有机物料添加对农田土壤硒有效性影响的环境过程及机制

DDue to both toxic and benifical effects, the selenium (Se) fate in environments has attracted great attention worldwide. Applied Se fertilizer to soil is a common way to inscrease Se in grain and ensure its safe supply in human diet. However, selenium use efficency is very low，and the residual Se in soil can induce potential environmental risk. Therefore, increaseing Se bioavaiability becomes the hotspot for many displines. As the source and pool of Se in soil, organic matter bound Se or organic Se ( Se-OM) occupies nearly half of the total soil Se, some of which can degrade into avaiable Se. At present, little is know about its formation, specaition and its environmental processes, this resulting in difficulty for evaluation of soil Se bioavailability and its regulation. To better understand and improve plant recoveries of Se fertilizers, lab batch experiment, lab incubation experiments, pot experiments, field experiments are planned to conduct, and 75Se isotopic tracing , Diffusive Gradients in Thin-films (DGT), FTIA, SEM and chemical fractionation for Se are planned to adopt for researches. The project focuses on the characteristics of Se-OM speciation distrbuition and reletaed influential factors, and effects of speciation transformation on bioavailability when organic amendment applied, and explores the interaction between dissolved organic matter (DOM) decomposed from organic amendments and selenium as well as their possible mechanism. Improving the assessment method of selenium bioaviability and Se-OM speciation analysis method is another content in order to have a concret basis for Se mangagement. Results of the project will provide some basic knowledge for understanding Se behavior and technology for appraising Se fertilization to its deficient soil, and solving Se deficiency in huamn health and pridicting selenium mobility and risk in the environment.

由于毒害和有益的双重作用，硒在环境中的行为受到广泛关注。采用土施硒肥提高作物含硒量，实现缺硒地区粮食营养安全，已成为农业生产的重要措施。但硒利用率低，施入的硒存在潜在环境风险，硒有效性的研究因此成为多学科研究热点。有机硒几乎占土壤总硒量一半，部分可转化为有效硒，是土壤硒的重要源和库。但对有机硒形成及环境过程了解很少，严重影响土壤硒有效性的评价。针对这一问题，本项目拟采用室内模拟、培养、盆栽和田间试验，用75Se同位素追踪、梯度扩散薄膜技术（DGT）、傅里叶变换红外光谱（FTIR）、扫描电镜和化学浸提技术，研究土壤有机硒形态分布及其影响因素，探讨添加有机物料对硒形态转化及有效性的影响，揭示有机物料影响硒有效性的环境过程及机制；通过探索有机硒形态与有效性的关系，建立有机硒形态测定方法，完善硒生物有效性评价方法。研究结果可为缺硒地区合理补硒，预测硒在环境中的运移及风险，保护人体健康提供科学依据。

本项目通过室内模拟实验、室内培养试验、盆栽试验和田间定位野外试验，用薄膜梯度扩散（DGT）技术、傅里叶变换红外光谱（FTIA）、扫描电镜和连续浸提技术，揭示了外源硒在土壤中的老化过程及其影响因素并提出了外源硒在不同土壤中的老化时间；探讨有机物料添加对硒形态转化及有效性的影响，初步揭示有机物料影响硒有效性的环境过程及机制，建立了土壤DOM结合态硒的浸提方法, 进一步验证了梯度扩散薄膜技术评价土壤硒的生物有效性的可行性及其影响因素（土壤性质、植物种类、外源硒和天然硒等）。另外，开展了植物对不同外源硒吸收转运差异的机制及影响因素的探索工作。完成了4篇有代表性的与土壤-植物体系中硒迁移转化及有效性有关的高水平综述文章。这些研究结果都为缺硒地区补硒和硒中毒地区土壤修复，预测硒在环境中的运移及风险，避免环境污染，保护人体健康提供科学依据。项目执行期间共发表SCI论文 19篇（其中中科院一区论文6篇），EI 2篇，中文论文2篇，培养研究生13名。作为大会主席组织了260人（外宾63人）参加的第六届环境中硒与人体健康国际会议。