城市污水厂尾水受纳河段沉积物脲酶活性及硝化潜力分析

Sediment urease activity and nitrification potential in the stream reaches receiving effluents from urban wastewater treatment plants

为探究城市污水厂尾水排放对河流沉积物氮素滞留的影响,在合肥市的南淝河、十五里河、塘西河、板桥河和廿埠河各选取一个河段,分3个季节采集尾水排放口上、下游一定范围的河道表层沉积物,解析沉积物脲酶活性、硝化潜力及其变化特征,并对沉积物脲酶活性对外源碳的响应开展定量化分析.结果表明,5个尾水受纳河段排放口下游河道沉积物TN、NH_(4)^(+)-N含量都不同程度的低于上游对照点,多数受纳河段沉积物NO_(3)^(-)-N和OM含量下降,TP则大都不同程度的升高.绝大多数受纳河段尾水排放口下游沉积物脲酶活性低于上游对照点,甚至离尾水排放口距离越近的采样点位脲酶活性越低.5个尾水受纳河段不同程度表现出沉积物脲酶活性随外源碳浓度梯度增大的特点,表明河段沉积物脲酶活性存在一定的碳限制性.南淝河、十五里河和塘西河河段尾水排放口下游所有采样点沉积物硝化速率均高于上游对照点,而板桥河、廿埠河河段则相反.总体上,各尾水受纳河段排放口上游对照点与下游采样点的沉积物脲酶活性、硝化潜力和硝化活性差异性不显著.

To investigate the influences of effluents from urban wastewater treatment plants on nitrogen retention in river sediments,surface sediments and overlying water samples were collected from five stream reaches in Hefei,the Nanfei river(NF),Shiwuli river(SW),Tangxi river(TX),Banqiao river(BQ),and Nianbu river(NB),covering a certain range upper and down the tailwater outlets in three seasons.In this study,the activity of sediment urease,nitrification potential,and their variation were determined,and the response of the activity of sediment urease to exogenous carbon was also analyzed.Results showed that both TN and NH_(4)^(+)-N contents in the sediments downstream of the tailwater outlets were lower than those in the upstream(control).The contents of NO_(3)^(-)-N and OM were decreased in the sediments collected from most of the tested reaches,while the contents of TP increased.The activity of sediment urease in most of the reaches was lower compared with the control,and such a trend was more profound when the sampling site was closer to the outlet.Additionally,the activity of sediment urease was elevated with increasing concentrations of exogenous carbon in all studied reaches,indicating that there was a carbon limitation to the activity of sediment urease.However,there were no obvious trends in the urease activity in the two reaches of NF and SW.The nitrification rates downstream of the tailwater outlets in the NF,SW and TX reaches were higher than the control,while opposite results were observed in the BQ and NB reaches.Generally,the activity of sediment urease,nitrification potential,and nitrification activity were not significantly affected for both of the sediment downstream and the upstream of the outlets.