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PCBs and chlorinated pesticides in the atmosphere and aquatic organisms of Ross Island, Antarctica
Marine Pollution Bulletin, Volume 25, 'o 12, pp. 281 287, 1992. Printed in Great Britain,
0112:, 326X 92 $5 0()+l).00 © Iq92 Pergamon Press 1.1d
PCBs and Chlorinated Pesticides in the Atmosphere and Aquatic Organisms of Ross Island, Antarctica PER LARSSON*~-, CECILIA JARNMARK* and ANDERS S O D E R G R E N t *Limnology Department of Ecology, Box 65, S-221 O0 Lund, Sweden t Chemical Ecology and Ecotoxicology, Department of Ecology, Ecology Building, S-223 62 Lund, Sweden ~Io whom correspondence should be addressed.
PCBs, p,p'-DDT, p,p'-DDE and lindane (y-hexaehiorocyclohexane) were monitored in the lower atmosphere of Ross Island, in Antarctica for 2 yr. Geometrical means were 15.2 pg m -3 for PCBs, 2.0 pg m -3 for p,p'DDT, 1.0 pg m -3 for p,p'-DDE and 25.8 pg m -3 for lindane. Atmospheric levels of lindane were positively correlated with temperature, and a significant difference was found between spring-summer and s u m m e r winter concentrations. No season related differences were found for the other chlorinated hydrocarbons, possibly owing to their lower vapour pressure and the cold climate. Periods with increased atmospheric levels of PCBs and D D T c o m p o u n d s were recorded. Lindane, p,p'-DDE and PCBs were present in fish and zooplankton sampled close to Ross Island. Pollutant levels in the zooplankton (on an extractable fat basis) were highest during the Antarctic spring and autumn and were inversely correlated to their fat content.
Antarctica is one of the most pristine areas in the world, and the influence of human activities there is still minor. However, in the late 1960s, organochlorine compounds (OCs) were detected in wildlife by several researchers. In 1983, Tanabe et aL concluded that the long-range transport by wind was largely responsible for the presence of these pollutants on the continent. The concentration of OCs in the air was lower compared with industrialized parts of the world. Thus, monitoring of persistent pollutants in the atmosphere, sea water or biota of Antarctica should give an indication of the degree to which remote areas are exposed to persistent pollutants. On the other hand, point sources exist, as shown by Riseborough et al. (1990), for PCBs (polychlorinated biphenyls) and PCTs (polychlorinated terphenyls) on Ross Island, Antarctica. These sources are old dump sites used by exploration bases, where equipment, etc. was, discarded. Although most studies have been focused on persistent pollutants in animals (Tanabe et al., 1983), lichens and mosses have also been sampled to monitor deposition of persistent pollutants (Bacci et al., 1986; Calamari et al., 1991).
Studies of chlorinated hydrocarbons in the atmosphere of the Southern Hemisphere have also been carried out on cruises in the Indian Ocean and adjacent seas (Bidleman & Leonard, 1982; Tanabe et al., 1982). In some cases, monitoring of airborne pollutants has been performed on islands, e.g. Bermuda (Knap et al., 1988) and Reunion (Ballschmiter & Wittlinger, 1991). The techniques commonly employed have been highvolume sampling for 8-12 h with polyurethane foam plugs (Tanabe et al., 1982; Bidleman & Leonard, 1982) or, more seldom, with silica gel (Ballschmiter & Wittlinger, 1991). The distribution and deposition of many pollutants in the atmosphere show seasonal patterns correlated with temperature. For example, seasonal patterns in the distribution of PCBs in the atmosphere have been found in North America (Hermanson & Hites, 1989; Manchester-Neeswig & Andren, 1989) and Sweden (Larsson & Okla, 1989), and the global deposition of DDTs and H C H (hexachlorocyclohexanes) also varies with the season (Calamari et al., 1991). These patterns are presumably due to the differential partitioning of the pollutants between a volatilized phase, airborne particles and airborne water. Thus at low temperatures the compounds associate with particles or water in the atmosphere and are washed out, whereas at high temperatures they are volatilized and may be transported over long distances (Ligocki et al., 1985a,b). The pollutants have entered the aquatic food web of Antarctica and reached top-predators such as seals and penguins. Hidaka et al. (1983) concluded that levels of PCBs and ZDDT were two or three orders of magnitude lower in Weddel seals (Leptonychotes wedelli) from Antarctic waters than in various species of marine mammals from other oceans. This conclusion was supported by McClurg (1984) after a study of Ross seals (Ommatophoca rossi). Levels of PCBs and p,p'DDE in Adelie penguins (Pygoscelis adeliae) ranged from 32-107 ng g-1 and from 162-804 ng g-~ extractable fat, respectively (Subramanian et al., 1986). Levels of persistent pollutants in these birds followed a seasonal cycle, being concentrated in the declining fat reserves during the breeding season when the birds fasted. Levels of chlorinated hydrocarbons are lower in 281
Marine PollutionBulletin various Antarctic bird species than in birds from other areas of the world (Luke et al., 1989). Zooplankton, which serves as food for many species of fish, provides an important link in the transfer of dissolved and particle-bound persistent pollutants to high trophic levels in the aquatic food web. Consequently, they play a major role in distributing organochlorine residues throughout the marine environment (Harding, 1986). To examine the occurrence and levels of persistent pollutants in the Antarctic atmosphere, lindane, DDTs (p,p'-DDT+p,p'-DDE), and PCBs (polychlorinated biphenyls) were monitored in the air at Ross Island from 1988-90. Zooplankton and fish were sampled during the same period to study the distribution of the pollutants in the aquatic food web.
