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The benthic community was analyzed to evaluate pollution-induced changes for the polychlorinated biphenyl (PCB)-contaminated site at Hunters Point (HP) relative to 30 reference sites in San Francisco Bay, California, USA. An analysis based on functional traits of feeding, reproduction, and position in the sediment shows that HP is depauperate in deposit feeders, subsurface carnivores, and species with no protective barrier. Sediment chemistry analysis shows that PCBs are the major risk drivers at HP (1,570 ppb) and that the reference sites contain very low levels of PCB contamination (9 ppb). Different feeding traits support the existence of direct pathways of exposure, which can be mechanistically linked to PCB...
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This metadata record contains 15 tables with results from field and laboratory tests used to assess bioremediation in wetland areas at the Standard Chlorine of Delaware, Inc. Superfund site, New Castle County, Delaware, during 2019-2021. Included in the dataset are (1) polychlorinated biphenyl (PCB) concentrations in wetland sediment from sediment microcosm laboratory experiments, (2) chlorobenzene concentrations in wetland sediment from sediment microcosm laboratory experiments, (3) polychlorinated biphenyl concentrations from PCB microcosm laboratory experiments using polyethylene strips, (4) chlorobenzene concentrations from PCB microcosm laboratory experiments using polyethylene strips, (5) total iron and ferrous...
Agricultural residues are abundantly available in energy deficient developing countries. Many of the agricultural residues are considered as waste, and their energy potential has not been realized in energy recovery schemes. Coutilization of agricultural residues in existing coal fired power plants can help in producing clean energy, disposing of waste, and increasing the income of the rural population. Sheameal, cotton stalk, sugar cane bagasse, and wood chips were cofired with coal in 5, 10, and 15% thermal fractions in a 20 kW down-fired combustor. The combustion behavior of the blends of biomass-coal was examined. It was found that agricultural residues can be used as a potential substitute fuel and can help...
Cobalt is a naturally occurring element found in rocks, soil, water, plants, and animals and has diverse industrial importance. It is cycled in surface environments through many natural processes (e.g. volcanic eruptions, weathering) and can be introduced through numerous anthropogenic activities (e.g. burning of coal or oil, or the production of cobalt alloys). The environmental behaviour of cobalt in terrestrial environment is relatively poorly studied and in particular where Co is used in industrial processes, the baseline information to support wider and long-term environmental impacts is widely dispersed. To support the adoption of new EU regulations on the risk assessment of chemicals, we review here the various...
Robin Stewart's research is focused on identifying and understanding processes influencing the fate and bioavailability of selenium and mercury in food webs across a range of aquatic environments including estuaries, rivers, lakes and reservoirs.
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This dataset is comprised of water quality data and benthic macroinvertebrate data collected from basins in Colorado, USA, and Finland. The data includes ancillary water quality characteristics but also a suite of trace metals observed at each site. Also included are modeled outputs that characterize the bioavailability of each trace metal to a biotic ligand. These data were used to explore the importance of metal toxicity and pH as stressors on benthic macroinvertebrates characterized as the number of unique Ephemeroptera + Plecoptera + Trichoptera genera observed at each site. An interpretive summary of the work follows. One of the primary goals of biological assessment of rivers is to identify whether contaminants...
Agricultural residues are abundantly available in energy deficient developing countries. Many of the agricultural residues are considered as waste, and their energy potential has not been realized in energy recovery schemes. Coutilization of agricultural residues in existing coal fired power plants can help in producing clean energy, disposing of waste, and increasing the income of the rural population. Sheameal, cotton stalk, sugar cane bagasse, and wood chips were cofired with coal in 5, 10, and 15% thermal fractions in a 20 kW down-fired combustor. The combustion behavior of the blends of biomass-coal was examined. It was found that agricultural residues can be used as a potential substitute fuel and can help...
