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At least 253 records · Page 14Linked to original sources
USGS2014

Long-term trends in alkalinity in large rivers of the conterminous US in relation to acidification, agriculture, and hydrologic modification

Alkalinity increases in large rivers of the conterminous US are well known, but less is understood about the processes leading to these trends as compared with headwater systems more intensively examined in conjunction with acid deposition studies. Nevertheless, large rivers are important conduits of inorganic carbon and other solutes to coastal areas and may have substantial influence on coastal calcium carbonate saturation dynamics. We examined long-term (mid-20th to early 21st century) trends in alkalinity and other weathering products in 23 rivers of the conterminous US. We used a rigorous flow-weighting technique which allowed greater focus on solute trends occurring independently of changes in flow. Increasing alkalinity concentrations and yield were widespread, occurring at 14 and 13 stations, respectively. Analysis of trends in other weathering products suggested that the causes of alkalinity trends were diverse, but at many stations alkalinity increases coincided with decreasing nitrate + sulfate and decreasing cation:alkalinity ratios, which is consistent with recovery from acidification. A positive correlation between the Sen–Thiel slopes of alkalinity increases and agricultural lime usage indicated that agricultural lime contributed to increasing solute concentration in some areas. However, several stations including the Altamaha, Upper Mississippi, and San Joaquin Rivers exhibited solute trends, such as increasing cation:alkalinity ratios and increasing nitrate + sulfate, more consistent with increasing acidity, emphasizing that multiple processes affect alkalinity trends in large rivers. This study was unique in its examination of alkalinity trends in large rivers covering a wide range of climate and land use types, but more detailed analyses will help to better elucidate temporal changes to river solutes and especially the effects they may have on coastal calcium carbonate saturation state.

Science of the Total Environment↗
USGS2014

Flow and sorption controls of groundwater arsenic in individual boreholes from bedrock aquifers in central Maine, USA

To understand the hydrogeochemical processes regulating well water arsenic (As) evolution in fractured bedrock aquifers, three domestic wells with [As] up to 478 μg/L are investigated in central Maine. Geophysical logging reveals that fractures near the borehole bottom contribute 70-100% of flow. Borehole and fracture water samples from various depths show significant proportions of As (up to 69%) and Fe (93-99%) in particulates (>0.45 μm). These particulates and those settled after a 16-day batch experiment contain 560-13,000 g/kg of As and 14-35% weight/weight of Fe. As/Fe ratios (2.5-20 mmol/mol) and As partitioning ratios (adsorbed/dissolved [As], 20,000-100,000 L/kg) suggest that As is sorbed onto amorphous hydrous ferric oxides. Newly drilled cores also show enrichment of As (up to 1300 mg/kg) sorbed onto secondary iron minerals on the fracture surfaces. Pumping at high flow rates induces large decreases in particulate As and Fe, a moderate increase in dissolved [As] and As(III)/As ratio, while little change in major ion chemistry. The δD and δ 18 O are similar for the borehole and fracture waters, suggesting a same source of recharge from atmospheric precipitation. Results support a conceptual model invoking flow and sorption controls on groundwater [As] in fractured bedrock aquifers whereby oxygen infiltration promotes the oxidation of As-bearing sulfides at shallower depths in the oxic portion of the flow path releasing As and Fe; followed by Fe oxidation to form Fe oxyhydroxide particulates, which are transported in fractures and sorb As along the flow path until intercepted by boreholes. In the anoxic portions of the flow path, reductive dissolution of As-sorbed iron particulates could re-mobilize As. For exposure assessment, we recommend sampling of groundwater without filtration to obtain total As concentration in groundwater.

Maine↗
USGS2014

Human and bovine viruses in the Milwaukee River Watershed: hydrologically relevant representation and relations with environmental variables

