FACTORS ACIDIFING PEAT IN CENTRAL KALIMANTAN, INDONESIA

摘要

The chemical properties of peat pore water in the basin of the Sebangau River and Lahei district, Central Kalimantan, Indonesia, were studied. We analyzed chemical properties of the peat pore water with reference to their vertical profile. We evaluated the contribution of sulfates to the acidification of peat. The lower basin of the Sebangau River included extraordinarily high concentrations of sulfates ( > 1,000 mg/L) compared to the peat in the middle and upper basins of the river ( < 10 mg/L). High concentrations of sulfates, however, did not lead to a low pH for the peat. Water discharged from canals into the mainstream of the Sebangau River showed lower pH compared to the mainstream water of the rivers, implying sulfuric acid loading from the canal to the mainstream of the rivers. The ratio of SO_4~(2-)/Cl~-, which was used as a parameter for estimating the contribution of pyritic sulfate to the river water chemistry, showed that the sulfuric acid loading from pyrite oxidation appeared from the river mouth up to 135 km upstream in the river.