abstract
- In this chapter I first give an overview of environmental problems due to contamination by sulfuric acid of surface water systems. Then I specially focus on the sulfuric acid discharge from the acid sulfate soils in tropical peat swamps occurring after agricultural land development in Central Kalimantan, Indonesia. Pyrite-containing sediments can be found in several parts of the world ranging from tropical to Arctic and Antarctic regions. As long as these pyrite-containing sediments remain waterlogged or covered with other sediments without pyrite, the presence of pyrite does not constitute any danger to the environment. Drainage of water or removal of covering layers for agricultural or industrial purposes, however, enable oxygen to enter the pyrite-containing sediments, and subsequently pyrite is oxidized to produce sulfuric acid. One of the regional environmental problems caused by human activities affecting tropical peat swamp forests, especially destruction of peat soil due to agricultural land development, is the oxidation of pyrite within the sediment underneath the peat layer. In order to estimate the range of the area that is affected by the sulfuric acid pollution, the water chemistry of some rivers in Central Kalimantan was surveyed. The sulfuric acid loading from pyrite oxidation appeared from the river mouth up to 135 km upstream. The discharge of pyritic sulfate from peat soil to the limnological system is much higher in the high water table season (October to March) than in the low water table season. Control of pyrite oxidation is indispensable for maintaining sustainable land use of the tropical peat land.