiocesium ( 137 Cs) migration from headwater forested areas to downstream rivers has been investigated in many studies since the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, which was triggered by a catastrophic earthquake and tsunami on 11 March 2011. The accident resulted in the release of a huge amount of radioactivity and its subsequent deposition in the environment. A large part of the radiocesium released has been shown to remain in the forest. The dissolved 137 Cs concentration and its temporal dynamics in river water, stream water, and groundwater have been reported, but reports of dissolved 137 Cs concentration in soil water remain sparse. In this study, soil water was sampled, and the dissolved 137 Cs concentrations were measured at five locations with different land-use types (mature/young cedar forest, broadleaf forest, meadow land, and pasture land) in Yamakiya District, located 35 km northwest of FDNPP from July 2011 to October 2012. Soil water samples were collected by suction lysimeters installed at three different depths at each site. Dissolved 137 Cs concentrations were analyzed using a germanium gamma ray detector. The dissolved 137 Cs concentrations in soil water were high, with a maximum value of 2.5 Bq/L in July 2011, and declined to less than 0.32 Bq/L by 2012. The declining trend of dissolved 137 Cs concentrations in soil water was fitted to a two-component exponential model. The rate of decline in dissolved 137 Cs concentrations in soil water (k 1 ) showed a good correlation with the radiocesium interception potential (RIP) of topsoil (0-5 cm) at the same site. Accounting for the difference of 137 Cs deposition density, we found that normalized dissolved 137 Cs concentrations of soil water in forest (mature/young cedar forest and broadleaf forest) were higher than those in grassland (meadow land and pasture land). Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Effects of long-term land use change on dissolved carbon characteristics in the permafrost streams of northeast China.

    Science.gov (United States)

    Guo, Yuedong; Song, Changchun; Wan, Zhongmei; Tan, Wenwen; Lu, Yongzheng; Qiao, Tianhua

    2014-11-01

    Permafrost soils act as large sinks of organic carbon but are highly sensitive to interference such as changes in land use, which can greatly influence dissolved carbon loads in streams. This study examines the effects of long-term land reclamation on seasonal concentrations of dissolved carbons in the upper reaches of the Nenjiang River, northeast China. A comparison of streams in natural and agricultural systems shows that the dissolved organic carbon (DOC) concentration is much lower in the agricultural stream (AG) than in the two natural streams (WAF, wetland dominated; FR, forest dominated), suggesting that land use change is associated with reduced DOC exporting capacity. Moreover, the fluorescence indexes and the ratio of dissolved carbon to nitrogen also differ greatly between the natural and agricultural streams, indicating that the chemical characteristics and the origin of the DOC released from the whole reaches are also altered to some extent. Importantly, the exporting concentration of dissolved inorganic carbon (DIC) and its proportion of total dissolved carbon (TDC) substantially increase following land reclamation, which would largely alter the carbon cycling processes in the downstream fluvial system. Although the strong association between the stream discharge and the DOC concentration was unchanged, the reduction in total soil organic carbon following land reclamation led to remarkable decline of the total flux and exporting coefficient of the dissolved carbons. The results suggest that dissolved carbons in permafrost streams have been greatly affected by changes in land use since the 1970s, and the changes in the concentration and chemical characteristics of dissolved carbons will last until the alteration in both the traditional agriculture pattern and the persistent reclamation activities.

  4. A data reconnaissance on the effect of suspended-sediment concentrations on dissolved-solids concentrations in rivers and tributaries in the Upper Colorado River Basin

    Science.gov (United States)

    Tillman, Fred D.; Anning, David W.

    2014-01-01

    The Colorado River is one of the most important sources of water in the western United States, supplying water to over 35 million people in the U.S. and 3 million people in Mexico. High dissolved-solids loading to the River and tributaries are derived primarily from geologic material deposited in inland seas in the mid-to-late Cretaceous Period, but this loading may be increased by human activities. High dissolved solids in the River causes substantial damages to users, primarily in reduced agricultural crop yields and corrosion. The Colorado River Basin Salinity Control Program was created to manage dissolved-solids loading to the River and has focused primarily on reducing irrigation-related loading from agricultural areas. This work presents a reconnaissance of existing data from sites in the Upper Colorado River Basin (UCRB) in order to highlight areas where suspended-sediment control measures may be useful in reducing dissolved-solids concentrations. Multiple linear regression was used on data from 164 sites in the UCRB to develop dissolved-solids models that include combinations of explanatory variables of suspended sediment, flow, and time. Results from the partial t-test, overall likelihood ratio, and partial likelihood ratio on the models were used to group the sites into categories of strong, moderate, weak, and no-evidence of a relation between suspended-sediment and dissolved-solids concentrations. Results show 68 sites have strong or moderate evidence of a relation, with drainage areas for many of these sites composed of a large percentage of clastic sedimentary rocks. These results could assist water managers in the region in directing field-scale evaluation of suspended-sediment control measures to reduce UCRB dissolved-solids loading.

  5. Digitized Onondaga Lake Dissolved Oxygen Concentrations and Model Simulated Values using Bayesian Monte Carlo Methods

    Data.gov (United States)

    U.S. Environmental Protection Agency — The dataset is lake dissolved oxygen concentrations obtained form plots published by Gelda et al. (1996) and lake reaeration model simulated values using Bayesian...

  6. Concentrations and fluxes of dissolved uranium in the Yellow River estuary: seasonal variation and anthropogenic (Water-Sediment Regulation Scheme) impact

    International Nuclear Information System (INIS)

    Juanjuan, Sui; Zhigang, Yu; Bochao, Xu; Wenhua, Dong; Dong, Xia; Xueyan, Jiang

    2014-01-01

    The Water-Sediment Regulation Scheme (WSRS) of the Yellow River is a procedure implemented annually from June to July to expel sediments deposited in Xiaolangdi and other large middle-reach reservoirs and to scour the lower reaches of the river, by controlling water and sediment discharges. Dissolved uranium isotopes were measured in river waters collected monthly as well as daily during the 2010 WSRS (June 19–July 16) from Station Lijin (a hydrologic station nearest to the Yellow River estuary). The monthly samples showed dissolved uranium concentrations of 3.85–7.57 μg l −1 and 234 U/ 238 U activity ratios of 1.24–1.53. The concentrations were much higher than those reported for other global major rivers, and showed seasonal variability. Laboratory simulation experiments showed significant uranium release from bottom and suspended sediment. The uranium concentrations and activity ratios differed during the two stages of the WSRS, which may reflect desorption/dissolution of uranium from suspended river sediments of different origins. An annual flux of dissolved uranium of 1.04 × 10 8 g y −1 was estimated based on the monthly average water discharge and dissolved uranium concentration in the lower reaches of the Yellow River. The amount of dissolved uranium (2.65 × 10 7 g) transported from the Yellow River to the sea during the WSRS constituted about 1/4 of the annual flux. -- Highlights: • Dissolved U in the Yellow River estuary has distinct seasonal variability. • Geochemistry of dissolved U influenced by the WSRS has been analyzed. • Uranium flux during the WSRS has been evaluated

  7. Technical Note: Comparison between a direct and the standard, indirect method for dissolved organic nitrogen determination in freshwater environments with high dissolved inorganic nitrogen concentrations

    DEFF Research Database (Denmark)

    Graeber, Daniel; Gelbrecht, Jörg; Kronvang, Brian

    2012-01-01

    Research on dissolved organic nitrogen (DON) in aquatic systems with high dissolved inorganic nitrogen (DIN, the sum of NO3–, NO2– and NH4+) concentrations is often hampered by high uncertainties regarding the determined DON concentration. The reason is that DON is determined indirectly...... accuracy at high DIN : TDN ratios, we investigated the DON measurement accuracy of this standard approach according to the DIN : TDN ratio and compared it to the direct measurement of DON by size-exclusion chromatography (SEC) for freshwater systems. For this, we used standard compounds and natural samples...... separation of DON from DIN. For SEC, DON recovery rates were 91–108% for five pure standard compounds and 89–103% for two standard compounds, enriched with DIN. Moreover, SEC resulted in 93–108% recovery rates for DON concentrations of natural samples at a DIN : TDN ratio of 0.8 and the technique...

  8. Impact of solute concentration on the electrocatalytic conversion of dissolved gases in buffered solutions

    KAUST Repository

    Shinagawa, Tatsuya

    2015-04-24

    To maintain local pH levels near the electrode during electrochemical reactions, the use of buffer solutions is effective. Nevertheless, the critical effects of the buffer concentration on electrocatalytic performances have not been discussed in detail. In this study, two fundamental electrochemical reactions, oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR), on a platinum rotating disk electrode are chosen as model gas-related aqueous electrochemical reactions at various phosphate concentrations. Our detailed investigations revealed that the kinetic and limiting diffusion current densities for both the ORR and HOR logarithmically decrease with increasing solute concentration (log|jORR|=-0.39c+0.92,log|jHOR|=-0.35c+0.73). To clarify the physical aspects of this phenomenon, the electrolyte characteristics are addressed: with increasing phosphate concentration, the gas solubility decrease, the kinematic viscosity of the solution increase and the diffusion coefficient of the dissolved gases decrease. The simulated limiting diffusion currents using the aforementioned parameters match the measured ones very well (log|jORR|=-0.43c+0.99,log|jHOR|=-0.40c+0.54), accurately describing the consequences of the electrolyte concentration. These alterations of the electrolyte properties associated with the solute concentration are universally applicable to other aqueous gas-related electrochemical reactions because the currents are purely determined by mass transfer of the dissolved gases. © 2015 The Authors.

  9. Passive sampling methods for contaminated sediments: Scientific rationale supporting use of freely dissolved concentrations

    DEFF Research Database (Denmark)

    Mayer, Philipp; Parkerton, Thomas F.; Adams, Rachel G.

    2014-01-01

    Passive sampling methods (PSMs) allow the quantification of the freely dissolved concentration (Cfree ) of an organic contaminant even in complex matrices such as sediments. Cfree is directly related to a contaminant's chemical activity, which drives spontaneous processes including diffusive upta...

  10. The distribution and stabilisation of dissolved Fe in deep-sea hydrothermal plumes

    Science.gov (United States)

    Bennett, Sarah A.; Achterberg, Eric P.; Connelly, Douglas P.; Statham, Peter J.; Fones, Gary R.; German, Christopher R.

    2008-06-01

    We have conducted a study of hydrothermal plumes overlying the Mid-Atlantic Ridge near 5° S to investigate whether there is a significant export flux of dissolved Fe from hydrothermal venting to the oceans. Our study combined measurements of plume-height Fe concentrations from a series of 6 CTD stations together with studies of dissolved Fe speciation in a subset of those samples. At 2.5 km down plume from the nearest known vent site dissolved Fe concentrations were ˜ 20 nM. This is much higher than would be predicted from a combination of plume dilution and dissolved Fe(II) oxidation rates, but consistent with stabilisation due to the presence of organic Fe complexes and Fe colloids. Using Competitive Ligand Exchange-Cathodic Stripping Voltammetry (CLE-CSV), stabilised dissolved Fe complexes were detected within the dissolved Fe fraction on the edges of one non-buoyant hydrothermal plume with observed ligand concentrations high enough to account for stabilisation of ˜ 4% of the total Fe emitted from the 5° S vent sites. If these results were representative of all hydrothermal systems, submarine venting could provide 12-22% of the global deep-ocean dissolved Fe budget.

  11. Automated determination of the stable carbon isotopic composition (δ13C) of total dissolved inorganic carbon (DIC) and total nonpurgeable dissolved organic carbon (DOC) in aqueous samples: RSIL lab codes 1851 and 1852

    Science.gov (United States)

    Révész, Kinga M.; Doctor, Daniel H.

    2014-01-01

    The purposes of the Reston Stable Isotope Laboratory (RSIL) lab codes 1851 and 1852 are to determine the total carbon mass and the ratio of the stable isotopes of carbon (δ13C) for total dissolved inorganic carbon (DIC, lab code 1851) and total nonpurgeable dissolved organic carbon (DOC, lab code 1852) in aqueous samples. The analysis procedure is automated according to a method that utilizes a total carbon analyzer as a peripheral sample preparation device for analysis of carbon dioxide (CO2) gas by a continuous-flow isotope ratio mass spectrometer (CF-IRMS). The carbon analyzer produces CO2 and determines the carbon mass in parts per million (ppm) of DIC and DOC in each sample separately, and the CF-IRMS determines the carbon isotope ratio of the produced CO2. This configuration provides a fully automated analysis of total carbon mass and δ13C with no operator intervention, additional sample preparation, or other manual analysis. To determine the DIC, the carbon analyzer transfers a specified sample volume to a heated (70 °C) reaction vessel with a preprogrammed volume of 10% phosphoric acid (H3PO4), which allows the carbonate and bicarbonate species in the sample to dissociate to CO2. The CO2 from the reacted sample is subsequently purged with a flow of helium gas that sweeps the CO2 through an infrared CO2 detector and quantifies the CO2. The CO2 is then carried through a high-temperature (650 °C) scrubber reactor, a series of water traps, and ultimately to the inlet of the mass spectrometer. For the analysis of total dissolved organic carbon, the carbon analyzer performs a second step on the sample in the heated reaction vessel during which a preprogrammed volume of sodium persulfate (Na2S2O8) is added, and the hydroxyl radicals oxidize the organics to CO2. Samples containing 2 ppm to 30,000 ppm of carbon are analyzed. The precision of the carbon isotope analysis is within 0.3 per mill for DIC, and within 0.5 per mill for DOC.

  12. [Distributions and influencing factors of total dissolved inorganic antimony in the coastal area of Zhejiang and Fujian].

    Science.gov (United States)

    Zhang, Xu-Zhou; Ren, Jing-Ling; Liu, Zong-Guang; Fan, Xiao-Peng; Liu, Cheng-Gang; Wu, Ying

    2014-02-01

    Antimony has been ubiquitously present in the aquatic environment as a toxic and rare metalloid element. The contamination of antimony and its compounds in the environment is increasingly severe, so it has been received extensive attention by the international scientific community. The cruise was carried out in the coastal area of Zhejiang and Fujian provinces in the East China Sea (ECS) in May 2008. The concentrations of total dissolved inorganic antimony (TDISb) were measured by Hydride Generation-Atomic Fluorescence (HG-AFS). The concentration ranges of TDISb in the surface and bottom layer were 0.68-5.64 nmol x L(-1) and 0.71-5.25 nmol x L(-1) with averages of 2.25 and 1.79 nmol x L(-1), respectively. The concentration of TDISb in the study area was lower than the environmental quality standards for surface water of China and drinking water standards of World Health Organization (about 41.08 nmol x L(-1)), indicating that it remained at the pristine level. The concentration of TDISb decreased gradually from the coastal area to the central ECS shelf with higher concentration in the surface layer than the bottom. Water mass mixing, adsorption/desorption behavior on the surface of the suspended particulate matters (SPM) and biological activities were the main influence factors of TDISb biogeochemistry in the study area.

  13. Removal of actinides from dissolved ORNL MVST sludge using the TRUEX process

    International Nuclear Information System (INIS)

    Spencer, B.B.; Egan, B.Z.; Chase, C.W.

    1997-07-01

    Experiments were conducted to evaluate the transuranium extraction process for partitioning actinides from actual dissolved high-level radioactive waste sludge. All tests were performed at ambient temperature. Time and budget constraints permitted only two experimental campaigns. Samples of sludge from Melton Valley Storage Tank W-25 were rinsed with mild caustic (0.2 M NaOH) to reduce the concentrations of nitrates and fission products associated with the interstitial liquid. In one campaign, the rinsed sludge was dissolved in nitric acid to produce a solution containing total metal concentrations of ca. 1.8 M with a nitric acid concentration of ca. 2.9 M. About 50% of the dry mass of the sludge was dissolved. In the other campaign, the sludge was neutralized with nitric acid to destroy the carbonates, then leached with ca. 2.6 M NaOH for ca. 6 h before rinsing with the mild caustic. The sludge was then dissolved in nitric acid to produce a solution containing total metal concentrations of ca. 0.6 M with a nitric acid concentration of ca. 1.7 M. About 80% of the sludge dissolved. The dissolved sludge solution form the first campaign began gelling immediately, and a visible gel layer was observed after 8 days. In the second campaign, the solution became hazy after ca. 8 days, indicating gel formation, but did not display separated gel layers after aging for 20 days. Batch liquid-liquid equilibrium tests of both the extraction and stripping operations were conducted. Chemical analyses of both phases were used to evaluate the process. Evaluation was based on two metrics: the fraction of TRU elements removed from the dissolved sludge and comparison of the results with predictions made with the Generic TRUEX Model (GTM). The fractions of Eu, Pu, Cm, Th, and U species removed from aqueous solution in only one extraction stage were > 95% and were close to the values predicted by the GTM. Mercury was also found to be strongly extracted, with a one-stage removal of > 92%

  14. Distributions and seasonal variations of dissolved carbohydrates in the Jiaozhou Bay, China

    Science.gov (United States)

    Yang, Gui-Peng; Zhang, Yan-Ping; Lu, Xiao-Lan; Ding, Hai-Bing

    2010-06-01

    Surface seawater samples were collected in the Jiaozhou Bay, a typical semi-closed basin located at the western part of the Shandong Peninsula, China, during four cruises. Concentrations of monosaccharides (MCHO), polysaccharides (PCHO) and total dissolved carbohydrates (TCHO) were measured with the 2,4,6-tripyridyl- s-triazine spectroscopic method. Concentrations of TCHO varied from 10.8 to 276.1 μM C for all samples and the ratios of TCHO to dissolved organic carbon (DOC) ranged from 1.1 to 67.9% with an average of 10.1%. This result indicated that dissolved carbohydrates were an important constituent of DOC in the surface seawater of the Jiaozhou Bay. In all samples, the concentrations of MCHO ranged from 2.9 to 65.9 μM C, comprising 46.1 ± 16.6% of TCHO on average, while PCHO ranged from 0.3 to 210.2 μM C, comprising 53.9 ± 16.6% of TCHO on average. As a major part of dissolved carbohydrates, the concentrations of PCHO were higher than those of MCHO. MCHO and PCHO accumulated in January and July, with minimum average concentration in April. The seasonal variation in the ratios of TCHO to DOC was related to water temperature, with high values in January and low values in July and October. The concentrations of dissolved carbohydrates displayed a decreasing trend from the coastal to the central areas. Negative correlations between concentrations of TCHO and salinity in July suggested that riverine input around the Jiaozhou Bay had an important effect on the concentrations of dissolved carbohydrates in surface seawater. The pattern of distributions of MCHO and PCHO reported in this study added to the global picture of dissolved carbohydrates distribution.

  15. Changes in concentration and (delta) 13C value of dissolved CH4, CO2 and organic carbon in rice paddies under ambient and elevated concentrations of atmospheric CO2

    International Nuclear Information System (INIS)

    Weiguo Cheng; Yagi, Kazuyuki; Sakai, Hidemitsu; Hua Xu; Kobayashi, Kazuhiko

    2005-01-01

    Changes in concentration and (delta) 13 C value of dissolved CH 4 , CO 2 and organic carbon (DOC) in floodwater and soil solution from a Japanese rice paddy were studied under ambient and elevated concentrations of atmospheric CO 2 in controlled environment chambers. The concentrations of dissolved CH 4 in floodwater increased with rice growth (with some fluctuation), while the concentrations of CO 2 remained between 2.9 to 4.4 and 4.2 to 5.8 μg C mL -1 under conditions of ambient and elevated CO 2 concentration, respectively. The amount of CH 4 dissolved in soil solution under elevated CO 2 levels was significantly lower than under ambient CO 2 in the tillering stage, implying that the elevated CO 2 treatment accelerated CH 4 oxidation during the early stage of growth. However, during later stages of growth, production of CH 4 increased and the amount of CH 4 dissolved in soil solution under elevated CO 2 levels was, on average, greater than that under ambient CO 2 conditions. Significant correlation existed among the (delta) 13 C values of dissolved CH 4 , CO 2 , and DOC in floodwater (except for the samples taken immediately after pulse feeding with 13 C enriched CO 2 ), indicating that the origins and cycling of CH 4 , CO 2 and DOC were related. There were also significant correlations among the (delta) 13 C values of CH 4 , CO 2 and DOC in the soil solution. The turnover rate of CO 2 in soil solution was most rapid in the panicle formation stage of rice growth and that of CH 4 fastest in the grain filling stage. (Author)

  16. Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

    International Nuclear Information System (INIS)

    Prasetyaningrum, A.; Ratnawati,; Jos, B.

    2015-01-01

    Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O 3 ) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV

  17. Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

    Science.gov (United States)

    Prasetyaningrum, A.; Ratnawati, Jos, B.

    2015-12-01

    Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O3) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.

  18. Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

    Energy Technology Data Exchange (ETDEWEB)

    Prasetyaningrum, A., E-mail: ajiprasetyaningrum@gmail.com; Ratnawati,; Jos, B. [Department of Chemical Engineering, Faculty of Engineering, Diponegoro University Jl. Prof. H. Soedarto Tembalang, Semarang, Central Java, Indonesia, 50276 (Indonesia)

    2015-12-29

    Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O{sub 3}) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.

  19. Regulation of the dissolved phosphate concentration of a mountainous stream, Kitakyushu, southwestern Japan.

    Science.gov (United States)

    Koga, Masaaki; Yoshimura, Kazuhisa

    2012-07-01

    The phosphate concentration in mountainous stream water can be a measure of the forest condition, because its concentration will be low when the biomass in the forest is increasing and vice versa when the forest is declining. To investigate the seasonal change in the dissolved phosphate concentration of the mountainous stream water of the Yamakami River, Kitakyushu, from June 2009 to August 2010, and the regulation mechanism of the phosphate concentration, solid-phase spectrophotometry, which can be applicable to natural water without any pretreatment procedures, was employed for the determination of phosphate at μg P L(-1) levels in natural water. The phosphate concentrations in the mountainous stream waters at 6 sites ranged from 2.2 to 13 μg P L(-1), and those from the catchment area of the steady state forest were 5.3 ± 1.6 (±1 SD) μg P L(-1). Changes in the concentration were fairly small even during a storm runoff. The average phosphate concentration of rain was 2.8 ± 0.7 μg P L(-1), about half of the concentration in the stream water. The rate of runoff in forest areas is generally considered to be about 50% of the total precipitation. For a forest under a climax condition, the phosphate concentration is estimated to be regulated by the fallout and evapotranspiration (α = 0.05). At one of the sites, an upstream tributary, where a fairly big landslide occurred before July in 2009, the phosphate concentration was the highest, suggesting that the biomass may still be decreasing. For all of the six sites examined, a characteristic seasonal change in phosphate concentration was observed, reflecting the local budget between the biological decomposition of plant matter and the consumption by the biomass. The increase in the phosphate concentration during late spring and early summer may result from the extensive decomposition of plant litter mainly supplied in autumn and of plant matter relating to spring blooming such as fallen flowers, pollen and immature

  20. Voltammetric determination of total dissolved iron in coastal waters using a glassy carbon electrode modified with reduced graphene oxide, Methylene Blue and gold nanoparticles

    International Nuclear Information System (INIS)

    Lin, Mingyue; Zhang, Haiyun; Han, Haitao; Pan, Dawei; Su, Zhencui

    2015-01-01

    A nanocomposite, prepared from reduced graphene oxide (rGO), Methylene Blue (MB) and gold nanoparticles (AuNPs), was used to modify a glassy carbon electrode for the determination of total dissolved iron by differential pulse voltammetry. The use of rGO warrants a larger electrode surface and the presence of more active sites, while electron transfer is accelerated by incorporating AuNPs. MB acts as an electron mediator, as an anchor for the AuNPs (which were grown in situ), and also prevents the aggregation of rGO. The modified electrode displayed a remarkably improved sensitivity and selectivity for Fe(III). The kinetics of the electrode reaction is adsorption-controlled, and the reversible process involves one proton and one electron. The response to Fe(III) is linear in the 0.3 to 100 μM concentration range, and the detection limit is 15 nM. Possible interferences by other ions were studied. The electrode was successfully applied to the determination of total dissolved iron in real coastal waters. (author)

  1. Impact of upwelling events on the sea water carbonate chemistry and dissolved oxygen concentration in the Gulf of Papagayo (Culebra Bay, Costa Rica: Implications for coral reefs

    Directory of Open Access Journals (Sweden)

    Tim Rixen

    2012-04-01

    Full Text Available The Gulf of Papagayo, Pacific coast of Costa Rica, is one of the three seasonal upwelling areas of Mesoamerica. In April 2009, a 29-hour experiment was carried out at the pier of the Marina Papagayo, Culebra Bay. We determined sea surface temperature (SST, dissolved oxygen concentration, salinity, pH, and the partial pressure of CO2 (pCO2. The aragonite saturation state (Ωa as well as the other parameters of the marine carbonate system such as the total dissolved inorganic carbon (DIC and the total alkalinity (TA were calculated based on the measured pH and the pCO2. The entrainment of subsurface waters raised the pCO2 up to 645 µatm. SSTs, dissolved oxygen concentrations decreased form 26.4 to 23.7°C and from 228 to 144 µmol l-1. Ωa dropped down to values of 2.1. Although these changes are assumed to reduce the coral growth, the main reef building coral species within the region (Pocillopora spp. and Pavona clavus reveal growth rates exceeding those measured at other sites in the eastern tropical Pacific. This implies that the negative impact of upwelling on coral growth might be overcompensated by an enhanced energy supply caused by the high density of food and nutrients and more favorable condition for coral growth during the non-upwelling season.

  2. Temporal and spatial variations in total suspended and dissolved solids in the upper part of Manoa stream, Hawaii

    NARCIS (Netherlands)

    Augustijn, Dionysius C.M.; Fares, Ali; Tran, Dai Ngia

    2011-01-01

    Hawaiian watersheds are small, steep, and receive high intensity rainfall events of non-uniform distribution. These geographic and weather patterns result in flashy streams of strongly variable water quality even within various stream segments. Total suspended solids (TSS) and total dissolved solids

  3. Concentrations and fluxes of dissolved uranium in the Yellow River estuary: seasonal variation and anthropogenic (Water-Sediment Regulation Scheme) impact.

    Science.gov (United States)

    Juanjuan, Sui; Zhigang, Yu; Bochao, Xu; Wenhua, Dong; Dong, Xia; Xueyan, Jiang

    2014-02-01

    The Water-Sediment Regulation Scheme (WSRS) of the Yellow River is a procedure implemented annually from June to July to expel sediments deposited in Xiaolangdi and other large middle-reach reservoirs and to scour the lower reaches of the river, by controlling water and sediment discharges. Dissolved uranium isotopes were measured in river waters collected monthly as well as daily during the 2010 WSRS (June 19-July 16) from Station Lijin (a hydrologic station nearest to the Yellow River estuary). The monthly samples showed dissolved uranium concentrations of 3.85-7.57 μg l(-1) and (234)U/(238)U activity ratios of 1.24-1.53. The concentrations were much higher than those reported for other global major rivers, and showed seasonal variability. Laboratory simulation experiments showed significant uranium release from bottom and suspended sediment. The uranium concentrations and activity ratios differed during the two stages of the WSRS, which may reflect desorption/dissolution of uranium from suspended river sediments of different origins. An annual flux of dissolved uranium of 1.04 × 10(8) g y(-1) was estimated based on the monthly average water discharge and dissolved uranium concentration in the lower reaches of the Yellow River. The amount of dissolved uranium (2.65 × 10(7) g) transported from the Yellow River to the sea during the WSRS constituted about 1/4 of the annual flux. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Effect of catchment land use and soil type on the concentration, quality, and bacterial degradation of riverine dissolved organic matter

    DEFF Research Database (Denmark)

    Autio, Iida; Soinne, Helena; Helin, Janne

    2016-01-01

    We studied the effects of catchment characteristics (soil type and land use) on the concentration and quality of dissolved organic matter (DOM) in river water and on the bacterial degradation of terrestrial DOM. The share of organic soil was the strongest predictor of high concentrations...... of dissolved organic carbon, nitrogen, and phosphorus (DOC, DON, and DOP, respectively), and was linked to DOM quality. Soil type was more important than land use in determining the concentration and quality of riverine DOM. On average, 5–9 % of the DOC and 45 % of the DON were degraded by the bacterial...

  5. The soil organic carbon content of anthropogenically altered organic soils effects the dissolved organic matter quality, but not the dissolved organic carbon concentrations

    Science.gov (United States)

    Frank, Stefan; Tiemeyer, Bärbel; Bechtold, Michel; Lücke, Andreas; Bol, Roland

    2016-04-01

    Dissolved organic carbon (DOC) is an important link between terrestrial and aquatic ecosystems. This is especially true for peatlands which usually show high concentrations of DOC due to the high stocks of soil organic carbon (SOC). Most previous studies found that DOC concentrations in the soil solution depend on the SOC content. Thus, one would expect low DOC concentrations in peatlands which have anthropogenically been altered by mixing with sand. Here, we want to show the effect of SOC and groundwater level on the quantity and quality of the dissolved organic matter (DOM). Three sampling sites were installed in a strongly disturbed bog. Two sites differ in SOC (Site A: 48%, Site B: 9%) but show the same mean annual groundwater level of 15 and 18 cm below ground, respectively. The SOC content of site C (11%) is similar to Site B, but the groundwater level is much lower (-31 cm) than at the other two sites. All sites have a similar depth of the organic horizon (30 cm) and the same land-use (low-intensity sheep grazing). Over two years, the soil solution was sampled bi-weekly in three depths (15, 30 and 60 cm) and three replicates. All samples were analyzed for DOC and selected samples for dissolved organic nitrogen (DON) and delta-13C and delta-15N. Despite differences in SOC and groundwater level, DOC concentrations did not differ significantly (A: 192 ± 62 mg/L, B: 163 ± 55 mg/L and C: 191 ± 97 mg/L). At all sites, DOC concentrations exceed typical values for peatlands by far and emphasize the relevance even of strongly disturbed organic soils for DOC losses. Individual DOC concentrations were controlled by the temperature and the groundwater level over the preceding weeks. Differences in DOM quality were clearer. At site B with a low SOC content, the DOC:DON ratio of the soil solution equals the soil's C:N ratio, but the DOC:DON ratio is much higher than the C:N ratio at site A. In all cases, the DOC:DON ratio strongly correlates with delta-13C. There is no

  6. A synthesis of light absorption properties of the Arctic Ocean: application to semianalytical estimates of dissolved organic carbon concentrations from space

    Science.gov (United States)

    Matsuoka, A.; Babin, M.; Doxaran, D.; Hooker, S. B.; Mitchell, B. G.; Bélanger, S.; Bricaud, A.

    2014-06-01

    In addition to scattering coefficients, the light absorption coefficients of particulate and dissolved materials are the main factors determining the light propagation of the visible part of the spectrum and are, thus, important for developing ocean color algorithms. While these absorption properties have recently been documented by a few studies for the Arctic Ocean (e.g., Matsuoka et al., 2007, 2011; Ben Mustapha et al., 2012), the data sets used in the literature were sparse and individually insufficient to draw a general view of the basin-wide spatial and temporal variations in absorption. To achieve such a task, we built a large absorption database of the Arctic Ocean by pooling the majority of published data sets and merging new data sets. Our results show that the total nonwater absorption coefficients measured in the eastern Arctic Ocean (EAO; Siberian side) are significantly higher than in the western Arctic Ocean (WAO; North American side). This higher absorption is explained by higher concentration of colored dissolved organic matter (CDOM) in watersheds on the Siberian side, which contains a large amount of dissolved organic carbon (DOC) compared to waters off North America. In contrast, the relationship between the phytoplankton absorption (aϕ(λ)) and chlorophyll a (chl a) concentration in the EAO was not significantly different from that in the WAO. Because our semianalytical CDOM absorption algorithm is based on chl a-specific aϕ(λ) values (Matsuoka et al., 2013), this result indirectly suggests that CDOM absorption can be appropriately derived not only for the WAO but also for the EAO using ocean color data. Based on statistics, derived CDOM absorption values were reasonable compared to in situ measurements. By combining this algorithm with empirical DOC versus CDOM relationships, a semianalytical algorithm for estimating DOC concentrations for river-influenced coastal waters of the Arctic Ocean is presented and applied to satellite

  7. Experimental study on total dissolved gas supersaturation in water

    Directory of Open Access Journals (Sweden)

    Lu Qu

    2011-12-01

    Full Text Available More and more high dams have been constructed and operated in China. The total dissolved gas (TDG supersaturation caused by dam discharge leads to gas bubble disease or even death of fish. Through a series of experiments, the conditions and requirements of supersaturated TDG generation were examined in this study. The results show that pressure (water depth, aeration, and bubble dissolution time are required for supersaturated TDG generation, and the air-water contact area and turbulence intensity are the main factors that affect the generation rate of supersaturated TDG. The TDG supersaturation levels can be reduced by discharging water to shallow shoals downstream of the dam or using negative pressure pipelines. Furthermore, the TDG supersaturation levels in stilling basins have no direct relationship with those in reservoirs. These results are of great importance for further research on the prediction of supersaturated TDG generation caused by dam discharge and aquatic protection.

  8. Research on electrochemical methods for concentration measurement of dissolved ion in molten salt to apply to electrolytic process control. Innovative research adopted in 2002 fiscal year

    International Nuclear Information System (INIS)

    Nagai, Takayuki

    2005-03-01

    The purpose of this research is to establish the online (in-situ) technique for concentration measuring of dissolved ion in the molten salt, and this technique is due to the electrochemical method for the concentration measuring of dissolved ion in solutions like the polarization curve measurement. This research executed the following four items. 1) Examination of possibility for concentration measuring of dissolved ion in molten salt by cyclic voltammetry. 2) Examination of possibility for concentration measuring of dissolved ion in molten salt by various electrochemical methods. 3) Examination of suitable electrochemical method for concentration measuring of dissolved ion. 4) Confirmation of selected electrochemical method for concentration measuring of dissolved ion. It has been understood that the differential pulse voltammetry (DPV) is a promising electrochemical technique for the concentration measuring of dissolved ion in the molten salt as a result of this research. An appropriate measurement condition is as follows, the potential sweep rate is -0.1 V/s, the pulse cycle is 0.1 s, the pulse width is 10 ms, and the pulse voltage is 50 mV. As for the electrodes, the platinum working electrode, the glassy carbon counter electrode, and silver/silver chloride reference electrode are suitable. Moreover, the molar absorptivities of U 3+ , U 4+ , UO 2 + , UO 2 2+ , and the standard redox potentials of couples of U 4+ /U 3+ and UO 2 2+ /UO 2 + were acquired as a basic data of the uranium and the uranyl ion in molten NaCl-2CsCl. (author)

  9. Comparison of Serum Concentrations of Total Cholesterol and Total ...

    African Journals Online (AJOL)

    Tuberculosis (TB) is one of the most dangerous tropical diseases that complicates HIV infection in Nigeria to date. Over two million Nigerians are known to be infected with TB and many more are at risk of the infection. Serum concentrations of total cholesterol and total lipid of 117 female TB patients attending chest clinic at ...

  10. Resin bead-thermal ionization mass spectrometry for determination of plutonium concentration in irradiated fuel dissolver solution

    International Nuclear Information System (INIS)

    Paul, Sumana; Shah, R.V.; Aggarwal, S.K.; Pandey, A.K.

    2015-01-01

    Determination of isotopic composition (IC) and concentration of plutonium (Pu) is necessary at various stages of nuclear fuel cycle which involves analysis of complex matrices like dissolver solution of irradiated fuel, nuclear waste stream etc. Mass spectrometry, e.g. thermal ionization mass spectrometry (TIMS) and inductively coupled plasma mass spectrometry (ICP-MS) are commonly used for determination of IC and concentration of plutonium. However, to circumvent matrix interferences, efficient separation as well as preconcentration of Pu is required prior to mass spectrometric analysis. Purification steps employing ion-exchange resins are widely used for the separation of Pu from dissolver solution or from mixture of other actinides e.g. U, Am. However, an alternative way is to selectively preconcentrate Pu on a resin bead, followed by direct loading of the bead on the filament of thermal ionization mass spectrometer

  11. [Distributions and seasonal variations of total dissolved inorganic arsenic in the estuaries and coastal area of eastern Hainan].

    Science.gov (United States)

    Cao, Xiu-Hong; Ren, Jing-Ling; Zhang, Gui-Ling; Zhang, Jin-E; Du, Jin-Zhou; Zhu, De-Di

    2012-03-01

    The concentrations of total dissolved inorganic arsenic (TDIAs) were measured by Hydride Generation-Atomic Fluorescence Spectrometry (HG-AFS). Two cruises were carried out in the river, estuary, coastal area and groundwater of eastern Hainan in December 2006 and August 2007. The concentrations of TDIAs in the Wanquan and Wenchang/Wenjiao rivers and their estuaries, coastal area in December 2006 were 4.0-9.4, 1.3-13.3, 13.3-17.3 nmol x L(-1), respectively. The concentrations of TDIAs in the Wanquan and Wenchang/Wenjiao rivers and their estuaries, coastal area in August 2007 were 1.6-15.5, 2.4-15.9, 10.8-17.6 nmol x L(-1), respectively. There was no significantly seasonal variation of TDIAs in the rivers and estuaries during the dry and wet seasons. Compared with other areas in the world, the concentration of TDIAs in the Eastern Hainan remained at pristine levels. TDIAs showed conservatively mixing in the both estuaries. The concentration of TDIAs of groundwater was below detection limit (BDL)-41.7 nmol x L(-1). The submarine groundwater discharge (SGD) to the coastal area was estimated in the drainage basin of Wenchang/Wenjiao river based on the average concentration of TDIAs in the groundwater and SGD water discharge, with the value of 1 153 mol x a(-1). Budget estimation indicated that the SGD discharge is one of the important sources of arsenic in the coastal area.

  12. Response surface modeling for optimization heterocatalytic Fenton oxidation of persistence organic pollution in high total dissolved solid containing wastewater.

    Science.gov (United States)

    Sekaran, G; Karthikeyan, S; Boopathy, R; Maharaja, P; Gupta, V K; Anandan, C

    2014-01-01

    The rice-husk-based mesoporous activated carbon (MAC) used in this study was precarbonized and activated using phosphoric acid. N2 adsorption/desorption isotherm, X-ray powder diffraction, electron spin resonance, X-ray photoelectron spectroscopy and scanning electron microscopy, transmission electron microscopy, (29)Si-NMR spectroscopy, and diffuse reflectance spectroscopy were used to characterize the MAC. The tannery wastewater carrying high total dissolved solids (TDS) discharged from leather industry lacks biodegradability despite the presence of dissolved protein. This paper demonstrates the application of free electron-rich MAC as heterogeneous catalyst along with Fenton reagent for the oxidation of persistence organic compounds in high TDS wastewater. The heterogeneous Fenton oxidation of the pretreated wastewater at optimum pH (3.5), H2O2 (4 mmol/L), FeSO4[Symbol: see text]7H2O (0.2 mmol/L), and time (4 h) removed chemical oxygen demand, biochemical oxygen demand, total organic carbon and dissolved protein by 86, 91, 83, and 90%, respectively.

  13. Monitoring dissolved radioactive cesium in Abukuma River in Fukushima Prefecture

    International Nuclear Information System (INIS)

    Yasutaka, Tetsuo; Kawabe, Yoshishige; Kurosawa, Akihiko; Komai, Takeshi

    2013-01-01

    Radioactive materials were released into the atmosphere and deposited over wide areas of farmland, forests, and cities; elevated levels of "1"3"1I, "1"3"4Cs, and "1"3"7Cs have been detected in these areas due to the accident at the Tokyo Power Fukushima Daiichi Nuclear Power Plant caused by the April 2011 earthquake and tsunami in eastern Japan. Radioactive Cs deposited on farmland and forests gradually leaches into water bodies such as mountain streams and rivers adsorbed onto particles or in a dissolved state. It is important to calrify the level of dissolved and total radioactive Cs in environmental water for forecasting the of discharge of radioactive Cs from forest and watersheds, assessing on the effect of dissolved and total radioactive Cs on not only irrigation water but also rice and other crops, and evaluating the transport of radioactive Cs from rivers to costal areas. Therefore, it is important to monitor their levels in Fukushima Prefecture over time. In this research, we monitored the levels of dissolved and total radioactive Cs in Abukuma River using a conventional evaporative concentration method. By monitoring the river waters since September 2012, it was estimated that the levels of dissolved radioactive Cs were less than 0.128 Bq/L and those of total radioactive Cs were less than 0.274 Bq/L in the main stream and branches of Abukuma River in the low suspended solid condition. (author)

  14. Dissolved strontium and calcium levels in the tropical Indian Ocean

    Science.gov (United States)

    Steiner, Zvi; Sarkar, Amit; Turchyn, Alexandra

    2017-04-01

    Measurements of seawater alkalinity and dissolved calcium concentrations along oceanic transects are often used to calculate calcium carbonate precipitation and dissolution rates. Given that the distribution coefficient of strontium in CaCO3 varies greatly between different groups of organisms, adding precise measurements of dissolved strontium concentrations provides opportunities to also track relative contributions of these different groups to the regional CaCO3 cycle. However, there are several obstacles to this approach. These obstacles include unresolved systematic discrepancies between seawater calcium and alkalinity data, very large analytical noise around the calcium concentration measurements and the unconstrained role of acantharia (radiolarian precipitating SrSO4 skeletons) in the marine strontium cycle. During the first cruise of the second International Indian Ocean Expedition (IIOE-2) water samples were collected along 67°E from 9°N to 5°S to explore the dissolution rate of calcium carbonate in the water. The dissolution rate can be calculated by combining measurements of water column potential alkalinity with calcium and strontium concentrations measured by ICP-OES and calcium concentration measurements using isotope dilution thermal ionization mass spectrometry (ID-TIMS). CaCO3 mineral saturation state calculated using pH and total alkalinity suggests that along 67°E, the aragonite saturation horizon lays at depth of 500 m on both sides of the equator. Across the cruise transect, dissolved strontium concentrations increase by 2-3% along the thermocline suggesting rapid recycling of strontium rich phases. This is particularly evident just below the thermocline at 8-9°N and below 1000 m water depth, south of the equator. The deep, southern enrichment in strontium does not involve a change in the Sr/Ca ratio, suggesting that this strontium enrichment is related to CaCO3 dissolution. In contrast, in the intermediate waters of the northern part of

  15. Effect of dissolved hydrogen concentration on IASCC initiation susceptibility of type 316 stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Min-Jae; Kim, Sung Woo; Hwang, Seong Sik [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    The effect of DH concentration on PWSCC of nickel based alloys has been studied, higher dissolved hydrogen strategy is being considered to obtain partial mitigation of PWSCC. In the case of stainless steels, it is necessary to research the effect of DH concentration on irradiation assisted stress corrosion cracking(IASCC). In this research, we tried to evaluate the effect of DH concentration on IASCC initiation susceptibility using the proton irradiated type 316 stainless steels under the condition of simulated primary water. The slow strain rate tests were performed using the proton irradiated type 316 stainless steels at the simulated primary water conditions, crack length per unit area for all tested specimens were calculated. IASCC initiation susceptibility was increased by increasing irradiation doses and by increasing DH concentration.

  16. Sensing dissolved sediment porewater concentrations of persistent and bioaccumulative poolutants using disposable solid-phase microextraction fibers

    NARCIS (Netherlands)

    Mayer, P.; Vaes, W.H.J.; Wijnker, F.; Legierse, K.C.H.M.; Kraaij, R.H.; Tolls, J.; Hermens, J.L.M.

    2000-01-01

    Polymer coated glass fibers were applied as disposable samplers to measure dissolved concentrations of persistent and bioaccumulative pollutants (PBPs) in sediment porewater. The method is called matrix solid-phase microextraction (matrix-SPME), because it utilizes the entire sediment matrix as a

  17. Dissolved and labile concentrations of Cd, Cu, Pb, and Zn in the South Fork Coeur d'Alene River, Idaho: Comparisons among chemical equilibrium models and implications for biotic ligand models

    Science.gov (United States)

    Balistrieri, L.S.; Blank, R.G.

    2008-01-01

    In order to evaluate thermodynamic speciation calculations inherent in biotic ligand models, the speciation of dissolved Cd, Cu, Pb, and Zn in aquatic systems influenced by historical mining activities is examined using equilibrium computer models and the diffusive gradients in thin films (DGT) technique. Several metal/organic-matter complexation models, including WHAM VI, NICA-Donnan, and Stockholm Humic model (SHM), are used in combination with inorganic speciation models to calculate the thermodynamic speciation of dissolved metals and concentrations of metal associated with biotic ligands (e.g., fish gills). Maximum dynamic metal concentrations, determined from total dissolved metal concentrations and thermodynamic speciation calculations, are compared with labile metal concentrations measured by DGT to assess which metal/organic-matter complexation model best describes metal speciation and, thereby, biotic ligand speciation, in the studied systems. Results indicate that the choice of model that defines metal/organic-matter interactions does not affect calculated concentrations of Cd and Zn associated with biotic ligands for geochemical conditions in the study area, whereas concentrations of Cu and Pb associated with biotic ligands depend on whether the speciation calculations use WHAM VI, NICA-Donnan, or SHM. Agreement between labile metal concentrations and dynamic metal concentrations occurs when WHAM VI is used to calculate Cu speciation and SHM is used to calculate Pb speciation. Additional work in systems that contain wide ranges in concentrations of multiple metals should incorporate analytical speciation methods, such as DGT, to constrain the speciation component of biotic ligand models. ?? 2008 Elsevier Ltd.

  18. A flow injection analyser conductometric coupled system for the field analysis of free dissolved CO{sub 2} and total dissolved inorganic carbon in natural waters

    Energy Technology Data Exchange (ETDEWEB)

    Martinotti, Valter; Balordi, Marcella; Ciceri, Giovanni [RSE SpA - Environment and Sustainable Development Department, Milan (Italy)

    2012-05-15

    A flow injection analyser coupled with a gas diffusion membrane and a conductometric microdetector was adapted for the field analysis of natural concentrations of free dissolved CO{sub 2} and dissolved inorganic carbon in natural waters and used in a number of field campaigns for marine water monitoring. The dissolved gaseous CO{sub 2} presents naturally, or that generated by acidification of the sample, is separated by diffusion using a hydrophobic semipermeable gas porous membrane, and the permeating gas is incorporated into a stream of deionised water and measured by means of an electrical conductometric microdetector. In order to make the system suitable and easy to use for in-field measurements aboard oceanographic ships, the single components of the analyser were compacted into a robust and easy to use system. The calibration of the system is carried out by using standard solutions of potassium bicarbonate at two concentration ranges. Calibration and sample measurements are carried out inside a temperature-constant chamber at 25 C and in an inert atmosphere (N{sub 2}). The detection and quantification limits of the method, evaluated as 3 and 10 times the standard deviation of a series of measurements of the matrix solution were 2.9 and 9.6 {mu}mol/kg of CO{sub 2}, respectively. Data quality for dissolved inorganic carbon was checked with replicate measurements of a certified reference material (A. Dickson, Scripps Institution of Oceanography, University of California, San Diego), both accuracy and repeatability were -3.3% and 10%, respectively. Optimization, performance qualification of the system and its application in various natural water samples are reported and discussed. In the future, the calibration step will be operated automatically in order to improve the analytical performance and the applicability will be increased in the course of experimental surveys carried out both in marine and freshwater ecosystems. Considering the present stage of

  19. Speciative determination of total V and dissolved inorganic vanadium species in environmental waters by catalytic–kinetic spectrophotometric method

    Directory of Open Access Journals (Sweden)

    Ramazan Gürkan

    2017-02-01

    Full Text Available A kinetic determination of V(V as a catalyst was spectrophotometrically performed by using the indicator reaction of Gallamine blue (GB+ and bromate at pH 2.0. The reaction was followed by measuring absorbance change for a fixed-time of 3 min at 537 nm. The variables such as reagent concentration, pH, buffer concentration, ionic strength and temperature were optimized to improve the selectivity and sensitivity. Under the optimized conditions, the determination of V(V was performed in the range 1–100 μg L−1 with limits of detection and quantification of 0.31 and 0.94 μg L−1. The developed kinetic method is sufficiently sensitive, selective and simple. It was successfully applied to the speciative determination of total V and inorganic dissolved vanadium species, V(V and V(IV in environmental water samples. The oxidizing property of permanganate is used to differentiate between V(IV and V(V species. The V(IV content was found by subtracting the V(V content from those of total V. The recovery is above 95% for V(V spiked samples. Additionally, the accuracy was validated by analysis of a certified water sample, CRM TMDA-53.3, and the results were in good agreement with the certified value.

  20. A Synthesis of Light Absorption Properties of the Arctic Ocean: Application to Semi-analytical Estimates of Dissolved Organic Carbon Concentrations from Space

    Science.gov (United States)

    Matsuoka, A.; Babin, M.; Doxaran, D.; Hooker, S. B.; Mitchell, B. G.; Belanger, S.; Bricaud, A.

    2014-01-01

    The light absorption coefficients of particulate and dissolved materials are the main factors determining the light propagation of the visible part of the spectrum and are, thus, important for developing ocean color algorithms. While these absorption properties have recently been documented by a few studies for the Arctic Ocean [e.g., Matsuoka et al., 2007, 2011; Ben Mustapha et al., 2012], the datasets used in the literature were sparse and individually insufficient to draw a general view of the basin-wide spatial and temporal variations in absorption. To achieve such a task, we built a large absorption database at the pan-Arctic scale by pooling the majority of published datasets and merging new datasets. Our results showed that the total non-water absorption coefficients measured in the Eastern Arctic Ocean (EAO; Siberian side) are significantly higher 74 than in the Western Arctic Ocean (WAO; North American side). This higher absorption is explained 75 by higher concentration of colored dissolved organic matter (CDOM) in watersheds on the Siberian 76 side, which contains a large amount of dissolved organic carbon (DOC) compared to waters off 77 North America. In contrast, the relationship between the phytoplankton absorption (a()) and chlorophyll a (chl a) concentration in the EAO was not significantly different from that in the WAO. Because our semi-analytical CDOM absorption algorithm is based on chl a-specific a() values [Matsuoka et al., 2013], this result indirectly suggests that CDOM absorption can be appropriately erived not only for the WAO but also for the EAO using ocean color data. Derived CDOM absorption values were reasonable compared to in situ measurements. By combining this algorithm with empirical DOC versus CDOM relationships, a semi-analytical algorithm for estimating DOC concentrations for coastal waters at the Pan-Arctic scale is presented and applied to satellite ocean color data.

  1. Temporal evolution of cadmium, copper and lead concentration in the Venice Lagoon water in relation with the speciation and dissolved/particulate partition.

    Science.gov (United States)

    Morabito, Elisa; Radaelli, Marta; Corami, Fabiana; Turetta, Clara; Toscano, Giuseppa; Capodaglio, Gabriele

    2018-04-01

    In order to study the role of sediment re-suspension and deposition versus the role of organic complexation, we investigated the speciation of cadmium (Cd), copper (Cu) and lead (Pb) in samples collected in the Venice Lagoon during several campaigns from 1992 to 2006. The increment in Cd and Pb concentration in the dissolved phases, observed in the central and northern basins, can be linked to important alterations inside the lagoon caused by industrial and urban factors. The study focuses on metal partition between dissolved and particulate phases. The analyses carried out in different sites illustrate the complex role of organic matter in the sedimentation process. While Cd concentration in sediments can be correlated with organic matter, no such correlation can be established in the case of Pb, whose particulate concentration is related only to the dissolved concentration. In the case of Cu, the role of organic complexation remains unclear. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Estimating dissolved organic carbon concentration in turbid coastal waters using optical remote sensing observations

    Science.gov (United States)

    Cherukuru, Nagur; Ford, Phillip W.; Matear, Richard J.; Oubelkheir, Kadija; Clementson, Lesley A.; Suber, Ken; Steven, Andrew D. L.

    2016-10-01

    Dissolved Organic Carbon (DOC) is an important component in the global carbon cycle. It also plays an important role in influencing the coastal ocean biogeochemical (BGC) cycles and light environment. Studies focussing on DOC dynamics in coastal waters are data constrained due to the high costs associated with in situ water sampling campaigns. Satellite optical remote sensing has the potential to provide continuous, cost-effective DOC estimates. In this study we used a bio-optics dataset collected in turbid coastal waters of Moreton Bay (MB), Australia, during 2011 to develop a remote sensing algorithm to estimate DOC. This dataset includes data from flood and non-flood conditions. In MB, DOC concentration varied over a wide range (20-520 μM C) and had a good correlation (R2 = 0.78) with absorption due to coloured dissolved organic matter (CDOM) and remote sensing reflectance. Using this data set we developed an empirical algorithm to derive DOC concentrations from the ratio of Rrs(412)/Rrs(488) and tested it with independent datasets. In this study, we demonstrate the ability to estimate DOC using remotely sensed optical observations in turbid coastal waters.

  3. Coupling loss characteristics of runoff-sediment-adsorbed and dissolved nitrogen and phosphorus on bare loess slope.

    Science.gov (United States)

    Wu, Lei; Qiao, Shanshan; Peng, Mengling; Ma, Xiaoyi

    2018-05-01

    Soil and nutrient loss is a common natural phenomenon but it exhibits unclear understanding especially on bare loess soil with variable rainfall intensity and slope gradient, which makes it difficult to design control measures for agricultural diffuse pollution. We employ 30 artificial simulated rainfalls (six rainfall intensities and five slope gradients) to quantify the coupling loss correlation of runoff-sediment-adsorbed and dissolved nitrogen and phosphorus on bare loess slope. Here, we show that effects of rainfall intensity on runoff yield was stronger than slope gradient with prolongation of rainfall duration, and the effect of slope gradient on runoff yield reduced gradually with increased rainfall intensity. But the magnitude of initial sediment yield increased significantly from an average value of 6.98 g at 5° to 36.08 g at 25° with increased slope gradient. The main factor of sediment yield would be changed alternately with the dual increase of slope gradient and rainfall intensity. Dissolved total nitrogen (TN) and dissolved total phosphorus (TP) concentrations both showed significant fluctuations with rainfall intensity and slope gradient, and dissolved TP concentration was far less than dissolved TN. Under the double influences of rainfall intensity and slope gradient, adsorbed TN concentration accounted for 7-82% of TN loss concentration with an average of 58.6% which was the main loss form of soil nitrogen, adsorbed TP concentration accounted for 91.8-98.7% of TP loss concentration with an average of 96.6% which was also the predominant loss pathway of soil phosphorus. Nitrate nitrogen (NO 3 - -N) accounted for 14.59-73.92% of dissolved TN loss, and ammonia nitrogen (NH 4 + -N) accounted for 1.48-18.03%. NO 3 - -N was the main loss pattern of TN in runoff. Correlation between dissolved TN, runoff yield, and rainfall intensity was obvious, and a significant correlation was also found between adsorbed TP, sediment yield, and slope gradient. Our

  4. Nutrient Concentrations in Upper and Lower Echo, Fallen Leaf, Spooner, and Marlette Lakes and Associated Outlet Streams, California and Nevada, 2002-03

    National Research Council Canada - National Science Library

    2004-01-01

    .... Water samples were collected to determine seasonal and spatial concentrations of dissolved nitrite plus nitrate, dissolved ammonia, total Kjeldahl nitrogen, dissolved orthophosphate, total phosphorus...

  5. Fast concentration of dissolved forms of cesium radioisotopes from large seawater samples

    International Nuclear Information System (INIS)

    Jan Kamenik; Henrieta Dulaiova; Ferdinand Sebesta; Kamila St'astna; Czech Technical University, Prague

    2013-01-01

    The method developed for cesium concentration from large freshwater samples was tested and adapted for analysis of cesium radionuclides in seawater. Concentration of dissolved forms of cesium in large seawater samples (about 100 L) was performed using composite absorbers AMP-PAN and KNiFC-PAN with ammonium molybdophosphate and potassium–nickel hexacyanoferrate(II) as active components, respectively, and polyacrylonitrile as a binding polymer. A specially designed chromatography column with bed volume (BV) 25 mL allowed fast flow rates of seawater (up to 1,200 BV h -1 ). The recovery yields were determined by ICP-MS analysis of stable cesium added to seawater sample. Both absorbers proved usability for cesium concentration from large seawater samples. KNiFC-PAN material was slightly more effective in cesium concentration from acidified seawater (recovery yield around 93 % for 700 BV h -1 ). This material showed similar efficiency in cesium concentration also from natural seawater. The activity concentrations of 137 Cs determined in seawater from the central Pacific Ocean were 1.5 ± 0.1 and 1.4 ± 0.1 Bq m -3 for an offshore (January 2012) and a coastal (February 2012) locality, respectively, 134 Cs activities were below detection limit ( -3 ). (author)

  6. Influences of observation method, season, soil depth, land use and management practice on soil dissolvable organic carbon concentrations: A meta-analysis.

    Science.gov (United States)

    Li, Siqi; Zheng, Xunhua; Liu, Chunyan; Yao, Zhisheng; Zhang, Wei; Han, Shenghui

    2018-08-01

    Quantifications of soil dissolvable organic carbon concentrations, together with other relevant variables, are needed to understand the carbon biogeochemistry of terrestrial ecosystems. Soil dissolvable organic carbon can generally be grouped into two incomparable categories. One is soil extractable organic carbon (EOC), which is measured by extracting with an aqueous extractant (distilled water or a salt solution). The other is soil dissolved organic carbon (DOC), which is measured by sampling soil water using tension-free lysimeters or tension samplers. The influences of observation methods, natural factors and management practices on the measured concentrations, which ranged from 2.5-3970 (mean: 69) mg kg -1 of EOC and 0.4-200 (mean: 12) mg L -1 of DOC, were investigated through a meta-analysis. The observation methods (e.g., extractant, extractant-to-soil ratio and pre-treatment) had significant effects on EOC concentrations. The most significant divergence (approximately 109%) occurred especially at the extractant of potassium sulfate (K 2 SO 4 ) solutions compared to distilled water. As EOC concentrations were significantly different (approximately 47%) between non-cultivated and cultivated soils, they were more suitable than DOC concentrations for assessing the influence of land use on soil dissolvable organic carbon levels. While season did not significantly affect EOC concentrations, DOC concentrations showed significant differences (approximately 50%) in summer and autumn compared to spring. For management practices, applications of crop residues and nitrogen fertilizers showed positive effects (approximately 23% to 91%) on soil EOC concentrations, while tillage displayed negative effects (approximately -17%), compared to no straw, no nitrogen fertilizer and no tillage. Compared to no nitrogen, applications of synthetic nitrogen also appeared to significantly enhance DOC concentrations (approximately 32%). However, further studies are needed in the future

  7. Trends in concentrations of nitrate and total dissolved solids in public supply wells of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins, San Bernardino County, California: influence of legacy land use.

    Science.gov (United States)

    Kent, Robert; Landon, Matthew K

    2013-05-01

    Concentrations and temporal changes in concentrations of nitrate and total dissolved solids (TDS) in groundwater of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins of the Upper Santa Ana Valley Groundwater Basin were evaluated to identify trends and factors that may be affecting trends. One hundred, thirty-one public-supply wells were selected for analysis based on the availability of data spanning at least 11 years between the late 1980s and the 2000s. Forty-one of the 131 wells (31%) had a significant (p<0.10) increase in nitrate and 14 wells (11%) had a significant decrease in nitrate. For TDS, 46 wells (35%) had a significant increase and 8 wells (6%) had a significant decrease. Slopes for the observed significant trends ranged from -0.44 to 0.91 mg/L/yr for nitrate (as N) and -8 to 13 mg/L/yr for TDS. Increasing nitrate trends were associated with greater well depth, higher percentage of agricultural land use, and being closer to the distal end of the flow system. Decreasing nitrate trends were associated with the occurrence of volatile organic compounds (VOCs); VOC occurrence decreases with increasing depth. The relations of nitrate trends to depth, lateral position, and VOCs imply that increasing nitrate concentrations are associated with nitrate loading from historical agricultural land use and that more recent urban land use is generally associated with lower nitrate concentrations and greater VOC occurrence. Increasing TDS trends were associated with relatively greater current nitrate concentrations and relatively greater amounts of urban land. Decreasing TDS trends were associated with relatively greater amounts of natural land use. Trends in TDS concentrations were not related to depth, lateral position, or VOC occurrence, reflecting more complex factors affecting TDS than nitrate in the study area. Published by Elsevier B.V.

  8. A synthesis of light absorption properties of the Pan-Arctic Ocean: application to semi-analytical estimates of dissolved organic carbon concentrations from space

    Science.gov (United States)

    Matsuoka, A.; Babin, M.; Doxaran, D.; Hooker, S. B.; Mitchell, B. G.; Bélanger, S.; Bricaud, A.

    2013-11-01

    The light absorption coefficients of particulate and dissolved materials are the main factors determining the light propagation of the visible part of the spectrum and are, thus, important for developing ocean color algorithms. While these absorption properties have recently been documented by a few studies for the Arctic Ocean (e.g., Matsuoka et al., 2007, 2011; Ben Mustapha et al., 2012), the datasets used in the literature were sparse and individually insufficient to draw a general view of the basin-wide spatial and temporal variations in absorption. To achieve such a task, we built a large absorption database at the pan-Arctic scale by pooling the majority of published datasets and merging new datasets. Our results showed that the total non-water absorption coefficients measured in the Eastern Arctic Ocean (EAO; Siberian side) are significantly higher than in the Western Arctic Ocean (WAO; North American side). This higher absorption is explained by higher concentration of colored dissolved organic matter (CDOM) in watersheds on the Siberian side, which contains a large amount of dissolved organic carbon (DOC) compared to waters off North America. In contrast, the relationship between the phytoplankton absorption (aφ(λ)) and chlorophyll a (chl a) concentration in the EAO was not significantly different from that in the WAO. Because our semi-analytical CDOM absorption algorithm is based on chl a-specific aφ(λ) values (Matsuoka et al., 2013), this result indirectly suggests that CDOM absorption can be appropriately derived not only for the WAO but also for the EAO using ocean color data. Derived CDOM absorption values were reasonable compared to in situ measurements. By combining this algorithm with empirical DOC vs. CDOM relationships, a semi-analytical algorithm for estimating DOC concentrations for coastal waters at the Pan-Arctic scale is presented and applied to satellite ocean color data.

  9. Shifts in Rumen Fermentation and Microbiota Are Associated with Dissolved Ruminal Hydrogen Concentrations in Lactating Dairy Cows Fed Different Types of Carbohydrates.

