College of Environment and Resource, Shanxi University, Taiyuan 030006, China; Department of Environmental Sciences, University of California, Riverside, CA 92521, USA; Guangzhou Key Laboratory of Environmental Exposure and Health, School of Environment, Jinan University, Guangzhou 510632, China.
College of Environment and Resource, Shanxi University, Taiyuan 030006, China.
Ecotoxicol Environ Saf. 2019 Mar;169:353-360. doi: 10.1016/j.ecoenv.2018.11.034. Epub 2018 Nov 17.
The adsorption of phthalate esters (PAEs) in mangrove sediment greatly influences their availability to aquatic organisms, however, the adsorption processes of PAEs in mangrove sediment, as well as the effects of root exudates, are poorly understood. In this study, dimethyl phthalate (DMP), diethyl phthalate (DEP) and dibutyl phthalate (DBP) was used as model PAEs to determine the effects and mechanism of citric acid on the adsorption kinetics and isotherms of PAEs in the mangrove sediments. The adsorption kinetics followed pseudo-second order model, describing the characteristics of heterogeneous chemisorption of PAEs in mangrove sediments. The adsorption isotherms of DMP and DEP followed Freundlich model, implying the characteristics of surface multilayer heterogeneous adsorption; while the Henry model better described the adsorption isotherms of DBP, suggesting that hydrophobic partition accounted for DBP adsorption in the mangrove sediments. Inter-chemical variability was observed in adsorption capacity (q) with the sequence of DBP > DEP > DMP. Surface polarity index ((C-O + COOH + C˭O)%) of particulate organic matter (POM) regulated the adsorption capacity of DMP and DEP in mangrove sediments, while different POM content among mangrove sediments explained the difference in the sorption strength for DBP. The presence of citric acid enhanced the q of the three PAEs by 6.4-12.6%. These findings are of great significance to reveal that the root exudates play a crucial role in the PAEs adsorption in mangrove sediments, and provide valuable information for availability of PAEs in mangrove ecosystem.
邻苯二甲酸酯（PAEs）在红树林沉积物中的吸附极大地影响了其对水生生物的有效性，但人们对 PAEs 在红树林沉积物中的吸附过程以及根分泌物的影响知之甚少。在本研究中，以邻苯二甲酸二甲酯（DMP）、邻苯二甲酸二乙酯（DEP）和邻苯二甲酸二丁酯（DBP）为模型 PAEs，以确定柠檬酸对 PAEs 在红树林沉积物中吸附动力学和吸附等温线的影响和机制。吸附动力学符合拟二级动力学模型，描述了 PAEs 在红树林沉积物中异质化学吸附的特征。DMP 和 DEP 的吸附等温线符合 Freundlich 模型，表明了表面多层异质吸附的特征；而亨利模型更好地描述了 DBP 的吸附等温线，表明疏水分配解释了 DBP 在红树林沉积物中的吸附。吸附容量（q）表现出吸附能力的化学变异性，顺序为 DBP > DEP > DMP。颗粒有机物质（POM）的表面极性指数（（C-O + COOH + C˭O）%）调节了 DMP 和 DEP 在红树林沉积物中的吸附容量，而红树林沉积物中不同的 POM 含量解释了 DBP 吸附强度的差异。柠檬酸的存在使三种 PAEs 的 q 增加了 6.4-12.6%。这些发现对于揭示根分泌物在 PAEs 吸附中的关键作用具有重要意义，并为红树林生态系统中 PAEs 的有效性提供了有价值的信息。
