ANNUAL VARIATIONS IN SUSPENDED PARTICULATE MATTER WITHIN THE DOVER STRAIT

During a survey at six stations in the Dover Strait, from July 1990 to November 1991, water samples were collected to measure : suspended se diment load and its organic content; particle characteristics; photosy nthesis pigments; and heavy metals. In this contribution, particle mea surements are interpreted in terms of hydrodynamical effects and seaso nal evolution. Multi-modal grain size spectra are indicative of depth and cross-sectional variations, from die coastline to the central wate rs. Tidal variations, biological productivity and wind effects can be identified. Suspended particulate matter (SPM) components (determined using SEM, when combined with size spectra) illustrate hydrodynamical, geomorphological and biological effects on the composition of the sus pended matter. Living and non-living diatom valves, used as particulat e tracers, provide information on the sources and hydrodynamic behavio ur of the suspended particles. Although the Seine input is high, river ine SPM input is not detected within the Dover Strait. SPM fluxes from the Eastern Channel into the southern North Sea, across the Dover Str ait, originate mainly from: Atlantic waters; coastal and sea bed erosi on; biological activity; and resuspension from the intertidal zone. SP M studies in the Eastern Channel could provide information on the comp lex behaviour of river pollutants over the region.