    Science.gov (United States)

    Wang, Min; Wang, Rong; Xie, Tian Yu; Janssen, Peter H; Sun, Xue Zhao; Beauchemin, Karen A; Tan, Zhi Liang; Gao, Min

    2016-09-01

    Different carbohydrates ingested greatly influence rumen fermentation and microbiota and gaseous methane emissions. Dissolved hydrogen concentration is related to rumen fermentation and methane production. We tested the hypothesis that carbohydrates ingested greatly alter the rumen environment in dairy cows, and that dissolved hydrogen concentration is associated with these changes in rumen fermentation and microbiota. Twenty-eight lactating Chinese Holstein dairy cows [aged 4-5 y, body weight 480 ± 37 kg (mean ± SD)] were used in a randomized complete block design to investigate effects of 4 diets differing in forage content (45% compared with 35%) and source (rice straw compared with a mixture of rice straw and corn silage) on feed intake, rumen fermentation, and microbial populations. Feed intake (10.7-12.6 kg/d) and fiber degradation (0.584-0.692) greatly differed (P ≤ 0.05) between cows fed the 4 diets, leading to large differences (P ≤ 0.05) in gaseous methane yield (27.2-37.3 g/kg organic matter digested), dissolved hydrogen (0.258-1.64 μmol/L), rumen fermentation products, and microbiota. Ruminal dissolved hydrogen was negatively correlated (r 0.40; P Ruminal dissolved hydrogen was positively correlated (r = 0.93; P ruminal dissolved hydrogen in lactating dairy cows. An unresolved paradox was that greater dissolved hydrogen was associated with greater numbers of methanogens but with lower gaseous methane emissions. © 2016 American Society for Nutrition.

  10. Summary of Dissolved Concentration Limits

    International Nuclear Information System (INIS)

    Yueting Chen

    2001-01-01

    According to the Technical Work Plan titled Technical Work Plan for Waste Form Degradation Process Model Report for SR (CRWMS M and O 2000a), the purpose of this study is to perform abstractions on solubility limits of radioactive elements based on the process-level information and thermodynamic databases provided by Natural Environment Program Operations (NEPO) and Waste Package Operations (WPO). The scope of this analysis is to produce solubility limits as functions, distributions, or constants for all transported radioactive elements identified by the Performance Assessment Operations (PAO) radioisotope screening. Results from an expert elicitation for solubility limits of most radioactive elements were used in the previous Total System Performance Assessments (TSPAs). However, the elicitation conducted in 1993 does not meet the criteria set forth by the U.S. Nuclear Regulatory Commission (NRC) due to lack of documentation and traceability (Kotra et al. 1996, Section 3). Therefore, at the Waste Form Abstraction Workshop held on February 2-4, 1999, at Albuquerque, New Mexico, the Yucca Mountain Site Characterization Project (YMP) decided to develop geochemical models to study solubility for the proposed Monitored Geologic Repository. WPO/NEPO is to develop process-level solubility models, including review and compilation of relevant thermodynamic data. PAO's responsibility is to perform abstractions based on the process models and chemical conditions and to produce solubility distributions or response surfaces applicable to the proposed repository. The results of this analysis and conceptual model will feed the performance assessment for Total System Performance Assessment--Site Recommendation (TSPA-SR) and Total System Performance Assessment--License Application (TSPA-LA), and to the Waste Form Degradation Process Model Report section on concentration limits

  11. Summary of Dissolved Concentration Limits

    Energy Technology Data Exchange (ETDEWEB)

    Yueting Chen

    2001-06-11

    According to the Technical Work Plan titled Technical Work Plan for Waste Form Degradation Process Model Report for SR (CRWMS M&O 2000a), the purpose of this study is to perform abstractions on solubility limits of radioactive elements based on the process-level information and thermodynamic databases provided by Natural Environment Program Operations (NEPO) and Waste Package Operations (WPO). The scope of this analysis is to produce solubility limits as functions, distributions, or constants for all transported radioactive elements identified by the Performance Assessment Operations (PAO) radioisotope screening. Results from an expert elicitation for solubility limits of most radioactive elements were used in the previous Total System Performance Assessments (TSPAs). However, the elicitation conducted in 1993 does not meet the criteria set forth by the U.S. Nuclear Regulatory Commission (NRC) due to lack of documentation and traceability (Kotra et al. 1996, Section 3). Therefore, at the Waste Form Abstraction Workshop held on February 2-4, 1999, at Albuquerque, New Mexico, the Yucca Mountain Site Characterization Project (YMP) decided to develop geochemical models to study solubility for the proposed Monitored Geologic Repository. WPO/NEPO is to develop process-level solubility models, including review and compilation of relevant thermodynamic data. PAO's responsibility is to perform abstractions based on the process models and chemical conditions and to produce solubility distributions or response surfaces applicable to the proposed repository. The results of this analysis and conceptual model will feed the performance assessment for Total System Performance Assessment--Site Recommendation (TSPA-SR) and Total System Performance Assessment--License Application (TSPA-LA), and to the Waste Form Degradation Process Model Report section on concentration limits.

  12. An intercomparison experiment on isotope dilution thermal ionisation mass spectrometry using plutonium-239 spike for the determination of plutonium concentration in dissolver solution of irradiated fuel

    International Nuclear Information System (INIS)

    Aggarwal, S.K.; Shah, P.M.; Saxena, M.K.; Jain, H.C.; Gurba, P.B.; Babbar, R.K.; Udagatti, S.V.; Moorthy, A.D.; Singh, R.K.; Bajpai, D.D.

    1996-01-01

    Determination of plutonium concentration in the dissolver solution of irradiated fuel is one of the key measurements in the nuclear fuel cycle. This report presents the results of an intercomparison experiment performed between Fuel Chemistry Division (FCD) at BARC and PREFRE, Tarapur for determining plutonium concentration in dissolver solution of irradiated fuel using 239 Pu spike in isotope dilution thermal ionisation mass spectrometry (ID-TIMS). The 239 Pu spike method was previously established at FCD as viable alternative to the imported enriched 242 Pu or 244 Pu; the spike used internationally for plutonium concentration determination by IDMS in dissolver solution of irradiated fuel. Precision and accuracy achievable for determining plutonium concentration are compared under the laboratory and the plant conditions using 239 Pu spike in IDMS. For this purpose, two different dissolver solutions with 240 Pu/ 239 Pu atom ratios of about 0.3 and 0.07 corresponding, respectively, to high and low burn-up fuels, were used. The results of the intercomparison experiment demonstrate that there is no difference in the precision values obtained under the laboratory and the plant conditions; with mean precision values of better than 0.2%. Further, the plutonium concentration values determined by the two laboratories agreed within 0.3%. This exercise, therefore, demonstrates that ID-TIMS method using 239 Pu spike can be used for determining plutonium concentration in dissolver solution of irradiated fuel, under the plant conditions. 7 refs., 8 tabs

  13. Method of dissolving metal ruthenium

    International Nuclear Information System (INIS)

    Tsuno, Masao; Soda, Yasuhiko; Kuroda, Sadaomi; Koga, Tadaaki.

    1988-01-01

    Purpose: To dissolve and clean metal ruthenium deposited to the inner surface of a dissolving vessel for spent fuel rods. Method: Metal ruthenium is dissolved in a solution of an alkali metal hydroxide to which potassium permanganate is added. As the alkali metal hydroxide used herein there can be mentioned potassium hydroxide, sodium hydroxide and lithium hydroxide can be mentioned, which is used as an aqueous solution from 5 to 20 % concentration in view of the solubility of metal ruthenium and economical merit. Further, potassium permanganate is used by adding to the solution of alkali metal hydroxide at a concentration of 1 to 5 %. (Yoshihara, H.)

  14. Lowering of the critical concentration for micelle formation in aqueous soap solutions by action of truly dissolved hydrocarbon at various temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Markina, Z.N.; Kostova, N.Z.; Rebinder, P.A.

    1970-03-01

    The effect of dissolved hydrocarbons (octane, benzene, and ethylbenzene) on critical micelle concentration of aqueous solutions of sodium salts of fatty acids from caproate to sodium myristate at various temperatures was studied. Experimental results showed that formation of micelles is promoted by presence of hydrocarbons dissolved in the water phase. Such solutions have below normal critical micelle concentration. The change in critical micelle concentration decreases with increase in length of hydrocarbon chain in the soap molecule and with decrease of hydrocarbon solubility in pure water. The nature of the hydrocarbon also affects the forms and dimension of the micelle. Aromatic hydrocarbons increase micelle volume and greatly decrease C.M.C., while aliphatic hydrocarbons decrease C.M.C. slightly. (12 refs.)

  15. Analysis of dissolved organic carbon concentration and 13C isotopic signature by TOC-IRMS - assessment of analytical performance

    Science.gov (United States)

    Kirkels, Frédérique; Cerli, Chiara; Federherr, Eugen; Kalbitz, Karsten

    2013-04-01

    Stable carbon isotopes provide a powerful tool to assess carbon pools and their dynamics. Dissolved organic carbon (DOC) has been recognized to play an important role in ecosystem functioning and carbon cycling and has therefore gained increased research interest. However, direct measurement of 13C isotopic signature of carbon in the dissolved phase is technically challenging particularly using high temperature combustion. Until recently, mainly custom-made systems existed which were modified for coupling of TOC instruments with IRMS for simultaneous assessment of C content and isotopic signature. The variety of coupled systems showed differences in their analytical performances. For analysis of DOC high temperature combustion is recognized as best performing method, owing to its high efficiency of conversion to CO2 also for highly refractory components (e.g. humic, fulvic acids) present in DOC and soil extracts. Therefore, we tested high temperature combustion TOC coupled to IRMS (developed by Elementar Group) for bulk measurements of DOC concentration and 13C signature. The instruments are coupled via an Interface to exchange the carrier gas from O2 to He and to concentrate the derived CO2 for the isotope measurement. Analytical performance of the system was assessed for a variety of organic compounds characterized by different stability and complexity, including humic acid and DOM. We tested injection volumes between 0.2-3 ml, thereby enabling measurement of broad concentration ranges. With an injection volume of 0.5 ml (n=3, preceded by 1 discarded injection), DOC and 13C signatures for concentrations between 5-150 mg C/L were analyzed with high precision (standard deviation (SD) predominantly TOC-IRMS in comparison with other systems capable of determining C concentration and isotopic signatures. We recognize the advantages of this system providing: - High sample throughput, short measurement time (15 minutes), flexible sample volume - Easy maintenance

  16. Concentration and distribution of dissolved amino acids in a shallow hydrothermal system, Vulcano Island (Italy)

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, E.; Skoog, A. [University of Connecticut, Groton, CT (United States). Dept. of Marine Sciences; Amend, J.P. [Washington University, St. Louis, MO (United States). Dept. of Earth and Planetary Sciences

    2004-09-01

    Hydrothermal systems are known to harbour a large number of microorganisms, but the organic chemical composition of the solution that comprises their potential substrate is largely unknown. Concentrations and distributions of dissolved free amino acids (DFAA) and dissolved combined amino acids (DCAA) were determined in fluids from the moderate-temperature (42-89{sup o}C), shallow hydrothermal system on the volcanically active island of Vulcano, Italy. The seven samples represent three different geological settings on the island; shallow ({approx} 1 m) submarine vents, geothermal wells, and seeps in heated beach sediments, in addition to ambient local seawater from the bay, Baia di Levante. All hydrothermal sites, with one exception, had TDAA concentrations that were 3-114 times higher than local seawater in Baia di Levante. There were large similarities in amino acid concentration and composition among samples from the same geological setting. The highest amino acid concentrations were found at sites with acidic and reducing conditions, which also had the largest freshwater component. An unusually high fraction of the TDAA pool was represented by DFAA (33-87%), possibly due to in situ acid hydrolysis of DCAA to DFAA. Both DFAA and DCAA concentrations were correlated to DOC, indicating similar source and sink functions for these pools. The yield of TDAA (TDAA-carbon as fraction of organic carbon) ranged from 2% to 25%, which is high compared with non-hydrothermal settings, and indicates high biological lability. The mole fraction of {beta}-alanine plus {gamma}-aminobutyric acid (% BALA + GABA) was 2-2.7% of TDAA, also indicating high biological lability. Owing to the high over-all amino acid concentrations, the high fraction of DFAAs, and the high biological lability of the organic matter, organic matter in general and amino acids specifically could represent significant carbon and energy sources for archaea and bacteria in this hydrothermal system. The clear

  17. Influence of the adipate and dissolved oxygen concentrations on the beta-lactam production during continuous cultivations of a Penicillium chrysogenum strain expressing the expandase gene from Streptomyces clavuligerus

    DEFF Research Database (Denmark)

    Robin, Jarno Jacky Christian; Bonneau, S.; Schipper, D.

    2003-01-01

    The influence of adipate concentration and dissolved oxygen on production of adipoyl-7-aminodeacetoxycephalosporanic acid (ad-7-ADCA) by a recombinant strain of Penicillium chrysogenum expressing the expandase gene from Streptomyces clavuligerus was studied in glucose-limited continuous cultures....... from 15 to 7%AS, r(p) (total) increased to 25 mumol g DW-1 h(-1), mainly due to a two-fold increase in the adipoyl-6-aminopenicillanic acid (ad-6-APA) specific productivity....

  18. Titanium distribution in swimming pool water is dominated by dissolved species

    International Nuclear Information System (INIS)

    David Holbrook, R.; Motabar, Donna; Quiñones, Oscar; Stanford, Benjamin; Vanderford, Brett; Moss, Donna

    2013-01-01

    The increased use of titanium dioxide nanoparticles (nano-TiO 2 ) in consumer products such as sunscreen has raised concerns about their possible risk to human and environmental health. In this work, we report the occurrence, size fractionation and behavior of titanium (Ti) in a children's swimming pool. Size-fractionated samples were analyzed for Ti using ICP-MS. Total titanium concentrations ([Ti]) in the pool water ranged between 21 μg/L and 60 μg/L and increased throughout the 101-day sampling period while [Ti] in tap water remained relatively constant. The majority of [Ti] was found in the dissolved phase (<1 kDa), with only a minor fraction of total [Ti] being considered either particulate or microparticulate. Simple models suggest that evaporation may account for the observed variation in [Ti], while sunscreen may be a relevant source of particulate and microparticule Ti. Compared to diet, incidental ingestion of nano-Ti from swimming pool water is minimal. -- Highlights: •Total titanium concentrations in unfiltered swimming pool water ranged between 21 and 60 μg/L. •Evaporation of the swimming pool water is suspected of causing a temporal increase in [Ti]. •The vast majority of Ti is found in the dissolved phase (<1 kD). •Swimming pools are not a significant Ti source for human exposure via ingestion. -- In children's swimming pool water, the majority of titanium is found in the dissolved phase

  19. Growth response of four freshwater algal species to dissolved organic nitrogen of different concentration and complexity

    DEFF Research Database (Denmark)

    Fiedler, Dorothea; Graeber, Daniel; Badrian, Maria

    2015-01-01

    1. Dissolved organic nitrogen (DON) compounds dominate the nitrogen pool of many lakes, but their importance as nitrogen sources for freshwater phytoplankton is not fully understood. Previous growth experiments demonstrated the availability of urea and amino acids but often at unnaturally high...... (DCAA), natural organic matter (NOM)) or with nitrate as the sole nitrogen source. Monocultures of Chlamydomonas spp., Cyclotella meneghiniana, Microcystis aeruginosa and Anabaena flos-aquae were incubated with dissolved nitrogen compounds at concentrations ranging from 0.01 to 0.5 mg N L−1, which...... and their compound preferences. Therefore, DON composition can influence biomass and structure of phytoplankton communities. 6. These experiments demonstrate the importance of the main DON compounds for phytoplankton growth when no inorganic nitrogen is available. DON should in future be included in nitrogen budget...

  20. Crossed Optical Fiber Sensor Arrays for High-Spatial-Resolution Sensing: Application to Dissolved Oxygen Concentration Measurements

    Directory of Open Access Journals (Sweden)

    M. Veronica Rigo

    2012-01-01

    Full Text Available Optical fiber sensors using luminescent probes located along an optical fiber in the cladding of this fiber are of great interest for monitoring physical and chemical properties in their environment. The interrogation of a luminophore with a short laser pulse propagating through the fiber core allows for the measurement of the location of these luminophores. To increase the spatial resolution of such a measurements and to measure multiple analytes and properties in a confined space, a crossed optical fiber sensing platform can be employed. Here we describe the application of this platform to measuring the concentration of dissolved oxygen. The sensor is based on luminescence quenching of a ruthenium complex immobilized in a highly crosslinked film and covalently attached to the optical fibers. Both luminescence-intensity and luminescence-lifetime changes of the sensor molecules in response to changes in the concentration of oxygen dissolved in water are reported. For luminescence-intensity measurements, a second adjacent sensor region is employed as reference to account for laser pulse energy fluctuations. Enhanced quenching response in water is demonstrated by the use of organically modified poly(ethylene glycol precursors, which increase the hydrophobicity of the film surface.

  1. Tertiary treatment of textile wastewater with combined media biological aerated filter (CMBAF) at different hydraulic loadings and dissolved oxygen concentrations

    International Nuclear Information System (INIS)

    Liu Fang; Zhao Chaocheng; Zhao Dongfeng; Liu Guohua

    2008-01-01

    An up-flow biological aerated filter packed with two layers media was employed for tertiary treatment of textile wastewater secondary effluent. Under steady state conditions, good performance of the reactor was achieved and the average COD, NH 4 + -N and total nitrogen (TN) in the effluent were 31, 2 and 8 mg/L, respectively. For a fixed dissolved oxygen (DO) concentration, an increase of hydraulic loading resulted in a decrease in substrate removal. With the increase of hydraulic loadings from 0.13 to 0.78 m 3 /(m 2 h), the removal efficiencies of COD, NH 4 + -N and TN all decreased, which dropped from 52 to 38%, from 90 to 68% and from 45 to 33%, respectively. In addition, the results also confirmed that the increase of COD and NH 4 + -N removal efficiencies resulted from the increase of DO concentrations, but this variation trend was not observed for TN removal. With the increase of DO concentrations from 2.4 to 6.1 mg/L, the removal efficiencies of COD and NH 4 + -N were 39-53% and 64-88%, whenas TN removal efficiencies increased from 39 to 42% and then dropped to 35%

  2. An extensive study of the concentrations of particulate/dissolved radiocaesium derived from the Fukushima Dai-ichi Nuclear Power Plant accident in various river systems and their relationship with catchment inventory

    International Nuclear Information System (INIS)

    Yoshimura, Kazuya; Onda, Yuichi; Sakaguchi, Aya; Yamamoto, Masayoshi; Matsuura, Yuki

    2015-01-01

    An extensive investigation of particulate radiocaesium in suspended solids and dissolved radiocaesium in river water was undertaken at 30 sites in Fukushima and Miyagi Prefectures in December 2012, and their relationships with catchment inventory and the solid/liquid distribution coefficient (K d ) were evaluated. Rivers located in the coastal region on the north side of the Fukushima Dai-ichi Nuclear Power Plant exhibited relatively higher particulate radiocaesium concentrations. Significant correlations were found between concentrations of particulate/dissolved radiocaesium and average catchment inventories, indicating that the concentrations of particulate/dissolved radiocaesium could be approximated from the catchment inventory. Particulate radiocaesium concentration was significantly correlated with dissolved radiocaesium concentration (with the exception of concentrations measured in estuaries), and the geometric mean K d was calculated as 3.6 × 10 5 with a 95% confidence interval of 2.6–5.1 × 10 5 . - Highlights: • Particulate radiocaesium concentration correlated with catchment inventory. • Particulate size can be an important factor of the correlation. • Solid/liquid distribution coefficients were obtained for extensive area

  3. Using total suspended solids (TSS) and turbidity as proxies for evaluation of metal transport in river water

    International Nuclear Information System (INIS)

    Nasrabadi, T.; Ruegner, H.; Sirdari, Z.Z.; Schwientek, M.; Grathwohl, P.

    2016-01-01

    The present study was carried out in Haraz basin (Iran) that is located in south of the Caspian Sea. The goal of this study was to establish correlations amongst total suspended solids concentration (TSS) and turbidity with total pollutant concentrations to evaluate the dissolved and particle-bound concentrations of major toxic metals. It also aimed to validate TSS and/or turbidity measurements as proxies to monitor pollutant fluxes. Eight metals, namely nickel, lead, cadmium, copper, zinc, cobalt, arsenic and strontium were analyzed for dissolved and total concentrations in water at ten locations within the catchment. TSS and turbidity were also measured. Sampling campaigns were designed to cover both the rainy (December) and the dry (May) season within the basin. The robust relationship between TSS (202–1212 mg/l) and turbidity (63–501 NTUs) in both seasons warranted their interchangeable potential as proxies within the observed ranges. Total element concentrations were plotted in separate attempts versus TSS and turbidity for all locations and both events. Very good linear correlations were attained where the slopes represent the metals concentration on suspended solids and the intercept the dissolved concentration in water. The results achieved by these linear regressions were in very good agreement with independently measured values for dissolved concentration and concentrations on river bed sediments taken at the same locations. This demonstrates that turbidity and/or TSS measurements may be used for monitoring of metal loads if once calibrated against total concentration of metals. The results also revealed that in the lower Haraz catchment metal concentrations on suspended and river bed sediment were homogeneously distributed along the investigated river stretch. This is assumed to be due to intensive gravel and sand mining activities in the upper and middle part of the catchment. - Highlights: • Turbidity is evaluated as a feasible proxy to predict

  4. Estimation of Freely-Dissolved Concentrations of Polychlorinated Biphenyls, 2,3,7,8-Substituted Congeners and Homologs of Polychlorinated dibenzo-p-dioxins and Dibenzofurans in Water for Development of Total Maximum Daily Loadings for the Bluestone River Watershed, Virginia and West Virginia

    Science.gov (United States)

    Gale, Robert W.

    2007-01-01

    The Commonwealth of Virginia Department of Environmental Quality, working closely with the State of West Virginia Department of Environmental Protection and the U.S. Environmental Protection Agency is undertaking a polychlorinated biphenyl source assessment study for the Bluestone River watershed. The study area extends from the Bluefield area of Virginia and West Virginia, targets the Bluestone River and tributaries suspected of contributing to polychlorinated biphenyl, polychlorinated dibenzo-p-dioxin and dibenzofuran contamination, and includes sites near confluences of Big Branch, Brush Fork, and Beaver Pond Creek. The objectives of this study were to gather information about the concentrations, patterns, and distribution of these contaminants at specific study sites to expand current knowledge about polychlorinated biphenyl impacts and to identify potential new sources of contamination. Semipermeable membrane devices were used to integratively accumulate the dissolved fraction of the contaminants at each site. Performance reference compounds were added prior to deployment and used to determine site-specific sampling rates, enabling estimations of time-weighted average water concentrations during the deployed period. Minimum estimated concentrations of polychlorinated biphenyl congeners in water were about 1 picogram per liter per congener, and total concentrations at study sites ranged from 130 to 18,000 picograms per liter. The lowest concentration was 130 picograms per liter, about threefold greater than total hypothetical concentrations from background levels in field blanks. Polychlorinated biphenyl concentrations in water fell into three groups of sites: low (130-350 picogram per liter); medium (640-3,500 picogram per liter; and high (11,000-18,000 picogram per liter). Concentrations at the high sites, Beacon Cave and Beaverpond Branch at the Resurgence, were about four- to sixfold higher than concentrations estimated for the medium group of sites

  5. Identification of dissolved-constituent sources in mine-site ground water using batch mixing

    International Nuclear Information System (INIS)

    Clark, G.M.; Williams, R.S. Jr.

    1991-01-01

    Batch-mixing experiments were used to help identify lithologic mineralogic sources of increased concentrations of dissolved solids in water affected by surface coal mining in northwestern Colorado. Ten overburden core samples were analyzed for mineral composition and mixed with distilled water for 90 days until mineral-water equilibrium was reached. Dissolved-solids concentrations ranged from 200 to 8,700 mg/L in water samples extracted from the mixtures after 90 days. Mass-balance simulations were conducted using the geochemical models BALANCE and WATEQF to quantify mineral-water interactions occurring in five selected sample mixtures and in water collected from a spring at a reclaimed mine site. The spring water is affected by mineral-water interactions occurring in all of lithologic units comprising the overburden. Results of the simulations indicate that oxidation of pyrite, dissolution of dolomite, gypsum, and epsomite, and cation-exchange reactions are the primary mineral-water interactions occurring in the overburden. Three lithologic units in the overburden probably contribute most of the dissolved solids to the spring water. Water sample extracts from mixtures using core from these three units accounted for 85 percent of the total dissolved solids in the 10 sample extracts. Other lithologic units in the overburden probably contribute smaller quantities of dissolved solids to the spring water

  6. Diel production and microheterotrophic utilization of dissolved free amino acids in waters off southern California

    International Nuclear Information System (INIS)

    Carlucci, A.F.; Craven, D.B.; Henrichs, S.M.

    1984-01-01

    Diel patterns of dissolved free amino acid (DFAA) concentration and microheterotrophic utilization were examined in the spring and fall of 1981 in euphotic waters from the base of the mixed layer off the southern California coast. The average depths of the isotherms sampled were 19.2 m for spring and 9.0 for fall. Total DFAA levels were generally higher in the spring than in the fall, 18 to 66 nM and 14 to 20 nM, respectively. Two daily concentration maxima and minima were observed for total DFAAs as well as for most individual DFAAs. Maxima were usually measured in the mid-dark period and in the early afternoon; minima were typically observed in early morning and late afternoon. Bacterial cell numbers reached maximal values near midnight in both seasons. The increases coincided with one of the total DFAA maxima. The second total DFAA maximum occurred in early to midafternoon, during the time of maximum photosynthetic carbon production and rapid dissolved amino acid utilization. Microbial metabolism (incorporation plus respiration) of selected 3 H-amino acids was 2.7 to 4.1 times greater during the daylight hours. DFAA turnover times, based on these metabolic measurements, ranged between 11 and 36 h for the amino acids tested, and rates were 1.7 to 3.7 times faster in the daylight hours than at night. DFAA distributions were related to primary production and chlorophyll a concentrations. Amino acids were estimated to represent 9 to 45% of the total phytoplankton exudate. Microheterotrophic utilization or production of total protein amino acids was estimated as 3.6 μg of C liter -1 day -1 in spring and 1.9 μg of C liter -1 day -1 in the fall. Assimilation efficiency for dissolved amino acids averaged 65% for marine microheterotrophs

  7. Dissolved gaseous mercury formation and mercury volatilization in intertidal sediments.

    Science.gov (United States)

    Cesário, Rute; Poissant, Laurier; Pilote, Martin; O'Driscoll, Nelson J; Mota, Ana M; Canário, João

    2017-12-15

    Intertidal sediments of Tagus estuary regularly experiences complex redistribution due to tidal forcing, which affects the cycling of mercury (Hg) between sediments and the water column. This study quantifies total mercury (Hg) and methylmercury (MMHg) concentrations and fluxes in a flooded mudflat as well as the effects on water-level fluctuations on the air-surface exchange of mercury. A fast increase in dissolved Hg and MMHg concentrations was observed in overlying water in the first 10min of inundation and corresponded to a decrease in pore waters, suggesting a rapid export of Hg and MMHg from sediments to the water column. Estimations of daily advective transport exceeded the predicted diffusive fluxes by 5 orders of magnitude. A fast increase in dissolved gaseous mercury (DGM) concentration was also observed in the first 20-30min of inundation (maximum of 40pg L -1 ). Suspended particulate matter (SPM) concentrations were inversely correlated with DGM concentrations. Dissolved Hg variation suggested that biotic DGM production in pore waters is a significant factor in addition to the photochemical reduction of Hg. Mercury volatilization (ranged from 1.1 to 3.3ngm -2 h -1 ; average of 2.1ngm -2 h -1 ) and DGM production exhibited the same pattern with no significant time-lag suggesting a fast release of the produced DGM. These results indicate that Hg sediment/water exchanges in the physical dominated estuaries can be underestimated when the tidal effect is not considered. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. On-line technique for preparingand measuring stable carbon isotopeof total dissolved inorganic carbonin water samples ( d13CTDIC

    Directory of Open Access Journals (Sweden)

    S. Inguaggiato

    2005-06-01

    Full Text Available A fast and completely automated procedure is proposed for the preparation and determination of d13C of total inorganic carbon dissolved in water ( d13CTDIC. This method is based on the acidification of water samples transforming the whole dissolved inorganic carbon species into CO2. Water samples are directly injected by syringe into 5.9 ml vials with screw caps which have a pierciable rubber septum. An Analytical Precision «Carbonate Prep System» was used both to flush pure helium into the vials and to automatically dispense a fixed amount of H3PO4. Full-equilibrium conditions between produced CO2 and water are reached at a temperature of 70°C (± 0.1°C in less than 24 h. Carbon isotope ratios (13C/ 12C were measured on an AP 2003 continuous flow mass spectrometer, connected on-line with the injection system. The precision and reproducibility of the proposed method was tested both on aqueous standard solutions prepared using Na2CO3 with d13C=-10.78 per mil versus PDB (1 s= 0.08, n = 11, and at five different concentrations (2, 3, 4, 5 and 20 mmol/l and on more than thirty natural samples. Mean d13CTDIC on standard solution samples is ?10.89 < per mil versus PDB (1 s= 0.18, n = 50, thus revealing both a good analytical precision and reproducibility. A comparison between average d13CTDIC values on a quadruplicate set of natural samples and those obtained following the chemical and physical stripping method highlights a good agreement between the two analytical methods.

  9. Subcooled boiling effect on dissolved gases behaviour

    International Nuclear Information System (INIS)

    Zmitko, M.; Sinkule, J.; Linek, V.

    1999-01-01

    A model describing dissolved gasses (hydrogen, nitrogen) and ammonia behaviour in subcooled boiling conditions of WWERs was developed. Main objective of the study was to analyse conditions and mechanisms leading to formation of a zone with different concentration of dissolved gases, eg. a zone depleted in dissolved hydrogen in relation to the bulk of coolant. Both, an equilibrium and dynamic approaches were used to describe a depletion of the liquid surrounding a steam bubble in the gas components. The obtained results show that locally different water chemistry conditions can be met in the subcooled boiling conditions, especially, in the developed subcooled boiling regime. For example, a 70% hydrogen depletion in relation to the bulk of coolant takes about 1 ms and concerns a liquid layer of 1 μn surrounding the steam bubble. The locally different concentration of dissolved gases can influence physic-chemical and radiolytic processes in the reactor system, eg. Zr cladding corrosion, radioactivity transport and determination of the critical hydrogen concentration. (author)

  10. Variation of dissolved organic nitrogen concentration during the ultrasonic pretreatment to Microcystis aeruginosa.

    Science.gov (United States)

    Liu, Cheng; Wang, Jie; Cao, Zhen; Chen, Wei; Bi, Hongkai

    2016-03-01

    Algae cells were the main sources of dissolved organic nitrogen (DON) in raw water with plenty of algae, and ultrasonic pretreatment was one of the algae-controlling methods through the damage of algae cells. However, the variation of DON concentration during the ultrasonic treatment process was not confirmed. Variation of DON concentration during the processes of low frequency ultrasound treatment of Microcystis aeruginosa was investigated. In addition, the effect of sonication on the metabolite concentration, algae cellar activity and the subsequent coagulation performance were discussed. The results showed that after a long duration of ultrasonic (60 s), nearly 90% of the algal cells were damaged and the maximum concentration of DON attained more than 3 mg/L. In order to control the leakage extent of DON, the sonication time should be less than 30 s with power intensity of more than 1.0 W/cm(3). In the mean time, ultrasonic treatment could inhibit the reactivation and the proliferation of algal, keep the algae cell wall integrity and enhance coagulation effectively under the same condition. However, ultrasound frequency had little effect on DON at the frequency range used in this study (20-150 kHz). Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Analyzing Solutions High in Total Dissolved Solids for Rare Earth Elements (REEs) Using Cation Exchange and Online Pre-Concentration with the seaFAST2 Unit; NETL-TRS-7-2017; NETL Technical Report Series; U.S. Department of Energy, National Energy Technology Laboratory: Albany, OR, 2017; p 32

    Energy Technology Data Exchange (ETDEWEB)

    Yang, J. [National Energy Technology Lab. (NETL), Albany, OR (United States); Oregon State Univ., Corvallis, OR (United States). College of Earth, Ocean, and Atmospheric Science; Torres, M. [Oregon State Univ., Corvallis, OR (United States). College of Earth, Ocean, and Atmospheric Science; Verba, C. [National Energy Technology Lab. (NETL), Albany, OR (United States); Oregon State Univ., Corvallis, OR (United States); Hakala, A. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

    2017-08-01

    The accurate quantification of the rare earth element (REE) dissolved concentrations in natural waters are often inhibited by their low abundances in relation to other dissolved constituents such as alkali, alkaline earth elements, and dissolved solids. The high abundance of these constituents can suppress the overall analytical signal as well as create isobaric interferences on the REEs during analysis. Waters associated with natural gas operations on black shale plays are characterized by high salinities and high total dissolved solids (TDS) contents >150,000 mg/L. Methods used to isolate and quantify dissolved REEs in seawater were adapted in order to develop the capability of analyzing REEs in waters that are high in TDS. First, a synthetic fluid based on geochemical modelling of natural brine formation fluids was created within the Marcellus black shale with a TDS loading of 153,000 mg/L. To this solution, 1,000 ng/mL of REE standards was added based on preliminary analyses of experimental fluids reacted at high pressure and temperature with Marcellus black shale. These synthetic fluids were then run at three different dilution levels of 10, 100, and 1,000–fold dilutions through cation exchange columns using AG50-X8 exchange resin from Eichrom Industries. The eluent from the cation columns were then sent through a seaFAST2 unit directly connected to an inductively coupled plasma mass spectrometer (ICP-MS) to analyze the REEs. Percent recoveries of the REEs ranged from 80–110% and fell within error for the external reference standard used and no signal suppression or isobaric interferences on the REEs were observed. These results demonstrate that a combined use of cation exchange columns and seaFAST2 instrumentation are effective in accurately quantifying the dissolved REEs in fluids that are >150,000 mg/L in TDS and have Ba:Eu ratios in excess of 380,000.

  12. Using disposable solid-phase microextraction (SPME) to determine the freely dissolved concentration of polybrominated diphenyl ethers (PBDEs) in sediments

    International Nuclear Information System (INIS)

    Jia Fang; Cui Xinyi; Wang Wei; Delgado-Moreno, Laura; Gan, Jay

    2012-01-01

    Polybrominated diphenyl ethers (PBDEs) are brominated flame retardants (BFRs). The ubiquity and persistence of PBDEs in sediment have raised concerns over their environmental fate and ecological risks. Due to strong affinity for sediment organic matter, environmental fate and bioavailability of PBDEs closely depend on their phase distribution. In this study, disposable polydimethylsiloxane (PDMS) fiber was used to derive the freely dissolved concentration (C free ) of PBDEs in sediment porewater as a measurement of bioavailability. The PDMS-to-water partition coefficient (log K PDMS ) was 5.46–5.83 for BDE 47, 99, and 153. In sediments, PBDEs were predominantly sorbed to the sediment phase, with C free accounting for free of PBDEs decreased as their bromination or sediment organic carbon content increased. The strong association with dissolved organic matter (DOM) implies a potential for facilitated offsite transport and dispersion in the environment that depends closely on the stability of sediment aggregates. - Highlights: ► A disposable SPME method was developed for measuring C free of PBDEs in sediment. ► C free decreased with increasing congener bromination or sediment OC content. ► C free of PBDEs accounted for DOC values suggest a high probability for DOM-facilitated offsite transport. - A SPME method based on disposable PDMS fibers was developed for measuring the freely dissolved concentration of PBDEs (C free ) in sediment porewater.

  13. Correlation between DNAPL distribution area and dissolved concentration in surfactant enhanced aquifer remediation effluent: a two-dimensional flow cell study

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Bin; Li, Huiying; Du, Xiaoming; Zhong, Lirong; Yang, Bin; Du, Ping; Gu, Qingbao; Li, Fasheng

    2016-02-01

    During the process of surfactant enhanced aquifer remediation (SEAR), free phase dense non-aqueous phase liquid (DNAPL) may be mobilized and spread. The understanding of the impact of DNAPL spreading on the SEAR remediation is not sufficient with its positive effect infrequently mentioned. To evaluate the correlation between DNAPL spreading and remediation efficiency, a two-dimensional sandbox apparatus was used to simulate the migration and dissolution process of 1,2-DCA (1,2-dichloroethane) DNAPL in SEAR. Distribution area of DNAPL in the sandbox was determined by digital image analysis and correlated with effluent DNAPL concentration. The results showed that the effluent DNAPL concentration has significant positive linear correlation with the DNAPL distribution area, indicating the mobilization of DNAPL could improve remediation efficiency by enlarging total NAPL-water interfacial area for mass transfer. Meanwhile, the vertical migration of 1,2-DCA was limited within the boundary of aquifer in all experiments, implying that by manipulating injection parameters in SEAR, optimal remediation efficiency can be reached while the risk of DNAPL vertical migration is minimized. This study provides a convenient visible and quantitative method for the optimization of parameters for SEAR project, and an approach of rapid predicting the extent of DNAPL contaminant distribution based on the dissolved DNAPL concentration in the extraction well.

  14. Spatiotemporal variation characteristics and related affecting factors of dissolved carbohydrates in the East China Sea

    Science.gov (United States)

    He, Zhen; Wang, Qi; Yang, Gui-Peng; Gao, Xian-Chi; Wu, Guan-Wei

    2015-10-01

    Carbohydrates are the largest identified fraction of dissolved organic carbon and play an important role in biogeochemical cycling in the ocean. Seawater samples were collected from the East China Sea (ECS) during June and October 2012 to study the spatiotemporal distributions of total dissolved carbohydrates (TCHOs) constituents, including dissolved monosaccharides (MCHOs) and polysaccharides (PCHOs). The concentrations of TCHOs, MCHOs and PCHOs showed significant differences between summer and autumn 2012, and exhibited an evident diurnal variation, with high values occurring in the daytime. Phytoplankton biomass was identified as the primary factor responsible for seasonal and diurnal variations of dissolved carbohydrates in the ECS. The TCHOs, MCHOs and PCHOs distributions in the study area displayed similar distribution patterns, with high concentrations appearing in the coastal water. The influences of chlorophyll-a, salinity and nutrients on the distributions of these carbohydrates were examined. A carbohydrate enrichment in the near-bottom water was found at some stations, implying that there might be an important source of carbohydrate in the deep water or bottom sediment.

  15. Influences of dissolved oxygen concentration on biocathodic microbial communities in microbial fuel cells.

    Science.gov (United States)

    Rago, Laura; Cristiani, Pierangela; Villa, Federica; Zecchin, Sarah; Colombo, Alessandra; Cavalca, Lucia; Schievano, Andrea

    2017-08-01

    Dissolved oxygen (DO) at cathodic interface is a critical factor influencing microbial fuel cells (MFC) performance. In this work, three MFCs were operated with cathode under different DO conditions: i) air-breathing (A-MFC); ii) water-submerged (W-MFC) and iii) assisted by photosynthetic microorganisms (P-MFC). A plateau of maximum current was reached at 1.06±0.03mA, 1.48±0.06mA and 1.66±0.04mA, increasing respectively for W-MFC, P-MFC and A-MFC. Electrochemical and microbiological tools (Illumina sequencing, confocal microscopy and biofilm cryosectioning) were used to explore anodic and cathodic biofilm in each MFC type. In all cases, biocathodes improved oxygen reduction reaction (ORR) as compared to abiotic condition and A-MFC was the best performing system. Photosynthetic cultures in the cathodic chamber supplied high DO level, up to 16mg O2 L -1 , which sustained aerobic microbial community in P-MFC biocathode. Halomonas, Pseudomonas and other microaerophilic genera reached >50% of the total OTUs. The presence of sulfur reducing bacteria (Desulfuromonas) and purple non-sulfur bacteria in A-MFC biocathode suggested that the recirculation of sulfur compounds could shuttle electrons to sustain the reduction of oxygen as final electron acceptor. The low DO concentration limited the cathode in W-MFC. A model of two different possible microbial mechanisms is proposed which can drive predominantly cathodic ORR. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Influence of land cover on riverine dissolved organic carbon concentrations and export in the Three Rivers Headwater Region of the Qinghai-Tibetan Plateau.

    Science.gov (United States)

    Ma, Xiaoliang; Liu, Guimin; Wu, Xiaodong; Smoak, Joseph M; Ye, Linlin; Xu, Haiyan; Zhao, Lin; Ding, Yongjian

    2018-07-15

    The Qinghai-Tibetan plateau (QTP) stores a large amount of soil organic carbon and is the headwater region for several large rivers in Asia. Therefore, it is important to understand the influence of environmental factors on river water quality and the dissolved organic carbon (DOC) export in this region. We examined the water physico-chemical characteristics, DOC concentrations and export rates of 7 rivers under typical land cover types in the Three Rivers Headwater Region during August 2016. The results showed that the highest DOC concentrations were recorded in the rivers within the catchment of alpine wet meadow and meadow. These same rivers had the lowest total suspended solids (TSS) concentrations. The rivers within steppe and desert had the lowest DOC concentrations and highest TSS concentrations. The discharge rates and catchment areas were negatively correlated with DOC concentrations. The SUVA 254 values were significantly negatively correlated with DOC concentrations. The results suggest that the vegetation degradation, which may represent permafrost degradation, can lead to a decrease in DOC concentration, but increasing DOC export and soil erosion. In addition, some of the exported DOC will rapidly decompose in the river, and therefore affect the regional carbon cycle, as well as the water quality in the source water of many large Asian rivers. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. Dissolved Vanillin as Tracer for Estuarine Lignin Conversion

    Science.gov (United States)

    Edelkraut, F.

    1996-12-01

    Lignin is produced only by vascular plants and therefore can be used as a tracer for terrestrial organic carbon input to the estuarine and marine environments. Lignin measurements have been done by analyses of the oxidation products such as vanillin or 4-hydroxybenzaldehyde. In the Elbe Estuary, free dissolved vanillin was analysed in order to test whether such measurements yield information on terrestrial carbon inputs into the Estuary and on the vanillin derived from lignin oxidation. In the period 1990-1992, concentrations of dissolved vanillin in the Elbe ranged from 0 to 60 μ g l -1(mean: 8 μg l -1). Higher values were found in areas of increased microbial activity such as the turbidity zone and the river mouth where the water chemistry is influenced by large tidal flats. No correlation was found between dissolved vanillin and suspended matter concentrations, although lignin is normally associated with suspended particulate matter, nor was a covariance seen between dissolved vanillin and the terrestrial carbon inputs into the Estuary. Apparently, biological conversion of lignin was faster than the transport processes, and local sources were more dominant for the vanillin concentration than riverine sources. The dissolved vanillin turnover was fast and, consequently, a significant amount of lignin may be converted within an estuary. In sediments from the Estuary, the concentrations of dissolved vanillin were similar to those found in the water phase and showed no clear vertical profile. The sediment is unlikely to be the source for vanillin.

  18. Dissolved black carbon in the global cryosphere: Concentrations and chemical signatures

    Science.gov (United States)

    Khan, Alia L.; Wagner, Sasha; Jaffe, Rudolf; Xian, Peng; Williams, Mark; Armstrong, Richard; McKnight, Diane

    2017-06-01

    Black carbon (BC) is derived from the incomplete combustion of biomass and fossil fuels and can enhance glacial recession when deposited on snow and ice surfaces. Here we explore the influence of environmental conditions and the proximity to anthropogenic sources on the concentration and composition of dissolved black carbon (DBC), as measured by benzenepolycaroxylic acid (BPCA) markers, across snow, lakes, and streams from the global cryosphere. Data are presented from Antarctica, the Arctic, and high alpine regions of the Himalayas, Rockies, Andes, and Alps. DBC concentrations spanned from 0.62 μg/L to 170 μg/L. The median and (2.5, 97.5) quantiles in the pristine samples were 1.8 μg/L (0.62, 12), and nonpristine samples were 21 μg/L (1.6, 170). DBC is susceptible to photodegradation when exposed to solar radiation. This process leads to a less condensed BPCA signature. In general, DBC across the data set was composed of less polycondensed DBC. However, DBC from the Greenland Ice Sheet (GRIS) had a highly condensed BPCA molecular signature. This could be due to recent deposition of BC from Canadian wildfires. Variation in DBC appears to be driven by a combination of photochemical processing and the source combustion conditions under which the DBC was formed. Overall, DBC was found to persist across the global cryosphere in both pristine and nonpristine snow and surface waters. The high concentration of DBC measured in supraglacial melt on the GRIS suggests that DBC can be mobilized across ice surfaces. This is significant because these processes may jointly exacerbate surface albedo reduction in the cryosphere.Plain Language SummaryHere we present dissolved black carbon (DBC) results for snow and glacial melt systems in Antarctica, the Arctic, and high alpine regions of the Himalayas, Rockies, Andes, and Alps. Across the global cryosphere, DBC composition appears to be a result of photochemical processes occurring en route in the atmosphere or in situ on the

  19. Assessment of dissolved-selenium concentrations and loads in the lower Gunnison River Basin, Colorado, as part of the Selenium Management Program, from 2011 to 2016

    Science.gov (United States)

    Henneberg, Mark F.

    2018-04-23

    The Gunnison Basin Selenium Management Program implemented a water-quality monitoring network in 2011 in the lower Gunnison River Basin in Colorado. Selenium is a trace element that bioaccumulates in aquatic food chains and can cause reproductive failure, deformities, and other harmful effects. This report presents the percentile values of selenium because regulatory agencies in Colorado make decisions based on the U.S. Environmental Protection Agency (EPA) Clean Water Act Section 303(d) that uses percentile values of concentration. Also presented are dissolved-selenium loads at 18 sites in the lower Gunnison River Basin for water years (WYs) 2011–2016 (October 1, 2010, through September 30, 2016). Annual dissolved-selenium loads were calculated for five sites with continuous U.S. Geological Survey (USGS) streamflow-gaging stations. Annual dissolved-selenium loads for WY 2011 through WY 2016 ranged from 179 and 391 pounds (lb) at Uncompahgre River at Colona to 11,100 and 17,300 lb at Gunnison River near Grand Junction (herein called Whitewater), respectively. Instantaneous loads were calculated for five sites with continuous U.S. Geological Survey (USGS) streamflow-gaging stations and 13 ancillary sites where discrete water-quality sampling also took place, using discrete water-quality samples and the associated discharge measurements collected during the period. Median instantaneous loads ranged from 0.01 pound per day (lb/d) at Smith Fork near Lazear to 33.0 lb/d at Whitewater. Mean instantaneous loads ranged from 0.06 lb/d at Smith Fork near Lazear to 36.2 lb/d at Whitewater. Most tributary sites in the basin had a median instantaneous dissolved-selenium load of less than 20.0 lb/day. In general, dissolved-selenium loads at Gunnison River main-stem sites showed an increase from upstream to downstream. The State of Colorado water-quality standard for dissolved selenium of 4.6 micrograms per liter (µg/L) was compared to the 85th percentiles for dissolved

  20. Watershed scale spatial variability in dissolved and total organic and inorganic carbon in contrasting UK catchments

    Science.gov (United States)

    Cumberland, S.; Baker, A.; Hudson, N. J.

    2006-12-01

    Approximately 800 organic and inorganic carbon analyses have been undertaken from watershed scale and regional scale spatial surveys in various British catchments. These include (1) a small (urban catchment (Ouseburn, N England); (2) a headwater, lowland agricultural catchment (River Tern, C England) (3) a large UK catchment (River Tyne, ~3000 sq-km) and (4) a spatial survey of ~300 analyses from rivers from SW England (~1700 sq-km). Results demonstrate that: (1) the majority of organic and inorganic carbon is in the dissolved (DOC and DIC) fractions; (2) that with the exception of peat rich headwaters, DIC concentration is always greater than DOC; (3) In the rural River Tern, riverine DOC and DIC are shown to follow a simple end- member mixing between DIC (DOC) rich (poor) ground waters and DOC (DIC) rich (poor) riparian wetlands for all sample sites. (4) In the urbanized Ouseburn catchment, although many sample sites also show this same mixing trend, some tributaries follow a pollutant trend of simultaneous increases in both DOC and DIC. The Ouseburn is part of the larger Tyne catchment: this larger catchment follows the simple groundwater DIC- soil water DOC end member mixing model, with the exception of the urban catchments which exhibit an elevated DIC compared to rural sites. (5) Urbanization is demonstrated to increase DIC compared to equivalent rural catchments; this DIC has potential sources including diffuse source inputs from the dissolution of concrete, point sources such as trade effluents and landfill leachates, and bedrock derived carbonates relocated to the soil dissolution zone by urban development. (6) DIC in rural SW England demonstrates that spatial variability in DIC can be attributed to variations in geology; but that DIC concentrations in the SW England rivers dataset are typically lower than the urbanized Tyne catchments despite the presence of carbonate bedrock in many of the sample catchments in the SW England dataset. (7) Recent

  1. Forecasting models for flow and total dissolved solids in Karoun river-Iran

    Science.gov (United States)

    Salmani, Mohammad Hassan; Salmani Jajaei, Efat

    2016-04-01

    Water quality is one of the most important factors contributing to a healthy life. From the water quality management point of view, TDS (total dissolved solids) is the most important factor and many water developing plans have been implemented in recognition of this factor. However, these plans have not been perfect and very successful in overcoming the poor water quality problem, so there are a good volume of related studies in the literature. We study TDS and the water flow of the Karoun river in southwest Iran. We collected the necessary time series data from the Harmaleh station located in the river. We present two Univariate Seasonal Autoregressive Integrated Movement Average (ARIMA) models to forecast TDS and water flow in this river. Then, we build up a Transfer Function (TF) model to formulate the TDS as a function of water flow volume. A performance comparison between the Seasonal ARIMA and the TF models are presented.

  2. Nonimaging light concentration using total internal reflection films.

    Science.gov (United States)

    Ouellette, G; Waltham, C E; Drees, R M; Poon, A; Schubank, R; Whitehead, L A

    1992-05-01

    We present a method of fabricating nonimaging light concentrators from total internal reflection film. A prototype has been made and tested and found to operate in agreement with predictions of ray-tracing codes. The performance of the prototype is comparable with that of concentrators made from specular reflecting materials.

  3. Evaluation of leachate dissolved organic nitrogen discharge effect on wastewater effluent quality.

    Science.gov (United States)

    Bolyard, Stephanie C; Reinhart, Debra R

    2017-07-01

    Nitrogen is limited more and more frequently in wastewater treatment plant (WWTP) effluents because of the concern of causing eutrophication in discharge waters. Twelve leachates from eight landfills in Florida and California were characterized for total nitrogen (TN) and dissolved organic nitrogen (DON). The average concentration of TN and DON in leachate was approximately 1146mg/L and 40mg/L, respectively. Solid-phase extraction was used to fractionate the DON based on hydrophobic (recalcitrant fraction) and hydrophilic (bioavailable fraction) chemical properties. The average leachate concentrations of bioavailable (bDON) and recalcitrant (rDON) DON were 16.5mg/L and 18.4mg/L, respectively. The rDON fraction was positively correlated, but with a low R 2 , with total leachate apparent color dissolved UV 254 , chemical oxygen demand (COD), and humic acid (R 2 equals 0.38, 0.49, and 0.40, respectively). The hydrophobic fraction of DON (rDON) was highly colored. This fraction was also associated with over 60% of the total leachate COD. Multiple leachate and wastewater co-treatment simulations were carried out to assess the effects of leachate on total nitrogen wastewater effluent quality using removals for four WWTPs under different scenarios. The calculated pass through of DON suggests that leachate could contribute to significant amounts of nitrogen discharged to aquatic systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Estimating absorption coefficients of colored dissolved organic matter (CDOM) using a semi-analytical algorithm for southern Beaufort Sea waters: application to deriving concentrations of dissolved organic carbon from space

    Science.gov (United States)

    Matsuoka, A.; Hooker, S. B.; Bricaud, A.; Gentili, B.; Babin, M.

    2013-02-01

    A series of papers have suggested that freshwater discharge, including a large amount of dissolved organic matter (DOM), has increased since the middle of the 20th century. In this study, a semi-analytical algorithm for estimating light absorption coefficients of the colored fraction of DOM (CDOM) was developed for southern Beaufort Sea waters using remote sensing reflectance at six wavelengths in the visible spectral domain corresponding to MODIS ocean color sensor. This algorithm allows the separation of colored detrital matter (CDM) into CDOM and non-algal particles (NAP) through the determination of NAP absorption using an empirical relationship between NAP absorption and particle backscattering coefficients. Evaluation using independent datasets, which were not used for developing the algorithm, showed that CDOM absorption can be estimated accurately to within an uncertainty of 35% and 50% for oceanic and coastal waters, respectively. A previous paper (Matsuoka et al., 2012) showed that dissolved organic carbon (DOC) concentrations were tightly correlated with CDOM absorption in our study area (r2 = 0.97). By combining the CDOM absorption algorithm together with the DOC versus CDOM relationship, it is now possible to estimate DOC concentrations in the near-surface layer of the southern Beaufort Sea using satellite ocean color data. DOC concentrations in the surface waters were estimated using MODIS ocean color data, and the estimates showed reasonable values compared to in situ measurements. We propose a routine and near real-time method for deriving DOC concentrations from space, which may open the way to an estimate of DOC budgets for Arctic coastal waters.

  5. Total protein and cholesterol concentrations in brain regions of male ...

    African Journals Online (AJOL)

    The results showed similarities (P>0.05) between the treatments in total protein concentrations in the cerebral cortex, medulla, hypothalamus, amygdala, mesencephalon and hippocampus. Total protein concentrations however differed significantly between diets (P<0.05) in the cerebellum and pons varoli with the lowest ...

  6. Effect of phytoremediation on concentrations of benzene, toluene, naphthalene, and dissolved oxygen in groundwater at a former manufactured gas plant site, Charleston, South Carolina, USA, 1998–2014

    Science.gov (United States)

    Landmeyer, James E.; Effinger, Thomas N.

    2016-01-01

    Concentrations of benzene, toluene, naphthalene, and dissolved oxygen in groundwater at a former manufactured gas plant site near Charleston, South Carolina, USA, have been monitored since the installation of a phytoremediation system of hybrid poplar trees in 1998. Between 2000 and 2014, the concentrations of benzene, toluene, and naphthalene (BT&N) in groundwater in the planted area have decreased. For example, in the monitoring well containing the highest concentrations of BT&N, benzene concentrations decreased from 10,200 µg/L to less than 4000 µg/L, toluene concentrations decreased from 2420 µg/L to less than 20 µg/L, and naphthalene concentrations decreased from 6840 µg/L to less than 3000 µg/L. Concentrations of BT&N in groundwater in all wells were observed to be lower during the summer months relative to the winter months of a particular year during the first few years after installing the phytoremediation system, most likely due to increased transpiration and contaminant uptake by the hybrid poplar trees during the warm summer months; this pathway of uptake by trees was confirmed by the detection of benzene, toluene, and naphthalene in trees during sampling events in 2002, and later in the study in 2012. These data suggest that the phytoremediation system affects the groundwater contaminants on a seasonal basis and, over multiple years, has resulted in a cumulative decrease in dissolved-phase contaminant concentrations in groundwater. The removal of dissolved organic contaminants from the aquifer has resulted in a lower demand on dissolved oxygen supplied by recharge and, as a result, the redox status of the groundwater has changed from anoxic to oxic conditions. This study provides much needed information for water managers and other scientists on the viability of the long-term effectiveness of phytoremediation in decreasing groundwater contaminants and increasing dissolved oxygen at sites contaminated by benzene, toluene, and naphthalene.

  7. Feedforward-feedback control of dissolved oxygen concentration in a predenitrification system.

    Science.gov (United States)

    Yong, Ma; Yongzhen, Peng; Shuying, Wang

    2005-07-01

    As the largest single energy-consuming component in most biological wastewater treatment systems, aeration control is of great interest from the point of view of saving energy and improving wastewater treatment plant efficiency. In this paper, three different strategies, including conventional constant dissolved oxygen (DO) set-point control, cascade DO set-point control, and feedforward-feedback DO set-point control were evaluated using the denitrification layout of the IWA simulation benchmark. Simulation studies showed that the feedforward-feedback DO set-point control strategy was better than the other control strategies at meeting the effluent standards and reducing operational costs. The control strategy works primarily by feedforward control based on an ammonium sensor located at the head of the aerobic process. It has an important advantage over effluent measurements in that there is no (or only a very short) time delay for information; feedforward control was combined with slow feedback control to compensate for model approximations. The feedforward-feedback DO control was implemented in a lab-scale wastewater treatment plant for a period of 60 days. Compared to operation with constant DO concentration, the required airflow could be reduced by up to 8-15% by employing the feedforward-feedback DO-control strategy, and the effluent ammonia concentration could be reduced by up to 15-25%. This control strategy can be expected to be accepted by the operating personnel in wastewater treatment plants.

  8. Concentration, composition, bioavailability, and N-nitrosodimethylamine formation potential of particulate and dissolved organic nitrogen in wastewater effluents: A comparative study

    International Nuclear Information System (INIS)

    Hu, Haidong; Ma, Haijun; Ding, Lili; Geng, Jinju; Xu, Ke; Huang, Hui; Zhang, Yingying; Ren, Hongqiang

    2016-01-01

    Wastewater-derived organic nitrogen (org-N) can act as both nutrients and carcinogenic nitrogenous disinfection byproduct precursors. In this study, the concentration, composition, bioavailability, and N-nitrosodimethylamine (NDMA) formation potential of particulate organic nitrogen (PON) from three different municipal wastewater treatment plants were characterized and compared with that of effluent dissolved organic nitrogen (DON). The average effluent PON and DON concentrations ranged from 0.09 to 0.55 mg N/L and from 0.91 to 1.88 mg N/L, respectively. According to principal component analysis, org-N composition and characterization differed in PON and DON samples (n = 20). Compared with DON, PON tended to be enriched in protein and nucleic acids, and showed a more proteinaceous character. Composition of org-N functional groups estimated from the X-ray photoelectron spectroscopy N 1s spectra indicate no significant differences in the molecular weight distribution of the protein-like materials between PON and DON. Moreover, PON exhibited a significantly higher bioavailability (61.0 ± 13.3%) compared to DON (38.5 ± 12.4%, p < 0.05, t-test) and a significantly higher NDMA yields (791.4 ± 404.0 ng/mg-N) compared to DON (374.8 ± 62.5 ng/mg-N, p < 0.05, t-test). Accordingly, PON contributed to approximately 12.3–41.7% of the total bioavailable org-N and 22.0–38.4% of the total NDMA precursors in wastewater effluents. Thus, the potential adverse effects of PON on wastewater discharge and reuse applications should not be overlooked, even though it only accounted for 7.4–26.8% of the total effluent org-N. - Highlights: • The concentration, composition, bioavailability, and NDMA FP of PON and DON in wastewater effluents are compared. • PON is enriched in protein and nucleic acids. • PON is more bioavailable and shows higher NDMA yields compared to DON. • PON contributes12–42% of total bioavailable org-N and 22–38% of total NDMA precursors.

  9. Concentration, composition, bioavailability, and N-nitrosodimethylamine formation potential of particulate and dissolved organic nitrogen in wastewater effluents: A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Haidong; Ma, Haijun; Ding, Lili; Geng, Jinju; Xu, Ke; Huang, Hui; Zhang, Yingying; Ren, Hongqiang, E-mail: hqren@nju.edu.cn

    2016-11-01

    Wastewater-derived organic nitrogen (org-N) can act as both nutrients and carcinogenic nitrogenous disinfection byproduct precursors. In this study, the concentration, composition, bioavailability, and N-nitrosodimethylamine (NDMA) formation potential of particulate organic nitrogen (PON) from three different municipal wastewater treatment plants were characterized and compared with that of effluent dissolved organic nitrogen (DON). The average effluent PON and DON concentrations ranged from 0.09 to 0.55 mg N/L and from 0.91 to 1.88 mg N/L, respectively. According to principal component analysis, org-N composition and characterization differed in PON and DON samples (n = 20). Compared with DON, PON tended to be enriched in protein and nucleic acids, and showed a more proteinaceous character. Composition of org-N functional groups estimated from the X-ray photoelectron spectroscopy N 1s spectra indicate no significant differences in the molecular weight distribution of the protein-like materials between PON and DON. Moreover, PON exhibited a significantly higher bioavailability (61.0 ± 13.3%) compared to DON (38.5 ± 12.4%, p < 0.05, t-test) and a significantly higher NDMA yields (791.4 ± 404.0 ng/mg-N) compared to DON (374.8 ± 62.5 ng/mg-N, p < 0.05, t-test). Accordingly, PON contributed to approximately 12.3–41.7% of the total bioavailable org-N and 22.0–38.4% of the total NDMA precursors in wastewater effluents. Thus, the potential adverse effects of PON on wastewater discharge and reuse applications should not be overlooked, even though it only accounted for 7.4–26.8% of the total effluent org-N. - Highlights: • The concentration, composition, bioavailability, and NDMA FP of PON and DON in wastewater effluents are compared. • PON is enriched in protein and nucleic acids. • PON is more bioavailable and shows higher NDMA yields compared to DON. • PON contributes12–42% of total bioavailable org-N and 22–38% of total NDMA precursors.

