Sedimentary biomarkers along a contamination gradient in a human-impacted sub-estuary in Southern Brazil: A multi-parameter approach based on spatial and seasonal variability

•New organic geochemistry insights from a large South American estuary.•Composition and seasonal variations of sedimentary organic matter were studied.•PAHs concentrations suggested the absence of contamination.•The Principal Components Analysis suggested spatial variation in the organic markers.

The composition and seasonal variations of sedimentary organic matter were investigated along the Cotinga sub-estuary, located in Paranaguá Bay, a large South American estuary where urban activities and the primary Brazilian grain shipping port are sources of pollution. Steroids and hydrocarbons were analyzed in surface sediments collected during the austral winter (2008) and summer (2009) in three distinct sectors, along this sub-estuary in a presumed gradient of fecal contamination. Concentrations ranged from 0.28 to 7.33 μg g−1 (in dry sample weight thereafter),