短链有机酸对多环芳烃在水体沉积物中迁移转化的影响研究

With the rapid development of economy, lots of polycyclic aromatic hydrocarbons (PAHs) have been generated and the persistence of these petroleum pollutants in aquatic environment has been of great public concern. Pollution caused by these compounds has been demonstrated to be a threat to ecosystem, food safety and human health due to their toxic characteristics. A well understanding of environmental behaviors of the PAH contanimants under complicated conditions is still challenging in many respects. In this study, we will investigate the temporal and spatial distribution of short-chain organic acids (SCOAs) in aquatic sediments and the uptake of SCOAs on sediments. The influence of SCOAs on sorption and desorption of PAHs will be evaluated. The related events and mechanisms will be studied to characterize the complicated interactions between SCOAs and PAHs during this process. The study will present the distribution of PAHs in sediment organic matter in the presence of SCOAs as well as the relation between the effects of SCOAs and the properties of organic matter in aquatic sediments. The performance of biodegradation will be studied to investigate the effects of SCOAs on microorganism and related degradation mechanism. Also the carbon and energy sources in degradation and dynamic characteristics as influenced by SCOAs will be investigated. The results from this study may have important implications for better understanding the behaviors of hydrophobic organic compounds in aquatic environment. The study can also help obtain more theoretical foundation for risk management and treatment applications for the remediation of PAH-contaminated aquatic environment.

随着国民经济的发展，我国水体的多环芳烃污染问题已日益凸现，对生态环境、食品安全和人体健康已构成了严重威胁。本项目针对有机污染物在水环境行为的复杂性，探索水体沉积物中短链有机酸的空间变化特征和留存机理，明确短链有机酸对多环芳烃在水体沉积物中的吸附与解吸过程的影响，从微观尺度揭示短链有机酸与水体沉积物污染物的复杂作用机制，探索短链有机酸存在条件下多环芳烃在水体沉积物有机质组分中的分配过程，确定短链有机酸的影响与水体沉积物有机质组分特性的关系，考察短链有机酸对水体沉积物微生物的生长特性及其降解多环芳烃机理的影响，研究短链有机酸对水体沉积物微生物代谢碳源与能源选择及降解过程动力学的影响。该研究对深入理解水体中疏水性有机污染物的环境效应具有重要理论意义，并可为水环境多环芳烃污染的风险控制和修复工程实践提供科学依据和技术支撑。

随着国民经济的发展，我国水体的芳香性污染物污染问题已日益凸现，对生态环境、食品安全和人体健康已构成了严重威胁。本项目针对有机污染物在环境行为的复杂性，探索环境沉积物中有机酸的空间变化特征和留存机理，明确有机酸在水体沉积物中的吸附与解吸过程的影响，从微观尺度揭示有机酸与沉积物污染物的复杂作用机制。主要研究结果包括如下几方面：（1）磺化腐植酸的去除率随着粉煤灰投加量的增加而升高，并随温度的升高而增加，较低pH及较低离子强度均对吸附有利；磺化腐植酸在粉煤灰上的吸附可以用Langmuir吸附等温线模型较好地描述；该吸附过程符合二级动力学模型；并且为自发、吸热、熵增加的过程。（2）过改性的粉煤灰，不仅表面发生了变化，结构上也产生了改变。由于表层孔洞被疏通，其比表面积增加，物理吸附作用因此加强，从而提高了磺化腐植酸在粉煤灰上的吸附量；改性粉煤灰的动力学、热力学以及吸附条件的影响与原样粉煤灰一致。（3）探讨了丹宁酸在改性粉煤灰上的吸附情况，并研究了吸附剂投加量、接触时间、温度和离子强度对吸附过程的影响。当粉煤灰投加量从0到20g/L变化时，丹宁酸的吸附明显增加。该吸附可以较好的用Freundlich和Langmuir吸附等温线模型模拟。吸附大约在90min达到反应平衡，该过程可以用二级动力学模型拟合。丹宁酸的吸附量在20°C时高于其他温度。热力学研究表明丹宁酸在改性粉煤灰上的吸附为放热过程，熵呈递减趋势。丹宁酸在粉煤灰上的去除率随着NaCl浓度从0到0.4 mol/L范围呈递减趋势。