Legacy Contaminants Research Articles

Co‐occurrence of 1,4‐dioxane with trichloroethylene in chlorinated solvent groundwater plumes at US Air Force installations: Fact or fiction

Increasing regulatory attention to 1,4-dioxane has prompted the United States Air Force (USAF) to evaluate potential environmental liabilities, primarily associated with legacy contamination, at an enterprise scale. Although accurately quantifying environmental liability is operationally difficult given limited historic environmental monitoring data, 1,4-dioxane is a known constituent (i.e., stabilizer) of chlorinated solvents, in particular 1,1,1-trichloroethane (TCA). Evidence regarding the co-occurrence of 1,4-dioxane and trichloroethylene (TCE), however, has been heavily debated. In fact, the prevailing opinion is that 1,4-dioxane was not a constituent of past TCE formulations and, therefore, these 2 contaminants would not likely co-occur in the same groundwater plume. Because historic handling, storage, and disposal practices of chlorinated solvents have resulted in widespread groundwater contamination at USAF installations, significant potential exists for unidentified 1,4-dioxane contamination. Therefore, the objective of this investigation is to determine the extent to which 1,4-dioxane co-occurs with TCE compared to TCA, and if these chemicals are co-contaminants, whether or not there is significant correlation using available monitoring data. To accomplish these objectives, the USAF Environmental Restoration Program Information Management System (ERPIMS) was queried for all relevant records for groundwater monitoring wells (GMWs) with 1,4-dioxane, TCA, and TCE, on which both categorical and quantitative analyses were carried out. Overall, ERPIMS contained 5788 GMWs from 49 installations with records for 1,4-dioxane, TCE, and TCA analytes. 1,4-Dioxane was observed in 17.4% of the GMWs with detections for TCE and/or TCA, which accounted for 93.7% of all 1,4-dioxane detections, verifying that 1,4-dioxane is seldom found independent of chlorinated solvent contamination. Surprisingly, 64.4% of all 1,4-dioxane detections were associated with TCE independently. Given the extensive data set, these results conclusively demonstrate for the first time that 1,4-dioxane is a relatively common groundwater co-contaminant with TCE. Trend analysis demonstrated a positive log-linear relationship where median 1,4-dioxane levels increased between approximately 6% and approximately 20% of the increase in TCE levels. In conclusion, this data mining exercise suggests that 1,4-dioxane has a probability of co-occurrence of approximately 17% with either TCE and/or TCA. Given the challenges imposed by remediation of 1,4-dioxane and the pending promulgation of a federal regulatory standard, environmental project managers should use the information presented in this article for prioritization of future characterization efforts to respond to the emerging issue. Importantly, site investigations should consider 1,4-dioxane a potential co-contaminant of TCE in groundwater plumes.

Estimations of historical atmospheric mercury concentrations from mercury refining and present-day soil concentrations of total mercury in Huancavelica, Peru

Detailed Spanish records of cinnabar mining and mercury production during the colonial period in Huancavelica, Peru were examined to estimate historical health risks to the community from exposure to elemental mercury (Hg) vapor resulting from cinnabar refining operations. Between 1564 and 1810, nearly 17,000metrictons of Hg were released to the atmosphere in Huancavelica from Hg production. AERMOD was used with estimated emissions and source characteristics to approximate historic atmospheric concentrations of mercury vapor. Modeled 1-hour and long-term concentrations were compared with present-day inhalation reference values for elemental Hg. Estimated 1-hour maximum concentrations for the entire community exceeded present-day occupational inhalation reference values, while some areas closest to the smelters exceeded present-day emergency response guideline levels. Estimated long-term maximum concentrations for the entire community exceeded the EPA Reference Concentration (RfC) by a factor of 30 to 100, with areas closest to the smelters exceeding the RfC by a factor of 300 to 1000. Based on the estimated historical concentrations of Hg vapor in the community, the study also measured the extent of present-day contamination throughout the community through soil sampling and analysis. Total Hg in soils sampled from 20 locations ranged from 1.75 to 698mg/kg and three adobe brick samples ranging from 47.4 to 284mg/kg, consistent with other sites of mercury mining and use. The results of the soil sampling indicate that the present-day population of Huancavelica is exposed to levels of mercury from legacy contamination which is currently among the highest worldwide, consequently placing them at potential risk of adverse health outcomes.

