Sedimentation, Heavy Metals Profiles and Cluster Analysis of a Former Tin Mining Lake

Abstract

Pb-210 method has been applied tosedimentation study on an abandoned tin mining lake inMalaysia. In recent years the lakes areas have been convertedinto more economically important areas with activities such asagriculture, recreational and residential. The sediment profilesat locations in the lakes are expected to be impacted by thedischarge of these near shores and on lakes activities. ThePb-210 depth profiles of the cores enable the respectivesediment 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. Formetals profiles, generally synchronous higher concentrationswere observed in the younger section of the cores. This coincideswith the period of the intensification of anthropogenic activitiesin 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 resultsare twice as high compared to results of a control location onundisturbed land. Discharges from such activities containingheavy metals get their way into the lake through surfacedeposition by rain water, and remobilized from the depositionalareas to the sediment coring sites. U-238 and Th-232 may beattributed to the minerals contained in the tin tailings left in thearea. Cluster analysis of the metals indicated they are of bothanthropogenic and natural origins.