Science.gov

Sample records for dissolved metal concentration

  1. [Concentrations and Speciation of Dissolved Heavy Metal in Rainwater in Guiyang, China].

    PubMed

    Zhu, Zhao-zhou; Li, Jun; Wang, Zhi-ru

    2015-06-01

    In order to understand the pollution situation, as well as seasonal changes in characteristics and speciation of dissolved heavy metals in acid rain control zone, the concentrations of dissolved heavy metals in rainwater collected at Guiyang were measured using inductively coupled plasma mass spectrometry (ICP-MS). And the speciation of dissolved heavy metals was further simulated by PHREEQC model. The results showed that the dissolved Co, Ni, Cu, Zn and Cd concentrations were low and not higher than the national standards for drinking water quality in China. The dissolved Pd concentrations were high in fall and winter and higher than the national standards for drinking water quality in China. The Co and Ni in rainwater mainly came from the crust and there was almost no human impact. The Cu, Zn, Cd and Pd pollutions in rainwater were affected by human activity with different levels. The degrees of contamination in autumn and winter were more serious than those in spring and summer. The free metal ion species was the dominant form of dissolved heavy metal, accounting for 47.27%-95.28% of the dissolved metal in rainwater from Guiyang city. The free metal ion species was followed in abundance by Metal-Oxalate and Metal-sulfate complexes that accounted for 0.72% -51.87% and 0.50%-7.66%, respectively. The acidity of rainwater, acid type as well as content of ligand more likely controlled the distribution of dissolved heavy metal in precipitation. PMID:26387294

  2. [Concentrations and Speciation of Dissolved Heavy Metal in Rainwater in Guiyang, China].

    PubMed

    Zhu, Zhao-zhou; Li, Jun; Wang, Zhi-ru

    2015-06-01

    In order to understand the pollution situation, as well as seasonal changes in characteristics and speciation of dissolved heavy metals in acid rain control zone, the concentrations of dissolved heavy metals in rainwater collected at Guiyang were measured using inductively coupled plasma mass spectrometry (ICP-MS). And the speciation of dissolved heavy metals was further simulated by PHREEQC model. The results showed that the dissolved Co, Ni, Cu, Zn and Cd concentrations were low and not higher than the national standards for drinking water quality in China. The dissolved Pd concentrations were high in fall and winter and higher than the national standards for drinking water quality in China. The Co and Ni in rainwater mainly came from the crust and there was almost no human impact. The Cu, Zn, Cd and Pd pollutions in rainwater were affected by human activity with different levels. The degrees of contamination in autumn and winter were more serious than those in spring and summer. The free metal ion species was the dominant form of dissolved heavy metal, accounting for 47.27%-95.28% of the dissolved metal in rainwater from Guiyang city. The free metal ion species was followed in abundance by Metal-Oxalate and Metal-sulfate complexes that accounted for 0.72% -51.87% and 0.50%-7.66%, respectively. The acidity of rainwater, acid type as well as content of ligand more likely controlled the distribution of dissolved heavy metal in precipitation.

  3. Seasonality of diel cycles of dissolved trace-metal concentrations in a Rocky Mountain stream

    USGS Publications Warehouse

    Nimick, D.A.; Cleasby, T.E.; McCleskey, R.B.

    2005-01-01

    Substantial diel (24-h) cycles in dissolved (0.1-??m filtration) metal concentrations were observed during summer low flow, winter low flow, and snowmelt runoff in Prickly Pear Creek, Montana. During seven diel sampling episodes lasting 34-61.5 h, dissolved Mn and Zn concentrations increased from afternoon minimum values to maximum values shortly after sunrise. Dissolved As concentrations exhibited the inverse timing. The magnitude of diel concentration increases varied in the range 17-152% for Mn and 70-500% for Zn. Diel increases of As concentrations (17-55%) were less variable. The timing of minimum and maximum values of diel streamflow cycles was inconsistent among sampling episodes and had little relation to the timing of metal concentration cycles, suggesting that geochemical rather than hydrological processes are the primary control of diel metal cycles. Diel cycles of dissolved metal concentrations should be assumed to occur at any time of year in any stream with dissolved metals and neutral to alkaline pH. ?? Springer-Verlag 2005.

  4. Seasonality of Diel Cycles of Dissolved Trace-Metal Concentrations in a Rocky Mountain Stream

    NASA Astrophysics Data System (ADS)

    Nimick, D. A.; Cleasby, T. E.; McCleskey, R. B.

    2004-12-01

    Substantial diel (24-hour) cycles in dissolved (0.1-μ m filtration) metal concentrations were observed during summer low flow, winter low flow, and snowmelt runoff in Prickly Pear Creek in southwestern Montana. The stream was alkaline (pH of 7.65-9.06), and dissolved metal concentrations were relatively low (1.8-7.1 μ g/L for As, 18-57 μ g/L for Mn, and 12-123 μ g/L for Zn). The metals are derived from abandoned mine lands in the stream's headwaters; As also is derived from geothermal sources. During seven diel sampling episodes, each lasting 34-61.5 hours, concentrations of dissolved Mn and Zn increased from minimum values in the afternoon to maximum values shortly after sunrise. The timing of diel cycles of dissolved As concentrations exhibited the inverse pattern. The magnitude of concentration increases during individual 24-hour periods ranged from 17-152% for Mn and 70-500% for Zn, and correlated positively with the magnitude of diel increases of pH and temperature, indicating that geochemical processes involving reactive inorganic and organic surfaces on and in the streambed probably control these diel metal cycles. Diel increases of As concentrations (17-55%) were proportionally smaller and less variable among the seasonal sampling episodes than for Mn and Zn, and they correlated poorly with diel increases of pH and temperature. Streamflow among the seven sampling episodes ranged from 0.35-3.3 m3/s. The timing of minimum and maximum values of diel streamflow cycles was inconsistent among sampling episodes and had little relation to the timing of metal concentration cycles, indicating that hydrological processes are not a primary control of diel metal cycles. Diel cycles of dissolved metal concentrations may occur at any time of year and during various hydrologic conditions in all streams with dissolved metals and neutral to alkaline pH.

  5. Diel cycles in dissolved metal concentrations in streams: Occurrence and possible causes

    USGS Publications Warehouse

    Nimick, D.A.; Gammons, C.H.; Cleasby, T.E.; Madison, J.P.; Skaar, D.; Brick, C.M.

    2003-01-01

    Substantial diel (24-hour) cycles in dissolved (0.1-??m filtration) metal concentrations were observed during low flow for 18 sampling episodes at 14 sites on 12 neutral and alkaline streams draining historical mining areas in Montana and Idaho. At some sites, concentrations of Cd, Mn, Ni, and Zn increased as much as 119, 306, 167, and 500%, respectively, from afternoon minimum values to maximum values shortly after sunrise. Arsenic concentrations exhibited the inverse temporal pattern with increases of up to 54%. Variations in Cu concentrations were small and inconsistent. Diel metal cycles are widespread and persistent, occur over a wide range of metal concentrations, and likely are caused primarily by instream geochemical processes. Adsorption is the only process that can explain the inverse temporal patterns of As and the divalent metals. Diel metal cycles have important implications for many types of water-quality studies and for understanding trace-metal mobility.

  6. Assessing time-integrated dissolved concentrations and predicting toxicity of metals during diel cycling in streams

    USGS Publications Warehouse

    Balistrieri, Laurie S.; Nimick, David A.; Mebane, Christopher A.

    2012-01-01

    Evaluating water quality and the health of aquatic organisms is challenging in systems with systematic diel (24 hour) or less predictable runoff-induced changes in water composition. To advance our understanding of how to evaluate environmental health in these dynamic systems, field studies of diel cycling were conducted in two streams (Silver Bow Creek and High Ore Creek) affected by historical mining activities in southwestern Montana. A combination of sampling and modeling tools were used to assess the toxicity of metals in these systems. Diffusive Gradients in Thin Films (DGT) samplers were deployed at multiple time intervals during diel sampling to confirm that DGT integrates time-varying concentrations of dissolved metals. Thermodynamic speciation calculations using site specific water compositions, including time-integrated dissolved metal concentrations determined from DGT, and a competitive, multiple-metal biotic ligand model incorporated into the Windemere Humic Aqueous Model Version 6.0 (WHAM VI) were used to determine the chemical speciation of dissolved metals and biotic ligands. The model results were combined with previously collected toxicity data on cutthroat trout to derive a relationship that predicts the relative survivability of these fish at a given site. This integrative approach may prove useful for assessing water quality and toxicity of metals to aquatic organisms in dynamic systems and evaluating whether potential changes in environmental health of aquatic systems are due to anthropogenic activities or natural variability.

  7. Assessing time-integrated dissolved concentrations and predicting toxicity of metals during diel cycling in streams

    USGS Publications Warehouse

    Balistrieri, Laurie S.; Nimick, David A.; Mebane, Christopher A.

    2012-01-01

    Evaluating water quality and the health of aquatic organisms is challenging in systems with systematic diel (24 h) or less predictable runoff-induced changes in water composition. To advance our understanding of how to evaluate environmental health in these dynamic systems, field studies of diel cycling were conducted in two streams (Silver Bow Creek and High Ore Creek) affected by historical mining activities in southwestern Montana. A combination of sampling and modeling tools was used to assess the toxicity of metals in these systems. Diffusive Gradients in Thin Films (DGT) samplers were deployed at multiple time intervals during diel sampling to confirm that DGT integrates time-varying concentrations of dissolved metals. Site specific water compositions, including time-integrated dissolved metal concentrations determined from DGT, a competitive, multiple-toxicant biotic ligand model, and the Windemere Humic Aqueous Model Version 6.0 (WHAM VI) were used to determine the equilibrium speciation of dissolved metals and biotic ligands. The model results were combined with previously collected toxicity data on cutthroat trout to derive a relationship that predicts the relative survivability of these fish at a given site. This integrative approach may prove useful for assessing water quality and toxicity of metals to aquatic organisms in dynamic systems and evaluating whether potential changes in environmental health of aquatic systems are due to anthropogenic activities or natural variability.

  8. METHOD OF DISSOLVING URANIUM METAL

    DOEpatents

    Slotin, L.A.

    1958-02-18

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

  9. Dissolved, particulate and acid-leachable trace metal concentrations in North Atlantic precipitation collected on the Global Change Expedition

    SciTech Connect

    Lim, B.; Jickells, T.D. )

    1990-12-01

    Atmospheric inputs of trace metals into surface waters are an important pathway for the oceanic biogeochemical cycling of many trace constituents. Rainwater samples from six precipitation events were collected on board ship during legs 3 and 4 of the Global Change Expedition over the North Atlantic Ocean and analyzed for dissolved, particulate (Al and Pb), and acid-leachable trace metals (Al, Fe, Mn, Cd, Cu, Pb, Zn). Acid-leachable concentrations of the elements were similar to reported values from the North Atlantic and Pacific Oceans which were measured using comparable acidification procedures. Concentrations of dissolved and particulate Al and Pb were determined in rain events acid-leachable and total trace metal concentrations suggest that the acid-leachable fraction of metals can significantly underestimate total concentrations of crustal elements in rain. The solubilities of Al and Pb in precipitation were variable and mean solubilities of the elements were 13% and 45%, respectively. Recycled sea salt components were less than 14% for Al, Fe, Mn, Pb, Cd, Cu, and Zn, indicating that the net trace metal flux is from the atmosphere to the oceans. Deep sea particle fluxes for these metals through the western tropical North Atlantic exceed atmospheric deposition fluxes by a factor of 18 to 41. 57 refs., 2 figs., 12 tabs.

  10. METHOD OF DISSOLVING METALLIC URANIUM

    DOEpatents

    Schulz, W.W.

    1959-07-28

    A process is presented for more rapidly dissolving metallic uranium which comprises contacting the uranium with a mixture of nitric and phosphoric acids. The preferred concentration is a mixture which is about 10 M in nitric acid and between 0.1 to 0.15 M in phosphoric acid.

  11. [Effect of the change in sulphate and dissolved oxygen mass concentration on metal release in old cast iron distribution pipes].

    PubMed

    Wu, Yong-li; Shi, Bao-you; Sun, Hui-fang; Zhang, Zhi-huan; Gu, Jun-nong; Wang, Dong-sheng

    2013-09-01

    To understand the processes of corrosion by-product release and the consequent "red water" problems caused by the variation of water chemical composition in drinking water distribution system, the effect of sulphate and dissolved oxygen (DO) concentration on total iron release in corroded old iron pipe sections historically transporting groundwater was investigated in laboratory using small-scale pipe section reactors. The release behaviors of some low-level metals, such as Mn, As, Cr, Cu, Zn and Ni, in the process of iron release were also monitored. The results showed that the total iron and Mn release increased significantly with the increase of sulphate concentration, and apparent red water occurred when sulphate concentration was above 400 mg x L(-1). With the increase of sulfate concentration, the effluent concentrations of As, Cr, Cu, Zn and Ni also increased obviously, however, the effluent concentrations of these metals were lower than the influent concentrations under most circumstances, which indicated that adsorption of these metals by pipe corrosion scales occurred. Increasing DO within a certain range could significantly inhibit the iron release.

  12. Dissolved Concentrations, Sources, and Risk Evaluation of Selected Metals in Surface Water from Mangla Lake, Pakistan

    PubMed Central

    Saleem, Muhammad; Iqbal, Javed; Shah, Munir H.

    2014-01-01

    The present study is carried out for the assessment of water quality parameters and selected metals levels in surface water from Mangla Lake, Pakistan. The metal levels (Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Sr, and Zn) were determined by flame atomic absorption spectrophotometry. Average levels of Cd, Co, Cr, Ni, and Pb were higher than the allowable concentrations set by national and international agencies. Principal component analysis indicated significant anthropogenic contributions of Cd, Co, Cr, Ni, and Pb in the water reservoir. Noncarcinogenic risk assessment was then evaluated using Hazard Quotient (HQing/derm) and Hazard Index (HIing/derm) following USEPA methodology. For adults and children, Cd, Co, Cr, and Pb (HQing > 1) emerged as the most important pollutants leading to noncarcinogenic concerns via ingestion route, whereas there was no risk via dermal contact of surface water. This study helps in establishing pollutant loading reduction goal and the total maximum daily loads, and consequently contributes to preserve public health and develop water conservation strategy. PMID:24744690

  13. Dissolved heavy metal concentrations of the Kralkızı, Dicle and Batman dam reservoirs in the Tigris River basin, Turkey.

    PubMed

    Varol, Memet

    2013-10-01

    Water samples were collected at monthly intervals during 1 year of monitoring from Kralkızı, Dicle and Batman dam reservoirs in the Tigris River basin to assess the concentrations of dissolved heavy metals and to determine their spatial and seasonal variations. The results indicated that dissolved heavy metal concentrations in the reservoirs were very low, reflecting the natural background levels. The lowest total metal concentrations in the three dam reservoirs were detected at sampling sites close to the dam wall. However, the highest total concentrations were observed at sites, which are located at the entrance of the streams to the reservoirs. Fe, Cr and Ni were the most abundant elements in the reservoirs, whereas Cd and As were the less abundant. The mean concentrations of dissolved metals in the dam reservoirs never exceeded the maximum permitted concentrations established by EC (European Community), WHO and USEPA drinking water quality guidelines. All heavy metals showed significant seasonal variations. As, Cd, Cr, Cu, Fe, Ni and Pb displayed higher values in the dry season, while higher values for Zn in the wet season. Cluster analysis grouped all ten sampling sites into three clusters. Clusters 1 and 2, and cluster 3 corresponded to relatively low polluted and moderate polluted regions, respectively. PCA/FA demonstrated the dissolved metals in the dam reservoirs controlled by natural sources.

  14. Assessing the concentration, speciation, and toxicity of dissolved metals during mixing of acid-mine drainage and ambient river water downstream of the Elizabeth Copper Mine, Vermont, USA

    USGS Publications Warehouse

    Balistrieri, L.S.; Seal, R.R.; Piatak, N.M.; Paul, B.

    2007-01-01

    The authors determine the composition of a river that is impacted by acid-mine drainage, evaluate dominant physical and geochemical processes controlling the composition, and assess dissolved metal speciation and toxicity using a combination of laboratory, field and modeling studies. Values of pH increase from 3.3 to 7.6 and the sum of dissolved base metal (Cd + Co + Cu + Ni + Pb + Zn) concentrations decreases from 6270 to 100 ??g/L in the dynamic mixing and reaction zone that is downstream of the river's confluence with acid-mine drainage. Mixing diagrams and PHREEQC calculations indicate that mixing and dilution affect the concentrations of all dissolved elements in the reach, and are the dominant processes controlling dissolved Ca, K, Li, Mn and SO4 concentrations. Additionally, dissolved Al and Fe concentrations decrease due to mineral precipitation (gibbsite, schwertmannite and ferrihydrite), whereas dissolved concentrations of Cd, Co, Cu, Ni, Pb and Zn decrease due to adsorption onto newly formed Fe precipitates. The uptake of dissolved metals by aquatic organisms is dependent on the aqueous speciation of the metals and kinetics of complexation reactions between metals, ligands and solid surfaces. Dissolved speciation of Cd, Cu, Ni and Zn in the mixing and reaction zone is assessed using the diffusive gradients in thin films (DGT) technique and results of speciation calculations using the Biotic Ligand Model (BLM). Data from open and restricted pore DGT units indicate that almost all dissolved metal species are inorganic and that aqueous labile or DGT available metal concentrations are generally equal to total dissolved concentrations in the mixing zone. Exceptions occur when labile metal concentrations are underestimated due to competition between H+ and metal ions for Chelex-100 binding sites in the DGT units at low pH values. Calculations using the BLM indicate that dissolved Cd and Zn species in the mixing and reaction zone are predominantly inorganic

  15. Contribution of groundwater discharge to the coastal dissolved nutrients and trace metal concentrations in Majorca Island: karstic vs detrital systems.

    PubMed

    Tovar-Sánchez, Antonio; Basterretxea, Gotzon; Rodellas, Valentí; Sánchez-Quiles, David; García-Orellana, Jordi; Masqué, Pere; Jordi, Antoni; López, José M; Garcia-Solsona, Ester

    2014-10-21

    Submarine groundwater discharge (SGD) and derived nutrient (NO2(-), NO3(-), NH4(+), PO4(3-), and SiO2) and trace element (Cd, Co, Cu, Fe, Mo, Ni, Pb, V and Zn) loadings to the coastal sea were systematically assessed along the coast of Majorca Island, Spain, in a general survey around the island and in three representative coves during 2010. We estimated that brackish water discharges through the shoreline are important contributors to the DIN, SiO2, Fe, and Zn budgets of the nearshore waters. Furthermore, our results showed that SGD-derived elements are conditioned by the hydrogeological formations of the aquifer and discharge type. Thus, while rapid discharges through karstic conduits are enriched in SiO2 and Zn, the large detrital aquifers of the island typically present enhanced concentrations of Fe. The estimated total annual inputs of chemicals constituents discharged by SGD to the coastal waters were as follows: DIN: 610 × 10(3) kg yr(-1), SiO2: 1400 × 10(3) kg yr(-1), Fe: 3.2 × 10(3) kg yr(-1), and Zn: 2.0 × 10(3) kg yr(-1). Our results provide evidence that SGD is a major contributor to the dissolved pool of inorganic nutrients and trace metals in the nearshore waters of Majorca.

  16. Contribution of groundwater discharge to the coastal dissolved nutrients and trace metal concentrations in Majorca Island: karstic vs detrital systems.

    PubMed

    Tovar-Sánchez, Antonio; Basterretxea, Gotzon; Rodellas, Valentí; Sánchez-Quiles, David; García-Orellana, Jordi; Masqué, Pere; Jordi, Antoni; López, José M; Garcia-Solsona, Ester

    2014-10-21

    Submarine groundwater discharge (SGD) and derived nutrient (NO2(-), NO3(-), NH4(+), PO4(3-), and SiO2) and trace element (Cd, Co, Cu, Fe, Mo, Ni, Pb, V and Zn) loadings to the coastal sea were systematically assessed along the coast of Majorca Island, Spain, in a general survey around the island and in three representative coves during 2010. We estimated that brackish water discharges through the shoreline are important contributors to the DIN, SiO2, Fe, and Zn budgets of the nearshore waters. Furthermore, our results showed that SGD-derived elements are conditioned by the hydrogeological formations of the aquifer and discharge type. Thus, while rapid discharges through karstic conduits are enriched in SiO2 and Zn, the large detrital aquifers of the island typically present enhanced concentrations of Fe. The estimated total annual inputs of chemicals constituents discharged by SGD to the coastal waters were as follows: DIN: 610 × 10(3) kg yr(-1), SiO2: 1400 × 10(3) kg yr(-1), Fe: 3.2 × 10(3) kg yr(-1), and Zn: 2.0 × 10(3) kg yr(-1). Our results provide evidence that SGD is a major contributor to the dissolved pool of inorganic nutrients and trace metals in the nearshore waters of Majorca. PMID:25215451

  17. Dissolved metals and associated constituents in abandoned coal-mine discharges, Pennsylvania, USA. Part 2: Geochemical controls on constituent concentrations

    USGS Publications Warehouse

    Cravotta, C.A.

    2008-01-01

    Water-quality data for discharges from 140 abandoned mines in the Anthracite and Bituminous Coalfields of Pennsylvania reveal complex relations among the pH and dissolved solute concentrations that can be explained with geochemical equilibrium models. Observed values of pH ranged from 2.7 to 7.3 in the coal-mine discharges (CMD). Generally, flow rates were smaller and solute concentrations were greater for low-pH CMD samples; pH typically increased with flow rate. Although the frequency distribution of pH was similar for the anthracite and bituminous discharges, the bituminous discharges had smaller median flow rates; greater concentrations of SO4, Fe, Al, As, Cd, Cu, Ni and Sr; comparable concentrations of Mn, Cd, Zn and Se; and smaller concentrations of Ba and Pb than anthracite discharges with the same pH values. The observed relations between the pH and constituent concentrations can be attributed to (1) dilution of acidic water by near-neutral or alkaline ground water; (2) solubility control of Al, Fe, Mn, Ba and Sr by hydroxide, sulfate, and/or carbonate minerals; and (3) aqueous SO4-complexation and surface-complexation (adsorption) reactions. The formation of AlSO4+ and AlHSO42 + complexes adds to the total dissolved Al concentration at equilibrium with Al(OH)3 and/or Al hydroxysulfate phases and can account for 10-20 times greater concentrations of dissolved Al in SO4-laden bituminous discharges compared to anthracite discharges at pH of 5. Sulfate complexation can also account for 10-30 times greater concentrations of dissolved FeIII concentrations at equilibrium with Fe(OH)3 and/or schwertmannite (Fe8O8(OH)4.5(SO4)1.75) at pH of 3-5. In contrast, lower Ba concentrations in bituminous discharges indicate that elevated SO4 concentrations in these CMD sources could limit Ba concentrations by the precipitation of barite (BaSO4). Coprecipitation of Sr with barite could limit concentrations of this element. However, concentrations of dissolved Pb, Cu, Cd, Zn

  18. Diurnal variations in, and influences on, concentrations of particulate and dissolved arsenic and metals in the mildly alkaline Wallkill River, New Jersey, USA

    USGS Publications Warehouse

    Barringer, J.L.; Wilson, T.P.; Szabo, Z.; Bonin, J.L.; Fischer, J.M.; Smith, N.P.

    2008-01-01

    Diurnal variations in particulate and dissolved As and metal concentrations were observed in mildly alkaline water from a wetlands site on the Wallkill River in northwestern New Jersey. The site, underlain by glacial sediments over dolomite bedrock, is 10 km downstream from a mined area of the Franklin Marble, host to Zn ores, also As and Mn minerals. In mid-September 2005, maxima and minima in dissolved-oxygen-concentration and pH, typically caused by photosynthesis and respiration, occurred at 2000 and 0800 hours. Concentrations of dissolved As (1.52-1.95 ??g/L) peaked at dusk (2000 hours), whereas dissolved Mn and Zn concentrations (76.5-96.9 and 8.55-12.8 ??g/L, respectively) were lowest at dusk and peaked at 1000 hours. These opposing cycles probably reflect sorption and desorption of As (an anion), and Mn and Zn (cations) as pH varied throughout the 24-h period. Doubly-peaked cycles of B, Cl, SO4, and nutrients also were observed; these may result from upstream discharges of septic-system effluent. Both recoverable amd particulate Al, Fe, Mn, and Zn concentrations peaked between 0200 and 0600 hours. The particulate metals cycle, with perturbations at 0400 hours, may be influenced by biological activity. ?? 2007 Springer-Verlag.

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

    USGS Publications Warehouse

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

    2007-01-01

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

  20. Cellular partitioning of nanoparticulate versus dissolved metals in marine phytoplankton.

    PubMed

    Bielmyer-Fraser, Gretchen K; Jarvis, Tayler A; Lenihan, Hunter S; Miller, Robert J

    2014-11-18

    Discharges of metal oxide nanoparticles into aquatic environments are increasing with their use in society, thereby increasing exposure risk for aquatic organisms. Separating the impacts of nanoparticle from dissolved metal pollution is critical for assessing the environmental risks of the rapidly growing nanomaterial industry, especially in terms of ecosystem effects. Metal oxides negatively affect several species of marine phytoplankton, which are responsible for most marine primary production. Whether such toxicity is generally due to nanoparticles or exposure to dissolved metals liberated from particles is uncertain. The type and severity of toxicity depends in part on whether phytoplankton cells take up and accumulate primarily nanoparticles or dissolved metal ions. We compared the responses of the marine diatom, Thalassiosira weissflogii, exposed to ZnO, AgO, and CuO nanoparticles with the responses of T. weissflogii cells exposed to the dissolved metals ZnCl2, AgNO3, and CuCl2 for 7 d. Cellular metal accumulation, metal distribution, and algal population growth were measured to elucidate differences in exposure to the different forms of metal. Concentration-dependent metal accumulation and reduced population growth were observed in T. weissflogii exposed to nanometal oxides, as well as dissolved metals. Significant effects on population growth were observed at the lowest concentrations tested for all metals, with similar toxicity for both dissolved and nanoparticulate metals. Cellular metal distribution, however, markedly differed between T. weissflogii exposed to nanometal oxides versus those exposed to dissolved metals. Metal concentrations were highest in the algal cell wall when cells were exposed to metal oxide nanoparticles, whereas algae exposed to dissolved metals had higher proportions of metal in the organelle and endoplasmic reticulum fractions. These results have implications for marine plankton communities as well as higher trophic levels, since

  1. Cellular partitioning of nanoparticulate versus dissolved metals in marine phytoplankton.

    PubMed

    Bielmyer-Fraser, Gretchen K; Jarvis, Tayler A; Lenihan, Hunter S; Miller, Robert J

    2014-11-18

    Discharges of metal oxide nanoparticles into aquatic environments are increasing with their use in society, thereby increasing exposure risk for aquatic organisms. Separating the impacts of nanoparticle from dissolved metal pollution is critical for assessing the environmental risks of the rapidly growing nanomaterial industry, especially in terms of ecosystem effects. Metal oxides negatively affect several species of marine phytoplankton, which are responsible for most marine primary production. Whether such toxicity is generally due to nanoparticles or exposure to dissolved metals liberated from particles is uncertain. The type and severity of toxicity depends in part on whether phytoplankton cells take up and accumulate primarily nanoparticles or dissolved metal ions. We compared the responses of the marine diatom, Thalassiosira weissflogii, exposed to ZnO, AgO, and CuO nanoparticles with the responses of T. weissflogii cells exposed to the dissolved metals ZnCl2, AgNO3, and CuCl2 for 7 d. Cellular metal accumulation, metal distribution, and algal population growth were measured to elucidate differences in exposure to the different forms of metal. Concentration-dependent metal accumulation and reduced population growth were observed in T. weissflogii exposed to nanometal oxides, as well as dissolved metals. Significant effects on population growth were observed at the lowest concentrations tested for all metals, with similar toxicity for both dissolved and nanoparticulate metals. Cellular metal distribution, however, markedly differed between T. weissflogii exposed to nanometal oxides versus those exposed to dissolved metals. Metal concentrations were highest in the algal cell wall when cells were exposed to metal oxide nanoparticles, whereas algae exposed to dissolved metals had higher proportions of metal in the organelle and endoplasmic reticulum fractions. These results have implications for marine plankton communities as well as higher trophic levels, since

  2. TOTAL DISSOLVED AND BIOAVAILABLE METALS AT LAKE TEXOMA MARINAS

    EPA Science Inventory

    Dissolved metals in water and total metals in sediments have been measured at marina areas in Lake Texoma during June 1999 to October 2001, and October 2001, respectively. The metals most often found in the highest concentrations in marina water were Na and Ca, followed by Mg an...

  3. Summary of Dissolved Concentration Limits

    SciTech Connect

    Yueting Chen

    2001-06-11

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

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

    USGS Publications Warehouse

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

    2015-09-02

    Following coagulation, but prior to passage through the wetland cells, coagulation treatments transferred dissolved mercury and carbon to the particulate fraction relative to untreated source water: at the wetland cell inlets, the coagulation treatments decreased concentrations of filtered total mercury by 59–76 percent, filtered monomethyl mercury by 40–70 percent, and dissolved organic carbon by 65–86 percent. Passage through the wetland cells decreased the particulate fraction of mercury in wetland cells that received coagulant-treated water. Changes in total mercury, monomethyl mercury, and dissolved organic carbon concentrations resulting from wetland passage varied both by treatment and season. Despite increased monomethyl mercury in the filtered fraction during wetland passage between March and August, the coagulation-wetland systems generally decreased total mercury (filtered plus particulate) and monomethyl mercury (filtered plus particulate) concentrations relative to source water. Coagulation—either alone or in association with constructed wetlands—could be an effective way to decrease concentrations of mercury and dissolved organic carbon in surface water as well as the bioavailability of mercury in the Sacramento–San Joaquin Delta.

  5. Fluctuation of dissolved heavy metal concentrations in the leachate from anaerobic digestion of municipal solid waste in commercial scale landfill bioreactors: The effect of pH and associated mechanisms.

    PubMed

    Xie, S; Ma, Y; Strong, P J; Clarke, W P

    2015-12-15

    Heavy metals present in landfill leachate have infrequently been related to complete anaerobic degradation municipal solid waste (MSW) due to discrete ages of deposited MSW layers and leachate channelling in landfills. In this study, anaerobic digestion of MSW was performed in two enclosed 1000 tonne bioreactors using a unique flood and drain process. Leachates were characterised in terms of pH, soluble chemical oxygen demand, volatile fatty acids (VFAs), ammonium nitrogen and heavy metals over the entire course of digestion. All parameters, including pH, fluctuated during acidogenesis, acetogenesis and methanogenesis, which strongly impacted on the dynamics of dissolved heavy metal concentrations. The simulation of dissolution and precipitation processes indicated that metal sulphide precipitation was not a factor as metal concentrations exceeded solubility limits. The correlation of pH and dissolved heavy metal concentrations indicated that other, mechanisms were involved in the homogenised conditions within the bioreactors. Beside dissolution and precipitation, the main processes most likely involved in metal distributions were adsorption (Zn, Cu, Ni, Pb and Cd), complexation (Cr) or combinations of both process (As and Co).

  6. DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS

    SciTech Connect

    NA

    2004-11-22

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

  7. DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS

    SciTech Connect

    P. Bernot

    2005-07-13

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

  8. Dissolved Concentration Limits of Radioactive Elements

    SciTech Connect

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

    2003-06-20

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

  9. An advanced passive diffusion sampler for the determination of dissolved gas concentrations

    NASA Astrophysics Data System (ADS)

    Gardner, P.; Solomon, D. K.

    2009-06-01

    We have designed and tested a passive headspace sampler for the collection of noble gases that allows for the precise calculation of dissolved gas concentrations from measured gas mixing ratios. Gas permeable silicon tubing allows for gas exchange between the headspace in the sampler volume and the dissolved gases in the adjacent water. After reaching equilibrium, the aqueous-phase concentration is related to the headspace concentration by Henry's law. Gas exchange between the water and headspace can be shut off in situ, preserving the total dissolved gas pressure upon retrieval. Gas samples are then sealed in an all metal container, retaining even highly mobile helium. Dissolved noble gas concentrations measured in these diffusion samplers are in good agreement with traditional copper tube aqueous-phase samples. These significantly reduce the laboratory labor in extracting the gases from a water sample and provide a simple and robust method for collecting dissolved gas concentrations in a variety of aqueous environments.

  10. The seasonal influence on the spatial distribution of dissolved selected metals in Lake Naivasha, Kenya

    NASA Astrophysics Data System (ADS)

    Kamau, Joseph Nyingi; Gachanja, Anthony; Ngila, Catherine; Kazungu, Johnson Michael; Zhai, Mingzhe

    Lake Naivasha is the only freshwater Lake in Rift Valley, in Kenya. It lies in a fertile semi-arid basin. The Lake has no surface water outlet and is presumed to be under stress. Dissolved metals are directly taken up by bacteria, algae, plants, and planktonic and benthic organisms. Dissolved metals can also adsorb to particulate matter in water column and enter aquatic organisms through various routes. Cadmium, copper, lead and zinc may bioaccumulate within lower organisms, yet they do not biomagnify up the food chain as do mercury and selenium. This study reports on the levels and distribution of dissolved heavy metals and investigates the influence of physicochemical parameters on metal mobilization. The bioavailability of selected metals was investigated by relating the levels of dissolved metals to that in fish. Water abstraction for irrigation and domestic use, compounded with organic matter inflow will affect physicochemical parameters and hence influences the mobilization of heavy metals. Dissolved Zn correlated highly with sediment pH (r = 0.67) indicating that dissolution increases with increase in pH. In addition, the fact that the pH also correlated positively with organic matter r = 0.50, Eh r = 0.63, temperature r = 0.56 and dissolved oxygen r = 56, would suggest that organic bound Zn contributed significantly to the concentration of dissolved Zn. In situ flux experiments indicated that the fringing papyrus reeds located along the shores of Lake Naivasha provided sites for metal immobilization due to their coprecipitation on redox sensitive.

  11. The effect of membrane filtration on dissolved trace element concentrations

    USGS Publications Warehouse

    Horowitz, A.J.; Lum, K.R.; Garbarino, J.R.; Hall, G.E.M.; Lemieux, C.; Demas, C.R.

    1996-01-01

    The almost universally accepted operational definition for dissolved constituents is based on processing whole-water samples through a 0.45-??m membrane filter. Results from field and laboratory experiments indicate that a number of factors associated with filtration, other than just pore size (e.g., diameter, manufacturer, volume of sample processed, amount of suspended sediment in the sample), can produce substantial variations in the 'dissolved' concentrations of such elements as Fe, Al, Cu, Zn, Pb, Co, and Ni. These variations result from the inclusion/exclusion of colloidally- associated trace elements. Thus, 'dissolved' concentrations quantitated by analyzing filtrates generated by processing whole-water through similar pore- sized membrane filters may not be equal/comparable. As such, simple filtration through a 0.45-??m membrane filter may no longer represent an acceptable operational definition for dissolved chemical constituents. This conclusion may have important implications for environmental studies and regulatory agencies.

  12. Effect of membrane filtration artifacts on dissolved trace element concentrations

    USGS Publications Warehouse

    Horowitz, Arthur J.; Elrick, Kent A.; Colberg, Mark R.

    1992-01-01

    Among environment scientists, the current and almost universally accepted definition of dissolved constituents is an operational one; only those materials which pass through a 0.45-??m membrane filter are considered to be dissolved. Detailed laboratory and field studies on Fe and Al indicate that a number of factors associated with filtration, other than just pore size, can substantially alter 'dissolved' trace element concentrations; these include: filter type, filter diameter, filtration method, volume of sample processed, suspended sediment concentration, suspended sediment grain-size distribution, concentration of colloids and colloidally associated trace elements and concentration of organic matter. As such, reported filtered-water concentrations employing the same pore size filter may not be equal. Filtration artifacts may lead to the production of chemical data that indicate seasonal or annual 'dissolved' chemical trends which do not reflect actual environmental conditions. Further, the development of worldwide averages for various dissolved chemical constituents, the quantification of geochemical cycles, and the determination of short- or long-term environmental chemical trends may be subject to substantial errors, due to filtration artifacts, when data from the same or multiple sources are combined. Finally, filtration effects could have a substantial impact on various regulatory requirements.

  13. Dissolved oxygen concentration affects hybrid striped bass growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management of dissolved oxygen (DO) concentration in ponds at night during the growing season is important because fish growth and yield are greater in ponds with higher nightly DO concentrations. Three studies were conducted to quantify performance traits and metabolic responses of hybrid striped b...

  14. Iron oxides, dissolved silica, and regulation of marine phosphate concentration

    NASA Astrophysics Data System (ADS)

    Planavsky, N.; Reinhard, C.; Lyons, T.

    2008-12-01

    Phosphorous concentrations in iron oxide-rich sediments reflect orthophosphate levels in the water column from which iron oxides precipitated. Sediment P/Fe ratios are also strongly influenced by the concentrations of dissolved species that inhibit orthophosphate-to-ferrihydrite sorption, most notably silica. It may, therefore, be possible to use P/Fe ratios in iron oxide-rich sediments to estimate past dissolved P concentrations, if one considers the evolution of the silica cycle. A compilation of Fe and P data in iron oxide-rich sediments through time reveals an increase in P/Fe ratios after the Jurassic. We propose that this trend indicates evolution of the iron-oxide phosphate removal mechanism caused by decreasing levels of sorption inhibition by dissolved silica. The large difference in P/Fe ratios in Cenozoic versus older iron-oxide rich sediments can be linked with Si drawdown caused by the proliferation of siliceous plankton in the Cretaceous. There is also a late Mesozoic or Cenozoic increase in V/Fe ratios, which provides additional evidence for lower ferrihydrite anion sorption efficiency prior to diatom radiation. P/Fe ratios in iron oxide-rich sediments from the early and middle Phanerozoic are comparable to the ratios in iron formations previously presented as evidence for an early Precambrian phosphate crisis (Bjerrum and Canfield, 2002, Nature, 417:159-162). Given the compelling evidence for higher Si concentrations in the Precambrian compared to the Phanerozoic and dissolved P concentrations comparable to modern levels throughout the Phanerozoic, the presented trend of P/Fe ratios suggests dissolved P concentrations were higher in Precambrian than Phanerozoic oceans. High dissolved P levels in the Precambrian may have been linked to inhibited carbonate fluorapatite (CFA) formation as a result of persistently high levels of carbonate supersaturation. Carbonate ion substitution into CFA scales with the ambient carbonate ion activity and increases

  15. Investigating Factors that Affect Dissolved Oxygen Concentration in Water

    ERIC Educational Resources Information Center

    Jantzen, Paul G.

    1978-01-01

    Describes activities that demonstrate the effects of factors such as wind velocity, water temperature, convection currents, intensity of light, rate of photosynthesis, atmospheric pressure, humidity, numbers of decomposers, presence of oxidizable ions, and respiration by plants and animals on the dissolved oxygen concentration in water. (MA)

  16. Dissolved gas concentrations of the geothermal fluids in Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, Ai-Ti; Yang, Tsanyao Frank

    2010-05-01

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

  17. Effect of dissolved oxygen concentration on sludge settleability.

    PubMed

    Martins, A M P; Heijnen, J J; van Loosdrecht, M C M

    2003-10-01

    This laboratory study presents a detailed evaluation of the effects of dissolved oxygen concentration and accumulation of storage polymers on sludge settleability in activated sludge systems with an aerobic selector. The oxygen and substrate availability regime were simulated in laboratory sequencing batch reactor systems. The experiments showed that low dissolved oxygen concentration (< or =1.1 mg O2 l(-1)) had a strong negative effect on sludge settleability, leading to the proliferation of filamentous bacteria (Thiothrix spp., Type 021N and Type 1851). This negative effect was stronger at high chemical oxygen demand loading rate. This indicates that a compartmentalised (plug flow) aerobic contact tank, designed at short hydraulic residence time to guarantee a strong substrate gradient, with low dissolved oxygen concentration, might be worse for sludge settleability than an "overdesigned" completely mixed contact tank. Contrary to the general hypothesis, the maximum specific acetate uptake rate, poly-beta-hydroxybutyrate production rate, and resistance to short starvation periods are similar in both poor- and well-settling sludge. The results of this study support our previous hypothesis on the importance of substrate gradients for the development of filamentous structures in biological flocs, from soluble organic substrate gradients to dissolved oxygen gradients in sludge flocs.

  18. Octanol-solubility of dissolved and particulate trace metals in contaminated rivers: implications for metal reactivity and availability.

    PubMed

    Turner, Andrew; Mawji, Edward

    2005-05-01

    The lipid-like, amphiphilic solvent, n-octanol, has been used to determine a hydrophobic fraction of dissolved and particulate trace metals (Al, Cd, Co, Cu, Mn, Ni, Pb, Zn) in contaminated rivers. In a sample from the River Clyde, southwest Scotland, octanol-solubility was detected for all dissolved metals except Co, with conditional octanol-water partition coefficients, D(ow), ranging from about 0.2 (Al and Cu) to 1.25 (Pb). In a sample taken from the River Mersey, northwest England, octanol-solubility was detected for dissolved Al and Pb, but only after sample aliquots had been spiked with individual ionic metal standards and equilibrated. Spiking of the River Clyde sample revealed competition among different metals for hydrophobic ligands. Metal displacement from hydrophobic complexes was generally most significant following the addition of ionic Al or Pb, although the addition of either of these metals had little effect on the octanol-solubility of the other. In both river water samples hydrophobic metals were detected on the suspended particles retained by filtration following their extraction in n-octanol. In general, particulate Cu and Zn (up to 40%) were most available, and Al, Co and Pb most resistant (<1%) to octanol extraction. Distribution coefficients defining the concentration ratio of octanol-soluble particle-bound metal to octanol-soluble dissolved metal were in the range 10(3.3)-10(5.3)mlg(-1). The presence of hydrophobic dissolved and particulate metal species has implications for our understanding of the biogeochemical behaviour of metals in aquatic environments. Specifically, such species are predicted to exhibit characteristics of non-polar organic contaminants, including the potential to penetrate the lipid bilayer. Current strategies for assessing the bioavailability and toxicity of dissolved and particulate trace metals in natural waters may, therefore, require revision.

  19. Assessment of dissolved heavy metal in the Yangtze River estuary and its adjacent sea, China.

    PubMed

    An, Qiang; Wu, Yanqing; Wang, Jinhui; Li, Zhien

    2010-05-01

    The purpose of this paper is to determine the concentrations of dissolved heavy metals namely mercury (Hg), lead (Pb), cadmium (Cd), and copper (Cu) and to investigate the relationships between nutrients (nitrate-nitrogen and phosphate) and dissolved heavy metals. For this purpose, the concentrations of dissolved heavy metals were measured through 51 voyages form 1984 to 2006 in the Yangtze river estuary and its adjacent sea. Results analysis showed that dissolved heavy metals were not the main pollutants in the Yangtze river estuary, and the main source of heavy metal contamination was industrial wastewater from terrestrial pollution during the past 20 years. Heavy metal values showed significant abundance in the south branch of the Yangtze River estuary and Hangzhou Bay. In addition, Pb showed negative correlation with nutrients, while the positive correlations between Hg, Cd, and nutrients were shown. The obtained molar ratios, DeltaCd/DeltaN = 1.68 x 10(-5) and DeltaCd/DeltaP = 1.66 x 10(-4), are close to those in plankton, showing the biogeochemical behavior and process of dissolved cadmium.

  20. CONTINUOUS DISSOLVER EXTRACTOR FOR PROCESSING METAL

    DOEpatents

    Lemon, R.B.; Buckham, J.A.

    1959-02-01

    An apparatus is presented for the continuous dissolution of metal slugs in an aqueous acid and sequential continuous extraction of selected metal values from the acid solution by counter-current contact with an organic solvent. The apparatus comprises a cylindrical tank divided into upper and lower sections. Dissolution of the metal slug takes place in the lower section and the solution so produced is continuously fed to the topmost plate of the upper extraction section. An immiscible organic extractant is continuously passed by a pulsing pump into the lowermost unit of the extraction section. Suitable piping and valving permits of removing the aqueous raffinate solution from the lowermost portion of the extraction section, and simultaneous removal of organic solvent extractant containing the desired product from the uppermost portion of the extraction section.

  1. Are nanosized or dissolved metals more toxic in the environment? A meta-analysis.

    PubMed

    Notter, Dominic A; Mitrano, Denise M; Nowack, Bernd

    2014-12-01

    Recently, much has been written about the extreme urgency of elaborating the regulations for engineered nanomaterials. Such regulations are needed both from lawmakers, to protect people from potentially adverse effects, and from industry representatives, to prove that nanoproducts are produced carefully and with caution to avoid possible lawsuits. However, developing regulations has proven to be a difficult task, and an ambiguous topic where errors can easily occur. In the present study, the authors present a meta-analysis of 3 different nanomaterials (nano-Ag, nano-ZnO, and nano-CuO) in which data from ecotoxicity studies and published half-maximal effective concentration (EC50) values are compared for both the nano form and the corresponding dissolved metal. A ratio equal to 1 means that the particle is as toxic as the dissolved metal ion, whereas a lower ratio signifies that the nano form is less toxic than the dissolved metal based on total metal concentrations. The results show that for 93.8% (Ag), 100% (Cu), and 81% (Zn) of the ratios considered, the nano form is less toxic than the dissolved metal in terms of total metal concentration. Very few of the studies surveyed found a ratio of EC50 values for (dissolved/nano) that was larger than 2 (Ag: 1.1%; Cu: 0%; Zn: 2.8%). Hence, a reduction in existing metal concentration thresholds by a factor of 2 in current freshwater and soil regulations for ecotoxicity may be sufficient to protect organisms and compartments from the nano form of these metals as well.

  2. Are nanosized or dissolved metals more toxic in the environment? A meta-analysis.

    PubMed

    Notter, Dominic A; Mitrano, Denise M; Nowack, Bernd

    2014-12-01

    Recently, much has been written about the extreme urgency of elaborating the regulations for engineered nanomaterials. Such regulations are needed both from lawmakers, to protect people from potentially adverse effects, and from industry representatives, to prove that nanoproducts are produced carefully and with caution to avoid possible lawsuits. However, developing regulations has proven to be a difficult task, and an ambiguous topic where errors can easily occur. In the present study, the authors present a meta-analysis of 3 different nanomaterials (nano-Ag, nano-ZnO, and nano-CuO) in which data from ecotoxicity studies and published half-maximal effective concentration (EC50) values are compared for both the nano form and the corresponding dissolved metal. A ratio equal to 1 means that the particle is as toxic as the dissolved metal ion, whereas a lower ratio signifies that the nano form is less toxic than the dissolved metal based on total metal concentrations. The results show that for 93.8% (Ag), 100% (Cu), and 81% (Zn) of the ratios considered, the nano form is less toxic than the dissolved metal in terms of total metal concentration. Very few of the studies surveyed found a ratio of EC50 values for (dissolved/nano) that was larger than 2 (Ag: 1.1%; Cu: 0%; Zn: 2.8%). Hence, a reduction in existing metal concentration thresholds by a factor of 2 in current freshwater and soil regulations for ecotoxicity may be sufficient to protect organisms and compartments from the nano form of these metals as well. PMID:25158308

  3. Effect of dissolved organic matter on the uptake of trace metals by American oysters.

    PubMed

    Guo, L; Hunt, B J; Santschi, P H; Ray, S M

    2001-03-01

    To examine the effects of dissolved organic matter on metal bioavailability, uptake of trace metals (Cd, Co, Hg, Cr, Ag, Zn) by American oysters (Crassostrea virginica) was compared between treatments with different dissolved organic carbon (DOC) concentrations and contrasting low molecular weight (LMW, 1 kDa) and high molecular weight (HMW, 1 kDa-0.2 micron) DOC fractions, using radiotracer techniques and short-term exposure experiments. Uptake rate constants (mL g-1 h-1) of metals, in general, increased with increasing DOC concentrations, with an initial decrease at lower DOC concentrations. Oyster dry weight concentration factors (DCF, mL g-1), determined at the end of exposure experiments (8 h), also increased for Cd, Co, Cr, Ag, and Zn, but decreased for Hg, with increasing DOC concentrations. Changes of metal uptake rate constants and DCF values with DOC concentration suggest that metal uptake pathways by American oysters vary from predominantly uptake (by diffusion of neutral) of free ionic, inorganically complexed, and LMW organic ligand complexed metals at very low DOC concentration to direct ingestion and digestion of HMW or colloidally complexed metals at higher DOC concentrations. Measured partition coefficients (Kc) between dissolved and colloidal phases were comparable between metals, ranging from 10(5.12) to 10(5.75) mL g-1. However, DCF values and uptake rate constants differed considerably between metals, with the highest DCF values and uptake rate constants found for B-type metals, e.g., Ag, Hg, Zn, and Cd, and the lowest ones for several intermediate-type metals (e.g., Co, Cr). Metal types and thus the interaction of metals with organic ligands, such as strong complexation of B-type metals with S-containing organic ligands, may play an important role in the bioavailability and toxicity of metals to aquatic organisms. Differences in metal uptake in contrasting LMW and HMW DOC treatments suggest a generally depressed bioavailability of colloidally

  4. Measurement of Relative Dissolved Gas Concentrations Using Underwater Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Bell, R. J.; Toler, S.; van Amerom, F. H.; Wenner, P.; Hall, M.; Edkins, J.; Gassig, S.; Short, R.; Byrne, R.

    2004-12-01

    The deployment of underwater mass spectrometer (UMS) systems in marine and lacustrine environments has provided chemical data of exceptional temporal and spatial resolution. UMS instruments operate moored, tethered, remotely, or autonomously, allowing users to customize deployments to suit a wide variety of situations. The ability to collect and analyze real-time data enables prompt, intelligent sampling decisions based on observed analyte distributions. UMS systems can simultaneously detect a wide variety of analytes generated by biological, chemical, physical, geothermal and anthropogenic activities. A polydimethylsiloxane (PDMS) membrane separates the sample-stream from the spectrometer's vacuum chamber. This membrane is selective against water and charged species, yet highly permeable to volatile organic compounds (VOC) and simple gases. Current detection limits for dissolved gases and VOCs are on the order of ppm and ppb respectively. Semi-quantitative proof-of-concept applications have included horizontal mapping of gas gradients, characterization of geothermal vent water, and observation of dissolved gas profiles. Horizontal gradients in dissolved gas concentrations were determined in Lake Maggiore, St Petersburg, Florida. The UMS was positioned on a remotely-guided surface vehicle, and real-time gas concentration data were transmitted to shore via wireless ethernet. Real-time observations allowed intensive sampling of areas with strong gas gradients. Oxygen and CO2 exhibited patchy distributions and their concentrations varied inversely, presumably in response to biological activity. The UMS signal for methane depended on the instrument's proximity to organic rich sediments. Geothermal vent water was characterized while the UMS was deployed in Yellowstone Lake, Wyoming, on a tethered Eastern Oceanics remotely operated vehicle (ROV). Observations of dissolved vent-gas compositions were obtained to depths of 30m. Distinct differences in dissolved vent

  5. Removal of dissolved heavy metals and radionuclides by microbial spores

    SciTech Connect

    Revis, N.W.; Hadden, C.T.; Edenborn, H.

    1997-11-01

    Microbial systems have been shown to remove specific heavy metals from contaminated aqueous waste to levels acceptable to EPA for environmental release. However, systems capable of removing a variety of heavy metals from aqueous waste to environmentally acceptable levels remain to be reported. The present studies were performed to determine the specificity of spores of the bacterium Bacillus megaterium for the adsorption of dissolved metals and radionuclides from aqueous waste. The spores effectively adsorbed eight heavy metals from a prepared metal mix and from a plating rinse waste to EPA acceptable levels for waste water. These results suggest that spores have multiple binding sites for the adsorption of heavy metals. Spores were also effective in adsorbing the radionuclides {sup 85}strontium and {sup 197}cesium. The presence of multiple sites in spores for the adsorption of heavy metals and radionuclides makes this biosorbent a good candidate for the treatment of aqueous wastes associated with the plating and nuclear industries. 17 refs., 4 tabs.

  6. Dissolved oxygen concentration in culture medium: assumptions and pitfalls.

    PubMed

    Newby, D; Marks, L; Lyall, F

    2005-04-01

    Oxygen is a key factor in the regulation of cytotrophoblast differentiation, proliferation and invasion in early pregnancy. Abnormalities in oxygen concentration have also been linked to a number of pregnancy disorders. Cell culture models have been used to study the effect of oxygen on cytotrophoblast behaviour in vitro, however, there is often little or no validation of oxygen levels in these cell culture systems. In this study, dissolved oxygen levels in culture medium maintained in standard culture conditions (18% O(2)) measured 18%. On transfer to a low oxygen environment (2% O(2)), oxygen levels decreased to 6-8% after 4h and reached 2% only after 24h in culture. Culture medium pre-gassed with nitrogen to remove dissolved oxygen quickly absorbed oxygen when exposed to ambient air during dispensing and required further incubation in a 2% oxygen environment before dissolved oxygen levels equilibrated to 2%. Thus, cultured cells placed in a low oxygen environment would be exposed to varying levels of oxygen before the desired level of oxygen exposure is reached. This study highlights the importance of validation of oxygen levels and potential problems associated with in vitro studies on the regulatory effects of oxygen.

  7. Diel Variation in Dissolved Trace-Element Concentrations in Streams Draining Abandoned Mine Lands

    NASA Astrophysics Data System (ADS)

    Nimick, D. A.

    2001-12-01

    Substantial diel (24-hour) variations in dissolved trace-element concentrations have been measured during 20 different hourly sampling episodes at 14 sites on 9 streams draining historical mining areas in Montana. At all sites, concentrations of dissolved (0.1-um filtration) Cd, Mn, and Zn increased during the night, reaching maximum values shortly after sunrise; concentrations then decreased to minimum values during mid to late afternoon. Dissolved As concentrations exhibited the opposite temporal pattern, while variations in dissolved Cu concentrations were small and displayed no consistent pattern. Most sites were sampled during low-flow conditions, but two sampling episodes during snowmelt runoff at one site showed that similar diel variations occur during high flow. All sites had near neutral to slightly alkaline pH. Diel variations did not occur in two other acidic (pH of 4.0-5.5) streams. The magnitude of change during diel concentration cycles varied for each trace element. Zn and Mn concentrations exhibited the largest variation, with maximum concentrations ranging from 120 to 590 percent higher than minimum concentrations. Cd maximum concentrations were about 200 percent higher than minimum concentrations, whereas As maximum concentrations were 115 to 155 percent higher. Diel trace-element cycles appear to be independent of concentration magnitude, occurring over a wide range of concentrations: 5-44 ug/L As; 1-7 ug/L Cd, 18-609 ug/L Mn, and 2-4,940 ug/L Zn. Several chemical, physical, and biological processes potentially can explain diel dissolved-trace-element cycles. Temperature- and pH-dependent sorption reactions occurring on streambed material in the channel and hyporheic zone are considered the most likely mechanisms because of the strong similarity in the symmetry and magnitude of temporal plots of concentration, temperature, and pH. In addition, sorption processes can explain the simultaneous decrease in divalent metal concentrations during the

  8. Dissolved and particulate metals dynamics in a human impacted estuary from the SW Atlantic

    NASA Astrophysics Data System (ADS)

    La Colla, Noelia S.; Negrin, Vanesa L.; Marcovecchio, Jorge E.; Botté, Sandra E.

    2015-12-01

    In order to evaluate metal behavior in urban stressed estuaries, the distribution of major elements (Fe and Mn) and trace elements (Cd and Cu) between suspended particulate matter (SPM) and subsuperficial seawater in the Bahía Blanca Estuary, Argentina, was studied. Four different impacted areas were selected to study the spatial and temporal distribution of these metals in an estuary in continuous industrial development and where an environmental law was implemented to supervise industrial discharges in waters. Sampling was performed within intertidal areas. Physicochemical conditions usually influence the partitioning of metals between the dissolved and particulate fraction thus, salinity, pH, turbidity, temperature and dissolved oxygen were also measured. Dissolved metals were analyzed with atomic absorption spectrophotometry (AAS) and the particulate fraction with inductively coupled plasma optical emission spectrometry (ICP OES). Metals concentration ranges, within the dissolved fraction (μg/L), were from below the method detection limit for all the elements to 4.7 in the case of Cd, 6.0 for Cu and 62 for Fe. Minimum and maximum values in the particulate fraction (μg/g, d.w.) were from below the method detection limit to 11 for Cd; from 24 to 220 for Cu and from 630 to 1500 for Mn. For Fe, concentrations ranged from 2.2 to 9.6 (%). The general order of the dissolved/particulate partition coefficients (Log10Kds) for the studied metals, considering mean values, were: Fe (7.0) > Cu (4.2) > Cd (3.3). The metals values as well as the physicochemical parameters showed temporal variations and many correlations were found among them. Log10Kd Fe values were the highest, highlighting its strong affinity for particles. Metals concentrations were sometimes higher than those from other polluted areas as well as from previous studies from the same estuary, which highlights the potential impact of these elements in the study area. The concentrations of particulate metals

  9. Bead and Process for Removing Dissolved Metal Contaminants

    SciTech Connect

    Summers, Bobby L., Jr.; Bennett, Karen L.; Foster, Scott A.

    2005-01-18

    A bead is provided which comprises or consists essentially of activated carbon immobilized by crosslinked poly (carboxylic acid) binder, sodium silicate binder, or polyamine binder. The bead is effective to remove metal and other ionic contaminants from dilute aqueous solutions. A method of making metal-ion sorbing beads is provided, comprising combining activated carbon, and binder solution (preferably in a pin mixer where it is whipped), forming wet beads, and heating and drying the beads. The binder solution is preferably poly(acrylic acid) and glycerol dissolved in water and the wet beads formed from such binder solution are preferably heated and crosslinked in a convection oven.

  10. Measuring Hydrogen Concentrations in Metals

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1985-01-01

    Commercial corrosion-measurement system adapted to electrochemical determination of hydrogen concentrations in metals. New technique based on diffusion of hydrogen through foil specimen of metal. In sample holder, hydrogen produced on one side of foil, either by corrosion reaction or by cathodic current. Hydrogen diffused through foil removed on other side by constant anode potential, which leads to oxidation of hydrogen to water. Anode current is measure of concentration of hydrogen diffusing through foil. System used to study hydrogen uptake, hydrogen elimination by baking, effect of heat treatment, and effect of electroplating on high-strength steels.

  11. Corals concentrate dissolved inorganic carbon to facilitate calcification.

    PubMed

    Allison, Nicola; Cohen, Itay; Finch, Adrian A; Erez, Jonathan; Tudhope, Alexander W

    2014-12-22

    The sources of dissolved inorganic carbon (DIC) used to produce scleractinian coral skeletons are not understood. Yet this knowledge is essential for understanding coral biomineralization and assessing the potential impacts of ocean acidification on coral reefs. Here we use skeletal boron geochemistry to reconstruct the DIC chemistry of the fluid used for coral calcification. We show that corals concentrate DIC at the calcification site substantially above seawater values and that bicarbonate contributes a significant amount of the DIC pool used to build the skeleton. Corals actively increase the pH of the calcification fluid, decreasing the proportion of DIC present as CO2 and creating a diffusion gradient favouring the transport of molecular CO2 from the overlying coral tissue into the calcification site. Coupling the increases in calcification fluid pH and [DIC] yields high calcification fluid [CO3(2-)] and induces high aragonite saturation states, favourable to the precipitation of the skeleton.

  12. Estuarine modification of dissolved and particulate trace metals in major rivers of East-Hainan, China

    NASA Astrophysics Data System (ADS)

    Fu, Jun; Tang, Xiao-Liang; Zhang, Jing; Balzer, Wolfgang

    2013-04-01

    Dissolved and particulate cadmium, copper, iron, lead, cobalt and nickel were analyzed in surface waters of the Wanquan River estuary and the Wenchang/Wenjiao River estuary in East-Hainan Island during the dry season (December 2006) and two wet seasons (August 2007 and July/August 2008). A major difference to other Chinese rivers was the very low concentration of suspended particles in these tropical Hainan estuaries. In the dissolved phase, a positive deviation from the theoretical dilution line was observed for Cd during different expeditions. Dissolved Cu and Ni essentially behaved conservatively, while Fe, Pb and partly also Co correlated in their negative deviation from simple mixing. Strong seasonal variability was observed only for dissolved Fe, Pb and Cd: sorption by the much higher loading with suspended particles during the dry season lead to a strong lowering of dissolved Fe and Pb, while the opposite was observed for dissolved Cd. In both estuaries all six metals in particulate form showed almost constant values with a tendency for slight decreases along the salinity profile. The normalization to particulate Al revealed some specific particle properties during the different expeditions. The dynamics of Fe chemistry dominated the distribution of Pb in all forms. The distribution coefficients KD showed a general decrease in the order Fe>Pb>Co>Ni>Cu≈Cd. There was no "particle concentration effect"; rather the KD's of Fe and Pb exhibited slightly positive correlations with the suspended particle loadings. Elevated concentrations levels in the Wenchang/Wenjiao river estuary, especially during the wet season 2008, were ascribed to diffuse inputs from aquaculture ponds which girdle the upper estuary. In comparison to major Chinese rivers, the tropical Hainan estuaries (S>0) showed similar levels for Cd, Cu, Pb, Co and Ni in particles and solution, while Fe was enriched in both matrices. On a global scale, neither in the Wanquan river estuary nor in the

  13. Understanding Dissolved and Colloidal Metal Transport and Transformation - Pathways for Aquatic Toxicity

    NASA Astrophysics Data System (ADS)

    Kimball, B. A.; Besser, J. M.

    2004-05-01

    Hundreds of miles of streams in the western United States are affected by the release of metals from weathering of mineralized bedrock and mine wastes. In many cases, historical mining has accelerated these weathering processes and increased concentrations of metals in affected streams. Copper and zinc are two metals that affect aquatic health in such streams. Aquatic toxicity from copper and zinc is thought to be related principally to their dissolved concentrations. But there are alternative pathways that may lead to toxicity. Movement of many metals associated with mine drainage is affected by iron colloidal solids. The initial precipitation of iron hydroxides results in nanometer-sized colloids that subsequently aggregate to form a continuum of particle sizes from about one nanometer to greater than one micrometer. This behavior makes the popular or legal definition of dissolved metals at 0.45 micrometers meaningless in streams affected by mine drainage. Ultrafiltration, using tangential-flow across 10,000-Dalton membranes, provides a means to understand dissolved and colloidal metal concentrations. When ultrafiltration is combined with methods to determine mass loading, it is possible to quantify sources and chemical reactions affecting metals. For example, results from a mass-loading study in Mineral Creek, Colorado, indicate that copper and zinc are contributed to the stream from both mined and unmined sources. As the pH of Mineral Creek changes in response to both neutral and acidic inflows, copper was repeatedly transferred between dissolved and colloidal phases through sorption reactions. When the colloidal phase was dominant, the total load of copper consistently decreased because the colloids are entrained by algae on cobbles and strained by the streambed during hyporheic exchange. Zinc load also decreased during transport, but this was a result of the physical process of water exchange with the hyporheic zone, and not a result of colloidal

  14. METAL-COLLOID PARTITIONING IN ARTIFICIAL INTERSTITIAL WATERS OF MARINE SEDIMENTS: INFLUENCES OF SALINITY, PH AND COLLOIDAL ORGANIC CARBON CONCENTRATION

    EPA Science Inventory

    For decades, heavy metals have been deposited into marine sediments as a result of anthropogenic activities. Depending on their bioavailability, these metals may represent a risk to benthic organisms. Dissolved interstitial water metal concentrations have been shown to be better ...

  15. Historical backcasting of metal concentrations in the Chattahoochee River, Georgia: Population growth and environmental policy

    USGS Publications Warehouse

    Neumann, K.; Lyons, W.B.; Graham, E.Y.; Callender, E.

    2005-01-01

    The impact of increasing urbanization on the quality of a river system has been investigated by examining the current concentration of trace metals in the Chattahoochee River south of Atlanta, GA, and comparing these to previously published historical sediment data from reservoirs along the river. The lack of historical data for dissolved metal concentrations prior to ???1980 requires an approach using these historic metal data from sediment cores. Core data are combined with current suspended load and dissolved metal data to "backcast" dissolved metal concentrations in the metro-Atlanta portion of the Chattahoochee River. The data suggest that the per capita input of dissolved trace metals have actually decreased since the 1920s, but anthropogenic inputs of metal are still a substantial water quality issue. ?? 2005 Elsevier Ltd. All rights reserved.

  16. Atmospheric input of dissolved and particulate metals to the northwestern Mediterranean

    NASA Astrophysics Data System (ADS)

    Guieu, C.; Chester, R.; Nimmo, M.; Martin, J.-M.; Guerzoni, S.; Nicolas, E.; Mateu, J.; Keyse, S.

    Concentrations of trace elements (Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were determined for aerosols, dry deposition, precipitation and total deposition samples collected from five stations on islands and in the coastal zone of the northwestern Mediterranean. Average concentrations of metals are very homogeneous over the sampled area, in particular at the three coastal sites. Cd and Pb are almost entirely of man-made origin, even in Saharan aerosols. For the other metals, the non-crustal fraction is lower in Saharan aerosols than in European aerosols, but there is an important man-made component in the Saharan aerosol, even for metals such as Fe and Cr. This confirms the results of Chester et al. (1992) who concluded that Mediterranean aerosols have a European background upon which are superimposed Saharan inputs. Dry deposition represents an important fraction of the total deposition. Partitioning of total atmospheric deposition between the dissolved and the particulate phases shows that Al, Fe and Cr originating from the atmosphere are mostly in a particulate form in the surface waters. For the other metals studied, the dissolved fraction represents more than 30% of the total input, and for Cd it is almost 100%. Extrapolation shows that more than 50% of the dissolved metals input to the northwestern Mediterranean originates from the atmosphere. Atmospheric input entirely dominates the total external input of pollution-derived elements, such as Pb and Cd. The dissolved input of atmospheric origin is also very important (> 80%) for elements of terrigeneous origin such as A1.

  17. Measurement of Solubility of Metallic Lithium Dissolved in Molten LiCl-Li2O

    NASA Astrophysics Data System (ADS)

    Burak, Adam J.; Simpson, Michael F.

    2016-07-01

    The solubility of lithium metal in molten LiCl-Li2O mixtures has been measured at various concentrations of Li2O ranging from 0 wt.% to 2.7 wt.% at a temperature of approximately 670-680°C. After contacting molten lithium with molten LiCl-Li2O for several hours to achieve equilibrium saturation, samples were taken by freezing the salt onto a room-temperature steel rod and dissolving in water for analysis. Both volume of hydrogen gas generated and volume of titrated HCl were measured to investigate two different approaches to calculating the lithium concentration. There appeared to be no effect of Li2O concentration on the Li solubility in the salt. But the results vary between different methods of deducing the amount of dissolved Li. The H2 collection method is recommended, but care must be taken to ensure all of the H2 has been included.

  18. Measurement of Solubility of Metallic Lithium Dissolved in Molten LiCl-Li2O

    NASA Astrophysics Data System (ADS)

    Burak, Adam J.; Simpson, Michael F.

    2016-10-01

    The solubility of lithium metal in molten LiCl-Li2O mixtures has been measured at various concentrations of Li2O ranging from 0 wt.% to 2.7 wt.% at a temperature of approximately 670-680°C. After contacting molten lithium with molten LiCl-Li2O for several hours to achieve equilibrium saturation, samples were taken by freezing the salt onto a room-temperature steel rod and dissolving in water for analysis. Both volume of hydrogen gas generated and volume of titrated HCl were measured to investigate two different approaches to calculating the lithium concentration. There appeared to be no effect of Li2O concentration on the Li solubility in the salt. But the results vary between different methods of deducing the amount of dissolved Li. The H2 collection method is recommended, but care must be taken to ensure all of the H2 has been included.

  19. Metal Ion Speciation and Dissolved Organic Matter Composition in Soil Solutions

    NASA Astrophysics Data System (ADS)

    Benedetti, M. F.; Ren, Z. L.; Bravin, M.; Tella, M.; Dai, J.

    2014-12-01

    Knowledge of the speciation of heavy metals and the role of dissolved organic matter (DOM) in soil solution is a key to understand metal mobility and ecotoxicity. In this study, soil column-Donnan membrane technique (SC-DMT) was used to measure metal speciation of Cd, Cu, Ni, Pb, and Zn in eighteen soil solutions, covering a wide range of metal sources and concentrations. DOM composition in these soil solutions was also determined. Our results show that in soil solution Pb and Cu are dominant in complex form, whereas Cd, Ni and Zn mainly exist as free ions; for the whole range of soil solutions, only 26.2% of DOM is reactive and consists mainly of fulvic acid (FA). The metal speciation measured by SC-DMT was compared to the predicted ones obtained via the NICA-Donnan model using the measured FA concentrations. The free ion concentrations predicted by speciation modelling were in good agreement with the measurements. Diffusive gradients in thin-films gels (DGT) were also performed to quantify the labile metal species in the fluxes from solid phase to solution in fourteen soils. The concentrations of metal species detected by DGT were compared with the free ion concentrations measured by DMT and the maximum concentrations calculated based on the predicted metal speciation in SC-DMT soil solutions. It is concluded that both inorganic species and a fraction of FA bound species account for the amount of labile metals measured by DGT, consistent with the dynamic features of this technique. The comparisons between measurements using analytical techniques and mechanistic model predictions provided mutual validation in their performance. Moreover, we show that to make accurate modelling of metal speciation in soil solutions, the knowledge of DOM composition is the crucial information, especially for Cu; like in previous studies the modelling of Pb speciation is not optimal and an updated of Pb generic binding parameters is required to reduce model prediction uncertainties.