Contaminants of Concern in the Marine Environment: The Need for New Monitoring and Assessment Strategies

Contaminants of Concern in the Marine Environment: The Need for New Monitoring and Assessment Strategies More than 156 million people, over half of the U.S. population, live in the coastal zone. These areas contribute $7.9 trillion to the U.S. economy. Economic development within the coastal zone may result in the discharge of chemical contaminants into coastal ecosystems from sewage treatment plants, industrial point sources and urban and agricultural nonpoint source runoff. Aquatic monitoring programs have long measured legacy contaminants such as DDT and PCBs, but are increasingly being asked to focus on modern commercial chemicals that as a group are referred to as Contaminants of Emerging Concern (CECs). CECs present many challenges, often because measurement methods don’t yet exist nor have toxicological studies yet been conducted to place monitoring results in proper context. This challenge is exacerbated because many CECs interact with hormone systems in wildlife to affect reproduction and development in ways that are not assessed through traditional toxicological evaluations.

Contrasting controls on arsenic and lead budgets for a degraded peatland catchment in Northern England

Atmospheric deposition of trace metals and metalloids from anthropogenic sources has led to the contamination of many European peatlands. To assess the fate and behaviour of previously deposited arsenic and lead, we constructed catchment-scale mass budgets for a degraded peatland in Northern England. Our results show a large net export of both lead and arsenic via runoff (282 ± 21.3 gPb ha−1 y−1 and 60.4 ± 10.5 gAs ha−1 y−1), but contrasting controls on this release. Suspended particulates account for the majority of lead export, whereas the aqueous phase dominates arsenic export. Lead release is driven by geomorphological processes and is a primary effect of erosion. Arsenic release is driven by the formation of a redox-dynamic zone in the peat associated with water table drawdown, a secondary effect of gully erosion. Degradation of peatland environments by natural and anthropogenic processes has the potential to release the accumulated pool of legacy contaminants to surface waters.

Historical Records Research and Analysis Becoming Increasingly Important in World War II Legacy Contamination Cases as Aging World War II Fact Witnesses Are Dying Off at an Alarming Rate

Historical Records Research and Analysis Becoming Increasingly Important in World War II Legacy Contamination Cases as Aging World War II Fact Witnesses Are Dying Off at an Alarming Rate

Evolutionary toxicology: contaminant-induced genetic mutations in mosquitofish from Sumgayit, Azerbaijan

This study builds on a long-term program that has shown Sumgayit, Azerbaijan to contain wetlands with high levels of a diversity of chemical contaminants. Previous contaminant and biomarker studies of turtles and frogs showed a correlation between somatic chromosomal damage and chemical contaminants at Sumgayit. The objective of this study was to determine if a recently arrived species (mosquitofish) has genetic impacts similar to native species (marsh frogs) thus confirming the pattern is not the result of historical events such as glacial cycles, but is associated with recent chemical contamination. Nucleotide sequences of the mtDNA control region of invasive mosquitofish (Gambusia holbrooki) from Sumgayit were compared to mosquitofish from pristine sites in Europe and Azerbaijan and to native North American populations. Persistent heteroplasmy for a hyper-mutable simple sequence repeat and low haplotype and nucleotide diversities were observed in all invasive populations. However, Sumgayit possessed four de novo haplotypes and heteroplasmic conditions. All of the observed variable nucleotide positions were within or adjacent to a cytosine mononucleotide repeat. This repeat was within a conserved secondary structure; the region likely undergoes expansion and contraction at a rate sufficient to prevent fixation of the common 1/3 heteroplasmy. Whereas the 1/3 heteroplasmy appeared coincident with the establishment of mosquitofish in Europe, other forms of heteroplasmy resulted from contaminant-induced de novo mutations in Sumgayit. We conclude that Sumgayit is a mutational hotspot caused by legacy contaminants from chemical factories from the era of the Soviet Union.

