Trace Metal Concentrations in an Agricultural Watershed: Case Study in the Sumani Watershed, West Sumatera Indonesia

Abstract

Selected trace metals investigation of agricultural soil at sawah, vegetable and river sediment in Sumani watershed, West Sumatra, Indonesia were conducted to determine their abundances and to assess contamination levels. pH, CEC and TC values indicates moderate to high soil fertility status. Average concentrations of Pb, Zn, Cu, TiO2, Fe2O3 and P2O5 were greater than those of Bulk Composition Crust (BCC) and UCC in most areas. Enrichment factor values at Sawah confirms depletion to minimal enrichment with most metals, while vegetable area indicates moderate enrichment with Pb, Cu and Rb, and depletion to minimal enrichment for Zn, Ni, Cr, V and Sr. Igeo values for Pb, at Sawah were unpolluted to moderately polluted but practically unpolluted for Zn, Cu, Ni, Cr, V, while vegetable area were moderately polluted with Pb, unpolluted to moderately polluted with Cu and Rb and and practically unpolluted for Zn, Ni, Cr, V and Sr. Elevated values of Pb in vegetable area, possibly due to volcanic ash from mount Talang, excess application of fertilizers and pesticides, and high contents of Pb in gasoline, Indonesia.