TRACE METALS IN SURFACE WATER BODIES
Uncontrolled discharges of heavy metals to surface water bodies pose it threat to humans.wild lire. plants and to micro-organisms. In Sri Lanka heavy metals are used in a greatnumber of industrial applications and metal waste from industry is a form of hazardouswaste. This preliminary study was conducted to determine the levels of heavy metals in thesurface water in Ekala area where some metal-based industries are located.
Samples were collected randomly through the drainage line from the main outlet, randomlyand within two hour intervals, and also from drinking water wells around the area. Totalconcentrations of copper, cadmium, manganese, z inc and chromium were analyscd bynameless atomic absorption spectroscopy and lead was determined by spectrophotometry.Values were compared with untreated and treated samples.
Results show that the effluent may some times be diluted before discharge to the maindrainage system and the metal content is reduced when it go far from the main outlet.Copper and Cadmium values are within the recommended levels but lead and ZIIlCconcentrations are above the Maximum Concentration Limits (MCL) for surface water
In well water manganese and chromium were present in very low or negligible amounts.Copper and cadmium concentrations are well within the maximum tolerance limits fordrinking water bur lead and zinc values are higher than the recommended values. Metalconcentrations are higher at the bottom level of the well water than the surface.