Flame retardants and legacy contaminants in polar bears from Alaska, Canada, East Greenland and Svalbard, 2005–2008

Flame retardants and legacy contaminants were analyzed in adipose tissue from 11 circumpolar polar bear ( Ursus maritimus) subpopulations in 2005–2008 spanning Alaska east to Svalbard. Although 37 polybrominated diphenyl ethers (PBDEs), total-(α)-hexabromocyclododecane (HBCD), 2 polybrominated biphenyls (PBBs), pentabromotoluene, pentabromoethylbenzene, hexabromobenzene, 1,2- bis(2,4,6-tribromophenoxy(ethane) and decabromodiphenyl ethane were screened, only 4 PBDEs, total-(α-)HBCD and BB153 were consistently found. Geometric mean ∑ PBDE (4.6–78.4 ng/g lipid weight (lw)) and BB153 (2.5–81.1 ng/g lw) levels were highest in East Greenland (43.2 and 39.2 ng/g lipid weight (lw), respectively), Svalbard (44.4 and 20.9 ng/g lw) and western (38.6 and 30.1 ng/g lw) and southern Hudson Bay (78.4 and 81.1 ng/g lw). Total-(α)-HBCD levels (< 0.3–41.1 ng/g lw) were lower than ∑ PBDE levels in all subpopulations except in Svalbard, consistent with greater European HBCD use versus North American pentaBDE product use. ∑ PCB levels were high relative to flame retardants as well as other legacy contaminants and increased from west to east (1797–10,537 ng/g lw). ∑ CHL levels were highest among legacy organochlorine pesticides and relatively spatially uniform (765–3477 ng/g lw). ∑ DDT levels were relatively low and spatially variable (31.5–206 ng/g lw). However, elevated proportions of p,p′-DDT to ∑ DDT in Alaska and Beaufort Sea relative to other subpopulations suggested fresh inputs from vector control use in Asia and/or Africa. Comparing earlier circumpolar polar bear studies, ∑ PBDE, total-(α)-HBCD, p,p′-DDE and ∑ CHL levels consistently declined, whereas levels of other legacy contaminants did not. International regulations have clearly been effective in reducing levels of several legacy contaminants in polar bears relative to historical levels. However, slow or stalling declines of certain historic pollutants like PCBs and a complex mixture of “new” chemicals continue to be of concern to polar bear health and that of their arctic marine ecosystems.

Efficacy of non‐toxic surfaces to reduce bioadhesion in terrestrial gastropods

Invasive species are described as the greatest threat to biodiversity, after habitat destruction and climate change, potentially imposing economic impacts and indigenous species impairment. Commonly applied chemical controls present the potential for legacy contamination and non-target organism injury. This study investigated the effects of different substrates and novel topographical surfaces on the behavioral and mechanical associations of the terrestrial gastropod Otala lactea. The gastropod preferentially aestivated on rough glass (61% increase, P < 0.01) relative to smooth glass but avoided a cross-patterned surface tessellation on silicone (82% reduction, P < 0.01) relative to smooth silicone. Significant deviations in turning behavior were found on the cross-patterned topographical surface and hydrophobic Teflon surfaces. The strongest correlation with gastropod adhesion strength to surfaces was found for surface elastic modulus (R = 0.88, P = 0.03), followed by hydrophobicity (R = - 0.71, P = 0.14), but no relationship with roughness (P = 0.36). Preliminary data suggest surface roughness controlled aestivation behavior while elastic modulus (surface flexibility) controlled adhesion strength. In spite of greater adhesion to high-modulus materials, surface modulus was not a statistically significant controlling factor on gastropod aestivation preference. Understanding and exploiting the behavioral and mechanistic cues that organisms use while attaching to surfaces may lead to more environmentally benign control approaches.

Kinetic differences of legacy organochlorine pesticides and polychlorinated biphenyls in Vietnamese human breast milk

The present study investigated the current contamination status and evaluated several kinetic-related features of organochlorine pesticides (OCPs) and PCBs in human breast milk collected from northern Vietnam. The variation in the levels of these contaminants was found to be strongly associated with total lactation time and dietary habits. OCPs exhibited the characteristics of steadily declining compounds: the overall levels of DDTs and HCHs in the population decreased with a half-time of only 5 years and it can be suggested that OCPs depurated relatively fast with breastfeeding (5% per month). PCBs were slower in both regards, with a temporal decrease half-time of 12 years and a suggested depuration rate via breastfeeding of 2.5% per month, indicating that the exposure level was still high relative to the human body burden. It was found that the PCB exposure levels of infant from breastfeeding exceeded the reference dose, and this situation may continue for the next two or three decades. Knowledge of these kinetic-related characteristics not only is useful for risk assessment and prediction of future trends of legacy contaminants but also may provide insight regarding similar kinetic processes of emerging persistent pollutants.

