Acid-available particulate trace metals associated with suspended sedimentin the Humber rivers: a regional assessment

Information on the distribution of acid-soluble Al, Ba, Co, Cr, Ni, Fe, Mn and Pb associated with suspended sediment is presented for the major Humber rivers draining into the North Sea. The data analysed are based on two maj or data sets: the Land-Ocean Interaction Study (LOIS) and Environment Agenc y (EA) regional monitoring programmes. Trace metal particulate concentratio ns show a large variation over space and time. Three types of pattern are o bserved. First, Ba and Pb are highly and linearly correlated and they have an order of magnitude higher concentrations to the north of the region owin g to localized bedrock mineralization, historic mining activity and the ass ociated contamination of floodplain areas during the 18th and 19th centurie s (type 1). Secondly, there are strong interelement relationships between A l, Co, Ni and Fe (and to a lesser extent Mn) and between these elements and suspended sediment concentrations (type 2) and the points for all the rive rs lie on the same straight line. For type 2 elements, concentrations are e nriched by a factor of three within the industrially affected rivers in the central and southern parts of the area: the rural Swale in the north of th e area also has enhanced concentrations of type 2 elements in relation to h igher suspended sediment concentrations. Thirdly, chromium shows about a th irty-fold enrichment in the industrial rivers (type 3). The relationships b etween all the trace metals are represented by a simple three-component mix ing scheme involving natural background materials, industrially generated p articulates and resuspended floodplain sediments contaminated by historic m ining activity. The need for (a) focused studies to identify and describe key type localiti es for specific industrial and urban pollution sources and (b) further expl oration of the wealth of information contained within the EA database, is h ighlighted. Copyright (C) 1999 John Wiley & Sons, Ltd.