The Fate of Chemically Dispersed and Untreated Crude Oil in Arctic Benthic Biota

Subtidal benthic biota were monitored for petroleum hydrocarbons following two experimental oil spills at Cape Hatt, N.W.T., Canada. In one spill oil was chemically dispersed into the water column, and in the other oil was released onto the water surface and allowed to strand on the shoreline. In addition to baseline samples, samples were collected immediately after the oil releases, two to three weeks after and one and two years after. Initial observations did not distinguish between effects of the surface and dispersed releases. Total oil content and hydrocarbon compositional analyses were conducted to investigate patterns of uptake and depuration for five different arctic species: Astarte borealis, Macoma calcarea, Mya truncata, Serripes groenlandicus and Strongylocentrotus droebachiensis. Filter-feeding species took up oil rapidly from the water column, while deposit-feeding species took up oil less rapidly from the sediments. All species depurated most of the oil after one year, but after two years the deposit feeders appeared to be taking up more oil from sediments contaminated by stranded oil from the surface oil release.Key words: oil, petroleum, determination, benthos, weathering, degradation, depuration, ArcticMots clés: pétrole, pétroliers, détermination, benthos, dégradation, décomposition, dépuration, arctique

Stable isotope food-web analysis and mercury biomagnification in polar bears ( Ursus maritimus )

Mercury (Hg) biomagnification occurs in many ecosystems, resulting in a greater potential for toxicological effects in higher-level trophic feeders. However, Hg transport pathways through different food-web channels are not well known, particularly in high-latitude systems affected by the atmospheric Hg deposition associated with snow and ice. Here, we report on stable carbon and nitrogen isotope ratios, and Hg concentrations, determined for 26, late 19th and early 20th century, polar bear ( Ursus maritimus ) hair specimens, collected from catalogued museum collections. These data elucidate relationships between the high-latitude marine food-web structure and Hg concentrations in polar bears. The carbon isotope compositions of polar bear hairs suggest that polar bears derive nutrition from coupled food-web channels, based in pelagic and sympagic primary producers, whereas the nitrogen isotope compositions indicate that polar bears occupy > fourth-level trophic positions. Our results show a positive correlation between polar bear hair Hg concentrations and δ 15 N. Interpretation of the stable isotope data in combination with Hg concentrations tentatively suggests that polar bears participating in predominantly pelagic food webs exhibit higher mercury concentrations than polar bears participating in predominantly sympagic food webs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73930/1/j.1751-8369.2009.00114.x.pd

Comprehensive re-analysis of archived herring gull eggs reconstructs historical temporal trends in chlorinated hydrocarbon contamination in Lake Ontario and Green Bay, Lake Michigan, 1971-1982

Herring gull egg homogenates collected between 1971 and 1982 from a colony in central Lake Ontario (Scotch Bonnet Island) and from a colony in central Green Bay, Lake Michigan (Big Sister Island) were archived in the Canadian Wildlife Service Specimen Bank. Pooled samples (N = 10) were exhaustively analyzed in 1993 for a wide range of individual chlorinated hydrocarbon contaminant (CHC) compounds: DDT, mirex and chlordane compounds and metabolites, chlorobenzenes (CBzs), dieldrin, chlorostyrenes (CSs), hexachlorocyclohexanes (HCHs), polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), and 87 PCB congeners, including the TCDD-like non-ortho and mono-ortho congeners. PCBs and DDTs were the dominant residues in eggs from both Lake Ontario (31-242 mg kg-1 and 9-64 mg kg-1) and Green Bay (34-133 mg kg -1 and 14-91 mg kg-1). ΣPCBs declined by a factor of 4-5 and DDTs a factor of 4-7 at both colonies between 1971 and 1982. Lake Ontario eggs had significantly higher residues of 2,3,7,8-TCDD (0.2-2.0 μg kg-1), HCBz (0.1-4.7 mg kg-1), OCS (0.03-0.45 mg kg -1), three HpCSs (0.13-0.97 mg kg-1), mirex and mirex photodegradation products (2.1-9.2 mg kg-1) than Green Bay eggs. HCBz levels in Lake Ontario eggs declined a factor of 40, TCDD and chlorostyrenes a factor of 8-10, and mirex a factor of 4 between 1971-1978. Green Bay eggs had slightly higher levels of chlordane-related compounds, dieldrin and β-HCH than Lake Ontario eggs. There were no consistent or strong trends in residue levels of these pesticides, PCDDs (except TCDD) and PCDFs in either lake, indicating that rates of input and removal of these CHCs in the lakes were much closer in the early 1970s than was the case for the other compounds

Identification of 4-hydroxyheptachlorostyrene in polar bear plasma and its binding affinity to transthyretin : a metabolite of octachlorostyrene?

