生物质炭对土壤中阿特拉津降解和淋溶的影响及微生物学机制

Atrazine(AT) is one of the most important herbicides in world.It widely used also in corn and the sorghum in China,especially in the North China and the Northeast area.It is one of permanent organic pollutions, and with very high mobility and long half-life in soil and water, its residues is more than one year. It had directly and indirectly threatened environment and people's health.Therefore, the effectively control the pollution of soils by AT and has become a concern focus by the public. Biochar(BC) is formed by incomplete combustion of biomass and has been shown to be particularly effective in sorption and sequestion of organic contaminants in soil due to its high microporosity, abundant functional groups and other physiochemical properties. It has been generally recongnized to control the contamined soils by organic pollutants in academia. In this study, the BC will be prepare from cassava straws, sugarcane leaves and silkworm excrements.The soils(lateritic red soil and fluvo-aquic soil) will be sampled in Guangxi Zhuang Nationality Autonomous Region. AT and BC are selected as objective pollutant and amendments. Laboratory studies are going to conduct to investigate the effect of the different BC on degredation and leaching of AT in different soils. And microorganisms polulations, microbial activity and microbial biomass will be analyzed with traditional methods, such as the microbial flat count and the fumigation-extration, and so on. The microbial community structure diversity, genetic diversity and functional diversity will be measured by means of BIOLOG-ECO, terminal restriction fragment length polymorphism(T-RFLP) and polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE) technology in order to clarify the microbial mechanism about the effect of BC on degradation and leaching of atrazine in soils.

阿特拉津（AT）具有持久性有机污染物的显著特征，在土壤和水中残留时间可超过1年，对动物有致癌、致畸作用，对人有致突变作用。因此，采取有效措施治理AT污染环境有着重要意义。生物质炭（BC）具有比表面积大、表面官能团丰富、吸附能力强等特点，在治理有机污染物污染土壤方面已经得到了学术界的普遍认可。但是，以往的研究大多侧重于BC对污染物吸附、迁移淋溶的影响，对影响污染物降解的微生物学机制研究较少。本项目拟以AT为目标污染物，BC作为土壤修复剂，通过室内培养和模拟土柱实验，探明BC对AT降解和淋溶的影响；采用传统方法（稀释平板计数法、氯仿熏蒸浸提法等）、分子生物学技术（T-RFLP、PCR-DGGE）和BIOLOG微平板法分析技术研究BC对AT污染土壤微生物数量、生物量、活性及微生物群落结构、遗传基因和代谢功能多样性的变化，从生化和分子生物水平上阐明BC对土壤中AT降解和淋溶的影响及微生物学机制。

本项目以阿特拉津为目标污染物，生物质炭作为土壤修复剂，研究室内模拟条件下，外源生物质炭对土壤中阿特拉津降解与淋溶的影响及其微生物学机理的研究。培养博士研究生1名，培养硕士研究生4名，已发表期刊论文18篇，其中SCI论文5篇，中文核心期刊13篇，申请中国专利4项，完成了预定目标。具体总结（1）吸附实验发现，两种生物质炭对阿特拉津均具有很强的吸附能力。添加生物质炭显著提高了土壤吸附阿特拉津的能力，其中添加甘蔗叶生物质炭提高效果较添加蚕沙生物质炭大。（2）通过室内培养实验研究了生物质炭对土壤中阿特拉津降解的影响，结果表明，灭菌土壤中阿特拉津降解速率要慢于未灭菌土壤。在未灭菌土壤中，添加甘蔗叶生物质炭均延缓了阿特拉津在三种土壤中的降解，延长了其半衰期；在冲积土、潮土中添加蚕沙生物质炭也延缓了阿特拉津的降解，而在水稻土中则促进了阿特拉津的降解。（3）运用模拟土柱淋溶实验的方法研究了甘蔗叶生物质炭和蚕沙生物质炭对阿特拉津在冲积土和潮土中淋溶迁移的影响。结果表明，添加生物质炭显著抑制了阿特拉津在土柱中的淋溶与迁移。在同一种土壤中，生物质炭添加量相同时，甘蔗叶生物质炭对土壤中阿特拉津的淋溶与迁移抑制效果较蚕沙炭明显。（4）添加生物质炭后，提高了阿特拉津污染土壤的微生物量碳、氮的含量。蚕沙和蚕沙炭的添加对阿特拉津污染土壤中过氧化氢酶、脲酶的活性均有促进作用，其中蚕沙原料的效果更好。蚕沙对脱氢酶活性有促进作用，而蚕沙炭则起到抑制作用。通过BIOLOG实验可知，蚕沙和蚕沙炭的添加提高了AWCD值，同时提高了土壤中微生物多样性指数，其中蚕沙的促进效果更为显著。通过高通量测序可知，从细菌来看，Proteobacteria，Bacteroidetes 和Acidobacteria是阿特拉津污染土壤中的优势菌群，蚕沙炭和蚕沙处理提高了Proteobacteria相对丰度，降低了Bacteroidetes的比例。从真菌来看，阿特拉津污染土壤中真菌以Penicillium、Sagenomella、Cephalothecaceae、Aspergillus和 Talaromyces为主菌群。