  10. Response of dissolved carbon and nitrogen concentrations to moderate nutrient additions in a tropical montane forest of south Ecuador

    Science.gov (United States)

    Velescu, Andre; Valarezo, Carlos; Wilcke, Wolfgang

    2016-05-01

    In the past two decades, the tropical montane rain forests in south Ecuador experienced increasing deposition of reactive nitrogen mainly originating from Amazonian forest fires, while Saharan dust inputs episodically increased deposition of base metals. Increasing air temperature and unevenly distributed rainfall have allowed for longer dry spells in a perhumid ecosystem. This might have favored mineralization of dissolved organic matter (DOM) by microorganisms and increased nutrient release from the organic layer. Environmental change is expected to impact the functioning of this ecosystem belonging to the biodiversity hotspots of the Earth. In 2007, we established a nutrient manipulation experiment (NUMEX) to understand the response of the ecosystem to moderately increased nutrient inputs. Since 2008, we have continuously applied 50 kg ha-1 a-1 of nitrogen (N), 10 kg ha-1 a-1 of phosphorus (P), 50 kg + 10 kg ha-1 a-1 of N and P and 10 kg ha-1 a-1 of calcium (Ca) in a randomized block design at 2000 m a.s.l. in a natural forest on the Amazonia-exposed slopes of the south Ecuadorian Andes. Nitrogen concentrations in throughfall increased following N+P additions, while separate N amendments only increased nitrate concentrations. Total organic carbon (TOC) and dissolved organic nitrogen (DON) concentrations showed high seasonal variations in litter leachate and decreased significantly in the P and N+P treatments, but not in the N treatment. Thus, P availability plays a key role in the mineralization of DOM. TOC/DON ratios were narrower in throughfall than in litter leachate but their temporal course did not respond to nutrient amendments. Our results revealed an initially fast, positive response of the C and N cycling to nutrient additions which declined with time. TOC and DON cycling only change if N and P supply are improved concurrently, while NO3-N leaching increases only if N is separately added. This indicates co-limitation of the microorganisms by N and P

  11. Response of dissolved carbon and nitrogen concentrations to moderate nutrient additions in a tropical montane forest of south Ecuador

    Directory of Open Access Journals (Sweden)

    Andre eVelescu

    2016-05-01

    Full Text Available In the past two decades, the tropical montane rain forests in south Ecuador experienced increasing deposition of reactive nitrogen mainly originating from Amazonian forest fires, while Saharan dust inputs episodically increased deposition of base metals. Increasing air temperature and unevenly distributed rainfall have allowed for longer dry spells in a perhumid ecosystem. This might have favored mineralization of dissolved organic matter (DOM by microorganisms and increased nutrient release from the organic layer. Environmental change is expected to impact the functioning of this ecosystem belonging to the biodiversity hotspots of the Earth.In 2007, we established a nutrient manipulation experiment (NUMEX to understand the response of the ecosystem to moderately increased nutrient inputs. Since 2008, we have continuously applied 50 kg ha-1 a-1 of nitrogen (N, 10 kg ha-1 a-1 of phosphorus (P, 50 kg + 10 kg ha-1 a-1 of N and P and 10 kg ha-1 a-1 of calcium (Ca in a randomized block design at 2000 m a.s.l. in a natural forest on the Amazonia-exposed slopes of the south Ecuadorian Andes.Nitrogen concentrations in throughfall increased following N+P additions, while separate N amendments only increased nitrate concentrations. Total organic carbon (TOC and dissolved organic nitrogen (DON concentrations showed high seasonal variations in litter leachate and decreased significantly in the P and N+P treatments, but not in the N treatment. Thus, P availability plays a key role in the mineralization of DOM. TOC/DON ratios were narrower in throughfall than in litter leachate but their temporal course did not respond to nutrient amendments.Our results revealed an initially fast, positive response of the C and N cycling to nutrient additions which declined with time. TOC and DON cycling only change if N and P supply are improved concurrently, while NO3-N leaching increases only if N is separately added. This indicates co-limitation of the microorganisms by N

  12. Dissolved gases

    International Nuclear Information System (INIS)

    Heaton, T.H.E.

    1981-01-01

    The concentrations of gaseous nitrogen, argon, oxygen and helium dissolved in groundwater are often different from their concentrations in rain and surface waters. These differences reflect changes in the gas content occurring after rain or surface water, having infiltrated into the ground, become isolated from equilibrium contact with the atmosphere. A study of these changes can give insight into the origin and subsequent subsurface history of groundwater. Nitrogen and argon concentrations for many groundwaters in southern Africa indicate that excess air is added to water during infiltration. The amount of excess air is believed to reflect the physical structure of the unsaturated zone and the climate of the recharge area. Since nitrogen and argon are essentially conservative in many aquifer environments in South Africa, their concentrations can be used in distinguishing grondwaters of different recharge origins. In some areas the high helium content of the groundwater suggests that much of the helium is derived through migration from a source outside (e.g. below) the aquifer itself. Radiogenic helium concentrations nevertheless show, in two artesian aquifers, a close linear relationship to the radiocarbon age of the groundwater. This indicates a uniformity in the factors responsible for the accumulation of helium, and suggests that in these circumstances helium data can be used to give information on the age of very old groundwater. In some groundwater dissolved oxygen concentrations are found to decrease with increasing groundwater age. Whilst the rate of decrease may be very different for different aquifers, the field measurement of oxygen may be useful in preliminary surveys directed toward the location of recharge areas

  13. Release of dissolved phosphorus from riparian wetlands: Evidence for complex interactions among hydroclimate variability, topography and soil properties.

    Science.gov (United States)

    Gu, Sen; Gruau, Gérard; Dupas, Rémi; Rumpel, Cornélia; Crème, Alexandra; Fovet, Ophélie; Gascuel-Odoux, Chantal; Jeanneau, Laurent; Humbert, Guillaume; Petitjean, Patrice

    2017-11-15

    In agricultural landscapes, establishment of vegetated buffer zones in riparian wetlands (RWs) is promoted to decrease phosphorus (P) emissions because RWs can trap particulate P from upslope fields. However, long-term accumulation of P risks the release of dissolved P, since the unstable hydrological conditions in these zones may mobilize accumulated particulate P by transforming it into a mobile dissolved P species. This study evaluates how hydroclimate variability, topography and soil properties interact and influence this mobilization, using a three-year dataset of molybdate-reactive dissolved P (MRDP) and total dissolved P (TDP) concentrations in soil water from two RWs located in an agricultural catchment in western France (Kervidy-Naizin), along with stream P concentrations. Two main drivers of seasonal dissolved P release were identified: i) soil rewetting during water-table rise after dry periods and ii) reductive dissolution of soil Fe (hydr)oxides during prolonged water saturation periods. These mechanisms were shown to vary greatly in space (according to topography) and time (according to intra- and interannual hydroclimate variability). The concentration and speciation of the released dissolved P also varied spatially depending on soil chemistry and local topography. Comparison of sites revealed a similar correlation between soil P speciation (percentage of organic P ranging from 35-70%) and the concentration and speciation of the released P (MRDP from topography and soil chemistry must be considered to decrease the risk of remobilizing legacy soil P when establishing riparian buffer zones in agricultural landscapes. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Suppression of aqueous corrosion of La(Fe0.88Si0.12)13 by reducing dissolved oxygen concentration for high-performance magnetic refrigeration

    International Nuclear Information System (INIS)

    Fujieda, S.; Fukamichi, K.; Suzuki, S.

    2014-01-01

    Highlights: • The aqueous corrosion of La(Fe 0.88 Si 0.12 ) 13 and its suppression were investigated. • The lattice expansion after immersion was caused by the hydrogen absorption. • The itinerant-electron metamagnetic transition became indistinct after immersion. • The aqueous corrosion was suppressed by reducing the dissolved oxygen concentration. - Abstract: The itinerant-electron metamagnetic transition of La(Fe 0.88 Si 0.12 ) 13 becomes indistinct after immersion in distilled-water containing about 8 ppm of the dissolved oxygen (DO) concentration because of aqueous corrosion. However, the aqueous corrosion of La(Fe 0.88 Si 0.12 ) 13 is significantly suppressed by reducing the DO concentration. Thus, isothermal magnetic entropy change after immersion for 30 days in deaerated distilled-water with a DO concentration less than 0.1 ppm is larger than that after immersion for 5 days in distilled-water containing about 8 ppm of the DO concentration. Consequently, the reduction of the DO concentration is effective for preservation of the excellent magnetocaloric effects of La(Fe 0.88 Si 0.12 ) 13 in an aqueous solution, which is a promising heat transfer fluid of room-temperature magnetic refrigeration

  15. Image analyzing method to evaluate in situ bioluminescence from an obligate anaerobe cultivated under various dissolved oxygen concentrations.

    Science.gov (United States)

    Ninomiya, Kazuaki; Yamada, Ryuji; Matsumoto, Masami; Fukiya, Satoru; Katayama, Takane; Ogino, Chiaki; Shimizu, Nobuaki

    2013-02-01

    An image analyzing method was developed to evaluate in situ bioluminescence expression, without exposing the culture sample to the ambient oxygen atmosphere. Using this method, we investigated the effect of dissolved oxygen concentration on bioluminescence from an obligate anaerobe Bifidobacterium longum expressing bacterial luciferase which catalyzes an oxygen-requiring bioluminescent reaction. Copyright © 2012 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  16. Dissolved organic nitrogen recalcitrance and bioavailable nitrogen quantification for effluents from advanced nitrogen removal wastewater treatment facilities.

    Science.gov (United States)

    Fan, Lu; Brett, Michael T; Jiang, Wenju; Li, Bo

    2017-10-01

    The objective of this study was to determine the composition of nitrogen (N) in the effluents of advanced N removal (ANR) wastewater treatment plants (WWTPs). This study also tested two different experimental protocols for determining dissolved N recalcitrance. An analysis of 15 effluent samples from five WWTPs, showed effluent concentrations and especially effluent composition varied greatly from one system to the other, with total nitrogen (TN) ranging between 1.05 and 8.10 mg L -1 . Nitrate (NO 3 - ) accounted for between 38 ± 32% of TN, and ammonium accounted for a further 29 ± 28%. All of these samples were dominated by dissolved inorganic nitrogen (DIN; NO 3 -  + NH 4 + ), and uptake experiments indicated the DIN fraction was as expected highly bioavailable. Dissolved organic N (DON) accounted for 20 ± 11% for the total dissolved N in these effluents, and uptake experiments indicated the bioavailability of this fraction varied between 27 ± 26% depending on the WWTP assessed. These results indicate near complete DIN removal should be the primary goal of ANR treatment systems. The comparison of bioavailable nitrogen (BAN) quantification protocols showed that the dissolved nitrogen uptake bioassay approach was clearly a more reliable way to determine BAN concentrations compared to the conventional cell yield protocol. Moreover, because the nitrogen uptake experiment was much more sensitive, this protocol made it easier to detect extrinsic factors (such as biological contamination or toxicity) that could affect the accuracy of these bioassays. Based on these results, we recommend the nitrogen uptake bioassay using filtered and autoclaved samples to quantify BAN concentrations. However, for effluent samples indicating toxicity, algal bioassays will not accurately quantify BAN. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Simplified sample treatment for the determination of total concentrations and chemical fractionation forms of Ca, Fe, Mg and Mn in soluble coffees.

    Science.gov (United States)

    Pohl, Pawel; Stelmach, Ewelina; Szymczycha-Madeja, Anna

    2014-11-15

    A simpler, and faster than wet digestion, sample treatment was proposed prior to determination of total concentrations for selected macro- (Ca, Mg) and microelements (Fe, Mn) in soluble coffees by flame atomic absorption spectrometry. Samples were dissolved in water and acidified with HNO3. Precision was in the range 1-4% and accuracy was better than 2.5%. The method was used in analysis of 18 soluble coffees available on the Polish market. Chemical fractionation patterns for Ca, Fe, Mg and Mn in soluble coffees, as consumed, using a two-column solid-phase extraction method, determined Ca, Mg and Mn were present predominantly as cations (80-93% of total content). This suggests these elements are likely to be highly bioaccessible. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Identification of dissolved-constituent sources in mine-site ground water using batch mixing

    Science.gov (United States)

    Clark, Gregory M.; Williams, Robert S.

    1991-01-01

    Batch-mixing experiments were used to help identify lithologic and mineralogic sources of increased concentrations of dissolved solids in water affected by surface coal mining in northwestern Colorado. Ten overburden core samples were analyzed for mineral composition and mixed with distilled water for 90 days until mineral-water equilibrium was reached. Between one day and 90 days after initial contact, specific conductance in the sample mixtures had a median increase of 306 percent. Dissolved-solids concentrations ranged from 200 to 8,700 mg/L in water samples extracted from the mixtures after 90 days. Mass-balance simulations were conducted using the geochemical models BALANCE and WATEQF to quantify mineral-water interactions occurring in five selected sample mixtures and in water collected from a spring at a reclaimed mine site. The spring water is affected by mineral-water interactions occurring in all of the lithologic units comprising the overburden. Results of the simulations indicate that oxidation of pyrite, dissolution of dolomite, gypsum, and epsomite, and cation-exchange reactions are the primary mineral-water interactions occurring in the overburden. Three lithologic units in the overburden (a coal, a sandstone, and a shale) probably contribute most of the dissolved solids to the spring water. Water sample extracts from mixtures using core from these three units accounted for 85 percent of the total dissolved solids in the 10 sample extracts. Other lithologic units in the over-burden probably contribute smaller quantities of dissolved solids to the spring water.

  19. Estimating absorption coefficients of colored dissolved organic matter (CDOM) using a semi-analytical algorithm for Southern Beaufort Sea (Canadian Arctic) waters: application to deriving concentrations of dissolved organic carbon from space

    Science.gov (United States)

    Matsuoka, A.; Hooker, S. B.; Bricaud, A.; Gentili, B.; Babin, M.

    2012-10-01

    A series of papers have suggested that freshwater discharge, including a large amount of dissolved organic matter (DOM), has increased since the middle of the 20th century. In this study, a semi-analytical algorithm for estimating light absorption coefficients of the colored fraction of DOM (CDOM) was developed for Southern Beaufort Sea waters using remote sensing reflectance at six wavelengths in the visible spectral domain corresponding to MODIS ocean color sensor. This algorithm allows to separate colored detrital matter (CDM) into CDOM and non-algal particles (NAP) by determining NAP absorption using an empirical relationship between NAP absorption and particle backscattering coefficients. Evaluation using independent datasets, that were not used for developing the algorithm, showed that CDOM absorption can be estimated accurately to within an uncertainty of 35% and 50% for oceanic and turbid waters, respectively. In situ measurements showed that dissolved organic carbon (DOC) concentrations were tightly correlated with CDOM absorption (r2 = 0.97). By combining the CDOM absorption algorithm together with the DOC versus CDOM relationship, it is now possible to estimate DOC concentrations in the near-surface layer of the Southern Beaufort Sea using satellite ocean color data. DOC concentrations in the surface waters were estimated using MODIS ocean color data, and the estimates showed reasonable values compared to in situ measurements. We propose a routine and near real-time method for deriving DOC concentrations from space, which may open the way to an estimate of DOC budgets for Arctic coastal waters.

  20. Effects of different water storage procedures on the dissolved Fe concentration and isotopic composition of chemically contrasted waters from the Amazon River Basin.

    Science.gov (United States)

    Mulholland, Daniel S; Poitrasson, Franck; Boaventura, Geraldo R

    2015-11-15

    Although recent studies have investigated the Fe isotopic composition of dissolved, colloidal and particulate phases from continental and oceanic natural waters, few efforts have been made to evaluate whether water sample storage and the separation of different pore-size fractions through filtration can cause any change to the Fe isotopic compositions. The present study investigates the possible biases introduced by different water storage conditions on the dissolved Fe concentration and isotopic composition of chemically different waters. Water samples were collected from an organic-rich river and from mineral particulate-rich rivers. Filtered and unfiltered water samples were stored either at room temperature or frozen at -18°C in order to assess possible biases due to (i) different water storage temperature, and (ii) storage of bulk (unfiltered) vs filtered water. Iron isotope measurements were performed by Multicollector Inductively Coupled Plasma Mass Spectrometry with a Thermo Electron Neptune instrument, after Fe purification using anion-exchange resins. Our data reveal that bulk water storage at room temperature without filtration produces minor changes in the dissolved Fe isotopic composition of mineral particulate-rich waters, but significant isotopic composition changes in organic-rich waters. In both cases, however, the impact of the different procedures on the Fe concentrations was strong. On the other hand, the bulk water stored frozen without filtration produced more limited changes in the dissolved Fe concentrations, and also on isotopic compositions, relative to the samples filtered in the field. The largest effect was again observed for the organic-rich waters. These findings suggest that a time lag between water collection and filtration may cause isotopic exchanges between the dissolved and particulate Fe fractions. When it is not possible to filter the samples in the field immediately after collection, the less detrimental approach is to

  1. Change in lattice parameter of tantalum due to dissolved hydrogen

    Directory of Open Access Journals (Sweden)

    Gyanendra P. Tiwari

    2012-06-01

    Full Text Available The volume expansion of tantalum due to the dissolved hydrogen has been determined using Bragg equation. The hydrogen was dissolved in the pure tantalum metal at constant temperature (360 °C and constant pressure (132 mbar by varying the duration of hydrogen charging. The amount of dissolved hydrogen was within the solid solubility limit. The samples with different hydrogen concentration were analyzed by X-ray diffraction technique. Slight peak shifts as well as peak broadening were observed. The relative changes of lattice parameters plotted against the hydrogen concentration revealed that the lattice parameters varied linearly with the hydrogen concentration.

  2. Zinc, copper and lead contents of wines. Comparison between the total concentrations by atomic absorption spectrometry and the concentrations of the free ions by polarography

    Directory of Open Access Journals (Sweden)

    J.-B. Fournier

    1998-03-01

    Full Text Available In the introduction of this article, some examples of the use of trace element data in the characterisation of viticultural produce are reminded. This paper described the determination of zinc, copper and lead by two techniques based on radically different principles. The atomic absorption spectrometry, applied after the mineralisation of the samples by wet process, allows the determination of the total element contents in wine. The polarography allows the analysis of the concentrations of these elements that are under labile chemical forms, and which are dissolved under the ionic forms Zn++, Cu++ and Pb++. The wines analysed in this study were produced from three different parcels chosen in relation to their geological qualities. The vines implanted on these parcels are strictly identical, and three fermentation techniques were applied to each lots of grapes. The results obtained shows that the copper is only under ionic form and that the temperature of the fermentation influences the total copper level in the final wine. At the opposite, there is no ion Pb++ in the samples, but a long duration of maceration increases the lead content. Concerning zinc, only the ions Zn++ are present in the wine in case of a short duration of the maceration. When this duration increases, some other chemical forms of zinc are dissolved in addition to the ions Zn++ which are instantaneously dissociated in aqueous solutions. The problem of the contamination of grapes by the materials used, the phytosanitary treatments and the atmospheric pollution is discussed. The knowledge of the proportion of a trace element that is under ionic forms is indispensable to evaluate the bio-availability of the considered element and the toxicologic risks. The advent and the expansion of the electrochemical methods is expected as an important advance in this field of research.

  3. Declines in the dissolved organic carbon (DOC) concentration and flux from the UK

    Science.gov (United States)

    Worrall, Fred; Howden, Nicholas J. K.; Burt, Tim P.; Bartlett, Rebecca

    2018-01-01

    Increased concentrations of dissolved organic carbon (DOC) have been reported for many catchments across the northern hemisphere. Hypotheses to explain the increase have varied (eg. increasing air temperature or recovery from acidification) but one test of alternative hypotheses is the trend over the recent decade, with the competing hypotheses predicting: continuing increase; the rate of increase declining with time; and even decrease in concentration. In this study, records of DOC concentration in non-tidal rivers across the UK were examined for the period 2003-2012. The study found that: Of the 62 decade-long concentration trends that could be examined, 3 showed a significant increase, 17 experienced no significant change and 42 showed a significant decrease; in 28 of the 42 significant decreases, a significant step change was apparent with step changes being a decrease in concentration in every case. Of the 118 sites where annual flux and concentration records were available from 1974, 28 showed a significant step change down in flux and 52 showed a step down in concentration. The modal year of the step changes was 2000 with no step changes observed before 1982. At the UK national scale, DOC flux peaked in 2005 at 1354 ktonnes C/yr (5.55 tonnes C/km2/yr) but has declined since. The study suggests that there is a disconnection between DOC records from large catchments at their tidal limits and complementary records from headwater catchments, which means that mechanisms believed to be driving increases in DOC concentrations in headwaters will not necessarily be those controlling trends in DOC concentration further downstream. We propose that the changes identified here have been driven by changes in in-stream processing and changes brought about by the Urban Waste Water Treatment Directive. Therefore, signals identified in headwater catchments may bear little relation to those observed in large rivers much further downstream and vice versa.

  4. Dissolved methane concentration and flux in the coastal zone of the Southern California Bight-Mexican sector: Possible influence of wastewater

    Science.gov (United States)

    We measured dissolved methane concentrations ([CH4]) in the coastal zone of the Southern California Bight-Mexican sector (SCBMex) during two cruises: S1 in the USA–Mexico Border Area (BA) during a short rainstorm and S2 in the entire SCBMex during a drier period a few days later....

  5. Estimating absorption coefficients of colored dissolved organic matter (CDOM using a semi-analytical algorithm for southern Beaufort Sea waters: application to deriving concentrations of dissolved organic carbon from space

    Directory of Open Access Journals (Sweden)

    A. Matsuoka

    2013-02-01

    Full Text Available A series of papers have suggested that freshwater discharge, including a large amount of dissolved organic matter (DOM, has increased since the middle of the 20th century. In this study, a semi-analytical algorithm for estimating light absorption coefficients of the colored fraction of DOM (CDOM was developed for southern Beaufort Sea waters using remote sensing reflectance at six wavelengths in the visible spectral domain corresponding to MODIS ocean color sensor. This algorithm allows the separation of colored detrital matter (CDM into CDOM and non-algal particles (NAP through the determination of NAP absorption using an empirical relationship between NAP absorption and particle backscattering coefficients. Evaluation using independent datasets, which were not used for developing the algorithm, showed that CDOM absorption can be estimated accurately to within an uncertainty of 35% and 50% for oceanic and coastal waters, respectively. A previous paper (Matsuoka et al., 2012 showed that dissolved organic carbon (DOC concentrations were tightly correlated with CDOM absorption in our study area (r2 = 0.97. By combining the CDOM absorption algorithm together with the DOC versus CDOM relationship, it is now possible to estimate DOC concentrations in the near-surface layer of the southern Beaufort Sea using satellite ocean color data. DOC concentrations in the surface waters were estimated using MODIS ocean color data, and the estimates showed reasonable values compared to in situ measurements. We propose a routine and near real-time method for deriving DOC concentrations from space, which may open the way to an estimate of DOC budgets for Arctic coastal waters.

  6. [Effects of nitrogen deposition on the concentration and spectral characteristics of dissolved organic matter in soil solution in a young Cunninghamia lanceolata plantation.

    Science.gov (United States)

    Yuan, Xiao Chun; Chen, Yue Min; Yuan, Shuo; Zheng, Wei; Si, You Tao; Yuan, Zhi Peng; Lin, Wei Sheng; Yang, Yu Sheng

    2017-01-01

    To study the effects of nitrogen deposition on the concentration and spectral characteristics of dissolved organic matter (DOM) in the forest soil solution from the subtropical Cunninghamia lanceolata plantation, using negative pressure sampling method, the dynamics of DOM in soil solutions from 0-15 and 15-30 cm soil layer was monitored for two years and the spectroscopic features of DOM were analyzed. The results showed that nitrogen deposition significantly reduced the concentration of dissolved organic carbon (DOC), and increased the aromatic index (AI) and the humic index (HIX), but had no significant effect on dissolved organic nitrogen (DON) concentration in both soil layers. There was obvious seasonal variation in DOM concentration of the soil solution, which was prominently higher in summer and autumn than in spring and winter.Fourier-transform infrared (FTIR) absorption spectrometry indicated that the DOM in forest soil solution had absorption peaks in the similar position of six regions, being the highest in wave number of 1145-1149 cm -1 . Three-dimensional fluorescence spectra indicated that DOM was mainly consisted of protein-like substances (Ex/Em=230 nm/300 nm) and microbial degradation products (Ex/Em=275 nm/300 nm). The availability of protein-like substances from 0-15 cm soil layer was reduced in the nitrogen treatments. Nitrogen deposition significantly reduced the concentration of DOC in soil solution, maybe largely by reducing soil pH, inhibiting soil carbon mineralization and stimulating plant growth. In particular, the decline of DOC concentration in the surface layer was due to the production inhibition of the protein-like substances and carboxylic acids. Short-term nitrogen deposition might be beneficial to the maintenance of soil fertility, while the long-term accumulation of nitrogen deposition might lead to the hard utilization of soil nutrients.

  7. Filter Membrane Effects on Water-Extractable Phosphorus Concentrations from Soil.

    Science.gov (United States)

    Norby, Jessica; Strawn, Daniel; Brooks, Erin

    2018-03-01

    To accurately assess P concentrations in soil extracts, standard laboratory practices for monitoring P concentrations are needed. Water-extractable P is a common analytical test to determine P availability for leaching from soils, and it is used to determine best management practices. Most P analytical tests require filtration through a filter membrane with 0.45-μm pore size to distinguish between particulate and dissolved P species. However, filter membrane type is rarely specified in method protocols, and many different types of membranes are available. In this study, three common filter membrane materials (polyether sulfone, nylon, and nitrocellulose), all with 0.45-μm pore sizes, were tested for analytical differences in total P concentrations and dissolved reactive P (DRP) concentrations in water extracts from six soils sampled from two regions. Three of the extracts from the six soil samples had different total P concentrations for all three membrane types. The other three soil extracts had significantly different total P results from at least one filter membrane type. Total P concentration differences were as great as 35%. The DRP concentrations in the extracts were dependent on filter type in five of the six soil types. Results from this research show that filter membrane type is an important parameter that affects concentrations of total P and DRP from soil extracts. Thus, membrane type should be specified in soil extraction protocols. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  8. The distribution of radionuclides between the dissolved and particulate phases of a contaminated freshwater stream

    International Nuclear Information System (INIS)

    Murdock, R.N.; Johnson, M.S.; Hemingway, J.D.

    1995-01-01

    Streamwater concentrations of the radionuclides 137 Cs, 241 Am and 239,240 Pu from a contaminated freshwater stream showed significant relationships between total concentration and flow rate. When total concentrations were divided into their dissolved and particulate components 239,240 Pu was shown to exist mainly (>80%) in the solute phase ( 137 Cs and 241 Am were distributed equally between the two phases. 137 Cs was most likely present either as the dissolved ion or as the specifically adsorbed ion on particulate sediments. Particle-associated 241 Am and the small particulate component of 239,240 Pu, were believed to be bound to sediment surface coatings, such as organic or oxide/hydroxides, rather than the truly adsorbed ion. Solute phase 239,240 Pu was most likely associated with colloidal organic carbon species (such as humic or fulvic acids). This was also apparent, but to a lesser extent, for 241 Am. Distribution coefficients were determined for a number of discrete sites and environmental conditions. The response of the stream to removal of its source of radioactivity (via a re-routing scheme) was both significant and rapid. (author)

  9. Measuring the pollutant transport capacity of dissolved organic matter in complex matrixes

    DEFF Research Database (Denmark)

    Persson, L.; Alsberg, T.; Odham, G.

    2003-01-01

    Dissolved organic matter (DOM) facilitated transport in contaminated groundwater was investigated through the measurement of the binding capacity of landfill leachate DOM (Vejen, Denmark) towards two model pollutants (pyrene and phenanthrene). Three different methods for measuring binding capacity....... It was further concluded that DOM facilitated transport should be taken into account for non-ionic PAHs with lg K OW above 5, at DOM concentrations above 250 mg C/L. The total DOM concentration was found to be more important for the potential of facilitated transport than differences in the DOM binding capacity....

  10. Distributions of nutrients, dissolved organic carbon and carbohydrates in the western Arctic Ocean

    Science.gov (United States)

    Wang, Deli; Henrichs, Susan M.; Guo, Laodong

    2006-09-01

    Seawater samples were collected from stations along a transect across the shelf-basin interface in the western Arctic Ocean during September 2002, and analyzed for nutrients, dissolved organic carbon (DOC), and total dissolved carbohydrate (TDCHO) constituents, including monosaccharides (MCHO) and polysaccharides (PCHO). Nutrients (nitrate, ammonium, phosphate and dissolved silica) were depleted at the surface, especially nitrate. Their concentrations increased with increasing depth, with maxima centered at ˜125 m depth within the halocline layer, then decreased with increasing depth below the maxima. Both ammonium and phosphate concentrations were elevated in shelf bottom waters, indicating a possible nutrient source from sediments, and in a plume that extended into the upper halocline waters offshore. Concentrations of DOC ranged from 45 to 85 μM and had an inverse correlation with salinity, indicating that mixing is a control on DOC concentrations. Concentrations of TDCHO ranged from 2.5 to 19 μM-C, comprising 13-20% of the bulk DOC. Higher DOC concentrations were found in the upper water column over the shelf along with higher TDCHO concentrations. Within the TDCHO pool, the concentrations of MCHO ranged from 0.4 to 8.6 μM-C, comprising 20-50% of TDCHO, while PCHO concentrations ranged from 0.5 to 13.6 μM-C, comprising 50-80% of the TDCHO. The MCHO/TDCHO ratio was low in the upper 25 m of the water column, followed by a high MCHO/TDCHO ratio between 25 and 100 m, and a low MCHO/TDCHO ratio again below 100 m. The high MCHO/TDCHO ratio within the halocline layer likely resulted from particle decomposition and associated release of MCHO, whereas the low MCHO/TDCHO (or high PCHO/TDCHO) ratio below the halocline layer could have resulted from slow decomposition and additional particulate CHO sources.

  11. Toxicity of dissolved and precipitated aluminium to marine diatoms.

    Science.gov (United States)

    Gillmore, Megan L; Golding, Lisa A; Angel, Brad M; Adams, Merrin S; Jolley, Dianne F

    2016-05-01

    Localised aluminium contamination can lead to high concentrations in coastal waters, which have the potential for adverse effects on aquatic organisms. This research investigated the toxicity of 72-h exposures of aluminium to three marine diatoms (Ceratoneis closterium (formerly Nitzschia closterium), Minutocellus polymorphus and Phaeodactylum tricornutum) by measuring population growth rate inhibition and cell membrane damage (SYTOX Green) as endpoints. Toxicity was correlated to the time-averaged concentrations of different aluminium size-fractions, operationally defined as aluminium exposure varied between diatom species. C. closterium was the most sensitive species (10% inhibition of growth rate (72-h IC10) of 80 (55-100)μg Al/L (95% confidence limits)) while M. polymorphus (540 (460-600)μg Al/L) and P. tricornutum (2100 (2000-2200)μg Al/L) were less sensitive (based on measured total aluminium). Dissolved aluminium was the primary contributor to toxicity in C. closterium, while a combination of dissolved and precipitated aluminium forms contributed to toxicity in M. polymorphus. In contrast, aluminium toxicity to the most tolerant diatom P. tricornutum was due predominantly to precipitated aluminium. Preliminary investigations revealed the sensitivity of C. closterium and M. polymorphus to aluminium was influenced by initial cell density with aluminium toxicity significantly (paluminium toxicity to diatoms do not involve compromising the plasma membrane. These results indicate that marine diatoms have a broad range in sensitivity to aluminium with toxic mechanisms related to both dissolved and precipitated aluminium. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Origin, concentration, availability and fate of dissolved organic carbon in coastal lagoons of the Rio de Janeiro State

    Directory of Open Access Journals (Sweden)

    Albert Luiz Suhett

    Full Text Available The coastal lagoons in the northern Rio de Janeiro State (Brazil present a wide gradient of dissolved organic carbon (DOC and water color, with the highest DOC concentrations reported in the literature for aquatic ecosystems. Thus, they represent a peculiar set of ecosystems for the study of the origin, processing and fate of DOC in inland waters. We reviewed data from 2 decades of studies on the carbon cycle in these coastal lagoons and discussed the fluctuations in the concentration and quality of DOC, factors affecting DOC microbial and photochemical degradation, CO2 emission, as well as the role of humic and non-humic carbon to the energy flow through the trophic chains. We show that DOC quality, not its quantity, determines the rates of photochemical and microbial degradation both seasonally (within system and spatially (among systems, with the exception of DOC photo-oxidation among lagoons, which is partially explained by DOC concentration at regional scale. In humic lagoons, there is a fairly predictable pattern of seasonal variation in DOC concentration associated to rainfall-induced inputs of allochthonous C. However, little is known about the exact timing of these allochthonous inputs and how they relate to the seasonal variation of DOC chemical properties (i.e. its quality. Depth-integrated photo-oxidation rates were less representative in highly humic lagoons, due to strong light attenuation in the water column. Nevertheless, the potential contribution of photo-oxidation and bacterial respiration to total CO2 efflux (~11% did not differ significantly when all lagoons were pooled together. Contrary to prevailing paradigms for humic waters, microalgae seem to be the main C source in humic lagoons, sustaining pelagic food webs through zooplankton, in spite of some contribution of allochthonous C. Thus, the predominant role of the microbial loop in the DOC recovery to food webs in such systems is to be questioned.

  13. Microbial community evolution during simulated managed aquifer recharge in response to different biodegradable dissolved organic carbon (BDOC) concentrations

    KAUST Repository

    Li, Dong

    2013-05-01

    This study investigates the evolution of the microbial community in laboratory-scale soil columns simulating the infiltration zone of managed aquifer recharge (MAR) systems and analogous natural aquifer sediment ecosystems. Parallel systems were supplemented with either moderate (1.1 mg/L) or low (0.5 mg/L) biodegradable dissolved organic carbon (BDOC) for a period of six months during which time, spatial (1 cm, 30 cm, 60 cm, 90 cm, and 120 cm) and temporal (monthly) analyses of sediment-associated microbial community structure were analyzed. Total microbial biomass associated with sediments was positively correlated with BDOC concentration where a significant decline in BDOC was observed along the column length. Analysis of 16S rRNA genes indicated dominance by Bacteria with Archaea comprising less than 1 percent of the total community. Proteobacteria was found to be the major phylum in samples from all column depths with contributions from Betaproteobacteria, Alphaproteobacteria and Gammaproteobacteria. Microbial community structure at all the phylum, class and genus levels differed significantly at 1 cm between columns receiving moderate and low BDOC concentrations; in contrast strong similarities were observed both between parallel column systems and across samples from 30 to 120 cm depths. Samples from 1 cm depth of the low BDOC columns exhibited higher microbial diversity (expressed as Shannon Index) than those at 1 cm of moderate BDOC columns, and both increased from 5.4 to 5.9 at 1 cm depth to 6.7-8.3 at 30-120 cm depths. The microbial community structure reached steady state after 3-4 months since the initiation of the experiment, which also resulted in an improved DOC removal during the same time period. This study suggested that BDOC could significantly influence microbial community structure regarding both composition and diversity of artificial MAR systems and analogous natural aquifer sediment ecosystems. © 2013 Elsevier Ltd.

  14. Lake transparency: a window into decadal variations in dissolved organic carbon concentrations in Lakes of Acadia National Park, Maine

    Science.gov (United States)

    Roesler, Collin S.; Culbertson, Charles W.

    2016-01-01

    A forty year time series of Secchi depth observations from approximately 25 lakes in Acadia National Park, Maine, USA, evidences large variations in transparency between lakes but relatively little seasonal cycle within lakes. However, there are coherent patterns over the time series, suggesting large scale processes are responsible. It has been suggested that variations in colored dissolved organic matter (CDOM) are primarily responsible for the variations in transparency, both between lakes and over time and further that CDOM is a robust optical proxy for dissolved organic carbon (DOC). Here we present a forward model of Secchi depth as a function of DOC based upon first principles and bio-optical relationships. Inverting the model to estimate DOC concentration from Secchi depth observations compared well with the measured DOC concentrations collected since 1995 (RMS error < 1.3 mg C l-1). This inverse model allows the time series of DOC to be extended back to the mid 1970s when only Secchi depth observations were collected, and thus provides a means for investigating lake response to climate forcing, changing atmospheric chemistry and watershed characteristics, including land cover and land use.

  15. Effects of inoculum type and bulk dissolved oxygen concentration on achieving partial nitrification by entrapped-cell-based reactors.

    Science.gov (United States)

    Rongsayamanont, Chaiwat; Limpiyakorn, Tawan; Khan, Eakalak

    2014-07-01

    An entrapment of nitrifiers into gel matrix is employed as a tool to fulfill partial nitrification under non-limiting dissolved oxygen (DO) concentrations in bulk solutions. This study aims to clarify which of these two attributes, inoculum type and DO concentration in bulk solutions, is the decisive factor for partial nitrification in an entrapped-cell based system. Four polyvinyl alcohol entrapped inocula were prepared to have different proportions of nitrite-oxidizing bacteria (NOB) and nitrite-oxidizing activity. At a DO concentration of 3 mg l(-1), the number of active NOB cells in an inoculum was the decisive factor for partial nitrification enhancement. However, when the DO concentration was reduced to 2 mg l(-1), all entrapped cell inocula showed similar degrees of partial nitrification. The results suggested that with the lower bulk DO concentration, the preparation of entrapped cell inocula is not useful as the DO level becomes the decisive factor for achieving partial nitrification. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Evaluation of water quality by chlorophyll and dissolved oxygen

    International Nuclear Information System (INIS)

    Latif, Z.; Tasneem, M.A.; Javed, T.; Butt, S.; Fazil, M.; Ali, M.; Sajjad, M.I.

    2002-01-01

    This paper focuses on the impact of Chlorophyll and dissolved Oxygen on water quality. Kalar Kahar and Rawal lakes were selected for this research. A Spectrophotometer was used for determination of Chlorophyll a, Chlorophyll b, Chlorophyll c and Pheophytin pigment. Dissolved Oxygen was measured in situ, using dissolved oxygen meter. The gamma O/sup 18/ of dissolved Oxygen, like concentration, is affected primarily by three processes: air water gas exchange, respiration and photosynthesis; gamma O/sup 18/ is analyzed on isotopic ratio mass spectrometer, after extraction of dissolved Oxygen from water samples, followed by purification and conversion into CO/sub 2/. Rawal lake receives most of the water from precipitation during monsoon period and supplemented by light rains in December and January. This water is used throughout the year for drinking purposes in Rawalpindi city. The water samples were collected from 5, 7.5, and 10 meters of depth for seasonal studies of physiochemical and isotopic parameters of water and dissolved Oxygen. Optimum experimental conditions for delta O/sup 18/ analysis of dissolved Oxygen from aqueous samples were determined. Stratification of dissolved Oxygen was observed in Rawal Lake before rainy season in summer. The water quality deteriorates with depth, because the respiration exceeds the photosynthesis and gas exchange. The concentration and delta O/sup 18/ of dissolved Oxygen show no variation with depth in 1998 winter sampling. Kalar Kahar lake gets water from springs, which are recharged by local rains on the nearby mountains. It is a big lake, with shallow and uniform depth of nearly 1.5 meters. A lot of vegetation can be seen on the periphery of the lake. Algae have grown on the floor of the lake Water samples were collected from the corner with large amount of vegetation and from the center of the lake for dissolved Oxygen and Chlorophyll measurements. Chlorophyll result shows that Kalar Kahar Lake falls in Eutrophic category

  17. Acid-base properties of Baltic Sea dissolved organic matter

    Science.gov (United States)

    Hammer, Karoline; Schneider, Bernd; Kuliński, Karol; Schulz-Bull, Detlef E.

    2017-09-01

    Calculations related to the marine CO2 system that are based on alkalinity data may be strongly biased if the contributions of organic compounds are ignored. In coastal seas, concentrations of dissolved organic matter (DOM) are frequently high and alkalinity from inorganic compounds is low. In this study, based on measurements of total alkalinity, total CO2, and pH, we determined the organic alkalinity, Aorg, in water from the central Baltic Sea. The maximum Aorg measured in the surface mixed layer during the spring bloom was > 50 μmol/kg-SW but the Aorg decreased with depth and approached zero below the permanent halocline. This behavior could be attributed to the decreased pH of deeper water layers. The data were used to calculate the bulk dissociation constant, KDOM, for marine DOM and the fraction f of dissolved organic carbon (DOC) that acts as a carrier for acid-base functional groups. The p KDOM (7.27) agreed well with the value (7.34) previously estimated in a preliminary study of organic alkalinity in the Baltic Sea. The fraction of carbon atoms carrying acid-base groups was 17% and was somewhat higher than previously reported (12%). Spike experiments performed using artificial seawater and three different humic/fulvic substances tested whether the acid-base properties of these substances explain the results of our field study. Specifically, Aorg was determined at different concentrations (DOC) of the added humic/fulvic substances. The relationship between Aorg and the DOC concentrations indicated that humic/fulvic substances are more acidic (p KDOM < 6.5) than the bulk DOC natural occurring in the Baltic Sea.

  18. E-perm radon monitors for determining waterborne concentrations of dissolved in radon 222Rn

    International Nuclear Information System (INIS)

    Jester, W.A.; Kotrappa, P.

    1989-01-01

    This paper describes a simple and relatively inexpensive method in which E-Perm radon monitors are used to determine the concentration of dissolved 222 Rn in drinking water. This procedure takes advantage of E-Perm's ability to accurately measure the integral radon exposure under conditions of high humidity. The method was evaluated against the liquid scintillation procedure recommended by the U.S. Environmental Protection Agency (EPA) and was found to give excellent agreement. An E-perm is an electret ion chamber that consists of a small chamber constructed from a conducting plastic and having an electret at its base and a filtered air inlet at the top. The technique described in this paper takes advantages of E-Perm's insensitivity to high humidity

  19. Fate of polychlorinated biphenyls in a contaminated lake ecosystem: Combining equilibrium passive sampling of sediment and water with total concentration measurements of biota

    DEFF Research Database (Denmark)

    Mäenpää, Kimmo; Leppänen, Matti T.; Figueiredo, Kaisa

    2015-01-01

    Equilibrium sampling devices can be applied to study and monitor the exposure and fate of hydrophobic organic chemicals on a thermodynamic basis. They can be used to determine freely dissolved concentrations and chemical activity ratios and to predict equilibrium partitioning concentrations...... of hydrophobic organic chemicals in biota lipids. The authors' aim was to assess the equilibrium status of polychlorinated biphenyls (PCBs) in a contaminated lake ecosystem and along its discharge course using equilibrium sampling devices for measurements in sediment and water and by also analyzing biota....... The authors used equilibrium sampling devices (silicone rubber and polyethylene [PE]) to determine freely dissolved concentrations and chemical activities of PCBs in the water column and sediment porewater and calculated for both phases the corresponding equilibrium concentrations and chemical activities...

  20. METHOD OF DISSOLVING URANIUM METAL

    Science.gov (United States)

    Slotin, L.A.

    1958-02-18

    This patent relates to an economicai means of dissolving metallic uranium. It has been found that the addition of a small amount of perchloric acid to the concentrated nitric acid in which the uranium is being dissolved greatly shortens the time necessary for dissolution of the metal. Thus the use of about 1 or 2 percent of perchioric acid based on the weight of the nitric acid used, reduces the time of dissolution of uranium by a factor of about 100.

  1. The effect of dissolved oxygen on water radiolysis behaviour

    International Nuclear Information System (INIS)

    Yakabuskie, P.A.; Joseph, J.M.; Wren, J.C.; Stuart, C.R.

    2012-09-01

    A quantitative understanding of the chemical or redox environments generated in water by ionizing radiation is important for material selection, development of maintenance programs, and safety assessments for water-cooled nuclear power reactors. The highly reactive radicals (·OH, ·H, ·e aq - , ·HO 2 , and ·O 2 - ) and molecular species (H 2 and H 2 O 2 ) generated by water radiolysis can compete in reactions with other dissolved compounds and impose changes to the system chemistry by altering the steady-state concentrations of water radiolysis products, which could impact the degradation of materials in contact with the aqueous phase. Understanding in detail how a given chemical additive changes the long-term radiolysis kinetics can help us to determine what chemistry control steps may be required to return the system to an optimal redox condition, and in turn, enhance the lifetime of reactor components. This study outlines the effect of dissolved oxygen gas, which could be introduced due to air ingress, on long-term water radiolysis behaviour. The effects of solution pH and initial dissolved O 2 concentration on the radiolytic production of molecular H 2 and H 2 O 2 have been investigated by performing experiments with three different O 2 concentrations at pH 6.0 and 10.6 under steady-state radiolysis conditions. The aqueous and gas phase analyses were performed using UV-Vis spectrophotometry and gas-chromatography equipped with electron capture and thermal conductivity detectors. The experimental results were compared with kinetic model calculations of steady-state radiolysis and were found to be in good agreement. The concentrations of water radiolysis products, H 2 O 2 and H 2 , were found to increase in the presence of dissolved oxygen, but the degree of increase was shown to depend on the solution pH. Furthermore, the steady-state concentration of H 2 did not increase as greatly as that of H 2 O 2 at either pH studied. The kinetic analyses have shown

  2. Fate of dissolved organic nitrogen in two stage trickling filter process.

    Science.gov (United States)

    Simsek, Halis; Kasi, Murthy; Wadhawan, Tanush; Bye, Christopher; Blonigen, Mark; Khan, Eakalak

    2012-10-15

    Dissolved organic nitrogen (DON) represents a significant portion of nitrogen in the final effluent of wastewater treatment plants (WWTPs). Biodegradable portion of DON (BDON) can support algal growth and/or consume dissolved oxygen in the receiving waters. The fate of DON and BDON has not been studied for trickling filter WWTPs. DON and BDON data were collected along the treatment train of a WWTP with a two-stage trickling filter process. DON concentrations in the influent and effluent were 27% and 14% of total dissolved nitrogen (TDN). The plant removed about 62% and 72% of the influent DON and BDON mainly by the trickling filters. The final effluent BDON values averaged 1.8 mg/L. BDON was found to be between 51% and 69% of the DON in raw wastewater and after various treatment units. The fate of DON and BDON through the two-stage trickling filter treatment plant was modeled. The BioWin v3.1 model was successfully applied to simulate ammonia, nitrite, nitrate, TDN, DON and BDON concentrations along the treatment train. The maximum growth rates for ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria, and AOB half saturation constant influenced ammonia and nitrate output results. Hydrolysis and ammonification rates influenced all of the nitrogen species in the model output, including BDON. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Annual and seasonal variation of turbidity, total dissolved solids, nitrate and nitrite in the Parsabad water treatment plant, Iran

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Zare

    2013-01-01

    Full Text Available Aims: This study investigated the annual and seasonal variation of turbidity; total dissolved solid (TDS, nitrate and nitrite in Parsabad water treatment plant (WTP, Iran. Materials and Methods: The water samples were obtained from the inlet and outlet of Parsabad WTP from February 2002 to June 2009. The samples′ turbidity, TDS, nitrate, nitrite, pH, and temperature were measured according to standard methods once a month and the average of these parameters were calculated for each season of year. Results: The maximum concentration of inlet turbidity, TDS, nitrate and nitrite were 691, 700.5, 25, and 0.17 mg/l, respectively. These parameters for outlet samples in the study period were 3.0, 696.7, 18, and 0.06 mg/l, respectively. While these concentrations in outlet zone were lower than World Health Organization (WHO or United States Environmental Protection Agency (US-EPA water quality guidelines, WTP could not reduce the TDS, nitrate, nitrite and pH value and these parameters were not different in the inlet and outlet samples. However, the WTP reduced the turbidity significantly with an efficiency of up to 85%. Conclusion: This study showed that a common WTP with rapid sand filtration can treat a maximum river turbidity of 700 NTU in several years. As no differences were observed between inlet and outlet TDS, nitrate, nitrite and pH in the studied WTP. It can be concluded that compensatory schemes should be predicted for modification of these parameters when they exceed the standards in the emergency situations.

  4. Microscopic characterization of pretransition oxide formed on Zr–Nb–Sn alloy under various Zn and dissolved hydrogen concentrations

    Directory of Open Access Journals (Sweden)

    Sungyu Kim

    2018-04-01

    Full Text Available Microstructure of oxide formed on Zr–Nb–Sn tube sample was intensively examined by scanning transmission electron microscopy after exposure to simulated primary water chemistry conditions of various concentrations of Zn (0 or 30 ppb and dissolved hydrogen (H2 (30 or 50 cc/kg for various durations without applying desirable heat flux. Microstructural analysis indicated that there was no noticeable change in the microstructure of the oxide corresponding to water chemistry changes within the test duration of 100 days (pretransition stage and no significant difference in the overall thickness of the oxide layer. Equiaxed grains with nano-size pores along the grain boundaries and microcracks were dominant near the water/oxide interface, regardless of water chemistry conditions. As the metal/oxide interface was approached, the number of pores tended to decrease. However, there was no significant effect of H2 concentration between 30 cc/kg and 50 cc/kg on the corrosion of the oxide after free immersion in water at 360°C. The adsorption of Zn on the cladding surface was observed by X-ray photoelectron spectroscopy and detected as ZnO on the outer oxide surface. From the perspective of OH− ion diffusion and porosity formation, the absence of noticeable effects was discussed further. Keywords: Dissolved Hydrogen Effect, Porosity, Pretransition Oxide, Transmission Electron Microscopy (TEM, Zirconium Alloys

  5. Dissolved organic nitrogen recalcitrance and bioavailable nitrogen quantification for effluents from advanced nitrogen removal wastewater treatment facilities

    International Nuclear Information System (INIS)

    Fan, Lu; Brett, Michael T.; Jiang, Wenju; Li, Bo

    2017-01-01

    The objective of this study was to determine the composition of nitrogen (N) in the effluents of advanced N removal (ANR) wastewater treatment plants (WWTPs). This study also tested two different experimental protocols for determining dissolved N recalcitrance. An analysis of 15 effluent samples from five WWTPs, showed effluent concentrations and especially effluent composition varied greatly from one system to the other, with total nitrogen (TN) ranging between 1.05 and 8.10 mg L −1 . Nitrate (NO 3 − ) accounted for between 38 ± 32% of TN, and ammonium accounted for a further 29 ± 28%. All of these samples were dominated by dissolved inorganic nitrogen (DIN; NO 3 −  + NH 4 + ), and uptake experiments indicated the DIN fraction was as expected highly bioavailable. Dissolved organic N (DON) accounted for 20 ± 11% for the total dissolved N in these effluents, and uptake experiments indicated the bioavailability of this fraction varied between 27 ± 26% depending on the WWTP assessed. These results indicate near complete DIN removal should be the primary goal of ANR treatment systems. The comparison of bioavailable nitrogen (BAN) quantification protocols showed that the dissolved nitrogen uptake bioassay approach was clearly a more reliable way to determine BAN concentrations compared to the conventional cell yield protocol. Moreover, because the nitrogen uptake experiment was much more sensitive, this protocol made it easier to detect extrinsic factors (such as biological contamination or toxicity) that could affect the accuracy of these bioassays. Based on these results, we recommend the nitrogen uptake bioassay using filtered and autoclaved samples to quantify BAN concentrations. However, for effluent samples indicating toxicity, algal bioassays will not accurately quantify BAN. - Highlights: • DIN was the dominated N pool for most of the tested effluent samples. • DON bioavailability considerably varied depending on the WWTP assessed.

  6. Dissolved inorganic nutrients and chlorophyll on the narrow continental shelf of Eastern Brazil

    Directory of Open Access Journals (Sweden)

    Gilmara Fernandes Eça

    2014-03-01

    Full Text Available The eastern Brazilian continental shelf is narrow and subject to the influence of a western boundary current system, presenting lower biological productivity than other regions. In this study, the distribution of water masses, dissolved inorganic nutrients, chlorophyll-a and total suspended solids (TSS on the inner shelf (< 35 m depth, between Itacaré and Canavieiras, eastern Brazil, is presented. Sampling surveys were carried out in March and August 2006 and March 2007. Tropical water (TW prevailed during March 2006 and August 2007 with the lower salinity waters (< 36 found in most samples taken in March 2007, reflecting the influence of continental outflow and rain in coastal waters. Low concentrations of dissolved inorganic nutrients and Chl-a found were typical of TW and results suggested that the inner shelf waters were depleted in dissolved inorganic nitrogen in August 2006 and March 2007, and in phosphate in March 2006, potentially affecting phytoplankton growth. Stratification of the water column was observed due to differences in dissolved nutrient concentrations, chlorophyll-a and TSS when comparing surface and bottom samples, possibly the result of a colder water intrusion and mixing on the bottom shelf and a deep chlorophyll maximum and/or sediment resuspension effect. Despite this stratification, oceanographic processes such as lateral mixing driven by the Brazil Current as well as a northward alongshore drift driven by winds and tides transporting Coastal Water can lead to an enhanced mixing of these waters promoting some heterogeneity in this oligotrophic environment.

  7. Influence of environmental parameters on the concentration of subsurface dissolved methane in two hydroelectric power plants in Brazil

    Science.gov (United States)

    Silva, M. G.; Marani, L.; Alvala, P. C.

    2013-12-01

    Methane (CH4) is a trace gas in the atmosphere of great importance for atmospheric chemistry as one of the main greenhouse gases. There are different sources with the largest individual production associated with the degradation of organic matter submerged in flooded areas. The amount of dissolved methane that reaches the surface depends on the production in the sediments and consumption in the water column. Both processes are associated with microbial activity and consequently dependent on the physico-chemical environmental conditions. The construction of hydroelectric dams cause flooding of areas near the river that can change the characteristics of the environment and cause changes in subsurface methane concentration. In this work, we studied two hydroelectric plants located in Brazil: Batalha (17°20'39.52"S, 47°29'34.29"W), under construction when the samples were take, and Itaipu (25°24'45.00"S, 54°35'39.00"W) which has been floated over 30 years ago. The water samples to determine dissolved methane were collected approximately 5 cm near the surface. In each collection point was measured depth, water temperature, pH and redox potential. The range of dissolved methane between the two dams was similar: 0.07-10.33 μg/l (Batalha) and 0.15-10.93 μg/l (Itaipu). However, the Batalha's average (4.04 × 3.43 μg/l; median = 3.66 μg/l) was higher than that observed in Itaipu (2.15 × 1.59 μg/l; median = 2.53 μg/l). The influence of environmental parameters on the concentration of dissolved methane was evaluated by multivariate statistical techniques (Principal Component Analysis - PCA). All of the parameters had some correlation with dissolved methane, however, the greatest contribution in Batalha was associated with pH while in Itaipu was the depth. The pH variation of the various points studied in Batalha may be associated with periods of drought and flooding of the river and hence the incorporation of organic matter in the environment. The organisms

  8. Dissolved organic carbon (DOC) concentrations in UK soils and the influence of soil, vegetation type and seasonality.

    Science.gov (United States)

    van den Berg, Leon J L; Shotbolt, Laura; Ashmore, Mike R

    2012-06-15

    Given the lack of studies which measured dissolved organic carbon (DOC) over long periods, especially in non-forest habitat, the aim of this study was to expand the existing datasets with data of mainly non-forest sites that were representative of the major soil and habitat types in the UK. A further aim was to predict DOC concentrations from a number of biotic and abiotic explanatory variables such as rainfall, temperature, vegetation type and soil type in a multivariate way. Pore water was sampled using Rhizon or Prenart samplers at two to three week intervals for 1 year. DOC, pH, organic carbon, carbon/nitrogen (C:N) ratios of soils and slope were measured and data on vegetation, soil type, temperature and precipitation were obtained. The majority of the variation in DOC concentrations between the UK sites could be explained by simple empirical models that included annual precipitation, and soil C:N ratio with precipitation being negatively related to DOC concentrations and C:N ratio being positively related to DOC concentrations. Our study adds significantly to the data reporting DOC concentrations in soils, especially in grasslands, heathlands and moorlands. Broad climatic and site factors have been identified as key factors influencing DOC concentrations. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Dissolved oxygen concentration in the medium during cell culture: Defects and improvements.

    Science.gov (United States)

    Zhang, Kuan; Zhao, Tong; Huang, Xin; He, Yunlin; Zhou, Yanzhao; Wu, Liying; Wu, Kuiwu; Fan, Ming; Zhu, Lingling

    2016-03-01

    In vitro cell culture has provided a useful model to study the effects of oxygen on cellular behavior. However, it remains unknown whether the in vitro operations themselves affect the medium oxygen levels and the living states of cells. In addition, a prevailing controversy is whether reactive oxygen species (ROS) production is induced by continuous hypoxia or reoxygenation. In this study, we have measured the effects of different types of cell culture containers and the oxygen environment where medium replacement takes place on the actual oxygen tension in the medium. We found that the deviations of oxygen concentrations in the medium are much greater in 25-cm(2) flasks than in 24-well plates and 35-mm dishes. The dissolved oxygen concentrations in the medium were increased after medium replacement in normoxia, but remained unchanged in glove boxes in which the oxygen tension remained at a low level (11.4, 5.7, and 0.5% O2 ). We also found that medium replacement in normoxia increased the number of ROS-positive cells and reduced the cell viability; meanwhile, medium replacement in a glove box did not produce the above effects. Therefore, we conclude that the use of 25-cm(2) flasks should be avoided and demonstrate that continuous hypoxia does not produce ROS, whereas the reoxygenation that occurs during the harvesting of cells leads to ROS and induces cell death. © 2015 International Federation for Cell Biology.

  10. Leaching of dissolved phosphorus from tile-drained agricultural areas.

    Science.gov (United States)

    Andersen, H E; Windolf, J; Kronvang, B

    2016-01-01

    We investigated leaching of dissolved phosphorus (P) from 45 tile-drains representing animal husbandry farms in all regions of Denmark. Leaching of P via tile-drains exhibits a high degree of spatial heterogeneity with a low concentration in the majority of tile-drains and few tile-drains (15% in our investigation) having high to very high concentration of dissolved P. The share of dissolved organic P (DOP) was high (up to 96%). Leaching of DOP has hitherto been a somewhat overlooked P loss pathway in Danish soils and the mechanisms of mobilization and transport of DOP needs more investigation. We found a high correlation between Olsen-P and water extractable P. Water extractable P is regarded as an indicator of risk of loss of dissolved P. Our findings indicate that Olsen-P, which is measured routinely in Danish agricultural soils, may be a useful proxy for the P leaching potential of soils. However, we found no straight-forward correlation between leaching potential of the top soil layer (expressed as either degree of P saturation, Olsen-P or water extractable P) and the measured concentration of dissolved P in the tile-drain. This underlines that not only the source of P but also the P loss pathway must be taken into account when evaluating the risk of P loss.

  11. Dissolved organic carbon, CO2, and CH4 concentrations and their stable isotope ratios in thermokarst lakes on the Qinghai-Tibetan Plateau

    Directory of Open Access Journals (Sweden)

    Cuicui Mu

    2016-01-01

    Full Text Available Thermokarst lakes are widely distributed on the Qinghai-Tibetan Plateau (QTP, which accounts for 8% of the global permafrost area. These lakes probably promote organic matter biodegradation and thus accelerate the emission of carbon-based greenhouse gases. However, little is known about greenhouse gas concentrations and their stable isotopes characteristics of these lakes. In this study, we measured the concentrations of dissolved organic carbon (DOC, dissolved CO2 and CH4, as well as the distribution of δ13CCO2, δ13CCH4, and δ13COM (organic matter of lake sediments in thermokarst lakes on the QTP. Results showed that the OM of the lake sediments was highly decomposed. The concentrations of DOC, CO2 and CH4 in the lake water on the QTP were 1.2–49.6 mg L–1, 3.6–45.0 μmol L–1 and 0.28–3.0 μmol L–1, respectively. The highest CO2 and CH4 concentrations were recorded in July while the lowest values in September, which suggested that temperature had an effect on greenhouse gas production, although this pattern may also relate to thermal stratification of the water column. The results implied that thermokast lakes should be paid more attention to regarding carbon cycle and greenhouse gas emissions on the QTP.

  12. Dissolved phosphorus pools and alkaline phosphatase activity in the euphotic zone of the western North Pacific Ocean.

    Directory of Open Access Journals (Sweden)

    Masahiro eSuzumura

    2012-03-01

    Full Text Available We measured pools of dissolved phosphorus (P, including dissolved inorganic P (DIP, dissolved organic P (DOP and alkaline phosphatase (AP-hydrolyzable labile DOP (L-DOP, and kinetic parameters of AP activity (APA in the euphotic zone in the western North Pacific Ocean. Samples were collected from one coastal station in Sagami Bay, Japan, and three offshore stations between the North Pacific Subtropical Gyre (NPSG and the Kuroshio region. Although DIP concentrations in the euphotic zone at all stations were equally low, around the nominal method detection limit of 20 nmol L−1, chlorophyll a (Chl a concentrations were one order of magnitude greater at the coastal station. DOP was the dominant P pool, comprising 62–92% of total dissolved P at and above the Chl a maximum layer (CML. L-DOP represented 22–39% of the total DOP at the offshore stations, whereas it accounted for a much higher proportion (about 85% in the coastal surface layers. Significant correlations between maximum potential AP hydrolysis rates and DIP concentrations or bacterial cell abundance in the offshore euphotic zone suggest that major APA in the oligotrophic surface ocean is from bacterial activity and regulated largely by DIP availability. Although the range of maximum potential APA was comparable among the environmental conditions, the in situ hydrolysis rate of L-DOP in the coastal station was 10 times those in the offshore stations. L-DOP turnover time at the CML ranged from 4.5 d at the coastal station to 84.4 d in the NPSG. The ratio of the APA half saturation constant to the ambient L-DOP concentration decreased markedly from the NPSG to the coastal station. There were substantial differences in the rate end efficiency of DOP remineralization and its contribution as the potential P source between the low-phosphate/high biomass coastal ecosystem and the low-phosphate/low biomass oligotrophic ocean.

  13. Age-dependent changes in the total protein concentrations in the ...

    African Journals Online (AJOL)

    related changes in total protein concentrations in ten regions of the pig brain and hypophyses from birth to 36 months of age. Age-related changes in protein concentrations in all the brain regions except the pons and cerebral cortex were not ...

  14. Sedimentary and mineral dust sources of dissolved iron to the world ocean

    Directory of Open Access Journals (Sweden)

    J. K. Moore

    2008-05-01

    Full Text Available Analysis of a global compilation of dissolved-iron observations provides insights into the processes controlling iron distributions and some constraints for ocean biogeochemical models. The distribution of dissolved iron appears consistent with the conceptual model developed for Th isotopes, whereby particle scavenging is a two-step process of scavenging mainly by colloidal and small particulates, followed by aggregation and removal on larger sinking particles. Much of the dissolved iron (<0.4 μm is present as small colloids (>~0.02 μm and, thus, is subject to aggregation and scavenging removal. This implies distinct scavenging regimes for dissolved iron consistent with the observations: 1 a high scavenging regime – where dissolved-iron concentrations exceed the concentrations of strongly binding organic ligands; and 2 a moderate scavenging regime – where dissolved iron is bound to both colloidal and soluble ligands. Within the moderate scavenging regime, biological uptake and particle scavenging decrease surface iron concentrations to low levels (<0.2 nM over a wide range of low to moderate iron input levels. Removal rates are also highly nonlinear in areas with higher iron inputs. Thus, observed surface-iron concentrations exhibit a bi-modal distribution and are a poor proxy for iron input rates. Our results suggest that there is substantial removal of dissolved iron from subsurface waters (where iron concentrations are often well below 0.6 nM, most likely due to aggregation and removal on sinking particles of Fe bound to organic colloids.