A new compound, 4-hydroxyheptachlorostyrene (4-OH-HpCS), was identified as a major component in the chlorinated phenolic compound fraction of polar bear plasma. The structure was hypothesized to be 4-OH-HpCS based on mass spectral interpretation, the assumption that it was a metabolite of octachlorostyrene, and the similarity of the structure to hydroxylated polychlorinated biphenyls (OH-PCBs) identified in plasma. High-resolution, electron impact (EI) ionization mass spectrometry of the methylated compound indicated a molecular formula of C9H3OCl7 and major fragment ions of [M - 15] , [M - 35] , and [M - 43] , which was a mass spectral pattern identical to a synthesized and methylated 4-OH-HpCS standard. The identity was further confirmed by matching gas chromatography (GC) retention times on three different GC columns of differing polarity. Levels of 4-OH-HpCS ranged from 2.89 to 22.9 ng/g wet weight in polar bear plasma (N = 30) and constituted between 3.8 and 24.8␘f the total quantified level of chlorinated phenolic compounds. The mean ratio of 4-OH-HpCS to CB153 concentrations in polar bear plasma samples was 0.712 (± 0.580 SD), which suggests selective retention of the 4-OH-HpCS in plasma. The presumed mechanism of retention involves 4-OH-HpCS binding to transthyretin (TTR). The presence of TTR was confirmed for the first time in polar bear plasma by binding of 125I-thyroxine (T4), the natural ligand of TTR, to separated plasma proteins. The binding affinity of 4-OH-HpCS to human TTR was tested and found to be 1.1 relative to T4. This suggests that 4-OH-HpCS has the potential to disrupt T4 and retinol transport, by analogy to OH-PCBs with similar structure. Metabolism of octachlorostyrene (OCS) is the most likely source of 4-OH-HpCS. OCS was shown to be present at low concentrations in polar bear tissues as well as in plasma of ringed seal, the principal prey species of polar bears. The ratio of 4-OH-HpCS to OCS and 4-OH-HpCS to CB153 concentrations were 150- and 44-fold higher in polar bear plasma than in ringed seal plasma. This study indicates that the phenolic metabolites of relatively minor contaminants possess the capacity to bind to circulating proteins, and their significance as potential endocrine-disrupting agents may be underestimated

Dietary changes cause temporal fluctuations in polychlerinated biphenyl levels in herring gull eggs from Lake Ontario

After adjusting Lake Ontario herring gull egg PCB concentrations for the influence of time, an analysis was conducted to explain the remaining variation in annual egg PCB concentrations. In years with cold winters and/or high alewife abundance, egg PCB concentrations were greater than predicted. PCB levels were also greater than predicted in years when alewife condition was low. Increasing the proportion of alewives in the gull's diet may lead to increased PCB levels in eggs. Stable isotope analysis ([15N]/[14N]) of herring gull eggs provided evidence supporting this hypothesis. Consumption of alewives by gulls (as influenced by gull metabolism, alewife abundance/condition, end alewife overwinter mortality) and alewife population characteristics (growth rates and age distribution) may be the keys to explaining fluctuations in Lake Ontario herring gull egg PCB levels

A quarter century of environmental surveillance: The Canadian Wildlife Service's Great Lakes Herring Gull Monitoring Program

