Sources, sinks and resuspension of suspended particulate matter in the eastern English Channel

Seasonal observations on the nature and concentration of suspended particul ate matter (SPM) are presented for a cross-section of the English Channel, between the Isle of Wight (UK) and Cotentin peninsula (France) i.e. the wes tern boundary of the eastern English Channel. The highest concentrations of suspended material are found adjacent to the English coastline, whereas th e offshore waters are associated with low concentrations. Seasonal variatio ns in the concentration and nature of suspended material are identified, wi th highest concentrations in winter. At this time, the suspended particles are characterised generally by peaked grain size spectra and an enrichment in coarse silt particles; in summer, the distributions are generally flat. The diatom communities found within the suspended matter indicate that mate rial resuspended in the coastal zone and the estuarine environments is tran sported offshore. SPM fluxes (based upon the observed SPM concentrations an d the output from a 2-D hydrodynamic model) from the western Channel throug h the Wight-Cotentin Section, ranged between 2 and 71 x 10(6) t a(-1) with a mean of around 20 x 10(6) t a(-1) over the period of the observations (19 94-1995). These fluxes are comparable to the order of magnitude and mean va lue reported as output through the Dover Strait. Therefore, it is possible that the eastern English Channel may be characterised as an area of fine-gr ained sediment 'bypass'. This interpretation is corroborated by: (a) the ab sence of fine-grained sediment deposits over the area; and (b) correlation between the potential resuspension time of the fine particles and the seabe d sediment distribution. (C) 1999 Elsevier Science Ltd. All rights reserved .