    We use the observational database to improve simulation of the iron cycle within a global-scale, Biogeochemical Elemental Cycling (BEC ocean model. Modifications to the model include: 1 an improved particle scavenging parameterization, based on the sinking mass flux of particulate organic material, biogenic silica, calcium carbonate, and mineral dust particles; 2 desorption of dissolved iron

  15. Ancient dissolved methane in inland waters at low concentrations revealed by a new collection method for radiocarbon (^{14}C) analysis

    Science.gov (United States)

    Dean, Joshua F.; Billett, Michael F.; Murray, Callum; Garnett, Mark H.

    2017-04-01

    Methane (CH4) is a powerful greenhouse gas and is released to the atmosphere from freshwater systems in numerous biomes globally. Radiocarbon (14C) analysis of methane can provide unique information about its age, source and rate of cycling in natural environments. Methane is often released from aquatic sediments in bubbles (ebullition), but dissolved methane is also present in lakes and streams at lower concentrations, and may not be of the same age or source. Obtaining sufficient non-ebullitive aquatic methane for 14C analysis remains a major technical challenge. Previous studies have shown that freshwater methane, in both dissolved and ebullitive form, can be significantly older than other forms of aquatic carbon (C), and it is therefore important to characterise this part of the terrestrial C balance. We present a novel method to capture sufficient amounts of dissolved methane from freshwater environments for 14C analysis by circulating water across a hydrophobic, gas-permeable membrane and collecting the methane in a large collapsible vessel. The results of laboratory and field tests show that reliable dissolved δ13CH4 and 14CH4 samples can be readily collected over short time periods (˜4 to 24 hours), at relatively low cost and from a variety of surface water types. The initial results further support previous findings that dissolved methane can be significantly older than other forms of aquatic C, especially in organic-rich catchments, and is currently unaccounted for in many terrestrial C balances and models. This method is suitable for use in remote locations, and could potentially be used to detect the leakage of unique 14CH4 signatures from point sources into waterways, e.g. coal seam gas and landfill gas.

  16. Annual dissolved nitrite plus nitrate and total phosphorous loads for the Susquehanna, St. Lawrence, Mississippi-Atchafalaya, and Columbia River basins, 1968-2004

    Science.gov (United States)

    Aulenbach, Brent T.

    2006-01-01

    Annual stream-water loads were calculated near the outlet of four of the larger river basins (Susquehanna, St. Lawrence, Mississippi-Atchafalaya, and Columbia) in the United States for dissolved nitrite plus nitrate (NO2 + NO3) and total phosphorus using LOADEST load estimation software. Loads were estimated for the period 1968-2004; although loads estimated for individual river basins and chemical constituent combinations typically were for shorter time periods due to limitations in data availability. Stream discharge and water-quality data for load estimates were obtained from the U.S. Geological Survey (USGS) with additional stream discharge data for the Mississippi-Atchafalaya River Basin from the U.S. Army Corps of Engineers. The loads were estimated to support national assessments of changes in stream nutrient loads that are periodically conducted by Federal agencies (for example, U.S. Environmental Protection Agency) and other water- and land-resource organizations. Data, methods, and results of load estimates are summarized herein; including World Wide Web links to electronic ASCII text files containing the raw data. The load estimates are compared to dissolved NO2 + NO3 loads for three of the large river basins from 1971 to 1998 that the USGS provided during 2001 to The H. John Heinz III Center for Science, Economics and the Environment (The Heinz Center) for a report The Heinz Center published during 2002. Differences in the load estimates are the result of using the most up-to-date monitoring data since the 2001 analysis, differences in how concentrations less than the reporting limit were handled by the load estimation models, and some errors and exclusions in the 2001 analysis datasets (which resulted in some inaccurate load estimates).

  17. Influence of in-stream diel concentration cycles of dissolved trace metals on acute toxicity to one-year-old cutthroat trout (Oncorhynchus clarki lewisi)

    Science.gov (United States)

    Nimick, D.A.; Harper, D.D.; Farag, A.M.; Cleasby, T.E.; MacConnell, Elizabeth; Skaar, D.

    2007-01-01

    Extrapolating results of laboratory bioassays to streams is difficult, because conditions such as temperature and dissolved metal concentrations can change substantially on diel time scales. Field bioassays conducted for 96 h in two mining-affected streams compared the survival of hatchery-raised, metal-nai??ve westslope cutthroat trout (Oncorhynchus clarki lewisi) exposed to dissolved (0.1-??m filtration) metal concentrations that either exhibited the diel variation observed in streams or were controlled at a constant value. Cadmium and Zn concentrations in these streams increased each night by as much as 61 and 125%, respectively, and decreased a corresponding amount the next day, whereas Cu did not display a diel concentration cycle. In High Ore Creek (40 km south of Helena, MT, USA), survival (33%) after exposure to natural diel-fluctuating Zn concentrations (range, 214-634 ??g/L; mean, 428 ??g/L) was significantly (p = 0.008) higher than survival (14%) after exposure to a controlled, constant Zn concentration (422 ??g/L). Similarly, in Dry Fork Belt Creek (70 km southeast of Great Falls, MT, USA), survival (75%) after exposure to diel-fluctuating Zn concentrations (range, 266-522 ??g/L; mean, 399 ??g/L) was significantly (p = 0.022) higher than survival (50%) in the constant-concentration treatment (392 ??g/L). Survival likely was greater in these diel treatments, both because the periods of lower metal concentrations provided some relief for the fish and because toxicity during periods of higher metal concentrations was lessened by the simultaneous occurrence each night of lower water temperatures, which reduce the rate of metal uptake. Based on the present study, current water-quality criteria appear to be protective for streams with diel concentration cycles of Zn (and, perhaps, Cd) for the hydrologie conditions tested. ?? 2007 SETAC.

  18. Mercury and Dissolved Organic Matter Dynamics During Snowmelt in the Upper Provo River, Utah, USA

    Science.gov (United States)

    Packer, B. N.; Carling, G. T.; Nelson, S.; Aanderud, Z.; Shepherd Barkdull, N.; Gabor, R. S.

    2017-12-01

    Mercury (Hg) is deposited to mountains by atmospheric deposition and mobilized during snowmelt runoff, leading to Hg contamination in otherwise pristine watersheds. Mercury is typically transported with dissolved organic matter (DOM) from soils to streams and lakes. This study focused on Hg and DOM dynamics in the snowmelt-dominated upper Provo River watershed, northern Utah, USA. We sampled Hg, dissolved organic carbon (DOC) concentrations, and DOM fluorescence in river water, snowpack, and ephemeral streams over four years from 2014-2017 to investigate Hg transport mechanisms. During the snowmelt season (April through June), Hg concentrations typically increased from 1 to 8 ng/L showing a strong positive correlation with DOC. The dissolved Hg fraction was dominant in the river, averaging 75% of total Hg concentrations, suggesting that DOC is more important for transport than suspended particulate matter. Ephemeral channels, which represent shallow flow paths with strong interactions with soils, had the highest Hg (>10 ng/L) and DOC (>10 mg/L) concentrations, suggesting a soil water source of Hg and organic matter. Fluorescence spectroscopy results showed important changes in DOM type and quality during the snowmelt season and the soil water flow paths are activated. Changes in DOM characteristics during snowmelt improve the understanding of Hg dynamics with organic matter and elucidate transport pathways from the soil surface, ephemeral channels and groundwater to the Provo River. This study has implications for understanding Hg sources and transport mechanisms in mountain watersheds.

  19. Free amino nitrogen concentration correlates to total yeast assimilable nitrogen concentration in apple juice.

    Science.gov (United States)

    Boudreau, Thomas F; Peck, Gregory M; O'Keefe, Sean F; Stewart, Amanda C

    2018-01-01

    Yeast assimilable nitrogen (YAN) is essential for yeast growth and metabolism during apple ( Malus x domestica Borkh.) cider fermentation. YAN concentration and composition can impact cider fermentation kinetics and the formation of volatile aroma compounds by yeast. The YAN concentration and composition of apples grown in Virginia, USA over the course of two seasons was determined through analysis of both free amino nitrogen (FAN) and ammonium ion concentration. FAN was the largest fraction of YAN, with a mean value of 51 mg N L -1 FAN compared to 9 mg N L -1 ammonium. Observed YAN values ranged from nine to 249 mg N L -1 , with a mean value of 59 mg N L -1 . Ninety-four percent of all samples analyzed in this study contained yeast to fully utilize all of the fermentable sugars. FAN concentration was correlated with total YAN concentration, but ammonium concentration was not. Likewise, there was no correlation between FAN and ammonium concentration.

  20. Simulated effects of surface coal mining and agriculture on dissolved solids in the Redwater River, east-central Montana

    Science.gov (United States)

    Ferreira, R.F.; Lambing, J.H.

    1985-01-01

    Dissolved solids concentrations in five reaches of the Redwater River in east-central Montana were simulated to evaluate the effects of surface coal mining and agriculture. A mass-balance model of streamflow and dissolved solids load developed for the Tongue River in southeastern Montana was modified and applied to the Redwater River. Mined acreages, dissolved solids concentrations in mined spoils, and irrigated acreage can be varied in the model to study relative changes in the dissolved solids concentration in consecutive reaches of the river. Because of extreme variability and a limited amount of data, the model was not consecutively validated. Simulated mean and median monthly mean streamflows and consistently larger than those calculated from streamflow records. Simulated mean and median monthly mean dissolved solids loads also are consistently larger than regression-derived values. These discrepancies probably result from extremely variable streamflow, overestimates of streamflow from ungaged tributaries, and weak correlations between streamflow and dissolved solids concentrations. The largest increases in simulated dissolved solids concentrations from mining and agriculture occur from September through January because of smaller streamflows and dissolved solids loads. Different combinations of agriculture and mining under mean flow conditions resulted in cumulative percentage increases of dissolved solids concentrations of less than 5% for mining and less than 2% for agriculture. (USGS)

  1. In Situ Bioreduction of Uranium (VI) to Submicromolar Levels and Reoxidation by Dissolved Oxygen

    International Nuclear Information System (INIS)

    Wu, Weimin; Carley, Jack M.; Luo, Jian; Ginder-Vogel, Matthew A.; Cardenas, Erick; Leigh, Mary Beth; Hwang, Chaichi; Kelly, Shelly D.; Ruan, Chuanmin; Wu, Liyou; Van Nostrand, Joy; Gentry, Terry J.; Lowe, Kenneth Alan; Mehlhorn, Tonia L.; Carroll, Sue L.; Luo, Wensui; Fields, Matthew Wayne; Gu, Baohua; Watson, David B.; Kemner, Kenneth M.; Marsh, Terence; Tiedje, James; Zhou, Jizhong; Fendorf, Scott; Kitanidis, Peter K.; Jardine, Philip M.; Criddle, Craig

    2007-01-01

    Groundwater within Area 3 of the U.S. Department of Energy (DOE) Environmental Remediation Sciences Program (ERSP) Field Research Center at Oak Ridge, TN (ORFRC) contains up to 135 (micro)M uranium as U(VI). Through a series of experiments at a pilot scale test facility, we explored the lower limits of groundwater U(VI) that can be achieved by in-situ biostimulation and the effects of dissolved oxygen on immobilized uranium. Weekly 2 day additions of ethanol over a 2-year period stimulated growth of denitrifying, Fe(III)-reducing, and sulfate-reducing bacteria, and immobilization of uranium as U(IV), with dissolved uranium concentrations decreasing to low levels. Following sulfite addition to remove dissolved oxygen, aqueous U(VI) concentrations fell below the U.S. Environmental Protection Agency maximum contaminant limit (MCL) for drinking water ( -1 or 0.126 (micro)M). Under anaerobic conditions, these low concentrations were stable, even in the absence of added ethanol. However, when sulfite additions stopped, and dissolved oxygen (4.0-5.5 mg L -1 ) entered the injection well, spatially variable changes in aqueous U(VI) occurred over a 60 day period, with concentrations increasing rapidly from <0.13 to 2.0 (micro)M at a multilevel sampling (MLS) well located close to the injection well, but changing little at an MLS well located further away. Resumption of ethanol addition restored reduction of Fe(III), sulfate, and U(VI) within 36 h. After 2 years of ethanol addition, X-ray absorption near-edge structure spectroscopy (XANES) analyses indicated that U(IV) comprised 60-80% of the total uranium in sediment samples. At the completion of the project (day 1260), U concentrations in MLS wells were less than 0.1 (micro)M. The microbial community at MLS wells with low U(VI) contained bacteria that are known to reduce uranium, including Desulfovibrio spp. and Geobacter spp., in both sediment and groundwater. The dominant Fe(III)-reducing species were Geothrix spp

  2. Total mercury concentration in common fish species of Lake Victoria ...

    African Journals Online (AJOL)

    Total mercury (THg) concentration was analysed in muscles of common fish species of Lake Victoria in the eastern and southern parts of the lake using cold vapour Atomic Absorption Spectrophotometric technique. Mercury concentration in all fish species was generally lower than the WHO maximum allowable ...

  3. Effect of sucralfate on total carbon dioxide concentration in horses subjected to a simulated race test.

    Science.gov (United States)

    Caltabilota, T J; Milizio, J G; Malone, S; Kenney, J D; McKeever, K H

    2010-02-01

    The purpose of this study was to test the hypothesis that sucralfate, a gastric ulcer medication, would alter plasma concentrations of total carbon dioxide (tCO2), lactate (LA), sodium (Na+), potassium (K+), chloride (Cl-) and total protein (TP), as well as calculated plasma strong ion difference (SID) and packed cell volume (PCV) in horses subjected to a simulated race test (SRT). Six unfit Standardbred mares (approximately 520 kg, 9-18 years) were used in a randomized crossover design with the investigators blinded to the treatment given. The horses were assigned to either a control (40-50 mL apple sauce administered orally (PO)) or a sucralfate (20 mg/kg bodyweight dissolved in 40-50 mL apple sauce administered PO) group. Each horse completed a series of SRTs during which blood samples were taken via jugular venipuncture at five sampling intervals (prior to receiving treatment, prior to SRT, immediately following exercise, and at 60 and 90 min post-SRT). During the SRTs, each horse ran on a treadmill fixed on a 6% grade for 2 min at a warm-up speed (4 m/s) and then for 2 min at a velocity predetermined to produce VO2max. Each horse then walked at 4 m/s for 2 min to complete the SRT. Plasma tCO2, electrolytes, LA, and blood PCV and TP were analysed at all intervals. No differences (P>0.05) were detected between control and sucralfate for any of the measured variables. There were differences (P<0.05) in tCO2, SID, PCV, TP, LA and electrolyte concentrations relative to sampling time. However, these differences were attributable to the physiological pressures associated with acute exercise and were not an effect of the medication. It was concluded that sucralfate did not alter plasma tCO2 concentration in this study. Copyright (c) 2008 Elsevier Ltd. All rights reserved.

  4. Exchange of reactive nitrogen compounds: concentrations and fluxes of total ammonium and total nitrate above a spruce canopy

    Directory of Open Access Journals (Sweden)

    V. Wolff

    2010-05-01

    Full Text Available Total ammonium (tot-NH4+ and total nitrate (tot-NO3 provide chemically conservative quantities in the measurement of surface exchange of reactive nitrogen compounds ammonia (NH3, particulate ammonium (NH4+, nitric acid (HNO3, and particulate nitrate (NO3, using the aerodynamic gradient method. Total fluxes were derived from concentration differences of total ammonium (NH3 and NH4+ and total nitrate (HNO3 and NO3 measured at two levels. Gaseous species and related particulate compounds were measured selectively, simultaneously and continuously above a spruce forest canopy in south-eastern Germany in summer 2007. Measurements were performed using a wet-chemical two-point gradient instrument, the GRAEGOR. Median concentrations of NH3, HNO3, NH4+, and NO3 were 0.57, 0.12, 0.76, and 0.48 μg m−3, respectively. Total ammonium and total nitrate fluxes showed large variations depending on meteorological conditions, with concentrations close to zero under humid and cool conditions and higher concentrations under dry conditions. Mean fluxes of total ammonium and total nitrate in September 2007 were directed towards the forest canopy and were −65.77 ng m−2 s−1 and −41.02 ng m−2 s−1 (in terms of nitrogen, respectively. Their deposition was controlled by aerodynamic resistances only, with very little influence of surface resistances. Including measurements of wet deposition and findings of former studies on occult deposition (fog water interception at the study site, the total N deposition in September 2007 was estimated to 5.86 kg ha−1.

  5. Specific Conductance and Dissolved-Solids Characteristics for the Green River and Muddy Creek, Wyoming, Water Years 1999-2008

    Science.gov (United States)

    Clark, Melanie L.; Davidson, Seth L.

    2009-01-01

    Southwestern Wyoming is an area of diverse scenery, wildlife, and natural resources that is actively undergoing energy development. The U.S. Department of the Interior's Wyoming Landscape Conservation Initiative is a long-term science-based effort to assess and enhance aquatic and terrestrial habitats at a landscape scale, while facilitating responsible energy development through local collaboration and partnerships. Water-quality monitoring has been conducted by the U.S. Geological Survey on the Green River near Green River, Wyoming, and Muddy Creek near Baggs, Wyoming. This monitoring, which is being conducted in cooperation with State and other Federal agencies and as part of the Wyoming Landscape Conservation Initiative, is in response to concerns about potentially increased dissolved solids in the Colorado River Basin as a result of energy development. Because of the need to provide real-time dissolved-solids concentrations for the Green River and Muddy Creek on the World Wide Web, the U.S. Geological Survey developed regression equations to estimate dissolved-solids concentrations on the basis of continuous specific conductance using relations between measured specific conductance and dissolved-solids concentrations. Specific conductance and dissolved-solids concentrations were less varied and generally lower for the Green River than for Muddy Creek. The median dissolved-solids concentration for the site on the Green River was 318 milligrams per liter, and the median concentration for the site on Muddy Creek was 943 milligrams per liter. Dissolved-solids concentrations ranged from 187 to 594 milligrams per liter in samples collected from the Green River during water years 1999-2008. Dissolved-solids concentrations ranged from 293 to 2,485 milligrams per liter in samples collected from Muddy Creek during water years 2006-08. The differences in dissolved-solids concentrations in samples collected from the Green River compared to samples collected from Muddy

  6. Microbial community evolution during simulated managed aquifer recharge in response to different biodegradable dissolved organic carbon (BDOC) concentrations.

    Science.gov (United States)

    Li, Dong; Alidina, Mazahirali; Ouf, Mohamed; Sharp, Jonathan O; Saikaly, Pascal; Drewes, Jörg E

    2013-05-01

    This study investigates the evolution of the microbial community in laboratory-scale soil columns simulating the infiltration zone of managed aquifer recharge (MAR) systems and analogous natural aquifer sediment ecosystems. Parallel systems were supplemented with either moderate (1.1 mg/L) or low (0.5 mg/L) biodegradable dissolved organic carbon (BDOC) for a period of six months during which time, spatial (1 cm, 30 cm, 60 cm, 90 cm, and 120 cm) and temporal (monthly) analyses of sediment-associated microbial community structure were analyzed. Total microbial biomass associated with sediments was positively correlated with BDOC concentration where a significant decline in BDOC was observed along the column length. Analysis of 16S rRNA genes indicated dominance by Bacteria with Archaea comprising less than 1 percent of the total community. Proteobacteria was found to be the major phylum in samples from all column depths with contributions from Betaproteobacteria, Alphaproteobacteria and Gammaproteobacteria. Microbial community structure at all the phylum, class and genus levels differed significantly at 1 cm between columns receiving moderate and low BDOC concentrations; in contrast strong similarities were observed both between parallel column systems and across samples from 30 to 120 cm depths. Samples from 1 cm depth of the low BDOC columns exhibited higher microbial diversity (expressed as Shannon Index) than those at 1 cm of moderate BDOC columns, and both increased from 5.4 to 5.9 at 1 cm depth to 6.7-8.3 at 30-120 cm depths. The microbial community structure reached steady state after 3-4 months since the initiation of the experiment, which also resulted in an improved DOC removal during the same time period. This study suggested that BDOC could significantly influence microbial community structure regarding both composition and diversity of artificial MAR systems and analogous natural aquifer sediment ecosystems. Copyright © 2013 Elsevier Ltd

  7. Cumulative effects of cascade hydropower stations on total dissolved gas supersaturation.

    Science.gov (United States)

    Ma, Qian; Li, Ran; Feng, Jingjie; Lu, Jingying; Zhou, Qin

    2018-03-01

    Elevated levels of total dissolved gas (TDG) may occur downstream of dams during the spill process. These high levels would increase the incidence of gas bubble disease in fish and cause severe environmental impacts. With increasing numbers of cascade hydropower stations being built or planned, the cumulative effects of TDG supersaturation are becoming increasingly prominent. The TDG saturation distribution in the downstream reaches of the Jinsha River was studied to investigate the cumulative effects of TDG supersaturation resulting from the cascade hydropower stations. A comparison of the effects of the joint operation and the single operation of two hydropower stations (XLD and XJB) was performed to analyze the risk degree to fish posed by TDG supersaturation. The results showed that water with supersaturated TDG generated at the upstream cascade can be transported to the downstream power station, leading to cumulative TDG supersaturation effects. Compared with the single operation of XJB, the joint operation of both stations produced a much higher TDG saturation downstream of XJB, especially during the non-flood discharge period. Moreover, the duration of high TDG saturation and the lengths of the lethal and sub-lethal areas were much higher in the joint operation scenario, posing a greater threat to fish and severely damaging the environment. This work provides a scientific basis for strategies to reduce TDG supersaturation to the permissible level and minimize the potential risk of supersaturated TDG.

  8. Preliminary evaluation of serum total cholesterol concentrations in dogs with osteosarcoma.

    Science.gov (United States)

    Leeper, H; Viall, A; Ruaux, C; Bracha, S

    2017-10-01

    To determine if total serum cholesterol concentrations were altered in dogs with osteosarcoma. To evaluate association of total serum cholesterol concentration with clinical outcomes in dogs with appendicular osteosarcoma. Retrospective, multi-institutional study on 64 dogs with osteosarcoma. Control population consisted of dogs with traumatic bone fractures (n=30) and healthy patients of similar age and weight as those of the osteosarcoma cases (n=31). Survival analysis was done on 35 appendicular osteosarcoma patients that received the current standard of care. Statistical associations were assessed by univariable and multi-variable analysis. Information about age, sex, primary tumour location, total cholesterol concentration, monocytes and lymphocyte counts and alkaline phosphatase were also included. Total cholesterol was elevated above the reference interval (3·89 to 7·12 mmol/L) (150 to 275 mg/dL) in 29 of 64 (45·3%) osteosarcoma-bearing dogs, whereas similar elevations were found in only 3 of 30 (10%) fracture controls (Posteosarcoma. These results suggest that elevated total cholesterol is associated with canine osteosarcoma and may have prognostic significance. © 2017 British Small Animal Veterinary Association.

  9. Influence of dissolved oxygen concentration on the toxicity of potassium cyanide to rainbow trout. [Salmo gairdneri

    Energy Technology Data Exchange (ETDEWEB)

    Downing, K M

    1954-01-01

    The present work was undertaken to see if similar results were obtained when fish were tested in a continuous flow of water in which the concentrations of oxygen and cyanide were kept constant. Periods of survival were measured this way to minimize distortion of results by accumulation of metabolic waste, depletion of oxygen or depletion of poison. Results are summarized as follows: rainbow trout survival in potassium cyanide increased with increase in dissolved oxygen; increase in survival times did not decline as oxygen saturation was approached; and medium survival times of 3.3 minutes or less were normally distributed while those of greater than 13 minutes were log normally distributed. 6 references, 1 figure.

  10. Behaviour of fluoride and dissolved silicon in Gouthami Godavari estuarine environment

    Digital Repository Service at National Institute of Oceanography (India)

    Sarma, V.V.; Sudhakar, U.; Varaprasad, S.J.D.

    The concentrations of fluoride and dissolved silicon in Gouthami-Godavari estuarine region (Andhra Pradesh, India) have been measured as a function of chlorinity during different seasons. Fluoride and dissolved silicon behave conservatively during...

  11. Technical Note: Precise quantitative measurements of total dissolved inorganic carbon from small amounts of seawater using a gas chromatographic system

    Directory of Open Access Journals (Sweden)

    T. Hansen

    2013-10-01

    Full Text Available Total dissolved inorganic carbon (CT is one of the most frequently measured parameters used to calculate the partial pressure of carbon dioxide in seawater. Its determination has become increasingly important because of the rising interest in the biological effects of ocean acidification. Coulometric and infrared detection methods are currently favored in order to precisely quantify CT. These methods however are not sufficiently validated for CT measurements of biological experiments manipulating seawater carbonate chemistry with an extended CT measurement range (~1250–2400 μmol kg–1 compared to natural open ocean seawater (~1950–2200 μmol kg−1. The requirement of total sample amounts between 0.1–1 L seawater in the coulometric- and infrared detection methods potentially exclude their use for experiments working with much smaller volumes. Additionally, precise CT analytics become difficult with high amounts of biomass (e.g., phytoplankton cultures or even impossible in the presence of planktonic calcifiers without sample pre-filtration. Filtration however, can alter CT concentration through gas exchange induced by high pressure. Addressing these problems, we present precise quantification of CT using a small, basic and inexpensive gas chromatograph as a CT analyzer. Our technique is able to provide a repeatability of ±3.1 μmol kg−1, given by the pooled standard deviation over a CT range typically applied in acidification experiments. 200 μL of sample is required to perform the actual CT measurement. The total sample amount needed is 12 mL. Moreover, we show that sample filtration is applicable with only minor alteration of the CT. The method is simple, reliable and with low cumulative material costs. Hence, it is potentially attractive for all researchers experimentally manipulating the seawater carbonate system.

  12. Quantification of Dissolved and Particulate Polyunsaturated Aldehydes in the Adriatic Sea

    Directory of Open Access Journals (Sweden)

    Raffaella Casotti

    2011-03-01

    Full Text Available Polyunsaturated aldehydes (PUA are supposed to play critical roles in chemically-mediated plankton interactions. Laboratory studies suggest that they act as mediators of chemical defense and chemical communication. PUA are oxylipins containing an α,β,γ,δ-unsaturated aldehyde structure element and are mainly found in diatoms. We present here a detailed surface mapping of PUA during a spring bloom of the diatom Skeletonema marinoi in the Adriatic Sea. We monitored dissolved PUA, as well as particulate PUA, which are produced by phytoplankton after cell disintegration. Our survey revealed a patchy distribution of PUA and shows that at most stations S. marinoi is the major contributor to the overall PUA. Our data also suggest that lysis of a diatom bloom can contribute significantly to the dissolved PUA concentrations and that other producers, which are smaller in cell size compared to diatoms, have to be taken into account as well if the total PUA content of marine samples is considered. The analyses of samples collected in deeper water suggests that diatom contribution to PUA decreases with depth, while smaller-sized unidentified organisms take place as dominant contributors to the PUA concentrations.

  13. Temporal Dynamics in the Concentration, Flux, and Optical Properties of Tree-Derived Dissolved Organic Matter in an Epiphyte-Laden Oak-Cedar Forest

    Science.gov (United States)

    Van Stan, John T.; Wagner, Sasha; Guillemette, François; Whitetree, Ansley; Lewis, Julius; Silva, Leticia; Stubbins, Aron

    2017-11-01

    Studies on the fate and transport of dissolved organic matter (DOM) along the rainfall-to-discharge flow pathway typically begin in streams or soils, neglecting the initial enrichment of rainfall with DOM during contact with plant canopies. However, rain water can gather significant amounts of tree-derived DOM (tree-DOM) when it drains from the canopy, as throughfall, and down the stem, as stemflow. We examined the temporal variability of event-scale tree-DOM concentrations, yield, and optical (light absorbance and fluorescence) characteristics from an epiphyte-laden Quercus virginiana-Juniperus virginiana forest on Skidaway Island, Savannah, Georgia (USA). All tree-DOM fluxes were highly enriched in dissolved organic carbon (DOC) compared to rainfall, and epiphytes further increased concentrations. Stemflow DOC concentrations were greater than throughfall across study species, yet larger throughfall water yields produced greater DOC yields versus stemflow. Tree-DOM optical characteristics indicate it is aromatic-rich with fluorescent DOM dominated by humic-like fluorescence, containing 10-20% protein-like (tryptophan-like) fluorescence. Storm size was the only storm condition that strongly correlated with tree-DOM concentration and flux; however, throughfall and stemflow optical characteristics varied little across a wide range of storm conditions (from low magnitude events to intense tropical storms). Annual tree-DOM yields from the study forest (0.8-46 g C m-2 yr-1) were similar to other yields from discrete down-gradient fluxes (litter leachates, soil leachates, and stream discharge) along the rainfall-to-discharge flow path.

  14. Mangroves, a major source of dissolved organic carbon to the oceans

    Science.gov (United States)

    Dittmar, Thorsten; Hertkorn, Norbert; Kattner, Gerhard; Lara, RubéN. J.

    2006-03-01

    Organic matter, which is dissolved in low concentrations in the vast waters of the oceans, contains a total amount of carbon similar to atmospheric carbon dioxide. To understand global biogeochemical cycles, it is crucial to quantify the sources of marine dissolved organic carbon (DOC). We investigated the impact of mangroves, the dominant intertidal vegetation of the tropics, on marine DOC inventories. Stable carbon isotopes and proton nuclear magnetic resonance spectroscopy showed that mangroves are the main source of terrigenous DOC in the open ocean off northern Brazil. Sunlight efficiently destroyed aromatic molecules during transport offshore, removing about one third of mangrove-derived DOC. The remainder was refractory and may thus be distributed over the oceans. On a global scale, we estimate that mangroves account for >10% of the terrestrially derived, refractory DOC transported to the ocean, while they cover only <0.1% of the continents' surface.

  15. Suppression of aqueous corrosion of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} by reducing dissolved oxygen concentration for high-performance magnetic refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Fujieda, S., E-mail: fujieda@tagen.tohoku.ac.jp; Fukamichi, K.; Suzuki, S.

    2014-07-05

    Highlights: • The aqueous corrosion of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} and its suppression were investigated. • The lattice expansion after immersion was caused by the hydrogen absorption. • The itinerant-electron metamagnetic transition became indistinct after immersion. • The aqueous corrosion was suppressed by reducing the dissolved oxygen concentration. - Abstract: The itinerant-electron metamagnetic transition of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} becomes indistinct after immersion in distilled-water containing about 8 ppm of the dissolved oxygen (DO) concentration because of aqueous corrosion. However, the aqueous corrosion of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} is significantly suppressed by reducing the DO concentration. Thus, isothermal magnetic entropy change after immersion for 30 days in deaerated distilled-water with a DO concentration less than 0.1 ppm is larger than that after immersion for 5 days in distilled-water containing about 8 ppm of the DO concentration. Consequently, the reduction of the DO concentration is effective for preservation of the excellent magnetocaloric effects of La(Fe{sub 0.88}Si{sub 0.12}){sub 13} in an aqueous solution, which is a promising heat transfer fluid of room-temperature magnetic refrigeration.

  16. Influence of environmental factors on spectral characteristics of chromophoric dissolved organic matter (CDOM) in Inner Mongolia Plateau, China

    Science.gov (United States)

    Wen, Z. D.; Song, K. S.; Zhao, Y.; Du, J.; Ma, J. H.

    2016-02-01

    Spectral characteristics of chromophoric dissolved organic matter (CDOM) were examined in conjunction with environmental factors in the waters of rivers and terminal lakes within the Hulun Buir plateau, northeast China. Dissolved organic carbon (DOC), total nitrogen (TN), and total phosphorous (TP) were significantly higher in terminal lakes than rivers waters (p CDOM absorption in river waters was significantly lower than terminal lakes. Analysis of the ratio of absorption at 250 to 365 nm (E250 : 365), specific ultraviolet (UV) absorbance (SUVA254), and the spectral slope ratio (Sr) indicated that CDOM in river waters had higher aromaticity, molecular weight, and vascular plant contribution than in terminal lakes. Furthermore, results showed that DOC concentration, CDOM light absorption, and the proportion of autochthonous sources of CDOM in plateau waters were all higher than in other freshwater rivers reported in the literature. The strong evapoconcentration, intense ultraviolet irradiance, and landscape features of the Hulun Buir plateau may be responsible for the above phenomenon. Redundancy analysis (RDA) indicated that the environmental variables total suspended matter (TSM), TN, and electrical conductivity (EC) had a strong correlation with light absorption characteristics, followed by total dissolved solid (TDS) and chlorophyll a. In most sampling locations, CDOM was the dominant non-water light-absorbing substance. Light absorption by non-algal particles often exceeded that by phytoplankton in the plateau waters. Study of these optical-physicochemical correlations is helpful in the evaluation of the potential influence of water quality factors on non-water light absorption in cold plateau water environments. The construction of a correlation between DOC concentration and water quality factors may help contribute to regional estimates of carbon sources and fate for catchment carbon budget assessments.

  17. Dissolved inorganic carbon, total alkalinity, pH, dissolved oxygen, and nutrients collected from profile, discrete sampling, and time series observations using CTD, Niskin bottle, and other instruments from R/V Gulf Challenger near a buoy off the coast of New Hampshire, U.S. in the Gulf of Maine from 2011-01-11 to 2015-11-18 (NCEI Accession 0142327)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains discrete measurements of dissolved inorganic carbon, total alkalinity, pH, dissolved oxygen, and nutrients collected at the buoy off...

  18. Chemical characteristics of dissolved organic matter (DOM) in relation to heavy metal concentrations in soil water from boreal peatlands after clear-cut harvesting

    Science.gov (United States)

    Kiikkilä, O.; Nieminen, T.; Starr, M.; Ukonmaanaho, L.

    2012-04-01

    Boreal peatlands form an important terrestrial carbon reserve and are a major source of dissolved organic matter (DOM) to surface waters, particularly when disturbed through forestry practices such as draining or timber harvesting. Heavy metals show a strong affinity to organic matter and so, along with DOM, heavy metals can be mobilized and transported from the soil to surface waters and sediments where they may become toxic to aquatic organisms and pass up the food chain. The complexation of heavy metals with DOM can be expected to be related and determined by the chemical characteristics of DOM and oxidation/reducing conditions in the peat. We extracted interstitial water from peat samples and determined the concentrations of dissolved organic carbon (DOC), dissolved organic nitrogen (DON) and Al, Cu, Zn and Fe in various fractions of DOM isolated by adsorption properties (XAD-8 fractionation) and molecular-weight (ultrafiltration). The peat samples were taken from 0-30 and 30-50 cm depth in drained peatland catchments two years after whole-tree or stem-only clear-cut harvesting (Scots pine or Norway spruce) had been carried out. The samples from the upper layer had been subject to alternating saturation/aeration conditions while the deeper layer had been continuously under the water table. The fractionation of DOC and DON according to both adsorption properties and molecular-weight fractions clearly differed between the upper and lower peat layers. While the hydrophobic acid fraction contained proportionally more DOC and DON than the hydrophilic acid fraction in the upper peat layer the results were vice versa in the lower peat layer. High-molecular-weight compounds (> 100 kDa) were proportionally more abundant in the upper and low-molecular-weight compounds (< 1 kDa) in the lower peat layer. These differences are assumed to reflect differences in the aerobic/ anaerobic conditions and degree of decomposition between the two layers. The concentrations of Zn, Al

  19. Absorption features of chromophoric dissolved organic matter (CDOM) and tracing implication for dissolved organic carbon (DOC) in Changjiang Estuary, China

    OpenAIRE

    Zhang, X. Y.; Chen, X.; Deng, H.; Du, Y.; Jin, H. Y.

    2013-01-01

    Chromophoric dissolved organic matter (CDOM) represents the light absorbing fraction of dissolved organic carbon (DOC). Studies have shown that the optical properties of CDOM can be used to infer the distribution and diffusion characteristics of DOC in the estuary and coastal zone. The inversion of DOC concentrations from remote sensing has been implemented in certain regions. In this study we investigate the potential of tracing DOC from CDOM by the measure...

  20. Improved estimates of filtered total mercury loadings and total mercury concentrations of solids from potential sources to Sinclair Inlet, Kitsap County, Washington

    Science.gov (United States)

    Paulson, Anthony J.; Conn, Kathleen E.; DeWild, John F.

    2013-01-01

    Previous investigations examined sources and sinks of mercury to Sinclair Inlet based on historic and new data. This included an evaluation of mercury concentrations from various sources and mercury loadings from industrial discharges and groundwater flowing from the Bremerton naval complex to Sinclair Inlet. This report provides new data from four potential sources of mercury to Sinclair Inlet: (1) filtered and particulate total mercury concentrations of creek water during the wet season, (2) filtered and particulate total mercury releases from the Navy steam plant following changes in the water softening process and discharge operations, (3) release of mercury from soils to groundwater in two landfill areas at the Bremerton naval complex, and (4) total mercury concentrations of solids in dry dock sumps that were not affected by bias from sequential sampling. The previous estimate of the loading of filtered total mercury from Sinclair Inlet creeks was based solely on dry season samples. Concentrations of filtered total mercury in creek samples collected during wet weather were significantly higher than dry weather concentrations, which increased the estimated loading of filtered total mercury from creek basins from 27.1 to 78.1 grams per year. Changes in the concentrations and loading of filtered and particulate total mercury in the effluent of the steam plant were investigated after the water softening process was changed from ion-exchange to reverse osmosis and the discharge of stack blow-down wash began to be diverted to the municipal water-treatment plant. These changes reduced the concentrations of filtered and particulate total mercury from the steam plant of the Bremerton naval complex, which resulted in reduced loadings of filtered total mercury from 5.9 to 0.15 grams per year. Previous investigations identified three fill areas on the Bremerton naval complex, of which the western fill area is thought to be the largest source of mercury on the base

  1. A highly accurate method for determination of dissolved oxygen: Gravimetric Winkler method

    International Nuclear Information System (INIS)

    Helm, Irja; Jalukse, Lauri; Leito, Ivo

    2012-01-01

    Highlights: ► Probably the most accurate method available for dissolved oxygen concentration measurement was developed. ► Careful analysis of uncertainty sources was carried out and the method was optimized for minimizing all uncertainty sources as far as practical. ► This development enables more accurate calibration of dissolved oxygen sensors for routine analysis than has been possible before. - Abstract: A high-accuracy Winkler titration method has been developed for determination of dissolved oxygen concentration. Careful analysis of uncertainty sources relevant to the Winkler method was carried out and the method was optimized for minimizing all uncertainty sources as far as practical. The most important improvements were: gravimetric measurement of all solutions, pre-titration to minimize the effect of iodine volatilization, accurate amperometric end point detection and careful accounting for dissolved oxygen in the reagents. As a result, the developed method is possibly the most accurate method of determination of dissolved oxygen available. Depending on measurement conditions and on the dissolved oxygen concentration the combined standard uncertainties of the method are in the range of 0.012–0.018 mg dm −3 corresponding to the k = 2 expanded uncertainty in the range of 0.023–0.035 mg dm −3 (0.27–0.38%, relative). This development enables more accurate calibration of electrochemical and optical dissolved oxygen sensors for routine analysis than has been possible before.

  2. Laboratory studies of dissolved radiolabelled microcystin-LR in lake water

    DEFF Research Database (Denmark)

    Hyenstrand, Per; Rohrlack, Thomas; Beattie, Kenneth A

    2003-01-01

    The fate of dissolved microcystin-LR was studied in laboratory experiments using surface water taken from a eutrophic lake. Based on initial range finding, a concentration of 50 microg l(-1) dissolved 14C-microcystin-LR was selected for subsequent time-course experiments. The first was performed ...... fractions. The study demonstrated that biodegradation of dissolved microcystin-LR occurred in water collected at a lake surface with carbon dioxide as a major end-product....

  3. Radiation-chemical sanitation of dissolved pollutants and environmental protection

    International Nuclear Information System (INIS)

    Petrukhin, N.V.; Putilov, A.V.

    1986-01-01

    Radiation-chemical sanitation of dissolved toxic pollutants resulted from the production processes of different substances and modern equipment operation is considered. The processes of fundamental industrial sewage processing and, as a result, features of practically total disposal of dissolved toxic agents are considered for the first time

  4. Dissolved organic nitrogen in wet deposition in a coastal city (Keelung) of the southern East China Sea: Origin, molecular composition and flux

    Science.gov (United States)

    Chen, You-Xin; Chen, Hung-Yu; Wang, Wei; Yeh, Jun-Xian; Chou, Wen-Chen; Gong, Gwo-Ching; Tsai, Fu-Jung; Huang, Shih-Jen; Lin, Cheng-Ting

    2015-07-01

    In this study, we collected and analyzed rainwater samples from Keelung, Taiwan, which is a coastal city located south of the East China Sea (ECS). From January 2012 until June 2013, 78 rainwater samples were collected over an 18-month period and were analyzed to examine the total dissolved nitrogen (TDN) and major ions in the rainwater. TDN can be divided into dissolved inorganic nitrogen (DIN) and dissolved organic nitrogen (DON). This study, which focused on the composition of DON, is the first study to employ ultrafiltration to separate DON in wet deposition into low molecular weight-DON (LMW-DON) and high molecular weight-DON (HMW-DON). The concentrations of dissolved nitrogen species observed in the research area between November 2012 and April 2013 were relatively high, whereas those observed between May 2013 and October 2012 were relatively low. The patterns of changes over time were similar to those of non-sea-salt (nss) ions. The concentration of nss-ions was high during months in which the total dissolved nitrogen concentration was also high, which occur frequently during the spring and winter. In addition, the concentration of nss-ions was low during months in which the TDN concentration was low, which primarily occurs during the summer. The amounts of DIN and DON accounted for 63 ± 5% and 37 ± 5% of the TDN, respectively, and the percentage of the DIN was higher during the spring and winter. The concentrations of LMW-DON and HMW-DON, which accounted for 84 ± 3% and 16 ± 3% of the DON, respectively, were both high in the winter and low in the summer. The percentage of LMW-DON increased in the summer, possibly because of the numerous oceanic air masses and typhoons. Furthermore, the percentage of HMW-DON increased in the spring, potentially due to biomass burning during agricultural activities. Regarding the wet deposition fluxes, the DIN (197 ± 10.27 mmol m-2 yr-1) and DON (129 ± 6.82 mmol m-2 yr-1) accounted for approximately 64% and 36% of the

  5. The release of dissolved nutrients and metals from coastal sediments due to resuspension

    Science.gov (United States)

    Kalnejais, Linda H.; Martin, William R.; Bothner, Michael H.

    2010-01-01

    Coastal sediments in many regions are impacted by high levels of contaminants. Due to a combination of shallow water depths, waves, and currents, these sediments are subject to regular episodes of sediment resuspension. However, the influence of such disturbances on sediment chemistry and the release of solutes is poorly understood. The aim of this study is to quantify the release of dissolved metals (iron, manganese, silver, copper, and lead) and nutrients due to resuspension in Boston Harbor, Massachusetts, USA. Using a laboratory-based erosion chamber, a range of typical shear stresses was applied to fine-grained Harbor sediments and the solute concentration at each shear stress was measured. At low shear stress, below the erosion threshold, limited solutes were released. Beyond the erosion threshold, a release of all solutes, except lead, was observed and the concentrations increased with shear stress. The release was greater than could be accounted for by conservative mixing of porewaters into the overlying water, suggesting that sediment resuspension enhances the release of nutrients and metals to the dissolved phase. To address the long-term fate of resuspended particles, samples from the erosion chamber were maintained in suspension for 90. h. Over this time, 5-7% of the particulate copper and silver was released to the dissolved phase, while manganese was removed from solution. Thus resuspension releases solutes both during erosion events and over a longer timescale due to reactions of suspended particles in the water column. The magnitude of the annual solute release during erosion events was estimated by coupling the erosion chamber results with a record of bottom shear stresses simulated by a hydrodynamic model. The release of dissolved copper, lead, and phosphate due to resuspension is between 2% and 10% of the total (dissolved plus particulate phase) known inputs to Boston Harbor. Sediment resuspension is responsible for transferring a significant

  6. Dissolved oxygen mapping: A powerful tool for site assessments and ground water monitoring

    International Nuclear Information System (INIS)

    Newman, W.A.; Kimball, G.

    1992-01-01

    Dissolved oxygen concentration profiles often provide an excellent indication of the natural biological activity of microorganisms in ground water. The analysis of dissolved oxygen in ground water also provides a rapid, inexpensive method for determining the areal extent of contaminant plumes containing aerobically degraded compounds such as petroleum hydrocarbons. Indigenous hydrocarbon degrading organisms are present at most petroleum product spills giving this technique an almost universal application for dissolved hydrocarbons in ground water. Data from several sites will be presented to demonstrate the relationship between oxygen and dissolved contaminant concentrations. The inverse relationship between oxygen concentrations and dissolved contaminants can be used in many ways. During the initial site assessment, rapid on-site testing of ground water can provide real time data to direct drilling by identification of potentially contaminated locations. Several analytical techniques are available that allow field analysis to be performed in less than five minutes. Dissolved oxygen testing also provides an inexpensive way to monitor hydrocarbon migration without expensive gas chromatography. Often a plume of oxygen depleted ground water extends farther downgradient than the dissolved hydrocarbon plume. The depletion of oxygen in a well can provide an early warning system that detects upgradient contamination before the well is impacted by detectable levels of contaminants. Another application is the measurement of the natural degradation potential for aerobic remediation. If an aerobic in-situ remediation is used, dissolved oxygen monitoring provides an inexpensive method to monitor the progress of the remediation

  7. Impact of upwelling events on the sea water carbonate chemistry and dissolved oxygen concentration in the Gulf of Papagayo (Culebra Bay, Costa Rica: Implications for coral reefs

    Directory of Open Access Journals (Sweden)

    Tim Rixen

    2012-04-01

    Full Text Available The Gulf of Papagayo, Pacific coast of Costa Rica, is one of the three seasonal upwelling areas of Mesoamerica. In April 2009, a 29-hour experiment was carried out at the pier of the Marina Papagayo, Culebra Bay. We determined sea surface temperature (SST, dissolved oxygen concentration, salinity, pH, and the partial pressure of CO2 (pCO2. The aragonite saturation state (Ωa as well as the other parameters of the marine carbonate system such as the total dissolved inorganic carbon (DIC and the total alkalinity (TA were calculated based on the measured pH and the pCO2. The entrainment of subsurface waters raised the pCO2 up to 645 µatm. SSTs, dissolved oxygen concentrations decreased form 26.4 to 23.7°C and from 228 to 144 µmol l-1. Ωa dropped down to values of 2.1. Although these changes are assumed to reduce the coral growth, the main reef building coral species within the region (Pocillopora spp. and Pavona clavus reveal growth rates exceeding those measured at other sites in the eastern tropical Pacific. This implies that the negative impact of upwelling on coral growth might be overcompensated by an enhanced energy supply caused by the high density of food and nutrients and more favorable condition for coral growth during the non-upwelling season.El Golfo de Papagayo, costa Pacífica de Costa Rica, es una de las tres regiones de afloramiento estacional de Mesoamérica. Las características físicas y químicas del agua que aflora no habían sido estudiadas. Durante 29 horas en Abril 2009, se estudiaron la temperatura superficial del mar (TSM, la concentración de oxígeno disuelto, salinidad, pH y la presión parcial de CO2 (pCO2, en la Marina Papagayo, Bahía Culebra. Con base en las mediciones de pH y pCO2 se calculó el estado de saturación de la aragonita (Ω y otros parámetros del sistema de carbonatos como lo es el carbono orgánico disuelto (COD y la alcalinidad total (AT. Los resultados indican que el arrastre por convecci

  8. Hydrographic parameters and distribution of dissolved Cu, Ni, Zn and nutrients near Jeddah desalination plant

    Directory of Open Access Journals (Sweden)

    Fallatah Mohammad M.

    2018-04-01

    Full Text Available The development of safe desalination plants with low environmental impact is as important an issue as the supply of drinking water. The desalination plant in Jeddah (Saudi Arabia, Red Sea coast produces freshwater from seawater by multi-stage flash distillation (MSFD and reverse osmosis (RO. The process produces brine as by-product, which is dumped into the sea. The aim of this study was to assess the impact of Jeddah desalination plant on the coastal water in the nearby of the plant. Total concentrations of dissolved Cu, Ni, Zn and nutrients in several locations around the plant were analyzed by cathodic stripping voltammetry. The average levels of dissolved Cu, Ni, and Zn on surface in the sampling locations were 15.02, 11.02, and 68.03 nM respectively, whereas the levels at the seafloor near the discharging point were much higher. Distribution of temperature, salinity, nutrients and dissolved oxygen were quite normal both on surface and in depth.

  9. Effect of gamma radiation on total antioxidant capacity, total lipid concentration and shelf life of finger millet flour

    International Nuclear Information System (INIS)

    Lathika; Manupriya, B.R.; Shenoy, K.B.; Patil, S.L.; Somashekarappa, H.M.

    2016-01-01

    The present study is an attempt to study the impact of gamma radiation on the shelf life, total antioxidant capacity and total lipid concentration of finger millet (Eleusine coracana L.) flour. Finger millet flour was procured from market. Flour samples of 50 g were taken in triplicates in a polyethylene pouch, air sealed and subjected to gamma irradiation doses ranging from 0.25 to 10 kGy and stored in polyethylene bags and plastic containers for a period of 1 year. Within 24 hours of irradiation, the samples were tested for moisture (2 ± 0.2%), total antioxidant capacity (0.12 ± 0.010 mg) and lipid concentration (15 ± 0.4 mg)

  10. Isotope dilution alpha spectrometry for the determination of plutonium concentration in irradiated fuel dissolver solution : IDAS and R-IDAS

    International Nuclear Information System (INIS)

    Ramaniah, M.V.; Jain, H.C.; Aggarwal, S.K.; Chitambar, S.A.; Kavimandan, V.D.; Almaula, A.I.; Shah, P.M.; Parab, A.R.; Sant, V.L.

    1980-01-01

    The report presents a new technique, Isotope Dilution Alpha Spectrometry (IDAS) and Reverse Isotope Dilution Alpha Spectrometry (R-IDAS) for determining the concentration of plutonium in the irradiated fuel dissolver solution. The method exploits sup(238)Pu in IDAS and sup(239)Pu in R-IDAS as a spike and provides an alternative method to Isotope Dilution Mass Spectrometry (IDMS) which requires enriched sup(242)Pu as a spike. Depending upon the burn-up of the fuel, sup(238)Pu or sup(239)Pu is used as a spike to change the sup(238)Pu/(sup(239)Pu+sup(240)Pu)α activity ratio in the sample by a factor of 10. This change is determined by α-spectrometry on electrodeposited sources using a solid state silicon surface barrier detector coupled to a multichannel analyser. The validity of a simple method based on the geometric progression (G.P.) decrease for the far tail of the spectrum to correct for the tail contribution of sup(238)Pu peak (5.50 MeV) to the low energy sup(239)Pu + sup(240)Pu peak (5.17 MeV) is established. Results for the plutonium concentration on different irradiated fuel dissolver solutions with burn-uo ranging from J,000 to 100,000 MWD/TU are presented and compared with those obtained by IDMS. The values obtained by IDAS or R-IDAS and IDMS agree within 0.5%. (auth.)

  11. Distribution of dissolved labile and particulate iron and copper in Terra Nova Bay polynya (Ross Sea, Antarctica) surface waters in relation to nutrients and phytoplankton growth

    Science.gov (United States)

    Rivaro, Paola; Ianni, Carmela; Massolo, Serena; Abelmoschi, M. Luisa; De Vittor, Cinzia; Frache, Roberto

    2011-05-01

    The distribution of the dissolved labile and of the particulate Fe and Cu together with dissolved oxygen, nutrients, chlorophyll a and total particulate matter was investigated in the surface waters of Terra Nova Bay polynya in mid-January 2003. The measurements were conducted within the framework of the Italian Climatic Long-term Interactions of the Mass balance in Antarctica (CLIMA) Project activities. The labile dissolved fraction was operationally defined by employing the chelating resin Chelex-100, which retains free and loosely bound trace metal species. The dissolved labile Fe ranges from below the detection limit (0.15 nM) to 3.71 nM, while the dissolved labile Cu from below the detection limit (0.10 nM) to 0.90 nM. The lowest concentrations for both metals were observed at 20 m depth (the shallowest depth for which metals were measured). The concentration of the particulate Fe was about 5 times higher than the dissolved Fe concentration, ranging from 0.56 to 24.83 nM with an average of 6.45 nM. The concentration of the particulate Cu ranged from 0.01 to 0.71 nM with an average of 0.17 nM. The values are in agreement with the previous data collected in the same area. We evaluated the role of the Fe and Cu as biolimiting metals. The N:dissolved labile Fe ratios (18,900-130,666) would or would not allow a complete nitrate removal, on the basis of the N:Fe requirement ratios that we calculated considering the N:P and the C:P ratios estimated for diatoms. This finding partially agrees with the Si:N ratio that we found (2.29). Moreover we considered a possible influence of the dissolved labile Cu on the Fe uptake process.

  12. Long-term dynamics of dissolved organic carbon: implications for drinking water supply.

    Science.gov (United States)

    Ledesma, José L J; Köhler, Stephan J; Futter, Martyn N

    2012-08-15

    Surface waters are the main source of drinking water in many regions. Increasing organic carbon concentrations are a cause for concern in Nordic countries since both dissolved and particulate organic carbon can transport contaminants and adversely affect drinking water treatment processes. We present a long-term study of dynamics of total (particulate and dissolved) organic carbon (TOC) concentrations in the River Fyris. This river supplies drinking water to approximately 200000 people in Uppsala, Sweden. The River Fyris is a main tributary to Lake Mälaren, which supplies drinking water to approximately 2 million people in the greater Stockholm area. Utilities responsible for drinking water supply in both Uppsala and Stockholm have expressed concerns about possible increases in TOC. We evaluate organic carbon dynamics within the Fyris catchment by calculating areal mass exports using observed TOC concentrations and modeled flows and by modeling dissolved organic carbon (as a proxy for TOC) using the dynamic, process based INCA-C model. Exports of TOC from the catchment ranged from 0.8 to 5.8 g m(-2) year(-1) in the period 1995-2010. The variation in annual exports was related to climatic variability which influenced seasonality and amount of runoff. Exports and discharge uncoupled at the end of 2008. A dramatic increase in TOC concentrations was observed in 2009, which gradually declined in 2010-2011. INCA-C successfully reproduced the intra- and inter-annual variation in concentrations during 1996-2008 and 2010-2011 but failed to capture the anomalous increase in 2009. We evaluated a number of hypotheses to explain the anomaly in 2009 TOC values, ultimately none proved satisfactory. We draw two main conclusions: there is at least one unknown or unmeasured process controlling or influencing surface water TOC and INCA-C can be used as part of the decision-making process for current and future use of rivers for drinking water supply. Copyright © 2012 Elsevier B

  13. Study of the total uranium in underground water in the city of Jimenez, Chihuahua; Estudio del uranio total en agua subterranea en la Ciudad de Jimenez, Chihuahua

    Energy Technology Data Exchange (ETDEWEB)

    Renteria V, M. [Centro de Investigacion de Materiales Avanzados (CIMAV), Av. Miguel de Cervantes Saavedra 120, 31109 Chihuahua (Mexico)]. e-mail: marusia.renteria@cimav.edu.mx

    2004-07-01

    Samples of water of wells in the city of Jimenez, Chihuahua were analyzed, and its were determined the content of total uranium. It was used the technique of extraction of uranium from water adding Bis ( 2- ethylexyl) phosphate and scintillating Beta plate Hi safe, and the measures of the activities were carried out in the portable scintillation detector Thiathler- O Y HIDEX. The obtained interval of concentrations was 0.12 to 0.26 Bq/l that it is finds below the maximum permissible limits that it manages the Mexican regulation. It was found a significant correlation among the concentration of uranium and those total solid dissolved present in the samples. (Author)

  14. In-situ measurement of the dissolved S2- in seafloor diffuse flow system: sensor preparation and calibration

    Institute of Scientific and Technical Information of China (English)

    Ying YE; Xia HUANG; Yi-wen PAN; Chen-hua HAN; Wei ZHAO

    2008-01-01

    The preparation approach and calibration result of an improved type of ion selective electrode (ISE), which is used to measure the total dissolved S2-, are introduced in this paper. The improved Ag/Ag2S electrode uses silver wire as the substrate, which is surrounded by electric polymer containing superfine silver powder. After the stabilization of the epoxy-resin, Ag2ES layer was formed by chemical reaction with 0.2 mol/L (NH4)2S solution for 5 min. With Ag/AgCl as reference electrode, the Ag/Ag2S electrode can be used to measure dissolved S2-. The correlation between the measured potentials and the logarithm of dissolved S2- is found to be linear, within range of the concentration of dissolved S2- from 10-2~10-7 mol/L. The slope of the regression line between measured potential and logarithm of dissolved S2- is about -27.7, which agrees well with the theoretical Nernst value -29.6. Furthermore, the performance of the improved Ag/Ag2S electrode, such as the response time, sensitivity and stability, greatly outweighs the conventional Ag/Ag2S electrode.

  15. Sources and transformations of dissolved lignin phenols and chromophoric dissolved organic matter in Otsuchi Bay, Japan

    Directory of Open Access Journals (Sweden)

    Chia-Jung eLu

    2016-06-01

    Full Text Available Dissolved lignin phenols and optical properties of dissolved organic matter (DOM were measured to investigate the sources and transformations of terrigenous DOM (tDOM in Otsuchi Bay, Japan. Three rivers discharge into the bay, and relatively high values of syringyl:vanillyl phenols (0.73 ± 0.07 and cinnamyl:vanillyl phenols (0.33 ± 0.10 indicated large contributions of non-woody angiosperm tissues to lignin and tDOM. The physical mixing of river and seawater played an important role in controlling the concentrations and distributions of lignin phenols and chromophoric DOM (CDOM optical properties in the bay. Lignin phenol concentrations and the CDOM absorption coefficient at 350 nm, a(350, were strongly correlated in river and bay waters. Measurements of lignin phenols and CDOM in bay waters indicated a variety of photochemical and biological transformations of tDOM, including oxidation reactions, photobleaching and a decrease in molecular weight. Photodegradation and biodegradation of lignin and CDOM were investigated in decomposition experiments with river water and native microbial assemblages exposed to natural sunlight or kept in the dark. There was a rapid and substantial removal of lignin phenols and CDOM during the first few days in the light treatment, indicating transformations of tDOM and CDOM can occur soon after discharge of buoyant river water into the bay. The removal of lignin phenols was slightly greater in the dark (34% than in the light (30% during the remaining 59 days of the incubation. Comparison of the light and dark treatments indicated biodegradation was responsible for 67% of total lignin phenol removal during the 62-day incubation exposed to natural sunlight, indicating biodegradation is a dominant removal process in Otsuchi Bay.

  16. Crustacean zooplankton release copious amounts of dissolved organic matter as taurine in the ocean.

    Science.gov (United States)

    Clifford, Elisabeth L; Hansell, Dennis A; Varela, Marta M; Nieto-Cid, Mar; Herndl, Gerhard J; Sintes, Eva

    2017-11-01

    Taurine (Tau), an amino acid-like compound, is present in almost all marine metazoans including crustacean zooplankton. It plays an important physiological role in these organisms and is released into the ambient water throughout their life cycle. However, limited information is available on the release rates by marine organisms, the concentrations and turnover of Tau in the ocean. We determined dissolved free Tau concentrations throughout the water column and its release by abundant crustacean mesozooplankton at two open ocean sites (Gulf of Alaska and North Atlantic). At both locations, the concentrations of dissolved free Tau were in the low nM range (up to 15.7 nM) in epipelagic waters, declining sharply in the mesopelagic to about 0.2 nM and remaining fairly stable throughout the bathypelagic waters. Pacific amphipod-copepod assemblages exhibited lower dissolved free Tau release rates per unit biomass (0.8 ± 0.4 μmol g -1 C-biomass h -1 ) than Atlantic copepods (ranging between 1.3 ± 0.4 μmol g -1 C-biomass h -1 and 9.5 ± 2.1 μmol g -1 C-biomass h -1 ), in agreement with the well-documented inverse relationship between biomass-normalized excretion rates and body size. Our results indicate that crustacean zooplankton might contribute significantly to the dissolved organic matter flux in marine ecosystems via dissolved free Tau release. Based on the release rates and assuming steady state dissolved free Tau concentrations, turnover times of dissolved free Tau range from 0.05 d to 2.3 d in the upper water column and are therefore similar to those of dissolved free amino acids. This rapid turnover indicates that dissolved free Tau is efficiently consumed in oceanic waters, most likely by heterotrophic bacteria.

  17. Study on radon concentration in groundwater of Sira and Tiptur taluk of Tumkur district, Karnataka, India

    Directory of Open Access Journals (Sweden)

    M B Karthik Kumar

    2017-01-01

    Full Text Available A study on radon concentration in groundwater samples collected from different villages of Sira and Tiptur taluk of Tumkur district has been conducted using emanometry method, and the effective dose to the public was estimated. The geometric mean of the activity concentration of dissolved radon was found to be 39.13 ± 1.99 and 3.78 ± 0.05 Bq/L for Sira and Tiptur taluk, respectively. The total annual effective dose for adult, children, and infants was also estimated and was found to be 0.20, 0.18, and 0.31 mSv/year, respectively, in Sira taluk and 0.019, 0.017, and 0.029 mSv/year in Tiptur taluk, respectively. Water samples were also analyzed for the physicochemical parameters to assess the quality of drinking water and also to understand the influence of these parameters on dissolved radon concentration. Poor correlation was observed between dissolved radon concentration and pH in both taluks.

  18. [Influence of decomposition of Cladophora sp. on phosphorus concentrations and forms in the overlying water].

