Why do organochlorine differences between Arctic Regions vary among trophic levels?

Statistical analysis of organochlorine contaminants (OCs) in marine mammals has shown that, for most OCs, the European Arctic is more contaminated than the Canadian and U.S. Arctic. Recently, comparison of OC concentration ranges in seabirds, arctic cod (Boregadus saida), and zooplankton, found no difference between these regions. To address these inconsistencies, marine food web OC data from the European (central Barents Sea (CBS)) and Canadian Arctic (Northwater Polynya (NOW)) were simultaneously statistically analyzed. In general, concentrations of OCs were greater in seabirds and ringed seals (Phoca hispida) from the CBS as compared to the NOW; consistent with circumpolar trends observed in marine mammals. In contrast, levels of OCs were generally similar in zooplankton and arctic cod between the CBS and NOW. The main exception is HCH which had greater levels in the NOW across all trophic levels because of the greater proximity to sources in eastern Asia. The lack of differences in OC concentrations in zooplankton and Arctic cod from the European and Canadian Arctic suggest that regional differences in OC contamination in the Arctic have evened out. Reduced regional differences were not observed in marine mammals or seabirds because they are long-lived and also acquire contaminants from maternal transfer and hence reflect levels from the past when the European Arctic was more contaminated than the Canadian Arctic. In addition, seabirds may reflect exposure from other areas. This study highlights the potential problem of comparing spatial trends by using means and confidence intervals as compared to simultaneous statistical analysis of raw data. Differences in the spatial trends of OCs between trophic levels in the Arctic are important for consideration when assessing regional differences in spatial and temporal trends of discontinued and current-use contaminants. © 2005 American Chemical Society

Hydrocarbon Biogeochemical Setting of the Baffin Island Oil Spill Experimental Sites. III. Biota

A baseline for petroleum residues in the Cape Hatt region of Baffin Island in arctic Canada was obtained in anticipation of controlled oil releases of the Baffin Island Oil Spill (BIOS) Project. Tissue hydrocarbons in a variety of arctic marine species were dominated by biogenic hydrocarbons. UV/F analysis of tissues indicated an upper limit of petroleum residues in the low to sub micro g/g concentration range. PAHs were detected in samples in the low ng/g concentration range and revealed a distribution of the combustion type. The hydrocarbon baseline in the BIOS study area was found to be as low as might be found anywhere on earth and therefore ideally suited to the BIOS study.Key words: BIOS, arctic marine Canada, hydrocarbon baseline, organismsMots clés: BIOS, Arctique marin canadien, niveau de référence d’hydrocarbures, organisme

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

Persistence of organochlorine chemical residues in fish from the Tombigbee River (Alabama, USA): Continuing risk to wildlife from a former DDT manufacturing facility

Organochlorine pesticide and total polychlorinated biphenyl (PCB) concentrations were measured in largemouth bass from the Tombigbee River near a former DDT manufacturing facility at McIntosh, Alabama. Evaluation of mean p,p\u27- and o,p\u27-DDT isomer concentrations and o,p\u27- versus p,p\u27-isomer proportions in McIntosh bass indicated that DDT is moving off site from the facility and into the Tombigbee River. Concentrations of p,p\u27-DDT isomers in McIntosh bass remained unchanged from 1974 to 2004 and were four times greater than contemporary concentrations from a national program. Total DDT in McIntosh bass exceeded dietary effect concentrations developed for bald eagle and osprey. Hexachlorobenzene, PCBs, and toxaphene concentrations in bass from McIntosh also exceeded thresholds to protect fish and piscivorous wildlife. Whereas concentrations of DDT and most other organochlorine chemicals in fish have generally declined in the U.S. since their ban, concentrations of DDT in fish from McIntosh remain elevated and represent a threat to wildlife

Hexachlorocyclohexane (HCH) isomers and chiral signatures of α-HCH in the arctic marine food web of the Northwater Polynya

Concentrations of hexachlorocyclohexane (HCH) isomers (α,β, and γ) and enantiomer fractions (EFs) of α-HCH were determined in the Northwater Polynya Arctic marine food web. Relative food web structure was established using trophic level models based on organic δ15N values. Concentrations of HCH in the samples collected, including water, sediment, benthic invertebrates (four species), pelagic zooplankton (six species), Arctic cod, seabirds (seven species), and ringed seal, were in the range previously reported for the Canadian Arctic. The relative proportion of the HCH isomers varied across the food web and appeared to be related to the biotransformation capacity of each species. For invertebrates and fish the biomagnification factors (BMFs) of the three isomers were \u3e1 and the proportion of each isomer and the EFs of α-HCH were similar to water, suggesting minimal biotransformation. Seabirds appear to readily metabolize γ- and α-HCH based on low BMFs for these isomers, high proportions of β-HCH (62-96%), and high EFs (0.65-0.97) for α-HCH. The α- and β-HCH isomers appear to be recalcitrant in ringed seals based on BMFs \u3e1 and near racemic EFs for α-HCH. The β isomer appears to be recalcitrant in all species examined and had an overall food web magnification factor of 3.9. EFs of α-HCH and the proportion of β-HCH in Σ-HCH in the food web were highly correlated (r2 = 0.92) suggesting that EFs were a good indicator of a species capability to biotransform α-HCH