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

    PubMed

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

    2014-08-01

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

  1. HEAVY METAL CONCENTRATION OF SOIL IN THE REGIONAL CITY PLAYGROUNDS

    NASA Astrophysics Data System (ADS)

    Nakagawa, Kei; Tsuzuki, Megumi; Asakura, Hiroshi

    It seems important to examine heavy metal concentration in playgrounds, to evaluate potential risk for heavy metal ingestion by children. In this study, heavy metal concentrations of soil samples in 40 playgrounds in K-city were investigated by the voltammetric method. To visualize heavy metal concentration distribution in playgrounds, free GIS software MANDARA was used. According to the comparison between the 1 N HCl dissolved concentration and the PTWI (Provisional Tolerable Weekly Intake), playgrounds in K-city may not have intake risk of lead. Even if the possibility of the risk was very low, there are differences of the intensities. As for the specific playground where concentration is high, investigating continuously may be desirable hereafter.

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

    USGS Publications Warehouse

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

    2010-01-01

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

  3. Dissolved sulfide in groundwater with elevated arsenic concentrations at Winthrop, Maine

    NASA Astrophysics Data System (ADS)

    He, Y.; Zheng, Y.; Zheng, Y.; Locke, D. C.; Simpson, J. H.; Stute, M.

    2001-12-01

    Although sulfur is a biogeochemically significant element because of its strong influence on and response to redox conditions, there are relatively few reliable data sets of trace levels of dissolved sulfide \\(less than1 uM \\) in groundwaters This circumstance results from the relatively high detection limit \\(˜ 1uM \\) of methylene blue colorimetry and the general lack of sensitive methods for field analysis. We were motivated to investigate trace levels of dissolved sulfide because highly insoluble sulfide precipitates of many elements such as As and Fe represent important removal pathways for these metals in reducing groundwaters. Using differential pulse cathodic stripping voltammetry \\(DPCSV\\) capable of detecting 4 nM of dissolved sulfide, we observed that at a site in Winthrop, Maine, groundwater sulfide concentrations ranged from less than 4 nM to ˜ 2000 nM for about a dozen multi-level observation wells under a landfill cap and less than 4 nM to ˜ 7300 nM from several nearby monitoring wells outside the landfill. Sulfide concentrations generally increased when oxygen reduction potential \\(ORP\\) values became more negative. Determination of sulfide should be carried out within 1 hr of sample collection. Samples taken by two methods, \\(1\\) PTFE syringes with luer-lock valves and \\(2\\) BOD bottles show a rapid decline of sulfide following sampling, with up to 90% and 60% losses, respectively, after 24 hrs of storage at 4 ° C. Despite the three orders of magnitude range of dissolved sulfide, arsenic and iron concentrations were all elevated in observational wells installed in a roughly 25 m by 20 m rectangle under the landfill cap, suggesting that As remains mobile under mildly sulfate-reducing conditions. In one well outside of the landfill area, with extremely negative ORP \\(-321 mV\\) and ˜ 7300 nM of dissolved sulfide, groundwater was very low in dissolved As, Fe, and sulfate, suggesting that precipitation of arsenopyrite could be a

  4. Nanomaterials in Biosolids Inhibit Nodulation, Shift Microbial Community Composition, and Result in Increased Metal Uptake Relative to Bulk/Dissolved Metals.

    PubMed

    Judy, Jonathan D; McNear, David H; Chen, Chun; Lewis, Ricky W; Tsyusko, Olga V; Bertsch, Paul M; Rao, William; Stegemeier, John; Lowry, Gregory V; McGrath, Steve P; Durenkamp, Mark; Unrine, Jason M

    2015-07-21

    We examined the effects of amending soil with biosolids produced from a pilot-scale wastewater treatment plant containing a mixture of metal-based engineered nanomaterials (ENMs) on the growth of Medicago truncatula, its symbiosis with Sinorhizobium meliloti, and on soil microbial community structure. Treatments consisted of soils amended with biosolids generated with (1) Ag, ZnO, and TiO2 ENMs introduced into the influent wastewater (ENM biosolids), (2) AgNO3, Zn(SO4)2, and micron-sized TiO2 (dissolved/bulk metal biosolids) introduced into the influent wastewater stream, or (3) no metal added to influent wastewater (control). Soils were amended with biosolids to simulate 20 years of metal loading, which resulted in nominal metal concentrations of 1450, 100, and 2400 mg kg(-1) of Zn, Ag, and Ti, respectively, in the dissolved/bulk and ENM treatments. Tissue Zn concentrations were significantly higher in the plants grown in the ENM treatment (182 mg kg(-1)) compared to those from the bulk treatment (103 mg kg(-1)). Large reductions in nodulation frequency, plant growth, and significant shifts in soil microbial community composition were found for the ENM treatment compared to the bulk/dissolved metal treatment. These results suggest differences in metal bioavailability and toxicity between ENMs and bulk/dissolved metals at concentrations relevant to regulatory limits.

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

  6. Distribution of dissolved trace metals around the Sacrificos coral reef island, in the southwestern Gulf of Mexico.

    PubMed

    Rosales-Hoz, L; Carranza-Edwards, A; Sanvicente-Añorve, L; Alatorre-Mendieta, M A; Rivera-Ramirez, F

    2009-11-01

    A reef system in the southwestern Gulf of Mexico is affected by anthropogenic activities, sourced by urban, fluvial, and sewage waters. Dissolved metals have higher concentrations during the rainy season. V and Pb, were derived from an industrial source and transported to the study area by rain water. On the other hand, Jamapa River is the main source for Cu and Ni, which carries dissolved elements from adjacent volcanic rocks. Principal Component Analysis shows a common source for dissolved nitrogen, phosphates, TOC, and suspended matters probably derived from a sewage treatment plant, which is situated near to the study area.

  7. Measuring freely dissolved water concentrations of PCBs using LDPE passive samplers and performance reference compounds (PRCs)

    EPA Science Inventory

    Low-Density polyethylene (LDPE) sheets are often used as passive samplers for aquatic environmental monitoring to measure the dissolved concentrations of hydrophobic organic contaminants (HOCs). These concentrations are then used to evaluate the potential for ecological and human...

  8. Seasonal variation and sources of dissolved trace metals in Maó Harbour, Minorca Island.

    PubMed

    Martínez-Soto, Marly C; Tovar-Sánchez, Antonio; Sánchez-Quiles, David; Rodellas, Valentí; Garcia-Orellana, Jordi; Basterretxea, Gotzon

    2016-09-15

    The environmental conditions of semi-enclosed coastal water-bodies are directly related to the catchment, human activities, and oceanographic setting in which they are located. As a result of low tidal forcing, and generally weak currents, waters in Mediterranean harbours are poorly renewed, leading to quality deterioration. Here, we characterise the seasonal variation of trace metals (i.e. Co, Cd, Cu, Fe, Mo, Ni, Pb, and Zn) in surface waters, and trace metal content in sediments from Maó Harbour, a semi-enclosed coastal ecosystem in the NW Mediterranean Sea. Our results show that most of the dissolved trace metals in the waters of Maó Harbour exhibit a marked inner-outer concentration gradient, suggesting a permanent input into the inner part of the harbour. In general, metal concentrations in the waters of Maó Harbour are higher than those in offshore waters. Concentration of Cu (21±8nM), Fe (9.2±3.2nM) and Pb (1.3±0.4nM) are particularly high when compared with other coastal areas of the Mediterranean Sea. The concentration of some metals such as Cu and Zn increases during summertime, when the human population and boat traffic increase during the tourism season, and when resuspension from the metal enriched sediments is higher. The evaluation of the metal sources in the harbour reveals that, compared with other putative sources such as runoff, aerosol deposition and fresh groundwater discharges, contaminated sediments are the main source of the metals found in the water column, most likely through vessel-driven resuspension events. This study contributes to the understanding of the processes that control the occurrence and distribution of trace metals in Maó Harbour, thus aiding in the effective management of the harbour, and enhancing the overall quality of the seawater ecosystem. PMID:27163484

  9. Linking dissolved organic matter composition to metal bioavailability in agricultural soils: effect of anionic surfactants

    NASA Astrophysics Data System (ADS)

    Hernandez-Soriano, M. C.; Jimenez-Lopez, J. C.

    2015-04-01

    The bioavailability of metals in soil is only partially explained by their partition among the solid and aqueous phase and is more related to the characterization of their speciation in the soil solution. The organic ligands in solution that largely determine metal speciation involve complex mixtures and the characterization of fluorescence components of dissolved organic matter (DOM) can identify pools of molecules that participate in metal speciation, this being essential for risk assessment. The bioavailability of Cd, Cu, Pb and Zn in three agricultural soils was examined in the laboratory to recreate irrigation with greywater enriched in anionic surfactants (Aerosol 22 and Biopower). Field capacity and saturation regimes were considered for this study. Irrigation with aqueous solutions of the anionic surfactants increased total DOM concentrations and metals in the soil solution (Pb > Cu > Zn > Cd). Significant correlation (p < 0.05) between the readily available pool of metals with the concentration of DOM was determined for Cu (r = 0.67), Pb (r = 0.82) and Zn (r = 0.68). However, speciation analysis performed with the software WHAM indicated that mobilisation of DOM and metals into the soluble phase resulted in a low concentration of free ion activities and promoted the formation of metal-organo complexes. The characterization of fluorescence components revealed that DOM in soil solution from soils irrigated with Aerosol 22 was enriched in a reduced quinone-like and a humic-like component. Besides, fluorescence quenching provided further evidence of metal complexation with organic ligands in solution. Hence, metal mobilization in soil irrigated with surfactant enriched greywater occurs with solubilisation of high affinity organic ligands, which substantially decreases the potential risk of metal toxicity.

  10. Stabilization of dissolved trace metals at hydrothermal vent sites: Impact on their marine biogeochemical cycles

    NASA Astrophysics Data System (ADS)

    Sander, Sylvia G.; Powell, Zach D.; Koschinsky, Andrea; Kuzmanovski, Stefan; Kleint, Charlotte

    2014-05-01

    Hydrothermal vents have long been neglected as a significant source of several bioactive trace metals as it was assumed that elements such as Fe, Mn, and Cu etc., precipitate in extensor forming poly-metallic sulfide and oxy-hydroxy sediments in the relative vicinity of the emanation site. However, recently this paradigm has been reviewed since the stabilization of dissolved Fe and Cu from hydrothermal vents was observed [1, 2] and increased concentrations of trace metals can be traced from their hydrothermal source thousands of kilometres through the ocean basins [3]. Furthermore several independent modelling attempts have shown that not only a stabilization of dissolved hydrothermal Fe and Cu is possible [4] but also that hydrothermalism must be a significant source of Fe to be able to balance the Fe-biogeochemical cycle [5]. Here we present new data that gives further evidence of the presence of copper stabilising organic and inorganic compounds in samples characterized by hydrothermal input. We can show that there are systematic differences in copper-complexing ligands at different vent sites such as 5°S on the Mid Atlantic Ridge, Brother Volcano on the Kermadec Arc, and some shallow hydrothermal CO2 seeps in the Bay of Plenty, New Zealand and the Mediterranean Sea. Quantitative and qualitative voltammetric data convincingly indicates that inorganic sulphur and organic thiols form the majority of the strong copper-complexing ligand pool in many of these hydrothermal samples. On average, the high temperature vents had a significantly higher copper binding capacity than the diffuse vents due to higher inorganic sulphur species concentrations. References: [1] Sander, S. G., et al. 2007. Organic complexation of copper in deep-sea hydrothermal vent systems. Environmental Chemistry 4: 81-89 [2] Bennett, S. A., et al. 2008. The distribution and stabilisation of dissolved Fe in deep-sea hydrothermal plumes. Earth and Planetary Science Letters 270: 157-167. [3] Wu J

  11. DISSOLVED ORGANIC CARBON (DOC) CONCENTRATIONS IN SMALL STREAMS OF THE GEORGIA PIEDMONT

    EPA Science Inventory

    Dissolved organic matter (DOM) supports microbial activity and contributes to transport of N and P in streams. We have studied the impact of land uses on dissolved organic carbon (DOC) concentrations in 17 Georgia Piedmont headwater streams since January 2001. We classified the w...

  12. Metal complexation properties of freshwater dissolved organic matter are explained by its aromaticity and by anthropogenic ligands.

    PubMed

    Baken, Stijn; Degryse, Fien; Verheyen, Liesbeth; Merckx, Roel; Smolders, Erik

    2011-04-01

    Dissolved organic matter (DOM) in surface waters affects the fate and environmental effects of trace metals. We measured variability in the Cd, Cu, Ni, and Zn affinity of 23 DOM samples isolated by reverse osmosis from freshwaters in natural, agricultural, and urban areas. Affinities at uniform pH and ionic composition were assayed at low, environmentally relevant free Cd, Cu, Ni, and Zn activities. The C-normalized metal binding of DOM varied 4-fold (Cu) or about 10-fold (Cd, Ni, Zn) among samples. The dissolved organic carbon concentration ranged only 9-fold in the waters, illustrating that DOM quality is an equally important parameter for metal complexation as DOM quantity. The UV-absorbance of DOM explained metal affinity only for waters receiving few urban inputs, indicating that in those waters, aromatic humic substances are the dominant metal chelators. Larger metal affinities were found for DOM from waters with urban inputs. Aminopolycarboxylate ligands (mainly EDTA) were detected at concentrations up to 0.14 μM and partly explained the larger metal affinity. Nickel concentrations in these surface waters are strongly related to EDTA concentrations (R2=0.96) and this is underpinned by speciation calculations. It is concluded that metal complexation in waters with anthropogenic discharges is larger than that estimated with models that only take into account binding on humic substances.

  13. Metal and phytochelatin content in phytoplankton from freshwater lakes with different metal concentrations

    SciTech Connect

    Knauer, K.; Xue, H.B.; Sigg, L.; Ahner, B.

    1998-12-01

    The trace metal (Cu, Zn, Cd, Mn) and phytochelatin (an intracellular chelator for metal ions) cellular content were determined in phytoplankton samples originating from four lakes. The lakes differ in their metal concentrations and in other conditions (pH, trophic state, organic matter). Total and intracellular contents of Cu and Cd were related to the experimentally determined free metal ion concentration and the total and intracellular content of Mn to the dissolved Mn. The intracellular Zn content was tightly regulated over a broad range of [Zn{sup 2+}]. Phytochelatin concentrations were measurable in phytoplankton communities from three of the lakes, in spite of low levels of free Cu, Zn, and Cd ion concentrations. Culture experiments showed that the concentration of intracellular phytochelatin in Scendesmus subspicatus and in a natural algal community increased upon addition of copper in a similar concentration range as in the lakes. Phytochelatin concentrations were below detection in the phytoplankton collected from the highly contaminated Lake Orta, perhaps suggesting that this algal community has adapted in some other way to high metal concentrations. Although the authors only sampled a few lakes, the lack of any clear relationship between phytochelatin and metal concentrations calls into question the feasibility of using phytochelatins as a bioindicator of metal exposure in lakes.

  14. SITE demonstration of the Dynaphore/Forager Sponge technology to remove dissolved metals from contaminated groundwater

    SciTech Connect

    Esposito, C.R.; Vaccaro, G.

    1995-10-01

    A Superfund Innovative Technology Evaluation (SITE) demonstration was conducted of the Dynaphore/Forager Sponge technology during the week of April 3, 1994 at the N.L. Industries Superfund Site in Pedricktown, New Jersey. The Forager Sponge is an open-celled cellulose sponge incorporating an amine-containing chelating polymer that selectively absorbs dissolved heavy metals in both cationic and anionic states. This technology is a volume reduction technology in which heavy metal contaminants from an aqueous medium are concentrated into a smaller volume for facilitated disposal. The developer states that the technology can be used to remove heavy metals from a wide variety of aqueous media, such as groundwater, surface waters and process waters. The sponge matrix can be directly disposed, or regenerated with chemical solutions. For this demonstration the sponge was set up as a mobile pump-and-treat system which treated groundwater contaminated with heavy metals. The demonstration focused on the system`s ability to remove lead, cadmium, chromium and copper from the contaminated groundwater over a continuous 72-hour test. The removal of heavy metals proceeded in the presence of significantly higher concentrations of innocuous cations such as calcium, magnesium, sodium, potassium and aluminum.

  15. Potentiating toxicological interaction of single-walled carbon nanotubes with dissolved metals.

    PubMed

    Al-Shaeri, Majed; Ahmed, Dina; McCluskey, Fiona; Turner, Gavin; Paterson, Lynn; Dyrynda, Elisabeth A; Hartl, Mark G J

    2013-12-01

    The present study explored the ecotoxicology of single-walled carbon nanotubes (SWCNTs) and their likely interaction with dissolved metals, with a focus on the effect of in vivo exposure in marine mussels. Any nano-scale effects were negated by the tendency of uncoated SWCNTs to agglomerate in water, particularly with high ionic strength as is the case in estuarine and full-strength seawater. However, SWCNTs, in combination with natural organic matter, remained suspended in seawater for long enough to become available to filter-feeding mussels, leading to their concentration on and increased contact with gill epithelia during exposure. For the first time, the authors describe a potentiating toxicological effect, expressed as DNA strand breaks obtained using the comet assay, on divalent metals afforded by negatively charged SWCNT agglomerates in seawater at concentrations as low as 5 µg L⁻¹. This is supported by the observation that SWCNTs alone were only toxic at concentrations ≥100 µg L⁻¹ and that the SWCNT-induced DNA damage was correlated with oxidative stress only in the absence of metals. If these laboratory experiments are confirmed in the natural environment, the present results will have implications for the understanding of the role of carbon nanotubes in environmental metal dynamics, toxicology, and consequently, regulatory requirements.

  16. Dissolved Divalent Metal and pH Effects on Amino Acid Polymerization: A Thermodynamic Evaluation

    NASA Astrophysics Data System (ADS)

    Kitadai, Norio

    2016-06-01

    Polymerization of amino acids is a fundamentally important step for the chemical evolution of life. Nevertheless, its response to changing environmental conditions has not yet been well understood because of the lack of reliable quantitative information. For thermodynamics, detailed prediction over diverse combinations of temperature and pH has been made only for a few amino acid-peptide systems. This study used recently reported thermodynamic dataset for the polymerization of the simplest amino acid "glycine (Gly)" to its short peptides (di-glycine and tri-glycine) to examine chemical and structural characteristics of amino acids and peptides that control the temperature and pH dependence of polymerization. Results showed that the dependency is strongly controlled by the intramolecular distance between the amino and carboxyl groups in an amino acid structure, although the side-chain group role is minor. The polymerization behavior of Gly reported earlier in the literature is therefore expected to be a typical feature for those of α-amino acids. Equilibrium calculations were conducted to examine effects of dissolved metals as a function of pH on the monomer-polymer equilibria of Gly. Results showed that metals shift the equilibria toward the monomer side, particularly at neutral and alkaline pH. Metals that form weak interaction with Gly (e.g., Mg2+) have no noticeable influence on the polymerization, although strong interaction engenders significant decrease of the equilibrium concentrations of Gly peptides. Considering chemical and structural characteristics of Gly and Gly peptides that control their interactions with metals, it can be expected that similar responses to the addition of metals are applicable in the polymerization of neutral α-amino acids. Neutral and alkaline aqueous environments with dissolved metals having high affinity with neutral α-amino acids (e.g., Cu2+) are therefore not beneficial places for peptide bond formation on the primitive

  17. Investigating extent of dissolved organic carbon stabilization by metal based coagulant in a wetland environment

    NASA Astrophysics Data System (ADS)

    Henneberry, Y.; Mourad, D.; Kraus, T.; Bachand, P.; Fujii, R.; Horwath, W.

    2008-12-01

    This study is part of a larger project designed to investigate the feasibility of using metal-based coagulants to remove dissolved organic carbon (DOC) from island drainage water in the San Joaquin Delta and subsequently retaining the metal-DOC precipitate (floc) in wetlands constructed at the foot of levees to promote levee stability. Dissolved organic carbon is a constituent of concern as some forms of DOC can be converted to carcinogenic compounds during drinking water treatment. The focus of this work is to assess floc stability over time and to determine whether floc can be permanently sequestered as part of wetland sediment. Drainage water collected seasonally from Twitchell Island was coagulated with ferric sulfate and polyaluminum chloride at optimal and 50%-optimal dosage levels. Floc was incubated in the laboratory under anaerobic conditions for six weeks under various conditions including different DOC concentrations, microbial inoculants, and addition of nutrients. Preliminary results indicate the floc is a stable system; little to no DOC was released from the floc into the water column under incubations with native microbial inoculate. In addition, floc incubated with previously coagulated water appeared to remove additional DOC from the water column. Future work will involve field and laboratory studies using 13C labeled plant material to examine the effects of fresh plant matter and the effects of peat soil DOC on floc stability, in order to elucidate mechanisms behind carbon stabilization by metal-based floc.

  18. The measurement of dissolved and gaseous carbon dioxide concentration

    NASA Astrophysics Data System (ADS)

    Zosel, J.; Oelßner, W.; Decker, M.; Gerlach, G.; Guth, U.

    2011-07-01

    In this review the basic principles of carbon dioxide sensors and their manifold applications in environmental control, biotechnology, biology, medicine and food industry are reported. Electrochemical CO2 sensors based on the Severinghaus principle and solid electrolyte sensors operating at high temperatures have been manufactured and widely applied already for a long time. Besides these, nowadays infrared, non-dispersive infrared and acoustic CO2 sensors, which use physical measuring methods, are being increasingly used in some fields of application. The advantages and drawbacks of the different sensor technologies are outlined. Electrochemical sensors for the CO2 measurement in aqueous media are pointed out in more detail because of their simple setup and the resulting low costs. A detailed knowledge of the basic detection principles and the windows for their applications is necessary to find an appropriate decision on the technology to be applied for measuring dissolved CO2. In particular the pH value and the composition of the analyte matrix exert important influence on the results of the measurements.

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

    USGS Publications Warehouse

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

    1996-01-01

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

  20. Metal concentrations of tadpoles in experimental ponds.

    PubMed

    Sparling, D W; Lowe, T P

    1996-01-01

    Anuran tadpoles are found in a variety of habitats, many of which are acidified or have high ambient concentrations of metals from anthropogenic sources. A few studies that have been conducted on metals in tadpoles demonstrate that they can contain high concentrations of some metals but have not demonstrated clear relationships between ambient conditions and metal concentrations. This study examines the influence of soil, water treatment, amphibian species, and body portion analyzed on metal concentration in tadpoles. In northern cricket frogs, gray treefrogs, and green frogs, concentrations of Al and Fe exceeded 10 000 microg.g(-1) and Mg and Mn exceeded 1000 microg g(-1). Body concentrations of Ba, Be, Fe, Mg, Mn, Ni, Pb, and Sr increased with soil concentrations. Acidification reduced body concentrations of Be and Sr, and pH correlated with Be, Mg, and Sr. Gray treefrogs had significantly lower concentrations of most metals compared to northern cricket frogs, possibly because of differences in microhabitats and soil ingestion. More than half of most metals was sequestered in the gut coil of green frog tadpoles, probably mixed with soil. Depending on bioavailablity, many of the metals in gut coils and whole bodies of these tadpoles could be potentially toxic to predators.

  1. Metal concentrations of tadpoles in experimental ponds

    USGS Publications Warehouse

    Sparling, D.W.; Lowe, T.P.

    1996-01-01

    Anuran tadpoles are found in a variety of habitats, many of which are acidified or have high ambient concentrations of metals from anthropogenic sources. A few studies that have been conducted on metals in tadpoles demonstrate that they can contain high concentrations of some metals but have not demonstrated clear relationships between ambient conditions and metal concentrations. This study examines the influence of soil, water treatment, amphibian species, and body portion analyzed on metal concentration in tadpoles. In northern cricket frogs, gray treefrogs, and green frogs, concentrations of Al and Fe exceeded I0000 g.g-1 and Mg and Mn exceeded 1000 g g-1. Body concentrations of Ba, Be, Fe, Mg, Mn, Ni, Pb, and Sr increased with soil concentrations. Acidification reduced body concentrations of Be and Sr, and pH correlated with Be, Mg, and Sr. Gray treefrogs had significantly lower concentrations of most metals compared to northern cricket frogs, possibly because of differences in microhabitats and soil ingestion. More than half of most metals was sequestered in the gut coil of green frog tadpoles, probably mixed with soil. Depending on bio-availability, many of the metals in gut coils and whole bodies of these tadpoles could be potentially toxic to predators.

  2. Use of lichen biomass to monitor dissolved metals in natural waters

    SciTech Connect

    Beck, J.N.; Ramelow, G.J. )

    1990-02-01

    The use of lichens for monitoring airborne metals is based on their immobility and a tendency to accumulate metals to a high degree by the trapping of atmospheric particles and by adsorptive ion exchange processes in which dissolved metals in rainwater are picked up by cellular membranes. The powerful metal-accumulating ability of lichens has been demonstrated in the laboratory. This strong metal accumulating ability of lichen biomass from aqueous solutions would seem to make lichen material an ideal biomonitor of dissolved metals in natural waters. To test this the present study was initiated to monitor dissolved zinc, copper, lead, nickel, cadmium, iron, manganese, chromium, and mercury in an industrially-impacted bayou in southwestern Louisiana. The results obtained with lichen biomonitors will be compared with other studies of the same metals in periphyton and sediments from this waterway.

  3. Metal partitioning between colloidal and dissolved phases and its relation with bioavailability to American oysters.

    PubMed

    Guo, Laodong; Santschi, Peter H; Ray, Sammy M

    2002-01-01

    Kinetics and the extent of metal partitioning between colloidal and dissolved phases and coagulation of metals associated with colloids were examined to determine their effects on the bioavailability of selected metals (Cd, Co, Hg, Ag, Fe, and Zn) to American oysters (Crassostrea virginica) using radiotracer and short term exposure experiments. After dispersion of radiolabeled colloids into low molecular weight (LMW, < 1 kDa) seawater, metal partitioning between dissolved (<1 kDa) and colloidal (1 kDa-0.2 microm) phases resulted in a consistent pattern, with a relatively constant percentage in the colloidal phase for each metal. On average, about 90% of Hg and Fe, approximately 60% of Ag and approximately 40% of Zn, Co, and Cd were measured in the colloidal fraction during a short term exposure experiment, consistent with their partitioning in natural waters. Controlled laboratory experiments carried out in parallel using radioactively tagged colloids showed that coagulation of colloidal species, quantified as the fraction retained by a 0.2 microm filter, was insignificant for most metals under the conditions and time periods of the uptake experiments. The bioavailability of colloidally complexed metals, measured in terms of dry weight concentration factor (DCF, ml g(-1)) and uptake rate constant (ml g(-1) h(-1)), was somewhat depressed compared with their counterpart in the LMW treatment, but could be well predicted from the results of the LMW treatment and metal partitioning. Both DCF values and uptake rate constants were higher in the LMW treatment than in the colloidal treatment. In addition, B-type metals, such as Ag, Hg, and Zn, all had higher values of DCF and uptake rate constants, regardless of treatments, except for Cd which had a lower DCF and uptake rate constant. In contrast, Co and Fe had significantly lower DCF values and uptake rate constants. Most of Hg and Ag (60-80%) were measured in the soft tissue of oysters in both LMW and colloidal treatments

  4. Distribution of dissolved and particulate trace metals in Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Taylor, M.; Hendy, I. L.; Aciego, S.; Meyer, K.

    2014-12-01

    Iron (Fe) is an essential biolimiting micronutrient, however, the bioavailablility of Fe is dependent on source and speciation. In a high nutrient/low chlorophyll region of the ocean such as the Arctic, sea ice is an important aggregator of dissolved and particulate Fe from aerosol, lithogenic, and biogenic sources. While particulate Fe is less bioavailable than dissolved Fe, it is far more abundant in sea ice. As a result, sea ice directly enhances productivity by ice entrapment of mineral dust particulates containing Fe, which can be released into the surface ocean waters during melting. In seawater underlying sea ice, Fe can be concentrated up to two orders of magnitude higher than in the ice-free open ocean (Lannuzel et al., 2011). A transect of sea ice cores were collected in the spring of 2014 offshore of Barrow, AK, and the Canadian Arctic Archipelago to capture a gradient of sediment contributions from shelf sediments to aeolian sediments. At Barrow, AK, land fast first year ice was sampled. In the Canadian Arctic, both multi-year (pack ice) and first year (land fast) ice cores were retrieved. First year ice cores were between 100-150 cm thick and the multi year core was 195 cm thick. Cores were subsampled by depth and filtered. The resulting ice core sediments were analyzed for elemental composition, and multistep Fe-leaching experiments were conducted to determine the fraction of soluble Fe. Thus we have ascertained the solubility of particulate Fe prior to onset of melt season. Dissolved trace metals were also analyzed to ascertain changes in concentration with ice core depth of lithogenic elements (Mn, Al) and biologically important elements (Si, Mo, Cu, Zn). Preliminary results show some enrichment of lithogenic inputs near surface, indicating dust deposition, and lower portions of the cores, suggesting resuspended sediments from the continental shelf. Concentrations of some biologically important elements decrease with depth, suggesting possible

  5. Dissolved volatile concentrations in an ore-forming magma

    USGS Publications Warehouse

    Lowenstern, J. B.

    1994-01-01

    Infrared spectroscopic measurements of glass inclusions within quartz phenocrysts from the Plinian fallout of the 22 Ma tuff of Pine Grove show that the trapped silicate melt contained high concentrations of H2O and CO2. Intrusive porphyries from the Pine Grove system are nearly identical in age, composition, and mineralogy to the tephra, and some contain high-grade Mo mineralization. Assuming that the porphyry magmas originally contained similar abundances of volatile components as the erupted rocks, they would have been saturated with fluid at pressures far greater than those at which the porphyries were emplaced and mineralized. The data are consistent with formation of Climax-type Mo porphyry deposits by prolonged fluid flux from a large volume of relatively Mo-poor (1-5 ppm) magma. -from Author

  6. Trace metal concentrations in oxidation ponds

    SciTech Connect

    Suffern, J.S.; Fitzgerald, C.M.; Szluha, A.T.

    1981-11-01

    Heavy metal concentrations of Cd, Cr, Cu, Ni, Pb, and Zn in the wastewater, sludge, and biotic components of the Oak Ridge National Laboratory oxidation ponds were examined to determine whether metals accumulated in tilapia. Results indicated that metal levels in the wastewater and biotic components are generally low and that the major metal reservoir is the sludge. Metals did not accumulate beyond established standards in the muscle or liver of tilapia grown in the oxidation ponds. This result may be partially due to the rapid growth rates of these fish (1-2 g fish/sup -1//day/sup -1/), with new tissue developing more rapidly than metals can accumulate. Another factor may be that the high concentrations of organic complexes in the ponds lower the availability of metals to the biota.

  7. Hypolimnetic concentrations of dissolved oxygen, nutrients, and trace elements in Coeur d'Alene Lake, Idaho

    USGS Publications Warehouse

    Woods, P.F.

    1989-01-01

    A reconnaissance study of Coeur d'Alene Lake, Idaho done from May through November 1987 assessed water quality throughout the lake. Particular emphasis was on hypolimnetic concentrations of dissolved oxygen, nutrients, and trace elements. Study results enabled refinement of the sampling protocol in a U.S. Geological Survey research proposal for a large-scale investigation of nutrient enrichment and trace element contamination problems affecting the 129.5 sq kilometer lake in northern Idaho. Hypolimnetic dissolved-oxygen concentrations as low as 4.1 mg/L in November and the frequent occurrence of supersaturated dissolved-oxygen concentrations during June through August indicated nutrient enrichment. Secchi-disc depths in the lake 's central and southern areas were typical of mesotrophic conditions, whereas oligotrophic conditions prevailed in the northern area. Throughout the study, hypolimnetic concentrations of total recoverable zinc exceeded chronic and acute toxicity criteria for freshwater aquatic life. (USGS)

  8. The effect of membrane filtration artifacts on dissolved trace element concentrations

    USGS Publications Warehouse

    Horowitz, A.J.; Elrick, K.A.; Colberg, M.R.

    1992-01-01

    Among environment scientists, the current and almost universally accepted definition of dissolved constituents is an operational one only those materials which pass through a 0.45-??m membrane filter are considered to be dissolved. Detailed laboratory and field studies on Fe and Al indicate that a number of factors associated with filtration, other than just pore size, can substantially alter 'dissolved' trace element concentrations; these include: filter type, filter diameter, filtration method, volume of sample processed, suspended sediment concentration, suspended sediment grain-size distribution, concentration of colloids and colloidally-associated trace elements and concentration of organic matter. As such, reported filtered-water concentrations employing the same pore size filter may not be equal. Filtration artifacts may lead to the production of chemical data that indicate seasonal or annual 'dissolved' chemical trends which do not reflect actual environmental conditions. Further, the development of worldwide averages for various dissolved chemical constituents, the quantification of geochemical cycles, and the determination of short- or long-term environmental chemical trends may be subject to substantial errors, due to filtration artifacts, when data from the same or multiple sources are combined. Finally, filtration effects could have a substantial impact on various regulatory requirements.

  9. Effect of dissolved oxygen concentration on growth of fingerling hybrid striped bass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management of dissolved oxygen (DO) concentration in production ponds is important because fish growth and yield are greater in ponds with higher DO concentrations. The purpose of this study was to evaluate growth and metabolic responses of hybrid striped bass (Morone chrysops x M. saxatilis; HSB) f...

  10. Effect of daily minimum pond dissolved oxygen concentration on hybrid striped bass fingerling yield

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management of dissolved oxygen (DO) concentration in ponds at night during the growing season is important because fish growth and yield are greater in ponds with higher nightly DO concentrations. The purpose of this study was to quantify the production and water quality responses of hybrid striped ...

  11. DISSOLVED ORGANIC MATTER AND METALS: EFFECTS OF PH ON PARTITIONING

    EPA Science Inventory

    Eighteen Dutch soils were extracted in aqueous solutions at varying pH. Extracts were analyzed for Cd, Cu, Ni, Pb, and Zn by ICP-AES. Extract dissolved organic carbon (DOC) was fractionated into three operationally defined fractions: hydrophilic acids (Hyd), fulvic acids (FA), an...

  12. Dissolved Phosphorus Concentrations in the Mississippi River Valley Alluvial Aquifer, Northwestern Mississippi

    NASA Astrophysics Data System (ADS)

    Rose, C. E.; Welch, H. L.

    2010-12-01

    The Mississippi River Valley alluvial (MRVA) aquifer is the most heavily used aquifer in the state of Mississippi with more than 1.3 billion gallons of water per day being withdrawn primarily for irrigation. In a study conducted in 1998, median concentrations of dissolved phosphorus in water from 25 wells screened in the Holocene alluvium and 29 wells screened in the Pleistocene valley train deposits, two subunits of the MRVA aquifer, were 0.65 and 0.11 milligrams per liter (mg/L), respectively. Both values are considerably higher than the typical average concentration of 0.02 mg/L for dissolved phosphorus in groundwater; and more than 0.1 mg/L, which is the U.S. Environmental Protection Agency’s water-quality criteria for dissolved phosphorus in streams for the prevention of nuisance plant growth. Approximately 67 percent of the water samples exceeded the EPA criteria. A general association between elevated phosphorus concentrations and high concentrations of dissolved iron suggests that reducing conditions that mobilize iron in the MRVA aquifer also may facilitate transport of phosphorus. These elevated concentrations of phosphorus in the two subunits may represent a source of phosphorus to streams and rivers in the study area through irrigation return flow and groundwater discharge during stream base-flow conditions. Fifty irrigation wells were sampled during the summer 2010 for total dissolved phosphorus, iron, manganese, calcium, arsenic, silica, and field parameters (pH, specific conductance, turbidity, and alkalinity) to further characterize the occurrence of phosphorus in the aquifer, as well as the factors that might contribute to high dissolved phosphorus concentrations in the aquifer.

  13. Effect of oxygen reduction rate and constant low dissolved oxygen concentrations on two estuarine fish

    SciTech Connect

    Burton, D.T.; Richardson, L.B.; Moore, C.J.

    1980-09-01

    The relationship between mean lethal oxygen concentration and rate of reduction of dissolved oxygen that induces fish kills was determined for Atlantic menhaden (Brevoortia tyrannus). Reduction of dissolved oxygen at hourly rates of 1.00 to 0.08 mg/liter had no effect on the mean lethal oxygen concentrations. There was an inverse relationship between the median time to death (LT50) and rate of oxygen reduction that can be used to estimate how quickly a fish kill may occur when oxygen concentrations decrease at a constant rate. Atlantic menhaden were less resistant than spot (Leiostomus xanthurus) when both species were exposed to constant low concentrations of oxygen. The lethal threshold concentrations for Atlantic menhaden and spot at 28/sup 0/C were approximately 1.1 and 0.7 mg/liter, respectively, whereas, the 96-hour, 5% lethal concentrations were approximately 1.6 and 0.8 mg/liter, respectively.

  14. Small-scale variability of metal concentrations in soil leachates

    SciTech Connect

    Wilcke, W.

    2000-02-01

    Soil tests often use composite soil samples to assess metal bioavailability. Composite soil samples cannot address small-scale soil heterogeneity. In this study, the concentrations of Al, Cd, Cu, Mn, Ni, Pb, Zn, dissolved organic C (DOC), and pH in soil leachates were examined as an index of small-scale soil heterogeneity. Ten undisturbed soil cores from a 1-m{sup 2} area of a Lithic Haplumbrept and a Typic Hapludoll (pH 4.3) under forest canopy were equilibrated with deionized water. The soil cores were then leached with a mock soil solution. In the Haplumbrept, the pH of the first 50-mL fraction of the leachates was 4.2 to 7.4, DOC concentrations were 11.4 to 38.9 mg L{sup {minus}1}. Aluminum, Cd, Mn, and Ni concentrations were significantly correlated with pH; varied little in the first 50-mL fractions; Cr, Cu, and Pb concentrations were correlated with DOC concentrations. The variability in metal concentrations of the first 50-mL fractions was comparable in both soils and did not change with increasing leachate volume except for Zn in the Haplumbrept. In all leachate fractions, variability was markedly higher than those reported for salt extracts of composite soil samples. Thus, the analysis of composite samples may be insufficient to address metal bioavailability in soils.

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

    USGS Publications Warehouse

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

    2008-01-01

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

  16. Problems associated with using filtration to define dissolved trace element concentrations in natural water samples

    USGS Publications Warehouse

    Horowitz, A.J.; Lum, K.R.; Garbarino, J.R.; Hall, G.E.M.; Lemieux, C.; Demas, C.R.

    1996-01-01

    Field and laboratory experiments indicate that a number of factors associated with filtration other than just pore size (e.g., diameter, manufacturer, volume of sample processed, amount of suspended sediment in the sample) can produce significant variations in the 'dissolved' concentrations of such elements as Fe, Al, Cu, Zn, Pb, Co, and Ni. The bulk of these variations result from the inclusion/exclusion of colloidally associated trace elements in the filtrate, although dilution and sorption/desorption from filters also may be factors. Thus, dissolved trace element concentrations quantitated by analyzing filtrates generated by processing whole water through similar pore-sized filters may not be equal or comparable. As such, simple filtration of unspecified volumes of natural water through unspecified 0.45-??m membrane filters may no longer represent an acceptable operational definition for a number of dissolved chemical constituents.

  17. Magnetic sulfide-modified nanoscale zerovalent iron (S-nZVI) for dissolved metal ion removal.

    PubMed

    Su, Yiming; Adeleye, Adeyemi S; Keller, Arturo A; Huang, Yuxiong; Dai, Chaomeng; Zhou, Xuefei; Zhang, Yalei

    2015-05-01

    Sulfide-modified nanoscale zerovalent iron (S-nZVI) is attracting a lot of attention due to its ease of production and high reactivity with organic pollutants. However, its structure is still poorly understood and its potential application in heavy metal remediation has not been explored. Herein, the structure of S-nZVI and its cadmium (Cd) removal performance under different aqueous conditions were carefully investigated. Transmission electron microscopy (TEM) with an energy-dispersive X-ray spectroscopy (EDS) analysis suggested that sulfur was incorporated into the zerovalent iron core. Scanning electron microscopy (SEM) with EDS analysis demonstrated that sulfur was also homogeneously distributed within the nanoparticles. When the concentration of Na2S2O4 was increased during synthesis, a flake-like structure (FeSx) increased significantly. S-nZVI had an optimal Cd removal capacity of 85 mg/g, which was >100% higher than for pristine nZVI. Even at pH 5, over 95% removal efficiency was observed, indicating sulfide compounds played a crucial role in metal ion removal and particle chemical stability. Oxygen impaired the structure of S-nZVI but enhanced Cd removal capacity to about 120 mg/g. Particle aging had no negative effect on removal capacity of S-nZVI, and Cd-containing mixtures remained stable in a two months experiment. S-nZVI can efficiently sequester dissolved metal ions from different contaminated water matrices. PMID:25706223

  18. Natural and anthropogenic factors controlling the dissolved organic carbon concentrations and fluxes in a large tropical river, India.

    PubMed

    Balakrishna, K; Kumar, Itta Arun; Srinikethan, G; Mugeraya, Gopal

    2006-11-01

    Carbon studies in tropical rivers have gained significance since it was realized that a significant chunk of anthropogenic CO(2) emitted into the atmosphere returns to the biosphere, that is eventually transported by the river and locked up in coastal sediments for a few thousand years. Carbon studies are also significant because dissolved organic carbon (DOC) is known to complex the toxic trace metals in the river and carry them in the dissolved form. For the first time, this work has made an attempt to study the variations in DOC concentrations in space and time for a period of 19 months, and estimate their fluxes in the largest peninsular Indian river, the Godavari at Rajahmundry. Anthropogenic influence on DOC concentrations possibly from the number of bathing ghats along the banks and domestic sewage discharge into the river are evident during the pre-monsoon of 2004 and 2005. The rise in DOC concentrations at the onset of monsoon could be due to the contributions from flood plains and soils from the river catchment. Spatial variations highlighted that the DOC concentrations in the river are affected more by the anthropogenic discharges in the downstream than in the upstream. The discharge weighted DOC concentrations in the Godavari river is 3-12 times lower than Ganga-Brahmaputra, Indus and major Chinese rivers. The total carbon fluxes from the Godavari into the Bay of Bengal is insignificant (0.5%) compared to the total carbon discharges by major rivers of the world into oceans.

  19. Natural and anthropogenic factors controlling the dissolved organic carbon concentrations and fluxes in a large tropical river, India.

    PubMed

    Balakrishna, K; Kumar, Itta Arun; Srinikethan, G; Mugeraya, Gopal

    2006-11-01

    Carbon studies in tropical rivers have gained significance since it was realized that a significant chunk of anthropogenic CO(2) emitted into the atmosphere returns to the biosphere, that is eventually transported by the river and locked up in coastal sediments for a few thousand years. Carbon studies are also significant because dissolved organic carbon (DOC) is known to complex the toxic trace metals in the river and carry them in the dissolved form. For the first time, this work has made an attempt to study the variations in DOC concentrations in space and time for a period of 19 months, and estimate their fluxes in the largest peninsular Indian river, the Godavari at Rajahmundry. Anthropogenic influence on DOC concentrations possibly from the number of bathing ghats along the banks and domestic sewage discharge into the river are evident during the pre-monsoon of 2004 and 2005. The rise in DOC concentrations at the onset of monsoon could be due to the contributions from flood plains and soils from the river catchment. Spatial variations highlighted that the DOC concentrations in the river are affected more by the anthropogenic discharges in the downstream than in the upstream. The discharge weighted DOC concentrations in the Godavari river is 3-12 times lower than Ganga-Brahmaputra, Indus and major Chinese rivers. The total carbon fluxes from the Godavari into the Bay of Bengal is insignificant (0.5%) compared to the total carbon discharges by major rivers of the world into oceans. PMID:16738757

  20. Tracking Dissolved Methane Concentrations near Active Seeps and Gas Hydrates: Sea of Japan.

    NASA Astrophysics Data System (ADS)

    Snyder, G. T.; Aoki, S.; Matsumoto, R.; Tomaru, H.; Owari, S.; Nakajima, R.; Doolittle, D. F.; Brant, B.

    2015-12-01

    A number of regions in the Sea of Japan are known for active gas venting and for gas hydrate exposures on the sea floor. In this investigation we employed several gas sensors mounted on a ROV in order to determine the concentrations of dissolved methane in the water near these sites. Methane concentrations were determined during two-second intervals throughout each ROV deployment during the cruise. The methane sensor deployments were coupled with seawater sampling using Niskin bottles. Dissolved gas concentrations were later measured using gas chromatography in order to compare with the sensor results taken at the same time. The observed maximum dissolved methane concentrations were much lower than saturation values, even when the ROV manipulators were in contact with gas hydrate. Nonetheless, dissolved concentrations did reach several thousands of nmol/L near gas hydrate exposures and gas bubbles, more than two orders of magnitude over the instrumental detection limits. Most of the sensors tested were able to detect dissolved methane concentrations as low as 10 nmol/L which permitted detection when the ROV approached methane plume sites, even from several tens of meters above the sea floor. Despite the low detection limits, the methane sensors showed variable response times when returning to low-background seawater (~5nM). For some of the sensors, the response time necessary to return to background values occurred in a matter of minutes, while for others it took several hours. Response time, as well as detection limit, should be an important consideration when selecting methane sensors for ROV or AUV investigations. This research was made possible, in part, through funding provided by the Japanese Ministry of Economy, Trade and Industry (METI).

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  2. Declines in Dissolved Silica Concentrations in Western Virginia Streams (1988- 2003)

    NASA Astrophysics Data System (ADS)

    Grady, A. E.; Scanlon, T. M.; Galloway, J. N.

    2006-12-01

    Dissolved silica concentrations in western Virginia streams showed a significant bias toward declines (p<0.0001) over the time period from 1988-2003. Streams with the greatest declines were those that had the highest mean dissolved silica concentrations, specific to watersheds underlain by basaltic and granitic bedrock. We examined potential geochemical, hydrological, and biological factors that could account for the observed widespread declines, focusing on six core watersheds where weekly stream chemistry data were available. No relationships were evident between stream water dissolved silica concentrations and pH, a finding supported by the results from a geochemical model applied to the dominant bedrock mineralogy. Along with changes in watershed acidity, changes in precipitation and discharge were also discounted since no significant trends were observed over the study period. Analyses of two longer-term datasets that extend back to 1979 revealed that the initiation of the dissolved silica declines coincided with the timing of a gypsy moth (Lymantria dispar) defoliation event. We develop a conceptual model centered on benthic diatoms, which are found within each of the six core watersheds but in greater abundance in the more silica-rich streams. Gypsy moth defoliation lead to greater sunlight penetration and enhanced nitrate concentrations in the streams, which could have spurred population growth and silica uptake. The model can explain why the observed declines are primarily driven by decreased concentrations during low-flow conditions. This study illustrates lasting effects of disturbance on watershed biogeochemistry, in this case causing decadal-scale variability in stream water dissolved silica concentrations.

  3. ACUTE SENSITIVITY OF JUVENILE SHORTNOSE STURGEON TO LOW DISSOLVED OXYGEN CONCENTRATIONS

    EPA Science Inventory

    Campbell, Jed G. and Larry R. Goodman. 2004. Acute Sensitivity of Juvenile Shortnose Sturgeon to Low Dissolved Oxygen Concentrations. EPA/600/J-04/175. Trans. Am. Fish. Soc. 133(3):772-776. (ERL,GB 1155).

    There is considerable concern that factors such as eutrophication, ...

  4. Occurrence and concentration of dissolved silver in rivers in England and Wales.

    PubMed

    Peters, A; Simpson, P; Merrington, G; Rothenbacher, K; Sturdy, L

    2011-06-01

    There is a paucity of monitoring data for silver in freshwater environments in Europe. There are several reasons for this, including the relatively low levels of silver in the aquatic environment and the requirement for commensurately low levels of detection (<100 ng l⁻¹), which are generally not routinely achieved in analytical laboratories. In this study 425 separate analytical determinations for dissolved (<0.45 μm) silver from 84 Environment Agency monitoring stations were carried out. Sampling was carried out on a monthly basis over a period of 6 months. Of the 425 samples, 346 were reported as having dissolved silver concentrations below the limit of quantification (6.6 ng l⁻¹) and, of these, 280 samples were reported as below the reporting limit of detection (3 ng l⁻¹). The mean of the maximum dissolved silver concentrations reported at each station was calculated as 6.1 ng l⁻¹ using a statistical extrapolation technique to allow for the high level of censorship in the dataset. The maximum mean dissolved silver concentration recorded at a station was 19.8 ng l⁻¹. A freshwater Predicted No Effect Concentration (PNEC) of 40 ng l⁻¹ was used in this study. PMID:21516451

  5. New Concentric Electrode Metal-Semiconductor-Metal Photodetectors

    NASA Technical Reports Server (NTRS)

    Towe, Elias

    1996-01-01

    A new metal-semiconductor-metal (MSM) photodetector geometry is proposed. The new device has concentric metal electrodes which exhibit a high degree of symmetry and a design flexibility absent in the conventional MSM device. The concentric electrodes are biased to alternating potentials as in the conventional interdigitated device. Because of the high symmetry configuration, however, the new device also has a lower effective capacitance. This device and the conventional MSM structure are analyzed within a common theoretical framework which allows for the comparison of the important performance characteristics.

  6. Significance of groundwater discharge along the coast of Poland as a source of dissolved metals to the southern Baltic Sea.

    PubMed

    Szymczycha, Beata; Kroeger, Kevin D; Pempkowiak, Janusz

    2016-08-15

    Fluxes of dissolved trace metals (Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) via groundwater discharge along the southern Baltic Sea have been assessed for the first time. Dissolved metal concentrations in groundwater samples were less variable than in seawater and were generally one or two orders of magnitude higher: Cd (2.1-2.8nmolL(-1)), Co (8.70-8.76nmolL(-1)), Cr (18.1-18.5nmolL(-1)), Mn (2.4-2.8μmolL(-1)), Pb (1.2-1.5nmolL(-1)), Zn (33.1-34.0nmolL(-1)). Concentrations of Cu (0.5-0.8nmolL(-1)) and Ni (4.9-5.8nmolL(-1)) were, respectively, 32 and 4 times lower, than in seawater. Groundwater-derived trace metal fluxes constitute 93% for Cd, 80% for Co, 91% for Cr, 6% for Cu, 66% for Mn, 4% for Ni, 70% for Pb and 93% for Zn of the total freshwater trace metal flux to the Bay of Puck. Groundwater-seawater mixing, redox conditions and Mn-cycling are the main processes responsible for trace metal distribution in groundwater discharge sites. PMID:27293076

  7. Significance of groundwater discharge along the coast of Poland as a source of dissolved metals to the southern Baltic Sea

    USGS Publications Warehouse

    Szymczycha, Beata; Kroeger, Kevin D.; Pempkowiak, Janusz

    2016-01-01

    Fluxes of dissolved trace metals (Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) via groundwater discharge along the southern Baltic Sea have been assessed for the first time. Dissolved metal concentrations in groundwater samples were less variable than in seawater and were generally one or two orders of magnitude higher: Cd (2.1–2.8 nmol L− 1), Co (8.70–8.76 nmol L− 1), Cr (18.1–18.5 nmol L− 1), Mn (2.4–2.8 μmol L− 1), Pb (1.2–1.5 nmol L− 1), Zn (33.1–34.0 nmol L− 1). Concentrations of Cu (0.5–0.8 nmol L− 1) and Ni (4.9–5.8 nmol L− 1) were, respectively, 32 and 4 times lower, than in seawater. Groundwater-derived trace metal fluxes constitute 93% for Cd, 80% for Co, 91% for Cr, 6% for Cu, 66% for Mn, 4% for Ni, 70% for Pb and 93% for Zn of the total freshwater trace metal flux to the Bay of Puck. Groundwater-seawater mixing, redox conditions and Mn-cycling are the main processes responsible for trace metal distribution in groundwater discharge sites.

  8. Nonaqueous method for dissolving lanthanide and actinide metals

    DOEpatents

    Crisler, L.R.

    1975-11-11

    Lanthanide and actinide beta-diketonate complex molecular compounds are produced by reacting a beta-diketone compound with a lanthanide or actinide element in the elemental metallic state in a mixture of carbon tetrachloride and methanol.

  9. Dissolved trace element concentrations in the East River-Long Island Sound system: relative importance of autochthonous versus allochthonous sources.

    PubMed

    Buck, Nathaniel J; Gobler, Christopher J; Sañudo-Wilhelmy, Sergio A

    2005-05-15

    Dissolved trace metal (Ag, Cd, Cu, Fe, Ni, Pb, and Zn), inorganic nutrient (NO3, NH4, PO4, H4SiO4), and DOC concentrations were measured at 43 stations during low (July 2000) and high (April 2001) river discharge conditions in surface waters of Long Island Sound (LIS). To evaluate the impact of fluvial sources to the total metal budget of the sound, samples were collected from major tributaries discharging into LIS (Thames, Quinnipiac, Housatonic, Connecticut, and East Rivers). To compare LIS with other coastal embayments, samples were also collected from five LIS coastal embayments (Manhassett Bay, Huntington Harbor, Oyster Bay, Hempstead Harbor, and Port Jefferson Harbor), which are monitored by the U.S. National Status and Trends Program. Metal and nutrient distributions identified two biogeochemical regimes within LIS: an area of relatively high nutrient and metal concentrations in the East River/Narrows region in western LIS and an area in the eastern region of the sound that had comparatively lower concentrations. Mass balance estimates indicated that, during low flow conditions, the East River was the dominant allochthonous source of most trace metals (Ag, Cd, Cu, Ni, Zn) and inorganic nutrients (NO3 and PO4); during high flow conditions, the most influential source of these constituents was the Connecticut River. Mass balance estimates also evidenced a large autochthonous source of Cu, Ni, and Zn, as their spatial distributions displayed elevated concentrations away from point sources such as the East River. Principal component analysis suggested that metal and nutrient distributions in the LIS system were influenced by different seasonal processes: remobilization from contaminated sediments, anthropogenic inputs from sewage discharges and phytoplankton scavenging during the spring freshet, and benthic remobilization during summer conditions.

  10. [Influence of the Concentration of Dissolved Oxygen on Embryonic Development of the Common Toad (Bufo bufo)].

    PubMed

    Dmitrieva, E V

    2015-01-01

    Several series of experiments investigating the influence of dissolved oxygen concentrations on the growth rates and mortality in the embryogenesis of the common toad Bufo bufo were carried out. The experiments showed that, when the eggs develop singly, the lack of oxygen does not lead to an increase in mortality by the time of hatching and results only in a change in the dynamics of mortality: mortality occurs at an earlier stage of development than in the conditions of normal access to oxygen. Taking into account the combined effect of the density of eggs and the dissolved oxygen concentration, we increase the accuracy of analysis of the experimental results and improve the interpretation of the results. In the conditions of different initial density of eggs, the impact of the concentration of dissolved oxygen on mortality and rates of development of the common toad embryos is manifested in different ways. At high density, only a small percentage of embryos survives by the time of hatching, and the embryos are significantly behind in their development compared with the individuals that developed in normal oxygen conditions. The lack of oxygen dissolved in the water slows down the development of embryos of the common toad.

  11. Fluoride, Nitrate, and Dissolved-Solids Concentrations in Ground Waters of Washington

    USGS Publications Warehouse

    Lum, W. E.; Turney, Gary L.

    1984-01-01

    This study provides basic data on ground-water quality throughout the State. It is intended for uses in planning and management by agencies and individuals who have responsibility for or interest in, public health and welfare. It also provides a basis for directing future studies of ground-water quality toward areas where ground-water quality problems may already exist. The information presented is a compilation of existing data from numerous sources including: the Washington Departments of Ecology and Social and Health Services, the Environmental Protection Agency, as well as many other local, county, state and federal agencies and private corporations. Only data on fluoride, nitrate, and dissolved-solids concentrations in ground water are presented, as these constituents are among those commonly used to determine the suitability of water for drinking or other purposes. They also reflect both natural and man-imposed effects on water quality and are the most readily available water-quality data for the State of Washington. The percentage of wells with fluoride, nitrate, or dissolved-solids concentrations exceeding U.S. Environmental Protection Agency Primary and Secondary Drinking Water Regulations were about 1, about 3, and about 3, respectively. Most high concentrations occurred in widely separated wells. Two exceptions were: high concentrations of nitrate and dissolved solids in wells on the Hanford Department of Energy Facility and high concentrations of nitrate in the lower Yakima River basin. (USGS)

  12. Urban Impact of Dissolved Metals in the Paso del Norte Segment of the Rio Grande

    ERIC Educational Resources Information Center

    Freiwan, Sumayeh Ahmad

    2013-01-01

    The Paso del Norte segment of the Rio Grande experiences two seasons per year; the (wet) irrigation season and the (dry) non-irrigation season. The goal of this study was to improve the understanding of occurrence and contribution of dissolved metals in this region during the non-irrigation season. The objectives of this study were to (1) evaluate…

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  14. Size exclusion and anion exchange high performance liquid chromatography for characterizing metals bound to marine dissolved organic matter.

    PubMed

    García-Otero, Natalia; Bermejo-Barrera, Pilar; Moreda-Piñeiro, Antonio

    2013-01-14

    Size exclusion chromatography (SEC) followed by anion exchange chromatography (AEC) hyphenated with inductively coupled plasma-mass spectrometry (ICP-MS) was applied for fractionating metals bound to marine dissolved organic matter (DOM). Surface seawater samples (100 L) were subjected to tangential flow ultrafiltration (10,000 Da cut off) for isolating and pre-concentrating dissolved large molecules. The isolated fraction (retentate) consisted of 1L, which was further freeze-dried and re-dissolved to 250 mL with ultrapure water. After HI Trap desalting of the re-dissolved retentate, SEC with UV detection showed marine DOM ranging from 6.5 kDa (lower than the permeable volume of the SEC column) to 16 kDa. A further characterization of this fraction by AEC with UV detection revealed the existence of four groups of macromolecules exhibiting retention times of 2.3, 2.8, 4.5 and 14.0 min. AEC hyphenated with ICP-MS showed the presence of strontium and zinc in the first AE fraction isolated from the SEC fraction; while manganese was found to be bound to the second AE fraction. Cobalt was found to be bound to molecules comprising the third AE fraction. PMID:23265737

  15. The Distribution between the Dissolved and the Particulate Forms of 49 Metals across the Tigris River, Baghdad, Iraq

    PubMed Central

    Hamad, Samera Hussein; Schauer, James Jay; Shafer, Martin Merrill; Abed Al-Raheem, Esam; Satar, Hyder

    2012-01-01

    The distribution of dissolved and particulate forms of 49 elements was investigated along transect of the Tigris River (one of the major rivers of the world) within Baghdad city and in its major tributary (Diyala River) from 11 to 28 July 2011. SF-ICP-MS was used to measure total and filterable elements at 17 locations along the Tigris River transect, two samples from the Diyala River, and in one sample from the confluence of the two rivers. The calculated particulate forms were used to determine the particle-partition coefficients of the metals. No major changes in the elements concentrations down the river transect. Dissolved phases dominated the physical speciation of many metals (e.g., As, Mo, and Pt) in the Tigris River, while Al, Fe, Pb, Th, and Ti were exhibiting high particulate fractions, with a trend of particle partition coefficients of [Ti(40) > Th(35) > Fe(15) > Al(13) > Pb(4.5)] ∗ 106 L/kg. Particulate forms of all metals exhibited high concentrations in the Diyala River, though the partition coefficients were low due to high TSS (~270 mg/L). A comparison of Tigris with the major rivers of the world showed that Tigris quality in Baghdad is comparable to Seine River quality in Paris. PMID:23304083

  16. Urinary metal concentrations among female welders.

    PubMed

    Arrandale, Victoria H; Beach, Jeremy; Cembrowski, George S; Cherry, Nicola M

    2015-01-01

    As part of a Canada-wide study of women entering non-traditional trades [Women's Health in Apprenticeship Trades-Metalworkers and Electricians (WHAT-ME)], we examined spot urine samples from women welders in Alberta to determine whether urinary metal concentrations exceeded those of the general population, to compare levels to previously published urinary concentrations in male welders and to examine the relationship with welding tasks. Women mailed-in urine samples collected close to the time of completing a detailed exposure questionnaire, including welding tasks on their most recent day welding at work. Of 53 welders working in their trade, 45 had urinary creatinine >0.3-≤3.0g l(-1) and were included in analyses. Seven metals were examined for which both population and male welder urinary concentrations were available: cadmium, chromium, cobalt, copper, manganese, nickel, and zinc. Principal component analysis was used to extract three components from natural log transformed creatinine-corrected metal concentrations. Of the 45 women, 17 reported more than one main task. Overall two thirds worked in fabrication, a third on pipe welding, and smaller numbers on repair, in construction or other tasks: manual metal arc welding was reported by 62%, semi-automatic arc welding by 47%, and arc welding with a tungsten electrode by 15%. In multiple regression analyses, little relation was found between urinary metals and task or type of welding, except for cadmium where lower levels were seen in those reporting semi-automatic manual welding (after adjustment for age and smoking). The proportion of women welders exceeding the selected general population 95th percentile was high for manganese (96%) and chromium (29%). Urinary metal concentrations were similar to those reported for male welders with only manganese, with a geometric mean in women of 1.91 µg g(-1) creatinine, and perhaps copper (11.8 µg g(-1) creatinine), consistently lower in male welders. Although not

  17. Urinary metal concentrations among female welders.

    PubMed

    Arrandale, Victoria H; Beach, Jeremy; Cembrowski, George S; Cherry, Nicola M

    2015-01-01

    As part of a Canada-wide study of women entering non-traditional trades [Women's Health in Apprenticeship Trades-Metalworkers and Electricians (WHAT-ME)], we examined spot urine samples from women welders in Alberta to determine whether urinary metal concentrations exceeded those of the general population, to compare levels to previously published urinary concentrations in male welders and to examine the relationship with welding tasks. Women mailed-in urine samples collected close to the time of completing a detailed exposure questionnaire, including welding tasks on their most recent day welding at work. Of 53 welders working in their trade, 45 had urinary creatinine >0.3-≤3.0g l(-1) and were included in analyses. Seven metals were examined for which both population and male welder urinary concentrations were available: cadmium, chromium, cobalt, copper, manganese, nickel, and zinc. Principal component analysis was used to extract three components from natural log transformed creatinine-corrected metal concentrations. Of the 45 women, 17 reported more than one main task. Overall two thirds worked in fabrication, a third on pipe welding, and smaller numbers on repair, in construction or other tasks: manual metal arc welding was reported by 62%, semi-automatic arc welding by 47%, and arc welding with a tungsten electrode by 15%. In multiple regression analyses, little relation was found between urinary metals and task or type of welding, except for cadmium where lower levels were seen in those reporting semi-automatic manual welding (after adjustment for age and smoking). The proportion of women welders exceeding the selected general population 95th percentile was high for manganese (96%) and chromium (29%). Urinary metal concentrations were similar to those reported for male welders with only manganese, with a geometric mean in women of 1.91 µg g(-1) creatinine, and perhaps copper (11.8 µg g(-1) creatinine), consistently lower in male welders. Although not

  18. Laser induced fluorescence measurements of dissolved oxygen concentration fields near air bubble surfaces

    NASA Astrophysics Data System (ADS)

    Roy, Sabita; Duke, Steve R.

    2000-09-01

    This article describes a laser-induced fluorescence (LIF) technique for measuring dissolved oxygen concentration gradients in water near the surface of an air bubble. Air bubbles are created at the tip of a needle in a rectangular bubble column filled with water that contains pyrenebutyric acid (PBA). The fluorescence of the PBA is induced by a planar pulse of nitrogen laser light. Oxygen transferring from the air bubble to the deoxygenated water quenches the fluorescence of the PBA. Images of the instantaneous and two-dimensional fluorescence field are obtained by a UV-intensified charge-coupled device (CCD) camera. Quenching of fluorescence intensity is determined at each pixel in the CCD image to measure dissolved oxygen concentration. Two-dimensional concentration fields are presented for a series of measurements of oxygen transfer from 1.6 mm bubbles suspended on the tip of a needle in a quiescent fluid. The images show the spatially varying concentration profiles, gradients, and boundary layer thicknesses at positions around the bubble surfaces. These direct and local measurements of concentration behavior within the mass transfer boundary layer show the potential of this LIF technique for the development of general and mechanistic models for oxygen transport across the air-water interface.

  19. Naturally dissolved arsenic concentrations in the Alpine/Mediterranean Var River watershed (France).

    PubMed

    Barats, Aurélie; Féraud, Gilbert; Potot, Cécile; Philippini, Violaine; Travi, Yves; Durrieu, Gaël; Dubar, Michel; Simler, Roland

    2014-03-01

    A detailed study on arsenic (As) in rocks and water from the Var River watershed was undertaken aiming at identifying (i) the origin and the distribution of As in this typical Alpine/Mediterranean basin, and (ii) As input into the Mediterranean Sea. Dissolved As concentrations in the Var River range from 0.1 to 4.5 μg⋅L(-1), due to high hydrological variability and the draining through different geological formations. In the upper part of the Var drainage basin, in the Tinée and the Vésubie valleys, high levels of dissolved As concentrations occur (up to 263 μg⋅L(-1)). The two main sources of As in rocks are the Hercynian metamorphic rocks and the Permian argilites. Highly heterogeneous distribution of As in waters draining through metamorphic rocks is probably related to ore deposits containing arsenopyrite. As, U, W and Mo concentrations in water and rocks correspond to the formation of As-rich ore deposits around Argentera granite by hydrothermal fluids deposited at the end of the Hercynian chain formation, which occurred about 300 My ago. In 2009, weekly monitoring was performed on the Var River (15 km upstream of the mouth), highlighting an average dissolved As concentration (<0.45 μm) of 2.7 ± 0.9 μg⋅L(-1), which is significantly higher than the world-average baseline for river water (0.83 μg⋅L(-1)). Taking the average annual discharge (49.4 m(3)⋅s(-1)) into account and the As levels in the dissolved phase and in deposits of the Var River, dissolved As input into the Mediterranean Sea would be 4. 2± 1.4 tons⋅year(-1) which represents 59% of the total As flux. This study also reveals a probable non-conservative As behaviour, i.e., possible transfer between aqueous and solid phases, during the mixing of the Var River with a tributary. PMID:24388820

  20. Naturally dissolved arsenic concentrations in the Alpine/Mediterranean Var River watershed (France).

    PubMed

    Barats, Aurélie; Féraud, Gilbert; Potot, Cécile; Philippini, Violaine; Travi, Yves; Durrieu, Gaël; Dubar, Michel; Simler, Roland

    2014-03-01

    A detailed study on arsenic (As) in rocks and water from the Var River watershed was undertaken aiming at identifying (i) the origin and the distribution of As in this typical Alpine/Mediterranean basin, and (ii) As input into the Mediterranean Sea. Dissolved As concentrations in the Var River range from 0.1 to 4.5 μg⋅L(-1), due to high hydrological variability and the draining through different geological formations. In the upper part of the Var drainage basin, in the Tinée and the Vésubie valleys, high levels of dissolved As concentrations occur (up to 263 μg⋅L(-1)). The two main sources of As in rocks are the Hercynian metamorphic rocks and the Permian argilites. Highly heterogeneous distribution of As in waters draining through metamorphic rocks is probably related to ore deposits containing arsenopyrite. As, U, W and Mo concentrations in water and rocks correspond to the formation of As-rich ore deposits around Argentera granite by hydrothermal fluids deposited at the end of the Hercynian chain formation, which occurred about 300 My ago. In 2009, weekly monitoring was performed on the Var River (15 km upstream of the mouth), highlighting an average dissolved As concentration (<0.45 μm) of 2.7 ± 0.9 μg⋅L(-1), which is significantly higher than the world-average baseline for river water (0.83 μg⋅L(-1)). Taking the average annual discharge (49.4 m(3)⋅s(-1)) into account and the As levels in the dissolved phase and in deposits of the Var River, dissolved As input into the Mediterranean Sea would be 4. 2± 1.4 tons⋅year(-1) which represents 59% of the total As flux. This study also reveals a probable non-conservative As behaviour, i.e., possible transfer between aqueous and solid phases, during the mixing of the Var River with a tributary.

  1. Dissolved and particulate trace metal micronutrients under the McMurdo Sound seasonal sea ice: basal sea ice communities as a capacitor for iron

    PubMed Central

    Noble, Abigail E.; Moran, Dawn M.; Allen, Andrew E.; Saito, Mak A.

    2013-01-01

    Dissolved and particulate metal concentrations are reported from three sites beneath and at the base of the McMurdo Sound seasonal sea ice in the Ross Sea of Antarctica. This dataset provided insight into Co and Mn biogeochemistry, supporting a previous hypothesis for water column mixing occurring faster than scavenging. Three observations support this: first, Mn-containing particles with Mn/Al ratios in excess of the sediment were present in the water column, implying the presence of bacterial Mn-oxidation processes. Second, dissolved and labile Co were uniform with depth beneath the sea ice after the winter season. Third, dissolved Co:PO3−4 ratios were consistent with previously observed Ross Sea stoichiometry, implying that over-winter scavenging was slow relative to mixing. Abundant dissolved Fe and Mn were consistent with a winter reserve concept, and particulate Al, Fe, Mn, and Co covaried, implying that these metals behaved similarly. Elevated particulate metals were observed in proximity to the nearby Islands, with particulate Fe/Al ratios similar to that of nearby sediment, consistent with a sediment resuspension source. Dissolved and particulate metals were elevated at the shallowest depths (particularly Fe) with elevated particulate P/Al and Fe/Al ratios in excess of sediments, demonstrating a sea ice biomass source. The sea ice biomass was extremely dense (chl a >9500 μg/L) and contained high abundances of particulate metals with elevated metal/Al ratios. A hypothesis for seasonal accumulation of bioactive metals at the base of the McMurdo Sound sea ice by the basal algal community is presented, analogous to a capacitor that accumulates iron during the spring and early summer. The release and transport of particulate metals accumulated at the base of the sea ice by sloughing is discussed as a potentially important mechanism in providing iron nutrition during polynya phytoplankton bloom formation and could be examined in future oceanographic

  2. Dissolved and particulate trace metal micronutrients under the McMurdo Sound seasonal sea ice: basal sea ice communities as a capacitor for iron

    NASA Astrophysics Data System (ADS)

    Noble, Abigail; Saito, Mak; Moran, Dawn; Allen, Andrew

    2013-10-01

    Dissolved and particulate metal concentrations are reported from three sites beneath and at the base of the McMurdo Sound seasonal sea ice in the Ross Sea of Antarctica. This dataset provided insight into Co and Mn biogeochemistry, supporting a previous hypothesis for water column mixing occurring faster than scavenging. Three observations support this: first, Mn-containing particles with Mn/Al ratios in excess of the sediment were present in the water column, implying the presence of bacterial Mn-oxidation processes. Second, dissolved and labile Co were uniform with depth beneath the sea ice after the winter season. Third, dissolved Co:PO43- ratios were consistent with previously observed Ross Sea stoichiometry, implying that over-winter scavenging was slow relative to mixing. Abundant dissolved Fe and Mn were consistent with a winter reserve concept, and particulate Al, Fe, Mn, and Co covaried, implying that these metals behaved similarly. Elevated particulate metals were observed in proximity to the nearby Islands, with particulate Fe/Al ratios similar to that of nearby sediment, consistent with a sediment resuspension source. Dissolved and particulate metals were elevated at the shallowest depths (particularly Fe) with elevated particulate P/Al and Fe/Al ratios in excess of sediments, demonstrating a sea ice biomass source. The sea ice biomass was extremely dense (chl a >9500 μg/L) and contained high abundances of particulate metals with elevated metal/Al ratios. A hypothesis for seasonal accumulation of bioactive metals at the base of the McMurdo Sound sea ice by the basal algal community is presented, analogous to a capacitor that accumulates iron during the spring and early summer. The release and transport of particulate metals accumulated at the base of the sea ice by sloughing is discussed as a potentially important mechanism in providing iron nutrition during polynya phytoplankton bloom formation and could be examined in future oceanographic expeditions.

