Heavy metal pollution is one of the major environmental issues in recent decades owing to the rapid increase in urbanisation and industrialisation. Sediments usually act as sinks for heavy metals due to their complex physical and chemical adsorption mechanisms. In this study, heavy metals like lead (Pb), Zinc (Zn), Cadmium (Cd), Copper (Cu) and Iron (Fe) in the surface sediment from 15 location (upstream and downstream) on the Perak River, Malaysia were investigated by means of inductively coupled plasma optical emission spectroscopy (ICP-OES). The geostatistical prediction map showed the range of Pb, Zn, Cd, Cu and Fe concentration in upstream area was 14.56–27.0 µg/g, 20–51.27 µg/g, 1.51–3.0 µg/g, 6.6–19.12 µg/g and 20.24–56.58%, respectively, and in downstream areas was 27.6–60.76 µg/g, 49.04–160.5 µg/g, 2.77–4.02 µg/g, 9.82–59.99 µg/g and 31.34–39.5%, respectively. Based on the enrichment factor and geoaccumulation index, Cd was found to be the most dominant pollutant in the study area. Pollution load index, sediment quality guidelines and sediment environmental toxicity quotient data showed that the downstream sediment was more polluted than the upstream sediment in the Perak River. The multivariate analysis showed that Pb, Zn and Cu mainly originated from natural sources with minor contribution from human activities, whereas Fe and Cd originated from various industrial and agricultural activities along the studied area.

Environmental degradation in estuaries may lead to a serious threat to marine life and may trigger human health risk with the help of the food web. This study was conducted to evaluate the concentration, distribution, sources, pollution status, and potential risk of contamination of five trace metals (Cd, Cu, Pb, Zn, and Fe) in estuarine surface sediment of ten different estuaries with their physicochemical parameters in the Kelantan State of Malaysia. The heavy metal concentrations in the estuarine surface sediment differ from one estuary to another following the order of: Fe (39.08%) > Zn (37.02 μg/g) > Pb (20.78 μg/g) > Cu (6.68 μg/g) > Cd (3.69 μg/g). The cluster analysis and source identification study indicated that almost all the estuaries are more or less polluted by anthropogenic activities. The Geo-accumulation index (Igeo) showed that all estuaries of the Kelantan Coastline were moderately polluted by Fe and strongly polluted by Cd which was also confirmed by enrichment factor (EF) and integrated potential ecological risk value (RI) assessment. The higher Pollution load index (PLI) values (PLI>1) revealed that all estuaries were polluted by studied trace metal contamination at a different level of magnitude.