Effects of Different NH3-N Concentrations on the Nitrification Process in Waters and Sediment from Zhushan Bay,Taihu Lake
NH3-N浓度对太湖竺山湾水体及沉积物中硝化作用的影响

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.