To examine the occurrence, hydrologic variability, and seasonal variability of human and bovine viruses in surface water, three stream locations were monitored in the Milwaukee River watershed in Wisconsin, USA, from February 2007 through June 2008. Monitoring sites included an urban subwatershed, a rural subwatershed, and the Milwaukee River at the mouth. To collect samples that characterize variability throughout changing hydrologic periods, a process control system was developed for unattended, large-volume (56–2800 L) filtration over extended durations. This system provided flow-weighted mean concentrations during runoff and extended (24-h) low-flow periods. Human viruses and bovine viruses were detected by real-time qPCR in 49% and 41% of samples (n = 63), respectively. All human viruses analyzed were detected at least once including adenovirus (40% of samples), GI norovirus (10%), enterovirus (8%), rotavirus (6%), GII norovirus (1.6%) and hepatitis A virus (1.6%). Three of seven bovine viruses analyzed were detected including bovine polyomavirus (32%), bovine rotavirus (19%), and bovine viral diarrhea virus type 1 (5%). Human viruses were present in 63% of runoff samples resulting from precipitation and snowmelt, and 20% of low-flow samples. Maximum human virus concentrations exceeded 300 genomic copies/L. Bovine viruses were present in 46% of runoff samples resulting from precipitation and snowmelt and 14% of low-flow samples. The maximum bovine virus concentration was 11 genomic copies/L. Statistical modeling indicated that stream flow, precipitation, and season explained the variability of human viruses in the watershed, and hydrologic condition (runoff event or low-flow) and season explained the variability of the sum of human and bovine viruses; however, no model was identified that could explain the variability of bovine viruses alone. Understanding the factors that affect virus fate and transport in rivers will aid watershed management for minimizing human exposure and disease transmission.

Wisconsin↗
USGS2014

Incorporation of inorganic mercury (Hg2+) in pelagic food webs of ultraoligotrophic and oligotrophic lakes: the role of different plankton size fractions and species assemblages

In lake food webs, pelagic basal organisms such as bacteria and phytoplankton incorporate mercury (Hg 2+ ) from the dissolved phase and pass the adsorbed and internalized Hg to higher trophic levels. This experimental investigation addresses the incorporation of dissolved Hg 2+ by four plankton fractions (picoplankton: 0.2–2.7 μm; pico + nanoplankton: 0.2–20 μm; microplankton: 20–50 μm; and mesoplankton: 50–200 μm) obtained from four Andean Patagonian lakes, using the radioisotope 197 Hg 2+ . Species composition and abundance were determined in each plankton fraction. In addition, morphometric parameters such as surface and biovolume were calculated using standard geometric models. The incorporation of Hg 2+ in each plankton fraction was analyzed through three concentration factors: BCF (bioconcentration factor) as a function of cell or individual abundance, SCF (surface concentration factor) and VCF (volume concentration factor) as functions of individual exposed surface and biovolume, respectively. Overall, this investigation showed that through adsorption and internalization, pico + nanoplankton play a central role leading the incorporation of Hg 2+ in pelagic food webs of Andean lakes. Larger planktonic organisms included in the micro- and mesoplankton fractions incorporate Hg 2+ by surface adsorption, although at a lesser extent. Mixotrophic bacterivorous organisms dominate the different plankton fractions of the lakes connecting trophic levels through microbial loops (e.g., bacteria–nanoflagellates–crustaceans; bacteria–ciliates–crustaceans; endosymbiotic algae–ciliates). These bacterivorous organisms, which incorporate Hg from the dissolved phase and through their prey, appear to explain the high incorporation of Hg 2+ observed in all the plankton fractions.

Patagonia↗
USGS2014

Inhalable desert dust, urban emissions, and potentially biotoxic metals in urban Saharan-Sahelian air

Saharan dust incursions and particulates emitted from human activities degrade air quality throughout West Africa, especially in the rapidly expanding urban centers in the region. Particulate matter (PM) that can be inhaled is strongly associated with increased incidence of and mortality from cardiovascular and respiratory diseases and cancer. Air samples collected in the capital of a Saharan–Sahelian country (Bamako, Mali) between September 2012 and July 2013 were found to contain inhalable PM concentrations that exceeded World Health Organization (WHO) and US Environmental Protection Agency (USEPA) PM 2.5 and PM 10 24-h limits 58 – 98% of days and European Union (EU) PM 10 24-h limit 98% of days. Mean concentrations were 1.2-to-4.5 fold greater than existing limits. Inhalable PM was enriched in transition metals, known to produce reactive oxygen species and initiate the inflammatory response, and other potentially bioactive and biotoxic metals/metalloids. Eroded mineral dust composed the bulk of inhalable PM, whereas most enriched metals/metalloids were likely emitted from oil combustion, biomass burning, refuse incineration, vehicle traffic, and mining activities. Human exposure to inhalable PM and associated metals/metalloids over 24-h was estimated. The findings indicate that inhalable PM in the Sahara–Sahel region may present a threat to human health, especially in urban areas with greater inhalable PM and transition metal exposure.

