COMPARATIVE GEOCHEMISTRIES OF ARSENIC AND ANTIMONY IN RIVERS AND ESTUARIES

Arsenic and antimony are toxic substances in Group VA of the periodic table. Being in the same periodic group, it would be expected that their geochemistries would have many similarities. However, differences would also be expected between the metalloid, arsenic, and the more metallic antimony. Their geochemistries are complicated by transformations in the environment between oxidation states and the presence of environmentally produced organometallic compounds. While there is a reasonable amount of data on the distribution of arsenic in rivers and estuaries, little work has been done on the riverine and estuarine chemistry of antimony, and practically no comparative measurements of these two elements have been made in the same systems. The distributions of arsenic and antimony are presented for various river and estuarine systems ranging from pristine to highly polluted and from inorganically dominated to very organic rich. For rivers there is a general correlation between arsenic and antimony concentrations, except where there are large anthropogenic influences. In estuaries there can be large differences in the behaviors of arsenic and antimony, depending upon the dominant geochemical processes occurring in the specific estuary. These processes and their varying effects upon these two chemically related trace elements are examined. © 1990.