  3. Spatial variability of dissolved phosphorous concentrations and alkaline phosphatase activity in the East China Sea

    NASA Astrophysics Data System (ADS)

    Liu, H.; Chang, J.; Ho, T.; Gong, G.

    2010-12-01

    The concentrations of dissolved inorganic phosphorus (DIP) and alkaline phosphatase activity (APA) have been determined at about 25 sampling stations in the East China Sea since 2003. The stations are mainly distributed from the Changjiang river mouth to northern Taiwan and east to the shelf break. In addition to the Changjiang discharge, we have found a specific nutrient source around a coastal site (122° 2’30’’ E, 28° 40’ N). Elevated DIP and nitrate concentrations have been constantly observed around the sampling station for 8 years, where the surface DIP concentrations are generally around 0.3 µM. The nutrient source may either originate from ground water discharge or coastal upwelling, where lower temperature has been observed in the water column around the station. In general, APA has been negatively correlated with DIP concentrations in the studies sites, with lowest APA around the high DIP station and the Changjiang river mouth.

  4. Preliminary estimates of benthic fluxes of dissolved metals in Coeur d'Alene Lake, Idaho

    USGS Publications Warehouse

    Balistrieri, L.S.

    1998-01-01

    This report presents porewater and selected water column data collected from Coeur d'Alene Lake in September of 1992. Despite probable oxidation of the porewater samples during collection and handling, these data are used to calculate molecular diffusive fluxes of dissolved metals (that is, Zn, Pb, Cu, and Mn) across the sediment-water interface. While these data and calculations provide preliminary information on benthic metal fluxes in Coeur d'Alene Lake, further work is needed to verify their direction and magnitude. The benthic flux calculations indicate that the sediment is generally a source of dissolved Zn, Cu, Mn, and, possibly, Pb to the overlying water column. These benthic fluxes are compared with two other major sources of metals to Coeur d'Alene Lake-the Coeur d'Alene and St. Joe Rivers. Comparisons indicate that benthic fluxes of Zn, Pb, and Cu are generally less than half of the fluxes of these metals into the lake from the Coeur d'Alene River. However, in a few cases, the calculated benthic metal fluxes exceed the Coeur d'Alene River fluxes. Benthic fluxes of Zn and, possibly, Pb may be greater than the corresponding metal fluxes from the St. Joe River. These results have implications for changes in the relative importance of metal sources to the lake as remediation activities in the Coeur d'Alene River basin proceed.

  5. Distribution of dissolved and particulate radiocesium concentrations along rivers and the relations between radiocesium concentration and deposition after the nuclear power plant accident in Fukushima.

    PubMed

    Tsuji, Hideki; Yasutaka, Tetsuo; Kawabe, Yoshishige; Onishi, Takeo; Komai, Takeshi

    2014-09-01

    This study involved measurement of concentrations of dissolved and particulate radiocesium ((134)Cs and (137)Cs) in river water, and determination of the quantitative relations between the amount of deposited (137)Cs and (137)Cs concentrations in river waters after the Fukushima Daiichi nuclear power plant accident. First, the current concentrations of dissolved and particulate (134)Cs·(137)Cs were determined in a river watershed from 20 sampling locations in four contaminated rivers (Abukuma, Kuchibuto, Shakado, and Ota). Distribution characteristics of different (137)Cs forms varied with rivers. Moreover, a higher dissolved (137)Cs concentration was observed at the sampling location where the (137)Cs deposition occurred much more heavily. In contrast, particulate (137)Cs concentration along the river was quite irregular, because fluctuations in suspended solids concentrations occur easily from disturbance and heavy precipitation. A similar tendency with dissolved (137)Cs distribution was observed for the (137)Cs concentration per unit weight of suspended solids. Regression analysis between deposited (137)Cs and dissolved/particulate (137)Cs concentrations was performed for the four rivers. The results showed a strong correlation between deposited (137)Cs and dissolved (137)Cs, and a relatively weak correlation between deposited (137)Cs and particulate (137)Cs concentration for each river. However, if the particulate (137)Cs concentration was converted to (137)Cs concentration per unit weight of suspended solid, the values showed a strong correlation with deposited (137)Cs.

  6. Dissolved organic matter concentration and quality influences upon structure and function of freshwater microbial communities.

    PubMed

    Docherty, Kathryn M; Young, Katherine C; Maurice, Patricia A; Bridgham, Scott D

    2006-10-01

    Past studies have suggested that the concentration and quality of dissolved organic matter (DOM) may influence microbial community structure. In this study, we cross-inoculated the bacterial communities from two streams and a dystrophic lake that varied in DOM concentration and chemistry, to yield nine fully crossed treatments. We measured dissolved organic carbon (DOC) concentration and heterotrophic microbial community productivity throughout a 72-h incubation period, characterized DOM quality by molecular weight, and determined microbial community structure at the initial and final time points. Our results indicate that all bacterial inoculate sources had similar effects upon DOC concentration and DOM quality, regardless of the DOM source. These effects included an overall decrease in DOM M (W) and an initial period of DOC concentration variability between 0-24h. In contrast, microbial communities and their metabolic rates converged to profiles that reflected the DOM source upon which they were growing, regardless of the initial bacterial inoculation. The one exception was that the bacterial community from the low-concentration and low-molecular-weight DOM source exhibited a greater denaturing gradient gel electrophoresis (DGGE) band richness when grown in its own DOM source than when grown in the highest concentration and molecular weight DOM source. This treatment also exhibited a higher rate of productivity. In general, our data suggest that microbial communities are selected by the DOM sources to which they are exposed. A microbial community will utilize the low-molecular-weight (or labile) DOM sources as well as parts of the high-molecular-weight (refractory) DOM, until a community develops that can efficiently metabolize the more abundant high-molecular-weight source. This experiment examines some of the complex interactions between microbial community selection and the combined factors of DOM quality and concentration. Our data suggest that the roles of

  7. The concentrations, appearance and taste of nine sedating drugs dissolved in four different beverages.

    PubMed

    Olsen, Vigdis; Gustavsen, Ingebjørg; Bramness, Jørgen G; Hasvold, Inger; Karinen, Ritva; Christophersen, Asbjørg S; Mørland, Jørg

    2005-07-16

    Sedating drugs are reported to be used in cases where people have been drugged unwittingly. In the present experiments we studied whether nine sedating medicinal drugs would dissolve in four different beverages to reach concentrations which could possibly cause impairment and whether the drugs altered the appearance and taste of the beverages. Nine sedating medicinal drugs were added separately to water, beer, Coca-Cola and ethanol. Drug concentrations were measured 5, 10, 20 and 40 min after spiking. The amount of drug in one swallow (50 mL) was calculated. Appearance and taste were recorded after 10 min. Flunipam, Sobril, Valium and Xanor dissolved faster than Rohypnol, Imovane, Somadril, Rivotril and Dolcontin. Ten minutes after adding Flunipam, Sobril, Imovane (in beer and Coca-Cola), Valium and Xanor, the concentrations had reached more than 50% of maximum theoretical concentration. Most of the drugs caused sediment, pieces and/or turbidity in one or more of the beverages. Some of the solutions were dyed from added Rohypnol (turquoise or green), Dolcontin (red) and Valium (yellow). Flunipam and Valium caused extensive frothing in beer. The tastes of Imovane and Somadril were distinct in all the beverages, while the taste of other drug solutions was less distinct. The ingestion of all solutions could probably have caused impairment. All the nine drugs were, however, apparent to the consumer from the altered appearance and/or taste of the beverages.

  8. Rheological behaviors in the regimes from dilute to concentrated in cellulose solutions dissolved at low temperature.

    PubMed

    Lue, Ang; Zhang, Lina

    2009-05-13

    Cellulose was dissolved rapidly in 9.5 wt.-% NaOH/4.5 wt.-% thiourea aqueous solution pre-cooled to -5 degrees C to prepare cellulose solution with different concentrations. The rheological properties of the cellulose solutions in wide concentration regimes from dilute (0.008 wt.-%) to concentrated (4.0 wt.-%) at 25 degrees C were investigated. On the basis of data from the steady-shear flow test, the critical overlap (c*), the entanglement (c(e)) and the gel (c(g)) concentrations of the cellulose solution at 25 degrees C were determined, respectively, to be 0.10 wt.-%, 0.53 wt.-% and 2.50 wt.-%, in accordance with the results of storage modulus (G') versus c by dynamic test. Moreover, the Cox-Merz deviation at relatively low concentrations was in good agreement with the micro-gel particles in dilute regime. As the cellulose concentration increased, a homogeneous 3-dimensional network formed in the cellulose solution in the concentrated regime, and further increasing of the concentration led to micro-phase separation as determined by the time-temperature superposition (tTS). So far, this complex cellulose solution has been successfully described by the concentration regime theory for the first time, and the relatively molecular morphologies in each regime have been determined, providing useful information for the applications of the cellulose solution systems. PMID:19039777

  9. New method for the direct determination of dissolved Fe(III) concentration in acid mine waters

    USGS Publications Warehouse

    To, T.B.; Nordstrom, D.K.; Cunningham, K.M.; Ball, J.W.; McCleskey, R.B.

    1999-01-01

    A new method for direct determination of dissolved Fe(III) in acid mine water has been developed. In most present methods, Fe(III) is determined by computing the difference between total dissolved Fe and dissolved Fe(II). For acid mine waters, frequently Fe(II) >> Fe(III); thus, accuracy and precision are considerably improved by determining Fe(III) concentration directly. The new method utilizes two selective ligands to stabilize Fe(III) and Fe(II), thereby preventing changes in Fe reduction-oxidation distribution. Complexed Fe(II) is cleanly removed using a silica-based, reversed-phase adsorbent, yielding excellent isolation of the Fe(III) complex. Iron(III) concentration is measured colorimetrically or by graphite furnace atomic absorption spectrometry (GFAAS). The method requires inexpensive commercial reagents and simple procedures that can be used in the field. Calcium(II), Ni(II), Pb(II), AI(III), Zn(II), and Cd(II) cause insignificant colorimetric interferences for most acid mine waters. Waters containing >20 mg of Cu/L could cause a colorimetric interference and should be measured by GFAAS. Cobalt(II) and Cr(III) interfere if their molar ratios to Fe(III) exceed 24 and 5, respectively. Iron(II) interferes when its concentration exceeds the capacity of the complexing ligand (14 mg/L). Because of the GFAAS elemental specificity, only Fe(II) is a potential interferent in the GFAAS technique. The method detection limit is 2 ??g/L (40 nM) using GFAAS and 20 ??g/L (0.4 ??M) by colorimetry.A new method for direct determination of dissolved Fe(III) in acid mine water has been developed. In most present methods, Fe(III) is determined by computing the difference between total dissolved Fe and dissolved Fe(II). For acid mine waters, frequently Fe(II)???Fe(III); thus, accuracy and precision are considerably improved by determining Fe(III) concentration directly. The new method utilizes two selective ligands to stabilize Fe(III) and Fe(II), thereby preventing changes

  10. Trends in nitrate and dissolved-solids concentrations in ground water, Carson Valley, Douglas County, Nevada, 1985-2001

    USGS Publications Warehouse

    Rosen, Michael R.

    2003-01-01

    Analysis of trends in nitrate and total dissolved-solids concentrations over time in Carson Valley, Nevada, indicates that 56 percent of 27 monitoring wells that have long-term records of nitrate concentrations show increasing trends, 11 percent show decreasing trends, and 33 percent have not changed. Total dissolved-solids concentrations have increased in 52 percent of these wells and are stable in 48 percent. None of these wells show decreasing trends in total dissolved-solids concentrations. The wells showing increasing trends in nitrate and total dissolved-solids concentrations were always in areas that use septic waste-disposal systems. Therefore, the primary cause of these increases is likely the increase in septic-tank usage over the past 40 years.

  11. Removal of inorganic mercury and methylmercury from surface waters following coagulation of dissolved organic matter with metal-based salts

    USGS Publications Warehouse

    Henneberry, Y.K.; Kraus, T.E.C.; Fleck, J.A.; Krabbenhoft, D.P.; Bachand, P.M.; Horwath, W.R.

    2011-01-01

    The presence of inorganic mercury (IHg) and methylmercury (MeHg) in surface waters is a health concern worldwide. This study assessed the removal potential use of metal-based coagulants as a means to remove both dissolved IHg and MeHg from natural waters and provides information regarding the importance of Hg associations with the dissolved organic matter (DOM) fraction and metal hydroxides. Previous research indicated coagulants were not effective at removing Hg from solution; however these studies used high concentrations of Hg and did not reflect naturally occurring concentrations of Hg. In this study, water collected from an agricultural drain in the Sacramento-San Joaquin Delta was filtered to isolate the dissolved organic matter (DOM) fraction. The DOM was then treated with a range of coagulant doses to determine the efficacy of removing all forms of Hg from solution. Three industrial-grade coagulants were tested: ferric chloride, ferric sulfate, and polyaluminum chloride. Coagulation removed up to 85% of DOM from solution. In the absence of DOM, all three coagulants released IHg into solution, however in the presence of DOM the coagulants removed up to 97% of IHg and 80% of MeHg. Results suggest that the removal of Hg is mediated by DOM-coagulant interactions. There was a preferential association of IHg with the more aromatic, higher molecular weight fraction of DOM but no such relationship was found for MeHg. This study offers new fundamental insights regarding large-scale removal of Hg at environmentally relevant regarding large-scale removal of Hg at environmentally relevant concentrations.

  12. The impact of seasonality and elevation on dissolved greenhouse gas concentrations in a northeastern Wyoming watershed

    NASA Astrophysics Data System (ADS)

    Kuhn, C.; Bettigole, C.; Raymond, P. A.; Glick, H.; Seegmiller, L.; Oliver, C.; Khadka, A.; Routh, D.

    2014-12-01

    Quantification of river and stream contributions to global carbon emission budgets using field-based measurements is key to understanding how freshwater streams act as conduits between terrestrial and atmospheric carbon pools. In order to better characterize drivers of this process, this study quantifies: a) emissions of carbon dioxide and methane from a semi-arid, high plains riverine system with montaine headwaters in order to establish baseline data for the watershed; b) the impact of stream order, seasonality and elevation on dissolved gas concentrations to better understand the spatial and temporal heterogeneity of dissolved carbon gases. To achieve the latter objective, we conducted field surveys in first and second order streams in the Clear Creek drainage of the Powder River Basin watershed. We took direct measurements of stream gases using headspace sampling at thirty sites along an elevation gradient ranging from 1,203-3,346 meters. We also intensely monitored five transects throughout the descending limb of spring runoff (June 8th-August 12th) to investigate how temperature and discharge volume impact greenhouse gas concentrations. Clear Creek, located in northeastern Wyoming, is approximately 118.4 km long with a drainage area of 2,968 km2. The creek flows east out of Bighorn National Forest where it turns northeast to converge with the Powder River about ten miles before the Montana border. The stream straddles the Middle Rockies and Northwestern Great Plains ecoregions and experiences an abrupt shift in soil type, riparian vegetation, underlying geology and stream geometry as the stream exits the mountains and enters the agricultural alluvial floodplain. These site specific biological and physical changes along the elevation gradient affect dissolved greenhouse gas concentrations.

  13. Influence of land use on total suspended solid and dissolved ion concentrations: Baton Rouge, Louisiana area

    NASA Astrophysics Data System (ADS)

    Carlson, D.

    2015-03-01

    Past studies in the Baton Rouge, Louisiana area considered streamwater quality during storm events but ignored water quality during low flow periods. This study includes determination of streamwater quality during low flow time periods for none watersheds in East Baton Rouge Parish, Louisiana. These samples were collected during dry-low flow periods as indicated by water levels at USGS stream gauging sites for each stream. Chemical analysis for ions was completed using colorimeters and gravimetric analysis for total dissolved solids (TDS) and total suspended solids (TSS). Land use appears to impact concentrations of ions, TDS and TSS in a variety of ways during periods of low flow. The two most rural watersheds, which are mainly underdeveloped, have higher concentrations of Fe and Mn. By contrast the three most urban watersheds, that are mainly commercial, industrial or residential, have higher concentrations of Si, SO4 and TDS.

  14. Frequency-duration analysis of dissolved-oxygen concentrations in two southwestern Wisconsin streams

    USGS Publications Warehouse

    Greb, Steven R.; Graczyk, David J.

    2007-01-01

    Historically, dissolved-oxygen (DO) data have been collected in the same manner as other water-quality constituents, typically at infrequent intervals as a grab sample or an instantaneous meter reading. Recent years have seen an increase in continuous water-quality monitoring with electronic dataloggers. This new technique requires new approaches in the statistical analysis of the continuous record. This paper presents an application of frequency-duration analysis to the continuous DO records of a cold and a warm water stream in rural southwestern Wisconsin. This method offers a quick, concise way to summarize large time-series data bases in an easily interpretable manner. Even though the two streams had similar mean DO concentrations, frequency-duration analyses showed distinct differences in their DO-concentration regime. This type of analysis also may be useful in relating DO concentrations to biological effects and in predicting low DO occurrences.

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

    NASA Astrophysics Data System (ADS)

    Prasetyaningrum, A.; Ratnawati, Jos, B.

    2015-12-01

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

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

    SciTech Connect

    Prasetyaningrum, A. Ratnawati,; Jos, B.

    2015-12-29

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

  17. Concentrations of dissolved oxygen in the lower Puyallup and White rivers, Washington, August and September 2000 and 2001

    USGS Publications Warehouse

    Ebbert, J.C.

    2002-01-01

    The U.S. Geological Survey, Washington State Department of Ecology, and Puyallup Tribe of Indians conducted a study in August and September 2001 to assess factors affecting concentrations of dissolved oxygen in the lower Puyallup and White Rivers, Washington. The study was initiated because observed concentrations of dissolved oxygen in the lower Puyallup River fell to levels ranging from less than 1 milligram per liter (mg/L) to about 6 mg/L on several occasions in September 2000. The water quality standard for the concentration of dissolved oxygen in the Puyallup River is 8 mg/L.This study concluded that inundation of the sensors with sediment was the most likely cause of the low concentrations of dissolved oxygen observed in September 2000. The conclusion was based on (1) knowledge gained when a dissolved-oxygen sensor became covered with sediment in August 2001, (2) the fact that, with few exceptions, concentrations of dissolved oxygen in the lower Puyallup and White Rivers did not fall below 8 mg/L in August and September 2001, and (3) an analysis of other mechanisms affecting concentrations of dissolved oxygen.The analysis of other mechanisms indicated that they are unlikely to cause steep declines in concentrations of dissolved oxygen like those observed in September 2000. Five-day biochemical oxygen demand ranged from 0.22 to 1.78 mg/L (mean of 0.55 mg/L), and river water takes only about 24 hours to flow through the study reach. Photosynthesis and respiration cause concentrations of dissolved oxygen in the lower Puyallup River to fluctuate as much as about 1 mg/L over a 24-hour period in August and September. Release of water from Lake Tapps for the purpose of hydropower generation often lowered concentrations of dissolved oxygen downstream in the White River by about 1 mg/L. The effect was smaller farther downstream in the Puyallup River at river mile 5.8, but was still observable as a slight decrease in concentrations of dissolved oxygen caused by

  18. Application of passive sampling for measuring dissolved concentrations of organic contaminants in the water column at three marine superfund sites

    EPA Science Inventory

    At contaminated sediment sites, including U.S. EPA Superfund sites, it is critical to measure water column concentrations of freely dissolved contaminants to understand the complete exposure of aquatic organisms to hydrophobic organic contaminants (HOCs). However, historically a...

  19. Concentrations of dissolved herbicides and pharmaceuticals in a small river in Luxembourg.

    PubMed

    Meyer, Berenike; Pailler, Jean-Yannick; Guignard, Cédric; Hoffmann, Lucien; Krein, Andreas

    2011-09-01

    Urban and agricultural areas affect the hydraulic patterns as well as the water quality of receiving drainage systems, especially of catchments smaller than 50 km(2). Urban runoff is prone to contamination due to pollutants like pesticides or pharmaceuticals. Agricultural areas are possible sources of nutrient and herbicide contamination for receiving water bodies. The pollution is derived from leaching by subsurface flow, as well as wash-off and erosion caused by surface runoff. In the Luxembourgish Mess River catchment, the pharmaceutical and pesticide concentrations are comparable with those detected by other authors in different river systems worldwide. Some investigated pesticide concentrations infringe current regulations. The maximum allowable concentration for diuron of 1.8 μg l( - 1) is exceeded fourfold by measured 7.41 μg l( - 1) in a flood event. The load of dissolved pesticides reaching the stream gauge is primarily determined by the amount applied to the surfaces within the catchment area. Storm water runoff from urban areas causes short-lived but high-pollutant concentrations and moderate loads, whereas moderate concentrations and high loads are representative for agricultural inputs to the drainage system. Dissolved herbicides, sulfonamides, tetracyclines, analgesics and hormones can be used as indicators to investigate runoff generation processes, including inputs from anthropogenic sources. The measurements prove that the influence of kinematic wave effects on the relationship between hydrograph and chemographs should not be neglected in smaller basins. The time lag shows that it is not possible to connect analysed substances of defined samples to the corresponding section of the hydrograph.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  1. Variations in dissolved organic nitrogen concentration in biofilters with different media during drinking water treatment.

    PubMed

    Zhang, Huining; Zhang, Kefeng; Jin, Huixia; Gu, Li; Yu, Xin

    2015-11-01

    Dissolved organic nitrogen (DON) is potential precursor of disinfection byproducts (DBPs), especially nitrogenous DBPs. In this study, we investigated the impact of biofilters on DON concentration changes in a drinking water plant. A small pilot plant was constructed next to a sedimentation tank in a drinking water plant and included activated carbon, quartz sand, anthracite, and ceramsite biofilters. As the biofilter layer depth increased, the DON concentration first decreased and then increased, and the variation in DON concentration differed among the biofilters. In the activated carbon biofilter, the DON concentration was reduced by the largest amount in the first part of the column and increased by the largest amount in the second part of the column. The biomass in the activated carbon filter was less than that in the quartz sand filter in the upper column. The heterotrophic bacterial proportion among bacterial flora in the activated carbon biofilter was the largest, which might be due to the significant reduction in DON in the first part of the column. Overall, the results indicate that the DON concentration in biofiltered water can be controlled via the selection of appropriate biofilter media. We propose that a two-layer biofilter with activated carbon in the upper layer and another media type in the lower layer could best reduce the DON concentration.

  2. Seasonal variations in concentration and lability of dissolved organic carbon in Tokyo Bay

    NASA Astrophysics Data System (ADS)

    Kubo, A.; Yamamoto-Kawai, M.; Kanda, J.

    2015-01-01

    Concentrations of recalcitrant and bioavailable dissolved organic carbon (DOC) and their seasonal variations were investigated at three stations in Tokyo Bay, Japan, and in two freshwater sources flowing into the bay. On average, recalcitrant DOC (RDOC), as a remnant of DOC after 150 days of bottle incubation, accounted for 78% of the total DOC in Shibaura sewage treatment plant (STP) effluent, 67% in the upper Arakawa River water, 66% in the lower Arakawa River water, and 78% in surface bay water. Bioavailable DOC (BDOC) concentrations, defined as DOC minus RDOC, were lower than RDOC at all stations. In freshwater environments, RDOC concentrations were almost constant throughout the year. In the bay, RDOC was higher during spring and summer than in autumn and winter because of freshwater input and biological production. The relative concentration of RDOC in the bay derived from phytoplankton, terrestrial, and open-oceanic waters was estimated to be 8-10, 21-32, and 59-69%, respectively, based on multiple regression analysis of RDOC, salinity, and chl a. In addition, comparison with previous data from 1972 revealed that concentrations of RDOC and BDOC have decreased by 33 and 74% at freshwater sites and 39 and 76% in Tokyo Bay, while the ratio of RDOC to DOC has increased. The change in DOC concentration and composition was probably due to increased amounts of STP effluent entering the system. Tokyo Bay exported mostly RDOC to the open ocean because of the remineralization of BDOC.

  3. Fast-freezing with liquid nitrogen preserves bulk dissolved organic matter concentrations, but not its composition

    NASA Astrophysics Data System (ADS)

    Thieme, Lisa; Graeber, Daniel; Kaupenjohann, Martin; Siemens, Jan

    2016-08-01

    Freezing can affect concentrations and spectroscopic properties of dissolved organic matter (DOM) in water samples. Nevertheless, water samples are regularly frozen for sample preservation. In this study we tested the effect of different freezing methods (standard freezing at -18 °C and fast-freezing with liquid nitrogen) on DOM concentrations measured as organic carbon (DOC) concentrations and on spectroscopic properties of DOM from different terrestrial ecosystems (forest and grassland). Fresh and differently frozen throughfall, stemflow, litter leachate and soil solution samples were analyzed for DOC concentrations, UV-vis absorption and fluorescence excitation-emission matrices combined with parallel factor analysis (PARAFAC). Fast-freezing with liquid nitrogen prevented a significant decrease of DOC concentrations observed after freezing at -18 °C. Nonetheless, the share of PARAFAC components 1 (EXmax < 250 nm (340 nm), EXmax: 480 nm) and 2 (EXmax: 335 nm, EXmax: 408 nm) to total fluorescence and the humification index (HIX) decreased after both freezing treatments, while the shares of component 3 (EXmax: < 250 nm (305 nm), EXmax: 438 nm) as well as SUVA254 increased. The contribution of PARAFAC component 4 (EXmax: 280 nm, EXmax: 328 nm) to total fluorescence was not affected by freezing. We recommend fast-freezing with liquid nitrogen for preservation of bulk DOC concentrations of samples from terrestrial sources, whereas immediate measuring is preferable to preserve spectroscopic properties of DOM.

  4. Mobilization of heavy metals and arsenic in polluted wetland soils and its dependence on dissolved organic matter.

    PubMed

    Kalbitz, K; Wennrich, R

    1998-01-01

    The wetland soils of the Mulde river in the industrial district of Bitterfeld-Wolfen (Germany) are highly contaminated with heavy metals and arsenic. We studied the mobility of accumulated heavy metals and arsenic and the influence of dissolved organic matter (DOM) on element mobility. Undisturbed soil cores were taken from five different sites to represent a wide range of heavy-metal contamination, soil properties and dissolved organic carbon (DOC) concentrations. The acid-soluble concentrations (mostly equal to the total content) were up to 1100 mg kg-1 for Zn, 800 mg kg-1 for Cr, 364 mg kg-1 for Cu, 265 mg kg-1 for As and 37 mg kg-1 for Hg, depending on the sampling site. Percolation experiments using small lysimeters with undisturbed topsoil cores illustrated a considerable mobilization of Zn, Cd, Cu, Cr and Hg, depending on soil properties. Up to 80 micrograms l-1 Cd, 8 mg 1-1 Zn, 130 micrograms l-1 Cr, 160 micrograms l-1 Cu and 7 micrograms l-1 Hg were detected in the soil percolates. Arsenic mobilization was low. The concentration of Cr, Hg, Cu and As in the soil percolates was positively correlated with DOM. Besides the element content (mobile or acid-soluble), soil pH and soil characteristics describing the soil potential for heavy-metal adsorption (clay, oxides, cation exchange capacity), the DOC concentration in the soil solution should be known to access the potential mobilization of Hg, Cr, Cu and As. In contrast, Cd and Zn mobilization depends on soil pH and mobile element content, but not on DOM. Additional studies on two soil profiles (down to 1.5 m) confirmed the translocation of heavy metals from the highly contaminated topsoil into deeper soil horizons and into the groundwater and the influence of DOM as revealed with the percolation experiment. Our results also showed that DOM is of minor importance on the mobilization of heavy metals in soils with a low soil pH (< 4.5).

  5. Effects of reduced dissolved oxygen concentrations on physiology and fluorescence of hermatypic corals and benthic algae.

    PubMed

    Haas, Andreas F; Smith, Jennifer E; Thompson, Melissa; Deheyn, Dimitri D

    2014-01-01

    While shifts from coral to seaweed dominance have become increasingly common on coral reefs and factors triggering these shifts successively identified, the primary mechanisms involved in coral-algae interactions remain unclear. Amongst various potential mechanisms, algal exudates can mediate increases in microbial activity, leading to localized hypoxic conditions which may cause coral mortality in the direct vicinity. Most of the processes likely causing such algal exudate induced coral mortality have been quantified (e.g., labile organic matter release, increased microbial metabolism, decreased dissolved oxygen availability), yet little is known about how reduced dissolved oxygen concentrations affect competitive dynamics between seaweeds and corals. The goals of this study were to investigate the effects of different levels of oxygen including hypoxic conditions on a common hermatypic coral Acropora yongei and the common green alga Bryopsis pennata. Specifically, we examined how photosynthetic oxygen production, dark and daylight adapted quantum yield, intensity and anatomical distribution of the coral innate fluorescence, and visual estimates of health varied with differing background oxygen conditions. Our results showed that the algae were significantly more tolerant to extremely low oxygen concentrations (2-4 mg L(-1)) than corals. Furthermore corals could tolerate reduced oxygen concentrations, but only until a given threshold determined by a combination of exposure time and concentration. Exceeding this threshold led to rapid loss of coral tissue and mortality. This study concludes that hypoxia may indeed play a significant role, or in some cases may even be the main cause, for coral tissue loss during coral-algae interaction processes.

  6. Effects of reduced dissolved oxygen concentrations on physiology and fluorescence of hermatypic corals and benthic algae.

    PubMed

    Haas, Andreas F; Smith, Jennifer E; Thompson, Melissa; Deheyn, Dimitri D

    2014-01-01

    While shifts from coral to seaweed dominance have become increasingly common on coral reefs and factors triggering these shifts successively identified, the primary mechanisms involved in coral-algae interactions remain unclear. Amongst various potential mechanisms, algal exudates can mediate increases in microbial activity, leading to localized hypoxic conditions which may cause coral mortality in the direct vicinity. Most of the processes likely causing such algal exudate induced coral mortality have been quantified (e.g., labile organic matter release, increased microbial metabolism, decreased dissolved oxygen availability), yet little is known about how reduced dissolved oxygen concentrations affect competitive dynamics between seaweeds and corals. The goals of this study were to investigate the effects of different levels of oxygen including hypoxic conditions on a common hermatypic coral Acropora yongei and the common green alga Bryopsis pennata. Specifically, we examined how photosynthetic oxygen production, dark and daylight adapted quantum yield, intensity and anatomical distribution of the coral innate fluorescence, and visual estimates of health varied with differing background oxygen conditions. Our results showed that the algae were significantly more tolerant to extremely low oxygen concentrations (2-4 mg L(-1)) than corals. Furthermore corals could tolerate reduced oxygen concentrations, but only until a given threshold determined by a combination of exposure time and concentration. Exceeding this threshold led to rapid loss of coral tissue and mortality. This study concludes that hypoxia may indeed play a significant role, or in some cases may even be the main cause, for coral tissue loss during coral-algae interaction processes. PMID:24482757

  7. Temporal Variability of Stemflow Dissolved Organic Carbon (DOC) Concentrations and Quality from Morphologically Contrasting Deciduous Canopies

    NASA Astrophysics Data System (ADS)

    van Stan, J. T.; Levia, D. F.; Inamdar, S. P.; Mitchell, M. J.; Mage, S. M.

    2010-12-01

    Dissolved organic carbon (DOC) inputs from canopy-derived hydrologic fluxes play a significant role in the terrestrial carbon budgets of forested ecosystems. However, no studies known to the authors have examined the variability of both DOC concentrations and quality for stemflow across time scales, nor has any study to date evaluated the effects of canopy structure on stemflow DOC characteristics. This investigation seeks to rectify this knowledge gap by examining the variability of stemflow DOC concentrations and quality across contrasting canopy morphologies and time scales (seasonal, storm and intrastorm). Bulk and intrastorm stemflow samples from a less dense, rough-barked, more plagiophile (Liriodendron tulipifera L. (tulip poplar)) and a denser, thin-barked, more erectophile (Fagus grandifolia Ehrh. (American beech)) canopy were collected and analyzed for DOC quality using metrics derived from UV-vis spectroscopy (E2:E3 ratio, SUVA254, select spectral slope (S), and spectral slope ratios (SR)). Our results suggest that stemflow DOC concentrations and quality change as crown architectural traits enhance or diminish hydrologic retention time within the canopy. The architecture of L. tulipifera canopies likely retards the flow of intercepted water, increasing chemical exchange with bark and foliar surfaces. UV-vis metrics indicated that this increased chemical exchange, particularly with bark surfaces, generally enhanced aromatic hydrocarbon content and increased molecular weight. Because leaf presence influenced DOC quality, stemflow DOC characteristics also varied seasonally in response to canopy condition. At the inter- and intrastorm scale, stemflow DOC concentration and quality varied with meteorological and antecedent canopy conditions. Since recent studies have linked stemflow production to preferential subsurface transport of dissolved chemistries, trends in DOC speciation and fluxes described in this study may impact soil environments within wooded

  8. An Estimate of the Dissolved oxygen Concentration in Subglacial Lake Vostok

    NASA Astrophysics Data System (ADS)

    Lipenkov, V.; Istomin, V.; Bulat, S.; Raynaud, D.; Petit, J.

    2002-05-01

    The upper section of 3.5 km thick glacier ice overlying Lake Vostok is characterized by abundance of air bubbles trapped during pore closure near the surface of the ice sheet. As the pressure increases with depth, the air occluded in ice gradually transforms to mixed air clathrate hydrate. In the region of interest the bubble-to-hydrate transition is complete at about 1300 mbs below which depth most of the air (about 99%) in the ice sheet is located within hydrate crystals. The basal-ice melting prevails in the north of Lake Vostok and the ice accretion occurs in the south. The concentration of air in the melting glacier ice is typically about 113 mg l-1 (86 mg N2 L-1 + 27 mg O2 L-1), whereas that in accreted ice is nearly zero. This suggests a net transfer of the atmospheric air (in the form of gas hydrate) through the ice-sheet thickness to Lake Vostok water. Available laboratory data and thermodynamic models indicate that, under conditions appropriate to Lake Vostok, the air-hydrate crystals released from the melting ice will persist within the water body provided there is enough air present in the system for a hydrate phase to coexist with dissolved N2 and O2. Neglecting biogeochemical inputs and losses of dissolved gases we have calculated the solubility of nitrogen (2.25 103 mg L-1) and oxygen (1.3 103 mg L-1) in equilibrium with air hydrate in lake water. Accordingly, the dissolved oxygen concentration is predicted to be between 27 and 1.3 103 mg L-1 (compare to 15 mg O2 L-1 for standard conditions). Assuming a steady state and taking 20 kyr for the residence time of the lake water, we have estimated that a 630 kyr period is needed to reach the upper bond of the dissolved O2 concentration, which is a prerequisite for air hydrate stability in the lake. Metabolic consumption of oxygen in the lake could only make this transition longer. We also demonstrate that strong hydrate-forming gases such as CO2 and CH4, if present in the lake together with N2 and O2

  9. Impact of environmental factors on dissolved organic carbon concentrations in German bogs under grassland

    NASA Astrophysics Data System (ADS)

    Frank, Stefan; Tiemeyer, Bärbel; Freibauer, Annette

    2013-04-01

    Peatlands cover about 5% of Germany's land area. Agricultural use combined with drainage increases the greenhouse gas emissions and alters the dissolved organic carbon (DOC) concentrations in the soil- and groundwater of these ecosystems. Cycling of DOC is influenced by a complex interaction of environmental factors such as peat characteristics, groundwater level, meteorological conditions, pH-value and ionic strength. Reasons for elevated DOC concentrations are debated in literature, but only a few studies on the dynamic of DOC in raised bogs in Germany have been conducted so far. In Germany, raised bogs are mainly used as grassland. Therefore, five grassland study sites and one natural reference have been selected. The bog "Ahlenmoor" has a deep, medium to weakly decomposed peat layer. There, three study sites represent different land use intensities with a corresponding groundwater table (intensive grassland, extensive grassland, natural reference). The bog relict "Großes Moor" is characterised by a shallow amorphous peat layer, which is partly mixed with sand. There, three sites in an extensive grassland were chosen to study the effects of soil carbon concentrations (9 to 48 %) and groundwater levels. At each site, nine suction plates (three replicates in each depth) and three tensiometers were installed in 15, 30 and 60 cm. Soil water was sampled fortnightly from June 2011 to December 2012 and analysed for electrical conductivity, pH-value and DOC concentration. Compared to most literature values, DOC concentrations at our study sites were very high (on average, 197 to 55 mg/L). At the "Ahlenmoor", an increase in agricultural intensity and a lower groundwater table increases both the DOC concentrations and their variability in the soil water in order intensive grassland > extensive grassland > natural site. Surprisingly, soil carbon concentration and groundwater table gradients as investigated in the "Großes Moor" did only lead to minor differences in the

  10. Hydrologic control of dissolved organic matter concentration and quality in a semiarid artificially drained agricultural catchment

    NASA Astrophysics Data System (ADS)

    Bellmore, Rebecca A.; Harrison, John A.; Needoba, Joseph A.; Brooks, Erin S.; Kent Keller, C.

    2015-10-01

    Agricultural practices have altered watershed-scale dissolved organic matter (DOM) dynamics, including in-stream concentration, biodegradability, and total catchment export. However, mechanisms responsible for these changes are not clear, and field-scale processes are rarely directly linked to the magnitude and quality of DOM that is transported to surface water. In a small (12 ha) agricultural catchment in eastern Washington State, we tested the hypothesis that hydrologic connectivity in a catchment is the dominant control over the concentration and quality of DOM exported to surface water via artificial subsurface drainage. Concentrations of dissolved organic carbon (DOC) and humic-like components of DOM decreased while the Fluorescence Index and Freshness Index increased with depth through the soil profile. In drain discharge, these characteristics were significantly correlated with drain flow across seasons and years, with drain DOM resembling deep sources during low-flow and shallow sources during high flow, suggesting that DOM from shallow sources bypasses removal processes when hydrologic connectivity in the catchment is greatest. Assuming changes in streamflow projected for the Palouse River (which contains the study catchment) under the A1B climate scenario (rapid growth, dependence on fossil fuel, and renewable energy sources) apply to the study catchment, we project greater interannual variability in annual DOC export in the future, with significant increases in the driest years. This study highlights the variability in DOM inputs from agricultural soil to surface water on daily to interannual time scales, pointing to the need for a more nuanced understanding of agricultural impacts on DOM dynamics in surface water.

  11. Long term in situ monitoring of total dissolved iron concentrations on the MoMAR observatory

    NASA Astrophysics Data System (ADS)

    Laes-Huon, Agathe; Legrand, Julien; Tanguy, Virginie; Cathalot, Cecile; Blandin, Jérôme; Rolin, Jean-Francois; Sarradin, Pierre-Marie

    2015-04-01

    Nowadays the scientific community wants relevant monitoring with an increase in spatial and temporal distribution of key chemicals. The hydrothermal ecosystems characterized by strong physico-chemical gradients are also of particular interest as they present an unique fauna, sustained by microbial chemosynthesis. The characterization of the chemical environment in the hydrothermal vent ecosystems implies the use of in situ instrumentation which is a serious challenge in the marine environment (Prien et al. 2007). The CHEMINI (CHEmical MINIaturised analyser), presented here, is a chemical in situ analyser specialized for deep sea uses (Vuillemin et al. 2007). It was first deployed on the autonomous deep sea observatory MoMAR (Monitoring of the Mid-Atlantic Ridge, FIXO3, Fixed point Open Ocean Observatories) in 2010. The first part of the presentation will focus on the description of the CHEMINI, then on the results obtained on the MoMAR observatory during the last 4 years. CHEMINI, implemented on the TEMPO ecological module determined total dissolved iron concentrations associated with an optode and a temperature probe. Several months of total iron concentrations, of T°C and videos were recorded permitting the study of the temporal dynamics of faunal assemblages and their habitat on the Lucky strike vent (-1700m, Cuvelier et al. 2011). Long term in situ analysis of total dissolved iron (31st of August 2013 - 23rd of February 2014, [DFe] = 7.12 +- 2.11 µmol L-1, n = 519) at the Eiffel Tower edifice is presented in details. The daily analyzed in situ standard (25µmol.L-1) showed an excellent reproducibility (1.07%, n=522). CHEMINI was reliable, robust over time for in situ analysis. The averaged total dissolved iron concentrations for the 6 months period remain low but they correlated significantly with temperature showing a spectra frequency with a maximal contribution around 4-5 days for both variables. The analytical results will be commented and the future

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

    PubMed

    Koga, Masaaki; Yoshimura, Kazuhisa

    2012-07-01

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

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

    PubMed

    Koga, Masaaki; Yoshimura, Kazuhisa

    2012-07-01

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

  14. Metal concentrations in water and sediments from tourist beaches of Acapulco, Mexico.

    PubMed

    Jonathan, M P; Roy, P D; Thangadurai, N; Srinivasalu, S; Rodríguez-Espinosa, P F; Sarkar, S K; Lakshumanan, C; Navarrete-López, M; Muñoz-Sevilla, N P

    2011-04-01

    A survey on the metal concentrations (As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, V, Zn) in beach water and sediments is reported from the tourist destination of Acapulco city on the Pacific coast of Mexico. The concentration of dissolved trace metals (DTMs) in beach water and acid leachable trace metals (ALTMs) in sediments indicated that they are anthropogenic in nature due to the increased tourist activities in the crowded beach locations. The statistical analysis indicates Fe and Mn play a major role as metal scavengers in both the medium (water and sediment) and the higher value of other metals is site specific in the study area, indicating that they are transported from the local area. Comparison results suggest that the beach water quality has deteriorated more than the sediments and special care needs to be taken to restore the beach quality.

  15. The influence of size distribution on the particle concentration effect and trace metal partitioning in rivers

    SciTech Connect

    Benoit, G.; Rozan, T.F.

    1999-01-01

    The particle concentration effect (p.c.e.) is an unexpected decline in partition coefficients (K{sub d}) as suspended particulate matter (SPM) increases. This anomaly has been attributed to a variety of causes, but most often to the existence of colloidal forms of the adsorbate, which are included, in error, in the dissolved fraction when calculating K{sub d}. To test this hypothesis the authors have directly measured colloidal, macroparticulate, and truly dissolved metals (Cd, Cu, Pb, Zn, fe, Al, Mn, Ag) monthly for one year (6/96--7/97) in four Connecticut rivers having a range of ancillary biogeochemical characteristics. These include factors that re all likely to influence partitioning between dissolved and solid phases, such as DOC, pH, and competing cations. The p.c.e. is clearly evident in these rivers, and explicit consideration of colloidal metals eliminates or reduces this anomaly in nearly all cases. Furthermore, a substantial portion of metals occurs in the colloidal fraction, and the amount of colloidal metals increases with SPM. Both of these conditions are necessary for the colloidal model to explain the p.c.e.. Important differences are observed among river and metals, and in some cases systematic decreases in K{sub d} continue even when colloidal metals are taken in to account. This additional decrease can be eliminated by excluding large particles having negligible surface complexation sites. When corrections are applied for both colloids and large particles, K{sub d} values become truly constant.

  16. Dissolved organic matter conformation and its interaction with pyrene as affected by water chemistry and concentration.

    PubMed

    Pan, Bo; Ghosh, Saikat; Xing, Baoshan

    2008-03-01

    Water chemistry and concentration of dissolved organic matter (DOM) have been reported to affect DOM conformation and binding properties with hydrophobic organic contaminants (HOCs). However, relationship between DOM conformation and its binding properties remains unclear. We designed a multibag equilibration system (MBES) to investigate the variation of carbon-normalized sorption coefficients (K(DOC)) of pyrene at different DOM concentrations based on an identical free solute concentration at different pHs and in the presence of Al ions. In addition, we studied the conformation of DOM under different conditions via atomic force microscopy (AFM) imaging, dynamic light scattering, and zeta potential measurements. Zeta potential measurements indicated that intra- and intermolecular interaction was facilitated at low pH or with the presence of Al ions, and a more organized molecular aggregate (such as a micelle-like structure) could form, thus, enhancing K(DOC). As DOM concentration increased, DOM molecular aggregation was promoted in a way reducing K(DOC). This research is a first attempt to correlate DOM conformation with K(DOC). Aggregation of DOM molecules resulting from increased zeta potential (less negative) generally led to an increased K(DOC). Further study in this area will provide valuable information on HOC-DOM interactions, thus, leading to more accurate predictions of K(DOC).

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

    PubMed

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

    2016-03-01

    Algae cells were the main sources of dissolved organic nitrogen (DON) in raw water with plenty of algae, and ultrasonic pretreatment was one of the algae-controlling methods through the damage of algae cells. However, the variation of DON concentration during the ultrasonic treatment process was not confirmed. Variation of DON concentration during the processes of low frequency ultrasound treatment of Microcystis aeruginosa was investigated. In addition, the effect of sonication on the metabolite concentration, algae cellar activity and the subsequent coagulation performance were discussed. The results showed that after a long duration of ultrasonic (60 s), nearly 90% of the algal cells were damaged and the maximum concentration of DON attained more than 3 mg/L. In order to control the leakage extent of DON, the sonication time should be less than 30 s with power intensity of more than 1.0 W/cm(3). In the mean time, ultrasonic treatment could inhibit the reactivation and the proliferation of algal, keep the algae cell wall integrity and enhance coagulation effectively under the same condition. However, ultrasound frequency had little effect on DON at the frequency range used in this study (20-150 kHz). PMID:26585003

  18. Quantifying dissolved organic carbon concentrations in upland catchments using phenolic proxy measurements

    NASA Astrophysics Data System (ADS)

    Peacock, Mike; Burden, Annette; Cooper, Mark; Dunn, Christian; Evans, Chris D.; Fenner, Nathalie; Freeman, Chris; Gough, Rachel; Hughes, David; Hughes, Steve; Jones, Tim; Lebron, Inma; West, Mike; Zieliński, Piotr

    2013-01-01

    SummaryConcentrations of dissolved organic carbon (DOC) in soil and stream waters in upland catchments are widely monitored, in part due to the potential of DOC to form harmful by-products when chlorinated during treatment of water for public supply. DOC can be measured directly, though this is expensive and time-consuming. Light absorbance in the UV-vis spectrum is often used as a surrogate measurement from which a colour-carbon relationship between absorbance and DOC can be derived, but this relationship can be confounded by numerous variables. Through the analysis of data from eight sites in England and Wales we investigate the possibility of using the concentration of phenolic compounds in water samples as a proxy for DOC concentration. A general model using data from all the sites allowed DOC to be calculated from phenolics at an accuracy of 81-86%. A detailed analysis at one site revealed that a site-specific calibration was more accurate than the general model, and that this compared favourably with a colour-carbon calibration. We therefore recommend this method for use where estimates of DOC concentration are needed, but where time and money are limiting factors, or as an additional method to calculate DOC alongside colour-carbon calibrations. Tests demonstrated only small amounts of phenolic degradation over time; a loss of 0.92 mg L-1 after 8 months in storage, and so this method can be used on older samples with limited loss of accuracy.

  19. Raising and controlling study of dissolved oxygen concentration in closed-type aeration tank.

    PubMed

    Chen, C K; Lo, S L

    2005-07-01

    This study investigated the promotion and control of dissolved oxygen (DO) concentration of the closed-type aeration tank via practical experiments in the wastewater treatment system of a 5-star hotel in Taipei. As with limited and treasured space in Taiwan, before the completion of the sewer system construction in cities, to utilize the mat foundation under large buildings as the space of sewage treatment plant still has been one of the alternatives of those sewage treatments. However, aeration tanks constructed in the mat foundation of buildings have smaller effective water depth, which will cause a lower total transfer amount of DO. Controlling the total exhaust gas flow rate can increase the pressure on such closed-type aeration tanks. The DO concentration thus may increase according to Henry's Law. Furthermore, it may enable operators to adjust the DO concentration of the aeration tank more precisely and thus sustain optimal operating conditions in these treatment facilities. Practical experiments indicated that the DO concentration of aeration tank maintains an average of 3.8 mg l(-1), obtaining the optimum operating conditions. The efficiency of the biological treatment facilities in the mat foundation could be markedly improved. PMID:16080335

  20. Evaluation of Electrodialysis as Part of an Improved Method to Concentrate Dissolved Organic Matter from Seawater

    NASA Astrophysics Data System (ADS)

    Chang, V.; Koprivnjak, J.; Ingall, E.; Pfromm, P.; Perdue, E. M.

    2004-12-01

    A major obstacle in the study of marine dissolved organic matter (DOM) has been isolating from seawater sufficient quantities for analysis of this highly dilute and chemically complex material. This research explores the application of electrodialysis (ED) in combination with reverse osmosis (RO) as a method to concentrate DOM from seawater. RO methods recover a significant fraction (90%) of DOM from fresh waters with little physical or chemical alteration, and similar high recoveries of DOM have been observed in preliminary tests using estuarine waters of varying salinity. Unfortunately, the extent to which DOM in saline waters can be concentrated by RO is very limited, because RO membranes co-concentrate inorganic salts with DOM. At an early stage of processing, osmotic pressures become too high and/or inorganic salts precipitate from solution and foul the RO membrane. To realize the potentially high recoveries of DOM from saline waters, RO must be coupled with an independent method for removal of inorganic salts. Electrodialysis, which is a well-established process for removal of inorganic salts from aqueous solutions, is such a method. In ED, a feed stream of the sample to be de-ionized and a receiving stream of a solution that will accept the removed ions are pumped through adjacent layers of a membrane stack, which consists of several layers of alternating anion and cation exchange membranes. The membranes are made from highly crosslinked polymers and are non-porous. The direction and velocity of diffusion of the cations and anions are further mediated by a DC electrical current that flows through the membrane stack. In the first stage of testing of the ED process, samples of near-seawater salinity (28 ppt) containing 4 ppm of dissolved organic carbon were collected at the Skidaway Institute of Oceanography in Savannah Georgia. Using ED, salinity was reduced by 87% in these samples with retention of more than 95% of the DOM. These experiments indicate that ED

  1. Fractionation and size-distribution of metal and metalloid contaminants in a polluted groundwater rich in dissolved organic matter.

    PubMed

    Kozyatnyk, Ivan; Bouchet, Sylvain; Björn, Erik; Haglund, Peter

    2016-11-15

    We investigated the concentration levels, fractionation and molecular weight distribution (MWD) of dissolved organic matter (DOM) and metals (V, Cr, Co, Ni, Cu, Zn, As, Cd, Sn, Ba, Hg and Pb) in a polluted groundwater from an industrial area in Northern Sweden. DOM was mainly recovered in the hydrophobic acidic and hydrophobic neutral sub-fractions (45 and 35%, respectively) while most metals were found in the acidic sub-fractions (46-93%) except for V, Fe and As, which were predominant in the basic sub-fractions (74-93%) and Cd in the neutral ones (50%). DOM exhibited a broad MWD in groundwaters, usually from 5 to 200kDa and was dominated by high molecular weight hydrophobic acids, low molecular weight hydrophilic acids and hydrophilic neutral compounds. Most of the studied metals (Fe, Cr, Co, Sn, Ba, Hg) were associated with the high molecular weight DOM fraction (ca. 40-100kDa). Cu, Pb, Zn, Cd and Ni interacted with a broad range of DOM size fractions but were still most abundant in the high molecular weight fraction. Few metal/metalloids (As, V and Cr in some cases) presented a very weak affinity for DOM and presumably existed predominantly as "free" inorganic ions in solution. PMID:27427886

  2. Fractionation and size-distribution of metal and metalloid contaminants in a polluted groundwater rich in dissolved organic matter.

    PubMed

    Kozyatnyk, Ivan; Bouchet, Sylvain; Björn, Erik; Haglund, Peter

    2016-11-15

    We investigated the concentration levels, fractionation and molecular weight distribution (MWD) of dissolved organic matter (DOM) and metals (V, Cr, Co, Ni, Cu, Zn, As, Cd, Sn, Ba, Hg and Pb) in a polluted groundwater from an industrial area in Northern Sweden. DOM was mainly recovered in the hydrophobic acidic and hydrophobic neutral sub-fractions (45 and 35%, respectively) while most metals were found in the acidic sub-fractions (46-93%) except for V, Fe and As, which were predominant in the basic sub-fractions (74-93%) and Cd in the neutral ones (50%). DOM exhibited a broad MWD in groundwaters, usually from 5 to 200kDa and was dominated by high molecular weight hydrophobic acids, low molecular weight hydrophilic acids and hydrophilic neutral compounds. Most of the studied metals (Fe, Cr, Co, Sn, Ba, Hg) were associated with the high molecular weight DOM fraction (ca. 40-100kDa). Cu, Pb, Zn, Cd and Ni interacted with a broad range of DOM size fractions but were still most abundant in the high molecular weight fraction. Few metal/metalloids (As, V and Cr in some cases) presented a very weak affinity for DOM and presumably existed predominantly as "free" inorganic ions in solution.

  3. Diminished Stream Nitrate Concentrations Linked to Dissolved Organic Carbon Dynamics After Leaf Fall

    NASA Astrophysics Data System (ADS)

    Sebestyen, S. D.; Shanley, J. B.; Boyer, E. W.; Doctor, D. H.; Kendall, C.

    2004-05-01

    Thermodynamic coupling of the nitrogen and carbon cycles has broad implications for controls on catchment nutrient fluxes. In the northeast US, leaf fall occurs in early October and the availability of organic carbon increases as the leaves decompose. At the Sleepers River Research Watershed in northeastern Vermont (USA), we sampled stream chemistry from seven nested catchments to determine how stream dissolved organic carbon (DOC) and nitrate vary as a function of flow conditions, land-use, and basin size in response to leaf fall. Following leaf fall, nitrate concentration patterns were quantitatively different from other times of the year. Under baseflow conditions, stream and soil water DOC concentrations were higher than normal, whereas nitrate concentrations declined sharply at the five smallest catchments and more modestly at the two largest catchments. Under high flow conditions, flushing of nitrate was observed, as is typical for stormflow response at Sleepers River. Our field data suggest that in-stream processing of nitrate is likely thermodynamically and kinetically favorable under baseflow but not at higher flow conditions when expanding variable source areas make hydrological connections between nitrate source areas and streams. We are working to evaluate this hypothesis with isotopic and other monitoring data, and to model the coupled interactions of water, DOC, and nitrate fluxes in these nested catchments.

  4. Powder-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    DOEpatents

    Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

    2016-05-03

    A powder-based adsorbent and a related method of manufacture are provided. The powder-based adsorbent includes polymer powder with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the powder-based adsorbent includes irradiating polymer powder, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Powder-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  5. Foam-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    DOEpatents

    Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

    2015-06-02

    Foam-based adsorbents and a related method of manufacture are provided. The foam-based adsorbents include polymer foam with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the foam-based adsorbents includes irradiating polymer foam, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Foam-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  6. The effect of decreased atmospheric sulphur deposition on soil dissolved organic carbon concentration and quality

    NASA Astrophysics Data System (ADS)

    Ekström, Sara; Kritzberg, Emma; Berggren, Dan; Graneli, Wilhelm; Bergkvist, Bo

    2010-05-01

    Increasing concentrations of dissolved organic carbon (DOC) has been observed in aquatic systems throughout the Northern Hemisphere the last decades. The reduction in sulphur deposition has been identified as one of the major mechanisms behind this trend, where several reports show correlations between DOC and sulphur concentrations in surface waters. The reasoning is that as sulphur deposition decreases, pH in soil increase and ionic strength decrease thereby making DOC more soluble and mobile. With a more mobile DOC, the transport of DOC from the terrestrial to the aquatic system will increase. However, most of these conclusions are based solely on monitoring data that generally only include the period of decreasing sulphur deposition, and little experimental evidence exist. In this study we wanted to test the effect of sulphur deposition on the concentration and quality of the DOC in soil water. This was done in a field experiment with artificial precipitation of 12 50*50 cm plots in a boreal-nemoral forest. There was one low and one high sulphate treatment and the soil water was collected every second week using zero-tension lysimeters placed just below the O-horizon and analyzed for both quantitative and qualitative DOC variables. The experiment lasted 2 years. After about one year the low acid treatment had significantly higher absorbance at a wavelength of 420 nm, while DOC concentration did not differ between the low and the high acid treatment. Rather than the expected increase in DOC concentration in the low acid treatment, a change in DOC quality was observed as characterized by absorbance, fluorescence and high performance size exclusion chromatography. DOC in the low acid treatment tended to be more aromatic and of greater molecular weight. A change in DOC quality will affect the fate of the DOC as it moves through the terrestrial and into the aquatic system. The susceptibility of DOC to photooxidation, biodegradation and flocculation may be greatly

  7. Dissolved Organic Matter Characteristics Control Filtered Total Mercury Concentrations in an Adirondack River Basin

    NASA Astrophysics Data System (ADS)

    Burns, D. A.; Aiken, G.; Bradley, P. M.; Journey, C.

    2011-12-01

    Dissolved organic carbon (DOC) plays important roles in the transport and biogeochemical processes that affect mercury (Hg) cycling in the environment. Previous investigations have shown strong correlations between DOC and Hg concentrations in surface waters. Commonly, other DOC-related measures such as ultraviolet absorbance (UV254), and hydrophobic acid content (HPOA) show even stronger positive correlations with Hg in waters indicating the importance of the more aromatic fraction of DOC in Hg cycling. Finally, in-situ optical sensor-derived DOC concentrations have proven useful as inexpensive proxies for estimating Hg concentrations in some surface waters. Here, we describe results from the 493 km2 Upper Hudson River basin in the Adirondack Mountains of New York in which stream water samples were collected for filtered total Hg (FTHg) concentrations, DOC concentrations, UV254, HPOA, and specific ultraviolet absorbance (SUVA, derived from the absorbance and DOC measurements) at two temporal and spatial scales during 2006-09: (1) biweekly to monthly in a 66 km2 basin, and (2) seasonally at 27 synoptic sites distributed across the larger Upper Hudson basin. These results indicate that SUVA values are more strongly correlated with FTHg concentrations than are those of DOC concentrations, especially during summer. The presence of numerous open water bodies in this basin appears to greatly affect DOC and FTHg concentrations and SUVA values as reflected by data collected upstream and downstream of ponds and lakes. Multivariate regression models developed to examine the landscape factors that control spatial variation in SUVA values among synoptic sites indicate that open water area is inversely correlated with these values, reflecting autochthonous carbon sources in lakes/ponds that are more aliphatic in character than that found in streams. In contrast, metrics such as percent riparian area that reflect the influence of soils with high organic carbon content are

  8. Dissolved low-molecular weight thiol concentrations from the U.S. GEOTRACES North Atlantic Ocean zonal transect

    NASA Astrophysics Data System (ADS)

    Swarr, Gretchen J.; Kading, Tristan; Lamborg, Carl H.; Hammerschmidt, Chad R.; Bowman, Katlin L.

    2016-10-01

    Low-molecular weight thiols, including cysteine and glutathione, are biomolecules involved in a variety of metabolic pathways and act as important antioxidant and metal buffering agents. In this last capacity, they represent a potential mechanism for modulating the bioavailability and biogeochemistry of many trace elements in the ocean, particularly for chalcophilic elements (e.g., Cu, Zn, Cd, Ag and Hg). For this reason, and in the context of the international GEOTRACES program that seeks to understand the biogeochemistry of trace elements in the ocean, we measured the concentration of individual dissolved low-molecular weight thiols during the U.S. GEOTRACES North Atlantic Zonal Transect (USGNAZT). Only two thiols were identified, cysteine and glutathione, in contrast to results from the northeast subarctic Pacific Ocean, where the dipeptides glycine-cysteine and arginine-cysteine were also present and γ-glutamylcysteine was dominant. Concentrations of cysteine and glutathione in the North Atlantic Ocean were lower than in the Pacific and ranged from below detection ( 0.01 nM) to 0.61 nM of cysteine and up to 1.0 nM of glutathione, with cysteine generally more abundant than glutathione. Vertical profiles of cysteine and glutathione were broadly consistent with their biological production, being more abundant in surface water and usually below detection at depths greater than about 200 m. Subsurface concentration maxima, often co-incident with the deep chlorophyll maximum, were frequently observed but not universal. We conclude that cysteine and glutathione do not make up significant portions of complexation capacity for Cu and Zn in the upper open ocean but could be important for Cd, Hg, and potentially other chalcophiles. Extremely low concentrations of cysteine and glutathione in deep water suggest that higher molecular-weight thiols are a more important ligand class for chalcophiles in that portion of the ocean.

  9. Salicylhydroxamic acid (SHAM) inhibition of the dissolved inorganic carbon concentrating process in unicellular green algae

    SciTech Connect

    Goyal, A.; Tolbert, N.E. )

    1990-03-01

    Rates of photosynthetic O{sub 2} evolution, for measuring K{sub 0.5}(CO{sub 2} + HCO{sub 3}{sup {minus}}) at pH 7, upon addition of 50 micromolar HCO{sub 3}{sup {minus}} to air-adapted Chlamydomonas, Dunaliella, or Scenedesmus cells, were inhibited up to 90% by the addition of 1.5 to 4.0 millimolar salicylhydroxamic acid (SHAM) to the aqueous medium. The apparent K{sub i}(SHAM) for Chlamydomonas cells was about 2.5 millimolar, but due to low solubility in water effective concentrations would be lower. Salicylhydroxamic acid did not inhibit oxygen evolution or accumulation of bicarbonate by Scenedesmus cells between pH 8 to 11 or by isolated intact chloroplasts from Dunaliella. Thus, salicylhydroxamic acid appears to inhibit CO{sub 2} uptake, whereas previous results indicate that vanadate inhibits bicarbonate uptake. These conclusions were confirmed by three test procedures with three air-adapted algae at pH 7. Salicylhydroxamic acid inhibited the cellular accumulation of dissolved inorganic carbon, the rate of photosynthetic O{sub 2} evolution dependent on low levels of dissolved inorganic carbon (50 micromolar NaHCO{sub 3}), and the rate of {sup 14}CO{sub 2} fixation with 100 micromolar ({sup 14}C)HCO{sub 3}{sup {minus}}. Salicylhydroxamic acid inhibition of O{sub 2} evolution and {sup 14}CO{sub 2}-fixation was reversed by higher levels of NaHCO{sub 3}. Thus, salicylhydroxamic acid inhibition was apparently not affecting steps of photosynthesis other than CO{sub 2} accumulation. Although salicylhydroxamic acid is an inhibitor of alternative respiration in algae, it is not known whether the two processes are related.

  10. Salicylhydroxamic Acid (SHAM) Inhibition of the Dissolved Inorganic Carbon Concentrating Process in Unicellular Green Algae.

    PubMed

    Goyal, A; Tolbert, N E

    1990-03-01

    Rates of photosynthetic O(2) evolution, for measuring K(0.5)(CO(2) + HCO(3) (-)) at pH 7, upon addition of 50 micromolar HCO(3) (-) to air-adapted Chlamydomonas, Dunaliella, or Scenedesmus cells, were inhibited up to 90% by the addition of 1.5 to 4.0 millimolar salicylhydroxamic acid (SHAM) to the aqueous medium. The apparent K(1)(SHAM) for Chlamydomonas cells was about 2.5 millimolar, but due to low solubility in water effective concentrations would be lower. Salicylhydroxamic acid did not inhibit oxygen evolution or accumulation of bicarbonate by Scenedesmus cells between pH 8 to 11 or by isolated intact chloroplasts from Dunaliella. Thus, salicylhydroxamic acid appears to inhibit CO(2) uptake, whereas previous results indicate that vanadate inhibits bicarbonate uptake. These conclusions were confirmed by three test procedures with three air-adapted algae at pH 7. Salicylhydroxamic acid inhibited the cellular accumulation of dissolved inorganic carbon, the rate of photosynthetic O(2) evolution dependent on low levels of dissolved inorganic carbon (50 micromolar Na-HCO(3)), and the rate of (14)CO(2) fixation with 100 micromolar [(14)C] HCO(3) (-). Salicylhydroxamic acid inhibition of O(2) evolution and (14)CO(2)-fixation was reversed by higher levels of NaHCO(3). Thus, salicylhydroxamic acid inhibition was apparently not affecting steps of photosynthesis other than CO(2) accumulation. Although salicylhydroxamic acid is an inhibitor of alternative respiration in algae, it is not known whether the two processes are related.

  11. Metal Concentrations and Hydrochemical Dynamics in a Tropical-Glacier Watershed

    NASA Astrophysics Data System (ADS)

    Fortner, S. K.; Mark, B. G.; McKenzie, J. M.; Baraer, M.; Schoenfelt, M. J.

    2008-12-01

    The rapid retreat of tropical glaciers and their related changes in hydrology has many implications for water resources, including domestic, agricultural, and industrial consumption water quality. The Cordillera Blanca is especially susceptible to water quality degradation given its abundant natural mineral resources and ongoing mining operations. Here we explore dissolved (<0.4 µm) Al, Fe, Mn, and Zn concentrations and behavior in the glacial-fed headwater region of the Rio Quilcay (9° S, 78° W) a stream that flows into the Rio Santa, Peru. Twenty-four samples were collected in July 2008 from the headwaters of the Rio Quilcay over a distance of 9 km between 4800 m and 3800 m above sea level. Samples were upstream of any mining activity and included the main channel, glacial headwater melt, joining tributaries, and shallow groundwater. Rio Quilcay headwater metal concentrations had broad ranges: (Al= 1.8 to 180 μM, Fe= 1.8 to 3,100 μM, Mn= 5.5 to 180 μM, Zn= 1.3 to 17 μM). Measured pH values had a significant negative correlation with elevation and dissolved Al, Mn, and Zn. However, dissolved Zn also had a significant positive correlation with Al, Fe, and Mn, suggesting possible adsorption of Zn to metal oxide surfaces. The greatest dissolved metal concentrations occurred immediately downstream of a reductive, high-sulfate, water-saturated region in association with the lowest pH values (~3.3). Visible metal precipitation was observed immediately downstream of this reductive environment and at subsequent downstream sites where less acidic tributaries joined the main channel. Dissolved metal concentrations observed in the Rio Quilcay exceed world river averages and are dramatically higher than other headwater streams. For example, both Fe and Mn concentrations were up to three orders of magnitude higher than those observed in tributaries of the Fraser River, British Columbia, Canada (Cameron et al., 1995). The prevalence of water-saturated, shallow

  12. Influence of groundwater recharge and well characteristics on dissolved arsenic concentrations in southeastern Michigan groundwater.

    PubMed

    Meliker, Jaymie R; Slotnick, Melissa J; Avruskin, Gillian A; Haack, Sheridan K; Nriagu, Jerome O

    2009-02-01

    Arsenic concentrations exceeding 10 microg/l, the United States maximum contaminant level and the World Health Organization guideline value, are frequently reported in groundwater from bedrock and unconsolidated aquifers of southeastern Michigan. Although arsenic-bearing minerals (including arsenian pyrite and oxide/hydroxide phases) have been identified in Marshall Sandstone bedrock of the Mississippian aquifer system and in tills of the unconsolidated aquifer system, mechanisms responsible for arsenic mobilization and subsequent transport in groundwater are equivocal. Recent evidence has begun to suggest that groundwater recharge and characteristics of well construction may affect arsenic mobilization and transport. Therefore, we investigated the relationship between dissolved arsenic concentrations, reported groundwater recharge rates, well construction characteristics, and geology in unconsolidated and bedrock aquifers. Results of multiple linear regression analyses indicate that arsenic contamination is more prevalent in bedrock wells that are cased in proximity to the bedrock-unconsolidated interface; no other factors were associated with arsenic contamination in water drawn from bedrock or unconsolidated aquifers. Conditions appropriate for arsenic mobilization may be found along the bedrock-unconsolidated interface, including changes in reduction/oxidation potential and enhanced biogeochemical activity because of differences between geologic strata. These results are valuable for understanding arsenic mobilization and guiding well construction practices in southeastern Michigan, and may also provide insights for other regions faced with groundwater arsenic contamination.

  13. Influence of groundwater recharge and well characteristics on dissolved arsenic concentrations in southeastern Michigan groundwater

    USGS Publications Warehouse

    Meliker, J.R.; Slotnick, M.J.; Avruskin, G.A.; Haack, S.K.; Nriagu, J.O.