    Science.gov (United States)

    Hou, Jin-Zhi; Wei, Quan; Gao, Li; Sun, Wei-Ming

    2013-06-01

    Sediments were sampled in the dominated zone of Cladophora sp. in Rongcheng Swan Lake, and cultivated with algae in the laboratory to reveal the influence of Cladophora decomposition on concentrations and forms of phosphorus in the overlying water. Concentrations of total phosphorus (TP), dissolved total phosphorus (DTP), soluble reactive phosphorus (SRP), particulate phosphorus (PP) and dissolved organic phosphorus (DOP) in overlying water were investigated, and some physicochemical parameters, such as dissolved oxygen (DO), pH and conductivity were monitored during the experiment. In addition, the influence of algae decomposition on P release from sediments was analyzed. Due to the decomposition of Cladophora, DO concentration in the overlying water declined remarkably and reached the anoxic condition (0-0.17 mg x L(-1)). The pH value of different treatments also decreased, and treatments with algae reduced by about 1 unit. Concentrations of TP and different P forms all increased obviously, and the increasing extent was larger with the adding algae amount. TP concentrations of different treatments varied from 0.04 mg x L(-1) to 1.34 mg x L(-1). DOP and PP were the main P forms in the overlying water in algae without sediments treatments, but SRP concentrations became much higher in algae with sediments treatments. The result showed that P forms released from decomposing Cladophora were mainly DOP and PP, and the Cladophora decomposition could also promote the sediments to release P into the overlying water.

  19. Tidal pumping drives nutrient and dissolved organic matter dynamics in a Gulf of Mexico subterranean estuary

    Science.gov (United States)

    Santos, Isaac R.; Burnett, William C.; Dittmar, Thorsten; Suryaputra, I. G. N. A.; Chanton, Jeffrey

    2009-03-01

    We hypothesize that nutrient cycling in a Gulf of Mexico subterranean estuary (STE) is fueled by oxygen and labile organic matter supplied by tidal pumping of seawater into the coastal aquifer. We estimate nutrient production rates using the standard estuarine model and a non-steady-state box model, separate nutrient fluxes associated with fresh and saline submarine groundwater discharge (SGD), and estimate offshore fluxes from radium isotope distributions. The results indicate a large variability in nutrient concentrations over tidal and seasonal time scales. At high tide, nutrient concentrations in shallow beach groundwater were low as a result of dilution caused by seawater recirculation. During ebb tide, the concentrations increased until they reached a maximum just before the next high tide. The dominant form of nitrogen was dissolved organic nitrogen (DON) in freshwater, nitrate in brackish waters, and ammonium in saline waters. Dissolved organic carbon (DOC) production was two-fold higher in the summer than in the winter, while nitrate and DON production were one order of magnitude higher. Oxic remineralization and denitrification most likely explain these patterns. Even though fresh SGD accounted for only ˜5% of total volumetric additions, it was an important pathway of nutrients as a result of biogeochemical inputs in the mixing zone. Fresh SGD transported ˜25% of DOC and ˜50% of total dissolved nitrogen inputs into the coastal ocean, with the remainder associated with a one-dimensional vertical seawater exchange process. While SGD volumetric inputs are similar seasonally, changes in the biogeochemical conditions of this coastal plain STE led to higher summertime SGD nutrient fluxes (40% higher for DOC and 60% higher for nitrogen in the summer compared to the winter). We suggest that coastal primary production and nutrient dynamics in the STE are linked.

  20. On the losses of dissolved CO(2) during champagne serving.

    Science.gov (United States)

    Liger-Belair, Gérard; Bourget, Marielle; Villaume, Sandra; Jeandet, Philippe; Pron, Hervé; Polidori, Guillaume

    2010-08-11

    Pouring champagne into a glass is far from being consequenceless with regard to its dissolved CO(2) concentration. Measurements of losses of dissolved CO(2) during champagne serving were done from a bottled Champagne wine initially holding 11.4 +/- 0.1 g L(-1) of dissolved CO(2). Measurements were done at three champagne temperatures (i.e., 4, 12, and 18 degrees C) and for two different ways of serving (i.e., a champagne-like and a beer-like way of serving). The beer-like way of serving champagne was found to impact its concentration of dissolved CO(2) significantly less. Moreover, the higher the champagne temperature is, the higher its loss of dissolved CO(2) during the pouring process, which finally constitutes the first analytical proof that low temperatures prolong the drink's chill and helps it to retain its effervescence during the pouring process. The diffusion coefficient of CO(2) molecules in champagne and champagne viscosity (both strongly temperature-dependent) are suspected to be the two main parameters responsible for such differences. Besides, a recently developed dynamic-tracking technique using IR thermography was also used in order to visualize the cloud of gaseous CO(2) which flows down from champagne during the pouring process, thus visually confirming the strong influence of champagne temperature on its loss of dissolved CO(2).

  1. Nitrous oxide emissions and dissolved oxygen profiling in a full-scale nitrifying activated sludge treatment plant.

    Science.gov (United States)

    Aboobakar, Amina; Cartmell, Elise; Stephenson, Tom; Jones, Mark; Vale, Peter; Dotro, Gabriela

    2013-02-01

    This paper reports findings from online, continuous monitoring of dissolved and gaseous nitrous oxide (N₂O), combined with dissolved oxygen (DO) and ammonia loading, in a full-scale nitrifying activated sludge plant. The study was conducted over eight weeks, at a 210,000 population equivalent sewage treatment works in the UK. Results showed diurnal variability in the gaseous and dissolved N₂O emissions, with hourly averages ranging from 0 to 0.00009 kgN₂O-N/h for dissolved and 0.00077-0.0027 kgN₂O-N/h for gaseous nitrous oxide emissions respectively, per ammonia loading, depending on the time of day. Similarly, the spatial variability was high, with the highest emissions recorded immediately after the anoxic zone and in the final pass of the aeration lane, where ammonia concentrations were typically below 0.5 mg/L. Emissions were shown to be negatively correlated to dissolved oxygen, which fluctuated between 0.5 and 2.5 mgO₂/L, at the control set point of 1.5 mgO₂/L. The resulting dynamic DO conditions are known to favour N₂O production, both by autotrophic and heterotrophic processes in mixed cultures. Average mass emissions from the lane were greater in the gaseous (0.036% of the influent total nitrogen) than in the dissolved (0.01% of the influent total nitrogen) phase, and followed the same diurnal and spatial patterns. Nitrous oxide emissions corresponded to over 34,000 carbon dioxide equivalents/year, adding 13% to the carbon footprint associated with the energy requirements of the monitored lane. A clearer understanding of emissions obtained from real-time data can help towards finding the right balance between improving operational efficiency and saving energy, without increasing N₂O emissions. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Characteristics of dissolved organic matter in the Upper Klamath River, Lost River, and Klamath Straits Drain, Oregon and California

    Science.gov (United States)

    Goldman, Jami H.; Sullivan, Annett B.

    2017-12-11

    Concentrations of particulate organic carbon (POC) and dissolved organic carbon (DOC), which together comprise total organic carbon, were measured in this reconnaissance study at sampling sites in the Upper Klamath River, Lost River, and Klamath Straits Drain in 2013–16. Optical absorbance and fluorescence properties of dissolved organic matter (DOM), which contains DOC, also were analyzed. Parallel factor analysis was used to decompose the optical fluorescence data into five key components for all samples. Principal component analysis (PCA) was used to investigate differences in DOM source and processing among sites.At all sites in this study, average DOC concentrations were higher than average POC concentrations. The highest DOC concentrations were at sites in the Klamath Straits Drain and at Pump Plant D. Evaluation of optical properties indicated that Klamath Straits Drain DOM had a refractory, terrestrial source, likely extracted from the interaction of this water with wetland peats and irrigated soils. Pump Plant D DOM exhibited more labile characteristics, which could, for instance, indicate contributions from algal or microbial exudates. The samples from Klamath River also had more microbial or algal derived material, as indicated by PCA analysis of the optical properties. Most sites, except Pump Plant D, showed a linear relation between fluorescent dissolved organic matter (fDOM) and DOC concentration, indicating these measurements are highly correlated (R2=0.84), and thus a continuous fDOM probe could be used to estimate DOC loads from these sites.

  3. The origin and isotopic composition of dissolved sulfide in groundwater from carbonate aquifers in Florida and Texas

    International Nuclear Information System (INIS)

    Rye, R.O.; Back, W.; Hanshaw, B.B.; Rightmire, C.T.; Pearson, F.J. Jr.

    1981-01-01

    The delta 34 S values of dissolved sulfide and the sulfur isotope fractionations between dissolved sulfide and sulfate species in Floridan ground water generally correlate with dissolved sulfate concentrations which are related to flow patterns and residence time within the aquifer. The dissolved sulfide derives from the slow in situ biogenic reduction of sulfate dissolved from sedimentary gypsum in the aquifer. In areas where the water is oldest, the dissolved sulfide has apparently attained isotopic equilibrium with the dissolved sulfate at the temperature of the system. This approach to equilibrium reflects an extremely slow reduction rate of the dissolved sulfate by bacteria; this slow rate probably results from very low concentrations of organic matter in the aquifer. In the reducing part of the Edwards aquifer, Texas, there is a general down-gradient increase in both dissolved sulfide and sulfate concentrations, but neither the delta 34 S values of sulfide nor the sulfide-sulfate isotope fractionation correlates with the ground-water flow pattern. The dissolved sulfide species appear to be derived primarily from biogenic reduction of sulfate ions whose source is gypsum dissolution although upgradient diffusion of H 2 S gas from deeper oil field brines may be important in places. (author)

  4. Implications for carbon processing beneath the Greenland Ice Sheet from dissolved CO2 and CH4 concentrations of subglacial discharge

    Science.gov (United States)

    Pain, A.; Martin, J.; Martin, E. E.

    2017-12-01

    Subglacial carbon processes are of increasing interest as warming induces ice melting and increases fluxes of glacial meltwater into proglacial rivers and the coastal ocean. Meltwater may serve as an atmospheric source or sink of carbon dioxide (CO2) or methane (CH4), depending on the magnitudes of subglacial organic carbon (OC) remineralization, which produces CO2 and CH4, and mineral weathering reactions, which consume CO2 but not CH4. We report wide variability in dissolved CO2 and CH4 concentrations at the beginning of the melt season (May-June 2017) between three sites draining land-terminating glaciers of the Greenland Ice Sheet. Two sites, located along the Watson River in western Greenland, drain the Isunnguata and Russell Glaciers and contained 1060 and 400 ppm CO2, respectively. In-situ CO2 flux measurements indicated that the Isunnguata was a source of atmospheric CO2, while the Russell was a sink. Both sites had elevated CH4 concentrations, at 325 and 25 ppm CH4, respectively, suggesting active anaerobic OC remineralization beneath the ice sheet. Dissolved CO2 and CH4 reached atmospheric equilibrium within 2.6 and 8.6 km downstream of Isunnguata and Russell discharge sites, respectively. These changes reflect rapid gas exchange with the atmosphere and/or CO2 consumption via instream mineral weathering. The third site, draining the Kiagtut Sermiat in southern Greenland, had about half atmospheric CO2 concentrations (250 ppm), but approximately atmospheric CH4 concentrations (2.1 ppm). Downstream CO2 flux measurements indicated ingassing of CO2 over the entire 10-km length of the proglacial river. CO2 undersaturation may be due to more readily weathered lithologies underlying the Kiagtut Sermiat compared to Watson River sites, but low CH4 concentrations also suggest limited contributions of CO2 and CH4 from OC remineralization. These results suggest that carbon processing beneath the Greenland Ice Sheet may be more variable than previously recognized

  5. Relationship between red wine grades and phenolics. 1. Tannin and total phenolics concentrations.

    Science.gov (United States)

    Mercurio, Meagan D; Dambergs, Robert G; Cozzolino, Daniel; Herderich, Markus J; Smith, Paul A

    2010-12-08

    Measuring chemical composition is a common approach to support decisions about allocating foods and beverages to grades related to market value. Red wine is a particularly complex beverage, and multiple compositional attributes are needed to account for its sensory properties, including measurement of key phenolic components such as anthocyanins, total phenolics, and tannin, which are related to color and astringency. Color has been shown to relate positively to red wine grade; however, little research has been presented that explores the relationship between astringency-related components such as total phenolic or tannin concentration and wine grade. The aim of this research has been to investigate the relationship between the wine grade allocations of commercial wineries and total phenolic and tannin concentrations, respectively, in Australian Shiraz and Cabernet Sauvignon wines. Total phenolic and tannin concentrations were determined using the methyl cellulose precipitable (MCP) tannin assay and then compared to wine grade allocations made by winemaker panels during the companies' postvintage allocation process. Data were collected from wines produced by one Australian wine company over the 2005, 2006, and 2007 vintages and by a further two companies in 2007 (total wines = 1643). Statistical analysis revealed a positive trend toward higher wine grade allocation and wines that had higher concentrations of both total phenolics and tannin, respectively. This research demonstrates that for these companies, in general, Cabernet Sauvignon and Shiraz wines allocated to higher market value grades have higher total phenolics and higher tannin concentrations and suggests that these compositional parameters should be considered in the development of future multiparameter decision support systems for relevant commercial red wine grading processes. In addition, both tannin and total phenolics would ideally be included because although, in general, a positive relationship

  6. Methodology to quantify the role of the factors controlling the variation of rivers' total dissolved solids in Jiu Catchment (Romania)

    Science.gov (United States)

    Adina Morosanu, Gabriela; Zaharia, Liliana; Ioana-Toroimac, Gabriela; Belleudy, Philippe

    2017-04-01

    The total dissolved solids (TDS) is a river water quality parameter reflecting its concentration in solute ions. It is sensitive to many physical and anthropogenic features of the watershed. In this context, the objective of this work is to analyze the spatial variation of the TDS and to identify the role of the main controlling factors (e.g. geology, soils, land use) in Jiu River and some of its main tributaries, by using a methodology based on GIS and multivariate analysis. The Jiu watershed (10,000 kmp) is located in south-western Romania and it has a high diversity of physical and anthropogenic features influencing the water flow and its quality. The study is based on TDS measurements performed in August, 2016, during low flow conditions in the Jiu River and its tributaries. To measure in situ the TDS (ppm), an EC/TDS/Temperature Hand-held Tester was used in the 12 measuring points on Jiu River and in another 7 points on some of its tributaries. Across the hydrographic basin, the recorded TDS values ranged from 31 ppm to 607 ppm, while in the case of Jiu River, the TDS varied between 38 ppm at Lonea station (upper Jiu River) and 314 ppm at Išalniča (in the lower course). For each catchment corresponding to the sampling points, the influence of some contiguous features was defined on the basis of the lithology (marls, limestones, erodible bedrocks) and soils (clay textures), as well as the land cover/use influencing the solubility and solid content. This assessment was carried out in GIS through a set of spatial statistics analysis by calculating the percentages of the catchment coverage area for each determinant. In order to identify the contributions of different catchment features on the TDS variability, principal components analysis (PCA) was then applied. The results revealed the major role of the marls and clayey soils in the increase of TDS (on the Amaradia and Gilort rivers and some sections in the middle course of the Jiu River). In contrast

  7. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory : evaluation of alkaline persulfate digestion as an alternative to Kjeldahl digestion for determination of total and dissolved nitrogen and phosphorus in water

    Science.gov (United States)

    Patton, Charles J.; Kryskalla, Jennifer R.

    2003-01-01

    Alkaline persulfate digestion was evaluated and validated as a more sensitive, accurate, and less toxic alternative to Kjeldahl digestion for routine determination of nitrogen and phosphorus in surface- and ground-water samples in a large-scale and geographically diverse study conducted by U.S. Geological Survey (USGS) between October 1, 2001, and September 30, 2002. Data for this study were obtained from about 2,100 surface- and ground-water samples that were analyzed for Kjeldahl nitrogen and Kjeldahl phosphorus in the course of routine operations at the USGS National Water Quality Laboratory (NWQL). These samples were analyzed independently for total nitrogen and total phosphorus using an alkaline persulfate digestion method developed by the NWQL Methods Research and Development Program. About half of these samples were collected during nominally high-flow (April-June) conditions and the other half were collected during nominally low-flow (August-September) conditions. The number of filtered and whole-water samples analyzed from each flow regime was about equal.By operational definition, Kjeldahl nitrogen (ammonium + organic nitrogen) and alkaline persulfate digestion total nitrogen (ammonium + nitrite + nitrate + organic nitrogen) are not equivalent. It was necessary, therefore, to reconcile this operational difference by subtracting nitrate + nitrite concentra-tions from alkaline persulfate dissolved and total nitrogen concentrations prior to graphical and statistical comparisons with dissolved and total Kjeldahl nitrogen concentrations. On the basis of two-population paired t-test statistics, the means of all nitrate-corrected alkaline persulfate nitrogen and Kjeldahl nitrogen concentrations (2,066 paired results) were significantly different from zero at the p = 0.05 level. Statistically, the means of Kjeldahl nitrogen concentrations were greater than those of nitrate-corrected alkaline persulfate nitrogen concentrations. Experimental evidence strongly

  8. Study on radon concentration in ground water of Sira and Tiptur taluk of Tumkur district, Karnataka, India

    International Nuclear Information System (INIS)

    Karthik Kumar, M.B.; Nagaiah, N.; Mathews, Gladys; Ambika, M.R.

    2016-01-01

    Radon is a naturally occurring, odor less, tasteless, inert gas that cannot be detected by human senses but can be identified by different techniques. Radon has highest solubility in water, with the mole fraction of 1.25 x 10 -5 at 37 ° C which is fifteen times that of the neon and helium. Radon can enter into the human body in two different ways i.e. ingestion and inhalation which affects the human health. In view of this, activity concentration of dissolved 222 Rn was measured in potable water of Sira and Tiptur taluk of Tumkur district and attempts were also made to understand the dependence of dissolved radon concentration on pH, conductivity and the Total Dissolved Solids (TDS)

  9. Dielectric compound parabolic concentrating solar collector with frustrated total internal reflection absorber

    Science.gov (United States)

    Hull, J. R.

    Since its introduction, the concept of nonimaging solar concentrators, as exemplified by the compound parabolic concentrator (CPC) design, has greatly enhanced the ability to collect solar energy efficiently in thermal and photovoltaic devices. When used as a primary concentrator, a CPC can provide significant concentration without the complication of a tracking mechanism and its associated maintenance problems. When used as a secondary, a CPC provides higher total concentration, or for a fixed concentration, tolerates greater tracking error in the primary.

  10. Dissolved organic carbon and chromophoric dissolved organic matter properties of rivers in the USA

    Science.gov (United States)

    Spencer, Robert G. M.; Butler, Kenna D.; Aiken, George R.

    2012-09-01

    Dissolved organic carbon (DOC) concentration and chromophoric dissolved organic matter (CDOM) parameters were measured over a range of discharge in 30 U.S. rivers, covering a diverse assortment of fluvial ecosystems in terms of watershed size and landscape drained. Relationships between CDOM absorption at a range of wavelengths (a254, a350, a440) and DOC in the 30 watersheds were found to correlate strongly and positively for the majority of U.S. rivers. However, four rivers (Colorado, Colombia, Rio Grande and St. Lawrence) exhibited statistically weak relationships between CDOM absorption and DOC. These four rivers are atypical, as they either drain from the Great Lakes or experience significant impoundment of water within their watersheds, and they exhibited values for dissolved organic matter (DOM) parameters indicative of autochthonous or anthropogenic sources or photochemically degraded allochthonous DOM and thus a decoupling between CDOM and DOC. CDOM quality parameters in the 30 rivers were found to be strongly correlated to DOM compositional metrics derived via XAD fractionation, highlighting the potential for examining DOM biochemical quality from CDOM measurements. This study establishes the ability to derive DOC concentration from CDOM absorption for the majority of U.S. rivers, describes characteristics of riverine systems where such an approach is not valid, and emphasizes the possibility of examining DOM composition and thus biogeochemical function via CDOM parameters. Therefore, the usefulness of CDOM measurements, both laboratory-based analyses and in situ instrumentation, for improving spatial and temporal resolution of DOC fluxes and DOM dynamics in future studies is considerable in a range of biogeochemical studies.

  11. Dissolved organic carbon and chromophoric dissolved organic matter properties of rivers in the USA

    Science.gov (United States)

    Spencer, Robert G.M.; Butler, Kenna D.; Aiken, George R.

    2012-01-01

    Dissolved organic carbon (DOC) concentration and chromophoric dissolved organic matter (CDOM) parameters were measured over a range of discharge in 30 U.S. rivers, covering a diverse assortment of fluvial ecosystems in terms of watershed size and landscape drained. Relationships between CDOM absorption at a range of wavelengths (a254, a350, a440) and DOC in the 30 watersheds were found to correlate strongly and positively for the majority of U.S. rivers. However, four rivers (Colorado, Colombia, Rio Grande and St. Lawrence) exhibited statistically weak relationships between CDOM absorption and DOC. These four rivers are atypical, as they either drain from the Great Lakes or experience significant impoundment of water within their watersheds, and they exhibited values for dissolved organic matter (DOM) parameters indicative of autochthonous or anthropogenic sources or photochemically degraded allochthonous DOM and thus a decoupling between CDOM and DOC. CDOM quality parameters in the 30 rivers were found to be strongly correlated to DOM compositional metrics derived via XAD fractionation, highlighting the potential for examining DOM biochemical quality from CDOM measurements. This study establishes the ability to derive DOC concentration from CDOM absorption for the majority of U.S. rivers, describes characteristics of riverine systems where such an approach is not valid, and emphasizes the possibility of examining DOM composition and thus biogeochemical function via CDOM parameters. Therefore, the usefulness of CDOM measurements, both laboratory-based analyses and in situ instrumentation, for improving spatial and temporal resolution of DOC fluxes and DOM dynamics in future studies is considerable in a range of biogeochemical studies.

  12. Constituent concentrations, loads, and yields to Beaver Lake, Arkansas, water years 1999-2008

    Science.gov (United States)

    Bolyard, Susan E.; De Lanois, Jeanne L.; Green, W. Reed

    2010-01-01

    Beaver Lake is a large, deep-storage reservoir used as a drinking-water supply and considered a primary watershed of concern in the State of Arkansas. As such, information is needed to assess water quality, especially nutrient enrichment, nutrient-algal relations, turbidity, and sediment issues within the reservoir system. Water-quality samples were collected at three main inflows to Beaver Lake: the White River near Fayetteville, Richland Creek at Goshen, and War Eagle Creek near Hindsville. Water-quality samples collected over the period represented different flow conditions (from low to high). Constituent concentrations, flow-weighted concentrations, loads, and yields from White River, Richland Creek, and War Eagle Creek to Beaver Lake for water years 1999-2008 were documented for this report. Constituents include total ammonia plus organic nitrogen, dissolved nitrite plus nitrate nitrogen, dissolved orthophosphorus (soluble reactive phosphorus), total phosphorus, total nitrogen, dissolved organic carbon, total organic carbon, and suspended sediment. Linear regression models developed by computer program S-LOADEST were used to estimate loads for each constituent for the 10-year period at each station. Constituent yields and flow-weighted concentrations for each of the three stations were calculated for the study. Constituent concentrations and loads and yields varied with time and varied among the three tributaries contributing to Beaver Lake. These differences can result from differences in precipitation, land use, contributions of nutrients from point sources, and variations in basin size. Load and yield estimates varied yearly during the study period, water years 1999-2008, with the least nutrient and sediment load and yields generally occurring in water year 2006, and the greatest occurring in water year 2008, during a year with record amounts of precipitation. Flow-weighted concentrations of most constituents were greatest at War Eagle Creek near Hindsville

  13. Dissolved organic nitrogen dynamics in the North Sea: A time series analysis (1995-2005)

    Science.gov (United States)

    Van Engeland, T.; Soetaert, K.; Knuijt, A.; Laane, R. W. P. M.; Middelburg, J. J.

    2010-09-01

    Dissolved organic nitrogen (DON) dynamics in the North Sea was explored by means of long-term time series of nitrogen parameters from the Dutch national monitoring program. Generally, the data quality was good with little missing data points. Different imputation methods were used to verify the robustness of the patterns against these missing data. No long-term trends in DON concentrations were found over the sampling period (1995-2005). Inter-annual variability in the different time series showed both common and station-specific behavior. The stations could be divided into two regions, based on absolute concentrations and the dominant times scales of variability. Average DON concentrations were 11 μmol l -1 in the coastal region and 5 μmol l -1 in the open sea. Organic fractions of total dissolved nitrogen (TDN) averaged 38 and 71% in the coastal zone and open sea, respectively, but increased over time due to decreasing dissolved inorganic nitrogen (DIN) concentrations. In both regions intra-annual variability dominated over inter-annual variability, but DON variation in the open sea was markedly shifted towards shorter time scales relative to coastal stations. In the coastal zone a consistent seasonal DON cycle existed with high values in spring-summer and low values in autumn-winter. In the open sea seasonality was weak. A marked shift in the seasonality was found at the Dogger Bank, with DON accumulation towards summer and low values in winter prior to 1999, and accumulation in spring and decline throughout summer after 1999. This study clearly shows that DON is a dynamic actor in the North Sea and should be monitored systematically to enable us to understand fully the functioning of this ecosystem.

  14. The potential applications of real-time monitoring of water quality in a large shallow lake (Lake Taihu, China) using a chromophoric dissolved organic matter fluorescence sensor.

    Science.gov (United States)

    Niu, Cheng; Zhang, Yunlin; Zhou, Yongqiang; Shi, Kun; Liu, Xiaohan; Qin, Boqiang

    2014-06-30

    This study presents results from field surveys performed over various seasons in a large, eutrophic, shallow lake (Lake Taihu, China) using an in situ chromophoric dissolved organic matter (CDOM) fluorescence sensor as a surrogate for other water quality parameters. These measurements identified highly significant empirical relationships between CDOM concentration measured using the in situ fluorescence sensor and CDOM absorption, fluorescence, dissolved organic carbon (DOC), chemical oxygen demand (COD) and total phosphorus (TP) concentrations. CDOM concentration expressed in quinine sulfate equivalent units, was highly correlated with the CDOM absorption coefficient (r(2) = 0.80, p CDOM concentration measured using the in situ fluorescence sensor could act as a substitute for the CDOM absorption coefficient and fluorescence measured in the laboratory. Similarly, CDOM concentration was highly correlated with DOC concentration (r(2) = 0.68, p CDOM fluorescence sensor measurements could be a proxy for DOC concentration. In addition, significant positive correlations were found between laboratory CDOM absorption coefficients and COD (r(2) = 0.83, p CDOM fluorescence sensor.

  15. Competition for spectral irradiance between epilimnetic optically active dissolved and suspended matter and phytoplankton in the metalimnion. Consequences for limnology and chemistry.

    Science.gov (United States)

    Bracchini, Luca; Dattilo, Arduino Massimo; Falcucci, Margherita; Hull, Vincent; Tognazzi, Antonio; Rossi, Claudio; Loiselle, Steven Arthur

    2011-06-01

    In deep lakes, water column stratification isolates the surface water from the deeper bottom layers, creating a three dimensional differentiation of the chemical, physical, biological and optical characteristics of the waters. Chromophoric dissolved organic matter (CDOM) and total suspended solids (TSS) play an important role in the attenuation of ultraviolet and photosynthetically active radiation. In the present analysis of spectral irradiance, we show that the wavelength composition of the metalimnetic visible irradiance was influenced by epilimnetic spatial distribution of CDOM. We found a low occurrence of blue-green photons in the metalimnion where epilimnetic concentrations of CDOM are high. In this field study, the spatial variation of the spectral irradiance in the metalimnion correlates with the observed metalimnetic concentrations of chlorophyll a as well as chlorophyll a : chlorophyll b/c ratios. Dissolved oxygen, pH, and nutrients trends suggest that chlorophyll a concentrations were representative of the phytoplankton biomass and primary production. Thus, metalimnetic changes of spectral irradiance may have a direct impact on primary production and an indirect effect on the spatial trends of pH, dissolved oxygen, and inorganic nutrients in the metalimnion.

  16. Effect of gamma irradiation on total carbohydrate concentration of finger millet flour

    International Nuclear Information System (INIS)

    Lathika; Patil, Shrikant L.; Bhasker Shenoy, K.; Somashekarappa, H.M.

    2015-01-01

    Ragi or finger millet (Eleusine coracana L.) is one of the common millets in several regions of India. The effect of gamma irradiation, on ragi flour was investigated in the study. Ragi flour is procured from market. Flour samples of 50 gms were taken in triplicates in a polyethylene pouch, air sealed and subjected to gamma irradiation doses ranging from 0.25 to 10 kGy and stored in polyethylene bags and plastic containers for a period of 30 and 90 days. Within 24 hours of irradiation, the samples were tested for total carbohydrate concentration by phenol-sulphuric acid method. The same was repeated after 30 and 90 days of storage. The comparative study showed that, at 0 day, total carbohydrate concentration has decreased slightly when compared to the non-irradiated sample (0.024 mg/ml). The lowest concentration of carbohydrate is seen at 0.025 kGy (0.019mg/ml). The samples stored in polyethylene bag, after 30 days showed both increase (0.056 mg/ml at 0.025 kGy) and decrease (0.04 mg/ml at 10 kGy) in total carbohydrate concentration when compared to control (0.046 mg/ml). 90 days stored samples showed increase in carbohydrate concentration when compared to control (0.029 mg/ml). The highest carbohydrate concentration is seen in 1 kGy dose (0.037 mg/ml). The samples stored at container after 30 days showed both increase (0.045 mg/ml at 5 kGy) and decrease (0.034 mg/ml at 0.025 mg/ml) of carbohydrate concentration when compared to control (0.043 mg/ml). 90 days stored samples showed decrease in carbohydrate concentration when compared to control (0.034 mg/ml). The lowest concentration is seen at 5 kGy (0.022 mg/ml). (author)

  17. AN APPLICATION OF FLOW INJECTION ANALYSIS WITH GAS DIFFUSION AND SPECTROPHOTOMETRIC DETECTION FOR THE MONITORING OF DISSOLVED SULPHIDE CONCENTRATION IN ENVIRONMENTAL SAMPLES

    Directory of Open Access Journals (Sweden)

    Malwina Cykowska

    2014-10-01

    Full Text Available The monitoring of the concentration of sulphide is very important from the environment point of view because of high toxicity of hydrogen sulphide. What is more hydrogen sulphide is an important pollution indicator. In many cases the determination of sulphide is very difficult due to complicated matrix of some environmental samples, which causes that most analytical methods cannot be used. Flow injection analysis allows to avoid matrix problem what makes it suitable for a wide range of applications in analytical laboratories. In this paper determination of dissolved sulphide in environmental samples by gas-diffusion flow injection analysis with spectrophotometric detection was presented. Used gas-diffusion separation ensures the elimination of interferences caused by sample matrix and gives the ability of determination of sulphides in coloured and turbid samples. Studies to optimize the measurement conditions and to determine the value of the validation parameters (e.g. limit of detection, limit of quantification, precision, accuracy were carried out. Obtained results confirm the usefulness of the method for monitoring the concentration of dissolved sulphides in water and waste water. Full automation and work in a closed system greatly reduces time of analysis, minimizes consumption of sample and reagents and increases safety of analyst’s work.

  18. Photonic crystal fiber modal interferometer with Pd/WO3 coating for real-time monitoring of dissolved hydrogen concentration in transformer oil.

    Science.gov (United States)

    Zhang, Ya-Nan; Wu, Qilu; Peng, Huijie; Zhao, Yong

    2016-12-01

    A highly-sensitive and temperature-robust photonic crystal fiber (PCF) modal interferometer coated with Pd/WO 3 film was fabricated and studied, aiming for real-time monitoring of dissolved hydrogen concentration in transformer oil. The sensor probe was fabricated by splicing two segments of a single mode fiber (SMF) with both ends of the PCF. Since the collapse of air holes in the PCF in the interfaces between SMF and PCF, a SMF-PCF-SMF interferometer structure was formed. The Pd/WO 3 film was fabricated by sol-gel method and coated on the surface of the PCF by dip-coating method. When the Pd/WO 3 film is exposed to hydrogen, both the length and cladding refractive index of the PCF would be changed, resulting in the resonant wavelength shift of the interferometer. Experimental results showed that the hydrogen measurement sensitivity of the proposed sensor can reach 0.109 pm/(μl/l) in the transformer oil, with the measurement range of 0-10 000 μl/l and response time less than 33 min. Besides, the proposed sensor was temperature-insensitive without any compensation process, easy to fabricate without any tapering, polishing, or etching process, low cost and quickly response without any oil-gas separation device. All these performances satisfy the actual need of real-time monitoring of dissolved hydrogen concentration in the transformer oil.

  19. Dissolved inorganic carbon, total alkalinity, pH, phosphate, dissolved oxygen, and other variables collected from surface discrete observations using Niksin bottle and other instruments from R/V Sultana in the southwest coast of Puerto Rico from 2009-01-05 to 2016-02-01 (NCEI Accession 0145164)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This time series dataset includes weekly and bi-weekly discrete seawater samples of pH and total alkalinity, dissolved inorganic carbon, phosphates and profile...

  20. Modeling Dissolved Solids in the Rincon Valley, New Mexico Using RiverWare

    Science.gov (United States)

    Abudu, S.; Ahn, S. R.; Sheng, Z.

    2017-12-01

    Simulating transport and storage of dissolved solids in surface water and underlying alluvial aquifer is essential to evaluate the impacts of surface water operations, groundwater pumping, and climate variability on the spatial and temporal variability of salinity in the Rio Grande Basin. In this study, we developed a monthly RiverWare water quantity and quality model to simulate the both concentration and loads of dissolved solids for the Rincon Valley, New Mexico from Caballo Reservoir to Leasburg Dam segment of the Rio Grande. The measured flows, concentration and loads of dissolved solids in the main stream and drains were used to develop RiveWare model using 1980-1988 data for calibration, and 1989-1995 data for validation. The transport of salt is tracked using discretized salt and post-process approaches. Flow and salt exchange between the surface water and adjacent groundwater objects is computed using "soil moisture salt with supplemental flow" method in the RiverWare. In the groundwater objects, the "layered salt" method is used to simulate concentration of the dissolved solids in the shallow groundwater storage. In addition, the estimated local inflows under different weather conditions by using a calibrated Soil Water Assessment Tool (SWAT) were fed into the RiverWare to refine the simulation of the flow and dissolved solids. The results show the salt concentration and loads increased at Leasburg Dam, which indicates the river collects salts from the agricultural return flow and the underlying aquifer. The RiverWare model with the local inflow fed by SWAT delivered the better quantification of temporal and spatial salt exchange patterns between the river and the underlying aquifer. The results from the proposed modeling approach can be used to refine the current mass-balance budgets for dissolved-solids transport in the Rio Grande, and provide guidelines for planning and decision-making to control salinity in arid river environment.

  1. Determination of plutonium isotopic ratios and total concentration by gamma ray spectrometry

    International Nuclear Information System (INIS)

    Despres, Michele.

    1980-11-01

    A non-destructive method of analysis is being investigated for the control in situ of plutonium isotopic composition and total concentration in different matrix without preliminary calibration. The plutonium isotopic composition is determined by gamma-ray spectrometry using germanium detector systems. The same apparatus is used for direct measuring of the total plutonium concentration in solutions or solids by a differential attenuation technique based on two transmitted gamma rays with energies on both sides of the k shell absorption edge of plutonium [fr

  2. Trends in soil solution dissolved organic carbon (DOC) concentrations across European forests

    NARCIS (Netherlands)

    Camino-Serrano, Marta; Graf Pannatier, Elisabeth; Vicca, Sara; Luyssaert, Sebastiaan; Jonard, Mathieu; Ciais, Philippe; Guenet, Bertrand; Gielen, Bert; Peñuelas, Josep; Sardans, Jordi; Waldner, Peter; Sawicka, Kasia

    2016-01-01

    Dissolved organic carbon (DOC) in surface waters is connected to DOC in soil solution through hydrological pathways. Therefore, it is expected that long-term dynamics of DOC in surface waters reflect DOC trends in soil solution. However, a multitude of site studies have failed so far to establish

  3. Trends in soil solution dissolved organic carbon (DOC) concentrations across European forests

    NARCIS (Netherlands)

    Camino-Serrano, M.; Graf Pannatier, E.; Vicca, S.; Luyssaert, S.; Jonard, M.; Ciais, P.; Guenet, B.; Gielen, B.; Peñuelas, J.; Sardans, J.; Waldner, P.; Etzold, S.; Cecchini, G.; Clarke, N.; Galić, Z.; Gandois, L.; Hansen, K.; Johnson, J.; Klinck, U.; Lachmanová, Z.; Lindroos, A.J.; Meesenburg, H.; Nieminen, T.M.; Sanders, T.G.M.; Sawicka, K.; Seidling, W.; Thimonier, A.; Vanguelova, E.; Verstraeten, A.; Vesterdal, L.; Janssens, I.A.

    2016-01-01

    Dissolved organic carbon (DOC) in surface waters is connected to DOC in soil solution through hydrological pathways. Therefore, it is expected that long-term dynamics of DOC in surface waters reflect DOC trends in soil solution. However, a multitude of site studies have failed so far to establish

  4. Modelling daily dissolved oxygen concentration using least square support vector machine, multivariate adaptive regression splines and M5 model tree

    Science.gov (United States)

    Heddam, Salim; Kisi, Ozgur

    2018-04-01

    In the present study, three types of artificial intelligence techniques, least square support vector machine (LSSVM), multivariate adaptive regression splines (MARS) and M5 model tree (M5T) are applied for modeling daily dissolved oxygen (DO) concentration using several water quality variables as inputs. The DO concentration and water quality variables data from three stations operated by the United States Geological Survey (USGS) were used for developing the three models. The water quality data selected consisted of daily measured of water temperature (TE, °C), pH (std. unit), specific conductance (SC, μS/cm) and discharge (DI cfs), are used as inputs to the LSSVM, MARS and M5T models. The three models were applied for each station separately and compared to each other. According to the results obtained, it was found that: (i) the DO concentration could be successfully estimated using the three models and (ii) the best model among all others differs from one station to another.

  5. Measurement and interpretation of low levels of dissolved oxygen in ground water

    Science.gov (United States)

    White, A.F.; Peterson, M.L.; Solbau, R.D.

    1990-01-01

    A Rhodazine-D colorimetric technique was adapted to measure low-level dissolved oxygen concentrations in ground water. Prepared samples containing between 0 and 8.0 ??moles L-1 dissolved oxygen in equilibrium with known gas mixtures produced linear spectrophotometric absorbance with a lower detection limit of 0.2 ??moles L-1. Excellent reproducibility was found for solutions ranging in composition from deionized water to sea water with chemical interferences detected only for easily reduced metal species such as ferric ion, cupric ion, and hexavalent chromium. Such effects were correctable based on parallel reaction stoichiometries relative to oxygen. The technique, coupled with a downhole wire line tool, permitted low-level monitoring of dissolved oxygen in wells at the selenium-contaminated Kesterson Reservoir in California. Results indicated a close association between low but measurable dissolved oxygen concentrations and mobility of oxidized forms of selenium. -from Authors

  6. Photochemical Reactivity of Dissolved Organic Matter in Boreal Lakes

    Science.gov (United States)

    Gu, Y.; Vuorio, K.; Tiirola, M.; Perämäki, S.; Vahatalo, A.

    2016-12-01

    Boreal lakes are rich in dissolved organic matter (DOM) that terrestrially derived from forest soil and wetland, yet little is known about potential for photochemical transformation of aquatic DOM in boreal lakes. Transformation of chromophoric dissolved organic matter (CDOM) can decrease water color and enhance microbial mineralization, affecting primary production and respiration, which both affect the CO2 balance of the lakes. We used laboratory solar radiation exposure experiments with lake water samples collected from 54 lakes located in Finland and Sweden, representing different catchment composition and watershed location to assess photochemical reactivity of DOM. The pH of water samples ranged from 5.4 to 8.3, and the concentrations of dissolved iron (Fe) were between samples received simulated solar radiation corresponding to a daily dose of sunlight, and photomineralization of dissolved organic carbon (DOC) to dissolved inorganic carbon (DIC) was measured for determination of spectral apparent quantum yields (AQY). During irradiation, photobleaching decreased the absorption coefficients of CDOM at 330 nm between 4.9 and 79 m-1 by 0.5 to 11 m-1. Irradiation generated DIC from 2.8 to 79 μmol C L-1. The AQY at 330 nm ranged between 31 and 273 ×10-6 mol C mol photons-1 h-1, which was correlated positively with concentration of dissolved Fe, and negatively with pH. Further statistical analyze indicated that the interaction between pH and Fe may explain much of the photochemical reactivity of DOM in the examined lakes, and land cover concerns main catchment areas also can have impact on the photoreaction process. This study may suggest how environmental conditions regulate DOM photomineralization in boreal lakes.

  7. Release of dissolved 85Kr by standing

    International Nuclear Information System (INIS)

    Ootsuka, Norikatsu; Yamamoto, Tadatoshi; Tsukui, Kohei

    1986-01-01

    The experiments on the release of dissolved 85 Kr by standing at room temperature were carried out to examine the influence of liquid level in a sampler and properties of solvent on the release efficiency. Six kinds of organic solvents as well as water were taken as solvents. The half-life period in case of the decrease in concentration of the dissolved 85 Kr which was used as an index of release efficiency, was proportional to the liquid level in the sampler and was inversely proportional to the diffusion coefficient of Kr gas in solvent. For organic solvents belonging to homologous series, the half-life period became longer with increasing the carbon number of solvent molecule. From the relationship between the half-life period and the carbon number, the release efficiency in the dissolved 85 Kr can be predicted for any commonly used solvent as a practical application. This method was found to be an effective means of removing the dissolved 85 Kr of low level though it takes rather long time. (author)

  8. Total Dissolved Gas Effects on Incubating Chum Salmon Below Bonneville Dam

    Energy Technology Data Exchange (ETDEWEB)

    Arntzen, Evan V.; Hand, Kristine D.; Carter, Kathleen M.; Geist, David R.; Murray, Katherine J.; Dawley, Earl M.; Cullinan, Valerie I.; Elston, Ralph A.; Vavrinec, John

    2009-01-29

    At the request of the U.S. Army Corps of Engineers (USACE; Portland District), Pacific Northwest National Laboratory (PNNL) undertook a project in 2006 to look further into issues of total dissolved gas (TDG) supersaturation in the lower Columbia River downstream of Bonneville Dam. In FY 2008, the third year of the project, PNNL conducted field monitoring and laboratory toxicity testing to both verify results from 2007 and answer some additional questions about how salmonid sac fry respond to elevated TDG in the field and the laboratory. For FY 2008, three objectives were 1) to repeat the 2006-2007 field effort to collect empirical data on TDG from the Ives Island and Multnomah Falls study sites; 2) to repeat the static laboratory toxicity tests on hatchery chum salmon fry to verify 2007 results and to expose wild chum salmon fry to incremental increases in TDG, above those of the static test, until external symptoms of gas bubble disease were clearly present; and 3) to assess physiological responses to TDG levels in wild chum salmon sac fry incubating below Bonneville Dam during spill operations. This report summarizes the tasks conducted and results obtained in pursuit of the three objectives. Chapter 1 discusses the field monitoring, Chapter 2 reports the findings of the laboratory toxicity tests, and Chapter 3 describes the field-sampling task. Each chapter contains an objective-specific introduction, description of the study site and methods, results of research, and discussion of findings. Literature cited throughout this report is listed in Chapter 4. Additional details on the monitoring methodology and results are provided in Appendices A and B included on the compact disc bound inside the back cover of the printed version of this report.

  9. Design and Implementation of Remotely Monitoring System for Total Dissolved Solid in Baghdad Drinking Water Networks

    Directory of Open Access Journals (Sweden)

    Hussein Abdul-Ridha Mohammed

    2018-01-01

    Full Text Available he pollution of drinking water is a dangerous problem for the whole world, it can threaten the health of people and as people in developed society attaches more importance to environmental protection, it is of great research significance to intelligently and remotely monitoring the environment. Therefore in this paper, a remote water monitoring system for Baghdad drinking water system is suggested. The proposed system consists of data sensing and monitoring nodes at different locations in Baghdad to sensing and analyzes the data. These nodes are periodically measured Total Dissolved Solids (TDS. In case of measured value above TDS threshold which is 500 ppm, then an automated warning message will be sent to authorize persons in the maintenance center via Global Position System to take the correct action. This suggested structure has several advantages over traditional monitoring systems in terms of price, portability, reliability, applicability and takes a sample from a water tap in easy and real-time approach.

  10. Characterization of particulate and dissolved phosphorus in tile and nearby riverine systems

    Science.gov (United States)

    Jiang, X.; Arai, Y.; David, M.; Gentry, L.

    2017-12-01

    In the Midwestern U.S., the drainage of agricultural land is predominantly managed by the tile drain system because of its poorly drain properties of clay rich indigenous soils. An accelerated subsurface flow of phosphorus (P) has recently been documented as a primary P transport path in contrast to the typical surface runoff events observed in the Eastern U.S. Recent studies suggested the important role of particulate P (PP) load in agricultural tile drainage water during high flow events. It was hypothesized that PP in the tile water is transported to riverine system contributing to the negative environmental impacts in the Midwestern U.S. In this study, correlation assessment of physicochemical properties of PP in agricultural tile drainage and nearby river samples after a storm event was conducted using a combination of 31P-nuclear magnetic resonance spectroscopy, P K-edge X-ray absorption near edge structure spectroscopy, X-ray diffraction, zetasizer, and transmission electron microscopy. Results show that significantly more colloidal (i.e. 1 nm- 2 µm) and silt-sized (i.e. > 2 µm) particles as well as higher dissolved total P (DTP) and dissolved reactive P (DRP) concentrations existed in river samples than tile samples. Tile and river samples showed similar zeta potential in each particle-size fraction and similar element distributions on colloidal fraction. However, colloidal P concentration and distribution are slightly different between tile and river samples: more colloidal total P and organic P existed in tile colloids than river colloids. The results of P speciation and mineralogical assessment will also be discussed.

  11. The effect of dissolved organic carbon on pelagial and near-sediment water traits in lakes

    Directory of Open Access Journals (Sweden)

    Krzysztof Banaś

    2011-01-01

    Full Text Available The effect of dissolved organic carbon (DOC on the environmental conditions of macrophytes has been studied in 35 lakes divided into soft- and hardwater: oligohumic (16.0 mg C dm-3. The optimum environmental conditions for macrophytes have been found in oligohumic lakes, characterised by low water colour and its good transparency. In soft- and hardwater lakes increasing concentration of DOC is accompanied with an increase in the colour (r=0.95, while the visibility decreases. With increasing DOC in the near-sediment layer the pH values decrease while the concentration of nitrogen increases and the concentration of phosphorus slightly increases. In hardwater lakes with increasing DOC concentration, the redox potential, conductivity, total hardness and calcium concentration in the near-sediment water decrease, whereas the content of CO2 remains at a very low level.

  12. The concentration of optimum dissolved oxygen levels for growth of mangrove crab Scylla serrata seed in recirculation system

    Directory of Open Access Journals (Sweden)

    Kurnia Faturrohman

    2017-07-01

    Full Text Available ABSTRACT This study aimed to determine optimum dissolved oxygen (DO through the addition of aeration and to evaluate the role of dissolved oxygen on production performance and stress responses of mangrove crab Scylla serrata. Experimental design used was complete randomized design with four treatments namely no aeration (A, one point aeration (B, two points aeration (C, and three points aeration (D. All treatments replicated three times. The crab with the average of body weight 45.6±2.1 g/individual cultured in a plastic box (40×30×30 cm3. The stocking densities was 10 crab/box. Crab was cultured within 42 days and were fed two times a day by restricted method (15% of the total biomass. The result showed that C treatment produced 5.51 mg/L dissolved oxygen and gave the best result of mangrove crabs production performance  with 60% survival, 0.83±0.03 g/day absolute growth rate and food conversion ratio 1.1. It also showed good response to the stress that indicated by the cortisol level (10.159 µg/dL. The best results of coefficient of diversity showed by D treatment that was 13.5%. The water quality during study period was fluctuative as affected by different dissolved oxygen value. Keyword: mangrove crabs, dissolved oxygen, production performance  ABSTRAK Penelitian ini bertujuan menentukan kadar oksigen terlarut (OT atau dissolved oxygen (DO yang optimum melalui penentuan titik aerasi serta mengevalusi peranan oksigen terlarut terhadap kinerja produksi dan respons stres kepiting bakau Scylla serrata. Rancangan penelitian yang digunakan adalah rancangan acak lengkap dengan empat pelakuan (penambahan titik aerasi dengan rincian A, tidak menggunakan titik aerasi; B, satu titik aerasi; C, dua titik aerasi dan D, tiga titik aerasi dan tiga ulangan. Kepiting bakau yang digunakan memiliki berat rata-rata 45,6±2,1 g/ekor dengan padat tebar 10 ekor/wadah. Wadah yang digunakan selama pemeliharaan adalah bak fiber plastik yang berukuran 40

  13. 25-hydroxyvitamin D, autoantigenic and total antibody concentrations

    DEFF Research Database (Denmark)

    Thorsen, Steffen Ullitz; Pipper, Christian B; Johannesen, Jesper

    2018-01-01

    conducted within this field. OBJECTIVE: Our objective was to investigate if higher 25-hydroxyvitamin D (25(OH)D) concentrations were inversely associated with β-cell autoantigens glutamic acid decarboxylase (isoform 65) (GADA) and insulinoma associated antigen-2A (IA-2A). Further, we also wanted to examine......BACKGROUND: B cells have recently entered the stage as an important accessory player in type 1 diabetes (T1D) etiopathogenesis. Experimental studies suggest regulatory functions of vitamin D on B cells. However, only a few human studies, with considerable methodological limitations, have been...... the relationship between 25(OH)D and total antibody concentrations. METHODS: We randomly selected 500 patients with newly diagnosed T1D and 500 siblings for 25(OH)D, antibody and genetic analysis from the population-based Danish Registry of Childhood and Adolescent Diabetes. The relative change (RC) in the mean...

  14. Dissolved air flotation for treating wastewater of the nuclear industry. Preliminary results

    International Nuclear Information System (INIS)

    Ortiz-Oliveros, H.B.; Jimenez-Moleon, M.C.; Cruz-Gonzalez, D.

    2012-01-01

    Preliminary testing of dissolved air flotation (DAF) for wastewater treatment is presented. A combined coagulation-flocculation/DAF column system is used to remove oil and 60 Co from nuclear industry wastewater. In this work, operational conditions and coagulant/flocculant concentrations are optimized by varying pH. Determinations of air-solids ratio (G/S), retention time (θ), pressure (P), volume of depressurized air-water mixture (V), turbidity and 60 Co concentrations are reported. The effect of the treatment on the efficiency of separation of oily residues is also discussed. The results establish that the coagulant/flocculant system, formed by a modified polyamine (25 mgL -1 ) and a slightly cationic polyacrylamide (1.5 mgL -1 ), under specific operational conditions (pH = 7, mixing intensity Im 1 = 300 s -1 and Im 2 = 30 s -1 ), allowed the destabilization of colloidal matter, resulting in resistant flocs. It was concluded that by using G/S = 0.3, θ = 15 min, P = 620 kPa and V = 0.0012 m 3 , the greatest percentage removals of oil, turbidity, total cobalt and 60 Co were obtained. These preliminary results then show that dissolved air flotation represents a good alternative for treatment of nuclear industry wastewater contaminated with radionuclides. (author)

  15. Significance of dissolved methane in effluents of anaerobically ...

    Science.gov (United States)

    The need for energy efficient Domestic Wastewater (DWW) treatment is increasing annually with population growth and expanding global energy demand. Anaerobic treatment of low strength DWW produces methane which can be used to as an energy product. Temperature sensitivity, low removal efficiencies (Chemical Oxygen Demand (COD), Suspended Solids (SS), and Nutrients), alkalinity demand, and potential greenhouse gas (GHG) emissions have limited its application to warmer climates. Although well designed anaerobic Membrane Bioreactors (AnMBRs) are able to effectively treat DWW at psychrophilic temperatures (10–30 °C), lower temperatures increase methane solubility leading to increased energy losses in the form of dissolved methane in the effluent. Estimates of dissolved methane losses are typically based on concentrations calculated using Henry's Law but advection limitations can lead to supersaturation of methane between 1.34 and 6.9 times equilibrium concentrations and 11–100% of generated methane being lost in the effluent. In well mixed systems such as AnMBRs which use biogas sparging to control membrane fouling, actual concentrations approach equilibrium values. Non-porous membranes have been used to recover up to 92.6% of dissolved methane and well suited for degassing effluents of Upflow Anaerobic Sludge Blanket (UASB) reactors which have considerable solids and organic contents and can cause pore wetting and clogging in microporous membrane modules. Micro

  16. Recharge processes and vertical transfer investigated through long-term monitoring of dissolved gases in shallow groundwater

    Science.gov (United States)

    de Montety, V.; Aquilina, L.; Labasque, T.; Chatton, E.; Fovet, O.; Ruiz, L.; Fourré, E.; de Dreuzy, J. R.

    2018-05-01

    We investigated temporal variations and vertical evolution of dissolved gaseous tracers (CFC-11, CFC-12, SF6, and noble gases), as well as 3H/3He ratio to determine groundwater recharge processes of a shallow unconfined, hard-rock aquifer in an agricultural catchment. We sampled dissolved gas concentration at 4 locations along the hillslope of a small experimental watershed, over 6 hydrological years, between 2 and 6 times per years, for a total of 20 field campaigns. We collected groundwater samples in the fluctuation zone and the permanently saturated zone using piezometers from 5 to 20 m deep. The purpose of this work is i) to assess the benefits of using gaseous tracers like CFCs and SF6 to study very young groundwater with flows suspected to be heterogeneous and variable in time, ii) to characterize the processes that control dissolved gas concentrations in groundwater during the recharge of the aquifer, and iii) to understand the evolution of recharge flow processes by repeated measurement campaigns, taking advantage of a long monitoring in a site devoted to recharge processes investigation. Gas tracer profiles are compared at different location of the catchment and for different hydrologic conditions. In addition, we compare results from CFCs and 3H/3He analysis to define the flow model that best explains tracer concentrations. Then we discuss the influence of recharge events on tracer concentrations and residence time and propose a temporal evolution of residence times for the unsaturated zone and the permanently saturated zone. These results are used to gain a better understanding of the conceptual model of the catchment and flow processes especially during recharge events.

  17. Effect of concentrate feeding strategy on the performance of dairy cows fed total mixed rations

    Directory of Open Access Journals (Sweden)

    H. KHALILI

    2008-12-01

    Full Text Available Little information is available concerning the effects of offering additional concentrates with total mixed ration (TMR on milk production. The aim of the present study was to compare TMR representing simplified feeding (TMR1 with TMR combined with a decreasing amount of additional concentrate (TMR2C. Finnish Ayrshire cows (39 were housed in a loose housing barn. TMR1 consisted of a mixed ration of grass silage (0.49 and concentrates (0.51. In TMR2C, the same grass silage and concentrate were mixed in a ratio of 55:45. In TMR2C, cows were offered additional concentrates from automatic feeders differing in composition from the concentrate in TMR1 [6.5 kg d-1 (first 100 days, Phase 1, 3.0 kg d-1 (subsequent 50 days, Phase 2 and no concentrate thereafter (Phase 3]. During the whole experiment (224 days, total consumption of concentrates per cow averaged 2426 kg dry matter (TMR1 and 2414 kg dry matter (TMR2C. There were no significant differences in mean total dry matter, metabolizable energy, crude protein or absorbed amino acid intakes. During Phase 2, total intake of all cows fed TMR2C was one kg lower (P = 0.10 than for cows fed TMR1. This was due to differences in total feed intake of multiparous cows. Average yields (kg d-1 of milk, energy corrected milk, protein, fat and lactose were not significantly different between diets. During Phase 2, primiparous cows tended to produce more energy corrected milk on TMR2C than on TMR1. The results showed that both TMR1 and TMR2C were equal feeding strategies for early lactating cows and cows did not benefit from greater concentrate consumption in early stage of lactation when total consumption of concentrates was similar.;

  18. Drying process of fermented inulin fiber concentrate by Bifidobacterium bifidum as a dietary fiber source for cholesterol binder

    Science.gov (United States)

    Susilowati, Agustine; Aspiyanto, Ghozali, Muhammad

    2017-11-01

    Fermentation on inulin hydrolysate as fructooligosaccharides (FOS) by Bifidobacterium bifidum as a result of hydrolysis by inulase enzyme of Scopulariopsis sp.-CBS1 fungi has been performed to bind cholesterol. Their applications on preparation of fermented pour beverages was conducted via a series of concentration process using dead-end Stirred Ultrafiltration Cell (SUFC) mode at stirrer rotation of 400 rpm, room temperature and pressure of 40 psia for 0 minute (pre-concentration process) as concentrate (A) and 45 minutes as concentrate (B), and drying process using vacuum dryer at 30 °C and 22 cm Hg for 0, 8, 16, 24, 32, 40 and 48 hours. Based on optimization of Total Dietary Fiber (TDF), the best time of drying process was achieved for 40 hours. Long time of drying process would increase TDF and total solids, decreased total acids, and fluctuated dissolved protein and Cholesterol Binding Capacity (CBC). At the optimum condition of drying process was get fermented inulin fiber powder from concentration processes using both UF as pre process (0 minute) as concentrate (A) and UF for 45 minutes as concentrate (B) with compositions of total solids of 92.31 % and 93.67 %, TDF of 59.07 % (dry weight) and 69.28 %, total acids of 7.03 % and 7.5 %, dissolved protein of 3.95 mg/mL and 3.05 mg/mL, and CBC pH 2 15.71 mg/g and 16.8 mg/g, respectively. Concentration process through dead-end SUFC mode gave distribution of particles with better smoothness level than without through dead-end SUFC mode.

  19. Utilizing Colored Dissolved Organic Matter to Derive Dissolved Black Carbon Export by Arctic Rivers

    Science.gov (United States)

    Stubbins, Aron; Spencer, Robert; Mann, Paul; Holmes, R.; McClelland, James; Niggemann, Jutta; Dittmar, Thorsten

    2015-10-01

    Wildfires have produced black carbon (BC) since land plants emerged. Condensed aromatic compounds, a form of BC, have accumulated to become a major component of the soil carbon pool. Condensed aromatics leach from soils into rivers, where they are termed dissolved black carbon (DBC). The transport of DBC by rivers to the sea is a major term in the global carbon and BC cycles. To estimate Arctic river DBC export, 25 samples collected from the six largest Arctic rivers (Kolyma, Lena, Mackenzie, Ob’, Yenisey and Yukon) were analyzed for dissolved organic carbon (DOC), colored dissolved organic matter (CDOM), and DBC. A simple, linear regression between DOC and DBC indicated that DBC accounted for 8.9 ± 0.3% DOC exported by Arctic rivers. To improve upon this estimate, an optical proxy for DBC was developed based upon the linear correlation between DBC concentrations and CDOM light absorption coefficients at 254 nm (a254). Relatively easy to measure a254 values were determined for 410 Arctic river samples between 2004 and 2010. Each of these a254 values was converted to a DBC concentration based upon the linear correlation, providing an extended record of DBC concentration. The extended DBC record was coupled with daily discharge data from the six rivers to estimate riverine DBC loads using the LOADEST modeling program. The six rivers studied cover 53% of the pan-Arctic watershed and exported 1.5 ± 0.1 million tons of DBC per year. Scaling up to the full area of the pan-Arctic watershed, we estimate that Arctic rivers carry 2.8 ± 0.3 million tons of DBC from land to the Arctic Ocean each year. This equates to ~8% of Arctic river DOC export, slightly less than indicated by the simpler DBC vs DOC correlation-based estimate. Riverine discharge is predicted to increase in a warmer Arctic. DBC export was positively correlated with river runoff, suggesting that the export of soil BC to the Arctic Ocean is likely to increase as the Arctic warms.

  20. Utilizing Colored Dissolved Organic Matter to Derive Dissolved Black Carbon Export by Arctic Rivers

    Directory of Open Access Journals (Sweden)

    Aron eStubbins

    2015-10-01

    Full Text Available Wildfires have produced black carbon (BC since land plants emerged. Condensed aromatic compounds, a form of BC, have accumulated to become a major component of the soil carbon pool. Condensed aromatics leach from soils into rivers, where they are termed dissolved black carbon (DBC. The transport of DBC by rivers to the sea is a major term in the global carbon and BC cycles. To estimate Arctic river DBC export, 25 samples collected from the six largest Arctic rivers (Kolyma, Lena, Mackenzie, Ob’, Yenisey and Yukon were analyzed for dissolved organic carbon (DOC, colored dissolved organic matter (CDOM, and DBC. A simple, linear regression between DOC and DBC indicated that DBC accounted for 8.9 ± 0.3% DOC exported by Arctic rivers. To improve upon this estimate, an optical proxy for DBC was developed based upon the linear correlation between DBC concentrations and CDOM light absorption coefficients at 254 nm (a254. Relatively easy to measure a254 values were determined for 410 Arctic river samples between 2004 and 2010. Each of these a254 values was converted to a DBC concentration based upon the linear correlation, providing an extended record of DBC concentration. The extended DBC record was coupled with daily discharge data from the six rivers to estimate riverine DBC loads using the LOADEST modeling program. The six rivers studied cover 53% of the pan-Arctic watershed and exported 1.5 ± 0.1 million tons of DBC per year. Scaling up to the full area of the pan-Arctic watershed, we estimate that Arctic rivers carry 2.8 ± 0.3 million tons of DBC from land to the Arctic Ocean each year. This equates to ~8% of Arctic river DOC export, slightly less than indicated by the simpler DBC vs DOC correlation-based estimate. Riverine discharge is predicted to increase in a warmer Arctic. DBC export was positively correlated with river runoff, suggesting that the export of soil BC to the Arctic Ocean is likely to increase as the Arctic warms.

