Contamination and effects of hydrocarbons on the Forth ecosystem, Scotland

Abstract

SynopsisSince 1924 the Forth has received effluent from Scotland's major petrochemical industry and refinery in addition to hydrocarbon inputs from many other sources. The firth shows no major effects of this, but the history of inputs, together with the estuary's physical characteristics, have created a large residue of hydrocarbon contaminants especially in its sediments. This paper gives the degree and gradients of contamination in several components and describes the effect of hydrocarbon contaminants on the ecosystem structure.The major inputs have produced localised lethal effects, in that productive estuarine intertidal habitat has been lost or its functioning altered. The changes are primarily due to organic enrichment with only very near-field toxic effects. Some of the effects result from historical contamination, but existing discharges continue to have a deleterious effect. New petrochemical discharges in both firth and estuary appear to have a minimal impact, although the historical contamination makes it difficult to assess their effects.