Materials and Methods Air was sampled at Ross Island, Cape Evans (77°38.1'S 166°24.6'E) from March 1988-January 1990. Each sampling period lasted from 7-21 days, during the time between 200 and 600 m 3 of air processed by filtering it through two polyurethane foam plugs connected in series (Larsson & Okla, 1989). The sampling method gives a time-integrated sample. Zooplankton was sampled with a net (mesh size 300 ~m) from May-December 1990 at Home Beach and South Bay at Ross Island, where the fish were also caught. The compounds adsorbed to the polyurethane foam plugs were extracted with acetone/hexane (1:1) in an ultrasonic bath (Larsson & Okla, 1989). The pollutants in the fish and in the zooplankton were extracted according to Larsson (1989). The samples were cleaned-up with fuming H2804, evaporated to 50-200 btl, and analysed by capillary gas chromatography/ECD (Okla & Wesdn, 1984). Twenty-four PCB congeners were searched for, quantified (Duinker & Hillebrand, 1983), and numbered according to the IUPAC system (Ballschmiter & Zell, 1980). Clophen A 60 served as an external standard, while PCB 53 (2,2',5,6'-tetrachlorobiphenyl) was used as an internal standard. Detection limits were 0.3 pg m -3 for PCB 153, 0.5 pg m -3 for lindane and 0.2 pg m -3 for p,p'-DDE. None of the pollutants was detected in non-exposed polyurethanefoam plugs. All concentrations of pollutants were logtransformed (log(1 + X)) in order to compute statistical comparisons, owing to the skewed distribution of the values (Newton, 1988) and because we regarded nondetected values to be relevant, thus they had to be included as zero-values in the statistical evaluations.
Results and Discussion The fact that the airborne pollutants were transferred to and transported in the Antarctic food web was shown by their occurrence in zooplankton and fish. Levels of lindane, DDT, and PCBs in the liver of the fish Pagothenia bernacchii (n= 15) were 0.03, 0.01, and 0.07 mg kg-1 fat wt, respectively, which are all lower than those reported in fish near industrialized areas of the world. At Syowa Station (69°00'S, 39°35'E) 282
Subramanian et al. (1983) found DDT (0.7 ng g-~ wet wt) and PCB (0.17 ng g-~ wet wt) in T. bernacchii. However, since these levels are based on whole fish, no comparison to our results can be made. Levels of lindane in zooplankton varied from 0.939.7 ng g-1 fresh wt (19-3322 ng g-1 extractable fat), and p,p'-DDE levels were between 0.1 and 4.2 ng g-t fresh wt (3-354 ng g-J extractable fat, Table 2). Pollutant levels were highest during the Antarctic spring and autumn. PCBs and p,p'-DDT were only occasionally detected in the zooplankton. Lindane and p,p'DDE were (on extractable fat basis) negatively related to the fat content of the zooplankton (linear regression, r2=0.48; 0.40, p<0.01 respectively). Levels of p,p'DDE in the zooplankton (geometric mean 29.2 ng g-~ extractable fat) were similar to those of plankton in the Ross Sea, Antarctica, measured in 1972 (Harding, 1986). The negative relationship between pollutant levels in zooplankton and their fat content may have been the result of yearly seasonal variation in zooplankton species composition, fat composition and levels of exposure to pollutant in water and/or food. One of the reasons why p,p'-DDT and PCBs were only occasionally found in the samples is probably that the zooplankton was collected under ice. Tanabe et al. (1983) found that concentrations of DDTs were lower in the water under ice than in the water from the outer margin of the pack ice. No such difference was found for PCBs and HCHs. However, the low-chlorinated congeners of PCB dominated in the samples from water under fast ice. The authors concluded that DDT and higher chlorinated PCBs, owing to their higher affinity for particles, are removed from the surface water by sedimentation. Thus, the dominating OCs found in zooplankton should be lindane and low chlorinated PCBs, although the latter have been shown to be metabolized. The mean temperature and the concentration of lindane in the air were significantly correlated (linear regression, r2=0.30, p < 0.01). Temperatures in the air were low, with a mean below -15°C during 14 out of 29 sampling periods. The mean temperatures only exceeded 0°C during one sampling period. To study seasonal variation, data were categorized according to season (spring, summer, autumn or winter) during which they had been collected. The category chosen was related to major temperature shifts (Table 1) A significant amount of variation in the concentration of lindane was recorded (Anova, p < 0.05), with significant differences between spring and summer (t-test, p<0.05) and between summer and winter (t-test, p=0.01). No differences were found between summer and autumn, autumn and winter, winter and spring or autumn and spring. For PCBs, individual PCB congeners, p,p'-DDE and p,p'-DDT no significant relationship was found between levels in the air and temperature. Lindane concentrations in the Antarctic air ranged from 0.5-118 pg m -3 (geometrical mean 25.8 pg m -3, Table 1, Fig. 1) and were higher than those of the other OCs investigated. Seasonal variation in the pollutant distributions in the atmosphere has been recorded in North America
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TABLE
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Fat content and concentrations of lindane and p,p'-DDE in Antarctic zooplankton. Date 1990 8 May 21 May 27 June 5 July 10 July 18 July 25 July 1 August 14 August 22 August 6 September 23 September 10 October 18 October 13 December 27 December