  1. Dissolved organic carbon and its potential predictors in eutrophic lakes.

    Science.gov (United States)

    Toming, Kaire; Kutser, Tiit; Tuvikene, Lea; Viik, Malle; Nõges, Tiina

    2016-10-01

    Understanding of the true role of lakes in the global carbon cycle requires reliable estimates of dissolved organic carbon (DOC) and there is a strong need to develop remote sensing methods for mapping lake carbon content at larger regional and global scales. Part of DOC is optically inactive. Therefore, lake DOC content cannot be mapped directly. The objectives of the current study were to estimate the relationships of DOC and other water and environmental variables in order to find the best proxy for remote sensing mapping of lake DOC. The Boosted Regression Trees approach was used to clarify in which relative proportions different water and environmental variables determine DOC. In a studied large and shallow eutrophic lake the concentrations of DOC and coloured dissolved organic matter (CDOM) were rather high while the seasonal and interannual variability of DOC concentrations was small. The relationships between DOC and other water and environmental variables varied seasonally and interannually and it was challenging to find proxies for describing seasonal cycle of DOC. Chlorophyll a (Chl a), total suspended matter and Secchi depth were correlated with DOC and therefore are possible proxies for remote sensing of seasonal changes of DOC in ice free period, while for long term interannual changes transparency-related variables are relevant as DOC proxies. CDOM did not appear to be a good predictor of the seasonality of DOC concentration in Lake Võrtsjärv since the CDOM-DOC coupling varied seasonally. However, combining the data from Võrtsjärv with the published data from six other eutrophic lakes in the world showed that CDOM was the most powerful predictor of DOC and can be used in remote sensing of DOC concentrations in eutrophic lakes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Studies in the dissolver off-gas system for a spent FBR fuel reprocessing plant

    International Nuclear Information System (INIS)

    Heinrich, E.; Huefner, R.; Weirich, F.

    1982-01-01

    Investigations of possible modifications of the process steps of a dissolver off-gas (DOG) system for a spent FBR fuel reprocessing plant are reported. The following operations are discussed: iodine removal from the fuel solution; behaviour of NOsub(x) and iodine in nitric acid off-gas scrubbers at different temperatures and nitric acid concentrations; iodine desorption from the scrub acid; selective absorption of noble gases in refrigerant-12; cold traps. The combination of suitable procedures to produce a total DOG system is described. (U.K.)

  3. Development of simulation code for FBR spent fuel dissolution with rotary drum type continuous dissolver

    International Nuclear Information System (INIS)

    Sano, Yuichi; Katsurai, Kiyomichi; Washiya, Tadahiro; Koizumi, Tsutomu; Matsumoto, Satoshi

    2011-01-01

    Japan Atomic Energy Agency (JAEA) has been studying rotary drum type continuous dissolver for FBR spent fuel dissolution. For estimating the fuel dissolution behavior under several operational conditions in this dissolver, we have been developing the simulation code, PLUM, which mainly consists of 3 modules for calculating chemical reaction, mass transfer and thermal balance in the rotary drum type continuous dissolver. Under the various conditions where dissolution experiments were carried out with the batch-wise dissolver for FBR spent fuel and with the rotary drum type continuous dissolver for UO 2 fuel, it was confirmed that the fuel dissolution behaviors calculated by the PLUM code showed good agreement with the experimental ones. Based on this result, the condition for obtaining the dissolver solution with high HM (heavy metal : U and Pu) concentration (∼500g/L), which is required for the next step, i.e. crystallization process, was also analyzed by this code and appropriate operational conditions with the rotary drum type continuous dissolver, such as feedrate, concentration and temperature of nitric acid, could be clarified. (author)

  4. Addition of biochar to sewage sludge decreases freely dissolved PAHs content and toxicity of sewage sludge-amended soil.

    Science.gov (United States)

    Stefaniuk, Magdalena; Oleszczuk, Patryk

    2016-11-01

    Due to an increased content of polycyclic aromatic hydrocarbons (PAHs) frequently found in sewage sludges, it is necessary to find solutions that will reduce the environmental hazard associated with their presence. The aim of this study was to determine changes of total and freely dissolved concentration of PAHs in sewage sludge-biochar-amended soil. Two different sewage sludges and biochars with varying properties were tested. Biochars (BC) were produced from biogas residues at 400 °C or 600 °C and from willow at 600 °C. The freely dissolved PAH concentration was determined by means of passive sampling using polyoxymethylene (POM). Total and freely dissolved PAH concentration was monitored at the beginning of the experiment and after 90 days of aging of the sewage sludge with the biochar and soil. Apart from chemical evaluation, the effect of biochar addition on the toxicity of the tested materials on bacteria - Vibrio fischeri (Microtox ® ), plants - Lepidium sativum (Phytotestkit F, Phytotoxkit F), and Collembola - Folsomia candida (Collembolan test) was evaluated. The addition of biochar to the sewage sludges decreased the content of C free PAHs. A reduction from 11 to 43% of sewage sludge toxicity or positive effects on plants expressed by root growth stimulation from 6 to 25% to the control was also found. The range of reduction of C free PAHs and toxicity was dependent on the type of biochar. After 90 days of incubation of the biochars with the sewage sludge in the soil, C free PAHs and toxicity were found to further decrease compared to the soil with sewage sludge alone. The obtained results show that the addition of biochar to sewage sludges may significantly reduce the risk associated with their environmental use both in terms of PAH content and toxicity of the materials tested. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Export of Dissolved Lignin from Coastal Wetlands to the Louisiana Shelf

    Science.gov (United States)

    Bianchi, T. S.; Dimarco, S. F.; Smith, R. W.; Schreiner, K. M.

    2008-12-01

    Here we report on spatial and temporal changes in the concentration and composition of dissolved lignin- phenols in surface and bottom waters off the Louisiana coast (USA). Samples were collected at 7 stations on 2 cruises (April, and July, 2008) along a transect that spanned from inside Terrebonne Bay, Louisiana (12 m water depth) to the outer-most station on the inner Louisiana shelf (21 m water depth). The highest average concentration of dissolved organic carbon (DOC) and dissolved lignin, during both cruises, occurred at the interface between Terrebonne Bay and the inner shelf. Average DOC and dissolved lignin concentrations were significantly higher in April than in July across most stations. Based on hydrologic data, these higher concentrations clearly reflect a combined mixing of DOM from plume waters to the west and local marsh inputs. The cinnamyl/vanillyl (C/V) and syringyl/vanillyl (S/V) ratios indicated that the predominant source of lignin was from non-woody angiosperms - likely the dominant species of wetland plants Spartina alterniflora and S. patens (Spartina spp.) that border the entire bay. The high vanillic acid to vanillin (Ad/Al)v ratios for all stations were typical of that found near estuarine boundaries, where biologically- and photochemically-mediated lignin decay processes are important. This preliminary data indicates that wetlands provide another source of dissolved organic matter (DOM) to the Louisiana shelf that likely contributes to microbial food resources and hence hypoxia, especially in the context of the instability and extensive erosion of these marshes over the past ca. 50 years. This has important implications for the current management plan to reduce hypoxia in the GOM, particularly in those regions that extend west of the nutrient-rich highly productive near-field zones of Atchafalaya-Mississippi river plumes.

  6. [Spectral characteristics of dissolved organic matter released during the metabolic process of small medusa].

    Science.gov (United States)

    Guo, Dong-Hui; Yi, Yue-Yuan; Zhao, Lei; Guo, Wei-Dong

    2012-06-01

    The metabolic processes of jellyfish can produce dissolved organic matter (DOM) which will influence the functioning of the aquatic ecosystems, yet the optical properties of DOM released by jellyfish are unknown. Here we report the absorption and fluorescence properties of DOM released by a medusa species Black fordia virginica during a 24 h incubation experiment. Compared with the control group, an obvious increase in the concentrations of dissolved organic carbon (DOC), absorption coefficient (a280) and total dissolved nitrogen (TDN) was observed in incubation group. This clearly demonstrated the release of DOM, chromophoric DOM (CDOM) and dissolved nutrients by B. virginica which feed on enough of Artemia sp. before the experiment. The increase in spectral slope ratio (SR) and decrease in humification index (HIX) indicated that the released DOM was less-humified and had relatively lower molecular weight. Parallel factor analysis (PARAFAC) decomposed the fluorescence matrices of DOM into three humic-like components (C1-C3) and one protein-like component (C4). The Fmax of two components (C2: 400 nm showed little changes. Thus, we suggested a zooplankton index (ZIX) to trace and characterize the DOM excreted by metabolic activity of zooplankton, which is calculated as the ratio of the sum of Fmax of all fluorescence components with the emission wavelength 400 nm.

  7. Characterization of dissolved solids in water resources of agricultural lands near Manila, Utah, 2004-05

    Science.gov (United States)

    Gerner, Steven J.; Spangler, L.E.; Kimball, B.A.; Naftz, D.L.

    2006-01-01

    Agricultural lands near Manila, Utah, have been identified as contributing dissolved solids to Flaming Gorge Reservoir. Concentrations of dissolved solids in water resources of agricultural lands near Manila, Utah, ranged from 35 to 7,410 milligrams per liter. The dissolved-solids load in seeps and drains in the study area that discharge to Flaming Gorge Reservoir ranged from less than 0.1 to 113 tons per day. The most substantial source of dissolved solids discharging from the study area to the reservoir was Birch Spring Draw. The mean daily dissolved-solids load near the mouth of Birch Spring Draw was 65 tons per day.The estimated annual dissolved-solids load imported to the study area by Sheep Creek and Peoples Canals is 1,330 and 13,200 tons, respectively. Daily dissolved-solid loads discharging to the reservoir from the study area, less the amount of dissolved solids imported by canals, for the period July 1, 2004, to June 30, 2005, ranged from 72 to 241 tons per day with a mean of 110 tons per day. The estimated annual dissolved-solids load discharging to the reservoir from the study area, less the amount of dissolved solids imported by canals, for the same period was 40,200 tons. Of this 40,200 tons of dissolved solids, about 9,000 tons may be from a regional source that is not associated with agricultural activities. The salt-loading factor is 3,670 milligrams per liter or about 5.0 tons of dissolved solids per acre-foot of deep percolation in Lucerne Valley and 1,620 milligrams per liter or 2.2 tons per acre-foot in South Valley.The variation of δ87Sr with strontium concentration indicates some general patterns that help to define a conceptual model of the processes affecting the concentration of strontium and the δ87Sr isotopic ratio in area waters. As excess irrigation water percolates through soils derived from Mancos Shale, the δ87Sr isotopic ratio (0.21 to 0.69 permil) approaches one that is typical of deep percolation from irrigation on Mancos

  8. Determination of diffusible and total hydrogen concentration in coated and uncoated steel

    Energy Technology Data Exchange (ETDEWEB)

    Mabho, Nonhlangabezo

    2010-09-23

    The new trend in the steel industry demands thin, flexible, high strength steels with low internal embrittlement. It is a well known fact that the atomic hydrogen which is picked up during production, fabrication and service embrittles the steel. This has led to an extensive research towards the improvement of the quality of metallic materials by focusing on total and diffusible hydrogen concentrations which are responsible for hydrogen embrittlement. Since the internal embrittlement cannot be foreseen, the concentrations of diffusible hydrogen work as indicators while the total hydrogen characterizes the absorbed quantities and quality of that particular product. To meet these requirements, the analytical chemistry methods which include the already existing carrier gas melt (fusion) extraction methods that use infrared and thermal conductivity for total hydrogen detection were applied. The newly constructed carrier gas thermal desorption mass spectroscopy was applied to monitor the diffusible concentration at specific temperatures and desorption rates of hydrogen which will contribute towards the quality of materials during service. The TDMS method also involved the characterization of the energy quantity (activation energy) required by hydrogen to be removed from traps of which irreversible traps are preferred because they enhance the stability of the product by inhibiting the mobility of hydrogen which is detrimental to the metallic structures. The instrumentation for TDMS is quite simple, compact, costs less and applicable to routine analysis. To determine total and diffusible hydrogen, the influence of the following processes: chemical and mechanical zinc coating removal, sample cleaning with organic solvents, conditions for hydrogen absorption by electrolytic hydrogen charging, conditions of hydrogen desorption by storing the sample at room temperature, solid CO{sub 2} and at temperatures of the drier was analysed. The contribution of steel alloys towards

  9. Soil Fauna Affects Dissolved Carbon and Nitrogen in Foliar Litter in Alpine Forest and Alpine Meadow.

    Science.gov (United States)

    Liao, Shu; Yang, Wanqin; Tan, Yu; Peng, Yan; Li, Jun; Tan, Bo; Wu, Fuzhong

    2015-01-01

    Dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) are generally considered important active biogeochemical pools of total carbon and nitrogen. Many studies have documented the contributions of soil fauna to litter decomposition, but the effects of the soil fauna on labile substances (i.e., DOC and TDN) in litter during early decomposition are not completely clear. Therefore, a field litterbag experiment was carried out from 13th November 2013 to 23rd October 2014 in an alpine forest and an alpine meadow located on the eastern Tibetan Plateau. Litterbags with different mesh sizes were used to provide access to or prohibit the access of the soil fauna, and the concentrations of DOC and TDN in the foliar litter were measured during the winter (the onset of freezing, deep freezing and thawing stage) and the growing season (early and late). After one year of field incubation, the concentration of DOC in the litter significantly decreased, whereas the TDN concentration in the litter increased. Similar dynamic patterns were detected under the effects of the soil fauna on both DOC and TDN in the litter between the alpine forest and the alpine meadow. The soil fauna showed greater positive effects on decreasing DOC concentration in the litter in the winter than in the growing season. In contrast, the dynamics of TND in the litter were related to seasonal changes in environmental factors, rather than the soil fauna. In addition, the soil fauna promoted a decrease in litter DOC/TDN ratio in both the alpine forest and the alpine meadow throughout the first year of decomposition, except for in the late growing season. These results suggest that the soil fauna can promote decreases in DOC and TDN concentrations in litter, contributing to early litter decomposition in these cold biomes.

  10. More on the losses of dissolved CO(2) during champagne serving: toward a multiparameter modeling.

    Science.gov (United States)

    Liger-Belair, Gérard; Parmentier, Maryline; Cilindre, Clara

    2012-11-28

    Pouring champagne into a glass is far from being inconsequential with regard to the dissolved CO(2) concentration found in champagne. Three distinct bottle types, namely, a magnum bottle, a standard bottle, and a half bottle, were examined with regard to their loss of dissolved CO(2) during the service of successively poured flutes. Whatever the bottle size, a decreasing trend is clearly observed with regard to the concentration of dissolved CO(2) found within a flute (from the first to the last one of a whole service). Moreover, when it comes to champagne serving, the bottle size definitely does matter. The higher the bottle volume, the better its buffering capacity with regard to dissolved CO(2) found within champagne during the pouring process. Actually, for a given flute number in a pouring data series, the concentration of dissolved CO(2) found within the flute was found to decrease as the bottle size decreases. The impact of champagne temperature (at 4, 12, and 20 °C) on the losses of dissolved CO(2) found in successively poured flutes for a given standard 75 cL bottle was also examined. Cold temperatures were found to limit the decreasing trend of dissolved CO(2) found within the successively poured flutes (from the first to the last one of a whole service). Our experimental results were discussed on the basis of a multiparameter model that accounts for the major physical parameters that influence the loss of dissolved CO(2) during the service of a whole bottle type.

  11. New approaches to improve the removal of dissolved organic matter and nitrogen in aquaculture

    DEFF Research Database (Denmark)

    von Ahnen, Mathis

    further due to the lack of cost-effective and easy applicable treatment methods for removing dissolved N and OM. The purpose of this PhD thesis was to assess the problem of removing dissolved N and OM in the context of the large differences in system intensity between farms, and to devise new, simple...... at increasing long-term waste loadings. The second part examined the potential of using anoxic denitrifying woodchip bioreactors for removal of nitrate from aquaculture effluent (Paper III-V). Investigations within the first part showed that the effectiveness of biofilters, as determined by their areal removal......-term biofilter loading up to a certain threshold. The latter indicated that the removal capacity of biofilters operated at lower loadings is easily exceeded, and that they may not respond very well to sudden increases in total ammonia nitrogen (TAN) concentrations. In the second part of the thesis, a field study...

  12. Dissolved gasesous hydrocarbons in shallow groundwater of Lower Saxony, Germany - Revisited 2016

    Science.gov (United States)

    Schloemer, Stefan; Illing, Christian J.; Blumenberg, Martin; Oest, Johanna; Elbracht, Jörg

    2017-04-01

    Many concerns arise within the public and government/political institutions over potential groundwater contamination from deep drilling operations. For this reason we initiated a baseline study in 2014 on the distribution of dissolved methane, ethane and propane in shallow groundwater ( 1000 groundwater wells, Schloemer et al., 2016) of Lower Saxony, which includes the major petroleum and natural gas provinces in Germany. We observed a variation of dissolved methane concentration over 7 orders of magnitude (20 nl/l to 60 ml/l [v/v]). Methane delta13C compositions ranged from -110‰ to +25‰ vs VPDB, narrowly clustering around -70‰ at high concentrations but being increasingly more variable at lower concentrations (-40‰ to -80‰)). Most of the data are clearly indicative for methanogenic processes, samples unusually enriched in delta13C can best be explained by secondary methane oxidation. Although some general regional trend can be observed, results are highly variable within short lateral distances or within different aquifers/filter depths. Frequently ethane (27% of samples, median 50nl/l) and occasionally propane (8%, median 23nl/l) has been detected. Lacking the carbon isotope composition of these homologues and thus solely based on the extremely low concentrations and atypical ethane/propane ratios, these have been tentatively interpreted as ubiquitous microbial background. From the original 2014 sample set around 100 wells have been selected for consecutive testing through 2015. In spring 2016 a total number of 1100 wells have been sampled, 700 of which had already been part of the initial study, providing us with the unique opportunity to assess long term variations. The overall comparison of these 700 samples revealed only small relative variations in methane concentrations (mostly ± 5‰ in 25% of samples). Minor variations could be related to uncertainties in laboratory analysis (± 10% in concentration, ± 0.5‰ delta13C). To which extent the

  13. Feasibility study for evaluating cumulative exposure of downstream migrant juvenile salmonids to total dissolved gas. Final report

    International Nuclear Information System (INIS)

    Abernethy, C.S.; Dauble, D.D.; Johnson, R.L.

    1997-11-01

    A feasibility study was initiated to determine if downstream migrant salmonids could be monitored to determine potential relationships between total dissolved gas (TDG) exposure and signs of gas bubble trauma (GBT). The primary objectives were to: (1) establish logistical requirements for in-river monitoring of TDG exposure, including net pen design, deployment, and navigation constraints; (2) resolve uncertainties associated with effects of the net pen on fish behavior; (3) test the accuracy and precision of in-river monitoring equipment used to measure fish distribution and water quality; and (4) determine the application of hydrologic/flow models to predictions of TDG exposure. In-river measurements included water velocity, boat position, and selected water quality parameters (temperature, dissolved oxygen, pH, depth, conductivity). Fish distribution within the net pen was monitored using scanning sonar, and a split-beam echo sounder was used to evaluate vertical distribution of fish m in the river adjacent to the net pen. Three test drifts were conducted from late July through late August. The studies demonstrated that it was feasible to assemble and deploy a large net pen for mobile monitoring of TDG exposure. Accurate monitoring of vertical and lateral distribution of smolts was performed, and diel differences in behavior were documented. Further, the fish sounded in response to researcher activity on the perimeter platform. Thus, in-transit monitoring for GBT or mortality would affect fish depth distribution and exposure to TDG. Principal recommendations for future studies are directed at improving maneuverability of the net pen in adverse weather conditions and applying new acoustics technology to simultaneously collect fish distribution data from within and outside of the pen. 6 refs., 17 figs., 2 tabs

  14. Modeling Fish Growth in Low Dissolved Oxygen

    Science.gov (United States)

    Neilan, Rachael Miller

    2013-01-01

    This article describes a computational project designed for undergraduate students as an introduction to mathematical modeling. Students use an ordinary differential equation to describe fish weight and assume the instantaneous growth rate depends on the concentration of dissolved oxygen. Published laboratory experiments suggest that continuous…

  15. Radiocarbon in marine dissolved organic carbon (DOC)

    NARCIS (Netherlands)

    Clercq, M. le; Plicht, J. van der; Meijer, H.A.J.; Baar, H.J.W. de

    Dissolved Organic Carbon (DOC) plays an important role in the ecology and carbon cycle in the ocean. Analytical problems with concentration and isotope ratio measurements have hindered its study. We have constructed a new analytical method based on supercritical oxidation for the determination of

  16. Occurrence and dominance of Cylindrospermopsis raciborskii and dissolved cylindrospermopsin in urban reservoirs used for drinking water supply, South China.

    Science.gov (United States)

    Lei, Lamei; Peng, Liang; Huang, Xianghui; Han, Bo-Ping

    2014-05-01

    The tropical cyanobacterium Cylindrospermopsis raciborskii is of particular concern for its invasive characteristics and production of the toxin cylindrospermopsin (CYN). The present study represents the first attempt to determine the distribution of C. raciborskii and CYN in tropical China. The presence of C. raciborskii and CYN, as well as the composition of phytoplankton, was determined from a total of 86 samples from 25 urban reservoirs for drinking water supply in Dongguan City of South China. The presence of C. raciborskii was observed in 21 of the 25 reservoirs and confirmed that this species has been widely distributed in the investigated reservoirs. C. raciborskii accounted for between 0.1 and 90.3 % of the total phytoplankton biomass and contributed to the majority of the phytoplankton in some reservoirs such as Tangkengbian and Xiagongyan. Its biomass was negatively correlated with NO3 (-)-N concentration and Secchi depth. Dissolved CYN was detected in more than one-half of the reservoirs with concentrations up to 8.25 μg L(-1), and it positively correlated with C. raciborskii biomass. Dissolved microcystins (MCs) were detected in 12 of the 25 reservoirs with a maximum concentration 1.99 μg L(-1). Our data strongly suggest that C. raciborskii and CYN could be important health hazards in urban reservoirs of South China and that more data are needed for further assessment.

  17. Study of the total uranium in underground water in the city of Jimenez, Chihuahua

    International Nuclear Information System (INIS)

    Renteria V, M.

    2004-01-01

    Samples of water of wells in the city of Jimenez, Chihuahua were analyzed, and its were determined the content of total uranium. It was used the technique of extraction of uranium from water adding Bis ( 2- ethylexyl) phosphate and scintillating Beta plate Hi safe, and the measures of the activities were carried out in the portable scintillation detector Thiathler- O Y HIDEX. The obtained interval of concentrations was 0.12 to 0.26 Bq/l that it is finds below the maximum permissible limits that it manages the Mexican regulation. It was found a significant correlation among the concentration of uranium and those total solid dissolved present in the samples. (Author)

  18. Diatom stratigraphy and long-term dissolved silica concentrations in the Baltic Sea

    Science.gov (United States)

    Olli, Kalle; Clarke, Annemarie; Danielsson, Åsa; Aigars, Juris; Conley, Daniel J.; Tamminen, Timo

    2008-10-01

    In many parts of the world coastal waters with anthropogenic eutrophication have experienced a gradual depletion of dissolved silica (DSi) stocks. This could put pressure on spring bloom diatom populations, e.g. by limiting the intensity of blooms or by causing shifts in species composition. In addition, eutrophication driven enhanced diatom growth is responsible for the redistribution of DSi from the water phase to the sediments, and changes in the growth conditions may be reflected in the sediment diatom stratigraphy. To test for changes in diatom communities we have analyzed four sediment cores from the Baltic Sea covering approximately the last 100 years. The sediment cores originate from the western Gulf of Finland, the Kattegat, the Baltic Proper and the Gulf of Riga. Three out of the four cores reveal only minor changes in composition of diatom assemblages, while the Gulf of Riga core contains major changes, occurring after the second World War. This area is set apart from the other Baltic Sea basins by a high frequency of low after spring bloom DSi concentrations (< 2 µmol L - 1 ) during a relatively well defined time period from 1991-1998. In 1991 to 1993 a rapid decline of DSi spring concentrations and winter stocks (down to 5 µmol L - 1 ) in the Gulf was preceded by exceptionally intense diatom spring blooms dominated by the heavily silicified species Thalassiosira baltica (1991-1992; up to 5.5 mg ww L - 1 ). T. baltica has been the principal spring bloom diatom in the Gulf of Riga since records began in 1975. DSi consumption and biomass yield experiments with cultured T. baltica suggest that intense blooms can potentially exhaust the DSi stock of the water column and exceed the annual Si dissolution in the Gulf of Riga. The phytoplankton time series reveals another exceptional T. baltica bloom period in 1981-1983 (up to 8 mg L - 1 ), which, however, took place before the regular DSi measurements. These periods may be reflected in the conspicuous

  19. The effect of microbial activity and adsorption processes on groundwater dissolved organic carbon character and concentration

    Science.gov (United States)

    Meredith, K.; McDonough, L.; Oudone, P.; Rutlidge, H.; O'Carroll, D. M.; Andersen, M. S.; Baker, A.

    2017-12-01

    Balancing the terrestrial global carbon budget has proven to be a significant challenge. Whilst the movement of carbon in the atmosphere, rivers and oceans has been extensively studied, the potential for groundwater to act as a carbon source or sink through both microbial activity and sorption to and from mineral surfaces, is poorly understood. To investigate the biodegradable component of groundwater dissolved organic carbon (DOC), groundwater samples were collected from multiple coastal and inland sites. Water quality parameters such as pH, electrical conductivity, temperature, dissolved oxygen were measured in the field. Samples were analysed and characterised for their biodegradable DOC content using spectrofluorometric and Liquid Chromatography-Organic Carbon Detection (LC-OCD) techniques at set intervals within a 28 day period. Further to this, we performed laboratory sorption experiments on our groundwater samples using different minerals to examine the effect of adsorption processes on DOC character and concentration. Calcium carbonate, quartz and iron coated quartz were heated to 400ºC to remove potential carbon contamination, and then added at various known masses (0 mg to 10 g) to 50 mL of groundwater. Samples were then rotated for two hours, filtered at 0.2 μm and analysed by LC-OCD. This research forms part of an ongoing project which will assist in identifying the factors affecting the mobilisation, transport and removal of DOC in uncontaminated groundwater. By quantifying the relative importance of these processes, we can then determine whether the groundwater is a carbon source or sink. Importantly, this information will help guide policy and identify the need to include groundwater resources as part of the carbon economy.

  20. Distributions of dissolved monosaccharides and polysaccharides in the surface microlayer and surface water of the Jiaozhou Bay and its adjacent area

    Science.gov (United States)

    Zhang, Yan-Ping; Yang, Gui-Peng; Lu, Xiao-Lan; Ding, Hai-Bing; Zhang, Hong-Hai

    2013-07-01

    Sea surface microlayer (SML) samples and corresponding bulk surface water (SW) samples were collected in the Jiaozhou Bay and its adjacent area in July and November 2008. The average concentrations of dissolved monosaccharides (MCHO) and polysaccharides (PCHO) revealed similar temporal variability, with higher concentrations during the green-tide period (in July) than during the non-green-tide period (in November). Average enrichment factors (EF) of MCHO and PCHO, defined as the ratio of the concentration in the SML to that in the SW, were 1.3 and 1.4 in July, respectively, while those values in November were 1.9 and 1.6. Our data also showed that the concentrations of MCHO and PCHO in the SML were strongly correlated with those in the SW, indicating that most of the organic materials in the SML came from the SW. The total dissolved carbohydrate concentrations (TDCHO) in the bulk surface water were closely correlated with salinity during the cruises (July: r=-0.580, n=18, P=0.01; November: r=-0.679, n=26, P<0.001), suggesting that riverine input had an important effect on the distribution of TDCHO in surface seawater of the study area.

  1. Laser Calorimetry Spectroscopy for ppm-level Dissolved Gas Detection and Analysis.

    Science.gov (United States)

    K S, Nagapriya; Sinha, Shashank; R, Prashanth; Poonacha, Samhitha; Chaudhry, Gunaranjan; Bhattacharya, Anandaroop; Choudhury, Niloy; Mahalik, Saroj; Maity, Sandip

    2017-02-20

    In this paper we report a newly developed technique - laser calorimetry spectroscopy (LCS), which is a combination of laser absorption spectroscopy and calorimetry - for the detection of gases dissolved in liquids. The technique involves determination of concentration of a dissolved gas by irradiating the liquid with light of a wavelength where the gas absorbs, and measuring the temperature change caused by the absorbance. Conventionally, detection of dissolved gases with sufficient sensitivity and specificity was done by first extracting the gases from the liquid and then analyzing the gases using techniques such as gas chromatography. Using LCS, we have been able to detect ppm levels of dissolved gases without extracting them from the liquid. In this paper, we show the detection of dissolved acetylene in transformer oil in the mid infrared (MIR) wavelength (3021 nm) region.

  2. The Potential Applications of Real-Time Monitoring of Water Quality in a Large Shallow Lake (Lake Taihu, China) Using a Chromophoric Dissolved Organic Matter Fluorescence Sensor

    Science.gov (United States)

    Niu, Cheng; Zhang, Yunlin; Zhou, Yongqiang; Shi, Kun; Liu, Xiaohan; Qin, Boqiang

    2014-01-01

    This study presents results from field surveys performed over various seasons in a large, eutrophic, shallow lake (Lake Taihu, China) using an in situ chromophoric dissolved organic matter (CDOM) fluorescence sensor as a surrogate for other water quality parameters. These measurements identified highly significant empirical relationships between CDOM concentration measured using the in situ fluorescence sensor and CDOM absorption, fluorescence, dissolved organic carbon (DOC), chemical oxygen demand (COD) and total phosphorus (TP) concentrations. CDOM concentration expressed in quinine sulfate equivalent units, was highly correlated with the CDOM absorption coefficient (r2 = 0.80, p CDOM concentration measured using the in situ fluorescence sensor could act as a substitute for the CDOM absorption coefficient and fluorescence measured in the laboratory. Similarly, CDOM concentration was highly correlated with DOC concentration (r2 = 0.68, p CDOM fluorescence sensor measurements could be a proxy for DOC concentration. In addition, significant positive correlations were found between laboratory CDOM absorption coefficients and COD (r2 = 0.83, p CDOM fluorescence sensor. PMID:24984060

  3. Radon concentrations in ground and drinking water in the state of Chihuahua, Mexico

    International Nuclear Information System (INIS)

    Villalba, L.; Colmenero Sujo, L.; Montero Cabrera, M.E.; Cano Jimenez, A.; Renteria Villalobos, M.; Delgado Mendoza, C.J.; Jurado Tenorio, L.A.; Davila Rangel, I.; Herrera Peraza, E.F.

    2005-01-01

    This paper reports 222 Rn concentrations in ground and drinking water of nine cities of Chihuahua State, Mexico. Fifty percent of the 114 sampled wells exhibited 222 Rn concentrations exceeding 11 Bq/L, the maximum contaminant level (MCL) recommended by the USEPA. Furthermore, around 48% (123 samples) of the tap-water samples taken from 255 dwellings showed radon concentrations over the MCL. There is an apparent correlation between total dissolved solids and radon concentration in ground-water. The high levels of 222 Rn found may be entirely attributed to the nature of aquifer rocks

  4. Radon concentrations in ground and drinking water in the state of Chihuahua, Mexico.

    Science.gov (United States)

    Villalba, L; Colmenero Sujo, L; Montero Cabrera, M E; Cano Jiménez, A; Rentería Villalobos, M; Delgado Mendoza, C J; Jurado Tenorio, L A; Dávila Rangel, I; Herrera Peraza, E F

    2005-01-01

    This paper reports (222)Rn concentrations in ground and drinking water of nine cities of Chihuahua State, Mexico. Fifty percent of the 114 sampled wells exhibited (222)Rn concentrations exceeding 11Bq/L, the maximum contaminant level (MCL) recommended by the USEPA. Furthermore, around 48% (123 samples) of the tap-water samples taken from 255 dwellings showed radon concentrations over the MCL. There is an apparent correlation between total dissolved solids and radon concentration in ground-water. The high levels of (222)Rn found may be entirely attributed to the nature of aquifer rocks.

  5. Effects of wind farm construction on concentrations and fluxes of dissolved organic carbon and suspended sediment from peat catchments at Braes of Doune, central Scotland

    Directory of Open Access Journals (Sweden)

    I. Grieve

    2008-07-01

    Full Text Available This paper assesses the impacts of disturbance associated with the construction of a wind farm on fluxes of dissolved organic carbon (DOC and suspended sediment from a blanket peat catchment in central Scotland during the period immediately following completion of construction. Six streams draining the site were sampled on six dates from October 2006, when construction was completed, and an additional three control streams to the west of the site were sampled on the same dates. Turbidity and stage were recorded semi-continuously in the two largest streams (one disturbed and one control, which were also sampled during storm events. Absorbance (400 nm and DOC concentrations were determined on all samples, and suspended sediment was determined on the event samples. Absorbance and DOC were closely correlated in both the disturbed and undisturbed streams, with slightly greater absorbance per unit DOC in the disturbed streams. DOC concentrations in disturbed tributaries were always greater than those in undisturbed streams, with mean differences ranging from 2 to around 5 mg L-1. DOC and stage were positively correlated during events with maximum concentrations in excess of 30 mg L 1 at peak flow. Suspended sediment concentrations were markedly elevated in the disturbed stream with maximum concentrations at peak flow some 4–5 times greater than in the control. The colour of the sediment suggested that it was highly organic in nature at peak flow, and suspended particulate organic carbon represented a further loss of C from the site. Using flow-weighted mean DOC concentrations calculated for the storms monitored in autumn 2007, dissolved carbon losses can be estimated for the catchments of the disturbed and control streams. From these data the additional DOC loss related to disturbance associated with the wind farm is estimated at 5 g m-2.

  6. Water, Rather than Temperature, Dominantly Impacts How Soil Fauna Affect Dissolved Carbon and Nitrogen Release from Fresh Litter during Early Litter Decomposition

    Directory of Open Access Journals (Sweden)

    Shu Liao

    2016-10-01

    Full Text Available Longstanding observations suggest that dissolved materials are lost from fresh litter through leaching, but the role of soil fauna in controlling this process has been poorly documented. In this study, a litterbag experiment employing litterbags with different mesh sizes (3 mm to permit soil fauna access and 0.04 mm to exclude fauna access was conducted in three habitats (arid valley, ecotone and subalpine forest with changes in climate and vegetation types to evaluate the effects of soil fauna on the concentrations of dissolved organic carbon (DOC and total dissolved nitrogen (TDN during the first year of decomposition. The results showed that the individual density and community abundance of soil fauna greatly varied among these habitats, but Prostigmata, Isotomidae and Oribatida were the dominant soil invertebrates. At the end of the experiment, the mass remaining of foliar litter ranged from 58% for shrub litter to 77% for birch litter, and the DOC and TDN concentrations decreased to 54%–85% and increased to 34%–269%, respectively, when soil fauna were not present. The effects of soil fauna on the concentrations of both DOC and TDN in foliar litter were greater in the subalpine forest (wetter but colder during the winter and in the arid valley (warmer but drier during the growing season, and this effect was positively correlated with water content. Moreover, the effects of fauna on DOC and TDN concentrations were greater for high-quality litter and were related to the C/N ratio. These results suggest that water, rather than temperature, dominates how fauna affect the release of dissolved substances from fresh litter.

  7. Spatial and Seasonal Variation of dissolved organic carbon (DOC) concentrations in Irish streams: importance of soil and topography characteristics.

    Science.gov (United States)

    Liu, Wen; Xu, Xianli; McGoff, Nicola M; Eaton, James M; Leahy, Paul; Foley, Nelius; Kiely, Gerard

    2014-05-01

    Dissolved organic carbon (DOC) concentrations have increased in many sites in Europe and North America in recent decades. High DOC concentrations can damage the structure and functions of aquatic ecosystems by influencing water chemistry. This study investigated the spatial and seasonal variation of DOC concentrations in Irish streams across 55 sites at seven time occasions over 1 year (2006/2007). The DOC concentrations ranged from 0.9 to 25.9 mg/L with a mean value of 6.8 and a median value of 5.7 mg/L and varied significantly over the course of the year. The DOC concentrations from late winter (February: 5.2 ± 3.0 mg/L across 55 sites) and early spring (April: 4.5 ± 3.5 mg/L) had significantly lower DOC concentrations than autumn (October: mean 8.3 ± 5.6 mg/L) and early winter (December: 8.3 ± 5.1 mg/L). The DOC production sources (e.g., litterfall) or the accumulation of DOC over dry periods might be the driving factor of seasonal change in Irish stream DOC concentrations. Analysis of data using stepwise multiple linear regression techniques identified the topographic index (TI, an indication of saturation-excess runoff potential) and soil conditions (organic carbon content and soil drainage characteristics) as key factors in controlling DOC spatial variation in different seasons. The TI and soil carbon content (e.g., soil organic carbon; peat occurrence) are positively related to DOC concentrations, while well-drained soils are negatively related to DOC concentrations. The knowledge of spatial and seasonal variation of DOC concentrations in streams and their drivers are essential for optimum riverine water resources management.

  8. DGT measurement of dissolved aluminum species in waters

    DEFF Research Database (Denmark)

    Panther, Jared G.; Bennett, William W.; Teasdale, Peter R.

    2012-01-01

    Aluminum is acutely toxic, and elevated concentrations of dissolved Al can have detrimental effects on both terrestrial and aquatic ecosystems. Robust analytical methods that can determine environmentally relevant Al fractions accurately and efficiently are required by the environmental monitoring...

  9. Concentrations and distributions of metals associated with dissolved organic matter from the Suwannee River (GA, USA)

    Science.gov (United States)

    Kuhn, M. Keshia; Neubauer, Elisabeth; Hofmann, Thilo; von der Kammer, Frank; Aiken, George R.; Maurice, Patricia A.

    2015-01-01

    Concentrations and distributions of metals in Suwannee River (SR) raw filtered surface water (RFSW) and dissolved organic matter (DOM) processed by reverse osmosis (RO), XAD-8 resin (for humic and fulvic acids [FA]), and XAD-4 resin (for “transphilic” acids) were analyzed by asymmetrical flow field-flow fractionation (AsFlFFF). SR samples were compared with DOM samples from Nelson's Creek (NLC), a wetland-draining stream in northern Michigan; previous International Humic Substances Society (IHSS) FA and RO samples from the SR; and an XAD-8 sample from Lake Fryxell (LF), Antarctica. Despite application of cation exchange during sample processing, all XAD and RO samples contained substantial metal concentrations. AsFlFFF fractograms allowed metal distributions to be characterized as a function of DOM component molecular weight (MW). In SR RFSW, Fe, Al, and Cu were primarily associated with intermediate to higher than average MW DOM components. SR RO, XAD-8, and XAD-4 samples from May 2012 showed similar MW trends for Fe and Al but Cu tended to associate more with lower MW DOM. LF DOM had abundant Cu and Zn, perhaps due to amine groups that should be present due to its primarily algal origins. None of the fractograms showed obvious evidence for mineral nanoparticles, although some very small mineral nanoparticles might have been present at trace concentrations. This research suggests that AsFlFFF is important for understanding how metals are distributed in different DOM samples (including IHSS samples), which may be key to metal reactivity and bioavailability.

  10. Concentration factors of stable elements and radionuclides in Po river fish

    International Nuclear Information System (INIS)

    Achilli, M.; Ciceri, G.; Bozzani, A.; Guzzi, L.; Queirazza, G.

    1988-01-01

    The concentration factors (CF) of stable Co, Cs, Mn, Fe, Zn and Sr in different fish from six stretches in the middle course of the Po river (N. Italy) have been investigated. The space-time variation in water has been followed for 14 months. The investigation has been undertaken to study CF variations in the same fish species as a function of the physico-chemical form of the different elements in water (dissolved, dissolved and exchangeable fraction of the particulate, total). CF values of 103 Ru, 131 I and 134 - 137 Cs were also investigated for Cyprinus carpio reared, with artificial food, in two semi-natural environments

  11. Measurement of dissolved hydrogen and hydrogen gas transfer in a hydrogen-producing reactor

    Energy Technology Data Exchange (ETDEWEB)

    Shizas, I.; Bagley, D.M. [Toronto Univ., ON (Canada). Dept. of Civil Engineering

    2004-07-01

    This paper presents a simple method to measure dissolved hydrogen concentrations in the laboratory using standard equipment and a series of hydrogen gas transfer tests. The method was validated by measuring hydrogen gas transfer parameters for an anaerobic reactor system that was purged with 10 per cent carbon dioxide and 90 per cent nitrogen using a coarse bubble diffuser stone. Liquid samples from the reactor were injected into vials and hydrogen was allowed to partition between the liquid and gaseous phases. The concentration of dissolved hydrogen was determined by comparing the headspace injections onto a gas chromatograph and a standard curve. The detection limit was 1.0 x 10{sup -5} mol/L of dissolved hydrogen. The gas transfer rate for hydrogen in basal medium and anaerobic digester sludge was used to validate the method. Results were compared with gas transfer models. In addition to monitoring dissolved hydrogen in reactor systems, this method can help improve hydrogen production potential. 1 ref., 4 figs.

  12. Application of isotope dilution method for measuring bioavailability of organic contaminants sorbed to dissolved organic matter (DOM)

    Energy Technology Data Exchange (ETDEWEB)

    Delgado-Moreno, Laura, E-mail: laura.delgado@eez.csic.es; Wu, Laosheng; Gan, Jay

    2015-08-15

    Natural waters such as surface water and sediment porewater invariably contain dissolved organic matter (DOM). Association of strongly hydrophobic contaminants (HOCs) with DOM leads to decreased toxicity and bioavailability, but bioavailability of DOM-sorbed HOCs is difficult to measure. Current methods to estimate bioavailability of HOCs in water are based on only the freely dissolved concentration (C{sub free}). The ignorance of the exchangeable fraction of HOCs sorbed on DOM may result in an underestimation of the toxicity potential of HOCs to aquatic organisms. Here we explore the applicability of an isotope dilution method (IDM) to measuring the desorption fraction of DOM-sorbed pyrene and bifenthrin and determining their exchangeable pool (E) as an approximation of bioavailability. E values, expressed as percentage of the total concentration, ranged between 0.80 and 0.92% for pyrene and 0.74 and 0.85% for bifenthrin, depending primarily on the amount of chemical in the freely dissolved form. However, between 34 and 78% of the DOM-sorbed pyrene was exchangeable. This fraction ranged between 23% and 82% for bifenthrin. The ability of IDM to predict bioavailability was further shown from a significant relationship (r{sup 2} > 0.72, P < 0.0001) between E and bioaccumulation into Daphnia magna. Therefore, IDM may be used to improve the bioavailability measurement and risk assessment of HOCs in aquatic systems.

  13. Application of isotope dilution method for measuring bioavailability of organic contaminants sorbed to dissolved organic matter (DOM)

    International Nuclear Information System (INIS)

    Delgado-Moreno, Laura; Wu, Laosheng; Gan, Jay

    2015-01-01

    Natural waters such as surface water and sediment porewater invariably contain dissolved organic matter (DOM). Association of strongly hydrophobic contaminants (HOCs) with DOM leads to decreased toxicity and bioavailability, but bioavailability of DOM-sorbed HOCs is difficult to measure. Current methods to estimate bioavailability of HOCs in water are based on only the freely dissolved concentration (C free ). The ignorance of the exchangeable fraction of HOCs sorbed on DOM may result in an underestimation of the toxicity potential of HOCs to aquatic organisms. Here we explore the applicability of an isotope dilution method (IDM) to measuring the desorption fraction of DOM-sorbed pyrene and bifenthrin and determining their exchangeable pool (E) as an approximation of bioavailability. E values, expressed as percentage of the total concentration, ranged between 0.80 and 0.92% for pyrene and 0.74 and 0.85% for bifenthrin, depending primarily on the amount of chemical in the freely dissolved form. However, between 34 and 78% of the DOM-sorbed pyrene was exchangeable. This fraction ranged between 23% and 82% for bifenthrin. The ability of IDM to predict bioavailability was further shown from a significant relationship (r 2 > 0.72, P < 0.0001) between E and bioaccumulation into Daphnia magna. Therefore, IDM may be used to improve the bioavailability measurement and risk assessment of HOCs in aquatic systems

  14. Concentrations, loads, and yields of nutrients and suspended sediment in the South Pacolet, North Pacolet, and Pacolet Rivers, northern South Carolina and southwestern North Carolina, October 2005 to September 2009

    Science.gov (United States)

    Journey, Celeste A.; Caldwell, Andral W.; Feaster, Toby D.; Petkewich, Mattew D.; Bradley, Paul M.

    2011-01-01

    The U.S. Geological Survey, in cooperation with Spartanburg Water, evaluated the concentrations, loads, and yields of suspended sediment, dissolved ammonia, dissolved nitrate plus nitrite, total organic nitrogen, total nitrogen, dissolved orthophosphate, dissolved phosphorus, and total phosphorus at sites in the South Pacolet, North Pacolet, and Pacolet Rivers in northern South Carolina and southwestern North Carolina from October 1, 2005, to September 30, 2009 (water years 2006 to 2009). Nutrient and sediment loads and yields also were computed for the intervening subbasin of the Pacolet River not represented by the South and North Pacolet River Basins. Except for a few outliers, the majority of the measurements of total nitrogen concentrations were well below the U.S. Environmental Protection Agency recommended guideline of 0.69 milligram per liter for streams and rivers in the nutrient ecoregion IX, which includes the study area within the Pacolet River Basin. Dissolved orthophosphate, dissolved phosphorus, and total phosphorus concentrations were significantly lower at the South Pacolet River site compared to the North Pacolet and Pacolet River sites. About 90 percent of the total phosphorus concentrations at the South Pacolet River site were below the U.S. Environmental Protection Agency recommended guideline of 0.37 milligram per liter, and more than 75 percent of the total phosphorus concentrations at the North Pacolet and Pacolet River sites were above that guideline. At all sites, minimum annual nutrient loads for the estimation period were observed during water year 2008 when severe drought conditions were present. An estimated mean annual total nitrogen load of 37,770 kilograms per year and yield of 2.63 kilograms per hectare per year were determined for the South Pacolet River site for the estimation period. The North Pacolet River site had a mean annual total nitrogen load of 65,890 kilograms per year and yield of 2.19 kilograms per hectare per year

  15. Effect of photodegradation and biodegradation on the concentration and composition of dissolved organic matter in diverse waterbodies

    Science.gov (United States)

    Manalilkada Sasidharan, S.; Dash, P.; Singh, S.; Lu, Y.

    2017-12-01

    The objective of this research was to quantify the effects of photodegradation and biodegradation on the dissolved organic matter (DOM) concentration and composition in five distinct waterbodies with diverse types of watershed land use and land cover in the southeastern United States. The water bodies included an agricultural pond, a lake in a predominantly forested watershed, a man-made reservoir, an estuary, and a bay. Two sets of samples were prepared from these water bodies by dispensing filtered water samples to unfiltered samples in 10:1 ratio. The first set was kept in the sunlight during the day (12 hours), and colored dissolved organic matter (CDOM) absorption and fluorescence were measured periodically over a 30-day period for examining the effects of combined photo- and biodegradation. The second set of samples was kept in the dark for examining the effects of biodegradation alone, and CDOM absorption and fluorescence were measured at the same time as the sunlight-exposed samples. Subsequently, spectrometric results in tandem with multivariate statistical analysis were used to interpret the lability vs. composition of DOM. Parallel factor analysis (PARAFAC) revealed the presence of four DOM components (C1-C4). C1 and C4 were microbial tryptophan-like, labile lighter components, while C2 and C3 were terrestrial humic like or fulvic acid type, larger aromatic refractory components. The principal component analysis (PCA) also revealed two distinct groups of DOM - C1 and C4 vs. C2 and C3. The negative PC1 loadings of C2, C3, HIX, a254 and SUVA indicated humic-like or fulvic-like structurally complex refractory aromatic DOM originated from higher plants in forested areas. C1, C4, SR, FI and BI had positive PC1 loadings, which indicated structurally simpler labile DOM were derived from agricultural areas or microbial activity. There was a decrease in dissolved organic carbon (DOC) due to combined photo- and biodegradation, and transformation of components C2

  16. Determination of serum free thyroxine concentration (FT4) by means of fT4-fraction and total thyroxine concentration

    International Nuclear Information System (INIS)

    Passath, A.; Leb, G.

    1985-01-01

    A new equilibrium assay for the determination of serum free thyroxine was evaluated in 514 patients. The assay comprises a two-vial-procedure to measure total thyroxine and free thyroxine fraction by use of monoclonal antibodies. Free thyroxine concentrations are calculated from fT 4 -fraction and total thyroxine concentration readings. In euthyroidism the average free thyroxine fraction (%fT 4 ) was 0.011%, in hyperthyroidism this fraction was elevated, in hypothyroidism it was below normal. In patients with TBG anomalies, TBG values were inversely correlated with fT 4 fraction readings. The 'euthyroid reference range' of FT 4 (SPAC ET) was between 0.70 to 1.78ng/dl. This euthyroid range of FT 4 was determined from TT 4 concentrations measured by T 4 -RIA (SPAC T 4 MONO) which were 30% above TT 4 values measured by conventional T 4 -RIA (SPAC T 4 POLY; polyclonal antibodies). However, a different euthyroid range of FT 4 between 0.55 to 1.30 ng/dl was observed as well as by other investigators when conventional T 4 -RIA measurements were used for calculation of FT 4 values. Our results indicate that calculated FT 4 concentration values are highly dependent on the methods used for determination of total thyroxine concentrations. Precision and reproducability of this two vial equilibrium assay did not meet the requirements mandatory for the application as a clinical routine diagnostic procedure, and its general use for this purpose can as yet not be recommended. (Author)

  17. Coulometric determination of dissolved hydrogen with a multielectrolytic modified carbon felt electrode-based sensor.

    Science.gov (United States)

    Matsuura, Hiroaki; Yamawaki, Yosuke; Sasaki, Kosuke; Uchiyama, Shunichi

    2013-06-01

    A multielectrolytic modified carbon electrode (MEMCE) was fabricated by the electrolytic-oxidation/reduction processes. First, the functional groups containing nitrogen atoms such as amino group were introduced by the electrode oxidation of carbon felt electrode in an ammonium carbamate aqueous solution, and next, this electrode was electroreduced in sulfuric acid. The redox waves between hydrogen ion and hydrogen molecule at highly positive potential range appeared in the cyclic voltammogram obtained by MEMCE. A coulometric cell using MEMCE with a catalytic activity of electrooxidation of hydrogen molecule was constructed and was used for the measurement of dissolved hydrogen. The typical current vs. time curve was obtained by the repetitive measurement of the dissolved hydrogen. These curves indicated that the measurement of dissolved hydrogen was finished completely in a very short time (ca. 10 sec). A linear relationship was obtained between the electrical charge needed for the electrooxidation process of hydrogen molecule and dissolved hydrogen concentration. This indicates that the developed coulometric method can be used for the determination of the dissolved hydrogen concentration.

  18. Fast-freezing with liquid nitrogen preserves bulk dissolved organic matter concentrations, but not its composition

    DEFF Research Database (Denmark)

    Thieme, Lisa; Graeber, Daniel; Kaupenjohann, Martin

    2016-01-01

    -freezing with liquid nitrogen) on DOM concentrations measured as organic carbon (DOC) concentrations and on spectroscopic properties of DOM from different terrestrial ecosystems (forest and grassland). Fresh and differently frozen throughfall, stemflow, litter leachate and soil solution samples were analyzed for DOC...... concentrations, UV-vis absorption and fluorescence excitation–emission matrices combined with parallel factor analysis (PARAFAC). Fast-freezing with liquid nitrogen prevented a significant decrease of DOC concentrations observed after freezing at −18 °C. Nonetheless, the share of PARAFAC components 1 (EXmax...... component 4 (EXmax: 280 nm, EXmax: 328 nm) to total fluorescence was not affected by freezing. We recommend fast-freezing with liquid nitrogen for preservation of bulk DOC concentrations of samples from terrestrial sources, whereas immediate measuring is preferable to preserve spectroscopic properties...

  19. Performance of Electrocoagulation Process in the Removal of Total Coliform and Hetrotrophic Bacteria from Surface Water

    Directory of Open Access Journals (Sweden)

    Jamshid Derayat

    2015-03-01

    Full Text Available Electrocoagulation is an electrochemical method for the treatment of water and wastewater. The present cross-sectional study was designed to investigate the removal efficiency of total coliform and heterotrophic bacteria from surface water using the process. For this purpose, water samples were taken from the drinking water intake at Suleiman-Shahsonghur Dam. The electrocoagulation process was carried out in a Plexiglas reactor in the batch mode with Al and Fe used electrodes. The experiment design was carried out using the Design Expert Software (Stat-Ease Inc., Ver. 6.0.6. After each run, the values of metals dissolved due to anode electrode dissolution were measured using the Inductively Coupled Plasma (ICP and the results were analyzed using the RSM model. Results revealed maximum removal efficiencies of 100% and 89.1% for total coliform and heterotrophic bacteria using the Al electrode, respectively. Also, maximum removal efficiencies using the Fe electrode for the same pollutants were 100% and 76.1%. The measurements clearly indicate that the quantities of Al and Fe released in water were higher than the recommended values. While the electrocoagulation process showed to be effective in removing microbial agents from surface waters, the high concentrations of dissolved metals due to the dissolution of the anode electrode seem to remain a health problem that requires optimal conditions to be determined for acheiving standard concentrations of the dissolved metals.

  20. Dissolved pesticides, dissolved organic carbon, and water-quality characteristics in selected Idaho streams, April--December 2010

    Science.gov (United States)

    Reilly, Timothy J.; Smalling, Kelly L.; Wilson, Emma R.; Battaglin, William A.

    2012-01-01

    Water-quality samples were collected from April through December 2010 from four streams in Idaho and analyzed for a suite of pesticides, including fungicides, by the U.S. Geological Survey. Water samples were collected from two agricultural and two nonagricultural (control) streams approximately biweekly from the beginning of the growing season (April) through the end of the calendar year (December). Samples were analyzed for 90 pesticides using gas chromatography/mass spectrometry. Twenty-three pesticides, including 8 fungicides, 10 herbicides, 3 insecticides, and 2 pesticide degradates, were detected in 45 water samples. The most frequently detected compounds in the two agricultural streams and their detection frequencies were metolachlor, 96 percent; azoxystrobin, 79 percent; boscalid, 79 percent; atrazine, 46 percent; pendimethalin, 33 percent; and trifluralin, 33 percent. Dissolved-pesticide concentrations ranged from below instrumental limits of detection (0.5-1.0 nanograms per liter) to 771 nanograms per liter (hexazinone). The total number of pesticides detected in any given water sample ranged from 0 to 11. Only three pesticides (atrazine, fipronil, and simazine) were detected in samples from the control streams during the sampling period.

  1. Total mercury concentrations in lionfish (Pterois volitans/miles) from the Florida Keys National Marine Sanctuary, USA.

    Science.gov (United States)

    Huge, Dane H; Schofield, Pamela J; Jacoby, Charles A; Frazer, Thomas K

    2014-01-15

    Strategies to control invasive lionfish in the western Atlantic and Caribbean are likely to include harvest and consumption. Until this report, total mercury concentrations had been documented only for lionfish from Jamaica, and changes in concentrations with increasing fish size had not been evaluated. In the Florida Keys, total mercury concentrations in dorsal muscle tissue from 107 lionfish ranged from 0.03 to 0.48 ppm, with all concentrations being less than the regulatory threshold for limited consumption. Mercury concentrations did not vary consistently with standard lengths or wet weights of lionfish. In 2010, lionfish from the upper Keys had mean concentrations that were 0.03-0.04 ppm higher than lionfish from the middle Keys, but mean concentrations did not differ consistently among years and locations. Overall, total mercury concentrations in lionfish were lower than those in several predatory fishes that support commercial and recreational fisheries in Florida. Published by Elsevier Ltd.

  2. A new device for continuous monitoring the CO2 dissolved in water

    Science.gov (United States)

    de Gregorio, S.; Camarda, M.; Cappuzzo, S.; Giudice, G.; Gurrieri, S.; Longo, M.

    2009-04-01

    The measurements of dissolved CO2 in water are common elements of industrial processes and scientific research. In order to perform gas dissolved measurements is required to separate the dissolved gaseous phase from water. We developed a new device able to separate the gases phase directly in situ and well suitable for continuous measuring the CO2 dissolved in water. The device is made by a probe of a polytetrafluorethylene (PTFE) tube connected to an I.R. spectrophotometer (I.R.) and a pump. The PTFE is a polymeric semi-permeable membrane and allows the permeation of gas in the system. Hence, this part of the device is dipped in water in order to equilibrate the probe headspace with the dissolved gases. The partial pressure of the gas i in the headspace at equilibrium (Pi) follows the Henry's law: Pi=Hi•Ci, where Hi is the Henry's constant and Ci is the dissolved concentration of gas i. After the equilibrium is achieved, the partial pressure of CO2 inside the tube is equal to the partial pressure of dissolved CO2. The concentration of CO2 is measured by the I.R. connected to the tube. The gas is moved from the tube headspace to the I.R. by using the pump. In order to test the device and assess the best operating condition, several experimental were performed in laboratory. All the test were executed in a special apparatus where was feasible to create controlled atmospheres. Afterward the device has been placed in a draining tunnel sited in the Mt. Etna Volcano edifice (Italy). The monitored groundwater intercepts the Pernicana Fault, along which degassing phenomena are often observed. The values recorded by the station result in agreement with monthly directly measurements of dissolved CO2 partial pressure.

  3. Water resources and effects of potential surface coal mining on dissolved solids in Hanging Woman Creek basin, southeastern Montana

    Science.gov (United States)

    Cannon, M.R.

    1989-01-01

    Groundwater resources of the Hanging Woman Creek basin, Montana include Holocene and Pleistocene alluvial aquifers and sandstone , coal, and clinker aquifers in the Paleocene Fort Union Formation. Surface water resources are composed of Hanging Woman Creek, its tributaries, and small stock ponds. Dissolved-solids concentrations in groundwater ranged from 200 to 11,00 mg/L. Generally, concentrations were largest in alluvial aquifers and smallest in clinker aquifers. Near its mouth, Hanging Woman Creek had a median concentration of about 1,800 mg/L. Mining of the 20-foot to 35-foot-thick Anderson coal bed and 3-foot to 16-foot thick Dietz coal bed could increase dissolved-solids concentrations in shallow aquifers and in Hanging Woman Creek because of leaching of soluble minerals from mine spoils. Analysis of saturated-paste extracts from 158 overburden samples indicated that water moving through mine spoils would have a median increase in dissolved-solids concentration of about 3,700 mg/L, resulting in an additional dissolved-solids load to Hanging Woman Creek of about 3.0 tons/day. Hanging Woman Creek near Birney could have an annual post-mining dissolved-solids load of 3,415 tons at median discharge, a 47% increase from pre-mining conditions load. Post-mining concentrations of dissolved solids, at median discharge, could range from 2,380 mg/L in March to 3,940 mg/L in August, compared to mean pre-mining concentrations that ranged from 1,700 mg/L in July, November, and December to 2,060 mg/L in May. Post-mining concentrations and loads in Hanging Woman Creek would be smaller if a smaller area were mined. (USGS)

  4. Mean total arsenic concentrations in chicken 1989-2000 and estimated exposures for consumers of chicken.

    OpenAIRE

    Lasky, Tamar; Sun, Wenyu; Kadry, Abdel; Hoffman, Michael K

    2004-01-01

    The purpose of this study was to estimate mean concentrations of total arsenic in chicken liver tissue and then estimate total and inorganic arsenic ingested by humans through chicken consumption. We used national monitoring data from the Food Safety and Inspection Service National Residue Program to estimate mean arsenic concentrations for 1994-2000. Incorporating assumptions about the concentrations of arsenic in liver and muscle tissues as well as the proportions of inorganic and organic a...

  5. The effect of the oxygen dissolved in the adsorption of gold in activated carbon

    International Nuclear Information System (INIS)

    Navarro, P.; Wilkomirsky, I.

    1999-01-01

    The effect of the oxygen dissolved on the adsorption of gold in a activated carbon such as these used for carbon in pulp (CIP) and carbon in leach (CIL) processes were studied. The research was oriented to dilucidate the effect of the oxygen dissolved in the gold solution on the kinetics and distribution of the gold adsorbed in the carbon under different conditions of ionic strength, pH and gold concentration. It was found that the level of the oxygen dissolved influences directly the amount of gold adsorbed on the activated carbon, being this effect more relevant for low ionic strength solutions. The pH and initial gold concentration has no effect on this behavior. (Author) 16 refs

  6. Dissolved nitrogen in drinking water resources of farming ...

    African Journals Online (AJOL)

    Dissolved nitrogen in drinking water resources of farming communities in Ghana. ... African Journal of Environmental Science and Technology ... Concentrations of these potentially toxic substances were below WHO acceptable limits for surface and groundwaters, indicating these water resources appear safe for drinking ...

  7. Seasonal and interannual variability of dissolved oxygen around the Balearic Islands from hydrographic data

    Science.gov (United States)

    Balbín, R.; López-Jurado, J. L.; Aparicio-González, A.; Serra, M.

    2014-10-01

    Oceanographic data obtained between 2001 and 2011 by the Spanish Institute of Oceanography (IEO, Spain) have been used to characterise the spatial distribution and the temporal variability of the dissolved oxygen around the Balearic Islands (Mediterranean Sea). The study area includes most of the Western Mediterranean Sea, from the Alboran Sea to Cape Creus, at the border between France and Spain. Dissolved oxygen (DO) at the water surface is found to be in a state of equilibrium exchange with the atmosphere. In the spring and summer a subsurface oxygen supersaturation is observed due to the biological activity, above the subsurface fluorescence maximum. Minimum observed values of dissolved oxygen are related to the Levantine Intermediate Waters (LIW). An unusual minimum of dissolved oxygen concentrations was also recorded in the Alboran Sea Oxygen Minimum Zone. The Western Mediterranean Deep Waters (WMDW) and the Western Intermediate Waters (WIW) show higher values of dissolved oxygen than the Levantine Intermediate Waters due to their more recent formation. Using these dissolved oxygen concentrations it is possible to show that the Western Intermediate Waters move southwards across the Ibiza Channel and the deep water circulates around the Balearic Islands. It has also been possible to characterise the seasonal evolution of the different water masses and their dissolved oxygen content in a station in the Algerian sub-basin.

