NH_3-N浓度对太湖竺山湾水体及沉积物中硝化作用的影响

Effects of Different NH_3-N Concentrations on the Nitrification Process in Waters and Sediment from Zhushan Bay,Taihu Lake

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。

Abstract ： 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 am- monia （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 signifi- cantly when NH3-N concentrations were more than 0.15 rag/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 rag/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.