Determination of hydrocarbon sources using n-alkane and PAH distribution indices in sediments from coastal areas of bonny river in Niger delta, Nigeria

Surface sediments from coastal areas of Bonny river in the Southeastern Niger Delta region of Nigeria were characterized for n-alkane and polycyclic aromatic hydrocarbon (PAH) compositions using gas chromatography-mass spectrometry (GC-MS) technique. The total n-alkane (TNA) concentrations in the study area ranged from 1.65-12.66 mg/kg dsw. The mean concentrations of n-alkanes C16 - C29 for the sediments ranged from 0.11- 10.31mg/kg dsw, with the highest mean value recorded for n-alkane C17. CPI values ranged from 0.31 - 1.65, and a predominance of odd/even carbon n-alkanes with unimodal distributions were observed for the entire stations. Factor analyses reduced the data set into three principal components (PCs) confirming mixed inputs from biogenic (71.48%), anthropogenic (11.61%) and microbial/bacterial (7.90%) sources of n-alkanes. Twenty four (24) parent and alkylated homologous PAHs of dominant pyrogenic origin were detected in stations from the study area, with total PAH concentrations in the range of 2.13- 16.72mg/kg.