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Sample records for dissolved organic phosphorus

  1. Sargasso Sea phosphorus biogeochemistry: an important role for dissolved organic phosphorus (DOP

    Directory of Open Access Journals (Sweden)

    M. W. Lomas

    2010-02-01

    Full Text Available Inorganic phosphorus (SRP concentrations in the subtropical North Atlantic are some of the lowest in the global ocean and have been hypothesized to constrain primary production. Based upon data from several transect cruises in this region, it has been hypothesized that dissolved organic phosphorus (DOP supports a significant fraction of primary production in the subtropical North Atlantic. In this study, a time-series of phosphorus biogeochemistry is presented for the Bermuda Atlantic Time-series Study site, including rates of phosphorus export. Most parameters have a seasonal pattern, although year-over-year variability in the seasonal pattern is substantial, likely due to differences in external forcing. Suspended particulate phosphorus exhibits a seasonal maximum during the spring bloom, despite the absence of a seasonal peak in SRP. However, DOP concentrations are at an annual maximum prior to the winter/spring bloom and decline over the course of the spring bloom while whole community alkaline phosphatase activities are highest. As a result of DOP bioavailability, the growth of particles during the spring bloom occurs in Redfield proportions, though particles exported from the euphotic zone show rapid and significant remineralization of phosphorus within the first 50 m below the euphotic zone. Based upon DOP data from transect cruises in this region, the southward cross gyral flux of DOP is estimated to support ~25% of annual primary production and ~100% of phosphorus export. These estimates are consistent with other research in the subtropical North Atlantic and reinforce the hypothesis that while the subtropics may be phosphorus stressed (a physiological response to low inorganic phosphorus, utilization of the DOP pool allows production and accumulation of microbial biomass at Redfield proportions.

  2. Assessing the Role of Dissolved Organic Phosphate on Rates of Microbial Phosphorus Cycling

    Science.gov (United States)

    Gonzalez, A. C.; Popendorf, K. J.; Duhamel, S.

    2016-02-01

    Phosphorus (P) is an element crucial to life, and it is limiting in many parts of the ocean. In oligotrophic environments, the dissolved P pool is cycled rapidly through the activity of microbes, with turnover times of several hours or less. The overarching aim of this study was to assess the flux of P from picoplankton to the dissolved pool and the role this plays in fueling rapid P cycling. To determine if specific microbial groups are responsible for significant return of P to the dissolved pool during cell lifetime, we compared the rate of cellular P turnover (cell-Pτ, the rate of cellular P uptake divided by cellular P content) to the rate of cellular biomass turnover (cellτ). High rates of P return to the dissolved pool during cell lifetime (high cell-Pτ/cellτ) indicate significant P regeneration, fueling more rapid turnover of the dissolved P pool. We hypothesized that cell-Pτ/cellτ varies widely across picoplankton groups. One factor influencing this variation may be each microbial group's relative uptake of dissolved organic phosphorus (DOP) versus dissolved inorganic phosphorus (DIP). As extracellular hydrolysis is necessary for P incorporation from DOP, this process may return more P to the dissolved pool than DIP incorporation. This leads to the question: does a picoplankton's relative uptake of DOP (versus DIP) affect the rate at which it returns phosphorus to the dissolved pool? To address this question, we compared the rate of cellular P turnover based on uptake of DOP and uptake DIP using cultured representatives of three environmentally significant picoplankton groups: Prochlorococcus, Synechococcus, and heterotrophic bacteria. These different picoplankton groups are known to take up different ratios of DOP to DIP, and may in turn make significantly different contributions to the regeneration and cycling phosphorus. These findings have implications towards our understanding of the timeframes of biogeochemical cycling of phosphorus in the

  3. Photochemical degradation of dissolved organic matter reduces the availability of phosphorus for aquatic primary producers

    Czech Academy of Sciences Publication Activity Database

    Porcal, Petr; Kopáček, Jiří

    2018-01-01

    Roč. 193, FEB (2018), s. 1018-1026 ISSN 0045-6535 R&D Projects: GA ČR GA15-09721S Institutional support: RVO:60077344 Keywords : photochemistry * phosphorus * dissolved organic matter * aluminum * iron Subject RIV: DA - Hydrology ; Limnology OBOR OECD: Environmental sciences (social aspects to be 5.7) Impact factor: 4.208, year: 2016

  4. Effect of exposure to sunlight and phosphorus-limitation on bacterial degradation of coloured dissolved organic matter (CDOM) in freshwater

    DEFF Research Database (Denmark)

    Kragh, Theis; Søndergaard, Morten; Tranvik, Lars

    2008-01-01

    This study reports on the interacting effect of photochemical conditioning of dissolved organic matter and inorganic phosphorus on the metabolic activity of bacteria in freshwater. Batch cultures with lake-water bacteria and dissolved organic carbon (DOC) extracted from a humic boreal river were...... arranged in an experimental matrix of three levels of exposure to simulated sunlight and three levels of phosphorus concentration. We measured an increase in bacterial biomass, a decrease in DOC and bacterial respiration as CO(2) production and O(2) consumption over 450 h. These measurements were used...

  5. Assessing the bioavailability of dissolved organic phosphorus in pasture and cultivated soils treated with different rates of nitrogen fertiliser

    NARCIS (Netherlands)

    McDowell, R.W.; Koopmans, G.F.

    2006-01-01

    A proportion of dissolved organic phosphorus (DOP) in soil leachates is readily available for uptake by aquatic organisms and, therefore, can represent a hazard to surface water quality. A study was conducted to characterise DOP in water extracts and soil P fractions of lysimeter soils (pasture

  6. Promotion Effect of Asian Dust on Phytoplankton Growth and Potential Dissolved Organic Phosphorus Utilization in the South China Sea

    Science.gov (United States)

    Chu, Qiang; Liu, Ying; Shi, Jie; Zhang, Chao; Gong, Xiang; Yao, Xiaohong; Guo, Xinyu; Gao, Huiwang

    2018-03-01

    Dust deposition is an important nutrient source to the South China Sea (SCS), but few in situ experiments were conducted on phytoplankton response to the deposition. We conducted onboard incubation experiments at three stations near Luzon Strait in the SCS, with addition of multiple dissolved inorganic nutrients, Asian dust, and rainwater. From our results, nitrogen and phosphorus were both urgently needed for phytoplankton growth in the SCS, indicated by the evident Chl a response to the addition of nitrogen and phosphorus together. Almost no evident response was observed by adding phosphorus or iron alone to incubation waters, although a delayed response of Chl a in mass concentration was observed by adding nitrogen alone. The latter implied a possible utilization of dissolved organic phosphorus because of insufficient dissolved inorganic phosphorus in incubation waters. Under such nutrient condition, Asian dust showed an apparent promotion effect on phytoplankton growth by providing sufficient amounts of nitrogen but low phosphorus. Meanwhile, it was found that large sized (> 5 μm) phytoplankton community showed different responses to dust addition at different stations. At stations A3 and A6, Chaetoceros spp. became the dominant species during the bloom period, while at station WG2, Nitzschia spp. became dominant. In combination with different initial nutrients and Chl a levels at the three stations, the different phytoplankton community evolution implied the response difference to external inputs between oligotrophic (stations A3 and A6) and ultraoligotrophic (station WG2) conditions in the SCS.

  7. Contrasted response of colloidal, organic and inorganic dissolved phosphorus forms during rewetting of dried riparian soils

    Science.gov (United States)

    Gu, Sen; Gruau, Gérard; Malique, François; Dupas, Rémi; Gascuel-Odoux, Chantal; Petitjean, Patrice; Bouhnik-Le Coz, Martine

    2017-04-01

    Riparian vegetated buffer strip (RVBS) are currently used to protect surface waters from phosphorus (P) emissions because of their ability to retain P-enriched soil particles. However, this protection role may be counterbalanced by the development in these zones of conditions able to trigger the release of highly mobile dissolved or colloidal P forms. Rewetting after drying is one of these conditions. So far, the potential sources of P mobilized during rewetting after drying are not clearly identified, nor are clearly identified the chemical nature of the released dissolved P species, or the role of the soil P speciation on these forms. In this study, two riparian soils (G and K) showing contrasting soil P speciation (65% of inorganic P species in soil G, as against 70% of organic P) were submitted to three successive dry/wet cycles in the laboratory. Conventional colorimetric determination of P concentrations combined with ultrafiltration, and measurements of iron (Fe) and aluminum (Al) and dissolved organic carbon (DOC) contents using ICP-MS and TOC analyzers, respectively, were used to study the response of the different P forms to rewetting after drying and also their release kinetics during soil leaching. For both soils, marked P release peaks were observed at the beginning of each wet cycles, with the organic-rich K soils giving, however, larger peaks than the inorganic one (G soil). For both soils also, concentrations in molybdate reactive P (MRP) remained quite constant throughout each leaching episode, contrary to the molybdate unreactive P (MUP) concentrations which were high immediately after rewetting and then decreased rapidly during leaching. A speciation change was observed from the beginning to the end of all leaching cycles. Colloidal P was found to be a major fraction of the total P immediately after rewetting (up to 50-70%) and then decreased to the end of each wet cycle where most of the eluted P was true dissolved inorganic P. Colloidal

  8. Dissolved organic phosphorus and its bioavailable fraction in the Baltic Sea

    Science.gov (United States)

    Nausch, M.; Nausch, G.; Setzkorn, D.; Welz, Ä.

    2009-04-01

    In general, it is accepted that dissolved organic phosphorus (DOP) is besides dissolved inorganic phosphorus (DIP) a source for phosphorus nutrition of phyto- and bacterioplankton. If available, DIP is usually preferred to DOP. DOP becomes the most important source under DIP depleted conditions occurring in the Baltic Sea in summer. However, its contribution to nutrition and consequently its significance is very difficult to appraise because only the bioavailable fraction (BAP = bioavailable phosphorus) can be used by organisms. DOP comprises also inert compounds which persist over longer periods. Therefore, there is an urgent need to quantify the bioavailable DOP. In 2004 and 2005, DOP and BAP concentrations were detected in surface water at three stations in the central Baltic Sea from May until July. In June/July 2008 an intensive measuring campaign was performed throughout the whole Baltic Sea. DOP measurements were done from the entrance to the North Sea in the West until the innermost parts of the Gulf of Bothnia in the North and the Gulf of Finland in the East. BAP was determined at 14 stations in the central and northern parts. DOP was determined using the alkaline potassium peroxidisulphate oxidation method followed by the manual DIP determination. BAP has been detected in time course experiments using 0.8 µm filtered sea water containing free-living heterotrophic bacteria and amended with 7 µM ammonium chloride and 1mg l-1 D-(+) glucosemonohydrate to prevent nitrogen and carbon limitation and increase the phosphorus demand in bacteria. BAP is defined as that proportion of DOP which is used by bacteria and calculated as the difference of DOP concentrations at the beginning and the lowest concentrations during an incubation for 4-6 days. In 2004 and 2005, most DOP concentrations ranged between 0.18 and 0.32 µM, with a declining tendency from spring to summer probably due to elevated uptake compared to its release caused by higher temperatures and DIP

  9. Dissolved organic phosphorus utilization and alkaline phosphatase activity of the dinoflagellate Gymnodinium impudicum isolated from the South Sea of Korea

    Science.gov (United States)

    Oh, Seok Jin; Kwon, Hyeong Kyu; Noh, Il Hyeon; Yang, Han-Soeb

    2010-09-01

    This study investigated alkaline phosphatase (APase) activity and dissolved organic and inorganic phosphorus utilization by the harmful dinoflagellate Gymnodinium impudicum (Fraga et Bravo) Hansen et Moestrup isolated from the South Sea of Korea. Under conditions of limited phosphorus, observation of growth kinetics in batch culture yielded a maximum growth rate (μmax) of 0.41 /day and a half saturation constant (Ks) of 0.71 μM. In time-course experiments, APase was induced as dissolved inorganic phosphorus (DIP) concentrations fell below 0.83 μM, a threshold near the estimated Ks; APase activity increased with further DIP depletion to a maximum of 0.70 pmol/cell/h in the senescent phase. Thus, Ks may be an important index of the threshold DIP concentration for APase induction. G. impudicum utilizes a wide variety of dissolved organic phosphorus compounds in addition to DIP. These results suggest that DIP limitation in the Southern Sea of Korea may have led to the spread of G. impudicum along with the harmful dinoflagellate Cochlodinium polykrikoides in recent years.

  10. Effect of exposure to sunlight and phosphorus-limitation on bacterial degradation of coloured dissolved organic matter (CDOM) in freshwater.

    Science.gov (United States)

    Kragh, Theis; Søndergaard, Morten; Tranvik, Lars

    2008-05-01

    This study reports on the interacting effect of photochemical conditioning of dissolved organic matter and inorganic phosphorus on the metabolic activity of bacteria in freshwater. Batch cultures with lake-water bacteria and dissolved organic carbon (DOC) extracted from a humic boreal river were arranged in an experimental matrix of three levels of exposure to simulated sunlight and three levels of phosphorus concentration. We measured an increase in bacterial biomass, a decrease in DOC and bacterial respiration as CO(2) production and O(2) consumption over 450 h. These measurements were used to calculate bacterial growth efficiency (BGE). Bacterial degradation of DOC increased with increasing exposure to simulated sunlight and availability of phosphorus and no detectable growth occurred on DOC that was not pre-exposed to simulated sunlight. The outcome of photochemical degradation of DOC changed with increasing availability of phosphorus, resulting in an increase in BGE from about 5% to 30%. Thus, the availability of phosphorus has major implications for the quantitative transfer of carbon in microbial food webs.

  11. Characterization of the rate and temperature sensitivities of bacterial remineralization of dissolved organic phosphorus by natural populations

    Directory of Open Access Journals (Sweden)

    Angelicque E. White

    2012-08-01

    Full Text Available Production, transformation, and degradation are the principal components of the cycling of dissolved organic matter (DOM in marine systems. Heterotrophic Bacteria (and Archaea play a large part in this cycling via enzymatic decomposition and intracellular transformations of organic material to inorganic carbon (C, nitrogen (N , and phosphorus (P. The rate and magnitude of inorganic nutrient regeneration from DOM is related to the elemental composition and lability of DOM substrates as well as the nutritional needs of the mediating organisms. While many previous efforts have focused on C and N cycling of DOM, less is known in regards to the controls of organic P utilization and remineralization by natural populations of bacteria. In order to constrain the relative time scales and degradation of select dissolved organic P (DOP compounds we have conducted a series of experiments focused on (1 assessment of the short-term lability of a range of DOP compounds, (2 characterization of labile DOP remineralization rates and (3 examination of temperature sensitivities of labile DOP remineralization for varying bacterial populations. Results reinforce previous findings of monoester and polyphosphate lability and the relative recalcitrance of a model phosphonate: 2-aminoethylphosphonate. High resolution time-series of P monoester remineralization indicates decay constants on the order of 0.67-7.04 d-1 for bacterial populations isolated from coastal and open ocean surface waters. The variability of these rates is predictably related to incubation temperature and initial concentrations of heterotrophic bacteria. Additional controls on DOP hydrolysis included seasonal shifts in bacterial populations and the physiological state of bacteria at the initiation of DOP addition experiments. Composite results indicate that bacterial hydrolysis of P-monoesters exceeds bacterial P demand and thus DOP remineralization efficiency may control P availability to autotrophs.

  12. 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.

  13. Dynamics of particulate and dissolved organic and inorganic phosphorus during the peak and declining phase of an iron-induced phytoplankton bloom in the eastern subarctic Pacific

    Science.gov (United States)

    Yoshimura, Takeshi; Nishioka, Jun; Ogawa, Hiroshi; Tsuda, Atsushi

    2018-01-01

    Phosphorus (P) is an essential element for all organisms and thus the P cycle plays a key role in determining the dynamics of lower trophic levels in marine ecosystems. P in seawater occurs conceptually in particulate and dissolved organic and inorganic (POP, PIP, DOP, and DIP, respectively) pools and clarification of the dynamics in these P pools is the basis to assess the biogeochemical cycle of P. Despite its importance, behaviors of each P pool with phytoplankton dynamics have not been fully examined. We measured the four operationally defined P pools (POPop, PIPop, DOPop, and SRP) during an iron-induced phytoplankton bloom (as part of the subarctic ecosystem response to iron enrichment study (SERIES)) in the eastern subarctic Pacific in summer 2002. During our observations of the iron-enriched patch from day 15 to day 26 after the iron infusion, chlorophyll-a concentration in the surface layer decreased from 6.3 to 1.2 μg L- 1, indicating the peak through decline phase of the phytoplankton bloom. At the bloom peak, P was partitioned into POPop, PIPop, and DOPop in proportions of 60, 27, and 13%, respectively. While chlorophyll-a and POPop showed similar temporal variations during the declining phase, PIPop showed a different peak timing with a 2 day delay compared to POPop, resulting in a rapid change in the relative proportion of PIPop to total particulate P (TPP = POPop + PIPop) at the peak (25%) and during the declining phase of the bloom (50%). A part of POPop was replaced by PIPop just after slowing down of phytoplankton growth. This process may have a significant role in the subsequent regeneration of P. We conclude that measurement of TPP alone is insufficient to show the interaction between P and phytoplankton dynamics and fractionation of TPP into POPop and PIPop provides useful insights to clarify the biogeochemical cycle of P.

  14. Organic chemistry of elemental phosphorus

    International Nuclear Information System (INIS)

    Milyukov, V A; Budnikova, Yulia H; Sinyashin, Oleg G

    2005-01-01

    The principal achievements and the modern trends in the development of the chemistry of elemental phosphorus are analysed, described systematically and generalised. The possibilities and advantages of the preparation of organophosphorus compounds directly from white phosphorus are demonstrated. Attention is focused on the activation and transformation of elemental phosphorus in the coordination sphere of transition metal complexes. The mechanisms of the reactions of white phosphorus with nucleophilic and electrophilic reagents are discussed. Electrochemical approaches to the synthesis of organic phosphorus derivatives based on white phosphorus are considered.

  15. The influence of dissolved phosphorus molecular form on recalcitrance and bioavailability

    International Nuclear Information System (INIS)

    Li, Bo; Brett, Michael T.

    2013-01-01

    Several studies have shown Soluble Reactive Phosphorus (SRP) analyses provide a poor index of dissolved phosphorus (P) bioavailability in natural systems. We tested 21 inorganic and organic P containing compounds with series of nutrient uptake and bioavailability bioassay experiments and chemical characterizations. Our results show that in 81% of cases, these compounds did not fit the classic assumption that SRP approximately equals Bioavailable P (BAP). Many organic compounds were classified as non-reactive, but had very rapid uptake kinetics and were nearly entirely bioavailable (e.g., several nucleic acids, ATP, RNA, DNA and phosphatidylcholine). Several inorganic compounds also classified as non-reactive but had high bioavailability (i.e., sodium tripolyphosphate and phosphorus pentoxide). Conversely, apatite was operationally classified as reactive, but had low bioavailability. Due to their tendency to alias as SRP, but recalcitrance and very low bioavailability, humic-(Al/Fe)-phosphorus complexes may play an especially important role in the dissolved phosphorus dynamics of natural systems. Highlights: •We tested 21 P containing compounds with bioassay and chemical speciation. •The acid molybdate method does not consistently predict the bioavailability of P compounds. •The P in humic substances was bounded with Al/Fe and could not be taken up by algal. •A new classification scheme divided P species based on bioavailability and chemical speciation. -- SRP is a poor indicator of the bioavailability of many of P containing compounds and much of what is classified as SRP in nature could be associated with humic-metal complexes with low bioavailability

  16. The release of dissolved phosphorus from lake sediments

    NARCIS (Netherlands)

    Boers, P.C.M.

    1991-01-01

    Chapter 1. Introduction: Eutrophication is one of the world's major water quality problems. Attempts to alleviate eutrophication of lakes have involved the control of phosphorus loadings. In such cases, an internal loading of phosphorus from the sediments may

  17. Cycling downwards - dissolved organic matter in soils

    NARCIS (Netherlands)

    Kaiser, K.; Kalbitz, K.

    2012-01-01

    Dissolved organic matter has been recognized as mobile, thus crucial to translocation of metals, pollutants but also of nutrients in soil. We present a conceptual model of the vertical movement of dissolved organic matter with soil water, which deviates from the view of a chromatographic stripping

  18. The Absorption of Light in Lakes: Negative Impact of Dissolved Organic Carbon on Primary Productivity

    OpenAIRE

    Thrane, Jan-Erik; Hessen, Dag O.; Andersen, Tom

    2014-01-01

    Colored dissolved organic matter (CDOM) absorbs a substantial fraction of photosynthetically active radiation (PAR) in boreal lakes. However, few studies have systematically estimated how this light absorption influences pelagic primary productivity. In this study, 75 boreal lakes spanning wide and orthogonal gradients in dissolved organic carbon (DOC) and total phosphorus (TP) were sampled during a synoptic survey. We measured absorption spectra of phytoplankton pigments, CDOM, and non-algal...

  19. Dissolved organic nutrients and phytoplankton production in the Mandovi estuary and coastal waters of Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Verlecar, X.N.

    Total organic nitrogen (TON) and dissolved organic phosphorus (DOP) in the coastal and estuarine waters of Goa, India varied from 0.6 to 47.1 mu g-at N 1-1 and 0.12 to 3.49 mu g-at P l-1 respectively. The chlorophyll content of these waters...

  20. 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

  1. 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.

  2. Dissolved oxygen and dietary phosphorus modulate utilization and effluent partitioning of phosphorus in rainbow trout (Oncorhynchus mykiss) aquaculture

    International Nuclear Information System (INIS)

    McDaniel, Nichole K.; Sugiura, Shozo H.; Kehler, Thomas; Fletcher, John W.; Coloso, Relicardo M.; Weis, Peddrick; Ferraris, Ronaldo P.

    2005-01-01

    Phosphorus (P) is the limiting nutrient in freshwater primary production, and excessive levels cause premature eutrophication. P levels in aquaculture effluents are now tightly regulated. Increasing our understanding of waste P partitioning into soluble, particulate, and settleable fractions is important in the management of effluent P. When water supply is limited, dissolved oxygen concentration (DO) decreases below the optimum levels. Therefore, we studied effects of DO (6 and 10 mg/L) and dietary P (0.7 and 1.0% P) on rainbow trout growth, P utilization, and effluent P partitioning. Biomass increased by 40% after 3 weeks. DO at 10 mg/L significantly increased fish growth and feed efficiency, and increased the amount of P in the soluble fraction of the effluent. Soluble effluent P was greater in fish fed 1.0% P. DO increases fish growth and modulates P partitioning in aquaculture effluent. - Dissolved oxygen concentration not only influences fish growth rate, but also affects dietary phosphorus utilization by fish in intensive aquaculture

  3. The simulation research of dissolved nitrogen and phosphorus non-point source pollution in Xiao-Jiang watershed of Three Gorges Reservoir area.

    Science.gov (United States)

    Wu, Lei; Long, Tian-Yu; Li, Chong-Ming

    2010-01-01

    Xiao-jiang, with a basin area of almost 5,276 km(2) and a length of 182.4 km, is located in the center of the Three Gorges Reservoir Area, and is the largest tributary of the central section in Three Gorges Reservoir Area, farmland accounts for a large proportion of Xiao-jiang watershed, and the hilly cropland of purple soil is much of the farmland of the watershed. After the second phase of water storage in the Three Gorges Reservoir, the majority of sub-rivers in the reservoir area experienced eutrophication phenomenon frequently, and non-point source (NPS) pollution has become an important source of pollution in Xiao-jiang Watershed. Because dissolved nitrogen and phosphorus non-point source pollution are related to surface runoff and interflow, using climatic, topographic and land cover data from the internet and research institutes, the Semi-Distributed Land-use Runoff Process (SLURP) hydrological model was introduced to simulate the complete hydrological cycle of the Xiao-jiang Watershed. Based on the SLURP distributed hydrological model, non-point source pollution annual output load models of land use and rural residents were respectively established. Therefore, using GIS technology, considering the losses of dissolved nitrogen and phosphorus in the course of transport, a dissolved non-point source pollution load dynamic model was established by the organic coupling of the SLURP hydrological model and land-use output model. Through the above dynamic model, the annual dissolved non-point source nitrogen and phosphorus pollution output as well as the load in different types were simulated and quantitatively estimated from 2001 to 2008, furthermore, the loads of Xiao-jiang Watershed were calculated and expressed by temporal and spatial distribution in the Three Gorges Reservoir Area. The simulation results show that: the temporal changes of dissolved nitrogen and phosphorus load in the watershed are close to the inter-annual changes of rainfall runoff, and the

  4. 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.

  5. Vertical Stratification of Soil Phosphorus as a Concern for Dissolved Phosphorus Runoff in the Lake Erie Basin.

    Science.gov (United States)

    Baker, David B; Johnson, Laura T; Confesor, Remegio B; Crumrine, John P

    2017-11-01

    During the re-eutrophication of Lake Erie, dissolved reactive phosphorus (DRP) loading and concentrations to the lake have nearly doubled, while particulate phosphorus (PP) has remained relatively constant. One potential cause of increased DRP concentrations is P stratification, or the buildup of soil-test P (STP) in the upper soil layer (soil samples (0-5 or 0-2.5 cm) alongside their normal agronomic samples (0-20 cm) ( = 1758 fields). The mean STP level in the upper 2.5 cm was 55% higher than the mean of agronomic samples used for fertilizer recommendations. The amounts of stratification were highly variable and did not correlate with agronomic STPs (Spearman's = 0.039, = 0.178). Agronomic STP in 70% of the fields was within the buildup or maintenance ranges for corn ( L.) and soybeans [ (L.) Merr.] (0-46 mg kg Mehlich-3 P). The cumulative risks for DRP runoff from the large number of fields in the buildup and maintenance ranges exceeded the risks from fields above those ranges. Reducing stratification by a one-time soil inversion has the potential for larger and quicker reductions in DRP runoff risk than practices related to drawing down agronomic STP levels. Periodic soil inversion and mixing, targeted by stratified STP data, should be considered a viable practice to reduce DRP loading to Lake Erie. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  6. Temperature dependence of photodegradation of dissolved organic matter to dissolved inorganic carbon and particulate organic carbon

    Czech Academy of Sciences Publication Activity Database

    Porcal, Petr; Dillon, P. J.; Molot, L. A.

    2015-01-01

    Roč. 10, č. 6 (2015), e0128884 E-ISSN 1932-6203 R&D Projects: GA ČR(CZ) GAP503/12/0781; GA ČR(CZ) GA15-09721S Institutional support: RVO:60077344 Keywords : dissolved organic carbon * particulate organic carbon * photodegradation * temperature Subject RIV: DA - Hydrology ; Limnology Impact factor: 3.057, year: 2015

  7. Acidity controls on dissolved organic carbon mobility in organic soils

    Czech Academy of Sciences Publication Activity Database

    Evans, Ch. D.; Jones, T.; Burden, A.; Ostle, N.; Zielinski, P.; Cooper, M.; Peacock, M.; Clark, J.; Oulehle, Filip; Cooper, D.; Freeman, Ch.

    2012-01-01

    Roč. 18, č. 11 (2012), s. 3317-3331 ISSN 1354-1013 Institutional support: RVO:67179843 Keywords : acidity * dissolved organic carbon * organic soil * peat * podzol * soil carbon * sulphur Subject RIV: EH - Ecology, Behaviour Impact factor: 6.910, year: 2012

  8. Spatial variation in sediment-water exchange of phosphorus in Florida Bay: AMP as a model organic compound.

    Science.gov (United States)

    Huang, Xiao-Lan; Zhang, Jia-Zhong

    2010-10-15

    Dissolved organic phosphorus (DOP) has been recognized as dominant components in total dissolved phosphorus (TDP) pools in many coastal waters, and its exchange between sediment and water is an important process in biogeochemical cycle of phosphorus. Adenosine monophosphate (AMP) was employed as a model DOP compound to simulate phosphorus exchange across sediment-water interface in Florida Bay. The sorption data from 40 stations were fitted to a modified Freundlich equation and provided a detailed spatial distribution both of the sediment's zero equilibrium phosphorus concentration (EPC(0-T)) and of the distribution coefficient (K(d-T)) with respect to TDP. The K(d-T) was found to be a function of the index of phosphorus saturation (IPS), a molar ratio of the surface reactive phosphorus to the surface reactive iron oxide content in the sediment, across the entire bay. However, the EPC(0-T) was found to correlate to the contents of phosphorus in the eastern bay only. Sediment in the western bay might act as a source of the phosphorus in the exchange process due to their high EPC(0-T) and low K(d-T), whereas sediments in the eastern bay might act as a sink because of their low EPC(0-T) and high K(d-T). These results strongly support the hypothesis that both phosphorus and iron species in calcareous marine sediments play a critical role in governing the sediment-water exchange of both phosphate and DOP in the coastal and estuarine ecosystems.

  9. Biological phosphorus and nitrogen removal in sequencing batch reactors: effects of cycle length, dissolved oxygen concentration and influent particulate matter.

    Science.gov (United States)

    Ginige, Maneesha P; Kayaalp, Ahmet S; Cheng, Ka Yu; Wylie, Jason; Kaksonen, Anna H

    2013-01-01

    Removal of phosphorus (P) and nitrogen (N) from municipal wastewaters is required to mitigate eutrophication of receiving water bodies. While most treatment plants achieve good N removal using influent carbon (C), the use of influent C to facilitate enhanced biological phosphorus removal (EBPR) is poorly explored. A number of operational parameters can facilitate optimum use of influent C and this study investigated the effects of cycle length, dissolved oxygen (DO) concentration during aerobic period and influent solids on biological P and N removal in sequencing batch reactors (SRBs) using municipal wastewaters. Increasing cycle length from 3 to 6 h increased P removal efficiency, which was attributed to larger portion of N being removed via nitrite pathway and more biodegradable organic C becoming available for EBPR. Further increasing cycle length from 6 to 8 h decreased P removal efficiencies as the demand for biodegradable organic C for denitrification increased as a result of complete nitrification. Decreasing DO concentration in the aerobic period from 2 to 0.8 mg L(-1) increased P removal efficiency but decreased nitrification rates possibly due to oxygen limitation. Further, sedimented wastewater was proved to be a better influent stream than non-sedimented wastewater possibility due to the detrimental effect of particulate matter on biological nutrient removal.

  10. 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.

  11. Forms of organic phosphorus in wetland soils

    Science.gov (United States)

    Cheesman, A. W.; Turner, B. L.; Reddy, K. R.

    2014-12-01

    Phosphorus (P) cycling in freshwater wetlands is dominated by biological mechanisms, yet there has been no comprehensive examination of the forms of biogenic P (i.e., forms derived from biological activity) in wetland soils. We used solution 31P NMR spectroscopy to identify and quantify P forms in surface soils of 28 palustrine wetlands spanning a range of climatic, hydrogeomorphic, and vegetation types. Total P concentrations ranged between 51 and 3516 μg P g-1, of which an average of 58% was extracted in a single-step NaOH-EDTA procedure. The extracts contained a broad range of P forms, including phosphomonoesters (averaging 24% of the total soil P), phosphodiesters (averaging 10% of total P), phosphonates (up to 4% of total P), and both pyrophosphate and long-chain polyphosphates (together averaging 6% of total P). Soil P composition was found to be dependant upon two key biogeochemical properties: organic matter content and pH. For example, stereoisomers of inositol hexakisphosphate were detected exclusively in acidic soils with high mineral content, while phosphonates were detected in soils from a broad range of vegetation and hydrogeomorphic types but only under acidic conditions. Conversely inorganic polyphosphates occurred in a broad range of wetland soils, and their abundance appears to reflect more broadly that of a "substantial" and presumably active microbial community with a significant relationship between total inorganic polyphosphates and microbial biomass P. We conclude that soil P composition varies markedly among freshwater wetlands but can be predicted by fundamental soil properties.

  12. Titanium dioxide-based DGT technique for in situ measurement of dissolved reactive phosphorus in fresh and marine waters

    DEFF Research Database (Denmark)

    Panther, Jared G.; Teasdale, Peter R.; Bennett, William W.

    2010-01-01

    A new diffusive gradients in a thin film (DGT) technique for measuring dissolved reactive phosphorus (DRP) in fresh and marine waters is reported. The new method, which uses a commercially available titanium dioxide based adsorbent (Metsorb), was evaluated and compared to the well-established fer...

  13. 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.

  14. 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.

  15. Organic carbon, nitrogen and phosphorus contents of some tea soils

    International Nuclear Information System (INIS)

    Ahmed, M.S.; Zamir, M.R.; Sanauallah, A.F.M.

    2005-01-01

    Soil samples were collected from Rungicherra Tea-Estate of Moulvibazar district, Bangladesh. Organic carbon, organic matter, total nitrogen and available phosphorus content of the collected soil of different topographic positions have been determined. The experimental data have been analyzed statistically and plotted against topography and soil depth. Organic carbon and organic matter content varied from 0.79 to 1.24% and 1.37 to 2.14%. respectively. Total nitrogen and available phosphorus content of these soils varied respectively from 0.095 to 0.13% and 2.31 to 4.02 ppm. (author)

  16. 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...

  17. Characterisation and quantification of organic phosphorus and organic nitrogen components in aquatic systems: A Review

    Energy Technology Data Exchange (ETDEWEB)

    Worsfold, Paul J. [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL48AA (United Kingdom)], E-mail: pworsfold@plymouth.ac.uk; Monbet, Philippe [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL48AA (United Kingdom); Water Studies Centre, School of Chemistry, Monash University, Clayton 3800, Victoria (Australia); Tappin, Alan D.; Fitzsimons, Mark F.; Stiles, David A. [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL48AA (United Kingdom); McKelvie, Ian D. [Water Studies Centre, School of Chemistry, Monash University, Clayton 3800, Victoria (Australia)

    2008-08-22

    This review provides a critical assessment of knowledge regarding the determination of organic phosphorus (OP) and organic nitrogen (ON) in aquatic systems, with an emphasis on biogeochemical considerations and analytical challenges. A general background on organic phosphorus and organic nitrogen precedes a discussion of sample collection, extraction, treatment/conditioning and preconcentration of organic phosphorus/nitrogen from sediments, including suspended particulate matter, and waters, including sediment porewaters. This is followed by sections on the determination of organic phosphorus/nitrogen components. Key techniques covered for organic phosphorus components are molecular spectrometry, atomic spectrometry and enzymatic methods. For nitrogen the focus is on the measurement of total organic nitrogen concentrations by carbon hydrogen nitrogen analysis and high temperature combustion, and organic nitrogen components by gas chromatography, high-performance liquid chromatography, gel electrophoresis, mass spectrometry, nuclear magnetic resonance spectrometry, X-ray techniques and enzymatic methods. Finally future trends and needs are discussed and recommendations made.

  18. Global effects of agriculture on fluvial dissolved organic matter

    DEFF Research Database (Denmark)

    Graeber, Daniel; Boëchat, Iola; Encina, Francisco

    2015-01-01

    Agricultural land covers approximately 40% of Earth’s land surface and affects hydromorphological, biogeochemical and ecological characteristics of fluvial networks. In the northern temperate region, agriculture also strongly affects the amount and molecular composition of dissolved organic matter...

  19. Improving phosphorus availability in an acid soil using organic amendments produced from agroindustrial wastes.

    Science.gov (United States)

    Ch'ng, Huck Ywih; Ahmed, Osumanu Haruna; Majid, Nik Muhamad Ab

    2014-01-01

    In acid soils, soluble inorganic phosphorus is fixed by aluminium and iron. To overcome this problem, acid soils are limed to fix aluminium and iron but this practice is not economical. The practice is also not environmentally friendly. This study was conducted to improve phosphorus availability using organic amendments (biochar and compost produced from chicken litter and pineapple leaves, resp.) to fix aluminium and iron instead of phosphorus. Amending soil with biochar or compost or a mixture of biochar and compost increased total phosphorus, available phosphorus, inorganic phosphorus fractions (soluble inorganic phosphorus, aluminium bound inorganic phosphorus, iron bound inorganic phosphorus, redundant soluble inorganic phosphorus, and calcium bound phosphorus), and organic phosphorus. This was possible because the organic amendments increased soil pH and reduced exchangeable acidity, exchangeable aluminium, and exchangeable iron. The findings suggest that the organic amendments altered soil chemical properties in a way that enhanced the availability of phosphorus in this study. The amendments effectively fixed aluminium and iron instead of phosphorus, thus rendering phosphorus available by keeping the inorganic phosphorus in a bioavailable labile phosphorus pool for a longer period compared with application of Triple Superphosphate without organic amendments.

  20. Improving Phosphorus Availability in an Acid Soil Using Organic Amendments Produced from Agroindustrial Wastes

    Directory of Open Access Journals (Sweden)

    Huck Ywih Ch’ng

    2014-01-01

    Full Text Available In acid soils, soluble inorganic phosphorus is fixed by aluminium and iron. To overcome this problem, acid soils are limed to fix aluminium and iron but this practice is not economical. The practice is also not environmentally friendly. This study was conducted to improve phosphorus availability using organic amendments (biochar and compost produced from chicken litter and pineapple leaves, resp. to fix aluminium and iron instead of phosphorus. Amending soil with biochar or compost or a mixture of biochar and compost increased total phosphorus, available phosphorus, inorganic phosphorus fractions (soluble inorganic phosphorus, aluminium bound inorganic phosphorus, iron bound inorganic phosphorus, redundant soluble inorganic phosphorus, and calcium bound phosphorus, and organic phosphorus. This was possible because the organic amendments increased soil pH and reduced exchangeable acidity, exchangeable aluminium, and exchangeable iron. The findings suggest that the organic amendments altered soil chemical properties in a way that enhanced the availability of phosphorus in this study. The amendments effectively fixed aluminium and iron instead of phosphorus, thus rendering phosphorus available by keeping the inorganic phosphorus in a bioavailable labile phosphorus pool for a longer period compared with application of Triple Superphosphate without organic amendments.

  1. Influence of dissolved organic carbon on the efficiency of P sequestration by a lanthanum modified clay

    DEFF Research Database (Denmark)

    Dithmer, Line; Nielsen, Ulla Gro; Lundberg, Daniel

    2016-01-01

    A laboratory scale experiment was set up to test the effect of dissolved organic carbon (DOC) as well as ageing of the La–P complex formed during phosphorus (P) sequestration by a La modified clay (Phoslock®). Short term (7 days) P adsorption studies revealed a significant negative effect of added...... DOC on the P sequestration of Phoslock®, whereas a long-term P adsorption experiment revealed that the negative effect of added DOC was reduced with time. The reduced P binding efficiency is kinetic, as evident from solid-state 31P magic-angle spinning (MAS) NMR spectroscopy, who showed that the P...

  2. 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

  3. Interactions of diuron with dissolved organic matter from organic amendments.

    Science.gov (United States)

    Thevenot, Mathieu; Dousset, Sylvie; Hertkorn, Norbert; Schmitt-Kopplin, Philippe; Andreux, Francis

    2009-07-01

    Diuron is frequently detected in some drinking water reservoirs under the Burgundy vineyards, where organic amendments are applied. The environmental effect of these amendments on pesticide transport is ambiguous: on the one hand it could enhance their retention by increasing soil organic carbon content; on the other hand, dissolved organic matter (DOM) could facilitate their transport. Elutions were performed using columns packed with glass beads in order to investigate DOM-diuron interactions, and the possible co-transport of diuron and DOM. Four organic amendments (A, B, C and D) were tested; C and D were sampled at fresh (F) and mature (M) stages. An increase in diuron leaching was observed only for A and D(F) amendments (up to 16% compared to the DOM-free blank samples), suggesting a DOM effect on diuron transport. These results could be explained by the higher DOM leaching for A and D(F) compared to B, C(F), C(M) and D(M) increasing diuron-DOM interactions. These interactions seem to be related to the aromatic and aliphatic content of the DOM, determining formation of hydrogen and non-covalent bonds. The degree of organic matter maturity does not seem to have any effect with amendment C, while a reduction in diuron leaching is observed between D(F) and D(M). After equilibrium dialysis measurement of diuron-DOM complexes, it appeared that less than 3% of the diuron applied corresponded to complexes with a molecular weight >1000 Da. Complexes <1000 Da could also take part in this facilitated transport.

  4. 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...

  5. Relationships between colored dissolved organic matter and dissolved organic carbon in different coastal gradients of the Baltic Sea

    OpenAIRE

    Harvey, E. Therese; Kratzer, Susanne; Andersson, Agneta

    2015-01-01

    Due to high terrestrial runoff, the Baltic Sea is rich in dissolved organic carbon (DOC), the light-absorbing fraction of which is referred to as colored dissolved organic matter (CDOM). Inputs of DOC and CDOM are predicted to increase with climate change, affecting coastal ecosystems. We found that the relationships between DOC, CDOM, salinity, and Secchi depth all differed between the two coastal areas studied; the W Gulf of Bothnia with high terrestrial input and the NW Baltic Proper with ...

  6. Determination of total organic phosphorus in samples of mineral soils

    Directory of Open Access Journals (Sweden)

    Armi Kaila

    1962-01-01

    Full Text Available In this paper some observations on the estimation of organic phosphorus in mineral soils are reported. The fact is emphasized that the accuracy of all the methods available is relatively poor. Usually, there are no reasons to pay attention to differences less than about 20 ppm. of organic P. Analyses performed on 345 samples of Finnish mineral soils by the extraction method of MEHTA et. al. (10 and by a simple procedure adopted by the author (successive extractions with 4 N H2SO4 and 0.5 N NaOH at room temperature in the ratio of 1 to 100 gave, on the average, equal results. It seemed to be likely that the MEHTA method removed the organic phosphorus more completely than did the less vigorous method, but in the former the partial hydrolysis of organic phosphorus compounds tends to be higher than in the latter. An attempt was made to find out whether the differences between the respective values for organic phosphorus obtained by an ignition method and the simple extraction method could be connected with any characteristics of the soil. No correlation or only a low correlation coefficient could be calculated between the difference in the results of these two methods and e. g. the pH-value, the content of clay, organic carbon, aluminium and iron soluble in Tamm’s acid oxalate, the indicator of the phosphate sorption capacity, or the »Fe-bound» inorganic phosphorus, respectively. The absolute difference tended to increase with an increase in the content of organic phosphorus. For the 250 samples of surface soils analyzed, the ignition method gave values which were, on the average, about 50 ppm. higher than the results obtained by the extraction procedure. The corresponding difference for the 120 samples from deeper layers was about 20 ppm of organic P. The author recommends, for the present, the determination of the total soil organic phosphorus as an average of the results obtained by the ignition method and the extraction method.

  7. Phosphorus organic extragents and sorbents of radioactive a heavy metals

    International Nuclear Information System (INIS)

    Trofimov, B.A.; Gusarova, N.K.; Malysheva, S.F.; Sukhov, B.G.

    2002-01-01

    A fundamentally new method for activation of phosphorus in heterogenous super-base media including the conditions of mechanical, ultrasonic and X-ray activation, opening up a new way to C-P bond formation is developed. The method is opens principally new possibilities for direct atom-economic synthesis of previously unknown or difficult to obtain organophosphorus compounds (primary, secondary, tertiary phosphines and phosphine oxides) from elemental phosphorus and orga-nyl halides, electrophilic alkenes, acetylenes and oxiranes. Thus, the phosphothion and phosphorylation of organic compounds with elemental phosphorus, phosphines and phosphine oxides opens the principal new approach to the synthesis of specific and selective extra-gents, sorbents and complex-forming agents which can be used in the processes of purification and disinfecting of soil and water from radioactive and heavy metals

  8. Towards an understanding of feedbacks between plant productivity, acidity and dissolved organic matter

    Science.gov (United States)

    Rowe, Ed; Tipping, Ed; Davies, Jessica; Monteith, Don; Evans, Chris

    2014-05-01

    The recent origin of much dissolved organic carbon (DOC) (Tipping et al., 2010) implies that plant productivity is a major control on DOC fluxes. However, the flocculation, sorption and release of potentially-dissolved organic matter are governed by pH, and widespread increases in DOC concentrations observed in northern temperate freshwater systems seem to be primarily related to recovery from acidification (Monteith et al., 2007). We explore the relative importance of changes in productivity and pH using a model, MADOC, that incorporates both these effects (Rowe et al., 2014). The feedback whereby DOC affects pH is included. The model uses an annual timestep and relatively simple flow-routing, yet reproduces observed changes in DOC flux and pH in experimental (Evans et al., 2012) and survey data. However, the first version of the model probably over-estimated responses of plant productivity to nitrogen (N) deposition in upland semi-natural ecosystems. There is a strong case that plant productivity is an important regulator of DOC fluxes, and theoretical reasons for suspecting widespread productivity increases in recent years due not only to N deposition but to temperature and increased atmospheric CO2 concentrations. However, evidence that productivity has increased in upland semi-natural ecosystems is sparse, and few studies have assessed the major limitations to productivity in these habitats. In systems where phosphorus (P) limitation prevails, or which are co-limited, productivity responses to anthropogenic drivers will be limited. We present a revised version of the model that incorporates P cycling and appears to represent productivity responses to atmospheric N pollution more realistically. Over the long term, relatively small fluxes of nutrient elements into and out of ecosystems can profoundly affect productivity and the accumulation of organic matter. Dissolved organic N (DON) is less easily intercepted by plants and microbes than mineral N, and DON

  9. Production of dissolved organic carbon in aquatic sediment suspensions

    NARCIS (Netherlands)

    Koelmans, A.A.; Prevo, L.

    2003-01-01

    In many water quality models production of dissolved organic carbon (DOC) is modelled as mineralisation from particulate organic matter (POM). In this paper it is argued that the DOC production from dessicated sediments by water turbulence may be of similar importance
    In many water quality

  10. Dilution limits dissolved organic carbon utilization in the deep ocean

    NARCIS (Netherlands)

    Arrieta, J.M.; Mayol, E.; Hansman, R.L.; Herndl, G.J.; Dittmar, T.; Duarte, C.M.

    2015-01-01

    Oceanic dissolved organic carbon (DOC) is the second largest reservoir of organic carbon in the biosphere. About 72% of the global DOC inventory is stored in deep oceanic layers for years to centuries, supporting the current view that it consists of materials resistant to microbial degradation. An

  11. Dissolved organic carbon and dissolved organic nitrogen data collected using bottle in a world wide distribution from 02 September 1998 to 02 November 2003 (NODC Accession 0002403)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) data were collected using bottle casts in a world wide distribution. Data were collected from 02...

  12. 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.

  13. Uranium bioprecipitation mediated by yeasts utilizing organic phosphorus substrates.

    Science.gov (United States)

    Liang, Xinjin; Csetenyi, Laszlo; Gadd, Geoffrey Michael

    2016-06-01

    In this research, we have demonstrated the ability of several yeast species to mediate U(VI) biomineralization through uranium phosphate biomineral formation when utilizing an organic source of phosphorus (glycerol 2-phosphate disodium salt hydrate (C3H7Na2O6P·xH2O (G2P)) or phytic acid sodium salt hydrate (C6H18O24P6·xNa(+)·yH2O (PyA))) in the presence of soluble UO2(NO3)2. The formation of meta-ankoleite (K2(UO2)2(PO4)2·6(H2O)), chernikovite ((H3O)2(UO2)2(PO4)2·6(H2O)), bassetite (Fe(++)(UO2)2(PO4)2·8(H2O)), and uramphite ((NH4)(UO2)(PO4)·3(H2O)) on cell surfaces was confirmed by X-ray diffraction in yeasts grown in a defined liquid medium amended with uranium and an organic phosphorus source, as well as in yeasts pre-grown in organic phosphorus-containing media and then subsequently exposed to UO2(NO3)2. The resulting minerals depended on the yeast species as well as physico-chemical conditions. The results obtained in this study demonstrate that phosphatase-mediated uranium biomineralization can occur in yeasts supplied with an organic phosphate substrate as sole source of phosphorus. Further understanding of yeast interactions with uranium may be relevant to development of potential treatment methods for uranium waste and utilization of organic phosphate sources and for prediction of microbial impacts on the fate of uranium in the environment.

  14. Fluorescent dissolved organic matter in the continental shelf waters ...

    Indian Academy of Sciences (India)

    Fluorescent dissolved organic matter (FDOM) of southwestern Bay of Bengal surface water during southwest monsoon consisted five fluorophores, three humic-like and two protein-like. The humification index (HIX) and humic fluorophores, viz., visible (C), marine (M) and UV (A) humic-likes indicated, better than ...

  15. Degradation of riverine dissolved organic matter by seawater bacteria

    NARCIS (Netherlands)

    Rochelle-Newall, E.J.; Pizay, M-D.; Middelburg, J.J.; Boschker, H.T.S.; Gattuso, J.P.

    2004-01-01

    The functional response of a seawater bacterial community transplanted into freshwater dissolved organic matter (DOM) was investigated together with the response of natural populations of bacteria to size-fractioned natural source water. Seawater bacteria were incubated over a period of 8 d in

  16. 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.

  17. Hydrological Variables and Dissolved Phosphorus in the Runoff from No-tilled Soil after Application of Swine Liquid

    Science.gov (United States)

    Barbosa, F. T.; Bertol, I.; de Amaral, A. J.; Grahl dos Santos, P.; Ramos, R. R.; Werner, R. S.; Miras Avalos, J. M.

    2012-04-01

    Swine manure is used as a soil fertilizer in South Brazil. Commonly, it is applied continuously and in great amounts over surfaces with an important relief and without facilities that avoid water erosion. Thus, this manure is a potential risk of environmental pollution, mainly for the eutrophication of water bodies due to a runoff rich in nutrients. The aim of this work was to assess some soil hydrological parameters and to quantify the dissolved phosphorus losses in the runoff from no-tilled soils after the application of swine liquid manure. The experiment was carried out in the Highlands of Santa Catarina State, Brazil, in June 2009, over a Nitisol. On field plots, a 90-minute simulated rainfall test was performed with a rotating boom rainfall simulator and rainfall intensity of 70 mm h-1. Prior to the rainfall simulation, sowing was performed using a disk planter either with or without tines. Spacing between lines was 0.5 m. Swine liquid manure was applied at rates of 0.0, 30 and 60 m3ha-1 to the plots planted using tines; whereas it was applied at 15, 45 e 75 m3ha-1 to the plots were no tines were used for planting. During rainfall simulation, readings of runoff rate were taken each five minutes; total water loss was calculated by integrating all the 5-minute readings. Runoff samples were collected at 10 minutes intervals, and they were filtered through a 0.45 μm filter to determine dissolved phosphorus. Hydrological variables were significantly affected by the use of tines, which favoured infiltration and reduced runoff as compared to the non-use of tines. Runoff started at 28 and 11 minutes, water losses were 252 and 467 m3 ha-1, maximum runoff rate were 29 and 42 mm h-1 and constant rates of infiltration were 41 and 28 mm h-1, for treatments with and without tines, respectively. Dissolved phosphorus increased with the rate of swine liquid manure applied, with a trend to decrease from the beginning to the end of rainfall. The highest concentration was 0

  18. [Vermicomposting of different organic materials and three-dimensional excitation emission matrix fluorescence spectroscopic characterization of their dissolved organic matter].

    Science.gov (United States)

    Yang, Wei; Wang, Dong-sheng; Liu, Man-qiang; Hu, Feng; Li, Hui-xin; Huang, Zhong-yang; Chang, Yi-jun; Jiao, Jia-guo

    2015-10-01

    In this experiment, different proportions of the cattle manure, tea-leaf, herb and mushroom residues, were used as food for earthworm (Eisenia fetida) to study the growth of the earth-worm. Then the characteristics and transformation of nutrient content and three-dimensional excitation emission matrix fluorescence (3DEEM) of dissolved organic matter (DOM) during vermistabilization were investigated by means of chemical and spectroscopic methods. The result showed that the mixture of different ratios of cattle manure with herb residue, and cattle manure with tea-leaf were conducive to the growth of earthworm, while the materials compounded with mushroom residue inhibited the growth of earthworm. With the increasing time of verimcomposting, the pH in vermicompost tended to be circumneutral and weakly acidic, and there were increases in electrical conductivity, and the contents of total nitrogen, total phosphorus, available nitrogen, and available phosphorus, while the total potassium and available potassium increased first and then decreased, and the organic matter content decreased. 3DEEM and fluorescence regional integration results indicated that, the fluorescence of protein-like fluorescence peaks declined significantly, while the intensity of humic-like fluorescence peak increased significantly in DOM. Vermicomposting process might change the compositions of DOM with elevated concentrations of humic acid and fulvic acid in the organics. In all, this study suggested the suitability of 3DEEM for monitoring the organics transformation and assessing the maturity in the vermicomposting.

  19. Dissolving mechanism of strain P17 on insoluble phosphorus of yellow-brown soil

    Directory of Open Access Journals (Sweden)

    Zhong Chuan-qing

    2014-09-01

    Full Text Available Strain P17 was a bacterial strain identified as Bacillus megaterium isolated from ground accumulating phosphate rock powder. The fermentation broth of strain P17 and the yellow-brown soil from Nanjing Agricultural University garden were collected to conduct this study. The simulation of fixed insoluble phosphorous forms after applying calcium superphosphate into yellow-brown soil was performed in pots, while available P and total P of soil were extremely positive correlative with those of groundwater. Then the dissolving effect of strain P17 on insoluble P of yellow-brown soil was studied. Results showed that Bacillus megaterium strain P17 had notable solubilizing effect on insoluble phosphates formed when too much water-soluble phosphorous fertilizer used. During 100 days after inoculation, strain P17 was dominant. Until the 120th day, compared with water addition, available P of strain P17 inoculation treated soil increased by 3 times with calcium superphosphate addition. Besides available P, pH, activity of acid and alkaline phosphatase and population of P-solubilizing microbes were detected respectively. P-solubilizing mechanism of P-solubilizing bacteria strain P17 seems to be a synergetic effect of pH decrease, organic acids, phosphatase, etc.

  20. Production of Dissolved Organic Matter During Doliolid Feeding

    Science.gov (United States)

    Castellane, N. J.; Paffenhofer, G. A.; Stubbins, A.

    2016-02-01

    The biological carbon pump (BCP) draws carbon dioxide out of the atmosphere and buries it at the seafloor. The efficiency of the BCP is determined in part by the sinking rates of particulate organic carbon (POC) from ocean surface waters. Zooplankton can package POC into fecal pellets with higher sinking rates than their food source (e.g. phytoplankton), increasing the efficiency of the BCP. However, dissolved organic carbon (DOC) is also produced as zooplankton ingest and egest food, reducing the efficiency of BCP. The pelagic tunicate Dolioletta gegenbauri (doliolid) is a gelatinous zooplankton found at high concentrations in shelf waters, including our study site: the South Atlantic Bight. Doliolids are efficient grazers capable of stripping large quantities of phytoplankton from the water column. To determine the balance between pellet formation and DOC production during feeding, doliolids (6-7 mm gonozooids) were placed in natural seawater amended with a live phytoplankton food source and incubated on a plankton wheel. Dissolved organic matter (DOM) released directly to the water as well as the water soluble fraction of pellet organic matter were quantified and optically characterized. Colored dissolved organic matter (CDOM) absorbance and fluorescence spectra revealed that doliolid feeding produces DOM with optical properties that are commonly indicative of newly produced, highly biolabile DOM of microbial origin. Based upon these optical characteristics, doliolid-produced DOM is expected to be highly bio-labile in the environment and therefore rapidly degraded by surface ocean microbes shunting phytoplankton-derived organic carbon out of the BCP and back to dissolved inorganic carbon.

  1. Iron traps terrestrially derived dissolved organic matter at redox interfaces

    Science.gov (United States)

    Riedel, Thomas; Zak, Dominik; Biester, Harald; Dittmar, Thorsten

    2013-01-01

    Reactive iron and organic carbon are intimately associated in soils and sediments. However, to date, the organic compounds involved are uncharacterized on the molecular level. At redox interfaces in peatlands, where the biogeochemical cycles of iron and dissolved organic matter (DOM) are coupled, this issue can readily be studied. We found that precipitation of iron hydroxides at the oxic surface layer of two rewetted fens removed a large fraction of DOM via coagulation. On aeration of anoxic fen pore waters, >90% of dissolved iron and 27 ± 7% (mean ± SD) of dissolved organic carbon were rapidly (within 24 h) removed. Using ultra-high-resolution MS, we show that vascular plant-derived aromatic and pyrogenic compounds were preferentially retained, whereas the majority of carboxyl-rich aliphatic acids remained in solution. We propose that redox interfaces, which are ubiquitous in marine and terrestrial settings, are selective yet intermediate barriers that limit the flux of land-derived DOM to oceanic waters. PMID:23733946

  2. A linear solvation energy relationship model of organic chemical partitioning to dissolved organic carbon.

    Science.gov (United States)

    Kipka, Undine; Di Toro, Dominic M

    2011-09-01

    Predicting the association of contaminants with both particulate and dissolved organic matter is critical in determining the fate and bioavailability of chemicals in environmental risk assessment. To date, the association of a contaminant to particulate organic matter is considered in many multimedia transport models, but the effect of dissolved organic matter is typically ignored due to a lack of either reliable models or experimental data. The partition coefficient to dissolved organic carbon (K(DOC)) may be used to estimate the fraction of a contaminant that is associated with dissolved organic matter. Models relating K(DOC) to the octanol-water partition coefficient (K(OW)) have not been successful for many types of dissolved organic carbon in the environment. Instead, linear solvation energy relationships are proposed to model the association of chemicals with dissolved organic matter. However, more chemically diverse K(DOC) data are needed to produce a more robust model. For humic acid dissolved organic carbon, the linear solvation energy relationship predicts log K(DOC) with a root mean square error of 0.43. Copyright © 2011 SETAC.

  3. Production of fluorescent dissolved organic matter in Arctic Ocean sediments

    Science.gov (United States)

    Chen, Meilian; Kim, Ji-Hoon; Nam, Seung-Il; Niessen, Frank; Hong, Wei-Li; Kang, Moo-Hee; Hur, Jin

    2016-12-01

    Little is known about the production of fluorescent dissolved organic matter (FDOM) in the anoxic oceanic sediments. In this study, sediment pore waters were sampled from four different sites in the Chukchi-East Siberian Seas area to examine the bulk dissolved organic carbon (DOC) and their optical properties. The production of FDOM, coupled with the increase of nutrients, was observed above the sulfate-methane-transition-zone (SMTZ). The presence of FDOM was concurrent with sulfate reduction and increased alkalinity (R2 > 0.96, p  0.95, p CDOM and FDOM to the overlying water column, unearthing a channel of generally bio-refractory and pre-aged DOM to the oceans.

  4. RNA function and phosphorus use by photosynthetic organisms

    Directory of Open Access Journals (Sweden)

    John Albert Raven

    2013-12-01

    Full Text Available Phosphorus (P in RNA accounts for half or more of the total non-storage P in oxygenic photolithotrophs grown in either P-replete or P-limiting growth conditions. Since many natural environments are P-limited for photosynthetic primary productivity, and peak phosphorus fertilizer production is forecast for the next few decades, the paper analyses what economies in P allocation to RNA could, in principle, increase P use efficiency of growth (rate of dry matter production per unit organism P. The possibilities of decreasing P allocation to RNA without decreasing growth rate include a more widespread down-regulation of RNA production in P-limited organisms (as in the growth rate hypothesis, optimal allocation of P to RNA spatially among cell compartments and organs, and temporally depending on the stage of growth, and, for exponentially growing organisms with a constant fraction of P in RNA, a constant rate of protein synthesis through the diel cycle. Acting on these suggestions would be technically demanding, and could have unintended consequences for other aspect of metabolism.

  5. Dissolved Organic Matter (DOM) Export from Watersheds to Coastal Oceans

    Science.gov (United States)

    Chen, R. F.; Gardner, G. B.; Peri, F.

    2016-02-01

    Dissolved organic matter (DOM) from terrestrial plants and soils is transported by surface waters and groundwaters to coastal ocean waters. Along the way, photochemical and biological degradation can remove DOM, and in situ processes such as phytoplankton leaching and sediment sources can add to the DOM in the river water. Wetlands, especially coastal wetlands can add significant amounts of DOM that is carried by rivers and is exported through estuaries to coastal systems. We will present observational data from a variety of coastal systems (San Francisco Bay, Boston Harbor, Chesapeake Bay, Hudson River, the Mississippi River, and a small salt marsh in the Gulf of Mexico). High resolution measurements of chromophoric dissolved organic matter (CDOM) can be correlated with dissolved organic carbon (DOC) so can be used to estimate DOC in specific systems and seasons. Gradients in CDOM/DOC combined with water fluxes can be used to estimate DOC fluxes from a variety of coastal watersheds to coastal systems. Influences of land use, system size, residence time, DOM quality, and photochemical and biological degradation will be discussed. The significance of coastal wetlands in the land-to-ocean export of DOC will be emphasized.

  6. 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.

  7. Soluble organic nutrient fluxes

    Science.gov (United States)

    Robert G. Qualls; Bruce L. Haines; Wayne Swank

    2014-01-01

    Our objectives in this study were (i) compare fluxes of the dissolved organic nutrients dissolved organic carbon (DOC), DON, and dissolved organic phosphorus (DOP) in a clearcut area and an adjacent mature reference area. (ii) determine whether concentrations of dissolved organic nutrients or inorganic nutrients were greater in clearcut areas than in reference areas,...

  8. Relationships between colored dissolved organic matter and dissolved organic carbon in different coastal gradients of the Baltic Sea.

    Science.gov (United States)

    Harvey, E Therese; Kratzer, Susanne; Andersson, Agneta

    2015-06-01

    Due to high terrestrial runoff, the Baltic Sea is rich in dissolved organic carbon (DOC), the light-absorbing fraction of which is referred to as colored dissolved organic matter (CDOM). Inputs of DOC and CDOM are predicted to increase with climate change, affecting coastal ecosystems. We found that the relationships between DOC, CDOM, salinity, and Secchi depth all differed between the two coastal areas studied; the W Gulf of Bothnia with high terrestrial input and the NW Baltic Proper with relatively little terrestrial input. The CDOM:DOC ratio was higher in the Gulf of Bothnia, where CDOM had a greater influence on the Secchi depth, which is used as an indicator of eutrophication and hence important for Baltic Sea management. Based on the results of this study, we recommend regular CDOM measurements in monitoring programmes, to increase the value of concurrent Secchi depth measurements.

  9. Effect of irrigation regimes on mobilization of nonreactive tracers and dissolved and particulate phosphorus in slurry-injected soils

    DEFF Research Database (Denmark)

    Glæsner, Nadia; Kjærgaard, Charlotte; Rubæk, Gitte Holton

    2011-01-01

    affected by the irrigation regime. These results highlight that nonequilibrium exchange dynamics are important when evaluating processes affecting mobilization and transport in structured soils. Leaching experiments, including cycles of irrigation interruptions and gravitational drainage, thus, adds......Understanding the mobilization processes of phosphorus (P) in the plow layer are essential to quantify potential P losses and suggest management strategies to reduce P losses. This study is aimed at examining nonequilibrium exchange dynamics on the mobilization of slurry-amended Br−, and dissolved...... and particulate P in slurry-injected soils. We compared leaching from intact soil columns (20 cm diam., 20 cm high) under unsaturated flow (suction at the lower boundary of 5 hPa) subjected to continuous irrigation at 2 mm hr−1, and intermittent irrigation at 2 mm hr−1 and 10 mm hr−1 to with interruptions of 10 h...

  10. Coagulation and flocculation of dissolved organic substances with organic polymers

    OpenAIRE

    Kvinnesland, Thomas

    2002-01-01

    Coagulation of natural organic matter (NOM) in water is a well-established process, enabling or enhancing the removal of these substances by different particle separation processes. The dominating coagulating agents used are, however, inorganic salts of iron (Fe3+) and aluminium (Al3+). The primary use of organic polymers is as flocculating agents for already coagulated aggregates. However, in recent years the use of cationic organic polymers have received increasing attent...

