二甲基二硫（DMDS）是一种新型土壤熏蒸剂，由于能有效控制毁灭性土传病害且对臭氧层无破坏，成为替代溴甲烷的首选药剂之一。但DMDS的高挥发特性不仅决定了其环境行为与药效发挥关系紧密，而且易散发到大气中对人类及非靶标生物安全造成威胁。目前在不同环境条件及施药方式下，DMDS在土壤中的扩散、降解及向大气中散发等环境行为规律还不清楚，也缺乏有效阻控DMDS向大气散发机制研究。因此，本项目利用室内土柱模拟实验及顶空法研究DMDS使用方式、土壤特性及土壤改良剂等对DMDS环境行为的影响，明确关键影响因素及作用机制，并以此为参数建立DMDS在土壤中迁移消解模型，揭示不同条件下DMDS环境行为规律；通过分析土壤改良剂对DMDS的吸附、降解作用与它们理化特性、结构特征间的相关性，明确土壤改良剂阻断DMDS向大气散发的途径与作用机制。项目研究对科学高效使用DMDS、保护人类健康及非靶标生物安全具有重要意义。

Dimethyl disulfide（DMDS）is a new type of fumigant. It is a perfect alternative for Methyl bromide due to its effectiveness against soil-borne pests and its non ozone-depleting potential. DMDS is a highly volatile pesticide，therefore its efficacy in eradicating pests up to its environmental profile. DMDS Gas emits easily into the atmosphere which is a high risk to people and non-target organisms. The distribution, degradation and emission of DMDS under different environmental conditions and application methods are unclear now, there is also a lack of research on emission reduction methods and relative mechanisms. This project will study the effects of soil properties, application methods and soil amendments on the environmental behavior of DMDS, and define the key factors to build a distribution- dissipation model for predicting DMDS environmental behaviors under different conditions. The effects of soil amendments on DMDS emission reduction will be studied, and a definite mechanism of the above effects will be found by analyzing the relationship between adsorption capability and degradation of soil amendments to DMDS. This project has important significance on the scientific use of DMDS. It is also important in outlining ways to protect workers, bystanders and non-target organisms from any toxic gas produced by DMDS.