Sludge disposal in Liverpool Bay - vertical profiles of heavy metals and organic carbon in bed sediments - April 1986

Data obtained from sediment cores, taken to investigate the depth of organic and heavy metal enrichment in the mud fraction of the surface sediment in Liverpool Bay, are described. The depth reached by man-made metal contaminants, variously arising out of the marine disposal of large quantities of sewage sludge and dredging spoil as well as the flow from the Mersey, differs markedly over the survey area. In the west, in the vicinity of the sludge disposal ground "natural background" mental concentrations are reached within 0.3m of the surface. By contrast, in the east to either side of the Mersey outflow, obvious contamination by heavy metals is found to at least 1.2m. The depth profiles complement annual surveys of the horizontal distributions of metals and organics in the top 25mm bed layer. They will also be used to support a numerical model designed by Hydraulics Research to simulate the movement and deposition of sewage sludge particulates