Sludge disposal in Liverpool Bay - fourteenth bed monitoring survey, November 1986

This report describes the fourteenth HR survey carried out in November 1987, continuing the long-term monitoring of the bed sediments of Liverpool Bay. The objective is to determine whether any changes are occurring in the abundance of heavy metals and of organic matter in the finer fraction of the bed sediment as a consequence of sewage sludge disposal. The differences in measured concentration arising from the selection of 90µm instead of the more traditional 63µm as the upper limit of the finer fraction is germane to the future conduct of the monitoring programme by the North West Water Authority. The findings of the first half of a two-year study into the expected consequences of making this choice are described