The Science of the Total Environment, 122 (1992) 75-134 Elsevier Science Publishers B.V., Amsterdam
75
Arctic marine ecosystem contamination D.C.G.
M u i r a, R . W a g e m a n n a, B . T . H a r g r a v e b, D . J . T h o m a s c, D.B. Peakall d and R.J. Norstrom a
aDepartment of Fisheries and Oceans, Central and Arctic Region, Winnipeg, MN R3T 2N6, Canada bDepartment of Fisheries and Oceans, Bedford Institute of Oceanography, Dartmouth, NS B2Y 4A2, Canada CAxys Group Ltd., Sidney, B.C. V8L 3S8, Canada aCanadian Wildlife Service, Environment Canada, Ottawa, ON K1A OH3, Canada (Accepted December 6th, 1991) ABSTRACT The current state of knowledge of levels, spatial and temporal trends of contaminants in the Arctic marine ecosystem varies greatly among pollutants and among environmental compartments. Levels of polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides and some heavy metals such as mercury and lead, in Arctic marine mammals and fish are relatively well documented because of the need for comparisons with biota in more polluted environments and interest in the contamination of native diets. Levels of heavy metals, alkanes, polyaromatic hydrocarbons (PAH) and OCs in the Arctic Ocean are comparable to uncontaminated ocean waters in the mid-latitudes. But concentrations of c~- and 7-hexachlorocyclohexane (HCHs) are higher in northern waters far removed from local sources, possibly because lower water temperature reduces transfer to the atmosphere. Bioaccumulation of OCs and heavy metals in Arctic marine food chains begins with epontic ice algae or phytoplankton in surface waters. Polychlorinated camphenes (PCC), PCBs, DDT- and chlordane-related compounds are the major OCs in marine fish, mammals and seabirds. Mean concentrations of most PCBs and OC pesticides in ringed seal (Phoca hispida) and polar bear (Ursus maritimus) populations in the Canadian Arctic are quite similar indicating a uniform geographic distribution of contamination, although c~-HCH showed a distinct latitudinal gradient in bears due to higher levels in zones influenced by continental runoff. Ringed seals from Spitzbergen have higher levels of PCBs, total DDT and polychlorinated dioxins/furans (PCDD/PCDFs). In contrast to other OCs, PCDD/PCDFs in Canadian Arctic ringed seals and polar bears were higher in the east/central Arctic than at more southerly locations. Remarkably high cadmium levels are found in kidney and liver of narwhal (Monodons monoceros) from western Baffin Bay (mean of 63.5 ~g g-:) and western Greenland waters (median of 39.5 ~g g-~). Mercury concentrations in muscle of ringed seal and cetaceans frequently exceed 0,5 txg g-: especially in older animals. Cadmium concentrations in polar bear liver increased from west to east, while mercury levels were higher in ringed seals from the western Canadian Arctic, which suggests that natural sources of these metals predominate. Studies of temporal trends in OCs in ringed seals and seabirds in the Canadian Arctic indicate PCB and DDT levels declined significantly from the early 1970s to the 1980s. There is a lack
76
D.C.G. MUIR ET AL.