Trends of legacy and emerging-issue contaminants in Lake Simcoe fishes

The temporal trends of legacy contaminants (i.e., mercury, PCBs, and DDT) and the current status of both legacy and emerging-issue (polybrominated diphenyl ethers (PBDEs) and polychlorinated naphthalenes (PCNs)) chemicals were examined in sport fishes from Lake Simcoe. Mercury concentrations decreased statistically significantly with time in lake trout, cisco, smallmouth bass, and yellow perch, consistent with assumed loading patterns. In contrast, mercury in largemouth bass, northern pike, and walleye showed a random relationship with time and increased statistically significantly with time in whitefish. Such differences among species suggest the influence of food-web processes (e.g., nutrient inputs and invasive species) in controlling temporal patterns of mercury in Lake Simcoe fishes. Concentrations of total-PCB and total-DDT in lake trout and whitefish generally followed an exponential decay pattern, with concentrations stabilizing during the 1990s. Current concentrations of legacy contaminants were, for the most part, below fish consumption guidelines for the general population. The risk associated with fish consumption to the sensitive population of women of child bearing age and children under 15 was of more concern for the larger, predatory fishes due to elevated mercury and PCBs. Recent measurements of PCNs and PBDEs were not of concern to Lake Simcoe sport fish consumers, although continued monitoring of fish contaminant levels is recommended in light of possible further loadings to this system. Contaminant related issues in Lake Simcoe sport fishes were of less or similar concern compared with the North American Great Lakes.

Neurological Disease Rises from Ocean to Bring Model for Human Epilepsy to Life

Domoic acid of macroalgal origin was used for traditional and medicinal purposes in Japan and largely forgotten until its rediscovery in diatoms that poisoned 107 people after consumption of contaminated mussels. The more severely poisoned victims had seizures and/or amnesia and four died; however, one survivor unexpectedly developed temporal lobe epilepsy (TLE) a year after the event. Nearly a decade later, several thousand sea lions have stranded on California beaches with neurological symptoms. Analysis of the animals stranded over an eight year period indicated five clusters of acute neurological poisoning; however, nearly a quarter have stranded individually outside these events with clinical signs of a chronic neurological syndrome similar to TLE. These poisonings are not limited to sea lions, which serve as readily observed sentinels for other marine animals that strand during domoic acid poisoning events, including several species of dolphin and whales. Acute domoic acid poisoning is five-times more prominent in adult female sea lions as a result of the proximity of their year-round breeding grounds to major domoic acid bloom events. The chronic neurological syndrome, on the other hand, is more prevalent in young animals, with many potentially poisoned in utero. The sea lion rookeries of the Channel Islands are at the crossroads of domoic acid producing harmful algal blooms and a huge industrial discharge site for dichlorodiphenyltrichloroethane (DDTs). Studies in experimental animals suggest that chronic poisoning observed in immature sea lions may result from a spatial and temporal coincidence of DDTs and domoic acid during early life stages. Emergence of an epilepsy syndrome from the ocean brings a human epilepsy model to life and provides unexpected insights into interaction with legacy contaminants and expression of disease at different life stages.

Transuranic waste remediation in Idaho: Pit 9, failed contracts, and lawsuits

AbstractThe U.S. Department of Energy (US DOE) remediation responsibilities include its Idaho National Laboratory. In 1989, the U.S. Environmental Protection Agency placed the Idaho site on its National Priority List for environmental cleanup. The site's contamination legacy from operations included inactive reactors and other structures, spent nuclear fuel, high‐level liquid radioactive wastes, calcined radioactive wastes, and transuranic wastes. Documents governing cleanup include a 1995 Settlement Agreement between the US DOE and the US Navy as responsible parties, and the State of Idaho. The Subsurface Disposal Area contains buried transuranic wastes, lies above the East Snake River Plain Aquifer, and could be the “site's most nettlesome cleanup issue,” according to an outside observer. This article describes the technical and legal difficulties that have been encountered in remediating this area. © 2010 Wiley Periodicals, Inc.

