Trace metal concentrations in the surface sediments of Sulaibikhat Bay, Kuwait

Surface sediment samples were collected by Van Veen grab samplers from thirty-four locations in Sulaibikhat Bay, Kuwait, during November and December, 2003. Bulk sediment composition was characterised by the analysis of the grain size distribution, determination of calcium carbonate and total organic carbon (TOC) contents. The metals cadmium, cobalt, chromium, copper, nickel, lead and zinc were measured by inductively coupled plasma-optical emission spectrometry following digestion with hydrofluoric acid/aqua regia. Arsenic and mercury were determined by hydride generation atomic absorptions spectrometry and cold-vapour atomic absorption spectrometry, respectively. Grain-size analysis showed that the silt fraction was dominant at most locations with a mean of 66.8% and with individual stations falling between 20.4% and 90.0%. The clay fraction (mean 18.0%; range 5.4% - 40.5%) and sand fraction (mean 15.2%; range 1.1% - 73.0%) were less significant. Calcium carbonate contents were 11.4% - 50.6% and TOC fell within the range 0.06% - 6.02%. Mean metal concentrations were 2.23 mu g/g As, 0.37 mu g/g Hg, 2.13 mu g/g Cd, 17.3 mu g/g Co, 139.6 mu g/g Cr, 36.7 mu g/g Cu, 97.8 mu g/g Ni, 10.5 mu g/g Pb and 93.3 mu g/g Zn. Metal concentrations in Sulaibikhat Bay appeared to be correlated with sediment total organic carbon (TOC), and with sediment mud content. Negative correlations were observed between metal concentrations and carbonate content. Metal concentrations were highest in the south east of Sulaibikhat Bay, adjacent to the Ghazali outfall, and decreased to the north.