土壤pH对硝酸根还原过程中N_2O产生的影响

EFFECT OF SOIL pH ON N_2O PRODUCTION IN NITRATE REDUCTION

采用氢氧化钠和盐酸将中性和碱性土壤分别分步调节成具有不同pH的系列土壤 ,加入等量硝态氮后 ,在添加易有效碳源葡萄糖和不添加葡萄糖的厌气条件下进行培养 ,测定不同处理条件下的N2 O和N2 产生速率。结果表明 ,不加碳源培养 2 4h后 ,原中性土壤系列中N2 O的最大产生速率位于pH 5 2 5左右 ,碱性土壤系列的该值位于 5 90左右 ;加入葡萄糖后 ,中性土壤系列中最大N2 O产生速率的pH值不变 ,但产生N2 最大速率的pH已提高至 6 50。而碱性土壤系列中N2 O产生最大速率时的pH值已移至 6 90处 ,即碳源的加入对产生N2 O所需的最佳pH有所提高。试验还显示 ,酸性条件可提高总还原气体中N2 O所占的比例 ,但就N2 O产生速率的绝对值来说 。

By adding NaOH or HCl, one neutral soil and one w eakly alkaline soil was respectively adjusted to a series of samples with differ ent pH After addition of NO 3 - the soil samples were anaerobically incubate d with or without glucose for 24 h After that N 2O production rate was measur ed The results show that without glucose the optimum pH for the greatest N 2O production rate is about 5 25 for the neutral soil series, and 5 90 for the weakly alkaline soil series With glucose, however, the optimum pH for N 2O production is different, at about 6 50 and 6 90 for the neutral soil series a nd the weakly alkaline soil series, respectively, demonstrating that the addit ion of easily available carbon source has raised the optimum pH for N 2O produc tion The experiment results also show that acidic condition could increase the ratio of N 2O to total reduced gas, as for the absolute value of N 2O produc tion, however, the neutral condition is still more favorable