Cu、抗生素协同污染对土壤微生物活性的影响

Collaborative effects of Cu and antibiotic on soil microbial activities

随着畜禽养殖业的规模化发展,重金属和抗生素在土壤环境中协同污染的几率不断升高。为分析和评价重金属、抗生素协同污染对土壤微生物生态系统的影响,以Cu、磺胺甲基嘧啶为添加毒物,其中,Cu的添加质量分数为0、100、500 mg·kg-1;磺胺甲基嘧啶的添加质量分数为0、5、25、50、100 mg·kg-1,采用室内培养试验的方法研究分析了Cu、磺胺甲基嘧啶协同污染对土壤微生物微生物基础呼吸、微生物量碳、微生物量氮、硝化势、尿酶以及脱氢酶等土壤微生物指标的影响。结果表明,与磺胺甲基嘧啶单独污染处理相比,在Cu的质量分数为100 mg·kg-1协同污染污染下土壤微生物呼吸,土壤微生物量碳、氮以及土壤尿酶等指标的活性均明显增加;即表明它们对Cu与磺胺甲基嘧啶的协同污染表现出不同程度的交互抗性;在Cu的协同污染质量分数为500 mg·kg-1,Cu与磺胺甲基嘧啶对土壤各微生物指标则基本表现为协同抑制作用;在不同剂量Cu的协同污染处理下,当磺胺甲基嘧啶处理质量分数≥10 mg·kg-1时,各土壤微生物指标的活性随着其处理质量分数的增加而显著降低,表现出很好的剂量依赖效应。因此,低剂量的Cu-磺胺甲基嘧啶协同污染可能会诱导土壤微生物对二者产生交互抗性;而高剂量协同污染则对土壤微生物生态功能产生较为严重的协同抑制作用。

Heavy metals and antibiotics are two important pollutes in agricultural soil with the development of livestock and poultry industry. To assess the collaborative effects of Cu and sulfamethazine （SMA） on soil microbial ecology, soil microbial basal respiration （SBR）, microbial carbon and nitrogen （MBC and MBN）, potential nitrification rate （PNR）, and soil enzyme activities （Urease and Dehydrogenase） were investigated in soils spiked with Cu and/or SMA. The results indicated that, when Cu was 100 mg＇kg-1 in soils, the activities of SBR, MBC, MBN and Urease were higher in Cu and SMA co-contaminated soil samples than those in SMA presence alone soil samples, which might suggest they possessed cross-resistance of Cu and SMA when both of them co-existed in soils; when Cu was spiked at 500 mg-kg1, activities of all the selected soil microbial properties were seriously inhabited in Cu and SMA joint polluted soils compared to those in SMA presence alone soils, indicating Cu and SMA might have a synergistic stress on soil microbial ecology. At the same time, in all the tested soils, when the concentration of SMA was≥ 10 mg＇kgl, activities of all soil microbial properties decreased with increasing degree of soil pollution by SMA, and they were all significantly negative correlation with SMA stress by correlative analysis.