Temporal variation and risk assessment of heavy metals and nutrients from water and sediment in a stormwater pond, Brazil

Abstract

Urban watercourses are under pressure owing to the inflow of environmental pollutants from stormwater and effluent. The concentrations of heavy metals, ammoniacal nitrogen, total phosphorus (TP), and physicochemical parameters were monitored in a sediment pond in the Brazilian Midwest. The correlation between the variables and the degree of sediment contamination was verified using the Geoaccumulation Index (Igeo), Contamination Factor (CF), and Pollutant Load Index (PLI). The general concentrations of the metals were in the order Mn > B > Ba > Zn > Cu > Cr > Pb > Ni in the water and Mn > Cr > Ba ≥ B > Zn > Cu > Ni . Pb in the sediment. The concentrations of Ba, Cr, Cu, Mn, Ni, Pb, and TP in the water exceeded the regulatory limits at least one time. The mean concentrations of Cr, Cu, and Ni in the sediment samples were 6.32, 1.63, and 2.61 higher than standard values. The applied geochemical indices indicated a moderate to a very high degree of sediment contamination, suggesting the anthropogenic origin of Cr, Cu, and Ni. Significant Pearson correlations were observed between turbidity and total suspended solids (TSS), Ba, Cr, Mn, Zn, and TP. Ponds and urban lakes require maintenance or may become a source of environmental pollutants.