铜污染胁迫条件下农田土壤酶活性及微生物多样性对大气CO2浓度升高的响应

在开放式大气CO2浓度升高平台上（Free-Air CO2 Enrichment,简称FACE）,采用盆栽实验,研究了不同浓度Cu污染胁迫条件下,稻麦轮作土壤中土壤酶活性及土壤微生物多样性对大气CO2浓度升高的响应。结果表明,大气CO2浓度升高显著诱导了清洁土壤中蛋白酶、脲酶、尿酸酶活性以及微生物多样性;正常大气和大气CO2浓度升高条件下,3种酶活性都随着土壤Cu污染胁迫的增加而逐渐降低;低浓度Cu污染胁迫条件下（50 mg.kg^-1）,FACE圈中的土壤脲酶和蛋白酶活性显著高于正常大气（Ambience）圈,尿酸酶活性无显著变化;高浓度Cu污染胁迫条件下（400 mg.kg^-1）,土壤脲酶与蛋白酶活性无显著变化,尿酸酶活性则显著降低,其原因可能与不同酶系对铜污染胁迫的敏感差异性以及大气CO2浓度升高对土壤中铜的活化作用有关。与清洁土壤相比,低浓度Cu污染（50 mg.kg^-1）对微生物生长具有一定的刺激作用,Ambience圈和FACE圈土壤微生物多样性都有所增加,FACE圈中这种现象更为明显;高浓度Cu污染胁迫（400 mg.kg^-1）对土壤微生物表现出了明显的毒害作用,微生物多样性有所降低,但在FACE圈中土壤微生物多样性的降低程度要低于Ambience圈,其影响机制有待进一步研究。

Response of Soil Enzymes and Microbial Communities to Elevated Concentration of Atmospheric CO2 Under Stress of Cu Pollution

The effects of elevated CO2 on soil enzyme activity and microbial diversity under Cu pollution stress were studied in soil with rice-wheat rotation cropping in China FACE（Free-Air CO2 Enrichment）platform.Enzyme activities（protease,urease,and uricase）and microbial diversity were stimulated by elevated CO2 in soil without Cu contamination.At low Cu concentration（50 mg.kg-1）,soil urease and protease activities were significantly stimulated by elevated CO2,however,no significant effect on uricase activity.At high Cu concentration（400 mg.kg-1）,soil uricase activity significantly decreased under the FACE conditions while urease and protease activities showed no significant change.We hypothesized that soil enzymes might have different sensitivities to Cu contamination and Cu species under different CO2 concen-trations.Low Cu contamination had certain stimulations on microbial growth under normal atmospheric CO2 concentration;however,the stim-ulation significantly increased under the FACE conditions.Soil microbial diversity was inhibited by high Cu contamination under both normal and elevated atmospheric CO2 concentrations,with much higher inhibition in the ambience rings.The results indicated that the stress of Cu pollution on soil enzymes and microbial community might be alleviated under elevated atmospheric CO2 concentration;however,the mecha-nism needed to be further studied.