The Siak is a black water river in central Sumatra, Indonesia, which owes its brown color to dissolved organic matter (DOM) leached from surrounding, heavily disturbed peat soils. The dissolved organic carbon (DOC) concentrations measured during five expeditions in the Siak between 2004 and 2006 are among the highest reported world wide. The DOM decomposition appeared to be a main factor influencing the oxygen concentration in the Siak which showed values down to 12 μmol l−1. Results derived from a box-diffusion model indicated that in addition to the DOC concentration and the associated DOM decomposition the water-depth also plays a crucial role in regulating the oxygen levels in the river because of its impact on the turbulence in the aquatic boundary layer and the surface/volume ratio of water in the river. Model results imply furthermore that a reduced water-depth could counteract an increased oxygen consumption caused by an enhanced DOM leaching during the transition from dry to wet periods. This buffer mechanism seems to be close to its limits as indicated by sensitivity studies which showed in line with measured data that an increase of the DOC concentrations by ~15% could already lead to anoxic conditions in the Siak. This emphasizes the sensitivity of the Siak against further peat soil degradation, which is assumed to increase DOC concentrations in the rivers.
Rixen T., Baum A., Pohlmann T., Balzer W., Samiaji J. and Jose C. (2008) The Siak, a tropical black water river in central Sumatra on the verge of anoxia. Biogeochemistry 90(2): 129-140. 10.1007/s10533-008-9239-y
@article{Rixen2008,
Title = {The Siak, a tropical black water river in central Sumatra on the verge of anoxia},
Author = {Rixen, Tim and Baum, Antje and Pohlmann, Thomas and Balzer, Wolfgang and Samiaji, Joko and Jose, Christine},
Editor = {},
Journal = {Biogeochemistry},
Year = {2008},
Pages = {129-140},
Volume = {90},
Doi = {10.1007/s10533-008-9239-y},
Abstract = {The Siak is a black water river in central Sumatra, Indonesia, which owes its brown color to dissolved organic matter (DOM) leached from surrounding, heavily disturbed peat soils. The dissolved organic carbon (DOC) concentrations measured during five expeditions in the Siak between 2004 and 2006 are among the highest reported world wide. The DOM decomposition appeared to be a main factor influencing the oxygen concentration in the Siak which showed values down to 12 μmol l−1. Results derived from a box-diffusion model indicated that in addition to the DOC concentration and the associated DOM decomposition the water-depth also plays a crucial role in regulating the oxygen levels in the river because of its impact on the turbulence in the aquatic boundary layer and the surface/volume ratio of water in the river. Model results imply furthermore that a reduced water-depth could counteract an increased oxygen consumption caused by an enhanced DOM leaching during the transition from dry to wet periods. This buffer mechanism seems to be close to its limits as indicated by sensitivity studies which showed in line with measured data that an increase of the DOC concentrations by ~15% could already lead to anoxic conditions in the Siak. This emphasizes the sensitivity of the Siak against further peat soil degradation, which is assumed to increase DOC concentrations in the rivers.},
}
TY - JOUR
AU - Rixen, Tim
AU - Baum, Antje
AU - Pohlmann, Thomas
AU - Balzer, Wolfgang
AU - Samiaji, Joko
AU - Jose, Christine
TI - The Siak, a tropical black water river in central Sumatra on the verge of anoxia
T2 - Biogeochemistry
PY - 2008
SP - 129-140
VL - 90
DO - 10.1007/s10533-008-9239-y
AB - The Siak is a black water river in central Sumatra, Indonesia, which owes its brown color to dissolved organic matter (DOM) leached from surrounding, heavily disturbed peat soils. The dissolved organic carbon (DOC) concentrations measured during five expeditions in the Siak between 2004 and 2006 are among the highest reported world wide. The DOM decomposition appeared to be a main factor influencing the oxygen concentration in the Siak which showed values down to 12 μmol l−1. Results derived from a box-diffusion model indicated that in addition to the DOC concentration and the associated DOM decomposition the water-depth also plays a crucial role in regulating the oxygen levels in the river because of its impact on the turbulence in the aquatic boundary layer and the surface/volume ratio of water in the river. Model results imply furthermore that a reduced water-depth could counteract an increased oxygen consumption caused by an enhanced DOM leaching during the transition from dry to wet periods. This buffer mechanism seems to be close to its limits as indicated by sensitivity studies which showed in line with measured data that an increase of the DOC concentrations by ~15% could already lead to anoxic conditions in the Siak. This emphasizes the sensitivity of the Siak against further peat soil degradation, which is assumed to increase DOC concentrations in the rivers.
ER -
