基于抗性菌与生物炭的再生水灌溉土壤重金属修复机制

The shortage of water resources has promoted the recycling use of sewage. Reclaimed water irrigation is an important way to alleviate the shortage of agricultural water resources in the world. With the increase of irrigation area of reclaimed water, the safety of agricultural irrigation with reclaimed water and its influence on ecological environment were of great concern. Long term reclaimed water irrigation can lead to the accumulation of heavy metals in soil. Microbial remediation is the process of using microorganisms to degrade pollutants in the environment or convert them into other harmless substances. As a new kind of environmental material, biochar can not only adsorb heavy metal pollutants, but also can improve soil fertility and soil habitat. The biological toxicity of cadmium is higher, the environmental pollution is particularly serious. In this experiment, the cadmium-resistant bacteria were screened from the soil with long-term reclaimed water. The effect of carrier-microorganism on adsorption capacity of cadmium and environmental conditions were studied, with biochar as microbial carrier. The distribution characteristics and adsorption mechanism of cadmium resistant bacteria were studied in soils irrigated with reclaimed water. The effects of physicochemical characteristics and quality security of crops were explored. And the regulatory mechanism of resistant bacteria on soil micro- environment were clarified under reclaimed water irrigation, which provide a theoretical reference for the ecological safety of reclaimed water irrigation.

水资源的严重短缺推动了污水再生利用。再生水灌溉是世界范围内缓解农业水资源短缺的重要途径。随着再生水灌溉面积的增加，其灌溉安全性及对生态环境的影响日趋引起关注。再生水长期灌溉能够导致土壤重金属的累积。微生物修复是利用微生物将环境中的污染物降解或转化为其他无害物质的过程。生物炭作为一种新型环境材料，不仅能够吸附重金属污染物，而且能够提高土壤肥力，改善土壤生境。镉生物毒性较高，引起的环境污染尤为严重。本试验将从长期再生水灌溉镉污染土壤中筛选出抗镉菌株，以生物炭作为微生物载体，研究了载体-微生物对镉的吸附能力及环境条件对吸附的影响。并通过研究再生水灌溉土壤镉抗性菌的分布特征、吸附机理及作用机制，探索其对土壤理化特性与作物品质安全性的影响机理，进而阐明再生水灌溉土壤抗性菌株对土壤微环境的调控机制，为再生水灌溉的生态安全提供理论参考。

水资源短缺是当前中国农业生产所面临的重大挑战。污水再生回用具有显著的社会、经济效益，已成为缓解水资源危机的一项重要举措。长期再生水灌溉土壤重金属可能累积至危害水平，给土壤生态环境带来一定的风险。微生物修复重金属技术因其具有处理费用低，对环境影响小等优点，越来越受到广泛关注。本试验通过长期再生水灌溉农田土壤镉抗性菌株的筛选及其生长特性和吸附机理研究，探索了以生物炭为载体的抗性菌剂对重金属镉的修复机制及其对土壤理化特性与作物品质安全性的影响机理。研究表明：在培养时间一定时，随着 Cd2+浓度的增加，抗性菌株对 Cd2+ 的吸附率减少，而生物吸附量则逐渐增加。在Cd2+浓度一定时，随着培养时间的延长，抗性菌株对Cd2+的吸附率呈现出先升高后降低的趋势。通过生物炭-抗性菌株联合，促进了微生物生物量的增加和菌株活性的提高，提高了对重金属镉的吸附效率。镉抗性菌株的抗性与细胞的翻译过程的调控改变有关，菌株抗性主要与结合和催化活性有关。抗性菌株通过细胞膜运输，酶激反应等与重金属结合，促进重金属Cd的吸收和转运。菌剂添加促进了小麦植株生长发育，显著增加了小麦产量。菌剂施用能够降低土壤有效态Cd含量，减少再生水灌溉下小麦植株对重金属Cd的吸收，有利于保障粮食安全，该研究为科学利用农业水资源，实现再生水农田灌溉安全提供重要的理论依据。