Bamako↗
USGS2015

Pesticide concentrations in frog tissue and wetland habitats in alandscape dominated by agriculture

Habitat loss and exposure to pesticides are likely primary factors contributing to amphibian decline in agricultural landscapes. Conservation efforts have attempted to restore wetlands lost through landscape modifications to reduce contaminant loads in surface waters and providing quality habitat to wildlife. The benefits of this increased wetland area, perhaps especially for amphibians, may be negated if habitat quality is insufficient to support persistent populations. We examined the presence of pesticides and nutrients in water and sediment as indicators of habitat quality and assessed the bioaccumulation of pesticides in the tissue of two native amphibian species Pseudacris maculata (chorus frogs) and Lithobates pipiens (leopard frogs) at six wetlands (3 restored and 3 reference) in Iowa, USA. Restored wetlands are positioned on the landscape to receive subsurface tile drainage water while reference wetlands receive water from overland run-off and shallow groundwater sources. Concentrations of the pesticides frequently detected in water and sediment samples were not different between wetland types. The median concentration of atrazine in surface water was 0.2 μg/L. Reproductive abnormalities in leopard frogs have been observed in other studies at these concentrations. Nutrient concentrations were higher in the restored wetlands but lower than concentrations thought lethal to frogs. Complex mixtures of pesticides including up to 8 fungicides, some previously unreported in tissue, were detected with concentrations ranging from 0.08 to 1500 μg/kg wet weight. No significant differences in pesticide concentrations were observed between species, although concentrations tended to be higher in leopard frogs compared to chorus frogs, possibly because of differences in life histories. Our results provide information on habitat quality in restored wetlands that will assist state and federal agencies, landowners, and resource managers in identifying and implementing conservation and management actions for these and similar wetlands in agriculturally dominated landscapes.

Iowa↗
USGS2015

At the crossroads: Hazard assessment and reduction of health risks from arsenic in private well waters of the northeastern United States and Atlantic Canada

This special issue contains 12 papers that report on new understanding of arsenic (As) hydrogeochemistry, performance of household well water treatment systems, and testing and treatment behaviors of well users in several states of the northeastern region of the United States and Nova Scotia, Canada. The responsibility to ensure water safety of private wells falls on well owners. In the U.S., 43 million Americans, mostly from rural areas, use private wells. In order to reduce As exposure in rural populations that rely on private wells for drinking water, risk assessment, which includes estimation of population at risk of exposure to As above the EPA Maximum Contaminant Level, is helpful but insufficient because it does not identify individual households at risk. Persistent optimistic bias among well owners against testing and barriers such as cost of treatment mean that a large percentage of the population will not act to reduce their exposure to harmful substances such as As. If households are in areas with known As occurrence, a potentially large percentage of well owners will remain unaware of their exposure. To ensure that everyone, including vulnerable populations such as low income families with children and pregnant women, is not exposed to arsenic in their drinking water, alternative action will be required and warrants further research.

Maine, New Hampshire, Massachusetts, Connecticut, ↗
USGS2015

Risk assessment of brine contamination to aquatic resources from energy development in glacial drift deposits: Williston Basin, USA

Contamination to aquatic resources from co-produced water (brine) associated with energy development has been documented in the northeastern portion of the Williston Basin; an area mantled by glacial drift. The presence and magnitude of brine contamination can be determined using the contamination index (CI) value from water samples. Recently, the U.S. Geological Survey published a section (~ 2.59 km 2 ) level risk assessment of brine contamination to aquatic resources for Sheridan County, Montana, using oilfield and hydrogeological parameters. Our goal was to improve the Sheridan County assessment (SCA) and evaluate the use of this new Williston Basin assessment (WBA) across 31 counties mantled by glacial drift in the Williston Basin. To determine if the WBA model improved the SCA model, results from both assessments were compared to CI values from 37 surface and groundwater samples collected to evaluate the SCA. The WBA (R 2 = 0.65) outperformed the SCA (R 2 = 0.52) indicating improved model performance. Applicability across the Williston Basin was evaluated by comparing WBA results to CI values from 123 surface water samples collected from 97 sections. Based on the WBA, the majority (83.5%) of sections lacked an oil well and had minimal risk. Sections with one or more oil wells comprised low (8.4%), moderate (6.5%), or high (1.7%) risk areas. The percentage of contaminated water samples, percentage of sections with at least one contaminated sample, and the average CI value of contaminated samples increased from low to high risk indicating applicability across the Williston Basin. Furthermore, the WBA performed better compared to only the contaminated samples (R 2 = 0.62) versus all samples (R 2 = 0.38). This demonstrates that the WBA was successful at identifying sections, but not individual aquatic resources, with an increased risk of contamination; therefore, WBA results can prioritize future sampling within areas of increased risk.

