Effect of sulfuric acid discharge on river water chemistry in peat swamp forests in central Kalimantan, Indonesia

Abstract

Effect of sulfuric acid discharge on river water chemistry in peat swamp forests in central Kalimantan, Indonesia Abstract To estimate the range of area that is affected by sulfuric acid pollution after pyrite oxidation, the surface water chemistry of two rivers in peat swamp forests in central Kalimantan, Indonesia, was surveyed at 1.0-to 3.0-km intervals in September 2003 and 2004 (dry season) and March 2004 and 2005 (rainy season). Water discharged from canals into the main stream of the Sebangau River and the Kahayan River showed lower pH compared to the mainstream water of the rivers, implying sulfuric acid loading from the canal to the main stream of the rivers. The ratio of concentrations of sulfate ion/chloride ion, which was used as a parameter for estimating the contribution of pyritic sulfate to river water chemistry, showed that sulfuric acid loading from pyrite oxidation occurred from the river mouth up to 150 km upstream in both rivers. Water of the main stream of the rivers as well as water discharged from artifi cial canals into the main stream in the rainy season showed much higher acidity and a higher ratio of sulfate ion/chloride ion than that in the dry season. This result implies that the discharge of pyritic sulfate from peat swamp forests to the limnological system is much higher in the rainy (high water table) season than the dry (low water table) season. Water in the canal in the rainy season was found to be highly acidic (pH = 2.0-3.0). Pyrite oxidation after peatland development causes not only acidifi cation of soil but also acidifi cation of the limnological ecosystem.

Fluvial organic carbon losses from a Bornean blackwater river

“…Kya, the source of the River Sebangau is approximately 20 km west of Palangka Raya, the provincial capital of Central Kalimantan. Almost the entire catchment is composed of peatland resulting in a high concentration of humic substances in the water, giving the River Sebangau water it's characteristically dark orange-black colour and a background pH of 3.5-4.0 (Haraguchi 2007). The maximum tidal range at the mouth of the River Sebangau is ∼3 m (UKHO, 2008).…”

Characterization of acid sulfate soils and assessing their impact on a humic boreal lake

“…Particularly during high water flow conditions, acidic pore water rich in metals, e.g. Al, Cd, Co, La, Mn, Ni and Zn, is flushed to recipient streams (Åström andBjörklund, 1995a, 1995b;Åström et al, 2010;Haraguchi, 2007;Macdonald et al, 2007;Palko et al, 1985;Weppling, 1993), causing large ecological damage (Hudd et al, 1984;Willett et al, 1993). Most of the released metals are precipitated at river estuaries (Macdonald et al, 2004;Nordmyr et al, 2008).…”

Composition of macrozoobenthos community in the Sebangau River Basin, Central Kalimantan, Indonesia

“…Six main canals have been constr ucted and connected to the Sebangau River. The lower basin of the Sebangau River was reported to be polluted by sulfuric acid after pyrite oxidation, and the water of the river was highly acidic (Haraguchi, 2007).…”

“…Furthermore, the water quality of the Sebangau River in the upper and the middle basin is seasonally stable. The lower basin of the Sebangau River was affected by the sulfuric acid discharged from peat soil in the basin, which was caused by agricultural land modification such as drainage or burning of peat and the consequent production of sulfuric acid after pyrite oxidation underlying the peat layer (Haraguchi 2007).…”

“…The water in the lower basin of the Sebangau River is characterized by high acidity caused by sulfuric acid contamination (Haraguchi 2007). Sulfuric acid in the peat soil discharges to fresh water ecosystems, but the impact of sulfuric acid on river ecosystems has not been investigated in this basin.…”