渭河河床沉积物对PPCPs的阻滞与释放作用研究

Pharmaceuticals and Personal Care Products have several characteristics after they enter into the environment, such as persistence, bioaccumulation, slow degradability and combined action. Since China has large-scale annual production, using and discharging of the PPCPs antibiotics, it has a serious threat to the environment safety. It is in urgent need of taking actions of PPCPs pollution in the water environment. The application aims at detecting PPCPs in the Weihe River，and the strong blocking effect of river bed deposition layers to pollutants like Pb2+, anthracene and etc.. Typically, focusing on the adsorption/desorption process of PPCPs in the Weihe River and sediments. Basing on PPCPs distribution characteristics and occurrence regularity, we discuss about relationship between PPCPs adsorption capacity and mineral composition, structural features and physicochemical properties of sediments. Clarifying the connection between the fine structure (such as lipids C, alkoxy C, aromatic C, carboxyl C, carbonyl C and etc.) of organic matter and adsorption of PPCPs after dissecting the composition and structure of organic matter of sediments. We study the adsorption/desorption roles of sediments to PPCPs and reveal the characteristics of adsorption kinetics and thermodynamics. Sorting out the relationship between released PPCPs by sediments and the environmental factors (pH, TDS, Eh, DOM). After determining the blocking coefficients of typical PPCPs in the Weihe River sediment layers, it reveals the blocking mechanisms of sediments to PPCPs and thus predicts the pollution risk of PPCPs in groundwater. At last, it provides the technical support for pollutants controlling in type of PPCPs and safety for drinking water.

药品和个人护理用品（PPCPs）进入环境后具有持久性、生物蓄积性、缓慢降解性和多品种共同作用等特点，大量排放严重威胁环境安全，加强PPCPs污染控制刻不容缓。本项申请围绕河床沉积物对PPCPs阻滞与释放的重要作用方式-吸附/解吸展开研究。以野外调查、样品测试、沉积物结构分析、静态吸附实验、砂柱模拟实验和综合分析为手段，探讨PPCPs的分布特征与赋存规律。剖析代表性PPCPs在典型河床沉积物中吸附/解吸行为过程，识别河床沉积物对PPCPs的吸附/解吸的主要影响因素，探索沉积物组分对吸附/解吸的作用机理，揭示PPCPs在沉积物中吸附/解吸动力学及热力学特征及其吸附系数的变化特征，从热力学角度回答PPCPs在河流-沉积物体系中吸附平衡移动的驱动力。评价河床沉积物对典型PPCPs的吸附与阻滞性能，深化沉积物对PPCPs阻滞与释放规律的理解和认识，为河流沿岸地下水中PPCPs类污染控制提供技术支撑。

项目以渭河沉积物对PPCPs的阻滞与释放作用为研究对象，在调研含水结构及PPCPs赋存规律的基础上，研究了沉积物类型、粒径、胶体及主要单矿物、有机组分及级分对抗生素的吸附解吸规律，探讨了吸附机理，分析了DOM（外源性、内源性）、胡敏酸胶 体、Zeta变化对吸附的影响，模拟了抗生素的迁移行为和协同运移过程，获得以下主要结论： .1. 研究区沉积物中代表性抗生素(土霉素OTC、金霉素CTC、美满霉素MC) 的检出率为100%，浓度范围分别为6.13-45.38 ng/g，6.17-32.29 ng/g，4.80-29.74 ng/g，残留量空间差异较大，支流和干流中OTC和CTC大部分处于低生态风险水平，排污口处于中等生态风险水平。.2. 沉积物(一级阶地、河漫滩和河床)对抗生素的吸附量稍有差异，胶体对污染物的吸附量远大于颗粒物，除比表面积效应外，与沉积物有机碳含量、亲水性、芳香性、极性以及类腐殖质和类蛋白质含量有关。将沉积物（OS）中有机质分为：去溶解性有机质级分（RDOM）、去矿级分（RM）、去游离脂级分（RLF）和不可水解有机碳级分（NHC）四个级分，各级分吸附容量KF的大小依次为：NHC≈OS＞RDOM＞RLF＞RM，各级分吸附反应均为自发吸热反应，以物理吸附为主。植物（柳树和芦苇）残体对土霉素的吸附量均为根远大于茎大于叶，腐烂植物远大于原始植物。.3. 沉积物中抗生素的解吸符合准二级动力学模型，为自发放热反应。胡敏酸胶体抑制解吸过程，解吸平衡时间延长，解吸量减少。.4. 无论是外源性还是内源性DOM，源自植物的DOM（类腐殖质），因含有较多芳香环基团增强了吸附作用。源自动物的DOM（类蛋白质）以脂肪链为主，抑制了土霉素吸附。吸附前后体系的ΔZeta变化对吸附有指示作用，ΔZeta越大，沉积物的吸附量越大；添加外源物质(如DOM)后，若ΔZeta变大，则促进吸附，反之，抑制吸附。.5. 模拟了6种情景下抗生素的迁移转化过程，沉积物对土霉素折减率最低为77.5%，虽然可以穿过沉积层，但是进入地下水的浓度很低，且浓度逐渐衰减，对地下水污染轻微，但对沉积层会造成污染。