Coprostanol in the intertidal sediments of Kuwait. Case study on urban sewage contamination

The present study was conducted to assess the nature and degree of contamination by urban sewage discharge in the costal zone of Kuwait. Intertidal surface sediments were collected from the vicinity of coastal effluents and bathing beaches. The sediments were characterized for their sterol composition (coprostanol; cholesterol; campesterol; stigmasterol and β-sitosterol) and total organic carbon content (TOC). The analyses revealed that the fecal biomarker coprostanol is present at levels ranging between 0.55-45.06 μg/g dry weight, which amounted to 9.9-49.45% of the total sedimentary sterols measured. The locus of highest impact is the southwestern edge of Kuwait Bay at Shuwaikh area. This probably resulted from the continuous sewage discharge from effluent, slow speed tidal currents and the nature of sediments. The overall patterns of distribution indicate that the sewage-derived material discharged from coastal effluent is affected by the physical processes constraining the area. The prevailing tidal currents contribute to fecal contamination of bathing beaches. Significant correlations were found between organic sewage derived materials (coprostanol/total sterol) and TOC. The sterols composition, other than the fecal inputs indicates the contribution of both terrigenous and biogenic inputs to sedimentary organic matter.