土壤中PAEs与Cd复合污染环境行为及其微生物生态学机理

Phthalic acid esters (PAEs) and cadmium (Cd) are two types of pollutants with great harm to human health and ecosystem safety, having attracted global concern in recent years. These pollutants are widespread in the soil of vegetable field in China.The environmental behavior of PAEs and Cd will present new feature from their combined pollution.However, the reported studies on environmental behavior of PAEs and Cd in soil were mostly based on the single pollution, and rarely based on the combined pollution. In this project, modern molecular biology techniques and the simulation experiments will be taken to study the environmental behavior of PAEs and Cd in the soil and its mechanism under the combined pollution. The forms, plant accumulation, and degradation of PAEs and Cd under combined pollution will be investigated. In addition, the response characteristics of microbial community structure and the functional genes of PAEs degradation under the combined pollution. This study aims to clarifiy the characteristics of environmental behaviors of PAEs and Cd including their form transformation, plant accumulation and biodegradation, and make certain what's the relationship between the soil microbial community structure and the environmental behavior of PAEs and Cd. The achievements of this project will reveal the environmental behaviors of PAEs and Cd under their combined pollution in soil and its microbial ecological mechanism. It is expected that this research will provide a support for the assessment, warning and remediation of soil pollution.

邻苯二甲酸酯(PAEs)类塑化剂与重金属镉(Cd)是近年来备受关注的两类全球性环境污染物，对人体健康及生态系统安全具有极大危害。我国蔬菜生产基地土壤中普遍存在这两类污染物，它们的复合污染将使其环境行为呈现新的特征。然而，目前两类污染物的环境行为研究多基于单一污染状态，针对其复合污染的研究鲜见报道。本项目拟采用模拟实验结合现代分子生物学技术手段，开展土壤中PAEs与Cd复合污染环境行为及其机理研究。重点研究复合污染条件下，PAEs与Cd的赋存形态、植物累积及PAEs的降解动态变化，以及土壤微生物群落结构、PAEs降解功能基因对复合污染的响应规律，阐明PAEs与Cd的形态转化、植物吸收与生物降解等环境行为的主要特征，弄清土壤微生物群落结构与两类污染物环境行为之间的变化关系，揭示PAEs与Cd在土壤中的复合污染环境行为及其微生物生态学机理，为农田土壤污染的评估、预警与修复提供科学依据。

本项目采用模拟实验结合现代分子生物学实验技术研究了PAEs与Cd复合污染环境行为及其微生物生态学机理。土壤中PAEs的降解动力学实验结果表明，土壤微生物对DnBP和DEHP的降解符合一级动力学方程，DnBP在土壤中的半衰期小于DEHP，且初始污染浓度越高，降解所需时间越长；盆栽实验结果表明，土壤中DnBP、DEHP含量随土壤中Cd污染浓度的增加而呈现出逐渐增高的趋势，这表明Cd对DnBP和DEHP的降解具有一定的抑制作用；形态分析结果表明，进入土壤中的Cd主要以可交换态及碳酸盐结合态、Fe/Mn氧化物结合态的形式存在，土壤中各形态Cd含量及植物地上部Cd含量与PAEs的污染浓度之间没有表现出明显的相关关系，这说明PAEs的共存对Cd的形态转化及植物有效性影响较小；土壤微生物活动对PAEs污染的动态响应实验结果发现，DnBP污染促进了土壤的基础呼吸、土壤脱氢酶活性，土壤中DnBP含量与土壤呼吸强度和脱氢酶活力呈极显著正相关（p < 0.01）。PAEs与Cd复合污染条件下，土壤基础呼吸、土壤脱氢酶、脲酶、磷酸酶活力以及土壤微生物种群数量均受到了明显的抑制，且总体上表现出抑制作用随Cd处理浓度的增加而增强的趋势，这说明Cd对土壤中DnBP和DEHP降解的抑制作用主要归因于其对土壤微生物的抑制。. 综上所述，本研究为探讨PAEs与Cd复合污染环境行为及其机理奠定了坚实的工作基础。项目资助发表学术论文9篇，其中SCI论文4篇，核心论文4篇；申请国家专利8项，已获得授权5项。直接培养硕士研究生2名，其中1名已通过毕业答辩，1名在读。项目投入经费25万元，支出21.3176万元，各项支出基本与预算相符。剩余经费计划用于本项目研究后续支出。