Wastewater reuse and predicted ecological risk posed by contaminant mixtures in Potomac River watershed streams

A wastewater model was applied to the Potomac River watershed to provide (i) a means to identify streams with a high likelihood of carrying elevated effluent-derived contaminants and (ii) risk assessments to aquatic life and drinking water. The model linked effluent discharges along stream networks, accumulated wastewater, and predicted contaminant loads of municipal wastewater constituents while accounting for instream dilution and attenuation. Simulations using 2016 data suggested that nearly 30% (8281 km) of streams were wastewater impacted. Low- to medium-order streams had the largest range of accumulated wastewater (ACCWW%) values. ACCWW% exceeded a 1% threshold at >39% of drinking-water intakes (varied by temporal condition). Risk assessments of municipal wastewater-contaminant mixtures indicated that 22% (1479 km) of streams impacted by municipal wastewater (5.5% of all reaches modeled) may pose high risk to aquatic organisms under mean-annual conditions, with fish more susceptible to chronic-exposure effects relative to other taxa. Risk varied temporally and by stream order, with the greatest risk occurring in the summer in small streams. These findings suggest that wastewater may be an important factor contributing to environmental degradation in the Potomac River watershed.     

PCB126 blocks the thermogenic beiging response of adipocytes

Environmental Science and Pollution Research - Subcutaneous white adipose tissue is capable of becoming thermogenic in a process that is referred to as “beiging.” Beiging is associated...     

Characteristics of Moose-vehicle Collisions in Anchorage, Alaska, 1991–1995

Moose have successfully adapted to Anchorage's urban environment, using greenbelt areas for shelter, forage, and protection from nearby predator populations. However, the proximity of moose to people poses unique hazards: a motor vehicle colliding a moose may cause significant injury and vehicle damage. The annual Moose Vehicle Collision (MVC) rate increased during the study period from 40 to 52 MVCs per 100,000 registered vehicles in Anchorage, a significant (X² = 7.8, p < 0.01) increase of 23%. Of 519 reported MVCs, 23% resulted in injury to 158 people, with no human fatalities. Collisions were 2.6 times more likely to have occurred in the dark (n = 375, [72%]) than during daylight hours. An MVC on a dry road was twice (95% CI: 1.29, 3.08) as likely to have resulted in an injury as an incident on a slick road. MVCs may be prevented by: reducing speed limits around greenbelt areas, brighter vehicle headlights, placement of street lights in known moose areas, underpasses for wildlife at known crossings, and snow removal to reduce berm height in areas of high moose concentrations. Published by National Safety Council and Elsevier Science Ltd     

Stability of the conjugated species of environmental phenols and parabens in human serum

In humans, the metabolism of environmental phenols may include the formation of conjugated species (e.g., glucuronides and sulfates), but the free species—not the conjugated forms—are considered biologically active. Therefore, information on the concentration of these free species in blood or urine could be helpful for risk assessment. Because conjugates could hydrolyze to their corresponding free forms during collection, handling, and storage of biological specimens, information on the temporal stability of the conjugates is of interest. Previously, we reported the temporal stability of urinary conjugates of several environmental phenols, but data on the stability of phenols' conjugated species in serum, albeit critical if concentrations of free and conjugated species are compared, are largely unknown. In the present study, we investigate the stability of the conjugates of four phenols—bisphenol A, benzophenone-3, triclosan, and 2,5-dichlorophenol—and two parabens—methyl paraben and propyl paraben—in 16 human serum samples for 30 days at above-freezing temperature storage conditions (4 °C, room temperature, and 37 °C). These conditions reflect the worst-case scenarios that could occur during the short-term storage of biological samples before their long-term storage at controlled subfreezing temperatures. We found that the percentage of the conjugated species of the four detected compounds (2,5-dichlorophenol, triclosan, and methyl and propyl parabens) in these serum specimens even when stored at 37 °C for at least 30 days did not vary significantly. These preliminary data suggest that the phenols' serum conjugates appear to be more stable than their corresponding urinary conjugates, some of which started to hydrolyze within 24 h under similar storage conditions. The reported stability of these conjugated species in human serum also suggests that the free species are unlikely to have resulted from the hydrolysis of their corresponding conjugates. This information could be important for interpreting the low concentrations of free phenol species detected in serum samples of nonoccupationally exposed populations. To our knowledge, this is the first study to report on the stability of conjugated species in serum, and as such requires replication.     

