Abstract

Pb-210 method has been applied to sedimentation study on an abandoned tin mining lake in Malaysia. In recent years the lakes areas have been converted into more economically important areas with activities such as agriculture, recreational and residential. The sediment profiles at locations in the lakes are expected to be impacted by the discharge of these near shores and on lakes activities. The Pb-210 depth profiles of the cores enable the respective sediment age and sedimentation rate to be determined. The sedimentation rate was found to be 0.57 ± 0.10 cm.y-1. Age wise, the sediment were about 40 – 50 years old. For metals profiles, generally synchronous higher concentrations were observed in the younger section of the cores. This coincides with the period of the intensification of anthropogenic activities in the area. Mean metal concentrations for all cores for As, Cr, Mn, Zn, U-238 and Th-232 were 48.9 ppm, 41.1 ppm, 407.9 ppm, 199.1 ppm, 30.6 ppm and 85.7 ppm respectively. These results are twice as high compared to results of a control location on undisturbed land. Discharges from such activities containing heavy metals get their way into the lake through surface deposition by rain water, and remobilized from the depositional areas to the sediment coring sites. U-238 and Th-232 may be attributed to the minerals contained in the tin tailings left in the area. Cluster analysis of the metals indicated they are of both anthropogenic and natural origins.