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Sample records for controlling arsenic mobility

  1. Redox control of arsenic mobilization in Bangladesh groundwater

    International Nuclear Information System (INIS)

    Zheng, Y.; Stute, M.; Geen, A. van; Gavrieli, I.; Dhar, R.; Simpson, H.J.; Schlosser, P.; Ahmed, K.M.

    2004-01-01

    Detailed hydrochemical measurements, δ 34 S SO4 and 3 H analyses were performed on 37 groundwater samples collected during February 1999, January and March 2000 from 6 locations in eastern and southeastern Bangladesh to examine redox processes that lead to As mobilization in groundwater. The study sites were chosen based on available nation-wide As surveys to span the entire spectrum of As concentrations in Bangladesh groundwater, and to represent 3 of 5 major geological units of the Ganges-Brahmaputra Delta: uplifted Pleistocene terrace, fluvial flood plain and delta plain. Arsenic was found to be mobilized under Fe-reducing conditions in shallow aquifers ( 4 -reducing conditions, suggesting that authigenic sulfide precipitation does not constitute a significant sink for As in these groundwaters. The redox state of the water was characterized by a variety of parameters including dissolved O 2 , NO 3 - , Mn 2+ , Fe 2+ concentrations, and SO 4 2- /Cl - ratios. High dissolved [As] (> 50 μg/l; or > 0.7 μM ) were always accompanied by high dissolved [HCO 3 - ] (> 4 mM), and were close to saturation with respect to calcite. Groundwater enriched in As (200-800 μg/l; or 2.7-10.7 μM) and phosphate (30-100 μM) but relatively low in dissolved Fe (5-40 μM) probably resulted from re-oxidation of reducing, As and Fe enriched water. This history was deduced from isotopic signatures of δ 34 S SO4 and 3 H 2 O ( 3 H) to delineate the nature of redox changes for some of the reducing groundwaters. In contrast, As is not mobilized in presumed Pleistocene aquifers, both shallow (30-60 m) and deep (150-270 m), because conditions were not reducing enough due to lack of sufficient O 2 demand

  2. Control of arsenic mobilization in paddy soils by manganese and iron oxides.

    Science.gov (United States)

    Xu, Xiaowei; Chen, Chuan; Wang, Peng; Kretzschmar, Ruben; Zhao, Fang-Jie

    2017-12-01

    Reductive mobilization of arsenic (As) in paddy soils under flooded conditions is an important reason for the relatively high accumulation of As in rice, posing a risk to food safety and human health. The extent of As mobilization varies widely among paddy soils, but the reasons are not well understood. In this study, we investigated As mobilization in six As-contaminated paddy soils (total As ranging from 73 to 122 mg kg -1 ) in flooded incubation and pot experiments. Arsenic speciation in the solution and solid phases were determined. The magnitude of As mobilization into the porewater varied by > 100 times among the six soils. Porewater As concentration correlated closely with the concentration of oxalate-extractable As, suggesting that As associated with amorphous iron (oxyhydr)oxides represents the potentially mobilizable pool of As under flooded conditions. Soil containing a high level of manganese oxides showed the lowest As mobilization, likely because Mn oxides retard As mobilization by slowing down the drop of redox potential upon soil flooding and maintaining a higher arsenate to arsenite ratio in the solid and solution phases. Additions of a synthetic Mn oxide (hausmannite) to two paddy soils increased arsenite oxidation, decreased As mobilization into the porewater and decreased As concentrations in rice grain and straw. Consistent with previous studies using simplified model systems or pure mineral phases, the present study shows that Mn oxides and amorphous Fe (oxyhydr)oxides are important factors controlling reductive As mobilization in As-contaminated paddy soils. In addition, this study also suggests a potential mitigation strategy using exogenous Mn oxides to decrease As uptake by rice in paddy soils containing low levels of indigenous Mn oxides, although further work is needed to verify its efficacy and possible secondary effects under field conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Assessing the mechanisms controlling the mobilization of arsenic in the arsenic contaminated shallow alluvial aquifer in the blackfoot disease endemic area

    International Nuclear Information System (INIS)

    Liao, Vivian Hsiu-Chuan; Chu, Yu-Ju; Su, Yu-Chen; Lin, Po-Cheng; Hwang, Yaw-Huei; Liu, Chen-Wuing; Liao, Chung-Min; Chang, Fi-John; Yu, Chan-Wei

    2011-01-01

    Highlights: ► Sedimentary microcosm showed simultaneous microbial reduction of Fe(III) and As(V). ► Addition of acetate caused a further increase in aqueous Fe(II) but not arsenic. ► An As(V)-reducing bacterium (ARS-3) native to aquifer sediments was isolated. ► ARS-3 showed microbial reduction of As(V) to As(III) in pore water in this aquifer. - Abstract: High levels of arsenic in groundwater and drinking water represent a major health problem worldwide. Drinking arsenic-contaminated groundwater is a likely cause of blackfoot disease (BFD) in Taiwan, but mechanisms controlling the mobilization of arsenic present at elevated concentrations within aquifers remain understudied. Microcosm experiments using sediments from arsenic contaminated shallow alluvial aquifers in the blackfoot disease endemic area showed simultaneous microbial reduction of Fe(III) and As(V). Significant soluble Fe(II) (0.23 ± 0.03 mM) in pore waters and mobilization of As(III) (206.7 ± 21.2 nM) occurred during the first week. Aqueous Fe(II) and As(III) respectively reached concentrations of 0.27 ± 0.01 mM and 571.4 ± 63.3 nM after 8 weeks. We also showed that the addition of acetate caused a further increase in aqueous Fe(II) but the dissolved arsenic did not increase. We further isolated an As(V)-reducing bacterium native to aquifer sediments which showed that the direct enzymatic reduction of As(V) to the potentially more-soluble As(III) in pore water is possible in this aquifer. Our results provide evidence that microorganisms can mediate the release of sedimentary arsenic to groundwater in this region and the capacity for arsenic release was not limited by the availability of electron donors in the sediments.

  4. Assessing the mechanisms controlling the mobilization of arsenic in the arsenic contaminated shallow alluvial aquifer in the blackfoot disease endemic area

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Vivian Hsiu-Chuan, E-mail: vivianliao@ntu.edu.tw [Department of Bioenvironmental Systems Engineering, National Taiwan University, 1 Roosevelt Road, Sec. 4, Taipei 106, Taiwan (China); Chu, Yu-Ju; Su, Yu-Chen; Lin, Po-Cheng [Department of Bioenvironmental Systems Engineering, National Taiwan University, 1 Roosevelt Road, Sec. 4, Taipei 106, Taiwan (China); Hwang, Yaw-Huei [Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, 17 Xu-Zhou Road, Taipei 100, Taiwan (China); Liu, Chen-Wuing; Liao, Chung-Min; Chang, Fi-John; Yu, Chan-Wei [Department of Bioenvironmental Systems Engineering, National Taiwan University, 1 Roosevelt Road, Sec. 4, Taipei 106, Taiwan (China)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer Sedimentary microcosm showed simultaneous microbial reduction of Fe(III) and As(V). Black-Right-Pointing-Pointer Addition of acetate caused a further increase in aqueous Fe(II) but not arsenic. Black-Right-Pointing-Pointer An As(V)-reducing bacterium (ARS-3) native to aquifer sediments was isolated. Black-Right-Pointing-Pointer ARS-3 showed microbial reduction of As(V) to As(III) in pore water in this aquifer. - Abstract: High levels of arsenic in groundwater and drinking water represent a major health problem worldwide. Drinking arsenic-contaminated groundwater is a likely cause of blackfoot disease (BFD) in Taiwan, but mechanisms controlling the mobilization of arsenic present at elevated concentrations within aquifers remain understudied. Microcosm experiments using sediments from arsenic contaminated shallow alluvial aquifers in the blackfoot disease endemic area showed simultaneous microbial reduction of Fe(III) and As(V). Significant soluble Fe(II) (0.23 {+-} 0.03 mM) in pore waters and mobilization of As(III) (206.7 {+-} 21.2 nM) occurred during the first week. Aqueous Fe(II) and As(III) respectively reached concentrations of 0.27 {+-} 0.01 mM and 571.4 {+-} 63.3 nM after 8 weeks. We also showed that the addition of acetate caused a further increase in aqueous Fe(II) but the dissolved arsenic did not increase. We further isolated an As(V)-reducing bacterium native to aquifer sediments which showed that the direct enzymatic reduction of As(V) to the potentially more-soluble As(III) in pore water is possible in this aquifer. Our results provide evidence that microorganisms can mediate the release of sedimentary arsenic to groundwater in this region and the capacity for arsenic release was not limited by the availability of electron donors in the sediments.

  5. Assessing the mechanisms controlling the mobilization of arsenic in the arsenic contaminated shallow alluvial aquifer in the blackfoot disease endemic area.

    Science.gov (United States)

    Liao, Vivian Hsiu-Chuan; Chu, Yu-Ju; Su, Yu-Chen; Lin, Po-Cheng; Hwang, Yaw-Huei; Liu, Chen-Wuing; Liao, Chung-Min; Chang, Fi-John; Yu, Chan-Wei

    2011-12-15

    High levels of arsenic in groundwater and drinking water represent a major health problem worldwide. Drinking arsenic-contaminated groundwater is a likely cause of blackfoot disease (BFD) in Taiwan, but mechanisms controlling the mobilization of arsenic present at elevated concentrations within aquifers remain understudied. Microcosm experiments using sediments from arsenic contaminated shallow alluvial aquifers in the blackfoot disease endemic area showed simultaneous microbial reduction of Fe(III) and As(V). Significant soluble Fe(II) (0.23±0.03 mM) in pore waters and mobilization of As(III) (206.7±21.2 nM) occurred during the first week. Aqueous Fe(II) and As(III) respectively reached concentrations of 0.27±0.01 mM and 571.4±63.3 nM after 8 weeks. We also showed that the addition of acetate caused a further increase in aqueous Fe(II) but the dissolved arsenic did not increase. We further isolated an As(V)-reducing bacterium native to aquifer sediments which showed that the direct enzymatic reduction of As(V) to the potentially more-soluble As(III) in pore water is possible in this aquifer. Our results provide evidence that microorganisms can mediate the release of sedimentary arsenic to groundwater in this region and the capacity for arsenic release was not limited by the availability of electron donors in the sediments. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Arsenic mobilization in the Brahmaputra plains of Assam: groundwater and sedimentary controls.

    Science.gov (United States)

    Sailo, Lalsangzela; Mahanta, Chandan

    2014-10-01

    Arsenic (As) mobilization to the groundwater of Brahmaputra floodplains was investigated in Titabor, Jorhat District, located in the North Eastern part of India. The groundwater and the aquifer geochemistry were characterized in the study area. The range of As concentration in the groundwater varies from 10 to 440 μg/l with mean concentration 210 μg/l. The groundwaters are characterized by high dissolved Fe, Mn, and HCO₃(-) and low concentrations of NO₃(-) and SO₄(2-) indicating the reduced conditions prevailing in the groundwater. In order to understand the actual mobilization processes in the area, six core drilling surrounding the two target tube wells (T1 and T2) with high As concentration (three drill-cores surrounds each tube well closely) was done. The sediment was analyzed its chemical, mineralogical, and elemental compositions. A selective sequential extraction suggested that most of the As in the sediment is bound to Fe oxides fractions (32 to 50%) and the competition for adsorption site by anions (PO₄(3-)) also accounts to significant fractions of the total arsenic extracted. High variability in the extraction as well as properties of the sediment was observed due to the heterogeneity of the sediment samples with different chemical properties. The SEM and EDX results indicate the presence of Fe, Mn coating along with As for most of the sample, and the presence of As associated minerals were calculated using PHREEQC. The mobilization of As into the groundwater was anticipated to be largely controlled by the reductive dissolution of Fe oxides and partly by the competitive anions viz. PO₄(3-).

  7. Simultaneous influence of indigenous microorganism along with abiotic factors controlling arsenic mobilization in Brahmaputra floodplain, India

    Science.gov (United States)

    Sathe, Sandip S.; Mahanta, Chandan; Mishra, Pushpanjali

    2018-06-01

    In the dynamic cycling of oxic and anoxic aqueous alluvial aquifer environments, varying Arsenic (As) concentrations are controlled by both abiotic and biotic factors. Studies have shown a significant form of toxic As (III) being released through the reductive dissolution of iron-oxy/hydroxide minerals and microbial reduction mechanisms, which leads to a serious health concern. The present study was performed in order to assess the abiotic and biotic factors influencing As release into the alluvial aquifer groundwater in Brahmaputra floodplain, India. The groundwater chemistry, characterization of the sediments, isolation, identification and characterization of prominent As releasing indigenous bacterium were conducted. The measured solid and liquid phases of total As concentration were ranged between 0.02 and 17.2 mg kg-1 and 8 to 353 μg L-1, respectively. The morphology and mineralogy showed the presence of detrital and authigenic mineral assemblages whereas primary and secondary As bearing Realgar and Claudetite minerals were identified, respectively. Furthermore, significant non-labile As fraction was found associated with the amorphous oxides of Fe, Mn and Al. The observed groundwater chemistry and sediment color, deduced a sub-oxic reducing aquifer conditions in As-contaminated regions. In addition, 16S rDNA sequencing results of the isolated bacterium showed the prominent Pseudomonas aeruginosa responsible for the mobilization of As, reducing condition, biomineralization and causing grey color to the sediments at the shallower and deeper aquifers in the study area. These findings suggest that microbial metabolic activities are equally responsible in iron-oxy/hydroxide reductive dissolution, controlling As mobilization in dynamic fluvial flood plains.

  8. Arsenic mobilization in sediments

    DEFF Research Database (Denmark)

    Bennett, W. W.; Teasdale, P. R.; Panther, J. G.

    2012-01-01

    We have recently developed Diffusive Gradients in Thin films (DGT) and Diffusive Equilibrium in Thin films (DET) techniques that permit the measurement of high-resolution porewater distributions of As(III), total inorganic arsenic and Fe(II). These novel techniques were utilized to investigate th...

  9. Geochemical and hydrologic controls on the mobilization of arsenic derived from herbicide application

    International Nuclear Information System (INIS)

    Fitzmaurice, Arthur G.; Bilgin, A. Azra; O'Day, Peggy A.; Illera, Virginia; Burris, David R.; Reisinger, H. James; Hering, Janet G.

    2009-01-01

    to JBF sediments may contribute to As sequestration, but As enrichment in JBF sediments within the plume (i.e., as compared with JBF sediments upgradient) was not observed. These results indicate that neither the persistence of As in the source area soils or the apparent stability of the plume of As-contaminated groundwater at this site can be explained by geochemical controls on As mobility. The absence of demonstrable geochemical bases for such observations suggests that possible hydrologic controls should be further investigated at this site.

  10. Effects of redox conditions on the control of arsenic mobility in shallow alluvial aquifers on the Venetian Plain (Italy)

    Energy Technology Data Exchange (ETDEWEB)

    Carraro, A. [Institute of Geosciences and Earth Resources, National Research Council (CNR) of Italy, Padova, Italy c/o Department of Geosciences, University of Padova, 35131 Padova (Italy); Fabbri, P. [Institute of Geosciences and Earth Resources, National Research Council (CNR) of Italy, Padova, Italy c/o Department of Geosciences, University of Padova, 35131 Padova (Italy); Department of Geosciences, University of Padova, 35131 Padova (Italy); Giaretta, A.; Peruzzo, L.; Tateo, F.; Tellini, F. [Institute of Geosciences and Earth Resources, National Research Council (CNR) of Italy, Padova, Italy c/o Department of Geosciences, University of Padova, 35131 Padova (Italy)

    2015-11-01

    The Venetian Plain is known for the occurrence of areas with high concentrations of arsenic in groundwater (greater than 400 μg/L). The study area represents the typical residential, industrial and agricultural features of most Western countries and is devoid of hydrothermal, volcanic or anthropogenic sources of arsenic. The aim of the study is to model the arsenic mobilization and the water–rock interaction by a complete hydrogeochemical investigation (analyses of filtered and unfiltered groundwater sediment mineralogy and geochemistry). The groundwater arsenic contamination and redox conditions are highly variable. Groundwaters with oxidizing and strongly reducing potentials have much lower arsenic concentrations than do mildly reducing waters. The grain size of the aquifer sediments includes gravels, sands and silty-clays. A continuous range of organic material concentrations is observed (from zero to 40%). The amount of sedimentary organic matter is highly correlated with the arsenic content of the sediments (up to 300 mg/kg), whereas no relationships are detectable between arsenic and other chemical parameters. The occurrence of arsenic minerals was observed as a peculiar feature under the scanning electron microscope. Arsenic and sulfur are the sole constituents of small tufts or thin crystals concentrated in small masses. These arsenic minerals were clearly observed in the peat sediments, in agreement with the geochemical modeling that requires very reducing conditions for their precipitation from the groundwater. The modeling suggests that, under oxidizing conditions, arsenic is adsorbed; moreover, a continuous decrease in the redox potential causes increasing desorption of arsenic. If the reducing conditions become more intense, the formation of As-S minerals would explain the lower concentration of arsenic measured in the strongly reducing groundwater. Even if As-sulfides are rare under low-temperature conditions, the anomalous abundance of reductants

  11. Effects of redox conditions on the control of arsenic mobility in shallow alluvial aquifers on the Venetian Plain (Italy)

    International Nuclear Information System (INIS)

    Carraro, A.; Fabbri, P.; Giaretta, A.; Peruzzo, L.; Tateo, F.; Tellini, F.

    2015-01-01

    The Venetian Plain is known for the occurrence of areas with high concentrations of arsenic in groundwater (greater than 400 μg/L). The study area represents the typical residential, industrial and agricultural features of most Western countries and is devoid of hydrothermal, volcanic or anthropogenic sources of arsenic. The aim of the study is to model the arsenic mobilization and the water–rock interaction by a complete hydrogeochemical investigation (analyses of filtered and unfiltered groundwater sediment mineralogy and geochemistry). The groundwater arsenic contamination and redox conditions are highly variable. Groundwaters with oxidizing and strongly reducing potentials have much lower arsenic concentrations than do mildly reducing waters. The grain size of the aquifer sediments includes gravels, sands and silty-clays. A continuous range of organic material concentrations is observed (from zero to 40%). The amount of sedimentary organic matter is highly correlated with the arsenic content of the sediments (up to 300 mg/kg), whereas no relationships are detectable between arsenic and other chemical parameters. The occurrence of arsenic minerals was observed as a peculiar feature under the scanning electron microscope. Arsenic and sulfur are the sole constituents of small tufts or thin crystals concentrated in small masses. These arsenic minerals were clearly observed in the peat sediments, in agreement with the geochemical modeling that requires very reducing conditions for their precipitation from the groundwater. The modeling suggests that, under oxidizing conditions, arsenic is adsorbed; moreover, a continuous decrease in the redox potential causes increasing desorption of arsenic. If the reducing conditions become more intense, the formation of As-S minerals would explain the lower concentration of arsenic measured in the strongly reducing groundwater. Even if As-sulfides are rare under low-temperature conditions, the anomalous abundance of reductants

  12. ASSESSING THE MOBILITY OF ARSENIC IN CONTAMINATED SEDIMENTS

    Science.gov (United States)

    The mobility of arsenic is controlled, in part, by partitioning to mineral surfaces in soils and sediments. Determination of the risk posed to human or ecosystem health by arsenic and identification of remediation technologies that could be employed to eliminate or reduce risk i...

  13. The role of cassiterite controlling arsenic mobility in an abandoned stanniferous tailings impoundment at Llallagua, Bolivia.

    Science.gov (United States)

    Romero, Francisco Martín; Canet, Carles; Alfonso, Pura; Zambrana, Rubén N; Soto, Nayelli

    2014-05-15

    The surface water contamination by potentially toxic elements (PTE) leached from mine tailings is a major environmental concern. However, the formation of insoluble solid phases can control the mobility of PTE, with subsequent decrease of the risk that tailings suppose to the environment. We characterized the tailings from a tin inactive mine in Llallagua, Bolivia in order to assess the risk for surface water quality. These tailings contain high concentrations of PTE, with up to 94,344 mg/kg Fe, 9,135 mg/kg Sn, 4,606 mg/kg As, 1,362 mg/kg Cu, 1,220 mg/kg Zn, 955 mg/kg Pb and 151 mg/kg Cd. Oxidation of sulfide minerals in these tailings generates acid leachates (pH=2.5-3.5), rich in SO4(2-) and dissolved PTE, thereby releasing contaminants to the surface waters. Nevertheless, the concentrations of dissolved Sn, As and Pb in acid leachates are low (Sntailing deposits; it should be the main solid phase controlling Sn and As mobility in the impoundment. Additionally, jarosite and plumbojarosite, identified among the secondary minerals, could also play an important role controlling the mobility of As and Pb. Taking into account (a) the low solubility constants of cassiterite (Ksp=10(-64.2)), jarosite (Ksp=10(-11)) and plumbojarosite (Ksp=10(-28.66)), and (b) the stability of these minerals under acidic conditions, we can conclude that they control the long-term fate of Sn, As and Pb in the studied tailings. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. High arsenic (As concentrations in the shallow groundwaters of southern Louisiana: Evidence of microbial controls on As mobilization from sediments

    Directory of Open Access Journals (Sweden)

    Ningfang Yang

    2016-03-01

    Full Text Available Study region: The Mississippi Delta in southern Louisiana, United States. Study focus: The probable role that microbial respiration plays in As release from the shallow aquifer sediments. New hydrological insights for the region: Shallow groundwaters in southern Louisiana have been reported to contain elevated As concentrations, whereas mechanisms responsible for As release from sediments have rarely been studied in this region. Microbial respiration is generally considered the main mechanism controlling As release in reducing anoxic aquifers such as the shallow aquifers in southern Louisiana and those of the Bengal basin. This study investigates the role microbial respiration plays in As release from shallow aquifer sediments in southern Louisiana through sediment incubation experiments and porewater analysis. Arsenic concentrations were the lowest in the sterilized control experiments, slightly higher in the un-amended experiments, and the highest in the experiments amended with acetate, and especially those amended with both acetate and AQDS (9,10-anthraquinone-2,6-disulfonic acid. Although Fe and Mn generally decreased at the beginning of all the experiments, they did follow a similar trend to As after the decrease. Porewater analysis showed that As and Fe concentrations were generally positively correlated and were higher in the coarse-grained sediments than in the fine-grained sediments. Results of the investigation are consistent with microbial respiration playing a key role in As release from the shallow aquifers sediments in southern Louisiana. Keywords: Groundwater, Arsenic, Microbial respiration

  15. Mobilization of iron and arsenic from soil by construction and demolition debris landfill leachate.

    Science.gov (United States)

    Wang, Yu; Sikora, Saraya; Kim, Hwidong; Dubey, Brajesh; Townsend, Timothy

    2012-05-01

    Column experiments were performed to examine (a) the potential for leachate from construction and demolition (C&D) debris landfills to mobilize naturally-occurring iron and arsenic from soils underlying such facilities and (b) the ability of crushed limestone to remove these aqueous phase pollutants. In duplicate columns, water was added to a 30-cm layer of synthetic C&D debris, with the resulting leachate serially passed through a 30-cm soil layer containing iron and arsenic and a 30-cm crushed limestone layer. This experiment was conducted for two different soil types (one high in iron (10,400mg/kg) and the second high in iron (5400mg/kg) and arsenic (70mg/kg)); also monitored were control columns for both soil types with water infiltration alone. Despite low iron concentrations in the simulated C&D debris leachate, elevated iron concentrations were observed when leachate passed through the soils; reductive dissolution was concluded to be the cause of iron mobilization. In the soil containing elevated arsenic, increased iron mobilization from the soil was accompanied by a similar but delayed arsenic mobilization. Since arsenic sorbs to oxidized iron soil minerals, reductive dissolution of these minerals results in arsenic mobilization. Crushed limestone significantly reduced iron (to values below the detection limit of 0.01mg/L in most cases); however, arsenic was not removed to any significant extent. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Investigation of hydrologic and biogeochemical controls on arsenic mobilization using distributed sensing at a field site in Munshiganj, Bangladesh

    Science.gov (United States)

    Ramanathan, N.; Estrin, D.; Harmon, T.; Harvey, C.; Jay, J.; Kohler, E.; Rothenberg, S.

    2006-12-01

    The presence of arsenic in the groundwater has led to the largest environmental poisoning in history; tens of millions of people in the Ganges Delta continue to drink groundwater that is dangerously contaminated with arsenic. A current working hypothesis is that arsenic is mobilized in the near surface environment where sediments are weathered by seasonal changes in the redox state that drive a cycle of pyrite oxidation and iron oxide reduction. In order to test the supporting hypothesis that subsurface geochemical changes may be induced by agricultural activity, we deployed 42 wirelessly networked ion-selective electrodes, including calcium, ammonium, nitrate, ORP, chloride, carbonate, and pH in a rice paddy in the Munshiganj district of Bangladesh in January of 2006. Each sensor was connected to an MDA300 sensor board and Mica2 wireless transceiver and computational device. Over a period of 11 days, we observed clear diel, and diurnal trends in 4 of the electrodes (calcium, ammonium, chloride and carbonate). The trends may be due to hydrological changes, or geochemical changes induced either by photosynthesis in the overlying water (which then infiltrated to the depth of the sensors) or in the root zone of rice plants. While the spatiotemporally dense measurements from wireless sensor networks enable scientists to ask new questions and elucidate complex relationships in heterogeneous physical environments such as soil, there are many practical issues to address in order to collect data usable for scientific purposes. For example, in response to a stream of faults in one of our sensor network deployments, we designed Sympathy to enable users to find and fix problems impacting the quantity of data collected in the field. Sympathy detects packet loss experienced at the base station and systematically assigns blame to faulty components in the network for remediation, replacing the prior policy of ad-hoc node rebooting and battery replacements. Sympathy has been

  17. Geochemical Triggers of Arsenic Mobilization during Managed Aquifer Recharge.

    Science.gov (United States)

    Fakhreddine, Sarah; Dittmar, Jessica; Phipps, Don; Dadakis, Jason; Fendorf, Scott

    2015-07-07

    Mobilization of arsenic and other trace metal contaminants during managed aquifer recharge (MAR) poses a challenge to maintaining local groundwater quality and to ensuring the viability of aquifer storage and recovery techniques. Arsenic release from sediments into solution has occurred during purified recycled water recharge of shallow aquifers within Orange County, CA. Accordingly, we examine the geochemical processes controlling As desorption and mobilization from shallow, aerated sediments underlying MAR infiltration basins. Further, we conducted a series of batch and column experiments to evaluate recharge water chemistries that minimize the propensity of As desorption from the aquifer sediments. Within the shallow Orange County Groundwater Basin sediments, the divalent cations Ca(2+) and Mg(2+) are critical for limiting arsenic desorption; they promote As (as arsenate) adsorption to the phyllosilicate clay minerals of the aquifer. While native groundwater contains adequate concentrations of dissolved Ca(2+) and Mg(2+), these cations are not present at sufficient concentrations during recharge of highly purified recycled water. Subsequently, the absence of dissolved Ca(2+) and Mg(2+) displaces As from the sediments into solution. Increasing the dosages of common water treatment amendments including quicklime (Ca(OH)2) and dolomitic lime (CaO·MgO) provides recharge water with higher concentrations of Ca(2+) and Mg(2+) ions and subsequently decreases the release of As during infiltration.

  18. Effect of fly ash characteristics on arsenic mobilization in the environment

    International Nuclear Information System (INIS)

    Bhumbla, D.K.; Singh, R.N.; Keefer, R.F.

    1993-01-01

    Coal combustion by products are a major source of arsenic mobilization in the environment. These by products have been successfully used in the reclamation of mine lands. However, there are concerns about the potential pollution problems from As by such use. A field experiment was established on a recently remined abandoned mine land where fly ashes from three different power plants were used for reclaiming mine soils. The experiment had seven treatments and 4 replications which were arranged in a randomized block design. The treatments consisted of 3 fly ashes at 2 rates each and a check treatment received lime. Arsenic content of the fly ashes varied between 53 and 220 mg/kg. Fly ashes also varied in the amounts of amorphous oxides of iron and neutralization potential. Arsenic concentrations were monitored in the vegetation, soil solutions, and soils. The results of this experiment showed that arsenic concentrations were higher in plants grown on plots receiving fly ash than in plants grown on plots receiving lime treatment. Arsenic concentrations in the plants, water, or soil were not governed by the arsenic content of fly ashes. Arsenic mobilization from the ashes was controlled by the chemical and morphological characteristics of the fly ashes and chemical transformations in the arsenic containing components in soil

  19. Arsenic mobilization and immobilization in paddy soils

    Science.gov (United States)

    Kappler, A.; Hohmann, C.; Zhu, Y. G.; Morin, G.

    2010-05-01

    Arsenic is oftentimes of geogenic origin and in many cases bound to iron(III) minerals. Iron(III)-reducing bacteria can harvest energy by coupling the oxidation of organic or inorganic electron donors to the reduction of Fe(III). This process leads either to dissolution of Fe(III)-containing minerals and thus to a release of the arsenic into the environment or to secondary Fe-mineral formation and immobilisation of arsenic. Additionally, aerobic and anaerobic iron(II)-oxidizing bacteria have the potential to co-precipitate or sorb arsenic during iron(II) oxidation at neutral pH that is usually followed by iron(III) mineral precipitation. We are currently investigating arsenic immobilization by Fe(III)-reducing bacteria and arsenic co-precipitation and immobilization by anaerobic iron(II)-oxidizing bacteria in batch, microcosm and rice pot experiments. Co-precipitation batch experiments with pure cultures of nitrate-dependent Fe(II)-oxidizing bacteria are used to quantify the amount of arsenic that can be immobilized during microbial iron mineral precipitation, to identify the minerals formed and to analyze the arsenic binding environment in the precipitates. Microcosm and rice pot experiments are set-up with arsenic-contaminated rice paddy soil. The microorganisms (either the native microbial population or the soil amended with the nitrate-dependent iron(II)-oxidizing Acidovorax sp. strain BoFeN1) are stimulated either with iron(II), nitrate, or oxygen. Dissolved and solid-phase arsenic and iron are quantified. Iron and arsenic speciation and redox state in batch and microcosm experiments are determined by LC-ICP-MS and synchrotron-based methods (EXAFS, XANES).

  20. Evaluation of conceptual and numerical models for arsenic mobilization and attenuation during managed aquifer recharge.

    Science.gov (United States)

    Wallis, Ilka; Prommer, Henning; Simmons, Craig T; Post, Vincent; Stuyfzand, Pieter J

    2010-07-01

    Managed Aquifer Recharge (MAR) is promoted as an attractive technique to meet growing water demands. An impediment to MAR applications, where oxygenated water is recharged into anoxic aquifers, is the potential mobilization of trace metals (e.g., arsenic). While conceptual models for arsenic transport under such circumstances exist, they are generally not rigorously evaluated through numerical modeling, especially at field-scale. In this work, geochemical data from an injection experiment in The Netherlands, where the introduction of oxygenated water into an anoxic aquifer mobilized arsenic, was used to develop and evaluate conceptual and numerical models of arsenic release and attenuation under field-scale conditions. Initially, a groundwater flow and nonreactive transport model was developed. Subsequent reactive transport simulations focused on the description of the temporal and spatial evolution of the redox zonation. The calibrated model was then used to study and quantify the transport of arsenic. In the model that best reproduced field observations, the fate of arsenic was simulated by (i) release via codissolution of arsenopyrite, stoichiometrically linked to pyrite oxidation, (ii) kinetically controlled oxidation of dissolved As(III) to As(V), and (iii) As adsorption via surface complexation on neo-precipitated iron oxides.

  1. Mobility and attenuation of arsenic in sulfide-rich mining wastes from the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Drahota, P.; Knappová, M.; Kindlová, H.; Culka, A.; Majzlan, J.; Mihaljevič, M.; Rohovec, Jan; Veselovský, F.; Fridrichová, Michaela; Jehlička, J.

    557/558, July 01 (2016), s. 192-203 ISSN 0048-9697 Institutional support: RVO:67985831 Keywords : arsenic * mining waste * mobility * pore water * secondary arsenic minerals Subject RIV: DD - Geochemistry Impact factor: 4.900, year: 2016

  2. Understanding arsenic mobilization using reactive transport modeling of groundwater hydrochemistry in the Datong basin study plot, China.

    Science.gov (United States)

    Mapoma, Harold Wilson Tumwitike; Xie, Xianjun; Pi, Kunfu; Liu, Yaqing; Zhu, Yapeng

    2016-03-01

    This paper discusses the reactive transport and evolution of arsenic along a selected flow path in a study plot within the central part of Datong basin. The simulation used the TOUGHREACT code. The spatial and temporal trends in hydrochemistry and mineral volume fraction along a flow path were observed. Furthermore, initial simulation of major ions and pH fits closely to the measured data. The study shows that equilibrium conditions may be attained at different stress periods for each parameter simulated. It is noted that the variations in ionic chemistry have a greater impact on arsenic distribution while reducing conditions drive the mobilization of arsenic. The study concluded that the reduction of Fe(iii) and As(v) and probably SO4/HS cycling are significant factors affecting localized mobilization of arsenic. Besides cation exchange and water-rock interaction, incongruent dissolution of silicates is also a significant control mechanism of general chemistry of the Datong basin aquifer.

  3. Multivariate analysis of the heterogeneous geochemical processes controlling arsenic enrichment in a shallow groundwater system.

    Science.gov (United States)

    Huang, Shuangbing; Liu, Changrong; Wang, Yanxin; Zhan, Hongbin

    2014-01-01

    The effects of various geochemical processes on arsenic enrichment in a high-arsenic aquifer at Jianghan Plain in Central China were investigated using multivariate models developed from combined adaptive neuro-fuzzy inference system (ANFIS) and multiple linear regression (MLR). The results indicated that the optimum variable group for the AFNIS model consisted of bicarbonate, ammonium, phosphorus, iron, manganese, fluorescence index, pH, and siderite saturation. These data suggest that reductive dissolution of iron/manganese oxides, phosphate-competitive adsorption, pH-dependent desorption, and siderite precipitation could integrally affect arsenic concentration. Analysis of the MLR models indicated that reductive dissolution of iron(III) was primarily responsible for arsenic mobilization in groundwaters with low arsenic concentration. By contrast, for groundwaters with high arsenic concentration (i.e., > 170 μg/L), reductive dissolution of iron oxides approached a dynamic equilibrium. The desorption effects from phosphate-competitive adsorption and the increase in pH exhibited arsenic enrichment superior to that caused by iron(III) reductive dissolution as the groundwater chemistry evolved. The inhibition effect of siderite precipitation on arsenic mobilization was expected to exist in groundwater that was highly saturated with siderite. The results suggest an evolutionary dominance of specific geochemical process over other factors controlling arsenic concentration, which presented a heterogeneous distribution in aquifers. Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of Environmental Science and Health, Part A, to view the supplemental file.

  4. Monitoring and evaluation of plant and hydrological controls on arsenic transport across the water sediment interface

    Science.gov (United States)

    Jaffe, P. R.; MacDonald, L. H.; Paull, J.

    2009-12-01

    dissolved arsenic concentrations during that time. This finding clearly links hydrological controls on sediment chemistry to arsenic mobility. Through mechanisms like this that influences iron, plants and hydrology impact many contaminants and, although focusing on arsenic, the principals uncovered from this detailed research bear real-world implications for forecasting and managing the transport of a variety of contaminants in wetland systems.

  5. Investigating arsenic speciation and mobilization in sediments with DGT and DET

    DEFF Research Database (Denmark)

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

    2012-01-01

    Mobilization of arsenic from freshwater and estuarine sediments during the transition from oxic to anoxic conditions was investigated using recently developed diffusive sampling techniques. Arsenic speciation and Fe(II) concentrations were measured at high resolution (1-3 mm) with in situ diffusi...

  6. Evaluation of Conceptual and Numerical Models for Arsenic Mobilization and Attenuation during Managed Aquifer Recharge

    NARCIS (Netherlands)

    Post, V.E.A.; Prommer, H.; Wallis, I.; Simmons, C.T.; Stuijfzand, P.J.

    2010-01-01

    Managed Aquifer Recharge (MAR) is promoted as an attractive technique to meet growing water demands. An impediment to MAR applications, where oxygenated water is recharged into anoxic aquifers, is the potential mobilization of trace metals (e.g., arsenic). While conceptual models for arsenic

  7. Imaging geochemical heterogeneities using inverse reactive transport modeling: An example relevant for characterizing arsenic mobilization and distribution

    DEFF Research Database (Denmark)

    Fakhreddine, Sarah; Lee, Jonghyun; Kitanidis, Peter K.

    2016-01-01

    groundwater parameters. Specifically, we simulate the mobilization of arsenic via kinetic oxidative dissolution of As-bearing pyrite due to dissolved oxygen in the ambient groundwater, which is an important mechanism for arsenic release in groundwater both under natural conditions and engineering applications......The spatial distribution of reactive minerals in the subsurface is often a primary factor controlling the fate and transport of contaminants in groundwater systems. However, direct measurement and estimation of heterogeneously distributed minerals are often costly and difficult to obtain. While...

  8. ARSENIC MOBILITY FROM IRON OXIDE SOLIDS PRODUCED DURING WATER TREATMENT

    Science.gov (United States)

    The Arsenic Rule under the Safe Drinking Water Act will require certain drinking water suppliers to add to or modify their existing treatment in order to comply with the new 10 ppb arsenic standard. One of the treatment options is co-precipitation of arsenic with iron. This tre...

  9. Sources and controls for the mobility of arsenic in oxidizing groundwaters from loess-type sediments in arid/semi-arid dry climates - evidence from the Chaco-Pampean plain (Argentina).

    Science.gov (United States)

    Nicolli, Hugo B; Bundschuh, Jochen; García, Jorge W; Falcón, Carlos M; Jean, Jiin-Shuh

    2010-11-01

    In oxidizing aquifers, arsenic (As) mobilization from sediments into groundwater is controlled by pH-dependent As desorption from and dissolution of mineral phases. If climate is dry, then the process of evaporative concentration contributes further to the total concentration of dissolved As. In this paper the principal As mobility controls under these conditions have been demonstrated for Salí River alluvial basin in NW Argentina (Tucumán Province; 7000 km(2)), which is representative for other basins or areas of the predominantly semi-arid Chaco-Pampean plain (1,000,000 km(2)) which is one of the world's largest regions affected by high As concentrations in groundwater. Detailed hydrogeochemical studies have been performed in the Salí River basin where 85 groundwater samples from shallow aquifers (42 samples), deep samples (26 samples) and artesian aquifers (17 samples) have been collected. Arsenic concentrations range from 11.4 to 1660 μg L(-1) leaving 100% of the investigated waters above the provisional WHO guideline value of 10 μg L(-1). A strong positive correlation among As, F, and V in shallow groundwaters was found. The correlations among those trace elements and U, B and Mo have less significance. High pH (up to 9.2) and high bicarbonate (HCO(3)) concentrations favour leaching from pyroclastic materials, including volcanic glass which is present to 20-25% in the loess-type aquifer sediments and yield higher trace element concentrations in groundwater from shallow aquifers compared to deep and artesian aquifers. The significant increase in minor and trace element concentrations and salinity in shallow aquifers is related to strong evaporation under semi-arid climatic conditions. Sorption of As and associated minor and trace elements (F, U, B, Mo and V) onto the surface of Fe-, Al- and Mn-oxides and oxi-hydroxides, restricts the mobilization of these elements into groundwater. Nevertheless, this does not hold in the case of the shallow unconfined

  10. Arsenic Mobility and Availability in Sediments by Application of BCR Sequential Extractions Method

    International Nuclear Information System (INIS)

    Larios, R.; Fernandez, R.; Rucandio, M. I.

    2011-01-01

    Arsenic is a metalloid found in nature, both naturally and due to anthropogenic activities. Among them, mining works are an important source of arsenic release to the environment. Asturias is a region where important mercury mines were exploited, and in them arsenic occurs in para genesis with mercury minerals. The toxicity and mobility of this element depends on the chemical species it is found. Fractionation studies are required to analyze the mobility of this metalloid in soils and sediments. Among them, the proposed by the Bureau Community of Reference (BCR) is one of the most employed. This method attempts to divide up, by operationally defined stages, the amount of this element associated with carbonates (fraction 1), iron and manganese oxy hydroxides (fraction 2), organic matter and sulphides (fraction 3), and finally as the amount associated residual fraction to primary and secondary minerals, that is, from the most labile fractions to the most refractory ones. Fractionation of arsenic in sediments from two mines in Asturias were studied, La Soterrana and Los Rueldos. Sediments from La Soterrana showed high levels of arsenic in the non-residual phases, indicating that the majority of arsenic has an anthropogenic origin. By contrast, in sediments from Los Rueldos most of the arsenic is concentrated in the residual phase, indicating that this element remains bound to very refractory primary minerals, as is also demonstrated by the strong correlation of arsenic fractionation and the fractionation of elements present in refractory minerals, such as iron, aluminum and titanium. (Author) 51 refs.

  11. Groundwater arsenic concentrations in Vietnam controlled by sediment age

    DEFF Research Database (Denmark)

    Postma, Dieke; Larsen, Flemming; Thai, Nguyen Thi

    2012-01-01

    Arsenic contamination of groundwater continues to threaten the health of millions of people in southeast Asia. The oxidation of organic carbon, coupled to the reductive dissolution of arsenic-bearing iron oxides, is thought to control the release of sediment-bound arsenic into groundwater. However......, the cause of the high spatial variability in groundwater arsenic concentrations—which can range from 5 to 500 μg l−1 within distances of a few kilometres—has been uncertain. Here, we combine measurements of sediment age, organic-matter reactivity and water chemistry at four locations along a cross......-section of the arsenic-contaminated Red River floodplain in Vietnam to determine the origin of variations in groundwater arsenic concentrations. The burial age of the aquifer sediments, determined using optical stimulated luminescence, ranged from 460 years near the course of the present-day river to 5,900 years...

  12. Investigating Arsenic Mobilization Mechanisms as well as Complexation Between Arsenic and Polysulfides Associated With a Bangladeshi Rice Paddy

    Science.gov (United States)

    Lin, T.; Kampalath, R.; Jay, J.

    2009-12-01

    The presence of arsenic in the groundwater has led to the largest environmental poisoning in history. Although it is a worldwide issue that affects numerous countries, including Taiwan, Bangladesh, India, China, Mexico, Peru, Australia, and the United States, the issue is of greatest concern in the West Bengal region. In the Ganges Delta, as many as 2 million people are diagnosed with arsenicosis each year. The World Health Organization (WHO) estimates 200,000 to 270,000 arsenic-induced cancer-related deaths in Bangladesh alone. More than 100 million people in the country consume groundwater that exceeds the WHO limit as 50% of the 8 million wells contain groundwater with more than 10 μg/L. Despite the tragic public health implications of this problem, we do not yet have a complete answer to the question of why dissolved arsenic concentrations are so high in the groundwater of the Ganges Delta. Since 1999, we have been intensively studying a field site in Munshiganj, Bangladesh with extremely high levels of arsenic in groundwater (up to 1.2 mg/L). Sediment cores were collected from two locations at the field site: 1) the rice paddy and 2) edge of a nearby irrigation pond. Recharge from irrigation ponds have recently been hypothesized to be an important site of arsenic mobilization. Recent work has proposed mineral dissolution under phosphorus-limited conditions as an important mechanism for arsenic mobilization. Using microcosms with paddy and pond sediment, we are comparing arsenic release via this mechanism with that resulting from reduction of iron hydroxides at our site. Concurrently, we are looking at enhanced solubility of As in the presence of polysulfides as the effects of elemental sulfur on As solubility have not been well researched. We hypothesize that the presence of elemental sulfur, and consequent formation of polysulfides, will substantially increase the solubility of orpiment in sulfidic water and that sorption of these complexes will

  13. Colloidal mobilization of arsenic from mining-affected soils by surface runoff.

    Science.gov (United States)

    Gomez-Gonzalez, Miguel Angel; Voegelin, Andreas; Garcia-Guinea, Javier; Bolea, Eduardo; Laborda, Francisco; Garrido, Fernando

    2016-02-01

    Scorodite-rich wastes left as a legacy of mining and smelting operations pose a threat to environmental health. Colloids formed by the weathering of processing wastes may control the release of arsenic (As) into surface waters. At a former mine site in Madrid (Spain), we investigated the mobilization of colloidal As by surface runoff from weathered processing wastes and from sediments in the bed of a draining creek and a downstream sedimentation-pond. Colloids mobilized by surface runoff during simulated rain events were characterized for their composition, structure and mode of As uptake using asymmetric flow field-flow fractionation coupled to inductively plasma mass spectrometry (AF4-ICP-MS) and X-ray absorption spectroscopy (XAS) at the As and Fe K-edges. Colloidal scorodite mobilized in surface runoff from the waste pile is acting as a mobile As carrier. In surface runoff from the river bed and the sedimentation pond, ferrihydrite was identified as the dominant As-bearing colloidal phase. The results from this study suggest that mobilization of As-bearing colloids by surface runoff may play an important role in the dispersion of As from metallurgical wastes deposited above ground and needs to be considered in risk assessment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Assessment of arsenic exposures and controls in gallium arsenide production.

    Science.gov (United States)

    Sheehy, J W; Jones, J H

    1993-02-01

    The electronics industry is expanding the use of gallium arsenide in the production of optoelectronic devices and integrated circuits. Workers in the electronics industry using gallium arsenide are exposed to hazardous substances such as arsenic, arsine, and various acids. Arsenic requires stringent controls to minimize exposures (the current OSHA PEL for arsenic is 10 micrograms/m3 and the NIOSH REL is 2 micrograms/m3 ceiling). Inorganic arsenic is strongly implicated in respiratory tract and skin cancer. For these reasons, NIOSH researchers conducted a study of control systems for facilities using gallium arsenide. Seven walk-through surveys were performed to identify locations for detailed study which appeared to have effective controls; three facilities were chosen for in-depth evaluation. The controls were evaluated by industrial hygiene sampling. Including personal breathing zone and area air sampling for arsenic and arsine; wipe samples for arsenic also were collected. Work practices and the use of personal protective equipment were documented. This paper reports on the controls and the arsenic exposure results from the evaluation of the following gallium arsenide processes: Liquid Encapsulated Czochralski (LEC) and Horizontal Bridgeman (HB) crystal growing, LEC cleaning operations, ingot grinding/wafer sawing, and epitaxy. Results at one plant showed that in all processes except epitaxy, average arsenic exposures were at or above the OSHA action level of 5 micrograms/m3. While cleaning the LEC crystal pullers, the average potential arsenic exposure of the cleaning operators was 100 times the OSHA PEL. At the other two plants, personal exposures for arsenic were well controlled in LEC, LEC cleaning, grinding/sawing, and epitaxy operations.

  15. Mobility and attenuation of arsenic in sulfide-rich mining wastes from the Czech Republic

    Energy Technology Data Exchange (ETDEWEB)

    Drahota, Petr, E-mail: petr.drahota@natur.cuni.cz [Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University, Albertov 6, 128 43 Prague 2 (Czech Republic); Knappová, Magdaléna; Kindlová, Helena; Culka, Adam [Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University, Albertov 6, 128 43 Prague 2 (Czech Republic); Majzlan, Juraj [Institute of Geosciences, Friedrich-Schiller University, Burgweg 11, D-07749 Jena (Germany); Mihaljevič, Martin [Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University, Albertov 6, 128 43 Prague 2 (Czech Republic); Rohovec, Jan [Institute of Geology, The Czech Academy of Sciences, v.v.i., Rozvojová 269, 165 00 Prague 6 (Czech Republic); Veselovský, František [Czech Geological Survey, Geologická 6, 152 00 Prague 5 (Czech Republic); Fridrichová, Michaela [Institute of Geology, The Czech Academy of Sciences, v.v.i., Rozvojová 269, 165 00 Prague 6 (Czech Republic); Jehlička, Jan [Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University, Albertov 6, 128 43 Prague 2 (Czech Republic)

    2016-07-01

    The mineralogical composition of mining wastes deposited in countless dumps around the world is the key factor that controls retention and release of pollutants. Here we report a multi-method data set combining mineralogical (X-ray diffraction, electron microprobe and Raman microspectrometry) and geochemical (sequential extraction and pore water analysis) methods to resolve As mobility in two 50-years-old mining waste dumps. Originally, all of the As in the mining wastes selected for the study was present as arsenopyrite and with time it has been replaced by secondary As phases. At Jedová jáma mining area, the most of As precipitated as X-ray amorphous ferric arsenate (HFA). Arsenic is also accumulated in the scorodite and Fe (hydr)oxide (with up to 3.2 wt.% As{sub 2}O{sub 5}) that is particularly represented by hematite. Mining wastes at Dlouhá Ves contain only trace amount of scorodite. Arsenic is primarily bound to Pb-jarosite and Fe (hydr)oxides (especially goethite) with up to 1.6 and 1.8 wt.% As{sub 2}O{sub 5}, respectively. The pore water collected after rainfall events indicated high concentrations of As (~ 4600 μg·L{sup −1}) at Jedová jáma, whereas aqueous As at Dlouhá Ves was negligible (up to 1.5 μg·L{sup −1}). Highly mobile As at Jedová jáma is attributed to the dissolution of HFA and simultaneous precipitation of Fe (hydr)oxides under mildly acidic conditions (pH ~ 4.4); immobile As at Dlouhá Ves is due to the efficient adsorption on the Fe (hydr)oxides and hydroxosulfates under acidic pH of ~ 2.8. Taken together, As mobility in the ferric arsenates-containing mining wastes may significantly vary. These wastes must be kept under acidic conditions or with high aqueous Fe(III) concentrations to prevent the release of As from incongruent dissolution of ferric arsenates. - Highlights: • Two 50 years-old sulfide-rich mining waste dumps were studied. • Environmental stability of secondary arsenic mineral phases were assessed.

  16. Mobility and attenuation of arsenic in sulfide-rich mining wastes from the Czech Republic

    International Nuclear Information System (INIS)

    Drahota, Petr; Knappová, Magdaléna; Kindlová, Helena; Culka, Adam; Majzlan, Juraj; Mihaljevič, Martin; Rohovec, Jan; Veselovský, František; Fridrichová, Michaela; Jehlička, Jan

    2016-01-01

    The mineralogical composition of mining wastes deposited in countless dumps around the world is the key factor that controls retention and release of pollutants. Here we report a multi-method data set combining mineralogical (X-ray diffraction, electron microprobe and Raman microspectrometry) and geochemical (sequential extraction and pore water analysis) methods to resolve As mobility in two 50-years-old mining waste dumps. Originally, all of the As in the mining wastes selected for the study was present as arsenopyrite and with time it has been replaced by secondary As phases. At Jedová jáma mining area, the most of As precipitated as X-ray amorphous ferric arsenate (HFA). Arsenic is also accumulated in the scorodite and Fe (hydr)oxide (with up to 3.2 wt.% As_2O_5) that is particularly represented by hematite. Mining wastes at Dlouhá Ves contain only trace amount of scorodite. Arsenic is primarily bound to Pb-jarosite and Fe (hydr)oxides (especially goethite) with up to 1.6 and 1.8 wt.% As_2O_5, respectively. The pore water collected after rainfall events indicated high concentrations of As (~ 4600 μg·L"−"1) at Jedová jáma, whereas aqueous As at Dlouhá Ves was negligible (up to 1.5 μg·L"−"1). Highly mobile As at Jedová jáma is attributed to the dissolution of HFA and simultaneous precipitation of Fe (hydr)oxides under mildly acidic conditions (pH ~ 4.4); immobile As at Dlouhá Ves is due to the efficient adsorption on the Fe (hydr)oxides and hydroxosulfates under acidic pH of ~ 2.8. Taken together, As mobility in the ferric arsenates-containing mining wastes may significantly vary. These wastes must be kept under acidic conditions or with high aqueous Fe(III) concentrations to prevent the release of As from incongruent dissolution of ferric arsenates. - Highlights: • Two 50 years-old sulfide-rich mining waste dumps were studied. • Environmental stability of secondary arsenic mineral phases were assessed. • Different modes of As binding are

  17. Effects of sulfur in flooded paddy soils: Implications for iron chemistry and arsenic mobilization

    Science.gov (United States)

    Avancha, S.; Boye, K.

    2013-12-01

    In the Mekong delta in Cambodia, naturally occurring arsenic (amplified by erosion in the Himalaya Mountains) in paddy soils is mobilized during the seasonal flooding. As a consequence, rice grown on the flooded soils may take up arsenic and expose people eating the rice to this carcinogenic substance. Iron and sulfur both interact strongly with arsenic in paddy soils: iron oxides are strong adsorbents for arsenic in oxic conditions, and sulfur (in the form of sulfide) is a strong adsorbent under anoxic conditions. In the process of reductive dissolution of iron oxides, arsenic, which had been adsorbed to the iron oxides, is released. Therefore, higher levels of reduced iron (ferrous iron) will likely correlate with higher levels of mobilized arsenic. However, the mobilized arsenic may then co-precipitate with or adsorb to iron sulfides, which form under sulfate-reducing conditions and with the aid of certain microbes already present in the soil. In a batch experiment, we investigated how these processes correlate and which has the greatest influence on arsenic mobilization and potential plant availability. The experiment was designed to measure the effects of various sources of sulfur (dried rice straw, charred rice straw, and gypsum) on the iron and arsenic release in an arsenic-contaminated paddy soil from Cambodia under flooded conditions. The two types of rice straw were designed to introduce the same amount of organic sulfur (7.7 μg/g of soil), but different levels of available carbon, since carbon stimulates microbial activity in the soil. In comparison, two different levels of gypsum (calcium sulfate) were used, 7.7 and 34.65 μg/g of soil, to test the effect of directly available inorganic sulfate without carbon addition. The soil was flooded with a buffer solution at pH 7.07 in airtight serum vials and kept as a slurry on a shaker at 25 °C. We measured pH, alkalinity, ferrous iron, ferric iron, sulfide, sulfate, total iron, sulfur, and arsenic in the

  18. Effects of Carbon in Flooded Paddy Soils: Implications for Microbial Activity and Arsenic Mobilization

    Science.gov (United States)

    Avancha, S.; Boye, K.

    2014-12-01

    In the Mekong delta in Cambodia, naturally occurring arsenic (originating from erosion in the Himalaya Mountains) in paddy soils is mobilized during the seasonal flooding. As a consequence, rice grown on the flooded soils may take up arsenic and expose people eating the rice to this carcinogenic substance. Microbial activity will enhance or decrease the mobilization of arsenic depending on their metabolic pathways. Among the microbes naturally residing in the soil are denitrifying bacteria, sulfate reducers, metal reducers (Fe, Mn), arsenic reducers, methanogens, and fermenters, whose activity varies based on the presence of oxygen. The purpose of the experiment was to assess how different amendments affect the microbial activity and the arsenic mobilization during the transition from aerobic to anaerobic metabolism after flooding of naturally contaminated Cambodian soil. In a batch experiment, we investigated how the relative metabolic rate of naturally occurring microbes could vary with different types of organic carbon. The experiment was designed to measure the effects of various sources of carbon (dried rice straw, charred rice straw, manure, and glucose) on the microbial activity and arsenic release in an arsenic-contaminated paddy soil from Cambodia under flooded conditions. All amendments were added based on the carbon content in order to add 0.036 g of carbon per vial. The soil was flooded with a 10mM TRIS buffer solution at pH 7.04 in airtight 25mL serum vials and kept at 25 °C. We prepared 14 replicates per treatment to sample both gas and solution. On each sampling point, the solution replicates were sampled destructively. The gas replicates continued on and were sampled for both gas and solution on the final day of the experiment. We measured pH, total arsenic, methane, carbon dioxide, and nitrous oxide at 8 hours, 1.5 days, 3.33 days, and 6.33 days from the start of the experiment.

  19. Arsenic mineralogy and mobility in the arsenic-rich historical mine waste dump

    International Nuclear Information System (INIS)

    Filippi, Michal; Drahota, Petr; Machovič, Vladimír; Böhmová, Vlasta; Mihaljevič, Martin

    2015-01-01

    A more than 250 year-old mine dump was studied to document the products of long-term arsenopyrite oxidation under natural conditions in a coarse-grained mine waste dump and to evaluate the environmental hazards associated with this material. Using complementary mineralogical and chemical approaches (SEM/EDS/WDS, XRD, micro-Raman spectroscopy, pore water analysis, chemical extraction techniques and thermodynamic PHREEQC-2 modeling), we documented the mineralogical/geochemical characteristics of the dumped arsenopyrite-rich material and environmental stability of the newly formed secondary minerals. A distinct mineralogical zonation was found (listed based on the distance from the decomposed arsenopyrite): scorodite (locally associated with native sulfur pseudomorphs) plus amorphous ferric arsenate (AFA/pitticite), kaňkite, As-bearing ferric (hydr)oxides and jarosite. Ferric arsenates and ferric (hydr)oxides were found to dissolve and again precipitate from downward migrating As-rich solutions cementing rock fragments. Acidic pore water (pH 3.8) has elevated concentrations of As with an average value of about 2.9 mg L −1 . Aqueous As is highly correlated with pH (R 2 = 0.97, p < 0.001) indicating that incongruent dissolution of ferric arsenates controls dissolved As well as the pH of the percolating waste solution. Arsenic released from the dissolution of ferric arsenates into the pore water is, however, trapped by latter and lower-down precipitating jarosite and especially ferric (hydr)oxides. The efficiency of As sequestration by ferric (hydr)oxides in the waste dump and underlying soil has been found to be very effective, suggesting limited environmental impact of the mine waste dump on the surrounding soil ecosystems. - Highlights: • More than 250 year-old arsenopyrite-rich mine waste dump was studied. • Mineral transformation and the environmental stability of different secondary arsenic mineral phases were assessed. • High efficiency of As

  20. Mineralogical controls on antimony and arsenic mobility during tetrahedrite-tennantite weathering at historic mine sites Špania Dolina-Piesky and Lubietová-Svätodušná, Slovakia

    Energy Technology Data Exchange (ETDEWEB)

    Bor,; #269; inová rAdková, AnežkA; Jamieson, Heather; Lalinská-Voleková, Bronislava; Majzlan, Juraj; Števko, Martin; Chovan, Martin

    2018-01-01

    The legacy of copper (Cu) mining at Špania Dolina-Piesky and Lubietová-Svätodušná (central Slovakia) is waste rock and soil, surface waters, and groundwaters contaminated with antimony (Sb), arsenic (As), Cu, and other metals. Copper ore is hosted in chalcopyrite (CuFeS2) and sulfosalt solid-solution tetrahedrite-tennantite {Cu6[Cu4(Fe,Zn)2]Sb4S13–Cu6[Cu4(Fe,Zn)2]As4S13} that show wide-spread oxidation characteristic by olive-green color secondary minerals. Tetrahedrite-tennantite can be a significant source of As and Sb contamination. Synchrotron-based μ-XRD, μ-XRF, and μ-XANES combined with electron microprobe analyses have been used to determine the mineralogy, chemical composition, element distribution, and Sb speciation in tetrahedrite-tennantite oxidation products in waste rock. Our results show that the mobility of Sb is limited by the formation of oxidation products such as tripuhyite and roméite group mineral containing 36.54 wt% Sb for samples where the primary mineral chemical composition is close to tetrahedrite end-member. Antimony K-edge μ-XANES spectra of these oxidation products indicate that the predominant Sb oxidation state is 5+. Arsenic and Cu are also hosted by amorphous phases containing 6.23 wt% Sb on average and these are intergrown with tripuhyite and roméite. Antimony in this environment is not very mobile, meaning it is not easily released from solid phases to water, especially compared to As, Cu, and S. For samples where the primary sulfosalt is close to tennantite composition, the oxidation products associated with tennantite relicts contain 2.43 wt% Sb and are amorphous. The variable solubility of the secondary minerals that have been identified is expected to influence mobility of Sb and As in near-surface environment.

  1. Effects of compost and phosphate amendments on arsenic mobility in soils and arsenic uptake by the hyperaccumulator, Pteris vittata L

    International Nuclear Information System (INIS)

    Cao Xinde; Ma, Lena Q.; Shiralipour, Aziz

    2003-01-01

    Chinese brake fern (Pteris vittata L.), an arsenic (As) hyperaccumulator, has shown the potential to remediate As-contaminated soils. This study investigated the effects of soil amendments on the leachability of As from soils and As uptake by Chinese brake fern. The ferns were grown for 12 weeks in a chromated-copper-arsenate (CCA) contaminated soil or in As spiked contaminated (ASC) soil. Soils were treated with phosphate rock, municipal solid waste, or biosolid compost. Phosphate amendments significantly enhanced plant As uptake from the two tested soils with frond As concentrations increasing up to 265% relative to the control. After 12 weeks, plants grown in phosphate-amended soil removed >8% of soil As. Replacement of As by P from the soil binding sites was responsible for the enhanced mobility of As and subsequent increased plant uptake. Compost additions facilitated As uptake from the CCA soil, but decreased As uptake from the ASC soil. Elevated As uptake in the compost-treated CCA soil was related to the increase of soil water-soluble As and As(V) transformation into As(III). Reduced As uptake in the ASC soil may be attributed to As adsorption to the compost. Chinese brake fern took up As mainly from the iron-bound fraction in the CCA soil and from the water-soluble/exchangeable As in the ASC soil. Without ferns for As adsorption, compost and phosphate amendments increased As leaching from the CCA soil, but had decreased leaching with ferns when compared to the control. For the ASC soil, treatments reduced As leaching regardless of fern presence. This study suggest that growing Chinese brake fern in conjunction with phosphate amendments increases the effectiveness of remediating As-contaminated soils, by increasing As uptake and decreasing As leaching. - Phosphate amendment increases the effectiveness of Chinese brake fern to remediate As-contaminated soils, by increasing As uptake and decreasing As leaching

  2. Arsenic mobilization and attenuation by mineral-water interactions: implications for managed aquifer recharge.

    Science.gov (United States)

    Neil, Chelsea W; Yang, Y Jeffrey; Jun, Young-Shin

    2012-07-01

    Managed aquifer recharge (MAR) has potential for addressing deficits in water supplies worldwide. It is also widely used for preventing saltwater intrusion, maintaining the groundwater table, and augmenting ecological stream flows, among many other beneficial environmental applications. However, field MAR sites have experienced arsenic mobilization from aquifer formation minerals due to induced changes in groundwater chemistry. To address this environmental concern, it is crucial to understand the potential sources and sinks impacting arsenic mobilization. This paper outlines important mineral-water interactions that can occur at MAR sites. Detailed information on minerals of concern, physiochemical processes for arsenic mobilization or attenuation, and the potential impact of microbial activity and hydrology on these processes is provided. Based on these mineral-water interactions, guidelines for predicting arsenic mobility are presented, and recommendations are made concerning MAR site monitoring. The review emphasizes important aspects in correlating interfacial reactions to reactive transport modeling and elucidating future challenges, a first step toward developing safer and more sustainable MAR operations.

  3. Integrated mobile robot control

    Science.gov (United States)

    Amidi, Omead; Thorpe, Chuck E.

    1991-03-01

    This paper describes the strucwre implementation and operation of a real-time mobile robot controller which integrates capabilities such as: position estimation path specification and hacking human interfaces fast communication and multiple client support The benefits of such high-level capabilities in a low-level controller was shown by its implementation for the Naviab autonomous vehicle. In addition performance results from positioning and tracking systems are reported and analyzed.

  4. Arsenic and Fluoride Mobilization Mechanism in Groundwater of Indus Delta and Thar Desert, Sindh, Pakistan

    Directory of Open Access Journals (Sweden)

    VIQAR HUSAIN

    2012-06-01

    Full Text Available Indus deltaic plain consists of medium to fine grained sediments, rich in organic matter deposited during the Holocene period. Thar desert is covered with sand dunes and loess originated from transported sediments from Rann of Kutch or the Indus plain by monsoon winds or by the reworking of local alluvial deposits. Groundwater salinity and microbial pollution are common in both types of lanforms, but arsenic (AS and fluoride (F toxicity dominate in the groundwater of Indus delta and Thar desert, respectively. Arsenic concentration in Tando Mohammad Khan and Tando Allayar varies from 10-500 ppb and exhibits near neutral slightly alkaline pH ranging from 6.8 to 8.0. Arsenic distribution is patchy and seems to be related to the prsence of small scale redox zonation in the aquifer. High arsenic affected areas are densely populated and intensively cultivated and its hot spots are those from where the Indus river passed during the Holocene period including Tando Allayar and Tando Mohammad Khan. Extensive ground water irrigation has accelerated flow of groundwater that brought dissolved degraded organic matter in contact with arsenic bearing sediments, enhancing reduction processes and triggering release of arsenic from detrital bioitite and muscovite in the groundwater. Furthermore, unlined sanitation and microbial contamination contribute to degradation of organic matter that enhances the reduction of iron oxy-hydroxide leading to release of arsenic to groundwater. Fluoride is found in all the groundwater samples of Tharparkar district, in the range of 0.96-2.74mg/l. The pH of groundwater is alkaline (7.38-8.59, which is accelerating maximum (1.24%F dissolution in the groundwater. The favourable pH of groundwater and soil composition of Holocene sediments of Indus delta and slightly older alluvium of Thar desert, respectively are responsible for mobilization of arsenic and fluoride in groundwater of Sindh province of Pakistan.

  5. Arsenic

    Science.gov (United States)

    ... for drinking-water quality Chemical hazards in drinking-water: arsenic Evaluations of the Joint FAO/WHO Expert Committee ... Africa Americas South-East Asia Europe Eastern Mediterranean Western ...

  6. Bacteria diversity and arsenic mobilization in rock biofilm from an ancient gold and arsenic mine.

    Science.gov (United States)

    Tomczyk-Żak, Karolina; Kaczanowski, Szymon; Drewniak, Łukasz; Dmoch, Łukasz; Sklodowska, Aleksandra; Zielenkiewicz, Urszula

    2013-09-01

    In this paper we characterize the biofilm community from an ancient Złoty Stok gold and arsenic mine. Bacterial diversity was examined using a culture-independent technique based on 16S rRNA gene amplification, cloning and sequencing. We show that unexpectedly the microbial diversity of this community was extremely high (more than 190 OTUs detected), with the most numerous members from Rhizobiales (α-Proteobacteria). Although the level of rock biofilm diversity was similar to the microbial mat community we have previously characterized in the same adit, its taxonomic composition was completely different. Detailed analysis of functional arrA and aioA genes, chemical properties of siderophores found in pore water as well as the biofilm chemical composition suggest that the biofilm community contributes to arsenic pollution of surrounding water in a biogeochemical cycle similar to the one observed in bacterial mats. To interpret our results concerning the biological arsenic cycle, we applied the theory of ecological pyramids of Charles Elton. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Arsenic stability and mobilization in soil at an amenity grassland overlying chemical waste (St. Helens, UK)

    Energy Technology Data Exchange (ETDEWEB)

    Hartley, William [School of Biological and Earth Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF (United Kingdom)], E-mail: w.hartley@ljmu.ac.uk; Dickinson, Nicholas M. [School of Biological and Earth Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF (United Kingdom); Clemente, Rafael [Department of Soil and Water Conservation and Organic Waste Management, Centro de Edafologia y Biologia Aplicada del Segura, CSIC, Apartado 4195, 30080 Murcia (Spain); French, Christopher [School of Biological and Earth Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF (United Kingdom); Piearce, Trevor G. [Biological Sciences Division, Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom); Sparke, Shaun; Lepp, Nicholas W. [School of Biological and Earth Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF (United Kingdom)

    2009-03-15

    A 6.6 ha grassland, established on a former chemical waste site adjacent to a residential area, contains arsenic (As) in surface soil at concentrations 200 times higher than UK Soil Guideline Values. The site is not recognized as statutory contaminated land, partly on the assumption that mobility of the metalloid presents a negligible threat to human health, groundwater and ecological receptors. Evidence for this is evaluated, based on studies of the effect of organic (green waste compost) and inorganic (iron oxides, lime and phosphate) amendments on As fractionation, mobility, plant uptake and earthworm communities. Arsenic mobility in soil was low but significantly related to dissolved organic matter and phosphate, with immobilization associated with iron oxides. Plant uptake was low and there was little apparent impact on earthworms. The existing vegetation cover reduces re-entrainment of dust-blown particulates and pathways of As exposure via this route. Minimizing risks to receptors requires avoidance of soil exposure, and no compost or phosphate application. - Stabilization of alkali industry waste requires careful management to minimise soil arsenic mobilization and dispersal to the wider environment.

  8. δ34S and δ18O of dissolved sulfate as biotic tracer of biogeochemical influences on arsenic mobilization in groundwater in the Hetao Plain, Inner Mongolia, China.

    Science.gov (United States)

    Li, M D; Wang, Y X; Li, P; Deng, Y M; Xie, X J

    2014-12-01

    Environmental isotopology of sulfur and oxygen of dissolved sulfate in groundwater was conducted in the Hetao Plain, northwestern China, aiming to better understand the processes controlling arsenic mobilization in arsenic-rich aqueous systems. A total of 22 groundwater samples were collected from domestic wells in the Hetao Plain. Arsenic concentrations ranged from 11.0 to 388 μg/L. The δ(34)S-SO4 and δ(18)O-SO4 values of dissolved sulfate covered a range from +1.48 to +22.4‰ and +8.17‰ to +14.8‰ in groundwater, respectively. The wide range of δ(34)S-SO4 values reflected either an input of different sources of sulfate, such as gypsum dissolution and fertilizer application, or a modification from biogeochemical process of bacterial sulfate reduction. The positive correlation between δ(34)S-SO4 and arsenic concentrations suggested that bacteria mediated processes played an important role in the mobilization of arsenic. The δ(18)O-SO4 values correlated non-linearly with δ(34)S-SO4, but within a relatively narrow range (+8.17 to +14.8‰), implying that complexities inherent in the sulfate-oxygen (O-SO4(2-)) origins, for instance, water-derived oxygen (O-H2O), molecular oxygen (O-O2) and isotope exchanging with dissolved oxides, are accounted for oxygen isotope composition of dissolved sulfate in groundwater in the Hetao Plain.

  9. Deciphering factors controlling groundwater arsenic spatial variability in Bangladesh

    Science.gov (United States)

    Tan, Z.; Yang, Q.; Zheng, C.; Zheng, Y.

    2017-12-01

    Elevated concentrations of geogenic arsenic in groundwater have been found in many countries to exceed 10 μg/L, the WHO's guideline value for drinking water. A common yet unexplained characteristic of groundwater arsenic spatial distribution is the extensive variability at various spatial scales. This study investigates factors influencing the spatial variability of groundwater arsenic in Bangladesh to improve the accuracy of models predicting arsenic exceedance rate spatially. A novel boosted regression tree method is used to establish a weak-learning ensemble model, which is compared to a linear model using a conventional stepwise logistic regression method. The boosted regression tree models offer the advantage of parametric interaction when big datasets are analyzed in comparison to the logistic regression. The point data set (n=3,538) of groundwater hydrochemistry with 19 parameters was obtained by the British Geological Survey in 2001. The spatial data sets of geological parameters (n=13) were from the Consortium for Spatial Information, Technical University of Denmark, University of East Anglia and the FAO, while the soil parameters (n=42) were from the Harmonized World Soil Database. The aforementioned parameters were regressed to categorical groundwater arsenic concentrations below or above three thresholds: 5 μg/L, 10 μg/L and 50 μg/L to identify respective controlling factors. Boosted regression tree method outperformed logistic regression methods in all three threshold levels in terms of accuracy, specificity and sensitivity, resulting in an improvement of spatial distribution map of probability of groundwater arsenic exceeding all three thresholds when compared to disjunctive-kriging interpolated spatial arsenic map using the same groundwater arsenic dataset. Boosted regression tree models also show that the most important controlling factors of groundwater arsenic distribution include groundwater iron content and well depth for all three

  10. Understanding the role of multiheme cytochromes in iron(III) reduction and arsenic mobilization by Shewanella sp. ANA-3

    Science.gov (United States)

    Reyes, C.; Duenas, R.; Saltikov, C.