  11. Prediction of dissolved reactive phosphorus losses from small agricultural catchments: calibration and validation of a parsimonious model

    Directory of Open Access Journals (Sweden)

    C. Hahn

    2013-10-01

    Full Text Available Eutrophication of surface waters due to diffuse phosphorus (P losses continues to be a severe water quality problem worldwide, causing the loss of ecosystem functions of the respective water bodies. Phosphorus in runoff often originates from a small fraction of a catchment only. Targeting mitigation measures to these critical source areas (CSAs is expected to be most efficient and cost-effective, but requires suitable tools. Here we investigated the capability of the parsimonious Rainfall-Runoff-Phosphorus (RRP model to identify CSAs in grassland-dominated catchments based on readily available soil and topographic data. After simultaneous calibration on runoff data from four small hilly catchments on the Swiss Plateau, the model was validated on a different catchment in the same region without further calibration. The RRP model adequately simulated the discharge and dissolved reactive P (DRP export from the validation catchment. Sensitivity analysis showed that the model predictions were robust with respect to the classification of soils into "poorly drained" and "well drained", based on the available soil map. Comparing spatial hydrological model predictions with field data from the validation catchment provided further evidence that the assumptions underlying the model are valid and that the model adequately accounts for the dominant P export processes in the target region. Thus, the parsimonious RRP model is a valuable tool that can be used to determine CSAs. Despite the considerable predictive uncertainty regarding the spatial extent of CSAs, the RRP can provide guidance for the implementation of mitigation measures. The model helps to identify those parts of a catchment where high DRP losses are expected or can be excluded with high confidence. Legacy P was predicted to be the dominant source for DRP losses and thus, in combination with hydrologic active areas, a high risk for water quality.

  12. Influence of allochthonous dissolved organic matter on pelagic basal production in a northerly estuary

    Science.gov (United States)

    Andersson, A.; Brugel, S.; Paczkowska, J.; Rowe, O. F.; Figueroa, D.; Kratzer, S.; Legrand, C.

    2018-05-01

    Phytoplankton and heterotrophic bacteria are key groups at the base of aquatic food webs. In estuaries receiving riverine water with a high content of coloured allochthonous dissolved organic matter (ADOM), phytoplankton primary production may be reduced, while bacterial production is favoured. We tested this hypothesis by performing a field study in a northerly estuary receiving nutrient-poor, ADOM-rich riverine water, and analyzing results using multivariate statistics. Throughout the productive season, and especially during the spring river flush, the production and growth rate of heterotrophic bacteria were stimulated by the riverine inflow of dissolved organic carbon (DOC). In contrast, primary production and photosynthetic efficiency (i.e. phytoplankton growth rate) were negatively affected by DOC. Primary production related positively to phosphorus, which is the limiting nutrient in the area. In the upper estuary where DOC concentrations were the highest, the heterotrophic bacterial production constituted almost 100% of the basal production (sum of primary and bacterial production) during spring, while during summer the primary and bacterial production were approximately equal. Our study shows that riverine DOC had a strong negative influence on coastal phytoplankton production, likely due to light attenuation. On the other hand DOC showed a positive influence on bacterial production since it represents a supplementary food source. Thus, in boreal regions where climate change will cause increased river inflow to coastal waters, the balance between phytoplankton and bacterial production is likely to be changed, favouring bacteria. The pelagic food web structure and overall productivity will in turn be altered.

  13. Comparing dissolved reactive phosphorus measured by DGT with ferrihydrite and titanium dioxide adsorbents

    DEFF Research Database (Denmark)

    Panther, Jared G.; Teasdale, Peter R.; Bennett, William W.

    2011-01-01

    Two adsorbents (Metsorb and ferrihydrite) used in binding layers with the diffusive gradients in a thin film technique were evaluated for the measurement of dissolved reactive phosphorous (DRP) in synthetic and natural waters. Possible interferences were investigated with Cl- (up to 1.35molL-1) a...

  14. Sea cucumbers reduce chromophoric dissolved organic matter in aquaculture tanks.

    Science.gov (United States)

    Sadeghi-Nassaj, Seyed Mohammad; Catalá, Teresa S; Álvarez, Pedro A; Reche, Isabel

    2018-01-01

    Mono-specific aquaculture effluents contain high concentrations of nutrients and organic matter, which affect negatively the water quality of the recipient ecosystems. A fundamental feature of water quality is its transparency. The fraction of dissolved organic matter that absorbs light is named chromophoric dissolved organic matter (CDOM). A sustainable alternative to mono-specific aquaculture is the multitrophic aquaculture that includes species trophically complementary named "extractive" species that uptake the waste byproducts. Sea cucumbers are recognized as efficient extractive species due to the consumption of particulate organic matter (POM). However, the effects of sea cucumbers on CDOM are still unknown. During more than one year, we monitored CDOM in two big-volume tanks with different trophic structure. One of the tanks (-holothurian) only contained around 810 individuals of Anemonia sulcata , whereas the other tank (+holothurian) also included 90 individuals of Holothuria tubulosa and Holothuria forskali . We routinely analyzed CDOM absorption spectra and determined quantitative (absorption coefficients at 325 nm) and qualitative (spectral slopes) optical parameters in the inlet waters, within the tanks, and in their corresponding effluents. To confirm the time-series results, we also performed three experiments. Each experiment consisted of two treatments: +holothurians (+H) and -holothurians (-H). We set up three +H tanks with 80 individuals of A. sulcata and 10 individuals of H. tubulosa in each tank and four -H tanks that contained only 80 individuals of A. sulcata . In the time-series, absorption coefficients at 325 nm ( a 325 ) and spectral slopes from 275 to 295 nm ( S 275-295 ) were significantly lower in the effluent of the +holothurian tank (average: 0.33 m -1 and 16 µm -1 , respectively) than in the effluent of the -holothurian tank (average: 0.69 m -1 and 34 µm -1 , respectively), the former being similar to those found in the inlet

  15. Experimental Evidence for Abiotic Sulfurization of Marine Dissolved Organic Matter

    Directory of Open Access Journals (Sweden)

    Anika M. Pohlabeln

    2017-11-01

    Full Text Available Dissolved organic sulfur (DOS is the largest pool of organic sulfur in the oceans, and as such it is an important component of the global sulfur cycle. DOS in the ocean is resistant against microbial degradation and turns over on a millennium time scale. However, sources and mechanisms behind its stability are largely unknown. Here, we hypothesize that in sulfate-reducing sediments sulfur is abiotically incorporated into dissolved organic matter (DOM and released to the ocean. We exposed natural seawater and the filtrate of a plankton culture to sulfidic conditions. Already after 1-h at 20°C, DOS concentrations had increased 4-fold in these experiments, and 14-fold after 4 weeks at 50°C, indicating that organic matter does not need long residence times in natural sulfidic environments to be affected by sulfurization. Molecular analysis via ultrahigh-resolution mass spectrometry showed that sulfur was covalently and unselectively bound to DOM. Experimentally produced and natural DOS from sediments were highly similar on a molecular and structural level. By combining our data with published benthic DOC fluxes we estimate that 30–200 Tg DOS are annually transported from anaerobic and sulfate reducing sediments to the oceans. Uncertainties in this first speculative assessment are large. However, this first attempt illustrates that benthic DOS flux is potentially one order of magnitude larger than that via rivers indicating that this could balance the estimated global net removal of refractory DOS.

  16. Overestimation of organic phosphorus in wetland soils by alkaline extraction and molybdate colorimetry.

    Science.gov (United States)

    Turner, Benjamin L; Newman, Susan; Reddy, K Ramesh

    2006-05-15

    Accurate information on the chemical nature of soil phosphorus is essential for understanding its bioavailability and fate in wetland ecosystems. Solution phosphorus-31 nuclear magnetic resonance (31P NMR) spectroscopy was used to assess the conventional colorimetric procedure for phosphorus speciation in alkaline extracts of organic soils from the Florida Everglades. Molybdate colorimetry markedly overestimated organic phosphorus by between 30 and 54% compared to NMR spectroscopy. This was due in large part to the association of inorganic phosphate with organic matter, although the error was exacerbated in some samples by the presence of pyrophosphate, an inorganic polyphosphate that is not detected by colorimetry. The results have important implications for our understanding of phosphorus biogeochemistry in wetlands and suggest that alkaline extraction and solution 31p NMR spectroscopy is the only accurate method for quantifying organic phosphorus in wetland soils.

  17. 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.

  18. Influence of Organic Manure on Organic Phosphorus Fraction in Soils

    Institute of Scientific and Technical Information of China (English)

    ZHANGYONG-SONG; NIWU-ZHONG; 等

    1993-01-01

    The transformation of organic P(Po) from organic manures in two types of soils (ultisol and entisol) and the influences of external addition of organic substance or inorganic P(Pi) on Po under the condition of the 60% maximum water capacity were investigated.The results obtained from Po fractionation experiments indicated that all the Po fractions except for the highly resistant Po fraction decreased during incubation.Application of pig feces and cow feces could largely increase each fraction of Po in the soils.Immediately after application of organic manure into the soils a large part of labile and moderately labile Po from organic manure was transferred into moderately resistant Po,which might be due to the fact that Ca-or Mg-inositol P was precipitated into Fe-inositol P.However,the availability of Po from organic manure in the soils would increase again after incubation because of the transformation of moderately labile and resistant Po fractions into labile Po fractions.Addition of cellulose or Pi into the soils showed a good effect on increasing all the Po fractions except for the highly resistant Po,and this effect was much more pronounced when cellulose was applied in combination with Pi.Therefore,in view of the effect of organic manure on improving P nutrition to plant,attention should be paid to both the Po and the organic substances from organic manure,It is suggested that application of Pi fertilizer combined with organic manure may be referred to as an effective means of protecting Pi from chemical fixation in soil.

  19. Bioavailability of autochthonous dissolved organic nitrogen in marine plankton communities

    DEFF Research Database (Denmark)

    Knudsen, Helle; Markager, Svend Stiig; Søndergaard, Morten

    The purpose of this study was to investigate the bioavailability of dissolved organic nitrogen (DON) produced during a phytoplankton bloom. The experiments were conducted with natural plankton communities as batch growth experiments over approximately 30 days with nitrogen limitation. Five to six...... times during the exponential and stationary phases of each experimental bloom the bioavailability of DON was measured over 60 days together with DOC and oxygen consumption. The overall aim was to quantify remineralization of the added nitrate. The results showed that maximum 33 % of the added nitrate...

  20. 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.

  1. 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.

  2. Latitudinal gradients in degradation of marine dissolved organic carbon

    DEFF Research Database (Denmark)

    Arnosti, Carol; Steen, Andrew; Ziervogel, Kai

    2011-01-01

    unknown, since the vast majority of marine bacteria have not been isolated in culture, and most measurements of DOC degradation rates have focused on uptake and metabolism of either bulk DOC or of simple model compounds (e.g. specific amino acids or sugars). Genomic investigations provide information......Heterotrophic microbial communities cycle nearly half of net primary productivity in the ocean, and play a particularly important role in transformations of dissolved organic carbon (DOC). The specific means by which these communities mediate the transformations of organic carbon are largely...... about the potential capabilities of organisms and communities but not the extent to which such potential is expressed. We tested directly the capabilities of heterotrophic microbial communities in surface ocean waters at 32 stations spanning latitudes from 76 ºS to 79 ºN to hydrolyze a range of high...

  3. 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

  4. Terrestrial dissolved organic matter distribution in the North Sea.

    Science.gov (United States)

    Painter, Stuart C; Lapworth, Dan J; Woodward, E Malcolm S; Kroeger, Silke; Evans, Chris D; Mayor, Daniel J; Sanders, Richard J

    2018-07-15

    The flow of terrestrial carbon to rivers and inland waters is a major term in the global carbon cycle. The organic fraction of this flux may be buried, remineralized or ultimately stored in the deep ocean. The latter can only occur if terrestrial organic carbon can pass through the coastal and estuarine filter, a process of unknown efficiency. Here, data are presented on the spatial distribution of terrestrial fluorescent and chromophoric dissolved organic matter (FDOM and CDOM, respectively) throughout the North Sea, which receives organic matter from multiple distinct sources. We use FDOM and CDOM as proxies for terrestrial dissolved organic matter (tDOM) to test the hypothesis that tDOM is quantitatively transferred through the North Sea to the open North Atlantic Ocean. Excitation emission matrix fluorescence and parallel factor analysis (EEM-PARAFAC) revealed a single terrestrial humic-like class of compounds whose distribution was restricted to the coastal margins and, via an inverse salinity relationship, to major riverine inputs. Two distinct sources of fluorescent humic-like material were observed associated with the combined outflows of the Rhine, Weser and Elbe rivers in the south-eastern North Sea and the Baltic Sea outflow to the eastern central North Sea. The flux of tDOM from the North Sea to the Atlantic Ocean appears insignificant, although tDOM export may occur through Norwegian coastal waters unsampled in our study. Our analysis suggests that the bulk of tDOM exported from the Northwest European and Scandinavian landmasses is buried or remineralized internally, with potential losses to the atmosphere. This interpretation implies that the residence time in estuarine and coastal systems exerts an important control over the fate of tDOM and needs to be considered when evaluating the role of terrestrial carbon losses in the global carbon cycle. Copyright © 2018 The Author(s). Published by Elsevier B.V. All rights reserved.

  5. 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.

  6. Dissolved organic matter (DOM) export to a temperate estuary: Seasonal variations and implications of land use

    DEFF Research Database (Denmark)

    Stedmon, C. A.; Markager, S.; Søndergaard, M.

    2006-01-01

    Inputs of dissolved carbon, nitrogen, and phosphorus were assessed for an estuary and its catchment (Horsens, Denmark). Seasonal patterns in the concentrations of DOM in the freshwater supply to the estuary differed depending on the soil and drainage characteristics of the area. In streams draini...

  7. Chromophoric dissolved organic matter export from U.S. rivers

    Science.gov (United States)

    Spencer, Robert G. M.; Aiken, George R.; Dornblaser, Mark M.; Butler, Kenna D.; Holmes, R. Max; Fiske, Greg; Mann, Paul J.; Stubbins, Aron

    2013-04-01

    Chromophoric dissolved organic matter (CDOM) fluxes and yields from 15 major U.S. rivers draining an assortment of terrestrial biomes are presented. A robust relationship between CDOM and dissolved organic carbon (DOC) loads is established (e.g., a350 versus DOC; r2 = 0.96, p CDOM yields are also correlated to watershed percent wetland (e.g. a350; r2 = 0.81, p CDOM export from ungauged watersheds. A large variation in CDOM yields was found across the rivers. The two rivers in the north-eastern U.S. (Androscoggin and Penobscot), the Edisto draining into the South Atlantic Bight, and some rivers draining into the Gulf of Mexico (Atchafalaya and Mobile) exhibit the highest CDOM yields, linked to extensive wetlands in these watersheds. If the Edisto CDOM yield is representative of other rivers draining into the South Atlantic Bight, this would result in a CDOM load equivalent to that of the Mississippi from a region of approximately 10% of the Mississippi watershed, indicating the importance of certain regions with respect to the role of terrigenous CDOM in ocean color budgets.

  8. The global distribution and dynamics of chromophoric dissolved organic matter.

    Science.gov (United States)

    Nelson, Norman B; Siegel, David A

    2013-01-01

    Chromophoric dissolved organic matter (CDOM) is a ubiquitous component of the open ocean dissolved matter pool, and is important owing to its influence on the optical properties of the water column, its role in photochemistry and photobiology, and its utility as a tracer of deep ocean biogeochemical processes and circulation. In this review, we discuss the global distribution and dynamics of CDOM in the ocean, concentrating on developments in the past 10 years and restricting our discussion to open ocean and deep ocean (below the main thermocline) environments. CDOM has been demonstrated to exert primary control on ocean color by its absorption of light energy, which matches or exceeds that of phytoplankton pigments in most cases. This has important implications for assessing the ocean biosphere via ocean color-based remote sensing and the evaluation of ocean photochemical and photobiological processes. The general distribution of CDOM in the global ocean is controlled by a balance between production (primarily microbial remineralization of organic matter) and photolysis, with vertical ventilation circulation playing an important role in transporting CDOM to and from intermediate water masses. Significant decadal-scale fluctuations in the abundance of global surface ocean CDOM have been observed using remote sensing, indicating a potentially important role for CDOM in ocean-climate connections through its impact on photochemistry and photobiology.

  9. Chromophoric dissolved organic matter export from U.S. rivers

    Science.gov (United States)

    Spencer, Robert G. M.; Aiken, George R.; Dornblaser, Mark M.; Butler, Kenna D.; Holmes, R. Max; Fiske, Greg; Mann, Paul J.; Stubbins, Aron

    2013-01-01

    Chromophoric dissolved organic matter (CDOM) fluxes and yields from 15 major U.S. rivers draining an assortment of terrestrial biomes are presented. A robust relationship between CDOM and dissolved organic carbon (DOC) loads is established (e.g., a350 versus DOC; r2 = 0.96, p CDOM yields are also correlated to watershed percent wetland (e.g. a350; r2 = 0.81, p CDOM export from ungauged watersheds. A large variation in CDOM yields was found across the rivers. The two rivers in the north-eastern U.S. (Androscoggin and Penobscot), the Edisto draining into the South Atlantic Bight, and some rivers draining into the Gulf of Mexico (Atchafalaya and Mobile) exhibit the highest CDOM yields, linked to extensive wetlands in these watersheds. If the Edisto CDOM yield is representative of other rivers draining into the South Atlantic Bight, this would result in a CDOM load equivalent to that of the Mississippi from a region of approximately 10% of the Mississippi watershed, indicating the importance of certain regions with respect to the role of terrigenous CDOM in ocean color budgets.

  10. 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.

  11. Dilution limits dissolved organic carbon utilization in the deep ocean

    KAUST Repository

    Arrieta, Jesus

    2015-03-19

    Oceanic dissolved organic carbon (DOC) is the second largest reservoir of organic carbon in the biosphere. About 72% of the global DOC inventory is stored in deep oceanic layers for years to centuries, supporting the current view that it consists of materials resistant to microbial degradation. An alternative hypothesis is that deep-water DOC consists of many different, intrinsically labile compounds at concentrations too low to compensate for the metabolic costs associated to their utilization. Here, we present experimental evidence showing that low concentrations rather than recalcitrance preclude consumption of a substantial fraction of DOC, leading to slow microbial growth in the deep ocean. These findings demonstrate an alternative mechanism for the long-term storage of labile DOC in the deep ocean, which has been hitherto largely ignored. © 2015, American Association for the Advancement of Science. All rights reserved.

  12. Dilution limits dissolved organic carbon utilization in the deep ocean

    KAUST Repository

    Arrieta, J M; Mayol, Eva; Hansman, Roberta L.; Herndl, Gerhard J.; Dittmar, Thorsten; Duarte, Carlos M.

    2015-01-01

    Oceanic dissolved organic carbon (DOC) is the second largest reservoir of organic carbon in the biosphere. About 72% of the global DOC inventory is stored in deep oceanic layers for years to centuries, supporting the current view that it consists of materials resistant to microbial degradation. An alternative hypothesis is that deep-water DOC consists of many different, intrinsically labile compounds at concentrations too low to compensate for the metabolic costs associated to their utilization. Here, we present experimental evidence showing that low concentrations rather than recalcitrance preclude consumption of a substantial fraction of DOC, leading to slow microbial growth in the deep ocean. These findings demonstrate an alternative mechanism for the long-term storage of labile DOC in the deep ocean, which has been hitherto largely ignored. © 2015, American Association for the Advancement of Science. All rights reserved.

  13. THE ROLE OF NITROGEN IN CHROMOPHORIC AND FLUORESCENT DISSOLVED ORGANIC MATTER FORMATION

    Science.gov (United States)

    Microbial and photochemical processes affect chromophoric dissolved organic matter (CDOM) dynamics in the ocean. Some evidence suggests that dissolved nitrogen plays a role in CDOM formation, although this has received little systematic attention in marine ecosystems. Coastal sea...

  14. Dynamics of dissolved organic matter in fjord ecosystems: Contributions of terrestrial dissolved organic matter in the deep layer

    Science.gov (United States)

    Yamashita, Youhei; McCallister, S. Leigh; Koch, Boris P.; Gonsior, Michael; Jaffé, Rudolf

    2015-06-01

    Annually, rivers and inland water systems deliver a significant amount of terrestrial organic matter (OM) to the adjacent coastal ocean in both particulate and dissolved forms; however, the metabolic and biogeochemical transformations of OM during its seaward transport remains one of the least understood components of the global carbon cycle. This transfer of terrestrial carbon to marine ecosystems is crucial in maintaining trophic dynamics in coastal areas and critical in global carbon cycling. Although coastal regions have been proposed as important sinks for exported terrestrial materials, most of the global carbon cycling data, have not included fjords in their budgets. Here we present distributional patterns on the quantity and quality of dissolved OM in Fiordland National Park, New Zealand. Specifically, we describe carbon dynamics under diverse environmental settings based on dissolved organic carbon (DOC) depth profiles, oxygen concentrations, optical properties (fluorescence) and stable carbon isotopes. We illustrate a distinct change in the character of DOC in deep waters compared to surface and mid-depth waters. Our results suggest that, both, microbial reworking of terrestrially derived plant detritus and subsequent desorption of DOC from its particulate counterpart (as verified in a desorption experiment) are the main sources of the humic-like enriched DOC in the deep basins of the studied fjords. While it has been suggested that short transit times and protection of OM by mineral sorption may ultimately result in significant terrestrial carbon burial and preservation in fjords, our data suggests the existence of an additional source of terrestrial OM in the form of DOC generated in deep, fjord water.

  15. Latitudinal gradients in degradation of marine dissolved organic carbon.

    Directory of Open Access Journals (Sweden)

    Carol Arnosti

    Full Text Available Heterotrophic microbial communities cycle nearly half of net primary productivity in the ocean, and play a particularly important role in transformations of dissolved organic carbon (DOC. The specific means by which these communities mediate the transformations of organic carbon are largely unknown, since the vast majority of marine bacteria have not been isolated in culture, and most measurements of DOC degradation rates have focused on uptake and metabolism of either bulk DOC or of simple model compounds (e.g. specific amino acids or sugars. Genomic investigations provide information about the potential capabilities of organisms and communities but not the extent to which such potential is expressed. We tested directly the capabilities of heterotrophic microbial communities in surface ocean waters at 32 stations spanning latitudes from 76°S to 79°N to hydrolyze a range of high molecular weight organic substrates and thereby initiate organic matter degradation. These data demonstrate the existence of a latitudinal gradient in the range of complex substrates available to heterotrophic microbial communities, paralleling the global gradient in bacterial species richness. As changing climate increasingly affects the marine environment, changes in the spectrum of substrates accessible by microbial communities may lead to shifts in the location and rate at which marine DOC is respired. Since the inventory of DOC in the ocean is comparable in magnitude to the atmospheric CO(2 reservoir, such a change could profoundly affect the global carbon cycle.

  16. Hydrologic controls on the export dynamics of dissolved and particulate phosphorus in a lowland, headwater agricultural catchment

    Science.gov (United States)

    Dupas, Rémi; Grimaldi, Catherine; Gruau, Gérard; Gascuel-Odoux, Chantal

    2014-05-01

    Phosphorus (P) availability controls eutrophication in freshwater ecosystems, since P is generally the limiting nutrient to algal development. The contribution of diffuse P emission to surface waters is significant in intensively livestock farmed catchments as a result of high application rates of P-rich animal waste and subsequent enrichment of soils. This study investigates the transport dynamics of particulate phosphorus (PP), suspended sediments (SS), and dissolved phosphorus (DP) with the aim of elucidating the relationship between PP and DP transport mechanisms and water dynamics in lowland, headwater catchments. The selected catchment (Kervidy-Naizin catchment, France) is particularly suitable for this purpose as it benefits of a 5 years, high-frequency monitoring of PP and DP concentrations at its outlet, including data recovered both during base flow and storm periods, with the monitoring of more than 50 storm flow events. The data analysis includes interpretation of concentration-discharge relationships at the annual time scale and on an event basis, seasonal analysis of flood characteristics and empirical modeling. Annual DP and PP concentration-discharge relationships of interflood samples display a hysteretic pattern, with higher concentrations during the autumn and spring periods, and progressive decrease during winter. No hysteretic pattern is visible for interflood SS concentration, which follows a classical C=a*Qb relationship. During floods, the dynamic of PP export is similar to that of SS during most of the events: the concentration peak occurs during the rising limb of the hydrogram (clockwise hysteresis), suggesting a source close to or within the stream. The amplitude and the hysteresis' loop size for SS and PP are a function of maximum discharge and rate of change in discharge. On the contrary, there is a strong decoupling between DP and SS (and thus PP) during most of the floods (no significant correlation), with DP concentration peaks

  17. Sea cucumbers reduce chromophoric dissolved organic matter in aquaculture tanks

    Directory of Open Access Journals (Sweden)

    Seyed Mohammad Sadeghi-Nassaj

    2018-02-01

    Full Text Available Background Mono-specific aquaculture effluents contain high concentrations of nutrients and organic matter, which affect negatively the water quality of the recipient ecosystems. A fundamental feature of water quality is its transparency. The fraction of dissolved organic matter that absorbs light is named chromophoric dissolved organic matter (CDOM. A sustainable alternative to mono-specific aquaculture is the multitrophic aquaculture that includes species trophically complementary named “extractive” species that uptake the waste byproducts. Sea cucumbers are recognized as efficient extractive species due to the consumption of particulate organic matter (POM. However, the effects of sea cucumbers on CDOM are still unknown. Methods During more than one year, we monitored CDOM in two big-volume tanks with different trophic structure. One of the tanks (−holothurian only contained around 810 individuals of Anemonia sulcata, whereas the other tank (+holothurian also included 90 individuals of Holothuria tubulosa and Holothuria forskali. We routinely analyzed CDOM absorption spectra and determined quantitative (absorption coefficients at 325 nm and qualitative (spectral slopes optical parameters in the inlet waters, within the tanks, and in their corresponding effluents. To confirm the time-series results, we also performed three experiments. Each experiment consisted of two treatments: +holothurians (+H and –holothurians (−H. We set up three +H tanks with 80 individuals of A. sulcata and 10 individuals of H. tubulosa in each tank and four –H tanks that contained only 80 individuals of A. sulcata. Results In the time-series, absorption coefficients at 325 nm (a325 and spectral slopes from 275 to 295 nm (S275−295 were significantly lower in the effluent of the +holothurian tank (average: 0.33 m−1 and 16 µm−1, respectively than in the effluent of the −holothurian tank (average: 0.69 m−1 and 34 µm−1, respectively, the former

  18. Improving Phosphorus Availability in an Acid Soil Using Organic Amendments Produced from Agroindustrial Wastes

    OpenAIRE

    Ch’ng, Huck Ywih; Ahmed, Osumanu Haruna; Majid, Nik Muhamad Ab.

    2014-01-01

    In acid soils, soluble inorganic phosphorus is fixed by aluminium and iron. To overcome this problem, acid soils are limed to fix aluminium and iron but this practice is not economical. The practice is also not environmentally friendly. This study was conducted to improve phosphorus availability using organic amendments (biochar and compost produced from chicken litter and pineapple leaves, resp.) to fix aluminium and iron instead of phosphorus. Amending soil with biochar or compost or a mixt...

  19. 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.

  20. Assessing the drivers of dissolved organic matter export from two contrasting lowland catchments, U.K.

    Science.gov (United States)

    Yates, Christopher A; Johnes, Penny J; Spencer, Robert G M

    2016-11-01

    Two lowland catchments in the U.K. were sampled throughout 2010-11 to investigate the dominant controls on dissolved organic matter quantity and composition. The catchments had marked differences in terms of nutrient status, land cover and contrasting lithologies resulting in differences in the dominant flow pathways (groundwater vs. surface water dominated). The Upper Wylye is a chalk stream with a baseflow index of 0.98, draining a catchment dominated by intensive agricultural production. Millersford Brook is a lowland peat catchment with a baseflow index of 0.43, draining a semi-natural catchment with heather moorland and coniferous forest. Samples were collected weekly between October 2010 and September 2011 from eleven sampling locations. Samples were analysed to determine dissolved organic carbon, nitrogen and phosphorus fractions with DOM composition evaluated via the DOC:DON ratio, DOC:DOP ratio, specific UV absorption at 254nm, absorbance ratio (a250:a365) and the spectral slope parameter between 350 and 400nm (S350-400). Significant differences were observed in all determinands between the catchments, over time, and spatially along nutrient enrichment and geoclimatic gradients. Seasonal variation in preferential flow pathways mobilising groundwater-derived DOM were identified as likely controls on the delivery of DOM in the permeable chalk dominated catchment. Steeper S350-400 values and elevated a250:a365 ratios in this catchment suggest material of a lower bulk aromatic C content and molecular weight delivered during the winter months when compared to the summer. DOC:DON ratios were markedly lower in the chalk catchment than the peatland catchment, reflecting the paucity of organic matter within the mineral soils of the chalk landscape, and higher fertiliser application rates. This manuscript highlights that DOM composition varies according to catchment landscape character and hydrological function. Copyright © 2016 The Authors. Published by Elsevier B

  1. Climate Variability, Dissolved Organic Carbon, UV Exposure, and Amphibian Decline

    Science.gov (United States)

    Brooks, P. D.; O'Reilly, C. M.; Diamond, S.; Corn, S.; Muths, E.; Tonnessen, K.; Campbell, D. H.

    2001-12-01

    Increasing levels of UV radiation represent a potential threat to aquatic organisms in a wide range of environments, yet controls on in situ variability on UV exposure are relatively unknown. The primary control on the penetration of UV radiation in surface water environments is the amount of photoreactive dissolved organic carbon (DOC). Consequently, biogeochemical processes that control the cycling of DOC also affect the exposure of aquatic organisms to UV radiation. Three years of monitoring UV extinction and DOC composition in Rocky Mountain, Glacier, Sequoia/ Kings Canyon, and Olympic National Parks demonstrate that the amount of fulvic acid DOC is much more important than the total DOC pool in controlling UV attenuation. This photoreactive component of DOC originates primarily in soil, and is subject both to biogeochemical controls (e.g. temperature, moisture, vegetation, soil type) on production, and hydrologic controls on transport to surface water and consequently UV exposure to aquatic organisms. Both of these controls are positively related to precipitation with greater production and transport associated with higher precipitation amounts. For example, an approximately 20 percent reduction in precipitation from 1999 to 2000 resulted in a 27% - 59% reduction in the amount of photoreactive DOC at three sites in Rocky Mountain National Park. These differences in the amount of hydrophobic DOC result in an increase in UV exposure in the aquatic environment by a factor of 2 or more. Implications of these findings for observed patterns of amphibian decline will be discussed.

  2. Underestimation of phosphorus fraction change in the supernatant after phosphorus adsorption onto iron oxides and iron oxide-natural organic matter complexes.

    Science.gov (United States)

    Yan, Jinlong; Jiang, Tao; Yao, Ying; Wang, Jun; Cai, Yuanli; Green, Nelson W; Wei, Shiqiang

    2017-05-01

    The phosphorus (P) fraction distribution and formation mechanism in the supernatant after P adsorption onto iron oxides and iron oxide-humic acid (HA) complexes were analyzed using the ultrafiltration method in this study. With an initial P concentration of 20mg/L (I=0.01mol/L and pH=7), it was shown that the colloid (1kDa-0.45μm) component of P accounted for 10.6%, 11.6%, 6.5%, and 4.0% of remaining total P concentration in the supernatant after P adsorption onto ferrihydrite (FH), goethite (GE), ferrihydrite-humic acid complex (FH-HA), goethite-humic acid complex (GE-HA), respectively. The oxide aggregates was the main mechanism for the formation of the colloid P in the supernatant. And colloidal adsorbent particles co-existing in the supernatant were another important reason for it. Additionally, dissolve organic matter dissolved from iron oxide-HA complexes could occupy large adsorption sites of colloidal iron causing less colloid P in the supernatant. Ultimately, we believe that the findings can provide a new way to deeply interpret the geochemical cycling of P, even when considering other contaminants such as organic pollutants, heavy metal ions, and arsenate at the sediment/soil-water interface in the real environment. Copyright © 2016. Published by Elsevier B.V.

  3. Inner filter correction of dissolved organic matter fluorescence

    DEFF Research Database (Denmark)

    Kothawala, D.N.,; Murphy, K.R.; Stedmon, Colin

    2013-01-01

    The fluorescence of dissolved organic matter (DOM) is suppressed by a phenomenon of self-quenching known as the inner filter effect (IFE). Despite widespread use of fluorescence to characterize DOM in surface waters, the advantages and constraints of IFE correction are poorly defined. We assessed...... the effectiveness of a commonly used absorbance-based approach (ABA), and a recently proposed controlled dilution approach (CDA) to correct for IFE. Linearity between corrected fluorescence and total absorbance (ATotal; the sum of absorbance at excitation and emission wavelengths) across the full excitation......-emission matrix (EEM) in dilution series of four samples indicated both ABA and CDA were effective to an absorbance of at least 1.5 in a 1 cm cell, regardless of wavelength positioning. In regions of the EEMs where signal to background noise (S/N) was low, CDA correction resulted in more variability than ABA...

  4. 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.

  5. Anthropogenic inputs of dissolved organic matter in New York Harbor

    Science.gov (United States)

    Gardner, G. B.; Chen, R. F.; Olavasen, J.; Peri, F.

    2016-02-01

    The Hudson River flows into the Atlantic Ocean through a highly urbanized region which includes New York City to the east and Newark, New Jersey to the west. As a result, the export of Dissolved Organic Carbon (DOC) from the Hudson to the Atlantic Ocean includes a significant anthropogenic component. A series of high resolution studies of the DOC dynamics of this system were conducted between 2003 and 2010. These included both the Hudson and adjacent large waterways (East River, Newark Bay, Kill Van Kull and Arthur Kill) using coastal research vessels and smaller tributaries (Hackensack, Pasaic and Raritan rivers) using a 25' boat. In both cases measurements were made using towed instrument packages which could be cycled from near surface to near bottom depths with horizontal resolution of approximately 20 to 200 meters depending on depth and deployment strategy. Sensors on the instrument packages included a CTD to provide depth and salinity information and a chromophoric dissolved organic matter(CDOM) fluorometer to measure the fluorescent fraction of the DOC. Discrete samples allowed calibration of the fluorometer and the CDOM data to be related to DOC. The combined data set from these cruises identified multiple scales of source and transport processes for DOC within the Hudson River/New York Harbor region. The Hudson carries a substantial amount of natural DOC from its 230 km inland stretch. Additional sources exist in fringing salt marshes adjacent to the Hackensack and Raritan rivers. However the lower Hudson/New Harbor region receives a large input of DOC from multiple publically owned treatment works (POTW) discharges. The high resolution surveys allowed us to elucidate the distribution of these sources and the manner in which they are rapidly mixed to create the total export. We estimate that anthropogenic sources account for up to 2.5 times the DOC flux contributed by natural processes.

  6. Dissolved Organic Matter Land-Ocean Linkages in the Arctic

    Science.gov (United States)

    Mann, P. J.; Spencer, R. M.; Hernes, P. J.; Tank, S. E.; Striegl, R.; Dyda, R. Y.; Peterson, B. J.; McClelland, J. W.; Holmes, R. M.

    2012-04-01

    Rivers draining into the Arctic Ocean exhibit high concentrations of terrigenous dissolved organic carbon (DOC), and recent studies indicate that DOC export is changing due to climatic warming and alteration in permafrost condition. The fate of exported DOC in the Arctic Ocean is important for understanding the regional carbon cycle and remains a point of discussion in the literature. As part of the NSF funded Arctic Great Rivers Observatory (Arctic-GRO) project, samples were collected for DOC, chromophoric and fluorescent dissolved organic matter (CDOM & FDOM) and lignin phenols from the Ob', Yenisey, Lena, Kolyma, Mackenzie and Yukon rivers in 2009 - 2010. DOC and lignin concentrations were elevated during the spring freshet and measurements related to DOC composition indicated an increasing contribution from terrestrial vascular plant sources at this time of year (e.g. lignin carbon-normalized yield, CDOM spectral slope, SUVA254, humic-like fluorescence). CDOM absorption was found to correlate strongly with both DOC (r2=0.83) and lignin concentration (r2=0.92) across the major arctic rivers. Lignin composition was also successfully modeled using FDOM measurements decomposed using PARAFAC analysis. Utilizing these relationships we modeled loads for DOC and lignin export from high-resolution CDOM measurements (daily across the freshet) to derive improved flux estimates, particularly from the dynamic spring discharge maxima period when the majority of DOC and lignin export occurs. The new load estimates for DOC and lignin are higher than previous evaluations, emphasizing that if these are more representative of current arctic riverine export, terrigenous DOC is transiting through the Arctic Ocean at a faster rate than previously thought. It is apparent that higher resolution sampling of arctic rivers is exceptionally valuable with respect to deriving accurate fluxes and we highlight the potential of CDOM in this role for future studies and the applicability of in

  7. Origins and bioavailability of dissolved organic matter in groundwater

    Science.gov (United States)

    Shen, Yuan; Chapelle, Francis H.; Strom, Eric W.; Benner, Ronald

    2015-01-01

    Dissolved organic matter (DOM) in groundwater influences water quality and fuels microbial metabolism, but its origins, bioavailability and chemical composition are poorly understood. The origins and concentrations of dissolved organic carbon (DOC) and bioavailable DOM were monitored during a long-term (2-year) study of groundwater in a fractured-rock aquifer in the Carolina slate belt. Surface precipitation was significantly correlated with groundwater concentrations of DOC, bioavailable DOM and chromophoric DOM, indicating strong hydrological connections between surface and ground waters. The physicochemical and biological processes shaping the concentrations and compositions of DOM during its passage through the soil column to the saturated zone are conceptualized in the regional chromatography model. The model provides a framework for linking hydrology with the processes affecting the transformation, remineralization and microbial production of DOM during passage through the soil column. Lignin-derived phenols were relatively depleted in groundwater DOM indicating substantial removal in the unsaturated zone, and optical properties of chromophoric DOM indicated lower molecular weight DOM in groundwater relative to surface water. The prevalence of glycine, γ-aminobutyric acid, and d-enantiomers of amino acids indicated the DOM was highly diagenetically altered. Bioassay experiments were used to establish DOC-normalized yields of amino acids as molecular indicators of DOM bioavailability in groundwater. A relatively small fraction (8 ± 4 %) of DOC in groundwater was bioavailable. The relatively high yields of specific d-enantiomers of amino acids indicated a substantial fraction (15–34 %) of groundwater DOC was of bacterial origin.

  8. Molecular characterization of dissolved organic matter (DOM): a critical review.

    Science.gov (United States)

    Nebbioso, Antonio; Piccolo, Alessandro

    2013-01-01

    Advances in water chemistry in the last decade have improved our knowledge about the genesis, composition, and structure of dissolved organic matter, and its effect on the environment. Improvements in analytical technology, for example Fourier-transform ion cyclotron (FT-ICR) mass spectrometry (MS), homo and hetero-correlated multidimensional nuclear magnetic resonance (NMR) spectroscopy, and excitation emission matrix fluorimetry (EEMF) with parallel factor (PARAFAC) analysis for UV-fluorescence spectroscopy have resulted in these advances. Improved purification methods, for example ultrafiltration and reverse osmosis, have enabled facile desalting and concentration of freshly collected DOM samples, thereby complementing the analytical process. Although its molecular weight (MW) remains undefined, DOM is described as a complex mixture of low-MW substances and larger-MW biomolecules, for example proteins, polysaccharides, and exocellular macromolecules. There is a general consensus that marine DOM originates from terrestrial and marine sources. A combination of diagenetic and microbial processes contributes to its origin, resulting in refractory organic matter which acts as carbon sink in the ocean. Ocean DOM is derived partially from humified products of plants decay dissolved in fresh water and transported to the ocean, and partially from proteinaceous and polysaccharide material from phytoplankton metabolism, which undergoes in-situ microbial processes, becoming refractory. Some of the DOM interacts with radiation and is, therefore, defined as chromophoric DOM (CDOM). CDOM is classified as terrestrial, marine, anthropogenic, or mixed, depending on its origin. Terrestrial CDOM reaches the oceans via estuaries, whereas autochthonous CDOM is formed in sea water by microbial activity; anthropogenic CDOM is a result of human activity. CDOM also affects the quality of water, by shielding it from solar radiation, and constitutes a carbon sink pool. Evidence in support

  9. Dissolved Nitrogen and Phosphorus Dynamics in the Lower Portion of the Paraiba do Sul River, Campos dos Goytacazes, RJ, Brazil

    Directory of Open Access Journals (Sweden)

    Mônica Aparecida Leite Silva

    2001-12-01

    Full Text Available The Paraíba do Sul river lower reach was monitored monthly between August 1995 and July 1996. This study was aimed at evaluating the temporal dynamics of dissolved nitrogen and phosphorus and its main controlling factors. Minimum and maximum observed values were as follows: N-NO2- - 0.08/0.51; N-NO3- - 21/57; N-NH4+ - 1.4/6.7; DON - 4.9/86.0; DIN -24.5/60.9; P-PO4(3- - 0.43/1.66; DOP - 0.05/0.92; pH - 6.2/7.8; Dissolved Oxygen - 6.4/10.1; Conductivity - 48/74; Temperature - 20.5/31.1 (Nutrients - µM; Dissolved Oxygen - mg/l; Conductivity - µS/cm; Temperature - °C. Discharge presented a characteristic seasonal variation, showing a peak in January. Increasing P-PO4(3-, DOP, N-NH4+ and N-NO2- concentrations with increasing discharges could be associated to the partial flooding of inumerous fluvial islands and floodplains and to the agricultural practices of sugar cane crops that during the wet season could transfer nitrogen and phosphorus compounds to the fluvial channel.O Rio Paraíba do Sul foi monitorado mensalmente na sua porção inferior, entre agosto de 1995 e julho de 1996, objetivando estudar a dinâmica temporal de nitrogênio e fósforo dissolvidos e avaliar seus principais fatores controladores. Os valores mínimos e máximos observados para os parâmetros analisados foram os seguintes: N-NO2- - 0,08/0,51; N-NO3- - 21/57; N-NH4+ - 1,4/6,7; Nitrogênio Orgânico Dissolvido (NOD - 4,9/86,0; Nitrogênio Inorgânico Dissolvido (NID - 24,5/60,9; P-PO4(3 - - 0,43/1,66; Fósforo Orgânico Dissolvido (POD - 0,05/0,92; pH - 6,2/7,8; Oxigênio Dissolvido - 6,4/10,1; Condutividade - 48/74; Temperatura - 20,5/31,1 (Nutrientes - µM; Oxigênio Dissolvido - mg/l; Condutividade - µS/cm; Temperatura - °C. A vazão apresentou uma variação sazonal característica, com pico de descarga em janeiro. A elevação das concentrações de P-PO4(3 -, POD, N-NH4+ e N-NO2- com o aumento da vazão pode estar associada à inundação parcial de numerosas

  10. Spectroscopic Characteristics of Dissolved Organic Matter in Afforestation Forest Soil of Miyun District, Beijing

    Science.gov (United States)

    Zhao, Chen; Shi, Zong-Hai; Zhong, Jun; Liu, Jian-Guo; Li, Jun-Qing

    2016-01-01

    In this study, soil samples collected from different plain afforestation time (1 year, 4 years, 10 years, 15 years, and 20 years) in Miyun were characterized, including total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), available K (K+), microbial biomass carbon (MBC), and dissolved organic carbon (DOC). The DOM in the soil samples with different afforestation time was further characterized via DOC, UV-Visible spectroscopy, excitation-emission matrix (EEM) fluorescence spectroscopy, and 1H NMR spectroscopy. The results suggested that the texture of soil sample was sandy. The extracted DOM from soil consisted mainly of aliphatic chains and only a minor aromatic component. It can be included that afforestation can improve the soil quality to some extent, which can be partly reflected from the indexes like TOC, TN, TP, K+, MBC, and DOC. And the characterization of DOM implied that UV humic-like substances were the major fluorophores components in the DOM of the soil samples, which consisted of aliphatic chains and aromatic components with carbonyl, carboxyl, and hydroxyl groups. PMID:27433371

  11. CHROMOPHORIC DISSOLVED ORGANIC MATTER (CDOM) DERIVED FROM DECOMPOSITION OF VARIOUS VASCULAR PLANT AND ALGAL SOURCES

    Science.gov (United States)

    Chromophoric dissolved organic (CDOM) in aquatic environments is derived from the microbial decomposition of terrestrial and microbial organic matter. Here we present results of studies of the spectral properties and photoreactivity of the CDOM derived from several organic matter...

  12. Yucca Mountain Area Saturated Zone Dissolved Organic Carbon Isotopic Data

    International Nuclear Information System (INIS)

    Thomas, James; Decker, David; Patterson, Gary; Peterman, Zell; Mihevc, Todd; Larsen, Jessica; Hershey, Ronald

    2007-01-01

    Groundwater samples in the Yucca Mountain area were collected for chemical and isotopic analyses and measurements of water temperature, pH, specific conductivity, and alkalinity were obtained at the well or spring at the time of sampling. For this project, groundwater samples were analyzed for major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC). The U.S. Geological Survey (USGS) performed all the fieldwork on this project including measurement of water chemistry field parameters and sample collection. The major ions dissolved in the groundwater, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) were analyzed by the USGS. All preparation and processing of samples for DOC carbon isotopic analyses and geochemical modeling were performed by the Desert Research Institute (DRI). Analysis of the DOC carbon dioxide gas produced at DRI to obtain carbon-13 and carbon-14 values was conducted at the University of Arizona Accelerator Facility (a NSHE Yucca Mountain project QA qualified contract facility). The major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of DIC were used in geochemical modeling (NETPATH) to determine groundwater sources, f ow paths, mixing, and ages. The carbon isotopes of DOC were used to calculate groundwater ages that are independent of DIC model corrected carbon-14 ages. The DIC model corrected carbon-14 calculated ages were used to evaluate groundwater travel times for mixtures of water including water beneath Yucca Mountain. When possible, groundwater travel times were calculated for groundwater flow from beneath Yucca Mountain to down gradient sample sites. DOC carbon-14 groundwater ages were also calculated for groundwaters in the Yucca Mountain area. When possible, groundwater travel times were estimated for groundwater flow from beneath Yucca Mountain to down gradient groundwater sample sites using the DOC calculated

  13. Colored dissolved organic matter in Tampa Bay, Florida

    Science.gov (United States)

    Chen, Z.; Hu, C.; Conmy, R.N.; Muller-Karger, F.; Swarzenski, P.

    2007-01-01

    Absorption and fluorescence of colored dissolved organic matter (CDOM) and concentrations of dissolved organic carbon (DOC), chlorophyll and total suspended solids in Tampa Bay and its adjacent rivers were examined in June and October of 2004. Except in Old Tampa Bay (OTB), the spatial distribution of CDOM showed a conservative relationship with salinity in June, 2004 (aCDOM(400) = − 0.19 × salinity + 6.78, R2 = 0.98, n = 17, salinity range = 1.1–32.5) with little variations in absorption spectral slope and fluorescence efficiency. This indicates that CDOM distribution was dominated by mixing. In October, 2004, CDOM distribution was nonconservative with an average absorption coefficient (aCDOM(400), ∼ 7.76 m-1) about seven times higher than that in June (∼ 1.11 m-1). The nonconservative behavior was caused largely by CDOM removal at intermediate salinities (e.g., aCDOM(400) removal > 15% at salinity ∼ 13.0), which likely resulted from photobleaching due to stronger stratification. The spatial and seasonal distributions of CDOM in Tampa Bay showed that the two largest rivers, the Alafia River (AR) and Hillsborough River (HR) were dominant CDOM sources to most of the bay. In OTB, however, CDOM showed distinctive differences: lower absorption coefficient, higher absorption spectral slopes, and lower ratios of CDOM absorption to DOC and higher fluorescence efficiency. These differences may have stemmed from (1) changes in CDOM composition by more intensive photobleaching due to the longer residence time of water mass in OTB; (2) other sources of CDOM than the HR/AR inputs, such as local creeks, streams, groundwater, and/or bottom re-suspension. Average CDOM absorption in Tampa Bay at 443 nm, aCDOM(443), was about five times higher in June and about ten times higher in October than phytoplankton pigment absorption, aph(443), indicating that blue light attenuation in the water column was dominated by CDOM rather than by phytoplankton absorption throughout the

  14. Characterization Of Dissolved Organic Mattter In The Florida Keys Ecosystem

    Science.gov (United States)

    Adams, D. G.; Shank, G. C.

    2009-12-01

    Over the past few decades, Scleractinian coral populations in the Florida Keys have increasingly experienced mortality due to bleaching events as well as microbial mediated illnesses such as black band and white band disease. Such pathologies seem to be most correlated with elevated sea surface temperatures, increased UV exposures, and shifts in the microbial community living on the coral itself. Recent studies indicate that corals’ exposure to UV in the Florida Keys is primarily controlled by the concentration of CDOM (Chromophoric Dissolved Organic Matter) in the water column. Further, microbial community alterations may be linked to changes in concentration and chemical composition of the larger DOM (Dissolved Organic Matter) pool. Our research characterized the spatial and temporal properties of DOM in Florida Bay and along the Keys ecosystems using DOC analyses, in-situ water column optical measurements, and spectral analyses including absorbance and fluorescence measurements. We analyzed DOM characteristics along transects running from the mouth of the Shark River at the southwest base of the Everglades, through Florida Bay, and along near-shore Keys coastal waters. Two 12 hour time-series samplings were also performed at the Seven-Mile Bridge, the primary Florida Bay discharge channel to the lower Keys region. Photo-bleaching experiments showed that the chemical characteristics of the DOM pool are altered by exposure to solar radiation. Results also show that DOC (~0.8-5.8 mg C/L) and CDOM (~0.5-16.5 absorbance coefficient at 305nm) concentrations exhibit seasonal fluctuations in our study region. EEM analyses suggest seasonal transitions between primarily marine (summer) and terrestrial (winter) sources along the Keys. We are currently combining EEM-PARAFAC analysis with in-situ optical measurements to model changes in the spectral properties of DOM in the water column. Additionally, we are using stable δ13C isotopic analysis to further characterize DOM

  15. 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

  16. Molecular simulation of a model of dissolved organic matter.

    Science.gov (United States)

    Sutton, Rebecca; Sposito, Garrison; Diallo, Mamadou S; Schulten, Hans-Rolf

    2005-08-01

    A series of atomistic simulations was performed to assess the ability of the Schulten dissolved organic matter (DOM) molecule, a well-established model humic molecule, to reproduce the physical and chemical behavior of natural humic substances. The unhydrated DOM molecule had a bulk density value appropriate to humic matter, but its Hildebrand solubility parameter was lower than the range of current experimental estimates. Under hydrated conditions, the DOM molecule went through conformational adjustments that resulted in disruption of intramolecular hydrogen bonds (H-bonds), although few water molecules penetrated the organic interior. The radius of gyration of the hydrated DOM molecule was similar to those measured for aquatic humic substances. To simulate humic materials under aqueous conditions with varying pH levels, carboxyl groups were deprotonated, and hydrated Na+ or Ca2+ were added to balance the resulting negative charge. Because of intrusion of the cation hydrates, the model metal-humic structures were more porous, had greater solvent-accessible surface areas, and formed more H-bonds with water than the protonated, hydrated DOM molecule. Relative to Na+, Ca2+ was both more strongly bound to carboxylate groups and more fully hydrated. This difference was attributed to the higher charge of the divalent cation. The Ca-DOM hydrate, however, featured fewer H-bonds than the Na-DOM hydrate, perhaps because of the reduced orientational freedom of organic moieties and water molecules imposed by Ca2+. The present work is, to our knowledge, the first rigorous computational exploration regarding the behavior of a model humic molecule under a range of physical conditions typical of soil and water systems.

  17. [Studies on nitrogen, phosphorus and organic matter in ponds around Chaohu Lake].

    Science.gov (United States)

    Sun, Qing-ye; Ma, Xiu-ling; Yang, Gui-de; Chen, Zheng; Wu, Hong-lin; Xuan, Huai-xiang

    2010-07-01

    There are a lot of ponds around Chaohu Lake. According to location and runoff supply of ponds, the ponds are divided into three types: ponds inner vellage (PIV), ponds adjacent vellage (PAV) and ponds outer vellage (POV). The samples of water and sediment were collected from 136 ponds around Chaohu Lake and the contents of nitrogen, phosphorus and organic matter in water and sediments were analyzed in this study. The results showed that mean contents of total nitrogen (TN), NH4+ -N, NO3- -N, NO2- -N, total phosphorus (TP), soluble PO4(3-) -P and COD were 2.53, 0.65, 0.18, 0.02, 0.97, 0.38 and 51.58 mg x L(-1) in pond water, respectively; and mean contents of TN, NH4+ -N, NO3- -N, NO2- -N, TP, inorganic phosphorus (IP), organic phosphorus (OP) and loss of ignition (LOI) in pond sediment were 1575.36, 35.73, 13.30, 2.88, 933.19, 490.14, 414.75 mg x kg(-1) and 5.44%, respectively. The ponds of more than 90% presented eutrophication in the contents of total nitrogen and phosphorus in water. The contents of TN and NH4+ -N in water and sediment of PIV were significantly higher than that of POV. And the contents of inorganic nitrogen in pond water and sediment displayed a following order: NH4+ -N > NO3- -N > NO2- -N. Data analysis indicated that there was a significantly positive correlation between organic matter and total nitrogen and phosphorus in water and sediment. The nitrogen, phosphorus and organic matter in ponds mainly sourced farmlands and village land surface. The contents of nitrogen, phosphorus and organic matter in ponds were affected by location and runoff supply of ponds. By retaining nitrogen, phosphorus and organic matter in runoff, the ponds can effectively decrease nutrient content into Chaohu Lake.

  18. Distribution of phosphorus and organic carbon in the nearshore sediments of Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Rajamanickam, G.V.; Setty, M.G.A.P.

    Samples collected from sediment water interface from the inner shelf region of Goa coast are examined for their phosphorus and organic carbon, which indicate the geochemical environment under which the present day deposits are laid down...

  19. Passive sampler for dissolved organic matter in freshwater environments.

    Science.gov (United States)

    Lam, Buuan; Simpson, André J

    2006-12-15

    A passive sampler for the isolation of dissolved organic matter (DOM) from freshwater environments is described. The sampler consists of a molecular weight selective membrane (1000 kDa) and an anion exchange resin (diethylaminoethylcellulose (DEAE-cellulose)). NMR indicates the samplers isolate DOM that is nearly indistinguishable from that isolated using the batch DEAE-cellulose procedure. In a comparative study DOM isolated from Lake Ontario cost approximately 0.30 dollars/mg to isolate using the passive samplers while DOM isolated using the traditional batch procedure cost approximately 8-10 dollars/mg. The samplers have been shown to be effective in a range of freshwater environments including a large inland lake (Lake Ontario), fast flowing tributary, and wetland. Large amounts (gram quantities of DOM) can be easily isolated by increasing the size or number of samplers deployed. Samplers are easy to construct, negate the need for pressure filtering, and also permit a range of temporal and spatial experiments that would be very difficult or impossible to perform using conventional approaches. For example, DOM can be monitored on a regular basis at numerous different locations, or samplers could be set at different depths in large lakes. Furthermore, they could potentially be deployed into hard to reach environments such as wells, groundwater aquifers, etc., and as they are easy to use, they can be mailed to colleagues or included with expeditions going to difficult to reach places such as the Arctic and Antarctic.

  20. Hidden cycle of dissolved organic carbon in the deep ocean.

    Science.gov (United States)

    Follett, Christopher L; Repeta, Daniel J; Rothman, Daniel H; Xu, Li; Santinelli, Chiara

    2014-11-25

    Marine dissolved organic carbon (DOC) is a large (660 Pg C) reactive carbon reservoir that mediates the oceanic microbial food web and interacts with climate on both short and long timescales. Carbon isotopic content provides information on the DOC source via δ(13)C and age via Δ(14)C. Bulk isotope measurements suggest a microbially sourced DOC reservoir with two distinct components of differing radiocarbon age. However, such measurements cannot determine internal dynamics and fluxes. Here we analyze serial oxidation experiments to quantify the isotopic diversity of DOC at an oligotrophic site in the central Pacific Ocean. Our results show diversity in both stable and radio isotopes at all depths, confirming DOC cycling hidden within bulk analyses. We confirm the presence of isotopically enriched, modern DOC cocycling with an isotopically depleted older fraction in the upper ocean. However, our results show that up to 30% of the deep DOC reservoir is modern and supported by a 1 Pg/y carbon flux, which is 10 times higher than inferred from bulk isotope measurements. Isotopically depleted material turns over at an apparent time scale of 30,000 y, which is far slower than indicated by bulk isotope measurements. These results are consistent with global DOC measurements and explain both the fluctuations in deep DOC concentration and the anomalous radiocarbon values of DOC in the Southern Ocean. Collectively these results provide an unprecedented view of the ways in which DOC moves through the marine carbon cycle.

  1. The characteristics of dissolved organic matter (DOM) and chromophoric dissolved organic matter (CDOM) in Antarctic sea ice

    Science.gov (United States)

    Norman, Louiza; Thomas, David N.; Stedmon, Colin A.; Granskog, Mats A.; Papadimitriou, Stathys; Krapp, Rupert H.; Meiners, Klaus M.; Lannuzel, Delphine; van der Merwe, Pier; Dieckmann, Gerhard S.

    2011-05-01

    An investigation of coloured dissolved organic matter (CDOM) and its relationships to physical and biogeochemical parameters in Antarctic sea ice and oceanic water have indicated that ice melt may both alter the spectral characteristics of CDOM in Antarctic surface waters and serve as a likely source of fresh autochthonous CDOM and labile DOC. Samples were collected from melted bulk sea ice, sea ice brines, surface gap layer waters, and seawater during three expeditions: one during the spring to summer and two during the winter to spring transition period. Variability in both physical (temperature and salinity) and biogeochemical parameters (dissolved and particulate organic carbon and nitrogen, as well as chlorophyll a) was observed during and between studies, but CDOM absorption coefficients measured at 375 nm (a 375) did not differ significantly. Distinct peaked absorption spectra were consistently observed for bulk ice, brine, and gap water, but were absent in the seawater samples. Correlation with the measured physical and biogeochemical parameters could not resolve the source of these peaks, but the shoulders and peaks observed between 260 and 280 nm and between 320 to 330 nm respectively, particularly in the samples taken from high light-exposed gap layer environment, suggest a possible link to aromatic and mycosporine-like amino acids. Sea ice CDOM susceptibility to photo-bleaching was demonstrated in an in situ 120 hour exposure, during which we observed a loss in CDOM absorption of 53% at 280 nm, 58% at 330 nm, and 30% at 375 nm. No overall coincidental loss of DOC or DON was measured during the experimental period. A relationship between the spectral slope (S) and carbon-specific absorption (a *375) indicated that the characteristics of CDOM can be described by the mixing of two broad end-members; and aged material, present in brine and seawater samples characterised by high S values and low a *375; and a fresh material, due to elevated in situ

  2. Enzymatic hydrolysis of organic phosphorus in swine manure and soil.

    Science.gov (United States)

    He, Zhongqi; Griffin, Timothy S; Honeycutt, C Wayne

    2004-01-01

    Organic phosphorus (Po) exists in many chemical forms that differ in their susceptibility to hydrolysis and, therefore, bioavailability to plants and microorganisms. Identification and quantification of these forms may significantly contribute to effective agricultural P management. Phosphatases catalyze reactions that release orthophosphate (Pi) from Po compounds. Alkaline phosphatase in tris-HCl buffer (pH 9.0), wheat (Triticum aestivum L.) phytase in potassium acetate buffer (pH 5.0), and nuclease P1 in potassium acetate buffer (pH 5.0) can be used to classify and quantify Po in animal manure. Background error associated with different pH and buffer systems is observed. In this study, we improved the enzymatic hydrolysis approach and tested its applicability for investigating Po in soils, recognizing that soil and manure differ in numerous physicochemical properties. We applied (i) acid phosphatase from potato (Solanum tuberosum L.), (ii) acid phosphatases from both potato and wheat germ, and (iii) both enzymes plus nuclease P1 to identify and quantify simple labile monoester P, phytate (myo-inositol hexakis phosphate)-like P, and DNA-like P, respectively, in a single pH/buffer system (100 mM sodium acetate, pH 5.0). This hydrolysis procedure released Po in sequentially extracted H2O, NaHCO3, and NaOH fractions of swine (Sus scrofa) manure, and of three sandy loam soils. Further refinement of the approach may provide a universal tool for evaluating hydrolyzable Po from a wide range of sources.

  3. Colored dissolved organic matter in shallow estuaries: the effect of source on quantification

    OpenAIRE

    W. K. Oestreich; N. K. Ganju; J. W. Pohlman; S. E. Suttles

    2015-01-01

    Light availability is of primary importance to the ecological function of shallow estuaries. For example, benthic primary production by submerged aquatic vegetation is contingent upon light penetration to the seabed. A major component that attenuates light in estuaries is colored dissolved organic matter (CDOM). CDOM is often measured via a proxy, fluorescing dissolved organic matter (fDOM...

  4. FACTORS INFLUENCING PHOTOREACTIONS OF DISSOLVED ORGANIC MATTER IN A COASTAL RIVER OF THE SOUTHEASTERN UNITED STATES

    Science.gov (United States)

    Photoreactions of dissolved organic matter can affect the oxidizing capacity, nutrient dynamics, trace gas exchange, and color of surface waters. This study focuses on factors that affect the photoreactions of the colored dissolved organic matter (CDOM) in the Satilla River, a co...

  5. Effect of organic fertilizers derived dissolved organic matter on pesticide sorption and leaching

    Energy Technology Data Exchange (ETDEWEB)

    Li Kun [Department of Plant, Soil, and Insect Sciences, Stockbridge Hall, University of Massachusetts, Amherst, MA 01003 (United States); Xing Baoshan [Department of Plant, Soil, and Insect Sciences, Stockbridge Hall, University of Massachusetts, Amherst, MA 01003 (United States) and Northeast Institute of Geography and Agro-ecology, CAS, Harbin 150040 (China)]. E-mail: bx@pssci.umass.edu; Torello, William A. [Department of Plant, Soil, and Insect Sciences, Stockbridge Hall, University of Massachusetts, Amherst, MA 01003 (United States)

    2005-03-01

    Incorporation of organic fertilizers/amendments has been, and continues to be, a popular strategy for golf course turfgrass management. Dissolved organic matter (DOM) derived from these organic materials may, however, facilitate organic chemical movement through soils. A batch equilibrium technique was used to evaluate the effects of organic fertilizer-derived DOM on sorption of three organic chemicals (2,4-D, naphthalene and chlorpyrifos) in USGA (United States Golf Association) sand, a mixed soil (70% USGA sand and 30% native soil) and a silt loam soil (Typic Fragiochrept). DOM was extracted from two commercial organic fertilizers. Column leaching experiments were also performed using USGA sand. Sorption experiments showed that sorption capacity was significantly reduced with increasing DOM concentration in solution for all three chemicals. Column experimental results were consistent with batch equilibrium data. These results suggest that organic fertilizer-derived DOM might lead to enhanced transport of applied chemicals in turf soils. - Dissolved organic matter could result in enhanced transport of chemicals applied to turf.

  6. Effect of organic fertilizers derived dissolved organic matter on pesticide sorption and leaching

    International Nuclear Information System (INIS)

    Li Kun; Xing Baoshan; Torello, William A.

    2005-01-01

    Incorporation of organic fertilizers/amendments has been, and continues to be, a popular strategy for golf course turfgrass management. Dissolved organic matter (DOM) derived from these organic materials may, however, facilitate organic chemical movement through soils. A batch equilibrium technique was used to evaluate the effects of organic fertilizer-derived DOM on sorption of three organic chemicals (2,4-D, naphthalene and chlorpyrifos) in USGA (United States Golf Association) sand, a mixed soil (70% USGA sand and 30% native soil) and a silt loam soil (Typic Fragiochrept). DOM was extracted from two commercial organic fertilizers. Column leaching experiments were also performed using USGA sand. Sorption experiments showed that sorption capacity was significantly reduced with increasing DOM concentration in solution for all three chemicals. Column experimental results were consistent with batch equilibrium data. These results suggest that organic fertilizer-derived DOM might lead to enhanced transport of applied chemicals in turf soils. - Dissolved organic matter could result in enhanced transport of chemicals applied to turf

  7. Sulfurization of Dissolved Organic Matter Increases Hg-Sulfide-Dissolved Organic Matter Bioavailability to a Hg-Methylating Bacterium.

