DISTRIBUTION OF METALS IN THE LINGGI RIVER BASIN, MALAYSIA, WITH REFERENCE TO POLLUTION

Pollution inputs into the Linggi River Basin comprise domestic sewage, agroindustrial effluent (especially from rubber factories and plam-oil mills), and effluent from animal-husbandry activities. Total metals were analysed at eight sampling stations located at three highly polluted sub-basins: Linggi, Simin and Kundor. Dissolved metals were analysed occasionally at 21 major tributaries. The following concentrations were found (mg L-1; d.l., detection limit): Na, 0.93-117.73; K, 0.88-77.03; Ca, 1.89-24.00; Mg, 0.30-14.78; Fe, 0.47-12.2; Zn, 0.06-5.12; Cu, < d.l.-2.88; Mn, < d.l.-0.18. Pb, Ni and Cr were not detectable in their dissolved or total forms. Organic sewage inputs greatly increased the concentration of metal ions in reaches just downstream of discharge points. Ion concentrations generally decreased, but not substantially so, in the recovery reaches. Various pollutants contributed differentially to the concentrations of specific metal ions; rubber-factory effluent contributed slightly lower amounts of these ions than did industrial, urban, or palm-oil-mill effluents. No seasonal changes can be readily detected because of the influence of rainfall patterns, variable effluent discharges, and a complex combination of physical, chemical and biological processes occurring in the river.