Research objectives: i) To determine whether metals, including dissolved, colloidal and particulate metals, are bioavailable and toxic to organisms; ii) To characterize and parameterize the physiological and geochemical processes governing metal bioaccumulation, toxicity and ultimately trophic transfer in aquatic ecosystems. iii) To model metal bioaccumulation and toxicity using kinetic models iv) To develop approaches that use isotopically modified metals, metal nanoparticles and metal bound to distinct mineral phases (such as Cu on ferric oxides) to quantify their bioavailability and toxicity to organisms, in particular invertebrates; v) To use enriched metal isotopes to gain mechanistic understanding of...
A value of simultaneously extracted metal to acid-volatile sulfide (SEM–AVS) can provide important information regarding metal availability in anaerobic sediment. SEM and AVS concentrations were obtained by the cold-acid purge-and-trap technique during spring and summer at six locations along the Mississippi River floodplain. SEM–AVS values and AVS concentrations did not vary significantly between locations during both seasons. AVS concentrations were significantly greater during summer than spring, resulting in significantly lower SEM–AVS values in summer. Total SEM concentrations did not significantly vary between seasons or specific locations. SEM-AVS values were greater than one at each location during both...
Field-related influences on polychlorinated biphenyl (PCB) exposure were evaluated by employing caged deposit-feeders, Neanthes arenaceodentata, along with polyoxymethylene (POM) samplers using parallel in situ and ex situ bioassays with homogenized untreated or activated carbon (AC) amended sediment. The AC amendment achieved a remedial efficiency in reducing bioaccumulation by 90% in the laboratory and by 44% in the field transplants. In situ measurements showed that PCB uptake by POM samplers was greater for POM placed in the surface sediment compared with the underlying AC amendment, suggesting that tidal exchange of surrounding material with similar PCB availability as untreated sediment was redeposited in...
My research objectives include characterization of dissolved and particulate natural organic acid influence on the reactivity, bioavailability, and mobility of metal ions and inorganic surfaces in aquatic environments. An important research objective of my project is examination of formation and dissolution rates of carbonate minerals. Biocalcification is a significant carbon sink in the world carbon budget and requires further investigation. I study aspects of biocalcification processes that proceed through a highly unstable calcium carbonate polymorph – amorphous calcium carbonate (ACC) stabilized by organic acids. I use chemical thermodynamics and kinetics to better describe and predict the fate and distribution...
Cobalt is a naturally occurring element found in rocks, soil, water, plants, and animals and has diverse industrial importance. It is cycled in surface environments through many natural processes (e.g. volcanic eruptions, weathering) and can be introduced through numerous anthropogenic activities (e.g. burning of coal or oil, or the production of cobalt alloys). The environmental behaviour of cobalt in terrestrial environment is relatively poorly studied and in particular where Co is used in industrial processes, the baseline information to support wider and long-term environmental impacts is widely dispersed. To support the adoption of new EU regulations on the risk assessment of chemicals, we review here the various...
In most soils, inorganic phosphorus occurs at fairly low concentrations in the soil solution whilst a large proportion of it is more or less strongly held by diverse soil minerals. Phosphate ions can indeed be adsorbed onto positively charged minerals such as Fe and Al oxides. Phosphate (P) ions can also form a range of minerals in combination with metals such as Ca, Fe and Al. These adsorption/desorption and precipitation/dissolution equilibria control the concentration of P in the soil solution and, thereby, both its chemical mobility and bioavailability. Apart from the concentration of P ions, the major factors that determine those equilibria as well as the speciation of soil P are (i) the pH, (ii) the concentrations...
    map background search result map search result map Disentangling the effects of low pH and metal mixture toxicity on macroinvertebrate diversity: data sets Volatile organic compound, polychlorinated biphenyl, and biogeochemical data from passive samplers and laboratory experiments for wetland bioremediation study, Standard Chlorine of Delaware, Inc. Superfund Site, New Castle County, Delaware, 2019–2021 Volatile organic compound, polychlorinated biphenyl, and biogeochemical data from passive samplers and laboratory experiments for wetland bioremediation study, Standard Chlorine of Delaware, Inc. Superfund Site, New Castle County, Delaware, 2019–2021 Disentangling the effects of low pH and metal mixture toxicity on macroinvertebrate diversity: data sets