Metal(loid)s pollution in coastal deep-water and tidal flat sediments from Pearl River system, China: concentration, source apportionment and environmental risk

The geochemical features of typical potentially toxic metals/metalloids (PTMs) of Mo, Th, As, Cu, Cr, Pb, Zn and Sr in deep-water sediments and tidal flat sediments were seldom compared. The objective of this research was to investigate the current status of concentration, source apportionment and environmental risk of PTMs in deep-water sediments and tidal flat sediments from the Pearl River system, one of the most economically developed districts, China. The results show concentrations of Cu, Zn and Pb in deep-water sediments were generally higher than those from the tidal flat sediments. Assessments of PTMs contamination suggest that the levels of contamination from Cu, As and Pb are high in all the sediments. Spatial variation was observed in the contamination levels of Cu and Zn. The potential ecological risk was identified as Cu > As > Pb > Zn > Cr for deep-water sediments and As > Cu > Pb > Zn > Cr for tidal flat sediments. According to the sediment quality guidelines (SQGs), potential adverse effects on aquatic biota may be indicated for all eight PTMs. Receptor models of positive matrix factorization (PMF) quantified the source types and contributions of these PTMs. Strong intensity of industrial activities coupling with agricultural applications (61.8%) and natural processes (14.7%) were responsible for the enriched accumulation of PTMs in these sediments. Based on the findings, environmental management strategies for the Pearl River should prioritize addressing contamination by Pb, Zn, and Cu. • Deep-water sediments carry more Cu, Zn, Pb than tidal flats in Pearl River, China. • Cu, As and Pb rank highest contamination in both deep-water and tidal flats sediments. • Industrial and farm runoff explain 62% of the PTMs contamination in the sediments.