8.1.2 Migratory and Bioaccumulative 



Peculiarities in the Biogeochemical Cycling 

 of Chlorinated Hydrocarbons 



SERGEI M. CHERNYAK, VALERIA M. VRONSKAYA, and TATIANA P. KOLOBOVA 



Institute oj Global Climaie and Ecology. Stale Committee for Hydrometeorology and Academy of Sciences, Moscow, USSR 



Introduction 



Among the multiple organic compounds polluting the 

 environment, chlorinated hydrocarbons are of great importance, 

 especially pesticide preparations (OC"s and PCB's). These 

 compounds, owing to their exclusive properties, were widely 

 used in the past and they are still being heavily used in certain 

 countries, in spite of the fact that since 1971-1972 many 

 developed countries have imposed restrictions or even a full 

 ban on the use of certain pesticides (forexample, DDT). In fact, 

 the world production of these preparations has hardly reduced 

 in the recent decade, becoming stable at approximately 

 1.2 million tons of PCB's (Bletchly, 1984), 3 million tons of 

 DDT(GoIdberg, I975;Tanabe, 1 982), and about 1 million tons 

 of lindane (Tanabe, 1985). Their use over many years has 

 resulted in the widespread distribution of these raw compounds 

 tha> now have become a constituent part of practically all 

 environmental compartments including marine ecosystems 

 (Izrael & Tsyban, 1985a), and owing to the processes of 

 atmospheric transfer, these contaminants have now gotten into 

 quite remote regions rather quickly (Izrael & Tsyban, 1985b). 

 Thus, forexample, residues of PCB have been found in fish and 

 mollusks of the Antarctic (Subramian et ai, 1987) and in 

 penguins (Subramian ('/a/., 1985). Note that the ocean, if one 

 may put it that way, has a role of an accumulator of chlorinated 

 hydrocarbons since, according to Tanabe (1985 ), up to 70% of 

 all chloroorganic compounds discharging into the environment 

 are concentrated in marine ecosystems. Having significant 

 molecular resistance and a high degree of affinity with lipids 

 and suspended agents, chlorinated hydrocarbons can be 

 accumulated in hydrobionls and transmitted along the food 

 chain. It is determined that the process of concentration in 

 living beings depends both on physical and chemical properties 

 of contaminants and on peculiarities of organism and 

 environmental conditions (Tanabe, 1985). Sea organisms not 

 only accumulate and transform contaminants but they also 

 transfer them into different compartments, v^hich leads to their 

 wide distribution in marine ecosystems. 



In this connection, the study of the processes of chlorinated 

 hydrocarbon accumulation and distribution in different 

 components of marine ecosystems and the study of their 

 interaction with the environment assume ever greater 



importance. Note that investigations of the mentioned processes 

 in background regions of the ocean that do not experience the 

 pemianent anthropogenic influence, including ecosystems of 

 the Bering and the Chukchi Seas, are of a special significance. 



Materials and Methods 



Seawater samples, 100 1 each, were passed through resin 

 ( XAD-2 ) at the rate of 20 1 per hour. The adsorbed chlorinated 

 hydrocarbons were eluted using 80 ml of ethanol to which an 

 equal volume of the 2% sodium sulfate solution was added. 

 The water-alcohol solution was extracted twice with n-hexane 

 ( 25 ml ). The extract was concentrated with the rotary evaporator 

 to 4-5 ml volumes; it was then purified by mixing it with 

 concentrated sulfuric acid, neutralized with a 5%-NaHCO, 

 solution, washed with the water, dried over sodium sulfate, and 

 concentrated by evaporation with pure nitrogen gas to a volume 

 of I ml. The concentrate was then injected into a Hewlett- 

 Packard 5840A gas chromatograph with an autosampler. The 

 chromatography was performed under the following conditions: 

 a capillary 30 m fused quartz column with the 0.32 internal 

 diameter; a DB-1 chromatography phase (0.25 |i m). The 

 analyses were carried out under the conditions of column 

 thermostat temperature programming: the starting temperature 

 was 1 20°C for 1 min, the programming rate was 5°C/min up to 

 250°C. The chromatography time was 40 min. The injector 

 temperature was 225°C; the electron capture detector 

 temperature was 300°C. Based on tests of this method, it was 

 found that the overall approach produced results that were 

 within 1 5-20% of the expected values for the concentrations of 

 chlorinated hydrocarbons in seawater. 



The bottom sediments were centrifuged for 20 min at a 

 speed of 2,000 rpm to completely separate the silt from the 

 water, then they were extracted with acetone, followed by a 

 shaking with a hexane-acetone mixture (3: 1 ). The combined 

 extract was mixed with an equal volume of the 2% sodium 

 sulfate solution. The hexane layer was separated and the 

 water-acetone layer was subjected to reextraction. The 

 combined hexane extract was concentrated and then purified 

 by mixing it with sulfuric acid to remove organic substances 

 and with tetrabutylammonium sulfate to remove sulphur and 

 sulfur-organic compounds. The purified solution was 



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