标题：Nitrification Potential of Mud Sediment of the Ariake Sea Tidal Flat and the Individual Effect of Temperature, pH, Salinity and Ammonium Concentration on its Nitrification Rate
期刊名称：Research Journal of Environmental and Earth Sciences
印刷版ISSN：2041-0484
电子版ISSN：2041-0492
出版年度：2011
卷号：3
期号：5
页码：587-599
出版社：Maxwell Science Publications
摘要：The aims of this study were to know the nitrification potential of the mud sediment of the Ariake sea tidal flat, and to investigate the individual influence of environmental parameters such as temperature, pH, salinity and ammonium concentration on its nitrification rate. The Ariake Sea is a semi-closed shallow sea with macro-tidal and the largest tidal flat in Japan. Nitrification Potential Rate (NPR) and Nitrification Rate (NR) of the tidal flat mud sediment were determined by amending sodium chlorate to inhibit the oxidation of NO2-N to NO3-N. NPRs of the sediment were 91.4, 71.2 and 64.8 nmol N/g Dry Weight Sediment (DWS)/h at the depth of 0-3, 3-6 and 6-9 cm, respectively. NRs were relatively high in the temperatures range of 20-35oC with the optimum temperature of 29.3oC. Relatively high NRs were determined in the range of pHs 7.5-8 with the optimum pH 7.7. The optimum salinity for nitrification was 15 ppt. NRs increased drastically in the range of salinity 10 to 15 ppt, but it decreased sharply at 15 to 20 ppt. Relationship between ammonium concentration and NR resulted a hyperbolic Michaëlis-Menten type curve (R2 = 0.98) with the maximum NR rate ( Vmax ) 32.5 nmol N/g DWS/h at NH4-N concentration 3,000 mM and the half saturation constant ( Ks ) 700 mM NH4-N. To our knowledge, this is the first report on nitrification of mud sediment of the Ariake sea tidal flat, and its optimal temperature, pH, salinity and NH4-N concentration as a single parameter.