    2006-12-01

    The reduction of Fe (III) to Fe (II) and of arsenate (As (V)) to arsenite (As (III)) by Fe (III) reducing and As (V) respiring prokaryotes such as the bacterium Shewanella sp. ANA-3 may contribute to arsenic mobilization in aquifers contaminated with arsenic, specifically in places such as Bangladesh. Under oxic conditions As (V) predominates and is often adsorbed onto mineral surfaces such as amorphous ferrihydrite. However, under anoxic conditions As (III) predominates, sorbs to fewer minerals, and has a greater hydrologic mobility compared to As (V). The genetic mechanism underlying arsenic release from subsurface material most likely involves a combination of respiratory gene clusters (e.g. mtr/omc and arr). In this study, we are investigating the genetic pathways underlying arsenic mobilization. We have generated various mutations in the mtr/omc gene cluster, which encodes several outermembrane decaheme c-type cytochromes. Deletions in one mtr/omc gene did not eliminate iron reduction. However, strains carrying multiple gene deletions were greatly impaired in iron reduction abilities. Work is currently underway to generate combinations of iron reduction and arsenate reduction single and double mutants that will be used to investigate microbial mobilization of arsenic in flow-through columns containing As (V)-HFO coated sand. This work will address the importance of arsenate reduction and iron reduction in the mobilization of arsenic.

  11. Diversity, metabolic properties and arsenic mobilization potential of indigenous bacteria in arsenic contaminated groundwater of West Bengal, India.

    Science.gov (United States)

    Paul, Dhiraj; Kazy, Sufia K; Gupta, Ashok K; Pal, Taraknath; Sar, Pinaki

    2015-01-01

    Arsenic (As) mobilization in alluvial aquifers is caused by a complex interplay of hydro-geo-microbiological activities. Nevertheless, diversity and biogeochemical significance of indigenous bacteria in Bengal Delta Plain are not well documented. We have deciphered bacterial community compositions and metabolic properties in As contaminated groundwater of West Bengal to define their role in As mobilization. Groundwater samples showed characteristic high As, low organic carbon and reducing property. Culture-independent and -dependent analyses revealed presence of diverse, yet near consistent community composition mostly represented by genera Pseudomonas, Flavobacterium, Brevundimonas, Polaromonas, Rhodococcus, Methyloversatilis and Methylotenera. Along with As-resistance and -reductase activities, abilities to metabolize a wide range carbon substrates including long chain and polyaromatic hydrocarbons and HCO3, As3+ as electron donor and As5+/Fe3+ as terminal electron acceptor during anaerobic growth were frequently observed within the cultivable bacteria. Genes encoding cytosolic As5+ reductase (arsC) and As3+ efflux/transporter [arsB and acr3(2)] were found to be more abundant than the dissimilatory As5+ reductase gene arrA. The observed metabolic characteristics showed a good agreement with the same derived from phylogenetic lineages of constituent populations. Selected bacterial strains incubated anaerobically over 300 days using natural orange sand of Pleistocene aquifer showed release of soluble As mostly as As3+ along with several other elements (Al, Fe, Mn, K, etc.). Together with the production of oxalic acid within the biotic microcosms, change in sediment composition and mineralogy indicated dissolution of orange sand coupled with As/Fe reduction. Presence of arsC gene, As5+ reductase activity and oxalic acid production by the bacteria were found to be closely related to their ability to mobilize sediment bound As. Overall observations suggest that

  12. Microcosm studies on iron and arsenic mobilization from aquifer sediments under different conditions of microbial activity and carbon source

    Science.gov (United States)

    Duan, Mengyu; Xie, Zuoming; Wang, Yanxin; Xie, Xianjun

    2009-05-01

    Microcosm experiments were conducted to understand the mechanism of microbially mediated mobilization of Fe and As from high arsenic aquifer sediments. Arsenic-resistant strains isolated from aquifer sediments of a borehole specifically drilled for this study at Datong basin were used as inoculated strains, and glucose and sodium acetate as carbon sources for the experiments. In abiotic control experiments, the maximum concentrations of Fe and As were only 0.47 mg/L and 0.9 μg/L, respectively. By contrast, the maximum contents of Fe and As in anaerobic microcosm experiments were much higher (up to 1.82 mg/L and 12.91 μg/L, respectively), indicating the crucial roles of microbial activities in Fe and As mobilization. The observed difference in Fe and As release with different carbon sources may be related to the difference in growth pattern and composition of microbial communities that develop in response to the type of carbon sources.

  13. The chromatographic behavior of arsenic compounds on anion exchange columns with binary organic acids as mobile phases

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, J.; Goessler, W.; Kosmus, W. [Graz Univ. (Austria). Inst. fuer Analytische Chemie

    1998-03-01

    Identification and quantification of arsenic compounds was performed with high-performance liquid chromatography (HPLC) and flame atomic absorption spectrometry (FAAS) as element-specific detector. Arsenous acid, methylarsonic acid, dimethylarsinic acid, arsenic acid, arsenobetaine, and arsenocholine were separated on two anion-exchange columns (Synchropak Q 300 and PRP-X 100) with different binary organic acids as mobile phases. The influence of chromatographic parameters, such as pH and the concentration of the mobile phase were investigated. An unusual chromatographic behavior of arsenous acid was observed when tartaric acid was used as mobile phase. (orig.)

  14. Trace metal distribution and mobility in drill cuttings and produced waters from Marcellus Shale gas extraction: Uranium, arsenic, barium

    International Nuclear Information System (INIS)

    Phan, Thai T.; Capo, Rosemary C.; Stewart, Brian W.; Graney, Joseph R.; Johnson, Jason D.; Sharma, Shikha; Toro, Jaime

    2015-01-01

    -bearing minerals in drill cuttings would likely be followed by immobilization of U in secondary minerals such as schoepite, uranophane, and soddyite, or uraninite as conditions become more reducing. Oxidative dissolution of arsenic containing sulfides could release soluble As in arsenate form under oxic acidic conditions. The degree to which the As is subsequently immobilized depends on the redox conditions along the landfill flow path. The results suggest that proper management of drill cuttings can minimize mobilization of these metals by monitoring and controlling Eh, pH and dissolved constituents in landfill leachates

  15. Linking geochemical processes in mud volcanoes with arsenic mobilization driven by organic matter.

    Science.gov (United States)

    Liu, Chia-Chuan; Kar, Sandeep; Jean, Jiin-Shuh; Wang, Chung-Ho; Lee, Yao-Chang; Sracek, Ondra; Li, Zhaohui; Bundschuh, Jochen; Yang, Huai-Jen; Chen, Chien-Yen

    2013-11-15

    The present study deals with geochemical characterization of mud fluids and sediments collected from Kunshuiping (KSP), Liyushan (LYS), Wushanting (WST), Sinyangnyuhu (SYNH), Hsiaokunshui (HKS) and Yenshuikeng (YSK) mud volcanoes in southwestern Taiwan. Chemical constituents (cations, anions, trace elements, organic carbon, humic acid, and stable isotopes) in both fluids and mud were analyzed to investigate the geochemical processes and spatial variability among the mud volcanoes under consideration. Analytical results suggested that the anoxic mud volcanic fluids are highly saline, implying connate water as the probable source. The isotopic signature indicated that δ(18)O-rich fluids may be associated with silicate and carbonate mineral released through water-rock interaction, along with dehydration of clay minerals. Considerable amounts of arsenic in mud irrespective of fluid composition suggested possible release through biogeochemical processes in the subsurface environment. Sequential extraction of As from the mud indicated that As was mostly present in organic and sulphidic phases, and adsorbed on amorphous Mn oxyhydroxides. Volcanic mud and fluids are rich in organic matter (in terms of organic carbon), and the presence of humic acid in mud has implications for the binding of arsenic. Functional groups of humic acid also showed variable sources of organic matter among the mud volcanoes being examined. Because arsenate concentration in the mud fluids was found to be independent from geochemical factors, it was considered that organic matter may induce arsenic mobilization through an adsorption/desorption mechanism with humic substances under reducing conditions. Organic matter therefore plays a significant role in the mobility of arsenic in mud volcanoes. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Linking geochemical processes in mud volcanoes with arsenic mobilization driven by organic matter

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chia-Chuan; Kar, Sandeep [Department of Earth Sciences, National Cheng Kung University, Tainan, Taiwan (China); Jean, Jiin-Shuh, E-mail: jiinshuh@mail.ncku.edu.tw [Department of Earth Sciences, National Cheng Kung University, Tainan, Taiwan (China); Wang, Chung-Ho [Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan (China); Lee, Yao-Chang [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Sracek, Ondra [OPV s.r.o. (Groundwater Protection Ltd.), Bělohorská 31, 169 00 Praha 6 (Czech Republic); Department of Geology, Faculty of Science, Palacký University, 17. listopadu 12, 771 46 Olomouc (Czech Republic); Li, Zhaohui [Department of Earth Sciences, National Cheng Kung University, Tainan, Taiwan (China); Department of Geosciences, University of Wisconsin – Parkside, Kenosha, WI 53144 (United States); Bundschuh, Jochen [Department of Earth Sciences, National Cheng Kung University, Tainan, Taiwan (China); Faculty of Engineering and Surveying and National Centre for Engineering in Agriculture, The University of Southern Queensland, Toowoomba (Australia); Yang, Huai-Jen [Department of Earth Sciences, National Cheng Kung University, Tainan, Taiwan (China); Chen, Chien-Yen [Department of Earth and Environmental Sciences, National Chung Cheng University, Chiayi 621, Taiwan (China)

    2013-11-15

    Highlights: ► Study represents geochemical characteristics and their spatial variability among six mud volcanoes of southern Taiwan. ► Anoxic mud volcanic fluids containing high NaCl imply connate water as the possible source. ► δ{sup 18}O-rich fluids is associated with silicate and carbonate mineral released through water–rock interaction. ► High As content in mud and its sequential extraction showed mostly adsorbed As on organic and sulphidic phases. ► Organic matter specially humic acid showed redox dependence and it may play an important role in binding and mobility of arsenic. -- Abstract: The present study deals with geochemical characterization of mud fluids and sediments collected from Kunshuiping (KSP), Liyushan (LYS), Wushanting (WST), Sinyangnyuhu (SYNH), Hsiaokunshui (HKS) and Yenshuikeng (YSK) mud volcanoes in southwestern Taiwan. Chemical constituents (cations, anions, trace elements, organic carbon, humic acid, and stable isotopes) in both fluids and mud were analyzed to investigate the geochemical processes and spatial variability among the mud volcanoes under consideration. Analytical results suggested that the anoxic mud volcanic fluids are highly saline, implying connate water as the probable source. The isotopic signature indicated that δ{sup 18}O-rich fluids may be associated with silicate and carbonate mineral released through water–rock interaction, along with dehydration of clay minerals. Considerable amounts of arsenic in mud irrespective of fluid composition suggested possible release through biogeochemical processes in the subsurface environment. Sequential extraction of As from the mud indicated that As was mostly present in organic and sulphidic phases, and adsorbed on amorphous Mn oxyhydroxides. Volcanic mud and fluids are rich in organic matter (in terms of organic carbon), and the presence of humic acid in mud has implications for the binding of arsenic. Functional groups of humic acid also showed variable sources of

  17. Behavioral Determinants of Switching to Arsenic-Safe Water Wells: An Analysis of a Randomized Controlled Trial of Health Education Interventions Coupled With Water Arsenic Testing

    Science.gov (United States)

    George, Christine Marie; Inauen, Jennifer; Perin, Jamie; Tighe, Jennifer; Hasan, Khaled; Zheng, Yan

    2017-01-01

    More than 100 million people globally are estimated to be exposed to arsenic in drinking water that exceeds the World Health Organization guideline of 10 µg/L. In an effort to develop and test a low-cost sustainable approach for water arsenic testing in Bangladesh, we conducted a randomized controlled trial which found arsenic educational…

  18. Arsenic mobilization and speciation during iron plaque decomposition in a paddy soil

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Hai; Chen, Zheng; Sun, Guoxin [Chinese Academy of Sciences, Beijing (China). Research Center for Eco-environmental Sciences; Zhu, Yongguan [Chinese Academy of Sciences, Beijing (China). Research Center for Eco-environmental Sciences; Chinese Academy of Sciences, Xiamen (China). Key Lab. of Urban Environment and Health; Yin, Xixiang [Chinese Academy of Sciences, Xiamen (China). Key Lab. of Urban Environment and Health; Chinese Academy of Sciences, Beijing (China). Research Center for Eco-environmental Sciences

    2012-03-15

    Little information is available concerning the mobilization and speciation of arsenic (As) in paddy soils during iron plaque decomposition. It is important to investigate these processes since they affect As bioavailability and contaminate surface and ground water systems. A microcosm experiment was conducted to investigate the reductive dissolution of iron plaque and subsequent As mobilization under NaN{sub 3} sterilized (abiotic treatments) and non-sterilized (biotic treatments) paddy soil conditions. In the biotic treatment, As and iron (Fe) were quickly released into the soil solution, with more than 76.1% of total arsenic (T{sub As}) on the roots lost in 27 days. In the abiotic treatment, both iron plaque decomposition and As release were significantly slower, with only 39.4% of T{sub As} on the roots lost in 85 days. A part of arsenate reduction reaction occurred before and may also occur after release from roots in both abiotic and biotic treatments. Bacterial abundance, quantified by real-time PCR, varied significantly between treatments. Terminal restriction fragment length polymorphism combined with principal component analysis (PCA) revealed that microbial community structures were also different between treatments. The changes in microbial factors (bacterial abundance and microbial diversity and activities) significantly affected iron plaque decomposition, As mobilization, and speciation processes. Iron plaque reductive dissolution was likely the major factor leading to As release. Most As released was trapped in the solid phase during the incubation period. (orig.)

  19. Arsenic mineral dissolution and possible mobilization in mineral–microbe–groundwater environment

    International Nuclear Information System (INIS)

    Islam, A.B.M.R.; Maity, Jyoti Prakash; Bundschuh, Jochen; Chen, Chien-Yen; Bhowmik, Bejon Kumar; Tazaki, Kazue

    2013-01-01

    Highlights: ► Bacteria use arsenic minerals for their growth without supplementary nutrient. ► Enzymatically active bacteria survive in the arsenic contaminated environment. ► Mostly bacillus, coccus and filamentous dissolves the arsenic mineral. ► Except enargite, soluble-As was detected with respect to other arsenic mineral. ► Dissolution: native-As > arsenolite > orpiment > realgar > arsenopyrite > tennantite. -- Abstract: Arsenic (As) is widely distributed in the nature as ores or minerals. It has been attracted much attention for the global public health issue, especially for groundwater As contamination. The aim of this study was to elucidate the characteristics of microbes in groundwater where As-minerals were dissolved. An ex situ experiment was conducted with 7 standard As-minerals in bacteria-free groundwater and stored in experimental vessels for 1 year without supplementary nutrients. The pH (6.7–8.4) and Eh S.H.E. (24–548 mV) changed between initial (0 day) and final stages (365 days) of experiment. The dissolution of As was detected higher from arsenolite (4240 ± 8.69 mg/L) and native arsenic (4538 ± 9.02 mg/L), whereas moderately dissolved from orpiment (653 ± 3.56 mg/L) and realgar (319 ± 2.56 mg/L) in compare to arsenopyrite (85 ± 1.25 mg/L) and tennantite (3 ± 0.06 mg/L). Optical microscopic, scanning electron microscopic observations and flurometric enumeration revealed the abundance of As-resistant bacillus, coccus and filamentous types of microorganisms on the surface of most of As-mineral. 4′-6-Diamidino-2-phenylindole (DAPI)-stained epifluorescence micrograph confirmed the presence of DNA and carboxyfluorescein diacetate (CFDA) staining method revealed the enzymatically active bacteria on the surface of As-minerals such as in realgar (As 4 S 4 ). Therefore, the microbes enable to survive and mobilize the As in groundwater by dissolution/bioweathering of As-minerals

  20. Arsenic mineral dissolution and possible mobilization in mineral–microbe–groundwater environment

    Energy Technology Data Exchange (ETDEWEB)

    Islam, A.B.M.R., E-mail: uttambangla@yahoo.com [Department of Human Ecology, School of International Health, Graduate School of Medicine, The University of Tokyo,7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); ITO Public Nuisance Research Institute, 1-26-8, Omori Kita, Otaku, Tokyo 142-0016 (Japan); Maity, Jyoti Prakash, E-mail: jyoti_maity@yahoo.com [Department of Earth and Environmental Sciences, National Chung Cheng University, 168 University Road, Ming-Shung, Chiayi County 62102, Taiwan (China); Bundschuh, Jochen [Faculty of Engineering and Surveying, University of Southern Queensland, Toowoomba, Queensland 435 (Australia); KTH-International Groundwater Arsenic Research Group, Department of Land and Water Resources Engineering, Royal Institute of Technology (KTH) Teknikringen 76,SE-10044 Stockholm (Sweden); Department of Earth Sciences, National Cheng Kung University, University Road, Tainan, 70101, Taiwan (China); Chen, Chien-Yen [Department of Earth and Environmental Sciences, National Chung Cheng University, 168 University Road, Ming-Shung, Chiayi County 62102, Taiwan (China); Bhowmik, Bejon Kumar [Department of Biotechnology, Graduate School of Agriculture and Life science, The University of Tokyo, 1-1-1,Yayoi, Bunkyo-ku, Tokyo 113-0033 (Japan); Tazaki, Kazue [Department of Earth Sciences, Faculty of Science, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192 (Japan)

    2013-11-15

    Highlights: ► Bacteria use arsenic minerals for their growth without supplementary nutrient. ► Enzymatically active bacteria survive in the arsenic contaminated environment. ► Mostly bacillus, coccus and filamentous dissolves the arsenic mineral. ► Except enargite, soluble-As was detected with respect to other arsenic mineral. ► Dissolution: native-As > arsenolite > orpiment > realgar > arsenopyrite > tennantite. -- Abstract: Arsenic (As) is widely distributed in the nature as ores or minerals. It has been attracted much attention for the global public health issue, especially for groundwater As contamination. The aim of this study was to elucidate the characteristics of microbes in groundwater where As-minerals were dissolved. An ex situ experiment was conducted with 7 standard As-minerals in bacteria-free groundwater and stored in experimental vessels for 1 year without supplementary nutrients. The pH (6.7–8.4) and Eh{sub S.H.E.} (24–548 mV) changed between initial (0 day) and final stages (365 days) of experiment. The dissolution of As was detected higher from arsenolite (4240 ± 8.69 mg/L) and native arsenic (4538 ± 9.02 mg/L), whereas moderately dissolved from orpiment (653 ± 3.56 mg/L) and realgar (319 ± 2.56 mg/L) in compare to arsenopyrite (85 ± 1.25 mg/L) and tennantite (3 ± 0.06 mg/L). Optical microscopic, scanning electron microscopic observations and flurometric enumeration revealed the abundance of As-resistant bacillus, coccus and filamentous types of microorganisms on the surface of most of As-mineral. 4′-6-Diamidino-2-phenylindole (DAPI)-stained epifluorescence micrograph confirmed the presence of DNA and carboxyfluorescein diacetate (CFDA) staining method revealed the enzymatically active bacteria on the surface of As-minerals such as in realgar (As{sub 4}S{sub 4}). Therefore, the microbes enable to survive and mobilize the As in groundwater by dissolution/bioweathering of As-minerals.

  1. Influence of traditional agricultural practices on mobilization of arsenic from sediments to groundwater in Bengal delta.

    Science.gov (United States)

    Farooq, S H; Chandrasekharam, D; Berner, Z; Norra, S; Stüben, D

    2010-11-01

    In the wake of the idea that surface derived dissolved organic carbon (DOC) plays an important role in the mobilization of arsenic (As) from sediments to groundwater and may provide a vital tool in understanding the mechanism of As contamination (mobilization/fixation) in Bengal delta; a study has been carried out. Agricultural fields that mainly cultivate rice (paddy fields) leave significantly large quantities of organic matter/organic carbon on the surface of Bengal delta which during monsoon starts decomposing and produces DOC. The DOC thus produced percolates down with rain water and mobilizes As from the sediments. Investigations on sediment samples collected from a paddy field clearly indicate that As coming on to the surface along with the irrigation water accumulates itself in the top few meters of sediment profile. The column experiments carried out on a 9 m deep sediment profile demonstrates that DOC has a strong potential to mobilize As from the paddy fields and the water recharging the aquifer through such agricultural fields contain As well above the WHO limit thus contaminating the shallow groundwater. Experiment also demonstrates that decay of organic matter induces reducing condition in the sediments. Progressively increasing reducing conditions not only prevent the adsorption of As on mineral surfaces but also cause mobilization of previously sorbed arsenic. There seems to be a cyclic pattern where As from deeper levels comes to the surface with irrigational water, accumulates itself in the sediments, and ultimately moves down to the shallow groundwater. The extensive and continual exploitation of intermediate/deep groundwater accelerates this cyclic process and helps in the movement of shallow contaminated groundwater to the deeper levels. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Chemical controls on abiotic and biotic release of geogenic arsenic from Pleistocene aquifer sediments to groundwater.

    Science.gov (United States)

    Gillispie, Elizabeth C; Andujar, Erika; Polizzotto, Matthew L

    2016-08-10

    Over 150 million people in South and Southeast Asia consume unsafe drinking water from arsenic-rich Holocene aquifers. Although use of As-free water from Pleistocene aquifers is a potential mitigation strategy, such aquifers are vulnerable to geogenic As pollution, placing millions more people at potential risk. The goal of this research was to define chemical controls on abiotic and biotic release of geogenic As to groundwater. Batch incubations of sediments with natural chemical variability from a Pleistocene aquifer in Cambodia were conducted to evaluate how interactions among arsenic, manganese and iron oxides, and dissolved and sedimentary organic carbon influenced As mobilization from sediments. The addition of labile dissolved organic carbon produced the highest concentrations of dissolved As after >7 months, as compared to sediment samples incubated with sodium azide or without added carbon, and the extent of As release was positively correlated with the percent of initial extractable Mn released from the sediments. The mode of As release was impacted by the source of DOC supplied to the sediments, with biological processes responsible for 81% to 85% of the total As release following incubations with lactate and acetate but only up to 43% to 61% of the total As release following incubations with humic and fulvic acids. Overall, cycling of key redox-active elements and organic-carbon reactivity govern the potential for geogenic As release to groundwater, and results here may be used to formulate better predictions of the arsenic pollution potential of aquifers in South and Southeast Asia.

  3. Dissolution of arsenic minerals mediated by dissimilatory arsenate reducing bacteria: estimation of the physiological potential for arsenic mobilization.

    Science.gov (United States)

    Lukasz, Drewniak; Liwia, Rajpert; Aleksandra, Mantur; Aleksandra, Sklodowska

    2014-01-01

    The aim of this study was characterization of the isolated dissimilatory arsenate reducing bacteria in the context of their potential for arsenic removal from primary arsenic minerals through reductive dissolution. Four strains, Shewanella sp. OM1, Pseudomonas sp. OM2, Aeromonas sp. OM4, and Serratia sp. OM17, capable of anaerobic growth with As (V) reduction, were isolated from microbial mats from an ancient gold mine. All of the isolated strains: (i) produced siderophores that promote dissolution of minerals, (ii) were resistant to dissolved arsenic compounds, (iii) were able to use the dissolved arsenates as the terminal electron acceptor, and (iii) were able to use copper minerals containing arsenic minerals (e.g., enargite) as a respiratory substrate. Based on the results obtained in this study, we postulate that arsenic can be released from some As-bearing polymetallic minerals (such as copper ore concentrates or middlings) under reductive conditions by dissimilatory arsenate reducers in indirect processes.

  4. Dissolution of Arsenic Minerals Mediated by Dissimilatory Arsenate Reducing Bacteria: Estimation of the Physiological Potential for Arsenic Mobilization

    Directory of Open Access Journals (Sweden)

    Drewniak Lukasz

    2014-01-01

    Full Text Available The aim of this study was characterization of the isolated dissimilatory arsenate reducing bacteria in the context of their potential for arsenic removal from primary arsenic minerals through reductive dissolution. Four strains, Shewanella sp. OM1, Pseudomonas sp. OM2, Aeromonas sp. OM4, and Serratia sp. OM17, capable of anaerobic growth with As (V reduction, were isolated from microbial mats from an ancient gold mine. All of the isolated strains: (i produced siderophores that promote dissolution of minerals, (ii were resistant to dissolved arsenic compounds, (iii were able to use the dissolved arsenates as the terminal electron acceptor, and (iii were able to use copper minerals containing arsenic minerals (e.g., enargite as a respiratory substrate. Based on the results obtained in this study, we postulate that arsenic can be released from some As-bearing polymetallic minerals (such as copper ore concentrates or middlings under reductive conditions by dissimilatory arsenate reducers in indirect processes.

  5. Mobilization of arsenic and other naturally occurring contaminants in groundwater of the Main Ethiopian Rift aquifers.

    Science.gov (United States)

    Rango, Tewodros; Vengosh, Avner; Dwyer, Gary; Bianchini, Gianluca

    2013-10-01

    This study investigates the mechanisms of arsenic (As) and other naturally occurring contaminants (F(-), U, V, B, and Mo) mobilization from Quaternary sedimentary aquifers of the Main Ethiopian Rift (MER) and their enrichment in the local groundwater. The study is based on systematic measurements of major and trace elements as well as stable oxygen and hydrogen isotopes in groundwater, coupled with geochemical and mineralogical analyses of the aquifer rocks. The Rift Valley aquifer is composed of rhyolitic volcanics and Quaternary lacustrine sediments. X-ray fluorescence (XRF) results revealed that MER rhyolites (ash, tuff, pumice and ignimbrite) and sediments contain on average 72 wt. % and 65 wt. % SiO2, respectively. Petrographic studies of the rhyolites indicate predominance of volcanic glass, sanidine, pyroxene, Fe-oxides and plagioclase. The As content in the lacustrine sediments (mean = 6.6 mg/kg) was higher than that of the rhyolites (mean: 2.5 mg/kg). The lacustrine aquifers of the Ziway-Shala basin in the northern part of MER were identified as high As risk zones, where mean As concentration in groundwater was 22.4 ± 33.5 (range of 0.60-190 μg/L) and 54% of samples had As above the WHO drinking water guideline value of 10 μg/L. Field As speciation measurements showed that most of the groundwater samples contain predominantly (~80%) arsenate-As(V) over arsenite-As(III) species. The As speciation together with field data of redox potential (mean Eh = +73 ± 65 mV) and dissolved-O2 (6.6 ± 2.2 mg/L) suggest that the aquifer is predominantly oxidative. Water-rock interactions, including the dissolution of volcanic glass produces groundwater with near-neutral to alkaline pH (range 6.9-8.9), predominance of Na-HCO3 ions, and high concentration of SiO2 (mean: 85.8 ± 11.3 mg/L). The groundwater data show high positive correlation of As with Na, HCO3, U, B, V, and Mo (R(2) > 0.5; p groundwater indicates that Fe-oxides and oxyhydroxides minerals were saturated

  6. Arsenic mobility in brownfield soils amended with green waste compost or biochar and planted with Miscanthus

    International Nuclear Information System (INIS)

    Hartley, William; Dickinson, Nicholas M.; Riby, Philip; Lepp, Nicholas W.

    2009-01-01

    Degraded land that is historically contaminated from different sources of industrial waste provides an opportunity for conversion to bioenergy fuel production and also to increase sequestration of carbon in soil through organic amendments. In pot experiments, As mobility was investigated in three different brownfield soils amended with green waste compost (GWC, 30% v/v) or biochar (BC, 20% v/v), planted with Miscanthus. Using GWC improved crop yield but had little effect on foliar As uptake, although the proportion of As transferred from roots to foliage differed considerably between the three soils. It also increased dissolved carbon concentrations in soil pore water that influenced Fe and As mobility. Effects of BC were less pronounced, but the impacts of both amendments on SOC, Fe, P and pH are likely to be critical in the context of As leaching to ground water. Growing Miscanthus had no measurable effect on As mobility. - Green waste compost enhances water-soluble iron, phosphorus and carbon, increasing arsenic mobility in soil pore water.

  7. Sampling technologies and air pollution control devices for gaseous and particulate arsenic: a review

    International Nuclear Information System (INIS)

    Helsen, Lieve

    2005-01-01

    Direct measurement of arsenic release requires a good sampling and analysis procedure in order to capture and detect the total amount of metals emitted. The literature is extensively reviewed in order to evaluate the efficiency of full field-scale and laboratory scale techniques for capturing particulate and gaseous emissions of arsenic from the thermo-chemical treatment of different sources of arsenic. Furthermore, trace arsenic concentrations in ambient air, national standard sampling methods and arsenic analysis methods are considered. Besides sampling techniques, the use of sorbents is also reviewed with respect to both approaches (1) to prevent the metals from exiting with the flue gas and (2) to react or combine with the metals in order to be collected in air pollution control systems. The most important conclusion is that submicron arsenic fumes are difficult to control in conventional air pollution control devices. Complete capture of the arsenic species requires a combination of particle control and vapour control devices. - Submicron arsenic fumes are difficult to control in conventional air pollution control devices

  8. On mobilization of lead and arsenic in groundwater in response to CO2 leakage from deep geological storage

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, L.; Apps, J.A.; Zhang, Y.; Xu, T.; Birkholzer, J.T.

    2009-07-01

    If carbon dioxide stored in deep saline aquifers were to leak into an overlying aquifer containing potable groundwater, the intruding CO{sub 2} would change the geochemical conditions and cause secondary effects mainly induced by changes in pH In particular, hazardous trace elements such as lead and arsenic, which are present in the aquifer host rock, could be mobilized. In an effort to evaluate the potential risks to potable water quality, reactive transport simulations were conducted to evaluate to what extent and mechanisms through which lead and arsenic might be mobilized by intrusion of CO{sub 2}. An earlier geochemical evaluation of more than 38,000 groundwater quality analyses from aquifers throughout the United States and an associated literature review provided the basis for setting up a reactive transport model and examining its sensitivity to model variation. The evaluation included identification of potential mineral hosts containing hazardous trace elements, characterization of the modal bulk mineralogy for an arenaceous aquifer, and augmentation of the required thermodynamic data. The reactive transport simulations suggest that CO{sub 2} ingress into a shallow aquifer can mobilize significant lead and arsenic, contaminating the groundwater near the location of intrusion and further downstream. Although substantial increases in aqueous concentrations are predicted compared to the background values, the maximum permitted concentration for arsenic in drinking water was exceeded in only a few cases, whereas that for lead was never exceeded.

  9. Impact of Varying Wave Conditions on the Mobility of Arsenic in a Nearshore Aquifer on the Great Lakes

    Science.gov (United States)

    Rakhimbekova, S.; O'Carroll, D. M.; Robinson, C. E.

    2017-12-01

    Groundwater-coastal water interactions play an important role in controlling the behavior of inorganic chemicals in nearshore aquifers and the subsequent flux of these chemicals to receiving coastal waters. Previous studies have shown that dynamic groundwater flows and water exchange across the sediment-water interface can set up strong geochemical gradients and an important reaction zone in a nearshore aquifer that affect the fate of reactive chemicals. There is limited understanding of the impact of transient coastal forcing such as wave conditions on groundwater dynamics and geochemistry in a nearshore aquifer. The goal of this study was to assess the impact of intensified wave conditions on the behavior of arsenic in a nearshore aquifer and to determine the hydrological and geochemical factors controlling its fate and ultimate delivery to receiving coastal waters. Field investigations were conducted over the period of intensified wave conditions on a freshwater beach on Lake Erie, Canada. High spatial resolution aqueous and sediment sampling was conducted to characterize the subsurface distribution of inorganic species in the nearshore aquifer. Numerical groundwater flow and transport simulations were conducted to evaluate wave-induced perturbations in the flow dynamics including characterizing changes in the groundwater flow recirculations in the nearshore aquifer. The combination of field data and numerical simulations reveal that varying wave conditions alter groundwater flows and set up geochemical transition zones within the aquifer resulting in the release and sequestration of arsenic. Interactions between oxic surface water, mildly reducing shallow groundwater, and reducing sulfur- and iron-rich deep groundwater promote dynamic iron, sulfur and manganese cycling which control the mobility of arsenic in the aquifer. The findings of this study have potential implications for the fate and transport of other reactive chemicals (e.g. phosphorus, mercury) in

  10. Arsenic mobilization in a freshening groundwater system formed within glaciomarine deposits

    International Nuclear Information System (INIS)

    Cavalcanti de Albuquerque, R.; Kirste, D.

    2012-01-01

    Arsenic release to groundwater and conditions favoring As mobility are investigated in a system of aquifers formed within unconsolidated Quaternary sediments. The studied groundwater system is comprised of unconfined aquifers formed in glaciofluvial sediments with Ca–Mg–HCO 3 groundwater, and confined aquifers formed within glaciomarine sediments with high As (above 10 μg/L) Na–HCO 3 or Na–Cl groundwater. A positive relationship of As concentrations with the Na/(Ca + Mg) ratio of groundwater indicates that As release occurs in glaciomarine sediments concurrent to cation exchange reactions related to groundwater freshening. Arsenic is mobile in confined aquifers as a result of groundwater basic pH which prevents arsenate from adsorbing to mineral surfaces, and reducing conditions that favor speciation to arsenite. Selected extractions applied to sediment core samples indicate that As occurs in sediments predominantly in sulfide minerals and in Mn oxides and/or Fe oxyhydroxides. General positive relationships between As and the reduced species Fe 2+ , NH 3 and dissolved S 2− suggest that As release occurs at increasingly reducing conditions. Despite likely As release via Fe oxyhydroxide reductive dissolution, Fe remains at relatively low concentrations in groundwater (up to 0.37 mg/L) as a result of possible Fe adsorption and Fe reprecipitation as carbonate minerals favored by basic pH and high alkalinity. The presence of S 2− in some samples, a negative relationship between δ 34 S of SO 4 and SO 4 2- concentrations, and a positive relationship between δ 34 S and δ 18 O of SO 4 indicate that groundwater in confined aquifers is undergoing bacterial SO 4 reduction.

  11. Assessing the influence of compost and biochar amendments on the mobility and toxicity of metals and arsenic in a naturally contaminated mine soil.

    Science.gov (United States)

    Beesley, Luke; Inneh, Onyeka S; Norton, Gareth J; Moreno-Jimenez, Eduardo; Pardo, Tania; Clemente, Rafael; Dawson, Julian J C

    2014-03-01

    Amending contaminated soils with organic wastes can influence trace element mobility and toxicity. Soluble concentrations of metals and arsenic were measured in pore water and aqueous soil extracts following the amendment of a heavily contaminated mine soil with compost and biochar (10% v:v) in a pot experiment. Speciation modelling and toxicity assays (Vibrio fischeri luminescence inhibition and Lolium perenne germination) were performed to discriminate mechanisms controlling metal mobility and assess toxicity risk thereafter. Biochar reduced free metal concentrations furthest but dissolved organic carbon primarily controlled metal mobility after compost amendment. Individually, both amendments induced considerable solubilisation of arsenic to pore water (>2500 μg l(-1)) related to pH and soluble phosphate but combining amendments most effectively reduced toxicity due to simultaneous reductions in extractable metals and increases in soluble nutrients (P). Thus the measure-monitor-model approach taken determined that combining the amendments was most effective at mitigating attendant toxicity risk. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Arsenic mobility and speciation in a contaminated urban soil are affected by different methods of green waste compost application

    Energy Technology Data Exchange (ETDEWEB)

    Hartley, William, E-mail: w.hartley@ljmu.ac.u [Liverpool John Moores University, Faculty of Science, Byrom Street, Liverpool L3 3AF (United Kingdom); Dickinson, Nicholas M.; Riby, Philip [Liverpool John Moores University, Faculty of Science, Byrom Street, Liverpool L3 3AF (United Kingdom); Leese, Elizabeth; Morton, Jackie [Health and Safety Laboratory, Harpur Hill, Buxton, Derbyshire SK17 9JN (United Kingdom); Lepp, Nicholas W., E-mail: nickandeileenlepp@hotmail.co [35 Victoria Road, Formby L37 7DH (United Kingdom)

    2010-12-15

    Application of green waste compost (GWC) to brownfield land is now common practice in soil restoration. However, previous studies have demonstrated both beneficial and detrimental effects on arsenic and metal mobility. In this paper, trace element behaviour was investigated following GWC application, either as surface mulch to, or mixed into soil from a previously described brownfield site in the U.K. Significant differences in arsenic mobility were observed between treatments. Mulching caused most disturbance, significantly increasing soil pore water As, together with Fe, P, Cr, Ni and dissolved organic carbon, the latter was a critical factor enhancing As mobilization. Arsenate was the main inorganic As species in soil pore water, increasing in concentration over time. An initial flush of potentially more toxic arsenite decreased 4 weeks after compost application. Biological processes appeared to play an important role in influencing As mobility. The results point to the necessity for careful management of As-contaminated soils. - A comparison of mulching and mixing of green waste compost to an urban soil results in differences in arsenic and metal leaching.

  13. Arsenic mobility and speciation in a contaminated urban soil are affected by different methods of green waste compost application

    International Nuclear Information System (INIS)

    Hartley, William; Dickinson, Nicholas M.; Riby, Philip; Leese, Elizabeth; Morton, Jackie; Lepp, Nicholas W.

    2010-01-01

    Application of green waste compost (GWC) to brownfield land is now common practice in soil restoration. However, previous studies have demonstrated both beneficial and detrimental effects on arsenic and metal mobility. In this paper, trace element behaviour was investigated following GWC application, either as surface mulch to, or mixed into soil from a previously described brownfield site in the U.K. Significant differences in arsenic mobility were observed between treatments. Mulching caused most disturbance, significantly increasing soil pore water As, together with Fe, P, Cr, Ni and dissolved organic carbon, the latter was a critical factor enhancing As mobilization. Arsenate was the main inorganic As species in soil pore water, increasing in concentration over time. An initial flush of potentially more toxic arsenite decreased 4 weeks after compost application. Biological processes appeared to play an important role in influencing As mobility. The results point to the necessity for careful management of As-contaminated soils. - A comparison of mulching and mixing of green waste compost to an urban soil results in differences in arsenic and metal leaching.

  14. Arsenic mineral dissolution and possible mobilization in mineral-microbe-groundwater environment.

    Science.gov (United States)

    Islam, A B M R; Maity, Jyoti Prakash; Bundschuh, Jochen; Chen, Chien-Yen; Bhowmik, Bejon Kumar; Tazaki, Kazue

    2013-11-15

    Arsenic (As) is widely distributed in the nature as ores or minerals. It has been attracted much attention for the global public health issue, especially for groundwater As contamination. The aim of this study was to elucidate the characteristics of microbes in groundwater where As-minerals were dissolved. An ex situ experiment was conducted with 7 standard As-minerals in bacteria-free groundwater and stored in experimental vessels for 1 year without supplementary nutrients. The pH (6.7-8.4) and EhS.H.E. (24-548 mV) changed between initial (0 day) and final stages (365 days) of experiment. The dissolution of As was detected higher from arsenolite (4240 ± 8.69 mg/L) and native arsenic (4538 ± 9.02 mg/L), whereas moderately dissolved from orpiment (653 ± 3.56 mg/L) and realgar (319 ± 2.56 mg/L) in compare to arsenopyrite (85 ± 1.25mg/L) and tennantite (3 ± 0.06 mg/L). Optical microscopic, scanning electron microscopic observations and flurometric enumeration revealed the abundance of As-resistant bacillus, coccus and filamentous types of microorganisms on the surface of most of As-mineral. 4'-6-Diamidino-2-phenylindole (DAPI)-stained epifluorescence micrograph confirmed the presence of DNA and carboxyfluorescein diacetate (CFDA) staining method revealed the enzymatically active bacteria on the surface of As-minerals such as in realgar (As4S4). Therefore, the microbes enable to survive and mobilize the As in groundwater by dissolution/bioweathering of As-minerals. Copyright © 2012. Published by Elsevier B.V.

  15. Regulation of arsenic mobility on basaltic glass surfaces by speciation and pH.

    Science.gov (United States)

    Sigfusson, Bergur; Meharg, Andrew A; Gislason, Sigurdur R

    2008-12-01

    The importance of geothermal energy as a source for electricity generation and district heating has increased over recent decades. Arsenic can be a significant constituent of the geothermal fluids pumped to the surface during power generation. Dissolved As exists in different oxidation states, mainly as As(III) and As(V), and the charge of individual species varies with pH. Basaltic glass is one of the most important rock types in many high-temperature geothermal fields. Static batch and dynamic column experiments were combined to generate and validate sorption coefficients for As(III) and As(V) in contact with basaltic glass at pH 3-10. Validation was carried out by two empirical kinetic models and a surface complexation model (SCM). The SCM provided a better fit to the experimental column data than kinetic models at high pH values. However, in certain circumstances, an adequate estimation of As transport in the column could not be attained without incorporation of kinetic reactions. The varying mobility with pH was due to the combined effects of the variable charge of the basaltic glass with the pH point of zero charge at 6.8 and the individual As species as pH shifted, respectively. The mobility of As(III) decreased with increasing pH. The opposite was true for As(V), being nearly immobile at pH 3 to being highly mobile at pH 10. Incorporation of appropriate sorption constants, based on the measured pH and Eh of geothermal fluids, into regional groundwater-flow models should allow prediction of the As(III) and As(V) transport from geothermal systems to adjacent drinking water sources and ecosystems.

  16. Arsenic in groundwater: a summary of sources and the biogeochemical and hydrogeologic factors affecting arsenic occurrence and mobility

    Science.gov (United States)

    Barringer, Julia L.; Reilly, Pamela A.; Bradley, Paul M.

    2013-01-01

    Arsenic (As) is a metalloid element (atomic number 33) with one naturally occurring isotope of atomic mass 75, and four oxidation states (-3, 0, +3, and +5) (Smedley and Kinniburgh, 2002). In the aqueous environment, the +3 and +5 oxidation states are most prevalent, as the oxyanions arsenite (H3AsO3 or H2AsO3- at pH ~9-11) and arsenate (H2AsO4- and HAsO42- at pH ~4-10) (Smedley and Kinniburgh, 2002). In soils, arsine gases (containing As3-) may be generated by fungi and other organisms (Woolson, 1977). The different forms of As have different toxicities, with arsine gas being the most toxic form. Of the inorganic oxyanions, arsenite is considered more toxic than arsenate, and the organic (methylated) arsenic forms are considered least toxic (for a detailed discussion of toxicity issues, the reader is referred to Mandal and Suzuki (2002)). Arsenic is a global health concern due to its toxicity and the fact that it occurs at unhealthful levels in water supplies, particularly groundwater, in more than 70 countries (Ravenscroft et al., 2009) on six continents.

  17. Contrasting controls on arsenic and lead budgets for a degraded peatland catchment in Northern England

    International Nuclear Information System (INIS)

    Rothwell, James J.; Taylor, Kevin G.; Evans, Martin G.; Allott, Timothy E.H.

    2011-01-01

    Atmospheric deposition of trace metals and metalloids from anthropogenic sources has led to the contamination of many European peatlands. To assess the fate and behaviour of previously deposited arsenic and lead, we constructed catchment-scale mass budgets for a degraded peatland in Northern England. Our results show a large net export of both lead and arsenic via runoff (282 ± 21.3 gPb ha -1 y -1 and 60.4 ± 10.5 gAs ha -1 y -1 ), but contrasting controls on this release. Suspended particulates account for the majority of lead export, whereas the aqueous phase dominates arsenic export. Lead release is driven by geomorphological processes and is a primary effect of erosion. Arsenic release is driven by the formation of a redox-dynamic zone in the peat associated with water table drawdown, a secondary effect of gully erosion. Degradation of peatland environments by natural and anthropogenic processes has the potential to release the accumulated pool of legacy contaminants to surface waters. - Highlights: → The fluvial outputs of arsenic and lead in the degraded peatland are an order-of-magnitude greater than atmospheric inputs. → The particulate phase dominates fluvial lead export, whereas the aqueous phase dominates fluvial arsenic export. → Lead export is a primary effect of peat erosion, whereas arsenic export is a secondary effect of peat erosion. - Degraded peatlands can be significant sources of previously deposited arsenic and lead

  18. The characterization, mobility, and persistence of roaster-derived arsenic in soils at Giant Mine, NWT

    Energy Technology Data Exchange (ETDEWEB)

    Bromstad, Mackenzie J.; Wrye, Lori A.; Jamieson, Heather E.

    2017-07-01

    Approximately 20,000 tonnes of arsenic (As)-bearing emissions from roasting gold (Au)-bearing arsenopyrite ore were aerially released from 1949 to 1999 at Giant Mine, near Yellowknife, Canada. Soil samples collected within 4 km of the former roaster from sites undisturbed by mining or other human activity contain up to 7700 mg/kg total As. Total As concentrations are highest within a few cm of the surface, and particularly enriched in soil pockets on rock outcrops. Scanning electron microscopy and synchrotron microanalysis show that roaster-derived arsenic trioxide (As2O3) has persisted in shallow soils in the area. Roaster-generated maghemite and hematite are also present. These anthropogenic forms of As are much more common in near-surface soils than natural As-bearing minerals. Comparison of the proportions of As, Sb, and Au concentrations in outcrop soil samples and historic As2O3-rich dust captured by emission controls suggest most of the roaster-derived As in soils at Giant was likely deposited before 1964. Topographic restriction by rock outcrops and a dry, cold climate likely contribute to the persistence of As2O3 in outcrop soils.

  19. Arsenic mobility and bioavailability in paddy soil under iron compound amendments at different growth stages of rice.

    Science.gov (United States)

    Yu, Huan-Yun; Wang, Xiangqin; Li, Fangbai; Li, Bin; Liu, Chuanping; Wang, Qi; Lei, Jing

    2017-05-01

    Iron (Fe)-based solids can reduce arsenic (As) mobility and bioavailability in soils, which has been well recognized. However, to our knowledge, there are few studies on As uptake at different growth stages of rice under Fe compound amendments. In addition, the formation of Fe plaques at different growth stages of rice has also been rarely reported. Therefore, the present study was undertaken to investigate As mobility and bioavailability in paddy soil under Fe compound amendments throughout the whole growth stage of rice plants. Amendments of poorly crystalline Fe oxides (PC-Fe), FeCl 2 +NaNO 3 and FeCl 2 reduced grain As by 54% ± 3.0%, 52% ± 3.0% and 46% ± 17%, respectively, compared with that of the non-amended control. The filling stage was suggested to be the key stage to take measures to reduce As uptake. At this stage, all soil amendments significantly reduced As accumulation in rice plants. At the maturation stage, PC-Fe amendment significantly reduced mobile pools and increased immobile pools of soil As. Besides, PC-Fe treatment promoted the transformation of Fe fractions from dissolved Fe to adsorbed, poorly crystalline and free Fe oxides. Moreover, significant positive correlations between soil Fe fractions and As fractions were found. Accordingly, we hypothesized that Fe compound amendments might affect the concentration distribution of Fe fractions first and then affect As fractionation in soil and its bioavailability to rice plants indirectly. The formation of Fe plaques varied with growth stages and different treatments. Significantly negative correlations between mobile pools of As and Fe or As in Fe plaques indicated that Fe plaques could immobilize mobile As in soils and thus affect As bioavailability. Overall, the effect of the soil amendments on reduction of As uptake varied with growth stages and different treatments, and further research on the key stage for reducing As uptake is still required. Copyright © 2017 Elsevier Ltd. All

  20. ARSENIC: A Review on Exposure Pathways, Accumulation, Mobility and Transmission into the Human Food Chain.

    Science.gov (United States)

    Arslan, Beste; Djamgoz, Mustafa B A; Akün, Ertan

    This review deals with exposure pathways of arsenic (As), as well as its transfer and uptake processes from its source to the human body. It is proven fact that uptake of inorganic As for a long period can lead to chronic As poisoning and a variety of adverse health effects such as skin, lung and bladder cancer, in addition to cardiovascular diseases, diabetes and gastrointestinal symptoms. As exposure occurs primarily from consumption of potable water containing high amounts of inorganic As and also from consumption of crops cultivated in As contaminated agricultural fields-either naturally or anthropogenically through contaminated air or pesticides-or irrigated with As containing water. In this review, light is shed on the transfer mechanism of As through the food chain and the parameters that enhance mobility of As in the environment. Amounts of As accumulation in plants and the transfer mechanisms are also quite different. These differences in As accumulation, such as in leaves, stems, fruits and roots, are discussed in detail. Moreover, presence of As in some vegetables consumed is given by investigating recent research articles that deal with As concentrations, especially in edible parts. Some comparative data are also presented, concerning the level of concentration of As in rice during washing, cooking and processing stages.

  1. Major and minor arsenic compounds accounting for the total urinary excretion of arsenic following intake of blue mussels (Mytilus edulis): A controlled human study

    DEFF Research Database (Denmark)

    Molin, M.; Ydersbond, T.A.; Ulven, S.M.

    2012-01-01

    Blue mussels (Mytilus edulis) accumulate and biotransform arsenic (As) to a larger variety of arsenicals than most seafood. Eight volunteers ingested a test meal consisting of 150g blue mussel (680μg As), followed by 72h with an identical, low As controlled diet and full urine sampling. We provide...... a complete speciation, with individual patterns, of urinary As excretion. Total As (tAs) urinary excretion was 328±47μg, whereof arsenobetaine (AB) and dimethylarsinate (DMA) accounted for 66% and 21%, respectively. Fifteen minor urinary arsenicals were quantified with inductively coupled plasma mass...... spectrometry (ICPMS) coupled to reverse-phase, anion and cation-exchange high performance liquid chromatography (HPLC). Thio-arsenicals and non-thio minor arsenicals (including inorganic As (iAs) and methylarsonate (MA)) contributed 10% and 7% of the total sum of species excretion, respectively, but there were...

  2. Geochemical Fractionations and Mobility of Arsenic, Lead and Cadmium in Sediments of the Kanto Plain, Japan.

    Science.gov (United States)

    Hossain, Sushmita; Oguchi, Chiaki T.; Hachinohe, Shoichi; Ishiyama, Takashi; Hamamoto, Hideki

    2014-05-01

    Lowland alluvial and floodplain sediment play a major role in transferring heavy metals and other elements to groundwater through sediment water interaction in changing environmental conditions. However identification of geochemical forms of toxic elements such as arsenic (As), lead (Pb) and cadmium (Cd) requires risk assessment of sediment and subsequent groundwater pollution. A four steps sequential extraction procedure was applied to characterize the geochemical fractionations of As, Pb and Cd for 44 sediment samples including one peat sample from middle basin area of the Nakagawa river in the central Kanto plain. The studied sediment profile extended from the bottom of the river to 44 m depth; sediment samples were collected at 1m intervals from a bored core. The existing sedimentary facies in vertical profile are continental, transitional and marine. There are two aquifers in vertical profile; the upper aquifer (15-20m) contains fine to medium sand whereas medium to coarse sand and gravelly sand contain in lower aquifer (37-44m). The total As and Pb contents were measured by the X-Ray Fluorescence analysis which ranged from 4 to 23 mg/kg of As and 10 to 27 mg/kg of Pb in sediment profile. The three trace elements and major heavy metals were determined by ICP/MS and ICP/AES, and major ions were measured by an ion chromatograph. The marine sediment is mainly Ca-SO4 type. The Geochemical analysis showed the order of mobility trends to be As > Pb > Cd for all the steps. The geochemical fractionations order was determined to be Fe-Mn oxide bound > carbonate bound > ion exchangeable > water soluble for As and Pb whereas the order for Cd is carbonate bound > Fe-Mn oxide bound > ion exchangeable > water soluble. The mobility tendency of Pb and Cd showed high in fine silty sediment of marine environment than for those from continental and transitional environments. In the case of As, the potential mobility is very high (>60%) in the riverbed sediments and clayey silt

  3. Mobility of arsenic and its compounds in soil and soil solution: the effect of soil pretreatment and extraction methods.

    Science.gov (United States)

    Száková, J; Tlustos, P; Goessler, W; Frková, Z; Najmanová, J

    2009-12-30

    The effect of soil extraction procedures and/or sample pretreatment (drying, freezing of the soil sample) on the extractability of arsenic and its compounds was tested. In the first part, five extraction procedures were compared with following order of extractable arsenic portions: 2M HNO(3)>0.43 M CH(3)COOH>or=0.05 M EDTA>or=Mehlich III (0.2M CH(3)COOH+0.25 M NH(4)NO(3)+0.013 M HNO(3)+0.015 M NH(4)F+0.001 M EDTA) extraction>water). Additionally, two methods of soil solution sampling were compared, centrifugation of saturated soil and the use of suction cups. The results showed that different sample pretreatments including soil solution sampling could lead to different absolute values of mobile arsenic content in soils. However, the interpretation of the data can lead to similar conclusions as apparent from the comparison of the soil solution sampling methods (r=0.79). For determination of arsenic compounds mild extraction procedures (0.05 M (NH(4))(2)SO(4), 0.01 M CaCl(2), and water) and soil solution sampling using suction cups were compared. Regarding the real soil conditions the extraction of fresh samples and/or in situ collection of soil solution are preferred among the sample pretreatments and/or soil extraction procedures. However, chemical stabilization of the solutions should be allowed and included in the analytical procedures for determination of individual arsenic compounds.

  4. Role of sulfur redox cycling on arsenic mobilization in aquifers of Datong Basin, northern China

    International Nuclear Information System (INIS)

    Pi, Kunfu; Wang, Yanxin; Xie, Xianjun; Ma, Teng; Su, Chunli; Liu, Yaqing

    2017-01-01

    Sulfur redox cycling potentially exerts important influences on arsenic (As) fate in shallow groundwater systems. Hydrochemical and sediment geochemical analysis combined with thermodynamic modeling study were conducted at Datong Basin to elaborate the effects of sulfur redox cycling on As speciation and mobilization under a strongly reducing environment. Dissolved As and sulfide concentration in 32 groundwater samples with depths of 19–40 m below the land surface varied from 8 to 2700 μg/L and from <5 to 490 μg/L, respectively, while dissolved Fe(II) was relatively low ranging from <20 to 280 μg/L. The apparent co-increase in dissolved sulfide and As concentration, especially for samples with As content larger than 500 μg/L, indicates that sulfidogenesis may significantly contribute to the mobilization of As via sulfide-induced reduction of both As-bearing Fe(III) oxide minerals and As(V). Thermodynamic calculations indicate that groundwater As might be also thiolated in the presence of high-level sulfide, particularly to a large extent for As(V) speciation, instead of sequestration by As-sulfide precipitates. Results of sequential extraction and scanning electron microscopy array on sediments indicate the presence of Fe(II) sulfide mineral phases and an appreciable amount of co-existent As in the sediments, suggesting the precipitation of Fe(II) sulfides can restrict the build-up of dissolved Fe(II) and sequester As from groundwater, but not strongly enough, thereby lowering down As to a moderate level of about 500 μg/L. Thus, redox processes involving As, S and Fe species under sulfidic conditions as observed in Datong Basin not only facilitate the enrichment of As(III) species and As(V) potentially existing as thiolated species, but also the depletion of Fe(II) concentration in groundwater due to Fe(II) sulfide formation. - Highlights: • Effects of sulfur redox cycling on As enrichment were clarified in Datong. • Co-increase in aqueous As and

  5. Arsenic mobilization in an oxidizing alkaline groundwater: Experimental studies, comparison and optimization of geochemical modeling parameters

    International Nuclear Information System (INIS)

    Hafeznezami, Saeedreza; Lam, Jacquelyn R.; Xiang, Yang; Reynolds, Matthew D.; Davis, James A.; Lin, Tiffany; Jay, Jennifer A.

    2016-01-01

    Arsenic (As) mobilization and contamination of groundwater affects millions of people worldwide. Progress in developing effective in-situ remediation schemes requires the incorporation of data from laboratory experiments and field samples into calibrated geochemical models. In an oxidizing aquifer where leaching of high pH industrial waste from unlined surface impoundments led to mobilization of naturally occurring As up to 2 mg L −1 , sequential extractions of solid phase As as well as, batch sediment microcosm experiments were conducted to understand As partitioning and solid-phase sorptive and buffering capacity. These data were combined with field data to create a series of geochemical models of the system with modeling programs PHREEQC and FITEQL. Different surface complexation modeling approaches, including component additivity (CA), generalized composite (GC), and a hybrid method were developed, compared and fitted to data from batch acidification experiments to simulate potential remediation scenarios. Several parameters strongly influence the concentration of dissolved As including pH, presence of competing ions (particularly phosphate) and the number of available sorption sites on the aquifer solids. Lowering the pH of groundwater to 7 was found to have a variable, but limited impact (<63%) on decreasing the concentration of dissolved As. The models indicate that in addition to lowering pH, decreasing the concentration of dissolved phosphate and/or increasing the number of available sorption sites could significantly decrease the As solubility to levels below 10 μg L −1 . The hybrid and GC modeling results fit the experimental data well (NRMSE<10%) with reasonable effort and can be implemented in further studies for validation. - Highlights: • Samples were collected from an oxidizing aquifer where high pH waste has led to mobilization of naturally occurring As. • Three surface complexation modeling approaches were used in modeling adsorption

  6. A cluster-based randomized controlled trial promoting community participation in arsenic mitigation efforts in Bangladesh

    OpenAIRE

    George, Christine Marie; van Geen, Alexander; Slavkovich, Vesna; Singha, Ashit; Levy, Diane; Islam, Tariqul; Ahmed, Kazi Matin; Moon-Howard, Joyce; Tarozzi, Alessandro; Liu, Xinhua; Factor-Litvak, Pam; Graziano, Joseph

    2012-01-01

    Abstract Objective To reduce arsenic (As) exposure, we evaluated the effectiveness of training community members to perform water arsenic (WAs) testing and provide As education compared to sending representatives from outside communities to conduct these tasks. Methods We conducted a cluster based randomized controlled trial of 20 villages in Singair, Bangladesh. Fifty eligible respondents were randomly selected in each village. In 10 villages, a community member provided As education and WAs...

  7. Arsenic chemistry in soils and sediments

    Energy Technology Data Exchange (ETDEWEB)

    Fendorf, S.; Nico, P.; Kocar, B.D.; Masue, Y.; Tufano, K.J.

    2009-10-15

    Arsenic is a naturally occurring trace element that poses a threat to human and ecosystem health, particularly when incorporated into food or water supplies. The greatest risk imposed by arsenic to human health results from contamination of drinking water, for which the World Health Organization recommends a maximum limit of 10 {micro}g L{sup -1}. Continued ingestion of drinking water having hazardous levels of arsenic can lead to arsenicosis and cancers of the bladder, skin, lungs and kidneys. Unfortunately, arsenic tainted drinking waters are a global threat and presently having a devastating impact on human health within Asia. Nearly 100 million people, for example, are presently consuming drinking water having arsenic concentrations exceeding the World Health Organization's recommended limit (Ahmed et al., 2006). Arsenic contamination of the environment often results from human activities such as mining or pesticide application, but recently natural sources of arsenic have demonstrated a devastating impact on water quality. Arsenic becomes problematic from a health perspective principally when it partitions into the aqueous rather than the solid phase. Dissolved concentrations, and the resulting mobility, of arsenic within soils and sediments are the combined result of biogeochemical processes linked to hydrologic factors. Processes favoring the partitioning of As into the aqueous phase, potentially leading to hazardous concentrations, vary extensively but can broadly be grouped into four categories: (1) ion displacement, (2) desorption (or limited sorption) at pH values > 8.5, (3) reduction of arsenate to arsenite, and (4) mineral dissolution, particularly reductive dissolution of Fe and Mn (hydr)oxides. Although various processes may liberate arsenic from solids, a transition from aerobic to anaerobic conditions, and commensurate arsenic and iron/manganese reduction, appears to be a dominant, but not exclusive, means by which high concentrations of

  8. Arsenic control during aquifer storage recovery cycle tests in the Floridan Aquifer.

    Science.gov (United States)

    Mirecki, June E; Bennett, Michael W; López-Baláez, Marie C

    2013-01-01

    Implementation of aquifer storage recovery (ASR) for water resource management in Florida is impeded by arsenic mobilization. Arsenic, released by pyrite oxidation during the recharge phase, sometimes results in groundwater concentrations that exceed the 10 µg/L criterion defined in the Safe Drinking Water Act. ASR was proposed as a major storage component for the Comprehensive Everglades Restoration Plan (CERP), in which excess surface water is stored during the wet season, and then distributed during the dry season for ecosystem restoration. To evaluate ASR system performance for CERP goals, three cycle tests were conducted, with extensive water-quality monitoring in the Upper Floridan Aquifer (UFA) at the Kissimmee River ASR (KRASR) pilot system. During each cycle test, redox evolution from sub-oxic to sulfate-reducing conditions occurs in the UFA storage zone, as indicated by decreasing Fe(2+) /H2 S mass ratios. Arsenic, released by pyrite oxidation during recharge, is sequestered during storage and recovery by co-precipitation with iron sulfide. Mineral saturation indices indicate that amorphous iron oxide (a sorption surface for arsenic) is stable only during oxic and sub-oxic conditions of the recharge phase, but iron sulfide (which co-precipitates arsenic) is stable during the sulfate-reducing conditions of the storage and recovery phases. Resultant arsenic concentrations in recovered water are below the 10 µg/L regulatory criterion during cycle tests 2 and 3. The arsenic sequestration process is appropriate for other ASR systems that recharge treated surface water into a sulfate-reducing aquifer. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.

  9. Arsenic mobilization in aquifers of the southwest Songnen basin, P.R. China: Evidences from chemical and isotopic characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Huaming [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083 (China); MOE Key Laboratory of Groundwater Circulation and Environment Evolution and School of Water Resources and Environment, China University of Geosciences, Beijing 100083 (China); Zhang, Di [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083 (China); MOE Key Laboratory of Groundwater Circulation and Environment Evolution and School of Water Resources and Environment, China University of Geosciences, Beijing 100083 (China); Wen, Dongguang [China Geological Survey, 24 Huangsi Dajie, Xicheng District, Beijing 100037 (China); Wu, Yang; Ni, Ping; Jiang, Yuxiao; Guo, Qi; Li, Fulan; Zheng, Hao; Zhou, Yinzhu [MOE Key Laboratory of Groundwater Circulation and Environment Evolution and School of Water Resources and Environment, China University of Geosciences, Beijing 100083 (China)

    2014-08-15

    Fe and As. - Highlights: • More than 86% groundwater had As concentration > 10 μg/L in study area. • High As groundwater was observed in both shallow and deep aquifers. • Distribution of groundwater As was controlled by hydrogeologic and redox conditions. • Microbial degradation of DOC was evidenced by {sup 13}C isotope of DOC and DIC. • Arsenic was released during microbially-mediated reduction of Fe oxides and As(V)

  10. Mobilization of arsenic and heavy metals from polluted soils by humic acid

    Science.gov (United States)

    Reyes, Arturo; Fuentes, Bárbara; Letelier, María Victoria; Cuevas, Jacqueline

    2017-04-01

    The existence of soils contaminated with harmful elements by mining activities is a global environmental concern. The northern part of Chile has several heavy metal contaminated sites due to former copper and gold artisanal mining activities. Therefore, a complete characterization of abandoned sites and the implementation of remediation technologies are of interest for regulators, the industry, and the population. The objective of the study was to test the use of humic acid as a washing treatment to reduce the heavy metal concentration of soil samples impacted by mine waste material. A stratified random sampling was conducted on the target site to determine the physical and chemical composition of mine waste and soil material. The sampling consisted of taking 37 samples at 0-20 cm depths in a 10,000 square-meter area. The samples were dried and sieved at 2 mm. The batch washing experiments were conducted in triplicate at pH 7.0. A 1:10 solid to liquid ratio and three humic acid dose (0, 50, and 100 mg/l) were used. After shaking (24 h, room temperature) and subsequently filtration (0.22 μm), the supernatants were analyzed for heavy metals, redox potential and pH. The heavy metals mobility was assessed using extraction methods before and after treatments. The soils had alkaline pH values, conductivity ranged between 8 and 35 mS/cm, with low organic matter. Total concentrations of Vanadium (V) (10.80 to 175.00 mg/kg), Lead (Pb) (7.31 to 90.10 mg/kg), Antimonium (Sb) (0.83 to 101.00 mg/kg), and Arsenic (As) (9.53 to 2691.00 mg/kg) exceeded several times the EPA`s recommended values for soils. At 100 mg/L HA the removal efficiencies for V, Pb, Sb, and As were 32, 68, 77, and 82% respectively. According to the extraction procedure V, Pb, Sb, and As species are mainly as oxidizable and residual fractions. According to the results, the target mine site is contaminated with harmful elements. It can be concluded that the use of humic acid is a good alternative as a

  11. Modelling and Control of a Mobile Robot

    DEFF Research Database (Denmark)

    Christensen, Georg Kronborg

    1998-01-01

    In order to control a mobile robot, kinematic odels as well as dynamic models are required. This parer describes these basic models for an experimental mobile robot under construction at the Department of Control and Engineering Design. A description of a set of trajectory control rules is given...

  12. Hydrogeological and biogeochemical constrains of arsenic mobilization in shallow aquifers from the Hetao basin, Inner Mongolia

    International Nuclear Information System (INIS)

    Guo Huaming; Zhang Bo; Li Yuan; Berner, Zsolt; Tang Xiaohui; Norra, Stefan; Stueben, Doris

    2011-01-01

    Little is known about the importance of drainage/irrigation channels and biogeochemical processes in arsenic distribution of shallow groundwaters from the Hetao basin. This investigation shows that although As concentrations are primarily dependent on reducing conditions, evaporation increases As concentration in the centre of palaeo-lake sedimentation. Near drainage channels, groundwater As concentrations are the lowest in suboxic-weakly reducing conditions. Results demonstrate that both drainage and irrigation channels produce oxygen-rich water that recharges shallow groundwaters and therefore immobilize As. Groundwater As concentration increases with a progressive decrease in redox potential along the flow path in an alluvial fan. A negative correlation between SO 4 2- concentrations and δ 34 S values indicates that bacterial reduction of SO 4 2- occurs in reducing aquifers. Due to high concentrations of Fe (>0.5 mg L -1 ), reductive dissolution of Fe oxides is believed to cause As release from aquifer sediments. Target aquifers for safe drinking water resources are available in alluvial fans and near irrigation channels. - Research highlights: → Low As groundwaters occur in alluvial fans. → We find low As groundwaters near irrigation and drainage channels. → Both hydrogeologic conditions and biogeochemical processes control As distribution. - Both hydrogeologic conditions and biogeochemical processes control As distribution of shallow groundwaters, which results in the occurrence of low As groundwater in alluvial fans and near irrigation channels and drainage channels.

  13. Differential Effects of Low-Molecular-Weight Organic Acids on the Mobilization of Soil-Borne Arsenic and Trace Metals.

    Science.gov (United States)

    Nworie, Obinna Elijah; Qin, Junhao; Lin, Chuxia

    2017-08-21

    A batch experiment was conducted to examine the effects of six low-molecular-weight organic acids on the mobilization of arsenic and trace metals from a range of contaminated soils. The results showed that the organic acids behaved differently when reacting with soil-borne As and trace metals. Oxalic acid and acetic acid had the strongest and weakest capacity to mobilize the investigated elements, respectively. The solubilisation of iron oxides by the organic acids appears to play a critical role in mobilizing other trace metals and As. Apart from acidification and complexation, reductive dissolution played a dominant role in the dissolution of iron oxides in the presence of oxalic acid, while acidification tended to be more important for dissolving iron oxides in the presence of other organic acids. The unique capacity of oxalic acid to solubilize iron oxides tended to affect the mobilization of other elements in different ways. For Cu, Mn, and Zn, acidification-driven mobilization was likely to be dominant while complexation might play a major role in Pb mobilization. The formation of soluble Fe and Pb oxalate complexes could effectively prevent arsenate or arsenite from combining with these metals to form solid phases of Fe or Pb arsenate or arsenite.

  14. Arsenic mobilization processes in the red river delta, Vietnam. Towards a better understanding of the patchy distribution of dissolved arsenic in alluvial deposits

    Energy Technology Data Exchange (ETDEWEB)

    Eiche, Elisabeth

    2009-07-01

    In this work the spatial variability of dissolved arsenic concentrations in aquifers was studied in a small village in the vicinity of Ha Noi, Vietnam. The main goal was to identify major geochemical, sedimentological and hydrochemical differences between high and low arsenic regions. Furthermore, the behaviour of arsenic and other elements during sequential extractions on a micrometer scale was characterized with micro synchrotron XRF analysis. Based on the results a conceptual model was developed which could explain the current situation in the village. Moreover, it could help to identify high arsenic areas throughout the world and, therefore, prevent the installation of drinking water wells in arsenic burdened regions. (orig.)

  15. Multiscale Characterization and Quantification of Arsenic Mobilization and Attenuation During Injection of Treated Coal Seam Gas Coproduced Water into Deep Aquifers

    Science.gov (United States)

    Rathi, Bhasker; Siade, Adam J.; Donn, Michael J.; Helm, Lauren; Morris, Ryan; Davis, James A.; Berg, Michael; Prommer, Henning

    2017-12-01

    Coal seam gas production involves generation and management of large amounts of co-produced water. One of the most suitable methods of management is injection into deep aquifers. Field injection trials may be used to support the predictions of anticipated hydrological and geochemical impacts of injection. The present work employs reactive transport modeling (RTM) for a comprehensive analysis of data collected from a trial where arsenic mobilization was observed. Arsenic sorption behavior was studied through laboratory experiments, accompanied by the development of a surface complexation model (SCM). A field-scale RTM that incorporated the laboratory-derived SCM was used to simulate the data collected during the field injection trial and then to predict the long-term fate of arsenic. We propose a new practical procedure which integrates laboratory and field-scale models using a Monte Carlo type uncertainty analysis and alleviates a significant proportion of the computational effort required for predictive uncertainty quantification. The results illustrate that both arsenic desorption under alkaline conditions and pyrite oxidation have likely contributed to the arsenic mobilization that was observed during the field trial. The predictive simulations show that arsenic concentrations would likely remain very low if the potential for pyrite oxidation is minimized through complete deoxygenation of the injectant. The proposed modeling and predictive uncertainty quantification method can be implemented for a wide range of groundwater studies that investigate the risks of metal(loid) or radionuclide contamination.

  16. Relationship between pyrite Stability and arsenic mobility during aquifer storage and recovery in southwest central Florida.

    Science.gov (United States)

    Jones, Gregg W; Pichler, Thomas

    2007-02-01

    Elevated arsenic concentrations are common in water recovered from aquifer storage and recovery (ASR) systems in west-central Florida that store surface water. Investigations of the Suwannee Limestone of the Upper Floridan aquifer, the storage zone for ASR systems, have shown that arsenic is highest in pyrite in zones of high moldic porosity. Geochemical modeling was employed to examine pyrite stability in limestone during simulated injections of surface water into wells open only to the Suwannee Limestone with known mineralogy and water chemistry. The goal was to determine if aquifer redox conditions could be altered to the degree of pyrite instability. Increasing amounts of injection water were added to native storage-zone water, and resulting reaction paths were plotted on pyrite stability diagrams. Native storage-zone water plotted within the pyrite stability field, indicating that conditions were sufficiently reducing to allow for pyrite stability. Thus, arsenic is immobilized in pyrite, and its groundwater concentration should be low. This was corroborated by analysis of water samples, none of which had arsenic concentrations above 0.036 microg/L. During simulation, however, as injection/native storage-zone water ratios increased, conditions became less reducing and pyrite became unstable. The result would be release of arsenic from limestone into storage-zone water.

  17. Heterogeneous redox conditions, arsenic mobility, and groundwater flow in a fractured-rock aquifer near a waste repository site in New Hampshire, USA

    Science.gov (United States)

    Anthropogenic sources of carbon from landfill or waste leachate can promote reductive dissolution of in situ arsenic (As) and enhance the mobility of As in groundwater. Groundwater from residential-supply wells in a fractured crystalline-rock aquifer adjacent to a Superfund site ...