    Science.gov (United States)

    Graham, Andrew M; Cameron-Burr, Keaton T; Hajic, Hayley A; Lee, Connie; Msekela, Deborah; Gilmour, Cynthia C

    2017-08-15

    Reactions of dissolved organic matter (DOM) with aqueous sulfide (termed sulfurization) in anoxic environments can substantially increase DOM's reduced sulfur functional group content. Sulfurization may affect DOM-trace metal interactions, including complexation and metal-containing particle precipitation, aggregation, and dissolution. Using a diverse suite of DOM samples, we found that susceptibility to additional sulfur incorporation via reaction with aqueous sulfide increased with increasing DOM aromatic-, carbonyl-, and carboxyl-C content. The role of DOM sulfurization in enhancing Hg bioavailability for microbial methylation was evaluated under conditions typical of Hg methylation environments (μM sulfide concentrations and low Hg-to-DOM molar ratios). Under the conditions of predicted metacinnabar supersaturation, microbial Hg methylation increased with increasing DOM sulfurization, likely reflecting either effective inhibition of metacinnabar growth and aggregation or the formation of Hg(II)-DOM thiol complexes with high bioavailability. Remarkably, Hg methylation efficiencies with the most sulfurized DOM samples were similar (>85% of total Hg methylated) to that observed in the presence of l-cysteine, a ligand facilitating rapid Hg(II) biouptake and methylation. This suggests that complexes of Hg(II) with DOM thiols have similar bioavailability to Hg(II) complexes with low-molecular-weight thiols. Overall, our results are a demonstration of the importance of DOM sulfurization to trace metal and metalloid (especially mercury) fate in the environment. DOM sulfurization likely represents another link between anthropogenic sulfate enrichment and MeHg production in the environment.

  8. Molecular characterization of macrophyte-derived dissolved organic matters and their implications for lakes

    Science.gov (United States)

    Chemical properties of whole organic matter (OM) and its dissolved organic matter (DOM) fraction from six dominant macrophytes in Lake Dianchi were comparatively characterized, and their environmental implications were discussed. Significant differences in chemical composition of the OM samples were...

  9. Dissolved organic carbon enhances the mass transfer of hydrophobic organic compounds from Nonaqueous Phase Liquids (NAPLs) into the aqueous phase

    NARCIS (Netherlands)

    Smith, K.E.C.; Thullner, M.; Wick, L.Y.; Harms, H.

    2011-01-01

    The hypothesis that dissolved organic carbon (DOC) enhances the mass transfer of hydrophobic organic compounds from nonaqueous phase liquids (NAPLs) into the aqueous phase above that attributable to dissolved molecular diffusion alone was tested. In controlled experiments, mass transfer rates of

  10. Molecular Determinants of Dissolved Organic Matter Reactivity in Lake Water

    Directory of Open Access Journals (Sweden)

    Alina Mostovaya

    2017-12-01

    Full Text Available Lakes in the boreal region have been recognized as the biogeochemical hotspots, yet many questions regarding the regulators of organic matter processing in these systems remain open. Molecular composition can be an important determinant of dissolved organic matter (DOM fate in freshwater systems, but many aspects of this relationship remain unclear due to the complexity of DOM and its interactions in the natural environment. Here, we combine ultrahigh resolution mass spectrometry (FT-ICR-MS with kinetic modeling of decay of >1,300 individual DOM molecular formulae identified by mass spectrometry, to evaluate the role of specific molecular characteristics in decomposition of lake water DOM. Our data is derived from a 4 months microbial decomposition experiment, carried out on water from three Swedish lakes, with the set-up including natural lake water, as well as the lake water pretreated with UV light. The relative decay rate of every molecular formula was estimated by fitting a single exponential model to the change in FT-ICR-MS signal intensities over decomposition time. We found a continuous range of exponential decay coefficients (kexp within different groups of compounds and show that for highly unsaturated and phenolic compounds the distribution of kexp was shifted toward the lowest values. Contrary to this general trend, plant-derived polyphenols and polycondensed aromatics were on average more reactive than compounds with an intermediate aromaticity. The decay rate of aromatic compounds increased with increasing nominal oxidation state of carbon, and molecular mass in some cases showed an inverse relationship with kexp in the UV-manipulated treatment. Further, we observe an increase in formulae-specific kexp as a result of the UV pretreatment. General trends in reactivity identified among major compound groups emphasize the importance of the intrinsic controllers of lake water DOM decay. However, we additionally indicate that each

  11. 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

  12. Organic carbon, nitrogen and phosphorus contents of some soils of kaliti tea-estate, Bangladesh

    International Nuclear Information System (INIS)

    Ahmed, M. S.; Shahin, M. M. H.; Sanaullah, A. F. M.

    2005-01-01

    Some soil samples were collected from Kaliti Tea-Estate of Moulvibazar district, Bangladesh. Total nitrogen, organic carbon, organic matter, carbon-nitrogen ratio and available phosphorus content of the collected soil samples of different depths and of different topographic positions have been determined. Total nitrogen was found 0.07 to 0.12 % organic carbon and organic matter content found to vary from 0.79 to 1.25 and 1.36 to 2.15 % respectively. Carbon-nitrogen ratio of these soils varied from 9.84 to 10.69, while available phosphorus content varied from 2.11 to 4.13 ppm. (author)

  13. Size exclusion chromatography with online ICP-MS enables molecular weight fractionation of dissolved phosphorus species in water samples.

    Science.gov (United States)

    Venkatesan, Arjun K; Gan, Wenhui; Ashani, Harsh; Herckes, Pierre; Westerhoff, Paul

    2018-04-15

    Phosphorus (P) is an important and often limiting element in terrestrial and aquatic ecosystem. A lack of understanding of its distribution and structures in the environment limits the design of effective P mitigation and recovery approaches. Here we developed a robust method employing size exclusion chromatography (SEC) coupled to an ICP-MS to determine the molecular weight (MW) distribution of P in environmental samples. The most abundant fraction of P varied widely in different environmental samples: (i) orthophosphate was the dominant fraction (93-100%) in one lake, two aerosols and DOC isolate samples, (ii) species of 400-600 Da range were abundant (74-100%) in two surface waters, and (iii) species of 150-350 Da range were abundant in wastewater effluents. SEC-DOC of the aqueous samples using a similar SEC column showed overlapping peaks for the 400-600 Da species in two surface waters, and for >20 kDa species in the effluents, suggesting that these fractions are likely associated with organic matter. The MW resolution and performance of SEC-ICP-MS agreed well with the time integrated results obtained using conventional ultrafiltration method. Results show that SEC in combination with ICP-MS and DOC has the potential to be a powerful and easy-to-use method in identifying unknown fractions of P in the environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Influence of dissolved organic substances in groundwater on sorption behavior of americium and neptunium

    International Nuclear Information System (INIS)

    Boggs, S. Jr.; Seitz, M.G.

    1984-01-01

    Groundwaters typically contain dissolved organic carbon consisting largely of high molecular weight compounds of humic and fulvic acids. To evaluate whether these dissolved organic substances can enhance the tranport of radionuclides through the groundwater system, experiments were conducted to examine the sorption of americium and neptunium onto crushed basalt in the presence of dissolved humic- and fulvic-acid organic carbon introduced into synthetic groundwater. The partitioning experiments with synthetic groundwater show that increasing the concentration of either humic or fulvic acid in the water has a significant inhibiting effect on sorption of both americium and neptunium. At 22 0 C, adsorption of these radionuclides, as measured by distribution ratios (the ratio of nuclide sorbed onto the solid to nuclide in solution at the end of the experiment), decreased by 25% to 50% by addition of as little as 1 mg/L dissolved organic carbon and by one to two orders of magnitude by addition of 100 to 200 mg/L dissolved organic carbon. Distribution ratios measured in solutions reacted at 90 0 C similarly decreased with the addition of dissolved organic carbon but generally ranged from one to two orders of magnitude higher than those determined in the 22 0 C experiment. These results suggest that organic carbon dissolved in deep groundwaters may significantly enhance the mobility of radionuclides of americium and neptunium. 23 references, 5 figures, 11 tables

  15. Composition of dissolved organic nitrogen in rivers associated with wetlands.

    Science.gov (United States)

    Watanabe, Akira; Tsutsuki, Kiyoshi; Inoue, Yudzuru; Maie, Nagamitsu; Melling, Lulie; Jaffé, Rudolf

    2014-09-15

    As basic information for assessing reactivity and functionality of wetland-associated dissolved organic matter (DOM) based on their composition and structural properties, chemical characteristics of N in ultrafiltered DOM (UDON; >1 kD) isolated from wetland-associated rivers in three climates (cool-temperate, Hokkaido, Japan; sub-tropical, Florida, USA; tropical, Sarawak, Malaysia) were investigated. The UDON was isolated during dry and wet seasons, or during spring, summer, and autumn. The proportion of UDON present as humic substances, which was estimated as the DAX-8 adsorbed fraction, ranged from 47 to 91%, with larger values in the Sarawak than at the other sites. The yield of hydrolyzable amino acid N ranged 1.24 to 7.01 mg g(-1), which correlated positively to the total N content of UDOM and tended to be larger in the order of Florida>Hokkaido>Sarawak samples. X-ray photoelectron N1s spectra of UDON showed a strong negative correlation between the relative abundances of amide/peptide N and primary amine N. The relative abundances of amide/peptide N and primary amine N in the Sarawak samples were smaller (70-76%) and larger (20-23%) respectively compared to those (80-88% and 4-9%) in the Florida and Hokkaido samples. Assuming terminal amino groups and amide N of peptides as major constituents of primary amine N and amide/peptide N, respectively, the average molecular weight of peptides was smaller in the Sarawak samples than that in the Florida and Hokkaido samples. Seasonal variations in UDON composition were scarce in the Sarawak and Florida samples, whereas the distribution of humic substance-N and nonhumic substance-N and compositions of amino acids and N functional groups showed a clear seasonality in the Hokkaido samples. While aromatic N increased from spring to autumn, contributions from fresh proteinaceous materials were also enhanced during autumn, resulting in the highest N content of UDOM for this season. Copyright © 2014 Elsevier B.V. All rights

  16. Composition of dissolved organic nitrogen in rivers associated with wetlands

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Akira, E-mail: akiraw@agr.nagoya-u.ac.jp [Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601 (Japan); Tsutsuki, Kiyoshi [Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555 (Japan); Inoue, Yudzuru [Graduate School of Science and Engineering, Saitama University, Sakura, Saitama 338-8570 (Japan); Maie, Nagamitsu [School of Veterinary Medicine, Kitasato University, Towada, Aomori 034-8628 (Japan); Melling, Lulie [Tropical Peat Research Laboratory Unit, Chief Minister' s Department, Jalan Badruddin 93400, Kuching, Sarawak (Malaysia); Jaffé, Rudolf [Southeast Environmental Research Center, Florida International University, 3000 NE 151 Str., Marine Sciences Building, North Miami, FL 33181 (United States); Department of Chemistry and Biochemistry, Florida International University, 3000 NE 151 Str., Marine Sciences Building, North Miami, FL 33181 (United States)

    2014-09-15

    As basic information for assessing reactivity and functionality of wetland-associated dissolved organic matter (DOM) based on their composition and structural properties, chemical characteristics of N in ultrafiltered DOM (UDON; > 1 kD) isolated from wetland-associated rivers in three climates (cool-temperate, Hokkaido, Japan; sub-tropical, Florida, USA; tropical, Sarawak, Malaysia) were investigated. The UDON was isolated during dry and wet seasons, or during spring, summer, and autumn. The proportion of UDON present as humic substances, which was estimated as the DAX-8 adsorbed fraction, ranged from 47 to 91%, with larger values in the Sarawak than at the other sites. The yield of hydrolyzable amino acid N ranged 1.24 to 7.01mg g{sup −1}, which correlated positively to the total N content of UDOM and tended to be larger in the order of Florida > Hokkaido > Sarawak samples. X-ray photoelectron N1s spectra of UDON showed a strong negative correlation between the relative abundances of amide/peptide N and primary amine N. The relative abundances of amide/peptide N and primary amine N in the Sarawak samples were smaller (70–76%) and larger (20–23%) respectively compared to those (80–88% and 4–9%) in the Florida and Hokkaido samples. Assuming terminal amino groups and amide N of peptides as major constituents of primary amine N and amide/peptide N, respectively, the average molecular weight of peptides was smaller in the Sarawak samples than that in the Florida and Hokkaido samples. Seasonal variations in UDON composition were scarce in the Sarawak and Florida samples, whereas the distribution of humic substance-N and nonhumic substance-N and compositions of amino acids and N functional groups showed a clear seasonality in the Hokkaido samples. While aromatic N increased from spring to autumn, contributions from fresh proteinaceous materials were also enhanced during autumn, resulting in the highest N content of UDOM for this season. - Highlights: • DON in

  17. Composition of dissolved organic nitrogen in rivers associated with wetlands

    International Nuclear Information System (INIS)

    Watanabe, Akira; Tsutsuki, Kiyoshi; Inoue, Yudzuru; Maie, Nagamitsu; Melling, Lulie; Jaffé, Rudolf

    2014-01-01

    As basic information for assessing reactivity and functionality of wetland-associated dissolved organic matter (DOM) based on their composition and structural properties, chemical characteristics of N in ultrafiltered DOM (UDON; > 1 kD) isolated from wetland-associated rivers in three climates (cool-temperate, Hokkaido, Japan; sub-tropical, Florida, USA; tropical, Sarawak, Malaysia) were investigated. The UDON was isolated during dry and wet seasons, or during spring, summer, and autumn. The proportion of UDON present as humic substances, which was estimated as the DAX-8 adsorbed fraction, ranged from 47 to 91%, with larger values in the Sarawak than at the other sites. The yield of hydrolyzable amino acid N ranged 1.24 to 7.01mg g −1 , which correlated positively to the total N content of UDOM and tended to be larger in the order of Florida > Hokkaido > Sarawak samples. X-ray photoelectron N1s spectra of UDON showed a strong negative correlation between the relative abundances of amide/peptide N and primary amine N. The relative abundances of amide/peptide N and primary amine N in the Sarawak samples were smaller (70–76%) and larger (20–23%) respectively compared to those (80–88% and 4–9%) in the Florida and Hokkaido samples. Assuming terminal amino groups and amide N of peptides as major constituents of primary amine N and amide/peptide N, respectively, the average molecular weight of peptides was smaller in the Sarawak samples than that in the Florida and Hokkaido samples. Seasonal variations in UDON composition were scarce in the Sarawak and Florida samples, whereas the distribution of humic substance-N and nonhumic substance-N and compositions of amino acids and N functional groups showed a clear seasonality in the Hokkaido samples. While aromatic N increased from spring to autumn, contributions from fresh proteinaceous materials were also enhanced during autumn, resulting in the highest N content of UDOM for this season. - Highlights: • DON in

  18. Dissolved organic carbon pools and export from the coastal ocean

    KAUST Repository

    Barrón, Cristina

    2015-10-21

    The distribution of dissolved organic carbon (DOC) concentration across coastal waters was characterized based on the compilation of 3510 individual estimates of DOC in coastal waters worldwide. We estimated the DOC concentration in the coastal waters that directly exchange with open ocean waters in two different ways, as the DOC concentration at the edge of the shelf break and as the DOC concentration in coastal waters with salinity close to the average salinity in the open ocean. Using these estimates of DOC concentration in the coastal waters that directly exchange with open ocean waters, the mean DOC concentration in the open ocean and the estimated volume of water annually exchanged between coastal and open ocean, we estimated a median ± SE (and average ± SE) global DOC export from coastal to open ocean waters ranging from 4.4 ± 1.0 Pg C yr−1 to 27.0 ± 1.8 Pg C yr−1 (7.0 ± 5.8 Pg C yr−1 to 29.0 ± 8.0 Pg C yr−1) depending on the global hydrological exchange. These values correspond to a median and mean median (and average) range between 14.7 ± 3.3 to 90.0 ± 6.0 (23.3 ± 19.3 to 96.7 ± 26.7) Gg C yr−1 per km of shelf break, which is consistent with the range between 1.4 to 66.1 Gg C yr−1 per km of shelf break of available regional estimates of DOC export. The estimated global DOC export from coastal to open ocean waters is also consistent with independent estimates of the net metabolic balance of the coastal ocean. The DOC export from the coastal to the open ocean is likely to be a sizeable flux and is likely to be an important term in the carbon budget of the open ocean, potentially providing an important subsidy to support heterotrophic activity in the open ocean.

  19. Dissolved organic carbon pools and export from the coastal ocean

    KAUST Repository

    Barró n, Cristina; Duarte, Carlos M.

    2015-01-01

    The distribution of dissolved organic carbon (DOC) concentration across coastal waters was characterized based on the compilation of 3510 individual estimates of DOC in coastal waters worldwide. We estimated the DOC concentration in the coastal waters that directly exchange with open ocean waters in two different ways, as the DOC concentration at the edge of the shelf break and as the DOC concentration in coastal waters with salinity close to the average salinity in the open ocean. Using these estimates of DOC concentration in the coastal waters that directly exchange with open ocean waters, the mean DOC concentration in the open ocean and the estimated volume of water annually exchanged between coastal and open ocean, we estimated a median ± SE (and average ± SE) global DOC export from coastal to open ocean waters ranging from 4.4 ± 1.0 Pg C yr−1 to 27.0 ± 1.8 Pg C yr−1 (7.0 ± 5.8 Pg C yr−1 to 29.0 ± 8.0 Pg C yr−1) depending on the global hydrological exchange. These values correspond to a median and mean median (and average) range between 14.7 ± 3.3 to 90.0 ± 6.0 (23.3 ± 19.3 to 96.7 ± 26.7) Gg C yr−1 per km of shelf break, which is consistent with the range between 1.4 to 66.1 Gg C yr−1 per km of shelf break of available regional estimates of DOC export. The estimated global DOC export from coastal to open ocean waters is also consistent with independent estimates of the net metabolic balance of the coastal ocean. The DOC export from the coastal to the open ocean is likely to be a sizeable flux and is likely to be an important term in the carbon budget of the open ocean, potentially providing an important subsidy to support heterotrophic activity in the open ocean.

  20. Biogeneration of chromophoric dissolved organic matter by bacteria and krill in the southern ocean

    OpenAIRE

    Ortega-Retuerta, E.; Frazer, Thomas K.; Duarte, Carlos M.; Ruiz-Halpern, Sergio; Tovar-Sánchez, Antonio; Arrieta López de Uralde, Jesús M.; Reche, Isabel

    2009-01-01

    Chromophoric dissolved organic matter (CDOM), the optically active fraction of dissolved organic matter, is primarily generated by pelagic organisms in the open ocean. In this study, we experimentally determined the quantity and spectral quality of CDOM generated by bacterioplankton using two different substrates (with and without photoproducts) and by Antarctic krill Euphausia superba and evaluated their potential contributions to CDOM dynamics in the peninsular region of the Southern Ocean....

  1. Dissolved organic carbon in the INDEX area of the Central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Sardessai, S.; De

    -Sea Research II 48 (2001) 3353–3361 Dissolved organic carbon in the INDEX area of the Central Indian Basin Sugandha Sardessai*, S.N. de Sousa National Institute of Oceanography, Dona-Paula, Goa 403 004, India Abstract Dissolved organic carbon (DOC..., 1996). While there is substantial information available on the DOC content of sea water throughout the Atlantic, Pacific and southern oceans, there are limited reports on contents and distribution of this organic fraction in the Indian Ocean (Menzel...

  2. Bioavailability of dissolved organic nitrogen (DON) in wastewaters from animal feedlots and storage lagoons

    Science.gov (United States)

    Dissolved organic nitrogen (DON) transport from animal agriculture to surface waters can lead to eutrophication and dissolved oxygen depletion. Biodegradable DON (BDON) is a portion of DON that is mineralized by bacteria while bioavailable DON (ABDON) is utilized by bacteria and/or algae. This stu...

  3. Determination of the Fate of Dissolved Organic Nitrogen in the Three Wastewater Treatment Plants, Jordan

    Science.gov (United States)

    Wedyan, Mohammed; Al Harahsheh, Ahmed; Qnaisb, Esam

    2016-01-01

    This research aimed to assess the composition of total dissolved nitrogen (TDN) species, particularly dissolved organic nitrogen (DON), over the traditional wastewater treatment operations in three biological nutrient removal (BNR) wastewater treatment plants (WWTPs) in Jordan. It had been found that the DON percentage was up to 30% of TDN within…

  4. Leaching of dissolved organic and inorganic nitrogen from legume-based grasslands

    DEFF Research Database (Denmark)

    Kusliene, Gedrime; Eriksen, Jørgen; Rasmussen, Jim

    2015-01-01

    Leaching of dissolved inorganic nitrogen (DIN) and dissolved organic nitrogen (DON) is a considerable loss pathway in grassland soils. We investigated the white clover (Trifolium repens) contribution to N transport and temporal N dynamics under a pure stand of white clover and white clover...

  5. Organic Matter Remineralization Predominates Phosphorus Cycling in the Mid-Bay Sediments in the Chesapeake Bay

    Energy Technology Data Exchange (ETDEWEB)

    Sunendra, Joshi R.; Kukkadapu, Ravi K.; Burdige, David J.; Bowden, Mark E.; Sparks, Donald L.; Jaisi, Deb P.

    2015-05-19

    The Chesapeake Bay, the largest and most productive estuary in the US, suffers from varying degrees of water quality issues fueled by both point and non–point source nutrient sources. Restoration of the bay is complicated by the multitude of nutrient sources, their variable inputs and hydrological conditions, and complex interacting factors including climate forcing. These complexities not only restrict formulation of effective restoration plans but also open up debates on accountability issues with nutrient loading. A detailed understanding of sediment phosphorus (P) dynamics enables one to identify the exchange of dissolved constituents across the sediment- water interface and aid to better constrain mechanisms and processes controlling the coupling between the sediments and the overlying waters. Here we used phosphate oxygen isotope ratios (δ18Op) in concert with sediment chemistry, XRD, and Mössbauer spectroscopy on the sediment retrieved from an organic rich, sulfidic site in the meso-haline portion of the mid-bay to identify sources and pathway of sedimentary P cycling and to infer potential feedback effect on bottom water hypoxia and surface water eutrophication. Isotope data indicate that the regeneration of inorganic P from organic matter degradation (remineralization) is the predominant, if not sole, pathway for authigenic P precipitation in the mid-bay sediments. We interpret that the excess inorganic P generated by remineralization should have overwhelmed any bottom-water and/or pore-water P derived from other sources or biogeochemical processes and exceeded saturation with respect to authigenic P precipitation. It is the first research that identifies the predominance of remineralization pathway against remobilization (coupled Fe-P cycling) pathway in the Chesapeake Bay. Therefore, these results are expected to have significant implications for the current understanding of P cycling and benthic-pelagic coupling in the bay, particularly on the

  6. Forcing of dissolved organic carbon release by phytoplankton by anticyclonic mesoscale eddies in the subtropical NE Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    S. Lasternas

    2013-03-01

    Full Text Available The organic carbon fluxes mediated by planktonic communities in two cyclonic eddies (CEs and two anticyclonic eddies (AEs at the Canary Eddy Corridor were studied and compared with the dynamics in two far-field (FF stations located outside the eddies. We observed favorable conditions and signs for upwelling at the center of CEs and for downwelling and mixing at the centers of AEs. CEs were characterized by a higher concentration of nutrients and the highest concentration of chlorophyll a (chl a, associated with the highest abundance of microphytoplankton and diatoms. AEs displayed concentrations of chl a values and nutrients similar to those at the FF stations, except for the highest ammonium concentration occurring at AE and a very low concentration of phosphorus at FF stations. AEs were transient systems characterized by an increasing abundance of picophytoplankton and heterotrophic bacteria. While primary production was similar between the systems, the production of dissolved organic carbon (PDOC was significantly higher in the AEs. Phytoplankton cell mortality was lowest in the CEs, and we found higher cell mortality rates at AE than at FF stations, despite similar chl a concentration. Environmental changes in the AEs have been significantly prejudicial to phytoplankton as indicated by higher phytoplankton cell mortality (60% of diatoms cells were dead and higher cell lysis rates. The adverse conditions for phytoplankton associated with the early-stage anticyclonic systems, mainly triggered by active downwelling, resulted in higher cell mortality, forcing photosynthesized carbon to fuel the dissolved pool.

  7. Cosorption study of organic pollutants and dissolved organic matter in a soil

    Energy Technology Data Exchange (ETDEWEB)

    Flores-Cespedes, F. [Department of Inorganic Chemistry, University of Almeria, La Canada de San Urbano s/n, 04120 Almeria (Spain); Fernandez-Perez, M. [Department of Inorganic Chemistry, University of Almeria, La Canada de San Urbano s/n, 04120 Almeria (Spain)]. E-mail: mfernand@ual.es; Villafranca-Sanchez, M. [Department of Inorganic Chemistry, University of Almeria, La Canada de San Urbano s/n, 04120 Almeria (Spain); Gonzalez-Pradas, E. [Department of Inorganic Chemistry, University of Almeria, La Canada de San Urbano s/n, 04120 Almeria (Spain)

    2006-08-15

    In this study we have evaluated the effects of dissolved organic matter (DOM) on sorption of imidacloprid, 3,4-dichloroaniline (3,4-DCA) and 4-bromoaniline (4-BA) on a typical calcareous soil (Luvic Xerosol) from south-eastern Spain. Two different types of DOM were used, that is to say, dissolved natural organic matter extracts from a commercial peat (DNOM) and a high-purity tannic acid (TA) solution. The experiments were carried out in a 0.01 M CaCl{sub 2} aqueous medium at 25 deg. C. The results indicated that the presence of both DNOM and TA, over a concentration range of 15-100 mg L{sup -1}, produced an increase in the amount of 3,4-DCA and 4-BA sorbed and a decrease in the amount of imidacloprid retained on the soil studied. A modified distribution coefficient, K {sub doc}, has been proposed as a safer parameter for soil sorption predictions of organic pollutants and it could be of help to model the fate of these in the environment. - Cosorption of organic pollutants and DOM.

  8. Cosorption study of organic pollutants and dissolved organic matter in a soil

    International Nuclear Information System (INIS)

    Flores-Cespedes, F.; Fernandez-Perez, M.; Villafranca-Sanchez, M.; Gonzalez-Pradas, E.

    2006-01-01

    In this study we have evaluated the effects of dissolved organic matter (DOM) on sorption of imidacloprid, 3,4-dichloroaniline (3,4-DCA) and 4-bromoaniline (4-BA) on a typical calcareous soil (Luvic Xerosol) from south-eastern Spain. Two different types of DOM were used, that is to say, dissolved natural organic matter extracts from a commercial peat (DNOM) and a high-purity tannic acid (TA) solution. The experiments were carried out in a 0.01 M CaCl 2 aqueous medium at 25 deg. C. The results indicated that the presence of both DNOM and TA, over a concentration range of 15-100 mg L -1 , produced an increase in the amount of 3,4-DCA and 4-BA sorbed and a decrease in the amount of imidacloprid retained on the soil studied. A modified distribution coefficient, K doc , has been proposed as a safer parameter for soil sorption predictions of organic pollutants and it could be of help to model the fate of these in the environment. - Cosorption of organic pollutants and DOM

  9. Complementary Enzymes Activities in Organic Phosphorus Mineralization and Cycling by Phosphohydrolases in Soils

    Science.gov (United States)

    Inorganic and organic phosphates react strongly with soil constituents, resulting in relatively low concentrations of soluble phosphates in the soil solution. Multiple competing reactions control the solution-phase concentration and the cycling of phosphorus-containing organic substrates and the re...

  10. Effect of continuous addition of an organic substrate to the anoxic phase on biological phosphorus removal

    DEFF Research Database (Denmark)

    Meinhold, Jens; Pedersen, Heinz; Arnold, Eva

    1998-01-01

    The continuous introduction of a biological phosphorus removal (BPR) promoting organic substrate to the denitrifying reactor of a BPR process is examined through a series of batch experiments using acetate as model organic substrate. Several observations are made regarding the influence of substr...

  11. 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.

  12. Exoenzyme activities as indicators of dissolved organic matter composition in the hyporheic zone of a floodplain river

    Science.gov (United States)

    Sandra M. Clinton; Rick T. Edwards; Stuart E.G. Findlay

    2010-01-01

    We measured the hyporheic microbial exoenzyme activities in a floodplain river to determine whether dissolved organic matter (DOM) bioavailability varied with overlying riparian vegetation patch structure or position along flowpaths. Particulate organic matter (POM), dissolved organic carbon (DOC), dissolved oxygen (DO), electrical conductivity and temperature were...

  13. Chromophoric Dissolved Organic Material, Aqua MODIS, NPP, 0.125 degrees, East US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS data is used to develop an index of the amount of chromophoric dissolved organic material (CDOM) in the surface waters. CDOM absorbs heavily in the blue...

  14. Chromophoric Dissolved Organic Material, Aqua MODIS, NPP, 0.125 degrees, West US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS data is used to develop an index of the amount of chromophoric dissolved organic material (CDOM) in the surface waters. CDOM absorbs heavily in the blue...

  15. Northern Gulf of Mexico estuarine coloured dissolved organic matter derived from MODIS data

    Science.gov (United States)

    Coloured dissolved organic matter (CDOM) is relevant for water quality management and may become an important measure to complement future water quality assessment programmes. An approach to derive CDOM using the Moderate Resolution Imaging Spectroradiometer (MODIS) was developed...

  16. Origin of heat-induced structural changes in dissolved organic matter

    Czech Academy of Sciences Publication Activity Database

    Drastík, M.; Novák, František; Kučerík, J.

    2013-01-01

    Roč. 90, č. 2 (2013), s. 789-795 ISSN 0045-6535 Institutional support: RVO:60077344 Keywords : dissolved organic matter * humic substances * hydration * hysteresis Subject RIV: DF - Soil Science Impact factor: 3.499, year: 2013

  17. CHROMOPHORIC DISSOLVED ORGANIC MATTER (CDOM) SOURCE CHARACTERIZATION IN THE LOUISIANA BIGHT

    Science.gov (United States)

    Chromophoric dissolved organic matter (CDOM) in the Mississippi plume region may have several distinct sources: riverine (terrestrial soils), wetland (terrestrial plants), biological production (phytoplankton, zooplankton, microbial), and sediments. Complex mixing, photodegradati...

  18. Photobleaching Kinetics of Chromophoric Dissolved Organic Matter Derived from Mangrove Leaf Litter and Floating Sargassum Colonies

    Science.gov (United States)

    We examined the photoreactivity of chromophoric dissolved organic matter (CDOM) derived from Rhizophora mangle (red mangrove) leaf litter and floating Sargassum colonies as these marine plants can be important contributors to coastal and open ocean CDOM pools, respectively. Mangr...

  19. Distinct optical chemistry of dissolved organic matter in urban pond ecosystems

    Czech Academy of Sciences Publication Activity Database

    McEnroe, N. A.; Williams, C. J.; Xenopoulos, M. A.; Porcal, Petr; Frost, P. C.

    2013-01-01

    Roč. 8, č. 11 (2013), e80334 E-ISSN 1932-6203 Institutional support: RVO:60077344 Keywords : dissolved organic matter * photodegradation * fluorescence * PARAFAC Subject RIV: DA - Hydrology ; Limnology Impact factor: 3.534, year: 2013

  20. Drivers of fluorescent dissolved organic matter in the global epipelagic ocean

    KAUST Repository

    Catalá , T. S.; Á lvarez-Salgado, X. A.; Otero, J.; Iuculano, F.; Companys, B.; Horstkotte, B.; Romera-Castillo, C.; Nieto-Cid, M.; Latasa, M.; Moran, Xose Anxelu G.; Gasol, J. M.; Marrasé , C.; Stedmon, C. A.; Reche, I.

    2016-01-01

    Fluorescent dissolved organic matter (FDOM) in open surface waters (< 200 m) of the Atlantic, Pacific, and Indian oceans was analysed by excitation-emission matrix (EEM) spectroscopy and parallel factor analysis (PARAFAC). A four-component PARAFAC

  1. Chromophoric Dissolved Organic Material, Aqua MODIS, NPP, 0.125 degrees, Gulf of Mexico

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS data is used to develop an index of the amount of chromophoric dissolved organic material (CDOM) in the surface waters. CDOM absorbs heavily in the blue...

  2. Chromophoric Dissolved Organic Material, Aqua MODIS, NPP, 0.05 degrees, Global, Science Quality

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS data is used to develop an index of the amount of chromophoric dissolved organic material (CDOM) in the surface waters. CDOM absorbs heavily in the blue...

  3. Response to Comment on "Dilution limits dissolved organic carbon utilization in the deep ocean"

    KAUST Repository

    Arrieta, J M; Mayol, E.; Hansman, R. L.; Herndl, G. J.; Dittmar, T.; Duarte, Carlos M.

    2015-01-01

    Our recent finding that dilution limits dissolved organic carbon (DOC) utilization in the deep ocean has been criticized based on the common misconception that lability equates to rapid and complete utilization. Even when considering

  4. Cosorption study of organic pollutants and dissolved organic matter in a soil.

    Science.gov (United States)

    Flores-Céspedes, F; Fernández-Pérez, M; Villafranca-Sánchez, M; González-Pradas, E

    2006-08-01

    In this study we have evaluated the effects of dissolved organic matter (DOM) on sorption of imidacloprid, 3,4-dichloroaniline (3,4-DCA) and 4-bromoaniline (4-BA) on a typical calcareous soil (Luvic Xerosol) from south-eastern Spain. Two different types of DOM were used, that is to say, dissolved natural organic matter extracts from a commercial peat (DNOM) and a high-purity tannic acid (TA) solution. The experiments were carried out in a 0.01 M CaCl2 aqueous medium at 25 degrees C. The results indicated that the presence of both DNOM and TA, over a concentration range of 15-100 mg L(-1), produced an increase in the amount of 3,4-DCA and 4-BA sorbed and a decrease in the amount of imidacloprid retained on the soil studied. A modified distribution coefficient, K(doc), has been proposed as a safer parameter for soil sorption predictions of organic pollutants and it could be of help to model the fate of these in the environment.

  5. Sources, fluxes, and behaviors of fluorescent dissolved organic matter (FDOM) in the Nakdong River Estuary, Korea

    Science.gov (United States)

    Lee, Shin-Ah; Kim, Guebuem

    2018-02-01

    We monitored seasonal variations in dissolved organic carbon (DOC), the stable carbon isotope of DOC (δ13C-DOC), and fluorescent dissolved organic matter (FDOM) in water samples from a fixed station in the Nakdong River Estuary, Korea. Sampling was performed every hour during spring tide once a month from October 2014 to August 2015. The concentrations of DOC and humic-like FDOM showed significant negative correlations against salinity (r2 = 0.42-0.98, p ocean.

  6. Chromophoric dissolved organic matter in experimental mesocosms maintained under different pCO2 levels

    OpenAIRE

    Rochelle-Newall, E.; Delille, B.; Frankignoulle, M.; Gattuso, J.-P.; Jacquet, S.; Riebesell, Ulf; Terbrüggen, A.; Zondervan, I.

    2004-01-01

    Chromophoric dissolved organic matter (CDOM) represents the optically active fraction of the bulk dissolved organic matter (DOM) pool. Recent evidence pointed towards a microbial source of CDOM in the aquatic environment and led to the proposal that phytoplankton is not a direct source of CDOM, but that heterotrophic bacteria, through reprocessing of DOM of algal origin, are an important source of CDOM. In a recent experiment designed at looking at the effects of elevated pCO2 on blooms of th...

  7. [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.

  8. 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.

  9. Utilizing chromophoric dissolved organic matter measurements to derive export and reactivity of dissolved organic carbon exported to the Arctic Ocean: A case study of the Yukon River, Alaska

    Science.gov (United States)

    Spencer, R.G.M.; Aiken, G.R.; Butler, K.D.; Dornblaser, M.M.; Striegl, Robert G.; Hernes, P.J.

    2009-01-01

    The quality and quantity of dissolved organic matter (DOM) exported by Arctic rivers is known to vary with hydrology and this exported material plays a fundamental role in the biogeochemical cycling of carbon at high latitudes. We highlight the potential of optical measurements to examine DOM quality across the hydrograph in Arctic rivers. Furthermore, we establish chromophoric DOM (CDOM) relationships to dissolved organic carbon (DOC) and lignin phenols in the Yukon River and model DOC and lignin loads from CDOM measurements, the former in excellent agreement with long-term DOC monitoring data. Intensive sampling across the historically under-sampled spring flush period highlights the importance of this time for total export of DOC and particularly lignin. Calculated riverine DOC loads to the Arctic Ocean show an increase from previous estimates, especially when new higher discharge data are incorporated. Increased DOC loads indicate decreased residence times for terrigenous DOM in the Arctic Ocean with important implications for the reactivity and export of this material to the Atlantic Ocean. Citation: Spencer, R. G. M., G. R. Aiken, K. D. Butler, M. M. Dornblaser, R. G. Striegl, and P. J. Hernes (2009), Utilizing chromophoric dissolved organic matter measurements to derive export and reactivity of dissolved organic carbon exported to the Arctic Ocean: A case study of the Yukon River, Alaska, Geophys. Res. Lett., 36, L06401, doi:10.1029/ 2008GL036831. Copyright 2009 by the American Geophysical Union.

  10. Phosphorus sorption on marine carbonate sediment: phosphonate as model organic compounds.

    Science.gov (United States)

    Huang, Xiao-Lan; Zhang, Jia-Zhong

    2011-11-01

    Organophosphonate, characterized by the presence of a stable, covalent, carbon to phosphorus (C-P) bond, is a group of synthetic or biogenic organophosphorus compounds. The fate of these organic phosphorus compounds in the environment is not well studied. This study presents the first investigation on the sorption of phosphorus (P) in the presence of two model phosphonate compounds, 2-aminothylphosphonoic acid (2-AEP) and phosphonoformic acid (PFA), on marine carbonate sediments. In contrast to other organic P compounds, no significant inorganic phosphate exchange was observed in seawater. P was found to adsorb on the sediment only in the presence of PFA, not 2-AEP. This indicated that sorption of P from phosphonate on marine sediment was compound specific. Compared with inorganic phosphate sorption on the same sediments, P sorption from organic phosphorus is much less in the marine environment. Further study is needed to understand the potential role of the organophosphonate compounds in biogeochemical cycle of phosphorus in the environment. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Photo-dissolution of flocculent, detrital material in aquatic environments: contributions to the dissolved organic matter pool.

    Science.gov (United States)

    Pisani, Oliva; Yamashita, Youhei; Jaffé, Rudolf

    2011-07-01

    This study shows that light exposure of flocculent material (floc) from the Florida Coastal Everglades (FCE) results in significant dissolved organic matter (DOM) generation through photo-dissolution processes. Floc was collected at two sites along the Shark River Slough (SRS) and irradiated with artificial sunlight. The DOM generated was characterized using elemental analysis and excitation emission matrix fluorescence coupled with parallel factor analysis. To investigate the seasonal variations of DOM photo-generation from floc, this experiment was performed in typical dry (April) and wet (October) seasons for the FCE. Our results show that the dissolved organic carbon (DOC) for samples incubated under dark conditions displayed a relatively small increase, suggesting that microbial processes and/or leaching might be minor processes in comparison to photo-dissolution for the generation of DOM from floc. On the other hand, DOC increased substantially (as much as 259 mgC gC(-1)) for samples exposed to artificial sunlight, indicating the release of DOM through photo-induced alterations of floc. The fluorescence intensity of both humic-like and protein-like components also increased with light exposure. Terrestrial humic-like components were found to be the main contributors (up to 70%) to the chromophoric DOM (CDOM) pool, while protein-like components comprised a relatively small percentage (up to 16%) of the total CDOM. Simultaneously to the generation of DOC, both total dissolved nitrogen and soluble reactive phosphorus also increased substantially during the photo-incubation period. Thus, the photo-dissolution of floc can be an important source of DOM to the FCE environment, with the potential to influence nutrient dynamics in this system. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Advancing understanding of the fluvial export of organic matter through high-resolution profiling of dissolved organic carbon.

    Science.gov (United States)

    Waldron, S.; Drew, S.; Gilvear, D.; Murray, H.; Heal, K.

    2012-04-01

    Quantifying the natural variation (complexity) of a system remains an enduring scientific challenge in better understanding controls on surface water quality. This characterisation is needed in order to reveal controlling processes, such as dilution, and also to identify unusual load profiles. In trying to capture that natural variation we still rely largely on concentration time series (and associated export budgets) generated from manual spot sampling, or from samples collected by autosamplers - approaches which are unlikely to provide the high temporal resolution of parameter concentration required. Now however, advances in sensor technology are helping us address this challenge. Here we present detailed dissolved organic carbon (DOC) export profiles from a small upland river (9.4 km sq.), generated since June 2011 by semi-continuous logging of UV-vis absorption (200-750 nm, every 2.5 nm) every 30 minutes. Observed increases in the concentration of the DOC, [DOC], in freshwaters have prompted significant research to understand the cause and consequences of increased export: higher levels of DOC require additional water purification of potable sources; increased aquatic export may represent a reduction in terrestrial C-soil sequestration; changes in light penetration can affect the heterotrophic / autotrophic balance in surface waters and this has consequences for the food web structure; increased aquatic export may also result in increased carbon dioxide evasion. Additionally, C export is often linked to nutrient export: we have observed statistically significant stoichiometric relationships between DOC and soluble reactive phosphorus (SRP) concentrations, thus understanding better this parameters offers insight into export of other nutrient and the source of material from which these dissolved compounds are produced; this may be particulate. Our Scottish study site is interesting because there are multiple processes that can contribute to DOC and other nutrient

  13. Simultaneous effect of dissolved organic carbon, surfactant, and organic acid on the desorption of pesticides investigated by response surface methodology

    DEFF Research Database (Denmark)

    Trinh, Ha Thu; Duong, Hanh Thi; Ta, Thao Thi

    2017-01-01

    Desorption of pesticides (fenobucarb, endosulfan, and dichlorodiphenyltrichloroethane (DDT)) from soil to aqueous solution with the simultaneous presence of dissolved organic carbon (DOC), sodium dodecyl sulfate (SDS), and sodium oxalate (Oxa) was investigated in batch test by applying a full...

  14. Facilitated transport of polychlorinated biphenyls and polybrominated diphenyl ethers by dissolved organic matter.

    NARCIS (Netherlands)

    ter Laak, T.L.; van Eijkeren, J.C.; Busser, F.; van Leeuwen, H.P.; Hermens, J.L.M.

    2009-01-01

    The exchange rate of hydrophobic organic chemicals between the aqueous phase and a sorbent (e.g., soil, organism, passive sampler) is relevant for distribution processes between environmental compartments, including organisms. Dissolved phases such as humic acids, proteins, and surfactants can

  15. Facilitated transport of polychlorinated biphenyls and polybrominated diphenyl ethers by dissolved organic matter

    NARCIS (Netherlands)

    Laak, ter T.L.; Eijkeren, van J.C.H.; Busser, F.J.M.; Leeuwen, van H.P.; Hermens, J.L.

    2009-01-01

    The exchange rate of hydrophobic organic chemicals between the aqueous phase and a sorbent (e.g., soil, organism, passive sampler) is relevant for distribution processes between environmental compartments, including organisms. Dissolved phases such as humic acids, proteins, and surfactants can

  16. Dynamics of dissolved organic carbon in a stream during a quarter century of forest succession

    Science.gov (United States)

    Judy L. Meyer; Jackson Webster; Jennifer Knoepp; E.F. Benfield

    2014-01-01

    Dissolved organic carbon (DOC) is a heterogeneous mixture of compounds that makes up a large fraction of the organic matter transported in streams. It plays a significant role in many ecosystems. Riverine DOC links organic carbon cycles of continental and oceanic ecosystems. It is a significant trophic resource in stream food webs. DOC imparts color to lakes,...

  17. Reclamation of cadmium-contaminated soil using dissolved organic matter solution originating from wine-processing waste sludge

    International Nuclear Information System (INIS)

    Liu, Cheng-Chung; Chen, Guan-Bu

    2013-01-01

    Highlights: ► Increases in acidity, washing frequency, and operational temperature enhance the Cd removal. ► Approximately 80% of Cd can be removed from the soil by dissolved organic matter (DOM) washing. ► The DOM washing can moderate the loss of soil fertility. ► The DOM washing will have a great improvement if we employ NaOH, KOH, Ca(OH) 2 , and Mg(OH) 2 to prepare the DOM solution together. -- Abstract: Soil washing using an acid solution is a common practice for removing heavy metals from contaminated soil in Taiwan. However, serious loss of nutrients from soil is a major drawback of the washing. Distillery sludge can be used to prepare a dissolved organic matter (DOM) solution by extracting its organic constituents with alkaline solutions. This study employed DOM solutions to remediate Cd-contaminated soil (with concentrations up to 21.5 mg kg −1 ) and determine the factors affecting removal of Cd, such as pH, initial concentration of DOM solution, temperature, and washing frequency. When washing with pH 3.0 and 1250 mg L −1 DOM solution, about 80% and 81% of Cd were removed from the topsoil at 27 °C and subsoil at 40 °C, respectively. To summarize the changes in fertility during DOM washing with various pH solutions: the increase in organic matter content ranged from 7.7% to 23.7%; cation exchange capacity (CEC) ranged from 4.6% to 13.9%; available ammonium (N-NH 4 ) content ranged from 39.4% to 2175%; and available phosphorus content ranged from 34.5% to 182%. Exchangeable K, Ca, and Mg remained in the topsoil after DOM washing, with concentrations of 1.1, 2.4, and 1.5 times higher than those treated with HCl solution at the same pH, respectively

  18. 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.

  19. Organic phosphorus fractionation in wetland soil profiles by chemical extraction and phosphorus-31 nuclear magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Li, Min; Zhang, Jing; Wang, Guangqian; Yang, Haijun; Whelan, Michael J.; White, Sue M.

    2013-01-01

    Highlights: ► Chemical sequential extraction and 31 P NMR spectroscopy were used for organic P analysis. ► Organic P includes orthophosphate, monoester and diester phosphate and pyrophosphate. ► Highly resistant organic P and monoester phosphate were the dominant organic P. ► HCl pretreatment can remove most inorganic P and increase organic P recovery rate. ► A comprehensive organic P chemical sequential fractionation approach was proposed. - Abstract: Organic P (OP) plays an important role in soil P cycling and is a potential P source for wetland plants. In this study, a modified chemical sequential fractionation method and 31 P nuclear magnetic resonance spectroscopy ( 31 P NMR) of NaOH–EDTA extracts were used to examine the distribution of organic P fractions and compounds in soil profiles of the Beijing Yeyahu Wetland, China. The influence of acid treatment prior to NaOH–EDTA extraction on 31 P NMR spectra was also investigated. Results show that highly resistant OP was the major class of organic P. The rank order of organic P fractions was highly resistant OP (on average accounting for 68.5% of total OP) > moderately resistant OP (15.8%m of total OP) > moderately labile OP (11.4% of total OP) > labile OP (4.3% of total OP). Most of the organic P fractions decreased with soil depth due to the accumulation of plant residues in surface soils and the deposition and diagenesis of soils. Moderately (r = 0.586, p < 0.01) and highly (r = 0.741, p < 0.01) resistant OP fractions were positively correlated with soil organic matter. Phosphorus compounds including orthophosphate (23–74.6% of total P in spectra), monoester phosphate (18.6–76%), diester phosphate (nil-7.8%) and pyrophosphate (nil-6.7%) were characterized using 31 P NMR. Monoester-P was the dominant soil organic P compound identified. The proportion of monoester-P increased significantly in NaOH–EDTA extracts with HCl pretreatment and it was confirmed by chemical analysis. Therefore, it

  20. Effects of sulfate deposition on pore water dissolved organic carbon, nutrients, and microbial enzyme activities in a northern peatland

    Science.gov (United States)

    Export of dissolved organic carbon from lakes and streams has increased throughout Europe and North America over the past several decades. One possible cause is altered deposition chemistry; specifically, decreasing sulfate inputs leading to changes in ionic strength and dissolve...

  1. Innovative process scheme for removal of organic matter, phosphorus and nitrogen from pig manure

    DEFF Research Database (Denmark)

    Karakashev, Dimitar Borisov; Schmidt, Jens Ejbye; Angelidaki, Irini

    2008-01-01

    blanket (UASB) reactor, partial oxidation), nitrogen (oxygen-limited autotrophic nitrification-denitrification, OLAND) and phosphorus (phosphorus removal by precipitation as struvite, PRS) from pig manure were tested. Results obtained showed that microfiltration was unsuitable for pig manure treatment....... PRS treated effluent was negatively affecting the further processing of the pig manure in UASB, and was therefore not included in the final process flow scheme. In a final scheme (PIGMAN concept) combination of the following successive process steps was used: thermophilic anaerobic digestion...... with sequential separation by decanter centrifuge, post-digestion in UASB reactor, partial oxidation and finally OLAND process. This combination resulted in reduction of the total organic, nitrogen and phosphorus contents by 96%, 88%, and 81%, respectively....

  2. Determination of organic phosphorus in UO2C2O4·TRPO complex

    International Nuclear Information System (INIS)

    Guo Yifei; Yuan Jianhua; Liang Junfu; Jiao Rongzhou; Liu Xiuqin

    2001-01-01

    Organic phosphorus in UO 2 C 2 O 4 ·TRPO complex is converted to inorganic phosphorous with H 2 SO 4 -HNO 3 -H 2 O 2 wet cinefaction method. In 0.14 mol/L H 2 SO 4 solution containing water soluble poly vinylalcohol as stabilizing agent, the highly sensitive ion-associates are formed by the reaction of basic dye ethyl violet with heteropoly molybdophosphoric blue. Spectrophotometric method is used for determination of phosphorus with these ion-associates. The absorbance maximum is at 620 nm. Determination of phosphorus is not affected with mass ratios R(UO 2 2+ /P) ≤ 1.4 x 10 3 , R(C 2 O 4 2- /P) ≤ 8.8 x 10 2 and R(C 2 O 4 2- /P ≤ 3.6 x 10 4 (one time wet cinefaction must be carried out). In aqueous phase, phosphorus can be directly developed and determined. This method is contrasted with poly vinylalcohol-Rodamine B-heteropoly molybdophosphoric blue, analytical results are in good coincidence. Conversion ratio of phosphorus is 99.8% - 101.1%. The minimum detection limit is 0.02 mg/L. The relative standard deviation is 3%. The recovery ratio is 97% - 103%

  3. Reclamation of cadmium-contaminated soil using dissolved organic matter solution originating from wine-processing waste sludge.

    Science.gov (United States)

    Liu, Cheng-Chung; Chen, Guan-Bu

    2013-01-15

    Soil washing using an acid solution is a common practice for removing heavy metals from contaminated soil in Taiwan. However, serious loss of nutrients from soil is a major drawback of the washing. Distillery sludge can be used to prepare a dissolved organic matter (DOM) solution by extracting its organic constituents with alkaline solutions. This study employed DOM solutions to remediate Cd-contaminated soil (with concentrations up to 21.5 mg kg(-1)) and determine the factors affecting removal of Cd, such as pH, initial concentration of DOM solution, temperature, and washing frequency. When washing with pH 3.0 and 1250 mg L(-1) DOM solution, about 80% and 81% of Cd were removed from the topsoil at 27 °C and subsoil at 40 °C, respectively. To summarize the changes in fertility during DOM washing with various pH solutions: the increase in organic matter content ranged from 7.7% to 23.7%; cation exchange capacity (CEC) ranged from 4.6% to 13.9%; available ammonium (NNH(4)) content ranged from 39.4% to 2175%; and available phosphorus content ranged from 34.5% to 182%. Exchangeable K, Ca, and Mg remained in the topsoil after DOM washing, with concentrations of 1.1, 2.4, and 1.5 times higher than those treated with HCl solution at the same pH, respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. 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.

  5. Bioavailability and export of dissolved organic matter from a tropical river during base- and stormflow conditions

    Science.gov (United States)

    Tracy N. Wiegner; Randee L. Tubal; Richard A. MacKenzie

    2009-01-01

    Concentrations, bioavailability, and export of dissolved organic matter (DOM), particulate organic matter (POM), and nutrients from the Wailuku River, Hawai'i, U.S.A., were examined under base- and stormflow conditions. During storms, DOM and POM concentrations increased approximately by factors of 2 and 11, respectively, whereas NO3...

  6. Differential recycling of coral and algal dissolved organic matter via the sponge loop

    NARCIS (Netherlands)

    Rix, L.; de Goeij, J.M.; van Oevelen, D.; Struck, U.; Al-Horani, F.A.; Wild, C.; Naumann, M.S.

    Corals and macroalgae release large quantities of dissolved organic matter (DOM), one of the largest sources of organic matter produced on coral reefs. By rapidly taking up DOM and transforming it into particulate detritus, coral reef sponges are proposed to play a key role in transferring the

  7. Uptake of allochthonous dissolved organic matter from soil and salmon in coastal temperate rainforest streams

    Science.gov (United States)

    Jason B. Fellman; Eran Hood; Richard T. Edwards; Jeremy B. Jones

    2009-01-01

    Dissolved organic matter (DOM) is an important component of aquatic food webs. We compare the uptake kinetics for NH4-N and different fractions of DOM during soil and salmon leachate additions by evaluating the uptake of organic forms of carbon (DOC) and nitrogen (DON), and proteinaceous DOM, as measured by parallel factor (PARAFAC) modeling of...

  8. Nonconservative behavior of dissolved organic carbon across the Laptev and East Siberian seas

    NARCIS (Netherlands)

    Alling, Vanja; Sanchez-Garcia, Laura; Porcelli, Don; Pugach, Sveta; Vonk, Jorien E.; Van Dongen, Bart; Mörth, Carl Magnus; Anderson, Leif G.; Sokolov, Alexander; Andersson, Per; Humborg, Christoph; Semiletov, Igor P.; Gustafsson, Örjan

    2010-01-01

    Climate change is expected to have a strong effect on the Eastern Siberian Arctic Shelf (ESAS) region, which includes 40% of the Arctic shelves and comprises the Laptev and East Siberian seas. The largest organic carbon pool, the dissolved organic carbon (DOC), may change significantly due to

  9. Characteristics of dissolved organic matter following 20 years of peatland restoration

    NARCIS (Netherlands)

    Höll, B.S.; Fiedler, S.; Jungkunst, H.F.; Kalbitz, K.; Freibauer, A.; Drösler, M.; Stahr, K.

    2009-01-01

    The changes in the amounts and composition of dissolved organic matter (DOM) following long-term peat restoration are unknown, although this fraction of soil organic matter affects many processes in such ecosystems. We addressed this lack of knowledge by investigating a peatland in south-west

  10. Linking aboveground net primary productivity to soil carbon and dissolved organic carbon in complex terrain

    Science.gov (United States)

    F.S. Peterson; K. Lajtha

    2013-01-01

    Factors influencing soil organic matter (SOM) stabilization and dissolved organic carbon (DOC) content in complex terrain, where vegetation, climate, and topography vary over the scale of a few meters, are not well understood. We examined the spatial correlations of lidar and geographic information system-derived landscape topography, empirically measured soil...

  11. FACTORS AFFECTING COLORED DISSOLVED ORGANIC MATTER IN AQUATIC ENVIRONMENTS OF THE SOUTHEASTERN UNITED STATES

    Science.gov (United States)

    The sunlight-absorbing (colored) component of dissolved organic matter (CDOM) in aquatic environments is widely distributed in freshwaters and coastal regions where it influences the fate and transport of toxic organic substances and biologically-important metals such as mercury,...

  12. Stabilization of dissolved organic matter by aluminium: A toxic effect or stabilization through precipitation?

    NARCIS (Netherlands)

    Scheel, T.; Jansen, B.; van Wijk, A.J.; Verstraten, J.M.; Kalbitz, K.

    2008-01-01

    Carbon mineralization in acidic forest soils can be retarded by large concentrations of aluminium (Al). However, it is still unclear whether Al reduces C mineralization by direct toxicity to microorganisms or by decreased bioavailability of organic matter (OM) because dissolved organic matter (DOM)

  13. Phosphorus Speciation of Forest-soil Organic Surface Layers using P K-edge XANES Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    J Prietzel; J Thieme; D Paterson

    2011-12-31

    The phosphorus (P) speciation of organic surface layers from two adjacent German forest soils with different degree of water-logging (Stagnosol, Rheic Histosol) was analyzed by P K-edge XANES and subsequent Linear Combination Fitting. In both soils, {approx}70% of the P was inorganic phosphate and {approx}30% organic phosphate; reduced P forms such as phosphonate were absent. The increased degree of water-logging in the Histosol compared to the Stagnosol did not affect P speciation.

  14. Transport of organic contaminants in subsoil horizons and effects of dissolved organic matter related to organic waste recycling practices.

    Science.gov (United States)

    Chabauty, Florian; Pot, Valérie; Bourdat-Deschamps, Marjolaine; Bernet, Nathalie; Labat, Christophe; Benoit, Pierre

    2016-04-01

    Compost amendment on agricultural soil is a current practice to compensate the loss of organic matter. As a consequence, dissolved organic carbon concentration in soil leachates can be increased and potentially modify the transport of other solutes. This study aims to characterize the processes controlling the mobility of dissolved organic matter (DOM) in deep soil layers and their potential impacts on the leaching of organic contaminants (pesticides and pharmaceutical compounds) potentially present in cultivated soils receiving organic waste composts. We sampled undisturbed soil cores in the illuviated horizon (60-90 cm depth) of an Albeluvisol. Percolation experiments were made in presence and absence of DOM with two different pesticides, isoproturon and epoxiconazole, and two pharmaceutical compounds, ibuprofen and sulfamethoxazole. Two types of DOM were extracted from two different soil surface horizons: one sampled in a plot receiving a co-compost of green wastes and sewage sludge applied once every 2 years since 1998 and one sampled in an unamended plot. Results show that DOM behaved as a highly reactive solute, which was continuously generated within the soil columns during flow and increased after flow interruption. DOM significantly increased the mobility of bromide and all pollutants, but the effects differed according the hydrophobic and the ionic character of the molecules. However, no clear effects of the origin of DOM on the mobility of the different contaminants were observed.

  15. Linkage between the temporal and spatial variability of dissolved organic matter and whole-stream metabolism

    Directory of Open Access Journals (Sweden)

    S. Halbedel

    2013-08-01

    Full Text Available Dissolved organic matter (DOM is an important resource for microbes, thus affecting whole-stream metabolism. However, the factors influencing its chemical composition and thereby also its bio-availability are complex and not thoroughly understood. It was hypothesized that whole-stream metabolism is linked to DOM composition and that the coupling of both is influenced by seasonality and different land-use types. We tested this hypothesis in a comparative study on two pristine forestry streams and two non-forestry streams. The investigated streams were located in the Harz Mountains (central Europe, Germany. The metabolic rate was measured with a classical two-station oxygen change technique and the variability of DOM with fluorescence spectroscopy. All streams were clearly net heterotrophic, whereby non-forestry streams showed a higher primary production, which was correlated to irradiance and phosphorus concentration. We detected three CDOM components (C1, C2, C3 using parallel factor (PARAFAC analysis. We compared the excitation and emission maxima of these components with the literature and correlated the PARAFAC components with each other and with fluorescence indices. The correlations suggest that two PARAFAC components are derived from allochthonous sources (C1, C3 and one is derived autochthonously (C2. The chromophoric DOM matrix was dominated by signals of humic-like substances with a highly complex structure, followed by humic-like, fulfic acids, low-molecular-weight substances, and with minor amounts of amino acids and proteins. The ratios of these PARAFAC components (C1 : C2, C1 : C3, C3 : C2 differed with respect to stream types (forestry versus non-forestry. We demonstrated a significant correlation between gross primary production (GPP and signals of autochthonously derived, low-molecular-weight humic-like substances. A positive correlation between P / R (i.e. GPP/daily community respiration and the fluorescence index FI suggests

  16. Fluorescent dissolved organic matter in the continental shelf waters ...

    Indian Academy of Sciences (India)

    Ocean and receives a large freshwater influx ca. 1600 km3 yr ... oceanic surface area of 1.13%, this influx consti- ... the Bay. The export flux of total organic carbon ..... Cycles 20. GB2006. Benner R 2002 Chemical composition and reactivity;.

  17. Thallium and Silver binding to dissolved organic matter

    Science.gov (United States)

    Benedetti, M. F.; Martin, L.; Simonucci, C.; Viollier, E.

    2017-12-01

    Silver (Ag) and thallium (Tl) are potential contaminants at the vicinity of mining sites and are harmful pollutants. Silver can be found in mine but also as released by the dissolution of Silver nanoparticles, a major new emerging contaminant. Tl is both lithophilic and calcophilic elements and found in sulphur ores (associated with lead, zinc, antimony…) or in rocks containing K-feldspar. Speciation of Ag and Tl is poorly known mainly due to their low concentrations in aquatic environments. Review of Ag and Tl geochemistry clearly shows a lack of quantitative information about interactions with natural organic matter. Organic ligands could play an important role in Ag or Tl bioavailability, chemical reactivity (adsorption or photo oxidation inhibition or catalysis) and hence geochemical transfers. Based on equilibrium between two solutions that are separated by a selectively permeable membrane, the so-called "Donnan membrane technique" (DMT) provides a measure of free ion concentrations. Analytes measurements are performed by HR-ICP-MS Element 2 (Thermo Scientific). Experimental setup allows the Donnan equilibrium to be reached after 100 and 120 hours for Tl. Experiments performed with purified natural organic matter allow calculating complexation constants in multiple pH conditions. With this work, we contribute new data and interpretations to an active debate on Ag and Tl geochemical modeling. In conclusion, this work brings a new view on risk assessment for mining activities.

  18. Predicting nitrogen and acidity effects on long-term dynamics of dissolved organic matter

    OpenAIRE

    Rowe, E.C.; Tipping, E.; Posch, M.; Oulehle, Filip; Cooper, D.M.; Jones, T.G.; Burden, A.; Hall, J.; Evans, C.D.

    2014-01-01

    Increases in dissolved organic carbon (DOC) fluxes may relate to changes in sulphur and nitrogen pollution. We integrated existing models of vegetation growth and soil organic matter turnover, acid-base dynamics, and organic matter mobility, to form the ‘MADOC’ model. After calibrating parameters governing interactions between pH and DOC dissolution using control treatments on two field experiments, MADOC reproduced responses of pH and DOC to additions of acidifying and alkalising solutions. ...

  19. Interactions Between Prokaryotes and Dissolved Organic Matter in Marine Waters

    DEFF Research Database (Denmark)

    Traving, Sachia Jo

    organic bound carbon equal in size to atmospheric carbon dioxide. Prokaryotes mediate the fate of a large part of marine DOM, which is their principal source of energy and substrate. However, a large fraction is also left behind in the water column persisting for millennia, and prokaryotes may hold...... the key to understanding the mechanisms controlling the cycling of DOM within marine waters. In the thesis presented here, the aim was to investigate the activity and composition of prokaryotes to determine their functional role in DOM utilization. The thesis incorporates a range of study systems...