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.     

Urinary and serum metabolites of di-n-pentyl phthalate in rats

Di-n-pentyl phthalate (DPP) is used mainly as a plasticizer in nitrocellulose. At high doses, DPP acts as a potent testicular toxicant in rats. We administered a single oral dose of 500 mg kg⁻¹ bw of DPP to adult female Sprague-Dawley rats (N = 9) and collected 24-h urine samples 1 d before and 24- and 48-h after DPP was administered to tentatively identify DPP metabolites that could be used as exposure biomarkers. At necropsy, 48 h after dosing, we also collected serum. The metabolites were extracted from urine or serum, resolved with high performance liquid chromatography, and detected by mass spectrometry. Two DPP metabolites, phthalic acid (PA) and mono(3-carboxypropyl) phthalate (MCPP), were identified by using authentic standards, whereas mono-n-pentyl phthalate (MPP), mono(4-oxopentyl) phthalate (MOPP), mono(4-hydroxypentyl) phthalate (MHPP), mono(4-carboxybutyl) phthalate (MCBP), mono(2-carboxyethyl) phthalate (MCEP), and mono-n-pentenyl phthalate (MPeP) were identified based on their full scan mass spectrometric fragmentation pattern. The ω − 1 oxidation product, MHPP, was the predominant urinary metabolite of DPP. The median urinary concentrations (μg mL⁻¹) of the metabolites in the first 24 h urine collection after DPP administration were 993 (MHPP), 168 (MCBP), 0.2 (MCEP), 222 (MPP), 47 (MOPP), 26 (PA), 16 (MPeP), and 9 (MCPP); the concentrations of metabolites in the second 24 h urine collection after DPP administration were significantly lower than in the first collection. We identified some urinary metabolic products in the serum, but at much lower levels than in urine. Because of the similarities in metabolism of phthalates between rats and humans, based on our results and the fact that MHPP can only be formed from the metabolism of DPP, MHPP would be the most adequate DPP exposure biomarker for human exposure assessment. Nonetheless, based on the urinary levels of MHPP, our preliminary data suggest that human exposure to DPP in the United States is rather limited.     

Perfluorinated compounds in whole fish homogenates from the Ohio, Missouri, and Upper Mississippi Rivers, USA

A method for the analysis of 10 perfluorinated compounds (PFCs) in whole fish homogenate is presented and applied to 60 fish samples collected from the Ohio, Missouri, and upper Mississippi Rivers in 2005. Method accuracy ranged between 86 and 125% with limits of quantitation between 0.2 and 10 ng/g wet weight. Intra- and inter-batch precision was generally ±20%. Perfluorooctane sulfonate (PFOS) was the predominant compound identified in these samples, contributing over 80% of total PFC composition in the fish from these rivers, with median PFOS concentrations of 24.4, 31.8, and 53.9 ng/g wet wt in the Missouri, Ohio, and Mississippi Rivers, respectively. Median PFOS levels were significantly (p = 0.01) elevated in piscivorous fish (88.0 ng/g) when compared with non-piscivorous fish (15.9 ng/g). The 10 samples with PFOS concentrations above 200 ng/g were broadly scattered across all three rivers, providing evidence of the widespread presence of this compound in these US waterways.     

The Arctic Water Resource Vulnerability Index: An Integrated Assessment Tool for Community Resilience and Vulnerability with Respect to Freshwater

People in the Arctic face uncertainty in their daily lives as they contend with environmental changes at a range of scales from local to global. Freshwater is a critical resource to people, and although water resource indicators have been developed that operate from regional to global scales and for midlatitude to equatorial environments, no appropriate index exists for assessing the vulnerability of Arctic communities to changing water resources at the local scale. The Arctic Water Resource Vulnerability Index (AWRVI) is proposed as a tool that Arctic communities can use to assess their relative vulnerability-resilience to changes in their water resources from a variety of biophysical and socioeconomic processes. The AWRVI is based on a social-ecological systems perspective that includes physical and social indicators of change and is demonstrated in three case study communities/watersheds in Alaska. These results highlight the value of communities engaging in the process of using the AWRVI and the diagnostic capability of examining the suite of constituent physical and social scores rather than the total AWRVI score alone.