Sewage-derived sterols in Kuala Selangor, Selangor Malaysia

Abstract

There are four sewage-derived sterols which are reliable and widely used to assess sewage contamination in aquatic environments. The main sewage-derived sterol is coprostanol and the rests are epicoprostanol, cholesterol and cholestanol. The distribution of these sterols in twelve surface sediment samples taken from Kuala Selangor, Selangor illustrate the presence of cholesterol as the major compound accounted 41 % of total sterols, followed by epicoprostanol (33%), cholestanol (22%) and surprisingly coprostanol has the lowest amount which constitutes only 5% of total sterols. Based on low composition of coprostanol and high amount of epicoprostanol, Kuala Selangor is assumed to be free from sewage contamination. However, to assure this assumption, application of ratios is required The most common ratios applied are coprostanollcholesterol, coprostanoll(coprostanol+cholestanol) and epicoprostanoll cholesterol ratios. Coprostanollcholesterol ratio exhibit station KS6 and KS12 have the value >0.2, which indicate an occurrence of sewage contamination. All of sampling stations on the other hand also have the value <1, which indicate input/rom biogenic instead of sewage source. This indication also supported by the coprostanoll(coprostanol+cholestanol) ratio which has the value <0.7 for all sampling stations which reflects no sewage contamination in the area, Mean while epicoprostanollcholesterol ratio calculated shows all of sampling stations have the value >0.2 which shows high amount of treated or old sewage. In conclusion, results from this study are fascinating as they presented main sewage-derived sterols have been quantified in all samples but still the study area is not contaminated with sewage matter,