重金属污染土壤中典型抗生素的生物毒性及机制研究

Antibiotics (ATBs) are often introduced into the soil with the application of sludge, sewage and livestock manure, endangering the soil biology system by performing their ecotoxicity and effects to the behavior of heavy metals or other pollutants. The activation to heavy metals by antibiotics in soil at low concentration could aggravate the risk of soil contamination. In order to illustrate the effects of antibiotics to rhizospheric microorganisms, crops, remediation plants, and phytoremediation efficiency, two typical heavy metal contaminated soils with Zn-Cd and Cd-polychlorinated biphenyls (PCBs) contamination were collected for simulation experiments in the laboratory and two more Cd-PCBs-antibiotic contaminated farmland soil caused by long time application of sewage sludge were also employed in this project: 1) to compare the effects of antibiotics by manually added and sewage sludge application on the eco-toxicity of typical heavy metal combined contaminated soils; 2) to estimate the environmental risk of heavy metal combined contaminated soils by microbial toxicity test and phyto-toxicity test with the present of typical antibiotics and to select sensitive bio-indicators for soil contamination estimation; 3) to illustrate toxicity of combined contamination, effects to bioremediation efficiency and the possibility of bio-remediation using hyperaccumulator Sedum plumbizincicola and Leguminous plant alfalfa (Medicago sativa L.) and to analyze the principle; 4) to assess the environmental safety of phytoremediation by means of the selected sensitive bio-indicators. The main purpose of this project is to bring about the efficient, environmental friendly and safe remediation of the typical heavy metal-antibiotic combined soil contamination, so that better suggestion and rules could be provided for the bioremediation of serious practical soil pollution problems in our country and the safety application of sewage sludge all over the world.

抗生素随畜禽粪便、污水污泥等进入土壤，不仅威胁土壤生物，还影响其它污染物的环境行为；低剂量抗生素可活化重金属，加重土壤污染风险。为明确抗生素对典型重金属污染土壤的植物、根际微生物及植物修复效率的影响，本项目拟选择两种典型重金属-持久性有机物污染土壤（Zn-Cd和Cd-PCBs），室内外试验相结合，比较研究抗生素污染的土壤微生物及植物毒性，筛选敏感的生物指标，阐明复合污染土壤的环境风险；探索污染土壤中抗生素对锌镉超积累植物伴矿景天及豆科植物紫花苜蓿等的毒性及重金属、持久性有机污染物修复效率的影响及机制；探明土壤复合污染风险生物联合消减的技术原理及安全性，以期实现典型重金属（有机）-抗生素复合污染土壤的高效、绿色和安全修复。

土壤重金属与持久性有机污染物的复合污染问题随着全球经济的飞速发展越来越普遍。研究农田土壤中重金属等污染物及其与抗生素等新型污染物的复合污染程度、联合作用方式、生态毒性等，尤其是抗生素随现代有机肥料进入土壤后的复合污染毒性，以及抗生素对典型重金属污染土壤的生态毒理效应影响，是针对性开展复合污染土壤生物修复，减少肥料农用环境风险的重要前提。研究外源抗生素对重金属、重金属-有机复合污染土壤的生物毒性，包括对重金属超积累植物、根际协同降解有机污染物的豆科植物的毒性以及根际微生物毒性是进行复合污染土壤生物联合修复、降低土壤复合污染与风险的基础。探明抗生素对重金属复合污染土壤的生态毒性，及其对植物联合修复效率的影响，对于缓解我国土壤复合污染形势，促进重金属复合污染土壤的生物高效修复具有重要意义。. 本研究探讨了复合污染条件下，典型新型污染物抗生素的生态风险及其对土壤原有重金属、有机污染物的生物毒性和生物有效性的影响；土壤复合污染的生态毒性与机理，污染物的相互作用方式；抗生素对修复植物的生态毒性及对土壤目标污染物修复效率的影响及调控原理等，这些内容，对于我国当前的农业发展具有非常重要的现实意义。. 研究表明，土霉素对土壤微生物的作用与土壤基本理化性质、微生物种类和活性、土霉素残留量和时间等因素有关。本研究中土壤微生物生物量碳、硝化潜能、微生物群落功能多样性和脲酶活性可作为复合污染土壤微生物生态毒性的敏感指标。土霉素对不同植物的急性毒性效应不同，但在设置浓度下均能在短期内明显干扰植物体内抗氧化系统与解毒系统的平衡；土霉素通过刺激改变空心菜体内的抗氧化酶活性，影响苗期其他生理活动，高剂量还会损伤叶片组织并导致土壤微生物多样性与活动强度如碳源利用潜能的显著变化。土霉素提高了景天与紫花苜蓿对污染土壤的修复效果，尤其是对镉的修复效果。土霉素能显著提高土壤微生物群落多样性，提高植物修复过程中的修复效果。