Impacts of Residential Areas and Aquaculture on the Sediment Quality of Semariang Batu River in Sarawak, Malaysia

The Semariang Batu River is an important spawning ground for fish. Sediment quality affects the overlying water quality. However, sediment quality has not been investigated in detail. Therefore, in this study, surface sediment was sampled at eleven stations including residential areas and aquaculture stations. Results show that pH near riverside village was the lowest among the stations. Organic carbon, total nitrogen and total phosphorus were the highest near the riverside village. At shrimp farm discharge, phosphorus concentration in the sediment ranked second highest among all stations studied. Mean concentration of heavy metals were in decreasing order of zinc>chromium>nickel>lead>copper. Zinc was the highest near the riverside residential village showing residential contributions. Nickel was the highest downstream of riverside village near a cage culture site but was not significantly different from other stations that receive inputs from residential areas. Lead was the second highest near the riverside residential village and the concentrations were higher mostly in the main river, the Semariang River, compared to its tributary likely due to anthropogenic inputs. Copper at shrimp farm discharge ranked the highest but not significantly different from the riverside village station. All heavy metals investigated did not exceed the Consensus–Based Threshold Effect Concentration of USEPA indicating that harmful effects are unlikely to be observed at the stations.