On the Rate of Decline of Persistent Organic Contaminants in Lake Trout (Salvelinus namaycush) from the Great Lakes, 1970−2003

Thirty-four years of data from the Great Lakes Fish Monitoring Program (GLFMP) show significant changes in the behavior of most contaminants in lake trout over time consistent with changes in contaminant inputs following regulation and remediation. Polybrominated diphenyl ethers (PBDEs) show positive apparent first-order rate constants falling to near zero. Dieldrin shows relatively unchanging half-lives of around 10 years except in Lake Superior (approximately 25 years). Mirex, consistently detected only in Lake Ontario fish, shows a slow decrease until the 1990s, when remediation of a source site occurred, after which half-lives are 2-3 years. Half-lives of oxychlordane, polychlorinated biphenyls (PCBs), and dichloro-diphenyl-trichlorethane (DDT) and its metabolites were typically 3-6 years until the mid 1980s; since then, the newest data confirm half-lives are usually around 15-30 years. For PCBs, an increasing half-life is found in other media as well. Changes in food web structure, fishery dynamics, and climate undoubtedly affect concentrations but cannot explain observed long-term trends across several media. Concentrations of legacy contaminants in the Great Lakes are likely to continue to decline only slowly and pose a health concern for decades without identifying and containing remaining sources.

REMEDIATION: A Break in the Clouds: Rebuilding New Orleans

Rebuilding housing in New Orleans after Hurricane Katrina has involved a massive cleanup effort: removal of millions of tons of debris, thousands of potentially hazardous appliances, and tons of hazardous waste along with consideration of underground storage tanks, Superfund sites, and disabled drinking water systems. Now nonprofit groups involved in the rebuilding effort in the city’s hardest-hit neighborhoods, including the Lower Ninth Ward, are working to ensure new homes are built on safe sites, and their efforts are starting to pay off. After Katrina struck in August 2005, more than half of New Orleans’ homes sat for days or weeks in up to 6 feet of floodwater. Environmental damage was severe, inside and out; one study published in the December 2006 issue of EHP found interior mold and endotoxin levels similar to agricultural environments. Citywide, thousands of houses were demolished. [For more information on the hurricane’s environmental health sequelae, see “In Katrina’s Wake,” EHP 114:A32–A39 (2006).] The New Orleans Office of Community Development has worked with nonprofit builders to restore neighborhoods with a view to environmental health and justice. One group, the Make It Right Foundation, was established in 2007 to build homes in the city’s most impoverished neighborhoods. The foundation’s goal, says executive director Tom Darden, is 150 new energy-efficient homes built with low-toxicity materials, each priced under $150,000. To start, Make It Right assessed the neighborhood’s environmental conditions with analyses from the U.S. Environmental Protection Agency (EPA) and the Tulane/Xavier Center for Bioenvironmental Research. Howard Mielke, a research professor at the center, had mapped the city’s soils before Katrina using a high-density sampling protocol, including collection of more than 5,000 samples across the city between 1998 and 2000. The main hazard he found, as reported in the December 2008 issue of Environmental Geochemistry and Health, was soil lead—up to 1,700 ppm in some locations. This so-called legacy contamination came from old lead-based paint as well as decades of residue from leaded gasoline and other sources, similar to other cities. In other neighborhoods Mielke still finds lead levels of 1,000–1,700 ppm. “Kids are playing in this stuff,” he says. [For more information on legacy lead contamination, see “Lead in Air: Adjusting to a New Standard,” p. A76 this issue.] Make It Right settled on small-scale housing on a 14-block area where the main hazard found was high soil lead (around 200 ppm, or half the EPA remediation threshold for play areas of 400 ppm). Adopting guidelines proposed in a paper Mielke co-authored in the 15 April 2006 issue of Environmental Science & Technology, Make It Right and another nonprofit, Global Green, added a clean 6- to 12-inch layer of river alluvium and landscaping to remediate the soil. Although the lead and other heavy metal contaminants were well below action levels, says Darden, the foundation made a policy of doubling the recommended depth of added clean soil “to be on the safe side.” Blocks of buildings in the part of the Lower Ninth Ward where Make It Right focused were reduced to bare concrete slabs by the spring of 2007 when they broke ground for rebuilding. The builders ground up concrete demolition waste, Darden says, and recycled it onsite into stormwater retention boxes, driveways, and stone gardens. By focusing on new home construction, Make It Right obviated the need to remediate interiors. They examined all building materials for low emissions and optimal recyclability. That included using structurally insulated panels made of wood and high-density insulation foam for less moisture absorption than gypsum-based drywall. By mid-December 2009, the foundation had completed 16 houses, all of which have been occupied. Another 20 are under construction, and there are plans to break ground on 10 more in coming months. Mielke says other cities should follow New Orleans’ model of soil testing and cleanup. “Every city in the country needs to be mapped really well.” Of the lead-contaminated soil he adds, “You can find it in any city today, and it has major impact on children’s health.”