of temporal trend data for other OC pesticides as well as for heavy metals and hydrocarbons. There is also a need for studies of the effects of elevated levels of contaminants such as mercury, and of low levels of exposure to PCBs, on top predators in the marine food chain and at the ecosystem level. Key words: artic marine ecosystem;marine mammals; marine fish; sea water; polychlorinated
biphenyls (PCBs); organochlorine pesticides;heavy metals; mercury;lead; cadmium; hydrocarbons; polychlorinated dioxins (PCDDs); polychlorinated furans (PCDFs) INTRODUCTION This review summarizes the current state of knowledge on levels, pathways of transport and bioaccumulation and sources of heavy metals, hydrocarbons, organochlorine (OC) pesticides, polychlorinated dioxins/furans (PCDD/PCDF) and polychlorinated biphenyls (PCBs) in the Arctic marine environment using literature available to early 1991. Interest in levels of contaminants in Arctic marine ecosystems arises from concerns that biota, especially top predators and aboriginal peoples utilizing marine mammals and fish in their traditional diet (Kinloch et al., 1992) may be adversely affected by chronic exposure to these pollutants (Dewailly et al., 1989). Studies of Arctic marine contamination have also been driven by the interest in understanding the behavior of pollutants, especially semi-volatile organic chemicals, in cold climates and by the need to compare levels of pollution in pristine areas with those in more polluted environments. In summarizing current information we have been particularly concerned with the following questions. Is the Arctic marine environment, as a result of its cold climate, a sink for semi-volatile organics, such as PCBs, PCDD/PCDFs, OC pesticides, polyaromatic hydrocarbons (PAH) and metals, such as mercury, emitted in the mid-latitudes (Ottar, 1981)? Are there identifiable temporal and geographic trends in contaminant burdens in Arctic marine biota? What are the contributions of anthropogenic or natural sources to hydrocarbon and metal contamination? How do contaminant levels generally compare with those in marine environments adjacent to industrialized areas in the mid-latitudes? Knowledge of Arctic marine ecosystem contamination varies greatly with the class of pollutant and with the environmental compartment. Information on the distribution of most contaminants in Arctic marine waters is limited, but levels of PCBs and related OC compounds, as well as mercury, in marine mammals and fish are relatively well documented. This spotty coverage of marine contamination reflects a focus on specific issues such as hydrocarbon contamination from oil and gas developments, contamination of native diets by PCBs and mercury, as well as the difficulties in obtaining adequate samples for trace analysis from this vast region.
ARCTIC MARINE ECOSYSTEM CONTAMINATION
77
Where substantial literature exists on Arctic marine contaminants, we have summarized it in tabular form and discussed the highlights in the text. C U R R E N T STATE OF K N O W L E D G E
The water column including sea ice Organochlorines Measurements of OCs in the Arctic Ocean have been made in Canadian (Hargrave et al., 1988, 1989; Bidleman et al., 1989), Norwegian (Gaul, 1991) and Soviet waters (Vlasov and Melnikov, 1990) (Table 1). Contaminant levels in snow are discussed in Barrie et al., (this volume). Hexachlorocyclohexanes (o~-HCH and 3,-HCH) were the predominate OCs in seawater from all Arctic locations. At the Ice Island (81°N, 97°W) in the Canadian Arctic, c~-HCH, 3,-HCH, hexachlorobenzene (HCB) and polychlorinated camphenes (PCCs or Toxaphene) were the primary OCs found in seawater, ice meltwater and snow samples taken during 1986 and 1987 (Table 1). In seawater, total hexachlorocyclohexanes (~:HCH) were present at concentrations far higher than those of other semi-volatile OCs and their concentrations in surface waters did not vary much over a 1-year period (means of 4300-5200 pg 1-1 in the 10-60 m depth). In May 1986, PCCs were present at concentrations about ten-fold lower than those of ~HCH and about ten-fold higher than those of HCB (Table 1). Dieldrin, DDT and PCBs were barely detectable in filtered waters (< 1 - < 4 pg 1-1), but were present in filterable particulates, unlike the more water soluble HCH isomers (Hargrave et al., 1988). In ice, c~-HCH (1.321 pg 1-l) was present at concentrations lower than in sea water (Table 1). The concentrations and proportions of all major OCs were lower in ice than in seawater suggesting that ice was not the source of these contaminants. HCB, chlordanes, DDT, DDE and PCBs were below levels of reliable quantification (< 2 pg 1-1) in ice but were measurable ( > 5 pg 1-1) in particulate matter collected from the bottom 10 cm of the ice. Gaul (1992) found concentrations of o~- and 3,-HCH isomers in seawater from two sites in European Arctic waters (73°30'N, 15°55'W and 77°N, 1°33'W) averaging 2.8 ng 1-1 (Table 1). Mean concentrations of EHCH in Arctic Ocean waters between the Norwegian coast and Spitzbergen did not decline significantly between 1979 and 1985. Gaul (1991) also found that concentrations of HCH isomers were lower in sea ice than in seawater while PCB congeners, DDT-related compounds and HCB were detectable in particulates associated with the ice. Vlasov and Melnikov (1990) found 2 H C H concentrations in surface seawater collected during 1986-1989 from the Kara, Laptev, East Siberian and Chukchi Seas that were similar to those observed in the Norwegian Sea
May 1986 May 1986
May 1986 Aug 1985 Aug 1985
May 1986 Aug 1986 Aug 1985 Aug 1985 1986-1989 1986-1989 1986-1989 1986-1989
Date
6 4
3 3 3
6 5 1 1 ? ? ? ?