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(Hermanson & Hites, 1989; Manchester-Neeswig & Andren, 1989) for PCBs and in Sweden for PCBs and DDTs (Larsson & Okla, 1989). This variation is presumably due to seasonal changes in the partitioning of the pollutants between a volatilized stage, airborne particles and airborne water. The distribution of a substance between airborne water and its gaseous phase is described by the Henry's Law constant, H, which is equal to the ratio of the compounds vapour pressure to its solubility (for low solubility substances, Ligocki et al., 1985a). Lindane has a lower H than both PCBs and DDTs (Ballschmiter & Wittlinger, 1991), implying that the substance will partition to airborne water easier than PCBs, p,p'-DDE and p,p'-DDT. For every 10-degree decrease in temperature, H decreases with a factor of two. Partitioning to particles is determined by a compounds vapour pressure, temperature and the amount and type of particles present (Ligoicki, 1985b). PCBs, p,p'-DDE and p,p'DDT, which have a lower vapour pressure than lindane (lindane~ 1.9X 10 -2 Pa, p,p'-DDT=3.3X 10 .5 Pa, p,p'-DDE=8.6 x 10 -4 Pa, PCB congeners substituted with five or more chlorine-atoms, e.g. PCB 101, 2.6x 10 -4 Pa, Ballschmiter & Wittlinger, 1991) will partition to particles to a higher degree than lindane. This partitioning will be favoured by decreasing 284
temperatures. Thus, OC concentrations in the atmosphere will be lower during winter than during summer, since total fallout is higher during winter. Also, during summer a remobilization of OCs from the ground to the atmosphere occurs owing to the higher temperatures-and thus higher evaporization rates (Larsson & Okla, 1989). Lindane is used during the summer in tropical/ temperate regions and the resulting high levels in the atmosphere may be reflected in elevated atmospheric levels in Antarctica during summer and autumn. Lindane's higher vapour pressure may also account for its higher concentrations compared with the other substances; i.e. since it is more easily remobilized from the ground to the atmosphere it is more susceptible than PCBs and DDTs to long-range transport over the Indian Ocean. The lower vapour pressures of PCB and DDT compared with that of lindane may also explain why there was no relation between temperature and their concentrations in the air. Thus, owing to the very cold climate on Antarctica, partitioning behaviour of these substances apparently depends on other yet-tobe-determined factors. The geometrical mean of the concentrations of PCBs in the air was 15.2 pg m -3 (Fig. 2). During one period (16-28 December 1988), however, the level of PCBs
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was two orders of magnitude higher than during any of the other periods, and the PCB-congener pattern at this time resembled that of Clophen A 60. Furthermore, levels of p,p'-DDE and p,p'-DDT were also high, suggesting that there had been an episodic inflow of long-range transported airborne pollutants. On the other hand, the increase in PCB concentrations was considerably greater than increases in the other compounds. Thus, it cannot be ruled out that local contamination was the source of the increase. For example, Risebrough et al. (1990) recorded PCB contamination at McMurdo Base on Ross Island. It is possible, that volatilization of PCBs from the dumping sites, followed by their airborne transport, could have contributed to the observed increase. The PCB congeners that generally dominated during the study were PCB 95, PCB 101, PCB 110, PCB 149, PCB 153, and PCB 138. Levels of p,p'-DDE and p,p'-DDT in the air varied from 0.2-43 pg m -3 and from 0.1-145 pg m -3, respectively (Fig. 3). The geometrical mean was 1.0 pg m -3 for p,p'-DDE and 2.0 pg m -3 for p,p'-DDT. In contrast to the situation in the Northern Hemisphere, few studies have been made on the occurrence and distribution of pesticides in the Southern Hemisphere. However, it is
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study and in the study by Tanabe et al. (1982) the reverse was true. Tanabe et al. (1982, 1983) measured the air concentration of OCs at two locations 'close' to our sampling station (Sabrina Coast 61-65°S, 121-125°E and Balleney Islands 60-67°S, 155-164°E) in January 1981. They reported respective concentrations of 92 and 120 pg m -3 for lindane, 120 pg m -3 for p,p'-DDT at both locations, 21 pg m -3 and 30 pg m -3 for p,p'DDE, and 180 and 64 pg m -3 for PCBs. In comparison with that study, our values for lindane from the Antarctic summers of 1988-89 and 1989-90 are lower (geometric m e a n = 4 2 pg m-3). The same is true for PCBs (geometric mean=21 pg m-~), p,p'-DDT and p,p'-DDE (geometric mean= 3 pg m -3 and 1 pg m -3, respectively). Similarly to Tanabe et al. (1983) higher levels of persistent pollutants were found in the summer than in winter. The generally lower levels of lindane found in the Antarctic atmosphere in the present study compared with other investigations in the Southern Hemisphere, can probably be explained by differences in sampling location. Since the prevailing winds in Antarctica are from the northwest, the source area for the Ross Islands is the Indian Ocean. Moreover, values obtained in investigations in the eastern parts of the Southern Hemisphere (Tanabe et al., 1982, 1983; Bidleman & Leonard, 1982) showed higher levels than our study. However, still higher levels were found by Ballschmiter & Wittlinger (1991) at the Reunion Island whose source area is Africa and the Atlantic Ocean. Thus, the comparison suggests the use of lindane in the Southern Hemisphere has been higher in the west than in the east. The same reasoning may hold for PCB and DDT although the difference between the two hemispheres are not great enough to distinguish different consumption amounts. The much lower concentration of DDTs found in our investigation compared with that reported by Tanabe et al. (1982, 1983) can be ascribed to the decrease in DDT use that has occurred over the last decade. This is 286
also supported by the decrease that occurred in DDT/ DDE ratios over about the same period (about 5 in 1981 and to 2.5 for the equivalent period in this study). The DDT/DDE ratio of 0.4 found by Ballschmiter & Wittlinger (1991) suggests more remote sources or historical inflow in the western parts of the Southern Hemisphere compared to the eastern parts. We thank the Greenpeace Antarctica Expedition for help with the sampling. Special thanks are due to Sabine Smidht, Wojtek Moskal, Liz Carr, Ricardo Roura and Lilian Hansen who withstood the severe Antarctic climate and carried out their sampling tasks in an outstanding manner.