  18. Arsenic Removal from Drinking Water by Adsorptive Media - U.S. EPA Demonstration Project at Hot Springs Mobile Home Park in Willard, Utah - Final Performance Evaluation Report

    Science.gov (United States)

    This report documents activities performed for and results obtained from the arsenic removal treatment technology demonstration project at the Hot Springs Mobile Home Park (HSMHP) in Willard, UT. The objectives of the project were to evaluate the effectiveness of Adsorbsia™ GTO™...

  19. ARSENIC REMOVAL FROM DRINKING WATER BY ADSORPTIVE MEDIA U.S. EPA DEMONSTRATION PROJECT AT SPRING BROOK MOBILE HOME PARK IN WALES, ME SIX-MONTH EVALUATION REPORT

    Science.gov (United States)

    This report documents the activities performed during and the results obtained from the first six months of the arsenic removal treatment technology demonstration project at the Spring Brook Mobile Home Park in Wales, ME. The objectives of the project are to evaluate the effectiv...

  20. ARSENIC REMOVAL FROM DRINKING WATER BY ADSORPTIVE MEDIA U.S. EPA DEMONSTRATION PROJECT AT CHATEAU ESTATES MOBILE HOME PARK IN SPRINGFIELD, OH. SIX-MONTH EVALUATION REPORT

    Science.gov (United States)

    This report documents the activities performed for and the results obtained from the first six months of the arsenic removal treatment technology demonstration project at the Chateau Estates Mobile Home Park at Springfield, OH. The objectives of the project are to evaluate the ef...

  1. ARSENIC REMOVAL FROM DRINKING WATER BY IRON REMOVAL USEPA DEMONSTRATION PROJECT AT BIG SAUK LAKE MOBILE HOME PARK IN SAUK CENTRE, MN. SIX MONTH EVALUATION REPORT

    Science.gov (United States)

    This report documents the activities performed and the results obtained from the first six months of the arsenic removal treatment technology demonstration project at the Big Sauk Lake Mobile Home Park (BSLMHP) in Sauk Centre, MN. The objectives of the project are to evaluate the...

  2. Stratigraphic and geochemical controls on naturally occurring arsenic in groundwater, eastern Wisconsin, USA

    Science.gov (United States)

    Schreiber, M. E.; Simo, J. A.; Freiberg, P. G.

    High arsenic concentrations (up to 12,000μg/L) have been measured in groundwater from a confined sandstone aquifer in eastern Wisconsin. The main arsenic source is a sulfide-bearing secondary cement horizon (SCH) that has variable thickness, morphology, and arsenic concentrations. Arsenic occurs in pyrite and marcasite as well as in iron oxyhydroxides but not as a separate arsenopyrite phase. Nearly identical sulfur isotopic signatures in pyrite and dissolved sulfate and the correlation between dissolved sulfate, iron, and arsenic concentrations suggest that sulfide oxidation is the dominant process controlling arsenic release to groundwater. However, arsenic-bearing oxyhydroxides can potentially provide another arsenic source if reducing conditions develop or if they are transported as colloids in the aquifer. Analysis of well data indicates that the intersection of the SCH with static water levels measured in residential wells is strongly correlated with high concentrations of arsenic in groundwater. Field and laboratory data suggest that the most severe arsenic contamination is caused by localized borehole interactions of air, water, and sulfides. Although arsenic contamination is caused by oxidation of naturally occurring sulfides, it is influenced by water-level fluctuations caused by municipal well pumping or climate changes, which can shift geographic areas in which contamination occurs. Résumé De fortes concentrations en arsenic, jusqu'à 12000μg/L, ont été mesurées dans l'eau souterraine d'un aquifère gréseux captif, dans l'est du Wisconsin. La principale source d'arsenic est un horizon à cimentation secondaire (SCH) comportant des sulfures, dont l'épaisseur, la morphologie et les concentrations en arsenic sont variables. L'arsenic est présent dans la pyrite et dans la marcassite, de même que dans des oxy-hydroxydes de fer, mais non pas dans une phase séparée d'arsénopyrite. Les signatures isotopiques du soufre presque identiques dans la

  3. AN INVESTIGATION OF ARSENIC MOBILITY FROM IRON OXIDE SOLIDS PRODUCED DURING DRINKING WATER TREATMENT

    Science.gov (United States)

    The Arsenic Rule under the Safe Drinking Water Act will require certain drinking water suppliers to add to or modify their existing treatment in order to comply with the regulations. One of the treatment options is iron co-precipitation. This treatment is attractive because ars...

  4. Arsenic in groundwater of the Red River floodplain, Vietnam: Controlling geochemical processes and reactive transport modeling

    DEFF Research Database (Denmark)

    Postma, Diederik Jan; Larsen, Flemming; Hue, N.T.M.

    2007-01-01

    The mobilization of arsenic (As) to the groundwater was studied in a shallow Holocene aquifer on the Red River flood plain near Hanoi, Vietnam. The groundwater chemistry was investigated in a transect of 100 piezometers. Results show an anoxic aquifer featuring organic carbon decomposition......(III) but some As(V) is always found. Arsenic correlates well with NH4, relating its release to organic matter decomposition and the source of As appears to be the Fe-oxides being reduced. Part of the produced Fe(II) is apparently reprecipitated as siderite containing less As. Results from sediment extraction...... chemistry over depth is homogeneous and a reactive transport model was constructed to quantify the geochemical processes along the vertical groundwater flow component. A redox zonation model was constructed using the partial equilibrium approach with organic carbon degradation in the sediment as the only...

  5. Interaction control of a redundant mobile manipulator

    International Nuclear Information System (INIS)

    Chung, J.H.; Velinsky, S.A.; Hess, R.A.

    1998-01-01

    This paper discusses the modeling and control of a spatial mobile manipulator that consists of a robotic manipulator mounted on a wheeled mobile platform. The Lagrange-d'Alembert formulation is used to obtain a concise description of the dynamics of the system, which is subject to nonholonomic constraints. The complexity of the model is increased by introducing kinematic redundancy, which is created when a multilinked manipulator is used. The kinematic redundancy is resolved by decomposing the mobile manipulator into two subsystems: the mobile platform and the manipulator. The redundancy resolution scheme employs a nonlinear interaction-control algorithm, which is developed and applied to coordinate the two subsystems' controllers. The subsystem controllers are independently designed, based on each subsystem's dynamic characteristics. Simulation results show the promise of the developed algorithm

  6. Process-based reactive transport model to quantify arsenic mobility during aquifer storage and recovery of potable water.

    Science.gov (United States)

    Wallis, Ilka; Prommer, Henning; Pichler, Thomas; Post, Vincent; Norton, Stuart B; Annable, Michael D; Simmons, Craig T

    2011-08-15

    Aquifer storage and recovery (ASR) is an aquifer recharge technique in which water is injected in an aquifer during periods of surplus and withdrawn from the same well during periods of deficit. It is a critical component of the long-term water supply plan in various regions, including Florida, USA. Here, the viability of ASR as a safe and cost-effective water resource is currently being tested at a number of sites due to elevated arsenic concentrations detected during groundwater recovery. In this study, we developed a process-based reactive transport model of the coupled physical and geochemical mechanisms controlling the fate of arsenic during ASR. We analyzed multicycle hydrochemical data from a well-documented affected southwest Floridan site and evaluated a conceptual/numerical model in which (i) arsenic is initially released during pyrite oxidation triggered by the injection of oxygenated water (ii) then largely complexes to neo-formed hydrous ferric oxides before (iii) being remobilized during recovery as a result of both dissolution of hydrous ferric oxides and displacement from sorption sites by competing anions.

  7. Controls on the Mobility of Antimony in Mine Waste from Three Deposit Types

    Science.gov (United States)

    Jamieson, H.; Radková, A. B.; Fawcett, S.

    2017-12-01

    Antimony can be considered both a critical metal and an environmental hazard, with a toxicity similar to arsenic. It is concentrated in stibnite deposits, but also present in polymetallic and precious metal ores, frequently accompanied by arsenic. We have studied the mineralogical controls on the mobility of antimony in three types of mine waste: stibnite tailings from an antimony mine, tetrahedrite-bearing waste rock from copper mining, and gold mine tailings and ore roaster waste. Our results demonstrate that the tendency of antimony to leach into the aqueous environment or remain sequestered in solid phases depends on the primary host minerals and conditions governing the precipitation of secondary antimony-hosting phases. In tailings at the Beaver Brook antimony mine in Newfoundland, Canada, stibnite oxidizes rapidly, and secondary minerals such as the relatively insoluble Sb-Fe tripuhyite-like phase and Sb-bearing goethite. However, under dry conditions, the most important secondary Sb host is the Mg-Sb hydroxide brandholzite, but this easily soluble mineral disappears when it rains. Antimony that was originally hosted in tetrahedrite, a complex multi-element sulfosalt, in the historic waste rock piles at Špania Dolina-Piesky, Slovakia, is not as mobile as Cu and As during weathering but reprecipiates to a mixture of tripuhyite and romeite. Finally, the original antimony-hosting minerals, both stibnite and sulphosalts, in the gold ore at Giant Mine, Yellowknife, Canada were completely destroyed during ore roasting. In tailings-contaminated sediments, antimony persists in roaster-generated iron oxide phases, except under reducing conditions where some of the antimony forms a Sb-S phase. The combined presence of antimony and arsenic in mine waste complicates risk assessment but in general, our findings suggest that antimony is less mobile than arsenic in the environment.

  8. Assisted phytoremediation of a multi-contaminated soil: Investigation on arsenic and lead combined mobilization and removal.

    Science.gov (United States)

    Barbafieri, Meri; Pedron, Francesca; Petruzzelli, Gianniantonio; Rosellini, Irene; Franchi, Elisabetta; Bagatin, Roberto; Vocciante, Marco

    2017-12-01

    The removal of contaminants from an earthy matrix by phytoremediation requires the selection of appropriate plant species and a suitable strategy to be effective. In order to set up an assisted phytoremediation intervention related to a disused industrial site affected by an arsenic and lead complex contamination, an extensive experimental investigation on micro and mesocosm scale has been conducted. Particular attention was given to the choice of plant species: using crop plants (Lupinus albus, Helianthus annuus and Brassica juncea) a series of parallel test campaigns have been realized to investigate different scenarios for the reclamation. With regard to the arsenic contamination, which is certainly the most worrying, the possibility of employing a hyper-accumulator species (Pteris vittata) has also been investigated, highlighting advantages and difficulties associated with such an approach. The application of various mobilizing agents in different concentrations was tested, in order to maximize the extraction efficiency of plants in respect of both contaminants, showing the necessity of a chemically assisted approach to promote their uptake and translocation in the shoots. Phosphate addition appears to produce the desired results, positively affecting As phyto-extraction for both hyper-accumulator and crop plants, while minimizing its toxic effects at the investigated concentrations. With regard to Pb, although tests with EDDS have been encouraging, EDTA should be preferred at present due to lower uncertainties about its effectiveness. The performed tests also improved the addition of mobilizing agents, allowing the simultaneous removal of the two metals despite their great diversity (which in general discourages such approach), with significant saving of time and an obvious improvement of the overall process. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Vertical variability of arsenic concentrations under the control of iron-sulfur-arsenic interactions in reducing aquifer systems

    Science.gov (United States)

    Pi, Kunfu; Wang, Yanxin; Postma, Dieke; Ma, Teng; Su, Chunli; Xie, Xianjun

    2018-06-01

    High spatial variability of arsenic (As) concentration in geogenic As-contaminated groundwater has been commonly observed worldwide, but the underlying reasons remain not well understood. Selecting a sulfate-containing, As-affected aquifer at the Datong Basin, northern China as the study area and combining hydrogeochemical investigation and sediment extraction with reactive transport modeling, this work elucidated the roles of Fe-S-As interactions in regulating the vertical variation of As concentration in the groundwater. Dissolved As concentration varied between 0.05 and 18 μmol/L, but generally increased in the depth of 20-25 m and then decreased in 25-30 m. The high-As groundwater contained low Fe(II) (groundwater devoid of sulfate reduction. The reductive dissolution of As-bearing Fe(III) oxides coupled to the degradation of organic matter with an estimated maximum rate of 0.22 mmol C/L/yr, mainly accounted for the depth-dependent increase of As concentration in the upper part of the shallow aquifer (groundwater but also probably co-precipitated As to prompt As decrease in the depth of 25-30 m. Arsenite adsorbed on remaining Fe(III) oxides and newly-formed Fe(II) sulfides is another important pool of As in the aquifer, which varies in response to the extents of Fe(III)-oxide and sulfate reduction and consequently alters As distribution coefficient between the solid and the aqueous phases. This study highlights the importance of coupled geochemical cycling of Fe, S and As for As mobilization and reveals how it regulates As partitioning between groundwater and sediments.

  10. Arsenic pollution sources.

    Science.gov (United States)

    Garelick, Hemda; Jones, Huw; Dybowska, Agnieszka; Valsami-Jones, Eugenia

    2008-01-01

    many (bio)geochemical processes: oxidation of arsenic-bearing sulfides, desorption from oxides and hydroxides, reductive dissolution, evaporative concentration, leaching from sulfides by carbonate, and microbial mobilization. Arsenic enrichment also takes place in geothermally active areas; surface waters are more susceptible than groundwater to contamination in the vicinity of such geothermal systems, and evidence suggests that increased use of geothermal power may elevate risks of arsenic exposure in affected areas. Past and current mining activities continue to provide sources of environmental contamination by arsenic. Because gold- and arsenic-bearing minerals coexist, there is a hazard of mobilizing arsenic during gold mining activities. The Ashanti region of central Ghana currently faces this as a real risk. Historical arsenic contamination exists in Cornwall, UK; an example of a recent arsenic pollution event is that of Ron Phibun town in southern Thailand, where arsenic-related human health effects have been reported. Other important sources of arsenic exposure include coal burning in Slovakia, Turkey, and the Guizhou Province of China; use of arsenic as pesticides in Australia, New Zealand, and the US; and consumption of contaminated foodstuffs (China) and exposure to wood preserving arsenicals (Europe and North America).

  11. Individual differences in arsenic metabolism and lung cancer in a case-control study in Cordoba, Argentina

    International Nuclear Information System (INIS)

    Steinmaus, Craig; Yuan Yan; Kalman, Dave; Rey, Omar A.; Skibola, Christine F.; Dauphine, Dave; Basu, Anamika; Porter, Kristin E.; Hubbard, Alan; Bates, Michael N.; Smith, Martyn T.; Smith, Allan H.

    2010-01-01

    In humans, ingested inorganic arsenic is metabolized to monomethylarsenic (MMA) then to dimethylarsenic (DMA), although in most people this process is not complete. Previous studies have identified associations between the proportion of urinary MMA (%MMA) and increased risks of several arsenic-related diseases, although none of these reported on lung cancer. In this study, urinary arsenic metabolites were assessed in 45 lung cancer cases and 75 controls from arsenic-exposed areas in Cordoba, Argentina. Folate has also been linked to arsenic-disease susceptibility, thus an exploratory assessment of associations between single nucleotide polymorphisms in folate metabolizing genes, arsenic methylation, and lung cancer was also conducted. In analyses limited to subjects with metabolite concentrations above detection limits, the mean %MMA was higher in cases than in controls (17.5% versus 14.3%, p = 0.01). The lung cancer odds ratio for subjects with %MMA in the upper tertile compared to those in the lowest tertile was 3.09 (95% CI, 1.08-8.81). Although the study size was too small for a definitive conclusion, there was an indication that lung cancer risks might be highest in those with a high %MMA who also carried cystathionine β-synthase (CBS) rs234709 and rs4920037 variant alleles. This study is the first to report an association between individual differences in arsenic metabolism and lung cancer, a leading cause of arsenic-related mortality. These results add to the increasing body of evidence that variation in arsenic metabolism plays an important role in arsenic-disease susceptibility.

  12. Corrigendum to "Arsenic mineralogy and mobility in the arsenic-rich historical mine waste dump" [Sci. Total Environ. 536 (2015) 713-728

    Czech Academy of Sciences Publication Activity Database

    Filippi, Michal; Drahota, P.; Machovič, V.; Böhmová, Vlasta; Mihaljevič, M.

    2016-01-01

    Roč. 541, January 15 (2016), s. 1639 ISSN 0048-9697 Institutional support: RVO:67985831 Keywords : corrigendum * erratum * arsenic mineralogy Subject RIV: DB - Geology ; Mineralogy Impact factor: 4.900, year: 2016

  13. Control synchronization of differential mobile robots

    NARCIS (Netherlands)

    Nijmeijer, H.; Rodriguez Angeles, A.; Allgoewer, F.

    2004-01-01

    In this paper a synchronization controller for differential mobile robots is proposed. The synchronization goal is to control the angular position of each wheel to a desired trajectory and at the same time the differential (or synchronization) error between the angular positions of the two wheels.

  14. [Transformation and mobility of arsenic in the rhizosphere and non-rhizosphere soils at different growth stages of rice].

    Science.gov (United States)

    Yang, Wen-Tao; Wang, Ying-Jie; Zhou, Hang; Yi, Kai-Xin; Zeng, Min; Peng, Pei-Qin; Liao, Bo-Han

    2015-02-01

    Speciation and bioavailability of arsenic in the rhizosphere and non-rhizosphere soils at different growth stages (tillering stage, jointing stage, booting stage, filling stage and maturing stage) of rice (Oryza sativa L.) were studied using toxicity characteristic leaching procedure (TCLP) and arsenic speciation analysis. Pot experiments were conducted and the soil samples were taken from a certain paddy soil in Hunan Province contaminated by mining industry. The results showed that: (1) With the extension of rice growth period, pH values and TCLP extractable arsenic levels in the rhizosphere and non-rhizosphere soils increased gradually. Soil pH and TCLP extractable arsenic levels in non-rhizosphere soils were higher than those in the rhizosphere soils at the same growth stage. (2) At the different growth stages of rice, contents of exchangeable arsenic (AE-As) in rhizosphere and non-rhizosphere soils were lower than those before the rice planting, and increased gradually with the extension of the rice growing period. Contents of Al-bound arsenic (Al-As), Fe-bound arsenic (Fe-As) and Ca-bound arsenic (Ca-As) increased gradually after rice planting, but not significantly. Residual arsenic (O-As) and total arsenic (T-As) decreased gradually after rice planting, by 37.30% and 14.69% in the rhizosphere soils and by 31.38% and 8.67% in the non-rhizosphere soils, respectively. (3) At the different growth stages of rice, contents of various forms of arsenic in the soils were in the following order: residual arsenic (O-As) > Fe-bound arsenic ( Fe-As) > Al-bound arsenic (Al-As) > Ca-bound arsenic (Ca-As) > exchangeable arsenic (AE-As). In the pH range of 5.0- 5.8, significant positive linear correlations were found between most forms of arsenic or TCLP extractable arsenic levels and pH values, while the Ca-bound arsenic was poorly correlated with pH values in the rhizosphere soils.

  15. Robot motion control in mobile environment

    Institute of Scientific and Technical Information of China (English)

    Iliya V Miroshnik; HUANG Xian-lin(黄显林); HE Jie(贺杰)

    2003-01-01

    With the problem of robot motion control in dynamic environment represented by mobile obstacles,working pieces and external mechanisms considered, a relevant control actions design procedure has been pro-posed to provide coordination of robot motions with respect to the moving external objects so that an extension ofrobot spatial motion techniques and active robotic strategies based on approaches of nonlinear control theory canbe achieved.

  16. Arsenic mobilization in an alluvial aquifer of the Terai region, Nepal

    Directory of Open Access Journals (Sweden)

    Jasmine Diwakar

    2015-09-01

    New Hydrological Insights for the Region: The aquifer is characterized by Ca-HCO3 type water and is multi-contaminated, with the WHO guideline values exceeded for As, Mn and F in 80%, 70% and 40% of cases respectively. The middle portion of the floodplain was heavily contaminated with As, predominantly as As(III. The river water displayed some evidence of reductive processes in the hyporheic zone contributing As, Fe and Mn to baseflow and also had elevated fluoride. The generally sub-oxic conditions, dominance of As(III and Fe2+ species and positive correlation between As and both NH3 and UV-absorbance at 254 nm suggests that oxidation of organic matter coupled with microbial mediated reductive processes are important for mobilizing As in the aquifer. The apparent decoupling between As(III(aq and Fe2+(aq may be explained by precipitation of siderite, but further work is required to resolve this unambiguously. Along with reductive processes, other geochemical mechanisms including silicate weathering and precipitation/dissolution of carbonate minerals, control the solute and major ion composition of groundwater.

  17. Mobility of arsenic, cadmium and zinc in a multi-element contaminated soil profile assessed by in-situ soil pore water sampling, column leaching and sequential extraction

    International Nuclear Information System (INIS)

    Beesley, Luke; Moreno-Jimenez, Eduardo; Clemente, Rafael; Lepp, Nicholas; Dickinson, Nicholas

    2010-01-01

    Three methods for predicting element mobility in soils have been applied to an iron-rich soil, contaminated with arsenic, cadmium and zinc. Soils were collected from 0 to 30 cm, 30 to 70 cm and 70 to 100 cm depths in the field and soil pore water was collected at different depths from an adjacent 100 cm deep trench. Sequential extraction and a column leaching test in the laboratory were compared to element concentrations in pore water sampled directly from the field. Arsenic showed low extractability, low leachability and occurred at low concentrations in pore water samples. Cadmium and zinc were more labile and present in higher concentrations in pore water, increasing with soil depth. Pore water sampling gave the best indication of short term element mobility when field conditions were taken into account, but further extraction and leaching procedures produced a fuller picture of element dynamics, revealing highly labile Cd deep in the soil profile. - Mobility of arsenic, cadmium and zinc in a polluted soil can be realistically interpreted by in-situ soil pore water sampling.

  18. Arsenic Mobility and Availability in Sediments by Application of BCR Sequential Extractions Method; Movilidad y Disponibilidad de Arsenico en Sedimentos Mediante la Aplicacion del Metodo de Extracciones Secuenciales BCR

    Energy Technology Data Exchange (ETDEWEB)

    Larios, R.; Fernandez, R.; Rucandio, M. I.

    2011-05-13

    Arsenic is a metalloid found in nature, both naturally and due to anthropogenic activities. Among them, mining works are an important source of arsenic release to the environment. Asturias is a region where important mercury mines were exploited, and in them arsenic occurs in para genesis with mercury minerals. The toxicity and mobility of this element depends on the chemical species it is found. Fractionation studies are required to analyze the mobility of this metalloid in soils and sediments. Among them, the proposed by the Bureau Community of Reference (BCR) is one of the most employed. This method attempts to divide up, by operationally defined stages, the amount of this element associated with carbonates (fraction 1), iron and manganese oxy hydroxides (fraction 2), organic matter and sulphides (fraction 3), and finally as the amount associated residual fraction to primary and secondary minerals, that is, from the most labile fractions to the most refractory ones. Fractionation of arsenic in sediments from two mines in Asturias were studied, La Soterrana and Los Rueldos. Sediments from La Soterrana showed high levels of arsenic in the non-residual phases, indicating that the majority of arsenic has an anthropogenic origin. By contrast, in sediments from Los Rueldos most of the arsenic is concentrated in the residual phase, indicating that this element remains bound to very refractory primary minerals, as is also demonstrated by the strong correlation of arsenic fractionation and the fractionation of elements present in refractory minerals, such as iron, aluminum and titanium. (Author) 51 refs.

  19. Model predictive Controller for Mobile Robot

    OpenAIRE

    Alireza Rezaee

    2017-01-01

    This paper proposes a Model Predictive Controller (MPC) for control of a P2AT mobile robot. MPC refers to a group of controllers that employ a distinctly identical model of process to predict its future behavior over an extended prediction horizon. The design of a MPC is formulated as an optimal control problem. Then this problem is considered as linear quadratic equation (LQR) and is solved by making use of Ricatti equation. To show the effectiveness of the proposed method this controller is...

  20. Controller Design Of Unicycle Mobile Robot

    Directory of Open Access Journals (Sweden)

    Mohd Zamzuri Abd Rashid

    2012-10-01

    Full Text Available ABSTRACT: The ability of unicycle mobile robot to stand and move around using one wheel has attracted a lot of researchers to conduct studies about the system, particularly in the design of the system mechanisms and the control strategies. This paper reports the investigation done on the design of the controller of the unicycle mobile robot system to maintain its stability in both longitudinal and lateral directions. The controller proposed is a Linear Quadratic Controller (LQR type which is based on the linearized model of the system. A thorough simulation studies have been carried out to find out the performance of the LQR controller. The best controller gain, K acquired through the simulation is selected to be implemented and tested in the experimental hardware. Finally, the results obtained from the experimental study are compared to the simulation results to study the controller efficacy. The analysis reveals that the proposed controller design is able to stabilize the unicycle mobile robot.ABSTRAK: Kemampuan robot satu roda untuk berdiri dan bergerak di sekitar telah menarik minat ramai penyelidik untuk mengkaji sistem robot terutamanya didalam bidang rangka mekanikal dan strategi kawalan robot. Kertas kajian ini melaporkan hasil penyelidikan ke atas strategi kawalan robot bagi memastikan sistem robot satu roda dapat distabilkan dari arah sisi dan hadapan. Strategi kawalan yang dicadang, menggunakan teknik kawalan kuadratik sejajar (Linear Quadratic Control yang berdasarkan model robot yang telah dipermudahkan. Kajian simulasi secara terperinci telah dijalankan bagi mengkaji prestasi strategi kawalan yang dicadangkan. Dari kajian simulasi sistem robot, pemilihan faktor konstan, K yang sesuai di dalam strategi kawalan telah dibuat, agar dapat dilaksanakan ke atas sistem robot yang dibangunkan. Keputusan dari kajian simulasi dan tindak balas oleh sistem robot yang dibangunkan akhirnya dibandingkan bagi melihat kesesuaian faktor kostan, K

  1. Controls on the distribution of arsenic in lake sediments impacted by 65 years of gold ore processing in subarctic Canada: the role of organic matter

    Science.gov (United States)

    Galloway, Jennifer; Palmer, Michael; Swindles, Graeme T.; Sanei, Hamed; Jamieson, Heather E.; Parsons, Michael; Macumber, Andrew L.; Patterson, Tim; Falck, Hendrik

    2017-04-01

    Gold mines in the Yellowknife region of the Northwest Territories, Canada, operated from 1938 to 2003 and released approximately 20,000 tonnes of arsenic trioxide to the environment through stack emissions. This release resulted in highly elevated arsenic concentrations in lake surface waters and sediments relative to Canadian drinking water standards and guidelines for the protection of aquatic life. High northern latitudes are experiencing substantial impacts, including changes in bio-physico-chemical processes, due to climate change. Determining the affect of warming climate on contamination is complicated by the fact that little is known of climate change controls on As mobility and bioavailability. Further, while the role of dissolved organic matter in As cycling is relatively well characterized in soils and wetland sediments, few studies have investigated the role of solid organic matter in lacustrine systems. We use a meta-analytical approach to better understand controls on sedimentary arsenic distribution in lakes within a 50 km2 area of historic mineral processing activities. Arsenic concentrations in near surface sediments of the 100 lakes studied range from 5 mg/kg to over 10,000 mg/kg (median 81 mg/kg). Distance from the historical Giant Mine roaster stack and the amount of labile organic matter (S1 carbon as determined by Rock Eval pyrolysis) in lake sediments are the variables most strongly correlated with sedimentary As concentrations (Spearman's rank correlation As:distance from historic roaster rs=-0.57, pcoating of pre-existing solid-phase As-mineral complexes, direct As-organic matter interactions, and promotion of microbial-mediated reduction and precipitation of As-bearing minerals.

  2. Microbes Enhance Mobility of Arsenic in Pleistocene Aquifer Sand from Bangladesh

    Science.gov (United States)

    Dhar, Ratan K.; Zheng, Yan; Saltikov, Chad W.; Radloff, Kathleen A.; Mailloux, Brian; Ahmed, Kazi. M.; van Geen, Alexander

    2018-01-01

    Dissimilatory metal-reducing bacteria can mobilize As, but few studies have studied such processes in deeper orange-colored Pleistocene sands containing 1–2 mg kg−1 As that are associated with low-As groundwater in Bangladesh. To address this gap, anaerobic incubations were conducted in replicate over 90 days using natural orange sands initially containing 0.14 mg kg−1 of 1 M phosphate-extractable As (24 hr), >99% as As(V), and 0.8 g kg−1 of 1.2 M HCl-leachable Fe (1 hr at 80°C), 95% as Fe(III). The sediment was resuspended in artificial groundwater, with or without lactate as a labile carbon source, and inoculated with metal-reducing Shewanella sp. ANA-3. Within 23 days, dissolved As concentrations increased to 17 μg L−1 with lactate, 97% as As(III), and 2 μg L−1 without lactate. Phosphate-extractable As concentrations increased 4-fold to 0.6 mg kg−1 in the same incubations, even without the addition of lactate. Dissolved As levels in controls without Shewanella, both with and without lactate, instead remained <1 μg L−1. These observations indicate that metal-reducers such as Shewanella can trigger As release to groundwater by converting sedimentary As to a more mobilizable form without the addition of high levels of labile carbon. Such interactions need to be better understood to determine the vulnerability of low-As aquifers from which drinking water is increasingly drawn in Bangladesh. PMID:21405115

  3. Contrasting distributions of groundwater arsenic and uranium in the western Hetao basin, Inner Mongolia: Implication for origins and fate controls

    International Nuclear Information System (INIS)

    Guo, Huaming; Jia, Yongfeng; Wanty, Richard B.; Jiang, Yuxiao; Zhao, Weiguang; Xiu, Wei; Shen, Jiaxing; Li, Yuan; Cao, Yongsheng; Wu, Yang; Zhang, Di; Wei, Chao; Zhang, Yilong; Cao, Wengeng

    2016-01-01

    Although As concentrations have been investigated in shallow groundwater from the Hetao basin, China, less is known about U and As distributions in deep groundwater, which would help to better understand their origins and fate controls. Two hundred and ninety-nine groundwater samples, 122 sediment samples, and 14 rock samples were taken from the northwest portion of the Hetao basin, and analyzed for geochemical parameters. Results showed contrasting distributions of groundwater U and As, with high U and low As concentrations in the alluvial fans along the basin margins, and low U and high As concentrations downgradient in the flat plain. The probable sources of both As and U in groundwater were ultimately traced to the bedrocks in the local mountains (the Langshan Mountains). Chemical weathering of U-bearing rocks (schist, phyllite, and carbonate veins) released and mobilized U as UO_2(CO_3)_2"2"− and UO_2(CO_3)_3"4"− species in the alluvial fans under oxic conditions and suboxic conditions where reductions of Mn and NO_3"− were favorable (OSO), resulting in high groundwater U concentrations. Conversely, the recent weathering of As-bearing rocks (schist, phyllite, and sulfides) led to the formation of As-bearing Fe(III) (hydr)oxides in sediments, resulting in low groundwater As concentrations. Arsenic mobilization and U immobilization occurred in suboxic conditions where reduction of Fe(III) oxides was favorable and reducing conditions (SOR). Reduction of As-bearing Fe(III) (hydr)oxides, which were formed during palaeo-weathering and transported and deposited as Quaternary aquifer sediments, was believed to release As into groundwater. Reduction of U(VI) to U(IV) would lead to the formation of uraninite, and therefore remove U from groundwater. We conclude that the contrasting distributions of groundwater As and U present a challenge to ensuring safe drinking water in analogous areas, especially with high background values of U and As. - Highlights:

  4. Contrasting distributions of groundwater arsenic and uranium in the western Hetao basin, Inner Mongolia: Implication for origins and fate controls

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Huaming, E-mail: hmguo@cugb.edu.cn [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083 (China); School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083 (China); Jia, Yongfeng [School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083 (China); Wanty, Richard B. [U.S. Geological Survey, MS 964d Denver Federal Center, Denver, CO 80225 (United States); Jiang, Yuxiao; Zhao, Weiguang [School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083 (China); Xiu, Wei [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083 (China); School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083 (China); Shen, Jiaxing [School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083 (China); Li, Yuan [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083 (China); School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083 (China); Cao, Yongsheng [School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083 (China); Wu, Yang [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083 (China); Zhang, Di [School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083 (China); Wei, Chao [School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083 (China); The National Institute of Metrology, Beijing 100013 (China); Zhang, Yilong; Cao, Wengeng [Institute of Hydrogeology and Environmental Geology, China Academy of Geological Sciences, Shijiazhuang, Hebei, 050061 (China); and others

    2016-01-15

    Although As concentrations have been investigated in shallow groundwater from the Hetao basin, China, less is known about U and As distributions in deep groundwater, which would help to better understand their origins and fate controls. Two hundred and ninety-nine groundwater samples, 122 sediment samples, and 14 rock samples were taken from the northwest portion of the Hetao basin, and analyzed for geochemical parameters. Results showed contrasting distributions of groundwater U and As, with high U and low As concentrations in the alluvial fans along the basin margins, and low U and high As concentrations downgradient in the flat plain. The probable sources of both As and U in groundwater were ultimately traced to the bedrocks in the local mountains (the Langshan Mountains). Chemical weathering of U-bearing rocks (schist, phyllite, and carbonate veins) released and mobilized U as UO{sub 2}(CO{sub 3}){sub 2}{sup 2−} and UO{sub 2}(CO{sub 3}){sub 3}{sup 4−} species in the alluvial fans under oxic conditions and suboxic conditions where reductions of Mn and NO{sub 3}{sup −} were favorable (OSO), resulting in high groundwater U concentrations. Conversely, the recent weathering of As-bearing rocks (schist, phyllite, and sulfides) led to the formation of As-bearing Fe(III) (hydr)oxides in sediments, resulting in low groundwater As concentrations. Arsenic mobilization and U immobilization occurred in suboxic conditions where reduction of Fe(III) oxides was favorable and reducing conditions (SOR). Reduction of As-bearing Fe(III) (hydr)oxides, which were formed during palaeo-weathering and transported and deposited as Quaternary aquifer sediments, was believed to release As into groundwater. Reduction of U(VI) to U(IV) would lead to the formation of uraninite, and therefore remove U from groundwater. We conclude that the contrasting distributions of groundwater As and U present a challenge to ensuring safe drinking water in analogous areas, especially with high

  5. Role of competing ions in the mobilization of arsenic in groundwater of Bengal Basin: insight from surface complexation modeling.

    Science.gov (United States)

    Biswas, Ashis; Gustafsson, Jon Petter; Neidhardt, Harald; Halder, Dipti; Kundu, Amit K; Chatterjee, Debashis; Berner, Zsolt; Bhattacharya, Prosun

    2014-05-15

    This study assesses the role of competing ions in the mobilization of arsenic (As) by surface complexation modeling of the temporal variability of As in groundwater. The potential use of two different surface complexation models (SCMs), developed for ferrihydrite and goethite, has been explored to account for the temporal variation of As(III) and As(V) concentration, monitored in shallow groundwater of Bengal Basin over a period of 20 months. The SCM for ferrihydrite appears as the better predictor of the observed variation in both As(III) and As(V) concentrations in the study sites. It is estimated that among the competing ions, PO4(3-) is the major competitor of As(III) and As(V) adsorption onto Fe oxyhydroxide, and the competition ability decreases in the order PO4(3-) ≫ Fe(II) > H4SiO4 = HCO3(-). It is further revealed that a small change in pH can also have a significant effect on the mobility of As(III) and As(V) in the aquifers. A decrease in pH increases the concentration of As(III), whereas it decreases the As(V) concentration and vice versa. The present study suggests that the reductive dissolution of Fe oxyhydroxide alone cannot explain the observed high As concentration in groundwater of the Bengal Basin. This study supports the view that the reductive dissolution of Fe oxyhydroxide followed by competitive sorption reactions with the aquifer sediment is the processes responsible for As enrichment in groundwater. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Hydrogeological and biogeochemical constrains of arsenic mobilization in shallow aquifers from the Hetao basin, Inner Mongolia.

    Science.gov (United States)

    Guo, Huaming; Zhang, Bo; Li, Yuan; Berner, Zsolt; Tang, Xiaohui; Norra, Stefan; Stüben, Doris

    2011-04-01

    Little is known about the importance of drainage/irrigation channels and biogeochemical processes in arsenic distribution of shallow groundwaters from the Hetao basin. This investigation shows that although As concentrations are primarily dependent on reducing conditions, evaporation increases As concentration in the centre of palaeo-lake sedimentation. Near drainage channels, groundwater As concentrations are the lowest in suboxic-weakly reducing conditions. Results demonstrate that both drainage and irrigation channels produce oxygen-rich water that recharges shallow groundwaters and therefore immobilize As. Groundwater As concentration increases with a progressive decrease in redox potential along the flow path in an alluvial fan. A negative correlation between SO₄²⁻ concentrations and δ³⁴S values indicates that bacterial reduction of SO₄²⁻ occurs in reducing aquifers. Due to high concentrations of Fe (> 0.5 mg L⁻¹), reductive dissolution of Fe oxides is believed to cause As release from aquifer sediments. Target aquifers for safe drinking water resources are available in alluvial fans and near irrigation channels. Copyright © 2011 Elsevier Ltd. All rights reserved.

  7. A cluster-based randomized controlled trial promoting community participation in arsenic mitigation efforts in Bangladesh.

    Science.gov (United States)

    George, Christine Marie; van Geen, Alexander; Slavkovich, Vesna; Singha, Ashit; Levy, Diane; Islam, Tariqul; Ahmed, Kazi Matin; Moon-Howard, Joyce; Tarozzi, Alessandro; Liu, Xinhua; Factor-Litvak, Pam; Graziano, Joseph

    2012-06-19

    To reduce arsenic (As) exposure, we evaluated the effectiveness of training community members to perform water arsenic (WAs) testing and provide As education compared to sending representatives from outside communities to conduct these tasks. We conducted a cluster based randomized controlled trial of 20 villages in Singair, Bangladesh. Fifty eligible respondents were randomly selected in each village. In 10 villages, a community member provided As education and WAs testing. In a second set of 10 villages an outside representative performed these tasks. Overall, 53% of respondents using As contaminated wells, relative to the Bangladesh As standard of 50 μg/L, at baseline switched after receiving the intervention. Further, when there was less than 60% arsenic contaminated wells in a village, the classification used by the Bangladeshi and UNICEF, 74% of study households in the community tester villages, and 72% of households in the outside tester villages reported switching to an As safe drinking water source. Switching was more common in the outside-tester (63%) versus community-tester villages (44%). However, after adjusting for the availability of arsenic safe drinking water sources, well switching did not differ significantly by type of As tester (Odds ratio = 0.86[95% confidence interval 0.42-1.77). At follow-up, among those using As contaminated wells who switched to safe wells, average urinary As concentrations significantly decreased. The overall intervention was effective in reducing As exposure provided there were As-safe drinking water sources available. However, there was not a significant difference observed in the ability of the community and outside testers to encourage study households to use As-safe water sources. The findings of this study suggest that As education and WAs testing programs provided by As testers, irrespective of their residence, could be used as an effective, low cost approach to reduce As exposure in many As-affected areas of

  8. A cluster-based randomized controlled trial promoting community participation in arsenic mitigation efforts in Bangladesh

    Directory of Open Access Journals (Sweden)

    George Christine

    2012-06-01

    Full Text Available Abstract Objective To reduce arsenic (As exposure, we evaluated the effectiveness of training community members to perform water arsenic (WAs testing and provide As education compared to sending representatives from outside communities to conduct these tasks. Methods We conducted a cluster based randomized controlled trial of 20 villages in Singair, Bangladesh. Fifty eligible respondents were randomly selected in each village. In 10 villages, a community member provided As education and WAs testing. In a second set of 10 villages an outside representative performed these tasks. Results Overall, 53% of respondents using As contaminated wells, relative to the Bangladesh As standard of 50 μg/L, at baseline switched after receiving the intervention. Further, when there was less than 60% arsenic contaminated wells in a village, the classification used by the Bangladeshi and UNICEF, 74% of study households in the community tester villages, and 72% of households in the outside tester villages reported switching to an As safe drinking water source . Switching was more common in the outside-tester (63% versus community-tester villages (44%. However, after adjusting for the availability of arsenic safe drinking water sources, well switching did not differ significantly by type of As tester (Odds ratio =0.86[95% confidence interval 0.42-1.77. At follow-up, among those using As contaminated wells who switched to safe wells, average urinary As concentrations significantly decreased. Conclusion The overall intervention was effective in reducing As exposure provided there were As-safe drinking water sources available. However, there was not a significant difference observed in the ability of the community and outside testers to encourage study households to use As-safe water sources. The findings of this study suggest that As education and WAs testing programs provided by As testers, irrespective of their residence, could be used as an effective, low cost

  9. Sources and controls of Arsenic contamination in groundwater of Rajnandgaon and Kanker District, Chattisgarh Central India

    Science.gov (United States)

    Shukla, Dericks Praise; Dubey, C. S.; Singh, Ningthoujam P.; Tajbakhsh, M.; Chaudhry, M.

    2010-12-01

    SummaryA high concentration of Arsenic (As) contamination in ground water has been reported in the village of Kaudikasa in Rajnandgaon district, wherein around 10% of the population is suffering from As-borne diseases. The region does not share any demographic or geological similarity with the sedimentary aquifers of the Bengal Delta Plain in Eastern India, but represents an igneous terrain with elevated As concentrations in groundwater. There is limited information about the source of As in groundwater and its mobility constraints. In this area, almost all the wells are located in the granitic terrain with pegmatitic intrusions. Most of these wells are characterized by As concentration above the World Health Organization ( WHO, 1999) and the BIS (Bureau of Indian Standards) standards, with the highest being found in a well with more than 250 μg/L of As. Here we report petrographic studies of the granitic host rock and X-ray diffraction results that indicate that altered realgar (α-As 4S 4), para realgar (AsS), and/or tennantite (Cu 12As 4S 13), are the main mineral that contain As. This element is leached during the weathering and water-rock interactions. Microprobe analysis of the altered realgar grains of in pegmatitic intrusions of the host granite indicate 23-27 wt.% As. Remote sensing is useful to delineate the source of this contaminant, which appears to lie at the intersection of a mineralized NW-SE and N-S lineaments associated with the Kotri rift zone. These lineaments are structurally controlled as rifting followed by thrusting and other types of faulting caused left-lateral displacement of N-S Kotri lineament along a NW-SE fault plane showing sinistral shearing. This process caused water drainage in the areas to flow along these highly mineralized weak zones. Thus, the water becomes highly contaminated due to leaching of minerals at the intersection of these lineaments, clearly visible at two areas of high contamination that lie very near to this

  10. Dredging Operations Technical Support Program. Transformation, Fixation, and Mobilization of Arsenic and Antimony in Contaminated Sediments.

    Science.gov (United States)

    1984-01-01

    and Edwards (1977) reported that whole cells of :ethaogenic bacteria in variod anaerobic environments ( rumen fluid, sewage sludge) nproduced...sediments were studied with emphasis placed on short- and long-term 14 leaching and sediment conditions that affect mobilization. -; Under anaerobic ...conditions, arsenate [As(V)] was reduced to arsenite [As(III)] in a wide range of sediments. In anaerobic Texas City sediment slur- ries, 70% of added As(V

  11. A Case control study of cardiovascular disease and arsenic exposure in Inner Mongolia, China

    Science.gov (United States)

    Background: Millions of people are at risk from the adverse effects of waterborne arsenic. Although the cardiovascular effects of high exposures to arsenic have been well documented, few individual level prospective studies have assessed cardiovascular risk at moderate exposures....

  12. Groundwater geochemistry and its implications for arsenic mobilization in shallow aquifers of the Hetao Basin, Inner Mongolia

    International Nuclear Information System (INIS)

    Guo Huaming; Yang Suzhen; Tang Xiaohui; Li Yuan; Shen Zhaoli

    2008-01-01

    Arsenic concentrations in shallow groundwaters from the Hetao Basin of Inner Mongolia range between 0.6 and 572 μg/L. High As groundwaters generally occur in the shallow alluvial-lacustrine aquifers, which are mainly composed of black (or dark grey) fine sands in a reducing environment. They are characterized by high concentrations of dissolved Fe, Mn, HCO 3 - , P and S 2- , and low concentrations of NO 3 - and SO 4 2- . Low SO 4 2- coupled with high S 2- suggests that SO 4 2- reduction has been an active process. In the reducing groundwaters, inorganic As(III) accounts for around 75% of total dissolved As. Total As contents in the sediments from three representative boreholes are observed to be 7.3-73.3 mg/kg (average of 18.9 mg/kg). The total As is mildly-strongly correlated with total Fe and total Mn, while a quite weak correlation exists between total As and total S, suggesting that the As is associated with Fe-Mn oxides, rather than sulfides in the sediments. It is found in the sequential extraction that chemically active As is mainly bound to Fe-Mn oxides, up to 3500 μg/kg. The mobilization of As under reducing conditions is believed to include reductive dissolution of Fe-Mn oxides and reduction of adsorbed As. Although exchangeable As is labile and very vulnerable to hydrogeochemical condition, the contribution is relatively limited due to the low concentrations. The competition between As and other anions (such as HPO 4 2- ) for binding sites on Fe-Mn oxides may also give rise to the release of As into groundwater. Slow groundwater movement helps accumulation of the released As in the groundwaters

  13. Effect of dissolved organic matter derived from waste amendments on the mobility of inorganic arsenic (III) in the Egyptian alluvial soil

    Energy Technology Data Exchange (ETDEWEB)

    Rashad, Mohamed [Land and Water Technologies Department, Arid Lands Cultivation Research Institute, City of Scientific Research and Technological Applications (SRTA-City), New Borg El-Arab, 21934 Alexandria (Egypt); Assaad, Faiz F. [Soils and Water Use Department, National Research Centre, Dokki, Cairo (Egypt); Shalaby, Elsayed A. [Environmental Studies Department, Institute of Graduate Studies and Research, Alexandria University (Egypt)

    2013-07-01

    Dissolved organic matter (DOM) is one of the decisive factors affecting pollutants mobility in soils receiving waste amendments. The aim of this study was to investigate the effects of DOM1 derived from agricultural solid waste (ASW) and DOM2 derived from municipal solid waste (MSW) on the mobility of inorganic arsenic (As) in two alluvial soils from the Nile River Delta. In column experiments, addition of DOM solutions significantly increased As concentration in the effluents. There was no significant difference between the two soils, the obtained results from soil2 columns revealed that DOM2 has stronger capability than DOM1 to facilitate As mobility. The pH of the studied soils is alkaline (8.1) which promoted the dissociation as well as deprotonation of DOM and as a consequence, humic substances in DOM become negatively charged organic anions, leading to their substantial competition with As for the adsorption sites on both soil surfaces. The results emphasized that in alkaline soils there is a risk of groundwater pollution in the long run by arsenic either naturally found in soil or originated at high soil pH when dissolved organic carbon (DOC) released from various organic amendments ASW and/or MSW and leached through soil profile.

  14. Arsenic mobility and speciation in contaminated kitchen garden and lawn soils: an evaluation of water for assessment of As phytoavailability.

    Science.gov (United States)

    Waterlot, Christophe; Douay, Francis

    2015-04-01

    Emissions from primary lead smelters have been recognized as one of the mainly factor which has contributed to the contamination of soils by metals. Less attention has been paid to volatile metalloids such as arsenic (As) which accompanies lead (Pb) smelting activities. One of the objectives of this study was to determine the As concentrations in various extracting solutions using a collection of urban soils located no far away from two former Pb and zinc plants in the North of France. The procedure for the determination of As, As(III), and As(V) with hydride vapor generator atomic absorption spectrometry was described in details. Pseudo-total concentrations of As in the studied soils ranged from 5.3 to 65.9 mg kg(-1). Good correlations were found between As and lead, zinc, and cadmium concentrations in soils. These depended on the soil uses and the soil distance from the source of contamination. Because the form of As may pose a health risk to human population, its speciation was determined in each urban top soils. Very good correlations were found between As(III) and As(V) versus As concentrations in soils studied, but the results did no permit to establish a relation between the location of soils and their uses. In contrast, it was shown that the highest mobility factor and lowest partitioning index values were related to the location. The mobilty of As depended on the assimilated phosphorus (P), carbonate contents, and pH. The percentages of the water-extractable As concentrations ranged from 0.3 to 3.0% of the As concentrations in soils. Very good positive correlations between water-extractable As(III) and As(V) versus water-extractable As concentrations were obtained. It was shown that the water-extractable As(III) concentrations depended on the soil uses. The results revealed that soils for which the As was the most mobile presented the highest water-extractable As concentrations. Principal component analysis indicated that mechanisms related to the release

  15. Occurrence and geochemical behavior of arsenic in a coastal aquifer–aquitard system of the Pearl River Delta, China

    International Nuclear Information System (INIS)

    Wang, Ya; Jiao, Jiu Jimmy; Cherry, John A.

    2012-01-01

    Elevated concentrations of arsenic, up to 161 μg/L, have been identified in groundwater samples from the confined basal aquifer underlying the aquitard of the Pearl River Delta (PRD). Both aquatic arsenic in pore water and solid arsenic in the sediments in the basal aquifer and aquitard were identified. Arsenic speciation of groundwater in the basal aquifer was elucidated on a pH-Eh diagram. In the PRD, arsenic is enriched in groundwater having both low and high salinity, and arsenic enriched groundwater is devoid of dissolved oxygen, has negative Eh values, is slightly alkaline, and has abnormally high concentrations of ammonium and dissolved organic carbon, but low concentrations of nitrate and nitrite. Results of geochemical and hydrochemical analyses and sequential extraction analysis suggest that reductive dissolution of iron oxyhydroxide could be one of the important processes that mobilized solid arsenic. We speculate that mineralization of sedimentary organic matter could also contribute to aquatic arsenic. Scanning electron microscope analysis confirms that abundant authigenic pyrite is present in the sediments. Sulphate derived from paleo-seawater served as the important sulfur source for authigenic pyrite formation. Co-precipitation of arsenic with authigenic pyrite significantly controlled concentrations of aquatic arsenic in the coastal aquifer–aquitard system. - Highlights: ► Coastal aquifer and aquitard are treated as an integrate system. ► Both aquatic arsenic and solid arsenic are observed. ► Aquatic arsenic is derived from reductive dissolution of iron oxyhydroxide. ► Aquatic arsenic can also derived from mineralization of sedimentary organic matter. ► Co-precipitation of arsenic with authigenic pyrite is significant in such a system.

  16. Occurrence and geochemical behavior of arsenic in a coastal aquifer-aquitard system of the Pearl River Delta, China

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ya [Department of Earth Sciences, The University of Hong Kong, Hong Kong (China); Jiao, Jiu Jimmy, E-mail: jjiao@hku.hk [Department of Earth Sciences, The University of Hong Kong, Hong Kong (China); Cherry, John A. [School of Engineering, University of Guelph, Guelph, ON, Canada N1G 2W1 (Canada)

    2012-06-15

    Elevated concentrations of arsenic, up to 161 {mu}g/L, have been identified in groundwater samples from the confined basal aquifer underlying the aquitard of the Pearl River Delta (PRD). Both aquatic arsenic in pore water and solid arsenic in the sediments in the basal aquifer and aquitard were identified. Arsenic speciation of groundwater in the basal aquifer was elucidated on a pH-Eh diagram. In the PRD, arsenic is enriched in groundwater having both low and high salinity, and arsenic enriched groundwater is devoid of dissolved oxygen, has negative Eh values, is slightly alkaline, and has abnormally high concentrations of ammonium and dissolved organic carbon, but low concentrations of nitrate and nitrite. Results of geochemical and hydrochemical analyses and sequential extraction analysis suggest that reductive dissolution of iron oxyhydroxide could be one of the important processes that mobilized solid arsenic. We speculate that mineralization of sedimentary organic matter could also contribute to aquatic arsenic. Scanning electron microscope analysis confirms that abundant authigenic pyrite is present in the sediments. Sulphate derived from paleo-seawater served as the important sulfur source for authigenic pyrite formation. Co-precipitation of arsenic with authigenic pyrite significantly controlled concentrations of aquatic arsenic in the coastal aquifer-aquitard system. - Highlights: Black-Right-Pointing-Pointer Coastal aquifer and aquitard are treated as an integrate system. Black-Right-Pointing-Pointer Both aquatic arsenic and solid arsenic are observed. Black-Right-Pointing-Pointer Aquatic arsenic is derived from reductive dissolution of iron oxyhydroxide. Black-Right-Pointing-Pointer Aquatic arsenic can also derived from mineralization of sedimentary organic matter. Black-Right-Pointing-Pointer Co-precipitation of arsenic with authigenic pyrite is significant in such a system.

  17. Arsenic, microbes and contaminated aquifers

    Science.gov (United States)

    Oremland, Ronald S.; Stolz, John F.

    2005-01-01

    The health of tens of millions of people world-wide is at risk from drinking arsenic-contaminated well water. In most cases this arsenic occurs naturally within the sub-surface aquifers, rather than being derived from identifiable point sources of pollution. The mobilization of arsenic into the aqueous phase is the first crucial step in a process that eventually leads to human arsenicosis. Increasing evidence suggests that this is a microbiological phenomenon.

  18. Adaptive learning fuzzy control of a mobile robot

    International Nuclear Information System (INIS)

    Tsukada, Akira; Suzuki, Katsuo; Fujii, Yoshio; Shinohara, Yoshikuni

    1989-11-01

    In this report a problem is studied to construct a fuzzy controller for a mobile robot to move autonomously along a given reference direction curve, for which control rules are generated and acquired through an adaptive learning process. An adaptive learning fuzzy controller has been developed for a mobile robot. Good properties of the controller are shown through the travelling experiments of the mobile robot. (author)

  19. Arsenite-oxidizing and arsenate-reducing bacteria associated with arsenic-rich groundwater in Taiwan

    Science.gov (United States)

    Liao, Vivian Hsiu-Chuan; Chu, Yu-Ju; Su, Yu-Chen; Hsiao, Sung-Yun; Wei, Chia-Cheng; Liu, Chen-Wuing; Liao, Chung-Min; Shen, Wei-Chiang; Chang, Fi-John

    2011-04-01

    Drinking highly arsenic-contaminated groundwater is a likely cause of blackfoot disease in Taiwan, but microorganisms that potentially control arsenic mobility in the subsurface remain unstudied. The objective of this study was to investigate the relevant arsenite-oxidizing and arsenate-reducing microbial community that exists in highly arsenic-contaminated groundwater in Taiwan. We cultured and identified arsenic-transforming bacteria, analyzed arsenic resistance and transformation, and determined the presence of genetic markers for arsenic transformation. In total, 11 arsenic-transforming bacterial strains with different colony morphologies and varying arsenic transformation abilities were isolated, including 10 facultative anaerobic arsenate-reducing bacteria and one strictly aerobic arsenite-oxidizing bacterium. All of the isolates exhibited high levels of arsenic resistance with minimum inhibitory concentrations of arsenic ranging from 2 to 200 mM. Strain AR-11 was able to rapidly oxidize arsenite to arsenate at concentrations relevant to environmental groundwater samples without the addition of any electron donors or acceptors. We provide evidence that arsenic-reduction activity may be conferred by the ars operon(s) that were not amplified by the designed primers currently in use. The 16S rRNA sequence analysis grouped the isolates into the following genera: Pseudomonas, Bacillus, Psychrobacter, Vibrio, Citrobacter, Enterobacter, and Bosea. Among these genera, we present the first report of the genus Psychrobacter being involved in arsenic reduction. Our results further support the hypothesis that bacteria capable of either oxidizing arsenite or reducing arsenate coexist and are ubiquitous in arsenic-contaminated groundwater.

  20. Responses of wild small mammals to arsenic pollution at a partially remediated mining site in Southern France.

    Science.gov (United States)

    Drouhot, Séverine; Raoul, Francis; Crini, Nadia; Tougard, Christelle; Prudent, Anne-Sophie; Druart, Coline; Rieffel, Dominique; Lambert, Jean-Claude; Tête, Nicolas; Giraudoux, Patrick; Scheifler, Renaud

    2014-02-01

    Partial remediation actions at a former gold mine in Southern France led to a mosaic of contaminated and rehabilitated zones. In this study, the distribution of arsenic and its potential adverse effects on small mammals were investigated. The effectiveness of remediation for reducing the transfer of this element into wildlife was also discussed. Arsenic levels were measured in the soil and in the stomach contents, livers, kidneys, and lungs of four small mammal species (the wood mouse (Apodemus sylvaticus), the Algerian mouse (Mus spretus), the common vole (Microtus arvalis), and the greater white-toothed shrew (Crocidura russula)). The animals were caught at the former extraction site, in zones with three different levels of remediation treatments, and at a control site. Arsenic concentrations in the soil were highly spatially heterogeneous (ranging from 29 to 18,900 μg g(-1)). Despite the decrease in arsenic concentrations in the remediated soils, both wood mice and Algerian mice experienced higher oral exposure to arsenic in remediated zones than in the control area. The accumulated arsenic in their organs showed higher intra-zonal variability than the arsenic distribution in the soil, suggesting that, in addition to remediation processes, other variables can help explain arsenic transfer to wildlife, such as the habitat and diet preferences of the animals or their mobility. A weak but significant correlation between arsenic concentration and body condition was observed, and weak relationships between the liver/kidney/lung mass and arsenic levels were also detected, suggesting possible histological alterations. © 2013.

  1. Control of wheeled mobile robot in restricted environment

    Science.gov (United States)

    Ali, Mohammed A. H.; En, Chang Yong

    2018-03-01

    This paper presents a simulation and practical control system for wheeled mobile robot in restricted environment. A wheeled mobile robot with 3 wheels is fabricated and controlled by proportional derivative active force control (PD-AFC) to move in a pre-planned restricted environment to maintain the tracking errors at zero level. A control system with two loops, outer by PD controller and inner loop by Active Force Control, are designed to control the wheeled mobile robot. Fuzzy logic controller is implemented in the Active force Control to estimate the inertia matrix that will be used to calculate the actual torque applied on the wheeled mobile robot. The mobile robot is tested in two different trajectories, namely are circular and straight path. The actual path and desired path are compared.

  2. Formal-Language-Theoretic Control & Coordination of Mobile Robots

    National Research Council Canada - National Science Library

    Ray, Asok

    2007-01-01

    .... The research has formulated and experimentally validated robust adaptive algorithms and software codes for decision and control of mobile robotic platforms, as applied to real-time computation...

  3. Effect of Monsoon on spatio-temporal variation of groundwater chemistry and stable isotopic signatures: insights for concomitant arsenic mobilization in West Bengal, India

    Science.gov (United States)

    Majumder, S.; Datta, S.; Nath, B.; Neidhardt, H.; Roman-Ross, G.; Berner, Z.; Hidalgo, M.; Chatterjee, D.; Sarkar, S.

    2017-12-01

    Large-scale groundwater abstraction was hypothesized to be one of the important factors controlling release and distribution of arsenic (As) in aquifers of Bengal Basin. In this study, we studied the groundwater/surface water geochemistry of two different geomorphic domains within the Chakdaha Block, West Bengal, to identify potential influences of groundwater withdrawal on the hydrochemical evolution of the aquifer. This has been done as a function of different water inputs (monsoon rain, irrigation and downward percolation from surface water impoundments) to the groundwater system and associated As mobilization. A low-land flood plain (with relatively more reducing aquifer) and a natural levee (less reducing aquifer) have been chosen for this purpose. The stable isotopic signatures of oxygen (δ18O) and hydrogen (δ2H) falls sub-parallel to the Global Meteoric Water Line (GMWL), with precipitation and subsequent evaporation seems to be the major controlling factor on the water isotopic composition. This shows a contribution of evaporation influenced water, derived from various surface water bodies, pointing at large-scale groundwater withdrawal helping drawdown of the evaporated surface water. In case of flood plain wells, the stable isotope composition and the Cl/Br molar ratio in local groundwater have revealed vertical recharge within the flood plain area to be the major recharge process, especially during the post-monsoon season. However, both evaporation and vertical mixing are visibly controlling the groundwater recharge in the natural levee area. A possible inflow of organic carbon to the aquifer during the monsoonal recharge process is noticeable, with an increase in dissolved organic carbon (DOC) concentration from 1.33 to 6.29 mg/L on passing from pre- to post-monsoon season. Concomitant increase in AsT, Fe(II) and HCO3- during the post monsoon season, being more pronounced in the flood plain samples, indicates a possible initial episode of reductive

  4. Arsenic Removal from Drinking Water by Iron Removal - U.S. EPA Demonstration Project at Big Sauk Lake Mobile Home Park in Sauk Centre, MN Final Performance Evaluation Report

    Science.gov (United States)

    This report documents the activities performed and the results obtained from the one-year arsenic removal treatment technology demonstration project at the Big Sauk Lake Mobile Home Park (BSLMHP) in Sauk Centre, MN. The objectives of the project are to evaluate (1) the effective...

  5. Evaluation of Redox Conditions and Enhanced Arsenic Mobility from Waste Disposal in a Complex Fractured Crystalline-Rock Aquifer, Raymond, New Hampshire, USA (Note: article rewritten under new title)

    Science.gov (United States)

    (Note: This entry is no longer valid; the paper was rewritten and submitted to a different journal.) This paper highlights some methods that can be used at a local scale to assess whether waste disposal activities are responsible for enhanced arsenic mobility through redox-contro...

  6. Wireless Control of Miniaturized Mobile Vehicle for Indoor Surveillance

    International Nuclear Information System (INIS)

    Saquib, Syed M Taha; Hameed, Sarmad; Jafri, Raza; Usman Ali, Syed M; Amin, Imran

    2013-01-01

    This work is based upon electronic automation and Smart Control techniques, which constitute the basis of Control Area Network (CAN) and Personal Area Network (PAN). Bluetooth technology has been interfaced with a programmable controller to provide multi-dimensional vehicle control. A network is proposed which contains a remote, mobile host controller and an android operating system based mobile set (Client). The client communicates with a host controller through a Bluetooth device. The system incorporates duplex communication after successful confirmation between the host and the client; the android based mobile unit controls the vehicle through the Bluetooth module

  7. EMBEDDED CONTROL SYSTEM FOR MOBILE ROBOTS WITH DIFFERENTIAL DRIVE

    Directory of Open Access Journals (Sweden)

    Michal KOPČÍK

    2017-09-01

    Full Text Available This article deals with design and implementation of control system for mobile robots with differential drive using embedded system. This designed embedded system consists of single control board featuring ARM based microcontroller which control the peripherals in real time and perform all low-level motion control. Designed embedded system can be easily expanded with additional sensors, actuators or control units to enhance applicability of mobile robot. Designed embedded system also features build-in communication module, which can be used for data for data acquisition and control of the mobile robot. Control board was implemented on two different types of mobile robots with differential drive, one of which was wheeled and other was tracked. These mobile robots serve as testing platform for Fault Detection and Isolation using hardware and analytical redundancy using Multisensor Data Fusion based on Kalman filters.

  8. Water Chemistry Impacts on Arsenic Mobilization from Arsenopyrite Dissolution and Secondary Mineral Precipitation: Implications for Managed Aquifer Recharge

    Science.gov (United States)

    Managed Aquifer Recharge (MAR) is one water reuse technique with the potential to meet growing water demands. However, MAR sites have encountered arsenic remobilization resulting from recharge operations. To combat this challenge, it is important to identify the mechanism of arse...

  9. Solid state cloaking for electrical charge carrier mobility control

    Science.gov (United States)

    Zebarjadi, Mona; Liao, Bolin; Esfarjani, Keivan; Chen, Gang

    2015-07-07

    An electrical mobility-controlled material includes a solid state host material having a controllable Fermi energy level and electrical charge carriers with a charge carrier mobility. At least one Fermi level energy at which a peak in charge carrier mobility is to occur is prespecified for the host material. A plurality of particles are distributed in the host material, with at least one particle disposed with an effective mass and a radius that minimize scattering of the electrical charge carriers for the at least one prespecified Fermi level energy of peak charge carrier mobility. The minimized scattering of electrical charge carriers produces the peak charge carrier mobility only at the at least one prespecified Fermi level energy, set by the particle effective mass and radius, the charge carrier mobility being less than the peak charge carrier mobility at Fermi level energies other than the at least one prespecified Fermi level energy.

  10. Cardiovascular disease and arsenic exposure in Inner Mongolia, China: a case control study

    Science.gov (United States)

    BACKGROUND: Millions of people are at risk from the adverse effects of arsenic exposure through drinking water. Increasingly, non-cancer effects such as cardiovascular disease have been associated with drinking water arsenic exposures. However, most studies have been conducted in...

  11. Biogeochemical Controls on Technetium Mobility in Biogeochemical Controls on Technetium Mobility in FRC Sediments

    International Nuclear Information System (INIS)

    Lloyd, J.R.; McBeth, J.M.; Livens, F.R.; Bryan, N.D.; Ellis, B.; Sharma, H.; Burke, I.T.; Morris, K.

    2004-01-01

    Technetium-99 is a priority pollutant at numerous DOE sites, due to its long half-life (2.1 x 10 5 years), high mobility as Tc(VII) in oxic waters, and bioavailability as a sulfate analog. 99 Tc is far less mobile under anaerobic conditions, forming insoluble Tc(IV) precipitates. As anaerobic microorganisms can reduce soluble Tc(VII) to insoluble Tc(IV), microbial metabolism may have the potential to treat sediments and waters contaminated with Tc. Baseline studies of fundamental mechanisms of Tc(VII) bioreduction and precipitation (reviewed by Lloyd et al, 2002) have generally used pure cultures of metal-reducing bacteria, in order to develop conceptual models for the biogeochemical cycling of Tc. There is, however, comparatively little known about interactions of metal-reducing bacteria with environmentally relevant trace concentrations of Tc, against a more complex biogeochemical background provided by mixed microbial communities in the subsurface. The objective of this new NABIR project is to probe the site specific biogeochemical conditions that control the mobility of Tc at the FRC (Oak Ridge, TN). This information is required for the rational design of in situ bioremediation strategies for technetium-contaminated subsurface environments. We will use a combination of geochemical, mineralogical, microbiological and spectroscopic techniques to determine the solubility and phase associations of Tc in FRC sediments, and characterize the underpinning biogeochemical controls. A key strength of this project is that many of the techniques we are using have already been optimized by our research team, who are also studying the biogeochemical controls on Tc mobility in marine and freshwater sediments in the UK in a NERC funded companion study.

  12. Mobility and natural attenuation of metals and arsenic in acidic waters of the drainage system of Timok River from Bor copper mines (Serbia) to Danube River.

    Science.gov (United States)

    Đorđievski, Stefan; Ishiyama, Daizo; Ogawa, Yasumasa; Stevanović, Zoran

    2018-06-22

    Bor, Krivelj, and Bela Rivers belong to the watershed of Timok River, which is a tributary of transboundary Danube River. These rivers receive metal-rich acidic wastewater from metallurgical facilities and acid mine drainage (AMD) from mine wastes around Bor copper mines. The aim of this study was to determine the mobility and natural attenuation of metals and arsenic in rivers from Bor copper mines to Danube River during the year 2015. The results showed that metallurgical facilities had the largest impact on Bor River by discharging about 400 t of Cu per year through highly acidic wastewater (pH = 2.6). The highest measured concentrations of Cu in river water and sediments were 40 mg L -1 and 1.6%, respectively. Dissolution of calcite from limestone bedrock and a high concentration of bicarbonate ions in natural river water (about 250 mg L -1 ) enhanced the neutralization of acidic river water and subsequent chemical precipitation of metals and arsenic. Decreases in the concentrations of Al, Fe, Cu, As, and Pb in river water were mainly due to precipitation on the river bed. On the other hand, dilution played an important role in the decreases in concentrations of Mn, Ni, Zn, and Cd. Chemically precipitated materials and flotation tailings containing Fe-rich minerals (fayalite, magnetite, and pyrite) were transported toward Danube River during the periods of high discharge. This study showed that processes of natural attenuation in catchments with limestone bedrock play an important role in reducing concentrations of metals and arsenic in AMD-bearing river water.

  13. Hierarchical coordination control of mobile robots

    NARCIS (Netherlands)

    Adinandra, S.

    2012-01-01

    In the last decade, robotic systems have penetrated human life more than human can imagine. In particular, the multi-mobile robotic systems have faced a fast growing due to the fact that by deploying a large collection of mobile robots the overall system has a high redundancy and offers the

  14. Mechanisms controlling radionuclide mobility in forest soils

    International Nuclear Information System (INIS)

    Delvaux, B.; Kruyts, N.; Maes, E.; Agapkina, G.I.; Kliashtorin, A.; Bunzl, K.; Rafferty, B.

    1996-01-01

    Soil processes strongly influence the radionuclide mobility in soils. The mobility of radionuclides in forest soils is governed by several processes involving both abiotic and biotic factors. The sorption-desorption process chiefly governs the activity of radionuclides in the soil solution, hence thereby their mobility and biological availability. Radiocaesium exhibits a very low mobility in mineral soils. Both mobility and bioavailability however increase as the thickness of organic layers and their content in organic matter increases. Clay minerals of micaceous origin strongly act as slinks for radiocaesium in forest soils. The magnitude of cesium mineral fixation in topsoils is expected to be the highest in mineral soils of Eutric cambisol type, and, to a lesser extent, of type of Distric cambisol and Podzoluvisol. A low mobility of radiocaesium in the surface horizons of forest soils may also be partially explained by a biological mobilization: fungi absorb radiocaesium and transport it to upper layers, thereby contributing to constantly recycle the radioelement in the organic horizons. This mechanism is probably important in soils with thick organic layers (Podsol, Histosol, and, to a lesser extent, Distric cambisol and Podzoluvisol). Radionuclides can be associated with soluble organic anions in the soil solution of forest acid soils. Such associations are highly mobile: they are stable in conditions of poor biological activity (low temperatures, acid soil infertility, water excess, etc.). Their magnitude is expected to be the highest in thick acid organic layers (soils of type Podzol and Histosol)

  15. Residential Mobility, Inhibitory Control, and Academic Achievement in Preschool

    Science.gov (United States)

    Schmitt, Sara A.; Finders, Jennifer K.; McClelland, Megan M.

    2015-01-01

    Research Findings: The present study investigated the direct effects of residential mobility on children's inhibitory control and academic achievement during the preschool year. It also explored fall inhibitory control and academic skills as mediators linking residential mobility and spring achievement. Participants included 359 preschool children…

  16. Flow and sorption controls of groundwater arsenic in individual boreholes from bedrock aquifers in central Maine, USA

    Science.gov (United States)

    Yang, Qiang; Culbertson, Charles W.; Nielsen, Martha G.; Schalk, Charles W.; Johnson, Carole D.; Marvinney, Robert G.; Stute, Martin; Zheng, Yan

    2014-01-01

    To understand the hydrogeochemical processes regulating well water arsenic (As) evolution in fractured bedrock aquifers, three domestic wells with [As] up to 478 μg/L are investigated in central Maine. Geophysical logging reveals that fractures near the borehole bottom contribute 70-100% of flow. Borehole and fracture water samples from various depths show significant proportions of As (up to 69%) and Fe (93-99%) in particulates (>0.45 μm). These particulates and those settled after a 16-day batch experiment contain 560-13,000 g/kg of As and 14-35% weight/weight of Fe. As/Fe ratios (2.5-20 mmol/mol) and As partitioning ratios (adsorbed/dissolved [As], 20,000-100,000 L/kg) suggest that As is sorbed onto amorphous hydrous ferric oxides. Newly drilled cores also show enrichment of As (up to 1300 mg/kg) sorbed onto secondary iron minerals on the fracture surfaces. Pumping at high flow rates induces large decreases in particulate As and Fe, a moderate increase in dissolved [As] and As(III)/As ratio, while little change in major ion chemistry. The δD and δ18O are similar for the borehole and fracture waters, suggesting a same source of recharge from atmospheric precipitation. Results support a conceptual model invoking flow and sorption controls on groundwater [As] in fractured bedrock aquifers whereby oxygen infiltration promotes the oxidation of As-bearing sulfides at shallower depths in the oxic portion of the flow path releasing As and Fe; followed by Fe oxidation to form Fe oxyhydroxide particulates, which are transported in fractures and sorb As along the flow path until intercepted by boreholes. In the anoxic portions of the flow path, reductive dissolution of As-sorbed iron particulates could re-mobilize As. For exposure assessment, we recommend sampling of groundwater without filtration to obtain total As concentration in groundwater.