  8. Measurement of thyroid volume, iodine concentration and total iodine content by CT and its clinical significance

    International Nuclear Information System (INIS)

    Nakaji, Shunsuke; Imanishi, Yoshimasa; Okamoto, Kyouko; Shinagawa, Toshihito

    2007-01-01

    Recently, Imanishi et al have developed new CT software for quantitative in vivo measurement of thyroid iodine. Using a CT system with the software, we measured volume, iodine concentration and total iodine content of thyroids in 63 controls and 435 patients with various diffuse thyroid diseases and thyroid nodules. In controls, all of them showed no difference between the sexes. Although the iodine concentration of the thyroid showed no difference among children, adults and seniles, the volume and total iodine content of the thyroid appeared smaller in children and seniles than in adults. In addition, although the volume and iodine concentration of the thyroid had two peaks in distribution, the total iodine content had almost normal distribution. Normal range of volume, iodine concentration and total iodine content in adults were 5.2-15.5 cm 3 , 0.28831-0.85919 mg/cm 3 and 2.35-11.69 mg, respectively. In thyroid nodule, there is no significant difference in volume, iodine concentration and total iodine content between benign and malignant nodules. All nodules with iodine concentration of less than 0.00007 mg/cm 3 were benign. No thyroid was higher in iodine concentration than the normal range although the thyroid was lower in 78.7% of patients with diffuse thyroid diseases. In all thyroids with increasing iodine concentration and total iodine content in medication course, thyroidal symptoms and signs were uncontrollable by the medication. In 43.8% of patients with long-period systemic diseases, the thyroid showed abnormality in any of the three. We concluded that quantitative in vivo measurement of thyroid iodine by CT could assist the diagnosis of thyroid diseases and decision of therapeutic methods. (author)

  9. Concentrations of 23 trace elements in ground water and surface water at and near the Idaho National Engineering Laboratory, Idaho, 1988--91

    International Nuclear Information System (INIS)

    Liszewski, M.J.; Mann, L.J.

    1993-01-01

    Analytical data for 23 trace elements are reported for ground- and surface-water samples collected at and near the Idaho National Engineering Laboratory during 1988--91. Water samples were collected from 148 wells completed in the Snake River Plain aquifer, 18 wells completed in discontinuous deep perched-water zones, and 1 well completed in an alluvial aquifer. Surface-water samples also were collected from three streams, two springs, two ponds, and one lake. Data are categorized by concentrations of total recoverable of dissolved trace elements. Concentrations of total recoverable trace elements are reported for unfiltered water samples and include results for one or more of the following: aluminum, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, selenium, silver, and zinc. Concentrations of dissolved trace elements are reported for water samples filtered through a nominal 0.45-micron filter and may also include bromide, fluoride, lithium, molybdenum, strontium, thallium, and vanadium. Concentrations of dissolved hexavalent chromium also are reported for many samples. The water samples were analyzed at the US Geological Survey's National Water Quality Laboratory in Arvada, Colorado. Methods used to collect the water samples and quality assurance instituted for the sampling program are described. Concentrations of chromium equaled or exceeded the maximum contaminant level at 12 ground-water quality monitoring wells. Other trace elements did not exceed their respective maximum contaminant levels

  10. Concentrations of 23 trace elements in ground water and surface water at and near the Idaho National Engineering Laboratory, Idaho, 1988--91

    Energy Technology Data Exchange (ETDEWEB)

    Liszewski, M.J.; Mann, L.J.

    1993-12-31

    Analytical data for 23 trace elements are reported for ground- and surface-water samples collected at and near the Idaho National Engineering Laboratory during 1988--91. Water samples were collected from 148 wells completed in the Snake River Plain aquifer, 18 wells completed in discontinuous deep perched-water zones, and 1 well completed in an alluvial aquifer. Surface-water samples also were collected from three streams, two springs, two ponds, and one lake. Data are categorized by concentrations of total recoverable of dissolved trace elements. Concentrations of total recoverable trace elements are reported for unfiltered water samples and include results for one or more of the following: aluminum, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, selenium, silver, and zinc. Concentrations of dissolved trace elements are reported for water samples filtered through a nominal 0.45-micron filter and may also include bromide, fluoride, lithium, molybdenum, strontium, thallium, and vanadium. Concentrations of dissolved hexavalent chromium also are reported for many samples. The water samples were analyzed at the US Geological Survey`s National Water Quality Laboratory in Arvada, Colorado. Methods used to collect the water samples and quality assurance instituted for the sampling program are described. Concentrations of chromium equaled or exceeded the maximum contaminant level at 12 ground-water quality monitoring wells. Other trace elements did not exceed their respective maximum contaminant levels.

  11. Salinity: Electrical conductivity and total dissolved solids

    Science.gov (United States)

    The measurement of soil salinity is a quantification of the total salts present in the liquid portion of the soil. Soil salinity is important in agriculture because salinity reduces crop yields by reducing the osmotic potential making it more difficult for the plant to extract water, by causing spe...

  12. Relationship between the colored dissolved organic matter and dissolved organic carbon and the application on remote sensing in East China Sea

    Science.gov (United States)

    Qiong, Liu; Pan, Delu; Huang, Haiqing; Lu, Jianxin; Zhu, Qiankun

    2011-11-01

    A cruise was conducted in the East China Sea (ECS) in autumn 2010 to collect Dissolved Organic Carbon (DOC) and Colored Dissolved Organic Matter (CDOM) samples. The distribution of DOC mainly controlled by the hydrography since the relationship between DOC and salinity was significant in both East China Sea. The biological activity had a significant influence on the concentration of DOC with a close correlation between DOC and Chl a. The absorption coefficient of CDOM (a355) decreased with the salinity increasing in the shelf of East China Sea (R2=0.9045). CDOM and DOC were significantly correlated in ECS where DOC distribution was dominated largely by the Changjiang diluted water. Based on the relationship of CDOM and DOC, we estimated the DOC concentration of the surface in ECS from satellite-derived CDOM images. Some deviations induced by the biological effect and related marine DOC accumulations were discussed.

  13. The role of hydrologic regimes on dissolved organic carbon composition in an agricultural watershed

    Science.gov (United States)

    Hernes, P.J.; Spencer, R.G.M.; Dyda, R.Y.; Pellerin, B.A.; Bachand, P.A.M.; Bergamaschi, B.A.

    2008-01-01

    Willow Slough, a seasonally irrigated agricultural watershed in the Sacramento River valley, California, was sampled weekly in 2006 in order to investigate seasonal concentrations and compositions of dissolved organic carbon (DOC). Average DOC concentrations nearly doubled from winter baseflow (2.75 mg L-1) to summer irrigation (5.14 mg L-1), while a concomitant increase in carbon-normalized vanillyl phenols (0.11 mg 100 mg OC-1 increasing to 0.31 mg 100 mg OC-1, on average) indicates that this additional carbon is likely vascular plant-derived. A strong linear relationship between lignin concentration and total suspended sediments (r2 = 0.79) demonstrates that agricultural management practices that mobilize sediments will likely have a direct and significant impact on DOC composition. The original source of vascular plant-derived DOC to Willow Slough appears to be the same throughout the year as evidenced by similar syringyl to vanillyl and cinnamyl to vanillyl ratios. However, differing diagenetic pathways during winter baseflow as compared to the rest of the year are evident in acid to aldehyde ratios of both vanillyl and syringyl phenols. The chromophoric dissolved organic matter (CDOM) absorption coefficient at 350 nm showed a strong correlation with lignin concentration (r2 = 0.83). Other CDOM measurements related to aromaticity and molecular weight also showed correlations with carbon-normalized yields (e.g. specific UV absorbance at 254 nm (r2 = 0.57) and spectral slope (r2 = 0.54)). Our overall findings suggest that irrigated agricultural watersheds like Willow Slough can potentially have a significant impact on mainstem DOC concentration and composition when scaled to the entire watershed of the main tributary. ?? 2008 Elsevier Ltd.

  14. The role of hydrologic regimes on dissolved organic carbon composition in an agricultural watershed

    Science.gov (United States)

    Hernes, Peter J.; Spencer, Robert G. M.; Dyda, Rachael Y.; Pellerin, Brian A.; Bachand, Philip A. M.; Bergamaschi, Brian A.

    2008-11-01

    Willow Slough, a seasonally irrigated agricultural watershed in the Sacramento River valley, California, was sampled weekly in 2006 in order to investigate seasonal concentrations and compositions of dissolved organic carbon (DOC). Average DOC concentrations nearly doubled from winter baseflow (2.75 mg L -1) to summer irrigation (5.14 mg L -1), while a concomitant increase in carbon-normalized vanillyl phenols (0.11 mg 100 mg OC -1 increasing to 0.31 mg 100 mg OC -1, on average) indicates that this additional carbon is likely vascular plant-derived. A strong linear relationship between lignin concentration and total suspended sediments ( r2 = 0.79) demonstrates that agricultural management practices that mobilize sediments will likely have a direct and significant impact on DOC composition. The original source of vascular plant-derived DOC to Willow Slough appears to be the same throughout the year as evidenced by similar syringyl to vanillyl and cinnamyl to vanillyl ratios. However, differing diagenetic pathways during winter baseflow as compared to the rest of the year are evident in acid to aldehyde ratios of both vanillyl and syringyl phenols. The chromophoric dissolved organic matter (CDOM) absorption coefficient at 350 nm showed a strong correlation with lignin concentration ( r2 = 0.83). Other CDOM measurements related to aromaticity and molecular weight also showed correlations with carbon-normalized yields (e.g. specific UV absorbance at 254 nm ( r2 = 0.57) and spectral slope ( r2 = 0.54)). Our overall findings suggest that irrigated agricultural watersheds like Willow Slough can potentially have a significant impact on mainstem DOC concentration and composition when scaled to the entire watershed of the main tributary.

  15. Photo-lability of deep ocean dissolved black carbon

    Directory of Open Access Journals (Sweden)

    A. Stubbins

    2012-05-01

    Full Text Available Dissolved black carbon (DBC, defined here as condensed aromatics isolated from seawater via PPL solid phase extraction and quantified as benzenepolycarboxylic acid (BPCA oxidation products, is a significant component of the oceanic dissolved organic carbon (DOC pool. These condensed aromatics are widely distributed in the open ocean and appear to be tens of thousands of years old. As such DBC is regarded as highly refractory. In the current study, the photo-lability of DBC, DOC and coloured dissolved organic matter (CDOM; ultraviolet-visible absorbance were determined over the course of a 28 day irradiation of North Atlantic Deep Water under a solar simulator. During the irradiation DBC fell from 1044 ± 164 nM-C to 55 ± 15 nM-C, a 20-fold decrease in concentration. Dissolved black carbon photo-degradation was more rapid and more extensive than for bulk CDOM and DOC. The concentration of DBC correlated with CDOM absorbance and the quality of DBC indicated by the ratios of different BPCAs correlated with CDOM absorbance spectral slope, suggesting the optical properties of CDOM may provide a proxy for both DBC concentrations and quality in natural waters. Further, the photo-lability of components of the DBC pool increased with their degree of aromatic condensation. These trends indicate that a continuum of compounds of varying photo-lability exists within the marine DOC pool. In this continuum, photo-lability scales with aromatic character, specifically the degree of condensation. Scaling the rapid photo-degradation of DBC to rates of DOC photo-mineralisation for the global ocean leads to an estimated photo-chemical half-life for oceanic DBC of less than 800 years. This is more than an order of magnitude shorter than the apparent age of DBC in the ocean. Consequently, photo-degradation is posited as the primary sink for oceanic DBC and the apparent survival of DBC molecules in the oceans for millennia appears to be facilitated not by their

  16. Fate of polychlorinated biphenyls in a contaminated lake ecosystem: combining equilibrium passive sampling of sediment and water with total concentration measurements of biota.

    Science.gov (United States)

    Mäenpää, Kimmo; Leppänen, Matti T; Figueiredo, Kaisa; Mayer, Philipp; Gilbert, Dorothea; Jahnke, Annika; Gil-Allué, Carmen; Akkanen, Jarkko; Nybom, Inna; Herve, Sirpa

    2015-11-01

    Equilibrium sampling devices can be applied to study and monitor the exposure and fate of hydrophobic organic chemicals on a thermodynamic basis. They can be used to determine freely dissolved concentrations and chemical activity ratios and to predict equilibrium partitioning concentrations of hydrophobic organic chemicals in biota lipids. The authors' aim was to assess the equilibrium status of polychlorinated biphenyls (PCBs) in a contaminated lake ecosystem and along its discharge course using equilibrium sampling devices for measurements in sediment and water and by also analyzing biota. The authors used equilibrium sampling devices (silicone rubber and polyethylene [PE]) to determine freely dissolved concentrations and chemical activities of PCBs in the water column and sediment porewater and calculated for both phases the corresponding equilibrium concentrations and chemical activities in model lipids. Overall, the studied ecosystem appeared to be in disequilibrium for the studied phases: sediment, water, and biota. Chemical activities of PCBs were higher in sediment than in water, which implies that the sediment functioned as a partitioning source of PCBs and that net diffusion occurred from the sediment to the water column. Measured lipid-normalized PCB concentrations in biota were generally below equilibrium lipid concentrations relative to the sediment (CLip ⇌Sed ) or water (CLip ⇌W ), indicating that PCB levels in the organisms were below the maximum partitioning levels. The present study shows the application versatility of equilibrium sampling devices in the field and facilitates a thermodynamic understanding of exposure and fate of PCBs in a contaminated lake and its discharge course. © 2015 SETAC.

  17. Loading Concentrations of Pollutant in Alur Ilmu at UKM Bangi Campus: Event Mean Concentration (EMC) Approach

    International Nuclear Information System (INIS)

    Haslinur Md Din; Mohd Ekhwan Toriman; Mazlin Mokhtar

    2012-01-01

    Water pollutant loadings and river discharge are among the basic data used in determining the dynamicity of a river. The input of water quality and river discharge are usually available through the collection of water samples in the field or at the observatory, and are done automatically using the data logger sensor. This paper discusses the concentrations pollutant load water quality and its relationship with discharge (m 3 / s) using Event Mean Concentration (EMC) in the Alur Ilmu, UKM source from the Diptrokarp forest at Hutan Simpan Bangi (2 degree 55' 1 4.72 N 101 degree 46' 5 7.37 E). Alur Ilmu is a 1.79 km long stretching across the main campus of National University of Malaysia before flowing into the Langat River. Water quality was measured using automatic gauging and continuous water quality stations which are installed at downstream of Alur Ilmu (2 degree 55 ' 40.33 N 100 degree 46 ' 47.15 E) and involves in measuring the parameters of total dissolved solid (TDS) and dissolved oxygen (DO). Laboratory analysis carried out for chemical parameters such as ammonia nitrogen (NH 3 -N), total suspended solid (TSS), biochemical oxygen demand (BOD) and chemical oxygen demand (COD) in accordance with guidelines American Public Health Association (APHA, 1995). The normal discharge rate recorded at Alur Ilmu is 0.33 m 3 / s and the wet discharge is 13.04 m 3 / s.The total estimated pollutant loadings according to EMC as DO (18.51±3.01 mg/ L), TDS (794.92±186.72 mg/ L), BOD (11.57±0.28 mg/ L), COD (201.29±1.55 mg/ l), TSS (470.03±27.63 mg/ L) and Ammonia Nitrogen (2.52±0.0 mg/ L). Correlation test showed a direct relationship between rainfall and flow (Q) and several pollutant loadings with R 2 =1 at a significance level of 0.05. The study also classified some of the pollutants concentrations in class III and IV as determined by the Water Quality Index (WQI). (author)

  18. Concentrations of stable elements and uranium in estuarine areas of Japan

    International Nuclear Information System (INIS)

    Takata, Hyoe; Aono, Tatsuo; Tagami, Keiko; Uchida, Shigeo

    2008-01-01

    The geochemistry of stable elements can be a good analogue for understanding the behavior of radionuclides in estuarine and coastal environments. In this study, the behavior of nutrients (NO 3 + NO 2 , PO 4 , Si(OH) 4 ), heavy metals, and U was observed in several estuarine and coastal waters of Japan. We also collected data on salinity, pH, and suspended particle matter (SPM). Nutrient concentrations followed conservative dilution lines in these estuaries, and concentrations of dissolved Fe decreased as salinity increased from 0 to 20. In general, most of the dissolved Fe in estuaries is in colloidal form. The behavior of dissolved Fe might reflect a loss of colloidal Fe through coagulation in this salinity range. Dissolved Co and Ni concentrations followed approximate dilution lines from the rivers to the seawater end-members, suggesting that they were quasi-conservative in these estuarine systems. A rapid increase in dissolved Cd concentrations was observed at low levels of salinity (<4). Estimated fluxes of dissolved Cd to the estuarine and coastal waters showed that the salt-induced desorption of Cd from particles constitutes a significant source of dissolved Cd in the estuarine and coastal waters. (author)

  19. Long-term atmospheric wet deposition of dissolved organic nitrogen in a typical red-soil agro-ecosystem, Southeastern China.

    Science.gov (United States)

    Cui, Jian; Zhou, Jing; Peng, Ying; He, Yuan Q; Yang, Hao; Xu, Liang J; Chan, Andy

    2014-05-01

    Dissolved organic nitrogen (DON) from atmospheric deposition has been a growing concern in the world and atmospheric nitrogen (N) deposition is increasing quickly in China especially Southeastern China. In our study, DON wet deposition was estimated by collecting and analyzing rainwater samples continuously over eight years (2005-2012) in a typical red-soil farmland ecosystem, Southeast China. Results showed that the volume-weighted-average DON concentration varied from 0.2 to 3.3 mg N L(-1) with an average of 1.2 mg N L(-1). DON flux ranged from 5.7 to 71.6 kg N ha(-1) year(-1) and averaged 19.7 kg N ha(-1) year(-1) which accounted for 34.6% of the total dissolved nitrogen (TDN) in wet deposition during the eight-year period. Analysis of DON concentration and flux, contribution of DON to TDN, rainfall, rain frequency, air temperature and wind frequency and the application of pig manure revealed possible pollution sources. Significant positive linear relation of annual DON flux and usage of pig manure (Pcycle in the red-soil agro-ecosystem in the future.

  20. Effects of Total Dissolved Gas on Chum Salmon Fry Incubating in the Lower Columbia River

    Energy Technology Data Exchange (ETDEWEB)

    Arntzen, Evan V.; Hand, Kristine D.; Geist, David R.; Murray, Katherine J.; Panther, Jenny; Cullinan, Valerie I.; Dawley, Earl M.; Elston, Ralph A.

    2008-01-30

    This report describes research conducted by Pacific Northwest National Laboratory in FY 2007 for the U.S. Army Corps of Engineers, Portland District, to characterize the effects of total dissolved gas (TDG) on the incubating fry of chum salmon (Onchorhynchus keta) in the lower Columbia River. The tasks conducted and results obtained in pursuit of three objectives are summarized: * to conduct a field monitoring program at the Ives Island and Multnomah Falls study sites, collecting empirical data on TDG to obtain a more thorough understanding of TDG levels during different river stage scenarios (i.e., high-water year versus low-water year) * to conduct laboratory toxicity tests on hatchery chum salmon fry at gas levels likely to occur downstream from Bonneville Dam * to sample chum salmon sac fry during Bonneville Dam spill operations to determine if there is a physiological response to TDG levels. Chapter 1 discusses the field monitoring, Chapter 2 reports the findings of the laboratory toxicity tests, and Chapter 3 describes the field-sampling task. Each chapter contains an objective-specific introduction, description of the study site and methods, results of research, and discussion of findings. Literature cited throughout this report is listed in Chapter 4. Additional details on the study methdology and results are provided in Appendixes A through D.

  1. Radon concentrations in ground and drinking water in the state of Chihuahua, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Villalba, L. [Centro de Investigacion en Materiales Avanzados, S.C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, CP 31109 Chihuahua, Chih. (Mexico); Colmenero Sujo, L. [Centro de Investigacion en Materiales Avanzados, S.C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, CP 31109 Chihuahua, Chih. (Mexico); Instituto Tecnologico de Chihuahua II, Ave. de las Industrias 11101, Chihuahua, Chih. (Mexico); Montero Cabrera, M.E. [Centro de Investigacion en Materiales Avanzados, S.C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, CP 31109 Chihuahua, Chih. (Mexico)]. E-mail: elena.montero@cimav.edu.mx; Cano Jimenez, A. [Centro de Investigacion en Materiales Avanzados, S.C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, CP 31109 Chihuahua, Chih. (Mexico); Renteria Villalobos, M. [Centro de Investigacion en Materiales Avanzados, S.C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, CP 31109 Chihuahua, Chih. (Mexico); Delgado Mendoza, C.J. [Facultad de Ciencias Quimicas, Universidad Autonoma de Chihuahua, Ciudad Universitaria S/N, Chihuahua, Chih. (Mexico); Jurado Tenorio, L.A. [Facultad de Ciencias Quimicas, Universidad Autonoma de Chihuahua, Ciudad Universitaria S/N, Chihuahua, Chih. (Mexico); Davila Rangel, I. [Centro Regional de Estudios Nucleares, Universidad Autonoma de Zacatecas, Cipres 20, Zacatecas, Zac. (Mexico); Herrera Peraza, E.F. [Centro de Investigacion en Materiales Avanzados, S.C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, CP 31109 Chihuahua, Chih. (Mexico)

    2005-07-01

    This paper reports {sup 222}Rn concentrations in ground and drinking water of nine cities of Chihuahua State, Mexico. Fifty percent of the 114 sampled wells exhibited {sup 222}Rn concentrations exceeding 11 Bq/L, the maximum contaminant level (MCL) recommended by the USEPA. Furthermore, around 48% (123 samples) of the tap-water samples taken from 255 dwellings showed radon concentrations over the MCL. There is an apparent correlation between total dissolved solids and radon concentration in ground-water. The high levels of {sup 222}Rn found may be entirely attributed to the nature of aquifer rocks.

  2. Concentrations of dissolved organic carbon along an altitudinal gradient from Norway spruce forest to the mountain birch/alpine ecotone in Norway

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, N.; Roesberg, I.; Aamlid, D.

    2005-07-01

    Concentrations of dissolved organic carbon (DOC) in soil water from the base of the soil organic layer were determined at three forest plots along an altitudinal gradient in eastern Norway. The lowest plot, at 830 m above sea level (a.s.l.), was in Norway spruce forest and there were additional plots at the ecotone between Norway spruce and mountain birch at 925 m a.s.l. and at the forest line (1000 m a.s.l.). DOC concentrations in soil water did not decrease uniformly with altitude although tree biomass, above-ground litterfall and the soil C pool all did so. Significant correlations between DOC and (H{sup +}) or electrical conductivity may reflect the contribution of DOC to solution acidity and the anionic charge, respectively. If mean temperature during the growing season increases, tree growth at any given altitude will tend to increase and the spruce-birch ecotone may move to a higher altitude than at present. Increased C inputs as litter to the soil might then lead to increasing DOC concentrations and fluxes in surface waters. (orig.)

  3. Assessing pesticide concentrations and fluxes in the stream of a small vineyard catchment - Effect of sampling frequency

    International Nuclear Information System (INIS)

    Rabiet, M.; Margoum, C.; Gouy, V.; Carluer, N.; Coquery, M.

    2010-01-01

    This study reports on the occurrence and behaviour of six pesticides and one metabolite in a small stream draining a vineyard catchment. Base flow and flood events were monitored in order to assess the variability of pesticide concentrations according to the season and to evaluate the role of sampling frequency on the evaluation of fluxes estimates. Results showed that dissolved pesticide concentrations displayed a strong temporal and spatial variability. A large mobilisation of pesticides was observed during floods, with total dissolved pesticide fluxes per event ranging from 5.7 x 10 -3 g/Ha to 0.34 g/Ha. These results highlight the major role of floods in the transport of pesticides in this small stream which contributed to more than 89% of the total load of diuron during August 2007. The evaluation of pesticide loads using different sampling strategies and method calculation, showed that grab sampling largely underestimated pesticide concentrations and fluxes transiting through the stream. - This work brings new insights about the fluxes of pesticides in surface water of a vineyard catchment, notably during flood events.

  4. Assessing pesticide concentrations and fluxes in the stream of a small vineyard catchment - Effect of sampling frequency

    Energy Technology Data Exchange (ETDEWEB)

    Rabiet, M., E-mail: marion.rabiet@unilim.f [Cemagref, UR QELY, 3bis quai Chauveau, CP 220, F-69336 Lyon (France); Margoum, C.; Gouy, V.; Carluer, N.; Coquery, M. [Cemagref, UR QELY, 3bis quai Chauveau, CP 220, F-69336 Lyon (France)

    2010-03-15

    This study reports on the occurrence and behaviour of six pesticides and one metabolite in a small stream draining a vineyard catchment. Base flow and flood events were monitored in order to assess the variability of pesticide concentrations according to the season and to evaluate the role of sampling frequency on the evaluation of fluxes estimates. Results showed that dissolved pesticide concentrations displayed a strong temporal and spatial variability. A large mobilisation of pesticides was observed during floods, with total dissolved pesticide fluxes per event ranging from 5.7 x 10{sup -3} g/Ha to 0.34 g/Ha. These results highlight the major role of floods in the transport of pesticides in this small stream which contributed to more than 89% of the total load of diuron during August 2007. The evaluation of pesticide loads using different sampling strategies and method calculation, showed that grab sampling largely underestimated pesticide concentrations and fluxes transiting through the stream. - This work brings new insights about the fluxes of pesticides in surface water of a vineyard catchment, notably during flood events.

  5. Export and retention of dissolved inorganic nutrients in the Cachoeira River, Ilhéus, Bahia, Brazil

    Directory of Open Access Journals (Sweden)

    Maria A.M. SILVA

    2010-02-01

    Full Text Available Dissolved inorganic nutrient concentrations and physical-chemical variables were determined in the lower reaches of the Cachoeira River watershed, from November 2003 to October 2004. Concentration of nutrients were high and highly variable. Mean concentrations and standard deviation of ammonium, nitrite, nitrate, phosphate and silicate were 25.4 ± 25.1; 3.9 ± 3.9; 62.2 ± 54.9; 15.8 ± 9.0 and 129.0 ± 5.6 (μmol L-1, respectively. Nutrient retention was observed mainly during the dry season. Chlorophyll-a concentrations were especially high in those periods. The Cachoeira River can be considered eutrophicated, and such condition becomes more intense with low fluvial flow during the dry months. Despite the spatial/temporal changes of the species of inorganic nitrogen, a removal of dissolved inorganic nitrogen was observed in relation to dissolved silicon and to phosphorus, with consequences for estuarine biogeochemistry. The basin exports annually about 3.5, 2.2 and 0.3 t y-1 of dissolved silicon, nitrogen, and phosphate to the estuary, respectively. The eutrophication and growth of macrophytes is responsible for most of these changes in nutrient fluxes to the estuary and coastal waters.

  6. Relative importance of dissolved and food pathways for lead contamination in shrimp

    Energy Technology Data Exchange (ETDEWEB)

    Boisson, F.; Cotret, O.; Teyssie, J.-L.; El-Baradeie, M.; Fowler, S.W

    2003-12-01

    The relative importance of dissolved and food pathways and the influence of food type in the bioaccumulation and retention of lead in the shrimp Palaemonetes varians were examined using a radiotracer method. Shrimp were exposed to {sup 210}Pb-labelled seawater or fed two types of {sup 210}Pb-labelled food, viz. mussels or worms. The amount of radiotracer accumulated by shrimp was examined over a 7-day period, followed by a 1-month and a 7-day depuration period for the dissolved and food source, respectively. Steady state in the uptake was reached after 2 days exposure to dissolved lead, with a resultant estimated concentration factor of 98 {+-} 3. Transfer factors following ingestion of contaminated mussels and worms were lower than unity for both food types, with lead transfer from worms being significantly higher than that from mussels. Accumulation of dissolved Pb by shrimp was found to occur mainly through adsorption on the exoskeleton with a minor accumulation in the internal tissues probably resulting from the intake of seawater for osmoregulation. In contrast, lead taken up from contaminated food was readily absorbed and bound in the internal tissues of P. varians. Although the transfer of lead to P. varians through the ingestion of contaminated food was low (TF < 1%), it still represented 4 to 8% of the lead content in the prey which is a significant additional contribution of lead to the shrimp body burden. Independent of food type, following ingestion of contaminated food, approximately 23-27% of total lead accumulated in shrimp was located in the edible parts (e.g. muscle). Therefore, the food pathway is suggested to be a significant contributor to the lead transfer to humans through ingestion of contaminated shrimp. After exposure to contaminated food, lead loss kinetics were described by a two-component model, whereas Pb loss following direct uptake from seawater was best described by a three-component model. The additional compartment representing 64

  7. Relative importance of dissolved and food pathways for lead contamination in shrimp

    International Nuclear Information System (INIS)

    Boisson, F.; Cotret, O.; Teyssie, J.-L.; El-Baradeie, M.; Fowler, S.W.

    2003-01-01

    The relative importance of dissolved and food pathways and the influence of food type in the bioaccumulation and retention of lead in the shrimp Palaemonetes varians were examined using a radiotracer method. Shrimp were exposed to 210 Pb-labelled seawater or fed two types of 210 Pb-labelled food, viz. mussels or worms. The amount of radiotracer accumulated by shrimp was examined over a 7-day period, followed by a 1-month and a 7-day depuration period for the dissolved and food source, respectively. Steady state in the uptake was reached after 2 days exposure to dissolved lead, with a resultant estimated concentration factor of 98 ± 3. Transfer factors following ingestion of contaminated mussels and worms were lower than unity for both food types, with lead transfer from worms being significantly higher than that from mussels. Accumulation of dissolved Pb by shrimp was found to occur mainly through adsorption on the exoskeleton with a minor accumulation in the internal tissues probably resulting from the intake of seawater for osmoregulation. In contrast, lead taken up from contaminated food was readily absorbed and bound in the internal tissues of P. varians. Although the transfer of lead to P. varians through the ingestion of contaminated food was low (TF < 1%), it still represented 4 to 8% of the lead content in the prey which is a significant additional contribution of lead to the shrimp body burden. Independent of food type, following ingestion of contaminated food, approximately 23-27% of total lead accumulated in shrimp was located in the edible parts (e.g. muscle). Therefore, the food pathway is suggested to be a significant contributor to the lead transfer to humans through ingestion of contaminated shrimp. After exposure to contaminated food, lead loss kinetics were described by a two-component model, whereas Pb loss following direct uptake from seawater was best described by a three-component model. The additional compartment representing 64% of total Pb

  8. Dissolved atmospheric gas in xylem sap measured with membrane inlet mass spectrometry.

    Science.gov (United States)

    Schenk, H Jochen; Espino, Susana; Visser, Ate; Esser, Bradley K

    2016-04-01

    A new method is described for measuring dissolved gas concentrations in small volumes of xylem sap using membrane inlet mass spectrometry. The technique can be used to determine concentrations of atmospheric gases, such as argon, as reported here, or for any dissolved gases and their isotopes for a variety of applications, such as rapid detection of trace gases from groundwater only hours after they were taken up by trees and rooting depth estimation. Atmospheric gas content in xylem sap directly affects the conditions and mechanisms that allow for gas removal from xylem embolisms, because gas can dissolve into saturated or supersaturated sap only under gas pressure that is above atmospheric pressure. The method was tested for red trumpet vine, Distictis buccinatoria (Bignoniaceae), by measuring atmospheric gas concentrations in sap collected at times of minimum and maximum daily temperature and during temperature increase and decline. Mean argon concentration in xylem sap did not differ significantly from saturation levels for the temperature and pressure conditions at any time of collection, but more than 40% of all samples were supersaturated, especially during the warm parts of day. There was no significant diurnal pattern, due to high variability between samples. © 2015 John Wiley & Sons Ltd.

  9. Biogeochemical controls of uranium bioavailability from the dissolved phase in natural freshwaters

    Science.gov (United States)

    Croteau, Marie-Noele; Fuller, Christopher C.; Cain, Daniel J.; Campbell, Kate M.; Aiken, George R.

    2016-01-01

    To gain insights into the risks associated with uranium (U) mining and processing, we investigated the biogeochemical controls of U bioavailability in the model freshwater speciesLymnaea stagnalis (Gastropoda). Bioavailability of dissolved U(VI) was characterized in controlled laboratory experiments over a range of water hardness, pH, and in the presence of complexing ligands in the form of dissolved natural organic matter (DOM). Results show that dissolved U is bioavailable under all the geochemical conditions tested. Uranium uptake rates follow first order kinetics over a range encompassing most environmental concentrations. Uranium uptake rates in L. stagnalis ultimately demonstrate saturation uptake kinetics when exposure concentrations exceed 100 nM, suggesting uptake via a finite number of carriers or ion channels. The lack of a relationship between U uptake rate constants and Ca uptake rates suggest that U does not exclusively use Ca membrane transporters. In general, U bioavailability decreases with increasing pH, increasing Ca and Mg concentrations, and when DOM is present. Competing ions did not affect U uptake rates. Speciation modeling that includes formation constants for U ternary complexes reveals that the aqueous concentration of dicarbonato U species (UO2(CO3)2–2) best predicts U bioavailability to L. stagnalis, challenging the free-ion activity model postulate.

  10. Development of an aquaculture system using nanobubble technology for the optimation of dissolved oxygen in culture media for nile tilapia (Oreochromis niloticus)

    Science.gov (United States)

    Mahasri, G.; Saskia, A.; Apandi, P. S.; Dewi, N. N.; Rozi; Usuman, N. M.

    2018-04-01

    The purpose of this research was to discover the process of enrichment of dissolved oxygen in fish cultivation media using nanobubble technology. This study was conducted with two treatments, namely a cultivation media without fish and a cultivation media containing 8 fish with an average body length of 24.5 cm. The results showed that the concentration of dissolved oxygen increased from 6.5 mg/L to 25 mg/L. The rate of increase in dissolved oxygen concentration for 30 minutes is 0.61 pp/minute. The rate of decrease in dissolved oxygen concentration in treatment 1 is 3.08 ppm/day and in treatment 2 is 0.23 ppm/minute. It was concluded that nanobubble is able to increase dissolved oxygen.

  11. Characterization of water quality and simulation of temperature, nutrients, biochemical oxygen demand, and dissolved oxygen in the Wateree River, South Carolina, 1996-98

    Science.gov (United States)

    Feaster, Toby D.; Conrads, Paul

    2000-01-01

    In May 1996, the U.S. Geological Survey entered into a cooperative agreement with the Kershaw County Water and Sewer Authority to characterize and simulate the water quality in the Wateree River, South Carolina. Longitudinal profiling of dissolved-oxygen concentrations during the spring and summer of 1996 revealed dissolved-oxygen minimums occurring upstream from the point-source discharges. The mean dissolved-oxygen decrease upstream from the effluent discharges was 2.0 milligrams per liter, and the decrease downstream from the effluent discharges was 0.2 milligram per liter. Several theories were investigated to obtain an improved understanding of the dissolved-oxygen dynamics in the upper Wateree River. Data suggest that the dissolved-oxygen concentration decrease is associated with elevated levels of oxygen-consuming nutrients and metals that are flowing into the Wateree River from Lake Wateree. Analysis of long-term streamflow and water-quality data collected at two U.S. Geological Survey gaging stations suggests that no strong correlation exists between streamflow and dissolved-oxygen concentrations in the Wateree River. However, a strong negative correlation does exist between dissolved-oxygen concentrations and water temperature. Analysis of data from six South Carolina Department of Health and Environmental Control monitoring stations for 1980.95 revealed decreasing trends in ammonia nitrogen at all stations where data were available and decreasing trends in 5-day biochemical oxygen demand at three river stations. The influence of various hydrologic and point-source loading conditions on dissolved-oxygen concentrations in the Wateree River were determined by using results from water-quality simulations by the Branched Lagrangian Transport Model. The effects of five tributaries and four point-source discharges were included in the model. Data collected during two synoptic water-quality samplings on June 23.25 and August 11.13, 1997, were used to calibrate

  12. Influence of natural dissolved organic carbon on the bioavailability of mercury to a freshwater alga

    International Nuclear Information System (INIS)

    Gorski, P.R.; Armstrong, D.E.; Hurley, J.P.; Krabbenhoft, D.P.

    2008-01-01

    Bioavailability of mercury (Hg) to Selenastrum capricornutum was assessed in bioassays containing field-collected freshwater of varying dissolved organic carbon (DOC) concentrations. Bioconcentration factor (BCF) was measured using stable isotopes of methylmercury (MeHg) and inorganic Hg(II). BCFs for MeHg in low-DOC lake water were significantly larger than those in mixtures of lake water and high-DOC river water. The BCF for MeHg in rainwater (lowest DOC) was the largest of any treatment. Rainwater and lake water also had larger BCFs for Hg(II) than river water. Moreover, in freshwater collected from several US and Canadian field sites, BCFs for Hg(II) and MeHg were low when DOC concentrations were >5 mg L -1 . These results suggest high concentrations of DOC inhibit bioavailability, while low concentrations may provide optimal conditions for algal uptake of Hg. However, variability of BCFs at low DOC indicates that DOC composition or other ligands may determine site-specific bioavailability of Hg. - Bioavailability of mercury to an alga was greatest at low concentrations of natural dissolved organic carbon and inhibited at high concentrations of natural dissolved organic carbon

  13. Freshwater and Saline Loads of Dissolved Inorganic Nitrogen to Hood Canal and Lynch Cove, Western Washington

    Science.gov (United States)

    Paulson, Anthony J.; Konrad, Christopher P.; Frans, Lonna M.; Noble, Marlene; Kendall, Carol; Josberger, Edward G.; Huffman, Raegan L.; Olsen, Theresa D.

    2006-01-01

    Hood Canal is a long (110 kilometers), deep (175 meters) and narrow (2 to 4 kilometers wide) fjord of Puget Sound in western Washington. The stratification of a less dense, fresh upper layer of the water column causes the cold, saltier lower layer of the water column to be isolated from the atmosphere in the late summer and autumn, which limits reaeration of the lower layer. In the upper layer of Hood Canal, the production of organic matter that settles and consumes dissolved oxygen in the lower layer appears to be limited by the load of dissolved inorganic nitrogen (DIN): nitrate, nitrite, and ammonia. Freshwater and saline loads of DIN to Hood Canal were estimated from available historical data. The freshwater load of DIN to the upper layer of Hood Canal, which could be taken up by phytoplankton, came mostly from surface and ground water from subbasins, which accounts for 92 percent of total load of DIN to the upper layer of Hood Canal. Although DIN in rain falling on land surfaces amounts to about one-half of the DIN entering Hood Canal from subbasins, rain falling directly on the surface of marine waters contributed only 4 percent of the load to the upper layer. Point-source discharges and subsurface flow from shallow shoreline septic systems contributed less than 4 percent of the DIN load to the upper layer. DIN in saline water flowing over the sill into Hood Canal from Admiralty Inlet was at least 17 times the total load to the upper layer of Hood Canal. In September and October 2004, field data were collected to estimate DIN loads to Lynch Cove - the most inland marine waters of Hood Canal that routinely contain low dissolved-oxygen waters. Based on measured streamflow and DIN concentrations, surface discharge was estimated to have contributed about one-fourth of DIN loads to the upper layer of Lynch Cove. Ground-water flow from subbasins was estimated to have contributed about one-half of total DIN loads to the upper layer. In autumn 2004, the relative

  14. Monitoring total endotoxin and (1 --> 3)-beta-D-glucan at the air exhaust of concentrated animal feeding operations.

    Science.gov (United States)

    Yang, Xufei; Wang, Xinlei; Zhang, Yuanhui; Lee, Jongmin; Su, Jingwei; Gates, Richard S

    2013-10-01

    Mitigation of bioaerosol emissions from concentrated animal feeding operations (CAFOs) demands knowledge of bioaerosol concentrations feeding into an end-of-pipe air treatment process. The aim of this preliminary study was to measure total endotoxin and (1 --> 3)-beta-glucan concentrations at the air exhaust of 18 commercial CAFOs and to examine their variability with animal operation type (swine farrowing, swine gestation, swine weaning, swine finishing, manure belt laying hen, and tom turkey) and season (cold, mild, and hot). The measured airborne concentrations of total endotoxin ranged from 98 to 23,157 endotoxin units (EU)/m3, and the airborne concentrations of total (1 --> 3)-beta-D-glucan ranged from 2.4 to 537.9 ng/m3. Animal operation type in this study had a significant effect on airborne concentrations of total endotoxin and (1 --> 3)-beta-D-glucan but no significant effect on their concentrations in total suspended particulate (TSP). Both endotoxin and (1 --> 3)-beta-D-glucan attained their highest airborne concentrations in visited tom turkey buildings. Comparatively, season had no significant effect on airborne concentrations of total endotoxin or (1 --> 3)-beta-D-glucan. Endotoxin and (1 --> 3)-beta-glucan concentrations in TSP dust appeared to increase as the weather became warmer, and this seasonal effect was significant in swine buildings. Elevated indoor temperatures in the hot season were considered to facilitate the growth and propagation of bacteria and fungi, thus leading to higher biocomponent concentrations in TSP.

  15. Self-sculpting of a dissolvable body due to gravitational convection

    Science.gov (United States)

    Davies Wykes, Megan S.; Huang, Jinzi Mac; Hajjar, George A.; Ristroph, Leif

    2018-04-01

    Natural sculpting processes such as erosion or dissolution often yield universal shapes that bear no imprint or memory of the initial conditions. Here we conduct laboratory experiments aimed at assessing the shape dynamics and role of memory for the simple case of a dissolvable boundary immersed in a fluid. Though no external flow is imposed, dissolution and consequent density differences lead to gravitational convective flows that in turn strongly affect local dissolving rates and shape changes, and we identify two distinct behaviors. A flat boundary dissolving from its lower surface tends to retain its overall shape (an example of near perfect memory) while bearing small-scale pits that reflect complex near-body flows. A boundary dissolving from its upper surface tends to erase its initial shape and form an upward spike structure that sharpens indefinitely. We propose an explanation for these different outcomes based on observations of the coupled shape dynamics, concentration fields, and flows.

  16. Dissolved helium and TDS in groundwater from Bhavnagar in Gujarat

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    2003-01-02

    Jan 2, 2003 ... by enhanced pumping of old groundwater with relatively higher concentration of dissolved helium and salt .... solubility changes due to these (Weiss 1971) can- ... aquifers and relatively low helium concentra- .... permeability.

  17. Relations among pH, sulfate, and metals concentrations in anthracite and bituminous coal-mine discharges, Pennsylvania

    Science.gov (United States)

    Cravotta, III, Charles A.

    2006-01-01

    Water-quality data for discharges from 140 abandoned mines in the Bituminous and Anthracite Coalfields of Pennsylvania illustrate relations among pH, sulfate, and dissolved metal concentrations. The pH for the 140 samples ranged from 2.7 to 7.3, with two modes at pH 2.5 to 4 (acidic) and 6 to 7 (near neutral). Generally, flow rates were smaller and solute concentrations were greater for low-pH samples; flow rates increased with pH. Although the pH distribution was similar for the bituminous and anthracite subsets, the bituminous discharges had smaller median flow rates, greater concentrations of sulfate, iron, and aluminum, and smaller concentrations of barium and lead than anthracite discharges with the same pH values. The observed relations between the pH and constituent concentrations can be attributed to (1) dilution of acidic water by alkaline ground water; (2) solubility control of aluminum, iron, manganese, barium, and lead by hydroxide, sulfate, and/or carbonate minerals; and (3) aqueous sulfate-complex formation. The formation of AlSO4+ and AlHSO4+2 complexes adds to the total dissolved aluminum concentration at pH of equilibrium with aluminum hydroxide or hydroxysulfate minerals and can account for 10 to 20 times greater concentrations of dissolved aluminum in bituminous discharges compared to anthracite discharges at similar pH. Sulfate complexation also can account for 10 to 30 times greater concentrations of dissolved ferric iron concentrations at equilibrium with ferrihydrite (Fe(OH)3) and/or schwertmannite (Fe8O8(OH)4.5(SO4)1.75) at pH of 3 to 5. In contrast, lower barium and lead concentrations in bituminous than anthracite discharges indicates elevated sulfate concentration could decrease mobility of these metals by the formation of insoluble minerals such as barite (BaSO4) or anglesite (PbSO4). Most samples were saturated with barite, but none were saturated with anglesite. Hence, lead concentrations could be controlled by coprecipitation with

  18. Distal transport of dissolved hydrothermal iron in the deep South Pacific Ocean.

    Science.gov (United States)

    Fitzsimmons, Jessica N; Boyle, Edward A; Jenkins, William J

    2014-11-25

    Until recently, hydrothermal vents were not considered to be an important source to the marine dissolved Fe (dFe) inventory because hydrothermal Fe was believed to precipitate quantitatively near the vent site. Based on recent abyssal dFe enrichments near hydrothermal vents, however, the leaky vent hypothesis [Toner BM, et al. (2012) Oceanography 25(1):209-212] argues that some hydrothermal Fe persists in the dissolved phase and contributes a significant flux of dFe to the global ocean. We show here the first, to our knowledge, dFe (Pacific Ocean, where dFe of 1.0-1.5 nmol/kg near 2,000 m depth (0.4-0.9 nmol/kg above typical deep-sea dFe concentrations) was determined to be hydrothermally derived based on its correlation with primordial (3)He and dissolved Mn (dFe:(3)He of 0.9-2.7 × 10(6)). Given the known sites of hydrothermal venting in these regions, this dFe must have been transported thousands of kilometers away from its vent site to reach our sampling stations. Additionally, changes in the size partitioning of the hydrothermal dFe between soluble (Pacific Rise only leaks 0.02-1% of total Fe vented into the abyssal Pacific, this dFe persists thousands of kilometers away from the vent source with sufficient magnitude that hydrothermal vents can have far-field effects on global dFe distributions and inventories (≥3% of global aerosol dFe input).

  19. Fuel-coolant interactions: preliminary experiments on the effect of gases dissolved in the 'coolant'

    International Nuclear Information System (INIS)

    Asher, R.C.; Davies, D.; Jones, P.G.

    1976-12-01

    A simple apparatus has been used to study fuel-coolant interactions under reasonably well controlled conditions. Preliminary experiments have used water as the 'coolant' and molten tin at 800 0 C as the 'fuel' and have investigated how the violence of the interaction is affected by dissolving gases (oxygen, nitrogen, carbon dioxide and nitrous oxide) in the water. It was found that saturating the water with carbon dioxide or nitrous oxide completely suppresses the violent interaction. Experiments in which the concentrations of these gases were varied showed that a certain critical concentration was needed; below this concentration the dissolved gas has no significant effect but above it the suppression is

  20. The measurement of dissolved and gaseous carbon dioxide concentration

    Science.gov (United States)

    Zosel, J.; Oelßner, W.; Decker, M.; Gerlach, G.; Guth, U.

    2011-07-01

    In this review the basic principles of carbon dioxide sensors and their manifold applications in environmental control, biotechnology, biology, medicine and food industry are reported. Electrochemical CO2 sensors based on the Severinghaus principle and solid electrolyte sensors operating at high temperatures have been manufactured and widely applied already for a long time. Besides these, nowadays infrared, non-dispersive infrared and acoustic CO2 sensors, which use physical measuring methods, are being increasingly used in some fields of application. The advantages and drawbacks of the different sensor technologies are outlined. Electrochemical sensors for the CO2 measurement in aqueous media are pointed out in more detail because of their simple setup and the resulting low costs. A detailed knowledge of the basic detection principles and the windows for their applications is necessary to find an appropriate decision on the technology to be applied for measuring dissolved CO2. In particular the pH value and the composition of the analyte matrix exert important influence on the results of the measurements.

  1. The measurement of dissolved and gaseous carbon dioxide concentration

    International Nuclear Information System (INIS)

    Zosel, J; Oelßner, W; Decker, M; Gerlach, G; Guth, U

    2011-01-01

    In this review the basic principles of carbon dioxide sensors and their manifold applications in environmental control, biotechnology, biology, medicine and food industry are reported. Electrochemical CO 2 sensors based on the Severinghaus principle and solid electrolyte sensors operating at high temperatures have been manufactured and widely applied already for a long time. Besides these, nowadays infrared, non-dispersive infrared and acoustic CO 2 sensors, which use physical measuring methods, are being increasingly used in some fields of application. The advantages and drawbacks of the different sensor technologies are outlined. Electrochemical sensors for the CO 2 measurement in aqueous media are pointed out in more detail because of their simple setup and the resulting low costs. A detailed knowledge of the basic detection principles and the windows for their applications is necessary to find an appropriate decision on the technology to be applied for measuring dissolved CO 2 . In particular the pH value and the composition of the analyte matrix exert important influence on the results of the measurements. (topical review)

  2. Qualitative changes of riverine dissolved organic matter at low salinities due to flocculation

    Science.gov (United States)

    Asmala, Eero; Bowers, David G.; Autio, Riitta; Kaartokallio, Hermanni; Thomas, David N.

    2014-10-01

    The flocculation of dissolved organic matter (DOM) was studied along transects through three boreal estuaries. Besides the bulk concentration parameters, a suite of DOM quality parameters were investigated, including colored DOM (CDOM), fluorescent DOM, and the molecular weight of DOM as well as associated dissolved iron concentrations. We observed significant deviations from conservative mixing at low salinities (DOC), UV absorption (a(CDOM254)), and humic-like fluorescence. The maximum deviation from conservative mixing for DOC concentration was -16%, at salinities between 1 and 2. An associated laboratory experiment was conducted where an artificial salinity gradient between 0 and 6 was created. The experiment confirmed the findings from the estuarine transects, since part of the DOC and dissolved iron pools were transformed to particulate fraction (>0.2 µm) and thereby removing them from the dissolved phase. We also measured flocculation of CDOM, especially in the UV region of the absorption spectrum. Protein-like fluorescence of DOM decreased, while humic-like fluorescence increased because of salt-induced flocculation. Additionally, there was a decrease in molecular weight of DOM. Consequently, the quantity and quality of the remaining DOM pool was significantly changed after influenced to flocculation. Based on these results, we constructed a mechanistic, two-component flocculation model. Our findings underline the importance of the coastal filter, where riverine organic matter is flocculated and exported to the sediments.

  3. Nano-Enriched and Autonomous Sensing Framework for Dissolved Oxygen

    Directory of Open Access Journals (Sweden)

    Nader Shehata

    2015-08-01

    Full Text Available This paper investigates a nano-enhanced wireless sensing framework for dissolved oxygen (DO. The system integrates a nanosensor that employs cerium oxide (ceria nanoparticles to monitor the concentration of DO in aqueous media via optical fluorescence quenching. We propose a comprehensive sensing framework with the nanosensor equipped with a digital interface where the sensor output is digitized and dispatched wirelessly to a trustworthy data collection and analysis framework for consolidation and information extraction. The proposed system collects and processes the sensor readings to provide clear indications about the current or the anticipated dissolved oxygen levels in the aqueous media.

  4. Nano-Enriched and Autonomous Sensing Framework for Dissolved Oxygen.

    Science.gov (United States)

    Shehata, Nader; Azab, Mohammed; Kandas, Ishac; Meehan, Kathleen

    2015-08-14

    This paper investigates a nano-enhanced wireless sensing framework for dissolved oxygen (DO). The system integrates a nanosensor that employs cerium oxide (ceria) nanoparticles to monitor the concentration of DO in aqueous media via optical fluorescence quenching. We propose a comprehensive sensing framework with the nanosensor equipped with a digital interface where the sensor output is digitized and dispatched wirelessly to a trustworthy data collection and analysis framework for consolidation and information extraction. The proposed system collects and processes the sensor readings to provide clear indications about the current or the anticipated dissolved oxygen levels in the aqueous media.

  5. Dissolved oxygen analysis, TMDL model comparison, and particulate matter shunting—Preliminary results from three model scenarios for the Klamath River upstream of Keno Dam, Oregon

    Science.gov (United States)

    Sullivan, Annett B.; Rounds, Stewart A.; Deas, Michael L.; Sogutlugil, I. Ertugrul

    2012-01-01

    Efforts are underway to identify actions that would improve water quality in the Link River to Keno Dam reach of the Upper Klamath River in south-central Oregon. To provide further insight into water-quality improvement options, three scenarios were developed, run, and analyzed using previously calibrated CE-QUAL-W2 hydrodynamic and water-quality models. Additional scenarios are under development as part of this ongoing study. Most of these scenarios evaluate changes relative to a "current conditions" model, but in some cases a "natural conditions" model was used that simulated the reach without the effect of point and nonpoint sources and set Upper Klamath Lake at its Total Maximum Daily Load (TMDL) targets. These scenarios were simulated using a model developed by the U.S. Geological Survey (USGS) and Watercourse Engineering, Inc. for the years 2006–09, referred to here as the "USGS model." Another model of the reach was developed by Tetra Tech, Inc. for years 2000 and 2002 to support the Klamath River TMDL process; that model is referred to here as the "TMDL model." The three scenarios described in this report included (1) an analysis of whether this reach of the Upper Klamath River would be in compliance with dissolved oxygen standards if sources met TMDL allocations, (2) an application of more recent datasets to the TMDL model with comparison to results from the USGS model, and (3) an examination of the effect on dissolved oxygen in the Klamath River if particulate material were stopped from entering Klamath Project diversion canals. Updates and modifications to the USGS model are in progress, so in the future these scenarios will be reanalyzed with the updated model and the interim results presented here will be superseded. Significant findings from this phase of the investigation include: * The TMDL analysis used depth-averaged dissolved oxygen concentrations from model output for comparison with dissolved oxygen standards. The Oregon dissolved oxygen

  6. Spatial and temporal variations of loads and sources of total and dissolved Phosphorus in a set of rivers (Western France).

    Science.gov (United States)

    Legeay, Pierre-Louis; Moatar, Florentina; Gascuel-Odoux, Chantal; Gruau, Gérard

    2015-04-01

    In intensive agricultural regions with important livestock farming, long-term land application of Phosphorus (P) both as chemical fertilizer and animal wastes, have resulted in elevated P contents in soils. Since we know that high P concentrations in rivers is of major concern, few studies have been done at to assess the spatiotemporal variability of P loads in rivers and apportionment of point and nonpoint source in total loads. Here we focus on Brittany (Western France) where even though P is a great issue in terms of human and drinking water safety (cyano-toxins), environmental protection and economic costs for Brittany with regards to the periodic proliferations of cyanobacteria that occur every year in this region, no regional-scale systematic study has been carried out so far. We selected a set of small rivers (stream order 3-5) with homogeneous agriculture and granitic catchment. By gathering data from three water quality monitoring networks, covering more than 100 measurements stations, we provide a regional-scale quantification of the spatiotemporal variability of dissolved P (DP) and total P (TP) interannual loads from 1992 to 2012. Build on mean P load in low flows and statistical significance tests, we developed a new indicator, called 'low flow P load' (LFP-load), which allows us to determine the importance of domestic and industrial P sources in total P load and to assess their spatiotemporal variability compared to agricultural sources. The calculation and the map representation of DP and TP interannual load variations allow identification of the greatest and lowest P contributory catchments over the study period and the way P loads of Brittany rivers have evolved through time. Both mean DP and TP loads have been divided by more than two over the last 20 years. Mean LFDP-load decreased by more than 60% and mean LFTP-load by more than 45% on average over the same period showing that this marked temporal decrease in total load is largely due to the

  7. Recovering/concentrating of hemicellulosic sugars and acetic acid by nanofiltration and reverse osmosis from prehydrolysis liquor of kraft based hardwood dissolving pulp process.

    Science.gov (United States)

    Ahsan, Laboni; Jahan, M Sarwar; Ni, Yonghao

    2014-03-01

    This work investigated the feasibility of recovering and concentrating sugars and acetic acid (HAc) from prehydrolysis liquor (PHL) of the kraft-based dissolving pulp process prior to fermentation of hemicellulosic sugars, by the combination of activated carbon adsorption, nanofiltration (NF) and reverse osmosis (RO) processes. To reduce the fouling PHL was subjected to adsorption on activated carbon, then the treated PHL (TPHL) passed through a nanofiltration (NF DK) membrane to retain the sugars, and the permeate of acetic acid rich solution was passed through a reverse osmosis membrane (RO SG). It was found that for NF process sugars were concentrated from 48 to 227g/L at a volume reduction factor (VRF) of 5 while 80 to 90% of acetic acid was permeated. For the reverse osmosis process, 68% of acetic acid retention was achieved at pH 4.3 and 500 psi pressure and the HAc concentration increased from 10 to 50g/L. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  8. Absorption and fluorescence properties of chromophoric dissolved organic matter: implications for the monitoring of water quality in a large subtropical reservoir.

    Science.gov (United States)

    Liu, Xiaohan; Zhang, Yunlin; Shi, Kun; Zhu, Guangwei; Xu, Hai; Zhu, Mengyuan

    2014-12-01

    The development of techniques for real-time monitoring of water quality is of great importance for effectively managing inland water resources. In this study, we first analyzed the absorption and fluorescence properties in a large subtropical reservoir and then used a chromophoric dissolved organic matter (CDOM) fluorescence monitoring sensor to predict several water quality parameters including the total nitrogen (TN), total phosphorus (TP), chemical oxygen demand (COD), dissolved organic carbon (DOC), and CDOM fluorescence parallel factor analysis (PARAFAC) components in the reservoir. The CDOM absorption coefficient at 254 nm (a(254)), the humic-like component (C1), and the tryptophan-like component (C3) decreased significantly along a gradient from the northwest to the lake center, northeast, southwest, and southeast region in the reservoir. However, no significant spatial difference was found for the tyrosine-like component (C2), which contributed only four marked peaks. A highly significant linear correlation was found between the a(254) and CDOM concentration measured using the CDOM fluorescence sensor (r(2) = 0.865, n = 76, p CDOM concentrations could act as a proxy for the CDOM absorption coefficient measured in the laboratory. Significant correlations were also found between the CDOM concentration and TN, TP, COD, DOC, and the maximum fluorescence intensity of C1, suggesting that the real-time monitoring of CDOM concentrations could be used to predict these water quality parameters and trace the humic-like fluorescence substance in clear aquatic ecosystems with DOC CDOM fluorescence sensor is a useful tool for on-line water quality monitoring if the empirical relationship between the CDOM concentration measured using the CDOM fluorescence sensor and the water quality parameters is calibrated and validated.

  9. The biogeochemistry of nutrients, dissolved oxygen and chlorophyll a in the Catalan Sea (NW Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    Mariona Segura-Noguera

    2016-09-01

    Full Text Available Reference depth profiles of dissolved inorganic nutrients, dissolved oxygen and chlorophyll a are described for the Catalan Sea using quality controlled data. Phosphate, nitrate and silicate show typical nutrient profiles, with nutriclines at different depths. Maximums of nitrite, dissolved oxygen and occasionally ammonium are found within the photic zone, close to the deep chlorophyll maximum. In intermediate waters we found a minimum of dissolved oxygen coincident with maximum concentrations of phosphate and nitrate. Ammonium concentration is unexpectedly high in the mesopelagic zone, where there are still measurable nitrite concentrations. The origin of such high ammonium and nitrite concentrations remains unclear. We also identify and describe anomalous data and profiles resulting from eutrophication, western Mediterranean Deep Water formation and dense shelf water cascading. The N:P ratio in deep waters is 22.4, which indicates P limitation relative to the Redfield ratio. However, the N:P ratio above the deep chlorophyll maximum in stratified surface waters is < 4 (< 8 including ammonium. The depth profiles of key biogeochemical variables described in this study will be a useful reference for future studies in the Catalan Sea (NW Mediterranean Sea in order to validate data sampled in this area, to identify anomalous processes, and to study the evolution of the ecosystem following the undergoing global change.

  10. Influence of dissolved organic carbon on the sorption of plutonium to natural sediments

    International Nuclear Information System (INIS)

    Nelson, D.M.; Karttunen, J.O.; Orlandini, K.A.; Larsen, R.P.

    1981-01-01

    One prominent aspect of the environmental behavior of plutonium is a tendency for strong, though not complete, association with soil and sediments. The nature of this association is not well understood, and the water quality parameters which may affect it have not been identified. It is assumed that adsorption is dependent upon the chemical species present (oxidation state and complex ion associations) and that the uncomplexed form of Pu(IV) is the one that is most highly sorbed. In certain oligotrophic waters the dissolved plutonium is primarily in the oxidized form (presumably as Pu(V)), a form that is weakly sorbed. This could account for its solubility. In all water, however, some of the dissolved plutonium is present in the reduced form (presumably as Pu(IV)). The apparent solubility of this reduced form, as measured by a sediment concentration factor, varies markedly among the lakes. The concentrations of dissolved organic carbon (DOC) have now been measured in the waters from a number of lakes and a general dependence of the sediment concentration factor (K/sub D/) for Pu(IV) upon DOC has become evident. In order to study the nature of this plutonium-organic complex in more detail several experiments were conducted in which the sediment concentration factor was measured as a function of DOC concentration

  11. Highly Polluted Wastewaters Treatment by Improved Dissolved Air Flotation Technology

    Science.gov (United States)

    Moga, I. C.; Covaliu, C. I.; Matache, M. G.; Doroftei, B. I.

    2017-06-01

    Numerous investigations are oriented towards the development of new wastewater treatment technologies, having high efficiencies for removing even low concentrations of pollutants found in water. These efforts were determined by the destroyer impact of the pollutants to the environment and human’s health. For this reason this paper presents our study concerning an improved dissolved air flotation technology for wastewater treatment. There is described a dissolved air flotation (DAF) installation composed by two equipments: pressurized capsule and lamellar settling. Also, there are presented some advantages of using nanoparticles as flotation collectors.

  12. Achieving low effluent NO3-N and TN concentrations in low influent chemical oxygen demand (COD) to total Kjeldahl nitrogen (TKN) ratio without using external carbon source

    Science.gov (United States)

    Cao, Jiashun; Oleyiblo, Oloche James; Xue, Zhaoxia; Otache, Y. Martins; Feng, Qian

    2015-07-01

    Two mathematical models were used to optimize the performance of a full-scale biological nutrient removal (BNR) activated treatment plant, a plug-flow bioreactors operated in a 3-stage phoredox process configuration, anaerobic anoxic oxic (A2/O). The ASM2d implemented on the platform of WEST2011 software and the BioWin activated sludge/anaerobic digestion (AS/AD) models were used in this study with the aim of consistently achieving the designed effluent criteria at a low operational cost. Four ASM2d parameters (the reduction factor for denitrification , the maximum growth rate of heterotrophs (µH), the rate constant for stored polyphosphates in PAOs ( q pp), and the hydrolysis rate constant ( k h)) were adjusted. Whereas three BioWin parameters (aerobic decay rate ( b H), heterotrophic dissolved oxygen (DO) half saturation ( K OA), and Y P/acetic) were adjusted. Calibration of the two models was successful; both models have average relative deviations (ARD) less than 10% for all the output variables. Low effluent concentrations of nitrate nitrogen (N-NO3), total nitrogen (TN), and total phosphorus (TP) were achieved in a full-scale BNR treatment plant having low influent chemical oxygen demand (COD) to total Kjeldahl nitrogen (TKN) ratio (COD/TKN). The effluent total nitrogen and nitrate nitrogen concentrations were improved by 50% and energy consumption was reduced by approximately 25%, which was accomplished by converting the two-pass aerobic compartment of the plug-flow bioreactor to anoxic reactors and being operated in an alternating mode. Findings in this work are helpful in improving the operation of wastewater treatment plant while eliminating the cost of external carbon source and reducing energy consumption.