Bacci, E., Calamari, D., Gaggi, C., Fanelli, R., Focardi, S. & Morosine, M. (1986). Chlorinated hydrocarbons in lichen and moss samples from the Antarctic peninsula. Chemosphere 15, 747-754. Ballschmiter, K. & Wittlinger, R. (1991). lnterhemisphere exchange of hexachlorocyclohexanes, hexachlorobenzene, polychlorobiphenyls, and 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane in lower troposphere. Environ. Sci. Technol. 25, 1103 1111. Ballschmiter, K. & Zell, M. (1980). Analysis of polychlorinated biphenyls (PCB) by glass capillary gas chromatography. Fresenius J. Anal. Chem. 302, 20-31, Bidleman, T. F. & Leonard, R. (1982). Aerial transport of pesticides over the Northern Indian Ocean and adjacent seas. Atmos. Environ. 16, 1099-1107. Calamari, D., Bacci, E., Fogardi, S., Gaggi, C., Morosini, M. and Vighi, M. (1991). Role of plant biomass in global environmental partitioning of chlorinated hydrocarbons. Environ. Sci. Technol. 25, 1213-1218. Duinker, J. C. & Hillebrand, T. J. (1983). Composition of PCB mixtures in biotic and abiotic marine compartments (Dutch Wadden Sea). Bull. Environ. Contain. Tox. 31, 25 32. Harding, G. C. (1986). Organochlorine dynamics between zooplankton and their environment, a reassessment. Mar. Ecol. Prog. Ser. 33, 167-191. Hermanson, M. K. & Hites, R. A. (1989). Long-term measuremems of atmospheric polychlorinated biphenyls in the vicinity of superiund dumps. Environ. Sci. Technol. 23, 1254-1258. Hidaka, H., Tanabe, S. & Tatzukawa. R. (1983). DDT compounds and PCB isomers and congeners in Weddell seals and their fate in Antarctic marine ecosystem. Agri. Biol. (;hem. 47, 2009-2017. Kaushik, C. P., Pillai, M. K., Raman, A. & Agarwal, H. C. (1987). Organochlorine insecticide residues in air in Dehli, India. Water, Air Soil Pollut. 32, 63-76. Knap, A. H., Binkley, K. S. & Artz. R. S. (1988). The occurrence and distribution of trace organic compounds in Bermuda precipitation. Atmos. Environ. 22, 1411-1423. Larsson. P. & Okla, L. (1989). Atmospheric transport of chlorinated
Volume 25/Numbers 9 12 hydrocarbons to Sweden in 1985 compared to 1973. Atrnos. Environ. 23, 1699 1711. Larsson, P. (1989). Atmospheric deposition of persistent pollutants governs uptake by zooplankton in a pond in southern Sweden. Atmos. Environ. 23, 2151-2158. Ligocki, M. P., Leuenberger, C. & Pankow, J. F. (1985a). Trace organic compounds in rain--If. Gas scavenging of neutral organic compounds. Atmos. Environ. 19, 1609-1617. Ligocki, M. P., Leuenberger, C. & Pankow, J. E (1985b). Trace organic compounds in rain--III. Particle scavenging of neutral organic compounds. Atmos. Environ. 19, 1619-1626. Luke, B. G., Johnstone, G. W. & Woelher, E. J. (1989). Organochlorine pesticides. PCBs and mercury in antarctic and subantarctic seabirds. Chemosphere 19, 2007-2021. Manchester-Neeswig, J. B. & Andren, A. W. (1989). Seasonal variation m the atmospheric concentration of polychlorinated biphenyl congeners. Environ. Sci. Technol. 23, 1138-1148. McClurg, T. R (1984). Trace metals and chlorinated hydrocarbons in Ross seals from Antarctica. Mal: Pollut. Bull. 15,384-389. Newton, I. (1988). Determination of critical pollutant levels in wild populations with examples from organochlorine insecticides in birds of prey. Environ. Pollut. 55, 29-4(1.
Okla, L. & Wes~n, C. (1984). A simple on-column injector for capillary gas chromatography. J. Chromatog. 299, 420-423. Ramesh, A., Tanabe, S. & Tatsukawa, R. (1989). Seasonal variations of organochlorine insecticide residues in air from Porta Novo, south India. Environ, Pollut. 62,213-222. Riseborough, R. W., de Lappe, B. W. and Younghans-Haug, C. (1990). PCB and PCT contamination in Winter Quarters Bay, Antarctica. Mar. Pollut. Bull. 231,523-529. Subramanian, A., Tanabe, S., Tanaka, H., Hidaka, H. & Tatsukawa, R. (1983). DDTs and PCB isomers and congeners in Antarctic fish. Arch. Environ. Contain. Toxicol. 12,621-626, Subramanian, A., Tanabe, S., Tanaka, H., Hidaka, H. & Tatsukawa, R. (1986). Gain and loss rates and biological half-life of PCBs and DDE in the bodies of Adelie penguins. Environ. Pollut. 43, 39-46. Tanabe, S., Hidaka, H., Kawano, M. & Tatsukawa, R. (1982). Global distribution and atmospheric transport of chlorinated hydrocarbons: HCH isomers and DDT compounds in the Western Pacific, Eastern Indian and Antarctic Ocean. J. Oceanog. Soc. Japan 5, 97-1(19. Tanabe, S., Hidaka, H. & Tatsukawa, R. (1983). PCBs and chlorinated hydrocarbon pesticides in Antarctic atmosphere and hydrosphere. Chemosphere 12,277-288.
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0112:, 326X 92 $5 0()+l).00 © Iq92 Pergamon Press 1.1d
PCBs and Chlorinated Pesticides in the Atmosphere and Aquatic Organisms of Ross Island, Antarctica PER LARSSON*~-, CECILIA JARNMARK* and ANDERS S O D E R G R E N t *Limnology Department of Ecology, Box 65, S-221 O0 Lund, Sweden t Chemical Ecology and Ecotoxicology, Department of Ecology, Ecology Building, S-223 62 Lund, Sweden ~Io whom correspondence should be addressed.
