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In a previous investigation, relatively simple relations were found to estimate free Cu, and hence a good approximation of bio-available Cu, at two sites in estuarine waters of the Dutch Oosterschelde and Westerschelde. In the present study, these relations are validated for the remainder of the two sea arms. In the Westerschelde the relation between the concentration of a dissolved organic ligand (K = 10(13)), DOC (dissolved organic carbon) and salinity is valid in a range of salinities at least from 10 up to 25 to 30. This ligand group is primarily riverine and partly estuarine. It is, as far as we know, the strongest Ligand for Cu, and its concentration dominantly affects the free Cu ion concentrations, which are around 50 fM. At high salinities, dilution and mineralisation diminish the riverine member of the ligand group too much and the relation with salinity and DOC is no longer valid. In the Oosterschelde the relations between POC (particulate organic carbon) and particulate Cu and between POC and the ratio of particulate and dissolved Cu are valid for the western, central and eastern compartments. Since equilibrium was assumed to exist between dissolved and particulate Cu, foe Cu can be calculated from POC and particulate Cu concentrations. Due to the large adsorption capacity of POC, the Oosterschelde is with respect to Cu a very well-buffered system with [Cu2+] of 20 fM. [KEYWORDS: estuaries; copper; speciation; bio-availability Cathodic stripping voltammetry; scheldt estuary; eastern scheldt; trace-metals; sea-water; complexation; speciation; zinc; bay; cu]
Original languageEnglish
Pages (from-to)193-203
JournalJournal of Sea Research
Issue number3-4
StatePublished - 1998

ID: 350052