system imposed by man-made additions. Although it appears that the 

 recent social concern with open-ocean pollution from these sources 

 was not fully justified, local regions can be subjected to trace-metal 

 contamination and associated environmental hazards. One of the serious 

 problems is that of assessing the increase of trace metals in the marine 

 environment because so little is known of their natural variations. 

 Further complication arises from the geochemical dissimilarity of 

 fluvial, estuarine and coastal regions by the dependency of organisms 

 on trace metal availability, from the chemical forms of the metals in 

 the water, and from the presence of other antagonistic or synergistic 

 elements. Perspective can be gained of man's relative influence on trace- 

 metal additons to the environment by comparing man-induced with 

 natural inputs (Table 4). It is evident that man plays an important part 

 in the mobilization of many of the heavy metals of concern. Fortunately, 

 the coastal region, because of the intimate sediment-water interaction, 

 appears best able to absorb excessive heavy metal input. 



Table 4 

 Annual Rates of Mobilization 



*Bowen (1966). 



t United Nations (1968). 



The influence of biological processes on the chemical state of trace 

 metals in ocean water is not clear. However, the indirect influence is 

 probably profound, because the organic matter that is responsible 



51 



