Cd^(2+)、Cu^(2+)和Zn^(2+)对人工湿地反硝化作用的影响

Cd^(2+),Cu^(2+), and Zn^(2+) Influence on Denitrification in Constructed Wetland

实验室研究了 3种重金属离子 Cd2 +、Cu2 +、Zn2 +对人工湿地反硝化作用的影响 .以 1 0 0、50 0、1 0 0 0 mg/kg剂量的 Cd2 +、Cu2 +、Zn2 +处理人工湿地土壤样品 ,检测其 N2 O的产生 .结果表明 ,3种金属离子的 50 0、1 0 0 0 mg/kg处理组土样 N2 O的产生均显著降低 ,各金属离子抑制 N2 O产生的程度顺序为 Cd2 +>Zn2 +>Cu2 +,这与 3种金属离子在土样中的有效态浓度顺序是一致的 ,反硝化微生物在处理过程中逐步产生了对重金属离子的耐受性 ,50 0、1 0 0 0 mg/kg处理组样品的 NH+4- N浓度较对照组显著升高提示部分 NO- 3 - N由于反硝化过程的抑制而异化性还原为 NH+4- N.

Laboratory experiments were conducted to characterise the impacts of 3 heavy metal ions (Cd2+、Cu2+、Zn2+) on denitrification in constructed wetland.Nitrous oxide (N2O) production was determined for soil samples of constructed wetland which exposed to 100,500 and 1000mg/kg levels of Cd2+,Cu2+and Zn2+.The results showed that the soils amended at 500 and 1000mg/kg concentration of 3 heavy metals exhibited significantly lower N2O production than nonamended soils.The relative inhibition on N2O production by individual metals was in order:Cd2+>Zn2+>Cu2+.It conformed to the sequence of available amount of 3 metals in samples.The denitrifying microorganisms developed the resistance to the metal inhibitory effects during the incubition period.Increase of NH+4N in 500 and 1000mg/kg level treated samples suggested some NO-3N was diverted to the pathway of dissimilatory reduction to NH+4N due to the metal inhibition on the denitrification process.