N
75
Arctic marine ecosystem contamination D.C.G.
M u i r a, R . W a g e m a n n a, B . T . H a r g r a v e b, D . J . T h o m a s c, D.B. Peakall d and R.J. Norstrom a
aDepartment of Fisheries and Oceans, Central and Arctic Region, Winnipeg, MN R3T 2N6, Canada bDepartment of Fisheries and Oceans, Bedford Institute of Oceanography, Dartmouth, NS B2Y 4A2, Canada CAxys Group Ltd., Sidney, B.C. V8L 3S8, Canada aCanadian Wildlife Service, Environment Canada, Ottawa, ON K1A OH3, Canada (Accepted December 6th, 1991) ABSTRACT The current state of knowledge of levels, spatial and temporal trends of contaminants in the Arctic marine ecosystem varies greatly among pollutants and among environmental compartments. Levels of polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides and some heavy metals such as mercury and lead, in Arctic marine mammals and fish are relatively well documented because of the need for comparisons with biota in more polluted environments and interest in the contamination of native diets. Levels of heavy metals, alkanes, polyaromatic hydrocarbons (PAH) and OCs in the Arctic Ocean are comparable to uncontaminated ocean waters in the mid-latitudes. But concentrations of c~- and 7-hexachlorocyclohexane (HCHs) are higher in northern waters far removed from local sources, possibly because lower water temperature reduces transfer to the atmosphere. Bioaccumulation of OCs and heavy metals in Arctic marine food chains begins with epontic ice algae or phytoplankton in surface waters. Polychlorinated camphenes (PCC), PCBs, DDT- and chlordane-related compounds are the major OCs in marine fish, mammals and seabirds. Mean concentrations of most PCBs and OC pesticides in ringed seal (Phoca hispida) and polar bear (Ursus maritimus) populations in the Canadian Arctic are quite similar indicating a uniform geographic distribution of contamination, although c~-HCH showed a distinct latitudinal gradient in bears due to higher levels in zones influenced by continental runoff. Ringed seals from Spitzbergen have higher levels of PCBs, total DDT and polychlorinated dioxins/furans (PCDD/PCDFs). In contrast to other OCs, PCDD/PCDFs in Canadian Arctic ringed seals and polar bears were higher in the east/central Arctic than at more southerly locations. Remarkably high cadmium levels are found in kidney and liver of narwhal (Monodons monoceros) from western Baffin Bay (mean of 63.5 ~g g-:) and western Greenland waters (median of 39.5 ~g g-~). Mercury concentrations in muscle of ringed seal and cetaceans frequently exceed 0,5 txg g-: especially in older animals. Cadmium concentrations in polar bear liver increased from west to east, while mercury levels were higher in ringed seals from the western Canadian Arctic, which suggests that natural sources of these metals predominate. Studies of temporal trends in OCs in ringed seals and seabirds in the Canadian Arctic indicate PCB and DDT levels declined significantly from the early 1970s to the 1980s. There is a lack
76
D.C.G. MUIR ET AL.
of temporal trend data for other OC pesticides as well as for heavy metals and hydrocarbons. There is also a need for studies of the effects of elevated levels of contaminants such as mercury, and of low levels of exposure to PCBs, on top predators in the marine food chain and at the ecosystem level. Key words: artic marine ecosystem;marine mammals; marine fish; sea water; polychlorinated
biphenyls (PCBs); organochlorine pesticides;heavy metals; mercury;lead; cadmium; hydrocarbons; polychlorinated dioxins (PCDDs); polychlorinated furans (PCDFs) INTRODUCTION This review summarizes the current state of knowledge on levels, pathways of transport and bioaccumulation and sources of heavy metals, hydrocarbons, organochlorine (OC) pesticides, polychlorinated dioxins/furans (PCDD/PCDF) and polychlorinated biphenyls (PCBs) in the Arctic marine environment using literature available to early 1991. Interest in levels of contaminants in Arctic marine ecosystems arises from concerns that biota, especially top predators and aboriginal peoples utilizing marine mammals and fish in their traditional diet (Kinloch et al., 1992) may be adversely affected by chronic exposure to these pollutants (Dewailly et al., 1989). Studies of Arctic marine contamination have also been driven by the interest in understanding the behavior of pollutants, especially semi-volatile organic chemicals, in cold climates and by the need to compare levels of pollution in pristine areas with those in more polluted environments. In summarizing current information we have been particularly concerned with the following questions. Is the Arctic marine environment, as a result of its cold climate, a sink for semi-volatile organics, such as PCBs, PCDD/PCDFs, OC pesticides, polyaromatic hydrocarbons (PAH) and metals, such as mercury, emitted in the mid-latitudes (Ottar, 1981)? Are there identifiable temporal and geographic trends in contaminant burdens in Arctic marine biota? What are the contributions of anthropogenic or natural sources to hydrocarbon and metal contamination? How do contaminant levels generally compare with those in marine environments adjacent to industrialized areas in the mid-latitudes? Knowledge of Arctic marine ecosystem contamination varies greatly with the class of pollutant and with the environmental compartment. Information on the distribution of most contaminants in Arctic marine waters is limited, but levels of PCBs and related OC compounds, as well as mercury, in marine mammals and fish are relatively well documented. This spotty coverage of marine contamination reflects a focus on specific issues such as hydrocarbon contamination from oil and gas developments, contamination of native diets by PCBs and mercury, as well as the difficulties in obtaining adequate samples for trace analysis from this vast region.