    2009-01-01

    Arsenic concentrations exceeding 10 ??g/l, the United States maximum contaminant level and the World Health Organization guideline value, are frequently reported in groundwater from bedrock and unconsolidated aquifers of southeastern Michigan. Although arsenic-bearing minerals (including arsenian pyrite and oxide/hydroxide phases) have been identified in Marshall Sandstone bedrock of the Mississippian aquifer system and in tills of the unconsolidated aquifer system, mechanisms responsible for arsenic mobilization and subsequent transport in groundwater are equivocal. Recent evidence has begun to suggest that groundwater recharge and characteristics of well construction may affect arsenic mobilization and transport. Therefore, we investigated the relationship between dissolved arsenic concentrations, reported groundwater recharge rates, well construction characteristics, and geology in unconsolidated and bedrock aquifers. Results of multiple linear regression analyses indicate that arsenic contamination is more prevalent in bedrock wells that are cased in proximity to the bedrock-unconsolidated interface; no other factors were associated with arsenic contamination in water drawn from bedrock or unconsolidated aquifers. Conditions appropriate for arsenic mobilization may be found along the bedrock-unconsolidated interface, including changes in reduction/oxidation potential and enhanced biogeochemical activity because of differences between geologic strata. These results are valuable for understanding arsenic mobilization and guiding well construction practices in southeastern Michigan, and may also provide insights for other regions faced with groundwater arsenic contamination. ?? Springer-Verlag 2008.

  14. Concentration, sources and flux of dissolved organic carbon of precipitation at Lhasa city, the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Li, C.

    2015-12-01

    Dissolved organic carbon (DOC) plays important role in climate system, but few data are available on the Tibetan Plateau (TP). In this study 89 precipitation samples were collected at Lhasa, the largest city of southern Tibet, from March to December 2013. The average concentration and wet deposition fluxes of DOC was 1.10 mg C/L and 0.62 g C m-2.yr-1, respectively. Seasonally, low DOC concentration and high flux appeared during monsoon period, which were in line with heavy precipitation amount, reflecting dilution effect of precipitation for the DOC. Compared to other regions, the values of Lhasa were lower than those of large cites (e.g. Beijing and Seoul) mainly because of less air pollution of Lhasa. The relationship between DOC and ion analysis showed that DOC of Lhasa was derived mainly from the natural sources, followed by burning activities. Furthermore, △14C value of DOC indicated that fossil combustion contributed around 20% of the precipitation DOC of Lhasa, indicating that the atmosphere of Lhasa has been influenced by vehicle emissions. Therefore, although atmosphere of Lhasa is relatively clean, pollutants emitted from local sources cannot be ignored.

  15. In vivo noninvasive monitoring of dissolved oxygen concentration within an implanted tissue-engineered pancreatic construct.

    PubMed

    Goh, Fernie; Sambanis, Athanassios

    2011-09-01

    The function of an implanted tissue-engineered pancreatic construct is influenced by many in vivo factors; however, assessing its function is based primarily on end physiologic effects. As oxygen significantly affects cell function, we established a dual perfluorocarbon method that utilizes (19)F nuclear magnetic resonance spectroscopy, with perfluorocarbons as oxygen concentration markers, to noninvasively monitor dissolved oxygen concentration (DO) in βTC-tet cell-containing alginate beads and at the implantation milieu. Beads were implanted in the peritoneal cavity of normal and streptozotocin-induced diabetic mice. Using this method, the feasibility of acquiring real-time in vivo DO measurements was demonstrated. Results showed that the mouse peritoneal environment is hypoxic and the DO is further reduced when βTC-tet cell constructs were implanted. The DO within cell-containing beads decreased considerably over time and could be correlated with the relative changes in the number of viable encapsulated cells. The reduction of construct DO due to the metabolic activity of the βTC-tet cells was also compatible with the implant therapeutic function, as observed in the reversal of hyperglycemia in diabetic mice. The importance of these findings in assessing implant functionality and host animal physiology is discussed.

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

    PubMed

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

    2016-03-01

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

  17. Novel method for online monitoring of dissolved N2O concentrations through a gas stripping device.

    PubMed

    Mampaey, Kris E; van Dongen, Udo G J M; van Loosdrecht, Mark C M; Volcke, Eveline I P

    2015-01-01

    Nitrous oxide emissions from wastewater treatment plants are currently measured by online gas phase analysis or grab sampling from the liquid phase. In this study, a novel method is presented to monitor the liquid phase N2O concentration for aerated as well as non-aerated conditions/reactors, following variations both in time and in space. The monitoring method consists of a gas stripping device, of which the measurement principle is based on a continuous flow of reactor liquid through a stripping flask and subsequent analysis of the N2O concentration in the stripped gas phase. The method was theoretically and experimentally evaluated for its fit for use in the wastewater treatment context. Besides, the influence of design and operating variables on the performance of the gas stripping device was addressed. This method can easily be integrated with online off-gas measurements and allows to better investigate the origin of the gas emissions from the treatment plant. Liquid phase measurements of N2O are of use in mitigation of these emissions. The method can also be applied to measure other dissolved gasses, such as methane, being another important greenhouse gas.

  18. Novel method for online monitoring of dissolved N2O concentrations through a gas stripping device.

    PubMed

    Mampaey, Kris E; van Dongen, Udo G J M; van Loosdrecht, Mark C M; Volcke, Eveline I P

    2015-01-01

    Nitrous oxide emissions from wastewater treatment plants are currently measured by online gas phase analysis or grab sampling from the liquid phase. In this study, a novel method is presented to monitor the liquid phase N2O concentration for aerated as well as non-aerated conditions/reactors, following variations both in time and in space. The monitoring method consists of a gas stripping device, of which the measurement principle is based on a continuous flow of reactor liquid through a stripping flask and subsequent analysis of the N2O concentration in the stripped gas phase. The method was theoretically and experimentally evaluated for its fit for use in the wastewater treatment context. Besides, the influence of design and operating variables on the performance of the gas stripping device was addressed. This method can easily be integrated with online off-gas measurements and allows to better investigate the origin of the gas emissions from the treatment plant. Liquid phase measurements of N2O are of use in mitigation of these emissions. The method can also be applied to measure other dissolved gasses, such as methane, being another important greenhouse gas. PMID:25573615

  19. Dissolved methane concentration profiles and air-sea fluxes from 41°S to 27°N

    NASA Astrophysics Data System (ADS)

    Kelley, Cheryl A.; Jeffrey, Wade H.

    2002-07-01

    Water column samples from a transect cruise from southern Chile through the Panama Canal to the Gulf of Mexico were used to determine dissolved methane depth profiles and air-sea methane fluxes. In the Gulf of Mexico, surface concentrations were approximately 40% supersaturated with respect to the atmosphere, whereas near the equator and in the Peru upwelling region, 10-20% supersaturation generally occurred. These saturation ratios translate into an average flux of methane from the sea surface to the atmosphere of 0.38 μmol m-2 d-1. In addition, water column profiles of dissolved methane indicate that subsurface maxima in dissolved methane concentrations are a consistent feature of the open ocean, except near the equator. At the equator, the subsurface peak at the base of the mixed layer may be bowed down by the Equatorial Undercurrent. The highest methane concentration (12 nM) was observed in the Peru upwelling region.

  20. Influence of Dissolved Metals on N-Nitrosamine Formation under Amine-based CO2 Capture Conditions.

    PubMed

    Wang, Zimeng; Mitch, William A

    2015-10-01

    As the prime contender for postcombustion CO2 capture technology, amine-based scrubbing has to address the concerns over the formation of potentially carcinogenic N-nitrosamine byproducts from reactions between flue gas NOx and amine solvents. This bench-scale study evaluated the influence of dissolved metals on the potential to form total N-nitrosamines in the solvent within the absorber unit and upon a pressure-cooker treatment that mimics desorber conditions. Among six transition metals tested for the benchmark solvent monoethanolamine (MEA), dissolved Cu promoted total N-nitrosamine formation in the absorber unit at concentrations permitted in drinking water, but not the desorber unit. The Cu effect increased with oxygen concentration. Variation of the amine structural characteristics (amine order, steric hindrance, -OH group substitution and alkyl chain length) indicated that Cu promotes N-nitrosamine formation from primary amines with hydroxyl or carboxyl groups (amino acids), but not from secondary amines, tertiary amines, sterically hindered primary amines, or amines without oxygenated groups. Ethylenediaminetetraacetate (EDTA) suppressed the Cu effect. The results suggested that the catalytic effect of Cu may be associated with the oxidative degradation of primary amines in the absorber unit, a process known to produce a wide spectrum of secondary amine products that are more readily nitrosatable than the pristine primary amines, and that can form stable N-nitrosamines. This study highlighted an intriguing linkage between amine degradation (operational cost) and N-nitrosamine formation (health hazards), all of which are challenges for commercial-scale CO2 capture technology. PMID:26335609

  1. Influence of Dissolved Metals on N-Nitrosamine Formation under Amine-based CO2 Capture Conditions.

    PubMed

    Wang, Zimeng; Mitch, William A

    2015-10-01

    As the prime contender for postcombustion CO2 capture technology, amine-based scrubbing has to address the concerns over the formation of potentially carcinogenic N-nitrosamine byproducts from reactions between flue gas NOx and amine solvents. This bench-scale study evaluated the influence of dissolved metals on the potential to form total N-nitrosamines in the solvent within the absorber unit and upon a pressure-cooker treatment that mimics desorber conditions. Among six transition metals tested for the benchmark solvent monoethanolamine (MEA), dissolved Cu promoted total N-nitrosamine formation in the absorber unit at concentrations permitted in drinking water, but not the desorber unit. The Cu effect increased with oxygen concentration. Variation of the amine structural characteristics (amine order, steric hindrance, -OH group substitution and alkyl chain length) indicated that Cu promotes N-nitrosamine formation from primary amines with hydroxyl or carboxyl groups (amino acids), but not from secondary amines, tertiary amines, sterically hindered primary amines, or amines without oxygenated groups. Ethylenediaminetetraacetate (EDTA) suppressed the Cu effect. The results suggested that the catalytic effect of Cu may be associated with the oxidative degradation of primary amines in the absorber unit, a process known to produce a wide spectrum of secondary amine products that are more readily nitrosatable than the pristine primary amines, and that can form stable N-nitrosamines. This study highlighted an intriguing linkage between amine degradation (operational cost) and N-nitrosamine formation (health hazards), all of which are challenges for commercial-scale CO2 capture technology.

  2. The determination of water quality and metal concentrations of Ampang Hilir Lake, Selangor, Peninsular Malaysia.

    PubMed

    Said, Khaled S A; Shuhaimi-Othman, M; Ahmad, A K

    2012-05-01

    A study of water quality parameters (temperature, conductivity, total dissolved solid, dissolved oxygen, pH and water hardness) in Ampang Hilir Lake was conducted in January, April, July and October 2010. The water quality parameters were tested and recorded at different sampling stations chosen randomly using Hydrolab Data Sonde 4 and Surveyor 4 a water quality multi probe (USA). Six metals which were cadmium, chromium, lead, nickel, zinc and copper were determined in five different compartments of the lake namely water, total suspended solids, plankton, sediment and fish. The metals concentration were determined by Inductively Coupled Plasma Mass Spectrometer (ICP-MS), Perkin Elmer Elan, model 9000.The water quality parameters were compared with National Water Quality Standard (NWQS Malaysia) while metal concentrations were compared with Malaysian and international standards. The study shows that water quality parameters are of class 2. This condition is suitable for recreational activities where body contact is allowed and suitable for sensitive fishing activities. Furthermore, metal concentrations were found to be lower than the international standards, therefore toxic effects for these metals would be rarely observed and the adverse effects to aquatic organisms would not frequently occur. PMID:24163953

  3. The evaluation of water quality and metal concentrations of Titiwangsa Lake, Selangor, Peninsular Malaysia.

    PubMed

    Said, Khaled S A; Shuhaimi-Othman, M; Ahmad, A K

    2012-05-15

    A study of water quality parameters (temperature, conductivity, total dissolved solid, dissolved oxygen, pH and water hardness) in Titiwangsa Lake was conducted in January, April, July and October 2010. The water quality parameters were tested and recorded at different sampling stations chosen randomly using hydrolab data sonde 4 and surveyor 4 a water quality multi probe (USA). Six metals i.e., cadmium, chromium, lead, nickel, zinc and copper were determined in five different compartments of the lake namely water, total suspended solids, plankton, sediment and fish. The metals concentration were determined by Inductively Coupled Plasma Mass Spectrometer (ICP-MS), perkin elmer elan, model 9000. The water quality parameters were compared with National Water Quality Standard (NWQS Malaysia) while metal concentrations were compared with Malaysian and international standards. The study shows that water quality parameters are of class 2. This condition is suitable for recreational activities where body contact is allowed and suitable for sensitive fishing activities. Furthermore, metal concentrations were found to be lower than the international standards, therefore toxic effects for these metals would be rarely observed and the adverse effects to aquatic organisms would not frequently occur. PMID:24187900

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

    NASA Astrophysics Data System (ADS)

    Velescu, Andre; Valarezo, Carlos; Wilcke, Wolfgang

    2016-05-01

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

  5. Risk assessment of dissolved trace metals in drinking water of Karachi, Pakistan.

    PubMed

    Karim, Zahida

    2011-06-01

    Health risk caused by the exposure to trace metals in water through different exposure pathways was investigated. Graphite furnace atomic absorption spectrometry was used for the determination of trace metals (nickel, copper, chromium, lead, cobalt, manganese and iron) in drinking water samples. The concentration of metals was compared with the world health organization (WHO) drinking water quality guideline values. Risk of metals on human health was evaluated using Hazard Quotient (HQ). Hazard quotients of all metals through oral ingestion and dermal absorption are found in the range of 1.11 × 10⁻² to 1.35 × 10⁻¹ and 8.52 × 10⁻⁵ to 9.75 × 10⁻², respectively. The results of the present study reflect the unlikely potential for adverse health effects to the inhabitants of Karachi due to the oral ingestion and dermal absorption of water containing these metals.

  6. Heavy metal behavior and dissolved organic matter (DOM) characterization of vermicomposted pig manure amended with rice straw.

    PubMed

    Zhu, Weiqin; Yao, Wu; Zhang, Zhi; Wu, Yang

    2014-11-01

    Vermicomposting is an eco-friendly method for disposing of livestock and poultry manure. In addition, dissolved organic matter (DOM) can serve as a carrier that enhances the migration and transformation of heavy metals. Here, pig manure amended with rice straw was vermicomposted with Eisenia fetida. The DOM content, molecular weight distribution, and spectroscopic properties of the amended pig manure were measured before and after vermicomposting. The Cu and Zn concentrations in the earthworms increased from 8.24 and 17.63 to 40.75 and 362.78 mg/kg separately after vermicomposting, and the earthworms also increased the heavy metal availability in the vermicompost. Relative to the DOM properties of conventional compost, the DOM molecular weight decreased and varied widely following vermicomposting, and the C/N ratio of the DOM in the vermicompost treatments decreased from 10.37 to 8.60. The Fourier transform far-infrared (FTIR) and fluorescence spectra of the DOM indicated that the amounts of oxygen-containing structures increased while the ratio of humic acid to fulvic acid decreased following vermicomposting. Accordingly, the earthworms augmented the heavy metal mitigation risk in the pig manure. This augment potentially resulted from the decreased humic acid-to-fulvic acid (HA/FA) ratio from DOM structural changes. PMID:24958537

  7. The episodic acidification of a stream with elevated concentrations of dissolved organic carbon

    NASA Astrophysics Data System (ADS)

    Wellington, Brian I.; Driscoll, Charles T.

    2004-10-01

    Organic acids are generally thought to play a minor role in the episodic acidification of streams in the USA. In this study, we investigated the episodic acidification of a stream at the Hubbard Brook Experimental Forest in New Hampshire with high concentrations of dissolved organic carbon and naturally occurring organic acids. We studied three events in 2001: spring snowmelt, which occurred from 6 April to 14 May and resulted in two distinct melt events; and two rain events, one on 17 June and the other on 17 July. During snowmelt events organic acids were a minor contributor to the short-term acidification of stream water, with increases in NO3- and dilution of base cations being the dominant mechanisms. During summer rainfall events, however, increases in inputs of organic acids were the dominant mechanism of episodic acidification when soil water was the dominant contributor to stream discharge (59 to 66% of peak stream discharge). We also found that precipitation events occurring after relatively wet antecedent conditions (17 July event) resulted in more severe acid episodes than events that followed drier antecedent conditions (17 June event). The minimum acid neutralizing capacity (ANC) was only -19 μeq l-1 for the 17 June event, whereas the minimum ANC for the 17 July event was much lower (-62 μeq l-1) although the total rainfall amount was similar for the two events.

  8. Concentrations and radiocarbon signatures of dissolved organic matter in the Pacific Ocean

    SciTech Connect

    Druffel, E.R.M. ); Williams, P.M. ); Suzuki, Yoshimi )

    1989-09-01

    The authors present evidence suggesting that only a portion of the dissolved organic carbon (DOC) in the seawater analyzed previously by Williams and Druffel (1987) was oxidized by the UV-radiation method. High temperature catalytic (HTC) methods (Sugimura and Suzuki, 1988) used to reoxidize the central North Pacific gyre water samples reveal that the total DOC (DOC{sub HTC}) is about twice that of the UV-oxidizable DOC (DOC{sub UV}). Indications from the original study suggest that this additional DOC contains higher concentrations of radiocarbon than in the DOC{sub UV} (Williams and Druffel, 1987). This evidence implies that DOC is older and thus more refractory with respect to biological utilization, yet is more chemically reactive with respect to photooxidation, than the fraction resistant to UV (DOC{sub res}). The authors report accelerator mass spectrometry (AMS) {Delta}{sup 14}C measurements of humic, fulvic and hydrophilic acid fractions isolated from water collected at 180 m in the North Pacific (19{degree}N, 158{degree}W) using XAD macroreticular resins. {Delta}{sup 14} values of the humic material are less than those of DOC{sub UV} from a similar depth 1,200 km further north (Williams and Druffel, 1987) indicating that these humic substances are part of the old recycled DOC{sub UV} in the ocean.

  9. Direct measurement of local dissolved oxygen concentration spatial profiles in a cell culture environment.

    PubMed

    Kagawa, Yuki; Matsuura, Katsuhisa; Shimizu, Tatsuya; Tsuneda, Satoshi

    2015-06-01

    Controlling local dissolved oxygen concentration (DO) in media is critical for cell or tissue cultures. Various biomaterials and culture methods have been developed to modulate DO. Direct measurement of local DO in cultures has not been validated as a method to test DO modulation. In the present study we developed a DO measurement system equipped with a Clark-type oxygen microelectrode manipulated with 1 μm precision in three-dimensional space to explore potential applications for tissue engineering. By determining the microelectrode tip position precisely against the bottom plane of culture dishes with rat or human cardiac cells in static monolayer culture, we successfully obtained spatial distributions of DO in the medium. Theoretical quantitative predictions fit the obtained data well. Based on analyses of the variance between samples, we found the data reflected "local" oxygen consumption in the vicinity of the microelectrode and the detection of temporal changes in oxygen consumption rates of cultured cells was limited by the diffusion rate of oxygen in the medium. This oxygen measuring system monitors local oxygen consumption and production with high spatial resolution, and can potentially be used with recently developed oxygen modulating biomaterials to design microenvironments and non-invasively monitor local DO dynamics during culture.

  10. Structurally colored biopolymer thin films for detection of dissolved metal ions in aqueous solution

    NASA Astrophysics Data System (ADS)

    Cathell, Matthew David

    Natural polymers, such as the polysaccharides alginate and chitosan, are noted sorbents of heavy metals. Their polymer backbone structures are rich in ligands that can interact with metal ions through chelation, electrostatics, ion exchange and nonspecific mechanisms. These water-soluble biopolymer materials can be processed into hydrogel thin films, creating high surface area interfaces ideal for binding and sequestering metal ions from solution. By virtue of their uniform nanoscale dimensions (with thicknesses smaller than wavelengths of visible light) polymer thin films exhibit structure-based coloration. This phenomenon, frequently observed in nature, causes the transparent and essentially colorless films to reflect light in a wide array of colors. The lamellar film structures act as one-dimensional photonic crystals, allowing selective reflection of certain wavelengths of light while minimizing other wavelengths by out-of-phase interference. The combination of metal-binding and reflective properties make alginate and chitosan thin films attractive candidates for analyte sensing. Interactions with metal ions can induce changes in film thicknesses and refractive indices, thus altering the path of light reflected through the film. Small changes in dimensional or optical properties can lead to shifts in film color that are perceivable by the unaided eye. These thin films offer the potential for optical sensing of toxic dissolved materials without the need for instrumentation, external power or scientific expertise. With the use of a spectroscopic ellipsometer and a fiber optic reflectance spectrometer, the physical and optical characteristics of biopolymer thin films have been characterized in response to 50 ppm metal ion solutions. It has been determined that metal interactions can lead to measurable changes in both film thicknesses and effective refractive indices. The intrinsic response behaviors of alginate and chitosan, as well as the responses of modified

  11. EXAFS study into the speciation of metal salts dissolved in ionic liquids and deep eutectic solvents.

    PubMed

    Hartley, Jennifer M; Ip, Chung-Man; Forrest, Gregory C H; Singh, Kuldip; Gurman, Stephen J; Ryder, Karl S; Abbott, Andrew P; Frisch, Gero

    2014-06-16

    The speciation of metals in solution controls their reactivity, and this is extremely pertinent in the area of metal salts dissolved in ionic liquids. In the current study, the speciation of 25 metal salts is investigated in four deep eutectic solvents (DESs) and five imidazolium-based ionic liquids using extended X-ray absorption fine structure. It is shown that in diol-based DESs M(I) ions form [MCl2](-) and [MCl3](2-) complexes, while all M(II) ions form [MCl4](2-) complexes, with the exception of Ni(II), which exhibits a very unusual coordination by glycol molecules. This was also found in the X-ray crystal structure of the compound [Ni(phen)2(eg)]Cl2·2eg (eg = ethylene glycol). In a urea-based DES, either pure chloro or chloro-oxo coordination is observed. In [C6mim][Cl] pure chloro complexation is also observed, but coordination numbers are smaller (typically 3), which can be explained by the long alkyl chain of the cation. In [C2mim][SCN] metal ions are entirely coordinated by thiocyanate, either through the N or the S atom, depending on the hardness of the metal ion according to the hard-soft acid-base principle. With weaker coordinating anions, mixed coordination between solvent and solute anions is observed. The effect of hydrate or added water on speciation is insignificant for the diol-based DESs and small in other liquids with intermediate or strong ligands. One of the main findings of this study is that, with respect to metal speciation, there is no fundamental difference between deep eutectic solvents and classic ionic liquids. PMID:24897923

  12. Hydrologically Driven Dynamics of Dissolved Organic Carbon Concentration and Composition in a Headwater Stream Ecosystem

    NASA Astrophysics Data System (ADS)

    Kaplan, L. A.; McLaughlin, C.; Hogan, K. R.; Newbold, J. D.

    2011-12-01

    A 34-year record of dissolved organic carbon (DOC) concentrations and compositions was used to assess the role of hydrologic variability in the carbon cycle of a headwater stream. The DOC concentration record is characterized by sharply increasing values during storms and annual minima associated with soil freezing in winter (Fig. 1). Baseflow discharge accounts for approximately 67% of the total runoff in this 3rd-order stream in the Pennsylvania Piedmont but storm flows transport approximately 75% of the DOC flux. The annual DOC flux varies as much as 3-fold and this variability is driven by unusual events such as major storms and prolonged droughts. During storms DOC quality changes as water moves to the stream through organic matter-rich upper soil horizons, by passing terrestrial controls on DOC content. The pool of biodegradable DOC (BDOC) as a percentage of total DOC increases from 33% to 73% with the most labile BDOC class increasing 4-fold while the semi-labile BDOC pool increases 2-fold. Storms also alter the structure and productivity of benthic bacterial communities that metabolize DOC in streams, though the impacts are tempered by stability of streambed substrata. For example, a February storm reduced the biomass and productivity of bacteria attached to sediments by 48% and 90%, respectively, while reducing the biomass of bacteria attached to rocks by 21% but increasing bacterial productivity by 22%. Molecular fingerprints of community compositions revealed a stable "climax community" whose alteration is influenced by the magnitude of the storm flows and eventually returns to its original composition. Actual measurements of carbon cycling based on whole-stream releases and sampling the stream bed microbial community are not feasible during storms, but we argue that for headwater streams it is the post-disturbance condition rather than any processing which occurs during storm flows that shapes the magnitude and dynamics of carbon cycling.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Camino-Serrano, Marta; Graf Pannatier, Elisabeth; Vicca, Sara; Luyssaert, Sebastiaan; Jonard, Mathieu; Ciais, Philippe; Guenet, Bertrand; Gielen, Bert; Peñuelas, Josep; Sardans, Jordi; Waldner, Peter; Etzold, Sophia; Cecchini, Guia; Clarke, Nicholas; Galić, Zoran; Gandois, Laure; Hansen, Karin; Johnson, Jim; Klinck, Uwe; Lachmanová, Zora; Lindroos, Antti-Jussi; Meesenburg, Henning; Nieminen, Tiina M.; Sanders, Tanja G. M.; Sawicka, Kasia; Seidling, Walter; Thimonier, Anne; Vanguelova, Elena; Verstraeten, Arne; Vesterdal, Lars; Janssens, Ivan A.

    2016-10-01

    Dissolved organic carbon (DOC) in surface waters is connected to DOC in soil solution through hydrological pathways. Therefore, it is expected that long-term dynamics of DOC in surface waters reflect DOC trends in soil solution. However, a multitude of site studies have failed so far to establish consistent trends in soil solution DOC, whereas increasing concentrations in European surface waters over the past decades appear to be the norm, possibly as a result of recovery from acidification. The objectives of this study were therefore to understand the long-term trends of soil solution DOC from a large number of European forests (ICP Forests Level II plots) and determine their main physico-chemical and biological controls. We applied trend analysis at two levels: (1) to the entire European dataset and (2) to the individual time series and related trends with plot characteristics, i.e., soil and vegetation properties, soil solution chemistry and atmospheric deposition loads. Analyses of the entire dataset showed an overall increasing trend in DOC concentrations in the organic layers, but, at individual plots and depths, there was no clear overall trend in soil solution DOC. The rate change in soil solution DOC ranged between -16.8 and +23 % yr-1 (median = +0.4 % yr-1) across Europe. The non-significant trends (40 %) outnumbered the increasing (35 %) and decreasing trends (25 %) across the 97 ICP Forests Level II sites. By means of multivariate statistics, we found increasing trends in DOC concentrations with increasing mean nitrate (NO3-) deposition and increasing trends in DOC concentrations with decreasing mean sulfate (SO42-) deposition, with the magnitude of these relationships depending on plot deposition history. While the attribution of increasing trends in DOC to the reduction of SO42- deposition could be confirmed in low to medium N deposition areas, in agreement with observations in surface waters, this was not the case in high N deposition areas. In

  15. Declines in dissolved silica concentrations in western Virginia streams (1988-2003): Gypsy moth defoliation stimulates diatoms?

    NASA Astrophysics Data System (ADS)

    Grady, Amy E.; Scanlon, Todd M.; Galloway, James N.

    2007-03-01

    Dissolved silica concentrations in western Virginia streams showed a significant bias toward declines (p < 0.0001) over the time period from 1988 to 2003. Streams with the greatest declines were those that had the highest mean dissolved silica concentrations, specific to watersheds underlain by basaltic and granitic bedrock. We examined potential geochemical, hydrological, and biological factors that could account for the observed widespread declines, focusing on six core watersheds where weekly stream chemistry data were available. No relationships were evident between stream water dissolved silica concentrations and pH, a finding supported by the results from a geochemical model applied to the dominant bedrock mineralogy. Along with changes in watershed acidity, changes in precipitation and discharge were also discounted since no significant trends were observed over the study period. Analyses of two longer-term data sets that extend back to 1979 revealed that the initiation of the dissolved silica declines coincided with the timing of a gypsy moth (Lymantria dispar) defoliation event. We develop a conceptual model centered on benthic diatoms, which are found within each of the six core watersheds but in greater abundance in the more silica-rich streams. Gypsy moth defoliation led to greater sunlight penetration and enhanced nitrate concentrations in the streams, which could have spurred population growth and silica uptake. The model can explain why the observed declines are primarily driven by decreased concentrations during low-flow conditions. This study illustrates lasting effects of disturbance on watershed biogeochemistry, in this case causing decadal-scale variability in stream water dissolved silica concentrations.

  16. Periodical bubble formation and the oscillatory change in dissolved oxygen concentration in a catalase-hydrogen peroxide system.

    PubMed

    Sasaki, Satoshi

    2006-06-01

    The relationship between the periodical bubble forming and the oscillatory change in the dissolved oxygen (DO) concentration in a catalase-hydrogen peroxide system was studied. Photographs of the bubbles and the responses from the DO electrode indicated that large bubbles were generated periodically, and that the DO profile depended on the geometrical relationship between the electrode and the bubbles. PMID:16772694

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

    PubMed

    Hall, Lenwood W; Anderson, Ronald D

    2013-01-01

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

  18. Rates of zinc and trace metal release from dissolving sphalerite at pH 2.0-4.0

    USGS Publications Warehouse

    Stanton, M.R.; Gemery-Hill, P. A.; Shanks, Wayne C.; Taylor, C.D.

    2008-01-01

    High-Fe and low-Fe sphalerite samples were reacted under controlled pH conditions to determine nonoxidative rates of release of Zn and trace metals from the solid-phase. The release (solubilization) of trace metals from dissolving sphalerite to the aqueous phase can be characterized by a kinetic distribution coefficient, (Dtr), which is defined as [(Rtr/X(tr)Sph)/(RZn/X(Zn) Sph)], where R is the trace metal or Zn release rate, and X is the mole fraction of the trace metal or Zn in sphalerite. This coefficient describes the relationship of the sphalerite dissolution rate to the trace metal mole fraction in the solid and its aqueous concentration. The distribution was used to determine some controls on metal release during the dissolution of sphalerite. Departures from the ideal Dtr of 1.0 suggest that some trace metals may be released via different pathways or that other processes (e.g., adsorption, solubility of trace minerals such as galena) affect the observed concentration of metals. Nonoxidative sphalerite dissolution (mediated by H+) is characterized by a "fast" stage in the first 24-30 h, followed by a "slow" stage for the remainder of the reaction. Over the pH range 2.0-4.0, and for similar extent of reaction (reaction time), sphalerite composition, and surface area, the rates of release of Zn, Fe, Cd, Cu, Mn and Pb from sphalerite generally increase with lower pH. Zinc and Fe exhibit the fastest rates of release, Mn and Pb have intermediate rates of release, and Cd and Cu show the slowest rates of release. The largest variations in metal release rates occur at pH 2.0. At pH 3.0 and 4.0, release rates show less variation and appear less dependent on the metal abundance in the solid. For the same extent of reaction (100 h), rates of Zn release range from 1.53 ?? 10-11 to 5.72 ?? 10-10 mol/m2/s; for Fe, the range is from 4.59 ?? 10-13 to 1.99 ?? 10-10 mol/m2/s. Trace metal release rates are generally 1-5 orders of magnitude slower than the Zn or Fe rates

  19. Use of dissolved H2 concentrations to determine distribution of microbially catalyzed redox reactions in anoxic groundwater

    USGS Publications Warehouse

    Lovley, D.R.; Chapelle, F.H.; Woodward, J.C.

    1994-01-01

    The potential for using concentrations of dissolved H2 to determine the distribution of redox processes in anoxic groundwaters was evaluated. In pristine aquifers in which standard geochemical measurements indicated that Fe-(III) reduction, sulfate reduction, or methanogenesis was the terminal electron accepting process (TEAP), the H2 concentrations were similar to the H2 concentrations that have previously been reported for aquatic sediments with the same TEAPs. In two aquifers contaminated with petroleum products, it was impossible with standard geochemical analyses to determine which TEAPs predominated in specific locations. However, the TEAPs predicted from measurements of dissolved H2 were the same as those determined directly through measurements of microbial processes in incubated aquifer material. These results suggest that H2 concentrations may be a useful tool for analyzing the redox chemistry of nonequilibrium groundwaters.

  20. Henry's Law vaporization studies and thermodynamics of einsteinium-253 metal dissolved in ytterbium

    SciTech Connect

    Kleinschmidt, P.D.; Ward, J.W.; Matlack, G.M.; Haire, R.G.

    1984-07-01

    The cohesive energy of metallic einsteinium determines whether einsteinium is a trivalent or divalent metal. The enthalpy of sublimation, a measure of the cohesive energy, is calculated from the partial pressures of einsteinium over an alloy. The partial pressure of /sup 253/Es has been measured over the range 470--870 K, using combined target and mass spectrometric Knudsen effusion techniques. An alloy was prepared with einsteinium dissolved in a ytterbium solvent to produce a very dilute solution. Partial pressure measurements on the alloy were amenable to the experimental technique and a data analysis using a Henry's law treatment of the data. Vapor pressure data are combined with an estimated crystal entropy S/sup 0//sub 298/ and ..delta..C/sup 0//sub p/ for ytterbium, to produce enthalpy, entropy, and free energy functions from 298 to 1300 K. The vapor pressure of einsteinium in a dilute einsteinium--ytterbium alloy is described by the equation log P(atm) = -(6815 +- 216)/T+2.576 +- 0.337, from which we calculate for the enthalpy of sublimation of pure einsteinium ..delta..H/sup 0//sub 298/ (second law) = 31.76 kcal/mol. The value of the enthalpy of sublimation is consistent with the conclusion that Es is a divalent metal.

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

    USGS Publications Warehouse

    Tillman, Fred D; Anning, David W.

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Tillman, Fred D.; Anning, David W.

    2014-11-01

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

  3. Response of oxidative enzyme activities to nitrogen deposition affects soil concentrations of dissolved organic carbon

    USGS Publications Warehouse

    Waldrop, M.P.; Zak, D.R.

    2006-01-01

    Recent evidence suggests that atmospheric nitrate (NO3- ) deposition can alter soil carbon (C) storage by directly affecting the activity of lignin-degrading soil fungi. In a laboratory experiment, we studied the direct influence of increasing soil NO 3- concentration on microbial C cycling in three different ecosystems: black oak-white oak (BOWO), sugar maple-red oak (SMRO), and sugar maple-basswood (SMBW). These ecosystems span a broad range of litter biochemistry and recalcitrance; the BOWO ecosystem contains the highest litter lignin content, SMRO had intermediate lignin content, and SMBW leaf litter has the lowest lignin content. We hypothesized that increasing soil solution NO 3- would reduce lignolytic activity in the BOWO ecosystem, due to a high abundance of white-rot fungi and lignin-rich leaf litter. Due to the low lignin content of litter in the SMBW, we further reasoned that the NO3- repression of lignolytic activity would be less dramatic due to a lower relative abundance of white-rot basidiomycetes; the response in the SMRO ecosystem should be intermediate. We increased soil solution NO3- concentrations in a 73-day laboratory incubation and measured microbial respiration and soil solution dissolved organic carbon (DOC) and phenolics concentrations. At the end of the incubation, we measured the activity of ??-glucosidase, N-acetyl-glucosaminidase, phenol oxidase, and peroxidase, which are extracellular enzymes involved with cellulose and lignin degradation. We quantified the fungal biomass, and we also used fungal ribosomal intergenic spacer analysis (RISA) to gain insight into fungal community composition. In the BOWO ecosystem, increasing NO 3- significantly decreased oxidative enzyme activities (-30% to -54%) and increased DOC (+32% upper limit) and phenolic (+77% upper limit) concentrations. In the SMRO ecosystem, we observed a significant decrease in phenol oxidase activity (-73% lower limit) and an increase in soluble phenolic concentrations

  4. 46 CFR 148.285 - Metal sulfide concentrates.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Metal sulfide concentrates. 148.285 Section 148.285... MATERIALS THAT REQUIRE SPECIAL HANDLING Special Requirements for Certain Materials § 148.285 Metal sulfide concentrates. (a) When information given by the shipper under § 148.60 of this part indicates that the...

  5. 46 CFR 148.285 - Metal sulfide concentrates.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Metal sulfide concentrates. 148.285 Section 148.285... MATERIALS THAT REQUIRE SPECIAL HANDLING Special Requirements for Certain Materials § 148.285 Metal sulfide concentrates. (a) When information given by the shipper under § 148.60 of this part indicates that the...

  6. 46 CFR 148.285 - Metal sulfide concentrates.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Metal sulfide concentrates. 148.285 Section 148.285... MATERIALS THAT REQUIRE SPECIAL HANDLING Special Requirements for Certain Materials § 148.285 Metal sulfide concentrates. (a) When information given by the shipper under § 148.60 of this part indicates that the...

  7. Closed-loop identification and control application for dissolved oxygen concentration in a full-scale coke wastewater treatment plant.

    PubMed

    Yoo, C K; Cho, J H; Kwak, H J; Choi, S K; Chun, H D; Lee, I

    2001-01-01

    The objective of this paper is to apply a closed-loop identification to actual dissolved oxygen control system in the coke wastewater treatment plant. It approximates the dissolved oxygen dynamics to a high order model using the integral transform method and reduces it to the first-order plus time delay (FOPTD) or second-order plus time delay (SOPTD) for the PID controller tuning. To experiment the process identification on the real plant, a simple set-point change of the speed of surface aerator under the closed-loop control without any mode change was used as an activation signal of the identification. The full-scale experimental results show a good identification performance and a good tracking ability for set-point change. As a result of improved control performance, the fluctuation of dissolved oxygen concentration variation has been decreased and the electric power saving has been accomplished.

  8. Closed-loop identification and control application for dissolved oxygen concentration in a full-scale coke wastewater treatment plant.

    PubMed

    Yoo, C K; Cho, J H; Kwak, H J; Choi, S K; Chun, H D; Lee, I

    2001-01-01

    The objective of this paper is to apply a closed-loop identification to actual dissolved oxygen control system in the coke wastewater treatment plant. It approximates the dissolved oxygen dynamics to a high order model using the integral transform method and reduces it to the first-order plus time delay (FOPTD) or second-order plus time delay (SOPTD) for the PID controller tuning. To experiment the process identification on the real plant, a simple set-point change of the speed of surface aerator under the closed-loop control without any mode change was used as an activation signal of the identification. The full-scale experimental results show a good identification performance and a good tracking ability for set-point change. As a result of improved control performance, the fluctuation of dissolved oxygen concentration variation has been decreased and the electric power saving has been accomplished. PMID:11385849

  9. Trace metal concentrations in estuaries and coastal regions

    SciTech Connect

    Hunt, C.D.

    1994-12-31

    Estuaries and coastal regions are highly variable in the physical and hydrographic conditions. As a result of heavy urbanization and industrialization of the head waters of most estuaries, there are substantial localized inputs of contaminants to the estuary. These factors combined with the flushing characteristics of individual estuaries to create relatively unique features that result in variation in the typical levels of trace metals for these systems. This makes intercomparison of the estuaries difficult. Comparability among estuaries becomes even more difficult when metals analyses are conducted without proper control of field and laboratory contamination, now firmly established in the trace metal analytical literature as a prerequisite for reliable marine trace metals analysis. This paper compares the concentrations of selected trace metal (Ag, Cd, Cu, Ni, Pb, and Zn) concentrations in the waters of several major estuaries of the United States. The basis of comparison is that all samples war collected under rigid trace metal clean collection and analysis procedures. Generally, metal concentrations within the estuaries are similar. Metal concentrations in the higher salinity coastal regions are more similar in concentration. The comparison provides a baseline of typical concentrations of these trace metals in the coastal waters against which future analytical results can be compared.

  10. Dissolved Pesticide and Organic Carbon Concentrations Detected in Surface Waters, Northern Central Valley, California, 2001-2002

    USGS Publications Warehouse

    Orlando, James L.; Jacobson, Lisa A.; Kuivila, Kathryn M.

    2004-01-01

    Field and laboratory studies were conducted to determine the effects of pesticide mixtures on Chinook salmon under various environmental conditions in surface waters of the northern Central Valley of California. This project was a collaborative effort between the U.S. Geological Survey (USGS) and the University of California. The project focused on understanding the environmental factors that influence the toxicity of pesticides to juvenile salmon and their prey. During the periods January through March 2001 and January through May 2002, water samples were collected at eight surface water sites in the northern Central Valley of California and analyzed by the USGS for dissolved pesticide and dissolved organic carbon concentrations. Water samples were also collected by the USGS at the same sites for aquatic toxicity testing by the Aquatic Toxicity Laboratory at the University of California Davis; however, presentation of the results of these toxicity tests is beyond the scope of this report. Samples were collected to characterize dissolved pesticide and dissolved organic carbon concentrations, and aquatic toxicity, associated with winter storm runoff concurrent with winter run Chinook salmon out-migration. Sites were selected that represented the primary habitat of juvenile Chinook salmon and included major tributaries within the Sacramento and San Joaquin River Basins and the Sacramento?San Joaquin Delta. Water samples were collected daily for a period of seven days during two winter storm events in each year. Additional samples were collected weekly during January through April or May in both years. Concentrations of 31 currently used pesticides were measured in filtered water samples using solid-phase extraction and gas chromatography-mass spectrometry at the U.S. Geological Survey's organic chemistry laboratory in Sacramento, California. Dissolved organic carbon concentrations were analyzed in filtered water samples using a Shimadzu TOC-5000A total organic carbon

  11. Diatom stratigraphy and long-term dissolved silica concentrations in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Olli, Kalle; Clarke, Annemarie; Danielsson, Åsa; Aigars, Juris; Conley, Daniel J.; Tamminen, Timo

    2008-10-01

    In many parts of the world coastal waters with anthropogenic eutrophication have experienced a gradual depletion of dissolved silica (DSi) stocks. This could put pressure on spring bloom diatom populations, e.g. by limiting the intensity of blooms or by causing shifts in species composition. In addition, eutrophication driven enhanced diatom growth is responsible for the redistribution of DSi from the water phase to the sediments, and changes in the growth conditions may be reflected in the sediment diatom stratigraphy. To test for changes in diatom communities we have analyzed four sediment cores from the Baltic Sea covering approximately the last 100 years. The sediment cores originate from the western Gulf of Finland, the Kattegat, the Baltic Proper and the Gulf of Riga. Three out of the four cores reveal only minor changes in composition of diatom assemblages, while the Gulf of Riga core contains major changes, occurring after the second World War. This area is set apart from the other Baltic Sea basins by a high frequency of low after spring bloom DSi concentrations (< 2 µmol L - 1 ) during a relatively well defined time period from 1991-1998. In 1991 to 1993 a rapid decline of DSi spring concentrations and winter stocks (down to 5 µmol L - 1 ) in the Gulf was preceded by exceptionally intense diatom spring blooms dominated by the heavily silicified species Thalassiosira baltica (1991-1992; up to 5.5 mg ww L - 1 ). T. baltica has been the principal spring bloom diatom in the Gulf of Riga since records began in 1975. DSi consumption and biomass yield experiments with cultured T. baltica suggest that intense blooms can potentially exhaust the DSi stock of the water column and exceed the annual Si dissolution in the Gulf of Riga. The phytoplankton time series reveals another exceptional T. baltica bloom period in 1981-1983 (up to 8 mg L - 1 ), which, however, took place before the regular DSi measurements. These periods may be reflected in the conspicuous

  12. ION EXCHANGE SOFTENING: EFFECTS ON METAL CONCENTRATIONS

    EPA Science Inventory

    A corrosion control pipe loop study to evaluate the effect of ion exchange water softening on metal leaching from household plumbing materials was conducted on two different water qualities having different pH's and hardness levels. The results showed that removing hardness ions ...

  13. Maximizing biomass concentration in baker's yeast process by using a decoupled geometric controller for substrate and dissolved oxygen.

    PubMed

    Chopda, Viki R; Rathore, Anurag S; Gomes, James

    2015-11-01

    Biomass production by baker's yeast in a fed-batch reactor depends on the metabolic regime determined by the concentration of glucose and dissolved oxygen in the reactor. Achieving high biomass concentration in turn is dependent on the dynamic interaction between the glucose and dissolved oxygen concentration. Taking this into account, we present in this paper the implementation of a decoupled input-output linearizing controller (DIOLC) for maximizing biomass in a fed-batch yeast process. The decoupling is based on the inversion of 2×2 input-output matrix resulting from global linearization. The DIOLC was implemented online using a platform created in LabVIEW employing a TCP/IP protocol via the reactor's built-in electronic system. An improvement in biomass yield by 23% was obtained compared to that using a PID controller. The results demonstrate superior capability of the DIOLC and that the cumulative effect of smoother control action contributes to biomass maximization. PMID:26233328

  14. Understanding and modelling the variability in Dissolved Organic Carbon concentrations in catchment drainage

    NASA Astrophysics Data System (ADS)

    Coleman, Martin; Waldron, Susan; Scott, Marian; Drew, Simon

    2013-04-01

    Our knowledge of dynamic natural habitats could be improved through the deployment of automated sensor technology. Dissolved organic carbon concentrations, [DOC], are of interest to water companies as purification removes this pool and currently in environmental science, due in part to rising DOC levels and also as respiration of this C pool can lead to an increased CO2 efflux. Manual sampling of catchment drainage systems has revealed seasonal patterns in DOC (Williams, P.J.L., 1995) and that hydrological events export most DOC(Raymond, P.A. and J.E. Saiers, 2010). However, manual sampling precludes detailed characterisation of the dynamic fluctuation of DOC over shorter but important time periods e.g. immediately prior to an event; the transition from base flow to a surface run-off dominated system as surface flow pathways defrost. Such insight is only gained through deployment of continuous-monitoring equipment. Since autumn 2010 we have deployed an S::CAN Spectrolyser (which from absorbance gives a measurement of [DOC]) in a 7.5 kilometre squared peaty catchment draining Europe's largest windfarm, Whitelee. Since autumn 2011, we have an almost complete time series of [DOC] every 30. Here [DOC] has ranged from 12.2 to 58.4 mg/l C and during event flow DOC had a maximum variation of 23.5 mg/l within a single day. Simultaneously with the Spectrolyser, we have logged stage height, pH and conductivity using an In-Situ Inc MD Troll 9000. Generally there is an inverse relationship between [DOC] and both pH and conductivity, but a positive relationship (albeit with seasonal differences) with [DOC] and stage height, from which we can infer hydrological changes in the source of the DOC. Here, in addition to presenting the time series of the data, and a more accurate export budget estimate, I will explore statistical methods for the handling of large datasets. Trends in the data of such large and dynamic data sets are challenging to model. Simple relationships with stage

  15. Risk assessment, statistical source identification and seasonal fluctuation of dissolved metals in the Subarnarekha River, India.

    PubMed

    Giri, Soma; Singh, Abhay Kumar

    2014-01-30

    Surface water samples were collected from 21 sampling sites throughout the Subarnarekha River during pre monsoon, monsoon and post monsoon seasons. The concentrations of metals were determined using inductively coupled plasma-mass spectrometry (ICP-MS) for the seasonal fluctuation, source apportionment and risk assessment. The results demonstrated that concentrations of the metals showed significant seasonality and most variables exhibited higher levels in the pre monsoon season. Principal component analysis (PCA) outcome of four factors together explained 76.9% of the variance with >1 initial eigenvalue indicated both innate and anthropogenic activities are contributing factors as source of metal profusion in Subarnarekha River. Risk of metals on human health was then evaluated using hazard quotients (HQ) by ingestion and dermal pathways for adult and child and it was indicated that As with HQingestion>1, was the most important pollutant leading to non-carcinogenic concerns. The largest contributors to chronic risks were As, V and Co, in all the seasons. The HQdermal of all the elements for adult and child were below unity, suggesting that the metals posed little hazards via dermal absorption indicating that the oral intake was the primary exposure pathway. PMID:24184125

  16. Risk assessment, statistical source identification and seasonal fluctuation of dissolved metals in the Subarnarekha River, India.

    PubMed

    Giri, Soma; Singh, Abhay Kumar

    2014-01-30

    Surface water samples were collected from 21 sampling sites throughout the Subarnarekha River during pre monsoon, monsoon and post monsoon seasons. The concentrations of metals were determined using inductively coupled plasma-mass spectrometry (ICP-MS) for the seasonal fluctuation, source apportionment and risk assessment. The results demonstrated that concentrations of the metals showed significant seasonality and most variables exhibited higher levels in the pre monsoon season. Principal component analysis (PCA) outcome of four factors together explained 76.9% of the variance with >1 initial eigenvalue indicated both innate and anthropogenic activities are contributing factors as source of metal profusion in Subarnarekha River. Risk of metals on human health was then evaluated using hazard quotients (HQ) by ingestion and dermal pathways for adult and child and it was indicated that As with HQingestion>1, was the most important pollutant leading to non-carcinogenic concerns. The largest contributors to chronic risks were As, V and Co, in all the seasons. The HQdermal of all the elements for adult and child were below unity, suggesting that the metals posed little hazards via dermal absorption indicating that the oral intake was the primary exposure pathway.

  17. Concentration and characteristics of dissolved carbon in the Sanjiang Plain influenced by long-term land reclamation from marsh.

    PubMed

    Guo, Y D; Lu, Y Z; Song, Y Y; Wan, Z M; Hou, A X

    2014-01-01

    Since the 1960s, the marshes in the Sanjiang Plain, Northeast China, which are an important reservoir for dissolved carbon, have undergone long-term reclamation to farmland, resulting in elevated marsh loss and degradation on a large scale. This study compared the concentrations of dissolved carbon, as well as the chemical characteristics of dissolved organic carbon (DOC), in natural marshes, a degraded marsh, and drainage ditches sampled during the growing seasons between 2008 and 2010 to clarify the temporal-spatial variability of the dissolved carbon in the fluvial system influenced by the long-term reclamation. The results show that the average concentrations of total dissolved carbon (TDC) and DOC are considerably greater in the natural marshes than in the degraded marsh and drainage ditches. The average DOC concentration for the natural marshes, approximately 35.53 ± 5.15 mg L(-1), is approximately 2.39 times that in the degraded marsh (14.84 ± 4.21 mg L(-1)) and 2.77 times the average value in the ditches (12.84 ± 4.49 mg L(-1)). The dissolved inorganic carbon (DIC) exhibits increased trends in the drainage ditches compared with the natural marshes, whereas the hydrophobic fraction of DOC is present at lower concentrations in the degraded marsh and ditches. Fluorescence indices also indicate that the DOC in the degraded marsh and ditches has a simpler humification structure. In total, the long-term reclamation has led to great variability in the DOC concentration and chemical characteristics in the fluvial system. Changes in the DOC production potential and hydrological regimes due to sustained reclamation are deemed the predominant causes of this effect. The continuously decreased DOC concentration and high variability of DOC in the surface fluvial systems are inevitable if reclamation continues in the Sanjiang Plain. More importantly, the presence of tyrosine and tryptophan-like substances in the ditches indicates that there has been extensive

  18. Concentration and characteristics of dissolved carbon in the Sanjiang Plain influenced by long-term land reclamation from marsh.

    PubMed

    Guo, Y D; Lu, Y Z; Song, Y Y; Wan, Z M; Hou, A X

    2014-01-01

    Since the 1960s, the marshes in the Sanjiang Plain, Northeast China, which are an important reservoir for dissolved carbon, have undergone long-term reclamation to farmland, resulting in elevated marsh loss and degradation on a large scale. This study compared the concentrations of dissolved carbon, as well as the chemical characteristics of dissolved organic carbon (DOC), in natural marshes, a degraded marsh, and drainage ditches sampled during the growing seasons between 2008 and 2010 to clarify the temporal-spatial variability of the dissolved carbon in the fluvial system influenced by the long-term reclamation. The results show that the average concentrations of total dissolved carbon (TDC) and DOC are considerably greater in the natural marshes than in the degraded marsh and drainage ditches. The average DOC concentration for the natural marshes, approximately 35.53 ± 5.15 mg L(-1), is approximately 2.39 times that in the degraded marsh (14.84 ± 4.21 mg L(-1)) and 2.77 times the average value in the ditches (12.84 ± 4.49 mg L(-1)). The dissolved inorganic carbon (DIC) exhibits increased trends in the drainage ditches compared with the natural marshes, whereas the hydrophobic fraction of DOC is present at lower concentrations in the degraded marsh and ditches. Fluorescence indices also indicate that the DOC in the degraded marsh and ditches has a simpler humification structure. In total, the long-term reclamation has led to great variability in the DOC concentration and chemical characteristics in the fluvial system. Changes in the DOC production potential and hydrological regimes due to sustained reclamation are deemed the predominant causes of this effect. The continuously decreased DOC concentration and high variability of DOC in the surface fluvial systems are inevitable if reclamation continues in the Sanjiang Plain. More importantly, the presence of tyrosine and tryptophan-like substances in the ditches indicates that there has been extensive

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

    USGS Publications Warehouse

    Anning, David W.; Flynn, Marilyn E.

    2014-01-01

    Results from the trend analysis and from the SPARROW model indicate that, compared to monitoring stations with no trends or decreasing trends, stations with increasing trends are associated with a smaller percentage of the predicted dissolved-solids load originating from geologic sources, and a larger percentage originating from urban lands and road deicers. Conversely, compared to stations with increasing trends or no trends, stations with decreasing trends have a larger percentage of the predicted dissolved-solids load originating from geologic sources and a smaller percentage originating from urban lands and road deicers. Stations with decreasing trends also have larger percentages of predicted dissolved-solids load originating from cultivated lands and pasture lands, compared to stations with increasing trends or no trends.

  20. Analysis of environmental issues related to small-scale hydroelectric development. VI. Dissolved oxygen concentrations below operating dams

    SciTech Connect

    Cada, G.F.; Kumar, K.D.; Solomon, J.A.; Hildebrand, S.G.

    1982-01-01

    Results are presented of an effort aimed at determining whether or not water quality degradation, as exemplified by dissolved oxygen concentrations, is a potentially significant issue affecting small-scale hydropower development in the US. The approach was to pair operating hydroelectric sites of all sizes with dissolved oxygen measurements from nearby downstream US Geological Survey water quality stations (acquired from the WATSTORE data base). The USGS data were used to calculate probabilities of non-compliance (PNCs), i.e., the probabilities that dissolved oxygen concentrations in the discharge waters of operating hydroelectric dams will drop below 5 mg/l. PNCs were estimated for each site, season (summer vs remaining months), and capacity category (less than or equal to 30 MW vs >30 MW). Because of the low numbers of usable sites in many states, much of the subsequent analysis was conducted on a regional basis. During the winter months (November through June) all regions had low mean PNCs regardless of capacity. Most regions had higher mean PNCs in summer than in winter, and summer PNCs were greater for large-scale than for small-scale sites. Among regions, the highest mean summer PNCs were found in the Great Basin, the Southeast, and the Ohio Valley. To obtain a more comprehensive picture of the effects of season and capacity on potential dissolved oxygen problems, cumulative probability distributions of PNC were developed for selected regions. This analysis indicates that low dissolved oxygen concentrations in the tailwaters below operating hydroelectric projects are a problem largely confined to large-scale facilities.

  1. Assessment of dissolved Pb concentration and isotopic composition in surface waters of the modern global ocean

    NASA Astrophysics Data System (ADS)

    Pinedo-Gonzalez, P.; West, A. J.; Sanudo-Wilhelmy, S. A.

    2015-12-01

    Lead (Pb) produced by human activities, mainly from leaded gasoline combustion and high-temperature industries, dominates Pb in our present-day oceans. Previous studies have shown that surface ocean Pb concentrations and isotope ratios have varied in time and space, reflecting the changes in the amount of inputs and sources of anthropogenic Pb. However, data on surface ocean Pb is quite limited, especially for some basins like the Indian Ocean. In the present study, Pb concentrations and stable isotopes (208, 207, and 206) have been analyzed in surface water samples (3m depth) collected during the Malaspina Circumnavigation Expedition, 2010. Our results are compared with data from the literature to i) evaluate the changing status of metal contamination in surface waters of the global ocean over the last 30 years, and ii) propose potential sources of modern Pb to the oceans. Our results show that Pb concentrations in surface waters of the North Atlantic Ocean have decreased ~ 40% since 1975, attributable to the phase-out of leaded gasoline in North America. This result is corroborated by stable Pb isotope measurements. Furthermore, the isotopic gradient observed in surface waters of the studied transects in the north tropical and subtropical Atlantic Ocean can be attributed to simple mixing of European and African aerosols and Saharan Holocene loess. Results from an understudied transect in the Southern Indian Ocean give an indication of the source region of Pb delivered to this region. Although comparison with literature data is limited, mixing of Australian ores and African and Australian coals could potentially explain the measured Pb isotope composition. This study provides an opportunity to build on the work of previous oceanographic campaigns, enabling us to assess the impact of anthropogenic Pb inputs to the ocean and the relative importance of various Pb sources, providing new insights into the transport and fate of Pb in the oceans.

  2. Heavy metal concentrations along the Louisiana coastal zone

    SciTech Connect

    Pardue, J.H.; DeLaune, R.D.; Smith, C.J.; Patrick, W.H. Jr.

    1988-01-01

    Cores were taken from seven locations in southern Louisiana and analyzed for concentrations of heavy metals. Sedimentation rates for the locations were determined using the /sup 137/Cs dating technique. Correlations of metals with depth were calculated using absolute, aluminum normalized, and iron normalized concentrations. Correlations indicated recent increases at several sites (Lake Palourde, Manchac Pass, and Wax Lake Outlet) for several metals (Pb, Cd, Cr, Ni, Zn) when profiles were normalized to aluminum. Metal profiles from rapidly-accreting areas (Atchafalaya and Four league Bay) did not show historical increases comparable to areas accreting less rapidly (e.g., Wax Lake Outlet, Manchac Pass, and Lake Palourde).

  3. Concentrations of dissolved methane (CH sub 4 ) and nitrogen (N sub 2 ) in groundwaters from the Hanford Site, Washington

    SciTech Connect

    Early, T.O.

    1986-03-14

    This document reports all available dissolved gas concentration data for groundwaters from the Hanford Site as of June 1985. Details of the computational procedures required to reduce data obtained from the field measurements made by the Basalt Waste Isolation Project are provided in the appendix. Most measured values for methane concentration from reference repository boreholes are in the range of from 350 to 700 mg/L for the Cohassett flow top. Because of the uncertainties associated with these measurements, it is currently recommended that a conservative methane concentration of 1200 mg/L (methane saturated) in groundwater be considered the most reasonable upper-bounding value. 16 refs., 2 figs., 2 tabs.

  4. Control of impurity concentration in liquid metals by neutron scattering

    SciTech Connect

    Morozov, V. A.; Novikov, A. G.; Savostin, V. V.

    2011-12-15

    A technique is proposed for determining the impurity concentration in liquid metal-impurity systems. This technique does not require special measurements or geometry: information about the impurity concentration can be obtained directly from the data collected during the diffraction experiment. The impurity concentrations in a lead melt with a potassium impurity and in a sodium melt with a lead impurity are determined.

  5. Effect of water hardness and dissolved-solid concentration on hatching success and egg size in bighead carp

    USGS Publications Warehouse

    Chapman, Duane C.; Deters, Joseph E.

    2009-01-01

    Bighead carp Hypophthalmichthys nobilis is an Asian species that has been introduced to the United States and is regarded as a highly undesirable invader. Soft water has been said to cause the bursting of Asian carp eggs and thus has been suggested as a factor that would limit the spread of this species. To evaluate this, we subjected fertilized eggs of bighead carp to waters with a wide range of hardness and dissolved-solid concentrations. Hatching rate and egg size were not significantly affected by the different water qualities. These results, combined with the low hardness (28–84 mg/L) of the Yangtze River (the primary natal habitat of Hypophthalmichthys spp.), suggest that managers and those performing risk assessments for the establishment of Hypophthalmichthys spp. should be cautious about treating low hardness and dissolved-solid concentrations as limiting factors.

  6. Long-term trends in dissolved iron and DOC concentration linked to nitrate depletion in riparian soils

    NASA Astrophysics Data System (ADS)

    Musolff, Andreas; Selle, Benny; Fleckenstein, Jan H.; Oosterwoud, Marieke R.; Tittel, Jörg

    2016-04-01

    The instream concentrations of dissolved organic carbon (DOC) are rising in many catchments of the northern hemisphere. Elevated concentrations of DOC, mainly in the form of colored humic components, increase efforts and costs of drinking water purification. In this study, we evaluated a long-term dataset of 110 catchments draining into German drinking water reservoirs in order to assess sources of DOC and drivers of a potential long-term change. The average DOC concentrations across the wide range of different catchments were found to be well explained by the catchment's topographic wetness index. Higher wetness indices were connected to higher average DOC concentrations, which implies that catchments with shallow topography and pronounced riparian wetlands mobilize more DOC. Overall, 37% of the investigated catchments showed a significant long-term increase in DOC concentrations, while 22% exhibited significant negative trends. Moreover, we found that increasing trends in DOC were positively correlated to trends in dissolved iron concentrations at pH≤6 due to remobilization of DOC previously sorbed to iron minerals. Both, increasing trends in DOC and dissolve iron were found to be connected to decreasing trends and low concentrations of nitrate (below ~6 mg/L). This was especially observed in forested catchments where atmospheric N-depositions were the major source for nitrate availability. In these catchments, we also found long-term increases of phosphate concentrations. Therefore, we argue that dissolved iron, DOC and phosphate were jointly released under iron-reducing conditions when nitrate as a competing electron acceptor was too low in concentrations to prevent the microbial iron reduction. In contrast, we could not explain the observed increasing trends in DOC, iron and phosphate concentrations by the long-term trends of pH, sulfate or precipitation. Altogether this study gives strong evidence that both, source and long-term increases in DOC are

  7. A case study on trace metals in surface sediments and dissolved inorganic nutrients in surface water of Olüdeniz Lagoon-Mediterranean, Turkey.

    PubMed

    Tuncel, Semra G; Tugrul, Suleyman; Topal, Tansel

    2007-01-01

    Hydro-chemical parameters (salinity, temperature, pH, dissolved oxygen, nitrate, silicate and phosphate) in seawater and major trace metals (Al, Fe, Mn, Cr, V, Zn, Pb, Cu) in sediments were evaluated for the assessment of quality of seawater and sediments in very small lagoon in Mediterranean, Olüdeniz. Enrichment factors for metals in sediment were in the range of 1.62-8.09, comparable to crustal rock composition. For metals, comparison with literature data revealed relatively low metal concentrations for Olüdeniz sediments. Correlation analyses on the sediment metal data showed strong correlation in between Cr, Fe and Zn. Surface water salinity slightly decreases within the lagoon, indicating that limited fresh waters inflow to the lagoon. In October, the lagoon waters contained very low phosphate concentrations but measurable values of nitrate and silicate, yielding high NO(3)(-)/PO(4)(3-) ratios (90). Very low Chlorophyll-a (biomass indicator) concentrations measured in the lagoon suggest the phosphorus limitation of primary productivity.

  8. Concentrations of metals in very small volumes of soil solution

    USGS Publications Warehouse

    Hinkley, T.

    1979-01-01

    A new method of sampling very small amounts of soil solution (0.3 g) shows that soil solutions contain high concentrations and unusual proportions of metals. In the soils studied, the solution is close in both metal proportions and total metal mass to what may be taken up annually by the growth of plants at the sites sampled. Composition of soil solution varies seasonally and with depth in soil. ?? 1979 Nature Publishing Group.

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

    USGS Publications Warehouse

    Thiros, Susan; Spangler, Larry

    2010-01-01

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

  10. Factors Controlling Concentration of Metals in the Leachate from Aerobic and Anaerobic Laboratory Landfill Bioreactors

    NASA Astrophysics Data System (ADS)

    Greenberg, M. R.; Hazen, T. C.; Borglin, S. E.; Oldenburg, C. M.

    2001-12-01

    Costs and environmental issues associated with operating municipal landfills have motivated laboratory experiments investigating methods to increase biodegradation and decrease fugitive emissions of both liquid and gas. Rates of settling, biodegradation, and emissions were measured in three large laboratory-scale bioreactors filled with 30 kg of typical municipal waste. The bioreactors (200-L clear acrylic tanks) were instrumented to monitor pressure, temperature, moisture, humidity, gas composition, and leachate composition. Three treatments were applied: 1) aerobic (air injection with water addition and recirculation), 2) anaerobic (no air injection, water addition and recirculation), and 3) a control tank (no air or water injection). Preliminary studies showed measurable concentrations of Fe, Ba, Cu, Al, Mn, Ni, and Zn in the leachate. To investigate this further, bi-weekly leachate samples were, and were analyzed for dissolved Fe, Ba, Cu, Al, Mn, Ni, Zn. NO3-, NO2-, NH4+, PO43-, SO42-, Cl-, Fl-, Na+, Ca2, total organic acid, Eh and pH. The aerobic tank leachate had metals concentrations that were an order of magnitude lower than the leachate from the anaerobic tank. Possible explanations include the existence of fewer organic-metal complexes due to the decrease in the dissolved organic matter in the leachate for the aerobic treatment, or the higher pH and redox potential in the aerobic treatment. A sensitivity analysis was performed using MINTEQA2, a U.S. EPA geochemical speciation model that reports on metal speciation based on water composition parameters, for a combination of actual and estimated data. Initial results suggest that the presence of certain organic acids dramatically increases the metal-organic complexation, consistent with observations of greater metal concentrations in the anaerobic treatment leachate. This work was supported by Laboratory Directed Research and Development Funds at Lawrence Berkeley National Laboratory under Department of

  11. Spatial variability in dissolved organic matter and inorganic nitrogen concentrations in a semiarid stream, San Pedro River, Arizona

    NASA Astrophysics Data System (ADS)

    Brooks, Paul D.; Lemon, Michelle M.

    2007-09-01

    We performed synoptic sampling of a 95-km reach of the San Pedro River, Arizona, to identify the effects of regional hydrology and land use on dissolved carbon and nitrogen concentrations. Six synoptic surveys, two before, two during, and two after the 2002 monsoon season, encompassed periods of both low and high stream discharge. Chloride concentrations and δ18O values during low-flow periods indicated the river was divided into three hydrologically distinct reaches each roughly 30 km long. Upper and lower reaches were characterized by areas of localized groundwater input followed by downstream evapo-concentration gradients, limited downstream solute transport, and highly variable carbon and nitrogen concentrations. In contrast, the middle reach was characterized by widespread groundwater input, continuous downstream hydrologic connectivity, and less variable carbon and nitrogen concentrations. During the monsoon season, base flow discharge increased five- to ten-fold, dissolved organic matter and inorganic N increased two- to ten-fold, Fluorescence Index (FI) values indicated a large input of terrestrial solutes, and both chloride concentrations and δ18O values indicated that stream water and alluvial groundwater were well mixed along the entire 95 km reach. Concurrently, the middle reach that exhibited continuous hydrologic connectivity during the nonmonsoon season was a net sink for N, while the reaches characterized by limited hydrologic connectivity during the low-flow season exhibited net N export. Our data suggest that instream biogeochemical cycling during the monsoon season is influenced by antecedent conditions, specifically hydrologic connectivity, during the dry season.

  12. A procedure for predicting concentrations of dissolved solids and sulfate ion in streams draining areas strip mined for coal

    USGS Publications Warehouse

    Bevans, H.E.

    1980-01-01

    Current trends in increased coal production necessitate the development of techniques to appraise the environmental degradation resulting from strip mining. A procedure is introduced for the prediction of dissolved-solids and sulfate-ion concentrations in streams draining strip-mined areas. Concentrations are a function of the percentage of the drainage area that has been strip mined. These relationships are expressed by regression equations computed from data collected in streams draining strip-mined areas of Cherokee and Crawford Counties in southeast Kansas. High correlation coefficients indicate that the relationships may be useful in the evaluation of present or future strip-mining operations. (USGS)

  13. Fiber-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    DOEpatents

    Janke, Christopher J; Dai, Sheng; Oyola, Yatsandra

    2014-05-13

    A fiber-based adsorbent and a related method of manufacture are provided. The fiber-based adsorbent includes polymer fibers with grafted side chains and an increased surface area per unit weight over known fibers to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. The polymer fibers include a circular morphology in some embodiments, having a mean diameter of less than 15 microns, optionally less than about 1 micron. In other embodiments, the polymer fibers include a non-circular morphology, optionally defining multiple gear-shaped, winged-shaped or lobe-shaped projections along the length of the polymer fibers. A method for forming the fiber-based adsorbents includes irradiating high surface area polymer fibers, grafting with polymerizable reactive monomers, reacting the grafted fibers with hydroxylamine, and conditioning with an alkaline solution. High surface area fiber-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  14. Fiber-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    DOEpatents

    Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

    2016-09-06

    A fiber-based adsorbent and a related method of manufacture are provided. The fiber-based adsorbent includes polymer fibers with grafted side chains and an increased surface area per unit weight over known fibers to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. The polymer fibers include a circular morphology in some embodiments, having a mean diameter of less than 15 microns, optionally less than about 1 micron. In other embodiments, the polymer fibers include a non-circular morphology, optionally defining multiple gear-shaped, winged-shaped or lobe-shaped projections along the length of the polymer fibers. A method for forming the fiber-based adsorbents includes irradiating high surface area polymer fibers, grafting with polymerizable reactive monomers, reacting the grafted fibers with hydroxylamine, and conditioning with an alkaline solution. High surface area fiber-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  15. Long term patterns in dissolved organic carbon, major elements and trace metals in boreal headwater catchments: Trends, mechanisms and heterogeneity.

    NASA Astrophysics Data System (ADS)

    Oni, Stephen; Futter, Martyn; Bishop, Kevin; Kohler, Stephan; Ottosson-Lofvenius, Mikael; Laudon, Hjalmar

    2013-04-01

    The effects of climate change are currently apparent in the boreal landscape of northern Sweden. Warmer temperature and declining acid deposition are affecting runoff chemistry. These effects are mediated by landscape type. Markedly different responses are observed in streams draining forest and mire landscape elements. Here, we assess long-term water quality time-series from three nested headwater streams draining upland forest (C2), peat/mire (C4) and mixed (C7) (forest and mire) catchments. Temporal trends in weather and runoff (1981-2008); dissolved organic carbon concentration [DOC] (1993-2010) and other water quality parameters (1987-2011) were assessed. Historically, sulfate deposition is low in the region and is further declining. There was no significant annual trend in precipitation or runoff but a significant monotonic increasing trend existed in air temperature and length of growing season. Stream [DOC] was positively correlated with some trace metals (copper, iron and zinc) and negatively with several other chemical parameters (e.g. sulfate, conductivity, calcium). Both sulfate and conductivity showed declining trends, while a significant increase was observed in pH during winter and spring. Calcium and magnesium showed monotonic decreasing trends. The declining trajectories of stream base cation and sulfate concentrations during other times of the year were not accompanied by changes in pH and alkalinity. Water temperature increased significantly both annually and in most months while iron and DOC concentrations showed significant increases in autumn months. Though all streams showed significant positive trends in [DOC] in autumn, only C2 had a significant annual increasing trend. There was also a shift in the magnitude of variability in spring [DOC] and increasing trend of summer baseflow [DOC] in C2 and C7.