Montana, North Dakota↗
USGS2014

River chloride trends in snow-affected urban watersheds: increasing concentrations outpace urban growth rate and are common among all seasons

Chloride concentrations in northern U.S. included in this study have increased substantially over time with average concentrations approximately doubling from 1990 to 2011, outpacing the rate of urbanization in the northern U.S. Historical data were examined for 30 monitoring sites on 19 streams that had chloride concentration and flow records of 18 to 49 years. Chloride concentrations in most studied streams increased in all seasons (13 of 19 in all seasons; 16 of 19 during winter); maximum concentrations occurred during winter. Increasing concentrations during non-deicing periods suggest that chloride was stored in hydrologic reservoirs, such as the shallow groundwater system, during the winter and slowly released in baseflow throughout the year. Streamflow dependency was also observed with chloride concentrations increasing as streamflow decreased, a result of dilution during rainfall- and snowmelt-induced high-flow periods. The influence of chloride on aquatic life increased with time; 29% of sites studied exceeded the concentration for the USEPA chronic water quality criteria of 230 mg/L by an average of more than 100 individual days per year during 2006–2011. The rapid rate of chloride concentration increase in these streams is likely due to a combination of possible increased road salt application rates, increased baseline concentrations, and greater snowfall in the Midwestern U.S. during the latter portion of the study period.

Science of the Total Environment↗
USGS2015

Concentrations of hormones, pharmaceuticals and other micropollutants in groundwater affected by septic systems in New England and New York

Septic-system discharges can be an important source of micropollutants (including pharmaceuticals and endocrine active compounds) to adjacent groundwater and surface water systems. Groundwater samples were collected from well networks tapping glacial till in New England (NE) and sandy surficial aquifer New York (NY) during one sampling round in 2011. The NE network assesses the effect of a single large septic system that receives discharge from an extended health care facility for the elderly. The NY network assesses the effect of many small septic systems used seasonally on a densely populated portion of Fire Island. The data collected from these two networks indicate that hydrogeologic and demographic factors affect micropollutant concentrations in these systems. The highest micropollutant concentrations from the NE network were present in samples collected from below the leach beds and in a well downgradient of the leach beds. Total concentrations for personal care/domestic use compounds, pharmaceutical compounds and plasticizer compounds generally ranged from 1 to over 20 μg/L in the NE network samples. High tris(2-butoxyethyl phosphate) plasticizer concentrations in wells beneath and downgradient of the leach beds (> 20 μg/L) may reflect the presence of this compound in cleaning agents at the extended health-care facility. The highest micropollutant concentrations for the NY network were present in the shoreline wells and reflect groundwater that is most affected by septic system discharges. One of the shoreline wells had personal care/domestic use, pharmaceutical, and plasticizer concentrations ranging from 0.4 to 5.7 μg/L. Estradiol equivalency quotient concentrations were also highest in a shoreline well sample (3.1 ng/L). Most micropollutant concentrations increase with increasing specific conductance and total nitrogen concentrations for shoreline well samples. These findings suggest that septic systems serving institutional settings and densely populated areas in coastal settings may be locally important sources of micropollutants to adjacent aquifer and marine systems.

New York↗
USGS2015

Desertification, salinization, and biotic homogenization in a dryland river ecosystem