  20. Improved automation of dissolved organic carbon sampling for organic-rich surface waters.

    Science.gov (United States)

    Grayson, Richard P; Holden, Joseph

    2016-02-01

    In-situ UV-Vis spectrophotometers offer the potential for improved estimates of dissolved organic carbon (DOC) fluxes for organic-rich systems such as peatlands because they are able to sample and log DOC proxies automatically through time at low cost. In turn, this could enable improved total carbon budget estimates for peatlands. The ability of such instruments to accurately measure DOC depends on a number of factors, not least of which is how absorbance measurements relate to DOC and the environmental conditions. Here we test the ability of a S::can Spectro::lyser™ for measuring DOC in peatland streams with routinely high DOC concentrations. Through analysis of the spectral response data collected by the instrument we have been able to accurately measure DOC up to 66 mg L(-1), which is more than double the original upper calibration limit for this particular instrument. A linear regression modelling approach resulted in an accuracy >95%. The greatest accuracy was achieved when absorbance values for several different wavelengths were used at the same time in the model. However, an accuracy >90% was achieved using absorbance values for a single wavelength to predict DOC concentration. Our calculations indicated that, for organic-rich systems, in-situ measurement with a scanning spectrophotometer can improve fluvial DOC flux estimates by 6 to 8% compared with traditional sampling methods. Thus, our techniques pave the way for improved long-term carbon budget calculations from organic-rich systems such as peatlands. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Iron Hydroxide Minerals Drive Organic and Phosphorus Chemistry in Subsurface Redox / pH Gradients

    Science.gov (United States)

    Flores, E.; Barge, L. M.; VanderVelde, D.; Baum, M.

    2017-12-01

    Iron minerals, particularly iron oxides and oxyhydroxides, are prevalent on Mars and may exist in mixed valence or even reduced states beneath the oxidized surface. Iron (II,III) hydroxides, including green rust, are reactive and potentially catalytic minerals that can absorb and concentrate charged species, while also driving chemical reactions. These minerals are highly redox-sensitive and the presence of organics and/or phosphorus species could affect their mineralogy and/or stability. Conversely, the minerals might be able to drive chemical processes such as amino acid formation, phosphorus oxyanion reactions, or could simply selectively preserve organic species via surface adsorption. In an open aqueous sediment column, soluble products of mineral-driven reactions could also diffuse to sites of different chemical conditions to react even further. We synthesized Fe-hydroxide minerals under various conditions relevant to early Earth and ancient Mars (>3.0 Gyr), anoxically and in the presence of salts likely to have been present in surface or ground waters. Using these minerals we conducted experiments to test whether iron hydroxides could promote amino acid formation, and how the reaction is affected by subsurface gradients of redox, pH, and temperature. We also tested the adsorption of organic and phosphorus species onto Fe-hydroxide minerals at different conditions within the gradients. The suite of organic or phosphorus signatures that may be found in a particular mineral system is a combination of what is synthesized there, what is preferentially concentrated / retained there, and what is preserved against degradation. Further work is needed to determine how these processes could have proceeded on Mars and what mineral-organic signatures, abiotic or otherwise, would be produced from such processes.

  2. 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...

  3. Species and biogeochemical cycles of organic phosphorus in sediments from a river with different aquatic plants located in Huaihe River Watershed, China.

    Science.gov (United States)

    Yuan, He Zhong; Pan, Wei; Ren, Li Jun; Liu, Eeng Feng; Shen, Ji; Geng, Qi Fang; An, Shu Qing

    2015-01-01

    The results of phosphorus fractionation in the sediments from a contaminated river containing different aquatic plants, analyzed by solution 31P-NMR for Organic Phosphorus, showed that the concentration of Inorganic Phosphorus dominated in all species and Organic Phosphorus accounted for over 20% of Total Phosphorus. In general, orthophosphate was dominant in all the sampling sites. The proportion of Organic Phosphorus accounting for the Total Phosphorus in the sediments with different plant decreased in the following order: Paspalum distichum>Typha orientalis>Hydrilla verticillata. Phosphorus-accumulation ability of Paspalum distichum was obviously stronger than Typha orientalis and Hydrilla verticillata. The Organic Phosphorus was in aquatic plants dominated by humic-associated P (Hu-P), which converted to Inorganic Ohosphorus more significantly in submerged plants than in emerged plants. The sediment dominated by Paspalum distichum abundantly accumulated Organic Phosphorus in the orthophosphate monoester fraction. The degradation and mineralization of orthophosphate monoester was the important source of high Inorganic Phosphorus concentration and net primary productivity in Suoxu River. The Organic Phosphorus derived from Typha orientalis and Hydrilla verticillata was dramatically converted to Inorganic Phosphorus when the environmental factors varied.

  4. Freshwater processing of terrestrial dissolved organic matter: What governs lability?

    Science.gov (United States)

    D'Andrilli, J.; Smith, H. J.; Junker, J. R.; Scholl, E. A.; Foreman, C. M.

    2016-12-01

    Aquatic and terrestrial ecosystems are linked through the transfer of energy and materials. Allochthonous organic matter (OM) is central to freshwater ecosystem function, influencing local food webs, trophic state, and nutrient availability. In order to understand the nature and fate of OM from inland headwaters to the open ocean, it is imperative to understand the links between OM lability and ecosystem function. Thus, biological, chemical, and physical factors need to be evaluated together to inform our understanding of environmental lability. We performed a laboratory processing experiment on naturally occurring OM leachates from riparian leaves, grasses, and pine needles. Measures of water chemistry, OM optical and molecular characterization, bacterial abundances, microbial assemblage composition, respiration, and C:N:P were integrated to discern the nature and fate of labile and recalcitrant OM in a freshwater stream. Peak processing of all OM sources in the stream water occurred after two days, with spikes in bacterial cell abundances, respiration rates, microbial assemblage shifts, and maximum C utilization. Respiration rates and microbial assemblages were dependent on the degree of lability of the OM molecular composition. Within the first few days, no differences in respiration rates were observed between leachate sources, however, beyond day five, the rates diverged with C processing efficiency correlated with OM lability. Originally comprised of amino acid-like, labile fluorescent species, the inoculated stream water OM became more recalcitrant after 16 days, indicating humification processing over time. Our study highlights the importance of interdisciplinary approaches for understanding the processing and fate of OM in aquatic ecosystems.

  5. Iodometric microdetermination of phosphorus in organic compounds by use of An amplification reaction

    OpenAIRE

    Al Kubaisi, A. H. [عبد الله حسين الكبيسي; Farag, A. B.; Amin, R. R.

    1994-01-01

    A high chemical amplification method is described for the iodometric microdetermination of phosphorus in organic compounds. This method depends on combustion by the oxygen flask, absorption of the combustion products in distilled water and conversion to orthophosphoric acid with bromine water. The phosphoric acid produced is then allowed to react with sodium molybdate in acid medium to form phosphomolybdic acid which is extracted into a mixture of diethyl ether and pentanol (5:1, V/V), and ba...

  6. Predicting nitrogen and acidity effects on long-term dynamics of dissolved organic matter

    International Nuclear Information System (INIS)

    Rowe, E.C.; Tipping, E.; Posch, M.; Oulehle, F.; Cooper, D.M.; Jones, T.G.; Burden, A.; Hall, J.; Evans, C.D.

    2014-01-01

    Increases in dissolved organic carbon (DOC) fluxes may relate to changes in sulphur and nitrogen pollution. We integrated existing models of vegetation growth and soil organic matter turnover, acid–base dynamics, and organic matter mobility, to form the ‘MADOC’ model. After calibrating parameters governing interactions between pH and DOC dissolution using control treatments on two field experiments, MADOC reproduced responses of pH and DOC to additions of acidifying and alkalising solutions. Long-term trends in a range of acid waters were also reproduced. The model suggests that the sustained nature of observed DOC increases can best be explained by a continuously replenishing potentially-dissolved carbon pool, rather than dissolution of a large accumulated store. The simulations informed the development of hypotheses that: DOC increase is related to plant productivity increase as well as to pH change; DOC increases due to nitrogen pollution will become evident, and be sustained, after soil pH has stabilised. -- Highlights: • A model of dissolved organic carbon (DOC) was developed by integrating simple models • MADOC simulates effects of sulphur and nitrogen deposition and interactions with pH. • Responses of DOC and pH to experimental acidification and alkalisation were reproduced. • The persistence of DOC increases will depend on continued supply of potential DOC. • DOC fluxes are likely determined by plant productivity as well as soil solution pH. -- Effects of changes in sulphur and nitrogen pollution on dissolved organic carbon fluxes are predicted by simulating soil organic matter cycling, the release of potentially-dissolved carbon, and interactions with soil pH

  7. Tracing dissolved organic matter (DOM) from land-based aquaculture systems in North Patagonian streams

    DEFF Research Database (Denmark)

    Nimptsch, Jorge; Woelfl, Stefan; Osorio, Sebastian

    2015-01-01

    Chile is the second largest producer of salmonids worldwide. The first step in the production of salmonids takes place in land-based aquacultures. However, the effects of the discharge from these aquacultures on stream dissolved organic matter (DOM) content, molecular composition and degradabilit...

  8. TREATMENT OF URBAN STORMWATER FOR DISSOLVED POLLUTANTS: A COMPARATIVE STUDY OF THREE NATURAL ORGANIC MEDIA

    Science.gov (United States)

    The feasibility of using hard and soft wood tree mulch and processed jute fiber, as filter media, for treating mixtures of dissolved pollutants (toxic organic compounds and heavy metals) in urban stormwater (SW) runoff was evaluated. Copper (Cu), cadmium (Cd), chromium (Cr+6), l...

  9. Effects of watershed history on dissolved organic matter characteristics in headwater streams

    Science.gov (United States)

    Youhei Yamashita; Brian D. Kloeppel; Jennifer Knoepp; Gregory L. Zausen; Rudolf Jaffe'

    2011-01-01

    Dissolved organic matter (DOM) is recognized as a major component in the global carbon cycle and is an important driver in aquatic ecosystem function. Climate, land use, and forest cover changes all impact stream DOM and alter biogeochemical cycles in terrestrial environments. We determined the temporal variation in DOM quantity and quality in headwater streams at a...

  10. Seasonal changes in photochemical properties of dissolved organic matter in small boreal streams

    Czech Academy of Sciences Publication Activity Database

    Porcal, Petr; Dillon, P. J.; Molot, L. A.

    2013-01-01

    Roč. 10, č. 8 (2013), s. 5533-5543 ISSN 1726-4170 R&D Projects: GA ČR(CZ) GAP503/12/0781 Institutional support: RVO:60077344 Keywords : photodegradation * dissolved organic matter * seasonal * stream Subject RIV: DA - Hydrology ; Limnology Impact factor: 3.753, year: 2013

  11. Dissolved organic carbon fluxes from hydropedologic units in Alaskan coastal temperate rainforest watersheds

    Science.gov (United States)

    David V. D' Amore; Rick T. Edwards; Paul A. Herendeen; Eran Hood; Jason B. Fellman

    2015-01-01

    Dissolved organic C (DOC) transfer from the landscape to coastal margins is a key component of regional C cycles. Hydropedology provides a conceptual and observational framework for linking soil hydrologic function to landscape C cycling. We used hydropedology to quantify the export of DOC from the terrestrial landscape and understand how soil temperature and water...

  12. The effect of increased loads of dissolved organic matter on estuarine microbial community composition and function

    DEFF Research Database (Denmark)

    Traving, Sachia J.; Rowe, Owen; Jakobsen, Nina M.

    2017-01-01

    Increased river loads are projected as one of the major consequences of climate change in the northern hemisphere, leading to elevated inputs of riverine dissolved organic matter (DOM) and inorganic nutrients to coastal ecosystems. The objective of this study was to investigate the effects...

  13. Biogeochemical relationships between ultrafiltered dissolved organic matter and picoplankton activity in the Eastern Mediterranean Sea

    NARCIS (Netherlands)

    Meador, Travis B.; Gogou, Alexandra; Spyres, Georgina; Herndl, Gerhard J.; Krasakopoulou, Evangelia; Psarra, Stella; Yokokawa, Taichi; De Corte, Daniele; Zervakis, Vassilis; Repeta, Daniel J.

    2010-01-01

    We targeted the warm, subsurface waters of the Eastern Mediterranean Sea (EMS) to investigate processes that are linked to the chemical composition and cycling of dissolved organic carbon (DOC) in seawater. The apparent respiration of semi-labile DOC accounted for 27 +/- 18% of oxygen consumption in

  14. Interaction of extrinsic chemical factors affecting photodegradation of dissolved organic matter in aquatic ecosystems

    Czech Academy of Sciences Publication Activity Database

    Porcal, Petr; Dillon, P. J.; Molot, L. A.

    2014-01-01

    Roč. 13, č. 5 (2014), s. 799-812 ISSN 1474-905X R&D Projects: GA ČR(CZ) GAP503/12/0781 Institutional support: RVO:60077344 Keywords : photodegradation * dissolved organic matter * calcium * nitrate * iron * pH Subject RIV: DA - Hydrology ; Limnology Impact factor: 2.267, year: 2014

  15. Dissolved organic carbon leaching from plastics stimulates microbial activity in the ocean

    NARCIS (Netherlands)

    Romera-Castillo, C.; Pinto, M.; Langer, T.M.; Alvarez-Salgado, X.A.; Herndl, G.

    2018-01-01

    Approximately 5.25 trillion plastic pieces are floating at the sea surface. The impact of plastic pollution on the lowest trophic levels of the food web, however, remains unknown. Here we show that plastics release dissolved organic carbon (DOC) into the ambient seawater stimulating the activity of

  16. PRODUCTION OF HYDRATED ELECTRONS FROM PHOTOIONIZATION OF DISSOLVED ORGANIC MATTER IN NATURAL WATERS

    Science.gov (United States)

    Under UV irradiation, an important primary photochemical reaction of colored dissolved organic matter (CDOM) is electron ejection, producing hydrated electrons (e-aq). The efficiency of this process has been studied in both fresh and seawater samples with both steady-state scave...

  17. Response to Comment on "Dilution limits dissolved organic carbon utilization in the deep ocean"

    KAUST Repository

    Arrieta, Jesus

    2015-12-18

    Our recent finding that dilution limits dissolved organic carbon (DOC) utilization in the deep ocean has been criticized based on the common misconception that lability equates to rapid and complete utilization. Even when considering the redefinition of recalcitrant DOC recently proposed by Jiao et al., the dilution hypothesis best explains our experimental observations.

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

    NARCIS (Netherlands)

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

    2010-01-01

    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

  19. Effect of light availability on dissolved organic carbon release by Caribbean reef algae and corals

    NARCIS (Netherlands)

    Mueller, B.; van der Zande, R.M.; van Leent, P.J.M.; Meesters, E.H.; Vermeij, M.J.A.; van Duyl, F.C.

    2014-01-01

    Dissolved organic carbon (DOC) release of three algal and two coral species was determined at three light intensities (0, 30–80, and 200–400 µmol photons m–2 s–1) in ex situ incubations to quantify the effect of light availability on DOC release by reef primary producers. DOC release of three

  20. Net removal of dissolved organic carbon in the anoxic waters of the Black Sea

    NARCIS (Netherlands)

    Margolin, A.R.; Gerringa, L.J.A.; Hansell, D.A.; Rijkenberg, M.J.A.

    2016-01-01

    Dissolved organic carbon (DOC) concentrations in the deep Black Sea are ~2.5 times higher than found in the globalocean. The two major external sources of DOC are rivers and the Sea of Marmara, a transit point for waters from theMediterranean Sea. In addition, expansive phytoplankton blooms

  1. INFLUENCE OF DISSOLVED ORGANIC MATTER ON AGROCHEMICAL PHOTOREACTIONS IN AQUATIC ENVIRONMENTS

    Science.gov (United States)

    Pioneering studies by Don Crosby and co-workers demonstrated that the sunlight-induced dissipation of agrochemicals in water often is strongly affected by natural constituents in the water such as nitrate and dissolved organic matter. In this presentation, the focus is on the rol...

  2. Method for removing and decolorizing aqueous waste effluents containing dissolved or dispersed organic matter

    International Nuclear Information System (INIS)

    Case, F.N.; Ketchen, E.E.

    1975-01-01

    A method is provided for treating organic waste material dissolved or dispersed in an aqueous effluent, which comprises contacting the effluent with an inert particulate carbonaceous sorbent at an oxygen pressure up to 2000 psi, irradiating the resultant mixture with high energy radiation until a decolorized liquid is produced, and then separating the decolorized liquid

  3. 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

  4. Linking variability in soil solution dissolved organic carbon to climate, soil type, and vegetation type

    NARCIS (Netherlands)

    Camino-Serrano, Marta; Gielen, Bert; Luyssaert, Sebastiaan; Ciais, Philippe; Vicca, Sara; Guenet, Bertrand; Vos, Bruno De; Cools, Nathalie; Ahrens, Bernhard; Altaf Arain, M.; Borken, Werner; Clarke, Nicholas; Clarkson, Beverley; Cummins, Thomas; Don, Axel; Pannatier, Elisabeth Graf; Laudon, Hjalmar; Moore, Tim; Nieminen, Tiina M.; Nilsson, Mats B.; Peichl, Matthias; Schwendenmann, Luitgard; Siemens, Jan; Janssens, Ivan

    2014-01-01

    Lateral transport of carbon plays an important role in linking the carbon cycles of terrestrial and aquatic ecosystems. There is, however, a lack of information on the factors controlling one of the main C sources of this lateral flux, i.e., the concentration of dissolved organic carbon (DOC) in

  5. 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

  6. Dissolved organic nitrogen and carbon release by a marine unicellular diazotrophic cyanobacterium

    NARCIS (Netherlands)

    Benavides, M.; Agawin, N.S.R.; Aristegui, J.; Peene, J.; Stal, L.J.

    2013-01-01

    Dinitrogen (N-2) fixation rates may be underestimated when recently fixed N2 is released as dissolved organic nitrogen (DON). DON release (DONr) is substantial in the filamentous cyanobacterium Trichodesmium but has never been reported in unicellular diazotrophic cyanobacteria. We used axenic

  7. Dissolved organic nitrogen and carbon release by a marine unicellular diazotrophic cyanobacterium

    NARCIS (Netherlands)

    Benavides, M.; Agawin, N.S.R.; Aristegui, J.; Peene, J.; Stal, L.J.

    2013-01-01

    Dinitrogen (N2) fixation rates may be underestimated when recently fixed N2 is released as dissolved organic nitrogen (DON). DON release (DONr) is substantial in the filamentous cyanobacterium Trichodesmium but has never been reported in unicellular diazotrophic cyanobacteria. We used axenic

  8. Production of Chromophoric Dissolved Organic Matter from Mangrove Leaf Litter and Floating Sargassum Colonies

    Science.gov (United States)

    Chromophoric dissolved organic matter (CDOM) strongly absorbs solar radiation in the blue-green and serves as the primary attenuator of water column ultraviolet radiation (UV-R). CDOM interferes with remote sensing of ocean chlorophyll and can control UV-R-induced damage to light...

  9. Drivers of fluorescent dissolved organic matter in the global epipelagic ocean

    DEFF Research Database (Denmark)

    Catalá, T.S.; Álvarez-Salgado, X. A.; Otero, J.

    2016-01-01

    Fluorescent dissolved organic matter (FDOM) in open surface waters (< 200 m) of the Atlantic, Pacific, and Indian oceans was analysed by excitation-emission matrix (EEM) spectroscopy and parallel factor analysis (PARAFAC). A four-component PARAFAC model was fit to the EEMs, which included two hum...

  10. Response of soil dissolved organic matter to microplastic addition in Chinese loess soil

    NARCIS (Netherlands)

    Liu, Hongfei; Yang, Xiaomei; Liu, Guobin; Liang, Chutao; Xue, Sha; Chen, Hao; Ritsema, Coen J.; Geissen, Violette

    2017-01-01

    Plastic debris is accumulating in agricultural land due to the increased use of plastic mulches, which is causing serious environmental problems, especially for biochemical and physical properties of the soil. Dissolved organic matter (DOM) plays a central role in driving soil biogeochemistry, but

  11. Long-Term Experimental Acidification Drives Watershed Scale Shift in Dissolved Organic Matter Composition and Flux

    Science.gov (United States)

    Michael D. SanClements; Ivan J. Fernandez; Robert H. Lee; Joshua A. Roberti; Mary Beth Adams; Garret A. Rue; Diane M. McKnight

    2018-01-01

    Over the last several decades dissolved organic carbon concentrations (DOC) in surface waters have increased throughout much of the northern hemisphere. Several hypotheses have been proposed regarding the drivers of this phenomenon including decreased sulfur (S) deposition working via an acidity- change mechanism. Using fluorescence spectroscopy and data from two long-...

  12. Effect of dissolved organic carbon in recycled wastewaters on boron adsorption by soils

    Science.gov (United States)

    In areas of water scarcity, recycled municipal wastewaters are being used as water resources for non-potable applications, especially for irrigation. Such wastewaters often contain elevated levels of dissolved organic carbon (DOC) and solution boron (B). Boron adsorption was investigated on eight ...

  13. Characterization of the dissolved organic carbon in landfill leachate-polluted groundwater

    DEFF Research Database (Denmark)

    Christensen, Jette B.; Jensen, Dorthe Lærke; Grøn, Christian

    1998-01-01

    Samples of dissolved organic carbon (DOG) were obtained from landfill leachate-polluted groundwater at Vejen Landfill, Denmark. The humic acids, fulvic acids and the hydrophilic fraction were isolated and purified. Based on DOC measurements, the fulvic acid fraction predominated, accounting...

  14. Quantifying the production of dissolved organic nitrogen in headwater streams using 15N tracer additions

    Science.gov (United States)

    Laura T. Johnson; Jennifer L. Tank; Robert O. Hall; Patrick J. Mullholland; Stephen K. Hamilton; H. Maurice Valett; Jackson R. Webster; Melody J. Bernot; William H. McDowell; Bruce J. Peterson; Suzanne M. Thomas

    2013-01-01

    Most nitrogen (N) assimilation in lake and marine ecosystems is often subsequently released via autochthonous dissolved organic nitrogen (DON) production, but autochthonous DON production has yet to be quantified in flowing waters. We measured in-stream DON production following 24 h 15N-nitrate (NO3-...

  15. The role of dissolved organic matter in adsorbing heavy metals in clay-rich soils

    NARCIS (Netherlands)

    Refaey, Y.; Jansen, B.; El-Shater, A.H.; El-Haddad, A.A.; Kalbitz, K.

    2014-01-01

    Adsorption of tested heavy metals on Egyptian soils was large in all situations tested and follows the order: Cu >> Ni ≈ Zn. Copper was influenced by the timing of dissolved organic matter addition more than Ni and Zn. Specific binding mechanisms (inner-sphere complexes) dominated the affinity of Cu

  16. Complexation with dissolved organic matter and solubility control of heavy metals in sandy soil

    NARCIS (Netherlands)

    Weng, L.; Temminghoff, E.J.M.; Lofts, S.; Tipping, E.; Riemsdijk, van W.H.

    2002-01-01

    The complexation of heavy metals with dissolved organic matter (DOM) in the environment influences the solubility and mobility of these metals. In this paper, we measured the complexation of Cu, Cd, Zn, Ni, and Pb with DOM in the soil solution at pH 3.7-6.1 using a Donnan membrane technique. The

  17. Dynamics of dissolved and extractable organic nitrogen upon soil amendment with crop residues

    NARCIS (Netherlands)

    Ros, G.H.; Hoffland, E.

    2010-01-01

    Dissolved organic nitrogen (DON) is increasingly recognized as a pivotal pool in the soil nitrogen (N) cycle. Numerous devices and sampling procedures have been used to estimate its size, varying from in situ collection of soil solution to extraction of dried soil with salt solutions. Extractable

  18. Dynamics of Intracellular Polymers in Enhanced Biological Phosphorus Removal Processes under Different Organic Carbon Concentrations

    Directory of Open Access Journals (Sweden)

    Lizhen Xing

    2013-01-01

    Full Text Available Enhanced biological phosphorus removal (EBPR may deteriorate or fail during low organic carbon loading periods. Polyphosphate accumulating organisms (PAOs in EBPR were acclimated under both high and low organic carbon conditions, and then dynamics of polymers in typical cycles, anaerobic conditions with excess organic carbons, and endogenous respiration conditions were examined. After long-term acclimation, it was found that organic loading rates did not affect the yield of PAOs and the applied low organic carbon concentrations were advantageous for the enrichment of PAOs. A low influent organic carbon concentration induced a high production of extracellular carbohydrate. During both anaerobic and aerobic endogenous respirations, when glycogen decreased to around 80 ± 10 mg C per gram of volatile suspended solids, PAOs began to utilize polyphosphate significantly. Regressed by the first-order reaction model, glycogen possessed the highest degradation rate and then was followed by polyphosphate, while biomass decay had the lowest degradation rate.

  19. Oxidation by UV and ozone of organic contaminants dissolved in deionized and raw mains water

    International Nuclear Information System (INIS)

    Francis, P.D.

    1987-01-01

    Organic contaminants dissolved in deionized pretreated and raw mains water were reacted with ultraviolet light and ozone. Ozone first was used for partial oxidation followed by ozone combined with ultraviolet radiation to produce total oxidation. The reduction of total organic carbon (TOC) level and direct oxidation of halogenated compounds were measured throughout the treatment process. The rate of TOC reduction was compared for ozone injected upstream and inside the reactor

  20. A watershed-scale characterization of dissolved organic carbon and nutrients on the South Carolina Coastal Plain

    Science.gov (United States)

    Daniel Tufford; Setsen Alton-Ochir

    2016-01-01

    Dissolved organic matter (DOM) is recognized as a major component in the global carbon cycle and is an important driver of numerous biogeochemical processes in aquatic ecosystems, both in-stream and downstream in estuaries. This study sought to characterize chromophoric DOM (CDOM), dissolved organic carbon (DOC), and dissolved nutrients in major rivers and their...

  1. A watershed-scale characterication of dissolved organic carbon and nutrients on the South Carolina Coastal Plain

    Science.gov (United States)

    Daniel L. Tufford; Setsen Alton-Ochir; Warren Hankinson

    2016-01-01

    Dissolved organic matter (DOM) is recognized as a major component in the global carbon cycle and is an important driver of numerous biogeochemical processes in aquatic ecosystems, both in-stream and downstream in estuaries. This study sought to characterize chromophoric DOM (CDOM), dissolved organic carbon (DOC), and dissolved nutrients in major rivers and their...

  2. Understanding dissolved organic matter reactivity in a global context: tribute to Dr. George Aiken's many contributions

    Science.gov (United States)

    McKnight, Diane

    2017-04-01

    As Dr. George Aiken emphasized throughout his distinguished research career, the diversity of sources of dissolved organic material (DOM) is associated with a diversity of dissolved organic compounds with a range of chemistries and reactivities that are present in the natural environment. From a limnological perspective, dissolved organic matter (DOM) can originate from allochthonous sources on the landscape which drains into a lake, river, wetland, coastal region, or other aquatic ecosystem, or from autochthonous sources within the given aquatic ecosystem. In many landscapes, the precursor organic materials that contribute to the DOM of the associated aquatic ecosystem can be derived from diverse sources, e.g. terrestrial plants, plant litter, organic material in different soil horizons, and the products of microbial growth and decay. Yet, through his focus on the underlying chemical processes a clear, chemically robust foundation for understanding DOM reactivity has emerged from Aiken's research. These processes include the enhancement in solubility due to ionized carboxylic acid functional groups and the reactions of organic sulfur groups with mercury. This approach has advanced understand of carbon cycling in the lakes of the Mars-like barren landscapes of the McMurdo Dry Valleys in Antarctica and the rivers draining the warming tundra of the Arctic.

  3. The Relationship Between Dissolved Organic Matter Composition and Organic Matter Optical Properties in Freshwaters

    Science.gov (United States)

    Aiken, G.; Spencer, R. G.; Butler, K.

    2010-12-01

    Dissolved organic matter (DOM) chemistry and flux are potentially useful, albeit, underutilized, indicators of watershed characteristics, climate influences on watershed hydrology and soils, and changes associated with resource management. Source materials, watershed geochemistry, oxidative processes and hydrology exert strong influences on the nature and reactivity of DOM in aquatic systems. The molecules that comprise DOM, in turn, control a number of environmental processes important for ecosystem function including light penetration and photochemistry, microbial activity, mineral dissolution/precipitation, and the transport and reactivity of hydrophobic compounds and metals (e.g. Hg). In particular, aromatic molecules derived from higher plants exert strong controls on aquatic photochemistry, and on the transport and biogeochemistry of metals. Assessment of DOM composition and transport, therefore, can provide a basis for understanding watershed processes and biogeochemistry of rivers and streams. Here we present results of multi-year studies designed to assess the seasonal and spatial variability of DOM quantity and quality for 57 North American Rivers. DOM concentrations and composition, based on DOM fractionation on XAD resins, ultraviolet (UV)/visible absorption and fluorescence spectroscopic analyses, and specific compound analyses, varied greatly both between sites and seasonally within a given site. DOM in these rivers exhibited a wide range of concentration (4000 µM C* L-1) and specific ultra-violet absorbance at 254 nm (SUVA254) (0.6 to 5 L *mg C-1 *m-1), an optical measurement that is an indicator of aromatic carbon content. In almost all systems, UV absorbance measured at specific wavelengths (e.g. 254 nm) correlated strongly with DOM and hydrophobic organic acid (HPOA) content (aquatic humic substances). The relationships between dissolved organic carbon (DOC) concentration and absorbance for the range of systems were quite variable due to

  4. Production and degradation of fluorescent dissolved organic matter in surface waters of the eastern north Atlantic ocean

    NARCIS (Netherlands)

    Lønborg, C.; Yokokawa, T.; Herndl, G.J.; Alvarez-Salgado, X.A.

    2015-01-01

    The distribution and fate of coloured dissolved organic matter (CDOM) in the epipelagic Eastern North Atlantic was investigated during a cruise in the summer 2009 by combining field observations and culture experiments. Dissolved organic carbon (DOC) and nitrogen (DON), the absorption spectra of

  5. Effects of sulfate deposition on pore water dissolved organic carbon, nutrients, and microbial enzyme activities in a northern peatland

    Science.gov (United States)

    L.R. Seifert-Monson; B.H. Hill; R.K. Kolka; T.M. Jicha; L.L. Lehto; C.M. Elonen

    2014-01-01

    Export of dissolved organic carbon from lakes and streams has increased throughout Europe and North America over the past several decades. One possible cause is altered deposition chemistry; specifically, decreasing sulfate inputs leading to changes in ionic strength and dissolved organic carbon solubility. To further investigate the relationship between deposition...

  6. Role of microbes associated with organic and inorganic substrates in phosphorus spiralling in a woodland stream

    International Nuclear Information System (INIS)

    Elwood, J.W.; Newbold, J.D.; O'Neill, R.V.; Stark, R.W.; Singley, P.T.

    1980-01-01

    Laboratory and field experiments were conducted to determine if nutrient spiralling is primarily a biological process. The experiments were conducted to examine the role of microbial uptake and abiotic sorption onto organic and inorganic substrates in the uptake of PO 4 -P in Walker Branch, a small, first-order woodland stream in east Tennessee, to estimate the total, microbial, and adsorptive pool sizes of exchangeable phosphorus associated with five particulate organic matter from this stream, and to measure the turnover rate of PO 4 -P by live and sterile inorganic substrates in Walker Branch

  7. Carbon transfer from dissolved organic carbon to the cladoceran Bosmina: a mesocosm study

    Directory of Open Access Journals (Sweden)

    Tang Yali

    2017-01-01

    Full Text Available A mesocosm study illuminated possible transfer pathways for dissolved organic carbon from the water column to zooplankton. Organic carbon was added as 13C enriched glucose to 15 mesocosms filled with natural lake water. Stable isotope analysis and phospholipid fatty acids-based stable isotope probing were used to trace the incorporation of 13C into the cladoceran Bosmina and its potential food items. Glucose-C was shown to be assimilated into phytoplankton (including fungi and heterotrophic protists, bacteria and Bosmina, all of which became enriched with 13C during the experiment. The study suggests that bacteria play an important role in the transfer of glucose-C to Bosmina. Furthermore, osmotic algae, fungi and heterotrophic protists might also contribute to the isotopic signature changes observed in Bosmina. These findings help to clarify the contribution of dissolved organic carbon to zooplankton and its potential pathways.

  8. Tracing the long-term microbial production of recalcitrant fluorescent dissolved organic matter in seawater

    DEFF Research Database (Denmark)

    Jørgensen, Linda; Stedmon, Colin A.; Granskog, Mats A.

    2014-01-01

    The majority of dissolved organic matter (DOM) in the ocean is resistant to microbial degradation, yet its formation remains poorly understood. The fluorescent fraction of DOM can be used to trace the formation of recalcitrant DOM (RDOM). A long-term (> 1 year) experiment revealed 27–52% removal...... of dissolved organic carbon and a nonlinear increase in RDOM fluorescence associated with microbial turnover of semilabile DOM. This fluorescence was also produced using glucose as the only initial carbon source, suggesting that degradation of prokaryote remnants contributes to RDOM. Our results indicate...... that the formation of a fluorescent RDOM component depends on the bioavailability of the substrate: the less labile, the larger the production of fluorescent RDOM relative to organic carbon remineralized. The anticipated increase in microbial carbon demand due to ocean warming can potentially forcemicrobes...

  9. Dissolved organic matter (DOM) in microalgal photobioreactors: a potential loss in solar energy conversion?

    Science.gov (United States)

    Hulatt, Chris J; Thomas, David N

    2010-11-01

    Microalgae are considered to be a potential alternative to terrestrial crops for bio-energy production due to their relatively high productivity per unit area of land. In this work we examined the amount of dissolved organic matter exuded by algal cells cultured in photobioreactors, to examine whether a significant fraction of the photoassimilated biomass could potentially be lost from the harvestable biomass. We found that the mean maximum amount of dissolved organic carbon (DOC) released measured 6.4% and 17.3% of the total organic carbon in cultures of Chlorellavulgaris and Dunaliella tertiolecta, respectively. This DOM in turn supported a significant growth of bacterial biomass, representing a further loss of the algal assimilated carbon. The release of these levels of DOC indicates that a significant fraction of the photosynthetically fixed organic matter could be lost into the surrounding water, suggesting that the actual biomass yield per hectare for industrial purposes could be somewhat less than expected. A simple and inexpensive optical technique, based on chromophoric dissolved organic matter (CDOM) measurements, to monitor such losses in commercial PBRs is discussed.

  10. Reclamation of cadmium-contaminated soil using dissolved organic matter solution originating from wine-processing waste sludge

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Cheng-Chung, E-mail: ccliu@niu.edu.tw [Department of Environmental Engineering, National Ilan University, Ilan, 260, Taiwan (China); Chen, Guan-Bu [Department of Environmental Engineering, National Ilan University, Ilan, 260, Taiwan (China)

    2013-01-15

    Highlights: ► Increases in acidity, washing frequency, and operational temperature enhance the Cd removal. ► Approximately 80% of Cd can be removed from the soil by dissolved organic matter (DOM) washing. ► The DOM washing can moderate the loss of soil fertility. ► The DOM washing will have a great improvement if we employ NaOH, KOH, Ca(OH){sub 2}, and Mg(OH){sub 2} to prepare the DOM solution together. -- Abstract: Soil washing using an acid solution is a common practice for removing heavy metals from contaminated soil in Taiwan. However, serious loss of nutrients from soil is a major drawback of the washing. Distillery sludge can be used to prepare a dissolved organic matter (DOM) solution by extracting its organic constituents with alkaline solutions. This study employed DOM solutions to remediate Cd-contaminated soil (with concentrations up to 21.5 mg kg{sup −1}) and determine the factors affecting removal of Cd, such as pH, initial concentration of DOM solution, temperature, and washing frequency. When washing with pH 3.0 and 1250 mg L{sup −1} DOM solution, about 80% and 81% of Cd were removed from the topsoil at 27 °C and subsoil at 40 °C, respectively. To summarize the changes in fertility during DOM washing with various pH solutions: the increase in organic matter content ranged from 7.7% to 23.7%; cation exchange capacity (CEC) ranged from 4.6% to 13.9%; available ammonium (N-NH{sub 4}) content ranged from 39.4% to 2175%; and available phosphorus content ranged from 34.5% to 182%. Exchangeable K, Ca, and Mg remained in the topsoil after DOM washing, with concentrations of 1.1, 2.4, and 1.5 times higher than those treated with HCl solution at the same pH, respectively.

  11. 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.

  12. [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.

  13. Measurement of dissolved reactive phosphorus in water with polyquaternary ammonium salt as a binding agent in diffusive gradients in thin-films technique.

    Science.gov (United States)

    Chen, Hong; Zhang, Meng-Han; Gu, Jia-Li; Zhao, Gang; Zhang, Yu; Li, Jian-Rong

    2014-12-17

    Diffusive gradients in thin-films (DGT) sampler with a polyquaternary ammonium salt (PQAS) aqueous solution as a binding phase and a dialysis membrane as a diffusive phase (PQAS DGT) was developed for the measurement of dissolved reactive phosphorus (DRP) in water. The performance of PQAS DGT was not dependent upon pH 3-10 and ionic strength from 1 × 10(-4) to 1 mol L(-1). The effective binding capacity of PQAS DGT containing 2.0 mL of 0.050 mol L(-1) PQAS solution was estimated as 9.9 μg cm(-2). The measurement of DRP in a synthetic solution by PQAS DGT over a 48 h deployment period demonstrated high consistency with the concentration of DRP in the synthetic solution measured directly by the ammonium molybdate spectrophotometric method. Field deployments of PQAS DGT samplers allowed for accurate measurement of the DRP concentration in situ. The advantages of PQAS DGT include no requirement of the elution steps and direct concentration measurements of the binding phase.

  14. PHOTOREACTIVITY OF CHROMOPHORIC DISSOLVED ORGANIC MATTER (CDOM) DERIVED FROM DECOMPOSITION OF VARIOUS VASCULAR PLANT AND ALGAL SOURCES

    Science.gov (United States)

    Chromophoric dissolved organic matter (CDOM) in aquatic environments is derived from the microbial decomposition of terrestrial and microbial organic matter. Here we present results of studies of the spectral properties and photoreactivity of the CDOM derived from several organi...

  15. Dissolved organic carbon and nitrogen release from boreal Holocene permafrost and seasonally frozen soils of Alaska

    Science.gov (United States)

    Wickland, Kimberly P.; Waldrop, Mark P.; Aiken, George R.; Koch, Joshua C.; Torre Jorgenson, M.; Striegl, Robert G.

    2018-06-01

    Permafrost (perennially frozen) soils store vast amounts of organic carbon (C) and nitrogen (N) that are vulnerable to mobilization as dissolved organic carbon (DOC) and dissolved organic and inorganic nitrogen (DON, DIN) upon thaw. Such releases will affect the biogeochemistry of permafrost regions, yet little is known about the chemical composition and source variability of active-layer (seasonally frozen) and permafrost soil DOC, DON and DIN. We quantified DOC, total dissolved N (TDN), DON, and DIN leachate yields from deep active-layer and near-surface boreal Holocene permafrost soils in interior Alaska varying in soil C and N content and radiocarbon age to determine potential release upon thaw. Soil cores were collected at three sites distributed across the Alaska boreal region in late winter, cut in 15 cm thick sections, and deep active-layer and shallow permafrost sections were thawed and leached. Leachates were analyzed for DOC, TDN, nitrate (NO3 ‑), and ammonium (NH4 +) concentrations, dissolved organic matter optical properties, and DOC biodegradability. Soils were analyzed for C, N, and radiocarbon (14C) content. Soil DOC, TDN, DON, and DIN yields increased linearly with soil C and N content, and decreased with increasing radiocarbon age. These relationships were significantly different for active-layer and permafrost soils such that for a given soil C or N content, or radiocarbon age, permafrost soils released more DOC and TDN (mostly as DON) per gram soil than active-layer soils. Permafrost soil DOC biodegradability was significantly correlated with soil Δ14C and DOM optical properties. Our results demonstrate that near-surface Holocene permafrost soils preserve greater relative potential DOC and TDN yields than overlying seasonally frozen soils that are exposed to annual leaching and decomposition. While many factors control the fate of DOC and TDN, the greater relative yields from newly thawed Holocene permafrost soils will have the largest

  16. 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.

  17. Removal of dissolved organic carbon in pilot wetlands of subsuperficial and superficial flows

    Directory of Open Access Journals (Sweden)

    Ruth M. Agudelo C

    2010-04-01

    Full Text Available Objective: to compare removal of dissolved organic carbon (d o c obtained with pilot wetlands of subsuperficial flow (p h s s and superficial flow (p h s, with Phragmites australis as treatment alternatives for domestic residual waters of small communities and rural areas. Methodology: an exploratory and experimental study was carried out adding 100,12 mg/L of dissolved organic carbon to synthetic water contaminated with Chlorpyrifos in order to feed the wetlands. A total amount of 20 samples were done, 16 of them in four experiments and the other ones in the intervals with no use of pesticides. Samples were taken on days 1, 4, 8, and 11 in the six wetlands, three of them subsuperficial, and three of them superficial. The main variable answer was dissolved organic carbon, measured in the organic carbon analyzer. Results: a high efficiency in the removal of d o c was obtained with the two types of wetlands: 92,3% with subsuperficial flow and 95,6% with superficial flow. Such a high removal was due to the interaction between plants, gravel and microorganisms. Conclusion: although in both types of wetlands the removal was high and similar, it is recommended to use those of subsuperficial flow because in the superficial ones algae and gelatinous bio-films are developed, which becomes favorable to the development of important epidemiologic vectors in terms of public health.

  18. Cellulase activity and dissolved organic carbon release from lignocellulose macrophyte-derived in four trophic conditions

    Directory of Open Access Journals (Sweden)

    Flávia Bottino

    2016-06-01

    Full Text Available Abstract Considering the importance of lignocellulose macrophyte-derived for the energy flux in aquatic ecosystems and the nutrient concentrations as a function of force which influences the decomposition process, this study aims to relate the enzymatic activity and lignocellulose hydrolysis in different trophic statuses. Water samples and two macrophyte species were collected from the littoral zone of a subtropical Brazilian Reservoir. A lignocellulosic matrix was obtained using aqueous extraction of dried plant material (≈40 °C. Incubations for decomposition of the lignocellulosic matrix were prepared using lignocelluloses, inoculums and filtered water simulating different trophic statuses with the same N:P ratio. The particulate organic carbon and dissolved organic carbon (POC and DOC, respectively were quantified, the cellulase enzymatic activity was measured by releasing reducing sugars and immobilized carbon was analyzed by filtration. During the cellulose degradation indicated by the cellulase activity, the dissolved organic carbon daily rate and enzyme activity increased. It was related to a fast hydrolysable fraction of cellulose that contributed to short-term carbon immobilization (ca. 10 days. After approximately 20 days, the dissolved organic carbon and enzyme activity were inversely correlated suggesting that the respiration of microorganisms was responsible for carbon mineralization. Cellulose was an important resource in low nutrient conditions (oligotrophic. However, the detritus quality played a major role in the lignocelluloses degradation (i.e., enzyme activity and carbon release.

  19. Effects of dissolved organic matter leaching from macrophyte litter on black water events in shallow lakes.

    Science.gov (United States)

    He, Yuhong; Song, Na; Jiang, He-Long

    2018-04-01

    In recent years, the black water phenomenon has become an environmental event in eutrophic shallow lakes in China, leading to deterioration of lake ecosystems and potable water crises. Decomposition of macrophyte debris has been verified as a key inducement for black water events. In this study, the effects of the decomposition of dissolved organic matter (Kottelat et al., WASP 187:343-351, 2008) derived from macrophyte leachate on the occurrence of black water events are investigated to clarify the detailed mechanisms involved. Results show that dissolved organic matter (DOM) is composed of a trace of chromophoric DOM and mostly non-chromophoric dissolved organic matter (CDOM). DOM decomposition is accompanied by varied concentration of CDOM components, generation of organic particles, and increased microbial concentrations. These processes increase water chroma only during initial 48 h, so the intensified water color cannot be maintained by DOM decomposition alone. During DOM decomposition, microorganisms first consume non-CDOM, increasing the relative CDOM concentration and turning the water color to black (or brown). Simultaneously, tryptophan and aromatic proteins, which are major ingredients of CDOM, enhance UV light absorption, further aggravating the macroscopic phenomenon of black color. Our results show that DOM leached from decayed macrophytes promotes or even triggers the occurrence of black water events and should be taken more seriously in the future.

  20. Cellulase activity and dissolved organic carbon release from lignocellulose macrophyte-derived in four trophic conditions.

    Science.gov (United States)

    Bottino, Flávia; Cunha-Santino, Marcela Bianchessi; Bianchini, Irineu

    2016-01-01

    Considering the importance of lignocellulose macrophyte-derived for the energy flux in aquatic ecosystems and the nutrient concentrations as a function of force which influences the decomposition process, this study aims to relate the enzymatic activity and lignocellulose hydrolysis in different trophic statuses. Water samples and two macrophyte species were collected from the littoral zone of a subtropical Brazilian Reservoir. A lignocellulosic matrix was obtained using aqueous extraction of dried plant material (≈40°C). Incubations for decomposition of the lignocellulosic matrix were prepared using lignocelluloses, inoculums and filtered water simulating different trophic statuses with the same N:P ratio. The particulate organic carbon and dissolved organic carbon (POC and DOC, respectively) were quantified, the cellulase enzymatic activity was measured by releasing reducing sugars and immobilized carbon was analyzed by filtration. During the cellulose degradation indicated by the cellulase activity, the dissolved organic carbon daily rate and enzyme activity increased. It was related to a fast hydrolysable fraction of cellulose that contributed to short-term carbon immobilization (ca. 10 days). After approximately 20 days, the dissolved organic carbon and enzyme activity were inversely correlated suggesting that the respiration of microorganisms was responsible for carbon mineralization. Cellulose was an important resource in low nutrient conditions (oligotrophic). However, the detritus quality played a major role in the lignocelluloses degradation (i.e., enzyme activity) and carbon release. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  1. Existing Versus Added Soil Organic Matter in Relation to Phosphorus Availability on Lateritic Soils

    Directory of Open Access Journals (Sweden)

    Fadly Hairannoor Yusran

    2008-01-01

    Full Text Available Lateritic soils (Ultisols and Oxisols are commonly characterised by high phosphate sorbing capacity due to the type of clay and present high content of aluminium (Al and iron (Fe oxides. Addition of fresh organic matter (OM may contribute to management of these soils by releasing more bicarbonate-extractable phosphorus (BP through organic phosphorus (OP transformation, or by the soluble component of OM additions desorbing phosphate by ligand exchange. It is not known, however, whether BP results solely from addition of new OM (by either mineralisation or desorption or from transformation of inherent or pre-existing in soil. We considered that removing the existing soil OM and replacing it with an equivalent amount of new OM may help to resolve this issue, especially with respect to P transformation after OM additions. Three lateritic soils of Western Australia (including a deep regolith material with very low inherent soil OM (SOM were used, and sub-samples of the three soils were combusted (450° C to obtain soils effectively free from existing OM. A further sub-sample of the soils was not combusted. Both soil groups, receiving the same amount of organic carbon (OC, from 80 ton ha-1 biomass + soil OM or biomass equal to soil OM from peat, wheat straw (Triticum aestivum L. and lucerne hay (Medicago sativa L., were incubated for nine months. Soil bicarbonate-extractable P as well as non-extractable P (NP, measured as Total-P (TP-BP increased due to new OM application in the order lucerne hay>peat>wheat straw. The correlation between BP with soil organic carbon (SOC became more positive over time. Microbial biomass phosphorus (MBP was not well correlated with the increase of NP content and phosphatase was not related to the increase in BP. Overall, freshly applied (new OM not only contributed to the increased level of P compared with the existing OM treatment.

  2. Limited Dissolved Phosphorus Runoff Losses from Layered Double Hydroxide and Struvite Fertilizers in a Rainfall Simulation Study.

    Science.gov (United States)

    Everaert, Maarten; da Silva, Rodrigo C; Degryse, Fien; McLaughlin, Mike J; Smolders, Erik

    2018-03-01

    The enrichment of P in surface waters has been linked to P runoff from agricultural fields amended with fertilizers. Novel slow-release mineral fertilizers, such as struvite and P-exchanged layered double hydroxides (LDHs), have received increasing attention for P recycling from waste streams, and these fertilizers may potentially reduce the risk of runoff losses. Here, a rainfall simulation experiment was performed to evaluate P runoff associated with the application of recycled slow-release fertilizers relative to that of a soluble fertilizer. Monoammonium phosphate (MAP), struvite, and LDH granular fertilizers were broadcasted at equal total P doses on soil packed in trays (5% slope) and covered with perennial ryegrass ( L.). Four rainfall simulation events of 30 min were performed at 1, 5, 15, and 30 d after the fertilizer application. Runoff water from the trays was collected, filtered, and analyzed for dissolved P. For the MAP treatment, P runoff losses were high in the first two rain events and leveled off in later rain events. In total, 42% of the applied P in the MAP treatment was lost due to runoff. In the slow-release fertilizer treatments, P runoff losses were limited to 1.9 (struvite) and 2.4% (LDH) of the applied doses and were more similar over the different rain events. The use of these novel P fertilizer forms could be beneficial in areas with a high risk of surface water eutrophication and a history of intensive fertilization. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  3. Organic Acids Regulation of Chemical-Microbial Phosphorus Transformations in Soils.

    Science.gov (United States)

    Menezes-Blackburn, Daniel; Paredes, Cecilia; Zhang, Hao; Giles, Courtney D; Darch, Tegan; Stutter, Marc; George, Timothy S; Shand, Charles; Lumsdon, David; Cooper, Patricia; Wendler, Renate; Brown, Lawrie; Blackwell, Martin; Wearing, Catherine; Haygarth, Philip M

    2016-11-01

    We have used an integrated approach to study the mobility of inorganic phosphorus (P) from soil solid phase as well as the microbial biomass P and respiration at increasing doses of citric and oxalic acid in two different soils with contrasting agronomic P status. Citric or oxalic acids significantly increased soil solution P concentrations for doses over 2 mmol kg -1 . However, low organic acid doses (<2 mmol kg -1 ) were associated with a steep increase in microbial biomass P, which was not seen for higher doses. In both soils, treatment with the tribasic citric acid led to a greater increase in soil solution P than the dibasic oxalic acid, likely due to the rapid degrading of oxalic acids in soils. After equilibration of soils with citric or oxalic acids, the adsorbed-to-solution distribution coefficient (K d ) and desorption rate constants (k -1 ) decreased whereas an increase in the response time of solution P equilibration (T c ) was observed. The extent of this effect was shown to be both soil and organic acid specific. Our results illustrate the critical thresholds of organic acid concentration necessary to mobilize sorbed and precipitated P, bringing new insight on how the exudation of organic acids regulate chemical-microbial soil phosphorus transformations.

  4. 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...

  5. 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.

  6. [Linking optical properties of dissolved organic matter with NDMA formation potential in the Huangpu River].

    Science.gov (United States)

    Dong, Qian-Qian; Zhang, Ai; Li, Yong-Mei; Chen, Ling; Huang, Qing-Hui

    2014-03-01

    Surface water samples from the Huangpu River were filtered to measure the UV absorption and fluorescence spectrum. Dissolved organic carbon (DOC), N-nitrosodimethylamine (NDMA), and its formation potential (NDMA-FP) were also analyzed to explore relationships between the properties of dissolved organic matter (DOM) and the formation potential of disinfection byproducts-NDMA in the Huangpu River. The study found that: NDMA-FP concentration increased with the increasing of DOC concentration (r = 0.487, P NDMA-FP concentration had positive relationships with the fluorescence intensity of protein-like substances such as low-molecular-weight (LMW) tyrosine-like and tryptophan-like substances (r = 0.421, P NDMA formation potential increases with the increasing DOM content in the Huangpu River, which is significantly related with the protein-like substances, but decreases with the increasing aromaticity and humification of DOM.

  7. Tracing global biogeochemical cycles and meridional overturning circulation using chromophoric dissolved organic matter

    Science.gov (United States)

    Nelson, Norman B.; Siegel, David A.; Carlson, Craig A.; Swan, Chantal M.

    2010-02-01

    Basin-scale distributions of light absorption by chromophoric dissolved organic matter (CDOM) are positively correlated (R2 > 0.8) with apparent oxygen utilization (AOU) within the top kilometer of the Pacific and Indian Oceans. However, a much weaker correspondence is found for the Atlantic (R2 organic matter from sinking particles. The observed meridional-depth sections of CDOM result from a balance between biogeochemical processes (autochthonous production and solar bleaching) and the meridional overturning circulation. Rapid mixing in the Atlantic dilutes CDOM in the interior and implies that the time scale for CDOM accumulation is greater than ˜50 years. CDOM emerges as a unique tracer for diagnosing changes in biogeochemistry and the overturning circulation, similar to dissolved oxygen, with the additional feature that it can be quantified from satellite observation.

  8. Pan-Arctic Distribution of Bioavailable Dissolved Organic Matter and Linkages With Productivity in Ocean Margins

    Science.gov (United States)

    Shen, Yuan; Benner, Ronald; Kaiser, Karl; Fichot, Cédric G.; Whitledge, Terry E.

    2018-02-01

    Rapid environmental changes in the Arctic Ocean affect plankton productivity and the bioavailability of dissolved organic matter (DOM) that supports microbial food webs. We report concentrations of dissolved organic carbon (DOC) and yields of amino acids (indicators of labile DOM) in surface waters across major Arctic margins. Concentrations of DOC and bioavailability of DOM showed large pan-Arctic variability that corresponded to varying hydrological conditions and ecosystem productivity, respectively. Widespread hot spots of labile DOM were observed over productive inflow shelves (Chukchi and Barents Seas), in contrast to oligotrophic interior margins (Kara, Laptev, East Siberian, and Beaufort Seas). Amino acid yields in outflow gateways (Canadian Archipelago and Baffin Bay) indicated the prevalence of semilabile DOM in sea ice covered regions and sporadic production of labile DOM in ice-free waters. Comparing these observations with surface circulation patterns indicated varying shelf subsidies of bioavailable DOM to Arctic deep basins.

  9. Amount, composition and seasonality of dissolved organic carbon and nitrogen export from agriculture in contrasting climates

    DEFF Research Database (Denmark)

    Graeber, Daniel; Meerhof, Mariana; Zwirnmann, Elke

    2014-01-01

    Agricultural catchments are potentially important but often neglected sources of dissolved organic matter (DOM), of which a large part is dissolved organic carbon (DOC) and nitrogen (DON). DOC is an important source of aquatic microbial respiration and DON may be an important source of nitrogen...... to aquatic ecosystems. However, there is still a lack of comprehensive studies on the amount, composition and seasonality of DOM export from agricultural catchments in different climates. The aim of our study was to assess the amount, composition and seasonality of DOM in a total of four streams in the wet......-temperate and subtropical climate of Denmark and Uruguay, respectively. In each climate, we investigated one stream with extensive agriculture (mostly pasture) and one stream with intensive agriculture (mostly intensively used arable land) in the catchment. We sampled each stream taking grab samples fortnightly for two...

  10. Seasonal dynamics and conservative mixing of dissolved organic matter in the temperate eutrophic estuary Horsens Fjord

    DEFF Research Database (Denmark)

    Markager, Stiig; Stedmon, Colin; Søndergaard, Morten

    2011-01-01

    of different DOM parameters i.e. dissolved organic carbon (DOC), nitrogen (DON), and phosphorous (DOP), light absorption and eight fluorescence components, were analysed relative to conservative mixing. Many of the parameters did not behave conservatively. For DON, DOP and absorption, more than 65......This study presents the results of a year-long study investigating the characteristics of dissolved organic matter (DOM) in the Danish estuary, Horsens Fjord. The estuary is shallow with a mean depth of 2.9 m and receives high loadings of inorganic nutrients from its catchment. The behaviour......% of the freshwater concentration was removed initially at salinities below 12. At higher salinities two general patterns were identified. Concentrations of DON, DOP and four humic fluorescent fractions were not, or only weakly, related to salinity, showing that other processes than mixing were involved. Other...

  11. δ15N, δ13C and radiocarbon in dissolved organic carbon as indicators of environmental change

    International Nuclear Information System (INIS)

    Geyer, S.; Kalbitz, K.

    2002-01-01

    Decomposition, humification, and stabilization of soil organic matter are closely related to the dynamics of dissolved organic matter. Enhanced peat decomposition results in increasing aromatic structures and polycondensation of dissolved organic molecules. Although recent studies support the concept that DOM can serve as an indicator for processes driven by changing environmental processes in soils affecting the C and N cycle (like decomposition and humification) and also permit insight in former conditions some 1000 years ago, it is unknown whether dissolved organic carbon (DOC) and nitrogen (DON) have an equal response to these processes. (author)

  12. Phosphorus release from phosphate rock and iron phosphate by low-molecular-weight organic acids.

    Science.gov (United States)

    Xu, Ren-kou; Zhu, Yong-guan; Chittleborough, David

    2004-01-01

    Low-molecular-weight(LMW) organic acids widely exist in soils, particularly in the rhizosphere. A series of batch experiments were carried out to investigate the phosphorus release from rock phosphate and iron phosphate by low-molecular-weight organic acids. Results showed that citric acid had the highest capacity to solubilize P from both rock and iron phosphate. P solubilization from rock phosphate and iron phosphate resulted in net proton consumption. P release from rock phosphate was positively correlated with the pKa values. P release from iron phosphate was positively correlated with Fe-organic acid stability constants except for aromatic acids, but was notcorrelated with pKa. Increase in the concentrations of organic acids enhanced P solubilization from both rock and iron phosphate almost linearly. Addition of phenolic compounds further increased the P release from iron phosphate. Initial solution pH had much more substantial effect on P release from rock phosphate than from iron phosphate.

  13. Unraveling the size-dependent optical properties of dissolved organic matter

    DEFF Research Database (Denmark)

    Wünsch, Urban; Stedmon, Colin; Tranvik, Lars

    2018-01-01

    The size-dependent optical properties of dissolved organic matter (DOM) from four Swedish lakes were investigated using High Performance Size Exclusion Chromatography (HPSEC) in conjunction with online characterization of absorbance (240–600 nm) and fluorescence (excitation: 275 nm, emission: 300....... This study demonstrates the potential for HPSEC and novel mathematical approaches to provide unprecedented insights into the relationship between optical and chemical properties of DOM in aquatic systems...

  14. Input of particulate organic and dissolved inorganic carbon from the Amazon to the Atlantic Ocean

    OpenAIRE

    Druffel, E. R. M; Bauer, J. E; Griffin, S.

    2005-01-01

    We report concentrations and isotope measurements (radiocarbon and stable carbon) of dissolved inorganic carbon (DIC) and suspended particulate organic carbon (POC) in waters collected from the mouth of the Amazon River and the North Brazil Current. Samples were collected in November 1991, when the Amazon hydrograph was at its annual minimum and the North Brazil Current had retroflected into the equatorial North Atlantic. The DIC Δ14C results revealed postbomb carbon in river and ocean waters...

  15. The effect of increased loads of dissolved organic matter on estuarine microbial community composition and function

    DEFF Research Database (Denmark)

    Traving, Sachia J.; Rowe, Owen; Jakobsen, Nina M.

    2017-01-01

    Increased river loads are projected as one of the major consequences of climate change in the northern hemisphere, leading to elevated inputs of riverine dissolved organic matter (DOM) and inorganic nutrients to coastal ecosystems. The objective of this study was to investigate the effects of ele...... supply to the Baltic Sea will be efficiently mineralized by microbes. This will have consequences for bacterioplankton and phytoplankton community composition and function, and significantly affect nutrient biogeochemistry....

  16. COLORED DISSOLVED ORGANIC MATTER (CDOM) CHARACTERIZATION BY ABSORPTION AND FLUORESCENCE SPECTRA

    OpenAIRE

    Goncalves Araujo, Rafael; Ramirez-Perez, Marta; Kraberg, Alexandra; Piera, Jaume; Bracher, Astrid

    2014-01-01

    Colored dissolved organic matter (CDOM) absorption and fluorescence spectra were analyzed from samples collected in the Lena River Delta region (Siberia, Russia; summer-2013) and in the Alfacs Bay (Ebro River Delta, Spain; summer-2013/winter-2014) in order to use optical measurements to infer loading and origin of CDOM. Absorbance spectra and Excitation-Emission matrices (EEMs) were obtained with a HORIBA Aqualog® spectrofluorometer. CDOM absorption at 443nm (a443) and terrestrial absorption ...

  17. Impact of Wetland Decline on Decreasing Dissolved Organic Carbon Concentrations along the Mississippi River Continuum

    OpenAIRE

    Duan, Shuiwang; He, Yuxiang; Kaushal, Sujay S.; Bianchi, Thomas S.; Ward, Nicholas D.; Guo, Laodong

    2017-01-01

    Prior to discharging to the ocean, large rivers constantly receive inputs of dissolved organic carbon (DOC) from tributaries or fringing floodplains and lose DOC via continuous in situ processing along distances that span thousands of kilometers. Current concepts predicting longitudinal changes in DOC mainly focus on in situ processing or exchange with fringing floodplain wetlands, while effects of heterogeneous watershed characteristics are generally ignored. We analyzed results from a 17-ye...

  18. 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

  19. Microbial Community Response to Terrestrially Derived Dissolved Organic Matter in the Coastal Arctic

    Directory of Open Access Journals (Sweden)

    Rachel E. Sipler

    2017-06-01

    Full Text Available Warming at nearly twice the global rate, higher than average air temperatures are the new ‘normal’ for Arctic ecosystems. This rise in temperature has triggered hydrological and geochemical changes that increasingly release carbon-rich water into the coastal ocean via increased riverine discharge, coastal erosion, and the thawing of the semi-permanent permafrost ubiquitous in the region. To determine the biogeochemical impacts of terrestrially derived dissolved organic matter (tDOM on marine ecosystems we compared the nutrient stocks and bacterial communities present under ice-covered and ice-free conditions, assessed the lability of Arctic tDOM to coastal microbial communities from the Chukchi Sea, and identified bacterial taxa that respond to rapid increases in tDOM. Once thought to be predominantly refractory, we found that ∼7% of dissolved organic carbon and ∼38% of dissolved organic nitrogen from tDOM was bioavailable to receiving marine microbial communities on short 4 – 6 day time scales. The addition of tDOM shifted bacterial community structure toward more copiotrophic taxa and away from more oligotrophic taxa. Although no single order was found to respond universally (positively or negatively to the tDOM addition, this study identified 20 indicator species as possible sentinels for increased tDOM. These data suggest the true ecological impact of tDOM will be widespread across many bacterial taxa and that shifts in coastal microbial community composition should be anticipated.

  20. Distributions and characteristics of dissolved organic matter in temperate coastal waters (Southern North Sea)

    Science.gov (United States)

    Lübben, Andrea; Dellwig, Olaf; Koch, Sandra; Beck, Melanie; Badewien, Thomas H.; Fischer, Sibylle; Reuter, Rainer

    2009-04-01

    The spatial and temporal distributions of chromophoric dissolved organic matter (CDOM) and dissolved organic carbon (DOC) was studied in the East-Frisian Wadden Sea (Southern North Sea) during several cruises between 2002 and 2005. The spatial distribution of CDOM in the German Bight shows a strong gradient towards the coast. Tidal and seasonal variations of dissolved organic matter (DOM) identify freshwater discharge via flood-gates at the coastline and pore water efflux from tidal flat sediments as the most important CDOM sources within the backbarrier area of the Island of Spiekeroog. However, the amount and pattern of CDOM and DOC is strongly affected by various parameters, e.g. changes in the amount of terrestrial run-off, precipitation, evaporation, biological activity and photooxidation. A decoupling of CDOM and DOC, especially during periods of pronounced biological activity (algae blooms and microbial activity), is observed in spring and especially in summer. Mixing of the endmembers freshwater, pore water, and open sea water results in the formation of a coastal transition zone. Whilst an almost conservative behaviour during mixing is observed in winter, summer data point towards non-conservative mixing.

  1. Uptake of dissolved organic carbon and trace elements by zebra mussels

    Science.gov (United States)

    Roditi, Hudson A.; Fisher, Nicholas S.; Sañudo-Wilhelmy, Sergio A.