  16. Elemental concentrations and metal bioaccessibility in UK household dust.

    PubMed

    Turner, Andrew; Simmonds, Lindsey

    2006-12-01

    Concentrations of metals and C, H and N have been determined in 32 household dust samples collected from four regions of the UK. For a given metal, total concentrations (available to aqua regia digestion) were highly variable, but geometric mean concentrations (in mug g(-1): Al=7950; Cd=1.2; Cu=301; Fe=8740; Mn=524; Ni=53.1; Pb=150; Sn=23.9; Zn=622) were, in general, consistent with equivalent values reported in the contemporary literature for a number of locations worldwide. Of the metals studied, Cd, Cu, Pb, Sn and Zn exhibited greatest enrichment in the household environment relative to their respective crustal abundances. Bioaccessibility of metals in dust, evaluated using a simulated gastric solution (pepsin in dilute HCl), ranged from about 10% of total metal for Sn to about 80% for Cu, Pb and Zn, indicating that enrichment alone is not necessarily a good proxy for assessing metal exposure or impact. Concentrations of C, H and N in household dust, determined combustiometrically, ranged from 11% to 46.2%, 1.5% to 7.0% and 1.0% to 8.5%, respectively. Carbon to hydrogen ratios of dust samples were relatively uniform (arithmetic mean 7.3; rsd<10%), reflecting the similarity of C:H ratios in various source materials. In contrast, C:N ratios were highly variable (arithmetic mean 8.5; rsd>40%), reflecting the variability of C:N ratios in source materials (e.g. protein=2.1; soil humics=14; lignin=78). Lack of correlation between metal concentrations and concentrations or ratios of C, H and N was attributed to the heterogeneous distribution of metal concentrations among the array of internal and external sources of household dust.

  17. The spatial distribution of dissolved and particulate heavy metals and their response to land-based inputs and tides in a semi-enclosed industrial embayment: Jiaozhou Bay, China.

    PubMed

    Wang, Changyou; Liang, Shengkang; Li, Yanbin; Li, Keqiang; Wang, Xiulin

    2015-07-01

    In order to evaluate heavy metal contamination in surface waters in the Jiaozhou Bay (JZB), a typical semi-enclosed bay in the north of China, and to identify the response of heavy metal distribution to terrigenous sources and tides, the land-based discharge flux of dissolved Cu, Pb, Zn and Cd and their particulates, as well as their concentrations, were synchronously surveyed in JZB in flood season and normal season respectively. The survey results showed that the amount of dissolved Cu clearly increased from the estuaries to the offshore waters during the flood season, especially from the Dagu estuary to the mouth of JZB. The same trend was observed for Pb. The isopleths of dissolved Zn during the flood season presented a different pattern in which a clear decrease was observed from the Lianwan, Moshui and Dagu estuaries to the offshore waters. However, the particulate Cu isopleths during the flood season, which had the same pattern as those of particulate Pb, Zn and Cd, showed a clear decrease from the Dagu estuary to the mouth of JZB. The isopleths for dissolved and particulate Cu during the normal season showed a clear decrease from the northeast to the entrance of JZB, and the same trend was observed for Pb, Zn and Cd. Observations based on synchronous investigations of the fluvial fluxes of the selected metals and their average concentrations in JZB showed that these patterns were controlled by the strong external fluvial inputs, especially from the Dagu River. The diurnal change in the Cu, Pb, Zn and Cd concentrations showed a periodicity with a cycle length of approximately 12 h in JZB, which indicates the noticeable impact of the semi-diurnal tide. The weighed average concentration from freshwater inputs calculated for dissolved Cu, Pb, Zn and Cd were higher than their average concentrations in JZB. This indicated that JZB had been contaminated with these metals, whose concentrations were also higher than those found in uncontaminated waters.

  18. Development of a pre-concentration system and auto-analyzer for dissolved methane, ethane, propane, and butane concentration measurements with a GC-FID

    NASA Astrophysics Data System (ADS)

    Chepigin, A.; Leonte, M.; Colombo, F.; Kessler, J. D.

    2014-12-01

    Dissolved methane, ethane, propane, and butane concentrations in natural waters are traditionally measured using a headspace equilibration technique and gas chromatograph with flame ionization detector (GC-FID). While a relatively simple technique, headspace equilibration suffers from slow equilibration times and loss of sensitivity due to concentration dilution with the pure gas headspace. Here we present a newly developed pre-concentration system and auto-analyzer for use with a GC-FID. This system decreases the time required for each analysis by eliminating the headspace equilibration time, increases the sensitivity and precision with a rapid pre-concentration step, and minimized operator time with an autoanalyzer. In this method, samples are collected from Niskin bottles in newly developed 1 L plastic sample bags rather than glass vials. Immediately following sample collection, the sample bags are placed in an incubator and individually connected to a multiport sampling valve. Water is pumped automatically from the desired sample bag through a small (6.5 mL) Liqui-Cel® membrane contactor where the dissolved gas is vacuum extracted and directly flushed into the GC sample loop. The gases of interest are preferentially extracted with the Liqui-Cel and thus a natural pre-concentration effect is obtained. Daily method calibration is achieved in the field with a five-point calibration curve that is created by analyzing gas standard-spiked water stored in 5 L gas-impermeable bags. Our system has been shown to substantially pre-concentrate the dissolved gases of interest and produce a highly linear response of peak areas to dissolved gas concentration. The system retains the high accuracy, precision, and wide range of measurable concentrations of the headspace equilibration method while simultaneously increasing the sensitivity due to the pre-concentration step. The time and labor involved in the headspace equilibration method is eliminated and replaced with the

  19. Dissolved Concentrations of PAHs and PCBs Are Often Over-predicted Using Sediment Concentrations and Literature Koc Values

    EPA Science Inventory

    There is an increasing amount of chemical and biological evidence that using sediment concentrations and commonly applied Koc values frequently overpredicts interstitial water concentrations of HOCs, and thereby overestimates uptake and/or effects of those chemicals on exposed or...

  20. Trace metal concentrations in tropical mangrove sediments, NE Brazil.

    PubMed

    Miola, Brígida; Morais, Jáder Onofre de; Pinheiro, Lidriana de Souza

    2016-01-15

    Sediment cores were taken from the mangroves of the Coreaú River estuary off the northeast coast of Brazil. They were analyzed for grain size, CaCO3, organic matter, and trace metal (Cd, Pb, Zn, Cu, Al, and Fe) contents. Mud texture was the predominant texture. Levels of trace metals in surface sediments indicated strong influence of anthropogenic processes, and diagenetic processes controlled the trace metal enrichment of core sediments of this estuary. The positive relationships between trace metals and Al and Fe indicate that Cu, Zn, Pb, and Cd concentrations are associated mainly with Al and Fe oxy-hydroxides and have natural sources.

  1. Dilution mixing estimates of trace metal concentrations of suspended sediments

    SciTech Connect

    Marcus, W.A. )

    1989-02-01

    Dilution mixing equations, at first glance, appear to provide an easy and useful approach for estimating pollutant loads in sediments of unmonitored stream channels. Results from Left Hand Creek, Colorado, however, indicate that only under proper circumstances can dilution mixing models be used to estimate suspended metal concentrations in unmonitored channels with any accuracy. The utility of this technique is severely limited by errors at monitored sites in measuring metal concentrations within sediments and sediment discharge. Specifically, three general constraints must be met before making dilution mixing estimates of unmonitored concentrations: (1) estimated sediment discharges in an unmonitored tributary should be at least 30 percent of that in the main channel below the confluence; (2) there must be a significant difference between the estimated or monitored metal load in the channel below the confluence and the metal loads of the upstream channels; and (3) travel times between the monitoring sites must be incorporated within the calculations.

  2. Behavior of dissolved and total phosphorus concentration and stream discharge: The form of hysteresis during storm events

    NASA Astrophysics Data System (ADS)

    Pradhanang, S. M.; Samal, N. R.; Pierson, D. C.; Schneiderman, E. M.; Zion, M. S.

    2013-12-01

    The forms, rotational patterns and trends of hysteretic loops of dissolved and total phosphorus were investigated in the watershed of a New York City drinking water reservoir. We evaluated two biogeochemical parameters summarizing the changes in solute concentrations and the overall dynamics of each hysteretic loop and seven hydrological parameters that characterize the hydrograph formation of particular storm events. The objectives of this study are: (1) to examine whether the characteristics of solute hysteretic loops monitored during the summer, winter and spring seasons followed a consistent and recurring pattern, (2) to identify hydrological parameters which could potentially influence features of dissolved and total phosphorus hysteresis. Relationships between hysteresis features and hydrological parameters at the watershed outlet were explored using multivariate redundancy analysis (RDA).

  3. Determination of isotopic composition of dissolved copper in seawater by multi-collector inductively coupled plasma mass spectrometry after pre-concentration using an ethylenediaminetriacetic acid chelating resin.

    PubMed

    Takano, Shotaro; Tanimizu, Masaharu; Hirata, Takafumi; Sohrin, Yoshiki

    2013-06-19

    Copper is an essential trace metal that shows a vertical recycled-scavenged profile in the ocean. To help elucidate the biogeochemical cycling of Cu in the present and past oceans, it is important to determine the distribution of Cu isotopes in seawater. However, precise isotopic analysis of Cu has been impaired by the low concentrations of Cu as well as co-existing elements that interfere with measurements by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The objective of this study is to develop a simple Cu pre-concentration method using Nobias-chelate PA1 resin (Hitachi High Technologies). This extraction followed by anion exchange, allows precise analysis of the Cu isotopic composition in seawater. Using this method, Cu was quantitatively concentrated from seawater and >99.9999% of the alkali and alkaline earth metals were removed. The technique has a low procedural blank of 0.70 ng for Cu for a 2L sample and the precision of the Cu isotopic analysis was ±0.07‰ (±2SD, n=6). We applied this method to seawater reference materials (i.e., CASS-5 and NASS-6) and seawater samples obtained from the northwestern Pacific Ocean. The range of dissolved δ(65)Cu was 0.40-0.68‰.

  4. The Inflammatory Phenotype in Failed Metal-On-Metal Hip Arthroplasty Correlates with Blood Metal Concentrations

    PubMed Central

    Paukkeri, Erja-Leena; Korhonen, Riku; Hämäläinen, Mari; Pesu, Marko; Eskelinen, Antti; Moilanen, Teemu; Moilanen, Eeva

    2016-01-01

    Introduction Hip arthroplasty is the standard treatment of a painful hip destruction. The use of modern metal-on-metal (MOM) bearing surfaces gained popularity in total hip arthroplasties during the last decade. Recently, worrisome failures due to adverse reaction to metal debris (ARMD), including pseudotumor response, have been widely reported. However, the pathogenesis of this reaction remains poorly understood. The aim of the present study was to investigate the ARMD response by flow cytometry approach. Methods Sixteen patients with a failed Articular Surface Replacement (ASR) hip prosthesis were included in the study. Samples of pseudotumor tissues collected during revision surgery were degraded by enzyme digestion and cells were typed by flow cytometry. Whole blood chromium and cobalt concentrations were analyzed with mass spectrometry before revision surgery. Results Flow cytometry analysis showed that the peri-implant pseudotumor tissue expressed two principal phenotypes, namely macrophage-dominated and T-lymphocyte-dominated response; the average portions being 54% (macrophages) and 25% (T-lymphocytes) in macrophage-dominated inflammation and 20% (macrophages) and 54% (T-lymphocytes) in T-lymphocyte-dominated response. The percentages of B-lymphocytes and granulocytes were lower in both phenotypes. Interestingly, the levels of blood chromium and cobalt were significantly higher in patients with macrophage-dominated response. Conclusions The results suggest that the adverse tissue reactions induced by MOM wear particles contain heterogeneous pathogeneses and that the metal levels are an important factor in the determination of the inflammatory phenotype. The present results support the hypothesis that higher metal levels cause cytotoxicity and tissue injury and macrophages are recruited to clear the necrotic debris. On the other hand, the adverse response developed in association with lower metal levels is T-lymphocyte-dominated and is likely to reflect

  5. Comparison of changes in metal toxicity following exposure of water with high dissolved organic carbon content to solar, UV-B and UV-A radiation.

    PubMed

    Winch, Susan; Lean, David

    2005-01-01

    This study examines the effects of natural solar radiation on the metal-binding capacity of dissolved organic matter (DOM). Newington Bog water (35.5 mg L(-1) dissolved organic carbon [DOC]) was irradiated for 20 days under UV-B lamps in the laboratory and under natural solar radiation. In the presence of irradiated DOM, IC(50) (contaminant concentration required to reduce algal growth by 50%) was significantly decreased with UV-B treatment for four metals: Pb, 64%; Cu, 63%; Ni, 35% and Cd, 40%. Solar radiation also significantly decreased IC(50) of Pb (58%) and Cu (49%), DOC concentration (11%), DOM fluorescence (DOMFL, 33%) and DOC-specific UV absorbance. Further experiments on Raisin River water (20.7 mg DOC L(-1)) exposed to 20 days of artificial UV-A and UV-B radiation produced significant decreases in IC(50) for Cu (48%) with UV-A and for Pb (43%) with UV-B. DOC concentration was decreased 20% by UV-B and 24% by UV-A. DOMFL decreased 51.5% in the first 5 days of UV-A exposure, an effect that was not observed with the UV-B treatment. The UV-A treatment decreased UV absorbance more at longer wavelengths and over a broader wavelength band than did the UV-B treatment. Change in toxicity with UV irradiation was inconsistent among the metals tested in this study, indicating that some organic metal-binding ligands were more quickly removed or altered than others. The DOM remaining after irradiation appears to be qualitatively different from the unirradiated DOM. The much greater irradiance of UV-A makes its contribution to the removal and/or alteration of DOM at least as important as the influence of higher energy UV-B.

  6. A combined process of activated carbon adsorption, ion exchange resin treatment and membrane concentration for recovery of dissolved organics in pre-hydrolysis liquor of the kraft-based dissolving pulp production process.

    PubMed

    Shen, Jing; Kaur, Ishneet; Baktash, Mir Mojtaba; He, Zhibin; Ni, Yonghao

    2013-01-01

    To recover dissolved organics in pre-hydrolysis liquor (PHL) of the kraft-based dissolving pulp production process, a new combined process concept of sequential steps of activated carbon adsorption, ion exchange resin treatment, and membrane concentration, was proposed. The removal of lignin in the PHL was achieved in the activated carbon adsorption step, which also facilitates the subsequent operations, such as the membrane filtration and ion exchange resin treatment. The ion exchange resin treatment resulted in the removal/concentration of acetic acid, which opens the door for acetic acid recovery. The membrane filtration is to recover/concentrate the dissolved sugars. The combined process resulted in the production of PHL-based concentrate with relatively high concentration of hemicellulosic sugars, i.e., 22.13%.

  7. Sources, transformations, and hydrological processes that control stream nitrate and dissolved organic matter concentrations during snowmelt in an upland forest

    USGS Publications Warehouse

    Sebestyen, S.D.; Boyer, E.W.; Shanley, J.B.; Kendall, C.; Doctor, D.H.; Aiken, G.R.; Ohte, N.

    2008-01-01

    We explored catchment processes that control stream nutrient concentrations at an upland forest in northeastern Vermont, USA, where inputs of nitrogen via atmospheric deposition are among the highest in the nation and affect ecosystem functioning. We traced sources of water, nitrate, and dissolved organic matter (DOM) using stream water samples collected at high frequency during spring snowmelt. Hydrochemistry, isotopic tracers, and end-member mixing analyses suggested the timing, sources, and source areas from which water and nutrients entered the stream. Although stream-dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) both originated from leaching of soluble organic matter, flushing responses between these two DOM components varied because of dynamic shifts of hydrological flow paths and sources that supply the highest concentrations of DOC and DON. High concentrations of stream water nitrate originated from atmospheric sources as well as nitrified sources from catchment soils. We detected nitrification in surficial soils during late snowmelt which affected the nitrate supply that was available to be transported to streams. However, isotopic tracers showed that the majority of nitrate in upslope surficial soil waters after the onset of snowmelt originated from atmospheric sources. A fraction of the atmospheric nitrogen was directly delivered to the stream, and this finding highlights the importance of quick flow pathways during snowmelt events. These findings indicate that interactions among sources, transformations, and hydrologic transport processes must be deciphered to understand why concentrations vary over time and over space as well as to elucidate the direct effects of human activities on nutrient dynamics in upland forest streams. Copyright 2008 by the American Geophysical Union.

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  9. Influent concentrations and removal performances of metals through municipal wastewater treatment processes.

    PubMed

    Choubert, J M; Pomiès, M; Ruel, S Martin; Coquery, M

    2011-01-01

    This extensive study aimed at quantifying the concentrations and removal efficiency of 23 metals and metalloids in domestic wastewater passing through full-scale plants. Nine facilities were equipped with secondary biological treatment and three facilities were equipped with a tertiary treatment stage. The metals investigated were Li, B, Al, Ti, V, Cr, Fe, Ni, Co, Cu, Zn, As, Se, Rb, Mo, Ag, Cd, Sn, Sb, Ba, TI, Pb and U. Particulate and dissolved metals were measured using 24 h composite samples at each treatment stage. In influents, total concentrations of Cd, Sb, Co, Se, U, Ag, V were below a few microg/L, whereas at the other extremity Zn, B, Fe, Ti, Al were in the range of 0.1 to > 1 mg/L. It was demonstrated that secondary treatment stage (activated sludge, biodisc and membrane bioreactor) were efficient to remove most metals (removal rate > 70%), with the exception of B, Li, Rb, Mo, Co, As, Sb and V due to their low adsorption capacities. With the tested tertiary stages (polishing pond, rapid chemical settler, ozonation), a removal efficiency was obtained for Ti, Cr, Cd, Cu, Zn, Sn, Pb, Fe, Ag and Al, whereas a little removal (< 30%) was obtained for other metals. PMID:21902037

  10. Dissolved metals and associated constituents in abandoned coal-mine discharges, Pennsylvania, USA. Part 1: Constituent quantities and correlations

    USGS Publications Warehouse

    Cravotta, C.A.

    2008-01-01

    Complete hydrochemical data are rarely reported for coal-mine discharges (CMD). This report summarizes major and trace-element concentrations and loadings for CMD at 140 abandoned mines in the Anthracite and Bituminous Coalfields of Pennsylvania. Clean-sampling and low-level analytical methods were used in 1999 to collect data that could be useful to determine potential environmental effects, remediation strategies, and quantities of valuable constituents. A subset of 10 sites was resampled in 2003 to analyze both the CMD and associated ochreous precipitates; the hydrochemical data were similar in 2003 and 1999. In 1999, the flow at the 140 CMD sites ranged from 0.028 to 2210 L s-1, with a median of 18.4 L s-1. The pH ranged from 2.7 to 7.3; concentrations (range in mg/L) of dissolved (0.45-??m pore-size filter) SO4 (34-2000), Fe (0.046-512), Mn (0.019-74), and Al (0.007-108) varied widely. Predominant metalloid elements were Si (2.7-31.3 mg L-1), B ( C > P = N = Se) were not elevated in the CMD samples compared to average river water or seawater. Compared to seawater, the CMD samples also were poor in halogens (Cl > Br > I > F), alkalies (Na > K > Li > Rb > Cs), most alkaline earths (Ca > Mg > Sr), and most metalloids but were enriched by two to four orders of magnitude with Fe, Al, Mn, Co, Be, Sc, Y and the lanthanide rare-earth elements, and one order of magnitude with Ni and Zn. The ochre samples collected at a subset of 10 sites in 2003 were dominantly goethite with minor ferrihydrite or lepidocrocite. None of the samples for this subset contained schwertmannite or was Al rich, but most contained minor aluminosilicate detritus. Compared to concentrations in global average shale, the ochres were rich in Fe, Ag, As and Au, but were poor in most other metals and rare earths. The ochres were not enriched compared to commercial ore deposits mined for Au or other valuable metals. Although similar to commercial Fe ores in composition, the ochres are dispersed and

  11. Distribution of polycyclic aromatic hydrocarbons in southern Chesapeake Bay surface water: Evaluation of three methods for determining freely dissolved water concentrations

    SciTech Connect

    Gustafson, K.E.; Dickhut, R.M.

    1997-03-01

    Gas sparging, semipermeable-membrane devices (SPMDs), and filtration with sorption of dissolved polycyclic aromatic hydrocarbons (PAHs) to XAD-2 resin were evaluated for determining the concentrations of freely dissolved PAHs in estuarine waters of southern Chesapeake Bay at sites ranging from rural to urban and highly industrialized. Gas sparging had significant sampling artifacts due to particle scavenging by rising bubbles, and SPMDs were kinetically limited for four-ring and larger PAHs relative to short-term temporal changes in water concentrations. Filtration with sorption of the dissolved contaminant fraction to XAD-2 resin was found to be the most accurate and feasible method for determining concentrations of freely dissolved PAHs in estuarine water. Concentrations and distribution coefficients of dissolved and particulate PAHs were measured using the filtration/XAD-2 method. Concentrations of PAHs in surface waters of southern Chesapeake Bay were higher than those reported for the northern bay; concentrations in the Elizabeth River were elevated relative to all other sites. A gradient for particulate PAHs was observed from urban to remote sites. No seasonal trends were observed in dissolved or particle-bound PAH fractions at any site. Distributions of dissolved and particulate PAHs in surface waters of the Chesapeake Bay are near equilibrium at all locations and during all seasons.

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

    PubMed

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

    2014-12-01

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

  13. Modelling the migration opportunities of diadromous fish species along a gradient of dissolved oxygen concentration in a European tidal watershed

    NASA Astrophysics Data System (ADS)

    Maes, J.; Stevens, M.; Breine, J.

    2007-10-01

    The relationship between poor water quality and migration opportunities for fish remains poorly documented, although it is an essential research step in implementing EU water legislation. In this paper, we model the environmental constraints that control the movements of anadromous and catadromous fish populations that migrate through the tidal watershed of River Scheldt, a heavily impacted river basin in Western Europe. Local populations of sturgeon, sea lamprey, sea trout, Atlantic salmon, houting and allis shad were essentially extirpated around 1900. For remaining populations (flounder, three-spined stickleback, twaite shad, thinlip mullet, European eel and European smelt), a data driven logistic model was parameterized. The presence or absence of fish species in samples taken between 1995 and 2004 was modelled as a function of temperature, dissolved oxygen concentration, river flow and season. Probabilities to catch individuals from all diadromous species but three-spined stickleback increased as a function of the interaction between temperature and dissolved oxygen. The hypoxic zone situated in the freshwater tidal part of the estuary was an effective barrier for upstream migrating anadromous spawners since it blocked the entrance to historical spawning sites upstream. Similarly, habitat availability for catadromous fish was greatly reduced and restricted to lower brackish water parts of the estuary. The model was applied to infer preliminary dissolved oxygen criteria for diadromous fish, to make qualitative predictions about future changes in fish distribution given anticipated changes in water quality and to suggest necessary measures with respect to watershed management.

  14. INTERACTION OF METALS AND ORGAINIC CARBON COLLOIDS IN ANOXIC INTERSTITIAL WATERS OF MARINE SEDIMENTS

    EPA Science Inventory

    Marine colloids are an important component of natural water geochemistry critical to the cycling, speciation and bioavailability of metals in marine sediments. In sediment, metals exist in three phases: particulate, colloidal and dissolved. Dissolved metal concentrations have bee...

  15. Effects of anomalous high temperatures on carbon dioxide, methane, dissolved organic carbon and trace element concentrations in thaw lakes in Western Siberia in 2012

    NASA Astrophysics Data System (ADS)

    Pokrovsky, O. S.; Shirokova, L. S.; Kirpotin, S. N.; Kulizhsky, S. P.; Vorobiev, S. N.

    2013-04-01

    During the anomalous hot summer in 2012, surface air temperatures in Western Siberia were 5 to 10 °C higher than those observed during the previous period of > 30 yr. This unusual climate phenomenon provided an opportunity to examine the effects of short-term natural heating of water in thermokarst ponds and lakes in discontinuous permafrost zones and compare these observations to previous field results obtained when the temperature was normal during the summer of 2010 in the same region. Thermokarst bodies of water shrank significantly, water levels dropped approximately 50 cm in large lakes and small (< 10-100 m2) ponds, and shallow soil depressions disappeared. Based on samples from ~ 40 bodies of water collected previously and in 2012, first-order features of changes in chemical composition in response to increased water temperatures (from 14.1 ± 2.2 to 23.8 ± 2.3 °C in 2010 and 2012, respectively) were established. In these thermokarst bodies of water that covered a full range of surface areas, the average conductivity and pH were almost unchanged, whereas dissolved organic carbon (DOC), Cl- and SO42- concentrations were higher by a factor of ~ 2 during summer 2012 compared to periods with normal temperatures. Similarly, most divalent metals and insoluble trivalent and tetravalent elements were more concentrated by a factor of 1.7-2.4 in the summer of 2012 than normal periods. The average concentrations of dissolved CO2 and CH4 during the hot summer of 2012 increased by factors of 1.4 and 4.9, respectively. For most of the trace elements bound to colloids, the degree of colloidal binding decreased by a factor of 1.44 ± 0.33 (for an average of 40 elements) during the hot summer of 2012 compared to normal periods. Increases in CO2 and CH4 concentrations with the decreasing size of the body of water were well-pronounced during the hot summer of 2012. The concentrations of CO2 and CH4 significantly increased by factors of 5 and 150, respectively, in small (

  16. Dissolved greenhouse gas concentrations as proxies for emissions: First results from a survey of 43 Alpine lakes

    NASA Astrophysics Data System (ADS)

    Pighini, Sylvie; Wohlfahrt, Georg; Miglietta, Franco

    2015-04-01

    Up to very recently, freshwater ecosystems were neglected in assessments of the global carbon cycle and considered merely as passive 'pipes' which transport carbon from the land to the oceans. This view has been challenged by an increasing number of studies showing that freshwater ecosystems may negate a substantial fraction of the carbon sink through carbon dioxide (CO2) and in particular methane (CH4) emissions and thus rather should be viewed as 'reactors' which process a large fraction of the terrigenous carbon. Most of our knowledge on freshwater CO2 and CH4 emissions to date derives from studies in tropical and boreal regions, while temperate freshwater ecosystems are understudied. This study is focused on lakes from the Alpine area and their content in dissolved greenhouse gases, CH4 and CO2. We mostly aim to assess the content of dissolved methane and carbon dioxide from the Alpine lakes in order to understand whether Alpine lakes could be potential CH4 and CO2 emitters. We also would like to relate concentrations to lake characteristics and potential biotic and abiotic driving forces. A diverse set of 43 lakes, from Trentino, South Tirol (Italy) and North Tirol (Austria), was selected resulting in a gradient with respect to elevation (from 240 to 1700 m a.s.l.) and latitude (from 45.52° to 47.38°). Complementary to dissolved CH4 and CO2 surface water samples, dissolved oxygen and temperature were measured. Only water surface samples were considered. Analyses were done with a gas chromatographer equipped with a flame ionization detector (FID) for CH4 and a thermal conductivity detector (TCD) for CO2 determination. The first results show that all the sampled lakes were super-saturated in dissolved methane and carbon dioxide concentrations, at least partly to a degree that in the literature has been shown to result in substantial emissions to the atmosphere. To estimate emissions, CO2 and CH4 fluxes will be quantified using the eddy covariance and floating

  17. Tolerance of Oncomelania hupensis quadrasi to varying concentrations of dissolved oxygen and organic pollution.

    PubMed

    Garcia, R G

    1972-01-01

    Ecological investigations were made of habitats containing natural populations of the snail Oncomelania hupensis quadrasi and of habitats free from the snail in the island of Leyte, Philippines. This species of snail is a vector of Schistosoma japonicum in the Philippines. Snail-infested habitats had dissolved oxygen levels of 3.8-9.85 ppm but snail-free habitats had levels of only 0.08-3.6 ppm. Snail-infested habitats were less polluted by organic matter than habitats that were snail-free. Larger numbers of chlorophyll-bearing algae were present in both the water and the soil of snail-infested habitats. Other factors, including temperature, pH, hydrogen carbonate alkalinity, and relative humidity, were also investigated.

  18. How do changes in dissolved oxygen concentration influence microbially-controlled phosphorus cycling in stream biofilms?

    NASA Astrophysics Data System (ADS)

    Saia, S. M.; Locke, N. A.; Regan, J. M.; Carrick, H. J.; Buda, A. R.; Walter, M. T.

    2014-12-01

    Advances in molecular microbiology techniques (e.g. epi-fluorescent microscopy and PCR) are making it easier to study the influence of specific microorganisms on nutrient transport. Polyphosphate accumulating organisms (PAOs) are commonly used in wastewater treatment plants to remove excess phosphorus (P) from effluent water. PAOs have also been identified in natural settings but their ecological function is not well known. In this study, we tested the hypothesis that PAOs in natural environments would release and accumulate P during anaerobic and aerobic conditions, respectively. We placed stream biofilms in sealed, covered tubs and subjected them to alternating air (aerobic conditions) and N2 gas (anaerobic condition) bubbling for 12 hours each. Four treatments investigated the influence of changing dissolved oxygen on micribially-controlled P cycling: (1) biofilms bubbled continuously with air, (2) biofilms bubbled alternatively with air and N2, (3) biocide treated biofilms bubbled continuously with air, and (4) biocide treated biofilms bubbled alternatively with air and N2. Treatments 3 and 4 serve as abiotic controls to treatments 1 and 2. We analyzed samples every 12 hours for soluble reactive P (SRP), temperature, dissolved oxygen, and pH. We also used fluorescent microscopy (i.e. DAPI staining) and PCR to verify the presence of PAOs in the stream biofilms. SRP results over the course of the experiment support our hypothesis that anaerobic and aerobic stream conditions may impact PAO mediated P release and uptake, respectively in natural environments. The results of these experiments draw attention to the importance of microbiological controls on P mobility in freshwater ecosystems.

  19. Liver metal concentrations in Greater Sage-grouse (Centrocercus urophasianus).

    PubMed

    Dailey, Rebecca N; Raisbeck, Merl F; Siemion, Roger S; Cornish, Todd E

    2008-04-01

    Greater Sage-grouse (Centrocercus urophasianus) are a species of concern due to shrinking populations associated with habitat fragmentation and loss. Baseline health parameters for this species are limited or lacking, especially with regard to tissue metal concentrations. To obtain a range of tissue metal concentrations, livers were collected from 71 Greater Sage-grouse from Wyoming and Montana. Mean +/- SE metal concentrations (mg/kg wet weight) in liver were determined for vanadium (V) (0.12 +/- 0.01), chromium (Cr) (0.50 +/- 0.02), manganese (Mn) (2.68 +/- 0.11), iron (Fe) (1,019 +/- 103), nickel (Ni) (0.40 +/- 0.04), cobalt (Co) (0.08 +/- 0.02), copper (Cu) (6.43 +/- 0.40), mercury (Hg) (0.30 +/- 0.09), selenium (Se) (1.45 +/- 0.64), zinc (Zn) (59.2 +/- 4.70), molybdenum (Mo) (0.93 +/- 0.07), cadmium (Cd) (1.44 +/- 0.14), barium (Ba) (0.20 +/- 0.03), and lead (Pb) (0.17 +/- 0.03). In addition to providing baseline data, metal concentrations were compared between sex, age (juvenile/adult), and West Nile virus (WNv) groups (positive/negative). Adult birds had higher concentrations of Ni and Cd compared to juveniles. In addition, Zn and Cu concentrations were significantly elevated in WNv-positive birds.

  20. Heavy metal concentrations in edible barnacles exposed to natural contamination.

    PubMed

    Dionísio, M; Costa, A; Rodrigues, A

    2013-04-01

    The giant barnacle Megabalanus azoricus is a popular seafood in the Azores. It is mainly caught in coastal environments and sold for domestic human consumption. This species is a filter feeder and can be used as a biomonitor of trace metal bioavailabilities. To investigate consumption safety, the concentrations of 10 trace metals - As, Cd, Cr, Cu, Mn, Pb, Rb, Se, Sr and Zn - were evaluated in 3 body tissues of M. azoricus from 3 sites on 2 islands. There were no significant differences between the metal loads of the barnacles from the different sites. However, the concentrations of the total trace metal loads revealed significant differences among the tissues (cirrus, muscles and ovaries). The concentrations of some metals in the body were not within the safety levels for consumers, based on the allowable standard levels for crustaceans issued by the European Union and of legislations in several countries. Alarming levels of As and Cd were found. Considering the absence of heavy industry in the region, a non-anthropogenic volcanic source was assumed to be the reason for the observed metal levels. Barnacles, in particular M. azoricus, seem to be useful as bioindicators in this peculiar environment.

  1. Experimental whole-lake increase of dissolved organic carbon concentration produces unexpected increase in crustacean zooplankton density

    USGS Publications Warehouse

    Kelly, Patrick T.; Craig, Nicola; Solomon, Christopher T.; Weidel, Brian C.; Zwart, Jacob A.; Jones, Stuart E.

    2016-01-01

    The observed pattern of lake browning, or increased terrestrial dissolved organic carbon (DOC) concentration, across the northern hemisphere has amplified the importance of understanding how consumer productivity varies with DOC concentration. Results from comparative studies suggest these increased DOC concentrations may reduce crustacean zooplankton productivity due to reductions in resource quality and volume of suitable habitat. Although these spatial comparisons provide an expectation for the response of zooplankton productivity as DOC concentration increases, we still have an incomplete understanding of how zooplankton respond to temporal increases in DOC concentration within a single system. As such, we used a whole-lake manipulation, in which DOC concentration was increased from 8 to 11 mg L−1 in one basin of a manipulated lake, to test the hypothesis that crustacean zooplankton production should subsequently decrease. In contrast to the spatially derived expectation of sharp DOC-mediated decline, we observed a small increase in zooplankton densities in response to our experimental increase in DOC concentration of the treatment basin. This was due to significant increases in gross primary production and resource quality (lower seston carbon-to-phosphorus ratio; C:P). These results demonstrate that temporal changes in lake characteristics due to increased DOC may impact zooplankton in ways that differ from those observed in spatial surveys. We also identified significant interannual variability across our study region, which highlights potential difficulty in detecting temporal responses of organism abundances to gradual environmental change (e.g., browning).

  2. Experimental whole-lake increase of dissolved organic carbon concentration produces unexpected increase in crustacean zooplankton density.

    PubMed

    Kelly, Patrick T; Craig, Nicola; Solomon, Christopher T; Weidel, Brian C; Zwart, Jacob A; Jones, Stuart E

    2016-08-01

    The observed pattern of lake browning, or increased terrestrial dissolved organic carbon (DOC) concentration, across the northern hemisphere has amplified the importance of understanding how consumer productivity varies with DOC concentration. Results from comparative studies suggest these increased DOC concentrations may reduce crustacean zooplankton productivity due to reductions in resource quality and volume of suitable habitat. Although these spatial comparisons provide an expectation for the response of zooplankton productivity as DOC concentration increases, we still have an incomplete understanding of how zooplankton respond to temporal increases in DOC concentration within a single system. As such, we used a whole-lake manipulation, in which DOC concentration was increased from 8 to 11 mg L(-1) in one basin of a manipulated lake, to test the hypothesis that crustacean zooplankton production should subsequently decrease. In contrast to the spatially derived expectation of sharp DOC-mediated decline, we observed a small increase in zooplankton densities in response to our experimental increase in DOC concentration of the treatment basin. This was due to significant increases in gross primary production and resource quality (lower seston carbon-to-phosphorus ratio; C:P). These results demonstrate that temporal changes in lake characteristics due to increased DOC may impact zooplankton in ways that differ from those observed in spatial surveys. We also identified significant interannual variability across our study region, which highlights potential difficulty in detecting temporal responses of organism abundances to gradual environmental change (e.g., browning).

  3. Application of Passive Sampling for Measuring Dissolved Concentrations of Organic Contaminants in the Water Column at Three U.S. EPA Marine Superfund Sites

    EPA Science Inventory

    At contaminated sediment sites, including U.S. EPA Superfund sites, it is critical to measure water column concentrations of freely dissolved contaminants to understand the complete exposure of aquatic organisms to hydrophobic organic contaminants (HOCs). Historically acquiring ...

  4. Application of Passive Sampling for Measuring Dissolved Concentrations of Organic Contaminants in the Water Column at Three U.S. EPA Marine Superfund Sites.

    EPA Science Inventory

    At contaminated sediment sites, including U.S. EPA Superfund sites, it is critical to measure water column concentrations of freely dissolved contaminants to understand the complete exposure of aquatic organisms to hydrophobic organic contaminants (HOCs). Historically, acquiring...

  5. Prediction of dissolved actinide concentrations in concentrated electrolyte solutions: a conceptual model and model results for the Waste Isolation Pilot Plant (WIPP)

    SciTech Connect

    Novak, C.F.; Moore, R.C.; Bynum, R.V.

    1996-10-25

    The conceptual model for WIPP dissolved concentrations is a description of the complex natural and artificial chemical conditions expected to influence dissolved actinide concentrations in the repository. By a set of physical and chemical assumptions regarding chemical kinetics, sorption substrates, and waste-brine interactions, the system was simplified to be amenable to mathematical description. The analysis indicated that an equilibrium thermodynamic model for describing actinide solubilities in brines would be tractable and scientifically supportable. This paper summarizes the conceptualization and modeling approach and the computational results as used in the WIPP application for certification of compliance with relevant regulations for nuclear waste repositories. The WIPP site contains complex natural brines ranging from sea water to 10x more concentrated than sea water. Data bases for predicting solubility of Am(III) (as well as Pu(III) and Nd(III)), Th(IV), and Np(V) in these brines under potential repository conditions have been developed, focusing on chemical interactions with Na, K, Mg, Cl, SO{sub 4}, and CO{sub 3} ions, and the organic acid anions acetate, citrate, EDTA, and oxalate. The laboratory and modeling effort augmented the Harvie et al. parameterization of the Pitzer activity coefficient model so that it could be applied to the actinides and oxidation states important to the WIPP system.

  6. Heavy metal concentrations in tissues of Virginia river otters

    SciTech Connect

    Anderson-Bledsoe, K.L.; Scanlon, P.F.

    1983-04-01

    Concentrations of lead, cadmium, zinc and copper in liver, kidney and bone samples of otter harvested during the 1979-1980 and 1980-1981 trapping seasons were determined by atomic absorption spectrophotometry. Correlations between metal concentrations and age for all three tissues were nonsignificant. Correlations among the concentrations of the four elements in liver and kidney samples were also nonsignificant for otter samples in both years. The highest correlation coefficient (0.47) was found between zinc and copper concentrations in liver samples from otters trapped during the 1979-1980 trapping season. (JMT)

  7. Corrosion investigations on zircaloy-4 and titanium dissolver materials for MOX fuel dissolution in concentrated nitric acid containing fluoride ions

    NASA Astrophysics Data System (ADS)

    Jayaraj, J.; Krishnaveni, P.; Krishna, D. Nanda Gopala; Mallika, C.; Mudali, U. Kamachi

    2016-05-01

    Aqueous reprocessing of plutonium-rich mixed oxide fuels require fluoride as a dissolution catalyst in boiling nitric acid for an effective dissolution of the spent fuel. High corrosion rates were obtained for the candidate dissolver materials zircaloy-4 (Zr-4) and commercial pure titanium (CP-Ti grade 2) in boiling 11.5 M HNO3 + 0.05 M NaF. Complexing the fluoride ions either with Al(NO3)3 or ZrO(NO3)2 aided in decreasing the corrosion rates of Zr-4 and CP-Ti. From the obtained corrosion rates it is concluded that CP-Ti is a better dissolver material than Zr-4 for extended service life in boiling 11.5 M HNO3 + 0.05 M NaF, when complexed with 0.15 M ZrO(NO3)2. XPS analysis confirmed the presence of TiO2 and absence of fluoride on the surface of CP-Ti samples, indicating that effective complexation had occurred in solution leading to passivation of the metal and imparting high corrosion resistance.

  8. Scenarios of metal concentrations in the Arcediano Dam (State of Jalisco, Mexico).

    PubMed

    Hansen, Anne M; Gonzalez-Marquez, Luis C

    2010-01-01

    The city of Guadalajara, Jalisco, Mexico has 4.1 million inhabitants and a serious deficit in water supply. Once constructed, the Arcediano Dam will catch waters from the Verde and Santiago rivers, and after treatment will provide water to the city. The present study was undertaken to formulate scenarios and estimate risks of polluting the water that will be collected in the dam from the release of contaminants accumulated in sediments. Desorption of metals from sediments was estimated through sampling of water and sediments, chemical analyses of the environmental samples, and numerical modeling of the water-sediment interactions. Water quality generally increased as the river flowed downstream from the El Salto sampling station to the site where the Arcediano Dam will be constructed. Aluminum exceeded the Mexican Criterion for Drinking Water Supply (MCDWS), at all sampling stations, whereas iron and manganese surpassed the criteria at some stations. Trace metals were below their respective criteria. For sediment samples in the river, chrome, copper and zinc exceeded the Canadian Interim Sediment Quality Guidelines (ISQG), whereas manganese and nickel exceeded the probable effect level (PEL). Other metals were below these limits. With exception of the El Salto sampling station, metals were mostly enriched in iron-containing sediments, followed by aluminum-containing clays and, to a lesser extent, by manganese oxides. Therefore, the interaction of metals with iron oxides was considered as the controlling adsorption mechanism. Simulations to estimate risks of water contamination by desorption of metals from sediments indicate that manganese and nickel may reach concentrations higher than the CDWS. In some cases, dissolved concentrations of lead and chrome may be higher than the respective CDWS, especially under conditions of high accumulation of sediments in the dam. Arsenic, copper and mercury concentrations did not exceed the CDWS under the simulated conditions.

  9. Scenarios of metal concentrations in the Arcediano Dam (State of Jalisco, Mexico).

    PubMed

    Hansen, Anne M; Gonzalez-Marquez, Luis C

    2010-01-01

    The city of Guadalajara, Jalisco, Mexico has 4.1 million inhabitants and a serious deficit in water supply. Once constructed, the Arcediano Dam will catch waters from the Verde and Santiago rivers, and after treatment will provide water to the city. The present study was undertaken to formulate scenarios and estimate risks of polluting the water that will be collected in the dam from the release of contaminants accumulated in sediments. Desorption of metals from sediments was estimated through sampling of water and sediments, chemical analyses of the environmental samples, and numerical modeling of the water-sediment interactions. Water quality generally increased as the river flowed downstream from the El Salto sampling station to the site where the Arcediano Dam will be constructed. Aluminum exceeded the Mexican Criterion for Drinking Water Supply (MCDWS), at all sampling stations, whereas iron and manganese surpassed the criteria at some stations. Trace metals were below their respective criteria. For sediment samples in the river, chrome, copper and zinc exceeded the Canadian Interim Sediment Quality Guidelines (ISQG), whereas manganese and nickel exceeded the probable effect level (PEL). Other metals were below these limits. With exception of the El Salto sampling station, metals were mostly enriched in iron-containing sediments, followed by aluminum-containing clays and, to a lesser extent, by manganese oxides. Therefore, the interaction of metals with iron oxides was considered as the controlling adsorption mechanism. Simulations to estimate risks of water contamination by desorption of metals from sediments indicate that manganese and nickel may reach concentrations higher than the CDWS. In some cases, dissolved concentrations of lead and chrome may be higher than the respective CDWS, especially under conditions of high accumulation of sediments in the dam. Arsenic, copper and mercury concentrations did not exceed the CDWS under the simulated conditions

  10. Predicting dissolved oxygen concentration using kernel regression modeling approaches with nonlinear hydro-chemical data.

    PubMed

    Singh, Kunwar P; Gupta, Shikha; Rai, Premanjali

    2014-05-01

    Kernel function-based regression models were constructed and applied to a nonlinear hydro-chemical dataset pertaining to surface water for predicting the dissolved oxygen levels. Initial features were selected using nonlinear approach. Nonlinearity in the data was tested using BDS statistics, which revealed the data with nonlinear structure. Kernel ridge regression, kernel principal component regression, kernel partial least squares regression, and support vector regression models were developed using the Gaussian kernel function and their generalization and predictive abilities were compared in terms of several statistical parameters. Model parameters were optimized using the cross-validation procedure. The proposed kernel regression methods successfully captured the nonlinear features of the original data by transforming it to a high dimensional feature space using the kernel function. Performance of all the kernel-based modeling methods used here were comparable both in terms of predictive and generalization abilities. Values of the performance criteria parameters suggested for the adequacy of the constructed models to fit the nonlinear data and their good predictive capabilities. PMID:24338099

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

    USGS Publications Warehouse

    Collin Roesler,; Culbertson, Charles W.

    2016-01-01

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

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

    USGS Publications Warehouse

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

    2014-01-01

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

  13. Spatial and Seasonal Variation of Dissolved Organic Carbon (DOC) Concentrations in Irish Streams: Importance of Soil and Topography Characteristics

    NASA Astrophysics Data System (ADS)

    Liu, Wen; Xu, Xianli; McGoff, Nicola M.; Eaton, James M.; Leahy, Paul; Foley, Nelius; Kiely, Gerard

    2014-05-01

    Dissolved organic carbon (DOC) concentrations have increased in many sites in Europe and North America in recent decades. High DOC concentrations can damage the structure and functions of aquatic ecosystems by influencing water chemistry. This study investigated the spatial and seasonal variation of DOC concentrations in Irish streams across 55 sites at seven time occasions over 1 year (2006/2007). The DOC concentrations ranged from 0.9 to 25.9 mg/L with a mean value of 6.8 and a median value of 5.7 mg/L and varied significantly over the course of the year. The DOC concentrations from late winter (February: 5.2 ± 3.0 mg/L across 55 sites) and early spring (April: 4.5 ± 3.5 mg/L) had significantly lower DOC concentrations than autumn (October: mean 8.3 ± 5.6 mg/L) and early winter (December: 8.3 ± 5.1 mg/L). The DOC production sources (e.g., litterfall) or the accumulation of DOC over dry periods might be the driving factor of seasonal change in Irish stream DOC concentrations. Analysis of data using stepwise multiple linear regression techniques identified the topographic index (TI, an indication of saturation-excess runoff potential) and soil conditions (organic carbon content and soil drainage characteristics) as key factors in controlling DOC spatial variation in different seasons. The TI and soil carbon content (e.g., soil organic carbon; peat occurrence) are positively related to DOC concentrations, while well-drained soils are negatively related to DOC concentrations. The knowledge of spatial and seasonal variation of DOC concentrations in streams and their drivers are essential for optimum riverine water resources management.

  14. Spatial and Seasonal Variation of dissolved organic carbon (DOC) concentrations in Irish streams: importance of soil and topography characteristics.

    PubMed

    Liu, Wen; Xu, Xianli; McGoff, Nicola M; Eaton, James M; Leahy, Paul; Foley, Nelius; Kiely, Gerard

    2014-05-01

    Dissolved organic carbon (DOC) concentrations have increased in many sites in Europe and North America in recent decades. High DOC concentrations can damage the structure and functions of aquatic ecosystems by influencing water chemistry. This study investigated the spatial and seasonal variation of DOC concentrations in Irish streams across 55 sites at seven time occasions over 1 year (2006/2007). The DOC concentrations ranged from 0.9 to 25.9 mg/L with a mean value of 6.8 and a median value of 5.7 mg/L and varied significantly over the course of the year. The DOC concentrations from late winter (February: 5.2 ± 3.0 mg/L across 55 sites) and early spring (April: 4.5 ± 3.5 mg/L) had significantly lower DOC concentrations than autumn (October: mean 8.3 ± 5.6 mg/L) and early winter (December: 8.3 ± 5.1 mg/L). The DOC production sources (e.g., litterfall) or the accumulation of DOC over dry periods might be the driving factor of seasonal change in Irish stream DOC concentrations. Analysis of data using stepwise multiple linear regression techniques identified the topographic index (TI, an indication of saturation-excess runoff potential) and soil conditions (organic carbon content and soil drainage characteristics) as key factors in controlling DOC spatial variation in different seasons. The TI and soil carbon content (e.g., soil organic carbon; peat occurrence) are positively related to DOC concentrations, while well-drained soils are negatively related to DOC concentrations. The knowledge of spatial and seasonal variation of DOC concentrations in streams and their drivers are essential for optimum riverine water resources management.

  15. Statistical evaluation of biogeochemical variables affecting spatiotemporal distributions of multiple free metal ion concentrationsin an urban estuary

    EPA Science Inventory

    Free metal ion concentrations have been recognized as a better indicator of metal bioavailability in aquatic environments than total dissolved metal concentrations. However, our understanding of the determinants of free ion concentrations, especially in a metal mixture, is limite...

  16. Alkaline earth metal cation exchange: effect of mobile counterion and dissolved organic matter.

    PubMed

    Indarawis, Katrina; Boyer, Treavor H

    2012-04-17

    The goal of this research was to provide an improved understanding of the interactions between alkaline earth metals and DOM under conditions that are encountered during drinking water treatment with particular focus on cation exchange. Both magnetically enhanced and nonmagnetic cation exchange resins were converted to Na, Mg, Ca, Sr, and Ba mobile counterion forms as a novel approach to investigate the exchange behavior between the cations and the interactions between the cations and DOM. The results show that cation exchange is a robust process for removal of Ca(2+) and Mg(2+) considering competition with cations on the resin surface and presence of DOM. DOM was actively involved during the cation exchange process through complexation, adsorption, and coprecipitation reactions. In addition to advancing the understanding of ion exchange processes for water treatment, the results of this work are applicable to membrane pretreatment to minimize fouling, treatment of membrane concentrate, and precipitative softening.

  17. Spatial and seasonal characteristics of dissolved heavy metals in the east and west Guangdong coastal waters, South China.

    PubMed

    Zhang, Ling; Shi, Zhen; Zhang, JingPing; Jiang, Zhijian; Wang, Fei; Huang, Xiaoping

    2015-06-15

    Heavy metal concentrations and physicochemical parameters in seawater were measured in Guangdong coastal waters, South China. Results showed that the concentrations and distribution of heavy metals varied spatially and seasonally. Generally, heavy metal concentrations in the east regions were higher than in the west. Concentrations of Pb, Zn, Cd and Cr in wet seasons were generally higher than in dry seasons owing to the seasonal differences of the river discharge, rainfall and seawater intrusion. Principal component (PC) analysis showed that PC1, PC2 and PC3 in the east were correlated to Pb+Cr+Zn+Cd, As+Cd and Cu, respectively, and they were correlated to Pb+Cr, Zn+Cu+Cd and As+Cu, respectively, in the west. That was maybe due to the differences of local heavy metal sources. The anthropogenic activities contributed more to the main sources of heavy metals, and contamination factors indicated that Zn and Pb pollution was serious in study area.

  18. Dissolved organic carbon concentrations and compositions, and trihalomethane formation potentials in waters from agricultural peat soils, Sacramento-San Joaquin Delta, California; implications for drinking-water quality

    USGS Publications Warehouse

    Fujii, Roger; Ranalli, Anthony J.; Aiken, George R.; Bergamaschi, Brian A.

    1998-01-01

    Water exported from the Sacramento-San Joaquin River delta (Delta) is an important drinking-water source for more than 20 million people in California. At times, this water contains elevated concentrations of dissolved organic carbon and bromide, and exceeds the U.S. Environmental Protection Agency's maximum contaminant level for trihalomethanes of 0.100 milligrams per liter if chlorinated for drinking water. About 20 to 50 percent of the trihalomethane precursors to Delta waters originates from drainage water from peat soils on Delta islands. This report elucidates some of the factors and processes controlling and affecting the concentration and quality of dissolved organic carbon released from peat soils and relates the propensity of dissolved organic carbon to form trihalomethanes to its chemical composition.Soil water was sampled from near-surface, oxidized, well-decomposed peat soil (upper soil zone) and deeper, reduced, fibrous peat soil (lower soil zone) from one agricultural field in the west central Delta over 1 year. Concentrations of dissolved organic carbon in the upper soil zone were highly variable, with median concentrations ranging from 46.4 to 83.2 milligrams per liter. Concentrations of dissolved organic carbon in samples from the lower soil zone were much less variable and generally slightly higher than samples from the upper soil zone, with median concentrations ranging from 49.3 to 82.3 milligrams per liter. The dissolved organic carbon from the lower soil zone had significantly higher aromaticity (as measured by specific ultraviolet absorbance) and contained significantly greater amounts of aromatic humic substances (as measured by XAD resin fractionation and carbon-13 nuclear magnetic resonance analysis of XAD isolates) than the dissolved organic carbon from the upper soil zone. These results support the conclusion that more aromatic forms of dissolved organic carbon are produced under anaerobic conditions compared to aerobic conditions

  19. Concentration of some platinum-group metals in coal

    USGS Publications Warehouse

    Finkelman, R.B.; Aruscavage, P. J.

    1981-01-01

    New data on some platinum group metals in coal indicate that the concentration of Pt is generally less than about 5 ppb, that of Pd is generally less than 1 ppb, and that of Rh is generally less than 0.5 ppb. No conclusive evidence was obtained concerning the mode of occurrence of these elements in coal. ?? 1981.

  20. Assessment of potable water quality including organic, inorganic, and trace metal concentrations.

    PubMed

    Nahar, Mst Shamsun; Zhang, Jing

    2012-02-01

    The quality of drinking water (tap, ground, and spring) in Toyama Prefecture, Japan was assessed by studying quality indicators including major ions, total carbon, and trace metal levels. The physicochemical properties of the water tested were different depending on the water source. Major ion concentrations (Ca(2+), K(+), Si(4+), Mg(2+), Na(+), SO(4)(2-), HCO(3)(-), NO(3)(-), and Cl(-)) were determined by ion chromatography, and the results were used to generate Stiff diagrams in order to visually identify different water masses. Major ion concentrations were higher in ground water than in spring and tap water. The relationship between alkaline metals (Na(+) and K(+)), alkaline-earth metals (Ca(2+) and Mg(2+)), and HCO(3)(-) showed little difference between deep and shallow ground water. Toyama ground, spring, and tap water were all the same type of water mass, called Ca-HCO(3). The calculated total dissolved solid values were below 300 mg/L for all water sources and met World Health Organization (WHO) water quality guidelines. Trace levels of As, Cd, Cr, Co, Cu, Fe, Pb, Mn, Mo, Ni, V, Zn, Sr, and Hg were detected in ground, spring, and tap water sources using inductively coupled plasma atomic emission spectrometry, and their levels were below WHO and Japanese water quality standard limits. Volatile organic carbon compounds were quantified by headspace gas chromatography-mass spectrometry, and the measured concentrations met WHO and Japanese water quality guidelines. Total trihalomethanes (THMs) were the major contaminant detected in all natural drinking water sources, but the concentration was highest in tap water (37.27 ± 0.05 μg/L). Notably, THMs concentrations reached up to 1.1 ± 0.05 μg/L in deep ground water. The proposed model gives an accurate description of the organic, inorganic, and trace heavy metal indicators studied here and may be used in natural clean water quality management.

  1. An Analysis of Dissolved Oxygen Concentrations in Tail Waters of Hydroelectric Dams and the Implications for Small-Scale Hydropower Development

    NASA Astrophysics Data System (ADS)

    Cada, Glenn F.; Kumar, K. D.; Solomon, Jean A.; Hildebrand, Stephen G.

    1983-08-01

    One of the environmental issues affecting small-scale hydropower development in the United States is water quality degradation. The extent of this potential problem, as exemplified by low dissolved oxygen concentrations in reservoir tail waters, was analyzed by pairing operating hydroelectric sites with dissolved oxygen measurements from nearby downstream U.S. Geological Survey water quality stations. These data were used to calculate probabilities of noncompliance (PNC's), that is, the probabilities that dissolved oxygen concentrations in the discharge waters of operating hydroelectric dams will drop below 5 mg/l. The continental states were grouped into eight regions based on geographic and climatic similarities. Most regions had higher mean PNC's in summer than in winter, and summer PNC's were greater for large-scale than for small-scale hydropower facilities. Cumulative probability distributions of PNC also indicated that low dissolved oxygen concentrations in the tail waters of operating hydroelectric dams are phenomena largely confined to sites with large-scale facilities.

  2. Use of pore-water composition to reconstruct past dissolved inorganic carbon concentration and alkalinity in Pacific bottom water

    NASA Astrophysics Data System (ADS)

    Sauvage, J. F.; Spivack, A. J.; D'Hondt, S. L.; Integrated Ocean Drilling Program Expedition 329 shipboard scientific party

    2011-12-01

    The carbonate system is a crucial component in controlling the pH of the world's oceans and the distribution of CO2 within the ocean, as well as between the ocean and atmosphere. Consequently, dissolved inorganic carbon (DIC) and alkalinity reconstructions bear lots of promise for improving understanding of the ocean's role in the global carbon cycle and climate. We propose and test a method to quantify in situ concentrations of deep-sea carbonate-system components (DIC, alkalinity, CO32-, Ca2+, and minor component concentrations) in pore fluid of deep-sea sediment cores. These concentrations can in turn be used to reconstruct deep-sea carbonate-system chemistry of the geologic past. Alkalinity, DIC and Ca2+ concentrations measured on research vessels differ from in situ values because temperature and pressure changes during core recovery, storage and extraction induce calcium carbonate precipitation and in this way alter the original composition. To reconstruct in situ values, we developed a method that takes advantage of the mathematically over-determined state of the system if three components are measured, given that CaCO3 is saturated and the dissolved carbonate system is at equilibrium in situ. As a result, based on the measured alkalinity, DIC and Ca2+ concentrations, in situ CO2aq, HCO3-, CO32-, and minor species concentrations are calculated by applying an iteration process. This approach allows us to calculate the amount of CaCO3 precipitated during sediment recovery from the seafloor, and hence in situ carbonate system components. We apply our model to pore-water data from two SPG sites rich in calcium carbonate and drilled by Integrated Ocean Drilling Program Expedition 329 (Sites 1367 and 1368). We compared two sample types for this study, (i) samples squeezed and processed within minutes of recovery (rapidly processed) and (ii) samples processed in the following hours/days, and as consequence prone to some substantial alteration (slowly processed

  3. Benthic invertebrates, periphyton, and bottom material and their trace-metal concentrations in Salmon Creek basin, Clark County, Washington

    USGS Publications Warehouse

    White, Amy C.; McKenzie, Stuart W.

    1979-01-01

    In 1978, data were collected for identification and quantification of benthic invertebrates, periphyton, and bottom material and their trace-metals concentrations from three sites in Salmon Creek basin, Wash. Metal analyses included arsenic, cadmium, chromium, copper, lead, zinc, selenium, and mercury. Physical data collected included water temperature, dissolved oxygen, pH, discharge, and size of cobbles and fine stream-bottom material. Additional chemical analyses included major constituents. Benthic invertebrate identifications were generally taken to the generic level, with a total of 49 taxons identified and quantified. A total of 36 periphyton taxons were quantified and identified, generally at the species level. 

  4. Effects of over-winter green cover on groundwater nitrate and dissolved organic carbon concentrations beneath tillage land.

    PubMed

    Premrov, Alina; Coxon, Catherine E; Hackett, Richard; Kirwan, Laura; Richards, Karl G

    2012-11-01

    Application of over-winter green cover (e.g. cover crops) as a measure for reducing nitrate losses from tillage land has been frequently investigated, especially in the unsaturated zone. Monitoring of groundwater is less common in these studies. Studies on groundwater responses to different land treatments can be challenging because they can be influenced by various conditions, such as recharge, seasonal variations, and aquifer properties, often occurring at different time scales than surface water processes. The aim of this study was to evaluate groundwater nitrate (NO(3)(-)N) and dissolved organic carbon (DOC) concentration responses to different over-winter green covers: mustard, natural regeneration and no cover. A field experiment was designed and run for three years on tillage land underlain by a vulnerable sand and gravel aquifer in the south-east of Ireland. Results showed that over-winter green cover growth on tillage land can be an effective measure to reduce groundwater NO(3)(-)N concentrations. A significant decrease in groundwater NO(3)(-)N concentrations was observed under the mustard cover compared to no cover. All treatments, including no cover, showed a decline in groundwater NO(3)(-)N concentrations over time. A significant increase in groundwater DOC was also observed under the mustard cover. Although the overall groundwater DOC concentrations were low, the increased DOC occurrence in groundwater should be accounted for in carbon balances and could potentially enhance groundwater denitrification in cases where aquifer conditions may favour it.

  5. River bank restoration effects on dissolved organic carbon concentrations in groundwater during floods

    NASA Astrophysics Data System (ADS)

    Derx, J.; Blaschke, A. P.

    2012-04-01

    Estimating the effect of river restoration on groundwater quality is important in the view of nationwide implementations demanded by e.g. the EU Water Framework Directive. DOC transport during river infiltration conditions was examined based on 3D flow and contaminant transport simulations with transient groundwater-surface water interaction. In a scenario setting the effects of river restoration on DOC concentrations, travel time and distance from the river required for DOC reduction in groundwater during river floods were investigated. River restoration was assumed to cause scouring of the riverbank, which a) affects the bank geometry and provides more chance of the river to interact with groundwater and b) reduces bank sediment clogging. A shallow unconfined alluvial aquifer of gravel and sandy gravel media was assumed which was either well connected to the river or was confined by a thin clogging layer at the top of the river bed and bank at natural infiltration conditions. Scenario results showed that riverbank restoration facilitates DOC transport into the aquifer during floods. Even if riverbank permeability remained unchanged, floods caused significantly higher DOC concentrations at a restored than at a channelised riverbank. At the same time, DOC concentration peaks in groundwater arrived earlier and the required distance from the river reducing DOC to background concentrations increased. These effects were explained by changes in bank geometry, and thus a greater ability of the river to interact with groundwater.

  6. Manifestation of cryptic fibroblast tissue factor occurs at detergent concentrations which dissolve the plasma membrane.

    PubMed

    Carson, S D

    1996-04-01

    Cultured fibroblasts treated with increasing concentrations of detergents expressed only encrypted levels of tissue factor activity (measured by fX activation in the presence of fVIIa), characteristic of undamaged cells, until each detergent reached a critical concentration at which the cryptic tissue factor activity was manifested. Beyond the narrow ranges of concentrations over which the detergents stimulated tissue factor activity, the detergents were inhibitory. Studies with Triton X-100 and octyl glucoside revealed that manifestation of tissue factor activity coincided with breakdown of the plasma membrane. The magnitude of the increased tissue factor activity differed among detergents, with octyl glucoside giving the largest response. The tissue factor that was active after Triton X-100 treatment remained mostly associated with the insoluble cell residue, whereas the concentration of octyl glucoside which stimulated activity released tissue factor activity into the supernatant. Radiolabeled antibody against human tissue factor was used to show that a small percentage of the total accessible tissue factor remained in the insoluble fraction after treatment with either non-ionic detergent. Chromatographic analysis of lipids extracted from cells treated with detergents and dansyl chloride showed dansyl-reactivity of phosphatidylserine on intact cells, and solubilization of membrane lipids at sublytic concentrations of detergents. These findings reveal that there is a critical level of detergent-induced membrane damage at which tissue factor activity is maximally expressed, in essentially an all-or-none manner. The results are consistent with a major role for phospholipid asymmetry in regulation of tissue factor specific activity, but require either maintenance of asymmetry during sublytic detergent perturbation of the plasma membrane or additional control mechanisms.

  7. [Characteristics of Dissolved CH₄ and N₂O Concentrations of Weihe River in Xinxiang Section in Spring].

    PubMed

    Hou, Cui-cui; Zhang, Fang; Li, Ying-chen; Wang, Qi-bo; Liu, Sai

    2016-05-15

    Distributions of CH₄ and N₂O concentrations in Weihe River in Xinxiang City were monitored in spring of 2015, and their influencing factors were discussed. The result showed that CH₄ and N₂O were super-saturated in surface water of Weihe River. The variation ranges of two gases' saturations in the surface water of Weihe River were 147.59-2667.85 (CH₄) and 4.06-188.25 (N₂O). In the urban area, significant correlation existed between N₂O and NH₄⁺-N concentrations (P < 0.01), but in the new district, dissolved N₂O concentration showed sharp increase because of the water input from the urban sewage plants, illustrating that the controlling mechanism on N₂O production varied as pollutant characteristics changed. Stepwise regression analysis showed that CH₄ concentrations could be explained by NH₄⁺-N concentrations and water temperature, and CH₄ concentrations in the surface water of Weihe River was significantly correlated with NH₄⁺-N concentrations (R² = 0.70, P < 0.01), suggesting that NH₄⁺-N was the key factor in regulating the production and assumption of CH₄oxidation in Weihe River in spring. Besides, this study showed that when there was less NO₃⁻-N but more NH₄⁺-N in river water, CH₄and N₂O concentrations would be positively correlated, indicating that different nitrogen sources would impact the coupling mechanism of CH₄and N₂O productions.

  8. [Characteristics of Dissolved CH₄ and N₂O Concentrations of Weihe River in Xinxiang Section in Spring].

    PubMed

    Hou, Cui-cui; Zhang, Fang; Li, Ying-chen; Wang, Qi-bo; Liu, Sai

    2016-05-15

    Distributions of CH₄ and N₂O concentrations in Weihe River in Xinxiang City were monitored in spring of 2015, and their influencing factors were discussed. The result showed that CH₄ and N₂O were super-saturated in surface water of Weihe River. The variation ranges of two gases' saturations in the surface water of Weihe River were 147.59-2667.85 (CH₄) and 4.06-188.25 (N₂O). In the urban area, significant correlation existed between N₂O and NH₄⁺-N concentrations (P < 0.01), but in the new district, dissolved N₂O concentration showed sharp increase because of the water input from the urban sewage plants, illustrating that the controlling mechanism on N₂O production varied as pollutant characteristics changed. Stepwise regression analysis showed that CH₄ concentrations could be explained by NH₄⁺-N concentrations and water temperature, and CH₄ concentrations in the surface water of Weihe River was significantly correlated with NH₄⁺-N concentrations (R² = 0.70, P < 0.01), suggesting that NH₄⁺-N was the key factor in regulating the production and assumption of CH₄oxidation in Weihe River in spring. Besides, this study showed that when there was less NO₃⁻-N but more NH₄⁺-N in river water, CH₄and N₂O concentrations would be positively correlated, indicating that different nitrogen sources would impact the coupling mechanism of CH₄and N₂O productions. PMID:27506045

  9. Influence of acid volatile sulfides and metal concentrations on metal partitioning in contaminated sediments

    USGS Publications Warehouse

    Lee, J.-S.; Lee, B.-G.; Luoma, S.N.; Choi, H.J.; Koh, C.-H.; Brown, C.L.

    2000-01-01

    The influence of acid volatile sulfide (AVS) on the partitioning of Cd, Ni, and Zn in porewater (PW) and sediment as reactive metals (SEM, simultaneously extracted metals) was investigated in laboratory microcosms. Two spiking procedures were compared, and the effects of vertical geochemical gradients and infaunal activity were evaluated. Sediments were spiked with a Cd-Ni-Zn mixture (0.06, 3, 7.5 ??mol/g, respectively) containing four levels of AVS (0.5, 7.5, 15, 35 ??mol/g). The results were compared to sediments spiked with four levels of Cd-Ni-Zn mixtures at one AVS concentration (7.5 ??mol/g). A vertical redox gradient was generated in each treatment by an 18-d incubation with an oxidized water column. [AVS] in the surface sediments decreased by 65-95% due to oxidation during incubation; initial [AVS] was maintained at 0.5-7.5 cm depth. PW metal concentrations were correlated with [SEM - AVS] among all data. But PW metal concentrations were variable, causing the distribution coefficient, Kd(pw) (the ratio of [SEM] to PW metal concentrations) to vary by 2-3 orders of magnitude at a given [SEM - AVS]. One reason for the variability was that vertical profiles in PW metal concentrations appeared to be influenced by diffusion as well as [SEM - AVS]. The presence of animals appeared to enhance the diffusion of at least Zn. The generalization that PW metal concentrations are controlled by [SEM - AVS] is subject to some important qualifications if vertical gradients are complicated, metal concentrations vary, or equilibration times differ.The influence of acid volatile sulfide (AVS) on the partitioning of Cd, Ni, and Zn in porewater (PW) and sediment as reactive metals (SEM, simultaneously extracted metals) was investigated in laboratory microcosms. Two spiking procedures were compared, and the effects of vertical geochemical gradients and infaunal activity were evaluated. Sediments were spiked with a Cd-Ni-Zn mixture (0.06, 3, 7.5 ??mol/g, respectively) containing

  10. Concentrations of heavy metals in soil, Zimapan, México

    NASA Astrophysics Data System (ADS)

    Ongley, L. K.; Armienta, A.; Mango, H.

    2003-05-01

    Pb-Zn-Ag mining and ore pocessing have occurred continuously in Zimapán, México since at least 1632 and possibly since 1576 [1, 2]. This has resulted in the development of significant slag and tailings piles. Dissolution of ore and tailings has resulted in arsenic contamination of much of the water in the valley raising the possibility of arsenicosis of the residents [3, 4, 5]. INAA and ICP analysis of more than 175 sediment, soil and tailings samples demonstrate significant metal and arsenic contamination of these unconsolidated materials. As, Cu, Pb, and Zn were among the measured elements. Metal concentrations in soils and sediments were highest within 1000 m of tailings or slag piles. Some of the highest soil metal concentrations were measured in a developing soil on top of a slag pile: As-14 700 mg/kg, Cu 8 638 mg/kg, Pb 41444 mg/kg, and Zn 16 976 mg/kg. Soils more than 4 000 m from the tailings and slag generally had less than 40 mg As/kg with Cu < 30 mg/kg, Pb < 64 mg/kg, and Zn < 200 mg/kg. Some rocks ftum the area also show elevated metal concentrations. For example, the As concentrations in dikes and ores from Zimapàn averaged 1 242 and 30 800 mg/kg respectively. Average shale As concentrations (74 mg/kg) match published data for shales that indicate “normal” As concentrations range from 3-490 mg/kg are found world-wide [6]. Some of the soil contamination is natural, the result of the geologic processes responsible for the Pb-Zn ores. However, particularly near the tailings and slag piles, the soils are also contaminated by anthropogenic means: by dry particulate deposition from smelters, by windblown tailings, and possibly by ore and rock dust from the ore transport trucks.

