The Use of Coprostanol, Epi-Coprostanol and Cholesterol in Evaluating Potential Sewage Input from Downstream River towards Marine Environment

Abstract

Contamination of sewage is a major concern in the river and marine environments since sewage can cause disease and ecosystem health problems. Worldwide, coprostanol, coprostanol and epi-coprostanol were used in sewage assessment due to their resistance towards environmental stressor. This study assessed the distribution of coprostanol, epi-coprostanol and cholesterol in the particulate of sewage treatment plant (STP) effluents and river water samples. The targeted analytes were extracted using sonication and quantified using gas chromatography-mass spectrometer (GC-MS). The potential sewage pollution in the river and marine environments were assessed using diagnostic approach and linear regression technique. Based on the result, cholesterol (mean = 15.6 mg L-1) was found to be higher than coprostanol (mean = 6.0 mg L-1) and epi coprostanol (mean= 2.3 mg L-1) in STPs samples. Similar to STPs, cholesterol (mean= 4.6 mg L-1) also was detected higher than coprostanol (mean= 2.4 mg L-1) and epi-coprostanol (mean= 2.4 mg L-1) in the river water samples. The double plot ratios of epi-coprostanol/cholesterol versus epi-coprostanol/coprostanol revealed the discharge of treated and untreated sewage into the river water. The river water samples were impacted by treated sewage and non-human sources. The linear regression analysis indicates potential moderate to high increasing trend (p<0.05) of sewage discharge towards downstream of the river. These findings provide an enhanced means in assessing sewage contamination input into the river and its potential effect towards the marine ecosystem.