PCBs, p,p'-DDT, p,p'-DDE and lindane (y-hexaehiorocyclohexane) were monitored in the lower atmosphere of Ross Island, in Antarctica for 2 yr. Geometrical means were 15.2 pg m -3 for PCBs, 2.0 pg m -3 for p,p'DDT, 1.0 pg m -3 for p,p'-DDE and 25.8 pg m -3 for lindane. Atmospheric levels of lindane were positively correlated with temperature, and a significant difference was found between spring-summer and s u m m e r winter concentrations. No season related differences were found for the other chlorinated hydrocarbons, possibly owing to their lower vapour pressure and the cold climate. Periods with increased atmospheric levels of PCBs and D D T c o m p o u n d s were recorded. Lindane, p,p'-DDE and PCBs were present in fish and zooplankton sampled close to Ross Island. Pollutant levels in the zooplankton (on an extractable fat basis) were highest during the Antarctic spring and autumn and were inversely correlated to their fat content.
Antarctica is one of the most pristine areas in the world, and the influence of human activities there is still minor. However, in the late 1960s, organochlorine compounds (OCs) were detected in wildlife by several researchers. In 1983, Tanabe et aL concluded that the long-range transport by wind was largely responsible for the presence of these pollutants on the continent. The concentration of OCs in the air was lower compared with industrialized parts of the world. Thus, monitoring of persistent pollutants in the atmosphere, sea water or biota of Antarctica should give an indication of the degree to which remote areas are exposed to persistent pollutants. On the other hand, point sources exist, as shown by Riseborough et al. (1990), for PCBs (polychlorinated biphenyls) and PCTs (polychlorinated terphenyls) on Ross Island, Antarctica. These sources are old dump sites used by exploration bases, where equipment, etc. was, discarded. Although most studies have been focused on persistent pollutants in animals (Tanabe et al., 1983), lichens and mosses have also been sampled to monitor deposition of persistent pollutants (Bacci et al., 1986; Calamari et al., 1991).
Studies of chlorinated hydrocarbons in the atmosphere of the Southern Hemisphere have also been carried out on cruises in the Indian Ocean and adjacent seas (Bidleman & Leonard, 1982; Tanabe et al., 1982). In some cases, monitoring of airborne pollutants has been performed on islands, e.g. Bermuda (Knap et al., 1988) and Reunion (Ballschmiter & Wittlinger, 1991). The techniques commonly employed have been highvolume sampling for 8-12 h with polyurethane foam plugs (Tanabe et al., 1982; Bidleman & Leonard, 1982) or, more seldom, with silica gel (Ballschmiter & Wittlinger, 1991). The distribution and deposition of many pollutants in the atmosphere show seasonal patterns correlated with temperature. For example, seasonal patterns in the distribution of PCBs in the atmosphere have been found in North America (Hermanson & Hites, 1989; Manchester-Neeswig & Andren, 1989) and Sweden (Larsson & Okla, 1989), and the global deposition of DDTs and H C H (hexachlorocyclohexanes) also varies with the season (Calamari et al., 1991). These patterns are presumably due to the differential partitioning of the pollutants between a volatilized phase, airborne particles and airborne water. Thus at low temperatures the compounds associate with particles or water in the atmosphere and are washed out, whereas at high temperatures they are volatilized and may be transported over long distances (Ligocki et al., 1985a,b). The pollutants have entered the aquatic food web of Antarctica and reached top-predators such as seals and penguins. Hidaka et al. (1983) concluded that levels of PCBs and ZDDT were two or three orders of magnitude lower in Weddel seals (Leptonychotes wedelli) from Antarctic waters than in various species of marine mammals from other oceans. This conclusion was supported by McClurg (1984) after a study of Ross seals (Ommatophoca rossi). Levels of PCBs and p,p'DDE in Adelie penguins (Pygoscelis adeliae) ranged from 32-107 ng g-1 and from 162-804 ng g-~ extractable fat, respectively (Subramanian et al., 1986). Levels of persistent pollutants in these birds followed a seasonal cycle, being concentrated in the declining fat reserves during the breeding season when the birds fasted. Levels of chlorinated hydrocarbons are lower in 281
Marine PollutionBulletin various Antarctic bird species than in birds from other areas of the world (Luke et al., 1989). Zooplankton, which serves as food for many species of fish, provides an important link in the transfer of dissolved and particle-bound persistent pollutants to high trophic levels in the aquatic food web. Consequently, they play a major role in distributing organochlorine residues throughout the marine environment (Harding, 1986). To examine the occurrence and levels of persistent pollutants in the Antarctic atmosphere, lindane, DDTs (p,p'-DDT+p,p'-DDE), and PCBs (polychlorinated biphenyls) were monitored in the air at Ross Island from 1988-90. Zooplankton and fish were sampled during the same period to study the distribution of the pollutants in the aquatic food web.
Materials and Methods Air was sampled at Ross Island, Cape Evans (77°38.1'S 166°24.6'E) from March 1988-January 1990. Each sampling period lasted from 7-21 days, during the time between 200 and 600 m 3 of air processed by filtering it through two polyurethane foam plugs connected in series (Larsson & Okla, 1989). The sampling method gives a time-integrated sample. Zooplankton was sampled with a net (mesh size 300 ~m) from May-December 1990 at Home Beach and South Bay at Ross Island, where the fish were also caught. The compounds adsorbed to the polyurethane foam plugs were extracted with acetone/hexane (1:1) in an ultrasonic bath (Larsson & Okla, 1989). The pollutants in the fish and in the zooplankton were extracted according to Larsson (1989). The samples were cleaned-up with fuming H2804, evaporated to 50-200 btl, and analysed by capillary gas chromatography/ECD (Okla & Wesdn, 1984). Twenty-four PCB congeners were searched for, quantified (Duinker & Hillebrand, 1983), and numbered according to the IUPAC system (Ballschmiter & Zell, 1980). Clophen A 60 served as an external standard, while PCB 53 (2,2',5,6'-tetrachlorobiphenyl) was used as an internal standard. Detection limits were 0.3 pg m -3 for PCB 153, 0.5 pg m -3 for lindane and 0.2 pg m -3 for p,p'-DDE. None of the pollutants was detected in non-exposed polyurethanefoam plugs. All concentrations of pollutants were logtransformed (log(1 + X)) in order to compute statistical comparisons, owing to the skewed distribution of the values (Newton, 1988) and because we regarded nondetected values to be relevant, thus they had to be included as zero-values in the statistical evaluations.
