Volume 2 (2004) Issue 2 Pages 83-90
The function of clams on the decomposition and biodegradability improvement of organic matters in tidal flat sediment were investigated. Moreover, nitrate removal capacity of tidal flat sediments with and without clams was also evaluated. It was found that concentration of DOC in tidal flat sediment with clams was about 1.1-2.1 mg/l higher than that in the sediment without clams. Also NH4-N concentration in the sediment with clams was 0.8-1.8 mg/l higher than that in the sediment without clams. DOC from the sediment with clams was readily biodegradable, while DOC in the sediment without clams was inherent biodegradable substance. Molecular weight of organic matters was distributed from 0.7x102 to 1.7x105 and 0.7x102 to 1.2x106 in the pore water of the sediment with and without clams, respectively. This indicated that clams accelerated the degradation of particulate organic matters and produced DOC, NH4-N and others compounds with higher biodegradability and lower molecular weight. The increase of readily biodegradable compounds as carbon and nutrients sources enhanced microbial growth and accelerated nitrate removal process in tidal flat sediment with clams.