  11. Variations in concentrations and fluxes of dissolved inorganic nutrients related to catchment scale human interventions in Pamba River, Kerala, India

    NASA Astrophysics Data System (ADS)

    David, S. E.; Jennerjahn, T. C.; Chattopadhyay, S.

    2012-12-01

    River basins are geo-hydrological units. Water flowing out of the basin bears the imprint of natural factors such as geology, soil, vegetation and rainfall along with anthropogenic factors including the type and degree of human intervention within the basin. Pamba, a small mountainous river in the SW coast of India with a population density of ~1,400 persons km-2 was studied for its varying land use and human interventions as the global database are biased towards temperate regions while little is know about the smaller catchments from tropical regions. Land use comprised of dense forest in the highland region together with forest plantation and the human impacted Sabarimala temple- the second largest pilgrim, settlement with mixed tree crop (smt) in the midland and lowland paddy cultivated region. 50-60 million devotees visiting Sabarimala during November to January every year associated with the ritual bathing, discharge of human wastes emanating from the influx of millions of pilgrims due to inadequate number of sanitary latrines and the lack of facilities for sewage collection and treatment caused several ecological variations during pilgrim season. In order to asses the effect of land use and pilgrims in combination with seasonal variations in hydrology we investigated the seasonal and spatial variations in physicochemical and nutrient concentrations. Samples were collected from March 2010 to February 2012 during premonsoon (January-May), SW(June to September) and NE monsoon(October to December), from sites varying in land use. Nutrient budgets (load and yield) were calculated to quantify the inputs from various land use segments. Spatio-temporal variations in the physicochemical and dissolved nutrient concentrations were observed along the course of the river. Upstream forest region had highest dissolved oxygen(DO) and pH together with lowest dissolved inorganic nitrogen(DIN) values indicating almost pristine conditions. DIN in the temple region had the

  12. Basin-scale transport of hydrothermal dissolved metals across the South Pacific Ocean.

    PubMed

    Resing, Joseph A; Sedwick, Peter N; German, Christopher R; Jenkins, William J; Moffett, James W; Sohst, Bettina M; Tagliabue, Alessandro

    2015-07-01

    Hydrothermal venting along mid-ocean ridges exerts an important control on the chemical composition of sea water by serving as a major source or sink for a number of trace elements in the ocean. Of these, iron has received considerable attention because of its role as an essential and often limiting nutrient for primary production in regions of the ocean that are of critical importance for the global carbon cycle. It has been thought that most of the dissolved iron discharged by hydrothermal vents is lost from solution close to ridge-axis sources and is thus of limited importance for ocean biogeochemistry. This long-standing view is challenged by recent studies which suggest that stabilization of hydrothermal dissolved iron may facilitate its long-range oceanic transport. Such transport has been subsequently inferred from spatially limited oceanographic observations. Here we report data from the US GEOTRACES Eastern Pacific Zonal Transect (EPZT) that demonstrate lateral transport of hydrothermal dissolved iron, manganese, and aluminium from the southern East Pacific Rise (SEPR) several thousand kilometres westward across the South Pacific Ocean. Dissolved iron exhibits nearly conservative (that is, no loss from solution during transport and mixing) behaviour in this hydrothermal plume, implying a greater longevity in the deep ocean than previously assumed. Based on our observations, we estimate a global hydrothermal dissolved iron input of three to four gigamoles per year to the ocean interior, which is more than fourfold higher than previous estimates. Complementary simulations with a global-scale ocean biogeochemical model suggest that the observed transport of hydrothermal dissolved iron requires some means of physicochemical stabilization and indicate that hydrothermally derived iron sustains a large fraction of Southern Ocean export production.

  13. Basin-scale transport of hydrothermal dissolved metals across the South Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Resing, Joseph A.; Sedwick, Peter N.; German, Christopher R.; Jenkins, William J.; Moffett, James W.; Sohst, Bettina M.; Tagliabue, Alessandro

    2015-07-01

    Hydrothermal venting along mid-ocean ridges exerts an important control on the chemical composition of sea water by serving as a major source or sink for a number of trace elements in the ocean. Of these, iron has received considerable attention because of its role as an essential and often limiting nutrient for primary production in regions of the ocean that are of critical importance for the global carbon cycle. It has been thought that most of the dissolved iron discharged by hydrothermal vents is lost from solution close to ridge-axis sources and is thus of limited importance for ocean biogeochemistry. This long-standing view is challenged by recent studies which suggest that stabilization of hydrothermal dissolved iron may facilitate its long-range oceanic transport. Such transport has been subsequently inferred from spatially limited oceanographic observations. Here we report data from the US GEOTRACES Eastern Pacific Zonal Transect (EPZT) that demonstrate lateral transport of hydrothermal dissolved iron, manganese, and aluminium from the southern East Pacific Rise (SEPR) several thousand kilometres westward across the South Pacific Ocean. Dissolved iron exhibits nearly conservative (that is, no loss from solution during transport and mixing) behaviour in this hydrothermal plume, implying a greater longevity in the deep ocean than previously assumed. Based on our observations, we estimate a global hydrothermal dissolved iron input of three to four gigamoles per year to the ocean interior, which is more than fourfold higher than previous estimates. Complementary simulations with a global-scale ocean biogeochemical model suggest that the observed transport of hydrothermal dissolved iron requires some means of physicochemical stabilization and indicate that hydrothermally derived iron sustains a large fraction of Southern Ocean export production.

  14. Evaluation of the Chemcatcher and DGT passive samplers for monitoring metals with highly fluctuating water concentrations.

    PubMed

    Allan, Ian J; Knutsson, Jesper; Guigues, Nathalie; Mills, Graham A; Fouillac, Anne-Marie; Greenwood, Richard

    2007-07-01

    ) that associate to a significant degree with suspended solids, colloids or dissolved organic carbon, or form complexes with large organic ligands, optimum agreement was with the filtered or ultrafiltered fractions and with the predicted inorganic and inorganic-fulvic acid associated fractions. While Chemcatcher-based TWA concentration ranges for Cu and Zn were in best agreement with the total filtered fraction, there was lack of agreement for Pb. The combined use of DGT devices with open pore (OP) and restricted pore (RP) gels allowed the labile fraction of metal associated with large organic ligands or DOC to be differentiated and quantified, since this is available to DGT OP but unable to diffuse into the DGT RP. This evaluation of the two sampling devices clearly demonstrated their ability to react reliably to transient peaks in concentration of metal pollutants in water and indicated where future efforts are needed to improve calibration data. Such samplers may prove valuable in responding to the monitoring requirements of the European Union's Water Framework Directive.

  15. PHOTOCHEMICAL ALTERATION OF DISSOLVED ORGANIC MATTER: EFFECTS ON THE CONCENTRATION AND ACIDITIES OF IONIZABLE SITES IN DISSOLVED ORGANIC MATTER IN THE SATILLA RIVER OF GEORGIA, USA

    EPA Science Inventory

    The acid-base properties of humic substances, the major component of dissolved organic matter (DOM), area major control on the alkalinity, or acid neutralizing capacity of freshwater systems. Alkalinity is one of the fundamental parameters measured in aquatic sciences, and is an ...

  16. +2 Valence Metal Concentrations in Lion Creek, Oakland, California

    NASA Astrophysics Data System (ADS)

    Vazquez, P.; Zedd, T.; Chagolla, R.; Dutton-Starbuck, M.; Negrete, A.; Jinham, M.; Lapota, M.

    2012-12-01

    Seven major creeks exist within the City of Oakland, California. These creeks all flow in the southwest direction from forested hills down through densely populated streets where they become susceptible to urban runoff. Lion Creek has been diverted to engineered channels and underground culverts and runs directly under our school (Roots International) before flowing into the San Leandro Bay. One branch of the creek begins near an abandoned sulfur mine. Previous studies have shown that extremely high levels of lead, arsenic and iron exist in this portion of the creek due to acid mine drainage. In this study +2 valence heavy metals concentration data was obtained from samples collected from a segment of the creek located approximately 2.8 miles downstream from the mine. Concentrations in samples collected at three different sites along this segment ranged between 50 ppb and 100 ppb. We hypothesize that these levels are related to the high concentration of +2 valence heavy metals at the mining site. To test this hypothesis, we have obtained samples from various locations along the roughly 3.75 miles of Lion Creek that are used to assess changes in heavy metals concentration levels from the mining site to the San Leandro Bay.

  17. Impacts of Agricultural Practices on Concentrations and Fluxes of Dissolved Organic Carbon

    NASA Astrophysics Data System (ADS)

    Oh, N.; Pellerin, B. A.; Bachand, P. A.; Bergamaschi, B. A.; Horwath, W. R.

    2008-12-01

    Organic matter from the breakdown of plant and animal material is a significant concern for drinking water quality in California due to the potential formation of carcinogenic disinfection byproducts (DBPs) during water treatment with chlorine. Reducing DOC concentration at the source water is a possible management strategy being explored for the reduction of DBP precursors. We examined a variety of land use/land cover, i.e. natural grasslands and intensive agriculture in the Willow Slough Watershed (415 km2) in Yolo County, California to determine the temporal and spatial DOC dynamics. Surface water DOC concentrations ranged from 1.62 to 11.44 mg L-1 at the mouth of the watershed during the first two years, with about two times higher DOC concentrations measured downstream in an intensive agricultural subwatershed dominated by summer flood irrigation. The mean DOC yield was also the highest from the agricultural subwatershed at 0.74 g m-2 over the six months of active irrigation. Results suggest that there is a positive correlation between cropland area and DOC yield. Among many crop species examined, alfalfa showed the strongest positive linear relationship with R2 = 0.91 between the irrigation season DOC yield and percentage crop area of each subwatershed, indicating that agricultural practices such as flood irrigation have a greater impact on DOC loads than other irrigation systems. The results indicate that agricultural practices may deserve further attention for watershed management of DOC and DBP precursors and that flood irrigation practices should be targeted to reduce DOC loading within the main watershed.

  18. Relative control of dissolved organic matter (DOM) composition and concentration for carbon-mineral complexation

    NASA Astrophysics Data System (ADS)

    Pan, W.; Inamdar, S. P.; Sparks, D. L.; Aufdenkampe, A. K.; Yoo, K.

    2012-12-01

    Growing concern about climate change has evoked considerable interest in the soil carbon (C) pool, the second largest C-sink on the earth. C-mineral complexation formed by ligand exchange between DOM and soil is considered as the dominant mechanism for DOM sorption and stabilization in soil. Despite intensive sorption studies, our understanding of how DOM composition influences sorption is still fairly limited. The objectives of the proposed study are: (a) to investigate the relative control of DOM composition and concentration on C-mineral complexation and (b) to determine the DOM composition metrics that are associated with irreversible binding between carbon and mineral surfaces. To address these objectives, we investigated the sorption of DOM isolated and extracted from 12 different watershed sources to goethite (a-FeOOH) with batch sorption and desorption experiments. Fluorescence-EEM and UV-absorbance methods were used to characterize DOM composition through a variety of metrics. DOM composition varied considerably for the 12 DOM solutions. With all DOM solutions adjusted to a DOC concentration of 30mgC/L, humification index (HIX) value ranged from 0.18 to 0.8 and the specific UV absorbance (SUVA) ranged from 1.12 to 3.70. The increase of 2 pH units after sorption indicated ligand exchange was likely the dominant process during sorption. The aromatic and humic-like DOM substances were preferentially sorbed. Preliminary results suggest that carbon mineral complexation (OC/SSA) was influenced by both, the concentration as well as the composition of the DOM. The explanatory power of the regression equations predicting DOM sorption to goethite was increased by the including of DOM composition matrix. The sorption isotherm revealed that DOM composition has a significant influence on the shape of the isotherms.

  19. [Concentration and Source of Dissolved Organic Carbon in Snowpits of the Tibetan Plateau].

    PubMed

    Yan, Fang-ping; Kang, Shi-chang; Chen, Peng-fei; Bai, Jian-kun; Li, Yang; Hu, Zhao-fu; Li, Chao-liu

    2015-08-01

    Snowpit samples of three glaciers (Laohugou NO. 12 Glacier (LHG), Small Dongkemadi Glacier on Mount Tanggula (TGL) and East Ronghuk Glacier on Mount Everest (ZF)) in the Tibetan Plateau were collected. Concentrations of DOC and major ions were analyzed. The results showed that average DOC concentrations of the snowpits of LHG, TGL and ZF were (250.30 +/- 157.10), (216.92 +/- 142.82) and (152.50 +/- 56.11) microg x L(-1), respectively. DOC of TGL and ZF accounted for large parts of total values of DOC and ions. Correspondingly, DOC of LHG accounted for small part (only 5%), because LHG was located at north China and intensively influenced by natural mineral dust, which caused high concentrations of Ca2+ (the highest value could reach 5299.18 microg x L(-1)) and consequently low percentage of DOC of snowpit samples. Correlation and PCA analyses were used to study the sources of DOC. DOC was significantly correlated with Ca2+, Mg2+, K+ and SO4(2-). Additionally, PCA further indicated that the main potential source of DOC was the natural source of mineral dust. Meanwhile, anthropogenic pollutants (e.g., biomass, fossil combustion and agricultural related pollutants) could also not be ignored. Moreover, the carbon depositional fluxes of three snowpits were roughly estimated, and the values of LHG, TGL and ZF snowpits were 189.23, 132.76 and 128.44 mg (m2 x a)(-1), respectively, which played a significant role in the carbon cycle in this region and was also helpful for the study of glaciers fluctuation. PMID:26592009

  20. [Concentration and Source of Dissolved Organic Carbon in Snowpits of the Tibetan Plateau].

    PubMed

    Yan, Fang-ping; Kang, Shi-chang; Chen, Peng-fei; Bai, Jian-kun; Li, Yang; Hu, Zhao-fu; Li, Chao-liu

    2015-08-01

    Snowpit samples of three glaciers (Laohugou NO. 12 Glacier (LHG), Small Dongkemadi Glacier on Mount Tanggula (TGL) and East Ronghuk Glacier on Mount Everest (ZF)) in the Tibetan Plateau were collected. Concentrations of DOC and major ions were analyzed. The results showed that average DOC concentrations of the snowpits of LHG, TGL and ZF were (250.30 +/- 157.10), (216.92 +/- 142.82) and (152.50 +/- 56.11) microg x L(-1), respectively. DOC of TGL and ZF accounted for large parts of total values of DOC and ions. Correspondingly, DOC of LHG accounted for small part (only 5%), because LHG was located at north China and intensively influenced by natural mineral dust, which caused high concentrations of Ca2+ (the highest value could reach 5299.18 microg x L(-1)) and consequently low percentage of DOC of snowpit samples. Correlation and PCA analyses were used to study the sources of DOC. DOC was significantly correlated with Ca2+, Mg2+, K+ and SO4(2-). Additionally, PCA further indicated that the main potential source of DOC was the natural source of mineral dust. Meanwhile, anthropogenic pollutants (e.g., biomass, fossil combustion and agricultural related pollutants) could also not be ignored. Moreover, the carbon depositional fluxes of three snowpits were roughly estimated, and the values of LHG, TGL and ZF snowpits were 189.23, 132.76 and 128.44 mg (m2 x a)(-1), respectively, which played a significant role in the carbon cycle in this region and was also helpful for the study of glaciers fluctuation.

  1. One year of Seaglider dissolved oxygen concentration profiles at the PAP site

    NASA Astrophysics Data System (ADS)

    Binetti, Umberto; Kaiser, Jan; Heywood, Karen; Damerell, Gillian; Rumyantseva, Anna

    2015-04-01

    Oxygen is one of the most important variables measured in oceanography, influenced both by physical and biological factors. During the OSMOSIS project, 7 Seagliders were used in 3 subsequent missions to measure a multidisciplinary suite of parameters at high frequency in the top 1000 m of the water column for one year, from September 2012 to September 2013. The gliders were deployed at the PAP time series station (nominally at 49° N 16.5° W) and surveyed the area following a butterfly-shaped path. Oxygen concentration was measured by Aanderaa optodes and calibrated using ship CTD O2 profiles during 5 deployment and recovery cruises, which were in turn calibrated by Winkler titration of discrete samples. The oxygen-rich mixed layer deepens in fall and winter and gets richer in oxygen when the temperature decreases. The spring bloom did not happen as expected, but instead the presence of a series of small blooms was measured throughout spring and early summer. During the summer the mixed layer become very shallow and oxygen concentrations decreased. A Deep Oxygen Maximum (DOM) developed along with a deep chlorophyll maximum during the summer and was located just below the mixed layer . At this depth, phytoplankton had favourable light and nutrient conditions to grow and produce oxygen, which was not subject to immediate outgassing. The oxygen concentration in the DOM was not constant, but decreased, then increased again until the end of the mission. Intrusions of oxygen rich water are also visible throughout the mission. These are probably due to mesoscale events through the horizontal transport of oxygen and/or nutrients that can enhance productivity, particularly at the edge of the fronts. We calculate net community production (NCP) by analysing the variation in oxygen with time. Two methods have been proposed. The classical oxygen budget method assumes that changes in oxygen are due to the sum of air-sea flux, isopycnal advection, diapycnal mixing and NCP. ERA

  2. Evaluation of capillary electrophoresis for determining the concentration of dissolved silica in geothermal brines.

    PubMed

    Santoyo, E; García, R; Aparicio, A; Verma, Surendra P; Verma, M P

    2005-04-15

    The determination of silica concentrations in geothermal brines is widely recognized as a difficult analytical task due to its complex chemical polymerization kinetics that occurs during sample collection and chemical analysis. Capillary electrophoresis (CE) has been evaluated as a new reliable analytical method to measure silica (as silicates) in geothermal brines. Synthetic and geothermal brine samples were used to evaluate CE methodology. A capillary electrophoresis instrument, Quanta 4000 (Waters-Millipore) coupled with a Waters 820 workstation was used to carry out the experimental work. The separation of silicates was completed in approximately 5.5 min using a conventional fused-silica capillary (75 microm i.d. x 375 microm o.d. x 60 cm total length). A hydrostatic injection (10 cm for 20 s at 25 degrees C) was employed for introducing the samples. The carrier electrolyte consisted of 10 mM sodium chromate, 3 mM tetradecyltrimethyl-ammonium hydroxide (TTAOH), 2 mM sodium carbonate, and 1 mM sodium hydroxide, adjusted to a pH 11.0 +/- 0.1. Silicates were determined using an indirect UV detection at a wavelength of 254 nm with a mercury lamp and with a negative power supply (-15 kV). A good reproducibility in the migration times (%R.S.D. approximately 1.6%) based on six non-consecutive injections of synthetic brine solutions was obtained. A linear response between silica concentration and corrected peak area was observed. Ordinary (OLR) and weighted (WLR) linear regression models were used for calculating silica concentrations in all samples using the corresponding fitted calibration curves. The analytical results of CE were finally compared with the most probable values of synthetic reference standards of silica using the Student's t-test. No significant differences were found between them at P = 0.01. Similarly, the atomic absorption spectrometry (AAS) results were also compared with the most probable concentrations of the same reference standards, finding

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  4. Correlation between the limiting pH of metal ion solubility and total metal concentration

    SciTech Connect

    Apak, R.; Hizal, J.; Ustaer, C.

    1999-03-15

    As an alternative to species distribution diagrams (pM vs pH curves in aqueous solution) drawn for a fixed total metal concentration, this work has developed simple linear models for correlating the limiting pH of metal ion solubility -- in equilibrium with the least soluble amorphous metal hydroxide solid phase -- to the total metal concentration. Thus adsorptive metal removal processes in complex systems can be better designed once the limiting pH of heavy metal solubility (i.e., pH{sup *}) in such a complex environment can be envisaged by simple linear equations. pH{sup *} vs pM{sub t} (M{sub t} = total metal concentration that can exist in aqueous solution in equilibrium with M(OH){sub 2(s)}) linear curves for uranyl-hydroxide, uranyl-carbonate-hydroxide, and mercuric-chloride-hydroxide simple and mixed-ligand systems and cupric-carbonate-hydroxide complexes in equilibrium with mixed hydroxide solid phases may enable the experimental chemist to distinguish true adsorption (e.g., onto hydrous oxide sorbents) from bulk precipitation removal of the metal and to interpret some anomalous metal fixation data -- usually attributed to pure adsorption in the literature -- with precipitation if the pM{sub t} at the studied pH is lower than that tolerated by pH{sup *} vs pM{sub t} curves. This easily predictable pH{sup *} corresponding to a given pM{sub t} may aid the design of desorptive mobilization experiments for certain metals as well as their adsorptive removal with the purpose of simulating metal adsorption and desorption cycles in real complex environments with changing groundwater pH.

  5. Generalized regression neural network-based approach for modelling hourly dissolved oxygen concentration in the Upper Klamath River, Oregon, USA.

    PubMed

    Heddam, Salim

    2014-08-01

    In this study, a comparison between generalized regression neural network (GRNN) and multiple linear regression (MLR) models is given on the effectiveness of modelling dissolved oxygen (DO) concentration in a river. The two models are developed using hourly experimental data collected from the United States Geological Survey (USGS Station No: 421209121463000 [top]) station at the Klamath River at Railroad Bridge at Lake Ewauna. The input variables used for the two models are water, pH, temperature, electrical conductivity, and sensor depth. The performances of the models are evaluated using root mean square errors (RMSE), the mean absolute error (MAE), Willmott's index of agreement (d), and correlation coefficient (CC) statistics. Of the two approaches employed, the best fit was obtained using the GRNN model with the four input variables used.

  6. Metal hydrides for concentrating solar thermal power energy storage

    NASA Astrophysics Data System (ADS)

    Sheppard, D. A.; Paskevicius, M.; Humphries, T. D.; Felderhoff, M.; Capurso, G.; Bellosta von Colbe, J.; Dornheim, M.; Klassen, T.; Ward, P. A.; Teprovich, J. A.; Corgnale, C.; Zidan, R.; Grant, D. M.; Buckley, C. E.

    2016-04-01

    The development of alternative methods for thermal energy storage is important for improving the efficiency and decreasing the cost of concentrating solar thermal power. We focus on the underlying technology that allows metal hydrides to function as thermal energy storage (TES) systems and highlight the current state-of-the-art materials that can operate at temperatures as low as room temperature and as high as 1100 °C. The potential of metal hydrides for thermal storage is explored, while current knowledge gaps about hydride properties, such as hydride thermodynamics, intrinsic kinetics and cyclic stability, are identified. The engineering challenges associated with utilising metal hydrides for high-temperature TES are also addressed.

  7. Comparison of land-based sources with ambient estuarine concentrations of total dissolved nitrogen in Jiaozhou Bay (China)

    NASA Astrophysics Data System (ADS)

    Lu, Dongliang; Yang, Nannan; Liang, Shengkang; Li, Keqiang; Wang, Xiulin

    2016-10-01

    Seasonal, land-sea synchronous surveys were conducted from 2012 to 2013 to characterize the relationship between the composition of land-based total dissolved nitrogen (TDN) and the concentration of dissolved inorganic nitrogen (DIN) in Jiaozhou Bay (JZB). A total of 11 freshwater riverine sampling sites were selected at the river mouths and at waste water outfalls around JZB, while a total 23 Bay stations were established in JZB. Among them, 11 Bay stations were located near the 11 outfalls. Each land-sea sampling was conducted synchronously during a semi-tidal cycle. The contribution of NO3sbnd N, NO2sbnd N, NH4sbnd N, and dissolved organic nitrogen (DON) to TDN in land-based freshwater were similar to those in JZB seawater, while the contribution of the sum of NO3sbnd N and NO2sbnd N to TDN and the contribution of DON to TDN were about 3.2 and 4.1 times higher than the contribution of NH4sbnd N to TDN, respectively. These results showed that inputs of all land-based forms of nitrogen impact the DIN in seawater. Spatial distributions of DIN and DON, showing a gradual decrease from inner bay to the mouth of the bay, were negatively correlated with S in different seasons. In summer and winter, the ratio of DIN to DON in seawater (Rs) gradually decreased from the inner bay to the center of the bay, and the ratio of land-based DIN to DON (RL) was less than RS, indicating net transformation from land-based DON into marine DIN. However, in spring and autumn, the distribution of Rs was opposite to that in summer and winter, and RL was greater than RS, indicating net conversion from land-based DIN into marine DON. Throughout the whole year, net land-based DON was transformed into marine DIN. We provided direct evidence that the variation in DIN concentration in JZB was affected both by land-based TDN inputs and by their hydrodynamic transport and biogeochemical transformation processes.

  8. Direct analysis of δ13C and concentration of dissolved organic carbon (DOC) in environmental samples by TOC-IRMS

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    Dissolved organic carbon (DOC) plays an important role in carbon cycling in terrestrial and aquatic systems. Stable isotope analysis (delta 13C) of DOC could provide valuable insights in its origin, fluxes and environmental fate. Precise and routine analysis of delta 13C and DOC concentration are therefore highly desirable. A promising, new system has been developed for this purpose, linking a high-temperature combustion TOC analyzer trough an interface with a continuous flow isotope ratio mass spectrometer (Elementar group, Hanau, Germany). This TOC-IRMS system enables simultaneous stable isotope (bulk delta 13C) and concentration analysis of DOC, with high oxidation efficiency by high-temperature combustion for complex mixtures as natural DOC. To give delta 13C analysis by TOC-IRMS the necessary impulse for broad-scale application, we present a detailed evaluation of its analytical performance for realistic and challenging conditions inclusive low DOC concentrations and environmental samples. High precision (standard deviation, SD predominantly < 0.15 permil) and accuracy (R2 = 0.9997, i.e. comparison TOC-IRMS and conventional EA-IRMS) were achieved by TOC-IRMS for a broad diversity of DOC solutions. This precision is comparable or even slightly better than that typically reported for EA-IRMS systems, and improves previous techniques for δ13C analysis of DOC. Simultaneously, very good precision was obtained for DOC concentration measurements. Assessment of natural abundance and slightly 13C enriched DOC, a wide range of concentrations (0.2-150 mgC/L) and injection volumes (0.05-3 ml), demonstrated good analytical performance with negligible memory effects, no concentration/volume effects and a wide linearity. Low DOC concentrations (< 2 mgC/L), were correctly analyzed without any pre-concentration. Moreover, TOC-IRMS was successfully applied to analyze DOC from diverse terrestrial, freshwater and marine environments (SD < 0.23 permil). In summary, the TOC

  9. Research of Influence Modification of Natural Concentrate on Quality Metal

    NASA Astrophysics Data System (ADS)

    Fedoseev, S. N.; Gizatulin, R. A.; Korotkova, E. A.

    2016-08-01

    Questions of increase of mechanical, technological and service properties of metal at minimum cost to produce it are relevant for the metallurgical enterprises. Modification of complex steel alloys containing reactive elements is one of the effective ways to improve the quality of steel. At the same time the direct costs for the use of modifiers are 0.2-0.3%, which little effect on the cost of production. The paper presents the results of the application of natural concentrates as a modifier steel. The effects on the metal quality changes due to the impact of the modification concentrates demonstrate the effectiveness of their application. As a result of modification decreased the content of nonmetallic inclusions and grain size. Reduction of impurity modified metal of was the cause more high plastic properties, especially, impact strength at ordinary and low temperatures of tests. Based on the experimental data evaluated hardening mechanisms that lead to a significant improvement of physic-mechanical properties of the metal workpiece after administration modifier.

  10. Effect of pH, ionic strength, dissolved organic carbon, time, and particle size on metals release from mine drainage impacted streambed sediments.

    PubMed

    Butler, Barbara A

    2009-03-01

    Acid-mine drainage (AMD) input to a stream typically results in the stream having a reduced pH, increased concentrations of metals and salts, and decreased biological productivity. Removal and/or treatment of these AMD sources is desired to return the impacted stream(s) to initial conditions, or at least to conditions suitable for restoration of the aquatic ecosystem. Some expected changes in the water chemistry of the stream following removal of AMD input include an increase in pH, a decrease in ionic strength, and an increase in dissolved organic carbon (DOC) concentrations from increased biological activity in the absence of toxic metals concentrations. These changes in water chemistry may cause the existing contaminated bed sediments to become a source of metals to the stream water. Streambed sediments, collected from North Fork Clear Creek (NFCC), Colorado, currently impacted by AMD, were assessed for the effects of pH, ionic strength, DOC concentration, time, and particle size on metals release using a factorial design. The design included two levels for each chemical parameter (ionic strength = 40 and 80% lower than ambient; pH = 6 and 8; and DOC = 1 and 3 mg/l higher than ambient), ten sampling times (from zero to 48 h), and two size fractions of sediments (63 microm < or = x < 2 mm and < 63 microm). Greater concentrations of metals were released from the smaller sized sediments compared with the larger, with the exception of Cu. A mild acid digestion (0.6M HCl) evaluated the amount of each metal that could be removed easily from each of the sediment size fractions. Release of all metals over all time points, treatments, and from both sediment sizes was less than 1% of the extractable concentrations, with the exception of Mn, which ranged from 4 to 7% from the smaller sized sediment. Greater percentages of the 0.6M HCl-extractable concentrations of Cu, Fe, and Zn were released from the larger sized sediment, while this was true for release of Cd and Mn from

  11. Effect of pH, ionic strength, dissolved organic carbon, time, and particle size on metals release from mine drainage impacted streambed sediments.

    PubMed

    Butler, Barbara A

    2009-03-01

    Acid-mine drainage (AMD) input to a stream typically results in the stream having a reduced pH, increased concentrations of metals and salts, and decreased biological productivity. Removal and/or treatment of these AMD sources is desired to return the impacted stream(s) to initial conditions, or at least to conditions suitable for restoration of the aquatic ecosystem. Some expected changes in the water chemistry of the stream following removal of AMD input include an increase in pH, a decrease in ionic strength, and an increase in dissolved organic carbon (DOC) concentrations from increased biological activity in the absence of toxic metals concentrations. These changes in water chemistry may cause the existing contaminated bed sediments to become a source of metals to the stream water. Streambed sediments, collected from North Fork Clear Creek (NFCC), Colorado, currently impacted by AMD, were assessed for the effects of pH, ionic strength, DOC concentration, time, and particle size on metals release using a factorial design. The design included two levels for each chemical parameter (ionic strength = 40 and 80% lower than ambient; pH = 6 and 8; and DOC = 1 and 3 mg/l higher than ambient), ten sampling times (from zero to 48 h), and two size fractions of sediments (63 microm < or = x < 2 mm and < 63 microm). Greater concentrations of metals were released from the smaller sized sediments compared with the larger, with the exception of Cu. A mild acid digestion (0.6M HCl) evaluated the amount of each metal that could be removed easily from each of the sediment size fractions. Release of all metals over all time points, treatments, and from both sediment sizes was less than 1% of the extractable concentrations, with the exception of Mn, which ranged from 4 to 7% from the smaller sized sediment. Greater percentages of the 0.6M HCl-extractable concentrations of Cu, Fe, and Zn were released from the larger sized sediment, while this was true for release of Cd and Mn from

  12. Use of a macroinvertebrate based biotic index to estimate critical metal concentrations for good ecological water quality.

    PubMed

    Van Ael, Evy; De Cooman, Ward; Blust, Ronny; Bervoets, Lieven

    2015-01-01

    Large datasets from total and dissolved metal concentrations in Flemish (Belgium) fresh water systems and the associated macroinvertebrate-based biotic index MMIF (Multimetric Macroinvertebrate Index Flanders) were used to estimate critical metal concentrations for good ecological water quality, as imposed by the European Water Framework Directive (2000). The contribution of different stressors (metals and water characteristics) to the MMIF were studied by constructing generalized linear mixed effect models. Comparison between estimated critical concentrations and the European and Flemish EQS, shows that the EQS for As, Cd, Cu and Zn seem to be sufficient to reach a good ecological quality status as expressed by the invertebrate-based biotic index. In contrast, the EQS for Cr, Hg and Pb are higher than the estimated critical concentrations, which suggests that when environmental concentrations are at the same level as the EQS a good quality status might not be reached. The construction of mixed models that included metal concentrations in their structure did not lead to a significant outcome. However, mixed models showed the primary importance of water characteristics (oxygen level, temperature, ammonium concentration and conductivity) for the MMIF.

  13. Dissolved organic nitrogen (DON) during batch denitrification of low concentrations of nitrate using suspended and attached biomass.

    PubMed

    Brandão, D N; Spanjers, H; van Lier, J B

    2015-01-01

    The occurrence and removal of dissolved organic nitrogen (DON) is an issue of increasing importance for the reclamation of treated wastewater. Effluent DON may act as a precursor of disinfection by-products during wastewater disinfection and may contribute to eutrophication of receiving surface waters. The aim of this study was to understand the effect of the post-denitrification process on final effluent DON (organic nitrogen filtered by 0.45 μm pore size) concentration to further gain knowledge on how to optimize denitrifying filtration, in order to reach the required discharge standards. To evaluate DON variation, denitrification batch experiments were carried out with suspended and attached biomass under different shear conditions. For both conditions, with suspended and attached biomass, DON concentration did not increase or decrease during the denitrification process with addition of an external carbon source. Moreover, the increase of shear rate did not affect the DON concentration. Apparently, there is no direct link between DON evolution and the denitrification process itself. PMID:26606082

  14. Influence of dissolved oxygen concentration on the start-up of the anammox-based process: ELAN®.

    PubMed

    Morales, N; Val del Río, A; Vázquez-Padín, J R; Gutiérrez, R; Fernández-González, R; Icaran, P; Rogalla, F; Campos, J L; Méndez, R; Mosquera-Corral, A

    2015-01-01

    The anammox-based process ELAN® was started-up in two different sequencing batch reactor (SBR) pilot plant reactors treating municipal anaerobic digester supernatant. The main difference in the operation of both reactors was the dissolved oxygen (DO) concentration in the bulk liquid. SBR-1 was started at a DO value of 0.4 mg O2/L whereas SBR-2 was started at DO values of 3.0 mg O2/L. Despite both reactors working at a nitrogen removal rate of around 0.6 g N/(L d), in SBR-1, granules represented only a small fraction of the total biomass and reached a diameter of 1.1 mm after 7 months of operation, while in SBR-2 the biomass was mainly composed of granules with an average diameter of 3.2 mm after the same operational period. Oxygen microelectrode profiling revealed that granules from SBR-2 where only fully penetrated by oxygen with DO concentrations of 8 mg O2/L while granules from SBR-1 were already oxygen penetrated at DO concentrations of 1 mg O2/L. In this way granules from SBR-2 performed better due to the thick layer of ammonia oxidizing bacteria, which accounted for up to 20% of all the microbial populations, which protected the anammox bacteria from non-suitable liquid media conditions. PMID:26247749

  15. Evaluating Function of a Constructed Fen in Alberta's Oil Sands Region Using Dissolved Organic Carbon Concentration and Chemistry

    NASA Astrophysics Data System (ADS)

    Strack, M.; Khadka, B.

    2014-12-01

    Peatlands, mainly fens, account for close to 65% of the landscape in the oil sands region near Fort McMurray, Alberta. Since mine closure plans require landscape reclamation, methods for fen construction are being investigated. As reclamation goals include the return of ecosystem function, criteria for evaluation must be developed. In this study we compare soil concentrations and spectrophometric properties of dissolved organic carbon (DOC) from a constructed fen during its first growing season with that collected from three diverse, undisturbed reference fens in the region. The constructed fen had lower DOC concentration than all the reference fens. Based on E2/E3, E4/E6 and specific UV absorbance of the DOC, the constructed fen had DOC with significantly greater humic content, aromatic nature, and larger molecular size than the reference fens. Results from laboratory DOC production studies indicate that these patterns are likely due to the limited DOC contribution from the newly planted vegetation at the constructed fen, resulting in DOC largely derived from humified peat placed during construction. These preliminary results suggest that DOC concentration and chemistry provide information about the ecological development of the constructed system that could be useful for evaluating reclamation success through time.

  16. Influence of increased dissolved oxygen concentration on the formation of secondary metabolites by manumycin-producing Streptomyces parvulus.

    PubMed

    Kaiser, D; Onken, U; Sattler, I; Zeeck, A

    1994-05-01

    The influence of increased dissolved O2 concentrations (DOC) on cell growth and production of the secondary metabolite manumycin by a strain of Streptomyces parvulus (Tü 64) was investigated in a stirred tank fermentor. DOC is given as the O2 partial pressure (po2) in the gas phase in an equilibrium state with the liquid phase. Growth of S. parvulus was not influenced up to DOC equivalent to po2 = 1260 mbar. At po2 = 2205 mbar the maximum biomass concentration was lowered by 40%. Production of manumycin was markedly influenced by DOC and reached the maximal concentration at po2 = 315 mbar. At increased DOC three new metabolites were observed. Two of them, 64p-A and 64p-B, were identified as carboxamides, which represent the branched side chain of the manumycin molecule and a derivative with a shorter chain length. The third metabolite, 64p-C, was a manumycin derivative containing an aromatic ring system. Feeding of glycerol during the production phase increased the total yield and showed a similar effect of DOC. Since DOC has significant regulation effects on product formation and selectivity, it should be used as a major parameter in development strategies of aerobic microbial processes.

  17. The effect of using different 0.45 μm filter membranes on 'dissolved' element concentrations in natural waters

    USGS Publications Warehouse

    Hall, G.E.M.; Bonham-Carter, G. F.; Horowitz, A.J.; Lum, K.; Lemieux, C.; Quemerais, B.; Garbarino, J.R.

    1996-01-01

    The effect of 4 different 0.45 ??m pore size filter membrane systems on the 'dissolved' concentration of 28 elements in 5 natural water samples of varying matrix is reported. In 3 of the 5 waters, consistently higher concentrations of most elements (minor and trace) are obtained using Nucleopore 47 mm filter and the cellulose acetate/nitrate 47 mm filter than those measured using the 142 mm cellulose nitrate MFS filter or the Gelman capsule 47 mm filter. These distinct and coherent patterns in elemental behaviour disappear for the other 2 samples, an organic-rich peat water of high suspended load and a mineralised sample high in Si and Ca. Thus the nature and degree of filtration artifacts is matrix-dependent. These trends are evident in both data sets produced by 2 independent laboratories using different instrumentation, techniques and calibrating procedures. The average relative standard deviation in elemental concentration across the 4 filter types is in the range 9-21%. The presence of such filtration artifacts must be considered in projects where, for example, seasonal variability of water composition is under examination, data from various sources are being merged or hydrogeochemical surveys are being conducted.

  18. Dissolved organic nitrogen (DON) during batch denitrification of low concentrations of nitrate using suspended and attached biomass.

    PubMed

    Brandão, D N; Spanjers, H; van Lier, J B

    2015-01-01

    The occurrence and removal of dissolved organic nitrogen (DON) is an issue of increasing importance for the reclamation of treated wastewater. Effluent DON may act as a precursor of disinfection by-products during wastewater disinfection and may contribute to eutrophication of receiving surface waters. The aim of this study was to understand the effect of the post-denitrification process on final effluent DON (organic nitrogen filtered by 0.45 μm pore size) concentration to further gain knowledge on how to optimize denitrifying filtration, in order to reach the required discharge standards. To evaluate DON variation, denitrification batch experiments were carried out with suspended and attached biomass under different shear conditions. For both conditions, with suspended and attached biomass, DON concentration did not increase or decrease during the denitrification process with addition of an external carbon source. Moreover, the increase of shear rate did not affect the DON concentration. Apparently, there is no direct link between DON evolution and the denitrification process itself.

  19. Heavy metal concentrations in groundwaters and soils of Thane Region of Maharashtra, India.

    PubMed

    Bhagure, Ganesh Ramdas; Mirgane, S R

    2011-02-01

    Thane district is one of the most industrialized districts in Maharashtra. The heavy industrialization and the increasing urbanization are responsible for the rapidly increasing stress on the water and soil environment of the area. Therefore, an attempt has been made through comprehensive study on the groundwater contamination and soil contamination due to heavy metals in Thane region of Maharashtra. The area undertaken for the study was Thane and its suburbans Kalwa, Divajunction, Dombivali, Kalyan, and Ulhasnagar. Industrialization and urbanization lead to generation of large volumes of wastewater from domestic, commercial, industrial, and other sources, which discharged in to natural water bodies like river and creek in this region. Groundwater samples and soil samples were collected from residential, commercial, agriculture, and industrial areas. Groundwater samples were analyzed for various water quality parameters. The analytical data shows very high concentration of total dissolved solids, total hardness, total alkalinity, chemical oxygen demand, chloride etc. Groundwater and soil samples were analyzed for ten heavy metals by inductively coupled plasma (ICPE-9000) atomic emission spectroscopy. The analytical data reveal that, very high concentration level of arsenic, cadmium, mercury, and nickel throughout the industrial area. The random dumping of hazardous waste in the industrial area could be the main cause of the groundwater and soil contamination spreading by rainwater and wind. In the residential areas the local dumping is expected to be the main source for heavy metals. A comparison of the results of groundwater with WHO guidelines show that most of the groundwater sampling station are heavily contaminated with organic matter and heavy metals. Groundwater samples are heavily contaminated by arsenic, cadmium, mercury, and nickel. Similarly, the results of heavy metals in soil compared with Swedish soil guideline values for polluted soil show that soil

  20. Transfer of metal(loid)s in a small vineyard catchment: contribution of dissolved and particulate fractions in river for contrasted hydrological conditions.

    PubMed

    Rabiet, M; Coquery, M; Carluer, N; Gahou, J; Gouy, V

    2015-12-01

    The use of inorganic pesticides in viticulture leads to the accumulation of metal(loid)s in soils which can be transferred to the hydro-systems (groundwater and surface water) via several processes. This study reports on the occurrence and behavior of metal(loid)s (Li, Al, Cr, Ni, Cu, Zn, As, Sr, and Ba), with a particular focus on Cu, Zn, and As, in a small stream draining a vineyard catchment. Base flow and flood events were monitored in order to assess the spatiotemporal variability of metal(loid) concentrations and to evaluate the contribution of the particulate fraction to the transfer of metal(loid)s according to the hydrological conditions. Results show that very different patterns of metal(loid)s were observed in the Morcille River according to the hydrological conditions. In base flow conditions, Cu and As were mainly transported in dissolved phase, which contributed to more than 70 and 80%, respectively, of the total load during this period. On the contrary, during base flow, Zn was mainly transported as associated to particles (90%). During the two storm events monitored, the particulate fraction was dominant, as its represented around 74-80%, 97%, and 50-70% of the total Cu, Zn, and As load in the river, respectively. Thus, despite a weaker affinity for particles during floods (decrease of particulate content during floods), metal(loid)s were mainly brought as particles, given that high amounts of suspended particulate matter (up to 2031 mg/L) were mobilized. Finally, comprehensive fluxes estimations confirmed that floods were responsible for more than 90% of the total Cu, Zn and 75% for As load transiting in the Morcille River in August within a very short period of time (less than 17%).

  1. Transfer of metal(loid)s in a small vineyard catchment: contribution of dissolved and particulate fractions in river for contrasted hydrological conditions.

    PubMed

    Rabiet, M; Coquery, M; Carluer, N; Gahou, J; Gouy, V

    2015-12-01

    The use of inorganic pesticides in viticulture leads to the accumulation of metal(loid)s in soils which can be transferred to the hydro-systems (groundwater and surface water) via several processes. This study reports on the occurrence and behavior of metal(loid)s (Li, Al, Cr, Ni, Cu, Zn, As, Sr, and Ba), with a particular focus on Cu, Zn, and As, in a small stream draining a vineyard catchment. Base flow and flood events were monitored in order to assess the spatiotemporal variability of metal(loid) concentrations and to evaluate the contribution of the particulate fraction to the transfer of metal(loid)s according to the hydrological conditions. Results show that very different patterns of metal(loid)s were observed in the Morcille River according to the hydrological conditions. In base flow conditions, Cu and As were mainly transported in dissolved phase, which contributed to more than 70 and 80%, respectively, of the total load during this period. On the contrary, during base flow, Zn was mainly transported as associated to particles (90%). During the two storm events monitored, the particulate fraction was dominant, as its represented around 74-80%, 97%, and 50-70% of the total Cu, Zn, and As load in the river, respectively. Thus, despite a weaker affinity for particles during floods (decrease of particulate content during floods), metal(loid)s were mainly brought as particles, given that high amounts of suspended particulate matter (up to 2031 mg/L) were mobilized. Finally, comprehensive fluxes estimations confirmed that floods were responsible for more than 90% of the total Cu, Zn and 75% for As load transiting in the Morcille River in August within a very short period of time (less than 17%). PMID:26253185

  2. Determination of size-dependent metal distribution in dissolved organic matter by SEC-UV/VIS-ICP-MS with special focus on changes in seawater.

    PubMed

    Rathgeb, Anna; Causon, Tim; Krachler, Regina; Hann, Stephan

    2016-04-01

    Iron is an essential micronutrient for all marine organisms, but it is also a growth limiting factor as the iron concentrations in the open ocean are below 1 nmol/L in sea water iron is almost entirely bound to organic ligands of the dissolved organic matter fraction, which are mostly of unknown structure. The input from rivers was traditionally considered as less important due to estuarine sedimentation processes of the mainly colloidal iron particles. However, recent studies have shown that this removal is not complete and riverine input may represent an important iron source in the open ocean. In this context, iron transport by land-derived natural organic matter (NOM), and dissolved organic matter (DOM) have been identified as carrier mechanisms for riverine iron. The aim of this work is to characterize complexes containing iron and other metals in waters simulating estuarine conditions in order to help understand which role iron-DOM compounds play in the open ocean. A method based on size-exclusion chromatography (SEC) with sequential UV/VIS and ICP-MS detection was developed for investigation of DOM size distribution and for assessment of the size-dependent metal distribution in NOM-rich surface water. Furthermore, sample matrix experiments were also performed revealing a dependence of DOM size distribution upon seawater concentration and different compounds present in seawater. Finally, efforts toward determination of DOM size with standardization with typical SEC standards indicate that only relative comparisons are possible with this approach, and that the sample matrix composition strongly influences obtained results. PMID:26814136

  3. Determination of size‐dependent metal distribution in dissolved organic matter by SEC‐UV/VIS‐ICP‐MS with special focus on changes in seawater

    PubMed Central

    Rathgeb, Anna; Causon, Tim; Krachler, Regina

    2016-01-01

    Iron is an essential micronutrient for all marine organisms, but it is also a growth limiting factor as the iron concentrations in the open ocean are below 1 nmol/L in sea water iron is almost entirely bound to organic ligands of the dissolved organic matter fraction, which are mostly of unknown structure. The input from rivers was traditionally considered as less important due to estuarine sedimentation processes of the mainly colloidal iron particles. However, recent studies have shown that this removal is not complete and riverine input may represent an important iron source in the open ocean. In this context, iron transport by land‐derived natural organic matter (NOM), and dissolved organic matter (DOM) have been identified as carrier mechanisms for riverine iron. The aim of this work is to characterize complexes containing iron and other metals in waters simulating estuarine conditions in order to help understand which role iron‐DOM compounds play in the open ocean. A method based on size‐exclusion chromatography (SEC) with sequential UV/VIS and ICP‐MS detection was developed for investigation of DOM size distribution and for assessment of the size‐dependent metal distribution in NOM‐rich surface water. Furthermore, sample matrix experiments were also performed revealing a dependence of DOM size distribution upon seawater concentration and different compounds present in seawater. Finally, efforts toward determination of DOM size with standardization with typical SEC standards indicate that only relative comparisons are possible with this approach, and that the sample matrix composition strongly influences obtained results. PMID:26814136

  4. Determination of size-dependent metal distribution in dissolved organic matter by SEC-UV/VIS-ICP-MS with special focus on changes in seawater.

    PubMed

    Rathgeb, Anna; Causon, Tim; Krachler, Regina; Hann, Stephan

    2016-04-01

    Iron is an essential micronutrient for all marine organisms, but it is also a growth limiting factor as the iron concentrations in the open ocean are below 1 nmol/L in sea water iron is almost entirely bound to organic ligands of the dissolved organic matter fraction, which are mostly of unknown structure. The input from rivers was traditionally considered as less important due to estuarine sedimentation processes of the mainly colloidal iron particles. However, recent studies have shown that this removal is not complete and riverine input may represent an important iron source in the open ocean. In this context, iron transport by land-derived natural organic matter (NOM), and dissolved organic matter (DOM) have been identified as carrier mechanisms for riverine iron. The aim of this work is to characterize complexes containing iron and other metals in waters simulating estuarine conditions in order to help understand which role iron-DOM compounds play in the open ocean. A method based on size-exclusion chromatography (SEC) with sequential UV/VIS and ICP-MS detection was developed for investigation of DOM size distribution and for assessment of the size-dependent metal distribution in NOM-rich surface water. Furthermore, sample matrix experiments were also performed revealing a dependence of DOM size distribution upon seawater concentration and different compounds present in seawater. Finally, efforts toward determination of DOM size with standardization with typical SEC standards indicate that only relative comparisons are possible with this approach, and that the sample matrix composition strongly influences obtained results.

  5. Estimation of Suspended and Dissolved Matter Concentration In Sea Water On Shelves By Satellite Remote Sensing

    NASA Astrophysics Data System (ADS)

    Pelevin, V.; Rostovtseva, V.

    Falling of rivers into the seas or surging in shallow aquatoria cause the violation of the balance between living and dead matter occurring in the open ocean ( Pelevin and Rostovtseva, 2001). That means in littoral arias the one-parameter model of sea waters optical properties developed for the open ocean (Pelevin and Rostovtseva, 1997) is not valid. We suggest to use the three-parameters model of light scattering and absorbing prop- erties of sea water for the most arias on shelves. The three parameters are: the coeffi- cient of light absorption by coloured matter at 500 nm (coloured matter includes both chlorophyll pigments and "yellow substance"), the coefficient of light absorption by suspended matter and the coefficient of light backscattering by suspended matter. For some specific shelf arias with coloured suspended matter we suggest to add the fourth parameter taking into account the spectral dependence of backscattering by suspended matter. The method of such type arias determination is also given. The algorithm of solution of the inverse problem of these parameters estimation using optical remote sensing data obtained from satellites is developed. It consists of two steps: the rough determination of the parameters values by some spectral characteris- tics and then the minimization of real and model spectra discrepancy. The suggested algorithm was used for spectral distribution of upward radiation mea- sured in the Black, Marmora and Baltic Seas. Comparison of the obtained results with some data of direct measurements carried out in these aquatoria proved the validity of the model for these shelf waters and showed the efficiency of the suggested approach. V.N.Pelevin and V.V.Rostovtseva , 1997, Estimation of lightscattering and lightabsorb- ing admixture concentration in open ocean waters of different types.- Atmospheric and Oceanic Optics, 10(9), 989-995. V.N.Pelevin and V.V.Rostovtseva, 2001, Modelling of optic- biological parameters of open ocean waters

  6. Estimation of Concentration and Bonding Environment of Water Dissolved in Common Solvents Using Near Infrared Absorptivity

    PubMed Central

    Dickens, Brian; Dickens, Sabine H.

    1999-01-01

    Integrated near infrared (NIR) absorbance has been used to determine the absorptivity of the υ2 + υ3 combination band of the asymmetric stretch (υ2) and the bending vibration (υ3) for water in several organic solvents. Absorptivity measured in this way is essentially constant across the absorption envelope and is found to be 336 L mol−1 cm−1 with a standard deviation of 4 L mol−1 cm−1 as estimated from a least squares fit of a straight line to data from water concentrations between 0.01 mol/L and 0.06 mol/L. Absorptivity measured from the peak maximum of the υ2 + υ3 combination band of water varies with the type of hydrogen bonding of the water molecule because the shape of the NIR absorption envelope changes with the hydrogen bonding. Because the integrated NIR absorptivity of the υ2 + υ3 combination band of water is essentially constant across the absorption envelope, the NIR absorption envelope reflects the distribution of hydrogen bonding of the water. The shape and location of the absorption envelope appear to be governed mostly by the number of hydrogen bonds from the water molecules to easily polarized atoms. Water that is a donor in hydrogen bonds to atoms which are not easily polarized (such as the oxygen of a typical carbonyl group) absorbs near 5240 cm−1 to 5260 cm−1. Water that donates one hydrogen bond to an easily polarized atom (such as a water molecule oxygen) absorbs near 5130 cm−1 to 5175 cm−1, and water that donates two hydrogen bonds to easily polarized atoms is estimated to absorb near 5000 cm−1 to 5020 cm−1. Water donating two hydrogen bonds to other water molecules may be said to be in a water-like environment. In no case does a small amount of water absorbed in a host material appear to have a water-like environment.

  7. Dissolved Oxygen Concentration Profiles in the Hyporheic Zone Through the Use of a High-Density Fiber Optic Measurement Network

    NASA Astrophysics Data System (ADS)

    Reeder, William Jeffrey; Quick, Annika; Farrell, Tiffany B.; Benner, Shawn G.; Feris, Kevin P.; Tonina, Daniele

    2015-04-01

    The majority of chemical reactions in riverine systems occur within the hyporheic zone (HZ). Hyporheic exchange, flow into and out of the hyporheic zone, represents a primary control over those reactions because the flow rate will determine the residence time and amount of chemical constituents in the HZ. Hyporheic flow can be conceptualized as discreet streamlines that collectively represent a broad distribution of residence times. Within this context, dissolved oxygen (DO) concentration becomes a primary indicator of the redox and biochemical state of the HZ including, for example, the fate of carbon, contaminant behavior, nutrient cycling, stream DO levels and nitrous oxide (N2O) production. River systems have been identified as a significant source of N2O emissions, contributing an estimated 10% of anthropogenically generated N2O. The primary biochemical transformations that lead to N2O production are nitrification (NH4+ to NO3-) and denitrification (NO3- to N2) reactions that are mediated by microbes living in the HZ. Current theory describes a process in which DO enters the stoss side of the HZ and is consumed by respiration and nitrification in the upstream, oxic portion of the streamlines leading to a progressive partitioning of the HZ from oxic to anoxic. This conceptualization, however, has not been well validated in a physical sense, due to inherent difficulties associated with measuring chemical concentrations in the HZ. To test current theory, we measured HZ DO concentrations, in a large-scale flume experiment, almost continuously for five months using a multiplexed optical network and a precision robotic surface probe system. We were able to measure DO at higher spatial and temporal resolution than has been previously demonstrated. These measurements, coupled with detailed numerical modeling of HZ flowlines, allowed us to map HZ DO concentrations spatially and over time. Our findings validate the models that describe the consumption of DO through

  8. [Heavy metal concentrations in mosses from Qiyi Glacier region].

    PubMed

    Ma, Juan-Juan; Li, Zhen

    2014-06-01

    Heavy metal (Cr, Fe, Cu, Zn, As, Cd and Pb) concentrations were measured in 17 moss samples which were collected at Qiyi Glacier Region in July, August and September, 2009 in a preliminary investigation of heavy metal pollution situation in this area. The results indicated that heavy metal concentrations in mosses were relatively high and concentrations of Fe were at the highest level (varied between 15 160.00 and 34 960.00 microg x g(-1)), followed by Zn, Cu, Cr, Pb, As, with average concentrations of 169.56, 134.81, 34.52, 26.16, 9.15 microg x g(-1). Enrichment factor analysis and correlation analysis indicated that Fe and Cr in mosses mainly stemmed from crustal dust, and concentrations of Cu, Pb, Zn and Cd were influenced by human activities; As was moderately enriched which means As in mosses was mainly originated from anthropogenic pollution. According to the Global Data Assimilation System (GDAS) meteorological data from the National Center for Environmental Prediction (NCEP) of 2009 and the simulation of the HYSPLIT v4.9 Model on 3-dimension back trajectories of air mass at Qiyi glacier district, several trajectories reflecting the main characteristics of air flow were obtained based on the classification of cluster analysis on the hundreds of back trajectories. The back trajectories revealed that atmospheric transport characteristics in the study area changed obviously by season. Compared to Spring and Autumn, atmospheric transmission sources were relatively more in Winter and Summer. The main sources of atmospheric pollutants in Qiyi Glacier region were transported from Jiuquan and Jiayuguan regions.

  9. Concentrations and chemical forms of trace metals in coastal seawater on coral reef and their seasonal variation

    NASA Astrophysics Data System (ADS)

    Ganaha, S.; ITOH, A.

    2011-12-01

    Coastal seawater on coral reef near Okinawa island in Japan, which is in oligotrophic condition, has a diverse and unique ecosystem. It is possible that nutritive sals and trace metals, classified into nutrient type, are effectively supplied to marine phytoplankton and zooxanthellae from seawater. However, the concentrations and chemical forms of trace metals in coastal seawater on coral reef have been scarcely reported so far. In the present study, the characteristics of the concentrations and chemical forms of trace metals in such a seawater were investigated with seasonal variation by analyzing the coastal seawater at every month, after an analytical method for a simple chemical speciation including on-site treatment was established. The analytical method using a chelating resin and a disposable syringe was employed for de-salt and preconcentration of trace metals in costal seawater. After that, trace metals in the concentrated solution were measured by ICP-MS. Three types of chemical forms of an ionic, a dissolved, and an acid-soluble were separated without any treatment, by filtering with membrane filter of 0.45 μm, and by filtering after adding nitric acid, respectively. Then, a monitoring investigation of the coastal seawater on coral reef, located at Sesoko island near the northern part of Okinawa island, was carried out once at every month from Sep. 2010 to Aug. 2011. As a result, 10 elements in the dissolved form in each sample could be determined. The average concentrations for all samples from Sep. 2010 to Apr. 2011 were as follows: Mo:10.7 ppb, U:3.2 ppb, V:1.5 ppb, Mn:0.17 ppb, Ni:0.16 ppb, Zn:0.13 ppb, Cu:0.070 ppb, Pb:0.024 ppb, Co:0.0022 ppb, Cd:0.0016ppb. The concentrations for most trace metals were almost close to ones in open surface seawater of the Pacific ocean. For the acid-soluble form, the concentrations of V, Mo, and U were almost same with those of the dissolved form, and ones of Mn, Co, Ni, Cu, and Cd were slightly larger than ones in

  10. Assessment of arsenic and heavy metal concentrations in water and sediments of the Rio Grande at El Paso-Juarez metroplex region.

    PubMed

    Rios-Arana, J V; Walsh, E J; Gardea-Torresdey, J L

    2004-01-01

    The Rio Grande located along the US-Mexico border is affected by anthropogenic activities along its geographical course. Runoff and wind deposition of smelting residues may contribute to the pollution of the Rio Grande in the El Paso-Ciudad Juarez area. Few studies have addressed the presence or impacts of heavy metals or arsenic in this ecosystem. This study reports a survey of heavy metals (Cr, Cu, Cd, Ni, Pb, and Zn) and arsenic (As) in water and sediments of the Rio Grande collected from seven sites in the El Paso-Juarez region. Since water quality influences metal content in water, physical (temperature, flow and conductivity), and chemical (pH, dissolved oxygen, nitrates, alkalinity, and water hardness) parameters were measured at each site. Arsenic and heavy metal levels were determined using Inductively Couple Plasma (ICP) emission spectroscopy following EPA procedures. Zinc and lead were found as both total and dissolved metals in most of the samples, with concentrations of total recoverable metals reaching up to 105 and 70 microg/l, respectively. Most metals were found in sediment samples collected from four of seven sites. The highest Cu concentration (35 mg/l) was found at the American Dam site. Concentrations of metals found through this survey will be used as a reference for future studies in monitoring arsenic, heavy metals, and their impacts in the Rio Grande.

  11. Concentrations and Potential Health Risks of Metals in Lip Products

    PubMed Central

    Liu, Sa; Rojas-Cheatham, Ann

    2013-01-01

    Background: Metal content in lip products has been an issue of concern. Objectives: We measured lead and eight other metals in a convenience sample of 32 lip products used by young Asian women in Oakland, California, and assessed potential health risks related to estimated intakes of these metals. Methods: We analyzed lip products by inductively coupled plasma optical emission spectrometry and used previous estimates of lip product usage rates to determine daily oral intakes. We derived acceptable daily intakes (ADIs) based on information used to determine public health goals for exposure, and compared ADIs with estimated intakes to assess potential risks. Results: Most of the tested lip products contained high concentrations of titanium and aluminum. All examined products had detectable manganese. Lead was detected in 24 products (75%), with an average concentration of 0.36 ± 0.39 ppm, including one sample with 1.32 ppm. When used at the estimated average daily rate, estimated intakes were > 20% of ADIs derived for aluminum, cadmium, chromium, and manganese. In addition, average daily use of 10 products tested would result in chromium intake exceeding our estimated ADI for chromium. For high rates of product use (above the 95th percentile), the percentages of samples with estimated metal intakes exceeding ADIs were 3% for aluminum, 68% for chromium, and 22% for manganese. Estimated intakes of lead were < 20% of ADIs for average and high use. Conclusions: Cosmetics safety should be assessed not only by the presence of hazardous contents, but also by comparing estimated exposures with health-based standards. In addition to lead, metals such as aluminum, cadmium, chromium, and manganese require further investigation. PMID:23674482

  12. Changes in Dissolved Carbon and Nitrogen Concentrations Along a Hill Slope Flow Path in Siberian Arctic Tundra

    NASA Astrophysics Data System (ADS)

    Theberge, J.; Schade, J. D.; Fiske, G. J.; Loranty, M. M.; Zimov, N.

    2014-12-01

    Permafrost soils contain a large pool of carbon that has accumulated for thousands of years, and remains frozen in organic form. As climate warms, permafrost thaw will lead to active cycling of old organic materials, possibly leading to release of carbon to the atmosphere or to export of organic carbon to the oceans. Organic matter breakdown may also release reactive forms of nitrogen, which may significantly impact ecosystem processes. We currently have limited understanding of where in Arctic landscapes breakdown of organic materials will occur, or whether this will influence the strength and direction of feedback loops that may occur in response to changes in C and N cycling. In this work, we studied changes in dissolved forms of C and N in water moving down a hillslope linking upland terrestrial environments to lowland floodplains within the Kolyma River watershed in the East Siberian Arctic tundra in July, 2014. The hill slope consisted of a mosaic of dry and saturated soils, generally with drier soils on the periphery and saturated soils in and around pools or short reaches of flowing surface water. We established transects at regular intervals downslope, installing wells in the center of the flow path and 5 meters laterally north and south. We analyzed pore-water from wells and surface water from pools at each transect for dissolved organic carbon (DOC) and total dissolved nitrogen (TDN). We used patterns in water chemistry to develop a conceptual model for biogeochemical changes as water moved downslope through soils, pools and runs. Pore-water analysis showed significantly higher DOC in lateral wells than in surface water and pore water in the center of the flow path, suggesting possible processing of C as water moves laterally towards the valley bottom. In contrast, DOC increased modestly down the center of the flow path, suggesting either higher hydrologic inputs or production of new DOC downslope. TDN concentration decreased downslope, suggesting

  13. A simple dissolved metals mixing method to produce high-purity MgTiO{sub 3} nanocrystals

    SciTech Connect

    Pratapa, Suminar E-mail: suminar-pratapa@physics.its.ac.id; Baqiya, Malik A. E-mail: suminar-pratapa@physics.its.ac.id; Istianah, E-mail: suminar-pratapa@physics.its.ac.id; Lestari, Rina E-mail: suminar-pratapa@physics.its.ac.id; Angela, Riyan E-mail: suminar-pratapa@physics.its.ac.id

    2014-02-24

    A simple dissolved metals mixing method has been effectively used to produce high-purity MgTiO{sub 3} (MT) nanocrystals. The method involves the mixing of independently dissolved magnesium and titanium metal powders in hydrochloric acid followed by calcination. The phase purity and nanocrystallinity were determined by making use of laboratory x-ray diffraction data, to which Rietveld-based analyses were performed. Results showed that the method yielded only one type magnesium titanate powders, i.e. MgTiO{sub 3}, with no Mg{sub 2}TiO{sub 4} or MgTi{sub 2}O{sub 5} phases. The presence of residual rutile or periclase was controlled by adding excessive Mg up to 5% (mol) in the stoichiometric mixing. The method also resulted in MT nanocrystals with estimated average crystallite size of 76±2 nm after calcination at 600°C and 150±4 nm (at 800°C). A transmission electron micrograph confirmed the formation of the nanocrystallites.

  14. An Isotope Dilution Method for High-frequency Measurements of Dissolved Inorganic Carbon concentration in the Surface Ocean

    NASA Astrophysics Data System (ADS)

    Huang, K.; Bender, M. L.; Wanninkhof, R. H.; Cassar, N.

    2013-12-01

    Dissolved inorganic carbon (DIC) is one of the most important species in the ocean carbon system. An autonomous system using isotope dilution as its core method has been developed to obtain high-frequency measurements of dissolved inorganic carbon (DIC) concentrations in the surface ocean. This system accurately mixes a seawater sample and a 13C-labeled sodium bicarbonate solution (spike). The mixed solution is then acidified and sent through a gas permeable membrane contactor. CO2 derived from DIC in the mixture is extracted by a CO2-free gas stream, and is sent to a cavity ring-down spectrometer to analyze its 13C/12C ratio. [DIC] of the seawater can then be derived from the measured 13C/12C, the known mixing ratio and the [DI13C] of the spike. The method has been tested under a wide [DIC] range (1800-2800 μmol/kg) in the laboratory. It has also been deployed on a cruise that surveyed ocean waters to the south of Florida. At a sampling resolution of 4 minutes (15 samples per hour), the relative standard deviation of DIC determined from the laboratory tests and the field deployment is ×0.07% and ×0.09%, respectively. The accuracy of the method is better than 0.1% except where [DIC] varies faster than 5 μmol/kg per minute. Based on the laboratory and field evaluations, we conclude that this method can provide accurate underway [DIC] measurements at high resolution in most oceanic regions. Schematic illustration of the work flow.

  15. Evaluation of Potential pH-Driven Metal Release Due to Elevated Groundwater CO2 Concentrations

    NASA Astrophysics Data System (ADS)

    Tinnacher, R. M.; Varadharajan, C.; Zheng, L.; Spycher, N.; Birkholzer, J. T.; Trautz, R. C.; Pugh, J. D.; Esposito, R.; Nico, P. S.

    2012-12-01

    The injection of carbon dioxide (CO2) emissions from industrial sources into deep geologic formations is a potential option for the control of CO2 concentrations in the atmosphere. While the risk of CO2 migration from the storage reservoir into potable groundwater is low considering the safeguards of site characterization and permitting, it is important to understand what type of potential impacts could occur and how to identify these impacts. Elevated CO2 concentrations may potentially lead to a decrease in groundwater pH and the subsequent release of metals and ions from natural sediments into the groundwater solution. In this risk scenario, potential metal release processes, such as enhanced mineral dissolution, metal desorption and/or ion exchange reactions, may be driven by changes in groundwater pH, the presence of carbonate ligands in solution or a combination of the two. However, a detailed understanding and a distinction of pH-driven and carbonate-driven metal release reactions are important for the development of site monitoring plans and remediation strategies, required by regulations in the unlikely event of a release. Hence, in this study we characterized metal release from natural sediments into synthetic groundwater solutions at two pH conditions in order to mimic the native groundwater pH (pH ~8.5) and the low pH conditions expected in the event of elevated CO2 concentrations (pH~5). In addition, results are compared between tests performed in the presence and absence of elevated CO2. Metal release was investigated in lab-scale sequential leaching experiments using two sediment types with different organic carbon contents over a time-frame of 25 days. Supernatant solutions were monitored for pH and characterized in terms of metal concentrations (ICP-MS), total inorganic carbon (TIC) and anion composition. Furthermore, experimental results were compared with data from a field study involving the controlled release of groundwater containing dissolved

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

    PubMed

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

    2014-02-01

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

  17. Effects of dissolved organic matter (DOM) at environmentally relevant carbon concentrations on atrazine degradation by Chelatobacter heintzii SalB.

    PubMed

    Cheyns, Karlien; Calcoen, Jasper; Martin-Laurent, Fabrice; Bru, David; Smolders, Erik; Springael, Dirk

    2012-09-01

    The dissolved organic matter (DOM) is the term used for organic components of natural origin present in the soil solution and is probably the most available C-source that primes microbial activity in subsoils. Contrasting effects of organic C components on pesticide degradation have been reported; however, most studies have used model organic compounds with compositions and concentrations which differ substantially from those found in the environment. Degradation of atrazine (AT) by Chelatobacter heintzii SalB was monitored in liquid batch assays in the absence or presence of well-defined model C compounds (glucose, gluconate and citrate) as model DOM (mDOM) or complex, less-defined, environmental DOM solutions (eDOM: isolated humic substances, soil and plant residue extracts) at environmentally relevant concentrations. Glucose significantly increased AT degradation rate by more than a factor of 8 at and above 2.5 mg C L( - 1). Optical density measurements showed that this stimulation is related to microbial growth. Gluconate and citrate had no effects unless at non-relevant concentrations (1,000 mg DOC L( - 1)) at which stimulations (gluconate) or inhibitions (citrate) were found. The effects of eDOM added at 10 mg DOC L( - 1) on AT degradation were generally small. The AT degradation time was reduced by factors 1.4-1.9 in the presence of humic acids and eDOM from soils amended with plant residues; however, no effects were found for fulvic acids or eDOM from a soil leachate solution or extracted from unamended peat or forest soil. In conclusion, DOM supplied as both mDOM and eDOM did not inhibit AT degradation at environmentally relevant concentrations, and stimulation can be found for selected DOM samples and this is partly related to its effect on growth. PMID:22159734

  18. Modeling hourly dissolved oxygen concentration (DO) using two different adaptive neuro-fuzzy inference systems (ANFIS): a comparative study.

