Suspended particulate matter in the western Dead Sea: Distribution and chemical composition

The concentrations and chemical composition of the suspended particulate matter (SPM) in the surface water of the western Dead Sea was studied. Surface brine samples were collected in April 1998 (20 stations) and October 1999 (13 stations). The samples were analyzed for major and minor element concentrations (Al, Fe, Mg, Ca, Na, K Ti, Ba, Sr, Co, La, Ce, U, Cu, Cr, Cd, Pb). Maximal SPM concentrations were found at the Jordan River estuary and the Qidron River mouth, with values >100 mg L^-1. SPM concentration decreases seaward after approximately one kilometer to values of 4.1 ± 2.7 mg L^-1 (mean and standard deviation), showing a patchy spatial distribution mapped using a Compact Airborne Spectrographic Imager (CAS1). The chemical composition of the SPM indicates the dominance of carbonates and alumino-silicates, and probably detrital organic matter, mainly derived from fluvial sources. A common origin and conservative behavior were detected for Al, Ti, Ce, La, and Co, while enrichment of Mn and Fe was attributed to particle coatings of Fe and Mn oxides. Enhancement of Sr/Ca ratios in SPM as compared to detrital carbonates may attest to the presence of authigenic aragonite. However, further in-depth examination is needed to indicate the relative importance of these processes. Statistically testing the variance of the element concentrations in SPM (principle component analysis), the following main associations were depicted: (1) a conservative group of elements, (2) Fe, Mn, U, and (3) Cd and Pb. This grouping probably represents common sources or removal mechanisms.