The Applications of Chemical Analyses of Sediments and Soils in ...

Of interest is the form of chromium in its effect on man. It is an essentialelement and the optimal form is a yet unidentified water soluble, low molecular weightcomplex (Mertz and Roginski, 1971). In animals, the rate of synthesis of thiscompound in the intestinal flora is probably the most important factor. Determinationof total chromium gives little information about its biological value (National ResearchCouncil,1974).ARSENICArsenic is commonly associated with sulphidic ores of copper and gold andbecomes airborne as the oxide during the roasting process. Some soils, such as in NewZealand, are naturally high in arsenic (up to 1 per cent). It was previously usedextensively in agriculture.Orchard soils in South-Western Ontario have been found to contain as much as121 ppm (Miles, 1968). Inorganic arsenic is rapidly deactivated in soil through theformation of insoluble iron and aluminum salts.Organic arsenicals of low toxicity such as mono-and di-sodium methane arsonate(MSMA and DSMA, respectively), cacodylic acid and arsanilic acid are also used inanimal food supplements. Arsanilic acid entering soil from manure is immobilized byiron, aluminum and calcium in the same manner as arsenate and phosphate (Woolson,1975).Biological concentration occurs up the food chain with up to 700x in fish.15