Contamination levels and sources of trace elements in river sediments of Northeast Brazil

Abstract The Capibaribe and Ipojuca Rivers drain vital watersheds in the state of Pernambuco, northeastern Brazil, but are influenced by intense anthropogenic activities, particularly because they flow through municipalities in the region known as the Textile Triangle. To evaluate the spatial distributions, contamination levels, and sources of trace elements, surface sediments were collected from the two rivers and the concentrations of seven trace elements (As, Cr, Cu, Co, Ni, Pb, and Zn) were determined. Contamination levels were assessed using five indices: enrichment factor (EF), geoaccumulation index (I geo ), contamination factor (CF), pollution load index (PLI), and combined pollution index (CPI). For the Capibaribe River, Pb was considered to originate from natural sources, with the remaining trace elements presenting contamination levels ranging from low to moderate, primarily due to inputs associated with textile industry effluents and agricultural activities. For the Ipojuca River, Ni was derived from natural sources, while Cr, Cu, Pb, and Zn, at levels ranging from moderate to high, were from anthropogenic origins, especially sewage discharges. Multivariate statistical analysis was employed to distinguish the primary sources of trace element contamination, which was shown to increase in urban areas. Potential sources of contamination in both rivers also included contributions from vehicle emissions and rainwater leachate. These findings provide a comprehensive understanding of substantial contamination by trace elements and the impact of human activities in these watersheds, serving as a guide for the development of preventive and remediation policies aimed at minimizing risks to living species.