This study determined long-term changes in fish assemblages, river discharge, salinity, and local precipitation, and examined hydrological drivers of biotic homogenization in a dryland river ecosystem, the Trans-Pecos region of the Rio Grande/Rio Bravo del Norte (USA/Mexico). Historical (1977-1989) and current (2010-2011) fish assemblages were analyzed by rarefaction analysis (species richness), nonmetric multidimensional scaling (composition/variability), multiresponse permutation procedures (composition), and paired t-test (variability). Trends in hydrological conditions (1970s-2010s) were examined by Kendall tau and quantile regression, and associations between streamfiow and specific conductance (salinity) by generalized linear models. Since the 1970s, species richness and variability of fish assemblages decreased in the Rio Grande below the confluence with the Rio Conchos (Mexico), a major tributary, but not above it. There was increased representation of lower-flow/higher-salinity tolerant species, thus making fish communities below the confluence taxonomically and functionally more homogeneous to those above it. Unlike findings elsewhere, this biotic homogenization was due primarily to changes in the relative abundances of native species. While Rio Conchos discharge was > 2-fold higher than Rio Grande discharge above their confluence, Rio Conchos discharge decreased during the study period causing Rio Grande discharge below the confluence to also decrease. Rio Conchos salinity is lower than Rio Grande salinity above their confluence and, as Rio Conchos discharge decreased, it caused Rio Grande salinity below the confluence to increase (reduced dilution). Trends in discharge did not correspond to trends in precipitation except at extreme-high (90th quantile) levels. In conclusion, decreasing discharge from the Rio Conchos has led to decreasing flow and increasing salinity in the Rio Grande below the confluence. This spatially uneven desertification and salinization of the Rio Grande has in turn led to a region-wide homogenization of hydrological conditions and of taxonomic and functional attributes of fish assemblages.

Science of the Total Environment↗
USGS2015

Prevalence of toxin-producing Clostridium botulinum associated with the macroalga Cladophora in three Great Lakes: Growth and management

The reemergence of avian botulism caused by Clostridium botulinum type E has been observed across the Great Lakes in recent years. Evidence suggests an association between the nuisance algae, Cladophora spp., and C. botulinum in nearshore areas of the Great Lakes. However, the nature of the association between Cladophora and C. botulinum is not fully understood due, in part, to the complex food web interactions in this disease etiology. In this study, we extensively evaluated their association by quantitatively examining population size and serotypes of C. botulinum in algal mats collected from wide geographic areas in lakes Michigan, Ontario, and Erie in 2011–2012 and comparing them with frequencies in other matrices such as sand and water. A high prevalence (96%) of C. botulinum type E was observed in Cladophora mats collected from shorelines of the Great Lakes in 2012. Among the algae samples containing detectable C. botulinum , the population size of C. Botulinum type E was 10 0 –10 4 MPN/g dried algae, which was much greater (up to 10 3 fold) than that found in sand or the water column, indicating that Cladophora mats are sources of this pathogen. Mouse toxinantitoxin bioassays confirmed that the putative C. botulinum belonged to the type E serotype. Steam treatment was effective in reducing or eliminating C. botulinum type E viable cells in Cladophora mats, thereby breaking the potential transmission route of toxin up to the food chain. Consequently, our data suggest that steam treatment incorporated with a beach cleaning machine may be an effective treatment of Cladophora -borne C. botulinum and may reduce bird mortality and human health risks.

Lake Erie, Lake Michigan, Lake Ontario↗
USGS2015

Characterization of hydraulic fracturing flowback water in Colorado: Implications for water treatment

A suite of analytical tools was applied to thoroughly analyze the chemical composition of an oil/gas well flowback water from the Denver–Julesburg (DJ) basin in Colorado, and the water quality data was translated to propose effective treatment solutions tailored to specific reuse goals. Analysis included bulk quality parameters, trace organic and inorganic constituents, and organic matter characterization. The flowback sample contained salts (TDS = 22,500 mg/L), metals (e.g., iron at 81.4 mg/L) and high concentration of dissolved organic matter (DOC = 590 mgC/L). The organic matter comprised fracturing fluid additives such as surfactants (e.g., linear alkyl ethoxylates) and high levels of acetic acid (an additives' degradation product), indicating the anthropogenic impact on this wastewater. Based on the water quality results and preliminary treatability tests, the removal of suspended solids and iron by aeration/precipitation (and/or filtration) followed by disinfection was identified as appropriate for flowback recycling in future fracturing operations. In addition to these treatments, a biological treatment (to remove dissolved organic matter) followed by reverse osmosis desalination was determined to be necessary to attain water quality standards appropriate for other water reuse options (e.g., crop irrigation). The study provides a framework for evaluating site-specific hydraulic fracturing wastewaters, proposing a suite of analytical methods for characterization, and a process for guiding the choice of a tailored treatment approach.