Assessment of Health and Ecological Impact of Policy on a Legacy Contamination Case Study

Background and Objective To investigate the effect of policy decisions on the health and ecological impact of pollution in an industrial area. Methods A sustainability assessment methodology is applied to study the impacts of pollution in an industrial area of Bristol, UK. The effects of several regulatory/policy-related changes on a smelting facility sited in Avonmouth are investigated. Impacts considered in the investigation relate to levels of air pollution, human health effects and impacts on the local ecology. In this study the main driver or key question addressed is: what are the implications of various emission policies on ecological and health impacts? Several scenarios which represent a suite of regulatory changes imposed on the smelter over the operating period are considered. Firstly, a scenario models fate and transport of emissions with real site data. A second scenario considering constant emissions at 2002 levels investigates the impact of the smelter if a high level of intervention had been made from the start of the operations. A third scenario with constant emissions at peak levels allows consideration of the potential impacts if none of the interventions had been implemented. Results Actual Cd, PM10, As, Zn and Pb emissions data and associated information on the operating parameters and regulatory policies during each stage of the operating period are identified. Life cycle assessment modelling is carried out to examine the environmental burdens and associated life cycle impacts of the smelting operations on the local area and the wider environment. Air dispersion/deposition modelling is performed to identify the fate and transport of pollutants in the surrounding area. Results of this modelling work are then used in ecological impact assessment and human health impact analysis. Conclusion Analysis of the scenarios considered allows an assessment of the impact of the policy decisions on human and ecological health.

Use of near surface geophysics in urban regeneration focused on the UK\'s mining and industrial contamination legacy

&lt;P align=justify&gt;Peter Styles and Nigel J. Cassidy argue the case for non-invasive subsurface investigative methods in site remediation or reclamation projects involving the UK\&apos;s legacy of mining and industrial contamination.&lt;/P&gt

Historical record of mercury contamination in sediments from the Babeni Reservoir in the Olt River, Romania