    PubMed

    Heddam, Salim

    2014-01-01

    This article presents a comparison of two adaptive neuro-fuzzy inference systems (ANFIS)-based neuro-fuzzy models applied for modeling dissolved oxygen (DO) concentration. The two models are developed using experimental data collected from the bottom (USGS station no: 420615121533601) and top (USGS station no: 420615121533600) stations at Klamath River at site KRS12a nr Rock Quarry, Oregon, USA. The input variables used for the ANFIS models are water pH, temperature, specific conductance, and sensor depth. Two ANFIS-based neuro-fuzzy systems are presented. The two neuro-fuzzy systems are: (1) grid partition-based fuzzy inference system, named ANFIS_GRID, and (2) subtractive-clustering-based fuzzy inference system, named ANFIS_SUB. In both models, 60 % of the data set was randomly assigned to the training set, 20 % to the validation set, and 20 % to the test set. The ANFIS results are compared with multiple linear regression models. The system proposed in this paper shows a novelty approach with regard to the usage of ANFIS models for DO concentration modeling.

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

    PubMed

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

    2013-01-01

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

  20. Modeling hourly dissolved oxygen concentration (DO) using two different adaptive neuro-fuzzy inference systems (ANFIS): a comparative study.

    PubMed

    Heddam, Salim

    2014-01-01

    This article presents a comparison of two adaptive neuro-fuzzy inference systems (ANFIS)-based neuro-fuzzy models applied for modeling dissolved oxygen (DO) concentration. The two models are developed using experimental data collected from the bottom (USGS station no: 420615121533601) and top (USGS station no: 420615121533600) stations at Klamath River at site KRS12a nr Rock Quarry, Oregon, USA. The input variables used for the ANFIS models are water pH, temperature, specific conductance, and sensor depth. Two ANFIS-based neuro-fuzzy systems are presented. The two neuro-fuzzy systems are: (1) grid partition-based fuzzy inference system, named ANFIS_GRID, and (2) subtractive-clustering-based fuzzy inference system, named ANFIS_SUB. In both models, 60 % of the data set was randomly assigned to the training set, 20 % to the validation set, and 20 % to the test set. The ANFIS results are compared with multiple linear regression models. The system proposed in this paper shows a novelty approach with regard to the usage of ANFIS models for DO concentration modeling. PMID:24057665

  1. Binding of mercury(II) to dissolved organic matter: The role of the mercury-to-DOM concentration ratio

    USGS Publications Warehouse

    Haitzer, M.; Aiken, G.R.; Ryan, J.N.

    2002-01-01

    The binding of Hg(II) to dissolved organic matter (DOM; hydrophobic acids isolated from the Florida Everglades by XAD-8 resin) was measured at a wide range of Hg-to-DOM concentration ratios using an equilibrium dialysis ligand exchange method. Conditional distribution coefficients (KDOM???) determined by this method were strongly affected by the Hg/DOM concentration ratio. At Hg/DOM ratios below approximately 1 ??g of Hg/mg of DOM, we observed very strong interactions (KDOM??? = 1023.2??1.0 L kg-1 at pH = 7.0 and I = 0.1), indicative of mercury-thiol bonds. Hg/DOM ratios above approximately 10 ??g of Hg/mg of DOM, as used in most studies that have determined Hg-DOM binding constants, gave much lower KDOM??? values (1010.7??1.0 L kg-1 at pH = 4.9-5.6 and I = 0.1), consistent with Hg binding mainly to oxygen functional groups. These results suggest that the binding of Hg to DOM under natural conditions (very low Hg/DOM ratios) is controlled by a small fraction of DOM molecules containing a reactive thiol functional group. Therefore, Hg/DOM distribution coefficients used for modeling the biogeochemical behavior of Hg in natural systems need to be determined at low Hg/DOM ratios.

  2. Concentration of heavy metals in ash produced from Lithuanian forests

    NASA Astrophysics Data System (ADS)

    Baltrenaite, Edita; Pereira, Paulo; Butkus, Donatas; Úbeda, Xavier

    2010-05-01

    Wood ash contains important amounts of heavy metals. This quantity depends on burned specie, temperature of exposition and heat duration time. Due the high mineralization imposed by the temperatures, ash is used as lime product in agriculture and forests. Also, after a forest fire large quantities of ash are produced and distributed in soil surface. This mineralized organic matter can induce important environmental problems, including soil toxicity provoked by heavy metals leachates from ash. There is an extensive literature about heavy metals contents on ash in different species. However, it recently highlighted that the same species placed in different environments can respond diversely to same temperatures. This question is of major importance because temperature effects on severity can be a function of the plant communities instead of specie characteristics. These findings add a higher degree of complexity in the understanding of temperature effects on ash composition and consequent availability of heavy metals. The aim of this study is to compare the ash chemical heavy metal composition, Cobalt (Co), Chromium (Cr), Cooper (Cu), Silver (Ag), Lead (Pb), Nickel (Ni), Manganese (Mn) and Zinc (Zn), from Pinus sylvestris and Betula pendula, collected in key and representative areas of Lithuanian forests, located in southern, coastal and central part. Samples were collected from alive trees, taken to laboratory and air dried. Subsequently were crushed and submitted to muffle furnace at temperature of 550°C during two hours. The ash samples were digested and in a HNO3-HCl solution and then analysed with AAS. Comparisons between species and sites were performed with a Non-parametric one-way ANOVA‘s on rank transformed data followed by Tukey‘s HSD, significant at a p<0.05. Results showed significant difference between Co and Ag concentrations between Pinus sylvestris and Betula pendula. Also, significantly different concentrations of Pb, Cu, Ni and Mn were

  3. Heavy metal and metallothionein concentrations in Atlantic Canadian seabirds.

    PubMed

    Elliott, J E; Scheuhammer, A M; Leighton, F A; Pearce, P A

    1992-01-01

    Seabird tissues, collected during the 1988 breeding season from colonies on the Atlantic coast of Canada, were analyzed for toxic metals--Cd, Hg and Pb--and 18 other trace elements. Metallothionein (MT) was measured in kidney, and kidneys and livers underwent histopathological examination. Levels of most essential trace elements appear to be closely regulated in seabird tissues; values were in good agreement with those previously reported in the published literature. Liver-Se concentrations in Leach's storm-petrels (Oceanodroma leukorrhea) (77.6 + 7.49 micrograms/g dry weight) were much higher than values normally reported for free-living birds and mammals. Cd levels varied greatly among individuals, but were always higher in kidney than in liver. Highest mean Cd concentrations (183 + 65 micrograms/g dry weight) were in kidneys of the planktivorous Leach's storm-petrels from the Gulf of St. Lawrence. A few individuals of this species had values greater than 300 micrograms/g dry weight. Cd and metallothionein (MT) concentrations were positively correlated in kidneys of Leach's storm-petrels (r = 0.692), Atlantic puffin (Fratercula arctica) (r = 0.845) and herring gull (Larus argentatus) (r = 0.866). Concentrations of total Hg varied greatly among species and individuals, but were consistently higher in liver than in kidney. Highest mean levels (21 + 28 micrograms/g) were in livers of the piscivorous double-crested cormorant (Phalacrocorax auritus) from Saint John Harbour in the Bay of Fundy. Concentrations of Hg and Se were positively correlated (r = 0.736) in livers of Leach's storm-petrel, but not in other species. Pb concentrations were consistently greatest in bone, with mean levels being highest in herring gulls from a colony in the Bay of Fundy (63 + 36 micrograms/g). Histological examination of liver and kidney failed to reveal indications of tissue damage associated with elevated levels of heavy metals. PMID:1554255

  4. Concentric dot-ring metal nanostructures prepared by colloidal lithography

    NASA Astrophysics Data System (ADS)

    Li, G.; Zopf, D.; Schmidl, G.; Fritzsche, W.; Stranik, O.

    2016-10-01

    A large scale production of well-defined metallic nanostructures represents an important step for a real application of plasmonic technology. Here, we report about a development in colloidal lithography for the production of metallic nanostructures of flexible geometry, which can be changed between disks, cones, rings and even concentric dot-ring structures. We show that the simple spherical colloidal mask—applied to produce metallic disks—can be modified by chemical and plasma etching process to produce either ring or dot-ring structure. Furthermore, etching of the colloidal mask leads to cone shaped metallic nanostructures. All these structures are prepared by the same fabrication steps, and different geometries are achieved just by variation of the fabrication parameters. We are able to prepare homogenously dispersed nanostructures (with defined density) with a height between 20 and 50 nm and a lateral dimension between 100 and 200 nm. In the realized nanostructures, the thickness of the ring is 46.2 ± 4.4 nm and the dot structure has an outer diameter of ˜217 nm.

  5. An in situ method to quantitatively determine dissolved free drug concentrations in vitro in the presence of polymer excipients using pulsatile microdialysis (PMD).

    PubMed

    Vejani, Charchil; Bellantone, Robert A

    2015-12-30

    In drug formulations containing polymer excipients, the effects of the polymer on the dissolved free drug concentration and resulting dissolution or release can be important, especially for poorly soluble drugs. In this study, an in vitro method based on pulsatile microdialysis (PMD) was developed to quantitatively determine dissolved free concentrations of drugs in the presence of polymers in aqueous media in situ (e.g., in place within the system being characterized). Formulations were made by dissolving various ratios of the drug griseofulvin and polymer PVP K30 in water and allowing the mix to equilibrate. A PMD probe was immersed in each mixture and the dissolved free drug concentrations were determined in the PMD samples. The experimental procedure and the equations used for data analysis are presented. To assess the consistency of data, a binding model was fit to the data obtained using PMD by calculating the dissolved free drug fraction fD for each drug-polymer ratio in solution, and obtaining the product of the binding stoichiometry and binding constant (νK per mole of polymer) from the slope of a plot of (1-fD)/fD vs. the molar polymer concentration. For comparison, equilibrium binding experiments were also performed at 23C, and the determined value of νK was similar to the value found using PMD. Experiments were performed at three temperatures, and a plot of ln (νK) vs. 1/T was linear and a binding enthalpy of -110.9±4.4J/mol of monomer was calculated from its slope. It was concluded that PMD can be used to determine the dissolved free drug concentrations in situ, which allows characterization of the drug-polymer interaction, even for low drug concentrations. This information may be important in modeling the dissolution or release of drugs from formulations containing polymers.

  6. Hydroclimatic Controls on the Seasonal and Inter-Annual Variability of Dissolved Phosphorus Concentration in a Lowland Agricultural Catchment

    NASA Astrophysics Data System (ADS)

    Dupas, R.; Gascuel-odoux, C.; Grimaldi, C.; Gruau, G.

    2014-12-01

    We investigated soluble reactive phosphorus (SRP) at the outlet of a lowland agricultural catchment (Kervidy-Naizin, France) to identify the hydroclimatic controls on the seasonal and inter-annual variability in concentrations. Six years of stream data have been used, including a regular 6-daily sampling and high-frequency monitoring of 52 floods. Both on an annual basis and during flood events, distinct export dynamics for SRP and particulate phosphorus (PP) revealed that SRP transport mechanism was independent from PP (Dupas et al., submitted). During most flood events, discharge-SRP hystereses were anticlockwise, which suggests that SRP was transferred to the stream via subsurface flow. Groundwater rise in wetland soils was likely the cause of this transfer, through the hydrological connectivity it created between the stream and P-rich soil horizons. SRP concentrations were highest in the beginning of the hydrological year (period A), when the stream started to flow again after the dry summer season and water table fluctuated in the wetland domain. Thus, wetland soils seemed to be a major source of SRP. Concentrations during period A were higher after a long summer period than after a short one, which suggest that a pool of labile P was constituted in soils during the dry summer period. During winter (period B), SRP concentration generally decreased compared to period A, both during floods and interflood. This could be due to depletion of a soil P pool in the wetland domain and/or dilution by deep groundwater with low P concentration from the upland domain. Concentration during period B barely decreased compared to A during wet years, probably due to increased connectivity with soils from the upland domain in wet conditions. During spring (period C), SRP concentration increased during baseflow periods. The possible mechanisms causing the release of SRP could involve reduction of Fe oxide-hydroxides in wetland soils or in-stream processes. At the same time, SRP

  7. Critical concentration for hydrogen bubble formation in metals.

    PubMed

    Sun, Lu; Jin, Shuo; Zhou, Hong-Bo; Zhang, Ying; Zhang, Wenqing; Ueda, Y; Lee, H T; Lu, Guang-Hong

    2014-10-01

    Employing a thermodynamic model with previously calculated first-principle energetics as inputs, we determined the hydrogen (H) concentration at the interstitial and monovacancy as well as its dependence on temperature and pressure in tungsten and molybdenum. Based on this, we predicted the critical H concentration for H bubble formation at different temperatures. The critical concentration, defined as the value when the concentration of H at a certain mH-vacancy complex first became equal to that of H at the interstitial, was 24 ppm/7.3 GPa and 410 ppm/4.7 GPa at 600 K in tungsten and molybdenum in the case of a monovacancy. Beyond the critical H concentration, numerous H atoms accumulated in the monovacancy, leading to the formation and rapid growth of H-vacancy complexes, which was considered the preliminary stage of H bubble formation. We expect that the proposed approach will be generally used to determine the critical H concentration for H bubble formation in metals.

  8. Water Mass Distribution and Particle Flux in the Arctic Ocean From Dissolved 10Be and 9Be Concentrations

    NASA Astrophysics Data System (ADS)

    Frank, M.; Porcelli, D.; Andersson, P.; Halliday, A. N.; Kubik, P. W.; Hattendorf, B.; Guenther, D.

    2002-12-01

    The Arctic Ocean basin is confined by landmasses similar to the Mediterranean. There is only little deep water formed seasonally on the shelves of the Arctic Ocean despite the low temperatures. This is due to a freshwater lid at the surface which originates from the Arctic rivers. The deeper Arctic Ocean water masses can thus only be renewed at comparatively low rates through the only deep connection to the Atlantic Ocean, the Fram Strait. At the same time the biogenic particulate fluxes in the central Arctic Ocean are very low due to perennial sea ice cover and the organic matter produced in the surface waters is remineralised efficiently. Detrital particle fluxes from either eolian or riverine sources are also very low. We will present the first combined dissolved 10Be (cosmogenic) and 9Be (continental sources) depth profiles from water samples of the major deep basins of the Arctic Ocean collected during the Swedish Arctic Ocean 2001 expedition. Be is 5-10 times less particle-reactive than other previously investigated radionuclides such as Th or Pa and should therefore even at the relatively low Arctic Ocean renewal rates serve as a quasi-conservative tracer for different origins of water masses (Atlantic Ocean/Norwegian Sea, Pacific Ocean, Arctic Shelves). 9Be and Nd isotope analyses provide complementary information on the pathways of dissolved material originating from the Arctic continents. Results obtained ten years ago at similar locations as in our study indicated a uniform distribution of 10Be at low values of 500 +/- 100 atoms/g suggesting restricted input and efficient homogenisation. In contrast, our new results show that in 2001 the inflowing waters from the Atlantic are traced by 10Be concentrations of up to 1100 atoms/g. In addition, the surface concentrations vary considerably. It will be discussed wether this is a consequence of a seasonal/decadal variability in the distribution of surface water masses, which has been deduced from oceanographic

  9. In-situ electrochemical measurements of total concentration and speciation of heavy metals in acid mine drainage (AMD): assessment of the use of anodic stripping voltammetry.

    PubMed

    Jung, Hun-Bok; Yun, Seong-Taek; Kim, Soon-Oh; Jung, Myung Chae; So, Chil-Sup; Koh, Yong-Kwon

    2006-06-01

    We assessed the use of anodic stripping voltammetry (ASV) for in-situ determinations of both total concentration and speciation of dissolved heavy metals (Cd, Cu, Pb and Zn) in acid mine drainage (AMD). In the Kwangyang Au-Ag mine area of South Korea, different sites with varying water chemistry within an AMD were studied with a field portable anodic stripping voltammeter. Anodic stripping voltammetry after wet oxidation (acidification) was very sensitive enough to determine total concentration of dissolved Cd because Cd was dominantly present as 'labile' species, whilst the technique was not so effective for determining total Cu especially in the downstream sites from the retention pond, due to its complexation with organic matter. For dissolved Pb, the concentrations determined by ASV after wet oxidation generally agreed with those by ICP-AES. In the downstream samples (pH>5), however, ASV data after wet oxidation were lower than ICP-AES data because a significant fraction of dissolved Pb was present in those samples as 'inert' species associated with colloidal iron oxide particles. The determination of total dissolved Zn by ASV after wet oxidation appeared to be unsatisfactory for the samples with high Cu content, possibly due to the interference by the formation of Zn-Cu intermetallic compounds on the mercury coated electrode. In AMD samples with high dissolved iron, use of ultraviolet irradiation was not effective for determining total concentrations because humate destruction by UV irradiation possibly resulted in the removal of a part of dissolved heavy metals from waters through the precipitation of iron hydroxides. PMID:16767566

  10. Effects of climate change on stream temperature, dissolved oxygen, and sediment concentration in the Sierra Nevada in California

    NASA Astrophysics Data System (ADS)

    Ficklin, Darren L.; Stewart, Iris T.; Maurer, Edwin P.

    2013-05-01

    Warmer temperatures are expected to raise mountain stream temperatures, affecting water quality and ecosystem health. We demonstrate the importance of climate-driven changes in hydrology as fundamental to understanding changes in the local water quality. In particular, we focus on changes in stream temperature, dissolved oxygen (DO) concentrations, and sediment transport in mountainous, snowmelt-dominated, and water-limited systems, using the Sierra Nevada as our case study. Downscaled output from an ensemble of general circulation model projections for the A2 (higher greenhouse gas) emission scenario was used to drive the Soil and Water Assessment Tool with a new integrated stream temperature model on the subbasin scale. Spring and summer stream temperature increase by 1°C-5.5°C, with varying increases among subbasins. The highest projected stream temperatures are in the low-elevation subbasins of the southern Sierra Nevada, while the northern Sierra Nevada, with distinct impacts on snowmelt and subsurface flow contributions to streamflow, shows moderated increases. The spatial pattern of stream temperature changes was the result of differences in surface and subsurface hydrologic, snowmelt, and air temperature changes. Concurrent with stream temperature increases and decreases in spring and summer flows, simulations indicated decreases in DO (10%) and sediment (50%) concentrations by 2100. Stream temperature and DO concentrations for several major streams decline below survival thresholds for several native indicator species. These results highlight that climatic changes in water-limited mountain systems may drive changes in water quality that have to be understood on the reach scale for developing adaptive management options.

  11. Influence of increasing dissolved inorganic carbon concentrations and decreasing pH on chemolithoautrophic bacteria from oxic-sulfidic interfaces

    NASA Astrophysics Data System (ADS)

    Mammitzsch, K.; Jost, G.; Jürgens, K.

    2012-12-01

    Increases in the dissolved inorganic carbon (DIC) concentration are expected to cause a decrease in the pH of ocean waters, a process known as ocean acidification. In oxygen-deficient zones this will add to already increased DIC and decreased pH values. It is not known how this might affect microbial communities and microbially mediated processes. In this study, the potential effects of ocean acidification on chemolithoautotrophic prokaryotes of marine oxic-anoxic transition zones were investigated, using the chemoautotrophic denitrifying ɛ-proteobacterium "Sulfurimonas gotlandica" strain GD1 as a model organism. This and related taxa use reduced sulfur compounds, e.g. sulfide and thiosulfate, as electron donors and were previously shown to be responsible for nitrate removal and sulfide detoxification in redox zones of the Baltic Sea water column but occur also in other oxygen-deficient marine systems. Bacterial cell growth within a broad range of DIC concentrations and pH values was monitored and substrate utilization was determined. The results showed that the DIC saturation concentration for growth was already reached at 800 μM, which is well below in situ DIC levels. The pH optimum was between 6.6 and 8.0. Within a pH range of 6.6-7.1 there was no significant difference in substrate utilization; however, at lower pH values cell growth decreased sharply and cell-specific substrate consumption increased. These findings suggest that a direct effect of ocean acidification, with the predicted changes in pH and DIC, on chemolithoautotrophic bacteria such as "S. gotlandica" str. GD1 is generally not very probable.

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

    USGS Publications Warehouse

    Landmeyer, James E.; Effinger, Thomas N.

    2016-01-01

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

  13. Environmental geochemistry of shale-hosted Ag-Pb-Zn massive sulfide deposits in northwest Alaska: Natural background concentrations of metals in water from mineralized areas

    USGS Publications Warehouse

    Kelley, K.D.; Taylor, C.D.

    1997-01-01

    Red Dog, Lik and Drenchwater are shale-hosted stratiform Ag-Pb-Zn massive sulfide deposits in the northwestern Brooks Range. Natural background concentrations of metals in waters from the undisturbed (unmined) Drenchwater prospect and Lik deposit were compared to pre-mining baseline studies conducted at Red Dog. The primary factors affecting water chemistry are the extent of exposure of the deposits, the grade of mineralization, the presence of carbonate reeks in the section, and the proportion of Fe-sulfide in the ore. Surface water samples from the Drenchwater prospect, which has pyrite-dominant mineralization exposed in outcrop, have pH values as low as 2.8 and high dissolved concentrations of metals including as much as 95 mg 1-1 Al, 270 mg 1-1 Fe, 8 ??1-1 Cd, 10 ??1-1 Pb, and 2600 ??1-1 Zn, with As up to 26 ??g1-1. Surface waters from the Red Dog deposit prior to mining were also acidic and metal-rich, however, dissolved metal concentrations in Red Dog waters were many times greater. The higher metal concentrations in Red Dog waters reflect the high Zn grades and the abundant sphalerite, pyrite, and galena that were present in outcrop prior to mining. In contrast, despite significant mineralization at the Lik deposit, carbonate rocks in the section buffer the system, resulting in less acidic, mostly near-neutral pH values with low concentrations of most metals except Zn.

  14. Trends in chloride, dissolved-solids, and nitrate concentrations in ground water, Carson Valley and Topaz Lake Areas, Douglas County, Nevada, 1959-88

    USGS Publications Warehouse

    Thodal, C.E.

    1996-01-01

    Rapid population growth in Douglas County, an area of approximately 750 square miles in west-central Nevada, has led to concern about the present and future effects of development on ground water. This report describes the results of two nonparametric statistical procedures applied to detect trends in concentrations of chloride, dissolved solids, and nitrate in ground water. The water-quality data consist of analytical results from ground-water samples collected and analyzed by the U. S. Geological Survey and ground-water-quality data provided by the Nevada Bureau of Health Protection Services for the Carson Valley and Topaz Lake areas of Douglas County, Nevada. For purposes of this study, statistical significance, expressed as the p-value, was set at 0.1. The Mann-Whitney-Wilcoxan rank-sum test detected increasing step-trends for nitrate in one of seven residential areas and for dissolved-solids concentrations throughout the study area. Decreasing step-trends for chloride and dissolved-solids concentrations were detected in the west Carson Valley area. Kendall's Tau detected monotonic trends for increasing nitrate concentrations at four domestic wells and for increasing dissolved-solids concentrations at two domestic wells. No other statistically significant trends were indicated by either test. Land-use relations to areas where increasing trends were detected suggest that the density of individual wastewater-treatment systems may exceed the capacity of soils to treat wastewater leachate.

  15. Water uptake and growth of cucumber plants (Cucumis sativus L.) under control of dissolved O2 concentration in hydroponics.

    PubMed

    Yoshida, S; Kitano, M; Eguchi, H

    1996-12-01

    Dissolved O2 concentration ([O2]) in nutrient solution was controlled at 0.01, 0.10 and 0.20 mM with accuracy of +/- 0.005 mM in a newly developed hydroponic system, and the effects of [O2] on water uptake and growth of cucumber plants (Cucumis sativus L.) were analyzed. For evaluating water uptake rate under the control of [O2], water flux at the stem base was measured on-line with +/-5% in accuracy, 1 mg s-1 in resolution and 1 min in time constant by heat flux control (HFC) method. Water uptake rate was drastically increased by lighting to the plant at each [O2], and water uptake per day was depressed in proportion to decrease in [O2]. In the plants grown for 10 days, leaf area, fresh weight and dry weight of leaves decreased at lower [O2], while stem length and number of leaves were scarcely affected. These facts suggest that membrane permeability of root cells reduces at lower [O2] through respiration-dependent processes, and growth is inhibited through leaf turgor loss caused by the depressed water uptake of roots in O2-deficient nutrient solution in hydroponics.

  16. Heavy metal concentrations in Louisiana waterways, sediments, and biota

    SciTech Connect

    Bundy, K.J.; Berzins, D.

    1994-12-31

    In this investigation polarographic methods (along with GFAAS and ICP) have been used to study the distribution of lead and chromium in Bayou Trepagnier and Devil`s Swamp. Both laboratory and field research have been conducted. Separation and extraction methodology appropriate for analysis of the contaminants at these sites have been developed. Particular attention has been paid to extraction methods for chromium which do not lead to valence state conversion. The availability of such techniques is essential to take full advantage of polarography, a method capable of performing speciation analysis. The results indicate that there is a very inhomogeneous distribution of heavy metals in these environments. In Devil`s Swamp, for example, separation and analysis of aqueous and variously sized particulate moieties in the water and sediment compartments were conducted to determine the partition of lead between them. The results showed that the average lead content was 14.7 ppb and 19.8 ppm, respectively, in these compartments. Apparently bull frogs in Devil`s Swamp can bioaccumulate lead (compared to the measured water level), since the muscle concentration was found to be about 0.6 ppm. This phenomenon is being investigated in a Xenopus frog laboratory model of heavy metal uptake. The basic methodology validated in this study should be fairly generally applicable to assays of other heavy metals.

  17. Trace-metal concentrations in sediment and water and health of aquatic macroinvertebrate communities of streams near Park City, Summit County, Utah

    USGS Publications Warehouse

    Giddings, Elis M.P.; Hornberger, Michelle I.; Hadley, Heidi K.

    2001-01-01

    The spatial distribution of metals in streambed sediment and surface water of Silver Creek, McLeod Creek, Kimball Creek, Spring Creek, and part of the Weber River, near Park City, Utah, was examined. From the mid-1800s through the 1970s, this region was extensively mined for silver and lead ores. Although some remediation has occurred, residual deposits of tailing wastes remain in place along large sections of Silver Creek. These tailings are the most likely source of metals to this system. Bed sediment samples were collected in 1998, 1999, and 2000 and analyzed using two extraction techniques: a total extraction that completely dissolves all forms of metals in minerals and trace elements associated with the sediment; and a weak-acid extraction that extracts the metals and trace elements that are only weakly adsorbed onto the sediment surface. This latter method is used to determine the more biologically relevant fraction of metal complexed onto the sediment. Water samples were collected in March and August 2000 and were analyzed for total and dissolved trace metals. Concentrations of silver, cadmium, copper, lead, mercury, and zinc in the streambed sediment of Silver Creek greatly exceeded background concentrations. These metals also exceeded established aquatic life criteria at most sites. In the Weber River, downstream of the confluence with Silver Creek, concentrations of cadmium, lead, zinc, and total mercury in streambed sediment also exceeded aquatic life guidelines, however, concentrations of metals in streambed sediment of McLeod and Kimball Creeks were lower than Silver Creek. Water-column concentrations of zinc, total mercury, and methylmercury in Silver Creek were high relative to unimpacted sites, and exceeded water quality criteria for the protection of aquatic organisms. Qualitative measurements of the macroinvertebrate community in Silver Creek were compared to the spatial distribution of metals in streambed sediment. The data indicate that

  18. Trout density and health in a stream with variable water temperatures and trace element concentrations: does a cold-water source attract trout to increased metal exposure?

    USGS Publications Warehouse

    Harper, D.D.; Farag, A.M.; Hogstr, C.; MacConnell, Elizabeth

    2009-01-01

    A history of hard-rock mining has resulted in elevated concentrations of heavy metals in Prickly Pear Creek (MT. USA). Remediation has improved water quality; however, dissolved zinc and cadmium concentrations still exceed U.S. Environmental Protection Agency water-quality criteria. Physical habitat, salmonid density, fish health, and water quality were assessed, and metal concentrations in fish tissues, biofilm, and macroinvertebrates were determined to evaluate the existing condition in the watershed. Cadmium, zinc, and lead concentrations in fish tissues, biofilm, and invertebrates were significantly greater than those at the upstream reference site and an experimental site farther downstream of the confluence. Fish densities were greatest, and habitat quality for trout was better, downstream of the confluence, where water temperatures were relatively cool (16??C). Measures of fish health (tissue metal residues, histology, metallothionein concentrations, and necropsies), however, indicate that the health of trout at this site was negatively affected. Trout were in colder but more contaminated water and were subjected to increased trace element exposures and associated health effects. Maximum water temperatures in Prickly Pear Creek were significantly lower directly below Spring Creek (16??C) compared to those at an experimental site 10 km downstream (26??C). Trout will avoid dissolved metals at concentrations below those measured in Prickly Pear Creek; however, our results suggest that the preference of trout to use cool water temperatures may supersede behaviors to avoid heavy metals. ?? 2009 SETAC.

  19. Year-round record of dissolved and particulate metals in surface snow at Dome Concordia (East Antarctica).

    PubMed

    Grotti, Marco; Soggia, Francesco; Ardini, Francisco; Magi, Emanuele; Becagli, Silvia; Traversi, Rita; Udisti, Roberto

    2015-11-01

    From January to December 2010, surface snow samples were collected with monthly resolution at the Concordia station (75°06'S, 123°20'E), on the Antarctic plateau, and analysed for major and trace elements in both dissolved and particulate (i.e. insoluble particles, >0.45 μm) phase. Additional surface snow samples were collected with daily resolution, for the determination of sea-salt sodium and not-sea-salt calcium, in order to support the discussion on the seasonal variations of trace elements. Concentrations of alkaline and alkaline-earth elements were higher in winter (April-October) than in summer (November-March) by a factor of 1.2-3.3, in agreement with the higher concentration of sea-salt atmospheric particles reaching the Antarctic plateau during the winter. Similarly, trace elements were generally higher in winter by a factor of 1.2-1.5, whereas Al and Fe did not show any significant seasonal trend. Partitioning between dissolved and particulate phases did not change with the sampling period, but it depended only on the element: alkaline and alkaline-earth elements, as well as Co, Cu, Mn, Pb and Zn were for the most part (>80%) in the dissolved phase, whereas Al and Fe were mainly associated with the particulate phase (>80%) and Cd, Cr, V were nearly equally distributed between the phases. Finally, the estimated marine and crustal enrichment factors indicated that Cd, Cr, Cu, Pb and Zn have a dominant anthropogenic origin, with a possible contribution from the Concordia station activities.

  20. Characterization of the structure, clean-sand percentage, dissolved-solids concentrations, and estimated quantity of groundwater in the Upper Cretaceous Nacatoch Sand and Tokio Formation, Arkansas

    USGS Publications Warehouse

    Gillip, Jonathan A.

    2014-01-01

    The West Gulf Coastal Plain, Mississippi embayment, and underlying Cretaceous aquifers are rich in water resources; however, large parts of the aquifers are largely unusable because of large concentrations of dissolved solids. Cretaceous aquifers are known to have large concentrations of salinity in some parts of Arkansas. The Nacatoch Sand and the Tokio Formation of Upper Cretaceous age were chosen for investigation because these aquifers produce groundwater to wells near their outcrops and have large salinity concentrations away from their outcrop areas. Previous investigations have indicated that dissolved-solids concentrations of groundwater within the Nacatoch Sand, 2–20 miles downdip from the outcrop, render the groundwater as unusable for purposes requiring freshwater. Groundwater within the Tokio Formation also exhibits large concentrations of dissolved solids downdip. Water-quality data showing elevated dissolved-solids concentrations are limited for these Cretaceous aquifers because other shallower aquifers are used for water supply. Although not suitable for many uses, large, unused amounts of saline groundwater are present in these aquifers. Historical borehole geophysical logs were used to determine the geologic and hydrogeologic properties of these Cretaceous aquifers, as well as the quality of the groundwater within the aquifers. Based on the interpretation of borehole geophysical logs, in Arkansas, the altitude of the top of the Nacatoch Sand ranges from more than 200 to less than -4,000 feet; the structural high occurs in the outcrop area and the structural low occurs in southeastern Arkansas near the Desha Basin structural feature. The thickness of the Nacatoch Sand ranges from 0 to over 550 feet. The minimum thickness occurs where the formation pinches out in the outcrop area, and the maximum thickness occurs in the southwestern corner of Arkansas. Other areas of large thickness include the area of the Desha Basin structural feature in

  1. Effect of the spatiotemporal variability of rainfall inputs in water quality integrated catchment modelling for dissolved oxygen concentrations

    NASA Astrophysics Data System (ADS)

    Moreno Ródenas, Antonio Manuel; Cecinati, Francesca; ten Veldhuis, Marie-Claire; Langeveld, Jeroen; Clemens, Francois

    2016-04-01

    Maintaining water quality standards in highly urbanised hydrological catchments is a worldwide challenge. Water management authorities struggle to cope with changing climate and an increase in pollution pressures. Water quality modelling has been used as a decision support tool for investment and regulatory developments. This approach led to the development of integrated catchment models (ICM), which account for the link between the urban/rural hydrology and the in-river pollutant dynamics. In the modelled system, rainfall triggers the drainage systems of urban areas scattered along a river. When flow exceeds the sewer infrastructure capacity, untreated wastewater enters the natural system by combined sewer overflows. This results in a degradation of the river water quality, depending on the magnitude of the emission and river conditions. Thus, being capable of representing these dynamics in the modelling process is key for a correct assessment of the water quality. In many urbanised hydrological systems the distances between draining sewer infrastructures go beyond the de-correlation length of rainfall processes, especially, for convective summer storms. Hence, spatial and temporal scales of selected rainfall inputs are expected to affect water quality dynamics. The objective of this work is to evaluate how the use of rainfall data from different sources and with different space-time characteristics affects modelled output concentrations of dissolved oxygen in a simplified ICM. The study area is located at the Dommel, a relatively small and sensitive river flowing through the city of Eindhoven (The Netherlands). This river stretch receives the discharge of the 750,000 p.e. WWTP of Eindhoven and from over 200 combined sewer overflows scattered along its length. A pseudo-distributed water quality model has been developed in WEST (mikedhi.com); this is a lumped-physically based model that accounts for urban drainage processes, WWTP and river dynamics for several

  2. Temporal control on concentration, character, and export of dissolved organic carbon in two hemiboreal headwater streams draining contrasting catchments

    NASA Astrophysics Data System (ADS)

    Wallin, Marcus B.; Weyhenmeyer, Gesa A.; Bastviken, David; Chmiel, Hannah E.; Peter, Simone; Sobek, Sebastian; Klemedtsson, Leif

    2015-05-01

    Although lateral carbon (C) export from terrestrial to aquatic systems is known to be an important component in landscape C balances, most existing global studies are lacking empirical data on the soil C export. In this study, the concentration, character, and export of dissolved organic carbon (DOC) were studied during 2 years in two hemiboreal headwater streams draining catchments with different soil characteristics (mineral versus peat soils). The streams exposed surprisingly similar strong air temperature controls on the temporal variability in DOC concentration in spite of draining such different catchments. The temporal variability in DOC character (determined by absorbance metrics, specific ultraviolet absorbance 254 (SUVA254) as a proxy for aromaticity and a254/a365 ratio as a proxy for mean molecular weight) was more complex but related to stream discharge. While the two streams showed similar ranges and patterns in SUVA254, we found a significant difference in median a254/a354, suggesting differences in the DOC character. Both streams responded similarly to hydrological changes with higher a254/a365 at higher discharge, although with rather small differences in a254/a365 between base flow and high flow (<0.3). The DOC exports (9.6-25.2 g C m-2 yr-1) were among the highest reported so far for Scandinavia and displayed large interannual and intraannual variability mainly driven by irregular precipitation/discharge patterns. Our results show that air temperature and discharge affect the temporal variability in DOC quantity and character in different ways. This will have implications for the design of representative sampling programs, which in turn will affect the reliability of future estimates of landscape C budgets.

  3. Effects of dissolved organic carbon and second substrates on the biodegradation of organic compounds at low concentrations

    SciTech Connect

    Schmidt, S.K.; Alexander, M.

    1985-04-01

    Pseudomonas acidovorans and Pseudomonas sp. strain ANL but not Salmonella typhimurium grew in an inorganic salts solution. The growth of P. acidovorans in this solution was not enhanced by the addition of 2.0 ..mu..g of phenol per liter, but the phenol was mineralized. Mineralization of 2.0 ..mu..g of phenol per liter by P. acidovorans was delayed 16 h by 70 ..mu..g of acetate per liter, and the delay was lengthened by increasing acetate concentrations, whereas phenol and acetate were utilized simultaneously at concentrations of 2.0 and 13 ..mu..g/liter, respectively. Growth of Pseudomonas sp. in the inorganic salts solution was not affected by the addition of 3.0 ..mu..g each of glucose and aniline per liter, nor was mineralization of the two compounds detected during the initial period of growth. However, mineralization of both substrates by this organism occurred simultaneously during the latter phases of growth and after growth had ended at the expense of the uncharacterized dissolved organic compounds in the salts solution. In contrast, when Pseudomonas sp. was grown in the salts solution supplemented with 300 ..mu..g each of glucose and aniline, the sugar was mineralized first, and aniline was mineralized only after much of the glucose carbon was converted to CO/sub 2/. S. typhimurium failed to multiply in the salts solution with 1.0 ..mu..g of glucose per liter. It grew slightly but mineralized little of the sugar at 5.0 ..mu..g/liter, but its population density rose at 10 ..mu..g of glucose per liter or higher. The hexose could be mineralized at 0.5 ..mu..g/liter, however, if the solution contained 5.0 mg of arabinose per liter.

  4. Dissolved carbon dioxide and oxygen concentrations in purge of vacuum-packaged pork chops and the relationship to shelf life and models for estimating microbial populations.

    PubMed

    Adams, K R; Niebuhr, S E; Dickson, J S

    2015-12-01

    The objectives of this study were to determine the dissolved CO2 and O2 concentrations in the purge of vacuum-packaged pork chops over a 60 day storage period, and to elucidate the relationship of dissolved CO2 and O2 to the microbial populations and shelf life. As the populations of spoilage bacteria increased, the dissolved CO2 increased and the dissolved O2 decreased in the purge. Lactic acid bacteria dominated the spoilage microflora, followed by Enterobacteriaceae and Brochothrix thermosphacta. The surface pH decreased to 5.4 due to carbonic acid and lactic acid production before rising to 5.7 due to ammonia production. A mathematical model was developed which estimated microbial populations based on dissolved CO2 concentrations. Scanning electron microscope images were also taken of the packaging film to observe the biofilm development. The SEM images revealed a two-layer biofilm on the packaging film that was the result of the tri-phase growth environment. PMID:26143235

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

    EPA Science Inventory

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

  6. Using Performance Reference Compounds (PRCs) to measure dissolved water concentrations (Cfree) in the water column: Assessing equilibrium models

    EPA Science Inventory

    Equilibrium-based passive sampling methods are often used in aquatic environmental monitoring to measure hydrophobic organic contaminants (HOCs) and in the subsequent evaluation of their effects on ecological and human health. HOCs freely dissolved in water (Cfree) will partition...

  7. Contrasting distributions of dissolved gaseous mercury concentration and evasion in the North Pacific Subarctic Gyre and the Subarctic Front

    NASA Astrophysics Data System (ADS)

    Kim, Hyunji; Rhee, Tae Siek; Hahm, Doshik; Hwang, Chung Yeon; Yang, Jisook; Han, Seunghee

    2016-04-01

    The distribution of dissolved gaseous mercury (DGM) and the oxidation-reduction processes of mercury (Hg) in the surface and subsurface ocean are currently understudied despite their importance in ocean-atmosphere interactions. We investigated the Hg(0) evasion and the DGM distribution at water depths of 2-500 m in the Subarctic Front, Western Subarctic Gyre, and Bering Sea of the Northwestern Pacific. The mean DGM concentration in the surface mixed water (<10 m) and the mean Hg(0) evasion flux were significantly higher in the Subarctic Front (125±5.0 fM and 15 pmol m-2 h-1, respectively), which typically has lower nutrient levels and higher primary production, than in the Western Subarctic Gyre and the Bering Sea (74±18 fM and 3.2±1.2 pmol m-2 h-1, respectively). The variation in the chlorophyll-a concentration and extracellular protease activity predicted 54% and 48% of the DGM variation, respectively, in the euphotic zone (2-50 m). The DGM concentration in aphotic intermediate water (415±286 fM) was positively correlated to the apparent oxygen utilization (AOU; r2=0.94 and p<0.001 for the Western Subarctic Gyre and the Bering Sea; r2=0.61 and p=0.01 for the Subarctic Front), emphasizing the importance of microbial oxidation of organic matter. The DGM-to-AOU ratio in aphotic water was significantly (p<0.05, ANCOVA) higher at the Western Subarctic Gyre and Bering Sea sites (2.5±0.14) than the ratio at the Subarctic Front sites (0.89±0.27) that mainly consisted of newly formed North Pacific Intermediate Water. The overall results imply that variation of DGM and Hg(0) evasion is closely linked to primary production in euphotic water and organic remineralization in aphotic intermediate water. The oceanic alterations in these factors may induce significant modification in Hg redox speciation in the Northwestern Pacific.

  8. Assessment of the Impact of Climate Change and Land Management Change on Soil Organic Carbon Content, Leached Carbon Rates and Dissolved Organic Carbon Concentrations

    NASA Astrophysics Data System (ADS)

    Stergiadi, Maria; de Nijs, Ton; van der Perk, Marcel; Bonten, Luc

    2014-05-01

    Climate change is projected to significantly affect the concentrations and mobility of contaminants, such as metals and pathogens, in soil, groundwater and surface water. Climate- and land management-induced changes in soil organic carbon and dissolved organic carbon levels may promote the transport of toxic substances, such as copper and cadmium, and pathogenic microorganisms, ultimately affecting the exposure of humans and ecosystems to these contaminants. In this study, we adopted the Century model to simulate past (1900 - 2010), present, and future (2010 - 2100) SOC and DOC levels for a sandy and a loamy soil typical for Central and Western European conditions under three land use types (forest, grassland and arable land) and several future scenarios addressing climate change and land management change. The climate scenarios were based on the KNMI'06 G+ and W+ scenarios from the Royal Dutch Meteorological Institute. The simulated current SOC levels were compared to observed SOC values derived from various Dutch soil databases, taking into account the different soil depths the simulated and observed values refer to. The simulated SOC levels were generally in line with the observed values for the different kinds of soil and land use types. Climate change scenarios resulted in a decrease in both SOC and DOC for the grassland systems, whereas in the arable land (on sandy soil) and in the forest systems, SOC was found to increase and DOC to decrease. A sensitivity analysis of the individual effects of changes in temperature and precipitation showed that the effect of temperature predominates over the effect of precipitation. A reduction in the application rates of artificial fertilizers leads to a decrease in the SOC stocks and the leached carbon rates in the arable land systems, but has a negligible effect on SOC and DOC levels of the grassland systems. This study demonstrated the ability of the Century model to simulate climate change and agricultural management

  9. High Temperature Concentrated Solar Power Using Liquid Metal

    NASA Astrophysics Data System (ADS)

    Henry, Asegun

    One of the most attractive ways to try and reduce the cost of concentrated solar power (CSP) is to increase the system efficiency and the biggest loss in the system occurs in the conversion of heat to electricity via heat engine. Heat engines that utilize turbomachinery currently operate near their thermodynamic limitations and thus one of the only ways to improve heat engine efficiency is to increase the turbine inlet temperature. Significant effort is being devoted to the development of supercritical CO2 heat engines, but the most efficient heat engines are combined cycles, which reach efficiencies as high as 60%. However, such heat engines require turbine inlet temperatures ~1300-1500C, which is far beyond what is currently feasible with the state of the art molten salt infrastructure. In working towards the development of a system that can operate in the 1300-1500C temperature range, the most significant challenges lie in the materials and forming functional and reliable components out of new materials. One of the most attractive options from a cost and heat transfer perspective is to use liquid metals, such as tin and aluminum-silicon alloys along with a ceramic based infrastructure. This talk will overview ongoing efforts in the Atomistic Simulation and Energy (ASE) research group at Georgia Tech to develop prototype components such as an efficient high temperature cavity receiver, pumps and valves that can make a liquid metal based CSP infrastructure realizable.

  10. Metal concentration and antioxidant activity of edible mushrooms from Turkey.

    PubMed

    Sarikurkcu, Cengiz; Tepe, Bektas; Kocak, Mehmet Sefa; Uren, Mehmet Cemil

    2015-05-15

    This study presents information on the antioxidant activity and heavy metal concentrations of Polyporus sulphureus, Macrolepiota procera, Lycoperdon perlatum and Gomphus clavatus mushrooms collected from the province of Mugla in the South-Aegean Region of Turkey. Antioxidant activities of mushroom samples were evaluated by four complementary tests. All tests showed L. perlatum and G. clavatus to possess extremely high antioxidant potential. Antioxidant activity of the samples was strongly correlated with total phenolic-flavonoid content. In terms of heavy metal content, L. perlatum exceeded the legal limits for daily intake of Pb, Fe, Mn, Cr, Ni and Co contents (0.461, 738.00, 14.52, 1.27, 1.65, 0.417 mg/day, respectively) by a 60-kg consumer. Co contents of M. procera (0.026 mg/day) and P. sulphureus (0.030 mg/day) and Cd contents of G. clavatus (0.071 mg/day) were also above the legal limits. According to these results, L. perlatum should not be consumed, despite the potentially beneficial antioxidant activity. Additionally, M. procera and G. clavatus should not be consumed daily due to their high levels of Cd and Co.

  11. Fatigue stress concentration and notch sensitivity in nanocrystalline metals

    DOE PAGES

    Furnish, Timothy A.; Boyce, Brad L.; Sharon, John A.; O’Brien, Christopher J.; Clark, Blythe G.; Arrington, Christian L.; Pillars, Jamin R.

    2016-03-11

    Recent studies have shown the potential for nanocrystalline metals to possess excellent fatigue resistance compared to their coarse-grained counterparts. Although the mechanical properties of nanocrystalline metals are believed to be particularly susceptible to material defects, a systematic study of the effects of geometric discontinuities on their fatigue performance has not yet been performed. In the present work, nanocrystalline Ni–40 wt%Fe containing both intrinsic and extrinsic defects were tested in tension–tension fatigue. The defects were found to dramatically reduce the fatigue resistance, which was attributed to the relatively high notch sensitivity in the nanocrystalline material. Microstructural analysis within the crack-initiation zonesmore » underneath the defects revealed cyclically-induced abnormal grain growth (AGG) as a predominant deformation and crack initiation mechanism during high-cycle fatigue. Furthermore, the onset of AGG and the ensuing fracture is likely accelerated by the stress concentrations, resulting in the reduced fatigue resistance compared to the relatively defect-free counterparts.« less

  12. Effects of Land Use on Stable Carbon Isotopic Composition and Concentration of Dissolved Organic Carbon (DOC) and Dissolved Inorganic Carbon (DIC) in Southeastern US Piedmont Headwater Streams

    EPA Science Inventory

    Stable carbon isotopic composition (delta 13C) and concentrations of DOC and DIC were measured in stream water samples collected monthly in 15 headwater streams from an area with extensive poultry and cattle production and a rapidly growing human population. Linear regression te...

  13. Effects of environmentally relevant concentrations of metallic compounds on the flatfish Scophthalmus maximus: biomarkers of neurotoxicity, oxidative stress and metabolism.

    PubMed

    Nunes, Bruno; Brandão, Fátima; Sérgio, Tânia; Rodrigues, Sara; Gonçalves, Fernando; Correia, Alberto Teodorico

    2014-06-01

    Flatfish species, such as the turbot (Scophthalmus maximus), are common targets for toxic effects, since they are exposed through the food chain (ingestion of contaminated preys) and are in direct contact with the waterborne contaminant and sediments. Furthermore, these fish species live in close proximity to interstitial water that frequently dissolves high amounts of contaminants, including metals. Despite this significant set of characteristics, the present knowledge concerning flatfish contamination and toxicity by metals is still scarce. To attain the objective of assessing the effects of metals on a flatfish species, S. maximus specimens were chronically exposed to lead, copper and zinc, at ecologically relevant concentrations, and biochemical (oxidative stress: catalase and glutathione S-transferases activities, and lipid peroxidation; neurotoxicity: cholinesterase activity) parameters were assessed on selected tissues (gills and liver). Copper had no significant effects on all tested parameters; lead was causative of significant increases in liver GSTs activities and also in lipoperoxidation of gill tissue; exposure to zinc caused a significant increase in catalase activity of gill tissue. None of the tested metals elicited noteworthy effects in terms of neurotoxicity. The obtained results showed that only the metal lead is of some environmental importance, since it was able to cause deleterious modifications of oxidative nature at relevant concentrations.

  14. Effects of environmentally relevant concentrations of metallic compounds on the flatfish Scophthalmus maximus: biomarkers of neurotoxicity, oxidative stress and metabolism.

    PubMed

    Nunes, Bruno; Brandão, Fátima; Sérgio, Tânia; Rodrigues, Sara; Gonçalves, Fernando; Correia, Alberto Teodorico

    2014-06-01

    Flatfish species, such as the turbot (Scophthalmus maximus), are common targets for toxic effects, since they are exposed through the food chain (ingestion of contaminated preys) and are in direct contact with the waterborne contaminant and sediments. Furthermore, these fish species live in close proximity to interstitial water that frequently dissolves high amounts of contaminants, including metals. Despite this significant set of characteristics, the present knowledge concerning flatfish contamination and toxicity by metals is still scarce. To attain the objective of assessing the effects of metals on a flatfish species, S. maximus specimens were chronically exposed to lead, copper and zinc, at ecologically relevant concentrations, and biochemical (oxidative stress: catalase and glutathione S-transferases activities, and lipid peroxidation; neurotoxicity: cholinesterase activity) parameters were assessed on selected tissues (gills and liver). Copper had no significant effects on all tested parameters; lead was causative of significant increases in liver GSTs activities and also in lipoperoxidation of gill tissue; exposure to zinc caused a significant increase in catalase activity of gill tissue. None of the tested metals elicited noteworthy effects in terms of neurotoxicity. The obtained results showed that only the metal lead is of some environmental importance, since it was able to cause deleterious modifications of oxidative nature at relevant concentrations. PMID:24595748

  15. Using in-situ spectrophotometric sensors to monitoring dissolved organic carbon concentration: our S::CAN experience

    NASA Astrophysics Data System (ADS)

    Coleman, Martin; Waldron, Susan; Scott, Marian; Drew, Simon

    2013-04-01

    Dissolved organic carbon, (DOC), is the component of the organic carbon that can pass through a membrane filter, with the accepted maximum pore size of 0.7 μm. There is growing interest in high resolution time series of such data e.g. heterotrophic respiration of DOC in freshwater systems can fuel atmospheric CO2 efflux so observing variation in DOC concentration, [DOC], is meaningful. Field deployable sensors, capable of measuring [DOC] on a continuous basis, have the potential to provide us with a far higher resolution time series data than we can obtain through manual sampling. At a catchment area draining Europe's largest windfarm, Whitelee, we have deployed an S::CAN Spectrolyser. This device scans wavelengths from 200 to 735nm, generating a spectral fingerprint and then, using an inbuilt algorithm, returns a value for the DOC concentration, termed DOC-equivalent, [DOC-eq]. The Spectrolyser also estimates other parameters such as total organic carbon and the true colour of the water. Unfortunately, our field Spectrolyser [DOC] are different from lab based measurement of [DOC] of the same field filtered samples (measured using a Thermalox high temperature catalytic oxidation system). Comparing 28 lab measured [DOC] with Spectrolyser [DOC-eq] shows an average difference of 7.6 mg/l C. Here we discuss our interpretation of why this disparity exists and how to accommodate this offset such that accuracy is improved. We have tried various methods of keeping the lens and path length clean through brushing, acid cleaning and the recent installation of a high pressure air hose (recommended by S::CAN). We will compare output before and after this installation. Further complexity is added because light may be absorbed by other components of the field sample, such as particulate material, and this could compromise the estimated [DOC-eq]. [DOC] may be estimated using absorption measurements made at 254nm and 340nm (Tipping et al, 2009). We have implemented this formula

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

    PubMed

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

    2013-05-01

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

  17. Factors affecting dissolved phosphorus and nitrate concentrations in ground and surface water for a valley dairy farm in the northeastern United States.

    PubMed

    Flores-López, Francisco; Easton, Zachary M; Geohring, Larry D; Steenhuis, Tammo S

    2011-02-01

    Agriculture often is considered to be a contributor of soluble reactive phosphorus (SRP) and nitrate-N (NO3- -N) to surface waters. This research analyzed SRP and NO3- -N concentrations in groundwater and in a creek fed by groundwater on a valley dairy farm in the Cannonsville basin of the New York City (NYC) watershed. A total of 37 groundwater piezometers were installed to depths of 0.3 to 1.5 m. Water-table depth and concentrations of SRP, NO3- -N, dissolved organic carbon (DOC), and dissolved oxygen were measured at regular intervals over a three-year period. A multivariate mixed model analysis of variance indicated that the SRP and NO3- -N concentrations were controlled primarily by three classes of variables: environmental variables, including precipitation and water table depth; source variables, including manure applied and crop type; and chemical variables, including DOC and dissolved oxygen concentrations in groundwater. The highest groundwater concentrations of N03- -N and SRP were found at the shallowest water-table depths, which has implications for agricultural nutrient management in areas with shallow groundwater.

  18. Metal exposures to native populations of the caddisfly Hydropsyche (Trichoptera: Hydropsychidae) determined from cytosolic and whole body metal concentrations

    USGS Publications Warehouse

    Cain, D.J.; Luoma, S.N.

    1998-01-01

    Metal concentrations of the soluble fraction of the cytoplasm (cytosol) and the whole body were determined in the caddisfly Hydropsyche spp. (Trichoptera). Metal accumulation in the cytosol and the whole body were compared in samples collected along 380 kms of a contamination gradient in the Clark Fork river in four consecutive years (1992-1995), and from a contaminated tributary (Flint Creek). Samples from the contaminated sites were compared to an uncontaminated tributary (Blackfoot River). Relations between cytosolic metal concentration and cytosolic protein (used as a general biomarker of protein metabolism) also were examined in 1994 and 1995. Relative to whole body concentrations, cytosolic metal concentrations varied among metals and years. Spatial patterns in whole body and cytosolic Cd, Cu and Pb concentrations were qualitatively similar each year, and these concentrations generally corresponded to contamination levels measured in bed sediments. The proportions of metals recovered in the cytosol of ranged from 12 to 64% for Cd and Cu and from 2 to 38% for Pb. Zinc in the whole body also was consistent with contamination levels, but cytosolic Zn concentrations increased only at the highest whole body Zn concentrations. As a result, the proportion of Zn recovered in the cytosol ranged from 16 to 63% and tended to be inversely related to whole body Zn concentrations. The proportions of cytosolic metals varied significantly among years and, as a result, interannual differences in metal concentrations were greater in the cytosol than in the whole body. The results demonstrated that Hydropsyche in the river were chronically exposed to biologically available metals. Some features of this exposure were not evident from whole body concentrations. In general, protein levels did not correspond to cytosolic metal concentrations. A variety of environmental factors could interact with metal exposures to produce complex responses in protein metabolism. Systematic study

  19. Thiol and metal contents in periphyton exposed to elevated copper and zinc concentrations: a field and microcosm study.

    PubMed

    Le Faucheur, Séverine; Behra, Renata; Sigg, Laura

    2005-10-15

    Phytochelatins are metal-binding polypeptides produced by algae under metal exposure. The aim of this study was to investigate the effects of metal concentration variations in natural systems on periphyton at the biochemical level by analyzing its intracellular thiol content, in particular phytochelatins. To that purpose, two field campaigns were conducted in a stream subject to an increase of dissolved metal concentrations (particularly Cu and Zn) during rain events, which results in an increase of their accumulation in periphyton. At background metal concentrations, several thiols were detectable in periphyton, namely, glutathione (GSH), gamma-glutamylcysteine (gammaGluCys), phytochelatins (PC2), and some unidentified thiols, U1 and U2. Glutathione and gammaGluCys contents were found to vary independently of the rain, as well as U1 and U2, whereas the phytochelatin content increased during the rain events. To investigate whether Cu or Zn may be responsible for this increase, microcosm experiments were carried out with natural water enriched with Cu, Zn, and Cd separately, and Cu and Zn in combination. In this study, GSH, PC2, and U1 were also detected, but not gammaGluCys. An increase in accumulated Cu content did not induce any changes in thiol content, whereas an increase of the Zn content induced a decrease in GSH content and an increase in phytochelatin content. Zinc rather than Cu may thus induce a phytochelatin content increase in periphyton in the field studies. Addition of Cu and Zn in combination also induced an increase in phytochelatin content. Cadmium was found to be the most effective inducer, with the production of larger phytochelatins (PC3-4). This study is the first one to report changes in thiol content in periphyton in response to an increase of the metal concentration in natural freshwaters. PMID:16295881

  20. Investigating the Temporal Effects of Metal-Based Coagulants to Remove Mercury from Solution in the Presence of Dissolved Organic Matter

    NASA Astrophysics Data System (ADS)

    Henneberry, Yumiko; Kraus, Tamara E. C.; Krabbenhoft, David P.; Horwath, William R.

    2016-01-01

    The presence of mercury (Hg), particularly methylmercury (MeHg), is a concern for both human and ecological health as MeHg is a neurotoxin and can bioaccumulate to lethal levels in upper trophic level organisms. Recent research has demonstrated that coagulation with metal-based salts can effectively remove both inorganic mercury (IHg) and MeHg from solution through association with dissolved organic matter (DOM) and subsequent flocculation and precipitation. In this study, we sought to further examine interactions between Hg and DOM and the resulting organo-metallic precipitate (floc) to assess if (1) newly added IHg could be removed to the same extent as ambient IHg or whether the association between IHg and DOM requires time, and (2) once formed, if the floc has the capacity to remove additional Hg from solution. Agricultural drainage water samples containing ambient concentrations of both DOM and IHg were spiked with a traceable amount of isotopically enriched IHg and dosed with ferric sulfate after 0, 1, 5, and 30 days. Both ambient and newly added IHg were removed within hours, with 69-79 % removed. To a separate sample set, isotopically enriched IHg was added to solution after floc had formed. Under those conditions, 81-95 % of newly added Hg was removed even at Hg concentrations 1000-fold higher than ambient levels. Results of this study indicate coagulation with ferric sulfate effectively removes both ambient and newly added IHg entering a system and suggests rapid association between IHg and DOM. This work also provides new information regarding the ability of floc to remove additional Hg from solution even after it has formed.

  1. Investigating the temporal effects of metal-based coagulants to remove mercury from solution in the presence of dissolved organic matter

    USGS Publications Warehouse

    Henneberry, Yumiko K.; Kraus, Tamara; Krabbenhoft, David P.; Horwath, William R.

    2015-01-01

    The presence of mercury (Hg), particularly methylmercury (MeHg), is a concern for both human and ecological health as MeHg is a neurotoxin and can bioaccumulate to lethal levels in upper trophic level organisms. Recent research has demonstrated that coagulation with metal-based salts can effectively remove both inorganic mercury (IHg) and MeHg from solution through association with dissolved organic matter (DOM) and subsequent flocculation and precipitation. In this study, we sought to further examine interactions between Hg and DOM and the resulting organo-metallic precipitate (floc) to assess if (1) newly added IHg could be removed to the same extent as ambient IHg or whether the association between IHg and DOM requires time, and (2) once formed, if the floc has the capacity to remove additional Hg from solution. Agricultural drainage water samples containing ambient concentrations of both DOM and IHg were spiked with a traceable amount of isotopically enriched IHg and dosed with ferric sulfate after 0, 1, 5, and 30 days. Both ambient and newly added IHg were removed within hours, with 69–79 % removed. To a separate sample set, isotopically enriched IHg was added to solution after floc had formed. Under those conditions, 81–95 % of newly added Hg was removed even at Hg concentrations 1000-fold higher than ambient levels. Results of this study indicate coagulation with ferric sulfate effectively removes both ambient and newly added IHg entering a system and suggests rapid association between IHg and DOM. This work also provides new information regarding the ability of floc to remove additional Hg from solution even after it has formed.

  2. Investigating the Temporal Effects of Metal-Based Coagulants to Remove Mercury from Solution in the Presence of Dissolved Organic Matter.

    PubMed

    Henneberry, Yumiko; Kraus, Tamara E C; Krabbenhoft, David P; Horwath, William R

    2016-01-01

    The presence of mercury (Hg), particularly methylmercury (MeHg), is a concern for both human and ecological health as MeHg is a neurotoxin and can bioaccumulate to lethal levels in upper trophic level organisms. Recent research has demonstrated that coagulation with metal-based salts can effectively remove both inorganic mercury (IHg) and MeHg from solution through association with dissolved organic matter (DOM) and subsequent flocculation and precipitation. In this study, we sought to further examine interactions between Hg and DOM and the resulting organo-metallic precipitate (floc) to assess if (1) newly added IHg could be removed to the same extent as ambient IHg or whether the association between IHg and DOM requires time, and (2) once formed, if the floc has the capacity to remove additional Hg from solution. Agricultural drainage water samples containing ambient concentrations of both DOM and IHg were spiked with a traceable amount of isotopically enriched IHg and dosed with ferric sulfate after 0, 1, 5, and 30 days. Both ambient and newly added IHg were removed within hours, with 69-79 % removed. To a separate sample set, isotopically enriched IHg was added to solution after floc had formed. Under those conditions, 81-95 % of newly added Hg was removed even at Hg concentrations 1000-fold higher than ambient levels. Results of this study indicate coagulation with ferric sulfate effectively removes both ambient and newly added IHg entering a system and suggests rapid association between IHg and DOM. This work also provides new information regarding the ability of floc to remove additional Hg from solution even after it has formed.

  3. Placental Metal Concentrations in Relation to Maternal and Infant Toenails in a U.S. Cohort.

    PubMed

    Punshon, Tracy; Li, Zhigang; Marsit, Carmen J; Jackson, Brian P; Baker, Emily R; Karagas, Margaret R

    2016-02-01

    Metal contaminants cross the placenta, presenting a heightened risk of perturbing fetal development. Information about placental concentrations and transfer of multiple potentially toxic metals from low to moderate exposure is lacking. We measured concentrations of Cd, Pb, Hg, Mn, Se, and Zn in 750 placentas collected from women enrolled in the New Hampshire Birth Cohort Study and examined the correlation between elements, and profiles of potentially toxic metals (Cd, Pb, Hg, and Mn) stratified by nutrient concentrations (Zn and Se) using principal components analyses. We further examined the indirect effects of maternal metal concentrations on infant metal concentrations through placental metal concentrations using structural equation models. Placental metal concentrations were all correlated, particularly Zn and Mn, and Zn and Cd, and the principal component of metals differed by stratum of high versus low Zn and Se. Associations were observed between placenta and maternal toenail Se (β = 63.49; P < 0.0001) and Pb (β = 0.90; P < 0.0001) but not other metals. Structural equation models did not indicate any statistically significant indirect effects through placental metal concentrations. Placental metal concentrations may represent a distinct biomarker of metal exposure and adverse health impacts to the fetus, particularly those stemming from the placenta. PMID:26727403

  4. Metal sorption on soils as affected by the dissolved organic matter in sewage sludge and the relative calculation of sewage sludge application.

    PubMed

    Liu, Xiaoli; Zhang, Shuzhen; Wu, Wenyong; Liu, Honglu

    2007-10-22

    To evaluate the influences of sewage sludge-derived organic matters on metal sorption and on the resultant sludge loading estimates, a batch experiment was conducted to compare the sorption of Ni, Cu and Pb in sewage sludge filtrates (1:20 sewage sludge to water) on eight soils and the adsorption of metals in a reference solution which had the same matrix as the sewage sludge filtrate except dissolved organic material (henceforth referred to as reference solution). Metal sorption could be well fitted by linear isotherm and the dissolved organic matter in sludge significantly depressed the sorption (p<0.01). The main factor controlling sorption of Ni on different soils was dominated by soil cation exchange capacity (CEC) and sorption of Cu and Pb was by soil organic matter (SOM). The parameters obtained from the sorption isotherm equations were then used to estimate sludge loadings into the soils. When the sorption parameters derived from the reference solution were used for calculation, that is the effect of dissolved organic matter was not considered, the calculated safe application rates are approximately 47.8, 51.4, 34.2, 31.3, 21.7, 46.3, 187.1 and 27.6 t-sludge/ha for the Beijing, Jiangxi, Xiamen, Jilin, Guangdong, Wuhan, Gansu and Xinjiang soils, respectively. However, when the sorption parameters derived from the dissolved organo-metallic complexes are used for calculation, the corresponding application rates are reduced to approximately 6.0, 3.4, 1.9, 10.0, 6.3, 3.6, 7.3 and 3.5 t-sludge/ha, respectively. By this study we can get a conclusion that the effect of sewage sludge derived dissolved organic matter on heavy metal sorption and soil properties should be considered in the course of regulating the safe application rates of sewage sludge to soil.

  5. Characterizing the production and retention of dissolved iron as Fe(II) across a natural gradient in chlorophyll concentrations in the Southern Drake Passage - Final Technical Report

    SciTech Connect

    Katherine Barbeau

    2007-04-10

    . As a co-PI in the NSF/OPP-funded project, I was responsible for iron addition incubation and radiotracer experiments, and analysis of iron chemistry, including iron-organic speciation. This final technical report describes the results of my DOE funded project to analyse reduced iron species using an FeLume flow injection analysis chemiluminescence system as an extension of my work on the NSF/OPP project. On the cruise in 2004, spatial and temporal gradients in Fe(II) were determined, and on-board incubations were conducted to study Fe(II) lifetime and production. Following the cruise a further series of experiments was conducted in my laboratory to study Fe(II) lifetimes and photoproduction under conditions typical of high latitude waters. The findings of this study suggest that, in contrast to results observed during mesoscale iron addition experiments, steady-state levels of Fe(II) are likely to remain low (below detection) even within a significant gradient in dissolved Fe concentrations produced as a result of natural iron enrichment processes. Fe(II) is likely to be produced, however, as a reactive intermediate associated with photochemical reactions in surface waters. While Fe(II) lifetimes measured in the field in this study were commensurate with those determined in previously published Southern Ocean work, Fe(II) lifetimes reflective of realistic Southern Ocean environmental conditions have proven difficult to determine in a laboratory setting, due to contamination by trace levels of H2O2. Laboratory experiments demonstrated that direct ligand-to-metal charge transfer reactions of strong Fe(III)-organic complexes do appear to be a viable source of available Fe(II) in Antarctic waters, and further studies are needed to characterize the temperature dependence of this phenomenon.

  6. Viral Lysis of Cells Influences The Concentration and Compostion of Dissolved Organic Matter and The Formation of Organic Aggregates (marine Snow)

    NASA Astrophysics Data System (ADS)

    Weinbauer, M. G.; Peduzzi, P.

    The effect of moderately (ca. 2.5 fold) increasing the concentration of the virus-size fraction (VSF) of seawater on the chemical composition of the dissolved organic mat- ter (DOM) pool during the formation of organic aggregates (marine snow) was tested experimentally with seawater samples collected in the Northern Adriatic Sea. The VSF enrichment did not significantly change the concentration of selected DOM com- pounds, whereas viral abundance was ca. 2-fold higher. During long-term experiments (40 - 200 hrs), bacterial abundance was on average 25% lower in the VSF amended than in the control incubations, and the frequency of visibly infected cells was stimu- lated by ca. 50%. VSF delayed the development of phytoplankton blooms (diatoms), but in the end of the experiments, Chl a concentrations in the VSF amended incuba- tions exceeded those in the control incubations. The VSF enrichment caused an enrich- ment of Serine and Threonine in the dissolved hydrolysable amino acid (AA) fraction indicative of viral lysis of diatoms. Bulk dissolved free AA acid and monomeric car- bohydrate (CHO) concentrations were repressed, whereas bulk dissolved hydrolysable AA and CHO concentrations were stimulated in the VSF enriched incubations. Viral lysis was likely the major reason for the stimulation of hydrolysable DOM. The for- mation of organic aggregates was repressed by the VSF enrichment, but the aggregates were larger and more persistent in the VSF amended than in the control incubations. Stimulation of hydrolysable DOM and sticky viral lysis products might be the reason for the larger and more persistent aggregates. This demonstrates that bioactive mate- rial in the VSF of seawater can have major implications for primary production and the cycling of organic carbon in the ocean.

  7. Land Use Controls on Stream and Lake Dissolved Silica Concentrations: A Case Study from the Finger Lakes, Central New York State, USA.

    NASA Astrophysics Data System (ADS)

    Halfman, J. D.

    2014-12-01

    Bedrock geology, climate and time are important controls on chemical weathering and release of dissolved silica. Forested land vs. other land uses was recently hypothesized as another control. The Finger Lakes region is an ideal natural laboratory to test this hypothesis as local watersheds vary in area, bedrock and agricultural to forested land cover in this rural setting. Annual mean dissolved silica data from 11 watersheds in our ongoing monitoring program ranged from 100 to 4,000 μg/L Si, analyzing filtered (0.45 μm) samples by spectrophotometer (molybdate indicator with metol/oxalic acid reagents). Like earlier work, only forested land use (12 to 73%) correlated to the mean silica concentrations (r2 = 0.3), which improves (r2 = 0.6) when a small, primarily (24%) developed watershed is excluded from the correlation. Bedrock (Devonian carbonates, 0 to 8% and clastics, 0 to 99% covered by till) and basin area (10 to 500 km2) did not correlate (r2 <= 0.1). Event and base flow samples of an agricultural (64%) watershed revealed peak to base flow fluctuations in silica concentrations that more closely mimic nitrates and other groundwater solutes than suspended particles, phosphates and other runoff signature parameters. Annual mean epilimnion and hypolimnion dissolved silica data from the 8 easternmost Finger Lakes in our ongoing monitoring program ranged from 250 to 1,500 μg/L Si. Forested cover (30 to 75%) positively correlated to epilimnion silica concentrations (r2 = 0.6). Lake water residence time (1 to 17 yr) negatively correlated to hypolimnion silica concentrations (r2 = 0.5). Agricultural land use, bedrock, and productivity indicators (chlorophyll-a, total phosphate, and secchi disk depth) lacked correlation (r2 <= 0.1). It suggested that land use impacts stream and, surprisingly, lake dissolved silica chemistry. Biogeochemical processes in the lakes like diatom uptake appears to increasingly decrease silica concentrations in lakes with longer residence

  8. Application of a novel sampling bailer device for the analysis of dissolved methane concentrations in municipal wastewater during and following anaerobic treatment.