Colorado↗
USGS2015

Steep spatial gradients of volcanic and marine sulfur in Hawaiian rainfall and ecosystems

Sulfur, a nutrient required by terrestrial ecosystems, is likely to be regulated by atmospheric processes in well-drained, upland settings because of its low concentration in most bedrock and generally poor retention by inorganic reactions within soils. Environmental controls on sulfur sources in unpolluted ecosystems have seldom been investigated in detail, even though the possibility of sulfur limiting primary production is much greater where atmospheric deposition of anthropogenic sulfur is low. Here we measure sulfur isotopic compositions of soils, vegetation and bulk atmospheric deposition from the Hawaiian Islands for the purpose of tracing sources of ecosystem sulfur. Hawaiian lava has a mantle-derived sulfur isotopic composition (δ 34 S VCDT) of − 0.8‰. Bulk deposition on the island of Maui had a δ 34 S VCDT that varied temporally, spanned a range from + 8.2 to + 19.7‰, and reflected isotopic mixing from three sources: sea-salt (+ 21.1‰), marine biogenic emissions (+ 15.6‰), and volcanic emissions from active vents on Kilauea Volcano (+ 0.8‰). A straightforward, weathering-driven transition in ecosystem sulfur sources could be interpreted in the shift from relatively low (0.0 to + 2.7‰) to relatively high (+ 17.8 to + 19.3‰) soil δ 34 S values along a 0.3 to 4100 ka soil age-gradient, and similar patterns in associated vegetation. However, sub-kilometer scale spatial variation in soil sulfur isotopic composition was found along soil transects assumed by age and mass balance to be dominated by atmospheric sulfur inputs. Soil sulfur isotopic compositions ranged from + 8.1 to + 20.3‰ and generally decreased with increasing elevation (0–2000 m), distance from the coast (0–12 km), and annual rainfall (180–5000 mm). Such trends reflect the spatial variation in marine versus volcanic inputs from atmospheric deposition. Broadly, these results illustrate how the sources and magnitude of atmospheric deposition can exert controls over ecosystem sulfur biogeochemistry across relatively small spatial scales.

Hawaii↗
USGS2015

Establishing a definition of polar bear (Ursus maritimus) health: A guide to research and management activities

The meaning of health for wildlife and perspectives on how to assess and measure health, are not well characterized. For wildlife at risk, such as some polar bear (Ursus maritimus) subpopulations, establishing comprehensive monitoring programs that include health status is an emerging need. Environmental changes, especially loss of sea ice habitat, have raised concern about polar bear health. Effective and consistent monitoring of polar bear health requires an unambiguous definition of health. We used the Delphi method of soliciting and interpreting expert knowledge to propose a working definition of polar bear health and to identify current concerns regarding health, challenges in measuring health, and important metrics for monitoring health. The expert opinion elicited through the exercise agreed that polar bear health is defined by characteristics and knowledge at the individual, population, and ecosystem level. The most important threats identified were in decreasing order: climate change, increased nutritional stress, chronic physiological stress, harvest management, increased exposure to contaminants, increased frequency of human interaction, diseases and parasites, and increased exposure to competitors. Fifteen metrics were identified to monitor polar bear health. Of these, indicators of body condition, disease and parasite exposure, contaminant exposure, and reproductive success were ranked as most important. We suggest that a cumulative effects approach to research and monitoring will improve the ability to assess the biological, ecological, and social determinants of polar bear health and provide measurable objectives for conservation goals and priorities and to evaluate progress.

Science of the Total Environment↗
USGS2015

Porewater dynamics of silver, lead and copper in coastal sediments and implications for benthic metal fluxes

To determine the conditions that lead to a diffusive release of dissolved metals from coastal sediments, porewater profiles of Ag, Cu, and Pb have been collected over seven years at two contrasting coastal sites in Massachusetts, USA. The Hingham Bay (HB) site is a contaminated location in Boston Harbor, while the Massachusetts Bay (MB) site is 11 km offshore and less impacted. At both sites, the biogeochemical cycles include scavenging by Fe-oxyhydroxides and release of dissolved metals when Fe-oxyhydroxides are reduced. Important differences in the metal cycles at the two sites, however, result from different redox conditions. Porewater sulfide and seasonal variation in redox zone depth is observed at HB, but not at MB. In summer, as the conditions become more reducing at HB, trace metals are precipitated as sulfides and are no longer associated with Fe-oxyhydroxides. Sulfide precipitation close to the sediment–water interface limits the trace metal flux in summer and autumn at HB, while in winter, oxidation of the sulfide phases drives high benthic fluxes of Cu and Ag, as oxic conditions return. The annual diffusive flux of Cu at HB is found to be significant and contributes to the higher than expected water column Cu concentrations observed in Boston Harbor. At MB, due to the lower sulfide concentrations, the association of trace metals with Fe-oxyhydroxides occurs throughout the year, leading to more stable fluxes. A surface enrichment of solid phase trace metals was found at MB and is attributed to the persistent scavenging by Fe-oxyhydroxides. This process is important, particularly at sites that are less reducing, because it maintains elevated metal concentrations at the surface despite the effects of bioturbation and sediment accumulation, and because it may increase the persistence of metal contamination in surface sediments.