ARCTIC MARINE ECOSYSTEM CONTAMINATION
77
Where substantial literature exists on Arctic marine contaminants, we have summarized it in tabular form and discussed the highlights in the text. C U R R E N T STATE OF K N O W L E D G E
The water column including sea ice Organochlorines Measurements of OCs in the Arctic Ocean have been made in Canadian (Hargrave et al., 1988, 1989; Bidleman et al., 1989), Norwegian (Gaul, 1991) and Soviet waters (Vlasov and Melnikov, 1990) (Table 1). Contaminant levels in snow are discussed in Barrie et al., (this volume). Hexachlorocyclohexanes (o~-HCH and 3,-HCH) were the predominate OCs in seawater from all Arctic locations. At the Ice Island (81°N, 97°W) in the Canadian Arctic, c~-HCH, 3,-HCH, hexachlorobenzene (HCB) and polychlorinated camphenes (PCCs or Toxaphene) were the primary OCs found in seawater, ice meltwater and snow samples taken during 1986 and 1987 (Table 1). In seawater, total hexachlorocyclohexanes (~:HCH) were present at concentrations far higher than those of other semi-volatile OCs and their concentrations in surface waters did not vary much over a 1-year period (means of 4300-5200 pg 1-1 in the 10-60 m depth). In May 1986, PCCs were present at concentrations about ten-fold lower than those of ~HCH and about ten-fold higher than those of HCB (Table 1). Dieldrin, DDT and PCBs were barely detectable in filtered waters (< 1 - < 4 pg 1-1), but were present in filterable particulates, unlike the more water soluble HCH isomers (Hargrave et al., 1988). In ice, c~-HCH (1.321 pg 1-l) was present at concentrations lower than in sea water (Table 1). The concentrations and proportions of all major OCs were lower in ice than in seawater suggesting that ice was not the source of these contaminants. HCB, chlordanes, DDT, DDE and PCBs were below levels of reliable quantification (< 2 pg 1-1) in ice but were measurable ( > 5 pg 1-1) in particulate matter collected from the bottom 10 cm of the ice. Gaul (1992) found concentrations of o~- and 3,-HCH isomers in seawater from two sites in European Arctic waters (73°30'N, 15°55'W and 77°N, 1°33'W) averaging 2.8 ng 1-1 (Table 1). Mean concentrations of EHCH in Arctic Ocean waters between the Norwegian coast and Spitzbergen did not decline significantly between 1979 and 1985. Gaul (1991) also found that concentrations of HCH isomers were lower in sea ice than in seawater while PCB congeners, DDT-related compounds and HCB were detectable in particulates associated with the ice. Vlasov and Melnikov (1990) found 2 H C H concentrations in surface seawater collected during 1986-1989 from the Kara, Laptev, East Siberian and Chukchi Seas that were similar to those observed in the Norwegian Sea
May 1986 May 1986
May 1986 Aug 1985 Aug 1985
May 1986 Aug 1986 Aug 1985 Aug 1985 1986-1989 1986-1989 1986-1989 1986-1989
Date
6 4
3 3 3
6 5 1 1 ? ? ? ?
N
