The Distribution of trace metals and fauna in the firth of clyde in relation to the Disposal of Sewage Sludge

Abstract

SummaryTrace metals have been determined in the sediments, waters and fauna of a sewagesludge disposal area in the Firth of Clyde. Enhanced values of organic carbon and several metals were found in the sediments of the immediate deposit area. The results are discussed in relation to local background variations and compared with data from the Solway Firth. Trace-metal concentrations in the waters of the deposit area were higher than those from further off shore in the Clyde.Epifaunal species showed rather erratic variation in trace metal content, unrelated to total or readily extractable trace metals in the underlying sediment. The tracemetal content of demersal fish species was not significantly different from figures reported for elsewhere in the United Kingdom.The distributions of some in-faunal and epifaunal species in the area are described.It is concluded that the effects of sewage sludge disposal in this area are local, gross changes being limited to an area of about 20 km2 of sea-bed. However, little is known of the overall effects of toxic wastes particularly at threshold levels, and further monitoring is required.