    2000-09-01

    Zebra mussels (Dreissena polymorpha) are widespread and abundant in major freshwater ecosystems in North America, even though the phytoplankton food resources in some of these systems seem to be too low to sustain them. Because phytoplankton biomass is greatly depleted in ecosystems with large D. polymorpha populations and bacteria do not seem to be an important food source for this species, exploitation of alternative carbon sources may explain the unexpected success of D. polymorpha in such environments. Here we examine the possibility that absorption of dissolved organic carbon (DOC) from water could provide a nutritional supplement to zebra mussels. We find that mussels absorb 14C-labelled DOC produced by cultured diatoms with an efficiency of 0.23%; this indicates that DOC in natural waters could contribute up to 50% of the carbon demand of zebra mussels. We also find that zebra mussels absorb some dissolved metals that have been complexed by the DOM; although absorption of dissolved selenium was unaffected by DOC, absorption of dissolved cadmium, silver and mercury by the mussels increased 32-, 8.7- and 3.6-fold, respectively, in the presence of high-molecular-weight DOC.

  2. An Analysis of Terrestrial and Aquatic Environmental Controls of Riverine Dissolved Organic Carbon in the Conterminous United States

    Directory of Open Access Journals (Sweden)

    Qichun Yang

    2017-05-01

    Full Text Available Analyses of environmental controls on riverine carbon fluxes are critical for improved understanding of the mechanisms regulating carbon cycling along the terrestrial-aquatic continuum. Here, we compile and analyze riverine dissolved organic carbon (DOC concentration data from 1402 United States Geological Survey (USGS gauge stations to examine the spatial variability and environmental controls of DOC concentrations in the United States (U.S. surface waters. DOC concentrations exhibit high spatial variability in the U.S., with an average of 6.42 ± 6.47 mg C/L (Mean ± Standard Deviation. High DOC concentrations occur in the Upper Mississippi River basin and the southeastern U.S., while low concentrations are mainly distributed in the western U.S. Soil properties such as soil organic matter, soil water content, and soil sand content mainly show positive correlations with DOC concentrations; forest and shrub land have positive correlations with DOC concentrations, but urban area and cropland demonstrate negative impacts; and total instream phosphorus and dam density correlate positively with DOC concentrations. Notably, the relative importance of these environmental controls varies substantially across major U.S. water resource regions. In addition, DOC concentrations and environmental controls also show significant variability from small streams to large rivers. In sum, our results reveal that general multi-linear regression of twenty environmental factors can partially explain (56% the DOC concentration variability. This study also highlights the complexity of the interactions among these environmental factors in determining DOC concentrations, thus calls for processes-based, non-linear methodologies to constrain uncertainties in riverine DOC cycling.

  3. Prediction of extraction ability during metal complexing with organic phosphorus extractants

    International Nuclear Information System (INIS)

    Rozen, A.M.; Krupnov, B.V.

    1995-01-01

    Quantum-chemical calculations of thermodynamic parameters of complexing of neutral organic phosphorus compounds (phosphates, phosphine oxides and diphosphine dioxides with different substituents) with seven acceptors of different strength have been made. It is shown that in a wide range of the complexes strength change the entropy contribution of the Gibbs energy of complexing depends but slightly both on the ligand basicity and on the acceptor nature. It is ascertained that this reaction series is isoentropic for any Lewis acid. Practicability of the previously used correlation between extractability and complexing enthalpy has been proved. 17 refs., 1 fig., 1 tab

  4. Experiments with organic phosphorus compounds for the treatment of cooling water

    International Nuclear Information System (INIS)

    Resch, G.; Burgmann, F.

    1975-01-01

    The stabilizing effect of organic phosphorus compounds has been investigated. The results obtained, however, do not enable statements as to the behaviour of the precipitating calcium carbonate beyond the stabilizing limit. It is possible that in the presence of hardness stabilizers, precipitating calcium carbonate, due to its specific solid strucutre, does not form hard, adhesive deposits, but soft, loose ones with coatings removable by continuous pipe cleaning systems. The stabilizing effect of hardness stabilizers is not the only criterion responsible for its value. The type and behaviour of the precipitated calcium carbonate must be considered. (HK/LH) [de

  5. 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

  6. Dynamic behaviour of river colloidal and dissolved organic matter through cross-flow ultrafiltration system.

    Science.gov (United States)

    Wilding, Andrew; Liu, Ruixia; Zhou, John L

    2005-07-01

    Through cross-flow filtration (CFF) with a 1-kDa regenerated cellulose Pellicon 2 module, the ultrafiltration characteristics of river organic matter from Longford Stream, UK, were investigated. The concentration of organic carbon (OC) in the retentate in the Longford Stream samples increased substantially with the concentration factor (cf), reaching approximately 40 mg/L at cf 15. The results of dissolved organic carbon (DOC) and colloidal organic carbon (COC) analysis, tracking the isolation of colloids from river waters, show that 2 mg/L of COC was present in those samples and good OC mass balance (77-101%) was achieved. Fluorescence measurements were carried out for the investigation of retentate and permeate behaviour of coloured dissolved organic materials (CDOM). The concentrations of CDOM in both the retentate and permeate increased with increasing cf, although CDOM were significantly more concentrated in the retentate. The permeation model expressing the correlation between log[CDOM] in the permeate and logcf was able to describe the permeation behaviour of CDOM in the river water with regression coefficients (r(2)) of 0.94 and 0.98. Dry weight analysis indicated that the levels of organic colloidal particles were from 49 to 71%, and between 29 and 51% of colloidal particles present were inorganic. COC as a percentage of DOC was found to be 10-16% for Longford Stream samples.

  7. 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.

  8. Using fluorescent dissolved organic matter to trace and distinguish the origin of Arctic surface waters

    DEFF Research Database (Denmark)

    Goncalves-Araujo, Rafael; Granskog, Mats A.; Bracher, Astrid

    2016-01-01

    were performed in the Fram and Davis Straits, and on the east Greenland Shelf (EGS), in late summer 2012/2013. Meteoric (f(mw)), sea-ice melt, Atlantic and Pacific water fractions were determined and the fluorescence properties of dissolved organic matter (FDOM) were characterized. In Fram Strait...... and EGS, a robust correlation between visible wavelength fluorescence and f(mw) was apparent, suggesting it as a reliable tracer of polar waters. However, a pattern was observed which linked the organic matter characteristics to the origin of polar waters. At depth in Davis Strait, visible wavelength FDOM...

  9. Dynamics of Dissolved Organic Matter and Microbes in Seawater through Sub-Micron Particle Size Analyses

    Digital Repository Service at National Institute of Oceanography (India)

    Goes, J.I.; Balch, W.M.; Vaughn, J.M.; Gomes, H.R.

    -78. Hansell, D.A. and Carlson, C.A., (1998) Deep-ocean gradients in the concentration of dissolved organic carbon. Nature, 395, 263-266. J. E. (1977) Characterization of suspended matter in the Gulf of Mexico ? II. Particles size analysis of suspended matter.... and Morris, I. (1980) Extracellular release of carbon by marine phytoplankton: a physiological approach. Limnol. Oceanogr., 25, 262-279. Maurer, L. G. (1976) Organic polymers in seawater: changes with depth in the Gulf of Mexico. Deep-Sea Res., 23, 1059...

  10. Dissolved natural organic matter (NOM) impacts photosynthetic oxygen production and electron transport in coontail Ceratophyllum demersum

    International Nuclear Information System (INIS)

    Pflugmacher, S.; Pietsch, C.; Rieger, W.; Steinberg, C.E.W.

    2006-01-01

    Dissolved natural organic matter (NOM) is dead organic matter exceeding, in freshwater systems, the concentration of organic carbon in all living organisms by far. 80-90% (w/w) of the NOM is made up of humic substances (HS). Although NOM possesses several functional groups, a potential effect on aquatic organisms has not been studied. In this study, direct effects of NOM from various origins on physiological and biochemical functions in the aquatic plant Ceratophyllum demersum are presented. Environmentally relevant concentrations of NOM cause inhibitory effects on the photosynthetic oxygen production of C. demersum. Various NOM sources and the synthetic humic substance HS1500 inhibit the photosynthetic oxygen production of the plant as observed with 1-amino-anthraquinone, a known inhibitor of plant photosynthesis. 1-Aminoanthraquinone may serve as an analogue for the quinoid structures in NOM and HS. Most likely, the effects of NOM may be related to quinoid structures and work downstream of photosynthesis at photosystem (PS) II

  11. Mobility of the dissolved organic matter through intact boom clay cores

    International Nuclear Information System (INIS)

    Put, M.J.; Dierckx, A.; Aertsens, M.; Canniere, P. de

    1998-01-01

    Performance assessment studies are expected to predict the enhancement of the migration of trivalent lanthanides and actinides due to their complexation with organic matter, which play a role as a transport agent [1]. Therefore, the mobility of the dissolved organic matter in the interstitial boom clay water is studied. For the first time, the mobile fraction present in the clay water is concentrated and labelled with a radioisotope to study the mobility of the organic matter in clay and the interaction of the mobile with the non-mobile. The isotopes tested as label are 125 I and 14 C. The 125 I label proved to be unstable and hence discarded. The labelled organic matter is then diluted for migration experiments on boom clay cores under anaerobic conditions. The influence of the molecular size on its mobility is studied by the separation of the labelled organic matter in different size fractions. (orig.)

  12. Elevated rates of organic carbon, nitrogen, and phosphorus accumulation in a highly impacted mangrove wetland

    Science.gov (United States)

    Sanders, Christian J.; Eyre, Bradley D.; Santos, Isaac R.; Machado, Wilson; Luiz-Silva, Wanilson; Smoak, Joseph M.; Breithaupt, Joshua L.; Ketterer, Michael E.; Sanders, Luciana; Marotta, Humberto; Silva-Filho, Emmanoel

    2014-04-01

    The effect of nutrient enrichment on mangrove sediment accretion and carbon accumulation rates is poorly understood. Here we quantify sediment accretion through radionuclide tracers to determine organic carbon (OC), total nitrogen (TN), and total phosphorus (TP) accumulation rates during the previous 60 years in both a nutrient-enriched and a pristine mangrove forest within the same geomorphological region of southeastern Brazil. The forest receiving high nutrient loads has accumulated OC, TN, and TP at rates that are fourfold, twofold, and eightfold respectively, higher than those from the undisturbed mangrove. Organic carbon and TN stable isotopes (δ13C and δ15N) reflect an increased presence of organic matter (OM) originating with either phytoplankton, benthic algae, or another allochthonous source within the more rapidly accumulated sediments of the impacted mangrove. This suggests that the accumulation rate of OM in eutrophic mangrove systems may be enhanced through the addition of autochthonous and allochthonous nonmangrove material.

  13. Optical properties and composition changes in chromophoric dissolved organic matter along trophic gradients: Implications for monitoring and assessing lake eutrophication.

    Science.gov (United States)

    Zhang, Yunlin; Zhou, Yongqiang; Shi, Kun; Qin, Boqiang; Yao, Xiaolong; Zhang, Yibo

    2017-12-26

    Chromophoric dissolved organic matter (CDOM) is an important optically active substance in aquatic environments and plays a key role in light attenuation and in the carbon, nitrogen and phosphorus biogeochemical cycles. Although the optical properties, abundance, sources, cycles, compositions and remote sensing estimations of CDOM have been widely reported in different aquatic environments, little is known about the optical properties and composition changes in CDOM along trophic gradients. Therefore, we collected 821 samples from 22 lakes along a trophic gradient (oligotrophic to eutrophic) in China from 2004 to 2015 and determined the CDOM spectral absorption and nutrient concentrations. The total nitrogen (TN), total phosphorus (TP), and chlorophyll a (Chla) concentrations and the Secchi disk depth (SDD) ranged from 0.02 to 24.75 mg/L, 0.002-3.471 mg/L, 0.03-882.66 μg/L, and 0.05-17.30 m, respectively. The trophic state index (TSI) ranged from 1.55 to 98.91 and covered different trophic states, from oligotrophic to hyper-eutrophic. The CDOM absorption coefficient at 254 nm (a(254)) ranged from 1.68 to 92.65 m -1 . Additionally, the CDOM sources and composition parameters, including the spectral slope and relative molecular size value, exhibited a substantial variability from the oligotrophic level to other trophic levels. The natural logarithm value of the CDOM absorption, lna(254), is highly linearly correlated with the TSI (r 2  = 0.92, p 10 m -1 , respectively. The results suggested that the CDOM absorption coefficient a(254) might be a more sensitive single indicator of the trophic state than TN, TP, Chla and SDD. Therefore, we proposed a CDOM absorption coefficient and determined the threshold for defining the trophic state of a lake. Several advantages of measuring and estimating CDOM, including rapid experimental measurements, potential in situ optical sensor measurements and large-spatial-scale remote sensing estimations, make it

  14. 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.

  15. 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

  16. Carbon-14 measurements and characterization of dissolved organic carbon in ground water

    International Nuclear Information System (INIS)

    Murphy, E.M.

    1987-01-01

    Carbon-14 was measured in the dissolved organic carbon (DOC) in ground water and compared with 14 C analyses of dissolved inorganic carbon (DIC). Two field sites were used for this study; the Stripa mine in central Sweden, and the Milk River Aquifer in southern Alberta, Canada. The Stripa mine consists of a Precambrian granite dominated by fracture flow, while the Milk River Aquifer is a Cretaceous sandstone aquifer characterized by porous flow. At both field sites, 14 C analyses of the DOC provide additional information on the ground-water age. Carbon-14 was measured on both the hydrophobic and hydrophilic organic fractions of the DOC. The organic compounds in the hydrophobic and hydrophilic fractions were also characterized. The DOC may originate from kerogen in the aquifer matrix, from soil organic matter in the recharge zone, of from a combination of these two sources. Carbon-14 analyses, along with characterization of the organics, were used to determine this origin. Carbon-14 analyses of the hydrophobic fraction in the Milk River Aquifer suggest a soil origin, while 14 C analyses of the hydrophilic fraction suggest an origin within the Cretaceous sediments (kerogen) or from the shale in contact with the aquifer

  17. 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

  18. 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.

  19. Multi-technical approach to characterize the dissolved organic matter from clay-stone

    International Nuclear Information System (INIS)

    Blanchart, Pascale; Michels, Raymond; Faure, Pierre; Parant, Stephane; Bruggeman, Christophe; De Craen, Mieke

    2012-01-01

    Document available in extended abstract form only. Currently, different clay formations (Boom Clay, Callovo-Oxfordian argilites, Opalinus Clay, Toarcian shales...) are studied as reference host rocks for methodological studies on the geological disposal of high-level and long-lived radioactive waste. While a significant effort is being done on the characterization of the mineral composition and the reactivity of the clays as barriers, the occurrence of organic matter, even in low proportion cannot be neglected. The organic matter appears as gas (C 1 -C 4 as identified in the Bure underground facilities), as solid (kerogen), as hydrocarbon liquids (free hydrocarbons within the kerogen or adsorbed on minerals) as well as in the aqueous phase (Dissolved Organic Matter - DOM). DOM raises specific interest, as it may have complexation properties towards metals and rare earth elements and is potentially mobile. Therefore, it is important to characterize the DOM as part of a study of feasibility of geological disposal. In this study, four host rocks were studied: - The Callovo-Oxfordian shales of Bure Underground Research Laboratory (Meuse, France); - The Opalinus Clay of Mont Terri Underground Research Laboratory (Switzerland); - The Toarcian shales of Tournemire (Aveyron, France); - The Boom Clay formation studied in The HADES Underground Research Laboratory (Mol, Belgium). Organic matter characteristics vary upon formation in terms of (i) origin (mainly marine type II; mixtures of marine type II and higher plants type III organic matter often poorly preserved), (ii) TOC contents, (iii) thermal maturity (for instance, Opalinus Clay and Toarcian shales are more mature and have poor oxygen content compare to Callovo-Oxfordian shales and Boom Clay). These differences in organic matter quality may have an influence on the quantity and the quality of DOM. The DOM of the rocks was isolated by Soxhlet extraction using pure water. A quantitative and qualitative multi

  20. Global distribution of dissolved organic matter along the aquatic continuum: Across rivers, lakes and oceans.

    Science.gov (United States)

    Massicotte, Philippe; Asmala, Eero; Stedmon, Colin; Markager, Stiig

    2017-12-31

    Based on an extensive literature survey containing more than 12,000 paired measurements of dissolved organic carbon (DOC) concentrations and absorption of chromophoric dissolved organic matter (CDOM) distributed over four continents and seven oceans, we described the global distribution and transformation of dissolved organic matter (DOM) along the aquatic continuum across rivers and lakes to oceans. A strong log-linear relationship (R 2 =0.92) between DOC concentration and CDOM absorption at 350nm was observed at a global scale, but was found to be ecosystem-dependent at local and regional scales. Our results reveal that as DOM is transported towards the oceans, the robustness of the observed relation decreases rapidly (R 2 from 0.94 to 0.44) indicating a gradual decoupling between DOC and CDOM. This likely reflects the decreased connectivity between the landscape and DOM along the aquatic continuum. To support this hypothesis, we used the DOC-specific UV absorbance (SUVA) to characterize the reactivity of the DOM pool which decreased from 4.9 to 1.7m 2 × gC -1 along the aquatic continuum. Across the continuum, a piecewise linear regression showed that the observed decrease of SUVA occurred more rapidly in freshwater ecosystems compared to marine water ecosystems, suggesting that the different degradation processes act preferentially on CDOM rather than carbon content. The observed change in the DOM characteristics along the aquatic continuum also suggests that the terrestrial DOM pool is gradually becoming less reactive, which has profound consequences on cycling of organic carbon in aquatic ecosystems. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Examining the role of dissolved organic nitrogen in stream ecosystems across biomes and Critical Zone gradients

    Science.gov (United States)

    Wymore, A.; Rodriguez-Cardona, B.; Coble, A. A.; Potter, J.; Lopez Lloreda, C.; Perez Rivera, K.; De Jesus Roman, A.; Bernal, S.; Martí Roca, E.; Kram, P.; Hruska, J.; Prokishkin, A. S.; McDowell, W. H.

    2016-12-01

    Watershed nitrogen exports are often dominated by dissolved organic nitrogen (DON); yet, little is known about the role ambient DON plays in ecosystems. As an organic nutrient, DON may serve as either an energy source or as a nutrient source. One hypothesized control on DON is nitrate (NO3-) availability. Here we examine the interaction of NO3- and DON in streams across temperate forests, tropical rainforests, and Mediterranean and taiga biomes. Experimental streams also drain contrasting Critical Zones which provide gradients of vegetation, soil type and lithology (e.g. volcaniclastic, granitic, ultramafic, Siberian Traps Flood Basalt) in which to explore how the architecture of the Critical Zone affects microbial biogeochemical reactions. Streams ranged in background dissolved organic carbon (DOC) concentration (1-50 mg C/L) and DOC: NO3- ratios (10-2000). We performed a series of ecosystem-scale NO3- additions in multiple streams within each environment and measured the change in DON concentration. Results demonstrate that there is considerable temporal and spatial variation across systems with DON both increasing and decreasing in response to NO3- addition. Ecologically this suggests that DON can serve as both a nutrient source and an energy source to aquatic microbial communities. In contrast, DOC concentrations rarely changed in response to NO3- additions suggesting that the N-rich fraction of the ambient dissolved organic matter pool is more bioreactive than the C-rich fraction. Contrasting responses of the DON and DOC pools indicate different mechanisms controlling their respective cycling. It is likely that DON plays a larger role in ecosystems than previously recognized.

  2. Restoration and Purification of Dissolved Organic Nitrogen by Bacteria and Phytoremediation in Shallow Eutrophic Lakes Sediments

    Science.gov (United States)

    Li, Xin; Yue, Yi

    2018-06-01

    Endogenous organic nitrogen loadings in lake sediments have increased with human activity in recent decades. A 6-month field study from two disparate shallow eutrophic lakes could partly reveal these issues by analysing seasonal variations of biodegradation and phytoremediation in the sediment. This paper describes the relationship between oxidation reduction potential, temperature, microbial activity and phytoremediation in nitrogen cycling by calculation degradative index of dissolved organic nitrogen and amino acid decomposition. The index was being positive in winter and negative in summer while closely positive correlated with biodegradation. Our analysis revealed that rather than anoxic condition, biomass is the primary factor to dissolved organic nitrogen distribution and decomposition. Some major amino acids statistics also confirm the above view. The comparisons of organic nitrogen and amino acid in abundance and seasons in situ provides that demonstrated plants cue important for nitrogen removal by their roots adsorption and immobilization. In conclusion, enhanced microbial activity and phytoremediation with the seasons will reduce the endogenous nitrogen loadings by the coupled mineralization and diagenetic process.

  3. Assessing the effect of dissolved organic ligands on mineral dissolution rates: An example from calcite dissolution

    International Nuclear Information System (INIS)

    DeMaio, T.; Grandstaff, D.E.

    1997-01-01

    Experiments suggest that dissolved organic ligands may primarily modify mineral dissolution rates by three mechanisms: (1) metal-ligand (M-L) complex formation in solution, which increases the degree of undersaturation, (2) formation of surface M-L complexes that attack the surface, and (3) formation of surface complexes which passivate or protect the surface. Mechanisms (1) and (2) increase the dissolution rate and the third decreases it compared with organic-free solutions. The types and importance of these mechanisms may be assessed from plots of dissolution rate versus degree of undersaturation. To illustrate this technique, calcite, a common repository cementing and vein-filling mineral, was dissolved at pH 7.8 and 22 C in Na-Ca-HCO 3 -Cl solutions with low concentrations of three organic ligands. Low citrate concentrations (50 microM) increased the dissolution rate consistent with mechanism (1). Oxalate decreased the rate, consistent with mechanism (3). Low phthalate concentration (<50 microM) decreased calcite dissolution rates; however, higher concentrations increased the dissolution rates, which became faster than in inorganic solutions. Thus, phthalate exhibits both mechanisms (2) and (3) at different concentrations. In such cases linear extrapolations of dissolution rates from high organic ligand concentrations may not be valid

  4. 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.

  5. 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

  6. PHOTOGENERATION OF SINGLET OXYGEN AND FREE RADICALS IN DISSOLVED ORGANIC MATTER ISOLATED FROM THE MISSISSIPPI AND ATCHAFALAYA RIVER PLUMES

    Science.gov (United States)

    The photoreactivity to UV light of ultrafiltered dissolved organic matter (DOM) collected during cruises along salinity transects in the Mississippi and Atchafalaya River plumes was examined by measuring photogenerated free radicals and singlet molecular oxygen (1O2) photosensiti...

  7. Development of an extraction method for the determination of dissolved organic radiocarbon in seawater by accelerator mass spectrometry

    International Nuclear Information System (INIS)

    Tanaka, Takayuki; Otosaka, Shigeyoshi; Togawa, Orihiko; Amano, Hikaru

    2009-01-01

    We developed an extraction method for accurately and reproducibly determining dissolved organic radiocarbon in seawater by ultraviolet oxidation of dissolved organic carbon and subsequent accelerator mass spectrometry. We determined the irradiation time required for oxidation of the dissolved organic carbon. By modifying the experimental apparatus, we decreased contamination by dead carbon, which came mainly from petrochemical products in the apparatus and from the incursion of carbon dioxide from the atmosphere. The modifications decreased the analytical blank level to less than 1% of sample size, a percentage that had not previously been achieved. The recovery efficiency was high, 95±1%. To confirm both the accuracy and reproducibility of the method, we tested it by analyzing an oxalic acid radiocarbon reference material and by determining the dissolved organic carbon in surface seawater samples. (author)

  8. SPATIAL AND TEMPORAL DISTRIBUTION OF COLOURED DISSOLVED ORGANIC MATTER (CDOM) IN NARRAGANSETT BAY, RI: IMPLICATIONS FOR PHYTOPLANKTON IN COASTAL WATERS

    Science.gov (United States)

    One indicator of health in estuarine and coastal ecosystems is the ability of local waters to transmit sunlight to planktonic, macrophytic, and other submerged vegetation for photosynthesis. The concentration of coloured dissolved organic matter (CDOM) is a primary factor affecti...

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

    KAUST Repository

    Baltar, Federico; Moran, Xose Anxelu G.; Lø nborg, Christian

    2017-01-01

    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

  10. Impact of low molecular weight organic acids and dissolved organic matter on sorption and mobility of isoproturon in two soils.

    Science.gov (United States)

    Ding, Qing; Wu, Hai Lang; Xu, Yun; Guo, Li Juan; Liu, Kai; Gao, Hui Min; Yang, Hong

    2011-06-15

    Isoproturon is a selective herbicide belonging to the phenylurea family and widely used for pre- and post-emergence control of annual weeds. Soil amendments (e.g. organic compounds or dissolved organic matter) may affect environmental behavior and bioavailability of pesticides. However, whether the physiochemical process of isoproturon in soils is affected by organic amendments and how it is affected in different soil types are unknown. To evaluate the impact of low molecular weight organic acids (LMWOA) and dissolved organic matter (DOM) on sorption/desorption and mobility of isoproturon in soils, comprehensive analyses were performed using two distinct soil types (Eutric gleysols and Hap udic cambisols). Our analysis revealed that adsorption of isoproturon in Eutric gleysols was depressed, and desorption and mobility of isoproturon were promoted in the presence of DOM and LMWOA. However, the opposite result was observed with Hap udic cambisols, suggesting that the soil type affected predominantly the physiochemical process. We also characterized differential components of the soils using three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy and Fourier transform infrared (FT-IR) spectroscopy and show that the two soils displayed different intensity of absorption bands for several functional groups. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. The role of some microorganisms on phosphorus availability from organic materials using nuclear technique

    International Nuclear Information System (INIS)

    Abou-seer, A.M.M

    2010-01-01

    Series of laboratory and field experiments were conducted at Soil Microbiology Unit and Farm of Soil and Water Research Department, Nuclear Research Center, Atomic Energy Authority, Egypt. Availability of phosphorus in Egyptian alkaline soil had been subjected to many problems related with adverse environmental conditions (biotic and abiotic factors) and human mismanagement on flied scale. The supply power of this second important element under these conditions was very low and soil become P-deficient. To overcome this problem, there are two strategies via application of chemical approach or biological management using soil microorganisms and fungi. We considered the biological approach as the most reliable strategy for reorientation of status in soil without risks on environment. This objective aims to recycling different plant and animal residues in soil which is consistent with (sustainable development) of these organic residues as organic P source for PSMs.The present work aimed to study :1- The role of PSMs as microbiological means to convert organic P into available form utilized by plant through secretion of acid and alkaline phosphatase.2-The incubation experiment to point out the best incubation period of the residues with PSMs to be chosen before application in the field experiment and the selection of applicable residues 3- The effect of PSMs on degradation of faba bean straw and sheep manure used as organic fertilizer in addition to nitrogen fixing bacteria on marjoram (as medical plant) growth, yield, nutrient uptake and essential oil yield.4- The purification of the produced enzymes from Pseudomonas aeruginosa and studying its properties in addition to the possible application pure enzyme of sequential fractionation scheme of phosphorus in soil after harvest marjoram plant.5- The effects of gamma irradiation on the chemical constituents and antimicrobial action of essential oil marjoram plant.

  12. 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.

  13. An organic-inorganic hybrid coagulant containing Al, Zn and Fe (HOAZF: preparation, efficiency and mechanism of removing organic phosphorus

    Directory of Open Access Journals (Sweden)

    Y. Fu

    2018-04-01

    Full Text Available A polymeric-Al-Zn-Fe (PAZF coagulant showing high removal of pollutants has been successfully developed using a galvanized slag in earlier works, but it gave less elimination of phosphorus. To improve phosphorus removal, a hybrid organic-Al-Zn-Fe (HOAZF coagulant was prepared using PAZF and polyacrylamide (PAM as an organic additive, and then was characterized by scanning electron microscopy (SEM, infrared spectroscopy (IR, X-ray diffraction (XRD, and Zeta potential, respectively. Removing efficiency and mechanism of organophosphorus by HOAZF was probed using jar tests in treating a simulated pesticide wastewater containing dichlorvos (DDVP, compared to that by PAZF and polyaluminum chloride. The results displayed that HOAZF having relative lower Zeta potential (compared to PAZF exhibited complex surface morphology composited by Al, Zn and Fe and PAM, forming some new crystalline and amorphous substances different from that in PAZF. HOAZF gave higher removal of organophosphorus and far lower dosage than PAZF, and also posed a suitable wider pH range (pH = 7–12 for HOAZF and 10–11 for PAZF, respectively and suitable wider organophosphorus level range than PAZF. Removing organophosphorus by HOAZF was a simultaneous complex process involving a non-phase transfer of adsorption/bridging/sweeping and a phase transfer of chemical precipitation.

  14. Formation of Chromophoric Dissolved Organic Matter by Bacterial Degradation of Phytoplankton-Derived Aggregates

    Directory of Open Access Journals (Sweden)

    Joanna D. Kinsey

    2018-01-01

    Full Text Available Organic matter produced and released by phytoplankton during growth is processed by heterotrophic bacterial communities that transform dissolved organic matter into biomass and recycle inorganic nutrients, fueling microbial food web interactions. Bacterial transformation of phytoplankton-derived organic matter also plays a poorly known role in the formation of chromophoric dissolved organic matter (CDOM which is ubiquitous in the ocean. Despite the importance of organic matter cycling, growth of phytoplankton and activities of heterotrophic bacterial communities are rarely measured in concert. To investigate CDOM formation mediated by microbial processing of phytoplankton-derived aggregates, we conducted growth experiments with non-axenic monocultures of three diatoms (Skeletonema grethae, Leptocylindrus hargravesii, Coscinodiscus sp. and one haptophyte (Phaeocystis globosa. Phytoplankton biomass, carbon concentrations, CDOM and base-extracted particulate organic matter (BEPOM fluorescence, along with bacterial abundance and hydrolytic enzyme activities (α-glucosidase, β-glucosidase, leucine-aminopeptidase were measured during exponential growth and stationary phase (~3–6 weeks and following 6 weeks of degradation. Incubations were performed in rotating glass bottles to keep cells suspended, promoting cell coagulation and, thus, formation of macroscopic aggregates (marine snow, more similar to surface ocean processes. Maximum carbon concentrations, enzyme activities, and BEPOM fluorescence occurred during stationary phase. Net DOC concentrations (0.19–0.46 mg C L−1 increased on the same order as open ocean concentrations. CDOM fluorescence was dominated by protein-like signals that increased throughout growth and degradation becoming increasingly humic-like, implying the production of more complex molecules from planktonic-precursors mediated by microbial processing. Our experimental results suggest that at least a portion of open

  15. Evaluating Spatial Variability in Sediment and Phosphorus Concentration-Discharge Relationships Using Bayesian Inference and Self-Organizing Maps

    Science.gov (United States)

    Underwood, Kristen L.; Rizzo, Donna M.; Schroth, Andrew W.; Dewoolkar, Mandar M.

    2017-12-01

    Given the variable biogeochemical, physical, and hydrological processes driving fluvial sediment and nutrient export, the water science and management communities need data-driven methods to identify regions prone to production and transport under variable hydrometeorological conditions. We use Bayesian analysis to segment concentration-discharge linear regression models for total suspended solids (TSS) and particulate and dissolved phosphorus (PP, DP) using 22 years of monitoring data from 18 Lake Champlain watersheds. Bayesian inference was leveraged to estimate segmented regression model parameters and identify threshold position. The identified threshold positions demonstrated a considerable range below and above the median discharge—which has been used previously as the default breakpoint in segmented regression models to discern differences between pre and post-threshold export regimes. We then applied a Self-Organizing Map (SOM), which partitioned the watersheds into clusters of TSS, PP, and DP export regimes using watershed characteristics, as well as Bayesian regression intercepts and slopes. A SOM defined two clusters of high-flux basins, one where PP flux was predominantly episodic and hydrologically driven; and another in which the sediment and nutrient sourcing and mobilization were more bimodal, resulting from both hydrologic processes at post-threshold discharges and reactive processes (e.g., nutrient cycling or lateral/vertical exchanges of fine sediment) at prethreshold discharges. A separate DP SOM defined two high-flux clusters exhibiting a bimodal concentration-discharge response, but driven by differing land use. Our novel framework shows promise as a tool with broad management application that provides insights into landscape drivers of riverine solute and sediment export.

  16. Optical Proxies for Dissolved Organic Matter in Estuaries and Coastal Waters

    Science.gov (United States)

    Osburn, C. L.; Montgomery, M. T.; Boyd, T. J.; Bianchi, T. S.; Coffin, R. B.; Paerl, H. W.

    2016-02-01

    The flux of terrestrial dissolved organic carbon (DOC) into the coastal ocean from rivers and estuaries is a major part of the ocean's carbon cycle. Absorbing and fluorescing properties of chromophoric dissolved organic matter (CDOM) often are used to fingerprint its sources and to track fluxes of terrestrial DOM into the ocean. They also are used as proxies for organic matter to calibrate remote sensing observations from air and space and from in situ platforms. In general, strong relationships hold for large river dominated estuaries (e.g., the Mississippi River) but little is known about how widely such relationships can be developed in estuaries that have relatively small or multiple riverine inputs. Results are presented from a comparison of six diverse estuarine systems: the Atchafalaya River (ARE), the Mackenzie River (MRE), the Chesapeake Bay (CBE), Charleston Harbor (CHE), Puget Sound (PUG), and the Neuse River (NRE). Mean DOM concentrations ranged from 100 to 700 µM and dissolved lignin concentrations ranged from ca. 3-30 µg L-1. Overall trends were linear between CDOM measured at 350 nm (a350) and DOC concentration (R2=0.77) and between a350 and lignin (R2=0.87). Intercepts of a350 vs lignin were not significantly different from zero (P=0.43) suggesting that most of the CDOM was terrestrial in nature. Deviations from these regressions were strongest in the Neuse River Estuary, the most eutrophic of the six estuaries studied. After this calibration procedure, fluorescence modeling via parallel factor analysis (PARAFAC) was used to make estimates of terrigenous and planktonic DOC in these estuaries.

  17. [Evolution of Dissolved Organic Matter Properties in a Constructed Wetland of Xiao River, Hebei].

    Science.gov (United States)

    Ma, Li-na; Zhang, Hui; Tan, Wen-bing; Yu, Min-da; Huang, Zhi-gang; Gao, Ru-tai; Xi, Bei-dou; He, Xiao-song

    2016-01-01

    The evolution of water DOC and COD, and the source, chemical structure, humification degree and redox of dissolved organic matter (DOM) in a constructed wetland of Xiao River, Hebei, was investigated by 3D excitation--emission matrix fluorescence spectroscopy coupled with ultraviolet spectroscopy and chemical reduction, in order to explore the geochemical processes and environmental effects of DOM. Although DOC contributes at least 60% to COD, its decrease in the constructed wetland is mainly caused by the more extensive degradation of elements N, H, S, and P than C in DOM, and 65% is contributed from the former. DOM is mainly consisted of microbial products based on proxies f470/520 and BIX, indicating that DOM in water is apparently affected by microbial degradation. The result based on PARAFAC model shows that DOM in the constructed wetland contains protein-like and humus-like components, and Fulvic- and humic-like components are relatively easier to degrade than protein-like components. Fulvic- and humic-like components undergo similar decomposition in the constructed wetland. A common source of chromophoric dissolved organic matter (CDOM) and fluorescent dissolved organic matter (FDOM) exists; both CDOM and FDOM are mainly composed of a humus-like material and do not exhibit selective degradation in the constructed wetland. The proxies E2 /E3, A240-400, r(A, C) and HIX in water have no changes after flowing into the constructed wetland, implying that the humification degree of DOM in water is hardly affected by wet constructed wetland. However, the constructed wetland environment is not only beneficial in forming the reduced state of DOM, but also facilitates the reduction of ferric. It can also improve the capability of DOM to function as an electron shuttle. This result may be related to the condition that the aromatic carbon of DOM can be stabilized well in the constructed wetland.

  18. State factor relationships of dissolved organic carbon and nitrogen losses from unpolluted temperate forest watersheds

    Science.gov (United States)

    Perakis, S.S.; Hedin, L.O.

    2007-01-01

    We sampled 100 unpolluted, old-growth forested watersheds, divided among 13 separate study areas over 5 years in temperate southern Chile and Argentina, to evaluate relationships among dominant soil-forming state factors and dissolved carbon and nitrogen concentrations in watershed streams. These watersheds provide a unique opportunity to examine broad-scale controls over carbon (C) and nitrogen (N) biogeochemistry in the absence of significant human disturbance from chronic N deposition and land use change. Variations in the ratio dissolved organic carbon (DOC) to nitrogen (DON) in watershed streams differed by underlying soil parent material, with average C:N = 29 for watersheds underlain by volcanic ash and basalt versus C:N = 73 for sedimentary and metamorphic parent materials, consistent with stronger adsorption of low C:N hydrophobic materials by amorphous clays commonly associated with volcanic ash and basalt weathering. Mean annual precipitation was related positively to variations in both DOC (range: 0.2-9.7 mg C/L) and DON (range: 0.008-0.135 mg N/L) across study areas, suggesting that variations in water volume and concentration may act synergistically to influence C and N losses across dry to wet gradients in these forest ecosystems. Dominance of vegetation by broadleaf versus coniferous trees had negligible effects on organic C and N concentrations in comparison to abiotic factors. We conclude that precipitation volume and soil parent material are important controls over chemical losses of dissolved organic C and N from unpolluted temperate forest watersheds. Our results raise the possibility that biotic imprints on watershed C and N losses may be less pronounced in naturally N-poor forests than in areas impacted by land use change and chronic N deposition. Copyright 2007 by the American Geophysical Union.

  19. Effects of coral reef benthic primary producers on dissolved organic carbon and microbial activity.

    Directory of Open Access Journals (Sweden)

    Andreas F Haas

    Full Text Available Benthic primary producers in marine ecosystems may significantly alter biogeochemical cycling and microbial processes in their surrounding environment. To examine these interactions, we studied dissolved organic matter release by dominant benthic taxa and subsequent microbial remineralization in the lagoonal reefs of Moorea, French Polynesia. Rates of photosynthesis, respiration, and dissolved organic carbon (DOC release were assessed for several common benthic reef organisms from the backreef habitat. We assessed microbial community response to dissolved exudates of each benthic producer by measuring bacterioplankton growth, respiration, and DOC drawdown in two-day dark dilution culture incubations. Experiments were conducted for six benthic producers: three species of macroalgae (each representing a different algal phylum: Turbinaria ornata--Ochrophyta; Amansia rhodantha--Rhodophyta; Halimeda opuntia--Chlorophyta, a mixed assemblage of turf algae, a species of crustose coralline algae (Hydrolithon reinboldii and a dominant hermatypic coral (Porites lobata. Our results show that all five types of algae, but not the coral, exuded significant amounts of labile DOC into their surrounding environment. In general, primary producers with the highest rates of photosynthesis released the most DOC and yielded the greatest bacterioplankton growth; turf algae produced nearly twice as much DOC per unit surface area than the other benthic producers (14.0±2.8 µmol h⁻¹ dm⁻², stimulating rapid bacterioplankton growth (0.044±0.002 log10 cells h⁻¹ and concomitant oxygen drawdown (0.16±0.05 µmol L⁻¹ h⁻¹ dm⁻². Our results demonstrate that benthic reef algae can release a significant fraction of their photosynthetically-fixed carbon as DOC, these release rates vary by species, and this DOC is available to and consumed by reef associated microbes. These data provide compelling evidence that benthic primary producers differentially influence

  20. Spatial and temporal distribution of coloured dissolved organic matter in a hypertrophic freshwater lagoon

    Directory of Open Access Journals (Sweden)

    Diana Vaičiūtė

    2015-05-01

    Full Text Available A dataset of 224 Medium Resolution Imaging Spectrometer (MERIS full resolution satellite images were processed to retrieve the concentration of coloured dissolved organic matter (CDOM in a hypertrophic estuary (Curonian Lagoon, Lithuania and Russia. Images covered a period of 7 months, spanning from the ice melting (March to the late summer (September of 7 consecutive years (2005-2011. The aim of the study was to analyse the spatial and temporal variations of CDOM, by focusing on the main regulating factors (riverine discharge, sea-lagoon water exchange, water temperature, chlorophyll a, wind in a large estuary. The working hypothesis is that CDOM distribution may reveal distinct, site specific seasonal patterns. Our results demonstrated that CDOM concentrations at the whole lagoon level were elevated (1.5-4 m-1 and slightly but significantly higher in spring (1.50 m-1 on average compared to the summer (1.45 m-1 on average. This is due to very different flow of CDOM-rich freshwater from the main lagoon tributary in spring compared to summer. They also highlight macroscopic differences among areas within the lagoon, depending on season, suggesting a complex regulation of CDOM in this system. Significant factors explaining observed differences are the dilution of lagoon water with CDOM-poor brackish water, regeneration of large amounts of dissolved organic matter from sediments and combinations of uptake/release from phytoplankton. CDOM and its variations are understudied due to inherent methodological and analytical difficulties. However, this pool has a demonstrated relevant role in the biogeochemistry of aquatic environments. We speculate that the dissolved organic pool in the Curonian Lagoon has a mainly allochthonous origin in the high discharge period and an autochthonous origin in the summer, algal bloom period. Both positive and negative relationships between CDOM and phytoplankton suggest that pelagic microalgae may act as a source or as

  1. 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.

  2. 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

  3. 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.

  4. Black phosphorus induced photo-doping for high-performance organic-silicon heterojunction photovoltaics

    Institute of Scientific and Technical Information of China (English)

    Zhouhui Xia; Pengfei Li; Yuqiang Liu; Tao Song; Qiaoliang Bao; Shuit-Tong Lee; Baoquan Sun

    2017-01-01

    In conventional crystalline silicon (Si) homojunction solar cells,a strategy of doping by transporting phosphorus or boron impurities into Si is commonly used to build Ohmic contacts at rear electrodes.However,this technique involves an energy intensive,high temperature (~ 800 ℃) process and toxic doping materials.Black phosphorus (BP) is a two-dimensional,narrow bandgap semiconductor with high carrier mobility that exhibits broad light harvesting properties.Here,we place BP:zinc oxide (ZnO) composite films between Si and aluminum (Al) to improve their contact.Once the BP harvests photons with energies below 1.1 eV from the crystalline Si,the ZnO carrier concentration increases dramatically due to charge injection.This photo-induced doping results in a high carrier concentration in the ZnO film,mimicking the modulated doping technique used in semiconductor heterojunctions.We show that photo-induced carriers dramatically increase the conductivities of the BP-modified ZnO films,thus reducing the contact resistance between Si and Al.A photovoltaic power conversion efficiency of 15.2% is achieved in organic-Si heterojunction solar cells that use a ZnO:BP layer.These findings demonstrate an effective way of improving Si/metal contact via a simple,low temperature process.

  5. Characteristics of Chromophoric and Fluorescent Dissolved Organic Matter in the Nordic Seas

    OpenAIRE

    Makarewicz, Anna; Kowalczuk, Piotr; Sagan, Sławomir; Granskog, Mats A.; Pavlov, Alexey K.; Zdun, Agnieszka; Borzycka, Karolina; Zabłocka, Monika

    2018-01-01

    Optical properties of Chromophoric (CDOM) and Fluorescent Dissolved Organic Matter (FDOM) were characterized in the Nordic Seas including the West Spitsbergen Shelf during June–July of 2013, 2014 and 2015. The CDOM absorption coefficient at 350 nm, aCDOM(350) showed significant interannual variation. In 2013, the highest average aCDOM(350) values (aCDOM = 0.30 ± 0.12 m−1) were observed due to the influence of cold and low–saline wat...

  6. 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....

  7. Seasonal changes in the optical properties of dissolved organic matter (DOM) in large Arctic rivers

    DEFF Research Database (Denmark)

    Walker, S.A.; Amon, R.M.; Stedmon, Colin

    Arctic rivers deliver over 10% of the annual global river discharge yet little is known about the seasonal fluctuations in the quantity and quality of terrigenous dissolved organic matter (tDOM). A good constraint on such fluctuations is paramount to understand the role that climate change may have...... on tDOM input to the Arctic Ocean. To understand such changes the optical properties of colored tDOM (tCDOM) were studied. Samples were collected over several seasonal cycles from the six largest Arctic Rivers as part of the PARTNERS project. This unique dataset is the first of its kind capturing...

  8. Temperature dependence of the relationship between pCO2 and dissolved organic carbon in lakes

    KAUST Repository

    Pinho, L.

    2016-02-15

    The relationship between the partial pressure of carbon dioxide (pCO2) and dissolved organic carbon (DOC) concentration in Brazilian lakes, encompassing 225 samples across a wide latitudinal range in the tropics, was tested. Unlike the positive relationship reported for lake waters, which was largely based on temperate lakes, we found no significant relationship for low-latitude lakes (< 33°), despite very broad ranges in both pCO2 and DOC levels. These results suggest substantial differences in the carbon cycling of low-latitude lakes, which must be considered when upscaling limnetic carbon cycling to global scales.

  9. The relationship between dissolved organic carbon and hydro-climatic factors in peat-muck soil

    Directory of Open Access Journals (Sweden)

    Jaszczyński Jacek

    2015-03-01

    Full Text Available The object of this study was the concentration of dissolved organic carbon (DOC in soil solution related to groundwater table, soil temperature, moisture, redox potential and intensive storm rain and their changes during ten years (2001–2010. The studies were localized in drained and agriculturally used Kuwasy Mire situated in the middle basin of the Biebrza River, north-eastern Poland. The study site was situated on a low peat soil managed as intensively used grassland. The soil was recognized as peat-muck in the second stage of the mucking process. DOC concentration was determined by means of the flow colorimetric method using the Skalar equipment.

  10. Temperature dependence of the relationship between pCO2 and dissolved organic carbon in lakes

    KAUST Repository

    Pinho, L.; Duarte, Carlos M.; Marotta, H.; Enrich-Prast, A.

    2016-01-01

    The relationship between the partial pressure of carbon dioxide (pCO2) and dissolved organic carbon (DOC) concentration in Brazilian lakes, encompassing 225 samples across a wide latitudinal range in the tropics, was tested. Unlike the positive relationship reported for lake waters, which was largely based on temperate lakes, we found no significant relationship for low-latitude lakes (< 33°), despite very broad ranges in both pCO2 and DOC levels. These results suggest substantial differences in the carbon cycling of low-latitude lakes, which must be considered when upscaling limnetic carbon cycling to global scales.

  11. BOREAS TGB-5 Dissolved Organic Carbon Data from NSA Beaver Ponds

    Science.gov (United States)

    Bourbonniere, Rick; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)

    2000-01-01

    The BOReal Ecosystem-Atmosphere Study Trace Gas Biogeochemistry (BOREAS TGB-5) team collected several data sets related to carbon and trace gas fluxes and concentrations in the Northern Study Area (NSA). This data set contains concentrations of dissolved organic and inorganic carbon species from water samples collected at various NSA sites. In particular, this set covers the NSA Tower Beaver Pond Site and the NSA Gillam Road Beaver Pond Site, including data from all visits to open water sampling locations during the BOREAS field campaigns from April to September 1994. The data are provided in tabular ASCII files.

  12. Carbon and phosphorus regulating bacterial metabolism in oligotrophic boreal lakes

    DEFF Research Database (Denmark)

    Vidal, L. O.; Graneli, W.; Daniel, C. B.

    2011-01-01

    This study focused on how phosphorus and carbon control pelagic bacteria in lakes over a gradient of dissolved organic carbon (DOC from 6.7 to 29.5 mg C L(-1)) and phosphorus (P-tot from 5 to 19 mu g L(-1)). Five oligotrophic lakes in southern Sweden were sampled in late autumn. Phosphate...... carbon mineralization in this kind of system during autumn is conditioned by the combined availability of labile carbon and phosphorus, with the assimilated carbon mainly transformed to inorganic carbon in respiration, contributing to CO(2) supersaturation in these systems....

  13. [Influence of Natural Dissolved Organic Matter on the Passive Sampling Technique and its Application].

    Science.gov (United States)

    Yu, Shang-yun; Zhou, Yan-mei

    2015-08-01

    This paper studied the effects of different concentrations of natural dissolved organic matter (DOM) on the passive sampling technique. The results showed that the presence of DOM affected the organic pollutant adsorption ability of the membrane. For lgK(OW), 3-5, DOM had less impact on the adsorption of organic matter by the membrane; for lgK(OW), > 5.5, DOM significantly increased the adsorption capacity of the membrane. Meanwhile, LDPE passive sampling technique was applied to monitor PAHs and PAEs in pore water of three surface sediments in Taizi River. All of the target pollutants were detected in varying degrees at each sampling point. Finally, the quotient method was used to assess the ecological risks of PAHs and PAEs. The results showed that fluoranthene exceeded the reference value of the aquatic ecosystem, meaning there was a big ecological risk.

  14. Phosphatase activity and culture conditions of the yeast Candida mycoderma sp. and analysis of organic phosphorus hydrolysis ability.

    Science.gov (United States)

    Yan, Mang; Yu, Liufang; Zhang, Liang; Guo, Yuexia; Dai, Kewei; Chen, Yuru

    2014-11-01

    Orthophosphate is an essential but limiting macronutrient for plant growth. About 67% cropland in China lacks sufficient phosphorus, especially that with red soil. Extensive soil phosphorus reserves exist in the form of organic phosphorus, which is unavailable for root uptake unless hydrolyzed by secretory acid phosphatases. Thus, many microorganisms with the ability to produce phosphatase have been exploited. In this work, the activity of an extracellular acid phosphatase and yeast biomass from Candida mycoderma was measured under different culture conditions, such as pH, temperature, and carbon source. A maximal phosphatase activity of 8.47×10(5)±0.11×10(5)U/g was achieved by C. Mycoderma in 36 hr under the optimal conditions. The extracellular acid phosphatase has high activity over a wide pH tolerance range from 2.5 to 5.0 (optimum pH3.5). The effects of different phosphorus compounds on the acid phosphatase production were also studied. The presence of phytin, lecithin or calcium phosphate reduced the phosphatase activity and biomass yield significantly. In addition, the pH of the culture medium was reduced significantly by lecithin. The efficiency of the strain in releasing orthophosphate from organic phosphorus was studied in red soil (used in planting trees) and rice soil (originating as red soil). The available phosphorus content was increased by 230% after inoculating 20 days in rice soil and decreased by 50% after inoculating 10 days in red soil. This work indicates that the yeast strain C. mycoderma has potential application for enhancing phosphorus utilization in plants that grow in rice soil. Copyright © 2014. Published by Elsevier B.V.

  15. Methods for assessing phosphorus overfeeding on organic and conventional dairy farms.

    Science.gov (United States)

    Nordqvist, M; Holtenius, K; Spörndly, R

    2014-02-01

    Phosphorus (P) losses from dairy farms can severely damage aquatic ecosystems, so it is important to have tools to assess overfeeding of P. This study screened P intake and faecal excretion of different P fractions in dairy cows on conventional and organic farms, compared the P feeding level of the herds against the recommendations and analysed different sampling and analysis methods for assessing the general status of P feeding on the farms. The organic (n=14) and conventional farms (n=15) were of comparable size and were located in southern Sweden. On each farm, feed intake was registered for 10 cows representing four different lactation stages and their P intake was calculated and related to current recommendations. Faecal samples taken from the same cows were analysed for total P (TP) and soluble P. Milk production data for the cows were obtained from the Swedish official milk recording scheme. TP was determined in one slurry sample per farm. More than 70% of the cows studied, representing both conventional and organic herds, consumed P in excess of the recommendations. Conventional herds had higher P content in the ration than organic herds, and lactating cows in conventional herds had higher faecal concentrations of total and soluble P than those in organic herds. However in dry cows, the P content of the ration and soluble P and TP in faeces did not differ between the two management systems. Soluble P was well correlated to TP in faeces, and both were good indicators of P overfeeding.

  16. Effect of phosphorus and organic matter on zinc availability on rice

    International Nuclear Information System (INIS)

    Gupta, G.N.; Kamath, M.B.; Motsara, M.R.

    1977-01-01

    Pot culture experiment was conducted on grey brown podzolic soil (Palampur) and Tarai soil (Pantnagar) to study the influence of the addition of organic matter, phosphorus and zinc on the uptake and utilization of zinc by rice crop. In podzolic soils the combined application of Zn-P and Zn-organic matter resulted in reduced zinc content in crop but the crop yield was not affected. The uptake and utilization of applied zinc increased with P application. In Tarai soil, crop response to Zn, P and organic matter was obtained when applied separately. A negative zinc x P and zinc x organic matter interaction was obtained on yield. However, zinc content of the crop increased due to the application of P, organic matter and zinc. The uptake and utilization of applied zinc increased with P application. The analysis of soils after crop harvest indicated an increased amount of 0.1 N HCl extractable zinc in soils treated with zinc in Tarai soils while in podzolic soil from Palampur, the available zinc increased only under the combined application of zinc and P. (author)

  17. 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.

  18. The removal kinetics of dissolved organic matter and the optical clarity of groundwater

    Science.gov (United States)

    Chapelle, Francis H.; Shen, Yuan; Strom, Eric W.; Benner, Ronald

    2016-09-01

    Concentrations of dissolved organic matter (DOM) and ultraviolet/visible light absorbance decrease systematically as groundwater moves through the unsaturated zones overlying aquifers and along flowpaths within aquifers. These changes occur over distances of tens of meters (m) implying rapid removal kinetics of the chromophoric DOM that imparts color to groundwater. A one-compartment input-output model was used to derive a differential equation describing the removal of DOM from the dissolved phase due to the combined effects of biodegradation and sorption. The general solution to the equation was parameterized using a 2-year record of dissolved organic carbon (DOC) concentration changes in groundwater at a long-term observation well. Estimated rates of DOC loss were rapid and ranged from 0.093 to 0.21 micromoles per liter per day (μM d-1), and rate constants for DOC removal ranged from 0.0021 to 0.011 per day (d-1). Applying these removal rate constants to an advective-dispersion model illustrates substantial depletion of DOC over flow-path distances of 200 m or less and in timeframes of 2 years or less. These results explain the low to moderate DOC concentrations (20-75 μM; 0.26-1 mg L-1) and ultraviolet absorption coefficient values ( a 254 < 5 m-1) observed in groundwater produced from 59 wells tapping eight different aquifer systems of the United States. The nearly uniform optical clarity of groundwater, therefore, results from similarly rapid DOM-removal kinetics exhibited by geologically and hydrologically dissimilar aquifers.

  19. Interrill erosion of carbon and phosphorus from conventionally and organically farmed Devon silt soils

    DEFF Research Database (Denmark)

    Kuhn, Nikolaus J; Armstrong, Elizabeth K; Ling, Amy C

    2012-01-01

    particles by raindrop impacted flow. Resistance to interrill erosion varies between soils depending on their physical, chemical and mineralogical properties. In addition, significant changes in soil resistance to interrill erosion occur during storms as a result of changes in surface roughness, cohesion...... to conventional soil management. The enrichment of P and C in the interrill sediment was not directly related to SOC, P content of the soil and soil interrill erodibility. A comparison of soil and sediment properties indicates that crusting, P and C content as well as density and size of eroded aggregate......Globally, between 0.57 and 1.33 Pg of soil organic carbon (SOC) may be affected by interrill processes. Also, a significant amount of phosphorus (P) is contained in the surface soil layer transformed by raindrop impact, runoff and crust formation. In the EU, the P content of a crusted (2 mm...

  20. Unifying concepts linking dissolved organic matter composition to persistence in aquatic ecosystems

    Science.gov (United States)

    Kellerman, Anne M.; Guillemette, François; Podgorski, David C.; Aiken, George R.; Butler, Kenna D.; Spencer, Robert G. M.

    2018-01-01

    The link between composition and reactivity of dissolved organic matter (DOM) is central to understanding the role aquatic systems play in the global carbon cycle; yet, unifying concepts driving molecular composition have yet to be established. We characterized 37 DOM isolates from diverse aquatic ecosystems, including their stable and radiocarbon isotopes (δ13C-dissolved organic carbon (DOC) and Δ14C-DOC), optical properties (absorbance and fluorescence), and molecular composition (ultrahigh resolution mass spectrometry). Isolates encompassed end-members of allochthonous and autochthonous DOM from sites across the United States, the Pacific Ocean, and Antarctic lakes. Modern Δ14C-DOC and optical properties reflecting increased aromaticity, such as carbon specific UV absorbance at 254 nm (SUVA254), were directly related to polyphenolic and polycyclic aromatic compounds, whereas enriched δ13C-DOC and optical properties reflecting autochthonous end-members were positively correlated to more aliphatic compounds. Furthermore, the two sets of autochthonous end-members (Pacific Ocean and Antarctic lakes) exhibited distinct molecular composition due to differences in extent of degradation. Across all sites and end-members studied, we find a consistent shift in composition with aging, highlighting the persistence of certain biomolecules concurrent with degradation time.

  1. Characterization and Fate of Dissolved Organic Matter in the Lena Delta Region, Siberia

    Science.gov (United States)

    Goncalves-Araujo, R.; Stedmon, C. A.; Heim, B.; Dubinenkov, I.; Kraberg, A.; Moiseev, D.; Bracher, A.

    2016-02-01

    Connectivity between the terrestrial and marine environment in the Artic is changing as a result of climate change, influencing both freshwater budgets and the supply of carbon to the sea. This study characterizes the optical properties of dissolved organic matter (DOM) within the Lena Delta region and evaluates the behavior of DOM across the fresh water-marine gradient. Six fluorescent components (four humic-like; one marine humic-like; one protein-like) were identified by Parallel Factor Analysis (PARAFAC) with a clear dominance of allochthonous humic-like signals. Colored DOM (CDOM) and dissolved organic carbon (DOC) were highly correlated and had their distribution coupled with hydrographical conditions. Higher DOM concentration and degree of humification were associated with the low salinity waters of the Lena River. Values decreased towards the higher salinity Laptev Sea shelf waters. Results demonstrate different responses of DOM mixing in relation to the vertical structure of the water column, as reflecting the hydrographical dynamics in the region. Two mixing curves for DOM were apparent. In surface waters above the pycnocline there was a sharper decrease in DOM concentration in relation to salinity indicating removal. In the bottom water layer the DOM decrease within salinity was less. We propose there is a removal of DOM occurring primarily at the surface layer, which is likely driven by photodegradation and flocculation.

  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. A study on the photocatalytic decomposition reactions of organics dissolved in water (II)

    International Nuclear Information System (INIS)

    Sung, K. W.; Na, J. W.; Cho, Y. H.; Chung, H. H.

    2001-01-01

    Experiments on aqueous TiO 2 photocatalytic reaction characteristics of 4 nitrogen-containing and 12 aromatic organic compounds were carried out. Based on the values calculated for the distribution of ionic species and atomic charge, the characteristics of their photocatalytic decomposition were estimated. It was shown that the dependence of decomposition of the N-containing compounds were linearly proportional to their nitrogen atomic charge values, while that of the aromatic compounds were inversely proportional. The effects of aqueous pH, oxygen content and concentration on the TiO 2 photocatalytic characteristics of EDTA-Cu(II) and EDTA-Fe(III) were experimentally investigated. All EDTA systems were decomposed better in the pH range of 2.5∼3.0 and with more dissolved oxygen. These results could be applied to a unit process for removal of organic impurities dissolved in a source water of the system water, and for treatment of EDTA-containing liquid waste produced by chemical cleaning process in the domestic NPPs

  4. Advanced characterization of dissolved organic matter released by bloom-forming marine algae

    KAUST Repository

    Rehman, Zahid Ur

    2017-06-01

    Algal organic matter (AOM), produced by marine phytoplankton during bloom periods, may adversely affect the performance of membrane processes in seawater desalination. The polysaccharide fraction of AOM has been related to (bio)fouling in micro-filtration and ultrafiltration, and reverse osmosis membranes. However, so far, the chemical structure of the polysaccharides released by bloom-forming algae is not well understood. In this study, dissolved fraction of AOM produced by three algal species (Chaetoceros affinis, Nitzschia epithemoides and Hymenomonas spp.) was characterized using liquid chromatography–organic carbon detection (LC-OCD) and fluorescence spectroscopy. Chemical structure of polysaccharides isolated from the AOM solutions at stationary phase was analyzed using proton nuclear magnetic resonance (H-NMR). The results showed that production and composition of dissolved AOM varied depending on algal species and their growth stage. AOM was mainly composed of biopolymers (BP; i.e., polysaccharides and proteins [PN]), but some refractory substances were also present.H-NMR spectra confirmed the predominance of carbohydrates in all samples. Furthermore, similar fingerprints were observed for polysaccharides of two diatom species, which differed considerably from that of coccolithophores. Based on the findings of this study,H-NMR could be used as a method for analyzing chemical profiles of algal polysaccharides to enhance the understanding of their impact on membrane fouling.

  5. A study on the photo catalytic decomposition reactions of organics dissolved in water (II)

    International Nuclear Information System (INIS)

    Sung, K.W.; Na, J. W.; Cho, Y. H.; Chung, H. H.

    2000-01-01

    Experiments on aqueous TiO 2 photo catalytic reaction of nitrogen containing organic compounds such as ethylamine, phenylhydrazine, pyridine, urea and EDTA were carried out. Based on the values calculated for the distribution of ionic species and atomic charge, the characteristics of their photo catalytic decomposition were estimated. It was shown that the decomposition characteristics was linearly proportional to nitrogen atomic charge value. On the other hand, the effects of aqueous pH, oxygen content and concentration on the TiO 2 photo catalytic characteristics of EDTA, EDTA-Cu(II) and EDTA-Fe(III) were experimentally investigated. All EDTA systems were decomposed better in the pH range of 2.5-3.0 and with more dissolved oxygen. These results could be applied to construction of a process for removal of organic impurities dissolved in a source of system water, or for treatment of EDTA-containing liquid waste produced by a chemical cleaning in the domestic NPPs. (author)

  6. Effect of Soil Passage and Ozonation on Dissolved Organic Carbon and Microbial Quantification in Wastewater

    KAUST Repository

    Ahmed, Elaf A.

    2013-05-01

    Water quality data are presented from a laboratory bench scale soil columns study, to simulate an aquifer recharge system injected with MBR wastewater effluent. This study investigates the effect of soil filtration and ozonation on the dissolved organic carbon and bacterial count in the wastewater. Flow Cytometry was used to quantify microorganisms in water samples. Other analytical tests were conducted as well, such as seven anions, fluorescence spectroscopy (FEEM), ultraviolet absorption (UV 254 nm) and dissolved organic carbon measurement (DOC). Influent in this study was injected into two identical soil columns. One of the columns was injected with treated wastewater combined with ozonation called SC1, The second column was injected with treated wastewater only and called SC2. Passing the wastewater through a deeper depth in the soil column showed a reduction in the DOC concentration. Removal of DOC was 53.7 % in SC1 and 53.8 % in SC2. UV 254 nm results demonstrated that the majority of the UV absorbing compounds were removed after the first 30 cm in the soil columns. FEEM results revealed that soil column treatment only doesn\\'t remove humic-like and fulvic-like substances. However, combining soil column treatment with ozonation was capable of removing humic-like, fulvic-like and protein-like substances from the wastewater. Flow Cytometry results showed a bacteria removal of 52.5 %-89.5 % in SC1 which was higher than SC2 removal of 29.1 %-56.5 %.

  7. Identification of Reactive and Refractory Components of Dissolved Organic Nitrogen by FT-ICR Mass Spectrometry

    Science.gov (United States)

    Cooper, W. T.; Podgorski, D. C.; Osborne, D. M.; Corbett, J.; Chanton, J.

    2010-12-01

    Dissolved organic nitrogen is an often overlooked but potentially significant bioavailable component of dissolved organic matter. Studies of bulk DON turnover have been reported, but the compositions of the reactive and refractory components of DON are largely unknown. Here we show the unique ability of atmospheric pressure photoionization (APPI) coupled to ultrahigh resolution mass spectrometry to identify the reactive and refractory components of DON. Figure 1 is an isolated 0.30 m/z window from an ultrahigh resolution APPI FT-ICR mass spectrum of DON in surface waters draining an agricultural area in South Florida. Using this optimized, negative-ion APPI strategy we have been able to identify the reactive and refractory components of DON in these nitrogen-rich waters. Similar results were observed with samples from soil porewaters in sedge-dominated fens and sphagnum-dominated bogs within the Glacial Lake Agassiz Peatlands (GLAP) of northern Minnesota. Surprisingly, microbes appear to initially use similar enzymatic pathways to degrade DON and DOC, often with little release of nitrogen. Figure 1. Isolated 0.30 m/z window at nominal mass 432 from negative-ion APPI FT-ICR mass spectrum of DOM from waters draining an agricultural area in South Florida. Peaks marked contain nitrogen.

