High resolution monitoring of dissolved Cu and Co in coastal surface waters of the Western North Sea

This paper discusses the distribution of dissolved Cu and Co in coastal surface waters of the western North Sea. High resolution data (more than 5500 (Cu) and 12000 (Co) data points), obtained using on-line flow-analysis techniques, clearly showed enhanced trace metal levels near the coast and estuarine outflows. In an offshore direction, the high metal levels were gradually diluted with metal-depleted seawater originating in the North Atlantic. The data indicated benthic sources for Cu and Co due to diagenetic remobilisation, sediment resuspension with injection of interstitial waters into the overlaying water and/or desorption from resuspended particles. Some evidence of biological removal of dissolved Cu was apparent in offshore coastal waters with enhanced chlorophyll concentrations. The study demonstrates how high resolution trace metal data allows us to deconvolute complex metal input and removal processes in dynamic coastal waters.