ASPECTS OF THE GEOCHEMISTRY OF DISSOLVED AND PARTICULATE CD, CU, NI, CO, AND PB IN THE DOVER STRAIT

Water column samples have been collected at six stations across the Do ver Strait within the framework of the FluxManche programme every mont h for fifteen months and analyzed for particulate and dissolved trace metals. Important seasonal variations in trace metal distributions hav e been identified. Dissolved Cu and Ni exhibit similar behaviour in th e Strait; while seasonal variation in their distribution may be determ ined by changes in freshwater input, additional processes including bi ological uptake and regeneration and benthic input probably perturb wa ter column inventories. Consistently with the suggestion of other auth ors, Co and Mn in both the dissolved and particulate phase exhibit som e degree of covariance; substantial increases in the concentration of dissolved Mn in the summer (9.0-69.0 nM as opposed to 3.3-9.6 nM in th e winter) across the entire Channel are to some extent supported by in creases in dissolved Co concentrations. Summer maxima are accompanied by a reduction in the acetic acid leachable particulate Mn, possibly i mplying release from this phase in the summer or increased uptake duri ng the winter. Data for particulate cadmium are consistent with the me tal being largely associated with biogenic material; biological activi ty is inferred to generate a spring depletion in dissolved Cd concentr ations. In contrast to deep ocean environments, there is no obvious co rrespondence between dissolved Cd and the classical nutrient elements in this environment. Dissolved Pb concentrations appear to be strongly influenced by seasonal variation in freshwater input and shorter time scale variation in atmospheric input. There is some evidence that bio logical activity perturbs the water column inventory. This is supporte d by observations from the particulate phase where atmospheric or fluv ially derived particles appear largely to determine the total particul ate Pb concentration in winter but other phases become important in it s regulation in summer.