  13. Contrasting distributions of dissolved gaseous mercury concentration and evasion in the North Pacific Subarctic Gyre and the Subarctic Front

    Science.gov (United States)

    Kim, Hyunji; Rhee, Tae Siek; Hahm, Doshik; Hwang, Chung Yeon; Yang, Jisook; Han, Seunghee

    2016-04-01

    The distribution of dissolved gaseous mercury (DGM) and the oxidation-reduction processes of mercury (Hg) in the surface and subsurface ocean are currently understudied despite their importance in ocean-atmosphere interactions. We investigated the Hg(0) evasion and the DGM distribution at water depths of 2-500 m in the Subarctic Front, Western Subarctic Gyre, and Bering Sea of the Northwestern Pacific. The mean DGM concentration in the surface mixed water (evasion flux were significantly higher in the Subarctic Front (125±5.0 fM and 15 pmol m-2 h-1, respectively), which typically has lower nutrient levels and higher primary production, than in the Western Subarctic Gyre and the Bering Sea (74±18 fM and 3.2±1.2 pmol m-2 h-1, respectively). The variation in the chlorophyll-a concentration and extracellular protease activity predicted 54% and 48% of the DGM variation, respectively, in the euphotic zone (2-50 m). The DGM concentration in aphotic intermediate water (415±286 fM) was positively correlated to the apparent oxygen utilization (AOU; r2=0.94 and pevasion is closely linked to primary production in euphotic water and organic remineralization in aphotic intermediate water. The oceanic alterations in these factors may induce significant modification in Hg redox speciation in the Northwestern Pacific.

  14. Effects of total gastrectomy on plasma silicon and amino acid concentrations in men.

    Science.gov (United States)

    Tatara, Marcin R; Krupski, Witold; Szpetnar, Maria; Dąbrowski, Andrzej; Bury, Paweł; Szabelska, Anna; Charuta, Anna; Boguszewska-Czubara, Anna; Maciejewski, Ryszard; Wallner, Grzegorz

    2015-12-01

    The aim of the study was to determine one-year effects of total gastrectomy on plasma silicon and free amino acid concentrations in patients and evaluate changes of volumetric bone mineral density (vBMD) in lumbar spine. Eight patients were enrolled to the control (CTR) group. Six patients subjected to total gastrectomy (GX group) were included to the experimental group. vBMD in trabecular and cortical bone was measured in lumbar vertebrae at baseline (before surgery) and one year later using quantitative computed tomography. Plasma concentrations of silicon and free amino acids were determined at baseline and one year later using photometric method and ion-exchange chromatography. Body weights within CTR and GX groups were not different after one-year follow-up when compared to the baseline values (P > 0.05). An average annual decrease of vBMD in the trabecular bone in the gastrectomized patients reached 15.0% in lumbar spine and was significantly different in comparison to the percentage changes observed in CTR group (P = 0.02). One-year percentage change of vBMD in the cortical bone in L1 and L2 has shown significantly decreased values by 10.5 and 9.1% in the GX group when compared to the percentage change observed in the controls (P silicon was significantly lowered by 26.7% one year after the total gastrectomy when compared to the baseline value (P = 0.009). Total gastrectomy in patients has induced severe osteoporotic changes in lumbar spine within one-year period. The observed osteoporotic changes were associated with decreased plasma concentration of silicon indicating importance of exocrine and endocrine functions of stomach for silicon homeostasis maintenance. Gastrectomy-induced bone loss was not related to decreased amino acid concentration in plasma obtained from overnight fasted patients. © 2015 by the Society for Experimental Biology and Medicine.

  15. Influence of PAHs among other coastal environmental variables on total and PAH-degrading bacterial communities.

    Science.gov (United States)

    Sauret, Caroline; Tedetti, Marc; Guigue, Catherine; Dumas, Chloé; Lami, Raphaël; Pujo-Pay, Mireille; Conan, Pascal; Goutx, Madeleine; Ghiglione, Jean-François

    2016-03-01

    We evaluated the relative impact of anthropogenic polycyclic aromatic hydrocarbons (PAHs) among biogeochemical variables on total, metabolically active, and PAH bacterial communities in summer and winter in surface microlayer (SML) and subsurface seawaters (SSW) across short transects along the NW Mediterranean coast from three harbors, one wastewater effluent, and one nearshore observatory reference site. At both seasons, significant correlations were found between dissolved total PAH concentrations and PAH-degrading bacteria that formed a gradient from the shore to nearshore waters. Accumulation of PAH degraders was particularly high in the SML, where PAHs accumulated. Harbors and wastewater outfalls influenced drastically and in a different way the total and active bacterial community structure, but they only impacted the communities from the nearshore zone (PAH concentrations on the spatial and temporal dynamic of total and active communities in this area, but this effect was putted in perspective by the importance of other biogeochemical variables.

  16. Hydrogen ion (Ph), ammonia, dissolved oxygen and nitrite ...

    African Journals Online (AJOL)

    Hydrogen ion (pH), dissolved oxygen, ammonia and nitrite concentrations were studied monthly in two systems (re-circulatory and semi-intensive of 3 m2 sizes) each for six months. The systems were each stocked with 200 g of Clarias gariepinus fingerlings. Results showed that all parameters were within acceptable limits ...

  17. Mathematical modeling of dissolved oxygen in fish ponds

    African Journals Online (AJOL)

    TUOYO

    A mathematical model was developed to predict the effects of wind speed, light, pH, Temperature, dissolved carbon dioxide .... chlorophyll, the energy obtained splits water, and oxygen ... is a function of temperature T, light L, substrate, and pH as shown in ..... plants and its relation to the concentration of carbon dioxide and.

  18. Characteristic of riverine dissolved inorganic nitrogen export in subtropic high-standing island, Taiwan

    Science.gov (United States)

    Lee, Li-Chin; Huang, -Chuan, Jr.; Lee, Tsung-Yu; Shih, Yu-Ting

    2015-04-01

    Extreme increase of anthropogenic nitrogen (e.g. fertilizer and excretion) has altered the nitrogen cycling and terrestrial ecosystems. Taiwan located between eastern Asia and Oceania is the hotspot of global riverine DIN (dissolved inorganic nitrogen, including NH4, NO3, and NO2) export, but rarely documented comprehensively. Totally 50 catchments, covering 2/3 of this island, with different anthropogenic activities are involved in this study. The monthly sampling for NH4 and seasonal sampling for NO3 and NO2 supplemented with daily discharge are used to estimate the riverine DIN export. Meanwhile, the landscape characteristics, land-use, and population density are also used to discriminate the characteristics of riverine DIN export. Results showed that the observed riverine DIN concentration and yield vary from 17.7-603.5 μM and 575.0-15588.9 kg-N km-2 yr-1 corresponding to the increase of anthropogenic activities. The arithmetic mean of DIN concentration and yield are 126.7μM and 3594.7 kg-N km-2 yr-1, respectively. The unexpected high yields can attribute to abundant precipitation, heavy fertilizer application, and high population. For concentration variation, no significant variation can be found in the pristine and agriculture-dominated catchments, whereas the strong dilution effect in the wet season is characterized in the intensively-disturbed catchments. Although there are some seasonal variations in concentration, the yields in wet season are almost doubled than that in dry season indicating the strong control of streamflow. For speciation, NH4 is the dominant species in intensively-disturbed catchment, but NO3 dominates the DIN composition for the pristine and agriculture-dominated catchments. Our result can provide a strong basis for supplementary estimation for regional to global study and DIN export control which is the aim of the Kampala Declaration on global nitrogen management. Keywords: dissolved inorganic nitrogen, anthropogenic nitrogen

  19. Effects of resuspension on benthic fluxes of oxygen, nutrients, dissolved inorganic carbon, iron and manganese in the Gulf of Finland, Baltic Sea

    NARCIS (Netherlands)

    Almroth, E.; Tengberg, A.; Andersson, J.H.; Pakhomova, S.; Hall, P.O.J.

    2009-01-01

    The effect of resuspension on benthic fluxes of oxygen (O2), ammonium (NH4+), nitrate (NO3-), phosphate (PO43-), silicate (Si(OH)4), dissolved inorganic carbon (DIC), total dissolved iron (Fe) and total dissolved manganese (Mn) was studied at three different stations in the Gulf of Finland (GoF),

  20. Seasonal and nonseasonal variability of satellite-derived chlorophyll and colored dissolved organic matter concentration in the California Current

    Science.gov (United States)

    Kahru, Mati; Mitchell, B. Greg

    2001-02-01

    Time series of surface chlorophyll a concentration (Chl) and colored dissolved organic matter (CDOM) derived from the Ocean Color and Temperature Sensor and Sea-Viewing Wide Field-of-View Sensor were evaluated for the California Current area using regional algorithms. Satellite data composited for 8-day periods provide the ability to describe large-scale changes in surface parameters. These changes are difficult to detect based on in situ observations alone that suffer from undersampling the large temporal and spatial variability, especially in Chl. We detected no significant bias in satellite Chl estimates compared with ship-based measurements. The variability in CDOM concentration was significantly smaller than that in Chl, both spatially and temporally. While being subject to large interannual and short-term variations, offshore waters (100-1000 km from the shore) have an annual cycle of Chl and CDOM with a maximum in winter-spring (December-March) and a minimum in late summer. For inshore waters the maximum is more likely in spring (April-May). We detect significant increase in both Chl and CDOM off central and southern California during the La Niña year of 1999. The trend of increasing Chl and CDOM from October 1996 to June 2000 is statistically significant in many areas.

  1. A record of deep-ocean dissolved O2 from the oxidation state of iron in submarine basalts

    Science.gov (United States)

    Stolper, Daniel A.; Keller, C. Brenhin

    2018-01-01

    The oxygenation of the deep ocean in the geological past has been associated with a rise in the partial pressure of atmospheric molecular oxygen (O2) to near-present levels and the emergence of modern marine biogeochemical cycles. It has also been linked to the origination and diversification of early animals. It is generally thought that the deep ocean was largely anoxic from about 2,500 to 800 million years ago, with estimates of the occurrence of deep-ocean oxygenation and the linked increase in the partial pressure of atmospheric oxygen to levels sufficient for this oxygenation ranging from about 800 to 400 million years ago. Deep-ocean dissolved oxygen concentrations over this interval are typically estimated using geochemical signatures preserved in ancient continental shelf or slope sediments, which only indirectly reflect the geochemical state of the deep ocean. Here we present a record that more directly reflects deep-ocean oxygen concentrations, based on the ratio of Fe3+ to total Fe in hydrothermally altered basalts formed in ocean basins. Our data allow for quantitative estimates of deep-ocean dissolved oxygen concentrations from 3.5 billion years ago to 14 million years ago and suggest that deep-ocean oxygenation occurred in the Phanerozoic (541 million years ago to the present) and potentially not until the late Palaeozoic (less than 420 million years ago).

  2. A record of deep-ocean dissolved O2 from the oxidation state of iron in submarine basalts.

    Science.gov (United States)

    Stolper, Daniel A; Keller, C Brenhin

    2018-01-18

    The oxygenation of the deep ocean in the geological past has been associated with a rise in the partial pressure of atmospheric molecular oxygen (O 2 ) to near-present levels and the emergence of modern marine biogeochemical cycles. It has also been linked to the origination and diversification of early animals. It is generally thought that the deep ocean was largely anoxic from about 2,500 to 800 million years ago, with estimates of the occurrence of deep-ocean oxygenation and the linked increase in the partial pressure of atmospheric oxygen to levels sufficient for this oxygenation ranging from about 800 to 400 million years ago. Deep-ocean dissolved oxygen concentrations over this interval are typically estimated using geochemical signatures preserved in ancient continental shelf or slope sediments, which only indirectly reflect the geochemical state of the deep ocean. Here we present a record that more directly reflects deep-ocean oxygen concentrations, based on the ratio of Fe 3+ to total Fe in hydrothermally altered basalts formed in ocean basins. Our data allow for quantitative estimates of deep-ocean dissolved oxygen concentrations from 3.5 billion years ago to 14 million years ago and suggest that deep-ocean oxygenation occurred in the Phanerozoic (541 million years ago to the present) and potentially not until the late Palaeozoic (less than 420 million years ago).

  3. Iron persistence in a distal hydrothermal plume supported by dissolved-particulate exchange

    Science.gov (United States)

    Fitzsimmons, Jessica N.; John, Seth G.; Marsay, Christopher M.; Hoffman, Colleen L.; Nicholas, Sarah L.; Toner, Brandy M.; German, Christopher R.; Sherrell, Robert M.

    2017-02-01

    Hydrothermally sourced dissolved metals have been recorded in all ocean basins. In the oceans' largest known hydrothermal plume, extending westwards across the Pacific from the Southern East Pacific Rise, dissolved iron and manganese were shown by the GEOTRACES program to be transported halfway across the Pacific. Here, we report that particulate iron and manganese in the same plume also exceed background concentrations, even 4,000 km from the vent source. Both dissolved and particulate iron deepen by more than 350 m relative to 3He--a non-reactive tracer of hydrothermal input--crossing isopycnals. Manganese shows no similar descent. Individual plume particle analyses indicate that particulate iron occurs within low-density organic matrices, consistent with its slow sinking rate of 5-10 m yr-1. Chemical speciation and isotopic composition analyses reveal that particulate iron consists of Fe(III) oxyhydroxides, whereas dissolved iron consists of nanoparticulate Fe(III) oxyhydroxides and an organically complexed iron phase. The descent of plume-dissolved iron is best explained by reversible exchange onto slowly sinking particles, probably mediated by organic compounds binding iron. We suggest that in ocean regimes with high particulate iron loadings, dissolved iron fluxes may depend on the balance between stabilization in the dissolved phase and the reversibility of exchange onto sinking particles.

  4. Estimation of polycyclic aromatic hydrocarbon concentrations in the water column based on tissue residues in mussels and salmon: An equilibrium partitioning approach

    International Nuclear Information System (INIS)

    Neff, J.M.; Burns, W.A.

    1996-01-01

    Equilibrium partitioning was used to estimate concentrations of dissolved polycyclic aromatic hydrocarbons (PAHs) in the water column from PAH residues in tissues of mussels and juvenile pink salmon collected from coastal marine waters affected by the Exxon Valdez oil spill. Estimated concentrations were within factors of 2 to 5 for fish and 5 to 10 for mussels of average total dissolved and particulate PAHs measured in concurrent water samples. Temporal trends of estimated and measured water-column PAH concentrations were comparable. Water-column PAH concentrations estimated from residues in tissues of mussels (Mytilus trossulus) were higher than estimates based on residues in tissues of juvenile pink salmon (Oncorhynchus gorbuscha). Possible reasons for this difference include seasonal variations in mussel lipid content, differences in PAH uptake and depuration rates between fish and mussels, differences in how fish and mussels interact with particulate oil, and possible short exposure times for juvenile pink salmon. All of these factors may play a role. In any event, estimates of dissolved PAHs in the water column, based on PAH residues in either fish or mussel tissue, confirm that PAH concentrations generally did not exceed water quality standards for protection of marine life

  5. PREDICTION OF TOTAL DISSOLVED GAS EXCHANGE AT HYDROPOWER DAMS

    Energy Technology Data Exchange (ETDEWEB)

    Hadjerioua, Boualem [ORNL; Pasha, MD Fayzul K [ORNL; Stewart, Kevin M [ORNL; Bender, Merlynn [Bureau of Reclamation; Schneider, Michael L. [U.S. Army Corps of Engineers

    2012-07-01

    Total dissolved gas (TDG) supersaturation in waters released at hydropower dams can cause gas bubble trauma in fisheries resulting in physical injuries and eyeball protrusion that can lead to mortality. Elevated TDG pressures in hydropower releases are generally caused by the entrainment of air in spillway releases and the subsequent exchange of atmospheric gasses into solution during passage through the stilling basin. The network of dams throughout the Columbia River Basin (CRB) are managed for irrigation, hydropower production, flood control, navigation, and fish passage that frequently result in both voluntary and involuntary spillway releases. These dam operations are constrained by state and federal water quality standards for TDG saturation which balance the benefits of spillway operations designed for Endangered Species Act (ESA)-listed fisheries versus the degradation to water quality as defined by TDG saturation. In the 1970s, the United States Environmental Protection Agency (USEPA), under the federal Clean Water Act (Section 303(d)), established a criterion not to exceed the TDG saturation level of 110% in order to protect freshwater and marine aquatic life. The states of Washington and Oregon have adopted special water quality standards for TDG saturation in the tailrace and forebays of hydropower facilities on the Columbia and Snake Rivers where spillway operations support fish passage objectives. The physical processes that affect TDG exchange at hydropower facilities have been studied throughout the CRB in site-specific studies and routine water quality monitoring programs. These data have been used to quantify the relationship between project operations, structural properties, and TDG exchange. These data have also been used to develop predictive models of TDG exchange to support real-time TDG management decisions. These empirically based predictive models have been developed for specific projects and account for both the fate of spillway and

  6. Total dissolved gas prediction and optimization in RiverWare

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Kevin M. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Witt, Adam M. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Hadjerioua, Boualem [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

    2015-09-01

    Management and operation of dams within the Columbia River Basin (CRB) provides the region with irrigation, hydropower production, flood control, navigation, and fish passage. These various system-wide demands can require unique dam operations that may result in both voluntary and involuntary spill, thereby increasing tailrace levels of total dissolved gas (TDG) which can be fatal to fish. Appropriately managing TDG levels within the context of the systematic demands requires a predictive framework robust enough to capture the operationally related effects on TDG levels. Development of the TDG predictive methodology herein attempts to capture the different modes of hydro operation, thereby making it a viable tool to be used in conjunction with a real-time scheduling model such as RiverWare. The end result of the effort will allow hydro operators to minimize system-wide TDG while meeting hydropower operational targets and constraints. The physical parameters such as spill and hydropower flow proportions, accompanied by the characteristics of the dam such as plant head levels and tailrace depths, are used to develop the empirically-based prediction model. In the broader study, two different models are developed a simplified and comprehensive model. The latter model incorporates more specific bubble physics parameters for the prediction of tailrace TDG levels. The former model is presented herein and utilizes an empirically based approach to predict downstream TDG levels based on local saturation depth, spillway and powerhouse flow proportions, and entrainment effects. Representative data collected from each of the hydro projects is used to calibrate and validate model performance and the accuracy of predicted TDG uptake. ORNL, in conjunction with IIHR - Hydroscience & Engineering, The University of Iowa, carried out model adjustments to adequately capture TDG levels with respect to each plant while maintaining a generalized model configuration. Validation results

  7. Dissolved Fe across the Weddell Sea and Drake Passage: impact of DFe on nutrient uptake

    NARCIS (Netherlands)

    Klunder, M.B.; Laan, P.; de Baar, H.J.W.; Middag, R.; Neven, I.; Van Ooijen, J.

    2014-01-01

    This manuscript reports the first full depth distributions of dissolved iron (DFe) over a high-resolution Weddell Sea and Drake Passage transect. Very low dissolved DFe concentrations (0.01-0.1 nM range) were observed in the surface waters of the Weddell Sea, and within the Drake Passage polar

  8. Dissolved Fe across the Weddell Sea and Drake Passage : Impact of DFe on nutrient uptake

    NARCIS (Netherlands)

    Klunder, M. B.; Laan, P.; De Baar, H. J. W.; Middag, R.; Neven, I.; Van Ooijen, J.

    2014-01-01

    This manuscript reports the first full depth distributions of dissolved iron (DFe) over a high-resolution Weddell Sea and Drake Passage transect. Very low dissolved DFe concentrations (0.01-0.1 nM range) were observed in the surface waters of the Weddell Sea, and within the Drake Passage polar

  9. Diel changes in metal concentrations in a geogenically acidic river: Rio Agrio, Argentina

    Science.gov (United States)

    Parker, Stephen R.; Gammons, Christopher H.; Pedrozo, Fernando L.; Wood, Scott A.

    2008-12-01

    Rio Agrio in Patagonia, Argentina is a geogenically acidic stream that derives its low-pH waters from condensation of acidic gases near its headwaters on the flanks of the active Copahue Volcano. This study reports the results of three diel (24-h) water samplings in three different pH regimes (3.2, 4.4 and 6.3) along the river. Changes in the concentration and speciation of Fe dominated the diel chemical changes at all three sites, although the timing and intensity of these cycles were different in each reach. At the two acidic sampling sites, total dissolved Fe and dissolved Fe(III) concentrations decreased during the day and increased at night, whereas dissolved Fe(II) showed the reverse pattern. These cycles are explained by Fe(III) photoreduction, as well as enhanced rates of precipitation of hydrous ferric oxide (HFO) during the warm afternoon hours. A strong correlation was observed between Fe(III) and As at the furthest upstream (pH 3.2) site, most likely due to co-precipitation of As with HFO. At the downstream (pH 6.3) location, Fe(II) concentrations increased at night, as did concentrations of rare earth elements and dissolved Al. Photoreduction does not appear to be an important process at pH 6.3, although it may be indirectly responsible for the observed diel cycle of Fe(II) due to advection of photochemically produced Fe(II) from acidic upstream waters. The results of this study of a naturally-acidic river are very similar to diel trends recently obtained from mining-impacted streams receiving acid rock drainage. The results are also used to explore the link between geochemistry and microbiology in acidic eco-systems. For example, Fe(III) photoreduction produces chemical potential energy (in the form of metastable Fe 2+) that helps support the bacterial community in this unique extreme environment.

  10. Dissolved Nutrients from Submarine Groundwater in Flic en Flac ...

    African Journals Online (AJOL)

    through a thin blanket of unconsolidated sediment through a fracture system and is concentrated along the ... The lagoon is subjected to diffuse SGD flows which may contribute to its high dissolved nutrient values. ... coastal zone management and similar tropical volcanic lagoonal systems. INTRODUCTION. Lagoons and ...

  11. Annual variability in the radiocarbon age and source of dissolved CO2 in a peatland stream

    International Nuclear Information System (INIS)

    Garnett, Mark H.; Dinsmore, Kerry J.; Billett, Michael F.

    2012-01-01

    Radiocarbon dating has the capacity to significantly improve our understanding of the aquatic carbon cycle. In this study we used a new passive sampler to measure the radiocarbon ( 14 C) and stable carbon (δ 13 C) isotopic composition of dissolved CO 2 for the first time in a peatland stream throughout a complete year (May 2010–June 2011). The in-stream sampling system collected time-integrated samples of CO 2 continuously over approximately 1 month periods. The rate of CO 2 trapping was proportional to independently measured streamwater CO 2 concentrations, demonstrating that passive samplers can be used to estimate the time-averaged dissolved CO 2 concentration of streamwater. While there was little variation and no clear trend in δ 13 CO 2 values (suggesting a consistent CO 2 source), we found a clear temporal pattern in the 14 C concentration of dissolved CO 2 . The 14 C age of CO 2 varied from 707 ± 35 to 1210 ± 39 years BP, with the youngest CO 2 in the autumn and oldest in spring/early summer. Mean stream discharge and 14 C content of dissolved CO 2 were positively correlated. We suggest that the observed pattern in the 14 C content of dissolved CO 2 reflects changes in its origin, with older carbon derived from deeper parts of the peat profile contributing proportionally more gaseous carbon during periods of low stream flow. - Highlights: ► Dissolved CO 2 was sampled from a peatland stream and radiocarbon dated. ► Samples collected using new passive sampler are suitable for integrated monthly samples. ► Age of CO 2 ranged from 707 to 1210 years old and seasonal pattern is observed. ► Age correlated with discharge and reflected source of dissolved CO 2 . ► Study highlights the value of 14 C analysis and potential of new method.

  12. Seasonal variation, flux estimation, and source analysis of dissolved emerging organic contaminants in the Yangtze Estuary, China.

    Science.gov (United States)

    Zhao, Heng; Cao, Zhen; Liu, Xue; Zhan, Yi; Zhang, Jing; Xiao, Xi; Yang, Yi; Zhou, Junliang; Xu, Jiang

    2017-12-15

    The occurrence and seasonal variation of 24 dissolved emerging organic contaminants in the Yangtze Estuary were studied, including 12 non-antibiotic pharmaceuticals, seven sulfonamides, two macrolides and three chloramphenicols. Sulfadiazine, erythromycin, thiamphenicol and paracetamol were the primary contaminants in sulfonamides, macrolides, chloramphenicols and non-antibiotic pharmaceutical groups, respectively. Compared to the concentrations at Datong, chloramphenicols at Xuliujing were significantly higher in autumn and winter, while macrolides were lower in spring. Based on the flux estimation, approximately 37.1 tons of sulfonamides, 17.4 tons of macrolides, 79.2 tons of chloramphenicols and 14.1 tons of non-antibiotic pharmaceuticals were discharged into the Yangtze Estuary from June 2013 to May 2014. However, the total flux from the Huangpu River only represented 5% of the total. The pharmaceutical sources were speculated on by analyzing the seasonal variations in pharmaceutical concentrations and fluxes at various sites. Both environmental and social factors might affect the fluxes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Determination of the partition coefficient between dissolved organic carbon and seawater using differential equilibrium kinetics.

    Science.gov (United States)

    Kim, Du Yung; Kwon, Jung-Hwan

    2018-05-04

    Because the freely dissolved fraction of highly hydrophobic organic chemicals is bioavailable, knowing the partition coefficient between dissolved organic carbon and water (K DOCw ) is crucial to estimate the freely dissolved fraction from the total concentration. A kinetic method was developed to obtain K DOCw that required a shorter experimental time than equilibrium methods. The equilibrium partition coefficients of four polychlorinated biphenyls (PCBs) (2,4,4'-trichlorobiphenyl (PCB 28), 2,2',3,5'-tetrachlorobiphenyl (PCB 44), 2,2',4,5,5'-pentachlorobiphenyl (PCB 101), and 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153)) between dissolved organic carbon and seawater (K DOCsw ) were determined using seawater samples from the Korean coast. The log K DOCsw values of PCB 28 were measured by equilibrating PCB 28, the least hydrophobic congener, with seawater samples, and the values ranged from 6.60 to 7.20. For the more hydrophobic PCBs (PCB 44, PCB 101, and PCB 153), kinetic experiments were conducted to determine the sorption rate constants (k 2 ) and their log K DOCsw values were obtained by comparing their k 2 with that of PCB 28. The calculated log K DOCsw values were 6.57-7.35 for PCB 44, 6.23-7.44 for PCB 101, and 6.35-7.73 for PCB 153. The validity of the proposed method was further confirmed using three less hydrophobic polycyclic aromatic hydrocarbons. This kinetic method shortened the experimental time to obtain the K DOCsw values of the more hydrophobic PCBs, which did not reach phase equilibrium. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Water analysis from wells in Ezeiza and surrounding areas. Dissolved uranium

    International Nuclear Information System (INIS)

    Santagata, D.M.; Arguelles, Maria G.; Barbaro, Nestor O.

    2006-01-01

    In order to give an answer to the different social sectors, we sampled water from previously existing wells that reaches the Puelche aquifer. The uranium concentration was determined in these samples to obtain a preliminary checkup of water quality situation. For the analysis we considered the samples obtained inside the CAE as well as those sampled in the surrounding areas as Monte Grande, Claypole and Burzaco. The results show a correlation between the amount of dissolved salts and the presence of dissolved uranium. (author) [es

  15. PROCESS OF DISSOLVING ZIRCONIUM ALLOYS

    Science.gov (United States)

    Shor, R.S.; Vogler, S.

    1958-01-21

    A process is described for dissolving binary zirconium-uranium alloys where the uranium content is about 2%. In prior dissolution procedures for these alloys, an oxidizing agent was added to prevent the precipitation of uranium tetrafluoride. In the present method complete dissolution is accomplished without the use of the oxidizing agent by using only the stoichiometric amount or slight excess of HF required by the zirconium. The concentration of the acid may range from 2M to 10M and the dissolution is advatageously carried out at a temperature of 80 deg C.

  16. Enhanced dissolved lipid production as a response to the sea surface warming

    Science.gov (United States)

    Novak, Tihana; Godrijan, Jelena; Pfannkuchen, Daniela Marić; Djakovac, Tamara; Mlakar, Marina; Baricevic, Ana; Tanković, Mirta Smodlaka; Gašparović, Blaženka

    2018-04-01

    The temperature increase in oceans reflects on marine ecosystem functioning and surely has consequences on the marine carbon cycle and carbon sequestration. In this study, we examined dissolved lipid, lipid classes and dissolved organic carbon (DOC) production in the northern Adriatic Sea, isolated diatom Chaetoceros pseudocurvisetus batch cultures grown in a wide temperature range (10-30 °C) and in contrasting nutrient regimes, phosphorus (P)-depleted and P-replete conditions. Additionally, lipids and DOC were analyzed in the northern Adriatic (NA) in two stations characterized with different P availability, occupied from February to August 2010 that covered a temperature range from 9.3 to 31.1 °C. To gain insight into factors governing lipid and lipid classes' production in the NA, apart from temperature (T), Chlorophyll a, phytoplankton community abundance and structure, nutrient concentrations were measured together with hydrographic parameters. We found enhanced accumulation of dissolved lipids, particulary glycolipids, with increasing T, especially during the highest in situ temperature. The effect of T on enhanced dissolved lipid release is much more pronounced under P-deplete conditions indicating that oligotrophic regions might be more vulnerable to T rise. Temperature between 25 and 30 °C is a threshold T range for C. pseudocurvisetus, at which a significant part of lipid production is directed toward the dissolved phase. Unlike monocultures, there are multiple factors influencing produced lipid composition, distribution and cycling in the NA that may counteract the T influence. The possible role of enhanced dissolved lipid concentration for carbon sequestration at elevated T is discussed. On the one hand, lipids are buoyant and do not sink, which enhances their retention at the surface layer. In addition, they are surface active, and therefore prone to adsorb on sinking particles, contributing to the C sequestration.

  17. A Novel Method for Analysis of Dissolved Inorganic Carbon Concentration and δ13C by Cavity Ring-Down Spectroscopy

    Science.gov (United States)

    Smith, E.; Gonneea, M. E.; Boze, L. G.; Casso, M.; Pohlman, J.

    2017-12-01

    Dissolved inorganic carbon (DIC) is the largest pool of carbon in the oceans and is where about half of anthropogenic carbon dioxide (CO2) emissions are being sequestered. Determining the concentration and stable carbon isotopic content (δ13C) of DIC allows us to delineate carbon sources that contribute to marine DIC. A simple and reliable method for measuring DIC concentration and δ13C can be used to apportion contributions from external sources and identify effects from biogeochemical reactions that contribute or remove DIC. The U.S. Geological Survey has developed a discrete sample analysis module (DSAM) that interfaces to a Picarro G-2201i cavity ring-down spectrometer (CRDS, Picarro Inc.) to analyze CO2 and methane concentrations and δ13C from discrete gas samples. In this study, we adapted the USGS DSAM-CRDS analysis system to include an AutoMate prep device (Automate FX, Inc.) for analysis of DIC concentration and δ13C from aqueous samples. The Automate prep device was modified to deliver CO2 extracted from DIC to the DSAM, which conditions and transfers the gas to the CRDS. LabVIEW software (National Instruments) triggers the Automate Prep device, controls the DSAM and collects data from the CRDS. CO2 mass concentration data are obtained by numerical integration of the CO2 volumetric concentrations output by the CRDS and subsequent comparison to standard materials. CO2 carbon isotope values from the CRDS (iCO2) are converted to δ13C values using a slope and offset correction calibration procedure. The system design and operation was optimized using sodium bicarbonate (NaHCO3) standards and a certified reference material. Surface water and pore water samples collected from Sage Lot Pond, a salt marsh in Cape Cod MA, have been analyzed for concentration by coulometry and δ13C by isotope ratio mass spectrometry and will be used to validate the DIC-DSAM-CRDS method for field applications.

  18. Beaver ponds increase methylmercury concentrations in Canadian shield streams along vegetation and pond-age gradients.

    Science.gov (United States)

    Roy, Virginie; Amyot, Marc; Carignan, Richard

    2009-08-01

    Beaver impoundments flood forested areas and may be important production sites for methylmercury (MeHg) because of the resulting enhanced microbial activity and oxygen depletion. The influence of 17 beaver impoundments on streamwater chemistry (total mercury (THg), MeHg, nutrients, cations, and anions)] was investigated by sampling sites located along vegetation and pond-age gradients in southwestern Quebec (Canada). Recently inundated beaver ponds (beaver ponds as suggested by depletions of dissolved oxygen, sulfate and nitrite-nitrate concentrations, and increases in nutrients (e.g., dissolved organic carbon, total phosphorus, and total nitrogen) in outlets compared to inlets. Acidic waters at coniferous sites may have stimulated more MeHg production than in mixed woodland regions. Lower methylation efficiencies in older ponds (> 20 years old) may be due to the degradation of less labile organic matter as ponds age. Beavers actively alter watersheds by building impoundments, and our findings indicate that this landscape disturbance may be a significant source of MeHg to downstream water bodies.

  19. Methanethiol Concentrations and Sea-Air Fluxes in the Subarctic NE Pacific Ocean

    Science.gov (United States)

    Kiene, R. P.; Williams, T. E.; Esson, K.; Tortell, P. D.; Dacey, J. W. H.

    2017-12-01

    Exchange of volatile organic sulfur from the ocean to the atmosphere impacts the global sulfur cycle and the climate system and is thought to occur mainly via the gas dimethylsulfide (DMS). DMS is produced during degradation of the abundant phytoplankton osmolyte dimethylsulfoniopropionate (DMSP) but bacteria can also convert dissolved DMSP into the sulfur gas methanethiol (MeSH). MeSH has been difficult to measure in seawater because of its high chemical and biological reactivity and, thus, information on MeSH concentrations, distribution and sea-air fluxes is limited. We measured MeSH in the northeast subarctic Pacific Ocean in July 2016, along transects with strong phytoplankton abundance gradients. Water samples obtained with Niskin bottles were analyzed for MeSH by purge-and-trap gas chromatography. Depth profiles showed that MeSH concentrations were high near the surface and declined with depth. Surface waters (5 m depth) had an average MeSH concentration of 0.75 nM with concentrations reaching up to 3nM. MeSH concentrations were correlated (r = 0.47) with microbial turnover of dissolved DMSP which ranged up to 236 nM per day. MeSH was also correlated with total DMSP (r = 0.93) and dissolved DMS (r = 0.63), supporting the conclusion that DMSP was a major precursor of MeSH. Surface water MeSH:DMS concentration ratios averaged 0.19 and ranged up to 0.50 indicating that MeSH was a significant fraction of the volatile sulfur pool in surface waters. Sea-air fluxes of MeSH averaged 15% of the combined DMS+MeSH flux, therefore MeSH contributed an important fraction of the sulfur emitted to the atmosphere from the subarctic NE Pacific Ocean.

  20. Characteristics and sources analysis of riverine chromophoric dissolved organic matter in Liaohe River, China.

    Science.gov (United States)

    Shao, Tiantian; Song, Kaishan; Jacinthe, Pierre-Andre; Du, Jia; Zhao, Ying; Ding, Zhi; Guan, Ying; Bai, Zhang

    2016-12-01

    Chromophoric dissolved organic matter (CDOM) in riverine systems can be affected by environmental conditions and land-use, and thus could provide important information regarding human activities in surrounding landscapes. The optical properties of water samples collected at 42 locations across the Liaohe River (LHR, China) watershed were examined using UV-Vis and fluorescence spectroscopy to determine CDOM characteristics, composition and sources. Total nitrogen (TN) and total phosphorus (TP) concentrations at all sampling sites exceeded the GB3838-2002 (national quality standards for surface waters, China) standard for Class V waters of 2.0 mg N/L and 0.4 mg P/L respectively, while trophic state index (TSI M ) indicated that all the sites investigated were mesotrophic, 64% of which were eutrophic at the same time. Redundancy analysis showed that total suspended matter (TSM), dissolved organic carbon (DOC), and turbidity had a strong correlation with CDOM, while the other parameters (Chl a, TN, TP and TSI M ) exhibited weak correlations with CDOM absorption. High spectral slope values and low SUVA254 (the specific UV absorption) values indicated that CDOM in the LHR was primarily comprised of low molecular weight organic substances. Analysis of excitation-emission matrices contour plots showed that CDOM in water samples collected from upstream locations exhibited fulvic-acid-like characteristics whereas protein-like substances were most likely predominant in samples collected in estuarine areas and downstream from large cities. These patterns were interpreted as indicative of water pollution from urban and industrial activities in several downstream sections of the LHR watershed.

  1. Origin and Evolution of Reactive and Noble Gases Dissolved in Matrix Pore Water

    Energy Technology Data Exchange (ETDEWEB)

    Eichinger, F. [Hydroisotop GmbH, Schweitenkirchen (Germany); Rock-Water Interaction, Institute of Geological Sciences, University of Bern, Bern (Switzerland); Waber, H. N. [Rock-Water Interaction, Institute of Geological Sciences, University of Bern, Bern (Switzerland); Smellie, J. A.T. [Conterra AB, Stockholm (Sweden)

    2013-07-15

    Reactive and noble gases dissolved in matrix pore water of low permeable crystalline bedrock were successfully extracted and characterized for the first time based on drillcore samples from the Olkiluoto investigation site (SW Finland). Interaction between matrix pore water and fracture groundwater occurs predominately by diffusion. Changes in the chemical and isotopic composition of gases dissolved in fracture groundwater are transmitted and preserved in the pore water. Absolute concentrations, their ratios and the stable carbon isotope signature of hydrocarbon gases dissolved in pore water give valuable indications about the evolution of these gases in the nearby flowing fracture groundwaters. Inert noble gases dissolved in matrix pore water and their isotopes combined with their in situ production and accumulation rates deliver information about the residence time of pore water. (author)

  2. Remote Sensing of Dissolved Oxygen and Nitrogen in Water Using Raman Spectroscopy

    Science.gov (United States)

    Ganoe, Rene; DeYoung, Russell J.

    2013-01-01

    The health of an estuarine ecosystem is largely driven by the abundance of dissolved oxygen and nitrogen available for maintenance of plant and animal life. An investigation was conducted to quantify the concentration of dissolved molecular oxygen and nitrogen in water by means of Raman spectroscopy. This technique is proposed for the remote sensing of dissolved oxygen in the Chesapeake Bay, which will be utilized by aircraft in order to survey large areas in real-time. A proof of principle system has been developed and the specifications are being honed to maximize efficiency for the final application. The theoretical criteria of the research, components of the experimental system, and key findings are presented in this report

  3. Influence of salinity and dissolved organic carbon on acute Cu toxicity to the rotifer Brachionus plicatilis.

    Science.gov (United States)

    Cooper, Christopher A; Tait, Tara; Gray, Holly; Cimprich, Giselle; Santore, Robert C; McGeer, James C; Wood, Christopher M; Smith, D Scott

    2014-01-21

    Acute copper (Cu) toxicity tests (48-h LC50) using the euryhaline rotifer Brachionus plicatilis were performed to assess the effects of salinity (3, 16, 30 ppt) and dissolved organic carbon (DOC, ∼ 1.1, ∼ 3.1, ∼ 4.9, ∼ 13.6 mg C L(-1)) on Cu bioavailability. Total Cu was measured using anodic stripping voltammetry, and free Cu(2+) was measured using ion-selective electrodes. There was a protective effect of salinity observed in all but the highest DOC concentrations; at all other DOC concentrations the LC50 value was significantly higher at 30 ppt than at 3 ppt. At all salinities, DOC complexation significantly reduced Cu toxicity. At higher concentrations of DOC the protective effect increased, but the increase was less than expected from a linear extrapolation of the trend observed at lower concentrations, and the deviation from linearity was greatest at the highest salinity. Light-scattering data indicated that salt induced colloid formation of DOC could be occurring under these conditions, thereby decreasing the number of available reactive sites to complex Cu. When measurements of free Cu across DOC concentrations at each individual salinity were compared, values were very similar, even though the total Cu LC50 values and DOC concentrations varied considerably. Furthermore, measured free Cu values and predicted model values were comparable, highlighting the important link between the concentration of bioavailable free Cu and Cu toxicity.

  4. Mercury concentration in black flies Simulium spp. (Diptera, Simuliidae) from soft-water streams in Ontario, Canada

    International Nuclear Information System (INIS)

    Harding, K.M.; Gowland, J.A.; Dillon, P.J.

    2006-01-01

    Total Hg in Simulium spp. (Diptera, Simuliidae) was measured in 17 soft-water streams in the District of Muskoka and Haliburton County (Ontario, Canada) during 2003 and 2004. Black flies contained 0.07-0.64 μg/g total Hg (dry weight). The methylmercury concentration was measured in 6 samples of the 17, and ranged from 58% to 93% of total Hg. The concentration of total Hg is much higher than has been found in other filter feeding insects, and represents a significant potential source of Hg to fish. Mercury concentrations in Simulium spp. at different sites were strongly positively correlated with dissolved organic carbon, and the proportion of land within each catchment that was wetland. There was also a strong negative correlation with pH. By examining Hg concentration in filter feeding insects we have found a significant entry point for Hg and MeHg into the food web. - Accumulation of total mercury by black fly larvae is affected by stream pH, DOC and wetland area in the stream catchment

  5. Mercury concentration in black flies Simulium spp. (Diptera, Simuliidae) from soft-water streams in Ontario, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Harding, K.M. [Trent University, 1600 West Bank Drive, Peterborough, ON K9J 7B8 (Canada); Gowland, J.A. [Trent University, 1600 West Bank Drive, Peterborough, ON K9J 7B8 (Canada); Dillon, P.J. [Trent University, 1600 West Bank Drive, Peterborough, ON K9J 7B8 (Canada)]. E-mail: pdillon@trentu.ca

    2006-10-15

    Total Hg in Simulium spp. (Diptera, Simuliidae) was measured in 17 soft-water streams in the District of Muskoka and Haliburton County (Ontario, Canada) during 2003 and 2004. Black flies contained 0.07-0.64 {mu}g/g total Hg (dry weight). The methylmercury concentration was measured in 6 samples of the 17, and ranged from 58% to 93% of total Hg. The concentration of total Hg is much higher than has been found in other filter feeding insects, and represents a significant potential source of Hg to fish. Mercury concentrations in Simulium spp. at different sites were strongly positively correlated with dissolved organic carbon, and the proportion of land within each catchment that was wetland. There was also a strong negative correlation with pH. By examining Hg concentration in filter feeding insects we have found a significant entry point for Hg and MeHg into the food web. - Accumulation of total mercury by black fly larvae is affected by stream pH, DOC and wetland area in the stream catchment.

  6. Determination of Anionic Detergent Concentration of Karasu Stream in Sinop (Turkey

    Directory of Open Access Journals (Sweden)

    Ayşe Gündoğdu

    2018-02-01

    Full Text Available The study was achieved between May 2014 and April 2015 at the Karasu Creek located in the province of Sinop. It was conducted to determine anionic detergent pollution and some physicochemical properties (pH, temperature, conductivity, salinity, dissolved oxygen, total hardness, chemical oxygen demand, phosphate PO4-3, total nitrogen. The anionic detergent concentration of the stations was determined on a monthly basis. Seasonally averaged values of the anionic detergent was measured as the highest value in the autumn season. The lowest values of anionic detergent were found in stations in winter and spring. The increase in the concentration of anionic detergent is caused by population growth in residential areas, increased agricultural activities and rains, and that chemicals move to riverbed from terrestrial areas with rain water.

  7. Role of dissolved and particulate cadmium in the accumulation of cadmium in cultured oysters (Crassostrea gigas)

    Energy Technology Data Exchange (ETDEWEB)

    Lekhi, Priyanka [Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z4 (Canada)], E-mail: anka.lekhi@ubc.ca; Cassis, D. [Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC V6T 1Z4 (Canada); Pearce, C.M. [Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC V9T 6N7 (Canada); Ebell, N. [Odyssey Shellfish Ltd., Nanoose Bay, BC V0R 9G0 (Canada); Maldonado, M.T. [Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC V6T 1Z4 (Canada); Orians, K.J. [Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z4 (Canada); Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC V6T 1Z4 (Canada)

    2008-04-15

    Pacific oysters (Crassostrea gigas) collected on the coast of British Columbia, Canada have occasionally shown cadmium (Cd) concentrations at or above 2 {mu}g g{sup -1} (wet weight), which has resulted in the loss of some international markets. This study investigated the source and transfer of Cd to oysters by focusing on the role of dissolved and particulate Cd in seawater. Parameters monitored for 1 year at two oyster farm sites on Vancouver Island included: oyster tissue mass and shell length, Cd in oysters, dissolved Cd, particulate Cd, temperature and salinity. Results show that dissolved Cd was the main source of Cd to the oysters and that Cd was mainly concentrated in the gut tissues. A seasonal trend was observed in Cd in oysters, in which levels were lowest during periods of higher temperatures. Results also indicate that the local oceanographic inputs and sediment diagenesis directly affect dissolved Cd and thereby influence the Cd levels in oysters. Particulate matter was not found to be a source of Cd in oysters, and was actually negatively correlated. This was likely due to the uptake of dissolved Cd by phytoplankton and the effect of phytoplankton on oyster tissue mass.

  8. Role of dissolved and particulate cadmium in the accumulation of cadmium in cultured oysters (Crassostrea gigas)

    International Nuclear Information System (INIS)

    Lekhi, Priyanka; Cassis, D.; Pearce, C.M.; Ebell, N.; Maldonado, M.T.; Orians, K.J.

    2008-01-01

    Pacific oysters (Crassostrea gigas) collected on the coast of British Columbia, Canada have occasionally shown cadmium (Cd) concentrations at or above 2 μg g -1 (wet weight), which has resulted in the loss of some international markets. This study investigated the source and transfer of Cd to oysters by focusing on the role of dissolved and particulate Cd in seawater. Parameters monitored for 1 year at two oyster farm sites on Vancouver Island included: oyster tissue mass and shell length, Cd in oysters, dissolved Cd, particulate Cd, temperature and salinity. Results show that dissolved Cd was the main source of Cd to the oysters and that Cd was mainly concentrated in the gut tissues. A seasonal trend was observed in Cd in oysters, in which levels were lowest during periods of higher temperatures. Results also indicate that the local oceanographic inputs and sediment diagenesis directly affect dissolved Cd and thereby influence the Cd levels in oysters. Particulate matter was not found to be a source of Cd in oysters, and was actually negatively correlated. This was likely due to the uptake of dissolved Cd by phytoplankton and the effect of phytoplankton on oyster tissue mass

  9. Influence of starter culture on total free aminoacids concentration during ripening of Krk cheese

    Directory of Open Access Journals (Sweden)

    Biljana Radeljević

    2013-03-01

    Full Text Available The aim of this study was to determine the influence of microbial (commercial starter culture on concentration of total free amino groups (amino acids in cheeses in different ripening stages. Free amino groups were determined by reaction with ninhydrin with cadmium (Cd in the water soluble cheese extract, and were expressed as the concentration of leucine in cheese dry matter. Changes in concentration of total free amino acids during cheese ripening (0th, 30th, 60th, 90th and 120th day were monitored. In water soluble extracts of cheese, the presence of free NH2 groups in all ripening stages was detected, which means smaller peptides and amino acids, whose concentration significantly (P<0.01 increased during ripening. Cheeses produced with and without microbial culture resulted in statistically significant differences (P<0.01 in content amino acids free on the 90th and 120th day of ripening. Cd - ninhydrin method was found to be suitable for cheese ripening monitoring, as well as for determination of the differences in mature characteristics of cheeses, depending on the production process.

  10. Dissolved aluminium in the surface microlayer of the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Narvekar, P.V.; Singbal, S.Y.S.

    Measurements of dissolved aluminium (Al) in surface microlayer (SML) samples from the eastern Arabian Sea during the southwest (summer) and northwast (winter) monsoon periods have revealed much higher concentrations (23-657 nmol kg sup(-1)) than...

  11. Electrochemical characterization of doped diamond-coated carbon fibers at different boron concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, E.C. [INPE, CP 515, Sao Jose dos Campos, SP 12201-970 (Brazil)]. E-mail: erica@las.inpe.br; Diniz, A.V. [INPE, CP 515, Sao Jose dos Campos, SP 12201-970 (Brazil); Trava-Airoldi, V.J. [INPE, CP 515, Sao Jose dos Campos, SP 12201-970 (Brazil); Ferreira, N.G. [CTA-Divisao de Materiais, Sao Jose dos Campos, SP 12228-904 (Brazil)

    2005-08-01

    Doped diamond films have been deposited on carbon fibers (felt) obtained from polyacrylonitrile at different levels of boron doping. For a successful coating of the fibers, an ultrasonic pretreatment in a bath of diamond powder dissolved in hexane was required. Films were grown on both sample sides, simultaneously, by hot filament-assisted chemical vapour deposition technique at 750 deg. C from a 0.5% H{sub 2}/CH{sub 4} mixture at a total pressure of 6.5 x 10{sup 3} Pa. Boron was obtained from H{sub 2} forced to pass through a bubbler containing B{sub 2}O{sub 3} dissolved in methanol. The doping level studied corresponds to films with acceptor concentrations in the range of 6.5 x 10{sup 18} to 1.5 x 10{sup 21} cm{sup -} {sup 3}, obtained from Mott-Schottky plots. Scanning electron microscopy analyses evidenced fibers totally covered with high quality polycrystalline boron-doped diamond film, also confirmed by Raman spectroscopy spectra. Diamond electrodes grown on carbon fibers demonstrated similar electrochemical behavior obtained from films on Si substrate, for ferri/ferrocyanide redox couple as a function of boron content. The boron content influences electrochemical surface area. A lower boron concentration provides a higher growth rate that results in a higher surface area.

  12. Dissolved Carbon Fluxes During the 2017 Mississippi River Flood

    Science.gov (United States)

    Reiman, J. H.; Xu, Y. J.

    2017-12-01

    The Mississippi River drains approximately 3.2 million square kilometres of land and discharges about 680 cubic kilometres of water into the Northern Gulf of Mexico annually, acting as a significant medium for carbon transport from land to the ocean. A few studies have documented annual carbon fluxes in the river, however it is unclear whether floods can create riverine carbon pulses. Such information is critical in understanding the effects that extreme precipitation events may have on carbon transport under the changing climate. We hypothesize that carbon concentration and mass loading will increase in response to an increase in river discharge, creating a carbon pulse, and that the source of carbon varies from river rising to falling due to terrestrial runoff processes. This study investigated dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) loadings during the 2017 Mississippi River early-summer flood. Water samples were taken from the Mississippi River at Baton Rouge on the rising limb, crest, and falling limb of the flood. All samples were analysed for concentrations of DOC, DIC, and their respective isotopic signature (δ13C). Partial pressure of carbon dioxide (pCO2) was also recorded in the field at each sampling trip. Additionally, the water samples were analysed for nutrients, dissolved metals, and suspended solids, and in-situ measurements were made on water temperature, pH, dissolved oxygen, and specific conductance. The preliminary findings suggest that carbon species responded differently to the flood event and that δ13C values were dependent on river flood stage. This single flood event transported a large quantity of carbon, indicating that frequent large pulses of riverine carbon should be expected in the future as climate change progresses.

  13. Free and total urinary phthalate metabolite concentrations among pregnant women from the Healthy Baby Cohort (HBC), China.

    Science.gov (United States)

    Zhu, Yingshuang; Wan, Yanjian; Li, Yuanyuan; Zhang, Bin; Zhou, Aifen; Cai, Zongwei; Qian, Zhengmin; Zhang, Chuncao; Huo, Wenqian; Huang, Kai; Hu, Jie; Cheng, Lu; Chang, Huailong; Huang, Zheng; Xu, Bing; Xia, Wei; Xu, Shunqing

    2016-03-01

    Total urinary phthalate metabolites (the free plus glucuronidated forms) have been frequently measured in the general population. However, data are limited on the free forms which may be more bioactive, especially for sensitive population such as pregnant women. Here the data gap was addressed by measuring concentrations of free and total forms of six phthalate metabolites in 293 urine samples from pregnant women at delivery, who were randomly selected from the prospective Healthy Baby Cohort (HBC), China. We observed detectable concentrations of the total amount of phthalate metabolites in all urine samples. The geometric mean (GM) urinary concentrations of free and total mono-butyl phthalate (MBP) (5.20, 54.49ng/mL) were the highest, followed by mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP) (4.52, 7.27ng/mL). For most of phthalate metabolites, urinary concentrations were significantly higher in women who were nulliparous. Significantly higher concentrations of mono-ethyl phthalate (MEP) and mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) were found in women who had higher educational level. To our knowledge, this is the first study to report the free and total forms of phthalate metabolites among pregnant women in China. The results suggest that exposure characteristics may be related to parity and education. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. New, rapid method to measure dissolved silver concentration in silver nanoparticle suspensions by aggregation combined with centrifugation

    International Nuclear Information System (INIS)

    Dong, Feng; Valsami-Jones, Eugenia; Kreft, Jan-Ulrich

    2016-01-01

    It is unclear whether the antimicrobial activities of silver nanoparticles (AgNPs) are exclusively mediated by the release of silver ions (Ag"+) or, instead, are due to combined nanoparticle and silver ion effects. Therefore, it is essential to quantify dissolved Ag in nanosilver suspensions for investigations of nanoparticle toxicity. We developed a method to measure dissolved Ag in Ag"+/AgNPs mixtures by combining aggregation of AgNPs with centrifugation. We also describe the reproducible synthesis of stable, uncoated AgNPs. Uncoated AgNPs were quickly aggregated by 2 mM Ca"2"+, forming large clusters that could be sedimented in a low-speed centrifuge. At 20,100g, the sedimentation time of AgNPs was markedly reduced to 30 min due to Ca"2"+-mediated aggregation, confirmed by the measurements of Ag content in supernatants with graphite furnace atomic absorption spectrometry. No AgNPs were detected in the supernatant by UV–Vis absorption spectra after centrifuging the aggregates. Our approach provides a convenient and inexpensive way to separate dissolved Ag from AgNPs, avoiding long ultracentrifugation times or Ag"+ adsorption to ultrafiltration membranes.

  15. New, rapid method to measure dissolved silver concentration in silver nanoparticle suspensions by aggregation combined with centrifugation

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Feng, E-mail: fengdongub@gmail.com [University of Birmingham, Institute of Microbiology and Infection, School of Biosciences (United Kingdom); Valsami-Jones, Eugenia [University of Birmingham, School of Geography, Earth and Environmental Sciences (United Kingdom); Kreft, Jan-Ulrich [University of Birmingham, Institute of Microbiology and Infection, School of Biosciences (United Kingdom)

    2016-09-15

    It is unclear whether the antimicrobial activities of silver nanoparticles (AgNPs) are exclusively mediated by the release of silver ions (Ag{sup +}) or, instead, are due to combined nanoparticle and silver ion effects. Therefore, it is essential to quantify dissolved Ag in nanosilver suspensions for investigations of nanoparticle toxicity. We developed a method to measure dissolved Ag in Ag{sup +}/AgNPs mixtures by combining aggregation of AgNPs with centrifugation. We also describe the reproducible synthesis of stable, uncoated AgNPs. Uncoated AgNPs were quickly aggregated by 2 mM Ca{sup 2+}, forming large clusters that could be sedimented in a low-speed centrifuge. At 20,100g, the sedimentation time of AgNPs was markedly reduced to 30 min due to Ca{sup 2+}-mediated aggregation, confirmed by the measurements of Ag content in supernatants with graphite furnace atomic absorption spectrometry. No AgNPs were detected in the supernatant by UV–Vis absorption spectra after centrifuging the aggregates. Our approach provides a convenient and inexpensive way to separate dissolved Ag from AgNPs, avoiding long ultracentrifugation times or Ag{sup +} adsorption to ultrafiltration membranes.

  16. Chromophoric Dissolved Organic Matter in Southwestern Greenland Lakes

    Science.gov (United States)

    Osburn, C. L.; Giles, M. E.; Underwood, G. J. C.

    2014-12-01

    Dissolved organic matter (DOM) is an important property of Arctic lake ecosystems, originating from allochthonous inputs from catchments and autochthonous production by plankton in the water column. Little is known about the quality of DOM in Arctic lakes that lack substantial inputs from catchments and such lakes are abundant in southwestern Greenland. Colored dissolved organic matter (CDOM), the fraction that absorbs ultraviolet (UV) and visible light, is the controlling factor for the optical properties of many surface waters and as well informs on the quality of DOM. We examined the quality of CDOM in 21 lakes in southwestern Greenland, from the ice sheet to the coast, as part of a larger study examining the role of DOM in regulating microbial communities in these lakes. DOM was size fractioned and absorbance and fluorescence was measured on each size fraction, as well as on bulk DOM. The specific ultraviolet absorbance (SUVA) at 254 nm (SUVA254), computed by normalizing absorption (a254) to dissolved organic carbon (DOC) concentration, provided an estimate of the aromatic carbon content of DOM. SUVA values were generally CDOM fluorescence was used to determine the relative abundance of allochthonous and autochthonous DOM in all size fractions. Younger lakes near the ice sheet and lakes near the coast had lower amounts of CDOM and appeared more microbial in quality. However, lakes centrally located between the ice sheet and the coast had the highest CDOM concentrations and exhibited strong humic fluorescence. Overall distinct differences in CDOM quality were observed between lake locations and among DOM size fractions.

  17. Dynamics of Total Microcystin LR Concentration in Three Subtropical Hydroelectric Generation Reservoirs in Uruguay, South America.

    Science.gov (United States)

    González-Piana, Mauricio; Fabián, Daniel; Piccardo, Andrea; Chalar, Guillermo

    2017-10-01

    This study analyzed the temporal dynamics of total microcystin LR concentrations between the years of 2012 and 2015 in the Bonete, Baygorria and Palmar hydroelectric generation reservoirs in the central region of the Negro River, Uruguay. The three reservoirs showed differents total microcystin LR concentration, with no significant differences among them. Over 20 sampling dates, the three reservoirs exhibited total microcystin LR concentrations on eight occasions that corresponded to a slight to moderate human health risk according to WHO guideline values for recreational waters. By determining the concentration of microcystin LR in cyanobacterial biomass, we identified cyanobacterial populations that occurred over time with varying degrees of toxin production (maximal 85.4 µg/mm 3 ). The microcystin LR concentration in Bonete was positively correlated with temperature (r = 0.587) and cyanobacterial biomass (r = 0.736), in Baygorria with cyanobacterial biomass (r = 0.521), and in Palmar with temperature (r = 0.500) and negatively correlated with ammonia (r = -0.492). Action is needed to reduce the presence of toxic cyanobacteria in these systems. A decrease in the use of agrochemicals and management changes in the reservoir basins could be successful long-term measures.

  18. Tidal impact on the dynamic behavior of dissolved pharmaceuticals in the Yangtze Estuary, China.

    Science.gov (United States)

    Zhao, Heng; Zhou, Jun Liang; Zhang, Jing

    2015-12-01

    The dynamic behavior of 24 dissolved pharmaceuticals over tidal cycles in the Yangtze Estuary, China was studied to assess the tidal impact on the fate of pharmaceutical residues. The results show that most pharmaceuticals were frequently detected with concentrations from below detection to 27.2 ng/L, with sulfamethoxazole, sulfamethazine, erythromycin, thiamphenicol and florfenicol dominating. During tidal cycles, pharmaceutical concentrations decreased during tidal rise, then increasing during tidal receding for all locations, except at site S2 which showed an opposite trend due to unique water movement there. It was observed that most compounds showed a non-conservative behavior, while diazepam and sulfamethoxazole displayed a conservative behavior. The pharmaceutical concentrations were found to increase with dissolved organic carbon (DOC) concentration, suggesting DOC as a carrier of pharmaceuticals. In addition, many compounds showed a significant negative relationship with suspended particulate matter (SPM) concentration, indicating SPM-water interactions as a control of pharmaceutical behavior in estuarine environment. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Total vs. internal element concentrations in Scots pine needles along a sulphur and metal pollution gradient

    International Nuclear Information System (INIS)

    Rautio, Pasi; Huttunen, Satu

    2003-01-01

    Different methods should be used for foliar analyses of trees used as bioindicators of pollution, than those analyses used in nutritional studies of trees. - Analysis of foliar elements is a commonly used method for studying tree nutrition and for monitoring the impacts of air pollutants on forest ecosystems. Interpretations based on the results of foliar element analysis may, however, be different in nutrition vs. monitoring studies. We studied the impacts of severe sulphur and metal (mainly Cu and Ni) pollution on the element concentrations (Al, Ca, Cu, Fe, K, Mg, Mn, Ni, P, Pb, S and Zn) in Scots pine (Pinus sylvestris L.) foliage along an airborne sulphur and metal pollution gradient. Emphasis was put on determining the contribution of air-borne particles that have accumulated on needle surfaces to the total foliage concentrations. A comparison of two soil extraction methods was carried out in order to obtain a reliable estimate of plant-available element concentrations in the soil. Element concentrations in the soil showed only a weak relationship with internal foliar concentrations. There were no clear differences between the total and internal needle S concentrations along the gradient, whereas at the plot closest to the metal smelter complex the total Cu concentrations in the youngest needles were 1.3-fold and Ni concentrations over 1.6-fold higher than the internal needle concentrations. Chloroform-extracted surface wax was found to have Ni and Cu concentrations of as high as 3000 and 600 μg/g of wax, respectively. Our results suggest that bioindicator studies (e.g. monitoring studies) may require different foliar analysis techniques from those used in studies on the nutritional status of trees

  20. Isotope correlation verification of analytical measurements for dissolver materials

    International Nuclear Information System (INIS)

    Satkowski, J.

    1988-01-01

    An independent verification of analytical results for accountability measurements of dissolver materials can be performed using the Iosotop Correlation Technique (ICT). ICT is based on the relationships that exist between the initial and final elemental concentration and isotopic abundances of the nuclear fuel. Linear correlation functions between isotopic ratios and plutonium/uranium ratios have been developed for specific reactor fuels. The application of these correlations to already existing analytical data provides a laboratory additional confidence in the reported results. Confirmation is done by a test of consistancy with historical data. ICT is being utilized with dissolver accountability measurements at the Savannah River Plant Laboratory. The application, implementation, and operating experience of this technique are presented