The Great Lakes Herring Gull Monitoring Program has annually provided information concerning levels of environmental contaminants in herring gull eggs since 1974, making it one of the longest running biomonitoring programs in the world. The program was initiated in response to observations of poor reproductive success in colonial waterbirds on the Great Lakes. Initial studies examined the role of halogenated hydrocarbons (HAHs) in causing this reproductive dysfunction. By the late 1970s, reproductive success in herring gulls had improved greatly and emphasis was placed on developing more sensitive indicators to measure the subtle effects associated with HAH exposure. Geographic and temporal trends in Great Lakes contamination were also elucidated. Analysis of herring gull tissues led to the identification of HAHs (mirex, photomirex, polynuclear aromatic hydrocarbons, chlorobenzenes, dioxins) previously undetected in Great Lakes upper trophic level biota. Data collected as part of this program have improved our understanding of contaminant sources and fate in the Great Lakes and have provided us with a means to assess our progress in controlling contaminant inputs. The extensive nature of this dataset has allowed detailed examination of the factors that regulate contaminant levels in this species. Most monitoring programs rely on less extensive datasets for the interpretation of environmental trends and may benefit from the mechanisms identified here. Research has also identified other stressors, e.g., dietary deficiencies, that may affect the success of Great Lakes herring gull populations. Ongoing monitoring of this species will continue to provide new insights into the dynamic Great Lakes ecosystem

Historical changes in PCB patterns in Lake Ontario and Green Bay, Lake Michigan, 1971 to 1982, from herring gull egg monitoring data

Patterns of PCB congener bioaccumulation were examined in archived herring gull (Larus argentatus) eggs collected from Big Sister Island in Green Bay, Lake Michigan, and Scotch Bonnet Island in Lake Ontario from 1971 to 1982 as part of the Canadian Wildlife Service's Great Lakes Herring Gull Monitoring Program. Concentrations of 97 PCB congeners were measured. From 1971 to 1982, ecological half-lives of most congeners, particularly the tri- through hexachlorobiphenyls, were greater in eggs from Green Bay than Lake Ontario. Comparing sum PCB levels in eggs collected in 1971 and 1982, concentrations declined 80% at Scotch Bonnet Island and 74% at Big Sister Island. PCB congener patterns were different in eggs from the two colonies. Principal components analysis showed that inter-site differences in congener patterns became more apparent after 1976. This indicated that regional PCB sources were the most influential in determining patterns of biologically-available PCBs during the 1971 to 1982 period in these two lakes, via recycling of historical PCBs from sediments or gradually decreasing loading. Trend analysis of selected congeners specific to Aroclors 1242, 1254, and 1260 revealed that the rapid decline of less chlorinated congeners, observed from 1971 to 1976 in Lake Ontario, was explained by a decrease in loading of Aroclor 1242 to the lake. At both colonies, ecological half life of the congeners was significantly (p < 0.001) correlated with log K(ow) and with -log HLC. Changes in PCB composition, after 1976 in Lake Ontario and from 1971 to 1982 in Green Bay, could be explained by differences in the physical behavior of individual congeners affecting removal by volatilization and sedimentation

Polychlorinated dibenzodioxins, dibenzofurans and non-ortho substituted polychlorinated biphenyls in caribou (Rangifer tarandus) from the Canadian Arctic

The presence of contaminants in the Arctic environment has raised concerns regarding levels in wildlife and possible effects on the health of wildlife populations. In addition, contaminants in wild foods are of particular concern to those people who rely on these foodstuffs for a significant portion of their diet. Among the most toxic contaminants found in the environment are the polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and non-ortho substituted polychlorinated biphenyls (NOPCBs). Few data exist documenting the levels of these compounds in Arctic terrestrial wildlife. In 1993, caribou samples were obtained from three herds in the Yukon Territory (Finlayson, Tay and Bonnet Plume) and from four herds in the Northwest Territories (Bathurst, Southampton Island, Cape Dorset and Lake Harbour). High resolution gas-chromatography/mass spectrometry was used to measure contaminant concentrations. Wet weight concentrations of PCDDs, PCDFs and NOPCBs were greater in fat tissue than in muscle and liver, however, concentrations in all tissues were extremely low. Lipid normalized concentrations were greater in muscle and liver than in fat, indicating that equilibrium partitioning is not the only process regulating tissue concentrations of these contaminants. There were no significant relationships between concentrations of individual congeners and caribou age. Concentrations of the non-ortho substituted PCBs #126 and #169 were greater in caribou from the eastern Arctic, although levels in all herds were low. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxic equivalents were also low in tissues from all herds. The presence of these compounds in the Arctic can likely be attributed to long-range atmospheric transport. The lev