Critical Review of Exposure and Effects: Implications for Setting Regulatory Health Criteria for Ingested Copper

Environmental Management - Decades of study indicate that copper oral exposures are typically not a human health concern. Ingesting high levels of soluble copper salts can cause acute...     

Estimating the spatial scale of herbicide and soil interactions by nested sampling, hierarchical analysis of variance and residual maximum likelihood

An unbalanced nested sampling design was used to investigate the spatial scale of soil and herbicide interactions at the field scale. A hierarchical analysis of variance based on residual maximum likelihood (REML) was used to analyse the data and provide a first estimate of the variogram. Soil samples were taken at 108 locations at a range of separating distances in a 9 ha field to explore small and medium scale spatial variation. Soil organic matter content, pH, particle size distribution, microbial biomass and the degradation and sorption of the herbicide, isoproturon, were determined for each soil sample. A large proportion of the spatial variation in isoproturon degradation and sorption occurred at sampling intervals less than 60 m, however, the sampling design did not resolve the variation present at scales greater than this. A sampling interval of 20-25 m should ensure that the main spatial structures are identified for isoproturon degradation rate and sorption without too great a loss of information in this field.     

Impact of Cathode Conditions on Coupled Electrochemical Treatment of Nitrate Brine Concentrates

Simulated concentrated nitrate brine waste was treated in a two-stage electrolysis process, where reduction of nitrate in a cathodic chamber was coupled with oxidation of ammonium (produced in the previous stage) in an anodic chamber. The influence of operating conditions such as applied potential, electrolyte composition, and initial concentration on conversion of nitrate to ammonium in the cathodic chamber was investigated. The effects of chloride and current density on the two-stage treatment process were also examined. More negative potential at the cathode (?2.0 vs. ?1.7 and ?1.5 V) and higher current density (33 vs. 22 and 13.9 mA/cm²) favored ammonium as the product of nitrate reduction at a copper cathode and increased the overall amount of nitrate conversion. Faster reduction was seen when nitrate concentration was lower (0.01 vs. 0.02 N), but total mass conversion of nitrate in the same time period was higher for 0.02 N. The reduction of nitrate was not sensitive to sulfate or chloride concentration in the ranges studied (0–2 and 1–1.5 mg/L, respectively), but the oxidation of ammonium was noticeably higher when chloride was present. Only small amounts of ammonium and nitrate remained in the second-stage effluent after coupled treatment.     

Effects of fifteen PBDE metabolites, DE71, DE79 and TBBPA on steroidogenesis in the H295R cell line

Polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol A (TBBPA) are brominated flame retardants that are produced in large quantities and are commonly used in construction materials, textiles, and as polymers in electronic equipment. Environmental and human levels of PBDEs have been increasing in the past 30 years, but the toxicity of PBDEs is not fully understood. Studies on their effects are relatively limited, and show that PBDEs are neurotoxins and potential endocrine disrupters. Hydroxylated (OH) and methoxylated (MeO) PBDEs have also been reported in the adipose tissue, blood and milk of wild animals and humans. In the present study, 15 PBDE metabolites, two BDE mixtures (DE71 and DE79), and TBBPA were studied individually to determine their effects on ten steroidogenic genes, aromatase activity, and concentrations of two steroid hormones (testosterone and 17beta-estradiol) in the H295R human adrenocortical carcinoma cell line. Exposure to 0.05 microM 2'-OH-BDE-68 significantly induced the expression of CYP11A, CYP11B2, CYP17, CYP21, 3betaHSD2, 17betaHSD1, and 17betaHSD4, and the expression of StAR was induced by 6-OH-BDE-90 at the three exposure concentrations. Exposure to DE71 and DE79 resulted in dose-dependent trend towards induction, but these effects were not significant. Exposure to 0.5 microM 2-OH-BDE-123 and 2-MeO-BDE-123 resulted in significantly greater aromatase activity. However, none of the compounds affected sex hormone production at the concentrations tested. Generally, OH-BDEs had a much stronger ability to affect steroidogenic gene expression than MeO-BDEs.     

Long-term changes in fish mercury levels in the historically impacted English-Wabigoon River system (Canada)

The English-Wabigoon River system in Northwestern Ontario, Canada, was one of the most heavily mercury-contaminated waterways in the world due to historical discharges in the 1960s from a chlor-alkali plant. This study examines long-term (1970-2010) monitoring data to assess temporal trends in mercury contamination in Walleye, Northern Pike and Lake Whitefish, three species important for sport and subsistence fishing in this region, using dynamic linear modeling and piecewise regression. For all lakes and species, there is a significant decline (36-94%) in mercury concentrations through time; however, there is evidence that this decline is either slowing down or levelling off. Concentrations in the English-Wabigoon fish are elevated, and may still present a potential health risk to humans consuming fish from this system. Various biotic and abiotic factors are examined as possible explanations to slowing rates of decline in mercury concentrations observed in the mid-1980s.     