Mercury (Hg) is a ubiquitous and hazardous contaminant in the aquatic environment showing a strong biomagnification effect along the food chain. The most common transfer path of Hg to humans is contaminated fish consumption. In severely exposed humans, Hg poisoning may lead to damage in the central nervous system. Thus, it is important to examine current and past contamination levels of Hg in aquatic milieu. The Olt River is the largest Romanian tributary of the Danube River. The use of Hg as an electrode in a chlor-alkali plant contributed to the contamination of the aquatic environment in the Rm Valcea region. The purpose of this study was to compare the current state of Hg contamination with the past contamination using a historical record obtained from a dated sediment core from one of the Olt River reservoirs (Babeni) located downstream from the chlor-alkali plant. To our knowledge, no published data on Hg contamination in this region are available. The Babeni Reservoir was selected for this study because it is situated downstream from the chlor-alkali plant, whilst the other reservoirs only retain the pollutants coming from the upstream part of the watershed. Preliminary analyses (unpublished) showed high Hg concentrations in the surface sediment of the Babeni Reservoir. One core was taken in the upstream Valcea Reservoir to provide a local background level of Hg concentrations in sediments. Sediment texture was uniform in the cores from both reservoirs. Laminated sediment structure, without any obvious discontinuities, was observed. Hg concentrations in the sediment core from the Valcea Reservoir were low and constant (0.01-0.08 mg/kg). In Babeni Reservoir sediments, Hg concentrations were very high in the deeper core section (up to 45 mg/kg in the longest core) and decreased to lower concentrations toward the top of the cores (1.3-2.4 mg/kg). This decrease probably reflects technological progress in control of emissions from the Hg-cell-based chlor-alkali industry. Two strong peaks could be distinguished in older sediments. The mean rate of sedimentation (5.9 cm/year) was calculated from the depth of the (137)Cs Chernobyl peak. This was in good agreement with the sedimentation rate estimated at this site from a bathymetric study. Assuming a constant sedimentation rate, the two Hg peaks would reflect two contamination events in 1987 and 1991, respectively. However, it is also possible that the two peaks belong to the same contamination event in 1987 but were separated by a sediment layer richer in sand and silt. This layer had a low Hg concentration, which can be interpreted as a mass deposition event related to a major flood bringing Hg-free sediments. Whilst the chlor-alkali plant partly switched to a cleaner technology in 1999, no obvious decrease of Hg concentrations was observed in recent decade. Results from the sediment core reflected the historical trend of Hg release from the chlor-alkali plant, revealed important contamination episodes and confirmed a legacy of contamination of Hg in recent sediments even if the concentrations of Hg decreased toward the surface due to a more efficient emission control. Although the Hg concentrations in Babeni Reservoir sediments were extremely high in the late eighties and they remain one order of magnitude higher in the surface sediments than in sediments from the upstream reservoir, little is known about the transfer of Hg to the biota and human population. Our initial measurements indicate the presence of monomethyl-Hg (MMHg) in pore water, but further studies are necessary to evaluate fluxes of MMHg at the sediment-water interface. Samples of fish and hair from various groups of the local population were recently collected to evaluate the potential hazard of Hg contamination to human health in the Rm Valcea region.

PCDDs, PCDFs, PCBs, OC pesticides and mercury in fish and osprey eggs from Willamette River, Oregon (1993, 2001 and 2006) with calculated biomagnification factors

The osprey (Pandion haliaetus) population nesting along the main stem Willamette River and lower Santiam River was first studied to evaluate contaminants and reproductive rates in 1993 when 78 occupied nests were present. By 2001, the population increased to 234 occupied nests, a 13.7% annual rate of population increase. A sample egg was collected from each of a series of nests along the Upper River (river mile 55-187) in 1993, 2001 and 2006 to evaluate trends of persistent contaminants (organochlorine [OC] pesticides, polychlorinated biphenyls [PCBs], polychlorinated dibenzo-p-dioxins [PCDDs], and polychlorinated dibenzofurans [PCDFs]). Nearly all OC pesticide residues decreased significantly, e.g., p, p'-DDE (DDE) from 2,350 to 1,353 to 210 microg/kg wet weight (ww). PCBs followed a similar pattern over time, e.g., SigmaPCBs 688 to 245 to 182 microg/kg ww, while PCDDs and PCDFs showed a more precipitous decline (often 85-95%) between 1993 and 2001, with no egg analyses warranted in 2006. During 2001-2002, sample osprey eggs were also collected from nests at three Headwater Reservoirs and two lower reaches (Newberg Pool and Tidal Portland) of the Willamette River, as well as the lower portion of the Santiam River to evaluate spatial residue patterns. Significant differences were seldom detected among the different sampling areas for OC pesticides (probably due to small sample sizes), although higher concentrations were often seen in the lower reaches, e.g., DDE 901 microg/kg ww (Headwater Reservoirs), 1,353 (Upper River), 1,384 (Newberg Pool) and 2,676 (Tidal Portland). PCB congener concentrations in eggs were usually higher in the Tidal Portland reach than at other locations and often significantly higher than at the Headwater Reservoirs or Upper River. Mercury (first analyzed in eggs in 2001), PCDDs and PCDFs were extremely low in 2001/2002 with no significant spatial patterns. Whole fish composite samples of largescale sucker (Catastomus macrocheilus) and northern pikeminnow (Ptychocheilus oregonensis), which account for about 90% of the biomass in the diet of this osprey population, were also collected from the Willamette River in 1993 and 2001 and analyzed for the same contaminants as osprey eggs. Contaminant residues in fish from the Upper River decreased between 1993 and 2001, paralleling findings for osprey eggs. Likewise, spatial patterns for fish residues paralleled findings for osprey eggs from the different reaches in 2001. A second empirical estimate of biomagnification factors (BMFs) from fish to osprey eggs for OC pesticides, PCBs, PCDDs and PCDFs (ww and lipid weight [lw] basis) was calculated based on residue data collected in 2001. The two independent BMF estimates (1993 and 2001) for each contaminant from the Upper River provide a measure of consistency, e.g., DDE (ww) 87 and 79, (lw) 103 and 112; SigmaPCBs (ww) 11 and 8.4, (lw) 13 and 12. Mercury did not biomagnify from fish to osprey eggs (BMF = 0.60). Legacy contaminants investigated had limited (perhaps only DDE), if any, effects on reproductive success of the increasing osprey population nesting along the Willamette River by 2001.

