Evaluation of the source, distribution and risk of metal contaminated stream sediment

Abstract

The research was conducted to determine the cause, dispersal, and risk assessment of metal-contaminated sediment. The sediment was collected from the Madna stream. It was transported to the laboratory, air-dried, ground with a mortar and pestle, and sieved. The sediment was digested with 10 ml of HNO3 and 30 ml of HCl and heated on a hot plate at 100 °C for about 2 hours. The 1 ml solution was diluted to about 50 ml and centrifuged at 1600 revolutions per minute for 10 minutes. The clear solution was analyzed by an atomic absorption spectrophotometer (AAS). The distribution of the average concentration showed that Cd < Cu < Co < Pb < Ni < Fe with a range of 0.03–72.81 mg/kg. The minimum Fe content was 99.78% higher than the maximum Ni, with Ni values being higher than other metals. The geoaccumulation index (igeo), the contamination factor (CF), and the pollution load index (PLI) showed insignificant contamination of the stream by the metals. However, the enrichment factor (EF) revealed minor to extreme enrichment for individual metals across the stations. However, The Ecological risk index (ERI) and Potential ecological risk (PER) showed low risk from individual and collective metals on the biota of the Madna stream ecosystem. There was no noncarcinogenic risk from the detected metals as the hazard quotient (HQ) and hazard index (HI) were <1; however, the children may suffer carcinogenic risk (CR) from cadmium through the nondietary oral route as Cadmium CR > 10−6. The sediment was assessed to be of high quality and posed no risk to the ecosystem as the average concentrations were lower than the effect range low (ERL), effect range median (ERM), and toxicology reference value (TRV). Based on the multivariate statistics and supported by EF, the sources of pollutants were anthropogenic and natural.