  8. How appetizing is the dissolved organic matter (DOM) trees lose during rainfall?

    Science.gov (United States)

    Howard, D.; Van Stan, J. T., II; Whitetree, A.; Zhu, L.; Stubbins, A.

    2017-12-01

    Dissolved organic carbon (DOC) is the chemical backbone of dissolved organic matter (DOM), which is important because it drives many processes in soils and waterways. Current DOC work has paid little attention to interactions between rain and plant canopies, where rainfall is partitioned into throughfall and stemflow. Even less DOC research has investigated the effect of arboreal epiphytes on throughfall and stemflow DOC. The purpose of this study is twofold: (1) assess the degree and timing of DOC consumption by microbial communities (biolability) in throughfall and stemflow, and (2) determine whether the presence of arboreal epiphytes in the canopy affect DOC biolability. Biolability of stemflow and throughfall DOC from Juniperus virginiana (cedar) was determined by incubating samples for 14 days. Throughfall and stemflow DOC was highly biolabile with DOC concentrations decreasing by 30-60%. Throughfall DOC was more biolabile than stemflow DOC. DOC in both throughfall and stemflow from epiphyte-covered cedars was less biolabile than DOC from trees without epiphytes. The high biolability of tree-derived DOC indicates that its supply provides carbon substrates to the microbial community at the forest floor, in soils and the rhizosphere. Epiphytes appear to be important in determining the biolability of DOC and therefore the size of this carbon subsidy to the soil ecosystem.

  9. Will enhanced turbulence in inland waters result in elevated production of autochthonous dissolved organic matter?

    Science.gov (United States)

    Zhou, Yongqiang; Zhou, Jian; Jeppesen, Erik; Zhang, Yunlin; Qin, Boqiang; Shi, Kun; Tang, Xiangming; Han, Xiaoxia

    2016-02-01

    Biological activity in lakes is strongly influenced by hydrodynamic conditions, not least turbulence intensity; which increases the encounter rate between plankter and nutrient patches. To investigate whether enhanced turbulence in shallow and eutrophic lakes may result in elevated biological production of autochthonous chromophoric dissolved organic matter (CDOM), a combination of field campaigns and mesocosm experiments was used. Parallel factor analysis identified seven components: four protein-like, one microbial humic-like and two terrestrial humic-like components. During our field campaigns, elevated production of autochthonous CDOM was recorded in open water with higher wind speed and wave height than in inner bays, implying that elevated turbulence resulted in increased production of autochthonous CDOM. Confirming the field campaign results, in the mesocosm experiment enhanced turbulence resulted in a remarkably higher microbial humic-like C1 and tryptophan-like C3 (pCDOM. This is consistent with the significantly higher mean concentrations of chlorophyll-a (Chl-a) and dissolved organic carbon (DOC) and the enhanced phytoplanktonic alkaline phosphatase activity (PAPA) recorded in the experimental turbulence groups than in the control group (pCDOM samples further suggested their probable autochthonous origin. Our results have implications for the understanding of CDOM cycling in shallow aquatic ecosystems influenced by wind-induced waves, in which the enhanced turbulence associated with extreme weather conditions may be further stimulated by the predicted global climate change. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. [Spectral characteristics variations of chromophoric dissolved organic matter during growth of filamentous green macroalgae].

    Science.gov (United States)

    Jiang, De-gang; Huang, Qing-hui; Li, Jian-hua

    2010-07-01

    As an important component of dissolved organic matter (DOM), chromophoric dissolved organic matter (CDOM) plays a central role in the global biogeochemical carbon cycle. Macroalgae are essential producers in aquatic ecosystems. They can release a considerable part of photosynthetic products as CDOM. So changes in optical properties of CDOM are studied on filamentous green macroalgae-Chadophorasle found in tidal flats of a brackish Lake Beihu in natural field condition by using spectrometry. Humic-like fluorescence peaks and protein-like fluorescence peaks detected by fluorescence excitation-emission matrix spectrum (EEMS) change little in control experiment but increase dramatically in incubation experiment. Applying parallel factor analysis (PARAFAC) together with fluorescence excitation-emission matrix can get four components of CDOM (C1, C2, C3 and C4) which are relative to humic-like fluorescence peak A(C), M and protein-like fluorescence peak B, T respectively. In incubation experiment four components increase by 211.5%, 255.8%, 75.3% and 129.3% respectively while in control experiment components have little changes except C1 decreasing by 34.3%. Absorption coefficient alpha (355) increases by 92.9% and has positive significant correlation (P CDOM molecular weight and composition, M and S values in incubation experiment are smaller than in control experiment, which illustrate that aromatic and macromolecular CDOM is produced in growth of Chadophorasle. All results indicate that growth of Chadophorasle can change the content and composition of CDOM.

  11. Dissolved organic matter in the Florida everglades: Implications for ecosystem restoration

    Science.gov (United States)

    Aiken, G.R.; Gilmour, C.C.; Krabbenhoft, D.P.; Orem, W.

    2011-01-01

    Dissolved organic matter (DOM) in the Florida Everglades controls a number of environmental processes important for ecosystem function including the absorption of light, mineral dissolution/precipitation, transport of hydrophobic compounds (e.g., pesticides), and the transport and reactivity of metals, such as mercury. Proposed attempts to return the Everglades to more natural flow conditions will result in changes to the present transport of DOM from the Everglades Agricultural Area and the northern conservation areas to Florida Bay. In part, the restoration plan calls for increasing water flow throughout the Everglades by removing some of the manmade barriers to flow in place today. The land- and water-use practices associated with the plan will likely result in changes in the quality, quantity, and reactivity of DOM throughout the greater Everglades ecosystem. The authors discuss the factors controlling DOM concentrations and chemistry, present distribution of DOM throughout the Everglades, the potential effects of DOM on key water-quality issues, and the potential utility of dissolved organic matter as an indicator of success of restoration efforts. Copyright ?? 2011 Taylor & Francis Group, LLC.

  12. Selection of magnetic anion exchange resins for the removal of dissolved organic and inorganic matters.

    Science.gov (United States)

    Wang, Qiongjie; Li, Aimin; Wang, Jinnan; Shuang, Chengdong

    2012-01-01

    Four magnetic anion exchange resins (MAERs) were used as adsorbents to purify drinking water. The effect of water quality (pH, temperature, ionic strength, etc.) on the performance of MAER for the removal of dissolved organic matter (DOM) was also investigated. Among the four studied MAERs, the strong base resin named NDMP-1 with high water content and enhanced exchange capacity exhibited the highest removal rate of dissolved organic carbon (DOC) (48.9% removal rate) and UV-absorbing substances (82.4% removal rate) with a resin dose of 10 mL/L after 30 min of contact time. The MAERs could also effectively remove inorganic matter such as sulfate, nitrate and fluoride. Because of the higher specific UV absorbance (SUVA) value, the DOM in the raw water was found to be removed more effectively than that in the clarified water by NDMP resin. The temperature showed a weak influence on the removal of DOC from 6 to 26 degrees C, while a relatively strong one at 36 degrees C. The removal of DOM by NDMP was also affected to some extent by the pH value. Moreover, increasing the sulfate concentration in the raw water could decrease the removal rates of DOC and UV-absorbing substances.

  13. Impact of dissolved organic matter on bioavailability of chlorotoluron to wheat

    Energy Technology Data Exchange (ETDEWEB)

    Song Ninghui [Department of Applied Chemistry, College of Sciences, Nanjing Agricultural University, Weigang No. 1, Building of Chemistry, Nanjing 210095 (China); Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095 (China); Zhang Shuang; Hong Min [Department of Applied Chemistry, College of Sciences, Nanjing Agricultural University, Weigang No. 1, Building of Chemistry, Nanjing 210095 (China); Yang Hong, E-mail: hongyang@njau.edu.c [Department of Applied Chemistry, College of Sciences, Nanjing Agricultural University, Weigang No. 1, Building of Chemistry, Nanjing 210095 (China); Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095 (China)

    2010-03-15

    Chlorotoluron (Chl) is a phenylurea herbicide and is widely used for controlling weeds. While it has brought great benefits to crop production, it has also resulted in contamination to ecosystem. In this study, we investigated accumulation of chlorotoluron (Chl) and biological responses of wheat plants as affected by dissolved organic matter (DOM). Wheat seedlings grown under 10 mg kg{sup -1} Chl for 4 d showed a low level of chlorophyll accumulation and damage to plasma membrane. The growth was inhibited by exposure of chlorotoluron. Treatment with 50 mg DOC kg{sup -1} DOM derived either from sludge (DOM-SL) or straw (DOM-ST) attenuated the chlorotoluron toxicity to plants. Both DOMs decreased activities of catalase, peroxidase and superoxide dismutase in Chl-treated seedlings. However, an increased glutathione S-transferases activity was observed under the same condition. Wheat plants treated with Chl in the presence of DOM accumulated less Chl than those treated with Chl alone. Moreover, in the presence of DOM, bioconcentration factor (BCF) decreased whereas translocation factors increased. Analyses with FT-IR spectra confirmed the regulatory role of DOMs in reducing Chl accumulation in wheat. - Dissolved organic matter (DOM) as a soil amendment can reduce herbicide accumulation in crops.

  14. The river as a chemostat: fresh perspectives on dissolved organic matter flowing down the river continuum

    Science.gov (United States)

    Creed, Irena F.; McKnight, Diane M.; Pellerin, Brian; Green, Mark B.; Bergamaschi, Brian; Aiken, George R.; Burns, Douglas A.; Findlay, Stuart E G; Shanley, James B.; Striegl, Robert G.; Aulenbach, Brent T.; Clow, David W.; Laudon, Hjalmar; McGlynn, Brian L.; McGuire, Kevin J.; Smith, Richard A.; Stackpoole, Sarah M.

    2015-01-01

    A better understanding is needed of how hydrological and biogeochemical processes control dissolved organic carbon (DOC) concentrations and dissolved organic matter (DOM) composition from headwaters downstream to large rivers. We examined a large DOM dataset from the National Water Information System of the US Geological Survey, which represents approximately 100 000 measurements of DOC concentration and DOM composition at many sites along rivers across the United States. Application of quantile regression revealed a tendency towards downstream spatial and temporal homogenization of DOC concentrations and a shift from dominance of aromatic DOM in headwaters to more aliphatic DOM downstream. The DOC concentration–discharge (C-Q) relationships at each site revealed a downstream tendency towards a slope of zero. We propose that despite complexities in river networks that have driven many revisions to the River Continuum Concept, rivers show a tendency towards chemostasis (C-Q slope of zero) because of a downstream shift from a dominance of hydrologic drivers that connect terrestrial DOM sources to streams in the headwaters towards a dominance of instream and near-stream biogeochemical processes that result in preferential losses of aromatic DOM and preferential gains of aliphatic DOM.

  15. A study on the photo catalytic decomposition reactions of organics dissolved in water (II)

    Energy Technology Data Exchange (ETDEWEB)

    Sung, K.W.; Na, J. W.; Cho, Y. H.; Chung, H. H

    2000-01-01

    Experiments on aqueous TiO{sub 2} photo catalytic reaction of nitrogen containing organic compounds such as ethylamine, phenylhydrazine, pyridine, urea and EDTA were carried out. Based on the values calculated for the distribution of ionic species and atomic charge, the characteristics of their photo catalytic decomposition were estimated. It was shown that the decomposition characteristics was linearly proportional to nitrogen atomic charge value. On the other hand, the effects of aqueous pH, oxygen content and concentration on the TiO{sub 2} photo catalytic characteristics of EDTA, EDTA-Cu(II) and EDTA-Fe(III) were experimentally investigated. All EDTA systems were decomposed better in the pH range of 2.5-3.0 and with more dissolved oxygen. These results could be applied to construction of a process for removal of organic impurities dissolved in a source of system water, or for treatment of EDTA-containing liquid waste produced by a chemical cleaning in the domestic NPPs. (author)

  16. A study on the photocatalytic decomposition reactions of organics dissolved in water (II)

    Energy Technology Data Exchange (ETDEWEB)

    Sung, K. W.; Na, J. W.; Cho, Y. H.; Chung, H. H

    2001-01-01

    Experiments on aqueous TiO{sup 2} photocatalytic reaction characteristics of 4 nitrogen-containing and 12 aromatic organic compounds were carried out. Based on the values calculated for the distribution of ionic species and atomic charge, the characteristics of their photocatalytic decomposition were estimated. It was shown that the dependence of decomposition of the N-containing compounds were linearly proportional to their nitrogen atomic charge values, while that of the aromatic compounds were inversely proportional. The effects of aqueous pH, oxygen content and concentration on the TiO{sup 2} photocatalytic characteristics of EDTA-Cu(II) and EDTA-Fe(III) were experimentally investigated. All EDTA systems were decomposed better in the pH range of 2.5{approx}3.0 and with more dissolved oxygen. These results could be applied to a unit process for removal of organic impurities dissolved in a source water of the system water, and for treatment of EDTA-containing liquid waste produced by chemical cleaning process in the domestic NPPs.

  17. Higher molecular weight dissolved organic nitrogen turnover as affected by soil management history

    DEFF Research Database (Denmark)

    Lønne Enggrob, Kirsten

    of different management histories on the turnover of high Mw DON. Further, we distinguished between several classes of high Mw DON, i.e., 1-10 kDa and >10 kDa. 3. Materials and methods With the use of micro-lysimeters, the turnover of triple-labeled (15N, 14C and 13C) high Mw DON was studied in a sandy soil......High molecular weight dissolved organic nitrogen turnover as affected by soil management history *Kirsten Lønne Enggrob,1 Lars Elsgaard,1 and Jim Rasmussen1 1Aarhus University, Dept. of Agroecology, Foulum, Denmark 1. Introduction Dissolved organic nitrogen (DON) play an important role in soil N...... are presented for 14CO2 evolution during 14 days of incubation. 4. Results and conclusion Results showed that the turnover rate of high Mw DON was dependent on both the Mw size of DON and on the soil liming history. Evidence showing where in the DON Mw sizes the bottleneck lies will be presented....

  18. In-situ production of humic-like fluorescent dissolved organic matter during Cochlodinium polykrikoides blooms

    Science.gov (United States)

    Kwon, Hyeong Kyu; Kim, Guebuem; Lim, Weol Ae; Park, Jong Woo

    2018-04-01

    We investigated phytoplankton pigments, dissolved organic carbon (DOC), and fluorescent dissolved organic matter (FDOM) during the summers of 2013 and 2016 in the coastal area of Tongyeong, Korea, where Cochlodinium polykrikoides blooms often occur. The density of red tides was evaluated using a dinoflagellate pigment, peridinin. The concentrations of peridinin and DOC in the patch areas were 15- and 4-fold higher than those in the non-patch areas. The parallel factor analysis (PARAFAC) model identified one protein-like FDOM (FDOMT) and two humic-like FDOM, classically classified as marine FDOM (FDOMM) and terrestrial FDOM (FDOMC). The concentrations of FDOMT in the patch areas were 5-fold higher than those in the non-patch areas, likely associated with biological production. In general, FDOMM and FDOMC are known to be dependent exclusively on salinity in any surface waters of the coastal ocean. However, in this study, we observed strikingly enhanced FDOMC concentration over that expected from the salinity mixing, whereas FDOMM increases were not clear. These FDOMC concentrations showed a significant positive correlation against peridinin, indicating that the production of FDOMC is associated with the red tide blooms. Our results suggest that FDOMC can be naturally enriched by some phytoplankton species, without FDOMM enrichment. Such naturally produced FDOM may play a critical role in biological production as well as biogeochemical cycle in red tide regions.

  19. Influence of nitrogen and phosphorus sources on mycorrhizal lettuces under organic farming

    Science.gov (United States)

    Scotti, Riccardo; Seguel, Alex; Cornejo, Pablo; Rao, Maria A.; Borie, Fernando

    2010-05-01

    Arbuscular mycorrhizal fungi (AMF) develop symbiotic associations with plants roots. These associations are very common in the natural environment and can provide a range of benefits to the host plant. AMF improve nutrition, enhance resistance to soil-borne pests and disease, increase resistance to drought and tolerance to heavy metals, and contribute to a better soil structure. However, agricultural intensive managements, such as the use of mineral fertilizes, pesticides, mouldboard tillage, monocultures and use of non-mycorrhizal crops, are detrimental to AMF. As a consequence, agroecosystems are impoverished in AMF and may not provide the full range of benefits to the crop. Organic farming systems may be less unfavourable to AMF because they exclude the use of water-soluble fertilisers and most pesticides, and generally they plan diverse crop rotations. The AMF develop the most common type of symbiosis in nature: about 90% of the plants are mycorrhizal and many agricultural crops are mycorrhizal. One of more mycorrhizal crops is lettuce, that is very widespread in intensive agricultural under greenhouse. Therefore, cultivated lettuce is know to be responsive to mycorrhizal colonization which can reach 80% of root length and contribute to phosphorus and nitrogen absorption by this plant specie. For this work four different lettuce cultivars (Romana, Milanesa, Grande Lagos and Escarola) were used to study mycorrhization under organic agricultural system, supplying compost from agricultural waste (1 kg m-2) as background fertilization for all plots, red guano as phosphorus source (75 U ha-1 and 150 U ha-1 of P2O5), lupine flour as nitrogen source (75 and 150 U/ha of N) and a combination of both. Lettuce plants were cultivated under greenhouse and after two months of growing, plants were harvested and dried and fresh weight of lettuce roots and shoots were evaluated. The number of spores, percentage of colonization, total mycelium and glomalin content were also

  20. 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

  1. Global trends in the fluorescence characteristics and distribution of marine dissolved organic matter

    DEFF Research Database (Denmark)

    Jørgensen, Linda; Stedmon, Colin; Kragh, Theis

    2011-01-01

    . These observations imply a link to dark ocean microbial remineralization and indicate that the major source of humic-like compounds is microbial turnover of organic matter. The results of the present study show that the distribution of the humic-like DOM fractions is a balance between supply from continental run off......A fraction of dissolved organic matter (DOM) is able to fluoresce. This ability has been used in the present study to investigate the characteristics and distribution of different DOM fractions. A unique global dataset revealed seven different fluorescent fractions of DOM: two humic-like, four...... in the surface layer indicate the quantitative importance of photochemical degradation as a sink of the humic-like compounds. In the dark ocean (below 200 m), significant linear relationships between humic-like DOM fluorescence and microbial activity (apparent oxygen utilization, NO3- and PO43-) were found...

  2. The Role of Refractory Dissolved Organic Matter in Ocean Carbon Sequestration

    DEFF Research Database (Denmark)

    Jørgensen, Linda

    The ocean assimilates a large amount of atmospheric CO2 and is potentially a buffer for climate change. A fraction of the assimilated CO2 is incorporated into algal biomass and further converted into refractory dissolved organic matter (DOM). Carbon bound in refractory DOM has the potential...... studies the prokaryotic production and degradation of oceanic refractory DOM and discusses the reasons for the persistent nature of this large DOM fraction. The first two papers investigate the microbial carbon pump, i.e. prokaryotic transfor-mation of organic carbon into refractory DOM. The results show...... DOM compounds in the ocean are rare—possibly too rare to sustain viable uptake and assimilation. Hence, the dilute concentration of individual compounds is a possible explanation for the apparent refractory nature of most DOM in the ocean. Understanding the mechanisms that control the quality...

  3. [Roles of soil dissolved organic carbon in carbon cycling of terrestrial ecosystems: a review].

    Science.gov (United States)

    Li, Ling; Qiu, Shao-Jun; Liu, Jing-Tao; Liu, Qing; Lu, Zhao-Hua

    2012-05-01

    Soil dissolved organic carbon (DOC) is an active fraction of soil organic carbon pool, playing an important role in the carbon cycling of terrestrial ecosystems. In view of the importance of the carbon cycling, this paper summarized the roles of soil DOC in the soil carbon sequestration and greenhouse gases emission, and in considering of our present ecological and environmental problems such as soil acidification and climate warming, discussed the effects of soil properties, environmental factors, and human activities on the soil DOC as well as the response mechanisms of the DOC. This review could be helpful to the further understanding of the importance of soil DOC in the carbon cycling of terrestrial ecosystems and the reduction of greenhouse gases emission.

  4. Role of organic phosphorus in sediment in a shallow eutrophic lake

    Science.gov (United States)

    Shinohara, Ryuichiro; Hiroki, Mikiya; Kohzu, Ayato; Imai, Akio; Inoue, Tetsunori; Furusato, Eiichi; Komatsu, Kazuhiro; Satou, Takayuki; Tomioka, Noriko; Shimotori, Koichi; Miura, Shingo

    2017-08-01

    We tested the hypothesis that mineralization of molybdenum unreactive phosphorus (MUP) in pore water is the major pathway for the changes in the concentration of molybdenum-reactive P (MRP) in pore water and inorganic P in sediment particles. The concentration of inorganic P in the sediment particles increased from December to April in Lake Kasumigaura, whereas concentrations of organic P in the sediment particles and MUP in pore water decreased. These results suggest that MUP mineralization plays a key role as the source of MRP, whereas desorption of inorganic P from the sediment particles into the pore water is a minor process. One-dimensional numerical simulation of sediment particles and the pore water supported the hypothesis. Diffusive flux of MUP was small in pore water, even in near-surface layers, so mineralization was the dominant process for changing the MUP concentration in the pore water. For MRP, diffusion was the dominant process in the surface layer, whereas adsorption onto the sediment was the dominant process in deeper layers. Researchers usually ignore organic P in the sediment, but organic P in sediment particles and the pore water is a key source of inorganic P in the sediment particles and pore water; our results suggest that in Lake Kasumigaura, organic P in the sediment is an important source, even at depths more than 1 cm below the sediment surface. In contrast, the large molecular size of MUP in pore water hampers diffusion of MUP from the sediment into the overlying water.

  5. Rhizosphere Environment and Labile Phosphorus Release from Organic Waste-Amended Soils.

    Science.gov (United States)

    Dao, Thanh H.

    2015-04-01

    Crop residues and biofertilizers are primary sources of nutrients for organic crop production. However, soils treated with large amounts of nutrient-enriched manure have elevated phosphorus (P) levels in regions of intensive animal agriculture. Surpluses occurred in these amended soils, resulting in large pools of exchangeable inorganic P (Pi) and enzyme-labile organic P (Po) that averaging 30.9 and 68.2 mg kg-1, respectively. Organic acids produced during crop residue decomposition can promote the complexation of counter-ions and decouple and release unbound Pi from metal and alkali metal phosphates. Animal manure and cover crop residues also contain large amounts of soluble organic matter, and likely generate similar ligands. However, a high degree of heterogeneity in P spatial distribution in such amended fields, arising from variances in substrate physical forms ranging from slurries to dried solids, composition, and diverse application methods and equipment. Distinct clusters of Pi and Po were observed, where accumulation of the latter forms was associated with high soil microbial biomass C and reduced phosphomonoesterases' activity. Accurate estimates of plant requirements and lability of soil P pools, and real-time plant and soil P sensing systems are critical considerations to optimally manage manure-derived nutrients in crop production systems. An in situ X-ray fluorescence-based approach to sensing canopy and soil XRFS-P was developed to improve the yield-soil P relationship for optimal nutrient recommendations in addition to allowing in-the-field verification of foliar P status.

  6. Characterizing Dissolved Organic Matter and Metabolites in an Actively Serpentinizing Ophiolite Using Global Metabolomics Techniques

    Science.gov (United States)

    Seyler, L. M.; Rempfert, K. R.; Kraus, E. A.; Spear, J. R.; Templeton, A. S.; Schrenk, M. O.

    2017-12-01

    Environmental metabolomics is an emerging approach used to study ecosystem properties. Through bioinformatic comparisons to metagenomic data sets, metabolomics can be used to study microbial adaptations and responses to varying environmental conditions. Since the techniques are highly parallel to organic geochemistry approaches, metabolomics can also provide insight into biogeochemical processes. These analyses are a reflection of metabolic potential and intersection with other organisms and environmental components. Here, we used an untargeted metabolomics approach to characterize dissolved organic carbon and aqueous metabolites from groundwater obtained from an actively serpentinizing habitat. Serpentinites are known to support microbial communities that feed off of the products of serpentinization (such as methane and H2 gas), while adapted to harsh environmental conditions such as high pH and low DIC availability. However, the biochemistry of microbial populations that inhabit these environments are understudied and are complicated by overlapping biotic and abiotic processes. The aim of this study was to identify potential sources of carbon in an environment that is depleted of soluble inorganic carbon, and to characterize the flow of metabolites and describe overlapping biogenic and abiogenic processes impacting carbon cycling in serpentinizing rocks. We applied untargeted metabolomics techniques to groundwater taken from a series of wells drilled into the Semail Ophiolite in Oman.. Samples were analyzed via quadrupole time-of-flight liquid chromatography tandem mass spectrometry (QToF-LC/MS/MS). Metabolomes and metagenomic data were imported into Progenesis QI software for statistical analysis and correlation, and metabolic networks constructed using the Genome-Linked Application for Metabolic Maps (GLAMM), a web interface tool. Further multivariate statistical analyses and quality control was performed using EZinfo. Pools of dissolved organic carbon could

  7. Nutrient and dissolved organic carbon removal from natural waters using industrial by-products.

    Science.gov (United States)

    Wendling, Laura A; Douglas, Grant B; Coleman, Shandel; Yuan, Zheng

    2013-01-01

    Attenuation of excess nutrients in wastewater and stormwater is required to safeguard aquatic ecosystems. The use of low-cost, mineral-based industrial by-products with high Ca, Mg, Fe or Al content as a solid phase in constructed wetlands potentially offers a cost-effective wastewater treatment option in areas without centralised water treatment facilities. Our objective was to investigate use of water treatment residuals (WTRs), coal fly ash (CFA), and granular activated carbon (GAC) from biomass combustion in in-situ water treatment schemes to manage dissolved organic carbon (DOC) and nutrients. Both CaO- and CaCO(3)-based WTRs effectively attenuated inorganic N species but exhibited little capacity for organic N removal. The CaO-based WTR demonstrated effective attenuation of DOC and P in column trials, and a high capacity for P sorption in batch experiments. Granular activated carbon proved effective for DOC and dissolved organic nitrogen (DON) removal in column trials, but was ineffective for P attenuation. Only CFA demonstrated effective removal of a broad suite of inorganic and organic nutrients and DOC; however, Se concentrations in column effluents exceeded Australian and New Zealand water quality guideline values. Water treated by filtering through the CaO-based WTR exhibited nutrient ratios characteristic of potential P-limitation with no potential N- or Si-limitation respective to growth of aquatic biota, indicating that treatment of nutrient-rich water using the CaO-based WTR may result in conditions less favourable for cyanobacterial growth and more favourable for growth of diatoms. Results show that selected industrial by-products may mitigate eutrophication through targeted use in nutrient intervention schemes. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

  8. Substoichiometric extraction of phosphorus

    International Nuclear Information System (INIS)

    Shigematsu, T.; Kudo, K.

    1981-01-01

    A study of the substoichiometric extraction of phosphorus is described. Phosphorus was extracted in the form of ternary compounds such as ammonium phosphomolybdate, 8-hydroxyquinolinium phosphomolybdate, tetraphenylarsonium phosphomolybdate and tri-n-octylamine phosphomolybdate. Consequently, phosphorus was extracted substoichiometrically by the addition of a substoichiometric amount of molybdenum for the four phosphomolybdate compounds. On the other hand, phosphorus could be separated substoichiometrically with a substoichiometric amount of tetraphenylarsonium chloride or tri-n-octylamine. Stoichiometric ratios of these ternary compounds obtained substoichiometrically were 1:12:3 for phosphorus, molybdenum and organic reagent. The applicability of these compounds to phosphorus determination is also discussed. (author)

  9. Colored dissolved organic matter in shallow estuaries: relationships between carbon sources and light attenuation

    Science.gov (United States)

    Oestreich, W. K.; Ganju, N. K.; Pohlman, J. W.; Suttles, S. E.

    2016-02-01

    Light availability is of primary importance to the ecological function of shallow estuaries. For example, benthic primary production by submerged aquatic vegetation is contingent upon light penetration to the seabed. A major component that attenuates light in estuaries is colored dissolved organic matter (CDOM). CDOM is often measured via a proxy, fluorescing dissolved organic matter (fDOM), due to the ease of in situ fDOM sensor measurements. Fluorescence must be converted to CDOM absorbance for use in light attenuation calculations. However, this CDOM-fDOM relationship varies among and within estuaries. We quantified the variability in this relationship within three estuaries along the mid-Atlantic margin of the eastern United States: West Falmouth Harbor (MA), Barnegat Bay (NJ), and Chincoteague Bay (MD/VA). Land use surrounding these estuaries ranges from urban to developed, with varying sources of nutrients and organic matter. Measurements of fDOM (excitation and emission wavelengths of 365 nm (±5 nm) and 460 nm (±40 nm), respectively) and CDOM absorbance were taken along a terrestrial-to-marine gradient in all three estuaries. The ratio of the absorption coefficient at 340 nm (m-1) to fDOM (QSU) was higher in West Falmouth Harbor (1.22) than in Barnegat Bay (0.22) and Chincoteague Bay (0.17). The CDOM : fDOM absorption ratio was variable between sites within West Falmouth Harbor and Barnegat Bay, but consistent between sites within Chincoteague Bay. Stable carbon isotope analysis for constraining the source of dissolved organic matter (DOM) in West Falmouth Harbor and Barnegat Bay yielded δ13C values ranging from -19.7 to -26.1 ‰ and -20.8 to -26.7 ‰, respectively. Concentration and stable carbon isotope mixing models of DOC (dissolved organic carbon) indicate a contribution of 13C-enriched DOC in the estuaries. The most likely source of 13C-enriched DOC for the systems we investigated is Spartina cordgrass. Comparison of DOC source to CDOM : f

  10. Colored dissolved organic matter in shallow estuaries: relationships between carbon sources and light attenuation

    Science.gov (United States)

    Oestreich, W.K.; Ganju, Neil K.; Pohlman, John; Suttles, Steven E.

    2016-01-01

    Light availability is of primary importance to the ecological function of shallow estuaries. For example, benthic primary production by submerged aquatic vegetation is contingent upon light penetration to the seabed. A major component that attenuates light in estuaries is colored dissolved organic matter (CDOM). CDOM is often measured via a proxy, fluorescing dissolved organic matter (fDOM), due to the ease of in situ fDOM sensor measurements. Fluorescence must be converted to CDOM absorbance for use in light attenuation calculations. However, this CDOM–fDOM relationship varies among and within estuaries. We quantified the variability in this relationship within three estuaries along the mid-Atlantic margin of the eastern United States: West Falmouth Harbor (MA), Barnegat Bay (NJ), and Chincoteague Bay (MD/VA). Land use surrounding these estuaries ranges from urban to developed, with varying sources of nutrients and organic matter. Measurements of fDOM (excitation and emission wavelengths of 365 nm (±5 nm) and 460 nm (±40 nm), respectively) and CDOM absorbance were taken along a terrestrial-to-marine gradient in all three estuaries. The ratio of the absorption coefficient at 340 nm (m−1) to fDOM (QSU) was higher in West Falmouth Harbor (1.22) than in Barnegat Bay (0.22) and Chincoteague Bay (0.17). The CDOM : fDOM absorption ratio was variable between sites within West Falmouth Harbor and Barnegat Bay, but consistent between sites within Chincoteague Bay. Stable carbon isotope analysis for constraining the source of dissolved organic matter (DOM) in West Falmouth Harbor and Barnegat Bay yielded δ13C values ranging from −19.7 to −26.1 ‰ and −20.8 to −26.7 ‰, respectively. Concentration and stable carbon isotope mixing models of DOC (dissolved organic carbon) indicate a contribution of 13C-enriched DOC in the estuaries. The most likely source of 13C-enriched DOC for the systems we investigated is Spartina cordgrass. Comparison of

  11. 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...

  12. Molecular insights into the microbial formation of marine dissolved organic matter: recalcitrant or labile?

    Science.gov (United States)

    Koch, B. P.; Kattner, G.; Witt, M.; Passow, U.

    2014-08-01

    The degradation of marine dissolved organic matter (DOM) is an important control variable in the global carbon cycle. For our understanding of the kinetics of organic matter cycling in the ocean, it is crucial to achieve a mechanistic and molecular understanding of its transformation processes. A long-term microbial experiment was performed to follow the production of non-labile DOM by marine bacteria. Two different glucose concentrations and dissolved algal exudates were used as substrates. We monitored the bacterial abundance, concentrations of dissolved and particulate organic carbon (DOC, POC), nutrients, amino acids and transparent exopolymer particles (TEP) for 2 years. The molecular characterization of extracted DOM was performed by ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) after 70 days and after ∼2 years of incubation. Although glucose quickly degraded, a non-labile DOC background (5-9% of the initial DOC) was generated in the glucose incubations. Only 20% of the organic carbon from the algal exudate degraded within the 2 years of incubation. The degradation rates for the non-labile DOC background in the different treatments varied between 1 and 11 μmol DOC L-1 year-1. Transparent exopolymer particles, which are released by microorganisms, were produced during glucose degradation but decreased back to half of the maximum concentration within less than 3 weeks (degradation rate: 25 μg xanthan gum equivalents L-1 d-1) and were below detection in all treatments after 2 years. Additional glucose was added after 2 years to test whether labile substrate can promote the degradation of background DOC (co-metabolism; priming effect). A priming effect was not observed but the glucose addition led to a slight increase of background DOC. The molecular analysis demonstrated that DOM generated during glucose degradation differed appreciably from DOM transformed during the degradation of the algal exudates. Our

  13. Dissolved organic and inorganic matter in bulk deposition of a coastal urban area: an integrated approach.

    Science.gov (United States)

    Santos, Patrícia S M; Santos, Eduarda B H; Duarte, Armando C

    2014-12-01

    Bulk deposition can remove atmospheric organic and inorganic pollutants that may be associated with gaseous, liquid or particulate phases. To the best of our knowledge, few studies have been carried out, which simultaneously analyse the presence of organic and inorganic fractions in rainwater. In the present work, the complementarity of organic and inorganic data was assessed, through crossing data of some organic [DOC (dissolved organic carbon), absorbance at 250 nm (UV250nm), integrated fluorescence] and inorganic [H(+), NH4(+), NO3(-), non sea salt sulphate (NSS-SO4(2-))] parameters measured in bulk deposition in the coastal urban area of Aveiro. The organic and inorganic parameters analysed were positively correlated (pCDOM) came from anthropogenic sources. Furthermore, the inverse correlations observed for the organic and inorganic parameters with the precipitation amount suggest that organic and inorganic fractions were incorporated into the rainwater partially by below-cloud scavenging of airborne particulate matter. This is in accordance with the high values of DOC and NO3(-) found in samples associated with marine air masses, which were linked in part to the contribution of local emissions from vehicular traffic. DOC of bulk deposition was the predominant constituent when compared with the constituents H(+), NH4(+), NO3(-) and NSS-SO4(2-), and consequently bulk deposition flux was also highest for DOC, highlighting the importance of DOC and of anthropogenic ions being simultaneously removed from the atmosphere by bulk deposition. However, it was verified that the contribution of anthropogenic sources to the DOC of bulk deposition may be different for distinct urban areas. Thus, it is recommended that organic and inorganic fractions of bulk deposition are studied together. Copyright © 2014. Published by Elsevier Ltd.

  14. 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.

  15. Dissolved inorganic carbon and organic carbon in mires in the Forsmark area. A pilot study

    Energy Technology Data Exchange (ETDEWEB)

    Loefgren, Anders [EcoAnalytica, Haegersten (Sweden)

    2011-12-15

    Dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) are the large dissolved carbon pools in mires. They are both related to a number of factors such as groundwater flow, minerogenic influence and peat properties, which all are more or less related to peatland development stage. In a scenario of a release of radionuclides from an underground repository containing radioactive material, behaviour of these pools during the mire ontogeny will be of importance for the understanding of how C-14 will constitute a potential risk to humans and non-human biota. In this pilot study, DIC and DOC concentrations were investigated for three mires representing a potential sequence of peatland development in a coastal area at Forsmark in central Sweden characterized by land upheaval, a flat topography and calcareous content in the soil. The mires where chosen based on difference in height above the sea level, covering approximate 1000 years, and characteristics based on their vegetation. Water samples were collected during August from all three mires at two different depths in the anoxic layer of the mires, by extracting water from peat obtained with a peat corer. DIC concentrations where related to the age of the mires, with the lowest concentrations in the highest located mire. There was a positive correlation between pH and DIC, where the higher DIC concentrations were found in the 'richer' fens. DIC concentrations were also positively related to the conductivity within and between the mires, where conductivity would be a proxy for the dominating cation Ca{sup 2+} associated to the calcareous-influenced groundwater. DOC concentrations were highest in the oldest mire, but were similar in the younger mires. No patterns were found between DIC and DOC, and the peat bulk density. The report ends with suggestions on how a continued study could be improved.

  16. Dissolved inorganic carbon and organic carbon in mires in the Forsmark area. A pilot study

    International Nuclear Information System (INIS)

    Loefgren, Anders

    2011-12-01

    Dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) are the large dissolved carbon pools in mires. They are both related to a number of factors such as groundwater flow, minerogenic influence and peat properties, which all are more or less related to peatland development stage. In a scenario of a release of radionuclides from an underground repository containing radioactive material, behaviour of these pools during the mire ontogeny will be of importance for the understanding of how C-14 will constitute a potential risk to humans and non-human biota. In this pilot study, DIC and DOC concentrations were investigated for three mires representing a potential sequence of peatland development in a coastal area at Forsmark in central Sweden characterized by land upheaval, a flat topography and calcareous content in the soil. The mires where chosen based on difference in height above the sea level, covering approximate 1000 years, and characteristics based on their vegetation. Water samples were collected during August from all three mires at two different depths in the anoxic layer of the mires, by extracting water from peat obtained with a peat corer. DIC concentrations where related to the age of the mires, with the lowest concentrations in the highest located mire. There was a positive correlation between pH and DIC, where the higher DIC concentrations were found in the 'richer' fens. DIC concentrations were also positively related to the conductivity within and between the mires, where conductivity would be a proxy for the dominating cation Ca 2+ associated to the calcareous-influenced groundwater. DOC concentrations were highest in the oldest mire, but were similar in the younger mires. No patterns were found between DIC and DOC, and the peat bulk density. The report ends with suggestions on how a continued study could be improved

  17. Alteration of Chemical Composition of Soil-leached Dissolved Organic Matter under Cryogenic Cycles

    Science.gov (United States)

    Zhang, X.; Bianchi, T. S.; Schuur, E.

    2016-02-01

    Arctic permafrost thawing has drawn great attention because of the large amount of organic carbon (OC) storage in Arctic soils that are susceptible to increasing global temperatures. Due to microbial activities, some of the OC pool is converted in part to greenhouse gases, like CH4 and CO2 gas, which can result in a positive feedback on global warming. In Artic soils, a portion of OC can be mobilized by precipitation, drainage, and groundwater circulation which can in some cases be transported to rivers and eventually the coastal margins. To determine some of the mechanisms associated with the mobilization of OC from soils to aquatic ecosystems, we conducted a series of laboratory soil leaching experiments. Surface soil samples collected from Healy, Alaska were eluted with artificial rain at a constant rate. Leachates were collected over time and analyzed for dissolved organic carbon (DOC) concentrations. Concentrations began from 387-705 mg/L and then dropped to asymptote states to 25-219 mg/L. High-resolution spectroscopy was used to characterize colored dissolved organic matter (CDOM) and CDOM fluorescence intensity also dropped with time. Fluorescence maximum intensity (Fmax) for peak C ranged from 0.7-4.2 RU, with Exmax/Emmax = 310/450 nm. Fmax for peak T ranged from 0.5-3.2 RU, with Exmax/Emmax = 275/325 nm. Peak C: peak T values indicated preferential leaching of humic-like components over protein-like components. After reaching asymptotic levels, samples were stored frozen and then thawed to study the cryogenic impact on OC composition. CDOM intensity and DOC concentration increased after the freeze-thaw cycle. It was likely that cryogenic processes promoted the breakdown of OC and the releases of more DOC from soils. PARAFAC of CDOM excitation and emission matrices (EEMs) will be used to analyze CDOM composition of the soil leachates.

  18. Pre-treatments, characteristics, and biogeochemical dynamics of dissolved organic matter in sediments: A review.

    Science.gov (United States)

    Chen, Meilian; Hur, Jin

    2015-08-01

    Dissolved organic matter (DOM) in sediments, termed here sediment DOM, plays a variety of important roles in global biogeochemical cycling of carbon and nutrients as well as in the fate and transport of xenobiotics. Here we reviewed sediment DOM, including pore waters and water extractable organic matter from inland and coastal sediments, based on recent literature (from 1996 to 2014). Sampling, pre-treatment, and characterization methods for sediment DOM were summarized. The characteristics of sediment DOM have been compared along an inland to coastal ecosystems gradient and also with the overlying DOM in water column to distinguish the unique nature of it. Dissolved organic carbon (DOC) from inland sediment DOM was generally higher than coastal areas, while no notable differences were found for their aromaticity and apparent molecular weight. Fluorescence index (FI) revealed that mixed sources are dominant for inland sediment DOM, but marine end-member prevails for coastal sediment DOM. Many reports showed that sediments operate as a net source of DOC and chromophoric DOM (CDOM) to the water column. Sediment DOM has shown more enrichment of nitrogen- and sulfur-containing compounds in the elemental signature than the overlying DOM. Fluorescent fingerprint investigated by excitation-emission matrix coupled with parallel factor analysis (EEM-PARAFAC) further demonstrated the characteristics of sediment DOM lacking in the photo-oxidized and the intermediate components, which are typically present in the overlying surface water. In addition, the biogeochemical changes in sediment DOM and the subsequent environmental implications were discussed with the focus on the binding and the complexation properties with pollutants. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Non-conservative behavior of fluorescent dissolved organic matter (FDOM) within a subterranean estuary

    Science.gov (United States)

    Suryaputra, I. G. N. A.; Santos, I. R.; Huettel, M.; Burnett, W. C.; Dittmar, T.

    2015-11-01

    The role of submarine groundwater discharge (SGD) in releasing fluorescent dissolved organic matter (FDOM) to the coastal ocean and the possibility of using FDOM as a proxy for dissolved organic carbon (DOC) was investigated in a subterranean estuary in the northeastern Gulf of Mexico (Turkey Point, Florida). FDOM was continuously monitored for three weeks in shallow beach groundwater and in the adjacent coastal ocean. Radon (222Rn) was used as a natural groundwater tracer. FDOM and DOC correlated in groundwater and seawater samples, implying that FDOM may be a proxy of DOC in waters influenced by SGD. A mixing model using salinity as a seawater tracer revealed FDOM production in the high salinity region of the subterranean estuary. This production was probably a result of infiltration and transformation of labile marine organic matter in the beach sediments. The non-conservative FDOM behavior in this subterranean estuary differs from most surface estuaries where FDOM typically behaves conservatively. At the study site, fresh and saline SGD delivered about 1800 mg d-1 of FDOM (quinine equivalents) to the coastal ocean per meter of shoreline. About 11% of this input was related to fresh SGD, while 89% were related to saline SGD resulting from FDOM production within the shallow aquifer. If these fluxes are representative of the Florida Gulf Coast, SGD-derived FDOM fluxes would be equivalent to at least 18% of the potential regional riverine FDOM inputs. To reduce uncertainties related to the scarcity of FDOM data, further investigations of river and groundwater FDOM inputs in Florida and elsewhere are necessary.

  20. Chemical composition and cycling of dissolved organic matter in the Mid-Atlantic Bight

    Science.gov (United States)

    Aluwihare, Lihini I.; Repeta, Daniel J.; Chen, Robert F.

    This study focuses on the chemical characterization of high molecular-weight dissolved organic matter (HMW DOM) isolated from the Middle Atlantic Bight in April 1994 and March 1996. Using proton nuclear magnetic resonance spectroscopy ( 1HNMR) and monosaccharide analysis we compared both spatial and temporal variations in the chemical structure of HMW DOM across this region. Our analyses support the presence of at least two compositionally distinct components to HMW DOM. The major component is acyl polysaccharide (APS), a biopolymer rich in carbohydrates, acetate and lipid, accounting for between 50% and 80% of the total high molecular-weight dissolved organic carbon (HMW DOC) in surface samples. APS is most abundant in fully marine, surface-water samples, and is a product of autochthonous production. Organic matter with spectral properties characteristic of humic substances is the second major component of HMW DOM. Humic substances are most abundant (up to 49% of the total carbon) in samples collected from estuaries, near the coast, and in deep water, suggesting both marine and perhaps terrestrial sources. Radiocarbon analyses of neutral monosaccharides released by the hydrolysis of APS have similar and modern (average 71‰) Δ 14C values. Radiocarbon data support our suggestion that these sugars occur as part of a common macromolecule, with an origin via recent biosynthesis. Preliminary radiocarbon data for total neutral monosaccharides isolated from APS at 300 and 750 m show this fraction to be substantially enriched relative to total HMW DOC and DOC. The relatively enriched radiocarbon values of APS at depth suggest APS is rapidly transported into the deep ocean.

  1. Dissolved organic carbon ameliorates the effects of UV radiation on a freshwater fish

    Energy Technology Data Exchange (ETDEWEB)

    Manek, Aditya K., E-mail: aditya.manek@usask.ca [Department of Biology, University of Saskatchewan, Saskatoon, S7N 5E2 SK (Canada); Ferrari, Maud C.O. [Department of Biomedical Sciences, WCVM, University of Saskatchewan, Saskatoon, S7N 5B4 SK (Canada); Chivers, Douglas P.; Niyogi, Som [Department of Biology, University of Saskatchewan, Saskatoon, S7N 5E2 SK (Canada)

    2014-08-15

    Anthropogenic activities over the past several decades have depleted stratospheric ozone, resulting in a global increase in ultraviolet radiation (UVR). Much of the negative effects of UVR in aquatic systems is minimized by dissolved organic carbon (DOC) which is known to attenuate UVR across the water column. The skin of many fishes contains large epidermal club cells (ECCs) that are known to play a role in innate immune responses and also release chemical alarm cues that warn other fishes of danger. This study investigated the effects of in vivo UVR exposure to fathead minnows (Pimephales promelas), under the influence of two sources of DOC: Sigma Aldrich humic acid, a coal based commercial source of DOC and Luther Marsh natural organic matter, a terrigenous source of DOC. Specifically, we examined ECC investment and physiological stress responses and found that fish exposed to high UVR, in the presence of either source of DOC, had higher ECC investment than fish exposed to high UVR only. Similarly, exposure to high UVR under either source of DOC, reduced cortisol levels relative to that in the high UVR only treatment. This indicates that DOC protects fish from physiological stress associated with UVR exposure and helps maintain production of ECC under conditions of UVR exposure. - Highlights: • We examined the combined effect of UV radiation and Dissolved Organic Carbon on fish. • Physiological stress response and epidermal club cell investment were measured. • Fish exposed to high UVR and DOC had higher ECC investment and reduced cortisol levels. • DOC plays a role in protecting fish from physiological stress and maintains ECC production.

  2. Development And Application of Functional Assays For Freshwater Dissolved Organic Matter

    Science.gov (United States)

    Thacker, S.; Tipping, E.; Gondar, D.; Baker, A.

    2006-12-01

    Dissolved organic matter (DOM) in natural waters participates in many important ecological and geochemical reactions, including acid-base buffering, light absorption, proton binding, binding of heavy metals, organic contaminants, aluminium and radionuclides, adsorption at surfaces, aggregation and photochemical reactivity. We are studying DOM in order to understand and quantify these functional properties, so we can use the knowledge to predict the influence of DOM on the natural freshwater environment. As DOM has no readily identifiable structure, our approach is to measure what it does, rather than what it is. Thus, we have developed a series of 12 standardised, reproducible assays of physico-chemical functions of dissolved organic matter (DOM) in freshwaters. The assays provide quantitative information on light absorption, fluorescence, photochemical fading, pH buffering, copper binding, benzo(a)pyrene binding, hydrophilicity and adsorption to alumina. We have collected twenty DOM samples in total, ten samples from a eutrophic lake (Esthwaite Water) and ten samples from three stream waters. A mild isolation method was then used to concentrate the DOM samples for the assay work. When assaying the concentrates, parallel assays were also preformed with Suwannee River Fulvic Acid (SRFA), as a quality control standard. Our results showed that; (i) for eleven of the assays, the variability among the twenty DOM samples was significantly (p<0.001) greater than can be explained by analytical error, i.e. by comparison with results from the SRFA quality control; (ii) the functional properties of the DOM from Esthwaite Water are strongly influenced by the seasonally-dependent input of autochthonous DOM, derived from phytoplankton. The autochthonous DOM is less fluorescent, light absorbing, hydrophobic and has a lower acid group content and capacity to be adsorbed onto alumina than terrestrially derived allochthonous DOM; (iii) significant correlations were found between

  3. Dissolved organic carbon ameliorates the effects of UV radiation on a freshwater fish

    International Nuclear Information System (INIS)

    Manek, Aditya K.; Ferrari, Maud C.O.; Chivers, Douglas P.; Niyogi, Som

    2014-01-01

    Anthropogenic activities over the past several decades have depleted stratospheric ozone, resulting in a global increase in ultraviolet radiation (UVR). Much of the negative effects of UVR in aquatic systems is minimized by dissolved organic carbon (DOC) which is known to attenuate UVR across the water column. The skin of many fishes contains large epidermal club cells (ECCs) that are known to play a role in innate immune responses and also release chemical alarm cues that warn other fishes of danger. This study investigated the effects of in vivo UVR exposure to fathead minnows (Pimephales promelas), under the influence of two sources of DOC: Sigma Aldrich humic acid, a coal based commercial source of DOC and Luther Marsh natural organic matter, a terrigenous source of DOC. Specifically, we examined ECC investment and physiological stress responses and found that fish exposed to high UVR, in the presence of either source of DOC, had higher ECC investment than fish exposed to high UVR only. Similarly, exposure to high UVR under either source of DOC, reduced cortisol levels relative to that in the high UVR only treatment. This indicates that DOC protects fish from physiological stress associated with UVR exposure and helps maintain production of ECC under conditions of UVR exposure. - Highlights: • We examined the combined effect of UV radiation and Dissolved Organic Carbon on fish. • Physiological stress response and epidermal club cell investment were measured. • Fish exposed to high UVR and DOC had higher ECC investment and reduced cortisol levels. • DOC plays a role in protecting fish from physiological stress and maintains ECC production

  4. Chromophoric Dissolved Organic Matter across a Marine Distributed Biological Observatory in the Pacific Arctic Region

    Science.gov (United States)

    Berman, S. L.; Frey, K. E.; Shake, K. L.; Cooper, L. W.; Grebmeier, J. M.

    2014-12-01

    Dissolved organic matter (DOM) plays an important role in marine ecosystems as both a carbon source for the microbial food web (and thus a source of CO2 to the atmosphere) and as a light inhibitor in marine environments. The presence of chromophoric dissolved organic matter (CDOM; the optically active portion of total DOM) can have significant controlling effects on transmittance of sunlight through the water column and therefore on primary production as well as the heat balance of the upper ocean. However, CDOM is also susceptible to photochemical degradation, which decreases the flux of solar radiation that is absorbed. Knowledge of the current spatial and temporal distribution of CDOM in marine environments is thus critical for understanding how ongoing and future changes in climate may impact these biological, biogeochemical, and physical processes. We describe the quantity and quality of CDOM along five key productive transects across a developing Distributed Biological Observatory (DBO) in the Pacific Arctic region. The samples were collected onboard the CCGS Sir Wilfred Laurier in July 2013 and 2014. Monitoring of the variability of CDOM along transects of high productivity can provide important insights into biological and biogeochemical cycling across the region. Our analyses include overall concentrations of CDOM, as well as proxy information such as molecular weight, lability, and source (i.e., autochthonous vs. allochthonous) of organic matter. We utilize these field observations to compare with satellite-derived CDOM concentrations determined from the Aqua MODIS satellite platform, which ultimately provides a spatially and temporally continuous synoptic view of CDOM concentrations throughout the region. Examining the current relationships among CDOM, sea ice variability, biological productivity, and biogeochemical cycling in the Pacific Arctic region will likely provide key insights for how ecosystems throughout the region will respond in future

  5. Isolation and characterization of dissolved organic matter from the Callovo-Oxfordian formation

    International Nuclear Information System (INIS)

    Courdouan, Amandine; Christl, Iso; Meylan, Sebastien; Wersin, Paul; Kretzschmar, Ruben

    2007-01-01

    Characterizing dissolved organic matter (DOM) in the pore water of the Callovo-Oxfordian formation, a potential host rock for the disposal of radioactive waste, is important to estimate its potential influence on the mobility of radionuclides in the rock. To isolate DOM, crushed rock material was extracted under anoxic conditions with deionized water, 0.1 M NaOH and synthetic pore water (SPW, water containing all major ions at pore water concentrations but no organic matter), respectively. The effects of extraction parameters on the extracted DOM including the solid-to-liquid ratio, extraction time, exposure to O 2 and acid pretreatment of the rock material prior to the anoxic extraction were evaluated. In addition, DOM in one of the first pore water samples collected in the underground rock laboratory at Bure (France) was characterized for comparison. The size distribution and the low molecular weight organic acid contents of the extracts and pore water DOM were determined by liquid chromatography coupled with an organic C detector (LC-OCD) and by ion chromatography. The results revealed that only a fraction of less than 1.2% of the total organic C present in the rock was extractable. Maximum dissolved organic C (DOC) concentrations in the anoxic extracts ranged from 5.5 ± 0.3 mg/L for SPW extracts to 14.2 ± 1.1 mg/L for 0.1 M NaOH extracts. The major portion of the DOC in the anoxic extracts consisted of hydrophilic compounds (48-78%) having a molecular weight of less than 500 Da. Up to 21% of DOC in the anoxic extracts was identified as acetate, formate, lactate and malate. The short-term exposure of rock material to O 2 during rock crushing strongly increased DOC concentrations and led to a shift towards smaller molecular weight compounds and to a higher low molecular weight organic acid (LMWOA) content as compared to the strictly anoxic extraction. The pore water sampled from a packed-off borehole exhibited a higher DOC concentration (56.7 mg/L) than the

  6. 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.

  7. Biogenic, urban, and wildfire influences on the molecular composition of dissolved organic compounds in cloud water

    Science.gov (United States)

    Cook, Ryan D.; Lin, Ying-Hsuan; Peng, Zhuoyu; Boone, Eric; Chu, Rosalie K.; Dukett, James E.; Gunsch, Matthew J.; Zhang, Wuliang; Tolic, Nikola; Laskin, Alexander; Pratt, Kerri A.

    2017-12-01

    Organic aerosol formation and transformation occurs within aqueous aerosol and cloud droplets, yet little is known about the composition of high molecular weight organic compounds in cloud water. Cloud water samples collected at Whiteface Mountain, New York, during August-September 2014 were analyzed by ultra-high-resolution mass spectrometry to investigate the molecular composition of dissolved organic carbon, with a focus on sulfur- and nitrogen-containing compounds. Organic molecular composition was evaluated in the context of cloud water inorganic ion concentrations, pH, and total organic carbon concentrations to gain insights into the sources and aqueous-phase processes of the observed high molecular weight organic compounds. Cloud water acidity was positively correlated with the average oxygen : carbon ratio of the organic constituents, suggesting the possibility for aqueous acid-catalyzed (prior to cloud droplet activation or during/after cloud droplet evaporation) and/or radical (within cloud droplets) oxidation processes. Many tracer compounds recently identified in laboratory studies of bulk aqueous-phase reactions were identified in the cloud water. Organosulfate compounds, with both biogenic and anthropogenic volatile organic compound precursors, were detected for cloud water samples influenced by air masses that had traveled over forested and populated areas. Oxidation products of long-chain (C10-12) alkane precursors were detected during urban influence. Influence of Canadian wildfires resulted in increased numbers of identified sulfur-containing compounds and oligomeric species, including those formed through aqueous-phase reactions involving methylglyoxal. Light-absorbing aqueous-phase products of syringol and guaiacol oxidation were observed in the wildfire-influenced samples, and dinitroaromatic compounds were observed in all cloud water samples (wildfire, biogenic, and urban-influenced). Overall, the cloud water molecular composition depended on

  8. Characterization of dissolved organic matter in fogwater by excitation-emission matrix fluorescence spectroscopy

    Science.gov (United States)

    Birdwell, J.E.; Valsaraj, K.T.

    2010-01-01

    Dissolved organic matter (DOM) present in fogwater samples collected in southeastern Louisiana and central-eastern China has been characterized using excitation-emission matrix fluorescence spectroscopy. The goal of the study was to illustrate the utility of fluorescence for obtaining information on the large fraction of organic carbon in fogwaters (typically >40% by weight) that defies characterization in terms of specific chemical compounds without the difficulty inherent in obtaining sufficient fogwater volume to isolate DOM for assessment using other spectroscopic and chemical analyses. Based on the findings of previous studies using other characterization methods, it was anticipated that the unidentified organic carbon fraction would have characteristic peaks associated with humic substances and fluorescent amino acids. Both humic- and protein-like fluorophores were observed in the fogwater spectra and fluorescence-derived indices for the fogwater had similar values to those of soil and sediment porewater. Greater biological character was observed in samples with higher organic carbon concentrations. Fogwaters are shown to contain a mixture of terrestrially- and microbially-derived fluorescent organic material, which is expected to be derived from an array of different sources, such as suspended soil and dust particles, biogenic emissions and organic substances generated by atmospheric processes. The fluorescence results indicate that much of the unidentified organic carbon present in fogwater can be represented by humic-like and biologically-derived substances similar to those present in other aquatic systems, though it should be noted that fluorescent signatures representative of DOM produced by atmospheric processing of organic aerosols may be contributing to or masked by humic-like fluorophores. ?? 2010.

  9. Radiocarbon in dissolved organic matter in the central North Pacific Ocean

    International Nuclear Information System (INIS)

    Williams, P.M.; Druffel, E.R.M.

    1987-01-01

    The authors present the first detailed profile of radiocarbon measured in dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) in the oligotrophic gyre of the central North Pacific. Δ 14 C of DOC ranged from -150 per mille (1,310 yr BP) in surface waters to -540 per mille (6,240 yr BP) at 5,710 m, 40 m off the bottom. The surprising similarity in the shapes of the profiles of Δ 14 C in the DOC and DIC pools suggest that similar processes are controlling the radiocarbon distribution in each of the two reservoirs and that bomb-produced radiocarbon has penetrated the DOC + DIC pools to a depth of ∼ 900 m. The depletion of the Δ 14 Csub(DOC) values by 300 per mille with respect to the Δ 14 Csub(DIC) values suggests that a certain fraction of the DOC is recycled within the ocean on longer time-scales than DIC. (author)

  10. 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.

  11. Impacts of beaver ponds on dissolved organic matter cycling in small temperate streams.

    Science.gov (United States)

    Larsen, J.; Lambert, T.; Larsen, A.; Lane, S.

    2017-12-01

    Beavers are engineers that modify the structure of river reaches and their hydrological functioning. By building dams, they modify the travel time of running waters and can lead to the flooding of surrounding soils and terrestrial vegetation, with potentially significant impact on biogeochemical cycles. Contradictory effects of beaver ponds on dissolved organic matter (DOM) concentration and composition have however been reported, and the underlying reasons are still unclear. In this study, we aimed to investigate the role of the landscape morphology as an important driver determining how a beaver population can affect stream DOM cycling. Four streams localized in Switzerland and Germany were visited during different seasons (spring, summer, winter) and monitored at upstream and downstream locations of beaver ponds across a hydrological cycle. The sites differed in terms of river channel morphology, presence or absence of floodplain, and vegetation cover. DOM composition was investigated through absorbance and fluorescence measurements coupled with parallel factor analysis (PARAFAC) along with stream water quality (nutrients, pH, dissolved oxygen and water temperature). The results show that the effects of beaver dams were variable, and emphasizes the importance of the geomorphological context.

  12. Enhanced Indirect Photochemical Transformation of Histidine and Histamine through Association with Chromophoric Dissolved Organic Matter.

    Science.gov (United States)

    Chu, Chiheng; Lundeen, Rachel A; Remucal, Christina K; Sander, Michael; McNeill, Kristopher

    2015-05-05

    Photochemical transformations greatly affect the stability and fate of amino acids (AAs) in sunlit aquatic ecosystems. Whereas the direct phototransformation of dissolved AAs is well investigated, their indirect photolysis in the presence of chromophoric dissolved organic matter (CDOM) is poorly understood. In aquatic systems, CDOM may act both as sorbent for AAs and as photosensitizer, creating microenvironments with high concentrations of photochemically produced reactive intermediates, such as singlet oxygen (1O2). This study provides a systematic investigation of the indirect photochemical transformation of histidine (His) and histamine by 1O2 in solutions containing CDOM as a function of solution pH. Both His and histamine showed pH-dependent enhanced phototransformation in the CDOM systems as compared to systems in which model, low-molecular-weight 1O2 sensitizers were used. Enhanced reactivity resulted from sorption of His and histamine to CDOM and thus exposure to elevated 1O2 concentrations in the CDOM microenvironment. The extent of reactivity enhancement depended on solution pH via its effects on the protonation state of His, histamine, and CDOM. Sorption-enhanced reactivity was independently supported by depressed rate enhancements in the presence of a cosorbate that competitively displaced His and histamine from CDOM. Incorporating sorption and photochemical transformation processes into a reaction rate prediction model improved the description of the abiotic photochemical transformation rates of His in the presence of CDOM.

  13. Linking the Molecular Signature of Heteroatomic Dissolved Organic Matter to Watershed Characteristics in World Rivers.

    Science.gov (United States)

    Wagner, Sasha; Riedel, Thomas; Niggemann, Jutta; Vähätalo, Anssi V; Dittmar, Thorsten; Jaffé, Rudolf

    2015-12-01

    Large world rivers are significant sources of dissolved organic matter (DOM) to the oceans. Watershed geomorphology and land use can drive the quality and reactivity of DOM. Determining the molecular composition of riverine DOM is essential for understanding its source, mobility and fate across landscapes. In this study, DOM from the main stem of 10 global rivers covering a wide climatic range and land use features was molecularly characterized via ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). FT-ICR mass spectral data revealed an overall similarity in molecular components among the rivers. However, when focusing specifically on the contribution of nonoxygen heteroatomic molecular formulas (CHON, CHOS, CHOP, etc.) to the bulk molecular signature, patterns relating DOM composition and watershed land use became apparent. Greater abundances of N- and S-containing molecular formulas were identified as unique to rivers influenced by anthropogenic inputs, whereas rivers with primarily forested watersheds had DOM signatures relatively depleted in heteroatomic content. A strong correlation between cropland cover and dissolved black nitrogen was established when focusing specifically on the pyrogenic class of compounds. This study demonstrated how changes in land use directly affect downstream DOM quality and could impact C and nutrient cycling on a global scale.

  14. Analysis of Dissolved Organic Nutrients in the Interstitial Water of Natural Biofilms.

    Science.gov (United States)

    Tsuchiya, Yuki; Eda, Shima; Kiriyama, Chiho; Asada, Tomoya; Morisaki, Hisao

    2016-07-01

    In biofilms, the matrix of extracellular polymeric substances (EPSs) retains water in the interstitial region of the EPS. This interstitial water is the ambient environment for microorganisms in the biofilms. The nutrient condition in the interstitial water may affect microbial activity in the biofilms. In the present study, we measured the concentrations of dissolved organic nutrients, i.e., saccharides and proteins, contained in the interstitial water of biofilms formed on the stones. We also analyzed the molecular weight distribution, chemical species, and availability to bacteria of some saccharides in the interstitial water. Colorimetric assays showed that the concentrations of saccharides and proteins in the biofilm interstitial water were significantly higher (ca. 750 times) than those in the surrounding lake waters (p Chromatographic analyses demonstrated that the saccharides in the interstitial waters were mainly of low molecular-weight saccharides such as glucose and maltose, while proteins in the interstitial water were high molecular-weight proteins (over 7000 Da). Bacterial growth and production of EPS occurred simultaneously with the decrease in the low molecular-weight saccharide concentrations when a small portion of biofilm suspension was inoculated to the collected interstitial water, suggesting that the dissolved saccharides in the interstitial water support bacterial growth and formation of biofilms.