    PubMed

    Beale, David J; Muster, Tim H; Low, Jason; Trickey, Mark

    2016-01-01

    Modern wastewater utilities need to be able to measure and quantify the amount of methane from their treatment facilities in order to understand the potential energy that can be produced and the amount of methane being lost. This paper describes the application of a novel sampling bailer designed for the collection of wastewater samples that minimises methane losses. Samples collected during and following anaerobic treatment from a wastewater treatment plant using a novel sampling bailer were analysed using a previously optimised analytical method. Analysis of wastewater and anaerobic pond samples using current industry approaches resulted in dissolved methane concentrations ranging from 0.01 to 14.33 mg L(-1). In comparison, the modified sampling protocol resulted in concentrations ranging from 0.08 to 18.73 mg L(-1). The relative standard deviations (RSD%) of low level spikes (5.0 mg L(-1) and 0.1 mg L(-1) methane; n = 5) were found to be 2.3 and 10.3, respectively. Statistical analysis of the dissolved methane concentrations using the two different approaches demonstrated a significant difference in the recovered dissolved methane concentrations, indicating there is a greater methane recovery potential in wastewater treatment plants than previously realised, when collected using the novel sampling bailer and analysed following the optimised analytical protocol. PMID:27332839

  9. Application of a novel sampling bailer device for the analysis of dissolved methane concentrations in municipal wastewater during and following anaerobic treatment.

    PubMed

    Beale, David J; Muster, Tim H; Low, Jason; Trickey, Mark

    2016-01-01

    Modern wastewater utilities need to be able to measure and quantify the amount of methane from their treatment facilities in order to understand the potential energy that can be produced and the amount of methane being lost. This paper describes the application of a novel sampling bailer designed for the collection of wastewater samples that minimises methane losses. Samples collected during and following anaerobic treatment from a wastewater treatment plant using a novel sampling bailer were analysed using a previously optimised analytical method. Analysis of wastewater and anaerobic pond samples using current industry approaches resulted in dissolved methane concentrations ranging from 0.01 to 14.33 mg L(-1). In comparison, the modified sampling protocol resulted in concentrations ranging from 0.08 to 18.73 mg L(-1). The relative standard deviations (RSD%) of low level spikes (5.0 mg L(-1) and 0.1 mg L(-1) methane; n = 5) were found to be 2.3 and 10.3, respectively. Statistical analysis of the dissolved methane concentrations using the two different approaches demonstrated a significant difference in the recovered dissolved methane concentrations, indicating there is a greater methane recovery potential in wastewater treatment plants than previously realised, when collected using the novel sampling bailer and analysed following the optimised analytical protocol.

  10. Blood metals concentration in type 1 and type 2 diabetics.

    PubMed

    Forte, Giovanni; Bocca, Beatrice; Peruzzu, Angela; Tolu, Francesco; Asara, Yolande; Farace, Cristiano; Oggiano, Riccardo; Madeddu, Roberto

    2013-12-01

    Mechanisms for the onset of diabetes and the development of diabetic complications remain under extensive investigations. One of these mechanisms is abnormal homeostasis of metals, as either deficiency or excess of metals, can contribute to certain diabetic outcomes. Therefore, this paper will report the blood levels of chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), mercury (Hg), nickel (Ni), lead (Pb), selenium (Se), and zinc (Zn) in subjects with type 1 diabetes (n = 192, mean age 48.8 years, mean disease duration 20.6 years), type 2 diabetes (n = 68, mean age 68.4 years, mean disease duration 10.2 years), and in control subjects (n = 59, mean age 57.2 years), and discuss the results indicating their possible role in diabetes. The metal concentrations were measured by sector field inductively coupled plasma mass spectrometry after microwave-induced acid digestion of blood samples. The accuracy was checked using a blood-based certified reference material, and recoveries of all elements were in the range of 92-101 % of certified values. Type 1 diabetes was found to be associated with Cr (p = 0.02), Mn (p < 0.001), Ni (p < 0.001), Pb (p = 0.02), and Zn (p < 0.001) deficiency, and type 2 diabetes with Cr (p = 0.014), Mn (p < 0.001), and Ni (p < 0.001) deficiency. These deficiencies were appreciated also subdividing the understudied patients for gender and age groups. Furthermore, in type 1 diabetes, there was a positive correlation between Pb and age (p < 0.001, ρ = 0.400) and Pb and BMI (p < 0.001, ρ = 0.309), while a negative correlation between Fe and age (p = 0.002, ρ = -0.218). In type 2 diabetes, there was a negative correlation between Fe and age (p = 0.017, ρ = -0.294) and Fe and BMI (p = 0.026, ρ = -0.301). Thus, these elements may play a role in both forms of diabetes and combined mineral supplementations could have beneficial effects. PMID:24222606

  11. Predicting the toxicity of sediment-associated trace metals with simultaneously extracted trace metal: Acid-volatile sulfide concentrations and dry weight-normalized concentrations: A critical comparison

    USGS Publications Warehouse

    Long, E.R.; MacDonald, D.D.; Cubbage, J.C.; Ingersoll, C.G.

    1998-01-01

    The relative abilities of sediment concentrations of simultaneously extracted trace metal: acid-volatile sulfide (SEM:AVS) and dry weight- normalized trace metals to correctly predict both toxicity and nontoxicity were compared by analysis of 77 field-collected samples. Relative to the SEM:AVS concentrations, sediment guidelines based upon dry weight-normalized concentrations were equally or slightly more accurate in predicting both nontoxic and toxic results in laboratory tests.

  12. Leaching of chloride, sulphate, heavy metals, dissolved organic carbon and phenolic organic pesticides from contaminated concrete.

    PubMed

    Van Praagh, M; Modin, H

    2016-10-01

    Concrete samples from demolition waste of a former pesticide plant in Sweden were analysed for total contents and leachate concentrations of potentially hazardous inorganic substances, TOC, phenols, as well as for pesticide compounds such as phenoxy acids, chlorophenols and chlorocresols. Leachates were produced by means of modified standard column leaching tests and pH-stat batch tests. Due to elevated contents of chromium and lead, as well as due to high chloride concentrations in the first leachate from column tests at L/S 0.1, recycling of the concrete as a construction material in groundworks is likely to be restricted according to Swedish guidelines. The studied pesticide compounds appear to be relatively mobile at the materials own pH>12, 12, 9 and 7. Potential leaching of pesticide residues from recycled concrete to ground water and surface water might exceed water quality guidelines for the remediation site and the EU Water Framework Directive. Results of this study stress the necessity to systematically study the mechanism behind mobility of organic contaminants from alkaline construction and demolition wastes rather than rely on total content limit values.

  13. Leaching of chloride, sulphate, heavy metals, dissolved organic carbon and phenolic organic pesticides from contaminated concrete.

    PubMed

    Van Praagh, M; Modin, H

    2016-10-01

    Concrete samples from demolition waste of a former pesticide plant in Sweden were analysed for total contents and leachate concentrations of potentially hazardous inorganic substances, TOC, phenols, as well as for pesticide compounds such as phenoxy acids, chlorophenols and chlorocresols. Leachates were produced by means of modified standard column leaching tests and pH-stat batch tests. Due to elevated contents of chromium and lead, as well as due to high chloride concentrations in the first leachate from column tests at L/S 0.1, recycling of the concrete as a construction material in groundworks is likely to be restricted according to Swedish guidelines. The studied pesticide compounds appear to be relatively mobile at the materials own pH>12, 12, 9 and 7. Potential leaching of pesticide residues from recycled concrete to ground water and surface water might exceed water quality guidelines for the remediation site and the EU Water Framework Directive. Results of this study stress the necessity to systematically study the mechanism behind mobility of organic contaminants from alkaline construction and demolition wastes rather than rely on total content limit values. PMID:27449537

  14. Impact of minimum daily dissolved oxygen concentration on production performance of hybrid female channel catfish x male blue catfish

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hybrid Catfish (female Channel Catfish Ictalurus punctatus X male Blue Catfish I. furcatus) were reared during two years as single-batch crops under two different dissolved oxygen (DO) regimes each year; a high-DO (control) treatment in which the minimum daily DO was maintained above 3.8 ppm during ...

  15. Reusable chelating resins concentrate metal ions from highly dilute solutions

    NASA Technical Reports Server (NTRS)

    Bauman, A. J.; Weetal, H. H.; Weliky, N.

    1966-01-01

    Column chromatographic method uses new metal chelating resins for recovering heavy-metal ions from highly dilute solutions. The absorbed heavy-metal cations may be removed from the chelating resins by acid or base washes. The resins are reusable after the washes are completed.

  16. Role of hydrous iron oxide formation in attenuation and diel cycling of dissolved trace metals in a stream affected by acid rock drainage

    USGS Publications Warehouse

    Parker, S.R.; Gammons, C.H.; Jones, C.A.; Nimick, D.A.

    2007-01-01

    Mining-impacted streams have been shown to undergo diel (24-h) fluctuations in concentrations of major and trace elements. Fisher Creek in south-central Montana, USA receives acid rock drainage (ARD) from natural and mining-related sources. A previous diel field study found substantial changes in dissolved metal concentrations at three sites with differing pH regimes during a 24-h period in August 2002. The current work discusses follow-up field sampling of Fisher Creek as well as field and laboratory experiments that examine in greater detail the underlying processes involved in the observed diel concentration changes. The field experiments employed in-stream chambers that were either transparent or opaque to light, filled with stream water and sediment (cobbles coated with hydrous Fe and Al oxides), and placed in the stream to maintain the same temperature. Three sets of laboratory experiments were performed: (1) equilibration of a Cu(II) and Zn(II) containing solution with Fisher Creek stream sediment at pH 6.9 and different temperatures; (2) titration of Fisher Creek water from pH 3.1 to 7 under four different isothermal conditions; and (3) analysis of the effects of temperature on the interaction of an Fe(II) containing solution with Fisher Creek stream sediment under non-oxidizing conditions. Results of these studies are consistent with a model in which Cu, Fe(II), and to a lesser extent Zn, are adsorbed or co-precipitated with hydrous Fe and Al oxides as the pH of Fisher Creek increases from 5.3 to 7.0. The extent of metal attenuation is strongly temperature-dependent, being more pronounced in warm vs. cold water. Furthermore, the sorption/co-precipitation process is shown to be irreversible; once the Cu, Zn, and Fe(II) are removed from solution in warm water, a decrease in temperature does not release the metals back to the water column. ?? 2006 Springer Science+Business Media B.V.

  17. Sources and concentrations of dissolved solids and selenium in the San Joaquin River and its tributaries, California, October 1985 to March 1987

    SciTech Connect

    Clifton, D.G.; Gilliom, R.J.

    1989-01-01

    Sources and concentrations of dissolved solids and selenium in the San Joaquin River and its tributaries, California, were assessed by a mass-balance approach to determine the effects of tile-drain water and irrigation-return flows on the river. The study included low-flow periods from October 1985 to mid-February 1986 and mid-May 1986 through March 1987, and a high-flow period from mid-February to mid-May 1985. During the combined low-flow period, the dissolved-solids load from eastside tributaries and the upper San Joaquin River accounted for only 18% of the total load at Vernalis, located farthest downstream, even though they accounted for 71% of the stream flow. Salt and Mud Sloughs contributed 40% of the dissolved-solids load but only 9% of stream flow. Unmeasured sources of dissolved solids contributed about 42% of the total load during low flow. In contrast, Salt and Mud Sloughs, which receive most of the tile-drain water that enters the river, contributed almost 80% of the total selenium load to the river, and loading of selenium concentrations were highest in Salt and Mud Sloughs and decreased downstream in the San Joaquin River with dilution from eastside tributaries. A State standard for dissolved solids of 500 mg/L was exceeded 11% of the time in the San Joaquin River at Vernalis. The US Environmental Protection Agency's 4-day average aquatic-life criterion of 5 micrograms/L of selenium was exceeded in more than 60% of the samples from the sloughs and in about 20% of the samples from the San Joaquin River, just downstream of the Merced River. 23 refs., 8 figs., 6 tabs.

  18. Metal concentrations in demersal fish species from Santa Maria Bay, Baja California Sur, Mexico (Pacific coast).

    PubMed

    Jonathan, M P; Aurioles-Gamboa, David; Villegas, Lorena Elizabeth Campos; Bohórquez-Herrera, Jimena; Hernández-Camacho, Claudia J; Sujitha, S B

    2015-10-15

    Concentrations of 11 trace metals (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd, As, Hg) in 40 fish species from Santa Maria Bay, Baja California Sur, Mexico, the strategically important area for marine mammals and organisms were analyzed. Based on their concentrations the ranking of metals Fe>Zn>Ni>Cr>Mn>Pb>Cu>Co>As>Cd>Hg suggests that organism size, metabolism and feeding habits are correlated with metal concentrations. Local geological formations affect the concentrations of different metals in the aquatic environment and are subsequently transferred to fishes. The correlation analysis suggests that metabolism and nurturing habits impact the concentration of metals. Concentrations of Fe and Mn appear to be influenced by scavenging and absorption processes, which vary by species. The considerable variability in the metal concentrations obtained in different species underscores the importance of regular monitoring.

  19. Influence of acid volatile sulfide and metal concentrations on metal bioavailability to marine invertebrates in contaminated sediments

    USGS Publications Warehouse

    Lee, B.-G.; Lee, J.-S.; Luoma, S.N.; Choi, H.J.; Koh, C.-H.

    2000-01-01

    An 18-day microcosm study was conducted to evaluate the influence of acid volatile sulfides (AVS) and metal additions on bioaccumulation from sediments of Cd, Ni, and Zn in two clams (Macoma balthica and Potamocorbula amurensis) and three marine polychaetes (Neanthes arenaceodentata, Heteromastus filiformis, and Spiophanes missionensis). Manipulation of AVS by oxidation of naturally anoxic sediments allowed use of metal concentrations typical of nature and evaluation of processes important to chronic metal exposure. A vertical sediment column similar to that often found in nature was used to facilitate realistic biological behavior. Results showed that AVS or porewater (PW) metals controlled bioaccumulation in only 2 of 15 metal-animal combinations. Bioaccumulation of all three metals by the bivalves was related significantly to metal concentrations extracted from sediments (SEM) but not to [SEM - AVS] or PW metals. SEM predominantly influenced bioaccumulation of Ni and Zn in N. arenaceodentata, but Cd bioaccumulation followed PW Cd concentrations. SEM controlled tissue concentrations of all three metals in H. filiformis and S. missionensis, with minor influences from metal-sulfide chemistry. Significant bioaccumulation occurred when SEM was only a small fraction of AVS in several treatments. Three factors appeared to contribute to the differences between these bioaccumulation results and the results from toxicity tests reported previously: differences in experimental design, dietary uptake, and biological attributes of the species, including mode and depth of feeding.An 18-day microcosm study was conducted to evaluate the influence of acid volatile sulfides (AVS) and metal additions on bioaccumulation from sediments of Cd, Ni, and Zn in two clams (Macoma balthica and Potamocorbula amurensis) and three marine polychaetes (Neanthes arenaceodentata, Heteromastus filiformis, and Spiophanes missionensis). Manipulation of AVS by oxidation of naturally anoxic sediments

  20. The role of dissolved organic matter and its adsorption for the fate of heavy metals in clay-rich soil

    NASA Astrophysics Data System (ADS)

    Refaey, Yasser B.; Jansen, Boris; El-Shater, Abdel-Hamid; El-Haddad, Abdel-Aziz; Kalbitz, Karsten

    2014-05-01

    Heavy metals (HMs), due to their toxic and hazardous nature, are possibly the most widespread contaminants imposing a serious threat to human health. To find out the effect of dissolved organic matter (DOM) and soil constituents on the uptake of Cu, Ni, and Zn, batch adsorption experiments were conducted using five soils sampled from Egypt. Sorption data were interpreted in terms of the initial mass (IM) isotherm model. In all soils, for all metals and in all experiments, the majority of the HMs were immobilized on the solid phase. The addition of DOM and timing thereof was found to play a pivotal role in determining the affinity of the HMs for the solid phase. When DOM and HMs were added simultaneously, Cu affinity decreased in Fe-(hydr)oxide rich soils (by 7%) and increased in soils poor in Fe-(hydr)oxide (by 6-10%). When DOM was added first, followed by HMs in a later stage affinity of Cu strongly increased in most soils. In contrast, for both Ni and Zn the affinity to the solid phase was enhanced (3-18%) in presence of DOM regardless of whether the DOM was added simultaneously with or prior to HMs addition. The difference is explained by Cu binding to the solid phase and to DOM through strong inner-sphere complexes, whereas Ni and Zn interacted predominantly through weaker electrostatic interactions. As a result Cu was able to bind more strongly to previously adsorbed DOM on the solid phase in case of smectite, while this effect was counteracted by the coating of available specific binding sites on Fe-(hydr)oxides.

  1. Toxicity identification evaluation of metal-contaminated sediments using an artificial pore water containing dissolved organic carbons

    SciTech Connect

    Boucher, A.M.; Watzin, M.C.

    1999-03-01

    Recent investigations of sediment-associated pollutants in Lake Champlain indicated significant contamination with As, Mn, and Ni in Outer Malletts Bay, Vermont, US. Ceriodaphnia dubia exposed to sediment pore water from several sites in Outer Malletts Bay showed repeatable, acute mortality at only one site. A toxicity identification evaluation (TIE) was conducted on pore water to determine the contaminants causing mortality at this site. Unlike most TIE applications, the dilution water used in these tests was formulated to match the hardness, alkalinity, pH, conductivity, and dissolved organic carbon content of the pore water. Results from phase 1 of the TIE indicated that divalent metals may be responsible for toxicity. Phase 2 results revealed levels of Mn above LC50 values. Spiking experiments employed in phase 3 confirmed Mn as the principal toxicant in sediment pore water. The formulated pore water worked well and helped ensure that toxicant behavior was influenced primarily by each TIE manipulation and not by physical and chemical differences between the dilution and site water. Although the Mn toxicity at this site may be the result of its unique geomorphology, this situation underscores the need to look broadly for potential toxicants when evaluating contaminated sites.

  2. Influence of dissolved organic matter and manganese oxides on metal speciation in soil solution: A modelling approach.

    PubMed

    Schneider, Arnaud R; Ponthieu, Marie; Cancès, Benjamin; Conreux, Alexandra; Morvan, Xavier; Gommeaux, Maxime; Marin, Béatrice; Benedetti, Marc F

    2016-06-01

    Trace element (TE) speciation modelling in soil solution is controlled by the assumptions made about the soil solution composition. To evaluate this influence, different assumptions using Visual MINTEQ were tested and compared to measurements of free TE concentrations. The soil column Donnan membrane technique (SC-DMT) was used to estimate the free TE (Cd, Cu, Ni, Pb and Zn) concentrations in six acidic soil solutions. A batch technique using DAX-8 resin was used to fractionate the dissolved organic matter (DOM) into four fractions: humic acids (HA), fulvic acids (FA), hydrophilic acids (Hy) and hydrophobic neutral organic matter (HON). To model TE speciation, particular attention was focused on the hydrous manganese oxides (HMO) and the Hy fraction, ligands not considered in most of the TE speciation modelling studies in soil solution. In this work, the model predictions of free ion activities agree with the experimental results. The knowledge of the FA fraction seems to be very useful, especially in the case of high DOM content, for more accurately representing experimental data. Finally, the role of the manganese oxides and of the Hy fraction on TE speciation was identified and, depending on the physicochemical conditions of the soil solution, should be considered in future studies. PMID:27017138

  3. Risk assessment and seasonal variations of dissolved trace elements and heavy metals in the Upper Han River, China.

    PubMed

    Li, Siyue; Zhang, Quanfa

    2010-09-15

    Surface water samples were collected from 42 sampling sites throughout the upper Han River during the time period of 2005-2006. The concentrations of trace metals were determined using inductively coupled plasma-atomic emission spectrometry (ICP-AES) for the seasonal variability and preliminary risk assessment. The results demonstrated that concentrations of 11 heavy metals showed significant seasonality and most variables exhibited higher levels in the rainy season. Principal component analysis (PCA) and factor analysis (FA) revealed that variables governing water quality in one season may not be important in another season. Risk of metals on human health was then evaluated using Hazard Quotient (HQ) and carcinogenic risk, and indicated that As with HQ >1 and carcinogenic risk >10(-4), was the most important pollutant leading to non-carcinogenic and carcinogenic concerns, in particular for children. The first five largest elements to chronic risks were As, Pb, V, Se and Sb, in the dry season, while they were As, V, Co, Pb and Sb in the rainy season. This assessment would help establish pollutant loading reduction goal and the total maximum daily loads, and consequently contribute to preserve public health in the Han River basin and develop water conservation strategy for the interbasin water transfer project.

  4. Metal concentrations in Hydrocynus vittatus (Castelnau 1861) populations from a premier conservation area: Relationships with environmental concentrations.

    PubMed

    Gerber, Ruan; Smit, Nico J; van Vuren, Johan H J; Wepener, Victor

    2016-07-01

    Metals are known to have deleterious effects on aquatic ecosystems, so monitoring the bioaccumulation of these pollutants is important for the assessment of potential impacts. The aim of the study was therefore to determine the degree to which aquatic biota in selected rivers of the world renowned Kruger National Park (KNP) are exposed to metals entering from the catchments outside the KNP and to determine how these metal levels reflect what is occurring within the environment. Many of these rivers have never previously been assessed and those which have, have not been assessed within the past two decades. Tigerfish (Hydrocynus vittatus) is an economically important apex predator and was selected as the bioindicator for this study. Fish were sampled from the KNP sections of the Luvuvhu, Letaba and Olifants Rivers during the high and low flow periods from 2009 to 2011. The analysis of various metals from the aforementioned systems revealed spatial and temporal related variation in metal level patterns of the chosen bioindicator, with concentrations in fish from the Olifants River>Letaba River>Luvuvhu River and 2009>2010>2011. Although there were differences between rivers, metal concentrations were comparable and indicate that all of the studied KNP rivers, even those considered to be in a natural state are affected to some degree by anthropogenic activities. However, concentrations found during this study were much lower than previous studies in the area, as well as contaminated sites across the world, but were higher than concentrations in fish from contaminated sites in the Vaal River, South Africa. Bioaccumulated metals showed no correlation to metals in the water column, but some were correlated to sediment metal concentrations and the contamination and bioavailability of these metals within the sediments. This is of concern when managing the water resources of the conservation area since the contaminants enter the park from outside the borders and pose

  5. Metal accumulation and metallothionein concentrations in tree swallow nestlings near acidified lakes

    SciTech Connect

    St. Louis, V.; Breebaart, L. . Dept. of Zoology); Barlow, J.C. . Dept. of Zoology Royal Ontario Museum, Toronto, Ontario . Dept. of Ornithology); Klaverkamp, J.F. . Dept. of Fisheries and Oceans)

    1993-07-01

    The authors studied metal accumulation in hepatic and renal tissues of tree swallow (Tachycineta bicolor) nestlings at acidified and nonacid reference lakes in northwestern Ontario. Hepatic concentrations of metallothionein (metal-binding proteins, MT) in tree swallow nestlings were negatively correlated with pH of the nest-site lake. Combined concentrations of Cu and Zn in the liver were correlated with liver MT concentrations, but Cd was not. Although no overt signs of metal toxicity were observed in nestlings near acid lakes, the results clearly provided evidence that metals are transferred from acid lakes to birds and that these metals are correlated with increases in hepatic MT production.

  6. Heavy metal concentrations in earthworms from soil amended with sewage slude

    SciTech Connect

    Beyer, W.N.; Chaney, R.L.; Mulhern, B.M.

    1982-07-01

    Metal concentrations in soil may be elevated considerably when metal-laden sewage sludge is spread on land. Metals in earthworms (Lumbricidae) from agicultural fields amended with sewage sludge and from experimental plots were examined to determine if earthworms are important in transferring metals in soil to wildlife. Earthworms from four sites amended with sludge contained significantly (P<0.05) more Cd (12 times), Cu (2.4 times), Zn (2.0 times), and Pb (1.2 times) than did earthworms from control sites, but the concentrations detected varied greatly and depended on the particular sludge application. Generally, Cd and Zn were concentrated by earthworms relative to soil, and Cu, Pb, and Ni were not concentrated. Concentrations of Cd, Zn, Cu, and Pb in earthworms were correlated (P<0.05) with those in soil. The ratio of the concentration of metals in earthworms to the concentration of metals in soil tended to be lower in contaminated soil than in clean soil. Concentrations of Cd as high as 100 ppm (dry wt) were detected in earthworms from soil containing only 2 ppm Cd. These concentrations are considered hazardous to wildlife that eat worms. Liming soil decreased Cd concentrations in earthworms slightly (P<0.05) but had no discernible effect on concentrations of the other metals studied. High Zn concentrations in soil substantially reduced Cd concentrations in earthworms.

  7. Heavy metal concentrations in earthworms from soil amended with sewage sludge

    USGS Publications Warehouse

    Beyer, W.N.; Chaney, R.L.; Mulhern, B.M.

    1982-01-01

    Metal concentrations in soil may be elevated considerably when metal-laden sewage sludge is spread on land. Metals in earthworms (Lumbricidae) from agricultural fields amended with sewage sludge and from experimental plots were examined to determine if earthworms are important in transferring metals in soil to wildlife. Earthworms from four sites amended with sludge contained significantly (P . < 0.05) more Cd (12 times), Cu (2.4 times), Zn (2.0 times), and Pb (1.2 times) than did earthworms from control sites, but the concentrations detected varied greatly and depended on the particular sludge application. Generally, Cd and Zn were concentrated by earthworms relative to soil, and Cu, Pb, and Ni were not concentrated. Concentrations of Cd, Zn, Cu, and Pb in earthworms were correlated (P < 0.05) with those in soil. The ratio of the concentration of metals in earthworms to the concentration of metals in soil tended to be lower in contaminated soil than in clean soil. Concentrations of Cd as high as 100 ppm (dry wt) were detected in earthworms from soil containing only 2 ppm Cd. These concentrations are considered hazardous to wildlife that eat worms. Liming soil decreased Cd concentrations in earthworms slightly (P < 0.05) but had no discernible effect on concentrations of the other metals studied. High Zn concentrations in soil substantially reduced Cd concentrations in earthworms.

  8. Evaluation of metal biouptake from the analysis of bulk metal depletion kinetics at various cell concentrations: theory and application.

    PubMed

    Rotureau, Elise; Billard, Patrick; Duval, Jérôme F L

    2015-01-20

    Bioavailability of trace metals is a key parameter for assessment of toxicity on living organisms. Proper evaluation of metal bioavailability requires monitoring the various interfacial processes that control metal partitioning dynamics at the biointerface, which includes metal transport from solution to cell membrane, adsorption at the biosurface, internalization, and possible excretion. In this work, a methodology is proposed to quantitatively describe the dynamics of Cd(II) uptake by Pseudomonas putida. The analysis is based on the kinetic measurement of Cd(II) depletion from bulk solution at various initial cell concentrations using electroanalytical probes. On the basis of a recent formalism on the dynamics of metal uptake by complex biointerphases, the cell concentration-dependent depletion time scales and plateau values reached by metal concentrations at long exposure times (>3 h) are successfully rationalized in terms of limiting metal uptake flux, rate of excretion, and metal affinity to internalization sites. The analysis shows the limits of approximate depletion models valid in the extremes of high and weak metal affinities. The contribution of conductive diffusion transfer of metals from the solution to the cell membrane in governing the rate of Cd(II) uptake is further discussed on the basis of estimated resistances for metal membrane transfer and extracellular mass transport.

  9. Evaluation of metal biouptake from the analysis of bulk metal depletion kinetics at various cell concentrations: theory and application.

    PubMed

    Rotureau, Elise; Billard, Patrick; Duval, Jérôme F L

    2015-01-20

    Bioavailability of trace metals is a key parameter for assessment of toxicity on living organisms. Proper evaluation of metal bioavailability requires monitoring the various interfacial processes that control metal partitioning dynamics at the biointerface, which includes metal transport from solution to cell membrane, adsorption at the biosurface, internalization, and possible excretion. In this work, a methodology is proposed to quantitatively describe the dynamics of Cd(II) uptake by Pseudomonas putida. The analysis is based on the kinetic measurement of Cd(II) depletion from bulk solution at various initial cell concentrations using electroanalytical probes. On the basis of a recent formalism on the dynamics of metal uptake by complex biointerphases, the cell concentration-dependent depletion time scales and plateau values reached by metal concentrations at long exposure times (>3 h) are successfully rationalized in terms of limiting metal uptake flux, rate of excretion, and metal affinity to internalization sites. The analysis shows the limits of approximate depletion models valid in the extremes of high and weak metal affinities. The contribution of conductive diffusion transfer of metals from the solution to the cell membrane in governing the rate of Cd(II) uptake is further discussed on the basis of estimated resistances for metal membrane transfer and extracellular mass transport. PMID:25525993

  10. Passive treatment of acid mine drainage with high metal concentrations using dispersed alkaline substrate.

    PubMed

    Rötting, Tobias S; Thomas, Robert C; Ayora, Carlos; Carrera, Jesús

    2008-01-01

    Passive treatment systems based on the dissolution of coarse calcite grains are widely used to remediate acid mine drainage (AMD). Unfortunately, they tolerate only low metal concentrations or acidity loads, because they are prone to passivation (loss of reactivity due to coating) and/or clogging (loss of permeability) by precipitates. To overcome these problems, a dispersed alkaline substrate (DAS) composed of a fine-grained alkaline reagent (calcite sand) mixed with a coarse inert matrix (wood chips) was developed. The small grains provide a large reactive surface and dissolve almost completely before the growing layer of precipitates passivates the substrate, whereas the dispersion of nuclei for precipitation on the inert surfaces retards clogging. Chemical and hydraulic performance of DAS was investigated in two laboratory columns fed at different flow rates with natural AMD of pH 2.3 to 3.5 and inflow net acidity 1350 to 2300 mg/L as CaCO(3). The DAS columns removed 900 to 1600 mg/L net acidity, 3 to 4.5 times more than conventional passive treatment systems. Regardless of the flow rate employed, Al, Fe(III), Cu, and Pb were virtually eliminated. Minor Zn, Ni, and Cd were removed at low flow rates. High acidity removal is possible because these metals accumulate intentionally in DAS, and their precipitation promotes further calcite dissolution. During 15 mo, DAS operated without clogging at 120 g acidity/m(2).d, four times the loading rate recommended for conventional passive systems; DAS may therefore be capable of treating AMD at sites where influent chemistry precludes the use of other passive systems.

  11. Mercury dynamics in relation to dissolved organic carbon concentration and quality during high flow events in three northeastern U.S. streams

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

    Mercury (Hg) contamination is widespread in remote areas of the northeastern United States. Forested uplands have accumulated a large reservoir of Hg in soil from decades of elevated anthropogenic deposition that can be released episodically to stream water during high flows. The objective of this study was to evaluate spatial and temporal variations in stream water Hg species and organic matter fractions over a range of hydrologic conditions in three forested upland watersheds (United States). Mercury and organic matter concentrations increased with discharge at all three sites; however, the partitioning of Hg fractions (dissolved versus particulate) differed among sites and seasons. Associated with increased discharge, flow paths shifted from mineral soil under base flow to upper soil horizons. As flow paths shifted, greater concentrations of dissolved organic carbon (DOC) richer in aromatic substances were flushed from upper soil horizons to stream water. The hydrophobic organic matter associated with humic material from upper soils appears to have had a greater capacity to bind Hg. Because of the strong correlation between Hg and DOC, we hypothesize that there was a concurrent shift in the source of Hg with DOC from lower mineral soil to upper soil horizons. Our study suggests that stream discharge is an effective predictor of dissolved total Hg flux.

  12. Influence of domestic pets on soil concentrations of dissolved organic carbon, nitrogen, and phosphorus under turfgrass in apartment complexes of Central Texas, USA

    NASA Astrophysics Data System (ADS)

    Steele, M.; Aitkenhead-Peterson, J. A.

    2009-12-01

    High nitrogen (N) and phosphorus (P) watershed loading rates increases the concentration and loads present in urban streams and rivers, resulting in eutrophication and degradation of surface water quality. Domestic pet animal feed may represent a significant proportion of nitrogen loading in urban watersheds, and because it is deposited directly on the watershed surface may have a large effect on N loads in urban surface waters (Baker et al. 2001). Animal manure has long been used to increase soil N and phosphorus concentrations for the purpose of growing agricultural crops; however, little is known about unintentional urban manuring resulting from a high density of domesticated pets. The purpose of this study is to determine if the presence of domesticated animals in high density urban developments results in increased concentrations of soil dissolved organic carbon (DOC), N, and P and the potential to contribute to loading of urban streams. Composite soil samples from the 0 to 5 cm and 5 to 10 cm soil depth were collected from apartment complexes in Bryan/College Station (BCS) and San Antonio, Texas during August, 2009. Apartment complexes were randomly located around the city and were chosen based on their rules regarding pet ownership. Four apartment complexes that allowed all domestic pets were compared to four that did not allow any domestic pets on the property. A 10:1 water extraction of field moist soil was conducted immediately after sampling. Soil water extracts were analyzed for DOC, total dissolved nitrogen (TDN), nitrate-N, ammonium-N, dissolved organic N, and orthophosphate-P. Results indicated significantly increased concentrations of DOC and N species at both depths in BCS apartments that allowed pets compared to those that did not; however, opposite trends were found in San Antonio. There is a trend for increased concentrations of orthophosphate-P at both locations. Baker, L.A., D. Hope, Y. Xu, et al. 2001. Nitrogen balance for the central Arizona

  13. A novel method of non-violent dissolution of sodium metal in a concentrated aqueous solution of Epsom salt

    NASA Astrophysics Data System (ADS)

    Lakshmanan, A. R.; Prasad, M. V. R.; Ponraju, D.; Krishnan, H.

    2004-10-01

    A new technique of non-violent and fast dissolution of sodium metal in a concentrated aqueous solution of Epsom salt (MgSO4.7H2O) at room temperature (RT) has been developed. The dissolution process is mildly exothermic but could be carried out even in a glass beaker in air under swift stirring condition. The reaction products consist of mixed salts of MgSO4 and Na2SO4 as well as Mg(OH)2 which are only mildly alkaline and hence are non-corrosive and non-hazardous unlike NaOH. A 50 mL solution having Epsom salt concentration of 2 M was found to give the optimal composition for disposal of 1 g of sodium. Supersaturated (>2.7 M), as well as dilute (<1.1 M) solutions, however, cause violent reactions and hence should be avoided. Repeated sodium dissolution in Epsom solution produced a solid waste of 4.7 g per g of sodium dissolved which is comparable with the waste (4 g) produced in 8 M NaOH solution. A 1.4 M Epsom solution sprayed with a high-pressure jet cleaner at RT in air easily removed the sodium blocked inside a metal pipe made of mild steel. The above jet also dissolved peacefully residual sodium collected on the metal tray after a sodium fire experiment. No sodium fire or explosion was observed during this campaign. The Epsom solution spray effectively neutralized the minor quantity of sodium aerosol produced during this campaign. This novel technique would hence be quite useful for draining sodium from fast breeder reactor components and bulk processing of sodium as well as for sodium fire fighting.

  14. Maternal exposure to alkali, alkali earth, transition and other metals: Concentrations and predictors of exposure.

    PubMed

    Hinwood, A L; Stasinska, A; Callan, A C; Heyworth, J; Ramalingam, M; Boyce, M; McCafferty, P; Odland, J Ø

    2015-09-01

    Most studies of metals exposure focus on the heavy metals. There are many other metals (the transition, alkali and alkaline earth metals in particular) in common use in electronics, defense industries, emitted via combustion and which are naturally present in the environment, that have received limited attention in terms of human exposure. We analysed samples of whole blood (172), urine (173) and drinking water (172) for antimony, beryllium, bismuth, cesium, gallium, rubidium, silver, strontium, thallium, thorium and vanadium using ICPMS. In general most metals concentrations were low and below the analytical limit of detection with some high concentrations observed. Few factors examined in regression models were shown to influence biological metals concentrations and explained little of the variation. Further study is required to establish the source of metals exposures at the high end of the ranges of concentrations measured and the potential for any adverse health impacts in children. PMID:25984984

  15. Maternal exposure to alkali, alkali earth, transition and other metals: Concentrations and predictors of exposure.

    PubMed

    Hinwood, A L; Stasinska, A; Callan, A C; Heyworth, J; Ramalingam, M; Boyce, M; McCafferty, P; Odland, J Ø

    2015-09-01

    Most studies of metals exposure focus on the heavy metals. There are many other metals (the transition, alkali and alkaline earth metals in particular) in common use in electronics, defense industries, emitted via combustion and which are naturally present in the environment, that have received limited attention in terms of human exposure. We analysed samples of whole blood (172), urine (173) and drinking water (172) for antimony, beryllium, bismuth, cesium, gallium, rubidium, silver, strontium, thallium, thorium and vanadium using ICPMS. In general most metals concentrations were low and below the analytical limit of detection with some high concentrations observed. Few factors examined in regression models were shown to influence biological metals concentrations and explained little of the variation. Further study is required to establish the source of metals exposures at the high end of the ranges of concentrations measured and the potential for any adverse health impacts in children.

  16. Background concentrations of metals in soils from selected regions in the State of Washington

    USGS Publications Warehouse

    Ames, K.C.; Prych, E.A.

    1995-01-01

    Soil samples from 60 sites in the State of Washington were collected and analyzed to determine the magnitude and variability of background concen- trations of metals in soils of the State. Samples were collected in areas that were relatively undisturbed by human activity from the most pre- dominant soils in 12 different regions that are representative of large areas of Washington State. Concentrations of metals were determined by five different laboratory methods. Concentrations of mercury and nickel determined by both the total and total-recoverable methods displayed the greatest variability, followed by chromium and copper determined by the total-recoverable method. Concentrations of other metals, such as aluminum and barium determined by the total method, varied less. Most metals concentrations were found to be more nearly log-normally than normally distributed. Total metals concentrations were not significantly different among the different regions. However, total-recoverable metals concentrations were not as similar among different regions. Cluster analysis revealed that sampling sites in three regions encompassing the Puget Sound could be regrouped to form two new regions and sites in three regions in south-central and southeastern Washington State could also be regrouped into two new regions. Concentrations for 7 of 11 total-recoverable metals correlated with total metals concentrations. Concen- trations of six total metals also correlated positively with organic carbon. Total-recoverable metals concentrations did not correlate with either organic carbon or particle size. Concentrations of metals determined by the leaching methods did not correlate with total or total-recoverable metals concentrations, nor did they correlate with organic carbon or particle size.

  17. Flow-adjusted trends in dissolved selenium load and concentration in the Gunnison and Colorado Rivers near Grand Junction, Colorado, water years 1986--2008

    USGS Publications Warehouse

    Mayo, John W.; Leib, Kenneth J.

    2012-01-01

    As a result of elevated selenium concentrations, many western Colorado rivers and streams are on the U.S. Environmental Protection Agency 2010 Colorado 303(d) list, including the main stem of the Colorado River from the Gunnison River confluence to the Utah border. Selenium is a trace metal that bioaccumulates in aquatic food chains and can cause reproductive failure, deformities, and other adverse impacts in birds and fish, including several threatened and endangered fish species. Salinity in the upper Colorado River has been the focus of source-control efforts for many years. Although salinity loads and concentrations have been previously characterized at the U.S. Geological Survey (USGS) streamflow-gaging stations at the Gunnison River near Grand Junction, Colo., and at the Colorado River near the Colorado-Utah State line, trends in selenium load and concentration at these two stations have not been studied. The USGS, in cooperation with the Bureau of Reclamation and the Colorado River Water Conservation District, evaluated dissolved selenium (herein referred to as "selenium") load and concentration trends at these two sites to inform decision makers on the status and trends of selenium. This report presents results of the evaluation of trends in selenium load and concentration for two USGS streamflow-gaging stations: the Gunnison River near Grand Junction, Colo. ("Gunnison River site"), USGS site 09152500, and the Colorado River near Colorado-Utah State line ("Colorado River site"), USGS site 09163500. Flow-adjusted selenium loads were estimated for the beginning water year (WY) of the study, 1986, and the ending WY of the study, 2008. The difference between flow-adjusted selenium loads for WY 1986 and WY 2008 was selected as the method of analysis because flow adjustment removes the natural variations in load caused by changes in mean-daily streamflow, emphasizing human-caused changes in selenium load and concentration. Overall changes in human-caused effects

  18. Metal concentrations in aquatic macrophytes as influenced by soil and acidification

    USGS Publications Warehouse

    Sparling, D.W.; Lowe, T.P.

    1998-01-01

    Bioavailability of metals to aquatic plants is dependent on many factors including ambient metal concentration, pH of soil or water, concentration of ligands, competition with other metals for binding sites, and mode of exposure. Plants may be exposed to metals through water, air, or soil, depending on growth form. This paper examines the influence of soil type under two regimens of water acidification on metal uptake by four species of aquatic macrophytes: smartweed (Polygonum sagittatum), burreed (Sparganium americanum), pondweed (Potamogeton diversifolius), and bladderwort (Utricularia vulgaris) in constructed, experimentally acidified wetlands. Soil types consisted of a comparatively high-metal clay or a lower-metal sandy loam. Each pond was either acidified to pH ca. 4.85.3 or allowed to remain circumneutral. Metal concentrations tended to be higher in the submerged bladderwort and pondweed than in the emergent burreed and smartweed. Soils were important to plant metal concentrations in all species, but especially in the emergents. Acidification influenced plant concentrations of some metals and was especially important in the submerged pondweed. Bioaccumulation of metals occurred for Mn, B, Sr, Ba, and Zn, compared to soil concentrations.

  19. Influence of pH, hardness, dissolved organic carbon concentration, and dissolved organic matter source on the acute toxicity of copper to Daphnia magna in soft waters: implications for the biotic ligand model.

    PubMed

    Ryan, Adam C; Tomasso, Joseph R; Klaine, Stephen J

    2009-08-01

    The influence of pH, dissolved organic carbon (DOC) concentration, water hardness, and dissolved organic matter (DOM) source on the acute toxicity of copper were investigated with standardized 48-h Daphnia magna toxicity tests. Toxicity tests were conducted according to a four-factor complete factorial design. Nominal factor levels were as follows: pH 6 and 8; DOC, 2.5 and 10 mg/L; hardness, 10, 20, and 40 mg/L as CaCO3; and two DOM sources (collected from the Black River and Edisto River, SC, USA). The experimental design resulted in 24 different factor level combinations. Results indicated that all factors had significant effects on copper toxicity. Furthermore, a strong interactive effect of DOC concentration and pH was detected. Because the biotic ligand model (BLM) has become a widely used tool for predicting toxicity and interpreting toxicity test results, its performance with these data was evaluated. Seventy percent of BLM predictions were within twofold of the observed median lethal concentrations. However, BLM parameters could be adjusted to improve model performance with this data set. This analysis suggested that in soft waters, the CuOH+ complex binds more strongly with the biotic ligand and that the competitive effect of hardness cations should be increased. The results of the present study may have implications for application of the BLM to some types of surface waters. Furthermore, a comprehensive analysis of BLM performance with all available data should be performed, and necessary updates to model parameters should be made to produce the most robust and widely applicable model.

  20. Long-term patterns in dissolved organic carbon, major elements and trace metals in boreal headwater catchments: trends, mechanisms and heterogeneity

    NASA Astrophysics Data System (ADS)

    Oni, S. K.; Futter, M. N.; Bishop, K.; Köhler, S. J.; Ottosson-Löfvenius, M.; Laudon, H.

    2013-04-01

    The boreal landscape is a complex, spatio-temporally varying mosaic of forest and mire landscape elements that control surface water hydrology and chemistry. Here, we assess long-term water quality time series from three nested headwater streams draining upland forest (C2), peat/mire (C4) and mixed (C7) (forest and mire) catchments. Acid deposition in this region is low and is further declining. Temporal trends in weather and runoff (1981-2008), dissolved organic carbon concentration [DOC] (1993-2010) and other water quality parameters (1987-2011) were assessed. There was no significant annual trend in precipitation or runoff. However, runoff increased in March and declined in May. This suggested an earlier snowmelt regime in recent years. Significant monotonic increasing trends in air temperature and length of growing season suggested a decrease in snowfall and less spring runoff. Stream [DOC] was positively correlated with some trace metals (copper, iron and zinc) and negatively with several other chemical parameters (e.g. sulfate, conductivity, calcium). Both sulfate and conductivity showed declining trends, while a significant increase was observed in pH during winter and spring. Calcium and magnesium showed monotonic decreasing trends. The declining trajectories of stream base cation and sulfate concentrations during other times of the year were not accompanied by changes in pH and alkalinity. These results indicate subtle effects of recovery from acidification. Water temperature increased significantly both annually and in most months. A simultaneous monotonic increase in iron (Fe) and [DOC] in autumn suggests co-transport of Fe-DOC in the form of organometallic complexes. A monotonic increase in UV absorbance in most months without co-occurring changes in DOC trend suggests a shift in DOC quality to a more humic-rich type. The observed increase in soil solution [DOC] and subtle trends in stream [DOC] suggest that climate rather than recovery from

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

    PubMed

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

    2015-01-01

    An extensive investigation of particulate radiocaesium in suspended solids and dissolved radiocaesium in river water was undertaken at 30 sites in Fukushima and Miyagi Prefectures in December 2012, and their relationships with catchment inventory and the solid/liquid distribution coefficient (Kd) were evaluated. Rivers located in the coastal region on the north side of the Fukushima Dai-ichi Nuclear Power Plant exhibited relatively higher particulate radiocaesium concentrations. Significant correlations were found between concentrations of particulate/dissolved radiocaesium and average catchment inventories, indicating that the concentrations of particulate/dissolved radiocaesium could be approximated from the catchment inventory. Particulate radiocaesium concentration was significantly correlated with dissolved radiocaesium concentration (with the exception of concentrations measured in estuaries), and the geometric mean Kd was calculated as 3.6 × 10(5) with a 95% confidence interval of 2.6-5.1 × 10(5). PMID:25242014

  2. Heavy metals in urban soils of East St. Louis, IL, Part I: Total concentration of heavy metals in soils.

    PubMed

    Kaminski, M D; Landsberger, S

    2000-09-01

    The city of East St. Louis, IL, has a history of abundant industrial activities including smelters of ferrous and non-ferrous metals, a coal-fired power plant, companies that produce organic and inorganic chemicals, and petroleum refineries. A protocol for soil analysis was developed to produce sufficient information on the extent of heavy metal contamination in East St. Louis soils. Soil cores representing every borough of East St. Louis were analyzed for heavy metals--As, Cd, Cu, Cr, Hg, Ni, Pb, Sb, Sn, and Zn. The topsoil contained heavy metal concentrations as high as 12.5 ppm Cd, 14,400 ppm Cu, ppm quantities of Hg, 1860 ppm Pb, 40 ppm Sb, 1130 ppm Sn, and 10,360 ppm Zn. Concentrations of Sb, Cu, and Cd were well correlated with Zn concentrations, suggesting a similar primary industrial source. In a sandy loam soil from a vacated rail depot near the bank of the Mississippi River, the metals were evenly distributed down to a 38-cm depth. The clay soils within a half-mile downwind of the Zn smelter and Cu products company contained elevated Cd (81 ppm), Cu (340 ppm), Pb (700 ppm), and Zn (6000 ppm) and displayed a systematic drop in concentration of these metals with depth. This study demonstrates the often high concentration of heavy metals heterogeneously distributed in the soil and provides baseline data for continuing studies of heavy metal soil leachability.

  3. Seasonal changes in concentrations of dissolved pesticides and organic carbon in the Sacramento-San Joaquin delta, California, 1994-1996

    USGS Publications Warehouse

    Orlando, James L.; Kuivila, Kathryn M.

    2006-01-01

    The Sacramento-San Joaquin Delta (Delta) of California is an ecologically rich and hydrologically complex region that receives runoff from nearly one-quarter of the state. Water-quality studies of surface water in the region have found dissolved pesticides in winter storm runoff at concentrations toxic to some aquatic invertebrates. However, scientists have little information on pesticide concentrations in the Delta on a seasonal timescale or the importance of pesticide contributions from within-Delta sources. Consequently, the U.S. Geological Survey conducted a study from 1994 to 1996 during which water samples were collected seasonally from 31 sites located within the Delta and on major tributaries to the Delta. Water samples were analyzed for 20 current-use pesticides and dissolved organic carbon. During the study, 11 current-use pesticides were detected; maximum concentrations ranging from 17 ng/L (for trifluralin) to 1,160 ng/L (for metolachlor). The highest concentrations of five pesticides (carbaryl, carbofuran, metolachlor, molinate, and simazine) were greater than 900 ng/L. The greatest number of pesticides was detected in the summer of 1994, whereas the least number were detected in the winter of 1994. The herbicides metolachlor and simazine were the most frequently detected pesticides and were detected in five of the six sampling seasons. The herbicides molinate and EPTC were detected only during the three summer sampling seasons. A comparison of pesticides detected during the spring and summer of 1995 showed some seasonal variability. Comparison of the three summer seasons sampled showed that a larger number of pesticides were detected, and with generally higher maximum concentrations, in 1994 than in 1995 or 1996. Dissolved organic carbon (DOC) concentrations ranged, over the course of the study, from 1.4 mg/L to 10.4 mg/L, and had a median concentration of 3.8 mg/L. On a seasonal basis, the lowest maximum DOC concentrations occurred during the summer

  4. Influence of discharge and urbanization on the concentration, speciation, and bioavailability of trace metals in the Raritan River, New Jersey. Final report

    SciTech Connect

    McLaughlin, F.B.; Ashley, G.M.; Renwick, W.H.

    1988-01-01

    The Raritan River and its tributaries are a vital drinking water and recreational resource in central New Jersey. These waters also serve as disposal media for municipal and industrial wastes and urban stormwater runoff. Rapid development over the last several decades has intensified the pressures on the quality and use of Raritan waters. The concentration and speciation of ten trace metals (Ag, As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Zn) were investigated in the Raritan Basin. From September 1985 to April 1987, one hundred twenty depth-integrated samples were collected at four locations and analyzed by Direct-Current Plasma Atomic Emission Spectrometry for concentrations of dissolved, particulate-associated, total, and suspended sediment trace metals. The concentrations of trace metals readily available, potentially available, and not available to aquatic and terrestrial biota are also reported. Discharge is the most important factor influencing the concentration and speciation of trace metals in the Raritan River and its tributaries. Seasonal variations affect speciation patterns, but have a minor impact on concentration and availability to biota. The sub-basin draining a more-urbanized area in the Raritan Basin appeared to have elevated concentrations and increased biological availability of trace metals relative to less-urbanized basins.

  5. Heavy metal concentrations and biomarkers of oxidative stress in native mussels (Mytilus edulis chilensis) from Beagle Channel coast (Tierra del Fuego, Argentina).

    PubMed

    Duarte, Claudia A; Giarratano, Erica; Amin, Oscar A; Comoglio, Laura I

    2011-08-01

    The aim of this study was to evaluate the usefulness of oxidative stress biomarkers of pollution in native mussels Mytilus edulis chilensis from the Beagle Channel. Spatial and seasonal variations of catalase, glutathione-S-transferase and lipid peroxidation in gills and digestive gland were analyzed in relation to environmental parameters, heavy metals in sediment and in tissue. Four sites with anthropogenic impact and a control site were selected and monitored during the four seasons of 2007. We found significant differences among sites in concentrations of dissolved nutrients and heavy metals in sediments, with the highest values recorded at sites with anthropogenic pressure. Different patterns were observed between concentrations of metals in tissues and in sediments suggesting differences in bioavailability. There were also significant differences in biomarker responses among sites, despite the strong seasonal variability. Our results showed relatively moderate levels of pollution in the study area as a result of urban influences.

  6. Metal concentrations in marine fishes collected from Hara biosphere in Iran.

    PubMed

    Mohammadnabizadeh, Sahar; Afshari, Reza; Pourkhabbaz, Alireza

    2013-02-01

    The metal levels (Hg, As, Cu, and Zn) in tissues of edible fish species (Pampus argenteus, Sillago sihama, Liza klunzingeri and Platycephalus indicus) were evaluated. The metal concentrations were found to follow the order: liver > kidney > gill > muscle, except for Zn from P. argenteus showing an inversion of liver and kidney. Generally, the benthic species (P. indicus and S. sihama) showed a marked potential for tolerating high metal levels. Significant negative correlations were found between fish size/age and metals concentration in the most organs. The element levels in the muscles were lower than the maximum allowable concentrations, except for mercury in S. sihama and P. indicus.

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  8. Recovering/concentrating of hemicellulosic sugars and acetic acid by nanofiltration and reverse osmosis from prehydrolysis liquor of kraft based hardwood dissolving pulp process.

    PubMed

    Ahsan, Laboni; Jahan, M Sarwar; Ni, Yonghao

    2014-03-01

    This work investigated the feasibility of recovering and concentrating sugars and acetic acid (HAc) from prehydrolysis liquor (PHL) of the kraft-based dissolving pulp process prior to fermentation of hemicellulosic sugars, by the combination of activated carbon adsorption, nanofiltration (NF) and reverse osmosis (RO) processes. To reduce the fouling PHL was subjected to adsorption on activated carbon, then the treated PHL (TPHL) passed through a nanofiltration (NF DK) membrane to retain the sugars, and the permeate of acetic acid rich solution was passed through a reverse osmosis membrane (RO SG). It was found that for NF process sugars were concentrated from 48 to 227g/L at a volume reduction factor (VRF) of 5 while 80 to 90% of acetic acid was permeated. For the reverse osmosis process, 68% of acetic acid retention was achieved at pH 4.3 and 500 psi pressure and the HAc concentration increased from 10 to 50g/L.

  9. Recovering/concentrating of hemicellulosic sugars and acetic acid by nanofiltration and reverse osmosis from prehydrolysis liquor of kraft based hardwood dissolving pulp process.

    PubMed

    Ahsan, Laboni; Jahan, M Sarwar; Ni, Yonghao

    2014-03-01

    This work investigated the feasibility of recovering and concentrating sugars and acetic acid (HAc) from prehydrolysis liquor (PHL) of the kraft-based dissolving pulp process prior to fermentation of hemicellulosic sugars, by the combination of activated carbon adsorption, nanofiltration (NF) and reverse osmosis (RO) processes. To reduce the fouling PHL was subjected to adsorption on activated carbon, then the treated PHL (TPHL) passed through a nanofiltration (NF DK) membrane to retain the sugars, and the permeate of acetic acid rich solution was passed through a reverse osmosis membrane (RO SG). It was found that for NF process sugars were concentrated from 48 to 227g/L at a volume reduction factor (VRF) of 5 while 80 to 90% of acetic acid was permeated. For the reverse osmosis process, 68% of acetic acid retention was achieved at pH 4.3 and 500 psi pressure and the HAc concentration increased from 10 to 50g/L. PMID:24434701

  10. Environmental and toenail metals concentrations in copper mining and non mining communities in Zambia.

    PubMed

    Ndilila, Wesu; Callan, Anna Carita; McGregor, Laura A; Kalin, Robert M; Hinwood, Andrea L

    2014-01-01

    Copper mining contributes to increased concentrations of metals in the environment, thereby increasing the risk of metals exposure to populations living in and around mining areas. This study investigated environmental and toenail metals concentrations of non-occupational human exposure to metals in 39 copper-mining town residents and 47 non-mining town residents in Zambia. Elevated environmental concentrations were found in samples collected from the mining town residents. Toenail concentrations of cobalt (GM 1.39 mg/kg), copper (GM 132 mg/kg), lead (21.41 mg/kg) selenium (GM 0.38 mg/kg) and zinc (GM 113 mg/kg) were significantly higher in the mining area and these metals have previously been associated with copper mining. Residence in the mining area, drinking water, dust and soil metals concentrations were the most important contributors to toenail metals concentrations. Further work is required to establish the specific pathways of exposure and the health risks of elevated metals concentrations in the copper mining area.

  11. An empirical method for estimating instream pre-mining pH and dissolved Cu concentration in catchments with acidic drainage and ferricrete

    USGS Publications Warehouse

    Nimick, D.A.; Gurrieri, J.T.; Furniss, G.

    2009-01-01

    Methods for assessing natural background water quality of streams affected by historical mining are vigorously debated. An empirical method is proposed in which stream-specific estimation equations are generated from relationships between either pH or dissolved Cu concentration in stream water and the Fe/Cu concentration ratio in Fe-precipitates presently forming in the stream. The equations and Fe/Cu ratios for pre-mining deposits of alluvial ferricrete then were used to reconstruct estimated pre-mining longitudinal profiles for pH and dissolved Cu in three acidic streams in Montana, USA. Primary assumptions underlying the proposed method are that alluvial ferricretes and modern Fe-precipitates share a common origin, that the Cu content of Fe-precipitates remains constant during and after conversion to ferricrete, and that geochemical factors other than pH and dissolved Cu concentration play a lesser role in determining Fe/Cu ratios in Fe-precipitates. The method was evaluated by applying it in a fourth, naturally acidic stream unaffected by mining, where estimated pre-mining pH and Cu concentrations were similar to present-day values, and by demonstrating that inflows, particularly from unmined areas, had consistent effects on both the pre-mining and measured profiles of pH and Cu concentration. Using this method, it was estimated that mining has affected about 480 m of Daisy Creek, 1.8 km of Fisher Creek, and at least 1 km of Swift Gulch. Mean values of pH decreased by about 0.6 pH units to about 3.2 in Daisy Creek and by 1-1.5 pH units to about 3.5 in Fisher Creek. In Swift Gulch, mining appears to have decreased pH from about 5.5 to as low as 3.6. Dissolved Cu concentrations increased due to mining almost 40% in Daisy Creek to a mean of 11.7 mg/L and as much as 230% in Fisher Creek to 0.690 mg/L. Uncertainty in the fate of Cu during the conversion of Fe-precipitates to ferricrete translates to potential errors in pre-mining estimates of as much as 0.25 units

  12. Relationships between 222Rn dissolved in ground water supplies and indoor 222Rn concentrations in some Colorado front range houses.

    PubMed

    Folger, P F; Nyberg, P; Wanty, R B; Poeter, E

    1994-09-01

    Indoor 222Rn concentrations were measured in 37 houses with alpha track detectors placed in water-use rooms near water sources (bathrooms, laundry rooms, and kitchens) and in non-water-use living rooms, dining rooms, and bedrooms away from water sources. Results show that relative contributions of 222Rn to indoor air from water use are insignificant when soil-gas concentrations are high but become increasingly important as the ratio of 222Rn-in-water: 222Rn-in-soil gas increases. High soil-gas 222Rn concentrations may mask 222Rn contributions from water even when waterborne 222Rn concentrations are as high as 750 kBq m-3. Ground water in Precambrian Pikes Peak granite averages 340 kBq m-3 222Rn, vs. 170 kBq m-3 in Precambrian migmatite, but average 222Rn concentrations in soil gas are also lower in migmatite. Because the ratio of 222Rn-in-water: 222Rn-in-soil gas may be consistently higher for houses in migmatite than in Pikes Peak granite, indoor air in houses built on migmatite may have a greater relative contribution from water use even though average 222Rn concentrations in the water are lower. Continuous monitoring of 222Rn concentrations in air on 15-min intervals also indicates that additions to indoor concentrations from water use are significant and measurable only when soil-gas concentrations are low and concentrations in water are high. When soil-gas concentrations were mitigated to less than 150 Bq m-3 in one house, water contributes 20-40% of the annual indoor 222Rn concentration in the laundry room (222Rn concentration in water of 670 kBq m-3). Conversely, when the mitigation system is inactive, diurnal fluctuations and other variations in the soil-gas 222Rn contribution swamp the variability due to water use in the house. Measurable variations in indoor concentrations from water use were not detected in one house despite a low soil-gas contribution of approximately 150 Bq m-3 because waterborne 222Rn concentrations also are low (80 kBq m-3). This

  13. Statistical Analysis Of Heavy Metals Concentration In Watermelon Plants Irrigated By Wastewater

    NASA Astrophysics Data System (ADS)

    Khanjani, M. J.; Maghsoudi moud, A. A.; Saffari, V. R.; Hashamipor, S. M.; Soltanizadeh, M.

    2008-01-01

    Concentration of heavy metals in vegetables irrigated by urban wastewater is a cause of serious concern due to the potentials health problems of consuming contaminated produce. In this study it is tried to model the concentration of heavy metals (Cd, Cr, Cu, Fe,…) as a function of their concentration in watermelon roots and stems. Our study shows there is a good relationship between them for most of collected data. By measuring the concentration in root and stem of watermelon plant samples before harvesting, the concentration of heavy metal in watermelon's fruit can be estimated by presented mathematical models. This study shows the concentrations of heavy metals in fruits, roots and stems of watermelon plants are very high and in dangerous level when irrigated by municipal waste water.

  14. Comparative toxicity of dissolved metals to early larval stages of Palaemon serratus, Maja squinado, and Homarus gammarus (Crustacea:Decapoda).

    PubMed

    Mariño-Balsa, J C; Poza, E; Vázquez, E; Beiras, R

    2000-10-01

    The acute lethal toxicities of mercury, copper, and cadmium to the first larval stage of the prawn (Palaemon serratus), spider crab (Maja squinado), and lobster (Homarus gammarus) were tested. Chromium was also tested with the prawn. Mortality was recorded after 48 h (for lobster) or 72 h (for other species) incubation at 18 degrees C, and the median lethal concentrations (LC(50) +/- 95% confidence intervals) per individual and per mass unit were calculated. The LC(50) values were, 74 microg Hg/L, 3,304 microg Cu/L, 1,686 microg Cd/L, 12,486 microg Cr/L for prawn; 72 microg Hg/L, 50 microg Cu/L, 158 microg Cd/L for spider crab; and 48 microg Hg/L, 46 microg Cu/L, 34 microg Cd/L for lobster. Therefore, larvae of spider crab and lobster were markedly more sensitive than prawn to heavy metals and thus more suitable to use in seawater quality bioassays. Of these two species, spider crab is recommended due to its abundance, easier maintenance, and higher fecundity. The mercury LC(50) values for different larval stages of P. serratus (zoea I, II, V, and VI) were obtained, and no ontogenetic change in sensitivity to the metal could be detected. PMID:10948285

  15. Distribution of heavy metal concentrations in surface sediments in Dubai Creeks, United Arab Emirates.

    PubMed

    Howari, Fares M

    2005-01-01

    Dubai is developing rapidly and many developmental activities are concentrated around its Creek. The present study reports the lateral distribution of heavy metals and compares it with local historical record of heavy metal concentrations. For this purpose surface sediment samples were collected and analyzed for metal contents, total organic carbon content (TOC), mineralogy and grain size. The percentages of the different grain size fraction of the collected sediments were as follow 65% for sand size, 15% for silt size fraction, and the rest accounted for clay size fraction. The microscopic analyses indicate that the sediment composed mainly from carbonate and quartz with traces of rock fragments. Such mineral composition is not believed to be a potential source of heavy metal. The study found that the average recorded heavy metal concentrations in the collected sediment samples were 87, 96, 127, 38.5, and 279 ppm for Cr, Cu, Ni, Pb, and Zn, respectively. Those values were slightly higher than metal concentrations recoded in 2001 with 1.22 (Cr), 2.5 (Cu), 2.87 (Ni), 0.69 (Pb), and 2.1 (Zn) folds. However, in 2001 and 2003 the measured metal contents, along the creek, were lower than those of the average earth crust. Along the Creek most metals recorded the highest concentrations in the upper reach of the Creek. The distribution of the measured heavy metals was not affected significantly with the TOC values. The present study also documented obvious related point sources of pollution.

  16. Metal concentrations of wild edible mushrooms from Turkey.

    PubMed

    Sarikurkcu, Cengiz; Tepe, Bektas; Solak, Mehmet Halil; Cetinkaya, Serap

    2012-01-01

    In the present study, the contents of Zn, Fe, Cu, Mn, Co, Ni, Pb, Cd, Cr, Al, Ca, Mg, and K in Agaricus campestris, Agrocybe cylindracea, Collybia dryophila, Helvella leucopus, Russula delica, Tricholoma auratum, Amanita ovoidea, Melanoleuca excissa, Rhizopogon roseolus, Russula chloroides, Volvoriella gloiocephala, Lyophyllum decastes, Morcella angusticeps, Morchella esculenta and Morcella eximia collected from Isparta, Mugla, and Osmaniye provinces (Turkey) were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave digestion. The intake of heavy metals (Pb, Cd) and other metals (Fe, Cu, Zn) by consumption of 30 g dry weight of mushrooms daily poses no risk at all except in A. cylindracea and H. leucopus (for Cd) for the consumer. PMID:22794131

  17. Concentrations of some heavy metals in commercially important finfish and shellfish of the River Ganga.

    PubMed

    Mitra, Abhijit; Chowdhury, Ranju; Banerjee, Kakoli

    2012-04-01

    Heavy metals are dangerous to aquatic organisms and it can be bioaccumulated in the food chain leading to diseases in human. Cumulative effects of metals or chronic poisoning may occur as a result of long-term exposure even to low concentrations. The accumulation of heavy metals varies depending upon the species, environmental conditions, and inhibitory processes. Concentrations of zinc, copper, lead, and cadmium were determined in finfish and shellfish species in the Gangetic delta using a PerkinElmer Sciex ELAN 5000 ICP mass spectrometer and expressed as milligrams per kilogram of dry weight. In finfish and shellfish species the concentrations of Zn, Cu, Pb, and Cd were comparatively higher at stations 1 and 2 than the permissible level of WHO. The concentration of metals exhibited significant spatial variation and followed the order station 1 > station 2 > station 3 > station 4, which may be related to different degree of contamination in different location. The metal accumulation exhibited species specificity.

  18. Concentrations of some heavy metals in commercially important finfish and shellfish of the River Ganga.

    PubMed

    Mitra, Abhijit; Chowdhury, Ranju; Banerjee, Kakoli

    2012-04-01

    Heavy metals are dangerous to aquatic organisms and it can be bioaccumulated in the food chain leading to diseases in human. Cumulative effects of metals or chronic poisoning may occur as a result of long-term exposure even to low concentrations. The accumulation of heavy metals varies depending upon the species, environmental conditions, and inhibitory processes. Concentrations of zinc, copper, lead, and cadmium were determined in finfish and shellfish species in the Gangetic delta using a PerkinElmer Sciex ELAN 5000 ICP mass spectrometer and expressed as milligrams per kilogram of dry weight. In finfish and shellfish species the concentrations of Zn, Cu, Pb, and Cd were comparatively higher at stations 1 and 2 than the permissible level of WHO. The concentration of metals exhibited significant spatial variation and followed the order station 1 > station 2 > station 3 > station 4, which may be related to different degree of contamination in different location. The metal accumulation exhibited species specificity. PMID:21660552

  19. Atmospherically deposited trace metals from bulk mineral concentrate port operations.

    PubMed

    Taylor, Mark Patrick

    2015-05-15

    Although metal exposures in the environment have declined over the last two decades, certain activities and locations still present a risk of harm to human health. This study examines environmental dust metal and metalloid hazards (arsenic, cadmium, lead and nickel) associated with bulk mineral transport, loading and unloading port operations in public locations and children's playgrounds in the inner city of Townsville, northern Queensland. The mean increase in lead on post-play hand wipes (965 μg/m(2)/day) across all sites was more than 10-times the mean pre-play loadings (95 μg/m(2)/day). Maximum loading values after a 10-minute play period were 3012 μg/m(2), more than seven times the goal of 400 μg/m(2) used by the Government of Western Australia (2011). Maximum daily nickel post-play hand loadings (404 μg/m(2)) were more than 26 times above the German Federal Immission Control Act 2002 annual benchmark of 15 μg/m(2)/day. Repeat sampling over the 5-day study period showed that hands and surfaces were re-contaminated daily from the deposition of metal-rich atmospheric dusts. Lead isotopic composition analysis of dust wipes ((208)Pb/(207)Pb and (206)Pb/(207)Pb) showed that surface dust lead was similar to Mount Isa type ores, which are exported through the Port of Townsville. While dust metal contaminant loadings are lower than other mining and smelting towns in Australia, they exceeded national and international benchmarks for environmental quality. The lessons from this study are clear - even where operations are considered acceptable by managing authorities, targeted assessment and monitoring can be used to evaluate whether current management practices are truly best practice. Reassessment can identify opportunities for improvement and maximum environmental and human health protection. PMID:25706750

  20. Atmospherically deposited trace metals from bulk mineral concentrate port operations.

    PubMed

    Taylor, Mark Patrick

    2015-05-15

    Although metal exposures in the environment have declined over the last two decades, certain activities and locations still present a risk of harm to human health. This study examines environmental dust metal and metalloid hazards (arsenic, cadmium, lead and nickel) associated with bulk mineral transport, loading and unloading port operations in public locations and children's playgrounds in the inner city of Townsville, northern Queensland. The mean increase in lead on post-play hand wipes (965 μg/m(2)/day) across all sites was more than 10-times the mean pre-play loadings (95 μg/m(2)/day). Maximum loading values after a 10-minute play period were 3012 μg/m(2), more than seven times the goal of 400 μg/m(2) used by the Government of Western Australia (2011). Maximum daily nickel post-play hand loadings (404 μg/m(2)) were more than 26 times above the German Federal Immission Control Act 2002 annual benchmark of 15 μg/m(2)/day. Repeat sampling over the 5-day study period showed that hands and surfaces were re-contaminated daily from the deposition of metal-rich atmospheric dusts. Lead isotopic composition analysis of dust wipes ((208)Pb/(207)Pb and (206)Pb/(207)Pb) showed that surface dust lead was similar to Mount Isa type ores, which are exported through the Port of Townsville. While dust metal contaminant loadings are lower than other mining and smelting towns in Australia, they exceeded national and international benchmarks for environmental quality. The lessons from this study are c