Identifying a Linked Reserve System Using a Regional Landscape Approach: the Florida Ecological Network

Abstract: We completed an analysis of potential ecological connectivity to identify areas with priority conservation significance and landscape linkages as part of a state of Florida program called Greenways. This is the latest step in the state's design and protection of a reserve system based on an aggressive land acquisition program. We used geographic information systems software (Arc-Info) to develop a decision support model that uses land-use data and information on significant ecological areas—including important habitats for target species, priority ecological communities, wetlands, roadless areas, floodplains, and important aquatic systems—to identify larger areas of ecological priority and potential ecological linkages. The result of this process, the Florida Ecological Network, includes approximately half the state's area, with over half of this network already in conservation lands or public-domain water. This network could provide a linked statewide reserve system containing most of each major ecological community and most known occurrences of rare species. Although the ecological network represents significant progress toward a more integrated approach to biodiversity conservation in Florida, further analysis is needed to (1) ensure that the needs of wide-ranging species, such as the Florida panther (   Puma concolor coryi ) and Florida black bear (   Ursus americanus floridanus ), are addressed; (2) identify other biodiversity elements not well represented; and (3) designate a system of cores and buffers that will address management issues. Reserve design is an iterative process, and future plans need to address new information, including the results of the Florida GAP analysis project and ongoing habitat loss.     

Bioventing of No. 2 Fuel Oil: Effects of Air Flowrate,Temperature, Nutrient Amendment,and Acclimation

A 14‐month pilot‐scale bioventing study, sponsored by the New Hampshire Department of Environmental Services, was conducted by the University of New Hampshire to determine the effects of the time between the contamination event and the onset of bioventing, as well as air flowrate, temperature, and nutrient amendments. Freshly contaminated soil was not readily amenable to bioventing. Bioventing was effective (82–92.5 percent removal) for acclimated soil amended with nutrients at 10 °C and 20 °C for the 275 cm³/min and 140 cm³/min air flowrates, respectively. First order degradation rates after nutrient addition were ?6.11 ± 0.83 (×10^?3)/day and ?6.57 ± 1.71 (×10^?3)/day, respectively. The results indicate that bioventing will be best applied when the contamination has occurred at least two years before the onset of treatment. © 2014 Wiley Periodicals, Inc.     

High solids co-digestion of food and landscape waste and the potential for ammonia toxicity

A pilot-scale study was completed to determine the feasibility of high-solids anaerobic digestion (HSAD) of a mixture of food and landscape wastes at a university in central Pennsylvania (USA). HSAD was stable at low loadings (2 g COD/L-day), but developed inhibitory ammonia concentrations at high loadings (15 g COD/L-day). At low loadings, methane yields were 232 L CH₄/kg COD fed and 229 L CH₄/kg VS fed, and at high loadings yields were 211 L CH₄/kg COD fed and 272 L CH₄/kg VS fed. Based on characterization and biodegradability studies, food waste appears to be a good candidate for HSAD at low organic loading rates; however, the development of ammonia inhibition at high loading rates suggests that the C:N ratio is too low for use as a single substrate. The relatively low biodegradability of landscape waste as reported herein made it an unsuitable substrate to increase the C:N ratio. Codigestion of food waste with a substrate high in bioavailable carbon is recommended to increase the C:N ratio sufficiently to allow HSAD at loading rates of 15 g COD/L-day.     

Seasonal performance of an outdoor constructed wetland for graywater treatment in a temperate climate

The seasonal treatment efficiency of a pilot-scale constructed wetland system located outdoors in a semi-arid, temperate climate was evaluated for graywater in a comprehensive, 1-year study. The system consisted of two wetland beds in series--a free water surface bed followed by a subsurface flow bed. Water quality monitoring evaluated organics, solids, nutrients, microbials, and surfactants. The results showed that the wetland substantially reduced graywater constituents during fall, spring, and summer, including biochemical oxygen demand (BOD) (92%), total nitrogen (85%), total phosphorus (78%), total suspended solids (TSS) (73%), linear alkylbenzene sulfonate (LAS) surfactants (94%), and E. coli (1.7 orders of magnitude). Except for TSS, lower removals of graywater constituents were noted in winter--BOD (78%), total nitrogen (64%), total phosphorus (65%), LAS (87%), and E. coli (1.0 order), indicating that, although wetland treatment slowed during the winter, the system remained active, even when the average water temperature was 5.2 +/- 4.5 degrees C.     

Distribution and partitioning of depleted uranium (DU) in soils at weapons test ranges - investigations combining the BCR extraction scheme and isotopic analysis

Depleted uranium (DU) has become a soil contaminant of considerable concern in many combat zones and weapons-testing sites around the world, including locations in Europe, the Middle East and the USA, arising from its dispersion via the application of DU-bearing munitions. Once DU is released into the environment its mobility and bioavailability will, like that of other contaminants, largely depend on the type of associations it forms in soil and on the nature of the soil components to which it binds. In this study we used the BCR sequential extraction scheme to determine the partitioning of DU amongst soil fractions of texturally varying soils from locations affected by weapons-testing activities. Isotopic analyses (MC-ICP-MS and alpha-spectrometry) were performed to verify the presence of DU in whole soils and soil fractions and to determine any preferential partitioning of the contaminant. Results identified soil organic matter as being consistently the most important component in terms of DU retention, accounting for 30-100% of DU observed in the soils examined. However, at greater distances from known contamination points, DU was also found to be largely associated with the exchangeable fraction, suggesting that DU can be mobilised and transported by surface and near-surface water and does remain in an exchangeable (and thus potentially bioavailable) form in soils.