Predicting the Congener-Specific Environmental Behaviour of Perfluorinated Acid Contaminants Using Semi-Empirical Computational Methods

AbstractPerfluorinated acids (PFAs) are contaminants detected worldwide in a range of abiotic and biotic environmental matrices. The two major classes of PFAs include the perfluorinated carboxylic acids (PFCAs) and perfluorinated sulfonic acids (PFSAs), both of which are considered persistent and potentially bioaccumulative. Current research and regulatory efforts are focussed on the straight-chain members of each PFA class and homologue group, primarily because these congeners are the major components of technical mixtures and are also available as pure standards. However, the numerous potential branched congeners in each PFA class represent a poorly understood family of environmental contaminants whose environmental and toxicological properties may be more important than the more prevalent straight-chain members. To help broaden the current understanding of PFA environmental fate and toxicology, semi-empirical computational methods were used predict fundamental physico-chemical properties of all potential C4 to C8 PCFA and PFSA congeners. Established quantitative structure-activity models for other multi-class emerging and legacy contaminants were applied to estimate key parameters related to the toxicology, environmental partitioning, and abiotic and biotic degradation mechanisms for each PFA class. The findings provide guidance for developing new analytical methods for separating and identifying PFAs in environmental and technical mixtures, prioritizing efforts on synthesizing authentic standards, and focussing toxicological studies on the congeners most likely to be of concern.

Biomarker Responses and Decreasing Contaminant Levels in Ringed Seals (Pusa hispida) from Svalbard, Norway

Blubber was analyzed for a wide range of contaminants from five subadult and eight adult male ringed seals sampled in 2004, namely, for polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), toxaphenes, chlordanes, dichlorodiphenyldichloroethylene (DDE), and polybrominated diphenylethers (PBDEs). Contaminant levels were compared to previously sampled animals from the same area, as well as data from literature for other arctic wildlife species from a wide variety of locations. Ringed seals sampled in 2004 showed 50–90% lower levels of legacy contaminants such as PCBs and chlorinated pesticides compared to animals sampled in 1996 of similar age (14 subadults and 7 adult males), indicating that the decline of chlorinated contaminants observed during the 1990s in a variety of arctic wildlife species is continuing into the 21st century. The results also indicated that PBDE declined in ringed seals; levels in 2004 were about 70–80% lower than in animals sampled in 1998. This is one of the first observations of reduced exposure to these compounds and might be a first indication that restrictions of production and use of these contaminants have resulted in lower exposures in the Arctic. The PCB pattern shifted toward the less chlorinated (i.e., less persistent) PCBs, especially in adult ringed seals, possibly as a result of reduced overall contaminant exposures and a consequently lower cytochrome P-450 (CYP) induction, which results in a slower metabolism of less persistent PCBs. The overall effect would be relative increases in the lower chlorinated PCBs and a relative decreases in the higher chlorinated PCB. Possibly due to low exposure and consequent low induction levels, ethoxyresorufin O-deethylation (EROD) activity proved to be a poor biomarker for contaminant exposure in ringed seals in the present study. The close negative correlation (r 2 = 70.9%)between EROD activity and percent blubber indicates that CYP might respond to increased bioavailability of the contaminant mixtures when they are mobilized from blubber during periods of reduced food intake.