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San Antonio, United States

Johnson B.,U.S. Army | Zhang Z.,SpecPro | Velleux M.,Hydroqual Inc | Julien P.,Colorado State University
Soil and Sediment Contamination

CTT&F is a physically based, spatially distributed watershed contaminant transport, transformation, and fate sub-model designed for use within existing hydrological modeling systems. To describe the fate of contaminants through landscape media as well as spatial variations of contaminant distributions, physical transport and transformation processes in CTT&F are simulated for each cell in the model and routed to the watershed outlet. CTT&F simulates contaminant erosion from soil and transport across the land surface by overland flow. The model also simulates contaminant erosion from stream bed sediment and transport through channels in addition to transport of contaminants inputs by overland flow. CTT&F can simulate solid (granular) contaminant transport and transformation, including partitioning between freely dissolved, dissolved organic carbon (DOC) bound, and particle-sorbed phases. To demonstrate model capabilities, CTT&F was coupled with an existing distributed hydrologic model and was tested and validated to simulate RDX and TNT transport using two experimental plots. These experiments examined dissolution of solid contaminants into the dissolved phase and their subsequent transport to the plot outlet. Model results were in close agreement with measured data. Such a model provides information for decision makers to make rational decisions relevant to the fate of toxic compounds. © Taylor & Francis Group, LLC. Source

Coleman J.G.,U.S. Army | Johnson D.R.,U.S. Army | Stanley J.K.,U.S. Army | Bednar A.J.,U.S. Army | And 3 more authors.
Environmental Toxicology and Chemistry

Nano-sized aluminum is currently being used by the military and commercial industries in many applications including coatings, thermites, and propellants. Due to the potential for wide dispersal in soil systems, we chose to investigate the fate and effects of nano-sized aluminum oxide (Al2O 3), the oxidized form of nano aluminum, in a terrestrial organism. The toxicity and bioaccumulation potential of micron-sized (50-200 μm, nominal) and nano-sized (11 nm, nominal) Al2O3 was comparatively assessed through acute and subchronic bioassays using the terrestrial earthworm, Eisenia fetida. Subchronic (28-d) studies were performed exposing E. fetida to nano- and micron-sized Al2O3-spiked soils to assess the effects of long-term exposure. No mortality occurred in subchronic exposures, although reproduction decreased at ≥3,000 mg/kg nano-sized Al2O3 treatments, with higher aluminum body burdens observed at 100 and 300 mg/kg; no reproductive effects were observed in the micron-sized Al2O3 treatments. In addition to toxicity and bioaccumulation bioassays, an acute (48-h) behavioral bioassay was conducted utilizing a soil avoidance wheel in which E. fetida were given a choice of habitat between control, nano-, or micron-sized Al2O 3 amended soils. In the soil avoidance bioassays, E. fetida exhibited avoidance behavior toward the highest concentrations of micron- and nano-sized Al2O3 (>5,000 mg/kg) relative to control soils. Results of the present study indicate that nano-sized Al2O3 may impact reproduction and behavior of E. fetida, although at high levels unlikely to be found in the environment. © 2010 SETAC. Source

van Ommen Kloeke A.E.E.,VU University Amsterdam | Gong P.,SpecPro | Ellers J.,VU University Amsterdam | Roelofs D.,VU University Amsterdam
Environmental Toxicology and Chemistry

Earthworms perform key functions for a healthy soil ecosystem, such as bioturbation. The soil ecosystem can be challenged by natural toxins such as isothiocyanates (ITCs), produced by many commercial crops. Therefore, the effects of 2-phenylethyl ITC were investigated on the earthworm Eisenia andrei using an ecotoxicogenomics approach. Exposure to 2-phenylethyl ITC reduced both survival and reproduction of E. andrei in a dose-dependent manner (median effective concentration [EC50]=556 nmol/g). Cross-species comparative genomic hybridization validated the applicability of an existing 4×44000 Eisenia fetida microarray to E. andrei. Gene expression profiles revealed the importance of metallothionein (MT) as an early warning signal when E. andrei was exposed to low concentrations of 2-phenylethyl ITC. Alignment of these MT genes with the MT-2 gene of Lumbricus rubellus showed that at least 2 MT gene clusters are present in the Eisenia sp. genome. At high-exposure concentrations, gene expression was mainly affected by inhibiting chitinase activity, inducing an oxidative stress response, and stimulating energy metabolism. Furthermore, analysis by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway implied that the high concentration may have caused impaired light sensitivity, angiogenesis, olfactory perception, learning, and memory. Increased levels of ITCs may be found in the field in the near future. The results presented call for a careful investigation to quantify the risk of such compounds before allowing them to enter the soil on a large scale. © 2013 SETAC. Source

Garcia-Reyero N.,University of Florida | Garcia-Reyero N.,Jackson State University | Lavelle C.M.,University of Minnesota | Escalon B.L.,SpecPro | And 5 more authors.
Aquatic Toxicology

Rivers containing effluents from water treatment plants are complex soups of compounds, ranging from pharmaceuticals to natural hormones. Male fathead minnows (Pimephales promelas) were exposed for 3 weeks to effluent waters from the Metropolitan Wastewater Treatment Plant in St. Paul, MN. Fish were tested for their competitive nest holding behavior. Changes in vitellogenin were measured and these were correlated to changes in gene expression using a 22,000 gene microarray developed specifically for fathead minnows. Significant changes in gene expression were observed in both liver and testis, which correlate to phenotypic changes of vitellogenin induction and reduced competitive behavior. We also compared by real-time PCR the expression changes in key genes related to steroid biosynthesis and metabolism in fish exposed to the effluent as well as in fish exposed to a model estrogen and a model androgen. While the gene expression signature from effluent-exposed fish shared some elements with estrogen and androgen signatures, overall it was different, underscoring the complexity of compounds present in sewage and their different modes of action. © 2010 Elsevier B.V. Source

Pennington J.C.,U.S. Army | Lotufo G.,U.S. Army | Hayes C.A.,SpecPro | Porter B.,SpecPro | George R.D.,Space and Naval Warfare Systems Center Pacific
ACS Symposium Series

Explosives may enter marine environments from unexploded ordnance, thus the potential for marine sediments to act as a sink for released explosives was evaluated. Relative distributions of TNT, RDX, and HMX in volatile, overlying water, pore water and sediment compartments were quantified, and their respective partitioning behaviors into various components of organic matter in marine sediments were determined. Marine sediments were incubated with radiolabeled explosives, held at 15°C for periods varying from 1 to 90 days and fractionated to the solvent extractable, cellulose, fulvic acid (FA), humic acid (HA), and humin organic carbon sediment pools. Studies of incubated sediment systems designed to trap CO2 and volatile organic compounds were also performed. For TNT and RDX, sediment is the principal sink, whereas for HMX, mineralization to CO2 is important. Mineralization is negligible for TNT, but significant for RDX. Contact time with sediment had a decreasing effect on the bioavailability of TNT, RDX, and HMX. © 2011 American Chemical Society. Source

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