外源土霉素和磺胺二甲嘧啶对土壤活性有机碳含量的影响

Effects of Exogenetic Oxytetracycline and Sulfamethazine on Soil Labile Organic Carbon Contents

为了解外源抗生素对土壤内环境的影响,基于盆栽试验研究了不同浓度土霉素(OTC)和磺胺二甲嘧啶(SMZ)对土壤微生物量碳(MBC)、水溶性有机碳(WSOC)、易氧化碳(ROC)以及溶解性有机碳(DOC)含量的影响。结果表明,4种活性有机碳指标对抗生素敏感性大小顺序为WSCO>MBC>DOC>ROC。WSOC和DOC含量随OTC和SMZ浓度升高整体呈递增趋势,WSOC最大增幅分别达137.1%和251.8%,DOC最大增幅分别达31.9%和10.7%;MBC和ROC含量随OTC和SMZ处理浓度递增而降低,MBC最大降幅分别达47.8%和52.4%,ROC最大降幅分别达4.9%和7.4%。同一浓度SMZ胁迫对活性有机碳整体的影响效果强于OTC。OTC和SMZ浓度分别低于50 mg·kg-1和10 mg·kg-1时,土壤受到污染程度较低,能够自我修复;OTC和SMZ浓度分别达100~200 mg·kg-1和50~100 mg·kg-1时,培养期结束土壤仍处于轻度污染,存在较大环境风险。

Long-term applications of livestock excreta could lead to antibiotic accumulation in soils,thus affecting the ecological environment. In order to understand the impact of antibiotics on soil environment,a pot experiment was conducted to examine the effects of oxytetracycline(OTC)and sulfamethazine(SMZ)at different concentrations on soil microbial biomass carbon(MBC),water soluble organic carbon(WSOC),readily oxidized carbon(ROC)and dissolved organic carbon(DOC). Four types of labile organic carbons were sensitive to antibiotics as follows:WSCO>MBC>DOC>ROC. The contents of WSOC and DOC increased with increasing rates of OTC and SMZ. Applying OTC and SMZ led to a greatest increase of 137.1% and 251.8% for WSOC,and 31.9% and 10.7% for DOC,respectively. However,OTC and SMZ additions decreased soil MBC and ROC,with the largest reduction of 47.8% and 52.4% for MBC,and 4.9% and 7.4% for ROC,respectively. The soil could self-restore when OTC and SMZ were less than 50 mg·kg-1and 10 mg·kg-1,respectively. However,the soil showed mild pollution at end of the experiment when exposed to 100~200 mg·kg-1OTC and 50~100 mg·kg-1SMZ,respectively,thus possessing environmental risk.