  17. Flow and sorption controls of groundwater arsenic in individual boreholes from bedrock aquifers in central Maine, USA

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Qiang [Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9 W, Palisades, NY 10964 (United States); School of Earth and Environmental Sciences, Queens College and Graduate Center, City University of New York, 65-30 Kissena Blvd., Flushing, NY 11367 (United States); Culbertson, Charles W.; Nielsen, Martha G.; Schalk, Charles W. [U.S. Geological Survey, Maine Water Science Center, 196 Whitten Road, Augusta, ME 04330 (United States); Johnson, Carole D. [U.S. Geological Survey, Branch of Geophysics, 11 Sherman Place, Unit 5015, University of Connecticut, Storrs, CT 06269 (United States); Marvinney, Robert G. [Maine Geological Survey, 93 State House Station, Augusta, ME 04333 (United States); Stute, Martin [Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9 W, Palisades, NY 10964 (United States); Zheng, Yan, E-mail: yan.zheng@qc.cuny.edu [Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9 W, Palisades, NY 10964 (United States); School of Earth and Environmental Sciences, Queens College and Graduate Center, City University of New York, 65-30 Kissena Blvd., Flushing, NY 11367 (United States)

    2015-02-01

    To understand the hydrogeochemical processes regulating well water arsenic (As) evolution in fractured bedrock aquifers, three domestic wells with [As] up to 478 μg/L are investigated in central Maine. Geophysical logging reveals that fractures near the borehole bottom contribute 70–100% of flow. Borehole and fracture water samples from various depths show significant proportions of As (up to 69%) and Fe (93–99%) in particulates (> 0.45 μm). These particulates and those settled after a 16-day batch experiment contain 560–13,000 mg/kg of As and 14–35% weight/weight of Fe. As/Fe ratios (2.5–20 mmol/mol) and As partitioning ratios (adsorbed/dissolved [As], 20,000–100,000 L/kg) suggest that As is sorbed onto amorphous hydrous ferric oxides. Newly drilled cores also show enrichment of As (up to 1300 mg/kg) sorbed onto secondary iron minerals on the fracture surfaces. Pumping at high flow rates induces large decreases in particulate As and Fe, a moderate increase in dissolved [As] and As(III)/As ratio, while little change in major ion chemistry. The δD and δ{sup 18}O are similar for the borehole and fracture waters, suggesting a same source of recharge from atmospheric precipitation. Results support a conceptual model invoking flow and sorption controls on groundwater [As] in fractured bedrock aquifers whereby oxygen infiltration promotes the oxidation of As-bearing sulfides at shallower depths in the oxic portion of the flow path releasing As and Fe; followed by Fe oxidation to form Fe oxyhydroxide particulates, which are transported in fractures and sorb As along the flow path until intercepted by boreholes. In the anoxic portions of the flow path, reductive dissolution of As-sorbed iron particulates could re-mobilize As. For exposure assessment, we recommend sampling of groundwater without filtration to obtain total As concentration in groundwater. - Highlights: • Most Fe and some As exist as particulates in the tested borehole and fracture water.

  18. Mobile robot navigation in unknown static environments using ANFIS controller

    Directory of Open Access Journals (Sweden)

    Anish Pandey

    2016-09-01

    Full Text Available Navigation and obstacle avoidance are the most important task for any mobile robots. This article presents the Adaptive Neuro-Fuzzy Inference System (ANFIS controller for mobile robot navigation and obstacle avoidance in the unknown static environments. The different sensors such as ultrasonic range finder sensor and sharp infrared range sensor are used to detect the forward obstacles in the environments. The inputs of the ANFIS controller are obstacle distances obtained from the sensors, and the controller output is a robot steering angle. The primary objective of the present work is to use ANFIS controller to guide the mobile robot in the given environments. Computer simulations are conducted through MATLAB software and implemented in real time by using C/C++ language running Arduino microcontroller based mobile robot. Moreover, the successful experimental results on the actual mobile robot demonstrate the effectiveness and efficiency of the proposed controller.

  19. Design of a hybrid command and control mobile botnet

    CSIR Research Space (South Africa)

    Pieterse, H

    2013-05-01

    Full Text Available and control mobile botnet. The hybrid design explores the efficiency of multiple command and control channels against the following objectives: no single point of failure within the topology, low cost for command dissemination, limited network activities...

  20. Atmospheric heavy metals and Arsenic in China: Situation, sources and control policies

    Science.gov (United States)

    Duan, Jingchun; Tan, Jihua

    2013-08-01

    In recent years, heavy metal pollution accidents were reported frequently in China. The atmospheric heavy metal pollution is drawing all aspects of attention. This paper summarizes the recent research results from our studies and previous studies in recent years in China. The level, temporal variation, seasonal variation and size distribution of the heavy metals of atmospheric Lead(Pb), Vanadium(V), Manganese(Mn), Nickel(Ni), Chromium(Cr), Cadmium(Cd), Copper(Cu), Zinc(Zn) and Arsenic(As) were characterized in China. The emission characteristics and sources of atmospheric heavy metals and As in China were reviewed. Coal burning, iron and steel industry and vehicle emission are important sources in China. Control policies and effects in China were reviewed including emission standards, ambient air quality standards, phase out of leaded gasoline and so on, and further works for atmospheric heavy metals control were suggested. The comprehensive heavy metals pollution control measures and suggestions were put forward based on the summarization of the development and experience of the atmospheric heavy metal pollution control abroad.

  1. Origin, mobility, and temporal evolution of arsenic from a low-contamination catchment in Alpine crystalline rocks

    Energy Technology Data Exchange (ETDEWEB)

    Pili, Eric, E-mail: Eric.Pili@cea.fr [CEA, DAM, DIF, F-91297 Arpajon (France); Institut de Physique du Globe de Paris-Sorbonne Paris Cité, CNRS, Université Paris Diderot, 1 rue Jussieu, F-75238 Paris cedex 05 (France); Tisserand, Delphine, E-mail: Delphine.Tisserand@obs.ujf-grenoble.fr [Institut des Sciences de la Terre (ISTerre) Université Joseph Fourier and CNRS, BP 53, 38041 Grenoble cedex 9 (France); Bureau, Sarah, E-mail: Sarah.Bureau@obs.ujf-grenoble.fr [Institut des Sciences de la Terre (ISTerre) Université Joseph Fourier and CNRS, BP 53, 38041 Grenoble cedex 9 (France)

    2013-11-15

    Highlights: ► δ{sup 34}S{sub SO4} vs. [As] and δ{sup 18}O{sub SO4} vs. As{sup V}/As{sup III} correlations provide new tools even for low [As]. ► Long-term and high-resolution monitoring shows droughts enhance pyrite dissolution. ► Major effect of 2003 European heatwave on pyrite dissolution and [As] increase. -- Abstract: The reduction to 10 μg/l of the limit for arsenic in drinking water led many resource managers to deal with expensive treatments. In the very common case of arsenic levels close to the recommended maximum concentration, knowing the origin and temporal evolution of As has become of great importance. Here we present a case study from an alpine basin. Arsenic speciation, isotopic compositions of pyrite, sulfate and water, and concentrations of major and trace elements demonstrate a geogenic source for arsenic linked to the dissolution of pyrite. We provide new tools to further study As at low concentrations where many processes may be masked. The observed negative correlation between δ{sup 34}S{sub SO4} and [As] is interpreted as a Rayleigh-type sulfur-isotope fractionation during increasing pyrite dissolution. The observed positive correlation between δ{sup 18}O{sub SO4} and As{sup V}/As{sup III} could help to retrieve initial redox conditions. A 3-year long monitoring at high-resolution demonstrated that drought conditions enhance pyrite dissolution whose degradation products are scavenged by recharge water. An increase in As in groundwater may result from droughts due to enhanced oxygen entry in the unsaturated zone. The 2003 European heatwave had a major effect.

  2. Arsenic Methyltransferase

    Science.gov (United States)

    The metalloid arsenic enters the environment by natural processes (volcanic activity, weathering of rocks) and by human activity (mining, smelting, herbicides and pesticides). Although arsenic has been exploited for homicidal and suicidal purposes since antiquity, its significan...

  3. Contrasting distributions of groundwater arsenic and uranium in the western Hetao basin, Inner Mongolia: Implication for origins and fate controls

    Science.gov (United States)

    Guo, Huaming; Jia, Yongfeng; Wanty, Richard B.; Jiang, Yuxiao; Zhao, Weiguang; Xiu, Wei; Shen, Jiaxing; Li, Yuan; Cao, Yongsheng; Wu, Yang; Zhang, Di; Wei, Chao; Zhang, Yilong; Cao, Wengeng; Foster, Andrea L.

    2016-01-01

    Although As concentrations have been investigated in shallow groundwater from the Hetao basin, China, less is known about U and As distributions in deep groundwater, which would help to better understand their origins and fate controls. Two hundred and ninety-nine groundwater samples, 122 sediment samples, and 14 rock samples were taken from the northwest portion of the Hetao basin, and analyzed for geochemical parameters. Results showed contrasting distributions of groundwater U and As, with high U and low As concentrations in the alluvial fans along the basin margins, and low U and high As concentrations downgradient in the flat plain. The probable sources of both As and U in groundwater were ultimately traced to the bedrocks in the local mountains (the Langshan Mountains). Chemical weathering of U-bearing rocks (schist, phyllite, and carbonate veins) released and mobilized U as UO2(CO3)22 − and UO2(CO3)34 − species in the alluvial fans under oxic conditions and suboxic conditions where reductions of Mn and NO3− were favorable (OSO), resulting in high groundwater U concentrations. Conversely, the recent weathering of As-bearing rocks (schist, phyllite, and sulfides) led to the formation of As-bearing Fe(III) (hydr)oxides in sediments, resulting in low groundwater As concentrations. Arsenic mobilization and U immobilization occurred in suboxic conditions where reduction of Fe(III) oxides was favorable and reducing conditions (SOR). Reduction of As-bearing Fe(III) (hydr)oxides, which were formed during palaeo-weathering and transported and deposited as Quaternary aquifer sediments, was believed to release As into groundwater. Reduction of U(VI) to U(IV) would lead to the formation of uraninite, and therefore remove U from groundwater. We conclude that the contrasting distributions of groundwater As and U present a challenge to ensuring safe drinking water in analogous areas, especially with high background values of U and As.

  4. Self-control and problematic mobile phone use in Chinese college students: the mediating role of mobile phone use patterns

    OpenAIRE

    Jiang, Zhaocai; Zhao, Xiuxin

    2016-01-01

    Background With the popularity of mobile phones, problematic mobile phone use is getting increasing attention in recent years. Although self-control was found to be a critical predictor of problematic mobile phone use, no study has ever explored the association between self-control and mobile phone use patterns as well as the possible pathway how self-control affects problematic mobile phone use. Methods Four hundred sixty-eight college students were randomly selected in this study. Data were...

  5. Characterization of ferric arsenate-sulfate compounds: Implications for arsenic control in refractory gold processing residues

    Czech Academy of Sciences Publication Activity Database

    Paktunc, D.; Majzlan, J.; Palatinus, Lukáš; Dutrizac, J.; Klementová, Mariana; Poirier, G.

    2013-01-01

    Roč. 98, č. 4 (2013), s. 554-565 ISSN 0003-004X Institutional support: RVO:68378271 Keywords : arsenic * ferric arsenate sulfate * autoclave residue * hydrometallurgy Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.059, year: 2013

  6. Diffusive Gradients in Thin Films Reveals Differences in Antimony and Arsenic Mobility in a Contaminated Wetland Sediment during an Oxic-Anoxic Transition.

    Science.gov (United States)

    Arsic, Maja; Teasdale, Peter R; Welsh, David T; Johnston, Scott G; Burton, Edward D; Hockmann, Kerstin; Bennett, William W

    2018-02-06

    Antimony (Sb) and arsenic (As) are priority environmental contaminants that often co-occur at mining-impacted sites. Despite their chemical similarities, Sb mobility in waterlogged sediments is poorly understood in comparison to As, particularly across the sediment-water interface (SWI) where changes can occur at the millimeter scale. Combined diffusive gradients in thin films (DGT) and diffusive equilibration in thin films (DET) techniques provided a high resolution, in situ comparison between Sb, As, and iron (Fe) speciation and mobility across the SWI in contaminated freshwater wetland sediment mesocosms under an oxic-anoxic-oxic transition. The shift to anoxic conditions released Fe(II), As(III), and As(V) from the sediment to the water column, consistent with As release being coupled to the reductive dissolution of iron(III) (hydr)oxides. Conversely, Sb(III) and Sb(V) effluxed to the water column under oxic conditions and fluxed into the sediment under anoxic conditions. Porewater DGT-DET depth profiles showed apparent decoupling between Fe(II) and Sb release, as Sb was primarily mobilized across the SWI under oxic conditions. Solid-phase X-ray absorption spectroscopy (XAS) revealed the presence of an Sb(III)-S phase in the sediment that increased in proportion with depth and the transition from oxic to anoxic conditions. The results of this study showed that Sb mobilization was decoupled from the Fe cycle and was, therefore, more likely linked to sulfur and/or organic carbon (e.g., most likely authigenic antimony sulfide formation or Sb(III) complexation by reduced organic sulfur functional groups).

  7. Arsenic mobility from anthropogenic impoundment sediments - Consequences of contamination to biota, water and sediments, Posa, Eastern Slovakia

    Energy Technology Data Exchange (ETDEWEB)

    Hiller, E.; Jurkovic, L.; Kordik, J.; Slaninka, I.; Jankular, M.; Majzlan, J.; Gottlicher, J.; Steininger, R. [Geological Survey of Slovak Republic, Bratislava (Slovakia). Dept. of Environmental Geochemistry

    2009-11-15

    An impoundment located near the village of Posa, Slovakia, is a significant source of contamination with As originating from the deposited coal fly-ash. Waters penetrating the impoundment are enriched in As and other potentially toxic elements. As a consequence of the contamination, the Kyjov Brook and the Ondava River have been extensively polluted. The mobility and solid-state partitioning of As in the impoundment material and stream sediments were investigated using column leaching and batch extraction tests, and a five-step sequential extraction procedure. Moreover, to investigate the bioavailability of As, two native plant species (Typha latifolia, or cattail, and Phragmites australis, or common reed) growing at the site were collected and analyzed. The As concentrations in representative sediment and water samples ranged from 36.3 to 3210 mg/kg and from 4.05 to 613 {mu} g/L, respectively, both being many times above the background levels. Although a part of As was present in a readily soluble form (6.6%), the majority of As was mainly associated with Fe and Mn oxides (37%) and residual phases (51%). Combined results of the column leaching, batch extraction, and sequential extraction tests, as well as mineralogical analysis, indicated that As mobilisation potential from the sediments is likely controlled by Fe, Al and Mn oxides, and by pH. There was no influence of various anions (PO{sub 4}{sup 3-}, SO{sub 4}{sup 2-}, NO{sup 3-}, Cl{sup -} and HCO{sub 3}{sup -}) on As mobility when present in aqueous solution at concentrations analogous to those in the water of the Kyjov Brook. Plants growing in the impoundment had As concentrations 10-100 times greater than did the same plants growing in a relatively non-polluted area.

  8. Design of a hybrid command and control mobile botnet: Presentation

    CSIR Research Space (South Africa)

    Pieterse, H

    2013-03-01

    Full Text Available smartphones controlled by a botmaster through a command and control network to serve a malicious purpose. This study presents the design of a hybrid command and control mobile botnet. It describes the propagation vectors, command and control channels...

  9. Flexible and Safe Control of Mobile Surface Systems, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The primary innovation of this work is a novel approach for flexible and safe control of highly capable mobile surface systems, such as long-duration science rovers,...

  10. Integrated Control Strategies Supporting Autonomous Functionalities in Mobile Robots

    National Research Council Canada - National Science Library

    Sights, B; Everett, H. R; Pacis, E. B; Kogut, G; Thompson, M

    2005-01-01

    High-level intelligence allows a mobile robot to create and interpret complex world models, but without a precise control system, the accuracy of the world model and the robot's ability to interact...

  11. Flexible and Safe Control of Mobile Surface Systems, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The primary innovation of this work is a novel Petri net based approach for safe and flexible control of highly capable mobile surface systems, such as long-duration...

  12. Navigation Algorithm Using Fuzzy Control Method in Mobile Robotics

    Directory of Open Access Journals (Sweden)

    Cviklovič Vladimír

    2016-03-01

    Full Text Available The issue of navigation methods is being continuously developed globally. The aim of this article is to test the fuzzy control algorithm for track finding in mobile robotics. The concept of an autonomous mobile robot EN20 has been designed to test its behaviour. The odometry navigation method was used. The benefits of fuzzy control are in the evidence of mobile robot’s behaviour. These benefits are obtained when more physical variables on the base of more input variables are controlled at the same time. In our case, there are two input variables - heading angle and distance, and two output variables - the angular velocity of the left and right wheel. The autonomous mobile robot is moving with human logic.

  13. Bake-Out Mobile Controls for Large Vacuum Systems

    CERN Document Server

    Blanchard, S; Gomes, P; Pereira, H; Kopylov, L; Merker, S; Mikheev, M

    2014-01-01

    Large vacuum systems at CERN (Large Hadron Collider - LHC, Low Energy Ion Rings - LEIR...) require bake-out to achieve ultra-high vacuum specifications. The bake-out cycle is used to decrease the outgassing rate of the vacuum vessel and to activate the Non-Evaporable Getter (NEG) thin film. Bake-out control is a Proportional-Integral-Derivative (PID) regulation with complex recipes, interlocks and troubleshooting management and remote control. It is based on mobile Programmable Logic Controller (PLC) cabinets, fieldbus network and Supervisory Control and Data Acquisition (SCADA) application. The CERN vacuum installations include more than 7 km of baked vessels; using mobile cabinets reduces considerably the cost of the control system. The cabinets are installed close to the vacuum vessels during the time of the bake-out cycle. Mobile cabinets can be used in any of the CERN vacuum facilities. Remote control is provided through a fieldbus network and a SCADA application

  14. Rethinking the economics of capital mobility and capital controls

    Directory of Open Access Journals (Sweden)

    Thomas I. Palley

    2009-09-01

    Full Text Available This paper reexamines the issue of international financial capital mobility, which is today's economic orthodoxy. Discussion is often framed in terms of the impossible trinity. That framing distorts discussion by representing capital mobility as having equal significance with sovereign monetary policy and control over exchange rates. It also distorts discussion by ignoring possibilities for coordinated monetary policy and exchange rates, and for managed capital flows. The case for capital mobility rests on neo-classical economic efficiency arguments and neo-liberal political arguments. The case against capital mobility is based on Keynesian macroeconomic inefficiency arguments, neo-Walrasian market failure arguments, and neo-Marxian arguments regarding distortion of the social structure of accumulation. Close examination shows the case for capital mobility to be extremely flimsy, pointing to the ideological dimension behind today's policy orthodoxy.

  15. A mobile console for local access to accelerator control systems.

    CERN Multimedia

    1981-01-01

    Microprocessors were installed as auxiliary crate controllers (ACCs) in the CAMAC interface of control systems for various accelerators. The same ACC was also at the hearth of a stand-alone system in the form of a mobile console. This was also used for local access to the control systems for tests and development work (Annual Report 1981, p. 80, Fig. 10).

  16. Automated microprocessor-controlled atomic absorption analysis of natural water for arsenic and selenium

    International Nuclear Information System (INIS)

    Morrow, R.W.; Futrell, T.L.; Adams, T.T.

    1978-08-01

    An automated, dual-channel atomic absorption spectrophotometer for the simultaneous determination of arsenic and selenium in natural water is now in operation. The instrument was constructed from commercially available optical components, spectral sources, and a sample changer. Automation was achieved by using an in-house-fabricated and programmed microprocessor. The instrument will analyze samples at a rate of 37 per hour, and a quantitative determination of arsenic and selenium to 0.2 μg/l (ppB) can be achieved. Arsenic can be determined with a precision of 19% at 1 μg/l and 6% at 10 μg/l, while selenium can be determined with a precision of 17% at 1 μg/l and 4% at 10 μg/l

  17. Car-Like Mobile Robot Oriented Positioning by Fuzzy Controllers

    Directory of Open Access Journals (Sweden)

    Noureddine Ouadah

    2008-11-01

    Full Text Available In this paper, fuzzy logic controllers (FLC are used to implement an efficient and accurate positioning of an autonomous car-like mobile robot, respecting final orientation. To accomplish this task, called "Oriented Positioning", two FLC have been developed: robot positioning controller (RPC and robot following controller (RFC. Computer simulation results illustrate the effectiveness of the proposed technique. Finally, real-time experiments have been made on an autonomous car-like mobile robot called "Robucar", developed to perform people transportation. Obtained results from experiments demonstrate the effectiveness of the proposed control strategy.

  18. Car-Like Mobile Robot Oriented Positioning by Fuzzy Controllers

    Directory of Open Access Journals (Sweden)

    Noureddine Ouadah

    2008-09-01

    Full Text Available In this paper, fuzzy logic controllers (FLC are used to implement an efficient and accurate positioning of an autonomous car-like mobile robot, respecting final orientation. To accomplish this task, called “Oriented Positioning”, two FLC have been developed: robot positioning controller (RPC and robot following controller (RFC. Computer simulation results illustrate the effectiveness of the proposed technique. Finally, real-time experiments have been made on an autonomous car-like mobile robot called “Robucar”, developed to perform people transportation. Obtained results from experiments demonstrate the effectiveness of the proposed control strategy.

  19. Exception detection and handling in mission control for mobile robots

    DEFF Research Database (Denmark)

    Andersen, Thomas Timm; Andersen, Nils Axel; Ravn, Ole

    2013-01-01

    This paper introduces a method for robust, rule-based mission control for mobile robots in a modular framework. Due to the modularity of the framework, it is possible to use both hierarchical control and reactive behavior seamlessly to find solutions to both planned and unplanned event in the mis......This paper introduces a method for robust, rule-based mission control for mobile robots in a modular framework. Due to the modularity of the framework, it is possible to use both hierarchical control and reactive behavior seamlessly to find solutions to both planned and unplanned event...

  20. Flow and sorption controls of groundwater arsenic in individual boreholes from bedrock aquifers in central Maine, USA.

    Science.gov (United States)

    Yang, Qiang; Culbertson, Charles W; Nielsen, Martha G; Schalk, Charles W; Johnson, Carole D; Marvinney, Robert G; Stute, Martin; Zheng, Yan

    2015-02-01

    To understand the hydrogeochemical processes regulating well water arsenic (As) evolution in fractured bedrock aquifers, three domestic wells with [As] up to 478 μg/L are investigated in central Maine. Geophysical logging reveals that fractures near the borehole bottom contribute 70-100% of flow. Borehole and fracture water samples from various depths show significant proportions of As (up to 69%) and Fe (93-99%) in particulates (>0.45 μm). These particulates and those settled after a 16-day batch experiment contain 560-13,000 mg/kg of As and 14-35% weight/weight of Fe. As/Fe ratios (2.5-20 mmol/mol) and As partitioning ratios (adsorbed/dissolved [As], 20,000-100,000 L/kg) suggest that As is sorbed onto amorphous hydrous ferric oxides. Newly drilled cores also show enrichment of As (up to 1300 mg/kg) sorbed onto secondary iron minerals on the fracture surfaces. Pumping at high flow rates induces large decreases in particulate As and Fe, a moderate increase in dissolved [As] and As(III)/As ratio, while little change in major ion chemistry. The δD and δ(18)O are similar for the borehole and fracture waters, suggesting a same source of recharge from atmospheric precipitation. Results support a conceptual model invoking flow and sorption controls on groundwater [As] in fractured bedrock aquifers whereby oxygen infiltration promotes the oxidation of As-bearing sulfides at shallower depths in the oxic portion of the flow path releasing As and Fe; followed by Fe oxidation to form Fe oxyhydroxide particulates, which are transported in fractures and sorb As along the flow path until intercepted by boreholes. In the anoxic portions of the flow path, reductive dissolution of As-sorbed iron particulates could re-mobilize As. For exposure assessment, we recommend sampling of groundwater without filtration to obtain total As concentration in groundwater. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Connection adaption for control of networked mobile chaotic agents.

    Science.gov (United States)

    Zhou, Jie; Zou, Yong; Guan, Shuguang; Liu, Zonghua; Xiao, Gaoxi; Boccaletti, S

    2017-11-22

    In this paper, we propose a strategy for the control of mobile chaotic oscillators by adaptively rewiring connections between nearby agents with local information. In contrast to the dominant adaptive control schemes where coupling strength is adjusted continuously according to the states of the oscillators, our method does not request adaption of coupling strength. As the resulting interaction structure generated by this proposed strategy is strongly related to unidirectional chains, by investigating synchronization property of unidirectional chains, we reveal that there exists a certain coupling range in which the agents could be controlled regardless of the length of the chain. This feature enables the adaptive strategy to control the mobile oscillators regardless of their moving speed. Compared with existing adaptive control strategies for networked mobile agents, our proposed strategy is simpler for implementation where the resulting interaction networks are kept unweighted at all time.

  2. Controlled Delegation Protocol in Mobile RFID Networks

    Directory of Open Access Journals (Sweden)

    Yang MingHour

    2010-01-01

    Full Text Available To achieve off-line delegation for mobile readers, we propose a delegation protocol for mobile RFID allowing its readers access to specific tags through back-end server. That is to say, reader-tag mutual authentication can be performed without readers being connected to back-end server. Readers are also allowed off-line access to tags' data. Compared with other delegation protocols, our scheme uniquely enables back-end server to limit each reader's reading times during delegation. Even in a multireader situation, our protocol can limit reading times and reading time periods for each of them and therefore makes back-end server's delegation more flexible. Besides, our protocol can prevent authorized readers from transferring their authority to the unauthorized, declining invalid access to tags. Our scheme is proved viable and secure with GNY logic; it is against certain security threats, such as replay attacks, denial of service (DoS attacks, Man-in-the-Middle attacks, counterfeit tags, and breaches of location and data privacy. Also, the performance analysis of our protocol proves that current tags can afford the computation load required in this scheme.

  3. Determination of total arsenic and arsenic(III) in phosphate fertilizers by hydride generation atomic absorption spectrometry after ultrasound-assisted extraction based on a control acid media.

    Science.gov (United States)

    Rezende, Helen Cristine; Coelho, Nivia Maria Melo

    2014-01-01

    An ultrasound-assisted extraction procedure was developed for determination of inorganic arsenic (As) in phosphate fertilizer by hydride generation atomic absorption spectrometry. The variables that affect the hydride generation step were optimized, including the reducer, acid, sample flow rate, and concentrations of the acid and reducer. The determination of As(lll) was performed through the simple control of solution pH with a 0.5 M citric acid-sodium citrate buffer solution at pH 4.5, and total As was determined after a pre-reduction reaction with 1.0% (w/v) thiourea. Ultrasound-assisted acid extraction was performed, and the parameters sonication time and acid and Triton X-114 concentrations were optimized using a 23 factorial design and central composite design. LODs for As(lll) and total As were 0.029 and 0.022 microg/L, respectively. The accuracy of the method was confirmed with certified reference materials. The method was successfully applied in the determination of inorganic As in phosphate fertilizer samples.

  4. Controlled area for mobile medical X-ray equipment

    Energy Technology Data Exchange (ETDEWEB)

    Menzel, B; Taschner, P; Koenig, W [Staatliches Amt fuer Atomsicherheit und Strahlenschutz, Berlin (German Democratic Republic); Fuehr, K P; Kucharz, R [Rostock Univ. (German Democratic Republic). Radiologische Klinik

    1976-10-01

    On the basis of dose rate measurements the radiation protection situation during operation of mobile X-ray machines is described. According to these results, the controlled area has been definitely fixed by the National Board of Nuclear Safety and Radiation Protection with respect to the following fields of application: stomatology, mobile radiography of patients confined to bed as well as performing radiological examinations in the operating theatre.

  5. Palaeosol control on groundwater flow and pollutant distribution: the example of arsenic.

    Science.gov (United States)

    McArthur, John M; Nath, Bibhash; Banerjee, Dhiraj M; Purohit, R; Grassineau, N

    2011-02-15

    The consumption of groundwater polluted by arsenic (As) has a severe and adverse effect on human health, particularly where, as happens in parts of SE Asia, groundwater is supplied largely from fluvial/deltaic aquifers. The lateral distribution of the As-pollution in such aquifers is heterogeneous. The cause of the heterogeneity is obscure. The location and severity of the As-pollution is therefore difficult to predict, despite the importance of such predictions to the protection of consumer health, aquifer remediation, and aquifer development. To explain the heterogeneity, we mapped As-pollution in groundwater using 659 wells across 102 km(2) of West Bengal, and logged 43 boreholes, to reveal that the distribution of As-pollution is governed by subsurface sedimentology. Across 47 km(2) of contiguous palaeo-interfluve, we found that the shallow aquifer (channels, the palaeosol is absent, so invasion of the aquifer by As and dissolved organic matter can occur, so palaeo-channel groundwater is mostly polluted by As (>50 μg/L). The role of palaeosols and, in particular, the LGMP, has been overlooked as a control on groundwater flow and pollutant movement in deltaic and coastal aquifers worldwide. Models of pollutant infiltration in such environments must include the appreciation that, where the LGMP (or other palaeosols) are present, recharge moves downward in palaeo-channel regions that are separated by palaeo-interfluvial regions where vertical recharge to underlying aquifers cannot occur and where horizontal flow occurs above the LGMP and any aquifer it caps.

  6. Arsenic release during managed aquifer recharge (MAR)

    Science.gov (United States)

    Pichler, T.; Lazareva, O.; Druschel, G.

    2013-12-01

    The mobilization and addition of geogenic trace metals to groundwater is typically caused by anthropogenic perturbations of the physicochemical conditions in the aquifer. This can add dangerously high levels of toxins to groundwater, thus compromising its use as a source of drinking water. In several regions world-wide, aquifer storage and recovery (ASR), a form of managed aquifer recharge (MAR), faces the problem of arsenic release due to the injection of oxygenated storage water. To better understand this process we coupled geochemical reactive transport modeling to bench-scale leaching experiments to investigate and verify the mobilization of geogenic arsenic (As) under a range of redox conditions from an arsenic-rich pyrite bearing limestone aquifer in Central Florida. Modeling and experimental observations showed similar results and confirmed the following: (1) native groundwater and aquifer matrix, including pyrite, were in chemical equilibrium, thus preventing the release of As due to pyrite dissolution under ambient conditions; (2) mixing of oxygen-rich surface water with oxygen-depleted native groundwater changed the redox conditions and promoted the dissolution of pyrite, and (3) the behavior of As along a flow path was controlled by a complex series of interconnected reactions. This included the oxidative dissolution of pyrite and simultaneous sorption of As onto neo-formed hydrous ferric oxides (HFO), followed by the reductive dissolution of HFO and secondary release of adsorbed As under reducing conditions. Arsenic contamination of drinking water in these systems is thus controlled by the re-equilibration of the system to more reducing conditions rather than a purely oxidative process.

  7. FUZZY CONTROLLER FOR THE CONTROL OF THE MOBILE PLATFORM OF THE CORBYS ROBOTIC GAIT REHABILITATION SYSTEM

    Directory of Open Access Journals (Sweden)

    Maria Kyrarini

    2014-12-01

    Full Text Available In this paper, an inverse kinematics based control algorithm for the joystick control of the mobile platform of the novel mobile robot-assisted gait rehabilitation system CORBYS is presented. The mobile platform has four independently steered and driven wheels. Given the linear and angular velocities of the mobile platform, the inverse kinematics algorithm gives as its output the steering angle and the driving angular velocity of each of the four wheels. The paper is focused on the steering control of the platform for which a fuzzy logic controller is developed and implemented. The experimental results of the real-world steering of the platform are presented in the paper.

  8. Biological monitoring of arsenic exposure of gallium arsenide- and inorganic arsenic-exposed workers by determination of inorganic arsenic and its metabolites in urine and hair

    Energy Technology Data Exchange (ETDEWEB)

    Yamauchi, H.; Takahashi, K.; Mashiko, M.; Yamamura, Y. (St. Marianna Univ. School of Medicine, Kawasaki (Japan))

    1989-11-01

    In an attempt to establish a method for biological monitoring of inorganic arsenic exposure, the chemical species of arsenic were measured in the urine and hair of gallium arsenide (GaAs) plant and copper smelter workers. Determination of urinary inorganic arsenic concentration proved sensitive enough to monitor the low-level inorganic arsenic exposure of the GaAs plant workers. The urinary inorganic arsenic concentration in the copper smelter workers was far higher than that of a control group and was associated with high urinary concentrations of the inorganic arsenic metabolites, methylarsonic acid (MAA) and dimethylarsinic acid (DMAA). The results established a method for exposure level-dependent biological monitoring of inorganic arsenic exposure. Low-level exposures could be monitored only by determining urinary inorganic arsenic concentration. High-level exposures clearly produced an increased urinary inorganic arsenic concentration, with an increased sum of urinary concentrations of inorganic arsenic and its metabolites (inorganic arsenic + MAA + DMAA). The determination of urinary arsenobetaine proved to determine specifically the seafood-derived arsenic, allowing this arsenic to be distinguished clearly from the arsenic from occupational exposure. Monitoring arsenic exposure by determining the arsenic in the hair appeared to be of value only when used for environmental monitoring of arsenic contamination rather than for biological monitoring.

  9. Dynamic Modelling and Adaptive Traction Control for Mobile Robots

    Directory of Open Access Journals (Sweden)

    A. Albagul

    2004-09-01

    Full Text Available Mobile robots have received a great deal of research in recent years. A significant amount of research has been published in many aspects related to mobile robots. Most of the research is devoted to design and develop some control techniques for robot motion and path planning. A large number of researchers have used kinematic models to develop motion control strategy for mobile robots. Their argument and assumption that these models are valid if the robot has low speed, low acceleration and light load. However, dynamic modelling of mobile robots is very important as they are designed to travel at higher speed and perform heavy duty work. This paper presents and discusses a new approach to develop a dynamic model and control strategy for wheeled mobile robot which I modelled as a rigid body that roles on two wheels and a castor. The motion control strategy consists of two levels. The first level is dealing with the dynamic of the system and denoted as ‘Low’ level controller. The second level is developed to take care of path planning and trajectory generation.

  10. Learning feedforward controller for a mobile robot vehicle

    NARCIS (Netherlands)

    Starrenburg, J.G.; Starrenburg, J.G.; van Luenen, W.T.C.; van Luenen, W.T.C.; Oelen, W.; Oelen, W.; van Amerongen, J.

    1996-01-01

    This paper describes the design and realisation of an on-line learning posetracking controller for a three-wheeled mobile robot vehicle. The controller consists of two components. The first is a constant-gain feedback component, designed on the basis of a second-order model. The second is a learning

  11. Arsenic mobility in groundwater/surface water systems in carbonate-rich Pleistocene glacial drift aquifers (Michigan)

    International Nuclear Information System (INIS)

    Szramek, Kathryn; Walter, Lynn M.; McCall, Patti

    2004-01-01

    Within the Lower Peninsula of Michigan, groundwaters from the Marshall Formation (Mississippian) contain As derived from As-rich pyrites, often exceeding the World Heath Organization drinking water limit of 10 μg/L. Many Michigan watersheds, established on top of Pleistocene glacial drift derived from erosion of the underlying Marshall Formation, also have waters with elevated As. The Huron River watershed in southeastern Lower Michigan is a well characterized hydrogeochemical system of glacial drift deposits, proximate to the Marshall Fm. subcrop, which hosts carbonate-rich groundwaters, streams, and wetlands (fens), and well-developed soil profiles. Aqueous and solid phase geochemistry was determined for soils, soil waters, surface waters (streams and fens) and groundwaters from glacial drift aquifers to better understand the hydrogeologic and chemical controls on As mobility. Soil profiles established on the glacial drift exhibit enrichment in both Fe and As in the oxyhydroxide-rich zone of accumulation. The amounts of Fe and As present as oxyhydroxides are comparable to those reported from bulk Marshall Fm. core samples by previous workers. However, the As host in core samples is largely unaltered pyrite and arsenopyrite. This suggests that the transformation of Fe sulfides to Fe oxyhydroxides largely retains As and Fe at the oxidative weathering site. Groundwaters have the highest As values of all the waters sampled, and many were at or above the World Health limit. Most groundwaters are anaerobic, within the zones of Fe 3+ and As(V) reduction. Although reduction of Fe(III) oxyhydroxides is the probable source of As, there is no correlation between As and Fe concentrations. The As/Fe mole ratios in drift groundwaters are about an order of magnitude greater than those in soil profiles, suggesting that As is more mobile than Fe. This is consistent with the dominance of As(III) in these groundwaters and with the partitioning of Fe 2+ into carbonate cements. Soil

  12. Characterization of PCBs from computers and mobile phones, and the proposal of newly developed materials for substitution of gold, lead and arsenic.

    Science.gov (United States)

    Dervišević, Irma; Minić, Duško; Kamberović, Željko; Ćosović, Vladan; Ristić, Mirjana

    2013-06-01

    In this paper, we have analyzed parts of printed circuit board (PCB) and liquid crystal display (LCD) screens of mobile phones and computers, quantitative and qualitative chemical compositions of individual components, and complete PCBs were determined. Differential thermal analysis (DTA) and differential scanning calorimetry (DSC) methods were used to determine the temperatures of phase transformations, whereas qualitative and quantitative compositions of the samples were determined by X-ray fluorescence spectrometry (XRF), inductively coupled plasma optical emission spectrometry (ICP-OES), and scanning electron microscopy (SEM)-energy dispersive X-ray spectrometry (EDS) analyses. The microstructure of samples was studied by optical microscopy. Based on results of the analysis, a procedure for recycling PCBs is proposed. The emphasis was on the effects that can be achieved in the recycling process by extraction of some parts before the melting process. In addition, newly developed materials can be an adequate substitute for some of the dangerous and harmful materials, such as lead and arsenic are proposed, which is in accordance with the European Union (EU) Restriction of the use of certain hazardous substances (RoHS) directive as well as some alternative materials for use in the electronics industry instead of gold and gold alloys.

  13. Quantifying Reactive Transport Processes Governing Arsenic Mobility after Injection of Reactive Organic Carbon into a Bengal Delta Aquifer.

    Science.gov (United States)

    Rawson, Joey; Siade, Adam; Sun, Jing; Neidhardt, Harald; Berg, Michael; Prommer, Henning

    2017-08-01

    Over the last few decades, significant progress has been made to characterize the extent, severity, and underlying geochemical processes of groundwater arsenic (As) pollution in S/SE Asia. However, comparably little effort has been made to merge the findings into frameworks that allow for a process-based quantitative analysis of observed As behavior and for predictions of its long-term fate. This study developed field-scale numerical modeling approaches to represent the hydrochemical processes associated with an in situ field injection of reactive organic carbon, including the reductive dissolution and transformation of ferric iron (Fe) oxides and the concomitant release of sorbed As. We employed data from a sucrose injection experiment in the Bengal Delta Plain to guide our model development and to constrain the model parametrization. Our modeling results illustrate that the temporary pH decrease associated with the sucrose transformation and mineralization caused pronounced, temporary shifts in the As partitioning between aqueous and sorbed phases. The results also suggest that while the reductive dissolution of Fe(III) oxides reduced the number of sorption sites, a significant fraction of the released As was rapidly scavenged through coprecipitation with neo-formed magnetite. These secondary reactions can explain the disparity between the observed Fe and As behavior.

  14. Rhizosphere colonization and arsenic translocation in sunflower (Helianthus annuus L.) by arsenate reducing Alcaligenes sp. strain Dhal-L.

    Science.gov (United States)

    Cavalca, Lucia; Corsini, Anna; Bachate, Sachin Prabhakar; Andreoni, Vincenza

    2013-10-01

    In the present study, six arsenic-resistant strains previously isolated were tested for their plant growth promoting characteristics and heavy metal resistance, in order to choose one model strain as an inoculum for sunflower plants in pot experiments. The aim was to investigate the effect of arsenic-resistant strain on sunflower growth and on arsenic uptake from arsenic contaminated soil. Based on plant growth promoting characteristics and heavy metal resistance, Alcaligenes sp. strain Dhal-L was chosen as an inoculum. Beside the ability to reduce arsenate to arsenite via an Ars operon, the strain exhibited 1-amino-cyclopropane-1-carboxylic acid deaminase activity and it was also able to produce siderophore and indole acetic acid. Pot experiments were conducted with an agricultural soil contaminated with arsenic (214 mg kg⁻¹). A real time PCR method was set up based on the quantification of ACR3(2) type of arsenite efflux pump carried by Alcaligenes sp. strain Dhal-L, in order to monitor presence and colonisation of the strain in the bulk and rhizospheric soil. As a result of strain inoculation, arsenic uptake by plants was increased by 53 %, whereas ACR3(2) gene copy number in rhizospheric soil was 100 times higher in inoculated than in control pots, indicating the colonisation of strain. The results indicated that the presence of arsenate reducing strains in the rhizosphere of sunflower influences arsenic mobilization and promotes arsenic uptake by plant.

  15. Possible Links Among Iron Reduction, Silicate Weathering, and Arsenic Mobility in the Mississippi River Alluvial Aquifer in Louisiana

    Science.gov (United States)

    Borrok, D. M.; Lenz, R. M.; Jennings, J. E.; Gentry, M. L.; Vinson, D. S.

    2017-12-01

    The Lower Mississippi River Alluvial Aquifer (LMRAA) is a critical groundwater resource for Arkansas, Mississippi, and Louisiana. Part of the aquifer in Louisiana contains waters rich in Na, HCO3, Fe, and As. We hypothesize that CO2 generated from dissimilatory iron reduction (DIR) within the aquifer acts to weather Na-bearing silicates, contributing Na and HCO3, which may influence the mobility of As. We examined the geochemistry of the aquifer using historical and new data collected from the Louisiana Department of Environmental Quality (LDEQ). Major and trace element data were collected from about 25 wells in the LMRAA in Louisiana every three years from 2001-2016. Samples collected in 2016 were additionally analyzed for water isotopes and the δ13C of dissolved inorganic carbon (DIC). Results suggest that groundwater in the LMRAA can be broken into two broad categories, (1) water with a molar Na/Cl ratio near 1 and/or high salinity, and (2) water with excess Na (i.e., the molar concentration of Na is greater than that of Cl) that is often higher in alkalinity (up to 616 mg/L as CaCO3), Fe (up to 21 mg/L), and sometimes As (up to 67 µg/L). Concentrations of dissolved Fe were found to correlate, at least weakly, with alkalinity and Na excess. Six of the approximately 25 wells historically sampled consistently had concentrations of As >10 µg/L. These locations generally correspond with groundwater characterized by higher Fe, alkalinity, and Na-excess. Initial results for δD and δ18O suggest that more isotopically depleted waters are sourced from the Mississippi River, whereas local precipitation recharges the aquifer farther from the river (δ18O ranged from -7.5‰ to -3.5‰). Part of the δ13C-DIC variation (-17.4‰ to -10.6‰) is consistent with pH modification (6.5-7.7) along differing horizontal and vertical flow paths in the aquifer. This geochemistry appears to be controlled in part by geology. Areas nearer to the current Mississippi River where

  16. Autonomous Visual Control of a Mobile Robot

    National Research Council Canada - National Science Library

    Blackburn, Michael

    1994-01-01

    .... We propose that efficient and extensible solutions to the target acquisition and maintenance problem may be found when the machine sensor-effector control algorithms emulate the mechanisms employed...

  17. Intelligent control and cooperation for mobile robots

    Science.gov (United States)

    Stingu, Petru Emanuel

    The topic discussed in this work addresses the current research being conducted at the Automation & Robotics Research Institute in the areas of UAV quadrotor control and heterogenous multi-vehicle cooperation. Autonomy can be successfully achieved by a robot under the following conditions: the robot has to be able to acquire knowledge about the environment and itself, and it also has to be able to reason under uncertainty. The control system must react quickly to immediate challenges, but also has to slowly adapt and improve based on accumulated knowledge. The major contribution of this work is the transfer of the ADP algorithms from the purely theoretical environment to the complex real-world robotic platforms that work in real-time and in uncontrolled environments. Many solutions are adopted from those present in nature because they have been proven to be close to optimal in very different settings. For the control of a single platform, reinforcement learning algorithms are used to design suboptimal controllers for a class of complex systems that can be conceptually split in local loops with simpler dynamics and relatively weak coupling to the rest of the system. Optimality is enforced by having a global critic but the curse of dimensionality is avoided by using local actors and intelligent pre-processing of the information used for learning the optimal controllers. The system model is used for constructing the structure of the control system, but on top of that the adaptive neural networks that form the actors use the knowledge acquired during normal operation to get closer to optimal control. In real-world experiments, efficient learning is a strong requirement for success. This is accomplished by using an approximation of the system model to focus the learning for equivalent configurations of the state space. Due to the availability of only local data for training, neural networks with local activation functions are implemented. For the control of a formation

  18. The environmental geochemistry of Arsenic – An overview

    Science.gov (United States)

    Bowell, Robert J.; Alpers, Charles N.; Jamieson, Heather E.; Nordstrom, D. Kirk; Majzlan, Juraj

    2014-01-01

    Arsenic is one of the most prevalent toxic elements in the environment. The toxicity, mobility, and fate of arsenic in the environment are determined by a complex series of controls dependent on mineralogy, chemical speciation, and biological processes. The element was first described by Theophrastus in 300 B.C. and named arsenikon (also arrhenicon; Caley and Richards 1956) referring to its “potent” nature, although it was originally considered an alternative form of sulfur (Boyle and Jonasson 1973). Arsenikon is believed to be derived from the earlier Persian, zarnik (online etymology dictionary, http://www.etymonline.com/index.php?term=arsenic). It was not until the thirteenth century that an alchemist, Albertus Magnus, was able to isolate the element from orpiment, an arsenic sulfide (As2S3). The complex chemistry required to do this led to arsenic being considered a “bastard metal” or what we now call a “metalloid,” having properties of both metals and non-metals. As a chemical element, arsenic is widely distributed in nature and can be concentrated in many different ways. In the Earth’s crust, arsenic is concentrated by magmatic and hydrothermal processes and has been used as a “pathfinder” for metallic ore deposits, particularly gold, tin, copper, and tungsten (Boyle and Jonasson 1973; Cohen and Bowell 2014). It has for centuries been considered a potent toxin, is a common poison in actual and fictional crimes, and has led to significant impacts on human health in many areas of the world (Cullen 2008; Wharton 2010).

  19. Wireless Sensor/Actuator Network Design for Mobile Control Applications

    Directory of Open Access Journals (Sweden)

    Youxian Sung

    2007-10-01

    Full Text Available Wireless sensor/actuator networks (WSANs are emerging as a new generationof sensor networks. Serving as the backbone of control applications, WSANs will enablean unprecedented degree of distributed and mobile control. However, the unreliability ofwireless communications and the real-time requirements of control applications raise greatchallenges for WSAN design. With emphasis on the reliability issue, this paper presents anapplication-level design methodology for WSANs in mobile control applications. Thesolution is generic in that it is independent of the underlying platforms, environment,control system models, and controller design. To capture the link quality characteristics interms of packet loss rate, experiments are conducted on a real WSAN system. From theexperimental observations, a simple yet efficient method is proposed to deal withunpredictable packet loss on actuator nodes. Trace-based simulations give promisingresults, which demonstrate the effectiveness of the proposed approach.

  20. DEVELOPMENT OF TRAJECTORY CONTROL SYSTEM FOR THE OMNIDIRECTIONAL MOBILE ROBOT

    Directory of Open Access Journals (Sweden)

    Y. A. Kapitanyuk

    2014-03-01

    Full Text Available The article deals with a trajectory control system development for the omnidirectional mobile robot. This kind of robots gives the possibility to control separately each degree of freedom due to special design of the wheels, which greatly facilitates the solution of the spatial control tasks and makes it possible to focus directly on the development of algorithms. Control law synthesis is based on kinematic model of a solid body on a plane. Desired trajectory is defined as a smooth implicit function in a fixed coordinate system. Procedure of control design is represented by using a differential-geometric method of nonlinear transformation of the original model to the task-oriented form, which describes the longitudinal motion along a trajectory and orthogonal deviation. Proportional controllers with direct compensation of nonlinear terms are synthesized for the transformed model. Main results are represented by nonlinear control algorithms and experimental data. Practical implementation of considered control laws for the Robotino mobile robot by Festo Didactics Company is done for illustration of this approach workability. The cases of straight line motion and movement along a circle are represented as desirable trajectories, and the majority of practical tasks for mobile robots control can be implemented by their combination.

  1. Arsenic removal from contaminated brackish sea water by sorption onto Al hydroxides and Fe phases mobilized by land-use.

    Science.gov (United States)

    Yu, Changxun; Peltola, Pasi; Nystrand, Miriam I; Virtasalo, Joonas J; Österholm, Peter; Ojala, Antti E K; Hogmalm, Johan K; Åström, Mats E

    2016-01-15

    This study examines the spatial and temporal distribution patterns of arsenic (As) in solid and aqueous materials along the mixing zone of an estuary, located in the south-eastern part of the Bothnian Bay and fed by a creek running through an acid sulfate (AS) soil landscape. The concentrations of As in solution form (<1 kDa) increase steadily from the creek mouth to the outer estuary, suggesting that inflowing seawater, rather than AS soil, is the major As source in the estuary. In sediments at the outer estuary, As was accumulated and diagenetically cycled in the surficial layers, as throughout much of the Bothnian Bay. In contrast, in sediments in the inner estuary, As concentrations and accumulation rates showed systematical peaks at greater depths. These peaks were overall consistent with the temporal trend of past As discharges from the Rönnskär smelter and the accompanied As concentrations in past sea-water of the Bothnian Bay, pointing to a connection between the historical smelter activities and the sediment-bound As in the inner estuary. However, the concentrations and accumulation rates of As peaked at depths where the smelter activities had already declined, but a large increase in the deposition of Al hydroxides and Fe phases occurred in response to intensified land-use in the mid 1960's and early 1970's. This correspondence suggests that, apart from the inflowing As-contaminated seawater, capture by Al hydroxides, Fe hydroxides and Fe-organic complexes is another important factor for As deposition in the inner estuary. After accumulating in the sediment, the solid-phase As was partly remobilized, as reflected by increased pore-water As concentrations, a process favored by As(V) reduction and high concentrations of dissolved organic matter. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Fuzzy Behaviors for Control of Mobile Robots

    Directory of Open Access Journals (Sweden)

    Saleh Zein-Sabatto

    2003-02-01

    Full Text Available In this research work, an RWI B-14 robot has been used as the development platform to embody some basic behaviors that can be combined to build more complex robotics behaviors. Emergency, avoid-obstacle, left wall- following, right wall-following, and move-to-point behaviors have been designed and embodied as basic robot behaviors. The basic behaviors developed in this research are designed based on fuzzy control technique and are integrated and coordinated to from complex robotics system. More behaviors can be added into the system as needed. A robot task can be defined by the user and executed by the intelligent robot control system. Testing results showed that fuzzy behaviors made the robot move intelligently and adapt to changes in its environment.

  3. Mobile Interfaces for Building Control Surveyors

    OpenAIRE

    Chmielewski , Jacek; Walczak , Krzysztof; Wiza , Wojciech

    2010-01-01

    International audience; The problem of integrating heterogeneous back-end platforms used in public administration has been widely addressed in a number of research and development projects. In such a complex and heterogeneous environment, application of the SOA paradigm can be particularly beneficial. However, in some application domains - such as the Building Control Administration - there is an additional requirement: integration of heterogeneous front-end platforms - including access throu...

  4. High p-type doping, mobility, and photocarrier lifetime in arsenic-doped CdTe single crystals

    Science.gov (United States)

    Nagaoka, Akira; Kuciauskas, Darius; McCoy, Jedidiah; Scarpulla, Michael A.

    2018-05-01

    Group-V element doping is promising for simultaneously maximizing the hole concentration and minority carrier lifetime in CdTe for thin film solar cells, but there are roadblocks concerning point defects including the possibility of self-compensation by AX metastability. Herein, we report on doping, lifetime, and mobility of CdTe single crystals doped with As between 1016 and 1020 cm-3 grown from the Cd solvent by the travelling heater method. Evidence consistent with AX instability as a major contributor to compensation in samples doped below 1017 cm-3 is presented, while for higher-doped samples, precipitation of a second phase on planar structural defects is also observed and may explain spatial variation in properties such as lifetime. Rapid cooling after crystal growth increases doping efficiency and mobility for times up to 20-30 days at room temperature with the highest efficiencies observed close to 45% and a hole mobility of 70 cm2/Vs at room temperature. A doping limit in the low 1017/cm3 range is observed for samples quenched at 200-300 °C/h. Bulk minority carrier lifetimes exceeding 20 ns are observed for samples doped near 1016 cm-3 relaxed in the dark and for unintentionally doped samples, while a lifetime of nearly 5 ns is observed for 1018 cm-3 As doping. These results help us to establish limits on properties expected for group-V doped CdTe polycrystalline thin films for use in photovoltaics.

  5. Tracking control of mobile robots: a case study in backstepping

    NARCIS (Netherlands)

    Jiang, Zhong-Ping; Nijmeijer, Henk

    1997-01-01

    A tracking control methodology via time-varying state feedback based on the backstepping technique is proposed for both a kinematic and simplified dynamic model of a two-degrees-of-freedom mobile robot. We first address the local tracking problem where initial tracking errors are sufficiently small.

  6. Remote-controlled vision-guided mobile robot system

    Science.gov (United States)

    Ande, Raymond; Samu, Tayib; Hall, Ernest L.

    1997-09-01

    Automated guided vehicles (AGVs) have many potential applications in manufacturing, medicine, space and defense. The purpose of this paper is to describe exploratory research on the design of the remote controlled emergency stop and vision systems for an autonomous mobile robot. The remote control provides human supervision and emergency stop capabilities for the autonomous vehicle. The vision guidance provides automatic operation. A mobile robot test-bed has been constructed using a golf cart base. The mobile robot (Bearcat) was built for the Association for Unmanned Vehicle Systems (AUVS) 1997 competition. The mobile robot has full speed control with guidance provided by a vision system and an obstacle avoidance system using ultrasonic sensors systems. Vision guidance is accomplished using two CCD cameras with zoom lenses. The vision data is processed by a high speed tracking device, communicating with the computer the X, Y coordinates of blobs along the lane markers. The system also has three emergency stop switches and a remote controlled emergency stop switch that can disable the traction motor and set the brake. Testing of these systems has been done in the lab as well as on an outside test track with positive results that show that at five mph the vehicle can follow a line and at the same time avoid obstacles.

  7. Geomicrobial interactions with arsenic and antimony

    Science.gov (United States)

    Oremland, Ronald S.

    2015-01-01

    Although arsenic and antimony are generally toxic to life, some microorganisms exist that can metabolize certain forms of these elements. Some can use arsenite or stibnite as potential or sole energy sources, whereas others can use aresenate and antimonite (as was discovered only recently) as terminal electron acceptors. Still other microbes can metabolize arsenic and antimony compounds to detoxify them. These reactions are important from a geomicrobial standpoint because they indicate that a number of microbes contribute to arsenic and antimony mobilization or immobilization in the environment and play a role in arsenic and antimony cycles. Recent reviews include five on prokaryotes and arsenic metabolism, a review with an arsenic perspective on biomining, and a series on environmental antimony, including one about antimony and its interaction with microbiota.

  8. RoCoMAR: Robots’ Controllable Mobility Aided Routing and Relay Architecture for Mobile Sensor Networks

    Directory of Open Access Journals (Sweden)

    Seokhoon Yoon

    2013-07-01

    Full Text Available In a practical deployment, mobile sensor network (MSN suffers from a low performance due to high node mobility, time-varying wireless channel properties, and obstacles between communicating nodes. In order to tackle the problem of low network performance and provide a desired end-to-end data transfer quality, in this paper we propose a novel ad hoc routing and relaying architecture, namely RoCoMAR (Robots’ Controllable Mobility Aided Routing that uses robotic nodes’ controllable mobility. RoCoMAR repeatedly performs link reinforcement process with the objective of maximizing the network throughput, in which the link with the lowest quality on the path is identified and replaced with high quality links by placing a robotic node as a relay at an optimal position. The robotic node resigns as a relay if the objective is achieved or no more gain can be obtained with a new relay. Once placed as a relay, the robotic node performs adaptive link maintenance by adjusting its position according to the movements of regular nodes. The simulation results show that RoCoMAR outperforms existing ad hoc routing protocols for MSN in terms of network throughput and end-to-end delay.

  9. RoCoMAR: Robots' Controllable Mobility Aided Routing and Relay Architecture for Mobile Sensor Networks

    Science.gov (United States)

    Van Le, Duc; Oh, Hoon; Yoon, Seokhoon

    2013-01-01

    In a practical deployment, mobile sensor network (MSN) suffers from a low performance due to high node mobility, time-varying wireless channel properties, and obstacles between communicating nodes. In order to tackle the problem of low network performance and provide a desired end-to-end data transfer quality, in this paper we propose a novel ad hoc routing and relaying architecture, namely RoCoMAR (Robots' Controllable Mobility Aided Routing) that uses robotic nodes' controllable mobility. RoCoMAR repeatedly performs link reinforcement process with the objective of maximizing the network throughput, in which the link with the lowest quality on the path is identified and replaced with high quality links by placing a robotic node as a relay at an optimal position. The robotic node resigns as a relay if the objective is achieved or no more gain can be obtained with a new relay. Once placed as a relay, the robotic node performs adaptive link maintenance by adjusting its position according to the movements of regular nodes. The simulation results show that RoCoMAR outperforms existing ad hoc routing protocols for MSN in terms of network throughput and end-to-end delay. PMID:23881134

  10. Successful Control of Disseminated Intravascular Coagulation by Recombinant Thrombomodulin during Arsenic Trioxide Treatment in Relapsed Patient with Acute Promyelocytic Leukemia

    Directory of Open Access Journals (Sweden)

    Motohiro Shindo

    2012-01-01

    Full Text Available Disseminated intravascular coagulation (DIC frequently occurs in patients with acute promyelocytic leukemia (APL. With the induction of therapy in APL using all-trans retinoic acid (ATRA, DIC can be controlled in most cases as ATRA usually shows immediate improvement of the APL. However, arsenic trioxide (ATO which has been used for the treatment of relapse in APL patients has shown to take time to suppress APL cells, therefore the control of DIC in APL with ATO treatment is a major problem. Recently, the recombinant soluble thrombomodulin fragment has received a lot of attention as the novel drug for the treatment of DIC with high efficacy. Here, we present a relapsed patient with APL in whom DIC was successfully and safely controlled by rTM during treatment with ATO.

  11. Sequestration of arsenic in ombrotrophic peatlands

    Science.gov (United States)

    Rothwell, James; Hudson-Edwards, Karen; Taylor, Kevin; Polya, David; Evans, Martin; Allott, Tim

    2014-05-01

    Peatlands can be important stores of arsenic but we are lacking spectroscopic evidence of the sequestration pathways of this toxic metalloid in peatland environments. This study reports on the solid-phase speciation of anthropogenically-derived arsenic in atmospherically contaminated peat from the Peak District National Park (UK). Surface and sub-surface peat samples were analysed by synchrotron X-ray absorption spectroscopy on B18 beamline at Diamond Light Source (UK). The results suggest that there are contrasting arsenic sequestration mechanisms in the peat. The bulk arsenic speciation results, in combination with strong arsenic-iron correlations at the surface, suggest that iron (hydr)oxides are key phases for the immobilisation of arsenic at the peat surface. In contrast, the deeper peat samples are dominated by arsenic sulphides (arsenopyrite, realgar and orpiment). Given that these peats receive inputs solely from the atmosphere, the presence of these sulphide phases suggests an in-situ authigenic formation. Redox oscillations in the peat due to a fluctuating water table and an abundant store of legacy sulphur from historic acid rain inputs may favour the precipitation of arsenic sequestering sulphides in sub-surface horizons. Oxidation-induced loss of these arsenic sequestering sulphur species by water table drawdown has important implications for the mobility of arsenic and the quality of waters draining peatlands.

  12. Understanding Arsenic Dynamics in Agronomic Systems to ...

    Science.gov (United States)

    This review is on arsenic in agronomic systems, and covers processes that influence the entry of arsenic into the human food supply. The scope is from sources of arsenic (natural and anthropogenic) in soils, biogeochemical and rhizosphere processes that control arsenic speciation and availability, through to mechanisms of uptake by crop plants and potential mitigation strategies. This review makes a case for taking steps to prevent or limit crop uptake of arsenic, wherever possible, and to work toward a long-term solution to the presence of arsenic in agronomic systems. The past two decades have seen important advances in our understanding of how biogeochemical and physiological processes influence human exposure to soil arsenic, and thus must now prompt an informed reconsideration and unification of regulations to protect the quality of agricultural and residential soils. Consumption of staple foods such as rice, beverages such as apple juice, or vegetables grown in historically arsenic-contaminated soils is now recognized as a tangible route of arsenic exposure that, in many cases, is more significant than exposure from drinking water. Understanding the sources of arsenic to crop plants and the factors that influence them is key to reducing exposure now and preventing exposure in future. In addition to the abundant natural sources of arsenic, there are a large number of industrial and agricultural sources of arsenic to the soil; from mining wastes, coal fly

  13. High p-Type Doping, Mobility, and Photocarrier Lifetime in Arsenic-Doped CdTe Single Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kuciauskas, Darius [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Nagaoka, Akira [Kyoto University; University of Utah; McCoy, Jedidiah [Washington State University; Scarpulla, Michael A. [University of Utah

    2018-05-08

    Group-V element doping is promising for simultaneously maximizing the hole concentration and minority carrier lifetime in CdTe for thin film solar cells, but there are roadblocks concerning point defects including the possibility of self-compensation by AX metastability. Herein, we report on doping, lifetime, and mobility of CdTe single crystals doped with As between 10^16 and 10^20 cm-3 grown from the Cd solvent by the travelling heater method. Evidence consistent with AX instability as a major contributor to compensation in samples doped below 10^17 cm-3 is presented, while for higher-doped samples, precipitation of a second phase on planar structural defects is also observed and may explain spatial variation in properties such as lifetime. Rapid cooling after crystal growth increases doping efficiency and mobility for times up to 20-30 days at room temperature with the highest efficiencies observed close to 45% and a hole mobility of 70 cm2/Vs at room temperature. A doping limit in the low 10^17/cm3 range is observed for samples quenched at 200-300 degrees C/h. Bulk minority carrier lifetimes exceeding 20 ns are observed for samples doped near 10^16 cm-3 relaxed in the dark and for unintentionally doped samples, while a lifetime of nearly 5 ns is observed for 10^18 cm-3 As doping. These results help us to establish limits on properties expected for group-V doped CdTe polycrystalline thin films for use in photovoltaics.

  14. A Phytoremediation Strategy for Arsenic

    Energy Technology Data Exchange (ETDEWEB)

    Meagher, Richard B.

    2005-06-01

    A Phytoremediation Strategy for Arsenic Progress Report May, 2005 Richard B. Meagher Principal Investigator Arsenic pollution affects the health of several hundred millions of people world wide, and an estimated 10 million Americans have unsafe levels of arsenic in their drinking water. However, few environmentally sound remedies for cleaning up arsenic contaminated soil and water have been proposed. Phytoremediation, the use of plants to extract and sequester environmental pollutants, is one new technology that offers an ecologically sound solution to a devastating problem. We propose that it is less disruptive to the environment to harvest and dispose of several thousand pounds per acre of contaminated aboveground plant material, than to excavate and dispose of 1 to 5 million pounds of contaminated soil per acre (assumes contamination runs 3 ft deep). Our objective is to develop a genetics-based phytoremediation strategy for arsenic removal that can be used in any plant species. This strategy requires the enhanced expression of several transgenes from diverse sources. Our working hypothesis is that organ-specific expression of several genes controlling the transport, electrochemical state, and binding of arsenic will result in the efficient extraction and hyperaccumulation of arsenic into aboveground plant tissues. This hypothesis is supported by theoretical arguments and strong preliminary data. We proposed six Specific Aims focused on testing and developing this arsenic phytoremediation strategy. During the first 18 months of the grant we made significant progress on five Specific Aims and began work on the sixth as summarized below. Specific Aim 1: Enhance plant arsenic resistance and greatly expand sinks for arsenite by expressing elevated levels of thiol-rich, arsenic-binding peptides. Hyperaccumulation of arsenic depends upon making plants that are both highly tolerant to arsenic and that have the capacity to store large amounts of arsenic aboveground

  15. The Association of Arsenic Exposure and Metabolism With Type 1 and Type 2 Diabetes in Youth: The SEARCH Case-Control Study.

    Science.gov (United States)

    Grau-Pérez, Maria; Kuo, Chin-Chi; Spratlen, Miranda; Thayer, Kristina A; Mendez, Michelle A; Hamman, Richard F; Dabelea, Dana; Adgate, John L; Knowler, William C; Bell, Ronny A; Miller, Frederick W; Liese, Angela D; Zhang, Chongben; Douillet, Christelle; Drobná, Zuzana; Mayer-Davis, Elizabeth J; Styblo, Miroslav; Navas-Acien, Ana

    2017-01-01

    Little is known about arsenic and diabetes in youth. We examined the association of arsenic with type 1 and type 2 diabetes in the SEARCH for Diabetes in Youth Case-Control (SEARCH-CC) study. Because one-carbon metabolism can influence arsenic metabolism, we also evaluated the potential interaction of folate and vitamin B12 with arsenic metabolism on the odds of diabetes. Six hundred eighty-eight participants iAs], monomethylated arsenic [MMA], dimethylated arsenic [DMA]), and one-carbon metabolism biomarkers (folate and vitamin B12) were measured in plasma. We used the sum of iAs, MMA, and DMA (∑As) and the individual species as biomarkers of arsenic concentrations and the relative proportions of the species over their sum (iAs%, MMA%, DMA%) as biomarkers of arsenic metabolism. Median ∑As, iAs%, MMA%, and DMA% were 83.1 ng/L, 63.4%, 10.3%, and 25.2%, respectively. ∑As was not associated with either type of diabetes. The fully adjusted odds ratios (95% CI), rescaled to compare a difference in levels corresponding to the interquartile range of iAs%, MMA%, and DMA%, were 0.68 (0.50-0.91), 1.33 (1.02-1.74), and 1.28 (1.01-1.63), respectively, for type 1 diabetes and 0.82 (0.48-1.39), 1.09 (0.65-1.82), and 1.17 (0.77-1.77), respectively, for type 2 diabetes. In interaction analysis, the odds ratio of type 1 diabetes by MMA% was 1.80 (1.25-2.58) and 0.98 (0.70-1.38) for participants with plasma folate levels above and below the median (P for interaction = 0.02), respectively. Low iAs% versus high MMA% and DMA% was associated with a higher odds of type 1 diabetes, with a potential interaction by folate levels. These data support further research on the role of arsenic metabolism in type 1 diabetes, including the interplay with one-carbon metabolism biomarkers. © 2017 by the American Diabetes Association.

  16. Arsenic removal from contaminated groundwater by membrane-integrated hybrid plant: optimization and control using Visual Basic platform.

    Science.gov (United States)

    Chakrabortty, S; Sen, M; Pal, P

    2014-03-01

    A simulation software (ARRPA) has been developed in Microsoft Visual Basic platform for optimization and control of a novel membrane-integrated arsenic separation plant in the backdrop of absence of such software. The user-friendly, menu-driven software is based on a dynamic linearized mathematical model, developed for the hybrid treatment scheme. The model captures the chemical kinetics in the pre-treating chemical reactor and the separation and transport phenomena involved in nanofiltration. The software has been validated through extensive experimental investigations. The agreement between the outputs from computer simulation program and the experimental findings are excellent and consistent under varying operating conditions reflecting high degree of accuracy and reliability of the software. High values of the overall correlation coefficient (R (2) = 0.989) and Willmott d-index (0.989) are indicators of the capability of the software in analyzing performance of the plant. The software permits pre-analysis, manipulation of input data, helps in optimization and exhibits performance of an integrated plant visually on a graphical platform. Performance analysis of the whole system as well as the individual units is possible using the tool. The software first of its kind in its domain and in the well-known Microsoft Excel environment is likely to be very useful in successful design, optimization and operation of an advanced hybrid treatment plant for removal of arsenic from contaminated groundwater.

  17. An iterative learning controller for nonholonomic mobile robots

    International Nuclear Information System (INIS)

    Oriolo, G.; Panzieri, S.; Ulivi, G.

    1998-01-01

    The authors present an iterative learning controller that applies to nonholonomic mobile robots, as well as other systems that can be put in chained form. The learning algorithm exploits the fact that chained-form. The learning algorithm exploits the fact that chained-form systems are linear under piecewise-constant inputs. The proposed control scheme requires the execution of a small number of experiments to drive the system to the desired state in finite time, with nice convergence and robustness properties with respect to modeling inaccuracies as well as disturbances. To avoid the necessity of exactly reinitializing the system at each iteration, the basic method is modified so as to obtain a cyclic controller, by which the system is cyclically steered through an arbitrary sequence of states. As a case study, a carlike mobile robot is considered. Both simulation and experimental results are reported to show the performance of the method

  18. Fuzzy Logic Supervised Teleoperation Control for Mobile Robot

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The supervised teleoperation control is presented for a mobile robot to implement the tasks by using fuzzy logic. The teleoperation control system includes joystick based user interaction mechanism, the high level instruction set and fuzzy logic behaviors integrated in a supervised autonomy teleoperation control system for indoor navigation. These behaviors include left wall following, right wall following, turn left, turn right, left obstacle avoidance, right obstacle avoidance and corridor following based on ultrasonic range finders data. The robot compares the instructive high level command from the operator and relays back a suggestive signal back to the operator in case of mismatch between environment and instructive command. This strategy relieves the operator's cognitive burden, handle unforeseen situations and uncertainties of environment autonomously. The effectiveness of the proposed method for navigation in an unstructured environment is verified by experiments conducted on a mobile robot equipped with only ultrasonic range finders for environment sensing.

  19. Both Phosphorus Fertilizers and Indigenous Bacteria Enhance Arsenic Release into Groundwater in Arsenic-Contaminated Aquifers.

    Science.gov (United States)

    Lin, Tzu-Yu; Wei, Chia-Cheng; Huang, Chi-Wei; Chang, Chun-Han; Hsu, Fu-Lan; Liao, Vivian Hsiu-Chuan

    2016-03-23

    Arsenic (As) is a human carcinogen, and arsenic contamination in groundwater is a worldwide public health concern. Arsenic-affected areas are found in many places but are reported mostly in agricultural farmlands, yet the interaction of fertilizers, microorganisms, and arsenic mobilization in arsenic-contaminated aquifers remains uncharacterized. This study investigates the effects of fertilizers and bacteria on the mobilization of arsenic in two arsenic-contaminated aquifers. We performed microcosm experiments using arsenic-contaminated sediments and amended with inorganic nitrogenous or phosphorus fertilizers for 1 and 4 months under aerobic and anaerobic conditions. The results show that microcosms amended with 100 mg/L phosphorus fertilizers (dipotassium phosphate), but not nitrogenous fertilizers (ammonium sulfate), significantly increase aqueous As(III) release in arsenic-contaminated sediments under anaerobic condition. We also show that concentrations of iron, manganese, potassium, sodium, calcium, and magnesium are increased in the aqueous phase and that the addition of dipotassium phosphate causes a further increase in aqueous iron, potassium, and sodium, suggesting that multiple metal elements may take part in the arsenic release process. Furthermore, microbial analysis indicates that the dominant microbial phylum is shifted from α-proteobacteria to β- and γ-proteobacteria when the As(III) is increased and phosphate is added in the aquifer. Our results provide evidence that both phosphorus fertilizers and microorganisms can mediate the release of arsenic to groundwater in arsenic-contaminated sediments under anaerobic condition. Our study suggests that agricultural activity such as the use of fertilizers and monitoring phosphate concentration in groundwater should be taken into consideration for the management of arsenic in groundwater.

