Seasonal and Inter-annual Variation of Selected Pollutants in Modern Intertidal Sediments, Aust Cliff, Severn Estuary

The seasonal and inter-annual variation of pollutants in Severn Estuary intertidal sediments appears partly related to factors other than the levels of pollutants being input to the system from anthropogenic sources. External controls, including seasonality, fluvial discharge and organic matter, are thought to modify pollutant levels in the short term. The sampling of sediments from a fixed station in the Severn Estuary demonstrated this phenomenon with respect to particulate coal debris and zinc. Heavy liquid separation for coal and X-Ray Fluorescence (XRF) analysis for heavy metals were used to determine pollution levels over a 2-year period from November 1987-October 1989 inclusive, comprizing a relatively stormy 12-month period followed by one of relative calm. This appears to be reflected in the pollutant composition of the sediments