  15. Short-term dynamics of North Sea bacterioplankton-dissolved organic matter coherence on molecular level

    Directory of Open Access Journals (Sweden)

    Judith eLucas

    2016-03-01

    Full Text Available Remineralisation and transformation of dissolved organic matter (DOM by marine microbes shape the DOM composition and thus, have large impact on global carbon and nutrient cycling. However, information on bacterioplankton-DOM interactions on a molecular level is limited. We examined the variation of bacterial community composition at Helgoland Roads (North Sea in relation to variation of molecular DOM composition and various environmental parameters on short-time scales. Surface water samples were taken daily over a period of twenty days. Bacterial community and molecular DOM composition were assessed via 16S rRNA gene tag sequencing and ultrahigh resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS, respectively. Environmental conditions were driven by a coastal water influx during the first half of the sampling period and the onset of a summer phytoplankton bloom towards the end of the sampling period. These phenomena led to a distinct grouping of bacterial communities and DOM composition which was particularly influenced by total dissolved nitrogen concentration, temperature and salinity, as revealed by distance-based linear regression analyses. Bacterioplankton-DOM interaction was demonstrated in strong correlations between specific bacterial taxa and particular DOM molecules, thus, suggesting potential specialization on particular substrates. We propose that a combination of high resolution techniques, as used in this study, may provide substantial information on substrate generalists and specialists and thus, contribute to prediction of bacterial community composition variation.

  16. Sources, distributions and dynamics of dissolved organic matter in the Canada and Makarov Basins

    Directory of Open Access Journals (Sweden)

    Yuan Shen

    2016-10-01

    Full Text Available A comprehensive survey of dissolved organic carbon (DOC and chromophoric dissolved organic matter (CDOM was conducted in the Canada and Makarov Basins and adjacent seas during 2010-2012 to investigate the dynamics of dissolved organic matter (DOM in the Arctic Ocean. Sources and distributions of DOM in polar surface waters were very heterogeneous and closely linked to hydrological conditions. Canada Basin surface waters had relatively low DOC concentrations (69±6 µmol L-1, CDOM absorption (a325: 0.32±0.07 m-1 and CDOM-derived lignin phenols (3±0.4 nmol L-1 and high spectral slope values (S275-295: 31.7±2.3 µm-1, indicating minor terrigenous inputs and evidence of photochemical alteration in the Beaufort Gyre. By contrast, surface waters of the Makarov Basin had elevated DOC (108±9 µmol L-1 and lignin phenol concentrations (15±3 nmol L-1, high a325 values (1.36±0.18 m-1 and low S275-295 values (22.8±0.8 µm-1, indicating pronounced Siberian river inputs associated with the Transpolar Drift and minor photochemical alteration. Observations near the Mendeleev Plain suggested limited interactions of the Transpolar Drift with Canada Basin waters, a scenario favoring export of Arctic DOM to the North Atlantic. The influence of sea-ice melt on DOM was region-dependent, resulting in an increase (Beaufort Sea, a decrease (Bering-Chukchi Seas, and negligible change (deep basins in surface DOC concentrations and a325 values. Halocline structures differed between basins, and the Canada Basin upper halocline and Makarov Basin halocline were comparable in their average DOC (65-70 µmol L-1 and lignin phenol concentrations (3-4 nmol L-1 and S275-295 values (22.9-23.7 µm-1. Deep-water DOC concentrations decreased by 6-8 µmol L-1 with increasing depth, water mass age, nutrient concentrations, and apparent oxygen utilization. Maximal estimates of DOC degradation rates (0.036-0.039 µmol L-1 yr-1 in the deep Arctic were lower than those in other ocean

  17. Sources, distributions and dynamics of dissolved organic matter in the Canada and Makarov Basins

    Science.gov (United States)

    Shen, Yuan; Benner, Ronald; Robbins, Lisa L.; Wynn, Jonathan

    2016-01-01

    A comprehensive survey of dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM) was conducted in the Canada and Makarov Basins and adjacent seas during 2010–2012 to investigate the dynamics of dissolved organic matter (DOM) in the Arctic Ocean. Sources and distributions of DOM in polar surface waters were very heterogeneous and closely linked to hydrological conditions. Canada Basin surface waters had relatively low DOC concentrations (69 ± 6 μmol L−1), CDOM absorption (a325: 0.32 ± 0.07 m−1) and CDOM-derived lignin phenols (3 ± 0.4 nmol L−1), and high spectral slope values (S275–295: 31.7 ± 2.3 μm−1), indicating minor terrigenous inputs and evidence of photochemical alteration in the Beaufort Gyre. By contrast, surface waters of the Makarov Basin had elevated DOC (108 ± 9 μmol L−1) and lignin phenol concentrations (15 ± 3 nmol L−1), high a325 values (1.36 ± 0.18 m−1), and low S275–295 values (22.8 ± 0.8 μm−1), indicating pronounced Siberian river inputs associated with the Transpolar Drift and minor photochemical alteration. Observations near the Mendeleev Plain suggested limited interactions of the Transpolar Drift with Canada Basin waters, a scenario favoring export of Arctic DOM to the North Atlantic. The influence of sea-ice melt on DOM was region-dependent, resulting in an increase (Beaufort Sea), a decrease (Bering-Chukchi Seas), and negligible change (deep basins) in surface DOC concentrations and a325 values. Halocline structures differed between basins, but the Canada Basin upper halocline and Makarov Basin halocline were comparable in their average DOC (65–70 μmol L−1) and lignin phenol concentrations (3–4 nmol L−1) and S275–295 values (22.9–23.7 μm−1). Deep-water DOC concentrations decreased by 6–8 μmol L−1 with increasing depth, water mass age, nutrient concentrations, and apparent oxygen utilization. Maximal estimates of DOC degradation rates (0.036–0.039 μmol L−1

  18. Linkages between the circulation and distribution of dissolved organic matter in the White Sea, Arctic Ocean

    Science.gov (United States)

    Pavlov, Alexey K.; Stedmon, Colin A.; Semushin, Andrey V.; Martma, Tõnu; Ivanov, Boris V.; Kowalczuk, Piotr; Granskog, Mats A.

    2016-05-01

    The White Sea is a semi-enclosed Arctic marginal sea receiving a significant loading of freshwater (225-231 km3 yr-1 equaling an annual runoff yield of 2.5 m) and dissolved organic matter (DOM) from river run-off. We report discharge weighed values of stable oxygen isotope ratios (δ18O) of -14.0‰ in Northern Dvina river for the period 10 May-12 October 2012. We found a significant linear relationship between salinity (S) and δ18O (δ18O=-17.66±0.58+0.52±0.02×S; R2=0.96, N=162), which indicates a dominant contribution of river water to the freshwater budget and little influence of sea ice formation or melt. No apparent brine additions from sea-ice formation is evident in the White Sea deep waters as seen from a joint analysis of temperature (T), S, δ18O and aCDOM(350) data, confirming previous suggestions about strong tidal induced vertical mixing in winter being the likely source of the deep waters. We investigated properties and distribution of colored dissolved organic matter (CDOM) and dissolved organic carbon (DOC) in the White Sea basin and coastal areas in summer. We found contrasting DOM properties in the inflowing Barents Sea waters and White Sea waters influenced by terrestrial runoff. Values of absorption by CDOM at 350 nm (aCDOM(350)) and DOC (exceeding 10 m-1 and 550 μmol l-1, respectively) in surface waters of the White Sea basin are higher compared to other river-influenced coastal Arctic domains. Linear relationship between S and CDOM absorption, and S and DOC (DOC=959.21±52.99-25.80±1.79×S; R2=0.85; N=154) concentrations suggests conservative mixing of DOM in the White Sea. The strongest linear correlation between CDOM absorption and DOC was found in the ultraviolet (DOC=56.31±2.76+9.13±0.15×aCDOM(254); R2=0.99; N=155), which provides an easy and robust tool to trace DOC using CDOM absorption measurements as well as remote sensing algorithms. Deviations from this linear relationship in surface waters likely indicate contribution from

  19. Transformations and Fates of Terrigenous Dissolved Organic Matter in River-influenced Ocean Margins

    Science.gov (United States)

    Fichot, Cedric G.

    Rivers contribute about 0.25 Pg of terrigenous dissolved organic carbon (tDOC) to the ocean each year. The fate and transformations of this material have important ramifications for the metabolic state of the ocean, air-sea CO2 exchange, and the global carbon cycle. Stable isotopic compositions and terrestrial biomarkers suggest tDOC must be efficiently mineralized in ocean margins. Nonetheless, the extent of tDOC mineralization in these environments remains unknown, as no quantitative estimate is available. The complex interplay of biogeochemical and physical processes in these systems compounded by the limited practicality of chemical proxies (organic biomarkers, isotopic compositions) make the quantification of tDOC mineralization in these dynamic systems particularly challenging. In this dissertation, new optical proxies were developed (Chapters 1 and 2) and facilitated the first quantitative assessment of tDOC mineralization in a dynamic river-influenced ocean margin (Chapter 3) and the monitoring of continental runoff distributions in the coastal ocean using remote sensing (Chapter 4). The optical properties of chromophoric dissolved organic matter (CDOM) were used as optical proxies for dissolved organic carbon concentration ([DOC]) and %tDOC. In both proxies, the CDOM spectral slope coefficient ( S275-295) was exploited for its informative properties on the chemical nature and composition of dissolved organic matter. In the first proxy, a strong relationship between S275-295 and the ratio of CDOM absorption to [DOC] facilitated accurate retrieval (+/- 4%) of [DOC] from CDOM. In the second proxy, the existence of a strong relationship between S275-295 and the DOC-normalized lignin yield facilitated the estimation of the %tDOC from S 275-295. Using the proxies, the tDOC concentration can be retrieved solely from CDOM absorption coefficients (lambda = 275-295 nm) in river-influenced ocean margins. The practicality of optical proxies facilitated the calculation

  20. Reclamation of zinc-contaminated soil using a dissolved organic carbon solution prepared using liquid fertilizer from food-waste composting

    International Nuclear Information System (INIS)

    Chiang, Po-Neng; Tong, Ou-Yang; Chiou, Chyow-San; Lin, Yu-An; Wang, Ming-Kuang; Liu, Cheng-Chung

    2016-01-01

    Highlights: • Nitrogen, phosphorus, and potassium contents in soil are substantially increased after the DOC washing. • The removal of Zn is dominated by proton replacement at pH 2.0, rather than by complexation with DOC. • The removal of Zn is dominated by DOC complexation between pH 3.0 and pH 5.0. - Abstract: A liquid fertilizer obtained through food-waste composting can be used for the preparation of a dissolved organic carbon (DOC) solution. In this study, we used the DOC solutions for the remediation of a Zn-contaminated soil (with Zn concentrations up to 992 and 757 mg kg −1 in topsoil and subsoil, respectively). We then determined the factors that affect Zn removal, such as pH, initial concentration of DOC solution, and washing frequency. Measurements using a Fourier Transform infrared spectrometer (FT-IR) revealed that carboxyl and amide were the major functional groups in the DOC solution obtained from the liquid fertilizer. Two soil washes using 1,500 mg L −1 DOC solution with a of pH 2.0 at 25 °C removed about 43% and 21% of the initial Zn from the topsoil and subsoil, respectively. Following this treatment, the pH of the soil declined from 5.4 to 4.1; organic matter content slightly increased from 6.2 to 6.5%; available ammonium (NH 4 + -N) content increased to 2.4 times the original level; and in the topsoil, the available phosphorus content and the exchangeable potassium content increased by 1.65 and 2.53 times their initial levels, respectively.

  1. Reclamation of zinc-contaminated soil using a dissolved organic carbon solution prepared using liquid fertilizer from food-waste composting

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, Po-Neng [Experimental Forest, National Taiwan University, Chushan, Nantou County, 55750, Taiwan (China); Tong, Ou-Yang [Department of Environment Engineering, College of the Environment and Ecology, and The Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, Xiamen University, Xiamen (China); Chiou, Chyow-San; Lin, Yu-An [Department of Environmental Engineering, National Ilan University, Ilan 26047, Taiwan (China); Wang, Ming-Kuang [Department of Animal Science, National Ilan University, Ilan 26047, Taiwan (China); Liu, Cheng-Chung, E-mail: ccliu@niu.edu.tw [Department of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan (China)

    2016-01-15

    Highlights: • Nitrogen, phosphorus, and potassium contents in soil are substantially increased after the DOC washing. • The removal of Zn is dominated by proton replacement at pH 2.0, rather than by complexation with DOC. • The removal of Zn is dominated by DOC complexation between pH 3.0 and pH 5.0. - Abstract: A liquid fertilizer obtained through food-waste composting can be used for the preparation of a dissolved organic carbon (DOC) solution. In this study, we used the DOC solutions for the remediation of a Zn-contaminated soil (with Zn concentrations up to 992 and 757 mg kg{sup −1} in topsoil and subsoil, respectively). We then determined the factors that affect Zn removal, such as pH, initial concentration of DOC solution, and washing frequency. Measurements using a Fourier Transform infrared spectrometer (FT-IR) revealed that carboxyl and amide were the major functional groups in the DOC solution obtained from the liquid fertilizer. Two soil washes using 1,500 mg L{sup −1} DOC solution with a of pH 2.0 at 25 °C removed about 43% and 21% of the initial Zn from the topsoil and subsoil, respectively. Following this treatment, the pH of the soil declined from 5.4 to 4.1; organic matter content slightly increased from 6.2 to 6.5%; available ammonium (NH{sub 4}{sup +}-N) content increased to 2.4 times the original level; and in the topsoil, the available phosphorus content and the exchangeable potassium content increased by 1.65 and 2.53 times their initial levels, respectively.

  2. Dissolved organic carbon from sewage sludge and manure can affect estrogen sorption and mineralization in soils

    Energy Technology Data Exchange (ETDEWEB)

    Stumpe, Britta, E-mail: britta.stumpe@rub.d [Ruhr-University Bochum, Institute of Geography, Department Soil Science/Soil Ecology, Universitaetsstr. 150, 44780 Bochum (Germany); Marschner, Bernd, E-mail: bernd.marschner@rub.d [Ruhr-University Bochum, Institute of Geography, Department Soil Science/Soil Ecology, Universitaetsstr. 150, 44780 Bochum (Germany)

    2010-01-15

    In this study, effects of sewage sludge and manure borne dissolved organic carbon (DOC) on 17beta-estradiol (E2) and 17alpha-ethinylestradiol (EE2) sorption and mineralization processes were investigated in three agricultural soils. Batch equilibrium techniques and equilibrium dialysis methods were used to determine sorption mechanisms between DOC, estrogens and the soil solid phase. It was found that that the presence of organic waste borne DOC decreased estrogen sorption in soils which seems to be controlled by DOC/estrogen complexes in solution and by exchange processes between organic waste derived and soil borne DOC. Incubation studies performed with {sup 14}C-estrogens showed that DOC addition decreased estrogen mineralization, probably due to reduced bioavailability of estrogens associated with DOC. This increased persistence combined with higher mobility could increase the risk of estrogen transport to ground and surface waters. - The effect of DOC on estrogen sorption and mineralization is influenced by exchange processes between organic waste borne and soil derived DOC.

  3. Complete and Partial Photo-oxidation of Dissolved Organic Matter Draining Permafrost Soils.

    Science.gov (United States)

    Ward, Collin P; Cory, Rose M

    2016-04-05

    Photochemical degradation of dissolved organic matter (DOM) to carbon dioxide (CO2) and partially oxidized compounds is an important component of the carbon cycle in the Arctic. Thawing permafrost soils will change the chemical composition of DOM exported to arctic surface waters, but the molecular controls on DOM photodegradation remain poorly understood, making it difficult to predict how inputs of thawing permafrost DOM may alter its photodegradation. To address this knowledge gap, we quantified the susceptibility of DOM draining the shallow organic mat and the deeper permafrost layer of arctic soils to complete and partial photo-oxidation and investigated changes in the chemical composition of each DOM source following sunlight exposure. Permafrost and organic mat DOM had similar lability to photomineralization despite substantial differences in initial chemical composition. Concurrent losses of carboxyl moieties and shifts in chemical composition during photodegradation indicated that photodecarboxylation could account for 40-90% of DOM photomineralized to CO2. Permafrost DOM had a higher susceptibility to partial photo-oxidation compared to organic mat DOM, potentially due to a lower abundance of phenolic moieties with antioxidant properties. These results suggest that photodegradation will likely continue to be an important control on DOM fate in arctic freshwaters as the climate warms and permafrost soils thaw.

  4. The hydrophilic/hydrophobic ratio vs. dissolved organics removal by coagulation – A review

    Directory of Open Access Journals (Sweden)

    Djamel Ghernaout

    2014-07-01

    Full Text Available This review discusses the hydrophilic/hydrophobic ratio as a function of the hydrophilic and hydrophobic contents removal by coagulation process. It is well established that coagulation process could bring a reduction in dissolved organic carbon of around 30–60% by increasing the coagulant dose and optimising reaction pH, in which large organic molecules with hydrophobic property was removed preferentially. Furthermore, the literature affirmed that the greater removal of UV-absorbing substances indicates that alum coagulation preferentially removed the hydrophobic fraction of the total organic carbon. For the hydrophobic fraction, it needs to be removed entirely without its transformation into hydrophilic fractions by coagulation process avoiding pre-chlorination/pre-oxidation due to the risk of organic molecules fragmentation. Determining the exact numerical values of the hydrophilic/hydrophobic ratio for raw water and treated water at different stages of the treatment processes in a water treatment plant, as for the DCO/DBO5 ratio in the case of wastewater treatment, would help on more focusing on OM control and removal.

  5. Characterization of biochars and dissolved organic matter phases obtained upon hydrothermal carbonization of Elodea nuttallii.

    Science.gov (United States)

    Poerschmann, J; Weiner, B; Wedwitschka, H; Zehnsdorf, A; Koehler, R; Kopinke, F-D

    2015-01-01

    The invasive aquatic plant Elodea nuttallii was subjected to hydrothermal carbonization at 200 °C and 240 °C to produce biochar. About 58% w/w of the organic carbon of the pristine plant was translocated into the solid biochar irrespectively of the operating temperature. The process water rich in dissolved organic matter proved a good substrate for biogas production. The E. nuttallii plants showed a high capability of incorporating metals into the biomass. This large inorganic fraction which was mainly transferred into the biochar (except sodium and potassium) may hamper the prospective application of biochar as soil amendment. The high ash content in biochar (∼ 40% w/w) along with its relatively low content of organic carbon (∼ 36% w/w) is associated with low higher heating values. Fatty acids were completely hydrolyzed from lipids due to hydrothermal treatment. Low molecular-weight carboxylic acids (acetic and lactic acid), phenols and phenolic acids turned out major organic breakdown products. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Dissolved organic carbon from sewage sludge and manure can affect estrogen sorption and mineralization in soils

    International Nuclear Information System (INIS)

    Stumpe, Britta; Marschner, Bernd

    2010-01-01

    In this study, effects of sewage sludge and manure borne dissolved organic carbon (DOC) on 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) sorption and mineralization processes were investigated in three agricultural soils. Batch equilibrium techniques and equilibrium dialysis methods were used to determine sorption mechanisms between DOC, estrogens and the soil solid phase. It was found that that the presence of organic waste borne DOC decreased estrogen sorption in soils which seems to be controlled by DOC/estrogen complexes in solution and by exchange processes between organic waste derived and soil borne DOC. Incubation studies performed with 14 C-estrogens showed that DOC addition decreased estrogen mineralization, probably due to reduced bioavailability of estrogens associated with DOC. This increased persistence combined with higher mobility could increase the risk of estrogen transport to ground and surface waters. - The effect of DOC on estrogen sorption and mineralization is influenced by exchange processes between organic waste borne and soil derived DOC.

  7. Fouling Characteristics of Dissolved Organic Matter in Papermaking Process Water on Polyethersulfone Ultrafiltration Membranes

    Directory of Open Access Journals (Sweden)

    Wenpeng Su

    2015-07-01

    Full Text Available In the papermaking industry, closure of process water (whitewater circuits has been used to reduce fresh water consumption. Membrane separation technology has potential for use in treating process water for recirculation. The purpose of this study was to reveal the fouling characteristics of a polyethersulfone (PES ultrafiltration membrane caused by dissolved organic matter (DOM in process water. Ultrafiltration membranes (UF and DAX ion exchange resins were applied to characterize the molecular weight (MW and hydrophilicity distribution of DOM. The interactions between various fractions of DOM and a PES ultrafiltration membrane were investigated. The membrane fouling characteristics were elucidated by examining the filtration resistances and linearized Herman’s blocking models. The results demonstrated that the membrane was fouled significantly by much of the MW distribution. The membrane was fouled more significantly by the low MW fraction rather than the high MW fraction. The filtration resistances and the fitted equation of Hermia’s laws indicated that hydrophilic organics were the main foulants. The hydrophilic organics partially block the membrane pores and form intermediate blocking, reducing the effective filtration area, while the hydrophobic organics form a gel layer or cake on the surface of the membrane.

  8. 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

  9. Controls of dissolved organic matter quality: Evidence from a large-scale boreal lake survey

    DEFF Research Database (Denmark)

    Kothawala, D.N.; Stedmon, Colin; Müller, R.A.

    2014-01-01

    Inland waters transport large amounts of dissolved organic matter (DOM) from terrestrial environments to the oceans, but DOM also reacts en route, with substantial water column losses by mineralization and sedimentation. For DOM transformations along the aquatic continuum, lakes play an important...... role as they retain waters in the landscape allowing for more time to alter DOM. We know DOM losses are significant at the global scale, yet little is known about how the reactivity of DOM varies across landscapes and climates. DOM reactivity is inherently linked to its chemical composition. We used...... analyzed in relation to lake chemistry, catchment, and climate characteristics. Land cover, particularly the percentage of water in the catchment, was a primary factor explaining variability in PARAFAC components. Likewise, lake water retention time influenced DOM quality. These results suggest...

  10. Molecular characterization of dissolved organic matter in freshwater wetlands of the Florida Everglades.

    Science.gov (United States)

    Lu, X Q; Maie, N; Hanna, J V; Childers, D L; Jaffé, R

    2003-06-01

    In this study, the molecular composition of dissolved organic matter (DOM), collected from wetlands of the Southern Everglades, was examined using a variety of analytical techniques in order to characterize its sources and transformation in the environment. The methods applied for the characterization of DOM included fluorescence spectroscopy, solid state 13C CPMAS NMR spectroscopy, and pyrolysis-GC/MS. The relative abundance of protein-like components and carbohydrates increased from the canal site to more remote freshwater marsh sites suggesting that significant amounts of non-humic DOM are autochthonously produced within the freshwater marshes, and are not exclusively introduced through canal inputs. Such in situ DOM production is important when considering how DOM from canals is processed and transported to downstream estuaries of Florida Bay.

  11. Radiocarbon measurements of dissolved organic carbon in sewage-treatment-plant effluent and domestic sewage

    International Nuclear Information System (INIS)

    Nara, Fumiko Watanabe; Imai, Akio; Matsushige, Kazuo; Komatsu, Kazuhiro; Kawasaki, Nobuyuki; Shibata, Yasuyuki

    2010-01-01

    In an attempt to better characterize dissolved organic carbon (DOC) in several specific sources to Lake Kasumigaura, such as sewage-treatment-plant effluent (STPE), domestic sewage (DS) and forest stream (FS), we analyzed radiocarbon ( 14 C) and stable carbon isotopic compositions ( 13 C) of the DOCs. The measurements of 14 C for DOC were performed by an accelerator mass spectrometer (AMS) at the National Institute for Environmental Studies (NIES-TERRA) in Japan. The Δ 14 C and δ 13 C values of the DOCs in several sources to Lake Kasumigaura, have low carbon isotopic values, ranging from -470 per mille to -79 per mille and from -27.9 per mille to -24.2 per mille , respectively. These carbon isotopic values are substantially different from those of Lake Kasumigaura. These results imply different origins for the DOC in Lake Kasumigaura. The 14 C and 13 C analyses of DOC led to a useful classification for DOCs in Lake Kasumigaura, Japan.

  12. The source and distribution of thermogenic dissolved organic matter in the ocean

    Science.gov (United States)

    Dittmar, T.; Suryaputra, I. G. N. A.; Paeng, J.

    2009-04-01

    Thermogenic organic matter (ThOM) is abundant in the environment. ThOM is produced at elevated temperature and pressure in deep sediments and earth's crust, and it is also a residue of fossil fuel and biomass burning ("black carbon"). Because of its refractory character, it accumulates in soils and sediments and, therefore, may sequester carbon from active cycles. It was hypothesized that a significant component of marine dissolved organic matter (DOM) might be thermogenic. Here we present a detailed data set on the distribution of thermogenic DOM in major water masses of the deep and surface ocean. In addition, several potential sources of thermogenic DOM to the ocean were investigated: active seeps of brine fluids in the deep Gulf of Mexico, rivers, estuaries and submarine groundwaters. Studies on deep-sea hydrothermal vents and aerosol deposition are ongoing. All DOM samples were isolated from seawater via solid phase extraction (SPE-DOM). ThOM was quantified in the extracts as benzene-polycarboxylic acids (BPCAs) after nitric acid oxidation via high-performance liquid chromatography and diode array detection (HPLC-DAD). BPCAs are produced exclusively from fused ring systems and are therefore unambiguous molecular tracers for ThOM. In addition to BPCA determination, the molecular composition and structure of ThOM was characterized in detail via ultrahigh resolution mass spectrometry (FT-ICR-MS). All marine and river DOM samples yielded significant amounts of BPCAs. The cold seep system in the deep Gulf of Mexico, but also black water rivers (like the Suwannee River) were particularly rich in ThOM. Up to 10% of total dissolved organic carbon was thermogenic in both systems. The most abundant BPCA was benzene-pentacarboxylic acid (B5CA). The molecular composition of BPCAs and the FT-ICR-MS data indicate a relatively small number (5-8) of fused aromatic rings per molecule. Overall, the molecular BPCA patterns were very similar independent of the source of Th

  13. Tolerance of Oncomelania hupensis quadrasi to varying concentrations of dissolved oxygen and organic pollution*

    Science.gov (United States)

    Garcia, Rolando G.

    1972-01-01

    Ecological investigations were made of habitats containing natural populations of the snail Oncomelania hupensis quadrasi and of habitats free from the snail in the island of Leyte, Philippines. This species of snail is a vector of Schistosoma japonicum in the Philippines. Snail-infested habitats had dissolved oxygen levels of 3.8-9.85 ppm but snail-free habitats had levels of only 0.08-3.6 ppm. Snail-infested habitats were less polluted by organic matter than habitats that were snail-free. Larger numbers of chlorophyll-bearing algae were present in both the water and the soil of snail-infested habitats. Other factors, including temperature, pH, hydrogen carbonate alkalinity, and relative humidity, were also investigated. PMID:4538906

  14. [Dissolved aluminum and organic carbon in soil solution under six tree stands in Lushan forest ecosystems].

    Science.gov (United States)

    Wang, Lianfeng; Pan, Genxing; Shi, Shengli; Zhang, Lehua; Huang, Mingxing

    2003-10-01

    Different depths of soils under 6 tree stands in Lushan Botany Garden were sampled and water-digested at room temperature. The dissolved aluminum and organic carbon were then determined by colorimetry, using 8-hydroxylquilin and TOC Analyzer, respectively. The results indicated that even derived from a naturally identical soil type, the test soils exhibited a diverse solution chemistry, regarding with the Al speciation. The soil solutions under Japanese cedar, giant arborvitae and tea had lower pH values and higher contents of soluble aluminum than those under Giant dogwood, azalea and bamboo. Under giant arborvitae, the lowest pH and the highest content of total soluble aluminum and monomeric aluminum were found in soil solution. There was a significant correlation between soluble aluminum and DOC, which tended to depress the accumulation of toxic monomeric aluminum. The 6 tree stands could be grouped into 2 categories of solution chemistry, according to aluminum mobilization.

  15. Changes in the composition and bioavailability of dissolved organic matter during sea ice formation

    DEFF Research Database (Denmark)

    Jørgensen, Linda; Stedmon, Colin A.; Kaartokallio, Hermanni

    2015-01-01

    matter (FDOM) fractions in sea ice, brines (contained in small pores between the ice crystals), and the underlying seawater during a 14 d experiment. Two series of mesocosms were used: one with seawater alone and one with seawater enriched with humic-rich river water. Abiotic processes increased...... processes such as sea ice formation as the source of the significant DOM removal in the Arctic Ocean. We present the results of a mesocosm experiment designed to investigate how sea ice formation affects DOM composition and bioavailability. We measured the change in different fluorescent dissolved organic...... the humic-like FDOM signal in the seawater below the ice during the initial ice formation. Humic-like FDOM fractions with a marine signal were preferentially retained in sea ice (relative to salinity), whereas humic-like FDOM with a terrestrial signal behaved more conservatively with respect to salinity...

  16. Advances in the Control System for a High Precision Dissolved Organic Carbon Analyzer

    Science.gov (United States)

    Liao, M.; Stubbins, A.; Haidekker, M.

    2017-12-01

    Dissolved organic carbon (DOC) is a master variable in aquatic ecosystems. DOC in the ocean is one of the largest carbon stores on earth. Studies of the dynamics of DOC in the ocean and other low DOC systems (e.g. groundwater) are hindered by the lack of high precision (sub-micromolar) analytical techniques. Results are presented from efforts to construct and optimize a flow-through, wet chemical DOC analyzer. This study focused on the design, integration and optimization of high precision components and control systems required for such a system (mass flow controller, syringe pumps, gas extraction, reactor chamber with controlled UV and temperature). Results of the approaches developed are presented.

  17. Linkages between the circulation and distribution of dissolved organic matter in the White Sea, Arctic Ocean

    OpenAIRE

    Pavlov, Alexey K.; Stedmon, Colin A.; Semushin, Andrey V.; Martma, Tõnu; Ivanov, Boris V.; Kowalczuk, Piotr; Granskog, Mats A.

    2016-01-01

    The White Sea is a semi-enclosed Arctic marginal sea receiving a significant loading of freshwater (225-231 km3 yr-1 equaling an annual runoff yield of 2.5 m) and dissolved organic matter (DOM) from river run-off. We report discharge weighed values of stable oxygen isotope ratios (δ18O) of -14.0‰ in Northern Dvina river for the period 10 May-12 October 2012. We found a significant linear relationship between salinity (S) and δ18O (δ18O=-17.66±0.58+0.52±0.02×S; R2=0.96, N=162), which indicates...

  18. Characterization by fluorescence of dissolved organic matter in rural drinking water storage tanks in Morocco.

    Science.gov (United States)

    Aziz, Faissal; Ouazzani, Naaila; Mandi, Laila; Assaad, Aziz; Pontvianne, Steve; Poirot, Hélène; Pons, Marie-Noëlle

    2018-04-01

    Water storage tanks, fed directly from the river through opened channels, are particular systems used for water supply in rural areas in Morocco. The stored water is used as drinking water by the surrounding population without any treatment. UV-visible spectroscopy and fluorescence spectroscopy (excitation-emission matrices and synchronous fluorescence) have been tested as rapid methods to assess the quality of the water stored in the reservoirs as well as along the river feeding them. Synchronous fluorescence spectra (SFS50), collected with a difference of 50 nm between excitation and emission wavelengths, revealed a high tryptophan-like fluorescence, indicative of a pollution induced by untreated domestic and/or farm wastewater. The best correlations were obtained between the total SFS50 fluorescence and dissolved organic carbon (DOC) and biological oxygen demand, showing that the contribution of humic-like fluorescent substances cannot be neglected to rapidly assess reservoir water quality in terms of DOC by fluorescence spectroscopy.

  19. Picocyanobacteria and deep-ocean fluorescent dissolved organic matter share similar optical properties

    Science.gov (United States)

    Zhao, Zhao; Gonsior, Michael; Luek, Jenna; Timko, Stephen; Ianiri, Hope; Hertkorn, Norbert; Schmitt-Kopplin, Philippe; Fang, Xiaoting; Zeng, Qinglu; Jiao, Nianzhi; Chen, Feng

    2017-05-01

    Marine chromophoric dissolved organic matter (CDOM) and its related fluorescent components (FDOM), which are widely distributed but highly photobleached in the surface ocean, are critical in regulating light attenuation in the ocean. However, the origins of marine FDOM are still under investigation. Here we show that cultured picocyanobacteria, Synechococcus and Prochlorococcus, release FDOM that closely match the typical fluorescent signals found in oceanic environments. Picocyanobacterial FDOM also shows comparable apparent fluorescent quantum yields and undergoes similar photo-degradation behaviour when compared with deep-ocean FDOM, further strengthening the similarity between them. Ultrahigh-resolution mass spectrometry (MS) and nuclear magnetic resonance spectroscopy reveal abundant nitrogen-containing compounds in Synechococcus DOM, which may originate from degradation products of the fluorescent phycobilin pigments. Given the importance of picocyanobacteria in the global carbon cycle, our results indicate that picocyanobacteria are likely to be important sources of marine autochthonous FDOM, which may accumulate in the deep ocean.

  20. The Role of Organic Acids on the Release of Phosphorus and Zinc in a Calcareous Soil

    Directory of Open Access Journals (Sweden)

    Sareh Nezami

    2017-02-01

    Full Text Available Introduction: Phosphorus (P and zinc (Zn fixation by soil minerals and their precipitation is one of the major constraints for crop production in calcareous soils. Recent Studies show that root exudates are effective for the extraction of the large amounts of nutrients in calcareous soils. A part of the root exudations are Low Molecular Weight Organic Acids (LMWOAs. LMWOAs are involved in the nutrients availability and uptake by plants, nutrients detoxification, minerals weathering and microbial proliferation in the soil. At nutrients deficiency conditions citric and oxalic acids are released by plants root in large quantities and increase nutrient solubility like P, Zn, Fe, Mn and Cu in the rhizosphere. These components are the large portion of the carbon source in the soil after exudations are mineralized by microorganisms, quickly. In addition, soil surface sorption can affect their half-life and other behaviors in the soil. In order to study the effect of oxalic and citric organic acids on the extraction of phosphorus and zinc from a calcareous soil, an experiment was conducted. Materials and Methods: Studied soil was calcareous and had P and Zn deficiency. Soil sample was collected from A horizon (0-30 cm of Damavand region. 3 g of dried soil sample was extracted with 30 ml of oxalic and citric acids extraction solutions at different concentrations (0.1, 1 and 10 mM and different time periods (10, 60, 180 and 360 minutes on an orbital shaker at 200 rev min-1.The soil extracts then centrifuged for 10 minutes (16000g. After filtering, the pH of the extractions was recorded and then phosphorus, calcium and zinc amounts were determined. Soil extraction with distilled water was used as control. Each treatment was performed in 3 replications. Statistical analysis was performed with ANOVA test followed by the Bonferroni method significant level adjustments due to multiple comparisons. Results and Discussion: The results of variance analysis showed

  1. Chromophoric Dissolved Organic Matter and Dissolved Organic Carbon from Sea-Viewing Wide Field-of-View Sensor (SeaWiFS), Moderate Resolution Imaging Spectroradiometer (MODIS) and MERIS Sensors: Case Study for the Northern Gulf of Mexico

    OpenAIRE

    Blake A. Schaeffer; Thomas S. Bianchi; Eurico J. D'Sa; Christopher L. Osburn; Nazanin Chaichi Tehrani

    2013-01-01

    Empirical band ratio algorithms for the estimation of colored dissolved organic matter (CDOM) and dissolved organic carbon (DOC) for Sea-viewing Wide Field-of-view Sensor (SeaWiFS), Moderate Resolution Imaging Spectroradiometer (MODIS) and MERIS ocean color sensors were assessed and developed for the northern Gulf of Mexico. Match-ups between in situ measurements of CDOM absorption coefficients at 412 nm (aCDOM(412)) with that derived from SeaWiFS were examined using two previously reported r...

  2. 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.

  3. Biologically labile photoproducts from riverine non-labile dissolved organic carbon in the coastal waters

    Science.gov (United States)

    Kasurinen, V.; Aarnos, H.; Vähätalo, A.

    2015-06-01

    In order to assess the production of biologically labile photoproducts (BLPs) from non-labile riverine dissolved organic carbon (DOC), we collected water samples from ten major rivers, removed labile DOC and mixed the residual non-labile DOC with artificial seawater for microbial and photochemical experiments. Bacteria grew on non-labile DOC with a growth efficiency of 11.5% (mean; range from 3.6 to 15.3%). Simulated solar radiation transformed a part of non-labile DOC into BLPs, which stimulated bacterial respiration and production, but did not change bacterial growth efficiency (BGE) compared to the non-irradiated dark controls. In the irradiated water samples, the amount of BLPs stimulating bacterial production depended on the photochemical bleaching of chromophoric dissolved organic matter (CDOM). The apparent quantum yields for BLPs supporting bacterial production ranged from 9.5 to 76 (mean 39) (μmol C mol photons-1) at 330 nm. The corresponding values for BLPs supporting bacterial respiration ranged from 57 to 1204 (mean 320) (μmol C mol photons-1). According to the calculations based on spectral apparent quantum yields and local solar radiation, the annual production of BLPs ranged from 21 (St. Lawrence) to 584 (Yangtze) mmol C m-2 yr-1 in the plumes of the examined rivers. Complete photobleaching of riverine CDOM in the coastal ocean was estimated to produce 10.7 Mt C BLPs yr-1 from the rivers examined in this study and globally 38 Mt yr-1 (15% of riverine DOC flux from all rivers), which support 4.1 Mt yr-1 of bacterial production and 33.9 Mt yr-1 bacterial respiration.

  4. Geochemistry and Flux of Terrigenous Dissolved Organic Matter to the Arctic Ocean

    Science.gov (United States)

    Spencer, R. G.; Mann, P. J.; Hernes, P. J.; Tank, S. E.; Striegl, R. G.; Dyda, R. Y.; Peterson, B. J.; McClelland, J. W.; Holmes, R. M.

    2011-12-01

    Rivers draining into the Arctic Ocean exhibit high concentrations of terrigenous dissolved organic carbon (DOC) and recent studies indicate that DOC export is changing due to climatic warming and alteration in permafrost condition. The fate of exported DOC in the Arctic Ocean is of key importance for understanding the regional carbon cycle and remains a point of discussion in the literature. As part of the Arctic Great Rivers Observatory (Arctic-GRO) project, samples were collected for DOC, chromophoric dissolved organic matter (CDOM) and lignin phenols from the Ob', Yenisey, Lena, Kolyma, Mackenzie and Yukon rivers in 2009 - 2010. DOC and lignin concentrations were elevated during the spring freshet and measurements related to DOC composition indicated an increasing contribution from terrestrial vascular plant sources at this time of year (e.g. lignin carbon-normalized yield, CDOM spectral slope, SUVA254, humic-like fluorescence). CDOM absorption was found to correlate strongly with both DOC (r2=0.83) and lignin concentration (r2=0.92) across the major arctic rivers. Utilizing these relationships we modeled loads for DOC and lignin export from high-resolution CDOM measurements (daily across the freshet) to derive improved flux estimates, particularly from the dynamic spring discharge maxima period when the majority of DOC and lignin export occurs. The new load estimates for DOC and lignin are higher than previous evaluations, emphasizing that if these are more representative of current arctic riverine export, terrigenous DOC is transiting through the Arctic Ocean at a faster rate than previously thought. It is apparent that higher resolution sampling of arctic rivers is exceptionally valuable with respect to deriving accurate fluxes and we highlight the potential of CDOM in this role for future studies and the applicability of in-situ CDOM sensors.

  5. Dissolved organic matter export in glacial and non-glacial streams along the Gulf of Alaska

    Science.gov (United States)

    Hood, E. W.; Scott, D.; Jeffery, A.; Schreiber, S.; Heavner, M.; Edwards, R.; D'Amore, D. V.; Fellman, J.

    2009-12-01

    The Gulf of Alaska drainage basin contains more than 75,000 km2 of glaciers, many of which are rapidly thinning and receding. We are using a paired watershed approach to evaluate how changes in glacier ecosystems will impact the export dissolved organic matter (DOM) into the Gulf of Alaska. Our primary study watersheds, Lemon Creek and Montana Creek, are similar in size, bedrock lithology and elevation range and extend from near sea level to the margin or interior of the Juneau Icefield. Lemon Creek has a glacial coverage of ~60%, while Montana Creek is free of glacier ice. Our goal is to evaluate seasonal differences in the quantity, chemical character and reactivity of DOM being exported from these watersheds to downstream near-shore marine ecosystems. In addition, we are monitoring a variety of physical parameters that influence instream DOM metabolism in both watersheds. Our initial results from the 2009 runoff season indicate that concentrations of dissolved organic carbon (DOC) are substantially higher in the non-glacial watershed. However, fluorescence analyses indicate that DOM from the glacier watershed has a higher protein and lower humic material content compared to DOM from the non-glacial watershed. After the spring snowmelt season, physical parameters between the two watersheds diverged, with higher streamflow and turbidity as well as colder water temperatures in the glacial watershed. Although our previous yield calculations show significantly higher DOC fluxes from the forested watershed, our results here suggest that glacier watersheds may be an important source of labile carbon to the near shore marine ecosystem. The contrast in the physical habitat between the two rivers (e.g glacier stream = cold, low light penetration, unstable substrate) supports the hypothesis that that in-stream DOM processing is limited within glacier dominated rivers, therefore delivering a higher percentage of labile DOM downstream.

  6. Human activities cause distinct dissolved organic matter composition across freshwater ecosystems

    Science.gov (United States)

    Williams, Clayton J.; Frost, Paul C.; Morales-Williams, Ana M.; Larson, James H.; Richardson, William B.; Chiandet, Aisha S.; Xenopoulos, Marguerite A.

    2016-01-01

    Dissolved organic matter (DOM) composition in freshwater ecosystems is influenced by interactions between physical, chemical, and biological processes that are controlled, at one level, by watershed landscape, hydrology, and their connections. Against this environmental template, humans may strongly influence DOM composition. Yet, we lack a comprehensive understanding of DOM composition variation across freshwater ecosystems differentially affected by human activity. Using optical properties, we described DOM variation across five ecosystem groups of the Laurentian Great Lakes Region: large lakes, Kawartha Lakes, Experimental Lakes Area, urban stormwater ponds, and rivers (n = 184 sites). We determined how between ecosystem variation in DOM composition related to watershed size, land use and cover, water quality measures (conductivity, dissolved organic carbon (DOC), nutrient concentration, chlorophyll a), and human population density. The five freshwater ecosystem groups had distinctive DOM composition from each other. These significant differences were not explained completely through differences in watershed size nor spatial autocorrelation. Instead, multivariate partial least squares regression showed that DOM composition was related to differences in human impact across freshwater ecosystems. In particular, urban/developed watersheds with higher human population densities had a unique DOM composition with a clear anthropogenic influence that was distinct from DOM composition in natural land cover and/or agricultural watersheds. This nonagricultural, human developed impact on aquatic DOM was most evident through increased levels of a microbial, humic-like parallel factor analysis component (C6). Lotic and lentic ecosystems with low human population densities had DOM compositions more typical of clear water to humic-rich freshwater ecosystems but C6 was only present at trace to background levels. Consequently, humans are strongly altering the quality of DOM in

  7. Flux and Seasonality of Dissolved Organic Matter From the Northern Dvina (Severnaya Dvina) River, Russia

    Science.gov (United States)

    Johnston, Sarah Ellen; Shorina, Natalia; Bulygina, Ekaterina; Vorobjeva, Taisya; Chupakova, Anna; Klimov, Sergey I.; Kellerman, Anne M.; Guillemette, Francois; Shiklomanov, Alexander; Podgorski, David C.; Spencer, Robert G. M.

    2018-03-01

    Pan-Arctic riverine dissolved organic carbon (DOC) fluxes represent a major transfer of carbon from land-to-ocean, and past scaling estimates have been predominantly derived from the six major Arctic rivers. However, smaller watersheds are constrained to northern high-latitude regions and, particularly with respect to the Eurasian Arctic, have received little attention. In this study, we evaluated the concentration of DOC and composition of dissolved organic matter (DOM) via optical parameters, biomarkers (lignin phenols), and ultrahigh resolution mass spectrometry in the Northern Dvina River (a midsized high-latitude constrained river). Elevated DOC, lignin concentrations, and aromatic DOM indicators were observed throughout the year in comparison to the major Arctic rivers with seasonality exhibiting a clear spring freshet and also some years a secondary pulse in the autumn concurrent with the onset of freezing. Chromophoric DOM absorbance at a350 was strongly correlated to DOC and lignin across the hydrograph; however, the relationships did not fit previous models derived from the six major Arctic rivers. Updated DOC and lignin fluxes were derived for the pan-Arctic watershed by scaling from the Northern Dvina resulting in increased DOC and lignin fluxes (50 Tg yr-1 and 216 Gg yr-1, respectively) compared to past estimates. This leads to a reduction in the residence time for terrestrial carbon in the Arctic Ocean (0.5 to 1.8 years). These findings suggest that constrained northern high-latitude rivers are underrepresented in models of fluxes based from the six largest Arctic rivers with important ramifications for the export and fate of terrestrial carbon in the Arctic Ocean.

  8. Relationships between land cover and dissolved organic matter change along the river to lake transition

    Science.gov (United States)

    Larson, James H.; Frost, Paul C.; Xenopoulos, Marguerite A.; Williams, Clayton J.; Morales-Williams, Ana M.; Vallazza, Jonathan M.; Nelson, J. C.; Richardson, William B.

    2014-01-01

    Dissolved organic matter (DOM) influences the physical, chemical, and biological properties of aquatic ecosystems. We hypothesized that controls over spatial variation in DOM quantity and composition (measured with DOM optical properties) differ based on the source of DOM to aquatic ecosystems. DOM quantity and composition should be better predicted by land cover in aquatic habitats with allochthonous DOM and related more strongly to nutrients in aquatic habitats with autochthonous DOM. Three habitat types [rivers (R), rivermouths (RM), and the nearshore zone (L)] associated with 23 tributaries of the Laurentian Great Lakes were sampled to test this prediction. Evidence from optical indices suggests that DOM in these habitats generally ranged from allochthonous (R sites) to a mix of allochthonous-like and autochthonous-like (L sites). Contrary to expectations, DOM properties such as the fluorescence index, humification index, and spectral slope ratio were only weakly related to land cover or nutrient data (Bayesian R 2 values were indistinguishable from zero). Strongly supported models in all habitat types linked DOM quantity (that is, dissolved organic carbon concentration [DOC]) to both land cover and nutrients (Bayesian R2 values ranging from 0.55 to 0.72). Strongly supported models predicting DOC changed with habitat type: The most important predictor in R sites was wetlands whereas the most important predictor at L sites was croplands. These results suggest that as the DOM pool becomes more autochthonous-like, croplands become a more important driver of spatial variation in DOC and wetlands become less important.

  9. Decoupling of dissolved organic matter patterns between stream and riparian groundwater in a headwater forested catchment

    Science.gov (United States)

    Bernal, Susana; Lupon, Anna; Catalán, Núria; Castelar, Sara; Martí, Eugènia

    2018-03-01

    Streams are important sources of carbon to the atmosphere, though knowing whether they merely outgas terrestrially derived carbon dioxide or mineralize terrestrial inputs of dissolved organic matter (DOM) is still a big challenge in ecology. The objective of this study was to investigate the influence of riparian groundwater (GW) and in-stream processes on the temporal pattern of stream DOM concentrations and quality in a forested headwater stream, and whether this influence differed between the leaf litter fall (LLF) period and the remaining part of the year (non-LLF). The spectroscopic indexes (fluorescence index, biological index, humification index, and parallel factor analysis components) indicated that DOM had an eminently protein-like character and was most likely originated from microbial sources and recent biological activity in both stream water and riparian GW. However, paired samples of stream water and riparian GW showed that dissolved organic carbon (DOC) and nitrogen (DON) concentrations as well as the spectroscopic character of DOM differed between the two compartments throughout the year. A simple mass balance approach indicated that in-stream processes along the reach contributed to reducing DOC and DON fluxes by 50 and 30 %, respectively. Further, in-stream DOC and DON uptakes were unrelated to each other, suggesting that these two compounds underwent different biogeochemical pathways. During the LLF period, stream DOC and DOC : DON ratios were higher than during the non-LLF period, and spectroscopic indexes suggested a major influence of terrestrial vegetation on stream DOM. Our study highlights that stream DOM is not merely a reflection of riparian GW entering the stream and that headwater streams have the capacity to internally produce, transform, and consume DOM.

  10. Photochemical Transformation and Bacterial Utilization of Dissolved Organic Matter and Disinfection Byproduct Precursors from Foliar Litter

    Science.gov (United States)

    Chow, A. T.; Wong, P.; O'Geen, A. T.; Dahlgren, R. A.

    2009-12-01

    Foliar litter is an important terrestrial source of dissolved organic matter (DOM) in surface water. DOM is a public health concern since it is a precursor of carcinogenic disinfection byproducts (DBPs) during drinking water treatment. Chemical characterization of in-situ water samples for their impact on water treatment may be misleading because DOM characteristics can be altered from their original composition during downstream transport to water treatment plants. In this study, we collected leachate from four fresh litters and decomposed duffs from four dominant vegetation components of California oak woodlands: blue oak (Quercus douglassi), live oak (Quercus wislizenii), foothill pine (Pinus sabiniana), and annual grasses to evaluate their DOM degradability and the reactivity of altered DOM towards DBP formation. Samples were filtered through a sterilized membrane (0.2 micron) and exposed to natural sunlight and Escherichia coli K-12 independently for 14 days. Generally speaking, leachate from decomposed duff was relatively resistant towards biodegradation compared to that from fresh litter, but the former was more susceptible to photo-transformation. Photo-bleaching caused a 30% decrease in ultra-violet absorbance at 254 nm (UVA) but no significant changes in dissolved organic carbon (DOC) concentration. This apparent loss of aromatic carbon in DOM, in terms of specific UVA, did not result in a decrease of specific trihalomethane (THM) formation potential, although aromatic carbon is considered as a major reactive site for THM formation. In addition, there were significant increases (p < 0.05) of chloral hydrate after the 14-day exposure, suggesting that the photolytic products could be a precursor of chloral hydrate. In contrast, samples inoculated with E. coli did not show a significant effect on the DOC concentration, UVA or DBP formation, although the colony counts indicated a 2-log cell growth during the 14-day incubation. Results suggest photolysis is a

  11. Small scale variability of transport and composition of dissolved organic matter in the subsoil

    Science.gov (United States)

    Leinemann, T.; Mikutta, R.; Kalbitz, K.; Guggenberger, G.

    2016-12-01

    Dissolved organic matter (DOM) is the most mobile fraction of carbon in the soil and connects the carbon-rich topsoil with the subsoil where translocated OM may get stabilized. The water flux in soil is highly heterogeneous, both temporarily and spatially. We, therefore, hypothesize that at high flow velocities, DOM can bypass possible mineral binding sites and microorganisms, thus leading to less degraded DOM under high flow velocities. To address this question, we investigated water and DOM fluxes in situ using segmented suction plates (4 x 4 segments on 24 x 24 cm) installed into three soil observatories at three depths (10 cm, 50 cm, and 150 cm) in a Dystric Cambisol under Beech (Fagus sylvatica) near Hannover, Germany. To follow the transport of carbon from the litter layer through the soil, an in situ 13C-labelling experiment has been conducted in January 2015. Concentration of dissolved organic carbon (DOC) and DOM composition was analyzed using high temperature combustion and photometric methods. The amount of transported DOC decreased by ca. 80 % from 10 to 50 cm depth and by 40 % from 50 to 150 cm depth. Different flow patterns existed at the centimeter scale, which were stable over time for individual suction plate segments. The specific UV280 nm absorbance of DOM decreased with increasing soil depth. This indicates a selective loss of aromatic compounds. The influence of different flow regimes on the DOM quality became apparent in the subsoil samples (>50 cm depth) showing a correlation of increasing UV280 nm absorbance with increasing water flux. The 13C-labelling experiment showed that after 10 month just 0.3 % of the DOC in 150 cm depth was derived from fresh litter. The transport of leaf litter carbon seemed to be controlled by the flow regime as the DO13C ratio and the water flux correlated positively. This can be an indication for the importance of preferential flow on carbon transport to the subsoil.

  12. 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.

  13. The effect of probe choice and solution conditions on the apparent photoreactivity of dissolved organic matter.

    Science.gov (United States)

    Maizel, Andrew C; Remucal, Christina K

    2017-08-16

    Excited triplet states of dissolved organic matter ( 3 DOM) are quantified directly with the species-specific probes trans,trans-hexadienoic acid (HDA) and 2,4,6-trimethylphenol (TMP), and indirectly with the singlet oxygen ( 1 O 2 ) probe furfuryl alcohol (FFA). Although previous work suggests that these probe compounds may be sensitive to solution conditions, including dissolved organic carbon concentration ([DOC]) and pH, and may quantify different 3 DOM subpopulations, the probes have not been systematically compared. Therefore, we quantify the apparent photoreactivity of diverse environmental waters using HDA, TMP, and FFA. By conducting experiments under ambient [DOC] and pH, with standardized [DOC] and pH, and with solid phase extraction isolates, we demonstrate that much of the apparent dissimilarity in photochemical measurements is attributable to solution conditions, rather than intrinsic differences in 3 DOM production. In general, apparent quantum yields (Φ 1 O 2 ≥ Φ 3 DOM,TMP ≫ Φ 3 DOM,HDA ) and pseudo-steady state concentrations ([ 1 O 2 ] ss > [ 3 DOM] ss,TMP > [ 3 DOM] ss,HDA ) show consistent relationships in all waters under standardized conditions. However, intrinsic differences in 3 DOM photoreactivity are apparent between DOM from diverse sources, as seen in the higher Φ 1 O 2 and lower Φ 3 DOM,TMP of wastewater effluents compared with oligotrophic lakes. Additionally, while conflicting trends in photoreactivity are observed under ambient conditions, all probes observe quantum yields increasing from surface wetlands to terrestrially influenced waters to oligotrophic lakes under standardized conditions. This work elucidates how probe selection and solution conditions influence the apparent photoreactivity of environmental waters and confirms that 3 DOM or 1 O 2 probes cannot be used interchangeably in waters that vary in [DOC], pH, or DOM source.

  14. Dissolved Organic Carbon along the Louisiana coast from MODIS and MERIS satellite data

    Science.gov (United States)

    Chaichi Tehrani, N.; D'Sa, E. J.

    2012-12-01

    Dissolved organic carbon (DOC) plays a critical role in the coastal and ocean carbon cycle. Hence, it is important to monitor and investigate its the distribution and fate in coastal waters. Since DOC cannot be measured directly through satellite remote sensors, chromophoric dissolved organic matter (CDOM) as an optically active fraction of DOC can be used as an alternative proxy to trace DOC concentrations. Here, satellite ocean color data from MODIS, MERIS, and field measurements of CDOM and DOC were used to develop and assess CDOM and DOC ocean color algorithms for coastal waters. To develop a CDOM retrieval algorithm, empirical relationships between CDOM absorption coefficient at 412 nm (aCDOM(412)) and reflectance ratios Rrs(488)/Rrs(555) for MODIS and Rrs(510)/Rrs(560) for MERIS were established. The performance of two CDOM empirical algorithms were evaluated for retrieval of (aCDOM(412)) from MODIS and MERIS in the northern Gulf of Mexico. Further, empirical algorithms were developed to estimate DOC concentration using the relationship between in situ aCDOM(412) and DOC, as well as using the newly developed CDOM empirical algorithms. Accordingly, our results revealed that DOC concentration was strongly correlated to aCDOM (412) for summer and spring-winter periods (r2 = 0.9 for both periods). Then, using the aCDOM(412)-Rrs and the aCDOM(412)-DOC relationships derived from field measurements, a relationship between DOC-Rrs was established for MODIS and MERIS data. The DOC empirical algorithms performed well as indicated by match-up comparisons between satellite estimates and field data (R2=0.52 and 0.58 for MODIS and MERIS for summer period, respectively). These algorithms were then used to examine DOC distribution along the Louisiana coast.

  15. 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.

  16. Dissolved organic carbon and nitrogen release from Holocene permafrost and seasonally frozen soils

    Science.gov (United States)

    Wickland, K.; Waldrop, M. P.; Koch, J. C.; Jorgenson, T.; Striegl, R. G.

    2017-12-01

    Permafrost (perennially frozen) soils store vast amounts of carbon (C) and nitrogen (N) that are vulnerable to mobilization to the atmosphere as greenhouse gases and to terrestrial and aquatic ecosystems as dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) upon thaw. Such releases will affect the biogeochemistry of arctic and boreal regions, yet little is known about active layer (seasonally frozen) and permafrost source variability that determines DOC and TDN mobilization. We quantified DOC and TDN leachate yields from a range of active layer and permafrost soils in Alaska varying in age and C and N content to determine potential release upon thaw. Soil cores from the upper 1 meter were collected in late winter, when soils were frozen, from three locations representing a range in geographic position, landscape setting, permafrost depth, and soil types across interior Alaska. Two 15 cm-thick segments were extracted from each core: a deep active-layer horizon and a shallow permafrost horizon. Soils were thawed and leached for DOC and TDN yields, dissolved organic matter optical properties, and DOC biodegradability; soils were analyzed for C and N content, and radiocarbon content. Soils had wide-ranging C and N content (<1-44% C, <0.1-2.3% N), and varied in radiocarbon age from 450-9200 years before present - thus capturing typical ranges of boreal and arctic soils. Soil DOC and TDN yields increased linearly with soil C and N content, and decreased with increasing radiocarbon age. However, across all sites DOC and TDN yields were significantly greater from permafrost soils (0.387 ± 0.324 mg DOC g-1 soil; 0.271 ± 0.0271 mg N g-1 soil) than from active layer soils (0.210 ± 0.192 mg DOC g-1 soil; 0.00716 ± 0.00569 mg N g-1 soil). DOC biodegradability increased with increasing radiocarbon age, and was statistically similar for active layer and permafrost soils. Our findings suggest that the continuously frozen state of permafrost soils has preserved

  17. Leaching behavior of total organic carbon, nitrogen, and phosphorus from banana peel.

    Science.gov (United States)

    Jiang, Ruixue; Sun, Shujuan; Xu, Yan; Qiu, Xiudong; Yang, Jili; Li, Xiaochen

    2015-01-01

    The leaching behavior of organic carbon and nutrient compounds from banana peel (BP) was investigated in batch assays with respect to particle size, contact time, pH value, and temperature. The granularity, contact time, pH, and temperature caused no significant effects on the leaching of total phosphorus (TP) from the BP. The maximum leached total nitrogen (TN) content was found at pH 5.0 and 90 minutes, while no significant effects were caused by the granularity and temperature. The maximum leached total organic carbon (TOC) content was found by using a powder of 40 mesh, 150 minutes and at pH 6.0, while the temperature had no effect on the TOC leaching. The proportions of the TN, TP, and TOC contents leached from the dried BP ranged from 33.6% to 40.9%, 60.4% to 72.7%, and 8.2% to 9.9%, respectively, indicating that BP could be a potential pollution source for surface and ground water if discharged as domestic waste or reutilized without pretreatment.

  18. Dissolved organic nitrogen (DON) losses from nested artificially drained lowland catchments with contrasting soil types

    Science.gov (United States)

    Tiemeyer, Bärbel; Kahle, Petra; Lennartz, Bernd

    2010-05-01

    Artificial drainage is a common practice to improve moisture and aeration conditions of agricultural land. It shortens the residence time of water in the soil and may therefore contribute to the degradation of peatlands as well as to the still elevated level of diffuse pollution of surface water bodies, particularly if flow anomalies like preferential flow cause a further acceleration of water and solute fluxes. Especially in the case of nitrate, artificially drained sub-catchments are found to control the catchment-scale nitrate losses. However, it is frequently found that nitrate losses and nitrogen field balances do not match. At the same time, organic fertilizers are commonly applied and, especially in lowland catchments, organic soils have been drained for agricultural use. Thus, the question arises whether dissolved organic nitrogen (DON) forms an important component of the nitrogen losses from artificially drained catchments. However, in contrast to nitrate and even to dissolved organic carbon (DOC), this component is frequently overlooked, especially in nested catchment studies with different soil types and variable land use. Here, we will present data from a hierarchical water quantity and quality measurement programme in the federal state Mecklenburg-Vorpommern (North-Eastern Germany). The monitoring programme in the pleistocene lowland catchment comprises automatic sampling stations at a collector drain outlet (4.2 ha catchment), at a ditch draining arable land on mineral soils (179 ha), at a ditch mainly draining grassland on organic soils (85 ha) and at a brook with a small rural catchment (15.5 km²) of mixed land use and soil types. At all sampling stations, daily to weekly composite samples were taken, while the discharge and the meteorological data were recorded continuously. Water samples were analyzed for nitrate-nitrogen, ammonium-nitrogen and total nitrogen. We will compare two years: 2006/07 was a very wet year (P = 934 mm) with a high summer

  19. Compositional Characteristics of Dissolved Organic Matter released from the sediment of Han river in Korea.

    Science.gov (United States)

    Oh, H.; Choi, J. H.

    2017-12-01

    The dissolved organic matter (DOM) has variable characteristics depending on the sources. The DOM of a river is affected by rain water, windborne material, surface and groundwater flow, and sediments. In particular, sediments are sources and sinks of nutrients and pollutants in aquatic ecosystems by supplying large amounts of organic matter. The DOM which absorbs ultraviolet and visible light is called colored dissolved organic matter (CDOM). CDOM is responsible for the optical properties of natural waters in several biogeochemical and photochemical processes and absorbs UV-A (315-400 nm) and UV-B (280-315), which are harmful to aquatic ecosystems (Helms et al., 2008). In this study, we investigated the quantity and quality of DOM and CDOM released from the sediments of Han river which was impacted by anthropogenic activities and hydrologic alternation of 4 Major River Restoration Project. The target area of this study is Gangchenbo (GC), Yeojubo (YJ), and Ipobo(IP) of the Han River, Korea. Sediments and water samples were taken on July and August of 2016 and were incubated at 20° up to 7 days. Absorbance was measured with UV-visible spectrophotometer (Libra S32 PC, Biochrom). Fluorescence intensity determined with Fluorescence EEMs (F-7000, Hitachi). Absorbance and fluorescence intensity were used to calculate Specific Ultraviolet Absorbance (SUVA254), Humification index (HIX), Biological index (BIX), Spectral slope (SR) and component analysis. The DOC concentration increased after 3 days of incubation. According to the SUVA254 analysis, the microbial activity is highest in the initial overlying water of IP. HIX have range of 1.35-4.08, and decrease poly aromatic structures of organic matter during incubation. From the results of the BIX, autochthonous organic matter was released from the sediments. In all sites, Humic-like DOM, Microbial humic-like DOM and Protein-like DOM increased significantly between Day 0 and 3(except Humic-like, Microbial humic-like DOM in

  20. Dissolved organic matter in sea spray: a transfer study from marine surface water to aerosols

    Science.gov (United States)

    Schmitt-Kopplin, P.; Liger-Belair, G.; Koch, B. P.; Flerus, R.; Kattner, G.; Harir, M.; Kanawati, B.; Lucio, M.; Tziotis, D.; Hertkorn, N.; Gebefügi, I.

