AN ASSESSMENT OF METAL CONTAMINATION IN NORTHERN IRISH COASTAL SEDIMENTS

Abstract

Coastal sediments may be considered contaminated with a metal if they have undergone an increase in concentrations above background levels due to anthropogenic inputs. The extent of contamiin ation in Northern Irish coastal sediments was examined by a combination of statistical and graphical analysis utilising aluminium as a grain-size proxy. Enrichment of mercury, lead, zinc and copper was commonly observed in sediments throughout the study area, whereas concentrations of nickel, chromium and iron largely reflected levels in their source rocks. Belfast Lough was the most contaminated area, and it is suggested that the metals commonly associated with industrial and domestic discharges are more biologically available than at the other coastal sites studied. Concentrations of metals in Strangford Lough were close to or at background concentrations and may be used as a baseline to assess the degree of enrichment in other Irish coastal sediments. The area of fine sediments in the western Irish Sea had higher concentrations of metals than some inshore areas that could not be accounted for by grain-size differences alone. The sources and transport mechanisms of metals to the western Irish Sea and the influence of a seasonal gyre on contaminant accumulation are discussed. M. Charlesworth (corre sponding author), De partment of Agricultural and Environmental Sci ence, The Queen's Uni