  20. Inorganic Arsenic and Basal Cell Carcinoma in Areas of Hungary, Romania, and Slovakia: A Case–Control Study

    Science.gov (United States)

    Leonardi, Giovanni; Vahter, Marie; Clemens, Felicity; Goessler, Walter; Gurzau, Eugen; Hemminki, Kari; Hough, Rupert; Koppova, Kvetoslava; Kumar, Rajiv; Rudnai, Peter; Surdu, Simona

    2012-01-01

    Background: Inorganic arsenic (iAs) is a potent carcinogen, but there is a lack of information about cancer risk for concentrations iAs exposure iAs metabolism. Methods: The Arsenic Health Risk Assessment and Molecular Epidemiology (ASHRAM) study, a case–control study, was conducted in areas of Hungary, Romania, and Slovakia with reported presence of iAs in groundwater. Consecutively diagnosed cases of basal cell carcinoma (BCC) of the skin were histologically confirmed; controls were general surgery, orthopedic, and trauma patients who were frequency matched to cases by age, sex, and area of residence. Exposure indices were constructed based on information on iAs intake over the lifetime of participants. iAs metabolism status was classified based on urinary concentrations of methylarsonic acid (MA) and dimethylarsinic acid (DMA). Associations were estimated by multivariable logistic regression. Results: A total of 529 cases with BCC and 540 controls were recruited for the study. BCC was positively associated with three indices of iAs exposure: peak daily iAs dose rate, cumulative iAs dose, and lifetime average water iAs concentration. The adjusted odds ratio per 10-μg/L increase in average lifetime water iAs concentration was 1.18 (95% confidence interval: 1.08, 1.28). The estimated effect of iAs on cancer was stronger in participants with urinary markers indicating incomplete metabolism of iAs: higher percentage of MA in urine or a lower percentage of DMA. Conclusion: We found a positive association between BCC and exposure to iAs through drinking water with concentrations < 100 μg/L. PMID:22436128

  1. Control of a mobile robot through brain computer interface

    Directory of Open Access Journals (Sweden)

    Robinson Jimenez Moreno

    2015-07-01

    Full Text Available This paper poses a control interface to command the movement of a mobile robot according to signals captured from the user's brain. These signals are acquired and interpreted by Emotiv EPOC device, a 14-electrode type sensor which captures electroencephalographic (EEG signals with high resolution, which, in turn, are sent to a computer for processing. One brain-computer interface (BCI was developed based on the Emotiv software and SDK in order to command the mobile robot from a distance. Functionality tests are performed with the sensor to discriminate shift intentions of a user group, as well as with a fuzzy controller to hold the direction in case of concentration loss. As conclusion, it was possible to obtain an efficient system for robot movements by brain commands.

  2. Control of an automated mobile manipulator using artificial immune system

    Science.gov (United States)

    Deepak, B. B. V. L.; Parhi, Dayal R.

    2016-03-01

    This paper addresses the coordination and control of a wheeled mobile manipulator (WMM) using artificial immune system. The aim of the developed methodology is to navigate the system autonomously and transport jobs and tools in manufacturing environments. This study integrates the kinematic structures of a four-axis manipulator and a differential wheeled mobile platform. The motion of the developed WMM is controlled by the complete system of parametric equation in terms of joint velocities and makes the robot to follow desired trajectories by the manipulator and platform within its workspace. The developed robot system performs its action intelligently according to the sensed environmental criteria within its search space. To verify the effectiveness of the proposed immune-based motion planner for WMM, simulations as well as experimental results are presented in various unknown environments.

  3. Alcohol control: Mobile sensor system and numerical signal analysis

    OpenAIRE

    Seifert, Rolf; Keller, Hubert B.; Conrad, Thorsten; Peter, Jens

    2016-01-01

    An innovative mobile sensor system for alcohol control in the respiratory air is introduced. The gas sensor included in the sensor system is thermo-cyclically operated. Ethanol is the leading component in this context. However, other components occur in the breathing air which can influence the concentration determination of ethanol. Therefore, mono- ethanol samples and binary gas mixtures are measured by the sensor system and analyzed with a new calibration and evaluation procedure which is ...

  4. DYNAMICS BASED CONTROL OF A SKID STEERING MOBILE ROBOT

    Directory of Open Access Journals (Sweden)

    Osama Elshazly

    2016-06-01

    Full Text Available In this paper, development of a reduced order, augmented dynamics-drive model that combines both the dynamics and drive subsystems of the skid steering mobile robot (SSMR is presented. A Linear Quadratic Regulator (LQR control algorithm with feed-forward compensation of the disturbances part included in the reduced order augmented dynamics-drive model is designed. The proposed controller has many advantages such as its simplicity in terms of design and implementation in comparison with complex nonlinear control schemes that are usually designed for this system. Moreover, the good performance is also provided by the controller for the SSMR comparable with a nonlinear controller based on the inverse dynamics which depends on the availability of an accurate model describing the system. Simulation results illustrate the effectiveness and enhancement provided by the proposed controller.

  5. Arsenic in the soils of Zimapan, Mexico

    International Nuclear Information System (INIS)

    Ongley, Lois K.; Sherman, Leslie; Armienta, Aurora; Concilio, Amy; Salinas, Carrie Ferguson

    2007-01-01

    Arsenic concentrations of 73 soil samples collected in the semi-arid Zimapan Valley range from 4 to 14 700 mg As kg -1 . Soil arsenic concentrations decrease with distance from mines and tailings and slag heaps and exceed 400 mg kg -1 only within 500 m of these arsenic sources. Soil arsenic concentrations correlate positively with Cu, Pb, and Zn concentrations, suggesting a strong association with ore minerals known to exist in the region. Some As was associated with Fe and Mn oxyhydroxides, this association is less for contaminated than for uncontaminated samples. Very little As was found in the mobile water-soluble or exchangeable fractions. The soils are not arsenic contaminated at depths greater than 100 cm below the surface. Although much of the arsenic in the soils is associated with relatively immobile solid phases, this represents a long-term source of arsenic to the environment. -- Much of the arsenic is relatively immobile but presents long-term source of arsenic

  6. Arsenic in the soils of Zimapan, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Ongley, Lois K. [Oak Hill High School, P.O. Box 400, Sabattus, ME 04280 (United States)]. E-mail: loisongley@earthlink.net; Sherman, Leslie [Department of Chemistry, Washington College, 300 Washington Avenue, Chestertown, MD 21620 (United States); Armienta, Aurora [Instituto de Geofisica, UNAM, Mexico D.F. 04510 (Mexico); Concilio, Amy [Department of Earth, Ecological, and Environmental Sciences, University of Toledo, Toledo, OH 43606 (United States); Salinas, Carrie Ferguson [Department of Agronomy and Environmental Management, Louisiana State University, Baton Rouge, LA 70803 (United States)

    2007-02-15

    Arsenic concentrations of 73 soil samples collected in the semi-arid Zimapan Valley range from 4 to 14 700 mg As kg{sup -1}. Soil arsenic concentrations decrease with distance from mines and tailings and slag heaps and exceed 400 mg kg{sup -1} only within 500 m of these arsenic sources. Soil arsenic concentrations correlate positively with Cu, Pb, and Zn concentrations, suggesting a strong association with ore minerals known to exist in the region. Some As was associated with Fe and Mn oxyhydroxides, this association is less for contaminated than for uncontaminated samples. Very little As was found in the mobile water-soluble or exchangeable fractions. The soils are not arsenic contaminated at depths greater than 100 cm below the surface. Although much of the arsenic in the soils is associated with relatively immobile solid phases, this represents a long-term source of arsenic to the environment. -- Much of the arsenic is relatively immobile but presents long-term source of arsenic.

  7. Arsenic speciation and sorption in natural environments

    Science.gov (United States)

    Campbell, Kate M.; Nordstrom, D. Kirk

    2014-01-01

    Aqueous arsenic speciation, or the chemical forms in which arsenic exists in water, is a challenging, interesting, and complicated aspect of environmental arsenic geochemistry. Arsenic has the ability to form a wide range of chemical bonds with carbon, oxygen, hydrogen, and sulfur, resulting in a large variety of compounds that exhibit a host of chemical and biochemical properties. Besides the intriguing chemical diversity, arsenic also has the rare capacity to capture our imaginations in a way that few elements can duplicate: it invokes images of foul play that range from sinister to comedic (e.g., “inheritance powder” and arsenic-spiked elderberry wine). However, the emergence of serious large-scale human health problems from chronic arsenic exposure in drinking water has placed a high priority on understanding environmental arsenic mobility, toxicity, and bioavailability, and chemical speciation is key to these important questions. Ultimately, the purpose of arsenic speciation research is to predict future occurrences, mitigate contamination, and provide successful management of water resources.

  8. Mobilization of arsenic, lead, and mercury under conditions of sea water intrusion and road deicing salt application

    Science.gov (United States)

    Sun, Hongbing; Alexander, John; Gove, Brita; Koch, Manfred

    2015-09-01

    Water geochemistry data from complexly designed salt-solution injection experiments in the laboratory, coastal aquifers of Bangladesh and Italy, taken from the literature, and two salted watersheds of New Jersey, US were collected and analyzed to study the geochemical mechanisms that mobilize As, Pb, and Hg under varied salting conditions. Overall, increased NaCl-concentrations in aquifers and soil are found to increase the release of Pb and Hg into the water. Reducing environments and possible soil dispersion by hydrated Na+ are found to lead to an increase of As-concentration in water. However, the application of a pure NaCl salt solution in the column injection experiment was found to release less As, Pb, and Hg initially from the soil and delay their concentration increase, when compared to the application of CaCl2 and NaCl mixed salts (at 6:4 weight ratio). The concentration correlation dendrogram statistical analyses of the experimental and field data suggest that the release of As, Hg, and Pb into groundwater and the soil solution depends not only on the salt level and content, but also on the redox condition, dissolved organic matter contents, competitiveness of other ions for exchange sites, and source minerals. With the ongoing over-exploration of coastal aquifers from increased pumping, continued sea-level rise, and increased winter deicing salt applications in salted watersheds of many inland regions, the results of this study will help understand the complex relation between the concentrations of As, Pb, and Hg and increased salt level in a coastal aquifer and in soils of a salted watershed.

  9. Applying virtual reality to remote control of mobile robot

    Directory of Open Access Journals (Sweden)

    Chen Chin-Shan

    2017-01-01

    Full Text Available The purpose of this research is based on virtual reality to assisted pick and place tasks. Virtual reality can be utilized to control remote robot for pick and place element. The operator monitored and controlled the situation information of working site by Human Machine Interface. Therefore, we worked in harsh or dangerous environments that thing can be avoided. The procedure to operate mobile robot in virtual reality describes as follow: An experiment site with really experimental equipment is first established. Then, the experimental equipment and scene modeling are input to virtual reality for establishing a environment similar to the reality. Finally, the remote mobile robot is controlled to operate pick and place tasks through wireless communication by the object operation in virtual reality. The robot consists of a movable robot platform and robotic arm. The virtual reality is constructed by EON software; the Human Machine Interface is established by Visual Basic. The wireless connection is equipped the wireless Bluetooth, which is set the PC and PLC controller. With experimental tests to verify the robot in virtual reality and the wireless remote control, the robot could be operated and controlled to successfully complete pick and place tasks in reality by Human Machine Interface.

  10. Augmented models for improving vision control of a mobile robot

    DEFF Research Database (Denmark)

    Andersen, Gert Lysgaard; Christensen, Anders C.; Ravn, Ole

    1994-01-01

    obtain good performance even when using standard low cost equipment and a comparatively low sampling rate. The plant model is a compound of kinematic, dynamic and sensor submodels, all integrated into a discrete state space representation. An intelligent strategy is applied for the vision sensor......This paper describes the modelling phases for the design of a path tracking vision controller for a three wheeled mobile robot. It is shown that, by including the dynamic characteristics of vision and encoder sensors and implementing the total system in one multivariable control loop, one can...

  11. Arsenic is associated with reduced effect of folic acid in myelomeningocele prevention: a case control study in Bangladesh

    Science.gov (United States)

    Background: Arsenic induces neural tube defects in several animal models, but its potential to cause neural tube defects in humans is unknown. Our objective was to investigate the associations between maternal arsenic exposure, periconceptional folic acid supplementation, and risk of posterior neura...

  12. Remote Control of a Mobile Robot for Indoor Patrol

    Directory of Open Access Journals (Sweden)

    Shih-Yao Juang

    2016-03-01

    Full Text Available This study applies smartphone, Bluetooth, and Wi-Fi wireless network to control a wheeled mobile robot (WMR remotely. The first part of this study demonstrates that the WMR can be controlled manually by a smartphone. The smartphone can remotely control the WMR for forward, backward, left-turn, and right-turn operations. The second part of this article presents object tracking. The WMR can follow a moving object through the use of image processing for object tracking and distance detection. In the third part, infrared sensor and fuzzy system algorithms are integrated into the control scheme. Through wall-following and obstacle-avoidance control, the WMR can successfully perform indoor patrol.

  13. Cooperative control of a squad of mobile vehicles

    International Nuclear Information System (INIS)

    Lewis, C.; Feddema, J.; Klarer, P.

    1998-01-01

    Tasks such as the localization of chemical sources, demining, perimeter control, surveillance and search and rescue missions are usually performed by teams of people. At least conceptually, large groups of relatively cheap mobile vehicles outfitted with sensors should be able to automatically accomplish some of these tasks. Sandia National Labs is currently developing a swarm of semi-autonomous all terrain vehicles for remote cooperative sensing applications. This paper will describe the capabilities of this system and outline some of its possible applications. Cooperative control and sensing strategies will also be described. Eight Roving All Terrain Lunar Explorer Rovers (RATLERs) have been built at Sandia as a test platform for cooperative control and sensing applications. This paper will first describe the hardware capabilities of the RATLER system. Then it will describe the basic control algorithm for GPS based navigation and obstacle avoidance. A higher level cooperative control task will then be described

  14. Control of mobility in molecular organic semiconductors by dendrimer generation

    Science.gov (United States)

    Lupton, J. M.; Samuel, I. D.; Beavington, R.; Frampton, M. J.; Burn, P. L.; Bässler, H.

    2001-04-01

    Conjugated dendrimers are of interest as novel materials for light-emitting diodes. They consist of a luminescent chromophore at the core with highly branched conjugated dendron sidegroups. In these materials, light emission occurs from the core and is independent of generation. The dendron branching controls the separation between the chromophores. We present here a family of conjugated dendrimers and investigate the effect of dendron branching on light emission and charge transport. We apply a number of transport measurement techniques to thin films of a conjugated dendrimer in a light-emitting diode configuration to determine the effect of chromophore spacing on charge transport. We find that the mobility is reduced by two orders of magnitude as the size of the molecule doubles with increased branching or dendrimer generation. The degree of branching allows a unique control of mobility by molecular structure. An increase in chromophore separation also results in a reduction of intermolecular interactions, which reduces the red emission tail in film photoluminescence. We find that the steady-state charge transport is well described by a simple device model incorporating the effect of generation, and use the materials to shed light on the interpretation of transient electroluminescence data. We demonstrate the significance of the ability to tune the mobility in bilayer devices, where a more balanced charge transport can be achieved.

  15. Mobile source pollution control in the United States and China

    International Nuclear Information System (INIS)

    Menz, Fredric C

    2002-01-01

    This paper reviews policies for the control of mobile source pollution and their potential application in China. The first section of the paper reviews the U.S. experience with mobile source pollution control since regulations were first established in the Clean Air Act of 1970. Highlights in the policy and trends in vehicle emissions over the 1970 to 2000 time period are discussed. The second section of the paper discusses the range of policy instruments that could be used to control vehicle pollution, ranging from traditional direct regulations to market-based instruments. Experiences with the use of economic incentives in the United States and elsewhere are also discussed. The third section of the paper discusses possible implications of the U.S. experience for controlling vehicle pollution in China. While market-based instruments might be particularly appropriate for use in several aspects of China's pollution control policies, important differences between the institutional structures in China and the United States suggest that they should be phased in gradually. The paper closes with concluding remarks. (author)

  16. Mobile source pollution control in the United States and China

    Energy Technology Data Exchange (ETDEWEB)

    Menz, Fredric C

    2002-07-01

    This paper reviews policies for the control of mobile source pollution and their potential application in China. The first section of the paper reviews the U.S. experience with mobile source pollution control since regulations were first established in the Clean Air Act of 1970. Highlights in the policy and trends in vehicle emissions over the 1970 to 2000 time period are discussed. The second section of the paper discusses the range of policy instruments that could be used to control vehicle pollution, ranging from traditional direct regulations to market-based instruments. Experiences with the use of economic incentives in the United States and elsewhere are also discussed. The third section of the paper discusses possible implications of the U.S. experience for controlling vehicle pollution in China. While market-based instruments might be particularly appropriate for use in several aspects of China's pollution control policies, important differences between the institutional structures in China and the United States suggest that they should be phased in gradually. The paper closes with concluding remarks. (author)

  17. Genome sequencing reveals the potential of an indigenous arsenotrophic bacterium; Achromobacter sp. KAs 3-5 for sub-surface arsenic mobilization and strategies for bioremediation

    Directory of Open Access Journals (Sweden)

    Balaram Mohapatra

    2017-12-01

    Full Text Available Prevalence of toxic arsenic (As oxyanion species in oligotrophic groundwater of south-east Asiatic regions (India and Bangladesh has threatened the health of millions of people. As-transforming bacteria alter the mobility, speciation and bioavailability of As in the aquifer ecosystem, hence play important roles in the biogeochemical cycling of As. Till date, only 19 cultivable As-transforming bacterial strains have been reported but with no description on their detail genomic and physiological perspective of As homeostasis. In this study, the draft genome (5.7 Mbp of an As-transforming, aromatic hydrocarbon utilizing and iron disproportioning indigenous groundwater bacterium KAs 3-5 has been obtained by Ion-Torrent sequencing revealed 65% genomic GC content, 5100 protein coding genes, and taxonomic affiliation to the members of genus Achromobacter, with >85% of genomic completeness. Phylogenomic signatures like MLST of 10 house-keeping genes, cut-off of <95% of average nucleotide/amino acid identity (ANI/OrthoANI/AAI, <0.99 of tetra-nucleotide correlations, and <70% value of DNA-DNA homology with nearest phylogenetic neighbors exhibited its species distinctiveness among all the described Achromobacter sp. members. Pan-genomic analysis confirmed the strain’s potential to adapt wide array of environmental stresses with a higher abundance of unique genes for metabolism of amino acids, polyketide, xenobiotics, nitroso compounds, aromatic hydrocarbons and most necessarily complete operon cluster for As-resistance/transformation/detoxification, as well as genes for transport, and signal transduction mechanisms. The genome analysis also highlighted its genetic determinants for loss of functions for antibiotic resistance, pathogenicity regulations, and gain of new/acquired functions for Fe-transport, fatty acids uptake-metabolism, motility, heavy metal (Cu-Zn-Co metabolism and several putative/hypothetical proteins owing to its capacity to acquired

  18. Position Control of the Single Spherical Wheel Mobile Robot by Using the Fuzzy Sliding Mode Controller

    OpenAIRE

    Hamed Navabi; Soroush Sadeghnejad; Sepehr Ramezani; Jacky Baltes

    2017-01-01

    A spherical wheel robot or Ballbot—a robot that balances on an actuated spherical ball—is a new and recent type of robot in the popular area of mobile robotics. This paper focuses on the modeling and control of such a robot. We apply the Lagrangian method to derive the governing dynamic equations of the system. We also describe a novel Fuzzy Sliding Mode Controller (FSMC) implemented to control a spherical wheel mobile robot. The nonlinear nature of the equations makes the controller nontrivi...

  19. Arsenic and selenium in microbial metabolism

    Science.gov (United States)

    Stolz, John F.; Basu, Partha; Santini, Joanne M.; Oremland, Ronald S.

    2006-01-01

    Arsenic and selenium are readily metabolized by prokaryotes, participating in a full range of metabolic functions including assimilation, methylation, detoxification, and anaerobic respiration. Arsenic speciation and mobility is affected by microbes through oxidation/reduction reactions as part of resistance and respiratory processes. A robust arsenic cycle has been demonstrated in diverse environments. Respiratory arsenate reductases, arsenic methyltransferases, and new components in arsenic resistance have been recently described. The requirement for selenium stems primarily from its incorporation into selenocysteine and its function in selenoenzymes. Selenium oxyanions can serve as an electron acceptor in anaerobic respiration, forming distinct nanoparticles of elemental selenium that may be enriched in (76)Se. The biogenesis of selenoproteins has been elucidated, and selenium methyltransferases and a respiratory selenate reductase have also been described. This review highlights recent advances in ecology, biochemistry, and molecular biology and provides a prelude to the impact of genomics studies.

  20. Mobilities

    DEFF Research Database (Denmark)

    to social networks, personal identities, and our relationship to the built environment. The omnipresence of mobilities within everyday life, high politics, technology, and tourism (to mention but a few) all point to a key insight harnessed by the ‘mobilities turn’. Namely that mobilities is much more than......The world is on the move. This is a widespread understanding by many inhabitants of contemporary society across the Globe. But what does it actually mean? During over one decade the ‘mobilities turn’ within the social sciences have provided a new set of insights into the repercussions of mobilities...... and environmental degradation. The spaces and territories marked by mobilities as well as the sites marked by the bypassing of such are explored. Moreover, the architectural and technological dimensions to infrastructures and sites of mobilities will be included as well as the issues of power, social exclusion...

  1. Efficient Control Law Simulation for Multiple Mobile Robots

    Energy Technology Data Exchange (ETDEWEB)

    Driessen, B.J.; Feddema, J.T.; Kotulski, J.D.; Kwok, K.S.

    1998-10-06

    In this paper we consider the problem of simulating simple control laws involving large numbers of mobile robots. Such simulation can be computationally prohibitive if the number of robots is large enough, say 1 million, due to the 0(N2 ) cost of each time step. This work therefore uses hierarchical tree-based methods for calculating the control law. These tree-based approaches have O(NlogN) cost per time step, thus allowing for efficient simulation involving a large number of robots. For concreteness, a decentralized control law which involves only the distance and bearing to the closest neighbor robot will be considered. The time to calculate the control law for each robot at each time step is demonstrated to be O(logN).

  2. The Bluetooth Based LED Control For Arduino Test Platform By Using Mobile APP

    OpenAIRE

    Yi-Jen Mon

    2015-01-01

    Abstract The Bluetooth is a commonly known convenient and famous communication protocol. In this paper it is used to control LED mounted on Arduino test platform by using the APP of mobile phone. At first the control program is completed by Arduino development software environment then the Android APP is installed in mobile phone. Finally by using the Bluetooth of mobile phone the test platform will be connected. The LED can be controlled by APP of mobile phone. The experiment results are dem...

  3. New Intelligent Transmission Concept for Hybrid Mobile Robot Speed Control

    Directory of Open Access Journals (Sweden)

    Nazim Mir-Nasiri

    2008-11-01

    Full Text Available This paper presents a new concept of a mobile robot speed control by using two degree of freedom gear transmission. The developed intelligent speed controller utilizes a gear box which comprises of epicyclic gear train with two inputs, one coupled with the engine shaft and another with the shaft of a variable speed dc motor. The net output speed is a combination of the two input speeds and is governed by the transmission ratio of the planetary gear train. This new approach eliminates the use of a torque converter which is otherwise an indispensable part of all available automatic transmissions, thereby reducing the power loss that occurs in the box during the fluid coupling. By gradually varying the speed of the dc motor a stepless transmission has been achieved. The other advantages of the developed controller are pulling over and reversing the vehicle, implemented by intelligent mixing of the dc motor and engine speeds. This approach eliminates traditional braking system in entire vehicle design. The use of two power sources, IC engine and battery driven DC motor, utilizes the modern idea of hybrid vehicles. The new mobile robot speed controller is capable of driving the vehicle even in extreme case of IC engine failure, for example, due to gas depletion..

  4. New Intelligent Transmission Concept for Hybrid Mobile Robot Speed Control

    Directory of Open Access Journals (Sweden)

    Nazim Mir-Nasiri

    2005-09-01

    Full Text Available This paper presents a new concept of a mobile robot speed control by using two degree of freedom gear transmission. The developed intelligent speed controller utilizes a gear box which comprises of epicyclic gear train with two inputs, one coupled with the engine shaft and another with the shaft of a variable speed dc motor. The net output speed is a combination of the two input speeds and is governed by the transmission ratio of the planetary gear train. This new approach eliminates the use of a torque converter which is otherwise an indispensable part of all available automatic transmissions, thereby reducing the power loss that occurs in the box during the fluid coupling. By gradually varying the speed of the dc motor a stepless transmission has been achieved. The other advantages of the developed controller are pulling over and reversing the vehicle, implemented by intelligent mixing of the dc motor and engine speeds. This approach eliminates traditional braking system in entire vehicle design. The use of two power sources, IC engine and battery driven DC motor, utilizes the modern idea of hybrid vehicles. The new mobile robot speed controller is capable of driving the vehicle even in extreme case of IC engine failure, for example, due to gas depletion.

  5. Coupled S and Sr isotope evidences for elevated arsenic concentrations in groundwater from the world's largest antimony mine, Central China

    Science.gov (United States)

    Wen, Bing; Zhou, Aiguo; Zhou, Jianwei; Liu, Cunfu; Huang, Yuliu; Li, Ligang

    2018-02-01

    The Xikuangshan(XKS) mine, the world's largest antimony mine, was chosen for a detailed arsenic hydrogeochemical study because of the elevated arsenic in bedrock aquifers used by local residents. Hydrochemical data, δ34S values of dissolved SO42- and 87Sr/86Sr ratios have been analyzed to identify the predominant geochemical processes that control the arsenic mobilization within the aquifers. Groundwater samples can be divided into three major types: low arsenic groundwater (0-50 μg/L), high arsenic groundwater (50-1000 μg/L) and anomalous high arsenic groundwater (>1000 μg/L). Arsenic occurs under oxidizing conditions at the XKS Sb mine as the HAsO42- anion. The Ca/Na ratio correlates significantly with HCO3-/Na and Sr/Na ratios, indicating that carbonate dissolution and silicate weathering are the dominant processes controlling groundwater hydrochemistry. The δ34S values of the groundwater indicate that dissolved SO42- in groundwater is mainly sourced from the oxidation of sulfide minerals, and elevated As concentrations in groundwater are influenced by the mixing of mine water and surface water. Furthermore, the δ34S values are not correlated with dissolved As concentrations and Fe concentrations, suggesting that the reduction dissolution of Fe(III) hydroxides is not the dominant process controlling As mobilization. The 87Sr/86Sr ratios imply that elevated As concentrations in groundwater are primarily derived from the interaction with the stibnite and silicified limestone. More specifically, the excess-Na ion, the feature of Ca/Na ratio, and the spatial association of elevated As concentrations in groundwater collectively suggest that high and anomalous high arsenic groundwater are associated with smelting slags and, in particular, the arsenic alkali residue. In general, the hydrochemistry analysis, especially the S and Sr isotope evidences elucidate that elevated As concentrations and As mobilization are influenced by several geochemical processes

  6. Position Control of the Single Spherical Wheel Mobile Robot by Using the Fuzzy Sliding Mode Controller

    Directory of Open Access Journals (Sweden)

    Hamed Navabi

    2017-01-01

    Full Text Available A spherical wheel robot or Ballbot—a robot that balances on an actuated spherical ball—is a new and recent type of robot in the popular area of mobile robotics. This paper focuses on the modeling and control of such a robot. We apply the Lagrangian method to derive the governing dynamic equations of the system. We also describe a novel Fuzzy Sliding Mode Controller (FSMC implemented to control a spherical wheel mobile robot. The nonlinear nature of the equations makes the controller nontrivial. We compare the performance of four different fuzzy controllers: (a regulation with one signal, (b regulation and position control with one signal, (c regulation and position control with two signals, and (d FSMC for regulation and position control with two signals. The system is evaluated in a realistic simulation and the robot parameters are chosen based on a LEGO platform, so the designed controllers have the ability to be implemented on real hardware.

  7. Arsenic in Food

    Science.gov (United States)

    ... Vaccines, Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products Food Home Food Foodborne Illness & Contaminants Metals Arsenic Share ... of the Method used to Measure Arsenic in Foods Inductively Coupled Plasma-Mass Spectrometric Determination of Arsenic, ...

  8. Alcohol Control: Mobile Sensor System and Numerical Signal Analysis

    Directory of Open Access Journals (Sweden)

    Rolf SEIFERT

    2016-10-01

    Full Text Available An innovative mobile sensor system for alcohol control in the respiratory air is introduced. The gas sensor included in the sensor system is thermo-cyclically operated. Ethanol is the leading component in this context. However, other components occur in the breathing air which can influence the concentration determination of ethanol. Therefore, mono- ethanol samples and binary gas mixtures are measured by the sensor system and analyzed with a new calibration and evaluation procedure which is also incorporated in the system. The applications demonstrate a good substance identification capability of the sensor system and a very good concentration determination of the components.

  9. Non linear predictive control of a LEGO mobile robot

    Science.gov (United States)

    Merabti, H.; Bouchemal, B.; Belarbi, K.; Boucherma, D.; Amouri, A.

    2014-10-01

    Metaheuristics are general purpose heuristics which have shown a great potential for the solution of difficult optimization problems. In this work, we apply the meta heuristic, namely particle swarm optimization, PSO, for the solution of the optimization problem arising in NLMPC. This algorithm is easy to code and may be considered as alternatives for the more classical solution procedures. The PSO- NLMPC is applied to control a mobile robot for the tracking trajectory and obstacles avoidance. Experimental results show the strength of this approach.

  10. Autonomous Power Control MAC Protocol for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available Battery energy limitation has become a performance bottleneck for mobile ad hoc networks. IEEE 802.11 has been adopted as the current standard MAC protocol for ad hoc networks. However, it was developed without considering energy efficiency. To solve this problem, many modifications on IEEE 802.11 to incorporate power control have been proposed in the literature. The main idea of these power control schemes is to use a maximum possible power level for transmitting RTS/CTS and the lowest acceptable power for sending DATA/ACK. However, these schemes may degrade network throughput and reduce the overall energy efficiency of the network. This paper proposes autonomous power control MAC protocol (APCMP, which allows mobile nodes dynamically adjusting power level for transmitting DATA/ACK according to the distances between the transmitter and its neighbors. In addition, the power level for transmitting RTS/CTS is also adjustable according to the power level for DATA/ACK packets. In this paper, the performance of APCMP protocol is evaluated by simulation and is compared with that of other protocols.

  11. Arsenic speciation using high performance liquid chromatography-inductively coupled plasma-mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Bass, D.A.; Yaeger, J.S.; Crain, J.S.; Kiely, J.T.; Parish, K.J.; Gowdy, M.J. [Argonne National Lab., IL (United States); Mohrman, G.B. [Rocky Mountain Arsenal, Commerce City, CO (United States)

    1995-08-01

    A method has been developed by Argonne National Laboratory to identify and quantify As(III), As(V), and organoarsenic compounds in environmental samples. A arsenic species were separated by reversed-phase, ion-pairing, HPLC using a microbore Inertsil-ODS{trademark} column. Only 1 {micro}L of sample was injected on the column, and the mobile phase flow rates were typically on the order of 40 {micro}L/min. The HPLC mobile phase was a mixture of methanol and tetrabutylammonium hydroxide (TBAH), and the column effluent was introduced into an ICP-mass spectrometer using direct injection nebulization. Detection limits of less than 1 pg As (as injected on the column) were easily obtained for each arsenic species. The effect of changes in mobile phase composition and ICP-MS conditions will be described, as well as quality control measures, e.g., the use of surrogates, internal standards, and matrix spikes. Precision and accuracy information will be presented from the analysis of aqueous standards and soil extracts that were spiked with arsenic oxide [As(III)], sodium arsenate [As(V)], dimethylarsinic acid (DMAA), or chlorovinyl arsenious acid (CVAA). The authors believe that these data demonstrate the utility of this technique for the sensitive determination of arsenic species present in water or soil.

  12. Integrated Control Strategies Supporting Autonomous Functionalities in Mobile Robots

    Directory of Open Access Journals (Sweden)

    Brandon Sights

    2006-10-01

    Full Text Available High-level intelligence allows a mobile robot to create and interpret complex world models, but without a precise control system, the accuracy of the world model and the robot's ability to interact with its surroundings are greatly diminished. This problem is amplified when the environment is hostile, such as in a battlefield situation where an error in movement or a slow response may lead to destruction of the robot. As the presence of robots on the battlefield continues to escalate and the trend toward relieving the human of the low-level control burden advances, the ability to combine the functionalities of several critical control systems on a single platform becomes imperative.

  13. Optimal Trajectory Tracking Control for a Wheeled Mobile Robot Using Fractional Order PID Controller

    Directory of Open Access Journals (Sweden)

    Ameer L. Saleh

    2018-02-01

    Full Text Available This paper present an optimal Fractional Order PID (FOPID controller based on Particle Swarm Optimization (PSO for controlling the trajectory tracking of Wheeled Mobile Robot(WMR.The issue of trajectory tracking with given a desired reference velocity is minimized to get the distance and deviation angle equal to zero, to realize the objective of trajectory tracking a two FOPID controllers are used for velocity control and azimuth control to implement the trajectory tracking control. A path planning and path tracking methodologies are used to give different desired tracking trajectories.  PSO algorithm is using to find the optimal parameters of FOPID controllers. The kinematic and dynamic models of wheeled mobile robot for desired trajectory tracking with PSO algorithm are simulated in Simulink-Matlab. Simulation results show that the optimal FOPID controllers are more effective and has better dynamic performance than the conventional methods.

  14. Bacteria, hypertolerant to arsenic in the rocks of an ancient gold mine, and their potential role in dissemination of arsenic pollution.

    Science.gov (United States)

    Drewniak, Lukasz; Styczek, Aleksandra; Majder-Lopatka, Malgorzata; Sklodowska, Aleksandra

    2008-12-01

    The aim of the present study was to find out if bacteria present in ancient gold mine could transform immobilized arsenic into its mobile form and increase its dissemination in the environment. Twenty-two arsenic-hypertolerant cultivable bacterial strains were isolated. No chemolithoautotrophs, which could use arsenite as an electron donor as well as arsenate as an electron acceptor, were identified. Five isolates exhibited hypertolerance to arsenic: up to 500mM of arsenate. A correlation between the presence of siderophores and high resistance to arsenic was found. The results of this study show that detoxification processes based on arsenate reductase activity might be significant in dissemination of arsenic pollution. It was concluded that the activity of the described heterotrophic bacteria contributes to the mobilization of arsenic in the more toxic As(III) form and a new mechanism of arsenic mobilization from a scorodite was proposed.

  15. Assessing the efficiency of aluminium phosphide and arsenic trioxide in controlling the Indian crested porcupine (hystrix indica) in an irrigated forest plantation or Punjab, Pakistan

    International Nuclear Information System (INIS)

    Khan, A.A.

    2010-01-01

    The Indian crested porcupine, Hystrix indica, is widely distributed in the irrigated forests of Punjab, Pakistan and causes serious damage to trees, nursery stocking, field crops and vegetables. Field trials were conducted to determine the efficacy of aluminium phosphide (Phostoxin, 3g tablets) and arsenic trioxide bait (at 2.5g per apple) against the porcupine in a forest plantation. For fumigation with phostoxin, tablets were used at the rate of four, five, six and seven tablets per den. Observations showed that four tablets were ineffective, five and six tablets provided partial control, while seven tablets provided complete control of porcupines. Baiting with arsenic trioxide also resulted in 89 % reduction of the porcupine population occupying the treated dens. (author)

  16. Intelligent control system for nuclear power plant mobile robot

    International Nuclear Information System (INIS)

    Koenig, A.; Lecoeur-Taibi, I.; Crochon, E.; Vacherand, F.

    1991-01-01

    In order to fully optimize the efficiency of the perception and navigation components available on a mobile robot, the upper level of a mobile robot control requires intelligence support to unload the work of the teleoperator. This knowledge-based system has to manage a priori data such as the map of the workspace, the mission, the characteristics of sensors and robot, but also, the current environment state and the running mission. It has to issue a plan to drive the sensors to focus on relevant objects or to scan the environment and to select the best algorithms depending on the current situation. The environment workspace is a nuclear power plant building. The teleoperated robot is a mobile wheeled or legged vehicle that moves inside the different floors of the building. There are three types of mission: radio-activity survey, inspection and intervention. To perform these goals the robot must avoid obstacles, pass through doors, possibly climb stairs and recognize valves and pipes. The perception control system has to provide the operator with a synthetic view of the surroundings. It manages background tasks such as obstacle detection and free space map building, and specific tasks such as beacon recognition for odometry relocalization and valve detection for maintenance. To do this, the system solves perception resources conflicts, taking into account the current states of the sensors and the current conditions such as lightness or darkness, cluttered scenes, sensor failure. A perception plan is issued from the mission goals, planned path, relocalization requirements and available perception resources. Basically, the knowledge-based system is implemented on a blackboard architecture which includes two parts: a top-down planning part and a bottom-up perception part. The results of the perception are continuously sent to the operator who can trigger new perception actions. (author)

  17. Using real-time stereopsis for mobile robot control

    Science.gov (United States)

    Bonasso, R. P.; Nishihara, H. K.

    1991-02-01

    This paper describes on-going work in using range and motion data generated at video-frame rates as the basis for long-range perception in a mobile robot. A current approach in the artificial intelligence community to achieve timecritical perception for situated reasoning is to use low-level perception for motor reflex-like activity and higher-level but more computationally intense perception for path planning reconnaissance and retrieval activities. Typically inclinometers and a compass or an infra-red beacon system provide stability and orientation maintenance and ultrasonic or infra-red sensors serve as proximity detectors for obstacle avoidance. For distant ranging and area occupancy determination active imaging systems such as laser scanners can be prohibitivtly expensive and heretofore passive systems typically performed more slowly than the cycle time of the control system causing the robot to halt periodically along its way. However a recent stereo system developed by Nishihara known as PRISM (Practical Real-time Imaging Stereo Matcher) matches stereo pairs using a sign-correlation technique that gives range and motion at video frame rates. We are integrating this technique with constant-time control software for distant ranging and object detection at a speed that is comparable with the cycle-times of the low-level sensors. Possibilities for a variety of uses in a leader-follower mobile robot situation are discussed.

  18. Consumption of low-moderate level arsenic contaminated water does not increase spontaneous pregnancy loss: a case control study.

    Science.gov (United States)

    Bloom, Michael S; Neamtiu, Iulia A; Surdu, Simona; Pop, Cristian; Lupsa, Ioana Rodica; Anastasiu, Doru; Fitzgerald, Edward F; Gurzau, Eugen S

    2014-10-13

    Previous work suggests an increased risk for spontaneous pregnancy loss linked to high levels of inorganic arsenic (iAs) in drinking water sources (>10 μg/L). However, there has been little focus to date on the impact of low-moderate levels of iAs in drinking water (control study in Timis County, Romania. We recruited women with incident spontaneous pregnancy loss of 5-20 weeks completed gestation as cases (n = 150), and women with ongoing pregnancies matched by gestational age (±1 week) as controls (n = 150). Participants completed a physician-administered questionnaire and we collected water samples from residential drinking sources. We reconstructed residential drinking water exposure histories using questionnaire data weighted by iAs determined using hydride generation-atomic absorption spectrometry (HG-AAS). Logistic regression models were used to generate odds ratios (OR) and 95% confidence intervals (CI) for associations between iAs exposure and loss, conditioned on gestational age and adjusted for maternal age, cigarette smoking, education and prenatal vitamin use. We explored potential interactions in a second set of models. Drinking water arsenic concentrations ranged from 0.0 to 175.1 μg/L, with median 0.4 μg/L and 90th%tile 9.4 μg/L. There were no statistically significant associations between loss and average or peak drinking water iAs concentrations (OR 0.98, 95% CI 0.96-1.01), or for daily iAs intake (OR 1.00, 95% CI 0.98-1.02). We detected modest evidence for an interaction between average iAs concentration and cigarette smoking during pregnancy (P = 0.057) and for daily iAs exposure and prenatal vitamin use (P = 0.085). These results suggest no increased risk for spontaneous pregnancy loss in association with low to moderate level drinking water iAs exposure. Though imprecise, our data also raise the possibility for increased risk among cigarette smokers. Given the low exposures overall, these data should reassure pregnant

  19. Evaluation of processes controlling the geochemical constituents in deep groundwater in Bangladesh: Spatial variability on arsenic and boron enrichment

    International Nuclear Information System (INIS)

    Halim, M.A.; Majumder, R.K.; Nessa, S.A.; Hiroshiro, Y.; Sasaki, K.; Saha, B.B.; Saepuloh, A.; Jinno, K.

    2010-01-01

    Forty-six deep groundwater samples from highly arsenic affected areas in Bangladesh were analyzed in order to evaluate the processes controlling geochemical constituents in the deep aquifer system. Spatial trends of solutes, geochemical modeling and principal component analysis indicate that carbonate dissolution, silicate weathering and ion exchange control the major-ion chemistry. The groundwater is dominantly of Na-Cl type brackish water. Approximately 17% of the examined groundwaters exhibit As concentrations higher than the maximum acceptable limit of 10 μg/L for drinking water. Strong correlation (R 2 = 0.67) of Fe with dissolved organic carbon (DOC) and positive saturation index of siderite suggests that the reductive dissolution of Fe-oxyhydroxide in presence of organic matter is considered to be the dominant process to release high content of Fe (median 0.31 mg/L) in the deep aquifer. In contrast, As is not correlated with Fe and DOC. Boron concentration in the 26% samples exceeds the standard limit of 500 μg/L, for water intended for human consumption. Negative relationships of B/Cl ratio with Cl and boron with Na/Ca ratio demonstrate the boron in deep groundwater is accompanied by brackish water and cation exchange within the clayey sediments.

  20. Intra-annual variations of arsenic totals and species in tropical estuary surface sediments

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, P.; Jayachandran, S.; Babu, P.V.R.; Karri, S.; Tyadi, P.; Yao, K.M.; Sharma, B.M.

    the mobility of arsenic complexes in an estuarine system. The higher salt (NaCl) concentrations result in less arsenic adsorption to the sediment due to formation of weak arsenic complexes because of competition from Cl sup(-) ions or due to a reduction...

  1. Effect of edta on arsenic phytoextraction by arundo donax

    International Nuclear Information System (INIS)

    Mirza, N.; Pervez, A.; Mahmood, Q.; Shah, M.M.; Farooq, U.

    2014-01-01

    Ligand assisted metal uptake by plants is recent trend in environmental clean-up. Arundo donax L. has been demonstrated as a suitable bioresource for the phytoextraction of arsenic recently. A. donax L. plants were grown in arsenic contaminated soil with doses (5 and 10 mg kg/sup -1/) of Ethylene Diamine Tetra Acetic Acid (EDTA) to investigate chelator-assisted phytoextraction. The arsenic treatments included control (no metal) and five doses of arsenic, i.e., 50, 100, 300, 600 and 1000 micro g kg/sup -1/ . The arsenic concentrations linearly increased in parts of plant with the increasing arsenic and EDTA in growth medium. Ligand addition also resulted in the increased arsenic accumulation in the shoot over its control plants. EDTA additionat the rate 5 mg kg/sup -1/ to the treatment system may effectively increase the arsenic uptake by A. donax without severe growth suppression. (author)

  2. Biotransformation of arsenite and bacterial aox activity in drinking water produced from surface water of floating houses: Arsenic contamination in Cambodia

    International Nuclear Information System (INIS)

    Chang, Jin-Soo

    2015-01-01

    The potential arsenite bioteansformation activity of arsenic was investigated by examining bacterial arsenic arsenite-oxidizing gene such as aoxS, aoxR, aoxA, aoxB, aoxC, and aoxD in high arsenic-contaminated drinking water produced from the surface water of floating houses. There is a biogeochemical cycle of activity involving arsenite oxidase aox system and the ars (arsenic resistance system) gene operon and aoxR leader gene activity in Alcaligenes faecalis SRR-11 and aoxS leader gene activity in Achromobacter xylosoxidans TSL-66. Batch experiments showed that SRR-11 and TSL-66 completely oxidized 1 mM of As (III) to As (V) within 35–40 h. The leaders of aoxS and aoxR are important for gene activity, and their effects in arsenic bioremediation and mobility in natural water has a significant ecological role because it allows arsenite oxidase in bacteria to control the biogeochemical cycle of arsenic-contaminated drinking water produced from surface water of floating houses. - Highlights: • The aox genotype system activity and arsenite-oxidizing bacteria was studied. • High arsenic contamination affects the detoxification activities of aoxS and aoxM. • Much Cambodian drinking water has dangerously high arsenic contamination. • Disease-causing microorganisms were found in various drinking water sources. - The importance of this study is that it responds to the high concentrations of arsenic contamination that were found in the drinking water of floating-house residents with the following proposition: The combined periplasm activity of the aoxS and aoxR genes and arsenite oxidase reflects the arsenic oxidation potential of the aoxA, aoxB, aoxC, and aoxD systems in the surface water of floating houses in Cambodia.

  3. Folic Acid and Creatine as Therapeutic Approaches to Lower Blood Arsenic: A Randomized Controlled Trial.

    Science.gov (United States)

    Peters, Brandilyn A; Hall, Megan N; Liu, Xinhua; Parvez, Faruque; Sanchez, Tiffany R; van Geen, Alexander; Mey, Jacob L; Siddique, Abu B; Shahriar, Hasan; Uddin, Mohammad Nasir; Islam, Tariqul; Balac, Olgica; Ilievski, Vesna; Factor-Litvak, Pam; Graziano, Joseph H; Gamble, Mary V

    2015-12-01

    The World Health Organization estimates that > 140 million people worldwide are exposed to arsenic (As)-contaminated drinking water. As undergoes biologic methylation, which facilitates renal As elimination. In folate-deficient individuals, this process is augmented by folic acid (FA) supplementation, thereby lowering blood As (bAs). Creatinine concentrations in urine are a robust predictor of As methylation patterns. Although the reasons for this are unclear, creatine synthesis is a major consumer of methyl donors, and this synthesis is down-regulated by dietary/supplemental creatine. Our aim was to determine whether 400 or 800 μg FA and/or creatine supplementation lowers bAs in an As-exposed Bangladeshi population. We conducted a clinical trial in which 622 participants were randomized to receive 400 μg FA, 800 μg FA, 3 g creatine, 3 g creatine+400 μg FA, or placebo daily. All participants received an As-removal filter on enrollment, and were followed for 24 weeks. After the 12th week, half of the two FA groups were switched to placebo to evaluate post-treatment bAs patterns. Linear models with repeated measures indicated that the decline in ln(bAs) from baseline in the 800-μg FA group exceeded that of the placebo group (weeks 1-12: β= -0.09, 95% CI: -0.18, -0.01; weeks 13-24: FA continued: β= -0.12, 95% CI: -0.24, -0.00; FA switched to placebo: β= -0.14, 95% CI: -0.26, -0.02). There was no rebound in bAs related to cessation of FA supplementation. Declines in bAs observed in the remaining treatment arms were not significantly different from those of the placebo group. In this mixed folate-deficient/replete study population, 12- and 24-week treatment with 800 μg (but not 400 μg) FA lowered bAs to a greater extent than placebo; this was sustained 12 weeks after FA cessation. In future studies, we will evaluate whether FA and/or creatine altered As methylation profiles.

  4. Urinary arsenic species, toenail arsenic, and arsenic intake estimates in a Michigan population with low levels of arsenic in drinking water.

    Science.gov (United States)

    Rivera-Núñez, Zorimar; Meliker, Jaymie R; Meeker, John D; Slotnick, Melissa J; Nriagu, Jerome O

    2012-01-01

    The large disparity between arsenic concentrations in drinking water and urine remains unexplained. This study aims to evaluate predictors of urinary arsenic in a population exposed to low concentrations (≤50 μg/l) of arsenic in drinking water. Urine and drinking water samples were collected from a subsample (n=343) of a population enrolled in a bladder cancer case-control study in southeastern Michigan. Total arsenic in water and arsenic species in urine were determined using ICP-MS: arsenobetaine (AsB), arsenite (As[III]), arsenate (As[V]), methylarsenic acid (MMA[V]), and dimethylarsenic acid (DMA[V]). The sum of As[III], As[V], MMA[V], and DMA[V] was denoted as SumAs. Dietary information was obtained through a self-reported food intake questionnaire. Log(10)-transformed drinking water arsenic concentration at home was a significant (Pwater were removed and further improved when analyses were applied to individuals who consumed amounts of home drinking water above the median volume (R(2)=0.40, Pwater was 0.42. Results show that arsenic exposure from drinking water consumption is an important determinant of urinary arsenic concentrations, even in a population exposed to relatively low levels of arsenic in drinking water, and suggest that seafood intake may influence urinary DMA[V] concentrations.

  5. Biotechnology based processes for arsenic removal

    NARCIS (Netherlands)

    Huisman, J.; Olde Weghuis, M.; Gonzalez-Contreras, P.A.

    2011-01-01

    The regulations for arsenic control have become strict. Therefore, better technologies to remove arsenic from bleeds and effluents are desired. In addition, no single solution is suitable for all cases. The properties of the process streams and the storage facilities are major factors determining

  6. Understanding Arsenic Dynamics in Agronomic Systems to Predict and Prevent Uptake by Crop Plants

    Science.gov (United States)

    This review is on arsenic in agronomic systems, and covers processes that influence the entry of arsenic into the human food supply. The scope is from sources of arsenic (natural and anthropogenic) in soils, biogeochemical and rhizosphere processes that control arsenic speciatio...

  7. Arsenic species and chemistry in groundwater of southeast Michigan

    International Nuclear Information System (INIS)

    Kim, M.-J.; Nriagu, Jerome; Haack, Sheridan

    2002-01-01

    Most of the arsenic detected was arsenite [As(III)]. - Groundwater samples, taken from 73 wells in 10 counties of southeast Michigan in 1997 had arsenic concentrations in the range of 0.5 to 278 μg/l, the average being 29 μg/l. About 12% of these wells had arsenic concentrations that exceeded the current USEPA's maximum contaminant level of 50 μg/l. Most (53-98%) of the arsenic detected was arsenite [As(III)] and other observations supported the arsenic species distribution (low redox potential and DO). In shallow groundwater ( 15 m), the concentration of arsenic is possibly controlled by reductive dissolution of arsenic-rich iron hydroxide/oxyhydroxide and dissolution of arsenic sulfide minerals

  8. Exiguobacterium mediated arsenic removal and its protective effect against arsenic induced toxicity and oxidative damage in freshwater fish, Channa striata

    Directory of Open Access Journals (Sweden)

    Neha Pandey

    2015-01-01

    Full Text Available Arsenic is a toxic metalloid existing widely in the environment, and its removal from contaminated water has become a global challenge. The use of bacteria in this regard finds a promising solution. In the present study, Exiguobacterium sp. As-9, which is an arsenic resistant bacterium, was selected with respect to its arsenic removal efficiency. Quantification of arsenic in the water treated with bacterium showed that Exiguobacterium efficiently removed up to 99% of arsenic in less than 20 h. In order to reveal the possible effect of this bacterium in removal of arsenic from water and protecting fishes from the detrimental effects of arsenic, we initiated a range of studies on fresh water fish, Channa striata. It was observed that the fishes introduced into bacteria treated water displayed no symptoms of arsenic toxicity which was marked by a decreased oxidative damage, whereas the fishes exposed to arsenic revealed a significant (p < 0.05 increase in the oxidative stress together with the elevated levels of malondialdehyde. Determination of the bioaccumulation of arsenic in the liver tissues of C. striata using hydride generation atomic absorption spectrophotometry (HG-AAS revealed an increased As(III accumulation in the fishes exposed to arsenic whereas the arsenic level in the control and bacteria treated fishes were found below the detectable limit. In conclusion, this study presents the strategies of bacterial arsenic removal with possible directions for future research.

  9. ARSENIC ADSORPTION AND REDUCTION IN IRON-RICH SOILS NEARBY LANDFILLS IN NORTHWEST FLORIDA

    Directory of Open Access Journals (Sweden)

    Hongqin Xue

    2016-01-01

    Full Text Available In Florida, soils are mainly composed of Myakka, an acid soil characterized by a subsurface accumulation of humus and Al(III and Fe(III oxides. Downgradient of the landfills in Northwest Florida, elevated levels of iron and arsenic observations had been made in the groundwater from monitoring wells, which was attributed to the geomicrobial iron and arsenic reduction. There is thus an immediate research need for a better understanding of the reduction reactions that are responsible for the mobilization of iron and arsenic in the subsurface soil nearby landfills. Owing to the high Fe(III oxide content, As(V adsorption reactions with Fe(III oxide surfaces are particularly important, which may control As(V reduction. This research focused on the investigation of the biogeochemical processes of the subsurface soil nearby landfills of Northwest Florida. Arsenic and iron reduction was studied in batch reactors and quantified based on Monod-type microbial kinetic growth simulations. As(V adsorption in iron-rich Northwest Floridian soils was further investigated to explain the reduction observations. It was demonstrated in this research that solubilization of arsenic in the subsurface soil nearby landfills in Northwest Florida would likely occur under conditions favoring Fe(III dissimilatory reduction.

  10. Robust tracking control of two-degrees-of-freedom mobile robots

    NARCIS (Netherlands)

    Oelen, W.; Oelen, W.; van Amerongen, J.

    1994-01-01

    A robust tracking controller for a mobile robot with two degrees of freedom has been developed. It is implemented and tested on a real mobile robot. Where other controllers show decreasing performance for low reference velocities, the performance of this controller depends only on the geometry of

  11. Environmental arsenic exposure from a coal-burning power plant as a potential risk factor for nonmelanoma skin carcinoma: Results from a case-control study in the district of Prievidza, Slovakia

    Energy Technology Data Exchange (ETDEWEB)

    Pesch, B.; Ranft, U.; Jakubis, P.; Nieuwenhuijsen, M.J.; Hergemoller, A.; Unfried, K.; Jakubis, M.; Miskovic, P.; Keegan, T. [University of Dusseldorf, Dusseldorf (Germany)

    2002-05-01

    To investigate the risk of arsenic exposure from a coal-burning power plant in Slovakia on nonmelanoma skin cancer (NMSC) development, a 1996-1999 population-based case-control study was conducted with 264 cases and 286 controls. Exposure assessment was based on residential history and annual emissions (Asres1, Asres2) and on nutritional habits and arsenic content in food (Asnut1, Asnut2). Asres1 was assessed as a function of the distance of places of residence to the plant. Asres2 additionally considered workplace locations. Asnut1 was used to calculate arsenic uptake by weighting food frequencies with arsenic concentrations and annual consumption of food items. Asnut2 additionally considered consumption of local products. Age- and gender-adjusted risk estimates for NMSC in the highest exposure category (90th vs. 30th percentile) were 1.90 (95% confidence interval (CI): 1.39, 2.60) for Asres1, 1.90 (95% CI: 1.38, 2.62) for Asres2, 1.19 (95% CI: 0.64, 2.12) for Asnut1, and 1.83 (95% CI: 0.98, 3.43) for Asnut2. No interaction was found between arsenic exposure and dietary and residential data. Other plant emissions could have confounded the distance-based exposure variables. Consumption of contaminated vegetables and fruits could be confounded by the protective effects of such a diet. Nevertheless, the authors found an excess NMSC risk for environmental arsenic exposure.

  12. Local system for control by console-mobile crane for russian depository of fissionable materials

    International Nuclear Information System (INIS)

    Troshchenko, V.G.; Kapustin, V.N.; Zinina, N.V.; Derbyshev, S.A.

    2005-01-01

    Description of crane of console-mobile type used for transportation of fissionable materials in depository with local control system is represented. Local control system realizes program control in real time [ru

  13. First-principles studies of di-arsenic interstitial and its implications for arsenic-interstitial diffusion in crystalline silicon

    International Nuclear Information System (INIS)

    Kim, Yonghyun; Kirichenko, Taras A.; Kong, Ning; Larson, Larry; Banerjee, Sanjay K.

    2007-01-01

    We propose new structural configurations and novel diffusion mechanisms for neutral di-arsenic interstitial (As 2 I 2 ) in silicon with a first-principle density functional theory simulation within the generalized gradient approximation. With an assumption of excess silicon interstitials and high arsenic concentrations, neutral As 2 I 2 is expected to be favorable and mobile with low-migration barrier. Moreover, because the diffusion barrier of arsenic interstitial pairs (AsI) is very low ( 2 I 2 can be easily formed and likely intermediate stage of larger arsenic interstitial clusters

  14. Three omni-directional wheels control on a mobile robot

    OpenAIRE

    Ribeiro, António Fernando; Moutinho, Ivo; Silva, Pedro; Fraga, Carlos; Pereira, Nino

    2004-01-01

    Traditional two wheels differential drive normally used on mobile robots have manoeuvrability limitations and take time to sort out. Most teams use two driving wheels (with one or two cast wheels), four driving wheels and even three driving wheels. A three wheel drive with omni-directional wheel has been tried with success, and was implemented on fast moving autonomous mobile robots. This paper deals with the mathematical kinematics description of such mobile platform, it describes the advant...

  15. Arsenic in New Jersey Coastal Plain streams, sediments, and shallow groundwater: effects from different geologic sources and anthropogenic inputs on biogeochemical and physical mobilization processes

    Science.gov (United States)

    Barringer, Julia L.; Reilly, Pamela A.; Eberl, Dennis D.; Mumford, Adam C.; Benzel, William M.; Szabo, Zoltan; Shourds, Jennifer L.; Young, Lily Y.

    2013-01-01

    Arsenic (As) concentrations in New Jersey Coastal Plain streams generally exceed the State Surface Water Quality Standard (0.017 micrograms per liter (µg/L)), but concentrations seldom exceed 1 µg/L in filtered stream-water samples, regardless of geologic contributions or anthropogenic inputs. Nevertheless, As concentrations in unfiltered stream water indicate substantial variation because of particle inputs from soils and sediments with differing As contents, and because of discharges from groundwater of widely varying chemistry.

  16. Biochars induced modification of dissolved organic matter (DOM) in soil and its impact on mobility and bioaccumulation of arsenic and cadmium.

    Science.gov (United States)

    Li, Gang; Khan, Sardar; Ibrahim, Muhammad; Sun, Tian-Ran; Tang, Jian-Feng; Cotner, James B; Xu, Yao-Yang

    2018-04-15

    Biochar application has attracted great attention due to its diverse uses and benefits in the fields of environmental management and agriculture. Biochar modifies the composition of dissolved organic matter (DOM) in soil, which directly or indirectly controls the mobility of metal contaminants and their bioaccumulation. In this study, ten different hydrothermal biochars pyrolysed from mushroom waste (MSBC), soybean straw (SBBC), sewage sludge (SSBC), peanut shells (PNBC) and rice straw (RSBC) at two pyrolysis temperatures (200 °C and 350 °C) were used to investigate DOM changes in soil solution and their effects on metal availability and bioaccumulation. Biochar induced modification of soil DOM which was characterized by spectroscopic analysis of water soluble organic carbon, specific absorbance (SUVA 254 ), UV-vis absorption, spectral slope (S R ) and the absorption coefficient. Regarding rice plant growth, the biochar effects on biomass were greatly varied. Biochars (except for RSBC and MSBC) prepared at high temperature significantly (P ≤ 0.05) suppressed the availability of As and Cd in soil and their subsequent bioaccumulation in rice plants. The highest reduction (88%) in bioaccumulated As was observed in rice grown on soil amended with SBBC prepared at 350 °C (the highest temperature for hydrothermal technique). The addition of biochars (except RSBC and MSBC) prepared at high temperature markedly (p < 0.05) decreased AsIII (30-92%), while the effects on dimethylarsenic acid (DMA) and arsenate (AsV) concentrations were not significant except for SSBC350 (prepared at 350 °C) treatment. These results highlight the potential of biochar-DOM interactions as an important mechanism for suppressing the mobility and bioaccumulation of As and Cd in biochar-amended paddy agricultural systems. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. SMR-CL, A Real-time Control Language for Mobile Robots

    DEFF Research Database (Denmark)

    Andersen, Nils Axel; Ravn, Ole

    2004-01-01

    The paper describes requirements and implementation of a tactical control lan¬guage for mobile robots. Emphasis is given to the real-time issues of the language especially the isolation of the hard real-time and the soft real-time layers of the mobile robot control system. The language may be used...

  18. Geochemistry of redox-sensitive elements and sulfur isotopes in the high arsenic groundwater system of Datong Basin, China

    International Nuclear Information System (INIS)

    Xie Xianjun; Ellis, Andre; Wang Yanxin; Xie Zuoming; Duan Mengyu; Su Chunli

    2009-01-01

    High arsenic groundwater in the Quaternary aquifers of Datong Basin, northern China contain As up to 1820 μg/L and the high concentration plume is located in the slow flowing central parts of the basin. In this study we used hydrochemical data and sulfur isotope ratios of sulfate to better understand the conditions that are likely to control arsenic mobilization. Groundwater and spring samples were collected along two flow paths from the west and east margins of the basin and a third set along the basin flow path. Arsenic concentrations range from 68 to 670 μg/L in the basin and from 3.1 to 44 μg/L in the western and eastern margins. The margins have relatively oxidized waters with low contents of arsenic, relatively high proportions of As(V) among As species, and high contents of sulfate and uranium. By contrast, the central parts of the basin are reducing with high contents of arsenic in groundwater, commonly with high proportions of As(III) among As species, and low contents of sulfate and uranium. No statistical correlations were observed between arsenic and Eh, sulfate, Fe, Mn, Mo and U. While the mobility of sulfate, uranium and molybdenum is possibly controlled by the change in redox conditions as the groundwater flows towards central parts of the basin, the reducing conditions alone cannot account for the occurrence of high arsenic groundwater in the basin but it does explain the characteristics of arsenic speciation. With one exception, all the groundwaters with As(III) as the major As species have low Eh and those with As(V) have high Eh. Reductive dissolution of Fe-oxyhydroxides or reduction of As(V) are consistent with the observations, however no increase in dissolved Fe concentration was noted. Furthermore, water from the well with the highest arsenic was relatively oxidizing and contained mostly As(V). From previous work Fe-oxyhydroxides are speculated to exist as coatings rather than primary minerals. The wide range of δ 34 S [SO4] values (from

  19. Geochemistry of redox-sensitive elements and sulfur isotopes in the high arsenic groundwater system of Datong Basin, China

    Energy Technology Data Exchange (ETDEWEB)

    Xie Xianjun [MOE Key Laboratory of Biogeology and Environmental Geology and School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); Ellis, Andre [Department of Geological Sciences, University of Texas at El Paso, TX 79968-0555 (United States); Wang Yanxin, E-mail: yx.wang@cug.edu.cn [MOE Key Laboratory of Biogeology and Environmental Geology and School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); Xie Zuoming; Duan Mengyu; Su Chunli [MOE Key Laboratory of Biogeology and Environmental Geology and School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China)

    2009-06-01

    High arsenic groundwater in the Quaternary aquifers of Datong Basin, northern China contain As up to 1820 {mu}g/L and the high concentration plume is located in the slow flowing central parts of the basin. In this study we used hydrochemical data and sulfur isotope ratios of sulfate to better understand the conditions that are likely to control arsenic mobilization. Groundwater and spring samples were collected along two flow paths from the west and east margins of the basin and a third set along the basin flow path. Arsenic concentrations range from 68 to 670 {mu}g/L in the basin and from 3.1 to 44 {mu}g/L in the western and eastern margins. The margins have relatively oxidized waters with low contents of arsenic, relatively high proportions of As(V) among As species, and high contents of sulfate and uranium. By contrast, the central parts of the basin are reducing with high contents of arsenic in groundwater, commonly with high proportions of As(III) among As species, and low contents of sulfate and uranium. No statistical correlations were observed between arsenic and Eh, sulfate, Fe, Mn, Mo and U. While the mobility of sulfate, uranium and molybdenum is possibly controlled by the change in redox conditions as the groundwater flows towards central parts of the basin, the reducing conditions alone cannot account for the occurrence of high arsenic groundwater in the basin but it does explain the characteristics of arsenic speciation. With one exception, all the groundwaters with As(III) as the major As species have low Eh and those with As(V) have high Eh. Reductive dissolution of Fe-oxyhydroxides or reduction of As(V) are consistent with the observations, however no increase in dissolved Fe concentration was noted. Furthermore, water from the well with the highest arsenic was relatively oxidizing and contained mostly As(V). From previous work Fe-oxyhydroxides are speculated to exist as coatings rather than primary minerals. The wide range of {delta}{sup 34}S

  20. Kinematics, dynamics and control design of 4WIS4WID mobile robots

    Directory of Open Access Journals (Sweden)

    Ming-Han Lee

    2015-01-01

    Full Text Available Kinematic and dynamic modelling and corresponding control design of a four-wheel-independent steering and four-wheel-independent driving (4WIS4WID mobile robot are presented in this study. Different from the differential or car-like mobile robot, the 4WIS4WID mobile robot is controlled by four steering and four driving motors, so the control scheme should possess the ability to integrate and manipulate the four independent wheels. A trajectory tracking control scheme is developed for the 4WIS4WID mobile robot, where both non-linear kinematic control and dynamic sliding-mode control are designed. All of the stabilities of the kinematic and dynamic control laws are proved by Lyapunov stability analysis. Finally, the feasibility and validity of the proposed trajectory tracking control scheme are confirmed through computer simulations.

  1. Migration control for mobile agents based on passport and visa

    OpenAIRE

    Guan, SU; Wang, T; Ong, SH

    2003-01-01

    Research on mobile agents has attracted much attention as this paradigm has demonstrated great potential for the next-generation e-commerce. Proper solutions to security-related problems become key factors in the successful deployment of mobile agents in e-commerce systems. We propose the use of passport and visa (P/V) for securing mobile agent migration across communities based on the SAFER e-commerce framework. P/V not only serves as up-to-date digital credentials for agent-host authentica...

  2. Arsenic burden survey among refuse incinerator workers

    Directory of Open Access Journals (Sweden)

    Chao Chung-Liang

    2005-01-01

    Full Text Available Background: Incinerator workers are not considered to have arsenic overexposure although they have the risk of overexposure to other heavy metals. Aim: To examine the relationship between arsenic burden and risk of occupational exposure in employees working at a municipal refuse incinerator by determining the concentrations of arsenic in the blood and urine. Settings and Design: The workers were divided into three groups based on their probability of contact with combustion-generated residues, namely Group 1: indirect contact, Group 2: direct contact and Group 3: no contact. Healthy age- and sex-matched residents living in the vicinity were enrolled as the control group. Materials and Methods: Heavy metal concentrations were measured by atomic absorption spectrophotometer. Downstream rivers and drinking water of the residents were examined for environmental arsenic pollution. A questionnaire survey concerning the contact history of arsenic was simultaneously conducted. Statistical analysis: Non-parametric tests, cross-tabulation and multinomial logistic regression. Results: This study recruited 122 incinerator workers. The urine and blood arsenic concentrations as well as incidences of overexposure were significantly higher in the workers than in control subjects. The workers who had indirect or no contact with combustion-generated residues had significantly higher blood arsenic level. Arsenic contact history could not explain the difference. Airborne and waterborne arsenic pollution were not detected. Conclusion: Incinerator workers run the risk of being exposed to arsenic pollution, especially those who have incomplete protection in the workplace even though they only have indirect or no contact with combustion-generated pollutants.

  3. Real-time Non-linear Target Tracking Control of Wheeled Mobile Robots

    Institute of Scientific and Technical Information of China (English)

    YU Wenyong

    2006-01-01

    A control strategy for real-time target tracking for wheeled mobile robots is presented. Using a modified Kalman filter for environment perception, a novel tracking control law derived from Lyapunov stability theory is introduced. Tuning of linear velocity and angular velocity with mechanical constraints is applied. The proposed control system can simultaneously solve the target trajectory prediction, real-time tracking, and posture regulation problems of a wheeled mobile robot. Experimental results illustrate the effectiveness of the proposed tracking control laws.

  4. Spread and Control of Mobile Benign Worm Based on Two-Stage Repairing Mechanism

    Directory of Open Access Journals (Sweden)

    Meng Wang

    2014-01-01

    Full Text Available Both in traditional social network and in mobile network environment, the worm is a serious threat, and this threat is growing all the time. Mobile smartphones generally promote the development of mobile network. The traditional antivirus technologies have become powerless when facing mobile networks. The development of benign worms, especially active benign worms and passive benign worms, has become a new network security measure. In this paper, we focused on the spread of worm in mobile environment and proposed the benign worm control and repair mechanism. The control process of mobile benign worms is divided into two stages: the first stage is rapid repair control, which uses active benign worm to deal with malicious worm in the mobile network; when the network is relatively stable, it enters the second stage of postrepair and uses passive mode to optimize the environment for the purpose of controlling the mobile network. Considering whether the existence of benign worm, we simplified the model and analyzed the four situations. Finally, we use simulation to verify the model. This control mechanism for benign worm propagation is of guiding significance to control the network security.

  5. Urinary arsenic profile affects the risk of urothelial carcinoma even at low arsenic exposure

    International Nuclear Information System (INIS)

    Pu, Y.-S.; Yang, S.-M.; Huang, Y.-K.; Chung, C.-J.; Huang, Steven K.; Chiu, Allen Wen-Hsiang; Yang, M.-H.; Chen, C.-J.; Hsueh, Y.-M.

    2007-01-01

    Arsenic exposure is associated with an increased risk of urothelial carcinoma (UC). To explore the association between individual risk and urinary arsenic profile in subjects without evident exposure, 177 UC cases and 313 age-matched controls were recruited between September 2002 and May 2004 for a case-control study. Urinary arsenic species including the following three categories, inorganic arsenic (As III + As V ), monomethylarsonic acid (MMA V ) and dimethylarsinic acid (DMA V ), were determined with high-performance liquid chromatography-linked hydride generator and atomic absorption spectrometry. Arsenic methylation profile was assessed by percentages of various arsenic species in the sum of the three categories measured. The primary methylation index (PMI) was defined as the ratio between MMA V and inorganic arsenic. Secondary methylation index (SMI) was determined as the ratio between DMA V and MMA V . Smoking is associated with a significant risk of UC in a dose-dependent manner. After multivariate adjustment, UC cases had a significantly higher sum of all the urinary species measured, higher percent MMA V , lower percent DMA V , higher PMI and lower SMI values compared with controls. Smoking interacts with the urinary arsenic profile in modifying the UC risk. Differential carcinogenic effects of the urinary arsenic profile, however, were seen more prominently in non-smokers than in smokers, suggesting that smoking is not the only major environmental source of arsenic contamination since the UC risk differs in non-smokers. Subjects who have an unfavorable urinary arsenic profile have an increased UC risk even at low exposure levels

  6. The impact of oscillating redox conditions: Arsenic immobilisation in contaminated calcareous floodplain soils

    International Nuclear Information System (INIS)

    Parsons, Christopher T.; Couture, Raoul-Marie; Omoregie, Enoma O.; Bardelli, Fabrizio; Greneche, Jean-Marc; Roman-Ross, Gabriela; Charlet, Laurent

    2013-01-01

    Arsenic contamination of floodplain soils is extensive and additional fresh arsenic inputs to the pedosphere from human activities are ongoing. We investigate the cumulative effects of repetitive soil redox cycles, which occur naturally during flooding and draining, on a calcareous fluvisol, the native microbial community and arsenic mobility following a simulated contamination event. We show through bioreactor experiments, spectroscopic techniques and modelling that repetitive redox cycling can decrease arsenic mobility during reducing conditions by up to 45%. Phylogenetic and functional analyses of the microbial community indicate that iron cycling is a key driver of observed changes to solution chemistry. We discuss probable mechanisms responsible for the arsenic immobilisation observed in-situ. The proposed mechanisms include, decreased heterotrophic iron reduction due to the depletion of labile particulate organic matter (POM), increases to the proportion of co-precipitated vs. aqueous or sorbed arsenic with α-FeOOH/Fe(OH) 3 and potential precipitation of amorphous ferric arsenate. Highlights: •Oscillating redox conditions and heterotrophic metabolism are implemented in PHREEQC. •Depletion of labile organic matter limits iron reduction and arsenic release. •Amorphous FeAsO 4 ∙2H 2 O precipitation potentially limits arsenic mobility during redox cycling. •Water fluctuating zones may naturally attenuate arsenic liberation during flooding. -- We demonstrate through batch experiments, spectroscopy and modelling that repetitive cycles of oxidation and reduction decrease arsenic mobility in soils during subsequent reducing conditions

  7. Arsenic: natural and anthropogenic

    National Research Council Canada - National Science Library

    Matschullat, Jörg; Deschamps, Eleonora

    2011-01-01

    .... Based on state-of-the-art investigations into the global arsenic cycle, the related human toxicology and available remediation technologies, it assesses arsenic in all the environmental compartments...

