biological processes involving stimulation, control, genetic changes, 

 or toxicity. Little information is available even as to the total amounts 

 of some elements such as antimony, cadmium, chromium and selenium. 

 Probably copper, zinc, and iron have had more study than any other 

 heavy metal and, although there is some evidence on their chemical 

 speciation, there is no information on the importance of a given chemical 

 species to a biological process. There is also little certain knowledge 

 of the rates of interchange between chemical species of this group in 

 the environment. There is evidence (Button, 1971) that the level of 

 copper in ocean water (about 3 /u,g/liter) decreases the assimilative 

 capacity of a laboratory yeast culture, unless some complexation occurs. 

 The problem of "good" and "bad" ocean waters is thought to be closely 

 related to trace metal complexation, which converts toxic forms, such as 

 Cu+^, to nontoxic ligand-bound forms. Data now being obtained on many 

 of the heavy metals in the oceans will no doubt enhance our knowledge 

 of the distribution of the specific chemical forms being examined, but 

 they will have limited value in assessing their role in biological pro- 

 cesses, the importance of the various chemical species to those processes, 

 or the dynamics of the coastal processes that largely determine the fate 

 of heavy metals in the ocean (National Academy of Sciences, 1971a). 

 Increased research related specifically to the biology, biochemistry, 

 chemical oceanography, and geochemistry of heavy metals in the ocean 

 environment is required to gain an understanding of the effect of biologi- 

 cal processes on trace-metal chemistry, and conversely, the chemistry 

 of trace metals on biological processes. 



Processes, Rates, and Mechanisms 



A process that influences the heavy metal concentration of the oceans 

 is the biological removal of oxygen from the sediments, which leads to 

 the production of hydrogen sulfide and precipitation of insoluble heavy 

 metal sulfides or the solubilization of elements such as iron and man- 

 ganese. The rates of such removal, the status of the equilibrium, and 

 the mechanisms of chemical and biological cycling in the sediments 

 and through the sediment-water interface are subject of great importance 

 in heavy metal chemistry. 



The biota concentrate many heavy metals relative to their environment. 

 Some of these elements have no apparent biological function, and it 

 appears that the organisms have little capability for selective uptake 

 or excretion. Such metals may not be toxic to the host organism, such 

 as zinc or copper in oysters, but they may be passed up the food chain 

 to higher organisms, including man. 



Concerns about heavy metals in the environment often arise from a 

 lack of understanding of the effects of perturbations on the natural 



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