Results and Discussion The fact that the airborne pollutants were transferred to and transported in the Antarctic food web was shown by their occurrence in zooplankton and fish. Levels of lindane, DDT, and PCBs in the liver of the fish Pagothenia bernacchii (n= 15) were 0.03, 0.01, and 0.07 mg kg-1 fat wt, respectively, which are all lower than those reported in fish near industrialized areas of the world. At Syowa Station (69°00'S, 39°35'E) 282
Subramanian et al. (1983) found DDT (0.7 ng g-~ wet wt) and PCB (0.17 ng g-~ wet wt) in T. bernacchii. However, since these levels are based on whole fish, no comparison to our results can be made. Levels of lindane in zooplankton varied from 0.939.7 ng g-1 fresh wt (19-3322 ng g-1 extractable fat), and p,p'-DDE levels were between 0.1 and 4.2 ng g-t fresh wt (3-354 ng g-J extractable fat, Table 2). Pollutant levels were highest during the Antarctic spring and autumn. PCBs and p,p'-DDT were only occasionally detected in the zooplankton. Lindane and p,p'DDE were (on extractable fat basis) negatively related to the fat content of the zooplankton (linear regression, r2=0.48; 0.40, p<0.01 respectively). Levels of p,p'DDE in the zooplankton (geometric mean 29.2 ng g-~ extractable fat) were similar to those of plankton in the Ross Sea, Antarctica, measured in 1972 (Harding, 1986). The negative relationship between pollutant levels in zooplankton and their fat content may have been the result of yearly seasonal variation in zooplankton species composition, fat composition and levels of exposure to pollutant in water and/or food. One of the reasons why p,p'-DDT and PCBs were only occasionally found in the samples is probably that the zooplankton was collected under ice. Tanabe et al. (1983) found that concentrations of DDTs were lower in the water under ice than in the water from the outer margin of the pack ice. No such difference was found for PCBs and HCHs. However, the low-chlorinated congeners of PCB dominated in the samples from water under fast ice. The authors concluded that DDT and higher chlorinated PCBs, owing to their higher affinity for particles, are removed from the surface water by sedimentation. Thus, the dominating OCs found in zooplankton should be lindane and low chlorinated PCBs, although the latter have been shown to be metabolized. The mean temperature and the concentration of lindane in the air were significantly correlated (linear regression, r2=0.30, p < 0.01). Temperatures in the air were low, with a mean below -15°C during 14 out of 29 sampling periods. The mean temperatures only exceeded 0°C during one sampling period. To study seasonal variation, data were categorized according to season (spring, summer, autumn or winter) during which they had been collected. The category chosen was related to major temperature shifts (Table 1) A significant amount of variation in the concentration of lindane was recorded (Anova, p < 0.05), with significant differences between spring and summer (t-test, p<0.05) and between summer and winter (t-test, p=0.01). No differences were found between summer and autumn, autumn and winter, winter and spring or autumn and spring. For PCBs, individual PCB congeners, p,p'-DDE and p,p'-DDT no significant relationship was found between levels in the air and temperature. Lindane concentrations in the Antarctic air ranged from 0.5-118 pg m -3 (geometrical mean 25.8 pg m -3, Table 1, Fig. 1) and were higher than those of the other OCs investigated. Seasonal variation in the pollutant distributions in the atmosphere has been recorded in North America
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TABLE
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Fat content and concentrations of lindane and p,p'-DDE in Antarctic zooplankton. Date 1990 8 May 21 May 27 June 5 July 10 July 18 July 25 July 1 August 14 August 22 August 6 September 23 September 10 October 18 October 13 December 27 December
Fat content (%)
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(Hermanson & Hites, 1989; Manchester-Neeswig & Andren, 1989) for PCBs and in Sweden for PCBs and DDTs (Larsson & Okla, 1989). This variation is presumably due to seasonal changes in the partitioning of the pollutants between a volatilized stage, airborne particles and airborne water. The distribution of a substance between airborne water and its gaseous phase is described by the Henry's Law constant, H, which is equal to the ratio of the compounds vapour pressure to its solubility (for low solubility substances, Ligocki et al., 1985a). Lindane has a lower H than both PCBs and DDTs (Ballschmiter & Wittlinger, 1991), implying that the substance will partition to airborne water easier than PCBs, p,p'-DDE and p,p'-DDT. For every 10-degree decrease in temperature, H decreases with a factor of two. Partitioning to particles is determined by a compounds vapour pressure, temperature and the amount and type of particles present (Ligoicki, 1985b). PCBs, p,p'-DDE and p,p'DDT, which have a lower vapour pressure than lindane (lindane~ 1.9X 10 -2 Pa, p,p'-DDT=3.3X 10 .5 Pa, p,p'-DDE=8.6 x 10 -4 Pa, PCB congeners substituted with five or more chlorine-atoms, e.g. PCB 101, 2.6x 10 -4 Pa, Ballschmiter & Wittlinger, 1991) will partition to particles to a higher degree than lindane. This partitioning will be favoured by decreasing 284