  8. ARSENIC RESEARCH AT GWERD

    Science.gov (United States)

    Abstract - The presentation will summarize the arsenic research program at the Ground Water & Ecosystems Restoration Division of the National Risk Management Research Laboratory of USEPA. Topics include use of permeable reactive barriers for in situ arsenic remediation in ground...

  9. Induction of Human Squamous Cell-Type Carcinomas by Arsenic

    International Nuclear Information System (INIS)

    Martinez, V. D.; Becker-Santos, D. D.; Vucic, E. A.; Lam, S.; Lam, W. L.

    2011-01-01

    Arsenic is a potent human carcinogen. Around one hundred million people worldwide have potentially been exposed to this metalloid at concentrations considered unsafe. Exposure occurs generally through drinking water from natural geological sources, making it difficult to control this contamination. Arsenic biotransformation is suspected to have a role in arsenic-related health effects ranging from acute toxicities to development of malignancies associated with chronic exposure. It has been demonstrated that arsenic exhibits preference for induction of squamous cell carcinomas in the human, especially skin and lung cancer. Interestingly, keratins emerge as a relevant factor in this arsenic-related squamous cell-type preference. Additionally, both genomic and epi genomic alterations have been associated with arsenic-driven neoplastic process. Some of these aberrations, as well as changes in other factors such as keratins, could explain the association between arsenic and squamous cell carcinomas in humans.

  10. Method development for arsenic analysis by modification in spectrophotometric technique

    Directory of Open Access Journals (Sweden)

    M. A. Tahir

    2012-01-01

    Full Text Available Arsenic is a non-metallic constituent, present naturally in groundwater due to some minerals and rocks. Arsenic is not geologically uncommon and occurs in natural water as arsenate and arsenite. Additionally, arsenic may occur from industrial discharges or insecticide application. World Health Organization (WHO and Pakistan Standard Quality Control Authority have recommended a permissible limit of 10 ppb for arsenic in drinking water. Arsenic at lower concentrations can be determined in water by using high tech instruments like the Atomic Absorption Spectrometer (hydride generation. Because arsenic concentration at low limits of 1 ppb can not be determined easily with simple spectrophotometric technique, the spectrophotometric technique using silver diethyldithiocarbamate was modified to achieve better results, up to the extent of 1 ppb arsenic concentration.

  11. Bacteria, hypertolerant to arsenic in the rocks of an ancient gold mine, and their potential role in dissemination of arsenic pollution

    International Nuclear Information System (INIS)

    Drewniak, Lukasz; Styczek, Aleksandra; Majder-Lopatka, Malgorzata; Sklodowska, Aleksandra

    2008-01-01

    The aim of the present study was to find out if bacteria present in ancient gold mine could transform immobilized arsenic into its mobile form and increase its dissemination in the environment. Twenty-two arsenic-hypertolerant cultivable bacterial strains were isolated. No chemolithoautotrophs, which could use arsenite as an electron donor as well as arsenate as an electron acceptor, were identified. Five isolates exhibited hypertolerance to arsenic: up to 500 mM of arsenate. A correlation between the presence of siderophores and high resistance to arsenic was found. The results of this study show that detoxification processes based on arsenate reductase activity might be significant in dissemination of arsenic pollution. It was concluded that the activity of the described heterotrophic bacteria contributes to the mobilization of arsenic in the more toxic As(III) form and a new mechanism of arsenic mobilization from a scorodite was proposed. - The activity of the described heterotrophic bacteria leads to mobilization of arsenic and in this way contributes to the dissemination of arsenic pollution

  12. Multimodal exercise training in multiple sclerosis: A randomized controlled trial in persons with substantial mobility disability.

    Science.gov (United States)

    Sandroff, Brian M; Bollaert, Rachel E; Pilutti, Lara A; Peterson, Melissa L; Baynard, Tracy; Fernhall, Bo; McAuley, Edward; Motl, Robert W

    2017-10-01

    Mobility disability is a common, debilitating feature of multiple sclerosis (MS). Exercise training has been identified as an approach to improve MS-related mobility disability. However, exercise randomized controlled trials (RCTs) on mobility in MS have generally not selectively targeted those with the onset of irreversible mobility disability. The current multi-site RCT compared the efficacy of 6-months of supervised, multimodal exercise training with an active control condition for improving mobility, gait, physical fitness, and cognitive outcomes in persons with substantial MS-related mobility disability. 83 participants with substantial MS-related mobility disability underwent initial mobility, gait, fitness, and cognitive processing speed assessments and were randomly assigned to 6-months of supervised multimodal (progressive aerobic, resistance, and balance) exercise training (intervention condition) or stretching-and-toning activities (control condition). Participants completed the same outcome assessments halfway through and immediately following the 6-month study period. There were statistically significant improvements in six-minute walk performance (F(2158)=3.12, p=0.05, η p 2 =0.04), peak power output (F(2150)=8.16, pmobility disability. This is critical for informing the development of multi-site exercise rehabilitation programs in larger samples of persons with MS-related mobility disability. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Difficulties in controlling mobilization pain using a standardized patient-controlled analgesia protocol in burns.

    Science.gov (United States)

    Nilsson, Andreas; Kalman, Sigga; Sonesson, Lena Karin; Arvidsson, Anders; Sjöberg, Folke

    2011-01-01

    The aim of this study was to evaluate pain relief for patients with burns during rest and mobilization with morphine according to a standard protocol for patient-controlled analgesia (PCA). Eighteen patients with a mean (SD) burned TBSA% of 26 (20) were studied for 10 days. Using a numeric rating scale (NRS, 0 = no pain and 10 = unbearable pain), patients were asked to estimate their acceptable and worst experienced pain by specifying a number on a scale and at what point they would like additional analgesics. Patients were allowed free access to morphine with a PCA pump device. Bolus doses were set according to age, (100 - age)/24 = bolus dose (mg), and 6 minutes lockout time. Degrees of pain, morphine requirements, doses delivered and demanded, oral intake of food, and antiemetics given were used as endpoints. Acceptable pain (mean [SD]) was estimated to be 3.8 (1.3) on the NRS, and additional treatment was considered necessary at scores of 4.3 (1.6) or more. NRS at rest was 2.7 (2.2) and during mobilization 4.7 (2.6). Required mean morphine per day was 81 (15) mg, and the number of doses requested increased during the first 6 days after the burn. The authors found no correlation between dose of morphine required and any other variables. Background pain can be controlled adequately with a standard PCA protocol. During mobilization, the pain experienced was too intense, despite having the already high doses of morphine increased. The present protocol must be refined further to provide analgesia adequate to cover mobilization as well.

  14. Leaching characteristics of encapsulated controlled low-strength materials containing arsenic-bearing waste precipitates from refractory gold bioleaching.

    Science.gov (United States)

    Bouzalakos, S; Dudeney, A W L; Chan, B K C

    2016-07-01

    We report on the leaching of heavy elements from cemented waste flowable fill, known as controlled low-strength materials (CLSM), for potential mine backfill application. Semi-dynamic tank leaching tests were carried out on laboratory-scale monoliths cured for 28 days and tested over 64 days of leaching with pure de-ionised water as leachant. Mineral processing waste include flotation tailings from a Spanish nickel-copper sulphide concentrate, and two bioleach neutralisation precipitates (from processing at 35°C and 70°C) from a South African arsenopyrite concentrate. Encapsulated CLSM formulations were evaluated to assess the reduction in leaching by encapsulating a 'hazardous' CLSM core within a layer of relatively 'inert' CLSM. The effect of each bioleach waste in CLSM core and tailings in CLSM encapsulating medium, are assessed in combination and in addition to CLSM with ordinary silica sand. Results show that replacing silica sand with tailings, both as core and encapsulating matrix, significantly reduced leachability of heavy elements, particularly As (from 0.008-0.190 mg/l to 0.008-0.060 mg/l), Ba (from 0.435-1.540 mg/l to 0.050-0.565 mg/l), and Cr (from 0.006-0.458 mg/l to 0.004-0.229 mg/l), to below the 'Dutch List' of groundwater contamination intervention values. Arsenic leaching was inherently high from both bioleach precipitates but was significantly reduced to below guideline values with encapsulation and replacing silica sand with tailings. Tailings proved to be a valuable encapsulating matrix largely owing to small particle size and lower hydraulic conductivity reducing diffusion transport of heavy elements. Field-scale trials would be necessary to prove this concept of encapsulation in terms of scale and construction practicalities, and further geochemical investigation to optimise leaching performance. Nevertheless, this work substantiates the need for alternative backfill techniques for sustainable management of hazardous finely-sized bulk

  15. Mussel tissue (T-31) - A new analytical quality control material for the determination of mercury and arsenic in mussels

    Energy Technology Data Exchange (ETDEWEB)

    Gawlik, B. [Joint Research Centre Ispra, Ispra, Varese (Italy). Environment Institute]|[Muenchen, Technische Universitaet (Germany). Lehrstuhl fuer Oekologische Chemie und Umweltanalytik; Druges, M. [Thomson Microelectronics, Crolles (France); Bianchi, M.; Muntau, H. [Joint Research Centre Ispra, Ispra, Varese (Italy). Environment Institute; Bortoli, A. [ULSS 12, Venice (Italy). Presidio Multizonale di Prevenzione; Kettrup, A. [Muenchen, Technische Universitaet (Germany). Lehrstuhl fur Oekologische Chemie und Umweltanalytik]|[GSF Forschungszentrum fuer Umwelt und Gesundheit, Oberschleissheim (Germany). Inst. fuer Oekologische Chemie

    1998-05-01

    The use of filter-feeding molluscs for the monitoring of selected contaminant levels in the marine environment is well-known in the scientific community. In the order to assure the quality of those analysis and to prepare laboratories for accreditation procedures certified reference materials and proficiency testing campaigns were introduced. However, there is still a need for the introduction of suitable analytical quality materials of high quality which can be used on a daily basis. This paper therefore describes the preparation of a mussel tissue material for the internal quality control of Hg and As analysis in bivalves, as well as the principle of preparation and the analytical characterisation of such a material. The total concentration for arsenic (8.98 {+-} 0.67 {mu}g/g) and mercury (0.169 {+-} 0.005 {mu}g/g) was determined by the use of different techniques. Additionally, indicative values for major constituents (C, H, N, Na, Cl, P, S, K, Mg, Ca, Si, Fe, Al, Br, Zn, Sr) and some trace elements (Cu, Cd, Pb, Ni) were measured. [Italiano] L`uso di molluschi filtratori nel monitoraggio dei livelli di contaminazione in ambiente marino e` ben noto in ambito scientifico. Per assicurare la qualita` di queste analisi e preparare i laboratori alle procedure di accreditamento e stato introdotto l`uso di materiali di riferimento certificati accoppiato alla partecipazione a campagne di controllo interlaboratoriale. Attualmente non sono ancora disponibili materiali di riferimento appropriati e di alta qualita`, che possano essere usati su base quotidiana. Questo lavoro descrive la preparazione di un materiale di riferimanto di cozze da usare come mezzo di controllo di qualita` interna e i principi di preparazione e di caratterizzazione analitica di un materiale di questo tipo. La concentrazione totale dell`arsenico (8.98 {+-} 0.67 {mu}g/g) e del mercurio (0.169 {+-} 0.005 {mu}g/g) sono state determinati mediante l`uso di differenti tecniche. Sono stati in oltre misurati

  16. Establishment of Groundwater Arsenic Potential Distribution and Discrimination in Taiwan

    Science.gov (United States)

    Tsai, Kuo Sheng; Chen, Yu Ying; Chung Liu, Chih; Lin, Chien Wen

    2016-04-01

    According to the last 10 years groundwater monitoring data in Taiwan, Arsenic concentration increase rapidly in some areas, similar to Bengal and India, the main source of Arsenic-polluted groundwater is geological sediments, through reducing reactions. There are many researches indicate that high concentration of Arsenic in groundwater poses the risk to water safety, for example, the farm lands irrigation water contains Arsenic cause the concentration of Arsenic increase in soil and crops. Based on the management of water usage instead of remediation in the situation of insufficient water. Taiwan EPA has been developed the procedures of Arsenic contamination potential area establishment and source discriminated process. Taiwan EPA use the procedures to determine the management of using groundwater, and the proposing usage of Arsenic groundwater accordance with different objects. Agencies could cooperate with the water quality standard or water needs, studying appropriate water purification methods and the groundwater depth, water consumption, thus achieve the goal of water safety and environmental protection, as a reference of policy to control total Arsenic concentration in groundwater. Keywords: Arsenic; Distribution; Discrimination; Pollution potential area of Arsenic; Origin evaluation of groundwater Arsenic

  17. Web Environment for Programming and Control of a Mobile Robot in a Remote Laboratory

    Science.gov (United States)

    dos Santos Lopes, Maísa Soares; Gomes, Iago Pacheco; Trindade, Roque M. P.; da Silva, Alzira F.; de C. Lima, Antonio C.

    2017-01-01

    Remote robotics laboratories have been successfully used for engineering education. However, few of them use mobile robots to to teach computer science. This article describes a mobile robot Control and Programming Environment (CPE) and its pedagogical applications. The system comprises a remote laboratory for robotics, an online programming tool,…

  18. Significantly increased risk of carotid atherosclerosis with arsenic exposure and polymorphisms in arsenic metabolism genes

    International Nuclear Information System (INIS)

    Hsieh, Yi-Chen; Lien, Li-Ming; Chung, Wen-Ting; Hsieh, Fang-I; Hsieh, Pei-Fan; Wu, Meei-Maan; Tseng, Hung-Pin; Chiou, Hung-Yi; Chen, Chien-Jen

    2011-01-01

    Individual susceptibility to arsenic-induced carotid atherosclerosis might be associated with genetic variations in arsenic metabolism. The purpose of this study is to explore the interaction effect on risk of carotid atherosclerosis between arsenic exposure and risk genotypes of purine nucleoside phosphorylase (PNP), arsenic (+3) methyltransferase (As3MT), and glutathione S-transferase omega 1 (GSTO1) and omega 2 (GSTO2). A community-based case-control study was conducted in northeastern Taiwan to investigate the arsenic metabolic-related genetic susceptibility to carotid atherosclerosis. In total, 863 subjects, who had been genotyped and for whom the severity of carotid atherosclerosis had been determined, were included in the present study. Individual well water was collected and arsenic concentration determined using hydride generation combined with flame atomic absorption spectrometry. The result showed that a significant dose-response trend (P=0.04) of carotid atherosclerosis risk associated with increasing arsenic concentration. Non-significant association between genetic polymorphisms of PNP Gly51Ser, Pro57Pro, As3MT Met287Thr, GSTO1 Ala140Asp, and GSTO2 A-183G and the risk for development of carotid atherosclerosis were observed. However, the significant interaction effect on carotid atherosclerosis risk was found for arsenic exposure (>50 μg/l) and the haplotypes of PNP (p=0.0115). A marked elevated risk of carotid atherosclerosis was observed in subjects with arsenic exposure of >50 μg/l in drinking water and those who carried the PNP A-T haplotype and at least either of the As3MT risk polymorphism or GSTO risk haplotypes (OR, 6.43; 95% CI, 1.79-23.19). In conclusion, arsenic metabolic genes, PNP, As3MT, and GSTO, may exacerbate the formation of atherosclerosis in individuals with high levels of arsenic concentration in well water (>50 μg/l). - Highlights: →Arsenic metabolic genes might be associated with carotid atherosclerosis. → A case-control

  19. Significantly increased risk of carotid atherosclerosis with arsenic exposure and polymorphisms in arsenic metabolism genes

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Yi-Chen [School of Public Health, College of Public Health and Nutrition, Taipei Medical University, 250 Wusing St., Taipei 11031, Taiwan (China); Lien, Li-Ming [Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan (China); School of Medicine, Taipei Medical University, Taipei, Taiwan (China); Department of Neurology, Shin Kong WHS Memorial Hospital, Taipei, Taiwan (China); Chung, Wen-Ting [Department of Neurology, Wanfang Hospital, Taipei Medical University, Taipei, Taiwan (China); Graduate Institute of Clinical Medicine, Taipei Medical University, Taipei, Taiwan (China); Hsieh, Fang-I; Hsieh, Pei-Fan [School of Public Health, College of Public Health and Nutrition, Taipei Medical University, 250 Wusing St., Taipei 11031, Taiwan (China); Wu, Meei-Maan [School of Public Health, College of Public Health and Nutrition, Taipei Medical University, 250 Wusing St., Taipei 11031, Taiwan (China); Graduate Institute of Basic Medicine, College of Medicine, Fu-Jen Catholic University, Taipei, Taiwan (China); Tseng, Hung-Pin [Department of Neurology, Lotung Poh-Ai Hospital, I-Lan, Taiwan (China); Chiou, Hung-Yi, E-mail: hychiou@tmu.edu.tw [School of Public Health, College of Public Health and Nutrition, Taipei Medical University, 250 Wusing St., Taipei 11031, Taiwan (China); Chen, Chien-Jen [Genomics Research Center, Academia Sinica, Taipei, Taiwan (China)

    2011-08-15

    Individual susceptibility to arsenic-induced carotid atherosclerosis might be associated with genetic variations in arsenic metabolism. The purpose of this study is to explore the interaction effect on risk of carotid atherosclerosis between arsenic exposure and risk genotypes of purine nucleoside phosphorylase (PNP), arsenic (+3) methyltransferase (As3MT), and glutathione S-transferase omega 1 (GSTO1) and omega 2 (GSTO2). A community-based case-control study was conducted in northeastern Taiwan to investigate the arsenic metabolic-related genetic susceptibility to carotid atherosclerosis. In total, 863 subjects, who had been genotyped and for whom the severity of carotid atherosclerosis had been determined, were included in the present study. Individual well water was collected and arsenic concentration determined using hydride generation combined with flame atomic absorption spectrometry. The result showed that a significant dose-response trend (P=0.04) of carotid atherosclerosis risk associated with increasing arsenic concentration. Non-significant association between genetic polymorphisms of PNP Gly51Ser, Pro57Pro, As3MT Met287Thr, GSTO1 Ala140Asp, and GSTO2 A-183G and the risk for development of carotid atherosclerosis were observed. However, the significant interaction effect on carotid atherosclerosis risk was found for arsenic exposure (>50 {mu}g/l) and the haplotypes of PNP (p=0.0115). A marked elevated risk of carotid atherosclerosis was observed in subjects with arsenic exposure of >50 {mu}g/l in drinking water and those who carried the PNP A-T haplotype and at least either of the As3MT risk polymorphism or GSTO risk haplotypes (OR, 6.43; 95% CI, 1.79-23.19). In conclusion, arsenic metabolic genes, PNP, As3MT, and GSTO, may exacerbate the formation of atherosclerosis in individuals with high levels of arsenic concentration in well water (>50 {mu}g/l). - Highlights: {yields}Arsenic metabolic genes might be associated with carotid atherosclerosis. {yields

  20. Arsenic enrichment and mobilization in the Holocene alluvial aquifers of the Chapai-Nawabganj district, Bangladesh: A geochemical and statistical study

    International Nuclear Information System (INIS)

    Reza, A.H.M. Selim; Jean, Jiin-Shuh; Lee, Ming-Kuo; Yang, Huai-Jen; Liu, Chia-Chuan

    2010-01-01

    Research highlights: → Four factors (i.e., salinity factor, As-enrichment factor, reduction factor, and hardness factor) control groundwater geochemistry. → Hydrochemical facies analysis showed that most of the water samples are dominated by Ca and HCO 3 ions. → Cluster 1 water types are highly enriched in As; an alternative water source is thus needed for domestic water supply. Possible solutions are to install tube wells in the deeper Pleistocene aquifers or use clean surface water sources such as reservoirs or rain water. → Cluster 4 water types contain low concentration As, below the Bangladesh standard ( 4 , total dissolved solids (TDS), and electrical conductivity (EC) are grouped under the first factor representing the salinity sources of waters. The second factor, represented by As and Mn, is related to As mobilization processes. The third factor of Fe and alkalinity is strongly influenced by bacterial Fe(III) reduction which would raise both Fe and HCO 3 - concentrations in water. The fourth factor of Ca and Mg reflects the hardness of the Ca-HCO 3 type of groundwater, which is confirmed by the hydrochemical facies analysis. Cluster analysis leads to the formulation of four water types including highly, moderately, and slightly As-enriched groundwater as well as groundwater with elevated SO 4 2- , from anthropogenic sources. Multivariate analyses of the geochemical parameters suggest that Fe- and Mn-oxyhydroxides and mineral phases of phyllosilicates (e.g., biotite) are the main hosts of As in the sediments. Statistical analysis also shows that As is closely associated with Fe and Mn in sediments while As is positively correlated with Mn in groundwater. These correlations along with results of sequential leaching experiments suggest that reductive dissolution of MnOOH and FeOOH mediated by anaerobic bacteria represents an important mechanism for releasing As into the groundwater.

  1. Difficulties in Controlling Mobilization Pain Using a Standardized Patient-Controlled Analgesia Protocol in Burns

    OpenAIRE

    Nilsson, Andreas; Kalman, Sigga; Arvidsson, Anders; Sjöberg, Folke

    2011-01-01

    The aim of this study was to evaluate pain relief for patients with burns during rest and mobilization with morphine according to a standard protocol for patient-controlled analgesia (PCA). Eighteen patients with a mean (SD) burned TBSA% of 26 (20) were studied for 10 days. Using a numeric rating scale (NRS, 0 = no pain and 10 = unbearable pain), patients were asked to estimate their acceptable and worst experienced pain by specifying a number on a scale and at what point they would like addi...

  2. Microbial Community Structure and Arsenic Biogeochemistry in Two Arsenic-Impacted Aquifers in Bangladesh

    Directory of Open Access Journals (Sweden)

    Edwin T. Gnanaprakasam

    2017-11-01

    Full Text Available Long-term exposure to trace levels of arsenic (As in shallow groundwater used for drinking and irrigation puts millions of people at risk of chronic disease. Although microbial processes are implicated in mobilizing arsenic from aquifer sediments into groundwater, the precise mechanism remains ambiguous. The goal of this work was to target, for the first time, a comprehensive suite of state-of-the-art molecular techniques in order to better constrain the relationship between indigenous microbial communities and the iron and arsenic mineral phases present in sediments at two well-characterized arsenic-impacted aquifers in Bangladesh. At both sites, arsenate [As(V] was the major species of As present in sediments at depths with low aqueous As concentrations, while most sediment As was arsenite [As(III] at depths with elevated aqueous As concentrations. This is consistent with a role for the microbial As(V reduction in mobilizing arsenic. 16S rRNA gene analysis indicates that the arsenic-rich sediments were colonized by diverse bacterial communities implicated in both dissimilatory Fe(III and As(V reduction, while the correlation analyses involved phylogenetic groups not normally associated with As mobilization. Findings suggest that direct As redox transformations are central to arsenic fate and transport and that there is a residual reactive pool of both As(V and Fe(III in deeper sediments that could be released by microbial respiration in response to hydrologic perturbation, such as increased groundwater pumping that introduces reactive organic carbon to depth.

  3. Hybrid Control Design for a Wheeled Mobile Robot

    DEFF Research Database (Denmark)

    Bak, Thomas; Bendtsen, Jan Dimon; Ravn, Anders Peter

    We present a hybrid systems solution to the problem of trajectory tracking for a four-wheel steered four-wheel driven mobile robot. The robot is modelled as a non-holonomic dynamic system subject to pure rolling, no-slip constraints. Under normal driving conditions, a nonlinear trajectory tracking...

  4. Hybrid Control Design for a Wheeled Mobile Robot

    DEFF Research Database (Denmark)

    Bak, Thomas; Bendtsen, Jan Dimon; Ravn, Anders Peter

    2003-01-01

    We present a hybrid systems solution to the problem of trajectory tracking for a four-wheel steered four-wheel driven mobile robot. The robot is modelled as a non-holonomic dynamic system subject to pure rolling, no-slip constraints. Under normal driving conditions, a nonlinear trajectory tracking...

  5. Control design for a mobile robot Including tire behavior

    NARCIS (Netherlands)

    Ploeg, J.; Schouten, H.E.; Nijmeijer, H.

    2008-01-01

    In order to support the development process of Advanced Driver Assistance systems for road vehicles, TNO is operating a hardware-in-the-loop test setup. In this facility, called VeHIL, vehicles in the direct neighborhood of the test vehicle are simulated using wheeled mobile robots. Due to the

  6. Control design for a mobile robot including tire behavior

    NARCIS (Netherlands)

    Ploeg, J.; Schouten, H.E.; Nijmeijer, H.

    2008-01-01

    In order to support the development process of Advanced Driver Assistance systems for road vehicles, TNO is operating a hardware-in-the-loop test setup. In this facility, called VeHIL, vehicles in the direct neighborhood of the test vehicle are simulated using wheeled mobile robots. Due to the

  7. Hybrid Control Design for a Wheeled Mobile Robot

    DEFF Research Database (Denmark)

    Bak, Thomas; Bendtsen, Jan Dimon; Ravn, Anders Peter

    2003-01-01

    We present a hybrid systems solution to the problem of trajectory tracking for a four-wheel steered four-wheel driven mobile robot. The robot is modelled as a non-holonomic dynamic system subject to pure rolling, no-slip constraints. Under normal driving conditions, a nonlinear trajectory trackin...

  8. Interface-controlled, high-mobility organic transistors

    NARCIS (Netherlands)

    Jurchescu, Oana D.; Popinciuc, Mihaita; van Wees, Bart J.; Palstra, Thomas T. M.

    2007-01-01

    The achievement of high mobilities in field-effect transistors (FETs) is one of the main challenges for the widespread application of organic conductors in devices. Good device performance of a single-crystal pentacene FET requires both removal of impurity molecules from the bulk and the

  9. Removal of Arsenic from Drinking Water by Adsorption and Coagulation

    Science.gov (United States)

    Zhang, M.; Sugita, H.; Hara, J.; Takahashi, S.

    2013-12-01

    Removal of arsenic from drinking water has been an important issue worldwide, which has attracted greater attentions in recent years especially for supplying safe drinking water in developing countries. Although many kinds of treatment approaches that are available or applicable both in principle and practice, such as adsorption, coagulation, membrane filtration, ion exchange, biological process, electrocoagulation and so on, the first 2 approaches (i.e., adsorption and coagulation) are most promising due to the low-cost, high-efficiency, simplicity of treating systems, and thus can be practically used in developing countries. In this study, a literature survey on water quality in Bangladesh was performed to understand the ranges of arsenic concentration and pH of groundwater in Bangladesh. A series of tests were then organized and performed to investigate the effects of arsenic concentration, arsenic forms, pH, chemical compositions of the materials used for adsorption and coagulation, particle size distribution and treatment time on quality of treated water. The experimental results obtained in the study illustrated that both adsorption and coagulation can be used to effectively reduce the concentrations of either arsenic (V) or arsenic (III) from the contaminated water. Coagulation of arsenic with a magnesium-based material developed in this study can be very effective to remove arsenic, especially arsenic (V), from contaminated water with a concentration of 10 ppm to an undetectable level of 0.002 ppm by ICP analyses. Compared to arsenic (III), arsenic (V) is easier to be removed. The materials used for adsorption and coagulation in this study can remove arsenic (V) up to 9 mg/g and 6 mg/g, and arsenic (III) up to 4 mg/g and 3 mg/g, respectively, depending on test conditions and compositions of the materials being used. The control of pH during treatment can be a challenging technical issue for developing both adsorbent and coagulant. Keywords: Water Treatment

  10. Effects of Nrf2 deficiency on arsenic metabolism in mice.

    Science.gov (United States)

    Wang, Huihui; Zhu, Jiayu; Li, Lu; Li, Yongfang; Lv, Hang; Xu, Yuanyuan; Sun, Guifan; Pi, Jingbo

    2017-12-15

    Inorganic arsenic (iAs) is a known toxicant and carcinogen. Worldwide arsenic exposure has become a threat to human health. The severity of arsenic toxicity is strongly correlated with the speed of arsenic metabolism (methylation) and clearance. Furthermore, oxidative stress is recognized as a major mechanism for arsenic-induced toxicity. Nuclear factor-E2-related factor 2 (Nrf2), a key regulator in cellular adaptive antioxidant response, is clearly involved in alleviation of arsenic-induced oxidative damage. Multiple studies demonstrate that Nrf2 deficiency mice are more vulnerable to arsenic-induced intoxication. However, what effect Nrf2 deficiency might have on arsenic metabolism in mice is still unknown. In the present study, we measured the key enzymes involved in arsenic metabolism in Nrf2-WT and Nrf2-KO mice. Our results showed that basal transcript levels of glutathione S-transferase omega 2 (Gsto2) were significantly higher and GST mu 1 (Gstm1) lower in Nrf2-KO mice compared to Nrf2-WT control. Arsenic speciation and methylation rate in liver and urine was then studied in mice treated with 5mg/kg sodium arsenite for 12h. Although there were some alterations in arsenic metabolism enzymes between Nrf2-WT and Nrf2-KO mice, the Nrf2 deficiency had no significant effect on arsenic methylation. These results suggest that the Nrf2-KO mice are more sensitive to arsenic than Nrf2-WT mainly because of differences in adaptive antioxidant detoxification capacity rather than arsenic methylation capacity. Copyright © 2017. Published by Elsevier Inc.

  11. Decentralized coverage control problems for mobile robotic sensor and actuator networks

    CERN Document Server

    Savkin, A; Xi, Z; Javed, F; Matveev, A; Nguyen, H

    2015-01-01

    This book introduces various coverage control problems for mobile sensor networks including barrier, sweep and blanket. Unlike many existing algorithms, all of the robotic sensor and actuator motion algorithms developed in the book are fully decentralized or distributed, computationally efficient, easily implementable in engineering practice and based only on information on the closest neighbours of each mobile sensor and actuator and local information about the environment. Moreover, the mobile robotic sensors have no prior information about the environment in which they operation. These various types of coverage problems have never been covered before by a single book in a systematic way. Another topic of this book is the study of mobile robotic sensor and actuator networks. Many modern engineering applications include the use of sensor and actuator networks to provide efficient and effective monitoring and control of industrial and environmental processes. Such mobile sensor and actuator networks are abl...

  12. Path tracking control of mobile robots with techniques based on the use of curved abscissa

    International Nuclear Information System (INIS)

    Micaelli, A.

    1992-01-01

    The paper describes a particular method, developed by the CEA, for the control of mobile robot trajectories based on Cornu's spiral, i.e; sections of trajectories with constant curvature. New approaches are discussed for methods more convenient

  13. Learning Mobility: Adaptive Control Algorithms for the Novel Unmanned Ground Vehicle (NUGV)

    National Research Council Canada - National Science Library

    Blackburn, Mike

    2003-01-01

    Mobility is a serious limiting factor in the usefulness of unmanned ground vehicles, This paper contains a description of our approach to develop control algorithms for the Novel Unmanned Ground Vehicle (NUGV...

  14. Consensus Formation Control for a Class of Networked Multiple Mobile Robot Systems

    Directory of Open Access Journals (Sweden)

    Long Sheng

    2012-01-01

    for investigating the sufficient conditions to linear control gain design for the system with constant time delays. Simulation results as well as experimental studies on Pioneer 3 series mobile robots are shown to verify the effectiveness of the proposed approach.

  15. Visual Servo Tracking Control of a Wheeled Mobile Robot with a Monocular Fixed Camera

    National Research Council Canada - National Science Library

    Chen, J; Dixon, W. E; Dawson, D. M; Chitrakaran, V. K

    2004-01-01

    In this paper, a visual servo tracking controller for a wheeled mobile robot (WMR) is developed that utilizes feedback from a monocular camera system that is mounted with a fixed position and orientation...

  16. Effects of joint mobilization on chronic ankle instability: a randomized controlled trial.

    Science.gov (United States)

    Cruz-Díaz, David; Lomas Vega, Rafael; Osuna-Pérez, Maria Catalina; Hita-Contreras, Fidel; Martínez-Amat, Antonio

    2015-01-01

    To evaluate the effects of joint mobilization, in which movement is applied to the ankle's dorsiflexion range of motion, on dynamic postural control and on the self-reported instability of patients with chronic ankle instability (CAI). A double-blind, placebo-controlled, randomized trial with repeated measures and a follow-up period. Ninety patients with a history of recurrent ankle sprain, self-reported instability, and a limited dorsiflexion range of motion, were randomly assigned to either the intervention group (Joint Mobilizations, 3 weeks, two sessions per week) the placebo group (Sham Mobilizations, same duration as joint mobilization) or the control group, with a 6 months follow-up. Dorsiflexion Range of Motion (DFROM), Star Excursion Balance Test (SEBT) and CAI Tool (CAIT) were outcome measures. A separate 3 × 4 mixed model analysis of variance was performed to examine the effect of treatment conditions and time, and intention-to-treat (ITT) analysis was applied to evaluate the effect of the independent variable. The application of joint mobilization resulted in better scores of DFROM, CAIT, and SEBTs in the intervention group when compared with the placebo or the control groups (p ankle DFROM, postural control, and self-reported instability. These results suggest that joint mobilization could be applied to patients with recurrent ankle sprain to help restore their functional stability. Implications for Rehabilitation Functional instability is a very common sequela in patients with CAI, resulting in reduced quality of living due to the limitations it imposes on daily life activities. The mobilization with movement technique presented by Mulligan, and based on the joint mobilization accompanied by active movement, appears as a valuable tool to be employed by physical therapists to restore ankle function after a recurrent ankle sprain history. ROM restriction, subjective feeling of instability and dynamic postural control are benefiting from the joint

  17. Robust balancing and position control of a single spherical wheeled mobile platform

    OpenAIRE

    Yavuz, Fırat; Yavuz, Firat; Ünel, Mustafa; Unel, Mustafa

    2016-01-01

    Self-balancing mobile platforms with single spherical wheel, generally called ballbots, are suitable example of underactuated systems. Balancing control of a ballbot platform, which aims to maintain the upright orientation by rejecting external disturbances, is important during station keeping or trajectory tracking. In this paper, acceleration based balancing and position control of a single spherical wheeled mobile platform that has three single-row omniwheel drive m...

  18. Central Vehicle Dynamics Control of the Robotic Research Platform ROboMObil

    OpenAIRE

    Bünte, Tilman; Ho, Lok Man; Satzger, Clemens; Brembeck, Jonathan

    2014-01-01

    The ROboMObil is DLR’s space-robotics driven by-wire electro-mobile research platform for mechatronic actuators, vehicle dynamics control, human machine interfaces, and autonomous driving (DLR = German Aerospace Center). Due to its four highly integrated identical Wheel Robots it exhibits an extraordinary manoeuvrability even allowing for driving sideward or rotating on the spot. Topics related to vehicle dynamics control are addressed in this article.

  19. An Optimal Mobile Service for Telecare Data Synchronization using a Role-based Access Control Model and Mobile Peer-to-Peer Technology.

    Science.gov (United States)

    Ke, Chih-Kun; Lin, Zheng-Hua

    2015-09-01

    The progress of information and communication technologies (ICT) has promoted the development of healthcare which has enabled the exchange of resources and services between organizations. Organizations want to integrate mobile devices into their hospital information systems (HIS) due to the convenience to employees who are then able to perform specific healthcare processes from any location. The collection and merage of healthcare data from discrete mobile devices are worth exploring possible ways for further use, especially in remote districts without public data network (PDN) to connect the HIS. In this study, we propose an optimal mobile service which automatically synchronizes the telecare file resources among discrete mobile devices. The proposed service enforces some technical methods. The role-based access control model defines the telecare file resources accessing mechanism; the symmetric data encryption method protects telecare file resources transmitted over a mobile peer-to-peer network. The multi-criteria decision analysis method, ELECTRE (Elimination Et Choice Translating Reality), evaluates multiple criteria of the candidates' mobile devices to determine a ranking order. This optimizes the synchronization of telecare file resources among discrete mobile devices. A prototype system is implemented to examine the proposed mobile service. The results of the experiment show that the proposed mobile service can automatically and effectively synchronize telecare file resources among discrete mobile devices. The contribution of this experiment is to provide an optimal mobile service that enhances the security of telecare file resource synchronization and strengthens an organization's mobility.

  20. Co-occurrence of arsenic and fluoride in groundwater of semi-arid regions in Latin America: genesis, mobility and remediation.

    Science.gov (United States)

    Alarcón-Herrera, María Teresa; Bundschuh, Jochen; Nath, Bibhash; Nicolli, Hugo B; Gutierrez, Melida; Reyes-Gomez, Victor M; Nuñez, Daniel; Martín-Dominguez, Ignacio R; Sracek, Ondra

    2013-11-15

    Several million people around the world are currently exposed to excessive amounts of arsenic (As) and fluoride (F) in their drinking water. Although the individual toxic effects of As and F have been analyzed, there are few studies addressing their co-occurrences and water treatment options. Several studies conducted in arid and semi-arid regions of Latin America show that the co-occurrences of As and F in drinking water are linked to the volcaniclastic particles in the loess or alluvium, alkaline pH, and limited recharge. The As and F contamination results from water-rock interactions and may be accelerated by geothermal and mining activities, as well as by aquifer over-exploitation. These types of contamination are particularly pronounced in arid and semi-arid regions, where high As concentrations often show a direct relationship with high F concentrations. Enrichment of F is generally related to fluorite dissolution and it is also associated with high Cl, Br, and V concentrations. The methods of As and F removal, such as chemical precipitation followed by filtration and reverse osmosis, are currently being used at different scales and scenarios in Latin America. Although such technologies are available in Latin America, it is still urgent to develop technologies and methods capable of monitoring and removing both of these contaminants simultaneously from drinking water, with a particular focus towards small-scale rural operations. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Power control algorithms for mobile ad hoc networks

    Directory of Open Access Journals (Sweden)

    Nuraj L. Pradhan

    2011-07-01

    We will also focus on an adaptive distributed power management (DISPOW algorithm as an example of the multi-parameter optimization approach which manages the transmit power of nodes in a wireless ad hoc network to preserve network connectivity and cooperatively reduce interference. We will show that the algorithm in a distributed manner builds a unique stable network topology tailored to its surrounding node density and propagation environment over random topologies in a dynamic mobile wireless channel.

  2. In-situ arsenic removal during groundwater recharge through unsaturated alluvium

    Science.gov (United States)

    O'Leary, David; Izbicki, John; T.J. Kim,; Clark Ajawani,; Suarez, Donald; Barnes, Thomas; Thomas Kulp,; Burgess, Matthew K.; Tseng, Iwen

    2015-01-01

    surface geophysical data to evaluate the lateral spreading of water as it moved downward through the unsaturated zone. Three laboratory studies were undertaken. Sequential extraction was used to evaluate the abundance of iron, aluminum, and manganese oxides and selected trace elements on operationally defined sites on the surfaces of mineral grains collected before and after infiltration from the pond. Secondly, radio-labeled arsenic-73 microcosm experiments evaluated the potential for incorporation of arsenic sorbed to exchange sites on mineral grains into less reactive crystalline mineral structures with time. Finally, column studies evaluated arsenic sorption and the pH dependence of sorption for selected unsaturated zone materials.RESULTS/CONCLUSIONS Between December 2010 and July 2012, more than 120,000 cubic meters (m3 ) (about 97 acre-feet) of high-arsenic groundwater was pumped from the deep aquifer into a 0.11 hectare (about 0.27 acres) pond and infiltrated though an 80-meter (about 260 feet) thick unsaturated zone to recharge a water-table aquifer. Arsenic concentrations were lowered from 30 to 2 g/L as water infiltrated though the unsaturated zone at the site. Some uranium, possibly associated with past agricultural land use at the site, was mobilized to concentrations as high as 66 g/L within the unsaturated zone during the experiment. Uranium was resorbed and the high uranium concentrations did not reach the water table at the site. Concentrations of other trace elements, including antimony, chromium, vanadium, and selenium were low throughout the study. Infiltration rates from the pond were as high as 0.4 meters per day (1.1 feet per day, ft/d), and the wetting front moved downward about 25 centimeters per day (cm/d) (0.8 ft/d) to a depth of about 50 m (about 165 feet). Clay layers at that depth slowed the downward movement of the wetting front to about 5 cm/d (0.16 ft/d). Lateral movement of the wetting front was monitored using sequential direct

  3. Discrete Globalised Dual Heuristic Dynamic Programming in Control of the Two-Wheeled Mobile Robot

    OpenAIRE

    Marcin Szuster; Zenon Hendzel

    2014-01-01

    Network-based control systems have been emerging technologies in the control of nonlinear systems over the past few years. This paper focuses on the implementation of the approximate dynamic programming algorithm in the network-based tracking control system of the two-wheeled mobile robot, Pioneer 2-DX. The proposed discrete tracking control system consists of the globalised dual heuristic dynamic programming algorithm, the PD controller, the supervisory term, and an additional control signal...

  4. Assessment of global industrial-age anthropogenic arsenic contamination.

    Science.gov (United States)

    Han, Fengxiang X; Su, Yi; Monts, David L; Plodinec, M John; Banin, Amos; Triplett, Glover E

    2003-09-01

    Arsenic, a carcinogenic trace element, threatens not only the health of millions of humans and other living organisms, but also global sustainability. We present here, for the first time, the global industrial-age cumulative anthropogenic arsenic production and its potential accumulation and risks in the environment. In 2000, the world cumulative industrial-age anthropogenic arsenic production was 4.53 million tonnes. The world-wide coal and petroleum industries accounted for 46% of global annual gross arsenic production, and their overall contribution to industrial-age gross arsenic production was 27% in 2000. Global industrial-age anthropogenic As sources (as As cumulative production) follow the order: As mining production>As generated from coal>As generated from petroleum. The potential industrial-age anthropogenic arsenic input in world arable surface in 2000 was 2.18 mg arsenic kg(-1), which is 1.2 times that in the lithosphere. The development of substitute materials for arsenic applications in the agricultural and forestry industries and controls of arsenic emissions from the coal industry may be possible strategies to significantly decrease arsenic pollution sources and dissipation rates into the environment.

  5. Investigation of biomethylation of arsenic and tellurium during composting

    International Nuclear Information System (INIS)

    Diaz-Bone, Roland A.; Raabe, Maren; Awissus, Simone; Keuter, Bianca; Menzel, Bernd; Kueppers, Klaus; Widmann, Renatus; Hirner, Alfred V.

    2011-01-01

    Though the process of composting features a high microbiological activity, its potential to methylate metals and metalloids has been little investigated so far in spite of the high impact of this process on metal(loid) toxicity and mobility. Here, we studied the biotransformation of arsenic, tellurium, antimony, tin and germanium during composting. Time resolved investigation revealed a highly dynamic process during self-heated composting with markedly differing time patterns for arsenic and tellurium species. Extraordinary high concentrations of up to 150 mg kg -1 methylated arsenic species as well as conversion rates up to 50% for arsenic and 5% for tellurium were observed. In contrast, little to no conversion was observed for antimony, tin and germanium. In addition to experiments with metal(loid) salts, composting of arsenic hyperaccumulating ferns Pteris vittata and P. cretica grown on As-amended soils was studied. Arsenic accumulated in the fronds was efficiently methylated resulting in up to 8 mg kg -1 methylated arsenic species. Overall, these studies indicate that metal(loid)s can undergo intensive biomethylation during composting. Due to the high mobility of methylated species this process needs to be considered in organic waste treatment of metal(loid) contaminated waste materials.

  6. Speciation of arsenic in Canadian feed-coal and combustion by-products

    Energy Technology Data Exchange (ETDEWEB)

    F. Goodarzi; F.E. Huggins [Natural Resourses Canada (Canada). Geological Survey of Canada-Calgary Division

    2003-07-01

    It is important to determine the oxidation state of arsenic in coal and coal combustion products, as this is generally the single most critical factor determining the toxicity of this element towards humans. However, the same factor is also important for understanding the volatility and reactions of arsenic forms in combustion and their leachability and mobility in ash-disposal situations. In this work, XAFS spectroscopy has been used to examine the speciation of arsenic in Canadian subbituminous and bituminous feed-coals and their combustion products. The concentration of arsenic in the feed-coals varied from < 2 ppm for subbituminous to 54 ppm for bituminous coals. Significant differences were noted in how arsenic occurs in subbituminous and bituminous coals, but, although such differences might influence the initial volatility and reactions of arsenic during coal combustion, arsenic is found almost entirely in the less toxic As{sup 5+} oxidation state in combustion products from both types of coal. (Abstract only)

  7. Arsenic in the groundwater: Occurrence, toxicological activities, and remedies.

    Science.gov (United States)

    Jha, S K; Mishra, V K; Damodaran, T; Sharma, D K; Kumar, Parveen

    2017-04-03

    Arsenic (As) contamination in groundwater has become a geo-environmental as well as a toxicological problem across the globe affecting more than 100-million people in nearly 21 countries with its associated disease "arsenicosis." Arsenic poisoning may lead to fatal skin and internal cancers. In present review, an attempt has been made to generate awareness among the readers about various sources of occurrence of arsenic, its geochemistry and speciation, mobilization, metabolism, genotoxicity, and toxicological exposure on humans. The article also emphasizes the possible remedies for combating the problem. The knowledge of these facts may help to work on some workable remedial measure.

  8. Environmental Source of Arsenic Exposure

    OpenAIRE

    Chung, Jin-Yong; Yu, Seung-Do; Hong, Young-Seoub

    2014-01-01

    Arsenic is a ubiquitous, naturally occurring metalloid that may be a significant risk factor for cancer after exposure to contaminated drinking water, cigarettes, foods, industry, occupational environment, and air. Among the various routes of arsenic exposure, drinking water is the largest source of arsenic poisoning worldwide. Arsenic exposure from ingested foods usually comes from food crops grown in arsenic-contaminated soil and/or irrigated with arsenic-contaminated water. According to a ...

  9. Controlling geological and hydrogeological processes in an arsenic contaminated aquifer on the Red River flood plain, Vietnam

    International Nuclear Information System (INIS)

    Larsen, Flemming; Nhan Quy Pham; Nhan Duc Dang; Postma, Dieke; Jessen, Soren; Viet Hung Pham; Nguyen, Thao Bach; Trieu, Huy Duc; Luu Thi Tran; Hoan Nguyen; Chambon, Julie; Hoan Van Nguyen; Dang Hoang Ha; Nguyen Thi Hue; Mai Thanh Duc; Refsgaard, Jens Christian

    2008-01-01

    Geological and hydrogeological processes controlling recharge and the mobilization of As were investigated in a shallow Holocene aquifer on the Red River flood plain near Hanoi, Vietnam. The geology was investigated using surface resistivity methods, geophysical borehole logging, drilling of boreholes and installation of more than 200 piezometers. Recharge processes and surface-groundwater interaction were studied using (i) time-series of hydraulic head distribution in surface water and aquifers, (ii) the stable isotope composition of waters and (iii) numerical groundwater modeling. The Red River and two of its distributaries run through the field site and control the groundwater flow pattern. For most of the year, there is a regional groundwater flow towards the Red River. During the monsoon the Red River water stage rises up to 6 m and stalls the regional groundwater flow. The two distributaries recharge the aquifer from perched water tables in the dry season, whilst in the flooding period surface water enters the aquifer through highly permeable bank sediments. The result is a dynamic groundwater flow pattern with rapid fluctuations in the groundwater table. A transient numerical model of the groundwater flow yields an average recharge rate of 60-100 mm/a through the confining clay, and a total recharge of approximately 200 mm/a was estimated from 3 H/ 3 He dating of the shallow groundwater. Thus in the model area, recharge of surface water from the river distributaries and recharge through a confining clay is of the same magnitude, being on average around 100 mm/a. The thickness of the confining clay varies between 2 and 10 m, and affects the recharge rate and the transport of electron acceptors (O 2 , NO 3 - and SO 4 2- ) into the aquifer. Where the clay layer is thin, an up to 2 m thick oxic zone develops in the shallow aquifer. In the oxic zone the As concentration is less than 1 μg/L but increases in the reduced zone below to 550 μg/L. In the Holocene

  10. Authenticated Blind Issuing of Symmetric Keys for Mobile Access Control System without Trusted Parties

    Directory of Open Access Journals (Sweden)

    Shin-Yan Chiou

    2013-01-01

    Full Text Available Mobile authentication can be used to verify a mobile user’s identity. Normally this is accomplished through the use of logon passwords, but this can raise the secret-key agreement problem between entities. This issue can be resolved by using a public-key cryptosystem, but mobile devices have limited computation ability and battery capacity and a PKI is needed. In this paper, we propose an efficient, non-PKI, authenticated, and blind issued symmetric key protocol for mobile access control systems. An easy-to-deploy authentication and authenticated key agreement system is designed such that empowered mobile devices can directly authorize other mobile devices to exchange keys with the server upon authentication using a non-PKI system without trusted parties. Empowered mobile users do not know the key value of the other mobile devices, preventing users from impersonating other individuals. Also, for security considerations, this system can revoke specific keys or keys issued by a specific user. The scheme is secure, efficient, and feasible and can be implemented in existing environments.

  11. Unexpected Effects of a System-Distributed Mobile Application in Maternity Care: A Randomized Controlled Trial.

    Science.gov (United States)

    Ledford, Christy J W; Womack, Jasmyne J; Rider, Heather A; Seehusen, Angela B; Conner, Stephen J; Lauters, Rebecca A; Hodge, Joshua A

    2018-06-01

    As pregnant mothers increasingly engage in shared decision making regarding prenatal decisions, such as induction of labor, the patient's level of activation may influence pregnancy outcomes. One potential tool to increase patient activation in the clinical setting is mobile applications. However, research is limited in comparing mobile apps with other modalities of patient education and engagement tools. This study was designed to test the effectiveness of a mobile app as a replacement for a spiral notebook guide as a patient education and engagement tool in the prenatal clinical setting. This randomized controlled trial was conducted in the Women's Health Clinic and Family Health Clinic of three hospitals. Repeated-measures analysis of covariance was used to test intervention effects in the study sample of 205 patients. Mothers used a mobile app interface to more frequently record information about their pregnancy; however, across time, mothers using a mobile app reported a significant decrease in patient activation. The unexpected negative effects in the group of patients randomized to the mobile app prompt these authors to recommend that health systems pause before distributing their own version of mobile apps that may decrease patient activation. Mobile apps can be inherently empowering and engaging, but how a system encourages their use may ultimately determine their adoption and success.

  12. Voltammetric Study of Arsenic (III and Arsenic (V in Ground Water of Hajigonj and Kalkini in Bangladesh

    Directory of Open Access Journals (Sweden)

    Mohammad Arifur Rahman

    2008-06-01

    Full Text Available The speciation of arsenic in groundwater samples using Square Wave Anodic Stripping Voltammetry (SWASV, Differential Pulse Anodic Stripping Voltammetry (DPASV and Normal Pulse Anodic Stripping Voltammetry (NPASV are described. Good resolution of the species, arsenic (III and arsenic (V is achieved using SWASV. The reliability of the methods was checked by analyzing the total arsenic content of the samples by Hydride Generation Atomic Absorptioion Spectrophotometer and by analyzing prepared controlled laboratory standard solution. Since this technique is comparatively cheaper than other available techniques it could be a better analytical technique for arsenic speciation from water. In this study, the assessment of inorganic arsenic species in ground water of Kalkini (Madaripur and Hajigonj (Chandpur is reported. It shows that arsenic content in water in different locations is irregular. Most of the locations contain higher level of As(III than As(V. The highest concentration of arsenic is found in Anayetnagor (554.46 ± 0.07 mg/L of Kalkini and Raichar (562 ± 0.50 mg/L of Hajigonj. However, the level of total arsenic and As(III of most of the villages of the study areas are more than the WHO guideline value (50mg/L. Therefore a proper monitoring process should be evolved along with the development of methods to keep the water free from arsenic.

  13. Vascular Hyperpermeability Response in Animals Systemically Exposed to Arsenic.

    Science.gov (United States)

    Chen, Shih-Chieh; Chang, Chao-Yuah; Lin, Ming-Lu

    2018-01-01

    The mechanisms underlying cardiovascular diseases induced by chronic exposure to arsenic remain unclarified. The objectives of this study were to investigate whether increased vascular leakage is induced by inflammatory mustard oil in mice systemically exposed to various doses of arsenic and whether an increased vascular leakage response is still present in arsenic-fed mice after arsenic discontinuation for 2 or 6 months. ICR mice were fed water or various doses of sodium arsenite (10, 15, or 20 mg/kg/day; 5 days/week) for 8 weeks. In separate experiments, the mice were treated with sodium arsenite (20 mg/kg) for 2 or 8 weeks, followed by arsenic discontinuation for 2 or 6 months. Vascular permeability to inflammatory mustard oil was quantified using Evans blue (EB) techniques. Both arsenic-exposed and water-fed (control) mice displayed similar basal levels of EB leakage in the ears brushed with mineral oil, a vehicle of mustard oil. The levels of EB leakage induced by mustard oil in the arsenic groups fed with sodium arsenite (10 or 15 mg/kg) were similar to those of water-fed mice. However, increased levels of EB leakage in response to mustard oil stimulation were significantly higher in mice treated with sodium arsenite (20 mg/kg; high dose) than in arsenic-fed (10 or 15 mg/kg; low and middle doses) or control mice. After arsenic discontinuation for 2 or 6 months, mustard oil-induced vascular EB leakage in arsenic-fed (20 mg/kg) mice was similar to that in control mice. Dramatic increases in mustard oil-induced vascular leakage were only present in mice systemically exposed to the high arsenic dose, indicating the synergistic effects of the high arsenic dose and mustard oil.

  14. THE REMOTE AND MOBILE AIR TRAFFIC CONTROL TOWER AND ITS POSSIBLE APPLICATION TO THE OPERATIONAL AREA

    Directory of Open Access Journals (Sweden)

    Tímea VAS

    2014-10-01

    Full Text Available The concept of remote and mobile Air Traffic Control Tower (ATC TWR and its development has started in Europe, Australia and also in the USA, in order to improve the efficiency of Air Traffic Management (ATM systems in terms of air transportation safety. These new technologies are applicable in many countries in peace time, but on mobility reasons these are promoted to achieve commitments in the operational area. This article describes the devices and range of equipment of mobile and remote tower, and their specifications, which can even serve a medium sized airport, furthermore examines, whether how can those provide the air traffic services at an operational airfield.

  15. Arsenic evolution in fractured bedrock wells in central Maine, USA

    Science.gov (United States)

    Yang, Q.; Zheng, Y.; Culbertson, C.; Schalk, C.; Nielsen, M. G.; Marvinney, R.

    2010-12-01

    , as well as to model the arsenic flux and mobilization from the fractures into the borehole by collecting fracture specific samples using inflatable packers and to differentiate the arsenic in dissolved, colloidal, and particulate forms using filtration methods.

  16. Geochemical and hydrodynamic controls on arsenic and trace metal cycling in a seasonally stratified US sub-tropical reservoir

    International Nuclear Information System (INIS)

    Brandenberger, Jill M.; Louchouarn, Patrick; Herbert, Bruce; Tissot, Philippe

    2004-01-01

    The phase distribution of trace metals and oxyanions was investigated within a South Texas watershed hosting a high density of surface uranium mine pits and tailings. The objectives of the study were to evaluate the potential impact of these old uranium mining sites on the watershed with particular emphasis on spatial and temporal changes in water quality of a reservoir that serves as the major source of freshwater to a population of ∼ 350,000 people in the region. A livestock pond, bordered by uranium mine tailings, was used as a model case-study site to evaluate the cycling of uranium mine-derived oxyanions under changing redox conditions. Although the pond showed seasonal thermal and chemical stratification, geochemical cycling of metals was limited to Co and Pb, which seemed to be mostly associated with redox cycling of Mn mineral phases, and U, which suggested reductive precipitation in the ponds hypolimnion. Uranium levels, however, were too low to support strong inputs from th e tailings into the water column of the pond. The strong relations observed between particulate Cr, Cs, V and Fe suggest that these metals are associated with a stable particulate phase (probably allochthonous aluminosilicates) enriched in unreactive iron. This observation is supported by a parallel relationship in sediments collected across a broad range of sediment depositional processed (and histories) in the basin. Arsenic, though selectively enriched in the ponds water column, remained stable and mostly in solution throughout the depth of the profile and showed no sign of geochemical cycling or interaction with Fe-rich particles. We found no evidence of anthropogenic impacts of U mines beyond the purely local scale. Arsenic does decrease in concentration downstream of uranium mining sites but its presence within the Nueces drainage basin is related to interactions between surface and ground waters with uranium-rich geological formations rather than long-scale transport of

  17. Geochemical and hydrodynamic controls on arsenic and trace metal cycling in a seasonally stratified US sub-tropical reservoir

    International Nuclear Information System (INIS)

    Brandenberger, J.; Louchouarn, P.; Herbert, B.; Tissot, P.

    2004-01-01

    The phase distribution of trace metals and oxyanions, including U and As, in 2 surface water bodies was investigated within a South Texas watershed hosting a high density of surface U mine pits and tailings. The objectives of the study were to evaluate the environmental legacy of U mining, with particular emphasis on the spatial and temporal variability of water quality in Lake Corpus Christi, a downstream reservoir that serves as the major water resource to a population of ∼350,000 people in the region. Lyssy Pond, a livestock pond bordered by U mine tailings, was used as a model case-study site to evaluate the cycling of U mine-derived oxyanions under changing redox conditions. Although the pond showed seasonal thermal and chemical stratification, geochemical cycling of metals was limited to Co and Pb, which was correlated with redox cycling of Mn mineral phases, and U, which suggested reductive precipitation in the pond's hypolimnion. Uranium levels, however, were too low to support strong inputs from the tailings into the water column of the pond. The strong relationships observed between particulate Cr, Cs, V, and Fe suggest that these metals are associated with a stable particulate phase (probably allochthonous alumino-silicates) enriched in unreactive Fe. This observation is supported by a parallel relationship in sediments collected across a broad range of sediment depositional processes (and histories) in the basin. Arsenic, though selectively enriched in the pond's water column, was dominated by dissolved species throughout the depth of the profile and showed no sign of geochemical cycling or interaction with Fe-rich particles. Arsenic (and other oxyanions) in the water columns of Lake Corpus Christi and Lyssy pond were not affected by the abundant presence of Fe-rich particles but instead behaved conservatively. No evidence was found of anthropogenic impacts of U mines beyond the purely local scale. Arsenic's presence within the Nueces drainage basin

  18. The new realized mobile device for extremal control research and presentation

    Directory of Open Access Journals (Sweden)

    Matej URBANSKÝ

    2015-12-01

    Full Text Available At our department we deal with torsional oscillating mechanical systems (TOMS continuous tuning during its operation in terms of torsional oscillation size. Therefore was build the new mobile device for research and presentation purposes of the TOMS continuous tuning using extremal control method. This paper deals mainly with design of the mobile device and its special compressed air distribution system, which is necessary for its regular function.

  19. Research on Open-Closed-Loop Iterative Learning Control with Variable Forgetting Factor of Mobile Robots

    Directory of Open Access Journals (Sweden)

    Hongbin Wang

    2016-01-01

    Full Text Available We propose an iterative learning control algorithm (ILC that is developed using a variable forgetting factor to control a mobile robot. The proposed algorithm can be categorized as an open-closed-loop iterative learning control, which produces control instructions by using both previous and current data. However, introducing a variable forgetting factor can weaken the former control output and its variance in the control law while strengthening the robustness of the iterative learning control. If it is applied to the mobile robot, this will reduce position errors in robot trajectory tracking control effectively. In this work, we show that the proposed algorithm guarantees tracking error bound convergence to a small neighborhood of the origin under the condition of state disturbances, output measurement noises, and fluctuation of system dynamics. By using simulation, we demonstrate that the controller is effective in realizing the prefect tracking.

  20. Calibration and control for range imaging in mobile robot navigation

    Energy Technology Data Exchange (ETDEWEB)

    Dorum, O.H. [Norges Tekniske Hoegskole, Trondheim (Norway). Div. of Computer Systems and Telematics; Hoover, A. [University of South Florida, Tampa, FL (United States). Dept. of Computer Science and Engineering; Jones, J.P. [Oak Ridge National Lab., TN (United States)

    1994-06-01

    This paper addresses some issues in the development of sensor-based systems for mobile robot navigation which use range imaging sensors as the primary source for geometric information about the environment. In particular, we describe a model of scanning laser range cameras which takes into account the properties of the mechanical system responsible for image formation and a calibration procedure which yields improved accuracy over previous models. In addition, we describe an algorithm which takes the limitations of these sensors into account in path planning and path execution. In particular, range imaging sensors are characterized by a limited field of view and a standoff distance -- a minimum distance nearer than which surfaces cannot be sensed. These limitations can be addressed by enriching the concept of configuration space to include information about what can be sensed from a given configuration, and using this information to guide path planning and path following.

  1. Mobile soak pits improve spray team mobility, productivity and safety of PMI malaria control programs.

    Science.gov (United States)

    Mitchell, David F; Brown, Annie S; Bouare, Sory Ibrahima; Belemvire, Allison; George, Kristen; Fornadel, Christen; Norris, Laura; Longhany, Rebecca; Chandonait, Peter J

    2016-09-15

    In the President's Malaria Initiative (PMI)-funded Africa Indoor Residual Spraying Project (AIRS), end-of-day clean-up operations require the safe disposal of wash water resulting from washing the exterior of spray tanks and spray operators' personal protective equipment. Indoor residual spraying (IRS) programs typically use soak pits - large, in-ground filters - to adsorb, filter and then safely degrade the traces of insecticide found in the wash water. Usually these soak pits are permanent installations serving 30 or more operators, located in a central area that is accessible to multiple spray teams at the end of their workday. However, in remote areas, it is often impractical for teams to return to a central soak pit location for cleanup. To increase operational efficiency and improve environmental compliance, the PMI AIRS Project developed and tested mobile soak pits (MSP) in the laboratory and in field applications in Madagascar, Mali, Senegal, and Ethiopia where the distance between villages can be substantial and the road conditions poor. Laboratory testing confirmed the ability of the easily-assembled MSP to reduce effluent concentrations of two insecticides (Actellic 300-CS and Ficam VC) used by the PMI AIRS Project, and to generate the minimal practicable environmental "footprint" in these remote areas. Field testing in the Mali 2014 IRS campaign demonstrated ease of installation and use, resulted in improved and more consistent standards of clean-up, decreased transportation requirements, improved spray team working conditions, and reduced potential for operator exposure to insecticide. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  2. Geological factors controlling occurrence and distribution of arsenic in groundwaters from the southern margin of the Duero Basin, Spain.

    Science.gov (United States)

    Giménez-Forcada, Elena; Smedley, Pauline L

    2014-12-01

    Groundwater from springs and boreholes on the southern edge of the Cenozoic Duero Basin (DB) of Spain has concentrations of arsenic (As) which are commonly above the EC drinking-water limit of 10 μg/L and reach observed values up to 241 μg/L. Groundwater compositions within the sedimentary aquifer vary from Ca-HCO3 type, variably affected by evaporation and agricultural pollution at shallow levels, to Na-HCO3 compositions in deeper boreholes of the basin. Groundwater conditions are mainly oxidising, but reducing groundwaters exist in sub-basins within the aquifer, localised flow paths likely being influenced by basement structure. Arsenic concentrations are spatially variable, reaching up to 38 μg/L in springs of the Spanish Central System (SCS) basement aquifer and up to 62 μg/L in springs from the DB. Highest As concentrations are associated with the Na-HCO3 compositions in deep boreholes (200-450 m depth) within the DB. These have high pH values (up to 9.6) which can give rise to associated elevated concentrations of V and U (up to 64 and 30 μg/L, respectively). In the deep borehole waters of the DB, oxidising flows derived from the mineralised igneous-metamorphic basement and discharging via major faults, and are considered the origin of the higher concentrations. Compositions are consistent with desorption of As and other anionic species from metal oxyhydroxides in an oxic environment. Under locally reducing conditions prevalent in some low-flow parts of the DB, an absence of detectable dissolved As is coincident with low or undetectable SO4 concentrations, and consistent with loss via formation of authigenic sulphide minerals. Mitigation measures are needed urgently in this semi-arid region where provision of alternative sources of safe drinking water is logistically difficult and expensive.

  3. Velocity Tracking Control of Wheeled Mobile Robots by Iterative Learning Control

    Directory of Open Access Journals (Sweden)

    Xiaochun Lu

    2016-05-01

    Full Text Available This paper presents an iterative learning control (ILC strategy to resolve the trajectory tracking problem of wheeled mobile robots (WMRs based on dynamic model. In the previous study of WMRs’ trajectory tracking, ILC was usually applied to the kinematical model of WMRs with the assumption that desired velocity can be tracked immediately. However, this assumption cannot be realized in the real world at all. The kinematic and dynamic models of WMRs are deduced in this chapter, and a novel combination of D-type ILC algorithm and dynamic model of WMR with random bounded disturbances are presented. To analyze the convergence of the algorithm, the method of contracting mapping, which shows that the designed controller can make the velocity tracking errors converge to zero completely when the iteration times tend to infinite, is adopted. Simulation results show the effectiveness of D-type ILC in the trajectory tracking problem of WMRs, demonstrating the effectiveness and robustness of the algorithm in the condition of random bounded disturbance. A comparative study conducted between D-type ILC and compound cosine function neural network (NN controller also demonstrates the effectiveness of the ILC strategy.

  4. Design and control of mobile traction energy storage system; Auslegung und Steuerung mobiler Traktionsenergiespeicher

    Energy Technology Data Exchange (ETDEWEB)

    Lehnert, Martin; Klausner, Sven [Fraunhofer-Institut fuer Verkehrs- und Infrastruktursysteme IVI, Dresden (Germany). Abt. fuer Fahrzeug- und Verkehrssystemtechnik

    2009-07-01

    Energy storage systems in trams may contribute to a noticeable reduction of energy consumption. Whether this or another operating purpose is to be pursued by the use of an energy store, major importance must in any case be attached to the type of storage technology to be selected, the design of the storage system and the kind of storage control strategy to be used. The latter has an influence on the efficiency of the store usage. It is especially predicative control strategies that offer a high potential to this effect. (orig.)

  5. Adaptive training of neural networks for control of autonomous mobile robots

    NARCIS (Netherlands)

    Steur, E.; Vromen, T.; Nijmeijer, H.; Fossen, T.I.; Nijmeijer, H.; Pettersen, K.Y.

    2017-01-01

    We present an adaptive training procedure for a spiking neural network, which is used for control of a mobile robot. Because of manufacturing tolerances, any hardware implementation of a spiking neural network has non-identical nodes, which limit the performance of the controller. The adaptive

  6. A virtual structure approach to formation control of unicycle mobile robots using mutual coupling

    NARCIS (Netherlands)

    Sadowska, A.D.; van den Broek, T.H.A.; Huijberts, H.J.C.; Wouw, van de N.; Kostic, D.; Nijmeijer, H.

    2011-01-01

    In this article, the formation control problem for unicycle mobile robots is studied. A distributed virtual structure control strategy with mutual coupling between the robots is proposed. The rationale behind the introduction of the coupling terms is the fact that these introduce additional

  7. G-CSF maintains controlled neutrophil mobilization during acute inflammation by negatively regulating CXCR2 signaling

    Science.gov (United States)

    Bajrami, Besnik; Zhu, Haiyan; Zhang, Yu C.

    2016-01-01

    Cytokine-induced neutrophil mobilization from the bone marrow to circulation is a critical event in acute inflammation, but how it is accurately controlled remains poorly understood. In this study, we report that CXCR2 ligands are responsible for rapid neutrophil mobilization during early-stage acute inflammation. Nevertheless, although serum CXCR2 ligand concentrations increased during inflammation, neutrophil mobilization slowed after an initial acute fast phase, suggesting a suppression of neutrophil response to CXCR2 ligands after the acute phase. We demonstrate that granulocyte colony-stimulating factor (G-CSF), usually considered a prototypical neutrophil-mobilizing cytokine, was expressed later in the acute inflammatory response and unexpectedly impeded CXCR2-induced neutrophil mobilization by negatively regulating CXCR2-mediated intracellular signaling. Blocking G-CSF in vivo paradoxically elevated peripheral blood neutrophil counts in mice injected intraperitoneally with Escherichia coli and sequestered large numbers of neutrophils in the lungs, leading to sterile pulmonary inflammation. In a lipopolysaccharide-induced acute lung injury model, the homeostatic imbalance caused by G-CSF blockade enhanced neutrophil accumulation, edema, and inflammation in the lungs and ultimately led to significant lung damage. Thus, physiologically produced G-CSF not only acts as a neutrophil mobilizer at the relatively late stage of acute inflammation, but also prevents exaggerated neutrophil mobilization and the associated inflammation-induced tissue damage during early-phase infection and inflammation. PMID:27551153

  8. Visually and force controlled opening and closing of doors by means of a mobile robot arm

    OpenAIRE

    Milighetti, G.; Hoffmann, E.; Fetzner, Angelika; Kuntze, Helge-Björn

    2012-01-01

    A multi-sensory discrete-continuous control concept has been developed to realize interactive basic skills for humanoid and mobile service robots. In the upper hierarchy level a discrete task control structure enables the flexible execution of primitive skill sequences. In the lower continuous level a suitable controller is chosen with control parameters adapted to the current primitive skill. The basic skill for the frequently occurring task of unlocking and opening a door by means of a mobi...

  9. Study of arsenic accumulation in rice and evaluation of protective effects of Chorchorus olitorius leaves against arsenic contaminated rice induced toxicities in Wistar albino rats.

    Science.gov (United States)

    Hosen, Saeed Mohammed Imran; Das, Dipesh; Kobi, Rupkanowar; Chowdhury, Dil Umme Salma; Alam, Md Jibran; Rudra, Bashudev; Bakar, Muhammad Abu; Islam, Saiful; Rahman, Zillur; Al-Forkan, Mohammad

    2016-10-14

    In the present study, we investigated the arsenic accumulation in different parts of rice irrigated with arsenic contaminated water. Besides, we also evaluated the protective effects of Corchorus olitorius leaves against arsenic contaminated rice induced toxicities in animal model. A pot experiment was conducted with arsenic amended irrigation water (0.0, 25.0, 50.0 and 75.0 mg/L As) to investigate the arsenic accumulation in different parts of rice. In order to evaluate the protective effects of Corchorus olitorius leaves, twenty Wistar albino rats were divided into four different groups. The control group (Group-I) was supplied with normal laboratory pellets while groups II, III, and IV received normal laboratory pellets supplemented with arsenic contaminated rice, C. olitorius leaf powder (4 %), arsenic contaminated rice plus C. olitorius leaf powder (4 %) respectively. Different haematological parameters and serum indices were analyzed to evaluate the protective effects of Corchorus olitorius leaves against arsenic intoxication. To gather more supportive evidences of Corchorus olitorius potentiality against arsenic intoxication, histopathological analysis of liver, kidney, spleen and heart tissues was also performed. From the pot experiment, we have found a significant (p ≤ 0.05) increase of arsenic accumulation in different parts of rice with the increase of arsenic concentrations in irrigation water and the trend of accumulation was found as root > straw > husk > grain. Another part of the experiment revealed that supplementation of C. olitorius leaves with arsenic contaminated rice significantly (p rice induced toxicities. Arsenic accumulation in different parts of rice increased dose-dependently. Hence, for irrigation purpose arsenic contaminated water cannot be used. Furthermore, arsenic contaminated rice induced several toxicities in animal model, most of which could be minimized with the food supplementation of Corchorus olitorius

  10. Transcriptomic Response of Purple Willow (Salix purpurea to Arsenic Stress

    Directory of Open Access Journals (Sweden)

    Aymeric Yanitch

    2017-06-01

    Full Text Available Arsenic (As is a toxic element for plants and one of the most common anthropogenic pollutants found at contaminated sites. Despite its severe effects on plant metabolism, several species can accumulate substantial amounts of arsenic and endure the associated stress. However, the genetic mechanisms involved in arsenic tolerance remains obscure in many model plant species used for land decontamination (phytoremediation, including willows. The present study assesses the potential of Salix purpurea cv. ‘Fish Creek’ for arsenic phytoextraction and reveals the genetic responses behind arsenic tolerance, phytoextraction and metabolism. Four weeks of hydroponic exposure to 0, 5, 30 and 100 mg/L revealed that plants were able to tolerate up to 5 mg/L arsenic. Concentrations of 0 and 5 mg/L of arsenic treatment were then used to compare alterations in gene expression of roots, stems and leaves using RNA sequencing. Differential gene expression revealed transcripts encoding proteins putatively involved in entry of arsenic into the roots, storage in vacuoles and potential transport through the plant as well as primary and secondary (indirect toxicity tolerance mechanisms. A major role for tannin as a compound used to relieve cellular toxicity is implicated as well as unexpected expression of the cadmium transporter CAX2, providing a potential means for internal arsenic mobility. These insights into the underpinning genetics of a successful phytoremediating species present novel opportunities for selection of dedicated arsenic tolerant crops as well as the potential to integrate such tolerances into a wider Salix ideotype alongside traits including biomass yield, biomass quality, low agricultural inputs and phytochemical production.

