Chromium distribution in waters and sediments of the eastern side of The Qatari Peninsula

Abstract

The coastal environment on the eastern side of the Qatari peninsula is subjected to several sources of pollution such as the leaching from a solid waste disposal site, the merchant and naval harbours of Doha and surface water discharge outlets. Chromium was measured in surface sea water and in surficial sediments by graphite furnace atomic absorption spectrophotometry (GFAAS). Average Cr concentrations in the investigated waters during the period of study were 0.08, 0.66 and 0.54 μg l −1, respectively, for Cr(III), Cr(VI), and particulate phases. The areal distribution of Cr in the studied waters reflected the impact of the leachate from the solid waste disposal site, the surface water discharge and the two harbours in the area. Cr concentrations in the investigated sediments ranged from 11.6 to 46.5 μg g −1 dry wt. with an average of 25.4 ± 8.7 μg g −1 dry wt. Elevated Cr levels were identified in the sediments around the solid waste disposal site (> 40 μg g −1 dry wt.) and around the surface water discharge outlet (> 30 μg g −1 dry wt.). Most of the other sediments onshore and offshore, down to a water depth of about 6 m, generally showed Cr concentrations between 20 and 30 μg g −1 dry wt. Labile Cr (extracted with 0.5 M HCl) represented only 32% of the total Cr levels in Doha surface sediments. In general, Cr levels in the studied waters and sediments decreased in a seaward direction. A moderate correlation was found between Cr concentration and organic carbon ( r = +0.64) in the studied sediments.