汪洋沟表层沉积物中总氮含量和氨氮释放特征

对汪洋沟6个样点沉积物样品的总氮含量以及沉积物中NH4+-N的释放动力学特征、释放潜能进行了研究。结果表明,汪洋沟沉积物中总氮含量在0.368~2.036 g/kg之间,平均值为1.037 g/kg。NH4+-N最大释放量在0.258~0.705 g/kg之间,释放主要集中在0~5 min内,约占最大释放量的79%~84%;随后释放速率逐渐放缓,到120 min后基本达到释放平衡。运用无限稀释法对沉积物NH4+-N释放潜能进行测定表明,汪洋沟沉积物NH4+-N释放潜能在0.351~0.706 g/kg之间,在水土质量比约为2 500时,NH4+-N释放量达到最大,随后释放逐渐趋于平衡。汪洋沟沉积物NH4+-N释放潜能及最大释放量与总氮含量呈正相关。汪洋沟沉积物中总氮含量与NH4+-N释放潜能低于洱海,与长江中下游湖泊相近,汪洋沟沉积物氨氮释放存在一定的风险。

Total nitrogen content and release characteristics of ammonium in surface sediment of Wangyang River

The total nitrogen content and the ammonium release kinetics of 6 sediment samples from the Wangyang River were determined. The results indicated that the total nitrogen content in the sediments varied from 0.368 g/kg to 2.036 g/kg with the mean value of 1.037 g/kg. The release kinetics of NH4+-N in the sediment surface was well simulated by the first-order kinetic equation, and the greatest amount of the released NH4+-N was between 0.258 g/kg and 0.705 g/kg. The release process of NH4+-N was mainly appeared within the first five minutes, and the amount released within 0~5 min accounted for approximately 79%~84% of the total release capacity. The release potential ability of NH4+-N was between 0.351 g/kg and 0.706 g/kg and the ammonium potential release capacity reached to the maximum value when the water/sediment ratio was about 2 500. The release potential ability of NH4+-N and the greatest amount of NH4+-N reached in sediment samples of Wangyang River were positively related to the total nitrogen content. The total nitrogen content and the release potential ability of NH4+-N are lower than those from Erhai Lake, nearly to those from the lakes in the middle and lower reaches of the Yangtze River region.