不同污染方式下铅对茶园土壤氮素转化及其相关微生物和酶活性的影响

为探讨不同污染方式的Pb对茶园土壤氮素转化的影响,采用盆栽试验对累积和一次性添加不同浓度Pb条件下茶园土壤中氮素含量、相关微生物和酶活性进行了研究。结果表明：累积污染处理的土壤中Pb全量和有效态含量高于一次污染处理。Pb污染对土壤、茶苗植株的氮含量影响表现为：增加土壤中全氮和¹⁵N含量,减少茶苗地上部全氮和¹⁵N含量。添加Pb浓度为900 mg/kg时,累积污染处理促进根系全氮和¹⁵N含量,一次污染则显著抑制;累积污染处理的茶苗根和地上部中的氮含量显著高于一次污染(P<0.05)。Pb污染对氮循环相关微生物的影响表现为：氨化细菌、自生固氮菌、亚硝酸细菌和硝酸细菌的数量减少,反硝化细菌的数量增加。Pb的不同污染方式对茶园土壤与氮循环相关微生物数量的影响不显著(P>0.05)。Pb污染抑制脲酶、亚硝化还原酶和硝酸还原酶活性,对蛋白酶活性存在“低促高抑”现象;高浓度Pb(900 mg/kg)污染时,累积处理显著增加土壤羟胺还原酶活性,一次处理则显著抑制。两种污染方式对土壤脲酶、硝酸还原酶和羟胺还原酶活性的影响因Pb...

Effects of Lead on Nitrogen Transformation and Related Microorganisms and Enzyme Activities in Tea Garden Soil Under Different Pollution Modes

In order to investigate the effects of lead pollution on the soil nitrogen transformation in tea plantation under different pollution modes, pot experiment was conducted to study the nitrogen content, related microorganisms and enzyme activities in tea garden soil under different concentrations of lead with accumulation and one-time addition. The results showed that the total and available contents of lead in soil under cumulative addition treatment were higher than that under one-time addition. The effects of lead pollution on nitrogen contents of tea plant and soil were as follows: the contents of total nitrogen and N15 in soil increased, while the contents of total nitrogen and N15 in overground part of tea plant decreased. When the lead concentration was 900 mg/kg, the contents of total nitrogen and N15 were promoted in the cumulative treatments, and significantly inhibited in the one-time treatments. The nitrogen contents in root and shoot of tea seedlings treated with cumulative addition was significantly higher than that with one-time addition (P < 0.05). The effects of lead pollution on microorganisms related to nitrogen cycle were as follows: the number of ammonifying bacteria, azotobacter, nitrite bacteria and nitrate bacteria decreased, while the number of denitrifying bacteria increased. The number nitrogen cycling related microorganisms in tea garden soil were not significantly affected by different adding modes of lead (P > 0.05). Lead pollution inhibited the activities of urease, nitrifying reductase and nitrate reductase, activated the activity of hydroxylamine reductase, and showed a phenomenon of "low promotion and high inhibition" on protease activity. The activities of urease, nitrate reductase and hydroxylamine reductase in soil were significantly affected by different adding modes of lead (P < 0.05). Correlation analysis showed that soil microbial quantity, protease, nitrite reductase and nitrate reductase activities were significantly negatively correlated with the available lead content in tea garden soil (P < 0.01).