    2012-04-01

    Atmospheric aerosols impose direct and indirect effects on the climate system, for example, by absorption of radiation in relation to cloud droplets size, on chemical and organic composition and cloud dynamics. The first step in the formation of Organic primary aerosols, i.e. the transfer of dissolved organic matter from the marine surface into the atmosphere, was studied. We present a molecular level description of this phenomenon using the high resolution analytical tools of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and nuclear magnetic resonance spectroscopy (NMR). Our experiments confirm the chemoselective transfer of natural organic molecules, especially of aliphatic compounds from the surface water into the atmosphere via bubble bursting processes. Transfer from marine surface water to the atmosphere involves a chemical gradient governed by the physicochemical properties of the involved molecules when comparing elemental compositions and differentiating CHO, CHNO, CHOS and CHNOS bearing compounds. Typical chemical fingerprints of compounds enriched in the aerosol phase were CHO and CHOS molecular series, smaller molecules of higher aliphaticity and lower oxygen content, and typical surfactants. A non-targeted metabolomics analysis demonstrated that many of these molecules corresponded to homologous series of oxo-, hydroxy-, methoxy-, branched fatty acids and mono-, di- and tricarboxylic acids as well as monoterpenes and sugars. These surface active biomolecules were preferentially transferred from surface water into the atmosphere via bubble bursting processes to form a significant fraction of primary organic aerosols. This way of sea spray production leaves a selective biological signature of the surface water in the corresponding aerosol that may be transported into higher altitudes up to the lower atmosphere, thus contributing to the formation of secondary organic aerosol on a global scale or transported laterally with

  1. Photomineralization and photomethanification of dissolved organic matter in Saguenay River surface water

    Science.gov (United States)

    Zhang, Y.; Xie, H.

    2015-11-01

    Rates and apparent quantum yields of photomineralization (AQYDOC) and photomethanification (AQYCH4) of chromophoric dissolved organic matter (CDOM) in Saguenay River surface water were determined at three widely differing dissolved oxygen concentrations ([O2]) (suboxic, air saturation, and oxygenated) using simulated-solar radiation. Photomineralization increased linearly with CDOM absorbance photobleaching for all three O2 treatments. Whereas the rate of photochemical dissolved organic carbon (DOC) loss increased with increasing [O2], the ratio of fractional DOC loss to fractional absorbance loss showed an inverse trend. CDOM photodegradation led to a higher degree of mineralization under suboxic conditions than under oxic conditions. AQYDOC determined under oxygenated, suboxic, and air-saturated conditions increased, decreased, and remained largely constant with photobleaching, respectively; AQYDOC obtained under air saturation with short-term irradiations could thus be applied to longer exposures. AQYDOC decreased successively from ultraviolet B (UVB) to ultraviolet A (UVA) to visible (VIS), which, alongside the solar irradiance spectrum, points to VIS and UVA being the primary drivers for photomineralization in the water column. The photomineralization rate in the Saguenay River was estimated to be 2.31 × 108 mol C yr-1, accounting for only 1 % of the annual DOC input into this system. Photoproduction of CH4 occurred under both suboxic and oxic conditions and increased with decreasing [O2], with the rate under suboxic conditions ~ 7-8 times that under oxic conditions. Photoproduction of CH4 under oxic conditions increased linearly with photomineralization and photobleaching. Under air saturation, 0.00057 % of the photochemical DOC loss was diverted to CH4, giving a photochemical CH4 production rate of 4.36 × 10-6 mol m-2 yr-1 in the Saguenay River and, by extrapolation, of (1.9-8.1) × 108 mol yr-1 in the global ocean. AQYCH4 changed little with

  2. Input of particulate organic and dissolved inorganic carbon from the Amazon to the Atlantic Ocean

    Science.gov (United States)

    Druffel, E. R. M.; Bauer, J. E.; Griffin, S.

    2005-03-01

    We report concentrations and isotope measurements (radiocarbon and stable carbon) of dissolved inorganic carbon (DIC) and suspended particulate organic carbon (POC) in waters collected from the mouth of the Amazon River and the North Brazil Current. Samples were collected in November 1991, when the Amazon hydrograph was at its annual minimum and the North Brazil Current had retroflected into the equatorial North Atlantic. The DIC Δ14C results revealed postbomb carbon in river and ocean waters, with slightly higher values at the river mouth. The low DIC δ13C signature of the river end-member (-11‰) demonstrates that about half of the DIC originated from the remineralization of terrestrially derived organic matter. A linear relationship between DIC and salinity indicates that DIC was mixed nearly conservatively in the transition zone from the river mouth to the open ocean, though there was a small amount (≤10%) of organic matter remineralization in the mesohaline region. The POC Δ14C values in the river mouth were markedly lower than those values from the western Amazon region (Hedges et al., 1986). We conclude that the dominant source of POC near the river mouth and in the inner Amazon plume during November 1991 was aged, resuspended material of significant terrestrial character derived from shelf sediments, while the outer plume contained mainly marine-derived POC.

  3. Characterization of isolated fractions of dissolved organic matter derived from municipal solid waste compost.

    Science.gov (United States)

    Yu, Minda; He, Xiaosong; Liu, Jiaomei; Wang, Yuefeng; Xi, Beidou; Li, Dan; Zhang, Hui; Yang, Chao

    2018-04-14

    Understanding the heterogeneous evolution characteristics of dissolved organic matter fractions derived from compost is crucial to exploring the composting biodegradation process and the possible applications of compost products. Herein, two-dimensional correlation spectroscopy integrated with reversed-phase high performance liquid chromatography and size exclusion chromatography were utilized to obtain the molecular weight (MW) and polarity evolution characteristics of humic acid (HA), fulvic acid (FA), and the hydrophilic (HyI) fractions during composting. The high-MW humic substances and building blocks in the HA fraction degraded faster during composting than polymers, proteins, and organic colloids. Similarly, the low MW acid FA factions transformed faster than the low weight neutral fractions, followed by building blocks, and finally polymers, proteins, and organic colloids. The evolutions of HyI fractions during composting occurred first for building blocks, followed by low MW acids, and finally low weight neutrals. With the progress of composting, the hydrophobic properties of the HA and FA fractions were enhanced. The degradation/humification process of the hydrophilic and transphilic components was faster than that of the hydrophobic component. Compared with the FA and HyI fractions, the HA fraction exhibited a higher MW and increased hydrophobicity. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. Towards a universal microbial inoculum for dissolved organic carbon degradation experiments

    Science.gov (United States)

    Pastor, Ada; Catalán, Núria; Gutiérrez, Carmen; Nagar, Nupur; Casas-Ruiz, Joan P.; Obrador, Biel; von Schiller, Daniel; Sabater, Sergi; Petrovic, Mira; Borrego, Carles M.; Marcé, Rafael

    2017-04-01

    Dissolved organic carbon (DOC) is the largest biologically available pool of organic carbon in aquatic ecosystems and its degradation along the land-to-ocean continuum has implications for carbon cycling from local to global scales. DOC biodegradability is usually assessed by incubating filtered water inoculated with native microbial assemblages in the laboratory. However, the use of a native inoculum from several freshwaters, without having a microbial-tailored design, hampers our ability to tease apart the relative contribution of the factors driving DOC degradation from the effects of local microbial communities. The use of a standard microbial inoculum would allow researchers to disentangle the drivers of DOC degradation from the metabolic capabilities of microbial communities operating in situ. With this purpose, we designed a bacterial inoculum to be used in experiments of DOC degradation in freshwater habitats. The inoculum is composed of six bacterial strains that easily grow under laboratory conditions, possess a versatile metabolism and are able to grow under both aerobic and anaerobic conditions. The mixed inoculum showed higher DOC degradation rates than those from their isolated bacterial components and the consumption of organic substrates was consistently replicated. Moreover, DOC degradation rates obtained using the designed inoculum were responsive across a wide range of natural water types differing in DOC concentration and composition. Overall, our results show the potential of the designed inoculum as a tool to discriminate between the effects of environmental drivers and intrinsic properties of DOC on degradation dynamics.

  5. Comparison of the chemical composition of dissolved organic matter in three lakes in Minnesota

    Science.gov (United States)

    Cao, Xiaoyan; Aiken, George R.; Butler, Kenna D.; Mao, Jingdong; Schmidt-Rohr, Klaus

    2018-01-01

    New information on the chemical composition of dissolved organic matter (DOM) in three lakes in Minnesota has been gained from spectral editing and two-dimensional nuclear magnetic resonance (NMR) methods, indicating the effects of lake hydrological settings on DOM composition. Williams Lake (WL), Shingobee Lake (SL), and Manganika Lake (ML) had different source inputs, and the lake water residence time (WRT) of WL was markedly longer than that of SL and ML. The hydrophobic organic acid (HPOA) and transphilic organic acid (TPIA) fractions combined comprised >50% of total DOM in these lakes, and contained carboxyl-rich alicyclic molecules (CRAM), aromatics, carbohydrates, and N-containing compounds. The previously understudied TPIA fractions contained fewer aromatics, more oxygen-rich CRAM, and more N-containing compounds compared to the corresponding HPOA. CRAM represented the predominant component in DOM from all lakes studied, and more so in WL than in SL and ML. Aromatics including lignin residues and phenols decreased in relative abundances from ML to SL and WL. Carbohydrates and N-containing compounds were minor components in both HPOA and TPIA and did not show large variations among the three lakes. The increased relative abundances of CRAM in DOM from ML, SL to WL suggested the selective preservation of CRAM with increased residence time.

  6. Microbial decomposition of marine dissolved organic matter in cool oceanic crust

    Science.gov (United States)

    Shah Walter, Sunita R.; Jaekel, Ulrike; Osterholz, Helena; Fisher, Andrew T.; Huber, Julie A.; Pearson, Ann; Dittmar, Thorsten; Girguis, Peter R.

    2018-05-01

    Marine dissolved organic carbon (DOC) is one of the largest active reservoirs of reduced carbon on Earth. In the deep ocean, DOC has been described as biologically recalcitrant and has a radiocarbon age of 4,000 to 6,000 years, which far exceeds the timescale of ocean overturning. However, abiotic removal mechanisms cannot account for the full magnitude of deep-ocean DOC loss. Deep-ocean water circulates at low temperatures through volcanic crust on ridge flanks, but little is known about the associated biogeochemical processes and carbon cycling. Here we present analyses of DOC in fluids from two borehole observatories installed in crustal rocks west of the Mid-Atlantic Ridge, and show that deep-ocean DOC is removed from these cool circulating fluids. The removal mechanism is isotopically selective and causes a shift in specific features of molecular composition, consistent with microbe-mediated oxidation. We suggest organic molecules with an average radiocarbon age of 3,200 years are bioavailable to crustal microbes, and that this removal mechanism may account for at least 5% of the global loss of DOC in the deep ocean. Cool crustal circulation probably contributes to maintaining the deep ocean as a reservoir of `aged' and refractory DOC by discharging the surviving organic carbon constituents that are molecularly degraded and depleted in 14C and 13C into the deep ocean.

  7. Experimental investigation and modeling of dissolved organic carbon removal by coagulation from seawater.

    Science.gov (United States)

    Jeong, Sanghyun; Sathasivan, Arumugam; Kastl, George; Shim, Wang Geun; Vigneswaran, Saravanamuthu

    2014-01-01

    Coagulation removes colloidal matters and dissolved organic carbon (DOC) which can cause irreversible membrane fouling. However, how DOC is removed by coagulant is not well-known. Jar test was used to study the removal of hydrophobic and hydrophilic DOC fractions at various doses (0.5-8.0 mg-Fe(+3) L(-1)) of ferric chloride (FeCl3) and pH (5.0-9.0). Natural organic matter (NOM) in seawater and treated seawater were fractionated by liquid chromatography-organic carbon detector (LC-OCD). Compared to surface water, the removal of DOC in seawater by coagulation was remarkably different. Majority of DOC could be easily removed with very low coagulant dose (fraction (HB) was better removed at high pH while hydrophilic fraction (HF) was better removed at low pH. A modified model of Kastl et al. (2004) which assumed that the removal occurred by adsorption of un-dissociated compounds onto ferric hydroxide was formulated and successfully validated against the jar test data. Copyright © 2013 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 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

    Directory of Open Access Journals (Sweden)

    Cheng Niu

    2014-06-01

    Full Text Available 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 < 0.001, fluorescence intensities (Ex./Em. 370/460 nm (r2 = 0.91, p < 0.001, the fluorescence index (r2 = 0.88, p < 0.001 and the humification index (r2 = 0.78, p < 0.001, suggesting that 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 < 0.001, indicating that in situ 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 < 0.001, TP (r2 = 0.82, p < 0.001 concentrations, suggesting a potential further application for the real-time monitoring of water quality using an in situ CDOM fluorescence sensor.

  10. A global hotspot for dissolved organic carbon in hypermaritime watersheds of coastal British Columbia

    Directory of Open Access Journals (Sweden)

    A. A. Oliver

    2017-08-01

    Full Text Available The perhumid region of the coastal temperate rainforest (CTR of Pacific North America is one of the wettest places on Earth and contains numerous small catchments that discharge freshwater and high concentrations of dissolved organic carbon (DOC directly to the coastal ocean. However, empirical data on the flux and composition of DOC exported from these watersheds are scarce. We established monitoring stations at the outlets of seven catchments on Calvert and Hecate islands, British Columbia, which represent the rain-dominated hypermaritime region of the perhumid CTR. Over several years, we measured stream discharge, stream water DOC concentration, and stream water dissolved organic-matter (DOM composition. Discharge and DOC concentrations were used to calculate DOC fluxes and yields, and DOM composition was characterized using absorbance and fluorescence spectroscopy with parallel factor analysis (PARAFAC. The areal estimate of annual DOC yield in water year 2015 was 33.3 Mg C km−2 yr−1, with individual watersheds ranging from an average of 24.1 to 37.7 Mg C km−2 yr−1. This represents some of the highest DOC yields to be measured at the coastal margin. We observed seasonality in the quantity and composition of exports, with the majority of DOC export occurring during the extended wet period (September–April. Stream flow from catchments reacted quickly to rain inputs, resulting in rapid export of relatively fresh, highly terrestrial-like DOM. DOC concentration and measures of DOM composition were related to stream discharge and stream temperature and correlated with watershed attributes, including the extent of lakes and wetlands, and the thickness of organic and mineral soil horizons. Our discovery of high DOC yields from these small catchments in the CTR is especially compelling as they deliver relatively fresh, highly terrestrial organic matter directly to the coastal ocean. Hypermaritime landscapes are common on the

  11. A global hotspot for dissolved organic carbon in hypermaritime watersheds of coastal British Columbia

    Science.gov (United States)

    Oliver, Allison A.; Tank, Suzanne E.; Giesbrecht, Ian; Korver, Maartje C.; Floyd, William C.; Sanborn, Paul; Bulmer, Chuck; Lertzman, Ken P.

    2017-08-01

    The perhumid region of the coastal temperate rainforest (CTR) of Pacific North America is one of the wettest places on Earth and contains numerous small catchments that discharge freshwater and high concentrations of dissolved organic carbon (DOC) directly to the coastal ocean. However, empirical data on the flux and composition of DOC exported from these watersheds are scarce. We established monitoring stations at the outlets of seven catchments on Calvert and Hecate islands, British Columbia, which represent the rain-dominated hypermaritime region of the perhumid CTR. Over several years, we measured stream discharge, stream water DOC concentration, and stream water dissolved organic-matter (DOM) composition. Discharge and DOC concentrations were used to calculate DOC fluxes and yields, and DOM composition was characterized using absorbance and fluorescence spectroscopy with parallel factor analysis (PARAFAC). The areal estimate of annual DOC yield in water year 2015 was 33.3 Mg C km-2 yr-1, with individual watersheds ranging from an average of 24.1 to 37.7 Mg C km-2 yr-1. This represents some of the highest DOC yields to be measured at the coastal margin. We observed seasonality in the quantity and composition of exports, with the majority of DOC export occurring during the extended wet period (September-April). Stream flow from catchments reacted quickly to rain inputs, resulting in rapid export of relatively fresh, highly terrestrial-like DOM. DOC concentration and measures of DOM composition were related to stream discharge and stream temperature and correlated with watershed attributes, including the extent of lakes and wetlands, and the thickness of organic and mineral soil horizons. Our discovery of high DOC yields from these small catchments in the CTR is especially compelling as they deliver relatively fresh, highly terrestrial organic matter directly to the coastal ocean. Hypermaritime landscapes are common on the British Columbia coast, suggesting that

  12. Spatial distribution of soils determines export of nitrogen and dissolved organic carbon from an intensively managed agricultural landscape

    DEFF Research Database (Denmark)

    Wohlfart, T; Exbrayat, J-F; Schelde, Kirsten

    2012-01-01

    nitrogen (TDN), nitrate (NO3−), ammonium nitrogen and dissolved organic carbon (DOC) concentrations were measured, and dissolved organic nitrogen (DON) was calculated for each grabbed sample. Electrical conductivity, pH and flow velocity were measured during sampling. Statistical analyses showed...... significant differences between the northern, southern and converged stream parts, especially for NO3− concentrations with average values between 1.4 mg N l−1 and 9.6 mg N l−1. Furthermore, throughout the sampling period DON concentrations increased to 2.8 mg N l−1 in the northern stream contributing up to 81...

  13. Dissolved Organic Matter Composition and Export from U.S. Rivers

    Science.gov (United States)

    Aiken, G.; Butman, D. E.; Spencer, R. G.; Raymond, P.

    2012-12-01

    Dissolved organic matter (DOM) chemistry and flux are potentially useful indicators of watershed characteristics, climate influences on watershed hydrology and soils, and changes associated with water and land resource management. Organic source materials, watershed geochemistry, oxidative processes and hydrology strongly influence the nature and reactivity of DOM in aquatic systems. The molecules that comprise DOM, in turn, control a number of environmental processes important for ecosystem function including light penetration and photochemistry, microbial activity, mineral dissolution/precipitation, and the transport and reactivity of hydrophobic compounds and metals. In particular, aromatic molecules derived from higher plants exert strong controls on aquatic photochemistry, and on the transport and biogeochemistry of metals. Assessment of DOM composition and transport, therefore, can provide a basis for understanding watershed processes and biogeochemistry of rivers and streams. Here we present results of a multi-year study designed to assess the seasonal and spatial variability of DOM quantity and quality for 15 large North American river basins. Samples were collected from the mouths of the rivers using a sampling program designed to capture hydrologic and seasonal variability of DOM export. DOM concentrations and composition, based on DOM fractionation on XAD resins, chromophoric dissolved organic matter (CDOM) parameters (ultraviolet /visible absorption and fluorescence spectroscopy), specific compound analyses, and DO14C content varied greatly both between sites and seasonally within a given site. DOM in these rivers exhibited a wide range of concentration and carbon specific ultra-violet absorbance at 254 nm (SUVA254), an optical measurement that is an indicator of DOM aromatic carbon content. In almost all systems, CDOM optical parameters correlated strongly with DOC concentration and hydrophobic organic acid (HPOA) content (aquatic humic substances). In

  14. Reclamation of zinc-contaminated soil using a dissolved organic carbon solution prepared using liquid fertilizer from food-waste composting.

    Science.gov (United States)

    Chiang, Po-Neng; Tong, Ou-Yang; Chiou, Chyow-San; Lin, Yu-An; Wang, Ming-Kuang; Liu, Cheng-Chung

    2016-01-15

    A liquid fertilizer obtained through food-waste composting can be used for the preparation of a dissolved organic carbon (DOC) solution. In this study, we used the DOC solutions for the remediation of a Zn-contaminated soil (with Zn concentrations up to 992 and 757 mg kg(-1) in topsoil and subsoil, respectively). We then determined the factors that affect Zn removal, such as pH, initial concentration of DOC solution, and washing frequency. Measurements using a Fourier Transform infrared spectrometer (FT-IR) revealed that carboxyl and amide were the major functional groups in the DOC solution obtained from the liquid fertilizer. Two soil washes using 1,500 mg L(-1) DOC solution with a of pH 2.0 at 25°C removed about 43% and 21% of the initial Zn from the topsoil and subsoil, respectively. Following this treatment, the pH of the soil declined from 5.4 to 4.1; organic matter content slightly increased from 6.2 to 6.5%; available ammonium (NH4(+)-N) content increased to 2.4 times the original level; and in the topsoil, the available phosphorus content and the exchangeable potassium content increased by 1.65 and 2.53 times their initial levels, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Low acetate concentrations favor polyphosphate-accumulating organisms over glycogen-accumulating organisms in enhanced biological phosphorus removal from wastewater.

    Science.gov (United States)

    Tu, Yunjie; Schuler, Andrew J

    2013-04-16

    Glycogen-accumulating organisms (GAOs) are thought to compete with polyphosphate-accumulating organisms (PAOs) in enhanced biological phosphorus removal (EBPR) wastewater treatment systems. A laboratory sequencing batch reactor (SBR) was operated for one year to test the hypothesis that PAOs have a competitive advantage at low acetate concentrations, with a focus on low pH conditions previously shown to favor GAOs. PAOs dominated the system under conventional SBR operation with rapid acetate addition (producing high in-reactor concentrations) and pH values of 7.4-8.4. GAOs dominated when the pH was decreased (6.4-7.0). Decreasing the acetate addition rate led to very low reactor acetate concentrations, and PAOs recovered, supporting the study hypothesis. When the acetate feed rate was increased, EBPR failed again. Dominant PAOs and GAOs were Candidatus Accumulibacter phosphatis and Defluviicoccus Cluster 2, respectively, according to fluorescent in situ hybridization and 454 pyrosequencing. Surprisingly, GAOs were not the immediate causes of PAO failures, based on functional and population measurements. Pyrosequencing results suggested Dechloromonas and Tetrasphaera spp. may have also been PAOs, and additional potential GAOs were also identified. Full-scale systems typically have lower in-reactor acetate concentrations than laboratory SBRs, and so, previous laboratory studies may have overestimated the practical importance of GAOs as causes of EBPR failure.

  16. The Effect of Organic Phosphorus and Nitrogen Enriched Manure on Nutritive Value of Sweet Corn Stover

    Science.gov (United States)

    Lukiwati, D. R.; Pujaningsih, R. I.; Murwani, R.

    2018-02-01

    The experiment aimed to evaluate the effect of some manure enriched with phosphorus (P) and nitrogen (N) organic (‘manure plus’) on crude protein and mineral production of sweet corn (Zea mays saccharata)and quality of fermented stover as livestock feed. A field experiment was conducted on a vertisol soil (low pH, nitrogen and low available Bray II extractable P). Randomized block design with 9 treatments in 3 replicates was used in this experiment. The treatments were T1(TSP), T2 (SA), T3 (TSP+SA), T4 (manure), T5 (manure+PR), T6 (manure+guano), T7 (manure+N-legume), T8 (manure+PR+N-legume), T9 (manure +guano+N-legume). Data were analyzed using analysis of variance (ANOVA) and the differences between treatment means were examined by Duncan Multiple Range Test (DMRT). Results of the experiment showed that the treatment significantly affected to the crude protein and calcium production of stover and nutrient concentration of fermented stover, but it is not affected to P production of stover. The result of DMRT showed that the effect of ‘manure plus’ was not significantly different on CP and Ca production of stover, mineral concentration, in vitro DMD and OMD of fermented stover, compared to inorganic fertilization. Conclusion, manure enriched with organic NP, resulted in similar on CP and Ca production of stover and nutrient concentration of fermented stover compared to inorganic fertilizer. Thus, organic-NP enriched manure could be an alternative and viable technology to utilize low grade of phosphate rock, guano and Gliricidea sepium to produce sweet corn in vertisol soil.

  17. GROWTH AND LEVELS OF N, P AND K IN ROOTSTOCKS OF TAMARIND TREES USING ORGANIC SUBSTRATES AND DOSES OF PHOSPHORUS

    Directory of Open Access Journals (Sweden)

    EDUARDO CASTRO PEREIRA

    2016-01-01

    Full Text Available The aim of this study was to evaluate different organic substrates and phosphorus doses on the growth and leaf content of nitrogen, phosphorus and potassium in rootstocks of Tamarindus indica L. The experiment was performed in a greenhouse nursery located on the campus of the Universidade Federal Rural do Semi-Árido (UFERSA, from March to October 2013. The treatments consisted of three organic sources at a concentration of 40% (v/v (bovine manure, goat manure and a commercial organic compound and four doses of simple superphosphate (0, 0 kg m-3, 2.5 kg m-3, 5.0 kg m-3 and 7.5 kg m-3. The experiment was conducted in a randomized block design (RBD, with 12 treatments (substrates, four replications and 10 plants per plot, totaling 480 plants. The goat manure and the organic compound were the most suitable treatments for the production of rootstocks of the tamarind tree. The maximum dose of 7.5 g kg-1 of simple superphosphate caused the highest levels of phosphorus and potassium in the dry mass of shoots. The nutrients in the dry matter of shoots accumulated in the following order: N > K > P.

  18. The role of dissolved organic matters in the aquatic photodegradation of atenolol

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Chao; Ji, Yuefei; Zhou, Lei; Zhang, Ya [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China); Yang, Xi, E-mail: yangxi@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer The main reactive species in the photosensitization between atenolol and DOMs is {center_dot}OH. Black-Right-Pointing-Pointer Dissolved organic matter (DOM) can quench {center_dot}OH and screen light. Black-Right-Pointing-Pointer High yield of {center_dot}OH was observed with iron ions and DOM coexisting under irradiation. Black-Right-Pointing-Pointer SRFA can promote addition of {center_dot}OH on aromatic ring. - Abstract: Atenolol (ATL) is a photostable and hydrolysis resistant beta-blocker and has been frequently detected in natural water. In this study, mechanism on aquatic photodegradation of ATL was investigated with an emphasis on the role of dissolved organic matters (DOMs) as well as other natural water compositions (nitrate, bicarbonate and ferric ions). Significant acceleration of photodegradtion of ATL was observed in the presence of each DOMs added, namely Suwannee River Fulvic Acid (SRFA), Suwannee River Humic Acid (SRHA), Nordic Lake Fulvic Acid (NOFA) and Nordic Lake Humic Acid (NOHA). Hydroxyl radical ({center_dot}OH) was determined as the main reactive species in this process, instead of singlet oxygen or excited triplet of DOM. Addition of these four DOMs all inhibited photodegradation of ATL in nitrate solutions through reducing nitrated-derived {center_dot}OH and screening photons absorbed by nitrate. No loss of ATL was detected in bicarbonate solution with or without DOMs. Bicarbonate exhibited a scavenger of {center_dot}OH derived from DOMs. However, in the presence of iron species, photodegradation of ATL was significantly enhanced by the addition of each DOM, due to the high yield of {center_dot}OH in the photoprocess of Fe(III)-DOM complex. The photoproducts distribution of ATL demonstrated that SRFA promote the hydroxylation on aromatic ring in the presence of nitrate and reduce the ketone moiety to alcohol in the system of ferric ions. Our findings indicate that DOMs should be considered in

  19. Pan-arctic trends in terrestrial dissolved organic matter from optical measurements

    Directory of Open Access Journals (Sweden)

    Paul James Mann

    2016-03-01

    Full Text Available Climate change is causing extensive warming across arctic regions resulting in permafrost degradation, alterations to regional hydrology, and shifting amounts and composition of dissolved organic matter (DOM transported by streams and rivers. Here, we characterize the DOM composition and optical properties of the six largest arctic rivers draining into the Arctic Ocean to examine the ability of optical measurements to provide meaningful insights into terrigenous carbon export patterns and biogeochemical cycling. The chemical composition of aquatic DOM varied with season, spring months were typified by highest lignin phenol and dissolved organic carbon (DOC concentrations with greater hydrophobic acid content, and lower proportions of hydrophilic compounds, relative to summer and winter months. Chromophoric DOM (CDOM spectral slope (S275-295 tracked seasonal shifts in DOM composition across river basins. Fluorescence and parallel factor analysis identified seven components across the six Arctic rivers. The ratios of ‘terrestrial humic-like’ versus ‘marine humic-like’ fluorescent components co-varied with lignin monomer ratios over summer and winter months, suggesting fluorescence may provide information on the age and degradation state of riverine DOM. CDOM absorbance (a350 proved a sensitive proxy for lignin phenol concentrations across all six river basins and over the hydrograph, enabling for the first time the development of a single pan-arctic relationship between a350 and terrigenous DOC (R2 = 0.93. Combining this lignin proxy with high-resolution monitoring of a350, pan-arctic estimates of annual lignin flux were calculated to range from 156 to 185 Gg, resulting in shorter and more constrained estimates of terrigenous DOM residence times in the Arctic Ocean (spanning 7 months to 2½ years. Furthermore, multiple linear regression models incorporating both absorbance and fluorescence variables proved capable of explaining much of the

  20. Response Characteristics of Dissolved Organic Carbon Flushing in a Subarctic Alpine Catchment

    Science.gov (United States)

    Carey, S. K.

    2002-12-01

    Dissolved organic carbon (DOC) is an important part of ecosystem-scale carbon balances and in the transport of contaminants as it interacts with other dissolved substances including trace metals. It also can be used as a surrogate hydrological tracer in permafrost regions as near-surface waters are often DOC enriched due to the presence of thick organic soils. In a small subarctic alpine catchment within the Wolf Creek Research Basin, Yukon, Canada, DOC was studied in the summer of 2001 and spring of 2002 to determine the role frost (both permanent and seasonal), snowmelt and summer storms on DOC flushing. Peak DOC concentrations occurred during the snowmelt period, approximately one week prior to peak discharge. However, peak discharge took place several weeks after snow on south facing exposures had melted. Within the hillslopes, DOC concentrations were three to five times greater in wells underlain with permafrost compared with seasonal frost. Groundwater DOC concentrations declined during snowmelt, yet remained at levels above the streamflow. After peaking, streamflow DOC concentrations declined exponentially suggesting a simple flushing mechanism, however there did not appear to be a relation between DOC and topographic position. Following melt, permafrost underlain slopes had near-surface water tables and retained elevated levels of DOC, whereas slopes without permafrost had rapidly declining water tables at upslope locations with low DOC concentrations at all positions except near-stream riparian zones. The influence of summer rainstorms on DOC was monitored on three occasions. In each case DOC peaked on the ascending limb of the runoff hydrograph and declined exponentially on the receding limb and hysteretic behavior occurred between discharge and DOC during all events. Patterns of DOC within the hillslopes and streams suggest that runoff from permafrost-underlain slopes control DOC flushing within the stream during both snowmelt and summer periods. This

  1. Pan-arctic trends in terrestrial dissolved organic matter from optical measurements

    Science.gov (United States)

    Mann, Paul; Spencer, Robert; Hernes, Peter; Six, Johan; Aiken, George; Tank, Suzanne; McClelland, James; Butler, Kenna; Dyda, Rachael; Holmes, Robert

    2016-03-01

    Climate change is causing extensive warming across arctic regions resulting in permafrost degradation, alterations to regional hydrology, and shifting amounts and composition of dissolved organic matter (DOM) transported by streams and rivers. Here, we characterize the DOM composition and optical properties of the six largest arctic rivers draining into the Arctic Ocean to examine the ability of optical measurements to provide meaningful insights into terrigenous carbon export patterns and biogeochemical cycling. The chemical composition of aquatic DOM varied with season, spring months were typified by highest lignin phenol and dissolved organic carbon (DOC) concentrations with greater hydrophobic acid content, and lower proportions of hydrophilic compounds, relative to summer and winter months. Chromophoric DOM (CDOM) spectral slope (S275-295) tracked seasonal shifts in DOM composition across river basins. Fluorescence and parallel factor analysis identified seven components across the six Arctic rivers. The ratios of 'terrestrial humic-like' versus 'marine humic-like' fluorescent components co-varied with lignin monomer ratios over summer and winter months, suggesting fluorescence may provide information on the age and degradation state of riverine DOM. CDOM absorbance (a350) proved a sensitive proxy for lignin phenol concentrations across all six river basins and over the hydrograph, enabling for the first time the development of a single pan-arctic relationship between a350 and terrigenous DOC (R2 = 0.93). Combining this lignin proxy with high-resolution monitoring of a350, pan-arctic estimates of annual lignin flux were calculated to range from 156 to 185 Gg, resulting in shorter and more constrained estimates of terrigenous DOM residence times in the Arctic Ocean (spanning 7 months to 2½ years). Furthermore, multiple linear regression models incorporating both absorbance and fluorescence variables proved capable of explaining much of the variability in

  2. Spatiotemporal drivers of dissolved organic matter in high alpine lakes: Role of Saharan dust inputs and bacterial activity.

    Science.gov (United States)

    Mladenov, Natalie; Pulido-Villena, Elvira; Morales-Baquero, Rafael; Ortega-Retuerta, Eva; Sommaruga, Ruben; Reche, Isabel

    2008-01-01

    The effects of many environmental stressors such as UV radiation are mediated by dissolved organic matter (DOM) properties. Therefore, determining the factors shaping spatial and temporal patterns is particularly essential in the most susceptible, low dissolved organic carbon (DOC) lakes. We analyzed spatiotemporal variations in dissolved organic carbon concentration and dissolved organic matter optical properties (absorption and fluorescence) in 11 transparent lakes located above tree line in the Sierra Nevada Mountains (Spain), and we assessed potential external (evaporation and atmospheric deposition) and internal (bacterial abundance, bacterial production, chlorophyll a, and catchment vegetation) drivers of DOM patterns. At spatial and temporal scales, bacteria were related to chromophoric DOM (CDOM). At the temporal scale, water soluble organic carbon (WSOC) in dust deposition and evaporation were found to have a significant influence on DOC and CDOM in two Sierra Nevada lakes studied during the ice-free periods of 2000-2002. DOC concentrations and absorption coefficients at 320 nm were strongly correlated over the spatial scale (n = 11, R(2) = 0.86; p DOC concentration and CDOM to these factors. At the continental scale, higher mean DOC concentrations and more CDOM in lakes of the Sierra Nevada than in lakes of the Pyrenees and Alps may be due to a combination of more extreme evaporation, and greater atmospheric dust deposition.

  3. Leaching of chloride, sulphate, heavy metals, dissolved organic carbon and phenolic organic pesticides from contaminated concrete.

    Science.gov (United States)

    Van Praagh, M; Modin, H

    2016-10-01

    Concrete samples from demolition waste of a former pesticide plant in Sweden were analysed for total contents and leachate concentrations of potentially hazardous inorganic substances, TOC, phenols, as well as for pesticide compounds such as phenoxy acids, chlorophenols and chlorocresols. Leachates were produced by means of modified standard column leaching tests and pH-stat batch tests. Due to elevated contents of chromium and lead, as well as due to high chloride concentrations in the first leachate from column tests at L/S 0.1, recycling of the concrete as a construction material in groundworks is likely to be restricted according to Swedish guidelines. The studied pesticide compounds appear to be relatively mobile at the materials own pH>12, 12, 9 and 7. Potential leaching of pesticide residues from recycled concrete to ground water and surface water might exceed water quality guidelines for the remediation site and the EU Water Framework Directive. Results of this study stress the necessity to systematically study the mechanism behind mobility of organic contaminants from alkaline construction and demolition wastes rather than rely on total content limit values. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Using fluorescent dissolved organic matter to trace and distinguish the origin of Arctic surface waters

    Science.gov (United States)

    Gonçalves-Araujo, Rafael; Granskog, Mats A.; Bracher, Astrid; Azetsu-Scott, Kumiko; Dodd, Paul A.; Stedmon, Colin A.

    2016-01-01

    Climate change affects the Arctic with regards to permafrost thaw, sea-ice melt, alterations to the freshwater budget and increased export of terrestrial material to the Arctic Ocean. The Fram and Davis Straits represent the major gateways connecting the Arctic and Atlantic. Oceanographic surveys were performed in the Fram and Davis Straits, and on the east Greenland Shelf (EGS), in late summer 2012/2013. Meteoric (fmw), sea-ice melt, Atlantic and Pacific water fractions were determined and the fluorescence properties of dissolved organic matter (FDOM) were characterized. In Fram Strait and EGS, a robust correlation between visible wavelength fluorescence and fmw was apparent, suggesting it as a reliable tracer of polar waters. However, a pattern was observed which linked the organic matter characteristics to the origin of polar waters. At depth in Davis Strait, visible wavelength FDOM was correlated to apparent oxygen utilization (AOU) and traced deep-water DOM turnover. In surface waters FDOM characteristics could distinguish between surface waters from eastern (Atlantic + modified polar waters) and western (Canada-basin polar waters) Arctic sectors. The findings highlight the potential of designing in situ multi-channel DOM fluorometers to trace the freshwater origins and decipher water mass mixing dynamics in the region without laborious samples analyses. PMID:27667721

  5. The Impact of Extreme Weather Events on Dissolved Organic Matter and Microbial Biomass of chernozem soils

    Science.gov (United States)

    Müller, Ann-Christin; Blagodatskaya, Evgenia

    2017-04-01

    The aim of this experiment was to study the impact of the extreme weather events freezing-thawing and drying-rewetting on C-, N- and P-dynamics in dissolved organic matter and microbial biomass. The three variants of a chernozem soil (Voronezh region, Russia) are (1) fertilized maize cropping, (2) unfertilized maize cropping and (3) a bare fallow. After both abiotic perturbations the respiration rates were generally lower in the freezing-thawing than in the drying-rewetting treatment, due to the lower temperature. The elevated respiration came along with the decay of organic matter, which was also manifested in increased mineralization of C, N and P immediately after rewetting. However, freezing-thawing had significantly less impact on C-, N- and P-mobilization. We conclude that drying-rewetting leads to an initially increased mobilization of C, N and P, which becomes obvious as increased amounts of DOM immediately after rewetting. Freezing-thawing does not affect mobilization in the same way. There, only an increased mobilization of C can be observed. Especially concerning N and P, the reaction is dependent on the form of use/cropping in both treatments.

  6. Selective Leaching of Dissolved Organic Matter From Alpine Permafrost Soils on the Qinghai-Tibetan Plateau

    Science.gov (United States)

    Wang, Yinghui; Xu, Yunping; Spencer, Robert G. M.; Zito, Phoebe; Kellerman, Anne; Podgorski, David; Xiao, Wenjie; Wei, Dandan; Rashid, Harunur; Yang, Yuanhe

    2018-03-01

    Ongoing global temperature rise has caused significant thaw and degradation of permafrost soils on the Qinghai-Tibetan Plateau (QTP). Leaching of organic matter from permafrost soils to aquatic systems is highly complex and difficult to reproduce in a laboratory setting. We collected samples from natural seeps of active and permafrost layers in an alpine swamp meadow on the QTP to shed light on the composition of mobilized dissolved organic matter (DOM) by combining optical measurements, ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry, radiocarbon (14C), and solid-state 13C nuclear magnetic resonance spectroscopy. Our results show that even though the active layer soils contain large amounts of proteins and carbohydrates, there is a selective release of aromatic components, whereas in the deep permafrost layer, carbohydrate and protein components are preferentially leached during the thawing process. Given these different chemical characteristics of mobilized DOM, we hypothesize that photomineralization contributes significantly to the loss of DOM that is leached from the seasonally thawed surface layer. However, with continued warming, biodegradation will become more important since biolabile materials such as protein and carbohydrate are preferentially released from deep-layer permafrost soils. This transition in DOM leachate source and associated chemical composition has ramifications for downstream fluvial networks on the QTP particularly in terms of processing of carbon and associated fluxes.

  7. Land-based salmon aquacultures change the quality and bacterial degradation of riverine dissolved organic matter

    Science.gov (United States)

    Kamjunke, Norbert; Nimptsch, Jorge; Harir, Mourad; Herzsprung, Peter; Schmitt-Kopplin, Philippe; Neu, Thomas R.; Graeber, Daniel; Osorio, Sebastian; Valenzuela, Jose; Carlos Reyes, Juan; Woelfl, Stefan; Hertkorn, Norbert

    2017-03-01

    Aquacultures are of great economic importance worldwide but pollute pristine headwater streams, lakes, and estuaries. However, there are no in-depth studies of the consequences of aquacultures on dissolved organic matter (DOM) composition and structure. We performed a detailed molecular level characterization of aquaculture DOM quality and its bacterial degradation using four salmon aquacultures in Chile. Fluorescence measurements, ultrahigh-resolution mass spectrometry, and nuclear magnetic resonance spectroscopy of the DOM revealed specific and extensive molecular alterations caused by aquacultures. Aquacultures released large quantities of readily bioavailable metabolites (primarily carbohydrates and peptides/proteins, and lipids), causing the organic matter downstream of all the investigated aquacultures to deviate strongly from the highly processed, polydisperse and molecularly heterogeneous DOM found in pristine rivers. However, the upstream individual catchment DOM signatures remained distinguishable at the downstream sites. The benthic algal biovolume decreased and the bacterial biovolume and production increased downstream of the aquacultures, shifting stream ecosystems to a more heterotrophic state and thus impairing the ecosystem health. The bacterial DOM degradation rates explain the attenuation of aquaculture DOM within the subsequent stream reaches. This knowledge may aid the development of improved waste processing facilities and may help to define emission thresholds to protect sensitive stream ecosystems.

  8. Extraordinary slow degradation of dissolved organic carbon (DOC) in a cold marginal sea.

    Science.gov (United States)

    Kim, Tae-Hoon; Kim, Guebuem; Lee, Shin-Ah; Dittmar, Thorsten

    2015-09-08

    Dissolved organic carbon (DOC) is the largest organic carbon reservoir in the ocean, and the amount of carbon in this reservoir rivals that in atmospheric CO2. In general, DOC introduced into the deep ocean undergoes a significant degradation over a centennial time scale (i.e., ~50 μM to ~34 μM in the North Atlantic and Mediterranean Sea). However, we here show that high concentrations of DOC (58 ± 4 μM) are maintained almost constantly over 100 years in the entire deep East/Japan Sea (EJS). The degradation rate in this sea is estimated to be 0.04 μmol C kg(-1) yr(-1), which is 2-3 times lower than that in the North Atlantic and Mediterranean Sea. Since the source of DOC in the deep EJS is found to be of marine origin on the basis of δ(13)C-DOC signatures, this slow degradation rate seems to be due to low temperature (DOC in the world ocean is very sensitive to global warming and slowdown of global deep-water overturning.

  9. Influence of colloidal dissolved organic carbon (DOC) on the sorption of plutonium on natural sediments

    International Nuclear Information System (INIS)

    Nelson, D.M.; Karttunen, J.O.; Mehlhoff, P.

    1982-01-01

    It now appears possible to formulate a practical model to describe the absorption of Pu(IV) by suspended solids. In such a model the constants describing the association of plutonium with both soluble organics and solid adsorbers must be known, as well as any variation in these constants due to solution properties such as pH and ionic strength. If the complexing ability of dissolved organic carbon is sufficiently constant, such a model could describe plutonium behavior in a wide variety of surface and ground waters. Observations to date indicate that the variation in K/sub D/ (K/sub D/ = concentration of Pu(IV) in suspended solids divided by the concentration of Pu(IV) in the water) among water bodies is due primarily to differences in water chemistry and that differences in the character of the absorbing solid are less important. The mathematical relationship and parameter values presented in this report adequately describe the adsorption of Pu(IV) on one-specific sediment

  10. Direct and indirect photolysis of triclocarban in the presence of dissolved organic matter

    Directory of Open Access Journals (Sweden)

    Tamara D. Trouts

    2015-05-01

    Full Text Available Abstract Photolysis is an important attenuation pathway for the removal of wastewater effluent organic micropollutants from surface waters. In this work, direct and indirect processes leading to the degradation of the disinfectant, triclocarban were studied. Photo-irradiation experiments were conducted in water collected from Old Woman Creek (OWC a tributary of Lake Erie near Huron, OH, USA and in solutions of fulvic acids isolated from the Suwannee River, Georgia, USA (SRFA, Old Woman Creek (OWCFA and Pony Lake, Antarctica (PLFA. Photodegradation of triclocarban proceeded faster in the presence of all three fulvic acids relative to deionized water. PLFA, an autochthonous dissolved organic matter (DOM was found to be more reactive than the other fulvic acids, while the mostly allochthonous SRFA exhibited the lowest reactivity toward triclocarban. The later observation can be in part explained by anti-oxidant moieties present in SRFA. Photosensitized triclocarban degradation in whole water DOM from OWC was entirely attributable to the fulvic acid fraction and suggests that this component is the most photo-reactive fraction of the DOM. Anoxic and methanol-quenched experiments revealed unexpected results whereby the former suggests oxidation through reaction with triplet DOM, while the later is indicative of reaction with photo-generated hydroxyl radicals. It is possible that methanol can quench excited DOM species, which would shut down the triplet oxidation pathway. Finally, we observed no enhancement of triclocarban-photosensitized degradation through the addition of iron.

  11. Relationships between Molecular Composition and Optical Properties of Dissolved Organic Matter

    Science.gov (United States)

    Cooper, W. T.; Tfaily, M.; Osborne, D.; Paul, A.; Podgorski, D. C.; Corbett, J.; Chanton, J.

    2009-12-01

    Our focus is on the relationships between the optical properties of dissolved organic matter (DOM) and its molecular composition. For example, we demonstrated that changes in the absorption and fluorescence characteristics of DOM in outwelling from Brazilian mangrove forests correlated with decreases in highly unsaturated organic compounds as DOM was transported from mangrove porewaters to the continental shelf. In that work we combined ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) that provided detailed compositional information with absorption and Excitation/Emission Matrix (EEM) spectroscopy This presentation will highlight new results utilizing the combination of optical spectroscopy and FT-ICR mass spectrometry to illuminate the processes which control DOM cycling. Our focus will be on the contributions of the heteroatom components of DOM (i.e. organic sulfur and organic nitrogen) to its optical properties and how changes in optical properties correlate with important environmental processes like humification and bioavailability. Figure 1 below includes a narrow 0.20 Dalton window from a mass spectrum which demonstrates the ability of ultrahigh resolution mass spectrometry to resolve and identify nitrogen heteroatom compounds in DOM. Our study sites include the Glacial Lake Agassiz Peatlands (GLAP) in northern Minnesota and wetlands in the Caloosahatchee River basin in South Florida. Figure 1. Isolated 0.20 Da window of an ESI-FT-ICR mass spectrum of DOM from a GLAP bog. Labels identify N1 (d,e,f) and N3 classes of nitrogen heteroatoms. The 0.0031 Da mass spacing is used to confirm the N3 class.

  12. Bioavailable dissolved and particulate organic carbon flux from coastal temperate rainforest watersheds

    Science.gov (United States)

    Fellman, J.; Hood, E. W.; D'Amore, D. V.; Moll, A.

    2017-12-01

    Coastal temperate rainforest (CTR) watersheds of southeast Alaska have dense soil carbon stocks ( 300 Mg C ha-1) and high specific discharge (1.5-7 m yr-1) driven by frontal storms from the Gulf of Alaska. As a result, dissolved organic carbon (DOC) fluxes from Alaskan CTR watersheds are estimated to exceed 2 Tg yr-1; however, little is known about the export of particulate organic carbon (POC). The magnitude and bioavailability of this land-to-ocean flux of terrigenous organic matter ultimately determines how much metabolic energy is translocated to downstream and coastal marine ecosystems in this region. We sampled streamwater weekly from May through October from four watersheds of varying landcover (gradient of wetland to glacial coverage) to investigate changes in the concentration and flux of DOC and POC exported to the coastal ocean. We also used headspace analysis of CO2 following 14 day laboratory incubations to determine the flux of bioavailable DOC and POC exported from CTR watersheds. Across all sites, bioavailable DOC concentrations ranged from 0.2 to 1.9 mg L-1 but were on average 0.6 mg L-1. For POC, bioavailable concentrations ranged from below detection to 0.3 mg L-1 but were on average 0.1 mg L-1. The concentration, flux and bioavailability of DOC was higher than for POC highlighting the potential importance of DOC as a metabolic subsidy to downstream and coastal environments. Ratios of DOC to POC decreased during high flow events because the increase in POC concentrations with discharge exceeds that for DOC. Overall, our findings suggest that projected increases in precipitation and storm intensity will drive changes in the speciation, magnitude and bioavailability of the organic carbon flux from CTR watersheds.

  13. Exudation of organic acids by Lupinus albus and Lupinus angustifolius as affected by phosphorus supply

    Science.gov (United States)

    Hentschel, Werner; Wiche, Oliver

    2016-04-01

    In phytomining and phytoremediation research mixed cultures of bioenergy crops with legumes hold promise to enhance availability of trace metals and metalloids in the soil plant system. This is due to the ability of certain legumes to mobilize trace elements during acquisition of nutrients making these elements available for co-cultured species. The legumes achieve this element mobilization by exudating carboxylates and enzymes as well as by lowering the pH value in the rhizosphere. The aim of our research was to determine characteristics and differences in the exudation of Lupinus albus and Lupinus angustifolius regarding to quantitative as to qualitative aspects. Especially the affection by phosphorus (P) supply was a point of interest. Thus we conducted laboratory batch experiments, wherein the plants were grown over four weeks under controlled light, moisture and nutritional conditions on sand as substrate. Half of the plants were supplied with 12 mg P per kg substrate, the other half were cultivated under a total lack of P. After cultivation the plants were transferred from the cultivation substrate into a 0,05 mmolṡL-1 CaCl2 solution. After two hours the plants were removed, moist and dry mass off shoots and roots were measured together with the root length (Tennants' method). Concentrations of exudated carboxylates in the CaCl2 solution were determined via IC (column: Metrosept OrganicAcids, eluent 0.5 molṡL-1 H2SO4 + 15% acetone, pH=3; 0.5 mLṡmin-1). As a result four different organic acids were identified (citric acid, fumaric acid, tartaric acid, malic acid) in concentration ranges of 0.15 mgṡL-1 (fumaric acid) to 9.21 mgṡL-1 (citric acid). Lupinus angustifolius showed a higher exudation rate (in nmol per cm root length per hour) than Lupinus albus in the presence of phosphorus (e.g. regarding citric acid: 1.99 vs 0.64 nmolṡ(gṡh)-1). However, as the root complexity and length of L. albus were far higher than of L. angustifolius, the total

  14. Preliminary investigation of phosphorus adsorption onto two types of iron oxide-organic matter complexes.

    Science.gov (United States)

    Yan, Jinlong; Jiang, Tao; Yao, Ying; Lu, Song; Wang, Qilei; Wei, Shiqiang

    2016-04-01

    Iron oxide (FeO) coated by natural organic matter (NOM) is ubiquitous. The associations of minerals with organic matter (OM) significantly changes their surface properties and reactivity, and thus affect the environmental fate of pollutants, including nutrients (e.g., phosphorus (P)). In this study, ferrihydrite/goethite-humic acid (FH/GE-HA) complexes were prepared and their adsorption characteristics on P at various pH and ionic strength were investigated. The results indicated that the FeO-OM complexes showed a decreased P adsorption capacity in comparison with bare FeO. The maximum adsorption capacity (Qmax) decreased in the order of FH (22.17 mg/g)>FH-HA (5.43 mg/g)>GE (4.67 mg/g)>GE-HA (3.27 mg/g). After coating with HA, the amorphous FH-HA complex still showed higher P adsorption than the crystalline GE-HA complex. The decreased P adsorption observed might be attributed to changes of the FeO surface charges caused by OM association. The dependence of P adsorption on the specific surface area of adsorbents suggests that the FeO component in the complexes is still the main contributor for the adsorption surfaces. The P adsorptions on FeO-HA complexes decreased with increasing initial pH or decreasing initial ionic strength. A strong dependence of P adsorption on ionic strength and pH may demonstrate that outer-sphere complexes between the OM component on the surface and P possibly coexist with inner-sphere surface complexes between the FeO component and P. Therefore, previous over-emphasis on the contributions of original minerals to P immobilization possibly over-estimates the P loading capacity of soils, especially in humic-rich areas. Copyright © 2015. Published by Elsevier B.V.

  15. Effects of natural organic matter on calcium and phosphorus co-precipitation.

    Science.gov (United States)

    Sindelar, Hugo R; Brown, Mark T; Boyer, Treavor H

    2015-11-01

    Phosphorus (P), calcium (Ca) and natural organic matter (NOM) naturally occur in all aquatic ecosystems. However, excessive P loads can cause eutrophic or hyper-eutrophic conditions in these waters. As a result, P regulation is important for these impaired aquatic systems, and Ca-P co-precipitation is a vital mechanism of natural P removal in many alkaline systems, such as the Florida Everglades. The interaction of P, Ca, and NOM is also an important factor in lime softening and corrosion control, both critical processes of drinking water treatment. Determining the role of NOM in Ca-P co-precipitation is important for identifying mechanisms that may limit P removal in both natural and engineered systems. The main goal of this research is to assess the role of NOM in inhibiting Ca and P co-precipitation by: (1) measuring how Ca, NOM, and P concentrations affect NOM's potential inhibition of co-precipitation; (2) determining the effect of pH; and (3) evaluating the precipitated solids. Results showed that Ca-P co-precipitation occurs at pH 9.5 in the presence of high natural organic matter (NOM) (≈30 mg L(-1)). The supersaturation of calcite overcomes the inhibitory effect of NOM seen at lower pH values. Higher initial P concentrations lead to both higher P precipitation rates and densities of P on the calcite surface. The maximum surface density of co-precipitated P on the precipitated calcite surface increases with increasing NOM levels, suggesting that NOM does prevent the co-precipitation of Ca and P. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Spatial and historical distribution of organic phosphorus driven by environment conditions in lake sediments.

    Science.gov (United States)

    Lü, Changwei; He, Jiang; Wang, Bing

    2018-02-01

    The chemistry of sedimentary organic phosphorus (OP) and its fraction distribution in sediments are greatly influenced by environmental conditions such as terrestrial inputs and runoffs. The linkage of OP with environmental conditions was analyzed on the basis of OP spatial and historical distributions in lake sediments. The redundancy analysis and OP spatial distribution results suggested that both NaOH-OP (OP extracted by NaOH) and Re-OP (residual OP) in surface sediments from the selected 13 lakes reflected the gradient effects of environmental conditions and the autochthonous and/or allochthonous inputs driven by latitude zonality in China. The lake level and salinity of Lake Hulun and the runoff and precipitation of its drainage basin were reconstructed on the basis of the geochemistry index. This work showed that a gradient in weather conditions presented by the latitude zonality in China impacts the OP accumulation through multiple drivers and in many ways. The drivers are mainly precipitation and temperature, governing organic matter (OM) production, degradation rate and transportation in the watershed. Over a long temporal dimension (4000years), the vertical distributions of Re-OP and NaOH-OP based on a dated sediment profile from HLH were largely regulated by the autochthonous and/or allochthonous inputs, which depended on the environmental and climate conditions and anthropogenic activities in the drainage basin. This work provides useful environmental geochemistry information to understand the inherent linkage of OP fractionation with environmental conditions and lake evolution. Copyright © 2017. Published by Elsevier B.V.

  17. Optical assessment of colored dissolved organic matter and its related parameters in dynamic coastal water systems

    Science.gov (United States)

    Shanmugam, Palanisamy; Varunan, Theenathayalan; Nagendra Jaiganesh, S. N.; Sahay, Arvind; Chauhan, Prakash

    2016-06-01

    Prediction of the curve of the absorption coefficient of colored dissolved organic matter (CDOM) and differentiation between marine and terrestrially derived CDOM pools in coastal environments are hampered by a high degree of variability in the composition and concentration of CDOM, uncertainties in retrieved remote sensing reflectance and the weak signal-to-noise ratio of space-borne instruments. In the present study, a hybrid model is presented along with empirical methods to remotely determine the amount and type of CDOM in coastal and inland water environments. A large set of in-situ data collected on several oceanographic cruises and field campaigns from different regional waters was used to develop empirical methods for studying the distribution and dynamics of CDOM, dissolved organic carbon (DOC) and salinity. Our validation analyses demonstrated that the hybrid model is a better descriptor of CDOM absorption spectra compared to the existing models. Additional spectral slope parameters included in the present model to differentiate between terrestrially derived and marine CDOM pools make a substantial improvement over those existing models. Empirical algorithms to derive CDOM, DOC and salinity from remote sensing reflectance data demonstrated success in retrieval of these products with significantly low mean relative percent differences from large in-situ measurements. The performance of these algorithms was further assessed using three hyperspectral HICO images acquired simultaneously with our field measurements in productive coastal and lagoon waters on the southeast part of India. The validation match-ups of CDOM and salinity showed good agreement between HICO retrievals and field observations. Further analyses of these data showed significant temporal changes in CDOM and phytoplankton absorption coefficients with a distinct phase shift between these two products. Healthy phytoplankton cells and macrophytes were recognized to directly contribute to the

  18. An intercomparison of three methods for the large-scale isolation of oceanic dissolved organic matter

    Science.gov (United States)

    Green, Nelson W.; Perdue, E. Michael; Aiken, George R.; Butler, Kenna D.; Chen, Hongmei; Dittmar, Thorsten; Niggemann, Jutta; Stubbins, Aron

    2014-01-01

    Dissolved organic matter (DOM) was isolated from large volumes of deep (674 m) and surface (21 m) ocean water via reverse osmosis/electrodialysis (RO/ED) and two solid-phase extraction (SPE) methods (XAD-8/4 and PPL) at the Natural Energy Laboratory of Hawaii Authority (NELHA). By applying the three methods to common water samples, the efficiencies of XAD, PPL and RO/ED DOM isolation were compared. XAD recovered 42% of dissolved organic carbon (DOC) from deep water (25% with XAD-8; 17% with XAD-4) and 30% from surface water (16% with XAD-8; 14% with XAD-4). PPL recovered 61 ± 3% of DOC from deep water and 61% from surface water. RO/ED recovered 82 ± 3% of DOC from deep water, 14 ± 3% of which was recovered in a sodium hydroxide rinse, and 75 ± 5% of DOC from surface water, with 12 ± 2% in the sodium hydroxide rinse. The highest recoveries of all were achieved by the sequential isolation of DOC, first with PPL and then via RO/ED. This combined technique recovered 98% of DOC from a deep water sample and 101% of DOC from a surface water sample. In total, 1.9, 10.3 and 1.6 g-C of DOC were collected via XAD, PPL and RO/ED, respectively. Rates of DOC recovery using the XAD, PPL and RO/ED methods were 10, 33 and 10 mg-C h− 1, respectively. Based upon C/N ratios, XAD isolates were heavily C-enriched compared with water column DOM, whereas RO/ED and PPL ➔ RO/ED isolate C/N values were most representative of the original DOM. All techniques are suitable for the isolation of large amounts of DOM with purities suitable for most advanced analytical techniques. Coupling PPL and RO/ED techniques may provide substantial progress in the search for a method to quantitatively isolate oceanic DOC, bringing the entirety of the DOM pool within the marine chemist's analytical window.

  19. The Influence of Water Circulation on Dissolved Organic Matter Dynamics in Bald Head Creek

    Science.gov (United States)

    Lebrasse, M. C.; Osburn, C. L.; Bohnenstiehl, D. R.; He, R.

    2016-12-01

    Dissolved organic matter (DOM) plays an important role in biogeochemical cycles in estuaries such as tidal creeks draining coastal wetlands such as salt marshes. However, significant knowledge gaps remain regarding the quantity and quality of the DOM that tidally exchanges between salt marshes and their adjacent estuaries. Tidal movements play a central role in lateral exchanges of materials and bidirectional flow results in the mixing of DOM from marsh plants and estuarine DOM. The aim of this study was to better understand the role of water circulation on the distribution and quality of DOM in Bald Head Creek, a tributary to the Cape Fear River estuary in eastern North Carolina. Dissolved organic carbon (DOC) concentration, stable carbon isotopes, and chromophoric DOM (CDOM) absorbance at 254 nm (a254) were used to distinguish between DOM quantity and quality at three locations along the creek: Site 3 (upstream), Site 2 (middle stream), and Site 1 (near the creek mouth). Samples were collected over four tidal cycles between March-August 2016 and compared to time series data collected approximately weekly from 2014-2016. DOM characteristics differed substantially over the tidal cycle. Higher CDOM and DOC concentration were observed at low tide than at high tide at all three sites, suggesting greater export of carbon from the marsh into the creek as the tides recede. Analysis of CDOM quality based on specific UV absorbance at 254 nm (SUVA254) and spectral slope ratio (SR) showed that the marsh end-member (Site 3) source of DOM had greater aromaticity and higher molecular weight. Site 1 showed greater variability over the tidal cycle most likely due to a greater tidal influence, being closer to the mouth. Additionally, an unmanned surface vehicle (USV) and a hydrodynamic model were used to map water circulation and DOC concentration along the creek to compute exchanges with the adjacent estuary. Results suggest that estuarine OM dynamics are strongly controlled by

  20. Molecular signatures of biogeochemical transformations in dissolved organic matter from ten World Rivers

    Directory of Open Access Journals (Sweden)

    Thomas Riedel

    2016-09-01

    Full Text Available Rivers carry large amounts of dissolved organic matter (DOM to the oceans thereby connecting terrestrial and marine element cycles. Photo-degradation in conjunction with microbial turnover is considered a major pathway by which terrigenous DOM is decomposed. To reveal globally relevant patterns behind this process, we performed photo-degradation experiments and year-long bio-assays on DOM from ten of the largest world rivers that collectively account for more than one-third of the fresh water discharge to the global ocean. We furthermore tested the hypothesis that the terrigenous component in deep ocean DOM may be far higher than biomarker studies suggest, because of the selective photochemical destruction of characteristic biomolecules from vascular plants. DOM was molecularly characterized by a combination of non-targeted ultrahigh-resolution mass spectrometry and quantitative molecular tracer analyses. We show that the reactivity of DOM is globally related to broad catchment properties. Basins that are dominated by forest and grassland export more photo-degradable DOM than other rivers. Chromophoric compounds are mainly vascular plant-derived polyphenols, and partially carry a pyrogenic signature from vegetation fires. These forest and grassland dominated rivers lost up to 50% of dissolved organic carbon (DOC during irradiation, and up to 85% of DOC was lost in total if subsequently bio-incubated for one year. Basins covered by cropland, on the other hand, export DOM with a higher proportion of photo-resistant and bio-available DOM which is enriched in nitrogen. In these rivers, 30% or less of DOC was photodegraded. Consistent with previous studies, we found that riverine DOM resembled marine DOM in its broad molecular composition after extensive degradation, mainly due to almost complete removal of aromatics. More detailed molecular fingerprinting analysis (based on the relative abundance of >4000 DOM molecular formulae, however, revealed

  1. Biodegradability of terrigenous dissolved organic matter in estuaries draining glacial and wetland-dominated watersheds

    Science.gov (United States)

    Fellman, J. B.; Hood, E.; Spencer, R. G.; Edwards, R. T.; D'Amore, D. V.; Hernes, P. J.

    2008-12-01

    The processing of terrigenous dissolved organic matter (DOM) by estuarine food webs mediates its transfer from riverine to near-shore coastal environments. We used PARAFAC modeling of fluorescence excitation- emission matrices (EEMs) and biodegradable dissolved organic carbon (BDOC) incubations to investigate changes in the chemical quality and biodegradability of terrigenous DOM along a salinity gradient in three estuaries in coastal southeastern Alaska: 1) a watershed with high glacial coverage, 2) a forested watershed with low glacial coverage and 3) a watershed with high wetland coverage. Biodegradable DOC incubations were conducted for each site by inoculating filtered river water with whole water collected from four different salinities (0, 2, 10 and 25 ppt) and incubating the water samples for 2, 7, 14 and 28 days. The percent BDOC ranged from 33-54% for the 28-day incubations at the three sites and greater than half of the total BDOC was consumed during the first 2 days of the incubations. The percent BDOC was also greater in the estuary draining the highly glaciated watershed for all four salinities. Moreover, percent BDOC increased with increasing salinity in all three estuaries, suggesting greater bacterial utilization of terrigenous DOC under estuarine as compared to riverine conditions. There are several potential explanations for the observed patterns in BDOC: 1) there is a shift in bacterial community composition along the salinity gradient we sampled and 2) marine bacteria contain a more diverse set of hydrolytic isoenzymes than riverine bacteria, allowing them to more effectively metabolize terrigenous DOM. Application of a conservative mixing model combined with PARAFAC modeling of fluorescence EEMs showed that fluorescent DOM behaved conservatively in all three estuaries, as indicated by the near-linear decrease in the contribution of humic-like fluorescence with increasing salinity. PARAFAC modeling further showed that the relative contribution

  2. Production of dissolved organic carbon in forest soils along the north-south European transect

    International Nuclear Information System (INIS)

    Buzek, F.; Paces, T.; Jackova, I.

    2009-01-01

    The aim of this study is to estimate the C loss from forest soils due to the production of dissolved organic C (DOC) along a north-south European transect. Dissolved organic