  11. Transcriptomic Response of Purple Willow (Salix purpurea) to Arsenic Stress

    Science.gov (United States)

    Yanitch, Aymeric; Brereton, Nicholas J. B.; Gonzalez, Emmanuel; Labrecque, Michel; Joly, Simon; Pitre, Frederic E.

    2017-01-01

    Arsenic (As) is a toxic element for plants and one of the most common anthropogenic pollutants found at contaminated sites. Despite its severe effects on plant metabolism, several species can accumulate substantial amounts of arsenic and endure the associated stress. However, the genetic mechanisms involved in arsenic tolerance remains obscure in many model plant species used for land decontamination (phytoremediation), including willows. The present study assesses the potential of Salix purpurea cv. ‘Fish Creek’ for arsenic phytoextraction and reveals the genetic responses behind arsenic tolerance, phytoextraction and metabolism. Four weeks of hydroponic exposure to 0, 5, 30 and 100 mg/L revealed that plants were able to tolerate up to 5 mg/L arsenic. Concentrations of 0 and 5 mg/L of arsenic treatment were then used to compare alterations in gene expression of roots, stems and leaves using RNA sequencing. Differential gene expression revealed transcripts encoding proteins putatively involved in entry of arsenic into the roots, storage in vacuoles and potential transport through the plant as well as primary and secondary (indirect) toxicity tolerance mechanisms. A major role for tannin as a compound used to relieve cellular toxicity is implicated as well as unexpected expression of the cadmium transporter CAX2, providing a potential means for internal arsenic mobility. These insights into the underpinning genetics of a successful phytoremediating species present novel opportunities for selection of dedicated arsenic tolerant crops as well as the potential to integrate such tolerances into a wider Salix ideotype alongside traits including biomass yield, biomass quality, low agricultural inputs and phytochemical production. PMID:28702037

  12. Application of the remote microphone method to active noise control in a mobile phone.

    Science.gov (United States)

    Cheer, Jordan; Elliott, Stephen J; Oh, Eunmi; Jeong, Jonghoon

    2018-04-01

    Mobile phones are used in a variety of situations where environmental noise may interfere with the ability of the near-end user to communicate with the far-end user. To overcome this problem, it might be possible to use active noise control technology to reduce the noise experienced by the near-end user. This paper initially demonstrates that when an active noise control system is used in a practical mobile phone configuration to minimise the noise measured by an error microphone mounted on the mobile phone, the attenuation achieved at the user's ear depends strongly on the position of the source generating the acoustic interference. To help overcome this problem, a remote microphone processing strategy is investigated that estimates the pressure at the user's ear from the pressure measured by the microphone on the mobile phone. Through an experimental implementation, it is demonstrated that this arrangement achieves a significant improvement in the attenuation measured at the ear of the user, compared to the standard active control strategy. The robustness of the active control system to changes in both the interfering sound field and the position of the mobile device relative to the ear of the user is also investigated experimentally.

  13. Sensory feedback in artificial control of human mobility

    NARCIS (Netherlands)

    Veltink, Petrus H.

    1999-01-01

    Artificial motor control systems may reduce the handicap of motor impaired individuals. Sensors are essential components in feedback control of these systems and in the information exchange with the user. The objective of this paper is to give an overview of the applications of sensors in the

  14. Remotely controlled working equipment and mobile systems for damage assessment

    International Nuclear Information System (INIS)

    Koehler, G.W.; Salaske, M.

    1975-01-01

    All functions of the MF3 vehicle with its variable geometry chassis were verified in accordance with specifications. Fixed price bids have now been submitted by industries on the action control system and the EMSM II manipulators. Tests of the EMSM I manipulator with supplements especially the remotely controlled application of tools, have been started. (orig.) [de

  15. Use of a mobile phone for potentiostatic control with low cost paper-based microfluidic sensors

    International Nuclear Information System (INIS)

    Delaney, Jacqui L.; Doeven, Egan H.; Harsant, Anthony J.; Hogan, Conor F.

    2013-01-01

    Graphical abstract: -- Highlights: •The ability to generate ECL emission using the audio output of a mobile phone is demonstrated. •Electrochemical control can be achieved by controlling the amplitude and waveform of the sound. •A mobile phone “app” synchronises the electrochemical stimulation with detection via the camera. •In combination with paper-based microfluidic sensors, extremely low cost analysis is possible. •Detection of proline at levels suitable for diagnosis of hyperprolinemia is demonstrated. -- Abstract: By exploiting its ability to play sounds, a mobile phone with suitable software installed can serve the basic functions of a potentiostat in controlling an applied potential to oxidise ECL-active molecules, while the resultant photonic signal is monitored using the camera in video mode. In combination with paper microfluidic sensors this opens significant new possibilities for low-cost, instrument-free sensing

  16. Use of a mobile phone for potentiostatic control with low cost paper-based microfluidic sensors

    Energy Technology Data Exchange (ETDEWEB)

    Delaney, Jacqui L.; Doeven, Egan H.; Harsant, Anthony J.; Hogan, Conor F., E-mail: c.hogan@latrobe.edu.au

    2013-08-06

    Graphical abstract: -- Highlights: •The ability to generate ECL emission using the audio output of a mobile phone is demonstrated. •Electrochemical control can be achieved by controlling the amplitude and waveform of the sound. •A mobile phone “app” synchronises the electrochemical stimulation with detection via the camera. •In combination with paper-based microfluidic sensors, extremely low cost analysis is possible. •Detection of proline at levels suitable for diagnosis of hyperprolinemia is demonstrated. -- Abstract: By exploiting its ability to play sounds, a mobile phone with suitable software installed can serve the basic functions of a potentiostat in controlling an applied potential to oxidise ECL-active molecules, while the resultant photonic signal is monitored using the camera in video mode. In combination with paper microfluidic sensors this opens significant new possibilities for low-cost, instrument-free sensing.

  17. Surface complexation modeling of groundwater arsenic mobility: Results of a forced gradient experiment in a Red River flood plain aquifer, Vietnam

    DEFF Research Database (Denmark)

    Jessen, Søren; Postma, Dieke; Larsen, Flemming

    2012-01-01

    , suggesting a comparable As(III) affinity of Holocene and Pleistocene aquifer sediments. A forced gradient field experiment was conducted in a bank aquifer adjacent to a tributary channel to the Red River, and the passage in the aquifer of mixed groundwater containing up to 74% channel water was observed......Three surface complexation models (SCMs) developed for, respectively, ferrihydrite, goethite and sorption data for a Pleistocene oxidized aquifer sediment from Bangladesh were used to explore the effect of multicomponent adsorption processes on As mobility in a reduced Holocene floodplain aquifer......(III) while PO43− and Fe(II) form the predominant surface species. The SCM for Pleistocene aquifer sediment resembles most the goethite SCM but shows more Si sorption. Compiled As(III) adsorption data for Holocene sediment was also well described by the SCM determined for Pleistocene aquifer sediment...

  18. Toxic Substances Portal- Arsenic

    Science.gov (United States)

    ... is found at low levels in breast milk. top How can families reduce their risk for exposure to arsenic? If you use arsenic-treated wood in home projects, you should wear dust masks, gloves, and protective clothing to decrease exposure to sawdust. ...

  19. Arsenical poisoning of racehorses

    Energy Technology Data Exchange (ETDEWEB)

    Sutherland, G.N.; Fawell, E.V.; Brown, J.K.

    1964-03-07

    A case of arsenic poisoning in a training stable of Thoroughbred racehorses is described. This was due to the accidental spilling of an arsenical rat poison into the corn bin. Nine horses were affected. The mortality rate was 100 per cent. 1 table.

  20. Managing mobility outcomes in vulnerable seniors ( MMOVeS): a randomized controlled pilot study.

    Science.gov (United States)

    Figueiredo, Sabrina; Morais, Jose A; Mayo, Nancy

    2017-12-01

    To estimate feasibility and potential for efficacy of an individualized, exercise-focused, self-management program (i.e. Managing Mobility Outcomes In Vulnerable Seniors ( MMOVeS)), in comparison to exercise information in improving mobility after six months among seniors recently discharged from hospital. Randomized pilot study. Two McGill University-teaching hospitals. Community dwelling seniors, aged 70 years and older, recently discharged from either participating hospitals. The physiotherapy-facilitated intervention consisted of (1) evaluation of mobility capacity, (2) setting short- and long-term goals, (3) delineation of an exercise treatment plan, (4) an educational booklet to enhance mobility self-management skills, and (5) six monthly telephone calls. Control group received a booklet with information on exercises targeting mobility limitations in seniors. Mobility, pain, and health status were assessed at baseline and at six months using multiple indicators drawn from Disabilities of the Arm, Shoulder, and Hand (DASH) Score, Lower Extremity Functional Scale (LEFS) and Short-Form (SF)-36. In all, 26 people were randomized to the intervention (mean age: 81 ± 8; 39% women), and 23 were randomized to the control (mean age: 79 ± 7; 33% women). The odds ratio for the mobility outcomes combined was 3.08 and the 95% confidence interval excluded 1 (1.65-5.77). The odds ratio for pain and health perception favored the MMOVeS group, but the 95% confidence interval included the null value. This feasibility study highlights the potential for efficacy of an individualized, exercise-focused, self-management program in comparison to exercise information in improving mobility outcome for seniors. Furthermore, a home-program combining self-management skills and exercise taught with minimal supervision prove to be feasible. Finally, data from this study can be used to estimate sample size for a confirmatory trial.

  1. Bioscorodite: biological crystallization of scorodite for arsenic removal

    NARCIS (Netherlands)

    Gonzalez-Contreras, P.A.

    2012-01-01

    The use of arsenic is banned for most applications, leading to its accumulation as arsenic trioxide and ferric arsenate sludge. The aim of this thesis was to develop a controlled process for biological crystallization of scorodite from metallurgical streams. In this thesis, the proof of

  2. Distributed Consensus-Based Robust Adaptive Formation Control for Nonholonomic Mobile Robots with Partial Known Dynamics

    Directory of Open Access Journals (Sweden)

    Zhaoxia Peng

    2014-01-01

    Full Text Available This paper investigates the distributed consensus-based robust adaptive formation control for nonholonomic mobile robots with partially known dynamics. Firstly, multirobot formation control problem has been converted into a state consensus problem. Secondly, the practical control strategies, which incorporate the distributed kinematic controllers and the robust adaptive torque controllers, are designed for solving the formation control problem. Thirdly, the specified reference trajectory for the geometric centroid of the formation is assumed as the trajectory of a virtual leader, whose information is available to only a subset of the followers. Finally, numerical results are provided to illustrate the effectiveness of the proposed control approaches.

  3. Electroencephalography (EEG) Based Control in Assistive Mobile Robots: A Review

    International Nuclear Information System (INIS)

    Krishnan, N Murali; Mariappan, Muralindran; Muthukaruppan, Karthigayan; Hijazi, Mohd Hanafi Ahmad; Kitt, Wong Wei

    2016-01-01

    Recently, EEG based control in assistive robot usage has been gradually increasing in the area of biomedical field for giving quality and stress free life for disabled and elderly people. This study reviews the deployment of EGG based control in assistive robots, especially for those who in need and neurologically disabled. The main objective of this paper is to describe the methods used for (i) EEG data acquisition and signal preprocessing, (ii) feature extraction and (iii) signal classification methods. Besides that, this study presents the specific research challenges in the designing of these control systems and future research directions. (paper)

  4. Arsenic pollution and fractionation in sediments and mine waste samples from different mine sites

    Energy Technology Data Exchange (ETDEWEB)

    Larios, Raquel; Fernandez-Martinez, Rodolfo [Unidad de Espectroscopia, Division de Quimica, Departamento de Tecnologia, CIEMAT. Av. Complutense, 40, E-28040 Madrid (Spain); Alvarez, Rodrigo [Dpto. de Explotacion y Prospeccion de Minas, Universidad de Oviedo, ETS de Ingenieros de Minas, C/Independencia, 13, E-33004 Oviedo (Spain); Rucandio, Isabel, E-mail: isabel.rucandio@ciemat.es [Unidad de Espectroscopia, Division de Quimica, Departamento de Tecnologia, CIEMAT. Av. Complutense, 40, E-28040 Madrid (Spain)

    2012-08-01

    A characterization of arsenic pollution and its associations with solid mineral phases in sediments and spoil heap samples from four different abandoned mines in Spain is performed. Three of them were mercury mines located in the same mining district, in the province of Asturias, and the other one, devoted to arsenic mining, is in the province of Leon. A sequential extraction procedure, especially developed for arsenic, was applied for the study of arsenic partitioning. Very high total arsenic concentrations ranging 300-67,000 mg{center_dot}kg{sup -1} were found. Arsenic fractionation in each mine is broadly in accordance with the mineralogy of the area and the extent of the mine workings. In almost all the studied samples, arsenic appeared predominantly associated with iron oxyhydroxides, especially in the amorphous form. Sediments from cinnabar roasted piles showed a higher arsenic mobility as a consequence of an intense ore treatment, posing an evident risk of arsenic spread to the surroundings. Samples belonging to waste piles where the mining activity was less intense presented a higher proportion of arsenic associated with structural minerals. Nevertheless, it represents a long-term source of arsenic to the environment. - Highlights: Black-Right-Pointing-Pointer Arsenic fractionation in sediments from different mining areas is evaluated. Black-Right-Pointing-Pointer A sequential extraction scheme especially designed for arsenic partitioning is applied. Black-Right-Pointing-Pointer As associations with mineral pools is in accordance to the mineralogy of each area. Black-Right-Pointing-Pointer As distribution and mobility in each area depends on the extent of mining activity. Black-Right-Pointing-Pointer As occurs mainly associated with amorphous iron oxyhydroxides in all samples.

  5. Arsenic pollution and fractionation in sediments and mine waste samples from different mine sites

    International Nuclear Information System (INIS)

    Larios, Raquel; Fernández-Martínez, Rodolfo; Álvarez, Rodrigo; Rucandio, Isabel

    2012-01-01

    A characterization of arsenic pollution and its associations with solid mineral phases in sediments and spoil heap samples from four different abandoned mines in Spain is performed. Three of them were mercury mines located in the same mining district, in the province of Asturias, and the other one, devoted to arsenic mining, is in the province of León. A sequential extraction procedure, especially developed for arsenic, was applied for the study of arsenic partitioning. Very high total arsenic concentrations ranging 300–67,000 mg·kg −1 were found. Arsenic fractionation in each mine is broadly in accordance with the mineralogy of the area and the extent of the mine workings. In almost all the studied samples, arsenic appeared predominantly associated with iron oxyhydroxides, especially in the amorphous form. Sediments from cinnabar roasted piles showed a higher arsenic mobility as a consequence of an intense ore treatment, posing an evident risk of arsenic spread to the surroundings. Samples belonging to waste piles where the mining activity was less intense presented a higher proportion of arsenic associated with structural minerals. Nevertheless, it represents a long-term source of arsenic to the environment. - Highlights: ► Arsenic fractionation in sediments from different mining areas is evaluated. ► A sequential extraction scheme especially designed for arsenic partitioning is applied. ► As associations with mineral pools is in accordance to the mineralogy of each area. ► As distribution and mobility in each area depends on the extent of mining activity. ► As occurs mainly associated with amorphous iron oxyhydroxides in all samples.

  6. Method for Reading Sensors and Controlling Actuators Using Audio Interfaces of Mobile Devices

    Science.gov (United States)

    Aroca, Rafael V.; Burlamaqui, Aquiles F.; Gonçalves, Luiz M. G.

    2012-01-01

    This article presents a novel closed loop control architecture based on audio channels of several types of computing devices, such as mobile phones and tablet computers, but not restricted to them. The communication is based on an audio interface that relies on the exchange of audio tones, allowing sensors to be read and actuators to be controlled. As an application example, the presented technique is used to build a low cost mobile robot, but the system can also be used in a variety of mechatronics applications and sensor networks, where smartphones are the basic building blocks. PMID:22438726

  7. Epigenetic control of mobile DNA as an interface between experience and genome change

    Directory of Open Access Journals (Sweden)

    James A. Shapiro

    2014-04-01

    Full Text Available Mobile DNA in the genome is subject to RNA-targeted epigenetic control. This control regulates the activity of transposons, retrotransposons and genomic proviruses. Many different life history experiences alter the activities of mobile DNA and the expression of genetic loci regulated by nearby insertions. The same experiences induce alterations in epigenetic formatting and lead to trans-generational modifications of genome expression and stability. These observations lead to the hypothesis that epigenetic formatting directed by non-coding RNA provides a molecular interface between life history events and genome alteration.

  8. Method for reading sensors and controlling actuators using audio interfaces of mobile devices.

    Science.gov (United States)

    Aroca, Rafael V; Burlamaqui, Aquiles F; Gonçalves, Luiz M G

    2012-01-01

    This article presents a novel closed loop control architecture based on audio channels of several types of computing devices, such as mobile phones and tablet computers, but not restricted to them. The communication is based on an audio interface that relies on the exchange of audio tones, allowing sensors to be read and actuators to be controlled. As an application example, the presented technique is used to build a low cost mobile robot, but the system can also be used in a variety of mechatronics applications and sensor networks, where smartphones are the basic building blocks.

  9. Walking Pattern Generation of Dual-Arm Mobile Robot Using Preview Controller

    OpenAIRE

    P. Wu; W. Wu

    2012-01-01

    Based on the stability request of robot’s moving on the ground, the motion planning of dual-arm mobile robot when moving on the ground is studied and the preview control system is applied in the robot walking pattern generation. Direct question of robot kinematics in the extended task space is analyzed according to Degrees of Freedom configuration of the dual-arm mobile robot. It is proved that the preview control system could be used in the generation of robot Center of Mass forward trajecto...

  10. Anionic sorbents for arsenic and technetium species

    International Nuclear Information System (INIS)

    Lucero, Daniel A.; Moore, Robert Charles; Bontchev, Ranko Panayotov; Hasan, Ahmed Ali Mohamed; Zhao, Hongting; Salas, Fred Manuel; Holt, Kathleen Caroline

    2003-01-01

    Two sorbents, zirconium coated zeolite and magnesium hydroxide, were tested for their effectiveness in removing arsenic from Albuquerque municipal water. Results for the zirconium coated zeolite indicate that phosphate present in the water interfered with the sorption of arsenic. Additionally, there was a large quantity of iron and copper present in the water, corrosion products from the piping system, which may have interfered with the uptake of arsenic by the sorbent. Magnesium hydroxide has also been proven to be a strong sorbent for arsenic as well as other metals. Carbonate, present in water, has been shown to interfere with the sorption of arsenic by reacting with the magnesium hydroxide to form magnesium carbonate. The reaction mechanism was investigated by FT-IR and shows that hydrogen bonding between an oxygen on the arsenic species and a hydrogen on the Mg(OH)2 is most likely the mechanism of sorption. This was also confirmed by RAMAN spectroscopy and XRD. Technetium exists in multiple oxidation states (IV and VII) and is easily oxidized from the relatively insoluble Tc(IV) form to the highly water soluble and mobile Tc(VII) form. The two oxidation states exhibit different sorption characteristics. Tc(VII) does not sorb to most materials whereas Tc(IV) will strongly sorb to many materials. Therefore, it was determined that it is necessary to first reduce the Tc (using SnCl2) before sorption to stabilize Tc in the environment. Additionally, the effect of carbonate and phosphate on the sorption of technetium by hydroxyapatite was studied and indicated that both have a significant effect on reducing Tc sorption

  11. A Null Space Control of Two Wheels Driven Mobile Manipulator Using Passivity Theory

    Science.gov (United States)

    Shibata, Tsuyoshi; Murakami, Toshiyuki

    This paper describes a control strategy of null space motion of a two wheels driven mobile manipulator. Recently, robot is utilized in various industrial fields and it is preferable for the robot manipulator to have multiple degrees of freedom motion. Several studies of kinematics for null space motion have been proposed. However stability analysis of null space motion is not enough. Furthermore, these approaches apply to stable systems, but they do not apply unstable systems. Then, in this research, base of manipulator equips with two wheels driven mobile robot. This robot is called two wheels driven mobile manipulator, which becomes unstable system. In the proposed approach, a control design of null space uses passivity based stabilizing. A proposed controller is decided so that closed-loop system of robot dynamics satisfies passivity. This is passivity based control. Then, control strategy is that stabilizing of the robot system applies to work space observer based approach and null space control while keeping end-effector position. The validity of the proposed approach is verified by simulations and experiments of two wheels driven mobile manipulator.

  12. Virtual Simulator for Autonomous Mobile Robots Navigation System Using Concepts of Control Rapid Prototyping

    Directory of Open Access Journals (Sweden)

    Leonimer Flavio de Melo

    2013-09-01

    Full Text Available This work presents the proposal of virtual environment implementation for project simulation and conception of supervision and control systems for mobile robots, that are capable to operate and adapting in different environments and conditions. This virtual system has as purpose to facilitate the development of embedded architecture systems, emphasizing the implementation of tools that allow the simulation of the kinematic conditions, dynamic and control, with real time monitoring of all important system points. For this, open control architecture is proposal, integrating the two main techniques of robotic control implementation in the hardware level: systems microprocessors and reconfigurable hardware devices. The implemented simulator system is composed of a trajectory generating module, a kinematic and dynamic simulator module and of a analysis module of results and errors. The kinematic and dynamic simulator module makes all simulation of the mobile robot following the pre-determined trajectory of the trajectory generator. All the kinematic and dynamic results shown during the simulation can be evaluated and visualized in graphs and tables formats, in the results analysis module, allowing an improvement in the system, minimizing the errors with the necessary adjustments optimization. For controller implementation in the embedded system, it uses the rapid prototyping, which is the technology that allows, in set with the virtual simulation environment, the development of a controller project for mobile robots. The validation and tests had been accomplishing with nonholonomics mobile robots models with differential transmission.

  13. Arsenic metabolism efficiency has a causal role in arsenic toxicity: Mendelian randomization and gene-environment interaction.

    Science.gov (United States)

    Pierce, Brandon L; Tong, Lin; Argos, Maria; Gao, Jianjun; Farzana, Jasmine; Roy, Shantanu; Paul-Brutus, Rachelle; Rahaman, Ronald; Rakibuz-Zaman, Muhammad; Parvez, Faruque; Ahmed, Alauddin; Quasem, Iftekhar; Hore, Samar K; Alam, Shafiul; Islam, Tariqul; Harjes, Judith; Sarwar, Golam; Slavkovich, Vesna; Gamble, Mary V; Chen, Yu; Yunus, Mohammad; Rahman, Mahfuzar; Baron, John A; Graziano, Joseph H; Ahsan, Habibul

    2013-12-01

    Arsenic exposure through drinking water is a serious global health issue. Observational studies suggest that individuals who metabolize arsenic efficiently are at lower risk for toxicities such as arsenical skin lesions. Using two single nucleotide polymorphisms(SNPs) in the 10q24.32 region (near AS3MT) that show independent associations with metabolism efficiency, Mendelian randomization can be used to assess whether the association between metabolism efficiency and skin lesions is likely to be causal. Using data on 2060 arsenic-exposed Bangladeshi individuals, we estimated associations for two 10q24.32 SNPs with relative concentrations of three urinary arsenic species (representing metabolism efficiency): inorganic arsenic (iAs), monomethylarsonic acid(MMA) and dimethylarsinic acid (DMA). SNP-based predictions of iAs%, MMA% and DMA% were tested for association with skin lesion status among 2483 cases and 2857 controls. Causal odds ratios for skin lesions were 0.90 (95% confidence interval[CI]: 0.87, 0.95), 1.19 (CI: 1.10, 1.28) and 1.23 (CI: 1.12, 1.36)for a one standard deviation increase in DMA%, MMA% and iAs%,respectively. We demonstrated genotype-arsenic interaction, with metabolism-related variants showing stronger associations with skin lesion risk among individuals with high arsenic exposure (synergy index: 1.37; CI: 1.11, 1.62). We provide strong evidence for a causal relationship between arsenic metabolism efficiency and skin lesion risk. Mendelian randomization can be used to assess the causal role of arsenic exposure and metabolism in a wide array of health conditions.exposure and metabolism in a wide array of health conditions.Developing interventions that increase arsenic metabolism efficiency are likely to reduce the impact of arsenic exposure on health.

  14. Finite-time tracking control for multiple non-holonomic mobile robots based on visual servoing

    Science.gov (United States)

    Ou, Meiying; Li, Shihua; Wang, Chaoli

    2013-12-01

    This paper investigates finite-time tracking control problem of multiple non-holonomic mobile robots via visual servoing. It is assumed that the pinhole camera is fixed to the ceiling, and camera parameters are unknown. The desired reference trajectory is represented by a virtual leader whose states are available to only a subset of the followers, and the followers have only interaction. First, the camera-objective visual kinematic model is introduced by utilising the pinhole camera model for each mobile robot. Second, a unified tracking error system between camera-objective visual servoing model and desired reference trajectory is introduced. Third, based on the neighbour rule and by using finite-time control method, continuous distributed cooperative finite-time tracking control laws are designed for each mobile robot with unknown camera parameters, where the communication topology among the multiple mobile robots is assumed to be a directed graph. Rigorous proof shows that the group of mobile robots converges to the desired reference trajectory in finite time. Simulation example illustrates the effectiveness of our method.

  15. Mobile-Based Video Learning Outcomes in Clinical Nursing Skill Education: A Randomized Controlled Trial.

    Science.gov (United States)

    Lee, Nam-Ju; Chae, Sun-Mi; Kim, Haejin; Lee, Ji-Hye; Min, Hyojin Jennifer; Park, Da-Eun

    2016-01-01

    Mobile devices are a regular part of daily life among the younger generations. Thus, now is the time to apply mobile device use to nursing education. The purpose of this study was to identify the effects of a mobile-based video clip on learning motivation, competence, and class satisfaction in nursing students using a randomized controlled trial with a pretest and posttest design. A total of 71 nursing students participated in this study: 36 in the intervention group and 35 in the control group. A video clip of how to perform a urinary catheterization was developed, and the intervention group was able to download it to their own mobile devices for unlimited viewing throughout 1 week. All of the students participated in a practice laboratory to learn urinary catheterization and were blindly tested for their performance skills after participation in the laboratory. The intervention group showed significantly higher levels of learning motivation and class satisfaction than did the control. Of the fundamental nursing competencies, the intervention group was more confident in practicing catheterization than their counterparts. Our findings suggest that video clips using mobile devices are useful tools that educate student nurses on relevant clinical skills and improve learning outcomes.

  16. Mobile phone intervention to improve diabetes care in rural areas of Pakistan: a randomized controlled trial.

    Science.gov (United States)

    Shahid, Muhammad; Mahar, Saeed Ahmed; Shaikh, Shiraz; Shaikh, Zuhaib-u-ddin

    2015-03-01

    To determine the effect of mobile phone intervention on HbA1c in type-2 Diabetes Mellitus (DM) patients living in rural areas of Pakistan. Randomized controlled trial. Department of Endocrinology, Liaquat National Hospital, Karachi, from December 2013 to June 2014. A total of 440 patients in intervention and control groups were enrolled. All patients between 18 - 70 years of age, residing in rural areas of Pakistan, HbA1c ³ 8.0% and having personal functional mobile phone were included. The intervention group patients were called directly on mobile phone after every 15 days for a period of 4 months. They were asked about the self-monitoring blood glucose, intake of medications, physical activity, healthy eating and were physically examined after 4 months. However, the control group was examined initially and after 4 months physically in the clinic and there were no mobile phone contacts with these patients. Patients in intervention group showed improvement (p Mobile phone technology in rural areas of Pakistan was helpful in lowering HbA1c levels in intervention group through direct communication with the diabetic patients. Lowering LDL and following diabetic diet plan can reduce HbA1c in these patients and help in preventing future complications.

  17. Pituitary tumor risk in relation to mobile phone use: A case-control study.

    Science.gov (United States)

    Shrestha, Mithila; Raitanen, Jani; Salminen, Tiina; Lahkola, Anna; Auvinen, Anssi

    2015-01-01

    The number of mobile phone users has grown rapidly, which has generated mounting public concern regarding possible health hazards. This study aims to assess pituitary tumor risk, as it has rarely been investigated. A case-control study was conducted with 80 eligible cases identified from all five university hospitals in Finland and frequency-matched 240 controls from the national population register. Controls were matched to cases by age, sex, region of residence and date of interview. A detailed history of mobile phone use was obtained using a structured interview. Several indicators of mobile phone use were assessed using conditional logistic regression. A reduced odds ratio was seen among regular mobile phone users [OR 0.39, 95% confidence interval (CI) 0.21, 0.72] relative to never/non-regular users, possibly reflecting methodological limitations. Pituitary tumor risk was not increased after 10 or more years since first use (OR 0.69, 95% CI 0.25, 1.89). The risk was not increased in relation to duration, cumulative hours of use, or cumulative number of calls. The results were similar for analog and digital phones. We found no excess risk associated with self-reported short- or medium-term use of mobile phones. This is consistent with most of the published studies. However, uncertainties remained for longer duration of use, as a very small proportion of study participants reported use beyond 10 years.

  18. Urinary arsenic speciation profile in ethnic group of the Atacama desert (Chile) exposed to variable arsenic levels in drinking water.

    Science.gov (United States)

    Yáñez, Jorge; Mansilla, Héctor D; Santander, I Paola; Fierro, Vladimir; Cornejo, Lorena; Barnes, Ramón M; Amarasiriwardena, Dulasiri

    2015-01-01

    Ethnic groups from the Atacama Desert (known as Atacameños) have been exposed to natural arsenic pollution for over 5000 years. This work presents an integral study that characterizes arsenic species in water used for human consumption. It also describes the metabolism and arsenic elimination through urine in a chronically exposed population in northern Chile. In this region, water contained total arsenic concentrations up to 1250 μg L(-1), which was almost exclusively As(V). It is also important that this water was ingested directly from natural water sources without any treatment. The ingested arsenic was extensively methylated. In urine 93% of the arsenic was found as methylated arsenic species, such as monomethylarsonic acid [MMA(V)] and dimethylarsinic acid [DMA(V)]. The original ingested inorganic species [As(V)], represent less than 1% of the total urinary arsenic. Methylation activity among individuals can be assessed by measuring primary [inorganic As/methylated As] and secondary methylation [MMA/DMA] indexes. Both methylation indexes were 0.06, indicating a high biological converting capability of As(V) into MMA and then MMA into DMA, compared with the control population and other arsenic exposed populations previously reported.

  19. Surface complexation modeling of groundwater arsenic mobility: Results of a forced gradient experiment in a Red River flood plain aquifer, Vietnam

    Science.gov (United States)

    Jessen, Søren; Postma, Dieke; Larsen, Flemming; Nhan, Pham Quy; Hoa, Le Quynh; Trang, Pham Thi Kim; Long, Tran Vu; Viet, Pham Hung; Jakobsen, Rasmus

    2012-12-01

    Three surface complexation models (SCMs) developed for, respectively, ferrihydrite, goethite and sorption data for a Pleistocene oxidized aquifer sediment from Bangladesh were used to explore the effect of multicomponent adsorption processes on As mobility in a reduced Holocene floodplain aquifer along the Red River, Vietnam. The SCMs for ferrihydrite and goethite yielded very different results. The ferrihydrite SCM favors As(III) over As(V) and has carbonate and silica species as the main competitors for surface sites. In contrast, the goethite SCM has a greater affinity for As(V) over As(III) while PO43- and Fe(II) form the predominant surface species. The SCM for Pleistocene aquifer sediment resembles most the goethite SCM but shows more Si sorption. Compiled As(III) adsorption data for Holocene sediment was also well described by the SCM determined for Pleistocene aquifer sediment, suggesting a comparable As(III) affinity of Holocene and Pleistocene aquifer sediments. A forced gradient field experiment was conducted in a bank aquifer adjacent to a tributary channel to the Red River, and the passage in the aquifer of mixed groundwater containing up to 74% channel water was observed. The concentrations of As (SCM correctly predicts desorption for As(III) but for Si and PO43- it predicts an increased adsorption instead of desorption. The goethite SCM correctly predicts desorption of both As(III) and PO43- but failed in the prediction of Si desorption. These results indicate that the prediction of As mobility, by using SCMs for synthetic Fe-oxides, will be strongly dependent on the model chosen. The SCM based on the Pleistocene aquifer sediment predicts the desorption of As(III), PO43- and Si quite superiorly, as compared to the SCMs for ferrihydrite and goethite, even though Si desorption is still somewhat under-predicted. The observation that a SCM calibrated on a different sediment can predict our field results so well suggests that sediment based SCMs may be a

  20. Control of group of mobile autonomous agents via local strategies

    Institute of Scientific and Technical Information of China (English)

    Lixin GAO; Daizhan CHENG; Yiguang HONG

    2008-01-01

    This paper considers the formation control problem of multi-agent systems in a distributed fashion.Two cases of the information propagating topologies among multiple agents,characterized by graphics model,are considered.One is fixed topology.The other is switching topology which represents the limited and less reliable information exchange.The local formation control strategies established in this paper are based on a simple modification of the existing consensus control strategies.Moreover,some existing convergence conditions ale shown to be a special case of our model even in the continuous-time consensus case.Therefore.the results of this paper extend the existing results about the consensus problem.

  1. Real-Time Inverse Optimal Neural Control for Image Based Visual Servoing with Nonholonomic Mobile Robots

    Directory of Open Access Journals (Sweden)

    Carlos López-Franco

    2015-01-01

    Full Text Available We present an inverse optimal neural controller for a nonholonomic mobile robot with parameter uncertainties and unknown external disturbances. The neural controller is based on a discrete-time recurrent high order neural network (RHONN trained with an extended Kalman filter. The reference velocities for the neural controller are obtained with a visual sensor. The effectiveness of the proposed approach is tested by simulations and real-time experiments.

  2. Remotely controlled working gear and mobile systems for damage assessment

    International Nuclear Information System (INIS)

    Koehler, G.W.; Salaske, M.; Selig, M.

    1975-01-01

    The chassis of the light MF3 manipulator vehicle and the necessary electric control system have reached and advanced stage of construction. Bids will soon be invited for the mission control system with multiplexers of whole MF3 unit and for simple equipment for damage assessment. All major problems have been clarified in the course of the design phase of the light electric EMSM II Master-Slave manipulators intended for this service. The prototype of the electric EMSM I Master-Slave manipulator has been equipped with some of the supplementary tools required for test missions. (orig.) [de

  3. Seasonal Influences on Ground-Surface Water Interactions in an Arsenic-Affected Aquifer in Cambodia

    Science.gov (United States)

    Richards, L. A.; Magnone, D.; Van Dongen, B.; Bryant, C.; Boyce, A.; Ballentine, C. J.; Polya, D. A.

    2015-12-01

    Millions of people in South and Southeast Asia consume drinking water daily which contains dangerous levels of arsenic exceeding health-based recommendations [1]. A key control on arsenic mobilization in aquifers in these areas has been controversially identified as the interaction of 'labile' organic matter contained in surface waters with groundwaters and sediments at depth [2-4], which may trigger the release of arsenic from the solid- to aqueous-phase via reductive dissolution of iron-(hyr)oxide minerals [5]. In a field site in Kandal Province, Cambodia, which is an arsenic-affected area typical to others in the region, there are strong seasonal patterns in groundwater flow direction, which are closely related to monsoonal rains [6] and may contribute to arsenic release in this aquifer. The aim of this study is to explore the implications of the high susceptibility of this aquifer system to seasonal changes on potential ground-surface water interactions. The main objectives are to (i) identify key zones where there are likely ground-surface water interactions, (ii) assess the seasonal impact of such interactions and (iii) quantify the influence of interactions using geochemical parameters (such as As, Fe, NO3, NH4, 14C, 3T/3He, δ18O, δ2H). Identifying the zones, magnitude and seasonal influence of ground-surface water interactions elucidates new information regarding potential locations/pathways of arsenic mobilization and/or transport in affected aquifers and may be important for water management strategies in affected areas. This research is supported by NERC (NE/J023833/1) to DP, BvD and CJB and a NERC PhD studentship (NE/L501591/1) to DM. References: [1] World Health Organization, 2008. [2] Charlet & Polya (2006), Elements, 2, 91-96. [3] Harvey et al. (2002), Science, 298, 1602-1606. [4] Lawson et al. (2013), Env. Sci. Technol. 47, 7085 - 7094. [5] Islam et al. (2004), Nature, 430, 68-71. [6] Benner et al. (2008) Appl. Geochem. 23(11), 3072 - 3087.

  4. Recent flow regime and sedimentological evolution of a fluvial system as the main factors controlling spatial distribution of arsenic in groundwater (Red River, Vietnam)

    DEFF Research Database (Denmark)

    Kazmierczak, J.; Larsen, F.; Jakobsen, R.

    2016-01-01

    sediments was partially eroded during the Holocene and covered by sand and clay deposited in fluvial environments. Sedimentary processes lead to the development of two flow systems. Shallow groundwater discharges either to the local surface water bodies or, in the areas where low permeable sediments...... isolating Pleistocene and Holocene aquifers were eroded, to the deep groundwater flow system discharging to Red River. Previously reported pattern of arsenic groundwater concentrations decreasing with an increasing sediment age is modified by the observed flow regime. Connection of the younger and older...... river channels resulted in a transport of high arsenic concentrations towards the Pleistocene aquifer, where low arsenic concentrations were expected....

  5. Optimizing a mobile robot control system using GPU acceleration

    Science.gov (United States)

    Tuck, Nat; McGuinness, Michael; Martin, Fred

    2012-01-01

    This paper describes our attempt to optimize a robot control program for the Intelligent Ground Vehicle Competition (IGVC) by running computationally intensive portions of the system on a commodity graphics processing unit (GPU). The IGVC Autonomous Challenge requires a control program that performs a number of different computationally intensive tasks ranging from computer vision to path planning. For the 2011 competition our Robot Operating System (ROS) based control system would not run comfortably on the multicore CPU on our custom robot platform. The process of profiling the ROS control program and selecting appropriate modules for porting to run on a GPU is described. A GPU-targeting compiler, Bacon, is used to speed up development and help optimize the ported modules. The impact of the ported modules on overall performance is discussed. We conclude that GPU optimization can free a significant amount of CPU resources with minimal effort for expensive user-written code, but that replacing heavily-optimized library functions is more difficult, and a much less efficient use of time.

  6. Position control of a wheeled mobile robot including tire behavior

    NARCIS (Netherlands)

    Ploeg, J.; Schouten, H.E.; Nijmeijer, H.

    2009-01-01

    Advanced driver assistance systems are increasingly available on road vehicles. These systems require a thorough development procedure, an important part of which consists of hardware-in-the-loop experiments in a controlled environment. To this end, a facility called Vehicle Hardware-In-the-Loop

  7. Remote control and motion coordination of mobile robots

    NARCIS (Netherlands)

    Alvarez Aguirre, A.

    2011-01-01

    As robots destined for personal and professional applications advance towards becoming part of our daily lives, the importance and complexity of the control algorithms which regulate them should not be underestimated. This thesis is related to two fields within robotics which are of major importance

  8. The effectiveness of educational interventions to enhance the adoption of fee-based arsenic testing in Bangladesh: a cluster randomized controlled trial.

    Science.gov (United States)

    George, Christine Marie; Inauen, Jennifer; Rahman, Sheikh Masudur; Zheng, Yan

    2013-07-01

    Arsenic (As) testing could help 22 million people, using drinking water sources that exceed the Bangladesh As standard, to identify safe sources. A cluster randomized controlled trial was conducted to evaluate the effectiveness of household education and local media in the increasing demand for fee-based As testing. Randomly selected households (N = 452) were divided into three interventions implemented by community workers: 1) fee-based As testing with household education (HE); 2) fee-based As testing with household education and a local media campaign (HELM); and 3) fee-based As testing alone (Control). The fee for the As test was US$ 0.28, higher than the cost of the test (US$ 0.16). Of households with untested wells, 93% in both intervention groups HE and HELM purchased an As test, whereas only 53% in the control group. In conclusion, fee-based As testing with household education is effective in the increasing demand for As testing in rural Bangladesh.

  9. An overview on real-time control schemes for wheeled mobile robot

    Science.gov (United States)

    Radzak, M. S. A.; Ali, M. A. H.; Sha’amri, S.; Azwan, A. R.

    2018-04-01

    The purpose of this paper is to review real-time control motion algorithms for wheeled mobile robot (WMR) when navigating in environment such as road. Its need a good controller to avoid collision with any disturbance and maintain a track error at zero level. The controllers are used with other aiding sensors to measure the WMR’s velocities, posture, and interference to estimate the required torque to be applied on the wheels of mobile robot. Four main categories for wheeled mobile robot control systems have been found in literature which are namely: Kinematic based controller, Dynamic based controllers, artificial intelligence based control system, and Active Force control. A MATLAB/Simulink software is the main software to simulate and implement the control system. The real-time toolbox in MATLAB/SIMULINK are used to receive/send data from sensors/to actuator with presence of disturbances, however others software such C, C++ and visual basic are rare to be used.

  10. Motion control of multi-actuator hydraulic systems for mobile machineries: Recent advancements and future trends

    Science.gov (United States)

    Xu, Bing; Cheng, Min

    2018-06-01

    This paper presents a survey of recent advancements and upcoming trends in motion control technologies employed in designing multi-actuator hydraulic systems for mobile machineries. Hydraulic systems have been extensively used in mobile machineries due to their superior power density and robustness. However, motion control technologies of multi-actuator hydraulic systems have faced increasing challenges due to stringent emission regulations. In this study, an overview of the evolution of existing throttling control technologies is presented, including open-center and load sensing controls. Recent advancements in energy-saving hydraulic technologies, such as individual metering, displacement, and hybrid controls, are briefly summarized. The impact of energy-saving hydraulic technologies on dynamic performance and control solutions are also discussed. Then, the advanced operation methods of multi-actuator mobile machineries are reviewed, including coordinated and haptic controls. Finally, challenges and opportunities of advanced motion control technologies are presented by providing an overall consideration of energy efficiency, controllability, cost, reliability, and other aspects.

  11. Cooperative Control of Mobile Sensor Networks for Environmental Monitoring: An Event-Triggered Finite-Time Control Scheme.

    Science.gov (United States)

    Lu, Qiang; Han, Qing-Long; Zhang, Botao; Liu, Dongliang; Liu, Shirong

    2017-12-01

    This paper deals with the problem of environmental monitoring by developing an event-triggered finite-time control scheme for mobile sensor networks. The proposed control scheme can be executed by each sensor node independently and consists of two parts: one part is a finite-time consensus algorithm while the other part is an event-triggered rule. The consensus algorithm is employed to enable the positions and velocities of sensor nodes to quickly track the position and velocity of a virtual leader in finite time. The event-triggered rule is used to reduce the updating frequency of controllers in order to save the computational resources of sensor nodes. Some stability conditions are derived for mobile sensor networks with the proposed control scheme under both a fixed communication topology and a switching communication topology. Finally, simulation results illustrate the effectiveness of the proposed control scheme for the problem of environmental monitoring.

  12. A computed torque method based attitude control with optimal force distribution for articulated body mobile robots

    International Nuclear Information System (INIS)

    Fukushima, Edwardo F.; Hirose, Shigeo

    2000-01-01

    This paper introduces an attitude control scheme based in optimal force distribution using quadratic programming which minimizes joint energy consumption. This method shares similarities with force distribution for multifingered hands, multiple coordinated manipulators and legged walking robots. In particular, an attitude control scheme was introduced inside the force distribution problem, and successfully implemented for control of the articulated body mobile robot KR-II. This is an actual mobile robot composed of cylindrical segments linked in series by prismatic joints and has a long snake-like appearance. These prismatic joints are force controlled so that each segment's vertical motion can automatically follow the terrain irregularities. An attitude control is necessary because this system acts like a system of wheeled inverted pendulum carts connected in series, being unstable by nature. The validity and effectiveness of the proposed method is verified by computer simulation and experiments with the robot KR-II. (author)

  13. Mobile monitoring and embedded control system for factory environment.

    Science.gov (United States)

    Lian, Kuang-Yow; Hsiao, Sung-Jung; Sung, Wen-Tsai

    2013-12-17

    This paper proposes a real-time method to carry out the monitoring of factory zone temperatures, humidity and air quality using smart phones. At the same time, the system detects possible flames, and analyzes and monitors electrical load. The monitoring also includes detecting the vibrations of operating machinery in the factory area. The research proposes using ZigBee and Wi-Fi protocol intelligent monitoring system integration within the entire plant framework. The sensors on the factory site deliver messages and real-time sensing data to an integrated embedded systems via the ZigBee protocol. The integrated embedded system is built by the open-source 32-bit ARM (Advanced RISC Machine) core Arduino Due module, where the network control codes are built in for the ARM chipset integrated controller. The intelligent integrated controller is able to instantly provide numerical analysis results according to the received data from the ZigBee sensors. The Android APP and web-based platform are used to show measurement results. The built-up system will transfer these results to a specified cloud device using the TCP/IP protocol. Finally, the Fast Fourier Transform (FFT) approach is used to analyze the power loads in the factory zones. Moreover, Near Field Communication (NFC) technology is used to carry out the actual electricity load experiments using smart phones.

  14. Lower limb control and mobility following exercise training

    Directory of Open Access Journals (Sweden)

    Kim Sukwon

    2012-02-01

    Full Text Available Abstract The objective of the present study was to evaluate the effects of 8-week balance or weight training on ankle joint stiffness and limb stability for older adults, furthermore, on outcomes of slips while walking. Eighteen older adults volunteered for the study and randomly were assigned to the three groups, such as, weight, balance, or control group. While walking on a walking track, three-dimensional posture data were sampled and ankle joint stiffness and limb stability were computed to evaluate the effects of training. 2 (pre and post × 3 (weight, balance, and control × 2 (dominant and non-dominant legs mixed factor repeated ANOVA was performed. The results indicated that only balance training group showed an improvement in joint stiffness and both the training groups showed improvements in limb stability. Also, fall frequency results suggested that joint stiffness and limb stability had an effect on the likelihood of slip-induced falls. In conclusion, training can facilitate improvements in joint and limb control mechanism for older adults contributing to an improvement in the likelihood of slip-induced falls.

  15. Controlling Oxygen Mobility in Ruddlesden–Popper Oxides

    Directory of Open Access Journals (Sweden)

    Dongkyu Lee

    2017-03-01

    Full Text Available Discovering new energy materials is a key step toward satisfying the needs for next-generation energy conversion and storage devices. Among the various types of oxides, Ruddlesden–Popper (RP oxides (A2BO4 are promising candidates for electrochemical energy devices, such as solid oxide fuel cells, owing to their attractive physicochemical properties, including the anisotropic nature of oxygen migration and controllable stoichiometry from oxygen excess to oxygen deficiency. Thus, understanding and controlling the kinetics of oxygen transport are essential for designing optimized materials to use in electrochemical energy devices. In this review, we first discuss the basic mechanisms of oxygen migration in RP oxides depending on oxygen nonstoichiometry. We then focus on the effect of changes in the defect concentration, crystallographic orientation, and strain on the oxygen migration in RP oxides. We also briefly review their thermal and chemical stability. Finally, we conclude with a perspective on potential research directions for future investigation to facilitate controlling oxygen ion migration in RP oxides.

  16. Mobile Monitoring and Embedded Control System for Factory Environment

    Science.gov (United States)

    Lian, Kuang-Yow; Hsiao, Sung-Jung; Sung, Wen-Tsai

    2013-01-01

    This paper proposes a real-time method to carry out the monitoring of factory zone temperatures, humidity and air quality using smart phones. At the same time, the system detects possible flames, and analyzes and monitors electrical load. The monitoring also includes detecting the vibrations of operating machinery in the factory area. The research proposes using ZigBee and Wi-Fi protocol intelligent monitoring system integration within the entire plant framework. The sensors on the factory site deliver messages and real-time sensing data to an integrated embedded systems via the ZigBee protocol. The integrated embedded system is built by the open-source 32-bit ARM (Advanced RISC Machine) core Arduino Due module, where the network control codes are built in for the ARM chipset integrated controller. The intelligent integrated controller is able to instantly provide numerical analysis results according to the received data from the ZigBee sensors. The Android APP and web-based platform are used to show measurement results. The built-up system will transfer these results to a specified cloud device using the TCP/IP protocol. Finally, the Fast Fourier Transform (FFT) approach is used to analyze the power loads in the factory zones. Moreover, Near Field Communication (NFC) technology is used to carry out the actual electricity load experiments using smart phones. PMID:24351642

  17. Mobile Monitoring and Embedded Control System for Factory Environment

    Directory of Open Access Journals (Sweden)

    Kuang-Yow Lian

    2013-12-01

    Full Text Available This paper proposes a real-time method to carry out the monitoring of factory zone temperatures, humidity and air quality using smart phones. At the same time, the system detects possible flames, and analyzes and monitors electrical load. The monitoring also includes detecting the vibrations of operating machinery in the factory area. The research proposes using ZigBee and Wi-Fi protocol intelligent monitoring system integration within the entire plant framework. The sensors on the factory site deliver messages and real-time sensing data to an integrated embedded systems via the ZigBee protocol. The integrated embedded system is built by the open-source 32-bit ARM (Advanced RISC Machine core Arduino Due module, where the network control codes are built in for the ARM chipset integrated controller. The intelligent integrated controller is able to instantly provide numerical analysis results according to the received data from the ZigBee sensors. The Android APP and web-based platform are used to show measurement results. The built-up system will transfer these results to a specified cloud device using the TCP/IP protocol. Finally, the Fast Fourier Transform (FFT approach is used to analyze the power loads in the factory zones. Moreover, Near Field Communication (NFC technology is used to carry out the actual electricity load experiments using smart phones.

  18. Arsenic and other oxyanion-forming trace elements in an alluvial basin aquifer: Evaluating sources and mobilization by isotopic tracers (Sr, B, S, O, H, Ra)

    Energy Technology Data Exchange (ETDEWEB)

    Vinson, David S., E-mail: dsv3@duke.edu [Duke University, Division of Earth and Ocean Sciences, Box 90227, Durham, NC 27708 (United States); McIntosh, Jennifer C. [University of Arizona, Department of Hydrology and Water Resources, 1133 E. James E. Rogers Way, Tucson, AZ 85721 (United States); Dwyer, Gary S.; Vengosh, Avner [Duke University, Division of Earth and Ocean Sciences, Box 90227, Durham, NC 27708 (United States)

    2011-08-15

    Highlights: > Elevated natural As and F occur in the Willcox Basin aquifer of Arizona. > Oxyanion-forming elements are derived from volcanic-source aquifer sediments. > Sr isotopes trace sediment sources linked to oxyanion-forming trace elements. > {sup 87}Sr/{sup 86}Sr > 0.720 indicates Proterozoic crystalline-source sediment contributing low As. > Both sediment source and hydrogeochemical evolution (Ca/Na) affect As levels. - Abstract: The Willcox Basin is a hydrologically closed basin in semi-arid southeastern Arizona (USA) and, like many other alluvial basins in the southwestern USA, is characterized by oxic, near-neutral to slightly basic groundwater containing naturally elevated levels of oxyanion-forming trace elements such as As. This study evaluates the sources and mobilization of these oxyanionic trace elements of health significance by using several isotopic tracers of water-rock interaction and groundwater sources ({sup 87}Sr/{sup 86}Sr, {delta}{sup 34}S{sub SO4}, {delta}{sup 11}B, {delta}{sup 2}H, {delta}{sup 18}O, {sup 3}H). Values of {delta}{sup 2}H (-85 per mille to -64 per mille) and {delta}{sup 18}O (-11.8 per mille to -8.6 per mille) are consistent with precipitation and groundwater in adjacent alluvial basins, and low to non-detectable {sup 3}H activities further imply that modern recharge is slow in this semi-arid environment. Large variations in {sup 87}Sr/{sup 86}Sr ratios imply that groundwater has interacted with multiple sediment sources that constitute the basin-fill aquifer, including Tertiary felsic volcanic rocks, Paleozoic sedimentary rocks, and Proterozoic crystalline rocks. In general, low concentrations of oxyanion-forming trace elements and F{sup -} are associated with a group of waters exhibiting highly radiogenic values of {sup 87}Sr/{sup 86}Sr (0.72064-0.73336) consistent with waters in Proterozoic crystalline rocks in the mountain blocks (0.73247-0.75010). Generally higher As concentrations (2-29 {mu}g L{sup -1}), other

  19. Arsenate reduction and mobilization in the presence of indigenous aerobic bacteria obtained from high arsenic aquifers of the Hetao basin, Inner Mongolia

    International Nuclear Information System (INIS)

    Guo, Huaming; Liu, Zeyun; Ding, Susu; Hao, Chunbo; Xiu, Wei; Hou, Weiguo

    2015-01-01

    Intact aquifer sediments were collected to obtain As-resistant bacteria from the Hetao basin. Two strains of aerobic As-resistant bacteria (Pseudomonas sp. M17-1 and Bacillus sp. M17-15) were isolated from the aquifer sediments. Those strains exhibited high resistances to both As(III) and As(V). Results showed that both strains had arr and ars genes, and led to reduction of dissolved As(V), goethite-adsorbed As(V), scorodite As(V) and sediment As(V), in the presence of organic carbon as the carbon source. After reduction of solid As(V), As release was observed from the solids to solutions. Strain M17-15 had a higher ability than strain M17-1 in reducing As(V) and promoting the release of As. These results suggested that the strains would mediate As(V) reduction to As(III), and thereafter release As(III), due to the higher mobility of As(III) in most aquifer systems. The processes would play an important role in genesis of high As groundwater. - Highlights: • Two strains of As-resistant bacteria were isolated from high As aquifer sediment. • The strains (M17–1 and M17-15) had an As tolerance under oxic conditions. • The strains had arr and ars genes, and reduced both dissolved As(V) and solid As(V). • Reduction of solid As(V) resulted in As release into solutions. • M17-15 had a higher ability in reducing As(V) and promoting As release than M17-1. - Indigenous aerobic bacteria from the high-As aquifer sediment had arr and ars genes and led to reduction of dissolved As(V), goethite-adsorbed As(V), scorodite As(V) and sedimentary As

  20. Admission Control for Multiservices Traffic in Hierarchical Mobile IPv6 Networks by Using Fuzzy Inference System

    Directory of Open Access Journals (Sweden)

    Jung-Shyr Wu

    2012-01-01

    Full Text Available CAC (Call Admission Control plays a significant role in providing QoS (Quality of Service in mobile wireless networks. In addition to much research that focuses on modified Mobile IP to get better efficient handover performance, CAC should be introduced to Mobile IP-based network to guarantee the QoS for users. In this paper, we propose a CAC scheme which incorporates multiple traffic types and adjusts the admission threshold dynamically using fuzzy control logic to achieve better usage of resources. The method can provide QoS in Mobile IPv6 networks with few modifications on MAP (Mobility Anchor Point functionality and slight change in BU (Binding Update message formats. According to the simulation results, the proposed scheme presents good performance of voice and video traffic at the expenses of poor performance on data traffic. It is evident that these CAC schemes can reduce the probability of the handoff dropping and the cell overload and limit the probability of the new call blocking.

  1. A case-control study of risk of leukaemia in relation to mobile phone use.

    Science.gov (United States)

    Cooke, R; Laing, S; Swerdlow, A J

    2010-11-23

    Mobile phone use is now ubiquitous, and scientific reviews have recommended research into its relation to leukaemia risk, but no large studies have been conducted. In a case-control study in South East England to investigate the relation of acute and non-lymphocytic leukaemia risk to mobile phone use, 806 cases with leukaemia incident 2003-2009 at ages 18-59 years (50% of those identified as eligible) and 585 non-blood relatives as controls (provided by 392 cases) were interviewed about mobile phone use and other potentially aetiological variables. No association was found between regular mobile phone use and risk of leukaemia (odds ratio (OR)=1.06, 95% confidence interval (CI)=0.76, 1.46). Analyses of risk in relation to years since first use, lifetime years of use, cumulative number of calls and cumulative hours of use produced no significantly raised risks, and there was no evidence of any trends. A non-significantly raised risk was found in people who first used a phone 15 or more years ago (OR=1.87, 95% CI=0.96, 3.63). Separate analyses of analogue and digital phone use and leukaemia subtype produced similar results to those overall. This study suggests that use of mobile phones does not increase leukaemia risk, although the possibility of an effect after long-term use, while biologically unlikely, remains open.

  2. Binational Arsenic Exposure Survey: Methodology and Estimated Arsenic Intake from Drinking Water and Urinary Arsenic Concentrations

    Directory of Open Access Journals (Sweden)

    Robin B. Harris

    2012-03-01

    Full Text Available The Binational Arsenic Exposure Survey (BAsES was designed to evaluate probable arsenic exposures in selected areas of southern Arizona and northern Mexico, two regions with known elevated levels of arsenic in groundwater reserves. This paper describes the methodology of BAsES and the relationship between estimated arsenic intake from beverages and arsenic output in urine. Households from eight communities were selected for their varying groundwater arsenic concentrations in Arizona, USA and Sonora, Mexico. Adults responded to questionnaires and provided dietary information. A first morning urine void and water from all household drinking sources were collected. Associations between urinary arsenic concentration (total, organic, inorganic and estimated level of arsenic consumed from water and other beverages were evaluated through crude associations and by random effects models. Median estimated total arsenic intake from beverages among participants from Arizona communities ranged from 1.7 to 14.1 µg/day compared to 0.6 to 3.4 µg/day among those from Mexico communities. In contrast, median urinary inorganic arsenic concentrations were greatest among participants from Hermosillo, Mexico (6.2 µg/L whereas a high of 2.0 µg/L was found among participants from Ajo, Arizona. Estimated arsenic intake from drinking water was associated with urinary total arsenic concentration (p < 0.001, urinary inorganic arsenic concentration (p < 0.001, and urinary sum of species (p < 0.001. Urinary arsenic concentrations increased between 7% and 12% for each one percent increase in arsenic consumed from drinking water. Variability in arsenic intake from beverages and urinary arsenic output yielded counter intuitive results. Estimated intake of arsenic from all beverages was greatest among Arizonans yet participants in Mexico had higher urinary total and inorganic arsenic concentrations. Other contributors to urinary arsenic concentrations should be evaluated.

  3. Robust Feedback Linearization-based Control Design for a Wheeled Mobile Robot

    DEFF Research Database (Denmark)

    Bendtsen, Jan Dimon; Andersen, Palle; Pedersen, Tom Søndergaard

    This paper considers the trajectory tracking problem for a four-wheel driven, four-wheel steered mobile robot moving in outdoor terrain. The robot is modeled as a non-holonomic dynamic system subject to pure rolling, no-slip constraints. A nonlinear trajectory tracking feedback control law based...

  4. Performance of high-level and low-level control for coordination of mobile robots

    NARCIS (Netherlands)

    Adinandra, S.; Caarls, J.; Kostic, D.; Nijmeijer, H.

    2010-01-01

    We analyze performance of different strategies for coordinated control of mobile robots. By considering an environment of a distribution center, the robots should transport goods from place A to place B while maintaining the desired formation and avoiding collisions. We evaluate performance of two

  5. Mobile Phone-Delivered Cognitive Behavioral Therapy for Insomnia : A Randomized Waitlist Controlled Trial

    NARCIS (Netherlands)

    Horsch, C.H.G.; Lancee, J.; Griffioen-Both, F.; Spruit, S.; Fitrianie, S.; Neerincx, M.A.; Beun, R.J.; Brinkman, W.-P.

    Background: This study is one of the first randomized controlled trials investigating cognitive behavioral therapy for insomnia (CBT-I) delivered by a fully automated mobile phone app. Such an app can potentially increase the accessibility of insomnia treatment for the 10% of people who have

  6. Mobile Phone-Delivered Cognitive Behavioral Therapy for Insomnia : A Randomized Waitlist Controlled Trial

    NARCIS (Netherlands)

    Horsch, C.H.G.; Lancee, J; Griffioen-Both, Fiemke; Spruit, Sandor; Fitrianie, S.; Neerincx, M.A.; Beun, RJ; Brinkman, W.P.

    2017-01-01

    Background: This study is one of the first randomized controlled trials investigating cognitive behavioral therapy for insomnia (CBT-I) delivered by a fully automated mobile phone app. Such an app can potentially increase the accessibility of insomnia treatment for the 10% of people who have

  7. Nonlinear smith-predictor based control strategy for a unicycle mobile robot subject to transport delay

    NARCIS (Netherlands)

    Alvarez Aguirre, A.; Velasco-Villa, M.; Del Muro Cuellar, B.

    2008-01-01

    This paper consider the remote control of an unicycle mobile robot subject to transport delay. The communication delay effects are considered by means of a discrete time approach that allows to solve the path tracking problem in terms of the delayed input. The causality problem involved in the

  8. Design of an arbitrary path-following controller for a non-holonomic mobile platform

    CSIR Research Space (South Africa)

    Sabatta, DG

    2009-11-01

    Full Text Available required for the platform to asymptotically track the path. The controller derived in this paper is implemented on the Seekur platform from Mobile Robots. Results showing the following of a pre-recorded path from differential GPS are discussed....

  9. Environmental biochemistry of arsenic

    Energy Technology Data Exchange (ETDEWEB)

    Tamaki, S.; Frankenberger, W.T. Jr. (Department of Soil and Environmental Sciences, University of California, Riverside (United States))

    1992-01-01

    Microorganisms are involved in the redistribution and global cycling of arsenic. Arsenic can accumulate and can be subject to various biotransformations including reduction, oxidation, and methylation. Bacterial methylation of inorganic arsenic is coupled to the methane biosynthetic pathway in methanogenic bacteria under anaerobic conditions and may be a mechanism for arsenic detoxification. The pathway proceeds by reduction of arsenate to arsenite followed by methylation to dimethylarsine. Fungi are also able to transform inorganic and organic arsenic compounds into volatile methylarsines. The pathway proceeds aerobically by arsenate reduction to arsenite followed by several methylation steps producing trimethylarsine. Volatile arsine gases are very toxic to mammals because they destroy red blood cells (LD50 in rats; 3.0 mg kg-1). Further studies are needed on dimethylarsine and trimethylarsine toxicity tests through inhalation of target animals. Marine algae transform arsenate into non-volatile methylated arsenic compounds (methanearsonic and dimethylarsinic acids) in seawater. This is considered to be a beneficial step not only to the primary producers, but also to the higher trophic levels, since non-volatile methylated arsenic is much less toxic to marine invertebrates. Freshwater algae like marine algae synthesize lipid-soluble arsenic compounds and do not produce volatile methylarsines. Aquatic plants also synthesize similar lipid-soluble arsenic compounds. In terrestrial plants, arsenate is preferentially taken up 3 to 4 times the rate of arsenite. In the presence of phosphate, arsenate uptake is inhibited while in the presence of arsenate, phosphate uptake is only slightly inhibited. There is a competitive interaction between arsenate and phosphate for the same uptake system in terrestrial plants.

  10. Different low-molecular-mass organic acids specifically control leaching of arsenic and lead from contaminated soil.

    Science.gov (United States)

    Ash, Christopher; Tejnecký, Václav; Borůvka, Luboš; Drábek, Ondřej

    2016-04-01

    Low-molecular-mass organic acids (LMMOA) are of key importance for mobilisation and fate of metals in soil, by functioning as ligands that increase the amount of dissolved metal in solution or by dissociation of metal binding minerals. Column leaching experiments were performed on soil polluted with As and Pb, in order to determine the specificity of LMMOA related release for individual elements, at varying organic acid concentrations. Acetic, citric and oxalic acids were applied in 12h leaching experiments over a concentration range (0.5-25 mM) to soil samples that represent organic and mineral horizons. The leaching of As followed the order: oxalic>citric>acetic acid in both soils. Arsenic leaching was attributed primarily to ligand-enhanced dissolution of mineral oxides followed by As released into solution, as shown by significant correlation between oxalic and citric acids and content of Al and Fe in leaching solutions. Results suggest that subsurface mineral soil layers are more vulnerable to As toxicity. Leaching of Pb from both soils followed the order: citric>oxalic>acetic acid. Mineral soil samples were shown to be more susceptible to leaching of Pb than samples characterised by a high content of organic matter. The leaching efficiency of citric acid was attributed to formation of stable complexes with Pb ions, which other acids are not capable of. Results obtained in the study are evidence that the extent of As and Pb leaching in contaminated surface and subsurface soil depends significantly on the types of carboxylic acid involved. The implications of the type of acid and the specific element that can be mobilised become increasingly significant where LMMOA concentrations are highest, such as in rhizosphere soil. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Adaptive Tracking and Obstacle Avoidance Control for Mobile Robots with Unknown Sliding

    Directory of Open Access Journals (Sweden)

    Mingyue Cui

    2012-11-01

    Full Text Available An adaptive control approach is proposed for trajectory tracking and obstacle avoidance for mobile robots with consideration given to unknown sliding. A kinematic model of mobile robots is established in this paper, in which both longitudinal and lateral sliding are considered and processed as three time-varying parameters. A sliding model observer is introduced to estimate the sliding parameters online. A stable tracking control law for this nonholonomic system is proposed to compensate the unknown sliding effect. From Lyapunov-stability analysis, it is proved, regardless of unknown sliding, that tracking errors of the controlled closed-loop system are asymptotically stable, the tracking errors converge to zero outside the obstacle detection region and obstacle avoidance is guaranteed inside the obstacle detection region. The efficiency and robustness of the proposed control system are verified by simulation results.

  12. Chronic occupational exposure to arsenic induces carcinogenic gene signaling networks and neoplastic transformation in human lung epithelial cells

    International Nuclear Information System (INIS)

    Stueckle, Todd A.; Lu, Yongju; Davis, Mary E.; Wang, Liying; Jiang, Bing-Hua; Holaskova, Ida; Schafer, Rosana; Barnett, John B.; Rojanasakul, Yon

    2012-01-01

    Chronic arsenic exposure remains a human health risk; however a clear mode of action to understand gene signaling-driven arsenic carcinogenesis is currently lacking. This study chronically exposed human lung epithelial BEAS-2B cells to low-dose arsenic trioxide to elucidate cancer promoting gene signaling networks associated with arsenic-transformed (B-As) cells. Following a 6 month exposure, exposed cells were assessed for enhanced cell proliferation, colony formation, invasion ability and in vivo tumor formation compared to control cell lines. Collected mRNA was subjected to whole genome expression microarray profiling followed by in silico Ingenuity Pathway Analysis (IPA) to identify lung carcinogenesis modes of action. B-As cells displayed significant increases in proliferation, colony formation and invasion ability compared to BEAS-2B cells. B-As injections into nude mice resulted in development of primary and secondary metastatic tumors. Arsenic exposure resulted in widespread up-regulation of genes associated with mitochondrial metabolism and increased reactive oxygen species protection suggesting mitochondrial dysfunction. Carcinogenic initiation via reactive oxygen species and epigenetic mechanisms was further supported by altered DNA repair, histone, and ROS-sensitive signaling. NF-κB, MAPK and NCOR1 signaling disrupted PPARα/δ-mediated lipid homeostasis. A ‘pro-cancer’ gene signaling network identified increased survival, proliferation, inflammation, metabolism, anti-apoptosis and mobility signaling. IPA-ranked signaling networks identified altered p21, EF1α, Akt, MAPK, and NF-κB signaling networks promoting genetic disorder, altered cell cycle, cancer and changes in nucleic acid and energy metabolism. In conclusion, transformed B-As cells with their whole genome expression profile provide an in vitro arsenic model for future lung cancer signaling research and data for chronic arsenic exposure risk assessment. Highlights: ► Chronic As 2 O 3

  13. Chronic occupational exposure to arsenic induces carcinogenic gene signaling networks and neoplastic transformation in human lung epithelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Stueckle, Todd A., E-mail: tstueckle@hsc.wvu.edu [Department of Basic Pharmaceutical Sciences, West Virginia University, Morgantown, WV 26506 (United States); Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505 (United States); Lu, Yongju, E-mail: yongju6@hotmail.com [Department of Basic Pharmaceutical Sciences, West Virginia University, Morgantown, WV 26506 (United States); Davis, Mary E., E-mail: mdavis@wvu.edu [Department of Physiology, West Virginia University, Morgantown, WV 26506 (United States); Wang, Liying, E-mail: lmw6@cdc.gov [Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505 (United States); Jiang, Bing-Hua, E-mail: bhjiang@jefferson.edu [Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107 (United States); Holaskova, Ida, E-mail: iholaskova@hsc.wvu.edu [Department of Microbiology, Immunology and Cell Biology, West Virginia University, Morgantown, WV 26506 (United States); Schafer, Rosana, E-mail: rschafer@hsc.wvu.edu [Department of Microbiology, Immunology and Cell Biology, West Virginia University, Morgantown, WV 26506 (United States); Barnett, John B., E-mail: jbarnett@hsc.wvu.edu [Department of Microbiology, Immunology and Cell Biology, West Virginia University, Morgantown, WV 26506 (United States); Rojanasakul, Yon, E-mail: yrojan@hsc.wvu.edu [Department of Basic Pharmaceutical Sciences, West Virginia University, Morgantown, WV 26506 (United States)

    2012-06-01

    Chronic arsenic exposure remains a human health risk; however a clear mode of action to understand gene signaling-driven arsenic carcinogenesis is currently lacking. This study chronically exposed human lung epithelial BEAS-2B cells to low-dose arsenic trioxide to elucidate cancer promoting gene signaling networks associated with arsenic-transformed (B-As) cells. Following a 6 month exposure, exposed cells were assessed for enhanced cell proliferation, colony formation, invasion ability and in vivo tumor formation compared to control cell lines. Collected mRNA was subjected to whole genome expression microarray profiling followed by in silico Ingenuity Pathway Analysis (IPA) to identify lung carcinogenesis modes of action. B-As cells displayed significant increases in proliferation, colony formation and invasion ability compared to BEAS-2B cells. B-As injections into nude mice resulted in development of primary and secondary metastatic tumors. Arsenic exposure resulted in widespread up-regulation of genes associated with mitochondrial metabolism and increased reactive oxygen species protection suggesting mitochondrial dysfunction. Carcinogenic initiation via reactive oxygen species and epigenetic mechanisms was further supported by altered DNA repair, histone, and ROS-sensitive signaling. NF-κB, MAPK and NCOR1 signaling disrupted PPARα/δ-mediated lipid homeostasis. A ‘pro-cancer’ gene signaling network identified increased survival, proliferation, inflammation, metabolism, anti-apoptosis and mobility signaling. IPA-ranked signaling networks identified altered p21, EF1α, Akt, MAPK, and NF-κB signaling networks promoting genetic disorder, altered cell cycle, cancer and changes in nucleic acid and energy metabolism. In conclusion, transformed B-As cells with their whole genome expression profile provide an in vitro arsenic model for future lung cancer signaling research and data for chronic arsenic exposure risk assessment. Highlights: ► Chronic As{sub 2}O

  14. Bioinspired Intelligent Algorithm and Its Applications for Mobile Robot Control: A Survey

    Directory of Open Access Journals (Sweden)

    Jianjun Ni

    2016-01-01

    Full Text Available Bioinspired intelligent algorithm (BIA is a kind of intelligent computing method, which is with a more lifelike biological working mechanism than other types. BIAs have made significant progress in both understanding of the neuroscience and biological systems and applying to various fields. Mobile robot control is one of the main application fields of BIAs which has attracted more and more attention, because mobile robots can be used widely and general artificial intelligent algorithms meet a development bottleneck in this field, such as complex computing and the dependence on high-precision sensors. This paper presents a survey of recent research in BIAs, which focuses on the research in the realization of various BIAs based on different working mechanisms and the applications for mobile robot control, to help in understanding BIAs comprehensively and clearly. The survey has four primary parts: a classification of BIAs from the biomimetic mechanism, a summary of several typical BIAs from different levels, an overview of current applications of BIAs in mobile robot control, and a description of some possible future directions for research.

