8.3.1 Heavy Metals in Water and Sediment 



TATIANA P. KOLOBOVA and LYUDMILA G. MANYAKHINA 



Institute of Global Climate and Ecology. State Committee for Hydrometeorology and Academy of Sciences, Moscow, USSR 



Introduction 



Materials and Methods 



Among numerous pollutants coming to the World Ocean, 

 the greatest potential threat is posed by chemicals that have 

 global distribution, continuous input, and pronounced adverse 

 effect on living creatures. These substances include heavy 

 metals. These and other substances may cause serious ecological 

 changes on aglobal scale. Therefore, studying theiroccurrence 

 and distribution may help us avoid their damaging effects. 



Pollution of the World Ocean by toxic metals is a most 

 telling example of a global anthropogenic effect. Today there 

 are practically no regions in the world oceans that do not 

 contain increased levels of trace metals. Analysis of the 

 modem data (Izrael & Tsyban, 1981) shows that millions of 

 tons of toxic metals come to the world oceans every year. It is 

 established ( Izrael & Tsyban, 1981; Sapozhnikov, 1982) that in 

 recent years the anthropogenic components of some pollutants 

 (including lead, mercury, arsenic) is comparable to and even 

 exceeds natural flows of these elements to the world oceans. 

 The present concentrations of toxic metals in the world oceans 

 varies from single digit to hundreds of ng/1, which considerably 

 exceeds (5 to 10 times ) their natural concentration in seawater. 



Being intrinsic constituents in the habitat, metals, when 

 exceeding their natural concentrations in these habitats, can 

 render an adverse effect on living creatures (Florence, 1983; 

 Yablokov& Ostroumov, 1983). 



In view of the above, investigation of toxic metal behavior, 

 as well as processes of their accumulation and distribution in 

 sea ecological systems, takes an important place among 

 environmental pollution problems. However, their 

 concentration is usually lower than those of such widely spread 

 pollutants as oil products and chlorinated hydrocarbons. 



At the same time, one has to note that, regardless of several 

 serious studies aimed at evaluation of the World Ocean pollution 

 by toxic metals performed in the last decades, individual seas, 

 specifically those in the so-called background regions of the 

 ocean, are still insufficiently studied. The present state of 

 knowledge does not provide any complete concept of the 

 processes of metal accumulation and distribution in ecological 

 systems of these seas. Meanwhile, some of these seas — in 

 particular, the Bering Sea and the Chukchi Sea — belong to the 

 most productive and more used regions of the world oceans. 

 That is why a study of toxic metal accumulation and distribution 

 processes in such ecological systems, as well as their interaction 

 with the environment, is of special interest. 



This paper discusses distribution of trace metals in water 

 and bottom sediments of the Bering Sea and the Chukchi Sea 

 on the basis of studies performed by the Third Joint US-USSR 

 Bering & Chukchi Seas Expedition. The cruise track covered 

 the larger part of the sea regions in this area, including shallow 

 water and coastal areas as well as deep-water regions. 



Water was sampled using Niskin plastic bathometers. 

 Preliminary treatment of samples was done using standard 

 procedure described in detail in the Methodological Foundations 

 of Integrated Ecological Monitoring of the Ocean (Tsyban 

 etai, 1988). 



The top layers of the bottom sediments were sampled 

 without disturbance of the stratification, using an OKEAN-50 

 dredger with 0.25 m- coverage area. After the samples were air 

 dried at 20 to 25°C, they were sealed in plastic bags for storage. 

 Further treatment of sediment samples was performed in the 

 permanent coastal laboratory using the procedure described by 

 Prokofyev and associates (Prokofyev et al, 1981 ). 



Solutions, resulting from acid digestion of the samples, 

 were tested for metal concentrations using flame atomic 

 absorption spectroscopy. 



Results and Discussion 



Tables 1 and 2 show the trace metal concentration in water 

 and bottom sediments of the Bering Sea and the Chukchi Sea. 



Comparison of the data shows inhomogeneity of metal 

 distribution in the water of the regions in question. For 

 instance, concentrations of copper varied from 0.01 |ag/l (in the 

 Gulf of Anadyr) to 0.46 |ig/l in the open areas of the Bering Sea 

 (Station 109), with an average value of 0.08 |ig/l. Shallow- 

 water stations ( up to 1 00 m deep ) demonstrated a direct relation 

 between copper concentration in water and bottom sediments: 

 a larger copper concentration in water is accompanied by its 

 larger concentration in bottom sediments. Such a correlation 

 was not found at the deep-water stations. In general, copper 

 concentration in bottom sediments of the Bering Sea varied 

 from 9.32 |ig/g dry wt. in the open areas of the Bering Sea up 

 to 38.32 ng/g dry wt. in the Gulf of Anadyr with the average 

 value 17.0 |ag/g. 



Sediments of the Chukchi Sea contained a significantly 

 smaller copper concentration — found near the Alaska coastline 

 ( Station 64 ) and the smallest one (4.6 jJg/g) near the arctic coast 



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