Biomarkers in surface sediments from the Cross River and estuary system, SE Nigeria: Assessment of organic matter sources of natural and anthropogenic origins

Herein, lipid biomarker analysis is applied to surface sediments from the southeastern Niger Delta region for the quantitative determination of aliphatic lipids, steroids and triterpenoids in order to differentiate between natural (autochthonous vs. allochthonous) and anthropogenic organic matter (OM) inputs to this deltaic environment. This ecosystem, composed of the Cross, Great Kwa and Calabar Rivers, is receiving new attention due to increased human and industrial development activities and the potential effects of these activities impacting its environmental health. While the presence of low molecular weight n-alkanes (

► Sources of organic matter to sediments from the SE Niger Delta region were assessed. ► A strong influence of point sources was observed along the river transects. ► Intermittent inputs of microbial OM are likely due to localized eutrophication. ► Anthropogenic inputs likely derive from oil production and/or urban activities. ► Other anthropogenic inputs are from untreated sewage waste and agricultural run-off.