temperatures. Thus, OC concentrations in the atmosphere will be lower during winter than during summer, since total fallout is higher during winter. Also, during summer a remobilization of OCs from the ground to the atmosphere occurs owing to the higher temperatures-and thus higher evaporization rates (Larsson & Okla, 1989). Lindane is used during the summer in tropical/ temperate regions and the resulting high levels in the atmosphere may be reflected in elevated atmospheric levels in Antarctica during summer and autumn. Lindane's higher vapour pressure may also account for its higher concentrations compared with the other substances; i.e. since it is more easily remobilized from the ground to the atmosphere it is more susceptible than PCBs and DDTs to long-range transport over the Indian Ocean. The lower vapour pressures of PCB and DDT compared with that of lindane may also explain why there was no relation between temperature and their concentrations in the air. Thus, owing to the very cold climate on Antarctica, partitioning behaviour of these substances apparently depends on other yet-tobe-determined factors. The geometrical mean of the concentrations of PCBs in the air was 15.2 pg m -3 (Fig. 2). During one period (16-28 December 1988), however, the level of PCBs
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was two orders of magnitude higher than during any of the other periods, and the PCB-congener pattern at this time resembled that of Clophen A 60. Furthermore, levels of p,p'-DDE and p,p'-DDT were also high, suggesting that there had been an episodic inflow of long-range transported airborne pollutants. On the other hand, the increase in PCB concentrations was considerably greater than increases in the other compounds. Thus, it cannot be ruled out that local contamination was the source of the increase. For example, Risebrough et al. (1990) recorded PCB contamination at McMurdo Base on Ross Island. It is possible, that volatilization of PCBs from the dumping sites, followed by their airborne transport, could have contributed to the observed increase. The PCB congeners that generally dominated during the study were PCB 95, PCB 101, PCB 110, PCB 149, PCB 153, and PCB 138. Levels of p,p'-DDE and p,p'-DDT in the air varied from 0.2-43 pg m -3 and from 0.1-145 pg m -3, respectively (Fig. 3). The geometrical mean was 1.0 pg m -3 for p,p'-DDE and 2.0 pg m -3 for p,p'-DDT. In contrast to the situation in the Northern Hemisphere, few studies have been made on the occurrence and distribution of pesticides in the Southern Hemisphere. However, it is
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generally accepted that the high levels of DDT compounds in the Southern Hemisphere are partly due to the extensive use of DDT in India (Ramesh et al., 1989; Kaushik et al., 1987) and Africa. The average level of airborne DDT in India during 1980-1982 was 60 ng m -3 (Kaushik et al., 1987), which is 4-5 orders of magnitude higher than the levels over the Indian Ocean. In the same study, Kaushik et al. reported levels of total HCH as high as 22 000 ng m -3, revealing an important source to the atmosphere south of the equator. Bidleman & Leonard (1982) found that the mean concentration of p,p'-DDT was 12.8 pg m -3 and that of lindane was 82.5 pg m -3 in the Arabian Sea, near the equator, in December and January 1976-77. On Reunion Island (near Madagascar) in March 1986 average pollutant levels were 406 pg m -3 for lindane, 125 pg m -3 for PCBs, 18 pg m -~ for p,p'-DDE, and 8 pg m -3 for p , p ' - D D T (Ballschmiter & Wittlinger, 1991). These levels are about ten times higher than those of lindane, p,p'-DDE, p,p'-DDT and PCBs from the corresponding time period in our study (autumn, Table 1). It should be noted that Ballschmiter & Wittlinger (1991) found the concentration of p,p'-DDE to be higher than that of p , p ' - D D T , whereas in our
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study and in the study by Tanabe et al. (1982) the reverse was true. Tanabe et al. (1982, 1983) measured the air concentration of OCs at two locations 'close' to our sampling station (Sabrina Coast 61-65°S, 121-125°E and Balleney Islands 60-67°S, 155-164°E) in January 1981. They reported respective concentrations of 92 and 120 pg m -3 for lindane, 120 pg m -3 for p,p'-DDT at both locations, 21 pg m -3 and 30 pg m -3 for p,p'DDE, and 180 and 64 pg m -3 for PCBs. In comparison with that study, our values for lindane from the Antarctic summers of 1988-89 and 1989-90 are lower (geometric m e a n = 4 2 pg m-3). The same is true for PCBs (geometric mean=21 pg m-~), p,p'-DDT and p,p'-DDE (geometric mean= 3 pg m -3 and 1 pg m -3, respectively). Similarly to Tanabe et al. (1983) higher levels of persistent pollutants were found in the summer than in winter. The generally lower levels of lindane found in the Antarctic atmosphere in the present study compared with other investigations in the Southern Hemisphere, can probably be explained by differences in sampling location. Since the prevailing winds in Antarctica are from the northwest, the source area for the Ross Islands is the Indian Ocean. Moreover, values obtained in investigations in the eastern parts of the Southern Hemisphere (Tanabe et al., 1982, 1983; Bidleman & Leonard, 1982) showed higher levels than our study. However, still higher levels were found by Ballschmiter & Wittlinger (1991) at the Reunion Island whose source area is Africa and the Atlantic Ocean. Thus, the comparison suggests the use of lindane in the Southern Hemisphere has been higher in the west than in the east. The same reasoning may hold for PCB and DDT although the difference between the two hemispheres are not great enough to distinguish different consumption amounts. The much lower concentration of DDTs found in our investigation compared with that reported by Tanabe et al. (1982, 1983) can be ascribed to the decrease in DDT use that has occurred over the last decade. This is 286
also supported by the decrease that occurred in DDT/ DDE ratios over about the same period (about 5 in 1981 and to 2.5 for the equivalent period in this study). The DDT/DDE ratio of 0.4 found by Ballschmiter & Wittlinger (1991) suggests more remote sources or historical inflow in the western parts of the Southern Hemisphere compared to the eastern parts. We thank the Greenpeace Antarctica Expedition for help with the sampling. Special thanks are due to Sabine Smidht, Wojtek Moskal, Liz Carr, Ricardo Roura and Lilian Hansen who withstood the severe Antarctic climate and carried out their sampling tasks in an outstanding manner.