  15. Bioinspired Intelligent Algorithm and Its Applications for Mobile Robot Control: A Survey.

    Science.gov (United States)

    Ni, Jianjun; Wu, Liuying; Fan, Xinnan; Yang, Simon X

    2016-01-01

    Bioinspired intelligent algorithm (BIA) is a kind of intelligent computing method, which is with a more lifelike biological working mechanism than other types. BIAs have made significant progress in both understanding of the neuroscience and biological systems and applying to various fields. Mobile robot control is one of the main application fields of BIAs which has attracted more and more attention, because mobile robots can be used widely and general artificial intelligent algorithms meet a development bottleneck in this field, such as complex computing and the dependence on high-precision sensors. This paper presents a survey of recent research in BIAs, which focuses on the research in the realization of various BIAs based on different working mechanisms and the applications for mobile robot control, to help in understanding BIAs comprehensively and clearly. The survey has four primary parts: a classification of BIAs from the biomimetic mechanism, a summary of several typical BIAs from different levels, an overview of current applications of BIAs in mobile robot control, and a description of some possible future directions for research.

  16. Bioinspired Intelligent Algorithm and Its Applications for Mobile Robot Control: A Survey

    Science.gov (United States)

    Ni, Jianjun; Wu, Liuying; Fan, Xinnan; Yang, Simon X.

    2016-01-01

    Bioinspired intelligent algorithm (BIA) is a kind of intelligent computing method, which is with a more lifelike biological working mechanism than other types. BIAs have made significant progress in both understanding of the neuroscience and biological systems and applying to various fields. Mobile robot control is one of the main application fields of BIAs which has attracted more and more attention, because mobile robots can be used widely and general artificial intelligent algorithms meet a development bottleneck in this field, such as complex computing and the dependence on high-precision sensors. This paper presents a survey of recent research in BIAs, which focuses on the research in the realization of various BIAs based on different working mechanisms and the applications for mobile robot control, to help in understanding BIAs comprehensively and clearly. The survey has four primary parts: a classification of BIAs from the biomimetic mechanism, a summary of several typical BIAs from different levels, an overview of current applications of BIAs in mobile robot control, and a description of some possible future directions for research. PMID:26819582

  17. Channel Access and Power Control for Mobile Crowdsourcing in Device-to-Device Underlaid Cellular Networks

    Directory of Open Access Journals (Sweden)

    Yue Ma

    2018-01-01

    Full Text Available With the access of a myriad of smart handheld devices in cellular networks, mobile crowdsourcing becomes increasingly popular, which can leverage omnipresent mobile devices to promote the complicated crowdsourcing tasks. Device-to-device (D2D communication is highly desired in mobile crowdsourcing when cellular communications are costly. The D2D cellular network is more preferable for mobile crowdsourcing than conventional cellular network. Therefore, this paper addresses the channel access and power control problem in the D2D underlaid cellular networks. We propose a novel semidistributed network-assisted power and a channel access control scheme for D2D user equipment (DUE pieces. It can control the interference from DUE pieces to the cellular user accurately and has low information feedback overhead. For the proposed scheme, the stochastic geometry tool is employed and analytic expressions are derived for the coverage probabilities of both the cellular link and D2D links. We analyze the impact of key system parameters on the proposed scheme. The Pareto optimal access threshold maximizing the total area spectral efficiency is obtained. Unlike the existing works, the performances of the cellular link and D2D links are both considered. Simulation results show that the proposed method can improve the total area spectral efficiency significantly compared to existing schemes.

  18. Adaptive Control for Autonomous Navigation of Mobile Robots Considering Time Delay and Uncertainty

    Science.gov (United States)

    Armah, Stephen Kofi

    Autonomous control of mobile robots has attracted considerable attention of researchers in the areas of robotics and autonomous systems during the past decades. One of the goals in the field of mobile robotics is development of platforms that robustly operate in given, partially unknown, or unpredictable environments and offer desired services to humans. Autonomous mobile robots need to be equipped with effective, robust and/or adaptive, navigation control systems. In spite of enormous reported work on autonomous navigation control systems for mobile robots, achieving the goal above is still an open problem. Robustness and reliability of the controlled system can always be improved. The fundamental issues affecting the stability of the control systems include the undesired nonlinear effects introduced by actuator saturation, time delay in the controlled system, and uncertainty in the model. This research work develops robustly stabilizing control systems by investigating and addressing such nonlinear effects through analytical, simulations, and experiments. The control systems are designed to meet specified transient and steady-state specifications. The systems used for this research are ground (Dr Robot X80SV) and aerial (Parrot AR.Drone 2.0) mobile robots. Firstly, an effective autonomous navigation control system is developed for X80SV using logic control by combining 'go-to-goal', 'avoid-obstacle', and 'follow-wall' controllers. A MATLAB robot simulator is developed to implement this control algorithm and experiments are conducted in a typical office environment. The next stage of the research develops an autonomous position (x, y, and z) and attitude (roll, pitch, and yaw) controllers for a quadrotor, and PD-feedback control is used to achieve stabilization. The quadrotor's nonlinear dynamics and kinematics are implemented using MATLAB S-function to generate the state output. Secondly, the white-box and black-box approaches are used to obtain a linearized

  19. Promise of a low power mobile CPU based embedded system in artificial leg control.

    Science.gov (United States)

    Hernandez, Robert; Zhang, Fan; Zhang, Xiaorong; Huang, He; Yang, Qing

    2012-01-01

    This paper presents the design and implementation of a low power embedded system using mobile processor technology (Intel Atom™ Z530 Processor) specifically tailored for a neural-machine interface (NMI) for artificial limbs. This embedded system effectively performs our previously developed NMI algorithm based on neuromuscular-mechanical fusion and phase-dependent pattern classification. The analysis shows that NMI embedded system can meet real-time constraints with high accuracies for recognizing the user's locomotion mode. Our implementation utilizes the mobile processor efficiently to allow a power consumption of 2.2 watts and low CPU utilization (less than 4.3%) while executing the complex NMI algorithm. Our experiments have shown that the highly optimized C program implementation on the embedded system has superb advantages over existing PC implementations on MATLAB. The study results suggest that mobile-CPU-based embedded system is promising for implementing advanced control for powered lower limb prostheses.

  20. Quantifying the impact of selection bias caused by nonparticipation in a case-control study of mobile phone use

    DEFF Research Database (Denmark)

    Vrijheid, Martine; Richardson, Lesley; Armstrong, Bruce K

    2009-01-01

    To quantitatively assess the impact of selection bias caused by nonparticipation in a multinational case-control study of mobile phone use and brain tumor.......To quantitatively assess the impact of selection bias caused by nonparticipation in a multinational case-control study of mobile phone use and brain tumor....

  1. Attenuation of arsenic neurotoxicity by curcumin in rats

    International Nuclear Information System (INIS)

    Yadav, Rajesh S.; Sankhwar, Madhu Lata; Shukla, Rajendra K.; Chandra, Ramesh; Pant, Aditya B.; Islam, Fakhrul; Khanna, Vinay K.

    2009-01-01

    In view of continued exposure to arsenic and associated human health risk including neurotoxicity, neuroprotective efficacy of curcumin, a polyphenolic antioxidant, has been investigated in rats. A significant decrease in locomotor activity, grip strength (26%) and rota-rod performance (82%) was observed in rats treated with arsenic (sodium arsenite, 20 mg/kg body weight, p.o., 28 days) as compared to controls. The arsenic treated rats also exhibited a decrease in the binding of striatal dopamine receptors (32%) and tyrosine hydroxylase (TH) immunoreactivity (19%) in striatum. Increased arsenic levels in corpus striatum (6.5 fold), frontal cortex (6.3 fold) and hippocampus (7.0 fold) associated with enhanced oxidative stress in these brain regions, as evident by an increase in lipid perioxidation, protein carbonyl and a decrease in the levels of glutathione and activity of superoxide dismutase, catalase and glutathione peroxidase with differential effects were observed in arsenic treated rats compared to controls. Simultaneous treatment with arsenic (sodium arsenite, 20 mg/kg body weight, p.o., 28 days) and curcumin (100 mg/kg body weight, p.o., 28 days) caused an increase in locomotor activity and grip strength and improved the rota-rod performance in comparison to arsenic treated rats. Binding of striatal dopamine receptors and TH expression increased while arsenic levels and oxidative stress decreased in these brain regions in co-treated rats as compared to those treated with arsenic alone. No significant effect on any of these parameters was observed in rats treated with curcumin (100 mg/kg body weight, p.o., 28 days) alone compared to controls. A significant protection in behavioral, neurochemical and immunohistochemical parameters in rats simultaneously treated with arsenic and curcumin suggest the neuroprotective efficacy of curcumin.

  2. Review of Coagulation Technology for Removal of Arsenic: Case of Chile

    OpenAIRE

    Sancha, Ana María

    2006-01-01

    Coagulation technology has been used since 1970 in northern Chile for removing arsenic from drinking-water. This experience suggests that coagulation is an effective technology for the removal of arsenic. It is currently possible to reduce arsenic from 400 μg/L to 10 μg/L at a rate of 500 L/sec, assuming pH, oxidizing and coagulation agents are strictly controlled. The Chilean experience with the removal of arsenic demonstrates that the water matrix dictates the selection of the arsenic-remov...

  3. [Study of relationship between arsenic methylation and skin lesion in a population with long-term high arsenic exposure].

    Science.gov (United States)

    Su, Liqin; Cheng, Yibin; Lin, Shaobin; Wu, Chuanye

    2007-05-01

    To investigate the difference of arsenic metabolism in populations with long-term high arsenic exposure and explore the relationship between arsenic metabolism diversity and skin lesion. 327 residents in an arsenic polluted village were voluntarily enrolled in this study. Questionnaire survey and medical examination were carried out to learn basic information and detect skin lesions. Urinary inorganic and methylated arsenic were speciated by high performance liquid chromatography combined with hydride-generation atomic fluorescence spectrometry. Total arsenic concentration in hair was determined with DDC-Ag method. Hair arsenic content of studied polutions was generally high, but no significant difference were found among the studied four groups. MMA and DMA concentration in urine increased with studied polution age, and were positively related with skin lesion grade. The relative proportion of MMA in serious skin lesion group was significantly higher than in other 3 groups, while DMA/MMA ratio was significantly lower than control and mild group. The relative proportion of MMA was positively related with skin lesion grade, DMA/ MMA ratio was negatively related with skin lesion grade. Males could have higher arsenic cumulation and lower methylation capacity than those of females. The population of above 40 years old may have higher methylation capacity than those of adults below 40yeas old. Smokers and drinkers seemed lower methylation capacity than those of non-smokers and non-drinkers respectively. The methylation of arsenic could affect by several factors, including age gender, smoking and drinking. Arsenic methylation copacity mey be associated with skin lesion induced by arsenic exposure.

  4. Trophic Transfer of Arsenic from an Aquatic Insect to Terrestrial Insect Predators.

    Science.gov (United States)

    Mogren, Christina L; Walton, William E; Parker, David R; Trumble, John T

    2013-01-01

    The movement of energy and nutrients from aquatic to terrestrial ecosystems can be substantial, and emergent aquatic insects can serve as biovectors not only for nutrients, but also for contaminants present in the aquatic environment. The terrestrial predators Tenodera aridifolia sinensis (Mantodea: Mantidae) and Tidarren haemorrhoidale (Araneae: Theridiidae) and the aquatic predator Buenoa scimitra (Hemiptera: Notonectidae) were chosen to evaluate the efficacy of arsenic transfer between aquatic and terrestrial environments. Culex tarsalis larvae were reared in either control water or water containing 1000 µg l(-1) arsenic. Adults that emerged from the control and arsenic treatments were fed to the terrestrial predators, and fourth instar larvae were fed to the aquatic predator reared in control or arsenic contaminated water. Tenodera a. sinensis fed arsenic-treated Cx. tarsalis accumulated 658±130 ng g(-1) of arsenic. There was no significant difference between control and arsenic-fed T. haemorrhoidale (range 142-290 ng g(-1)). Buenoa scimitra accumulated 5120±406 ng g(-1) of arsenic when exposed to arsenic-fed Cx. tarsalis and reared in water containing 1000 µg l(-1) arsenic. There was no significant difference between controls or arsenic-fed B. scimitra that were not exposed to water-borne arsenic, indicating that for this species environmental exposure was more important in accumulation than strictly dietary arsenic. These results indicate that transfer to terrestrial predators may play an important role in arsenic cycling, which would be particularly true during periods of mass emergence of potential insect biovectors. Trophic transfer within the aquatic environment may still occur with secondary predation, or in predators with different feeding strategies.

  5. Trophic Transfer of Arsenic from an Aquatic Insect to Terrestrial Insect Predators

    Science.gov (United States)

    Mogren, Christina L.; Walton, William E.; Parker, David R.; Trumble, John T.

    2013-01-01

    The movement of energy and nutrients from aquatic to terrestrial ecosystems can be substantial, and emergent aquatic insects can serve as biovectors not only for nutrients, but also for contaminants present in the aquatic environment. The terrestrial predators Tenodera aridifolia sinensis (Mantodea: Mantidae) and Tidarren haemorrhoidale (Araneae: Theridiidae) and the aquatic predator Buenoa scimitra (Hemiptera: Notonectidae) were chosen to evaluate the efficacy of arsenic transfer between aquatic and terrestrial environments. Culex tarsalis larvae were reared in either control water or water containing 1000 µg l−1 arsenic. Adults that emerged from the control and arsenic treatments were fed to the terrestrial predators, and fourth instar larvae were fed to the aquatic predator reared in control or arsenic contaminated water. Tenodera a. sinensis fed arsenic-treated Cx. tarsalis accumulated 658±130 ng g−1 of arsenic. There was no significant difference between control and arsenic-fed T. haemorrhoidale (range 142–290 ng g−1). Buenoa scimitra accumulated 5120±406 ng g−1 of arsenic when exposed to arsenic-fed Cx. tarsalis and reared in water containing 1000 µg l−1 arsenic. There was no significant difference between controls or arsenic-fed B. scimitra that were not exposed to water-borne arsenic, indicating that for this species environmental exposure was more important in accumulation than strictly dietary arsenic. These results indicate that transfer to terrestrial predators may play an important role in arsenic cycling, which would be particularly true during periods of mass emergence of potential insect biovectors. Trophic transfer within the aquatic environment may still occur with secondary predation, or in predators with different feeding strategies. PMID:23826344

  6. Trophic Transfer of Arsenic from an Aquatic Insect to Terrestrial Insect Predators.

    Directory of Open Access Journals (Sweden)

    Christina L Mogren

    Full Text Available The movement of energy and nutrients from aquatic to terrestrial ecosystems can be substantial, and emergent aquatic insects can serve as biovectors not only for nutrients, but also for contaminants present in the aquatic environment. The terrestrial predators Tenodera aridifolia sinensis (Mantodea: Mantidae and Tidarren haemorrhoidale (Araneae: Theridiidae and the aquatic predator Buenoa scimitra (Hemiptera: Notonectidae were chosen to evaluate the efficacy of arsenic transfer between aquatic and terrestrial environments. Culex tarsalis larvae were reared in either control water or water containing 1000 µg l(-1 arsenic. Adults that emerged from the control and arsenic treatments were fed to the terrestrial predators, and fourth instar larvae were fed to the aquatic predator reared in control or arsenic contaminated water. Tenodera a. sinensis fed arsenic-treated Cx. tarsalis accumulated 658±130 ng g(-1 of arsenic. There was no significant difference between control and arsenic-fed T. haemorrhoidale (range 142-290 ng g(-1. Buenoa scimitra accumulated 5120±406 ng g(-1 of arsenic when exposed to arsenic-fed Cx. tarsalis and reared in water containing 1000 µg l(-1 arsenic. There was no significant difference between controls or arsenic-fed B. scimitra that were not exposed to water-borne arsenic, indicating that for this species environmental exposure was more important in accumulation than strictly dietary arsenic. These results indicate that transfer to terrestrial predators may play an important role in arsenic cycling, which would be particularly true during periods of mass emergence of potential insect biovectors. Trophic transfer within the aquatic environment may still occur with secondary predation, or in predators with different feeding strategies.

  7. Mobile application as a prenatal education and engagement tool: A randomized controlled pilot.

    Science.gov (United States)

    Ledford, Christy J W; Canzona, Mollie Rose; Cafferty, Lauren A; Hodge, Joshua A

    2016-04-01

    Research has shown that mobile applications provide a powerful alternative to traditional paper diaries; however, little data exists in comparing apps to the traditional mode of paper as a patient education and engagement tool in the clinical setting. This study was designed to compare the effectiveness of a mobile app versus a spiral-notebook guide throughout prenatal care. This randomized (n=173) controlled pilot was conducted at an East Coast community hospital. Chi-square and repeated-measures analysis of variance was used to test intervention effects in the sample of 127 pregnant mothers who completed their prenatal care in the healthcare system. Patients who were distributed the mobile application used the tool to record information about pregnancy more frequently (p=.04) and developed greater patient activation (p=.02) than patients who were distributed notebooks. No difference was detected on interpersonal clinical communication. A mobile application successfully activated a patient population in which self-management is a critical factor. This study shows that mobile apps can prompt greater use and result in more activated patients. Findings may be translated to other patient populations who receive recurring care for chronic disease. Published by Elsevier Ireland Ltd.

  8. A leptin-regulated circuit controls glucose mobilization during noxious stimuli.

    Science.gov (United States)

    Flak, Jonathan N; Arble, Deanna; Pan, Warren; Patterson, Christa; Lanigan, Thomas; Goforth, Paulette B; Sacksner, Jamie; Joosten, Maja; Morgan, Donald A; Allison, Margaret B; Hayes, John; Feldman, Eva; Seeley, Randy J; Olson, David P; Rahmouni, Kamal; Myers, Martin G

    2017-08-01

    Adipocytes secrete the hormone leptin to signal the sufficiency of energy stores. Reductions in circulating leptin concentrations reflect a negative energy balance, which augments sympathetic nervous system (SNS) activation in response to metabolically demanding emergencies. This process ensures adequate glucose mobilization despite low energy stores. We report that leptin receptor-expressing neurons (LepRb neurons) in the periaqueductal gray (PAG), the largest population of LepRb neurons in the brain stem, mediate this process. Application of noxious stimuli, which often signal the need to mobilize glucose to support an appropriate response, activated PAG LepRb neurons, which project to and activate parabrachial nucleus (PBN) neurons that control SNS activation and glucose mobilization. Furthermore, activating PAG LepRb neurons increased SNS activity and blood glucose concentrations, while ablating LepRb in PAG neurons augmented glucose mobilization in response to noxious stimuli. Thus, decreased leptin action on PAG LepRb neurons augments the autonomic response to noxious stimuli, ensuring sufficient glucose mobilization during periods of acute demand in the face of diminished energy stores.

  9. Arsenic speciation in arsenic-rich Brazilian soils from gold mining sites under anaerobic incubation

    Science.gov (United States)

    De Mello, J. W. V.; Talbott, J.L.; Scott, J.; Roy, W.R.; Stucki, J.W.

    2007-01-01

    Background. Arsenic speciation in environmental samples is essential for studying toxicity, mobility and bio-transformation of As in aquatic and terrestrial environments. Although the inorganic species As(III) and As(V) have been considered dominant in soils and sediments, organisms are able to metabolize inorganic forms of arsenic into organo-arsenic compounds. Arsenosugars and methylated As compounds can be found in terrestrial organisms, but they generally occur only as minor constituents. We investigated the dynamics of arsenic species under anaerobic conditions in soils surrounding gold mining areas from Minas Gerais State, Brazil to elucidate the arsenic biogeochemical cycle and water contamination mechanisms. Methods. Surface soil samples were collected at those sites, namely Paracatu Formation, Banded Iron Formation and Riacho dos Machados Sequence, and incubated in CaCl2 2.5 mmol L-1 suspensions under anaerobic conditions for 1, 28, 56 and 112 days. After that, suspensions were centrifuged and supernatants analyzed for soluble As species by IC-ICPMS and HPLC-ICPMS. Results. Easily exchangeable As was mainly arsenite, except when reducible manganese was present. Arsenate was mainly responsible for the increase in soluble arsenic due to the reductive dissolution of either iron or manganese in samples from the Paracatu Formation and Riacho dos Machados Sequence. On the other hand, organic species of As dominated in samples from the Banded Iron Formation during anaerobic incubation. Discussion. Results are contrary to the expectation that, in anaerobic environments, As release due to the reductive dissolution of Fe is followed by As(V) reduction to As(III). The occurrence of organo-arsenic species was also found to be significant to the dynamics of soluble arsenic, mainly in soils from the Banded Iron Formation (BIF), under our experimental conditions. Conclusions. In general, As(V) and organic As were the dominant species in solution, which is surprising

  10. Effect of a mobile app intervention on vegetable consumption in overweight adults: a randomized controlled trial.

    Science.gov (United States)

    Mummah, Sarah; Robinson, Thomas N; Mathur, Maya; Farzinkhou, Sarah; Sutton, Stephen; Gardner, Christopher D

    2017-09-15

    Mobile applications (apps) have been heralded as transformative tools to deliver behavioral health interventions at scale, but few have been tested in rigorous randomized controlled trials. We tested the effect of a mobile app to increase vegetable consumption among overweight adults attempting weight loss maintenance. Overweight adults (n=135) aged 18-50 years with BMI=28-40 kg/m 2 near Stanford, CA were recruited from an ongoing 12-month weight loss trial (parent trial) and randomly assigned to either the stand-alone, theory-based Vegethon mobile app (enabling goal setting, self-monitoring, and feedback and using "process motivators" including fun, surprise, choice, control, social comparison, and competition) or a wait-listed control condition. The primary outcome was daily vegetables servings, measured by an adapted Harvard food frequency questionnaire (FFQ) 8 weeks post-randomization. Daily vegetable servings from 24-hour dietary recalls, administered by trained, certified, and blinded interviewers 5 weeks post-randomization, was included as a secondary outcome. All analyses were conducted according to principles of intention-to-treat. Daily vegetable consumption was significantly greater in the intervention versus control condition for both measures (adjusted mean difference: 2.0 servings; 95% CI: 0.1, 3.8, p=0.04 for FFQ; and 1.0 servings; 95% CI: 0.2, 1.9; p=0.02 for 24-hour recalls). Baseline vegetable consumption was a significant moderator of intervention effects (p=0.002) in which effects increased as baseline consumption increased. These results demonstrate the efficacy of a mobile app to increase vegetable consumption among overweight adults. Theory-based mobile interventions may present a low-cost, scalable, and effective approach to improving dietary behaviors and preventing associated chronic diseases. ClinicalTrials.gov NCT01826591. Registered 27 March 2013.

  11. Arsenic speciation results

    Data.gov (United States)

    U.S. Environmental Protection Agency — Linear combination fitting results of synchrotron data to determine arsenic speciation in soil samples. This dataset is associated with the following publication:...

  12. Arsenic Trioxide Injection

    Science.gov (United States)

    ... people who have not been helped by other types of chemotherapy or whose condition has improved but then worsened following treatment with other types of chemotherapy. Arsenic trioxide is in a class of medications ...

  13. Paper on Arsenic

    African Journals Online (AJOL)

    Hiren

    The current study was undertaken to determine the effects of arsenic on ... concentration caused reduction in plant growth along with induction of few antioxidants. ... esculentum, a herbaceous monocot plant, towards reactive oxygen species.

  14. A report on isotope hydrology of groundwater in Bangladesh: implications for characterization and mitigation of arsenic in groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Aggarwal, P K; Froehlich, K [International Atomic Energy Agency, Isotope Hydrology Section, Vienna (Austria); Basu, A R; Poreda, R J [Department of Earth Sciences, University of Rochester Rochester, New York (United States); Kulkarni, K M [Bhabha Atomic Research Centre, Isotope Hydrology Section, Trombay, Mumbai (India); Tarafdar, S A; Ali, Mohamed; Ahmed, Nasir [Bangladesh Atomic Energy Commission, Dhaka (Bangladesh); Hussain, Alamgir; Rahman, Mizanur; Ahmed, Syed Reazuddin [Bangladesh Water Development Board, Dhaka (Bangladesh)

    2000-12-01

    An investigation of the source and dynamics of groundwater in Bangladesh has been conducted with environmental isotope tracers. The primary objective of this study was to provide a scientific basis for developing mitigation strategies by characterizing the mechanism of arsenic mobilization in groundwater and the present and future status of arsenic contamination in deeper aquifers. About 55 shallow and deep groundwater samples ranging in depth from 10 to 335 m were collected and analyzed for their chemical and isotopic compositions. Distinct patterns of isotope compositions are found in shallow and deep groundwaters. Arsenic contamination is found to be present mostly in shallow groundwater to depths of less than 70 m. Groundwater samples from deep wells containing elevated arsenic concentrations are found to contain water mostly from shallow aquifers and do not indicate arsenic contamination of deeper aquifers. However, depth in itself is not a criterion that can be reliably or easily used to find arsenic-free, safe drinking water. Water with high arsenic concentrations sampled from 'deep' wells may not be representative of deep aquifers, and presently uncontaminated water from somewhat deeper wells ({approx}100 m) may not remain so over a long period of time. Increased exploitation of deep groundwater ({approx}300 m) such as in the Barisal area appears to be possible without fear of arsenic contamination from shallow aquifers. However, the potential for groundwater mining is clearly evident and the sustainability of this resource needs to be evaluated. The exponential increase in groundwater exploitation between 1979 and 1999 does not appear to have affected the overall hydrodynamics of shallow and deep aquifers and, by implication, the arsenic mobilization processes. Currently favored mechanisms of arsenic mobilization are found to be inconsistent with isotope data. The most likely process of arsenic mobilization may involve desorption from the sediments as a

  15. A report on isotope hydrology of groundwater in Bangladesh: implications for characterization and mitigation of arsenic in groundwater

    International Nuclear Information System (INIS)

    Aggarwal, P.K.; Froehlich, K.; Basu, A.R.; Poreda, R.J.; Kulkarni, K.M.; Tarafdar, S.A.; Mohamed Ali; Nasir Ahmed; Alamgir Hussain; Mizanur Rahman; Syed Reazuddin Ahmed

    2000-12-01

    An investigation of the source and dynamics of groundwater in Bangladesh has been conducted with environmental isotope tracers. The primary objective of this study was to provide a scientific basis for developing mitigation strategies by characterizing the mechanism of arsenic mobilization in groundwater and the present and future status of arsenic contamination in deeper aquifers. About 55 shallow and deep groundwater samples ranging in depth from 10 to 335 m were collected and analyzed for their chemical and isotopic compositions. Distinct patterns of isotope compositions are found in shallow and deep groundwaters. Arsenic contamination is found to be present mostly in shallow groundwater to depths of less than 70 m. Groundwater samples from deep wells containing elevated arsenic concentrations are found to contain water mostly from shallow aquifers and do not indicate arsenic contamination of deeper aquifers. However, depth in itself is not a criterion that can be reliably or easily used to find arsenic-free, safe drinking water. Water with high arsenic concentrations sampled from 'deep' wells may not be representative of deep aquifers, and presently uncontaminated water from somewhat deeper wells (∼100 m) may not remain so over a long period of time. Increased exploitation of deep groundwater (∼300 m) such as in the Barisal area appears to be possible without fear of arsenic contamination from shallow aquifers. However, the potential for groundwater mining is clearly evident and the sustainability of this resource needs to be evaluated. The exponential increase in groundwater exploitation between 1979 and 1999 does not appear to have affected the overall hydrodynamics of shallow and deep aquifers and, by implication, the arsenic mobilization processes. Currently favored mechanisms of arsenic mobilization are found to be inconsistent with isotope data. The most likely process of arsenic mobilization may involve desorption from the sediments as a result of

  16. MPC-Based Path Following Control of an Omnidirectional Mobile Robot with Consideration of Robot Constraints

    Directory of Open Access Journals (Sweden)

    Kiattisin Kanjanawanishkul

    2015-01-01

    Full Text Available In this paper, the path following problem of an omnidirectional mobile robot (OMR has been studied. Unlike nonholonomic mobile robots, translational and rotational movements of OMRs can be controlled simultaneously and independently. However the constraints of translational and rotational velocities are coupled through the OMR's orientation angle. Therefore, a combination of a virtual-vehicle concept and a model predictive control (MPC strategy is proposed in this work to handle both robot constraints and the path following problem. Our proposed control scheme allows the OMR to follow the reference path successfully and safely, as illustrated in simulation experiments. The forward velocity is close to the desired one and the desired orientation angle is achieved at a given point on the path, while the robot's wheel velocities are maintained within boundaries.

  17. Hierarchical Brokering with Feedback Control Framework in Mobile Device-Centric Clouds

    Directory of Open Access Journals (Sweden)

    Chao-Lieh Chen

    2016-01-01

    Full Text Available We propose a hierarchical brokering architecture (HiBA and Mobile Multicloud Networking (MMCN feedback control framework for mobile device-centric cloud (MDC2 computing. Exploiting the MMCN framework and RESTful web-based interconnection, each tier broker probes resource state of its federation for control and management. Real-time and seamless services were developed. Case studies including intrafederation energy-aware balancing based on fuzzy feedback control and higher tier load balancing are further demonstrated to show how HiBA with MMCN relieves the embedding of algorithms when developing services. Theoretical performance model and real-world experiments both show that an MDC2 based on HiBA features better quality in terms of resource availability and network latency if it federates devices with enough resources distributed in lower tier hierarchy. The proposed HiBA realizes a development platform for MDC2 computing which is a feasible solution to User-Centric Networks (UCNs.

  18. Discrete Globalised Dual Heuristic Dynamic Programming in Control of the Two-Wheeled Mobile Robot

    Directory of Open Access Journals (Sweden)

    Marcin Szuster

    2014-01-01

    Full Text Available Network-based control systems have been emerging technologies in the control of nonlinear systems over the past few years. This paper focuses on the implementation of the approximate dynamic programming algorithm in the network-based tracking control system of the two-wheeled mobile robot, Pioneer 2-DX. The proposed discrete tracking control system consists of the globalised dual heuristic dynamic programming algorithm, the PD controller, the supervisory term, and an additional control signal. The structure of the supervisory term derives from the stability analysis realised using the Lyapunov stability theorem. The globalised dual heuristic dynamic programming algorithm consists of two structures: the actor and the critic, realised in a form of neural networks. The actor generates the suboptimal control law, while the critic evaluates the realised control strategy by approximation of value function from the Bellman’s equation. The presented discrete tracking control system works online, the neural networks’ weights adaptation process is realised in every iteration step, and the neural networks preliminary learning procedure is not required. The performance of the proposed control system was verified by a series of computer simulations and experiments realised using the wheeled mobile robot Pioneer 2-DX.

  19. Tracking Control for Mobile Robots Considering the Dynamics of All Their Subsystems: Experimental Implementation

    Directory of Open Access Journals (Sweden)

    José Rafael García-Sánchez

    2017-01-01

    Full Text Available The trajectory tracking task in a wheeled mobile robot (WMR is solved by proposing a three-level hierarchical controller that considers the mathematical model of the mechanical structure (differential drive WMR, actuators (DC motors, and power stage (DC/DC Buck power converters. The highest hierarchical level is a kinematic control for the mechanical structure; the medium level includes two controllers based on differential flatness for the actuators; and the lowest hierarchical level consists of two average controllers also based on differential flatness for the power stage. In order to experimentally validate the feasibility of the proposed control scheme, the hierarchical controller is implemented via a Σ–Δ-modulator in a differential drive WMR prototype that we have built. Such an implementation is achieved by using MATLAB-Simulink and the real-time interface ControlDesk together with a DS1104 board. The experimental results show the effectiveness and robustness of the proposed control scheme.

  20. End-Point Contact Force Control with Quantitative Feedback Theory for Mobile Robots

    Directory of Open Access Journals (Sweden)

    Shuhuan Wen

    2012-12-01

    Full Text Available Robot force control is an important issue for intelligent mobile robotics. The end-point stiffness of a robot is a key and open problem in the research community. The control strategies are mostly dependent on both the specifications of the task and the environment of the robot. Due to the limited stiffness of the end-effector, we may adopt inherent torque to feedback the oscillations of the controlled force. This paper proposes an effective control strategy which contains a controller using quantitative feedback theory. The nested loop controllers take into account the physical limitation of the system's inner variables and harmful interference. The biggest advantage of the method is its simplicity in both the design process and the implementation of the control algorithm in engineering practice. Taking the one-link manipulator as an example, numerical experiments are carried out to verify the proposed control method. The results show the satisfactory performance.

  1. Studies on Arsenic Release and its Mitigation from Tailings Dam ...

    African Journals Online (AJOL)

    Studies on Arsenic Release and its Mitigation from Tailings Dam Using Nanomagnetite Particles. ... Ghana Mining Journal ... Abstract. Knowledge of the geochemistry of As in tailings material after beneficiation of gold-bearing sulphidic ores is necessary to comprehend the nature, stability and mobilization of As into the ...

  2. Mobile phones improve antenatal care attendance in Zanzibar: a cluster randomized controlled trial

    Science.gov (United States)

    2014-01-01

    Background Applying mobile phones in healthcare is increasingly prioritized to strengthen healthcare systems. Antenatal care has the potential to reduce maternal morbidity and improve newborns’ survival but this benefit may not be realized in sub-Saharan Africa where the attendance and quality of care is declining. We evaluated the association between a mobile phone intervention and antenatal care in a resource-limited setting. We aimed to assess antenatal care in a comprehensive way taking into consideration utilisation of antenatal care as well as content and timing of interventions during pregnancy. Methods This study was an open label pragmatic cluster-randomised controlled trial with primary healthcare facilities in Zanzibar as the unit of randomisation. 2550 pregnant women (1311 interventions and 1239 controls) who attended antenatal care at selected primary healthcare facilities were included at their first antenatal care visit and followed until 42 days after delivery. 24 primary health care facilities in six districts were randomized to either mobile phone intervention or standard care. The intervention consisted of a mobile phone text-message and voucher component. Primary outcome measure was four or more antenatal care visits during pregnancy. Secondary outcome measures were tetanus vaccination, preventive treatment for malaria, gestational age at last antenatal care visit, and antepartum referral. Results The mobile phone intervention was associated with an increase in antenatal care attendance. In the intervention group 44% of the women received four or more antenatal care visits versus 31% in the control group (OR, 2.39; 95% CI, 1.03-5.55). There was a trend towards improved timing and quality of antenatal care services across all secondary outcome measures although not statistically significant. Conclusions The wired mothers’ mobile phone intervention significantly increased the proportion of women receiving the recommended four antenatal care

  3. Limited mobility of target pests crucially lowers controllability when sterile insect releases are spatiotemporally biased.

    Science.gov (United States)

    Ikegawa, Yusuke; Himuro, Chihiro

    2017-05-21

    The sterile insect technique (SIT) is a genetic pest control method wherein mass-reared sterile insects are periodically released into the wild, thereby impeding the successful reproduction of fertile pests. In Okinawa Prefecture, Japan, the SIT has been implemented to eradicate the West Indian sweet potato weevil Euscepes postfasciatus (Fairmaire), which is a flightless agricultural pest of sweet potatoes. It is known that E. postfasciatus is much less mobile than other insects to which the SIT has been applied. However, previous theoretical studies have rarely examined effects of low mobility of target pests and variation in the spatiotemporal evenness of sterile insect releases. To theoretically examine the effects of spatiotemporal evenness on the regional eradication of less mobile pests, we constructed a simple two-patch population model comprised of a pest and sterile insect moving between two habitats, and numerically simulated different release strategies (varying the number of released sterile insects and release intervals). We found that spatially biased releases allowed the pest to spatially escape from the sterile insect, and thus intensively lowered its controllability. However, we showed that the temporally counterbalancing spatially biased releases by swapping the number of released insects in the two habitats at every release (called temporal balancing) could greatly mitigate this negative effect and promote the controllability. We also showed that the negative effect of spatiotemporally biased releases was a result of the limited mobility of the target insect. Although directed dispersal of the insects in response to habitats of differing quality could lower the controllability in the more productive habitat, the temporal balancing could promote and eventually maximize the controllability as released insects increased. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Obstacle negotiation control for a mobile robot suspended on overhead ground wires by optoelectronic sensors

    Science.gov (United States)

    Zheng, Li; Yi, Ruan

    2009-11-01

    Power line inspection and maintenance already benefit from developments in mobile robotics. This paper presents mobile robots capable of crossing obstacles on overhead ground wires. A teleoperated robot realizes inspection and maintenance tasks on power transmission line equipment. The inspection robot is driven by 11 motor with two arms, two wheels and two claws. The inspection robot is designed to realize the function of observation, grasp, walk, rolling, turn, rise, and decline. This paper is oriented toward 100% reliable obstacle detection and identification, and sensor fusion to increase the autonomy level. An embedded computer based on PC/104 bus is chosen as the core of control system. Visible light camera and thermal infrared Camera are both installed in a programmable pan-and-tilt camera (PPTC) unit. High-quality visual feedback rapidly becomes crucial for human-in-the-loop control and effective teleoperation. The communication system between the robot and the ground station is based on Mesh wireless networks by 700 MHz bands. An expert system programmed with Visual C++ is developed to implement the automatic control. Optoelectronic laser sensors and laser range scanner were installed in robot for obstacle-navigation control to grasp the overhead ground wires. A novel prototype with careful considerations on mobility was designed to inspect the 500KV power transmission lines. Results of experiments demonstrate that the robot can be applied to execute the navigation and inspection tasks.

  5. Mobile diabetes intervention study: testing a personalized treatment/behavioral communication intervention for blood glucose control.

    Science.gov (United States)

    Quinn, Charlene C; Gruber-Baldini, Ann L; Shardell, Michelle; Weed, Kelly; Clough, Suzanne S; Peeples, Malinda; Terrin, Michael; Bronich-Hall, Lauren; Barr, Erik; Lender, Dan

    2009-07-01

    National data find glycemic control is within target (A1ccommunication system, using mobile phones and patient/physician portals to allow patient-specific treatment and communication. All physicians receive American Diabetes Association (ADA) Guidelines for diabetes care. Patients with poor diabetes control (A1c> or =7.5%) at baseline (n=260) are enrolled in study groups based on PCP randomization. All study patients receive blood glucose (BG) meters and a year's supply of testing materials. Patients in three treatment groups select one of two mobile phone models, receive one-year unlimited mobile phone data and service plan, register on the web-based individual patient portal and receive study treatment phone software based on study assignment. Control group patients receive usual care from their PCP. The primary outcome is mean change in A1c over a 12-month intervention period. Traditional methods of disease management have not achieved adequate control for BG and other conditions important to persons with diabetes. Tools to improve communication between patients and PCPs may improve patient outcomes and be satisfactory to patients and physicians. This RCT is ongoing.

  6. Arsenic (Environmental Health Student Portal)

    Science.gov (United States)

    ... Water Waterborne Diseases & Illnesses Water Cycle Water Treatment Videos Games Experiments For Teachers Home Chemicals Arsenic Print this ... human activities, such as mining, farming, and other industries. This can be dangerous, because arsenic is poisonous ...

  7. Prediction based active ramp metering control strategy with mobility and safety assessment

    Science.gov (United States)

    Fang, Jie; Tu, Lili

    2018-04-01

    Ramp metering is one of the most direct and efficient motorway traffic flow management measures so as to improve traffic conditions. However, owing to short of traffic conditions prediction, in earlier studies, the impact on traffic flow dynamics of the applied RM control was not quantitatively evaluated. In this study, a RM control algorithm adopting Model Predictive Control (MPC) framework to predict and assess future traffic conditions, which taking both the current traffic conditions and the RM-controlled future traffic states into consideration, was presented. The designed RM control algorithm targets at optimizing the network mobility and safety performance. The designed algorithm is evaluated in a field-data-based simulation. Through comparing the presented algorithm controlled scenario with the uncontrolled scenario, it was proved that the proposed RM control algorithm can effectively relieve the congestion of traffic network with no significant compromises in safety aspect.

  8. Motion Control Design for an Omnidirectional Mobile Robot Subject to Velocity Constraints

    Directory of Open Access Journals (Sweden)

    Ollin Peñaloza-Mejía

    2015-01-01

    Full Text Available A solution to achieve global asymptotic tracking with bounded velocities in an omnidirectional mobile robot is proposed in this paper. It is motivated by the need of having a useful in-practice motion control scheme, which takes into account the physical limits of the velocities. To this end, a passive nonlinear controller is designed and combined with a tracking controller in a negative feedback connection structure. By using Lyapunov theory and passivity tools, global asymptotic tracking with desired bounded velocities is proved. Simulations and experimental results are provided to show the effectiveness of the proposal.

  9. New Control Paradigms for Resources Saving: An Approach for Mobile Robots Navigation

    Directory of Open Access Journals (Sweden)

    Rafael Socas

    2018-01-01

    Full Text Available In this work, an event-based control scheme is presented. The proposed system has been developed to solve control problems appearing in the field of Networked Control Systems (NCS. Several models and methodologies have been proposed to measure different resources consumptions. The use of bandwidth, computational load and energy resources have been investigated. This analysis shows how the parameters of the system impacts on the resources efficiency. Moreover, the proposed system has been compared with its equivalent discrete-time solution. In the experiments, an application of NCS for mobile robots navigation has been set up and its resource usage efficiency has been analysed.

  10. New Control Paradigms for Resources Saving: An Approach for Mobile Robots Navigation.

    Science.gov (United States)

    Socas, Rafael; Dormido, Raquel; Dormido, Sebastián

    2018-01-18

    In this work, an event-based control scheme is presented. The proposed system has been developed to solve control problems appearing in the field of Networked Control Systems (NCS). Several models and methodologies have been proposed to measure different resources consumptions. The use of bandwidth, computational load and energy resources have been investigated. This analysis shows how the parameters of the system impacts on the resources efficiency. Moreover, the proposed system has been compared with its equivalent discrete-time solution. In the experiments, an application of NCS for mobile robots navigation has been set up and its resource usage efficiency has been analysed.

  11. Behavior coordination of mobile robotics using supervisory control of fuzzy discrete event systems.

    Science.gov (United States)

    Jayasiri, Awantha; Mann, George K I; Gosine, Raymond G

    2011-10-01

    In order to incorporate the uncertainty and impreciseness present in real-world event-driven asynchronous systems, fuzzy discrete event systems (DESs) (FDESs) have been proposed as an extension to crisp DESs. In this paper, first, we propose an extension to the supervisory control theory of FDES by redefining fuzzy controllable and uncontrollable events. The proposed supervisor is capable of enabling feasible uncontrollable and controllable events with different possibilities. Then, the extended supervisory control framework of FDES is employed to model and control several navigational tasks of a mobile robot using the behavior-based approach. The robot has limited sensory capabilities, and the navigations have been performed in several unmodeled environments. The reactive and deliberative behaviors of the mobile robotic system are weighted through fuzzy uncontrollable and controllable events, respectively. By employing the proposed supervisory controller, a command-fusion-type behavior coordination is achieved. The observability of fuzzy events is incorporated to represent the sensory imprecision. As a systematic analysis of the system, a fuzzy-state-based controllability measure is introduced. The approach is implemented in both simulation and real time. A performance evaluation is performed to quantitatively estimate the validity of the proposed approach over its counterparts.

  12. Role of Dissolved Organic Matter and Geochemical Controls on Arsenic Cycling from Sediments to Groundwater along the Meghna River, Bangladesh: Tracking possible links to permeable natural reactive barrier

    Science.gov (United States)

    Datta, S.; Berube, M.; Knappett, P.; Kulkarni, H. V.; Vega, M.; Jewell, K.; Myers, K.

    2017-12-01

    Elevated levels of dissolved arsenic (As), iron (Fe) and manganese (Mn) are seen in the shallow groundwaters of southeast Bangladesh on the Ganges Brahmaputra Meghna River delta. This study takes a multi disciplinary approach to understand the extent of the natural reactive barrier (NRB) along the Meghna River and evaluate the role of the NRB in As sequestration and release in groundwater aquifers. Shallow sediment cores, and groundwater and river water samples were collected from the east and west banks of the Meghna. Groundwater and river water samples were tested for FeT, MnT, and AsT concentrations. Fluorescence spectroscopic characterization of groundwater dissolved organic matter (DOM) provided insight into the hydro geochemical reactions active in the groundwater and the hyporheic zones. Eight sediment cores of 1.5 m depth were collected 10 m away from the edge of the river. Vertical solid phase concentration profiles of Fe, Mn and As were measured via 1.2 M HCl digestion which revealed solid phase As accumulation along the riverbanks up to concentrations of 1500 mg/kg As. Microbial interactions with DOM prompts the reduction of Fe3+ to Fe2+, causing As to mobilize into groundwater and humic-like DOM present in the groundwater may catalyze this process. The extent to which microbially mediated release of As occurs is limited by labile dissolved organic carbon (DOC) availability. Aqueous geochemical results showed the highest dissolved As concentrations in shallow wells (groundwater was found to contain microbial and terrestrial derived DOC, and decomposed, humified and aromatic DOM. Deeper aquifers had a significantly larger microbial OM signature than the shallower aquifers and was less aromatic, decomposed and humified. The results from this study illustrate the potential for humic substances to contribute to As cycling and quantify the extent of As accumulation in the sediments and groundwater along a 1 km stretch of the Meghna. These findings contribute

  13. Ultramafic-derived arsenic in a fractured bedrock aquifer

    International Nuclear Information System (INIS)

    Ryan, Peter C.; Kim, Jonathan; Wall, Andrew J.; Moen, Jonathan C.; Corenthal, Lilly G.; Chow, Daniel R.; Sullivan, Colleen M.; Bright, Kevin S.

    2011-01-01

    Highlights: → Arsenic is elevated in groundwater from a fractured bedrock aquifer system in northern Vermont, USA. → The arsenic source is serpentinized ultramafic rock. → Antigorite, magnetite (MgCO 3 ) and magnetite (Fe 3 O 4 ) appear to be the main mineralogical hosts of arsenic in the ultramafic rock. → Arsenic appears to be introduced to the ultramafic rock when As-bearing fluids are driven out of sediments during subduction. → The occurrence of serpentinized ultramafic rocks in many orogenic belts suggests that similar arsenic anomalies may occur in geologically-similar terranes globally. - Abstract: In the fractured bedrock aquifer of northern Vermont, USA, As concentrations in groundwater range from 3 ) with lesser amounts in magnetite (Fe 3 O 4 ). Hydrochemistry of monitoring wells drilled into fractured ultramafic rock in a groundwater recharge area with no anthropogenic As source reveals above background As (2-9 μg/L) and an Mg-HCO 3 hydrochemical signature that reflects dissolution of antigorite and magnesite, confirming that As in groundwater can be derived from ultramafic rock dissolution. Arsenic mobility in groundwater affected by ultramafic rock dissolution may be enhanced by alkaline pH values and relatively high HCO 3 - concentrations.

  14. Acute and chronic arsenic toxicity

    OpenAIRE

    Ratnaike, R

    2003-01-01

    Arsenic toxicity is a global health problem affecting many millions of people. Contamination is caused by arsenic from natural geological sources leaching into aquifers, contaminating drinking water and may also occur from mining and other industrial processes. Arsenic is present as a contaminant in many traditional remedies. Arsenic trioxide is now used to treat acute promyelocytic leukaemia. Absorption occurs predominantly from ingestion from the small intestine, though minimal absorption o...

  15. Mobility of Cs137 and Sr90 in organic soils and its control

    International Nuclear Information System (INIS)

    Rovdan, E.

    2002-01-01

    In the management of the radionuclide contaminated areas and application of a countermeasure strategy for reduction of both the external and internal doses to the population it is extremely important to know the environmental mechanisms governing the behaviour of radionuclides in soil ecosystems. The purpose of work is to investigate by means of laboratory, field experiments and mathematical modelling the mechanisms and dynamics of radionuclide transfer in the organic soil to propose measures for control their mobility. The Chernobyl radionuclides behaviour was studied for ameliorated peat-mire soil (peat deposit Pogonyanskoye, 21 km off the ChNPP). To control the mobility of radionuclides in soils the characteristics of the migration and sorption of Cs 137 and Sr 90 in sedge peat, quartz sand, bentonite, kaolin, sapropel as well as the electrolytes impact upon the radionuclide behaviour have been experimentally investigated

  16. Optimal Design for PID Controller Based on DE Algorithm in Omnidirectional Mobile Robot

    Directory of Open Access Journals (Sweden)

    Wu Peizhang

    2017-01-01

    Full Text Available This paper introduces a omnidirectional mobile robot based on Mecanum wheel, which is used for conveying heavy load in a small space of the automatic warehousing logistics center. Then analyzes and establishes the omnidirectional chassis inverse and forward kinematic model. In order to improve the performance of motion, the paper proposes the optimal PID controller based on differential evolution algorithm. Finally, through MATLAB simulation, the results show that the kinematic model of mobile robot chassis is correct, further more the controller optimized by the DE algorithm working better than the traditional Z-N PID tuned. So the optimal scheme is reasonable and feasible, which has a value for engineering applications.

  17. Web-Based and Mobile Stress Management Intervention for Employees: A Randomized Controlled Trial

    OpenAIRE

    Heber, Elena; Lehr, Dirk; Ebert, David Daniel; Berking, Matthias; Riper, Heleen

    2016-01-01

    Background: Work-related stress is highly prevalent among employees and is associated with adverse mental health consequences. Web-based interventions offer the opportunity to deliver effective solutions on a large scale; however, the evidence is limited and the results conflicting. Objective: This randomized controlled trial evaluated the efficacy of guided Web-and mobile-based stress management training for employees. Methods: A total of 264 employees with elevated symptoms of stress (Perce...

  18. Investigation of humidity control via membrane separation for advanced Extravehicular Mobility Unit (EMU) application

    Science.gov (United States)

    Newbold, D. D.; Ray, R. J.; Pledger, W. A.; Mccray, S. B.; Brown, M. F.

    1989-01-01

    This paper describes the development of a membrane-based process for dehumidifying the Extravehicular Mobility Unit (EMU). The membrane process promises to be smaller, lighter, and more energy efficient than the other technologies for dehumidification. The dehydration membranes were tested for 90 days at conditions expected to be present in the EMU. The results of these tests indicate that membrane-based technology can effectively control humidity in the EMU.

  19. ARSENIC REMOVAL FROM DRINKING WATER BY ADSORPTIVE MEDIA. U.S. EPA DEMONSTRATION PROJECT AT SPRINGFIELD, OH. PROJECT SUMMARY

    Science.gov (United States)

    This document is a eight page summary of the final report on arsenic demonstration project at the Chateau Estates Mobile Home Park in Springfield, OH. The objectives of the project are to evaluate the effectiveness of AdEdge Technologies’ AD-33 media in removing arsenic to meet t...

  20. Effects of gamma-sterilization on DOC, uranium and arsenic remobilization from organic and microbial rich stream sediments

    International Nuclear Information System (INIS)

    Schaller, Joerg; Weiske, Arndt; Dudel, E. Gert

    2011-01-01

    Organic-rich sediments are known to be effective accumulators for uranium and arsenic. Much is known about the capacity for metal or metalloid fixation by microbes and organic compounds as well as inorganic sediment particles. Experiments investigating the effect of microbes on the process of metal fixation in sediments require sterilized sediments as control treatment which is often realized by gamma-sterilization. Only few studies show that gamma-sterilization has an effect on the remobilization of metal and metalloids and on their physico-chemical properties. These studies deal with sediments with negligible organic content whereas almost nothing is known about organic-rich sediments including a probably high microbial activity. In view of this, we investigated the effect of gamma-sterilization of organic-rich sediments on uranium and arsenic fixation and release. After ten days within an exposure experiment we found a significant higher remobilization of uranium and arsenic in sterile compared to unsterile treatments. In line with these findings the content of dissolved organic carbon (DOC), manganese, and iron increased to even significantly higher concentration in the sterile compared to unsterile treatment. Gamma-sterilization seems to change the physico-chemical properties of organic-rich sediments. Microbial activity is effectively eliminated. From increased DOC concentrations in overlaying water it is concluded that microbes are eventually killed with leaching of cellular compounds in the overlaying water. This decreases the adsorption capacity of the sediment and leads to enhanced uranium and arsenic remobilization. - Research highlight s : →Remobilization of uranium and arsenic is higher in gamma-sterile treatments. →DOC mobilization is also higher in sterilized treatment. →Adsorption capacity in sediments is reduced by release of DOC.

  1. A Universal Communication Framework and Navigation Control Software for Mobile Prototyping Platforms

    Directory of Open Access Journals (Sweden)

    Andreas Mitschele-Thiel

    2010-09-01

    Full Text Available In our contribution we would like to describe two new aspects of our low-cost mobile prototyping platform concept: a new hardware communication framework as well as new software features for navigation and control of our mobile platform. The paper is an extension of the ideas proposed in REV2009 [1] and is based on the therein used hardware platform and the monitoring and management software. This platform is based on the Quadrocopter concept – autonomous flying helicopter-style robots – and includes additional off-the-shelf parts. This leads to a universal mobile prototyping platform for communication tasks providing both mobile phone and WiFi access. However, the platform can provide these functions far more quickly than a technician on the ground might be able to. We will show that with our concept we can easily adapt the platform to the individual needs of the user, which leads to a very flexible and semi-autonomous system.

  2. Positioning and tracking control system analysis for mobile free space optical network

    Science.gov (United States)

    Li, Yushan; Refai, Hazem; Sluss, , James J., Jr.; Verma, Pramode; LoPresti, Peter

    2005-08-01

    Free Space Optical (FSO) communication has evolved to be applied to the mobile network, because it can provide up to 2.5Gbps or higher data rate wireless communication. One of the key challenges with FSO systems is to maintain the Line of Sight (LOS) between transmitter and receiver. In this paper, the feasibility and performance of applying the FSO technology to the mobile network is explored, and the design plan of the attitude positioning and tracking control system of the FSO transceiver is investigated. First, the system architecture is introduced, the requirements for the control system are analyzed, the involved reference frames and frame transformation are presented. Second, the control system bandwidth is used to evaluate the system performance in controlling a positioning system consisting of a gimbal and a steering mirror, some definitions to describe the positioning accuracy and tracking capacity are given. The attitude control of a FSO transceiver is split into 2 similar channels: pitch and yaw. Using an equivalent linear control system model, the simulations are carried out, with and without the presence of uncertainties that includes GPS data errors and sensor measurement errors. Finally, based on the simulation results in the pitch channel, the quantitative evaluation on the performance of the control system is given, including positioning accuracy, tracking capability and uncertainty tolerance.

  3. Effect of Solution Properties on Arsenic Adsorption by Drinking Water Treatment Residuals

    Science.gov (United States)

    Nagar, R.; Sarkar, D.; Datta, R.; Sharma, S.

    2005-05-01

    Arsenic (As) is a ubiquitous element in the environment. Higher levels of As in soils may result from various anthropogenic sources such as use of arsenical pesticides, fertilizers, wood preservatives, smelter wastes, and coal combustion. This is of great environmental and human health concern due to the high toxicity and proven carcinogenicity of several arsenical species. Thus there is a need for developing cost effective technologies capable of lowering bioavailable As concentrations in soils to environmentally acceptable levels. In-situ immobilization of metals using inexpensive amendments such as minerals (apatite, zeolite, or clay minerals) or waste by-products (steel shot, beringite, and iron-rich biosolids) to reduce bioavailability is an inexpensive alternative to the more expensive ex-situ remediation methods. One such emerging in-situ technique is the application of drinking water treatment residuals (WTRs). WTRs can be classified as a byproduct of drinking water treatment plants and are generally composed of amorphous Fe/Al oxides, activated C and cationic polymers. WTRs possess amorphous structure and generally have high positive charge. Because As is chemically similar to phosphorus, the oxyanions As (V) and As (III) may have the potential of being retained by the WTRs. Thus, it is hypothesized that WTRs retain As irreversibly, thereby reducing As biavailability. As mobility of arsenic is controlled by adsorption reactions, knowledge of adsorption of As by WTRs is of primary relevance. Although the overall rate of adsorption is dependent on numerous factors, review of the literature indicates that competing ions in solution play an important role in the overall retention of As; however, little work has been conducted to identify which ions provide the most competition. As arsenic adsorption appears to be influenced by the variable pH-dependent charges developed on the soil particle surfaces, the effect of pH is also of critical importance. Hence, the

  4. Diverse arsenic- and iron-cycling microbial communities in arsenic-contaminated aquifers used for drinking water in Bangladesh.

    Science.gov (United States)

    Hassan, Zahid; Sultana, Munawar; van Breukelen, Boris M; Khan, Sirajul I; Röling, Wilfred F M

    2015-04-01

    Subsurface removal of arsenic by injection with oxygenated groundwater has been proposed as a viable technology for obtaining 'safe' drinking water in Bangladesh. While the oxidation of ferrous iron to solid ferric iron minerals, to which arsenic adsorbs, is assumed to be driven by abiotic reactions, metal-cycling microorganisms may potentially affect arsenic removal. A cultivation-independent survey covering 24 drinking water wells in several geographical regions in Bangladesh was conducted to obtain information on microbial community structure and diversity in general, and on specific functional groups capable of the oxidation or reduction of arsenic or iron. Each functional group, targeted by either group-specific 16S rRNA or functional gene amplification, occurred in at least 79% of investigated samples. Putative arsenate reducers and iron-oxidizing Gallionellaceae were present at low diversity, while more variation in potentially arsenite-oxidizing microorganisms and iron-reducing Desulfuromonadales was revealed within and between samples. Relations between community composition on the one hand and hydrochemistry on the other hand were in general not evident, apart from an impact of salinity on iron-cycling microorganisms. Our data suggest widespread potential for a positive contribution of arsenite and iron oxidizers to arsenic removal upon injection with oxygenated water, but also indicate a potential risk for arsenic re-mobilization by anaerobic arsenate and iron reducers once injection is halted. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  5. Evaluating Leaf and Canopy Reflectance of Stressed Rice Plants to Monitor Arsenic Contamination

    Directory of Open Access Journals (Sweden)

    Varaprasad Bandaru

    2016-06-01

    Full Text Available Arsenic contamination is a serious problem in rice cultivated soils of many developing countries. Hence, it is critical to monitor and control arsenic uptake in rice plants to avoid adverse effects on human health. This study evaluated the feasibility of using reflectance spectroscopy to monitor arsenic in rice plants. Four arsenic levels were induced in hydroponically grown rice plants with application of 0, 5, 10 and 20 µmol·L−1 sodium arsenate. Reflectance spectra of upper fully expanded leaves were acquired over visible and infrared (NIR wavelengths. Additionally, canopy reflectance for the four arsenic levels was simulated using SAIL (Scattering by Arbitrarily Inclined Leaves model for various soil moisture conditions and leaf area indices (LAI. Further, sensitivity of various vegetative indices (VIs to arsenic levels was assessed. Results suggest that plants accumulate high arsenic amounts causing plant stress and changes in reflectance characteristics. All leaf spectra based VIs related strongly with arsenic with coefficient of determination (r2 greater than 0.6 while at canopy scale, background reflectance and LAI confounded with spectral signals of arsenic affecting the VIs’ performance. Among studied VIs, combined index, transformed chlorophyll absorption reflectance index (TCARI/optimized soil adjusted vegetation index (OSAVI exhibited higher sensitivity to arsenic levels and better resistance to soil backgrounds and LAI followed by red edge based VIs (modified chlorophyll absorption reflectance index (MCARI and TCARI suggesting that these VIs could prove to be valuable aids for monitoring arsenic in rice fields.

  6. Reaction Mechanism and Distribution Behavior of Arsenic in the Bottom Blown Copper Smelting Process

    Directory of Open Access Journals (Sweden)

    Qinmeng Wang

    2017-08-01

    Full Text Available The control of arsenic, a toxic and carcinogenic element, is an important issue for all copper smelters. In this work, the reaction mechanism and distribution behavior of arsenic in the bottom blown copper smelting process (SKS process were investigated and compared to the flash smelting process. There are obvious differences of arsenic distribution in the SKS process and flash process, resulting from the differences of oxygen potentials, volatilizations, smelting temperatures, reaction intensities, and mass transfer processes. Under stable production conditions, the distributions of arsenic among matte, slag, and gas phases are 6%, 12%, and 82%, respectively. Less arsenic is reported in the gas phase with the flash process than with the SKS process. The main arsenic species in gas phase are AsS (g, AsO (g, and As2 (g. Arsenic exists in the slag predominantly as As2O3 (l, and in matte as As (l. High matte grade is harmful to the elimination of arsenic to gas. The changing of Fe/SiO2 has slight effects on the distributions of arsenic. In order to enhance the removal of arsenic from the SKS smelting system to the gas phase, low oxygen concentration, low ratios of oxygen/ore, and low matte grade should be chosen. In the SKS smelting process, no dust is recycled, and almost all dust is collected and further treated to eliminate arsenic and recover valuable metals by other process streams.

  7. Associations between toenail arsenic concentration and dietary factors in a New Hampshire population

    Directory of Open Access Journals (Sweden)

    Gruber Joann F

    2012-06-01

    Full Text Available Abstract Background Dietary factors such as folate, vitamin B12, protein, and methionine are important for the excretion of arsenic via one-carbon metabolism in undernourished populations exposed to high levels of arsenic via drinking water. However, the effects of dietary factors on toenail arsenic concentrations in well-nourished populations exposed to relatively low levels of water arsenic are unknown. Methods As part of a population-based case–control study of skin and bladder cancer from the USA, we evaluated relationships between consumption of dietary factors and arsenic concentrations in toenail clippings. Consumption of each dietary factor was determined from a validated food frequency questionnaire. We used general linear models to examine the associations between toenail arsenic and each dietary factor, taking into account potentially confounding effects. Results As expected, we found an inverse association between ln-transformed toenail arsenic and consumption of vitamin B12 (excluding supplements and animal protein. Unexpectedly, there were also inverse associations with numerous dietary lipids (e.g., total fat, total animal fat, total vegetable fat, total monounsaturated fat, total polyunsaturated fat, and total saturated fat. Finally, increased toenail arsenic concentrations were associated with increased consumption of long chain n-3 fatty acids. Conclusion In a relatively well-nourished population exposed to relatively low levels of arsenic via water, consumption of certain dietary lipids may decrease toenail arsenic concentration, while long chain n-3 fatty acids may increase toenail arsenic concentration, possibly due to their association with arsenolipids in fish tissue.

  8. Congestion Control and Traffic Scheduling for Collaborative Crowdsourcing in SDN Enabled Mobile Wireless Networks

    Directory of Open Access Journals (Sweden)

    Dawei Shen

    2018-01-01

    Full Text Available Currently, a number of crowdsourcing-based mobile applications have been implemented in mobile networks and Internet of Things (IoT, targeted at real-time services and recommendation. The frequent information exchanges and data transmissions in collaborative crowdsourcing are heavily injected into the current communication networks, which poses great challenges for Mobile Wireless Networks (MWN. This paper focuses on the traffic scheduling and load balancing problem in software-defined MWN and designs a hybrid routing forwarding scheme as well as a congestion control algorithm to achieve the feasible solution. The traffic scheduling algorithm first sorts the tasks in an ascending order depending on the amount of tasks and then solves it using a greedy scheme. In the proposed congestion control scheme, the traffic assignment is first transformed into a multiknapsack problem, and then the Artificial Fish Swarm Algorithm (AFSA is utilized to solve this problem. Numerical results on practical network topology reveal that, compared with the traditional schemes, the proposed congestion control and traffic scheduling schemes can achieve load balancing, reduce the probability of network congestion, and improve the network throughput.

  9. Unraveling the mechanism of neuroprotection of curcumin in arsenic induced cholinergic dysfunctions in rats

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Pranay [CSIR-Indian Institute of Toxicology Research, Post Box 80, MG Marg, Lucknow 226 001 (India); Yadav, Rajesh S. [CSIR-Indian Institute of Toxicology Research, Post Box 80, MG Marg, Lucknow 226 001 (India); Department of Crimnology and Forensic Science, Harisingh Gour University, Sagar 470 003 (India); Chandravanshi, Lalit P.; Shukla, Rajendra K.; Dhuriya, Yogesh K.; Chauhan, Lalit K.S. [CSIR-Indian Institute of Toxicology Research, Post Box 80, MG Marg, Lucknow 226 001 (India); Dwivedi, Hari N. [Babu Banarasi Das University, BBD City, Faizabad Road, Lucknow 227 015 (India); Pant, Aditiya B. [CSIR-Indian Institute of Toxicology Research, Post Box 80, MG Marg, Lucknow 226 001 (India); Khanna, Vinay K., E-mail: vkkhanna1@gmail.com [CSIR-Indian Institute of Toxicology Research, Post Box 80, MG Marg, Lucknow 226 001 (India)

    2014-09-15

    Earlier, we found that arsenic induced cholinergic deficits in rat brain could be protected by curcumin. In continuation to this, the present study is focused to unravel the molecular mechanisms associated with the protective efficacy of curcumin in arsenic induced cholinergic deficits. Exposure to arsenic (20 mg/kg body weight, p.o) for 28 days in rats resulted to decrease the expression of CHRM2 receptor gene associated with mitochondrial dysfunctions as evident by decrease in the mitochondrial membrane potential, activity of mitochondrial complexes and enhanced apoptosis both in the frontal cortex and hippocampus in comparison to controls. The ultrastructural images of arsenic exposed rats, assessed by transmission electron microscope, exhibited loss of myelin sheath and distorted cristae in the mitochondria both in the frontal cortex and hippocampus as compared to controls. Simultaneous treatment with arsenic (20 mg/kg body weight, p.o) and curcumin (100 mg/kg body weight, p.o) for 28 days in rats was found to protect arsenic induced changes in the mitochondrial membrane potential and activity of mitochondrial complexes both in frontal cortex and hippocampus. Alterations in the expression of pro- and anti-apoptotic proteins and ultrastructural damage in the frontal cortex and hippocampus following arsenic exposure were also protected in rats simultaneously treated with arsenic and curcumin. The data of the present study reveal that curcumin could protect arsenic induced cholinergic deficits by modulating the expression of pro- and anti-apoptotic proteins in the brain. More interestingly, arsenic induced functional and ultrastructural changes in the brain mitochondria were also protected by curcumin. - Highlights: • Neuroprotective mechanism of curcumin in arsenic induced cholinergic deficits studied • Curcumin protected arsenic induced enhanced expression of stress markers in rat brain • Arsenic compromised mitochondrial electron transport chain protected

  10. Unraveling the mechanism of neuroprotection of curcumin in arsenic induced cholinergic dysfunctions in rats

    International Nuclear Information System (INIS)

    Srivastava, Pranay; Yadav, Rajesh S.; Chandravanshi, Lalit P.; Shukla, Rajendra K.; Dhuriya, Yogesh K.; Chauhan, Lalit K.S.; Dwivedi, Hari N.; Pant, Aditiya B.; Khanna, Vinay K.

    2014-01-01

    Earlier, we found that arsenic induced cholinergic deficits in rat brain could be protected by curcumin. In continuation to this, the present study is focused to unravel the molecular mechanisms associated with the protective efficacy of curcumin in arsenic induced cholinergic deficits. Exposure to arsenic (20 mg/kg body weight, p.o) for 28 days in rats resulted to decrease the expression of CHRM2 receptor gene associated with mitochondrial dysfunctions as evident by decrease in the mitochondrial membrane potential, activity of mitochondrial complexes and enhanced apoptosis both in the frontal cortex and hippocampus in comparison to controls. The ultrastructural images of arsenic exposed rats, assessed by transmission electron microscope, exhibited loss of myelin sheath and distorted cristae in the mitochondria both in the frontal cortex and hippocampus as compared to controls. Simultaneous treatment with arsenic (20 mg/kg body weight, p.o) and curcumin (100 mg/kg body weight, p.o) for 28 days in rats was found to protect arsenic induced changes in the mitochondrial membrane potential and activity of mitochondrial complexes both in frontal cortex and hippocampus. Alterations in the expression of pro- and anti-apoptotic proteins and ultrastructural damage in the frontal cortex and hippocampus following arsenic exposure were also protected in rats simultaneously treated with arsenic and curcumin. The data of the present study reveal that curcumin could protect arsenic induced cholinergic deficits by modulating the expression of pro- and anti-apoptotic proteins in the brain. More interestingly, arsenic induced functional and ultrastructural changes in the brain mitochondria were also protected by curcumin. - Highlights: • Neuroprotective mechanism of curcumin in arsenic induced cholinergic deficits studied • Curcumin protected arsenic induced enhanced expression of stress markers in rat brain • Arsenic compromised mitochondrial electron transport chain protected

  11. Mobilities Mobilities

    Directory of Open Access Journals (Sweden)

    César Pompeyo

    2011-12-01

    Full Text Available Urry, John (2007 Mobilities.Oxford: Polity Press.Urry, John (2007 Mobilities.Oxford: Polity Press.John Urry (1946-, profesor en la Universidad de Lancaster, es un sociólogo de sobra conocido y altamente reputado en el panorama internacional de las ciencias sociales. Su dilatada carrera, aparentemente dispersa y diversificada, ha seguido senderos bastante bien definidos dejando tras de sí un catálogo extenso de obras sociológicas de primer nivel. Sus primeros trabajos se centraban en el campo de la teoría social y la filosofía de las ciencias sociales o de la sociología del poder [...

  12. Near-Optimal Tracking Control of Mobile Robots Via Receding-Horizon Dual Heuristic Programming.

    Science.gov (United States)

    Lian, Chuanqiang; Xu, Xin; Chen, Hong; He, Haibo

    2016-11-01

    Trajectory tracking control of wheeled mobile robots (WMRs) has been an important research topic in control theory and robotics. Although various tracking control methods with stability have been developed for WMRs, it is still difficult to design optimal or near-optimal tracking controller under uncertainties and disturbances. In this paper, a near-optimal tracking control method is presented for WMRs based on receding-horizon dual heuristic programming (RHDHP). In the proposed method, a backstepping kinematic controller is designed to generate desired velocity profiles and the receding horizon strategy is used to decompose the infinite-horizon optimal control problem into a series of finite-horizon optimal control problems. In each horizon, a closed-loop tracking control policy is successively updated using a class of approximate dynamic programming algorithms called finite-horizon dual heuristic programming (DHP). The convergence property of the proposed method is analyzed and it is shown that the tracking control system based on RHDHP is asymptotically stable by using the Lyapunov approach. Simulation results on three tracking control problems demonstrate that the proposed method has improved control performance when compared with conventional model predictive control (MPC) and DHP. It is also illustrated that the proposed method has lower computational burden than conventional MPC, which is very beneficial for real-time tracking control.

  13. Arsenic in drinking water and lung cancer: A systematic review

    International Nuclear Information System (INIS)

    Celik, Ismail; Gallicchio, Lisa; Boyd, Kristina; Lam, Tram K.; Matanoski, Genevieve; Tao Xuguang; Shiels, Meredith; Hammond, Edward; Chen Liwei; Robinson, Karen A.; Caulfield, Laura E.; Herman, James G.; Guallar, E