keywords: hydrocarbon, geological, biogenic, anthropogenic, n-alkanes
Sadong River is a major river catchment in Sarawak, Malaysia. Sediments are useful tools in understanding the environmental processes and are final sinks of hydrocarbons in rivers. Hydrocarbon biomarkers are organic compounds found in the environment with structures suggesting an unambiguous connection with known contemporary natural products. These specific indicator compounds which are found in extracts of geological and environmental sample such as sediment can be utilized for genetic source correlations. Hydrocarbons derived from biogenic sources appear with low concentrations in river sediments, while high level of concentration in hydrocarbon compounds are attributed to be of anthropogenic source which often lead to petroleum pollution. Several indices were used to distinguish the origin of n-alkanes in the river such as Low Molecular Weight to High Molecular weight (LMW/HMW), Carbon Preference Index (CPI) and Average Chain Length (ACL). Assessment of n-alkanes in the core sediments showed the hydrocarbons originated from terrestrial sources and anthropogenic sources.