Bacci, E., Calamari, D., Gaggi, C., Fanelli, R., Focardi, S. & Morosine, M. (1986). Chlorinated hydrocarbons in lichen and moss samples from the Antarctic peninsula. Chemosphere 15, 747-754. Ballschmiter, K. & Wittlinger, R. (1991). lnterhemisphere exchange of hexachlorocyclohexanes, hexachlorobenzene, polychlorobiphenyls, and 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane in lower troposphere. Environ. Sci. Technol. 25, 1103 1111. Ballschmiter, K. & Zell, M. (1980). Analysis of polychlorinated biphenyls (PCB) by glass capillary gas chromatography. Fresenius J. Anal. Chem. 302, 20-31, Bidleman, T. F. & Leonard, R. (1982). Aerial transport of pesticides over the Northern Indian Ocean and adjacent seas. Atmos. Environ. 16, 1099-1107. Calamari, D., Bacci, E., Fogardi, S., Gaggi, C., Morosini, M. and Vighi, M. (1991). Role of plant biomass in global environmental partitioning of chlorinated hydrocarbons. Environ. Sci. Technol. 25, 1213-1218. Duinker, J. C. & Hillebrand, T. J. (1983). Composition of PCB mixtures in biotic and abiotic marine compartments (Dutch Wadden Sea). Bull. Environ. Contain. Tox. 31, 25 32. Harding, G. C. (1986). Organochlorine dynamics between zooplankton and their environment, a reassessment. Mar. Ecol. Prog. Ser. 33, 167-191. Hermanson, M. K. & Hites, R. A. (1989). Long-term measuremems of atmospheric polychlorinated biphenyls in the vicinity of superiund dumps. Environ. Sci. Technol. 23, 1254-1258. Hidaka, H., Tanabe, S. & Tatzukawa. R. (1983). DDT compounds and PCB isomers and congeners in Weddell seals and their fate in Antarctic marine ecosystem. Agri. Biol. (;hem. 47, 2009-2017. Kaushik, C. P., Pillai, M. K., Raman, A. & Agarwal, H. C. (1987). Organochlorine insecticide residues in air in Dehli, India. Water, Air Soil Pollut. 32, 63-76. Knap, A. H., Binkley, K. S. & Artz. R. S. (1988). The occurrence and distribution of trace organic compounds in Bermuda precipitation. Atmos. Environ. 22, 1411-1423. Larsson. P. & Okla, L. (1989). Atmospheric transport of chlorinated
Volume 25/Numbers 9 12 hydrocarbons to Sweden in 1985 compared to 1973. Atrnos. Environ. 23, 1699 1711. Larsson, P. (1989). Atmospheric deposition of persistent pollutants governs uptake by zooplankton in a pond in southern Sweden. Atmos. Environ. 23, 2151-2158. Ligocki, M. P., Leuenberger, C. & Pankow, J. F. (1985a). Trace organic compounds in rain--If. Gas scavenging of neutral organic compounds. Atmos. Environ. 19, 1609-1617. Ligocki, M. P., Leuenberger, C. & Pankow, J. E (1985b). Trace organic compounds in rain--III. Particle scavenging of neutral organic compounds. Atmos. Environ. 19, 1619-1626. Luke, B. G., Johnstone, G. W. & Woelher, E. J. (1989). Organochlorine pesticides. PCBs and mercury in antarctic and subantarctic seabirds. Chemosphere 19, 2007-2021. Manchester-Neeswig, J. B. & Andren, A. W. (1989). Seasonal variation m the atmospheric concentration of polychlorinated biphenyl congeners. Environ. Sci. Technol. 23, 1138-1148. McClurg, T. R (1984). Trace metals and chlorinated hydrocarbons in Ross seals from Antarctica. Mal: Pollut. Bull. 15,384-389. Newton, I. (1988). Determination of critical pollutant levels in wild populations with examples from organochlorine insecticides in birds of prey. Environ. Pollut. 55, 29-4(1.
Okla, L. & Wes~n, C. (1984). A simple on-column injector for capillary gas chromatography. J. Chromatog. 299, 420-423. Ramesh, A., Tanabe, S. & Tatsukawa, R. (1989). Seasonal variations of organochlorine insecticide residues in air from Porta Novo, south India. Environ, Pollut. 62,213-222. Riseborough, R. W., de Lappe, B. W. and Younghans-Haug, C. (1990). PCB and PCT contamination in Winter Quarters Bay, Antarctica. Mar. Pollut. Bull. 231,523-529. Subramanian, A., Tanabe, S., Tanaka, H., Hidaka, H. & Tatsukawa, R. (1983). DDTs and PCB isomers and congeners in Antarctic fish. Arch. Environ. Contain. Toxicol. 12,621-626, Subramanian, A., Tanabe, S., Tanaka, H., Hidaka, H. & Tatsukawa, R. (1986). Gain and loss rates and biological half-life of PCBs and DDE in the bodies of Adelie penguins. Environ. Pollut. 43, 39-46. Tanabe, S., Hidaka, H., Kawano, M. & Tatsukawa, R. (1982). Global distribution and atmospheric transport of chlorinated hydrocarbons: HCH isomers and DDT compounds in the Western Pacific, Eastern Indian and Antarctic Ocean. J. Oceanog. Soc. Japan 5, 97-1(19. Tanabe, S., Hidaka, H. & Tatsukawa, R. (1983). PCBs and chlorinated hydrocarbon pesticides in Antarctic atmosphere and hydrosphere. Chemosphere 12,277-288.
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