Using anthropogenic contaminants and stable isotopes to assess the feeding ecology of Greenland sharks

Organochlorine contaminants (OCs) are a large group of ubiquitous pollutants that have potential as tracers of ecological processes. To examine this utility, we measured OCs, stable isotopes of nitrogen (δ15N) and carbon (δ15C), and stomach contents in a large Arctic marine fish, the Greenland shark (Somniosus microcephalus), collected in the Davis Strait region to examine the feeding ecology of this little studied elasmobranch. Stable isotopes and OCs were also measured in the turbot (Reinhardtius hippoglossoides) and stable isotopes in the ringed seal (Phoca hispida) and harp seal (Pagophilus groenlandicus) to put the shark results in context. Values of δ15N suggest that the Greenland shark feeds at a similar trophic level as the turbot and ringed seal (about the fourth trophic level) and at a higher trophic level than harp seals, despite the presence of many turbot and a single ringed seal in the stomach contents of 14 sharks. Values of δ13C indicate that source of carbon in turbot and Greenland shark is of a more pelagic origin than in ringed and harp seals. High concentrations of biomagnifying OCs in the sharks compared with the turbot (concentration 10-100X lower) and ringed seals (3-10X lower) suggest that the sharks feed at a higher trophic level than implied by stable isotopes. High urea levels found in the tissues of sharks may influence δ15N values, resulting in an underestimate of shark trophic position, and requires additional study. The presence of a ringed seal in the stomach of one shark, relatively high levels of a contaminant metabolite (oxychlordane; slowly formed in fish) in some sharks, and high OC levels suggest that seals may be a common food item of some Greenland sharks. This study shows the utility of using OCs in ecological study and suggests caution when interpreting stable-isotope data as a single indicator of trophic position

Examination of the bioaccumulation of halogenated dimethyl bipyrroles in an Arctic marine food web using stable nitrogen isotope analysis

Concentrations of four possibly naturally produced organohalogens - 1,1′-dimethyl-3,3′,4-tribromo-4,5,5′-trichloro-2,2′- bipyrrole (DBP-Br3Cl3), 1,1′-dimethyl-3,3′,4,4′-tetrabromo-5,5′-dichloro-2, 2′-bipyrrole (DBP-Br4Cl2), 1,1′-dimethyl-3,3′,4,4′,5-pentabromo-5′-chloro-2, 2′-bipyrrole (DBP-Br5Cl) and 1,1′-dimethyl-3,3′,4,4′,5,5′-hexabromo-2,2′- bipyrrole (DBP-Br6) - were quantitated and the extent of their magnification through an entire Arctic marine food web [measured as integrated trophic magnification factors (TMFs)] were calculated. The food web consisted of three zooplankton species (Calanus hyperboreus, Mysis oculata, and Sagitta sp.), one fish species [Arctic cod (Boreogadus saida)], four seabird species [dovekie (Alle alle), black guillemot (Cepphus grylle), black-legged kittiwake (Rissa tridactyla), and glaucous gull (Larus hyperboreus)], and one marine mammal species [ringed seal (Phoca hispida)]. Trophic levels in the food web were calculated from ratios of stable isotopes of nitrogen (15N/14N). All halogenated dimethyl bipyrrole (HDBP) congeners were found to significantly (P \u3c0.02) biomagnify, or increase in concentration with trophic level in the invertebrate - fish - seabird food web. DBP-Br4Cl2 (TMF=14.6) was found to biomagnify to a greater extent than DBP-Br3Cl3 (TMF=5.2), DBP-Br5Cl (TMF=6.9), or DBP-Br6 (TMF=7.0), even though the Kow of DBP-Br4Cl2 was predicted to be lower than those of DBP-Br5Cl and DBP-Br6. None of the four HDBP congeners in ringed seals followed the general trend of increasing concentration with trophic level, which was possibly due to an ability of the seals to metabolize HDBPs. Crown Copyright © 2001 Published by Elsevier Science Ltd. All rights reserved