Massachusetts↗
USGS2015

Endocrine disrupting alkylphenolic chemicals and other contaminants in wastewater treatment plant effluents, urban streams, and fish in the Great Lakes and Upper Mississippi River Regions

Urban streams are an integral part of the municipal water cycle and provide a point of discharge for wastewater treatment plant (WWTP) effluents, allowing additional attenuation through dilution and transformation processes, as well as a conduit for transporting contaminants to downstream water supplies. Domestic and commercial activities dispose of wastes down-the-drain, resulting in wastewater containing complex chemical mixtures that are only partially removed during treatment. A key issue associated with WWTP effluent discharge into streams is the potential to cause endocrine disruption in fish. This study provides a long-term (1999-2009) evaluation of the occurrence of alkylphenolic endocrine disrupting chemicals (EDCs) and other contaminants discharged from WWTPs into streams in the Great Lakes and Upper Mississippi River Regions (Indiana, Illinois, Michigan, Minnesota, and Ohio). The Greater Metropolitan Chicago Area Waterways, Illinois, were evaluated to determine contaminant concentrations in the major WWTP effluents and receiving streams, and assess the behavior of EDCs from their sources within the sewer collection system, through the major treatment unit processes at a WWTP, to their persistence and transport in the receiving stream. Water samples were analyzed for alkylphenolic EDCs and other contaminants, including 4-nonylphenol (NP), 4-nonylphenolpolyethoxylates (NPEO), 4-nonylphenolethoxycarboxylic acids (NPEC), 4-tert-octylphenol (OP), 4-tert-octylphenolpolyethoxylates (OPEO), bisphenol A, triclosan, ethylenediaminetetraacetic acid (EDTA), and trace elements. All of the compounds were detected in all of the WWTP effluents, with EDTA and NPEC having the greatest concentrations. The compounds also were detected in the WWTP effluent dominated rivers. Multiple fish species were collected from river and lake sites and analyzed for NP, NPEO, NPEC, OP, and OPEO. Whole-body fish tissue analysis indicated widespread occurrence of alkylphenolic compounds, with the highest concentrations occurring in streams with the greatest WWTP effluent content. Biomarkers of endocrine disruption in the fish indicated long-term exposure to estrogenic chemicals in the wastewater impacted urban waterways.

Science of the Total Environment↗
USGS2015

Exposure to runoff from coal-tar-sealed pavement induces genotoxicity and impairment of DNA repair capacity in the RTL-W1 fish liver cell line

Coal-tar-based (CTB) sealcoat, frequently applied to parking lots and driveways in North America, contains elevated concentrations of polycyclic aromatic hydrocarbons (PAHs) and related compounds. The RTL-W1 fish liver cell line was used to investigate two endpoints (genotoxicity and DNA-repair-capacity impairment) associated with exposure to runoff from asphalt pavement with CTB sealcoat or with an asphalt-based sealcoat hypothesized to contain about 7% CTB sealcoat (AS-blend). Genotoxic potential was assessed by the Formamido pyrimidine glycosylase (Fpg)-modified comet assay for 1:10 and 1:100 dilutions of runoff samples collected from 5 h to 36 d following sealcoat application. DNA-repair capacity was assessed by the base excision repair comet assay for 1:10 dilution of samples collected 26 h and 36 d following application. Both assays were run with and without co-exposure to ultraviolet-A radiation (UVA). With co-exposure to UVA, genotoxic effects were significant for both dilutions of CTB runoff for three of four sample times, and for some samples of AS-blend runoff. Base excision repair was significantly impaired for CTB runoff both with and without UVA exposure, and for AS-blend runoff only in the absence of UVA. This study is the first to investigate the effects of exposure to the complex mixture of chemicals in coal tar on DNA repair capacity. The results indicate that co-exposure to runoff from CT-sealcoated pavement and UVA as much as a month after sealcoat application has the potential to cause genotoxicity and impair DNA repair capacity.

Science of the Total Environment↗