NH3-N浓度对太湖竺山湾水体及沉积物中硝化作用的影响

通过模拟培养试验,比较不同浓度非离子态氨(NH3-N)条件下,富营养化湖泊———太湖竺山湾水体及沉积物中硝化作用2个过程,即氨氧化和亚硝酸盐氧化的发生情况。结果表明,在试验设置的NH3-N浓度范围内,水体和沉积物中氨氧化速率都随着NH3-N浓度的升高显著增加(LSD检验,P<0.05),亚硝酸盐氧化速率却呈阶段性变化。水体中NH3-N浓度大于0.35 mg/L时,亚硝酸盐氧化速率开始显著降低(LSD检验,P<0.05),而氨氧化速率与亚硝酸盐氧化速率的比值从NH3-N浓度为0.15 mg/L开始随着NH3-N浓度的升高而显著增加,说明水体中亚硝酸盐氧化过程在NH3-N浓度为0.15 mg/L时已受到部分抑制;沉积物中亚硝酸盐氧化速率在NH3-N浓度大于0.65 mg/L时开始降低(LSD检验,P>0.05),而氨氧化速率与亚硝酸盐氧化速率的比值从NH3-N浓度为0.35 mg/L开始随着NH3-N浓度的升高而显著增加,说明沉积物中亚硝酸盐氧化过程在NH3-N浓度为0.35 mg/L时已受到部分抑制。太湖竺山湾水体中的NH3-N浓度为0.19 mg/L,已达到对亚硝酸盐氧化过程的抑制范围;沉积物间隙水中NH3-N浓度为0.16 mg/L,还未对亚硝酸盐氧化过程产生抑制效果。

Effects of Different NH3-N Concentrations on the Nitrification Process in Waters

Through the in-door simulation experiment,two processes of nitrification,namely ammonia oxidation and nitrite oxidation in water and sediment from Zhushan Bay of Taihu Lake were studied under different unionized ammonia(NH3-N) concentrations.The results showed that,in the range of ammonia concentrations designed in the experiment,ammonia oxidation rates in water and sediment increased significantly with the increasing of NH3-N concentrations(LSD test,P<0.05).However,the occurrence of nitrite oxidation process had different stages.In water,nitrite oxidation rates started to decrease significantly(LSD test,P<0.05) when NH3-N concentrations were more than 0.35 mg/L.The ratio between ammonia oxidation rates to nitrite oxidation rates increase significantly when NH3-N concentrations were more than 0.15 mg/L,indicating that nitrite oxidation rate has been partly inhibited when NH3-N concentration was 0.15 mg/L.NH3-N concentration in the water of Zhushan Bay,Taihu Lake was 0.19 mg/L which has achieved the range of inhibition to nitrite oxidation.In sediment,nitrite oxidation rates started to decrease(LSD test,P>0.05) when NH3-N concentrations were more than 0.65 mg/L.The ratios between ammonia oxidation rates to nitrite oxidation rates increased significantly when NH3-N concentrations were more than 0.35 mg/L,indicating that nitrite oxidation rate has been partly inhibited when NH3-N concentration was 0.35 mg/L.NH3-N concentration in the interstitial water of Zhushan Bay,Taihu Lake was 0.16 mg/L which has not resulted in significant inhibition to nitrite oxidation.