The prevalence of per- and polyfluoroalkyl substances (PFASs) in agricultural soils has raised concerns regarding the health risks associated with the consumption of PFAS-contaminated agricultural products. The present study investigated the uptake and translocation of nine PFASs in lettuce using a hydroponic setting. During the uptake experiments, long-chain PFASs (≥ C8) exhibited greater accumulations in lettuce roots, while short-chain PFASs (≤ C7) manifested preferential transport to the shoots. The average root concentration factors of PFASs were positively correlated with their log K ow values. A significantly negative relationship was found between the average translocation factors of PFASs and their molecular volume. Sorption of long-chain PFASs by lettuce roots was enhanced after heating the roots to increase the cell membrane permeability. The accumulation of perfluorododecanoic acid increased significantly in shoots of lettuce plants without roots as compared to whole lettuce plants. Results of the present study indicate that sorption to root surface tissues and efficiency in passing through the root Casparian strip are two important factors that affect the uptake and distribution of PFASs within plants.
Min Lin,Zheng B. Hou,Shun Yao,Zhi X. Wang,Hang Song
A new series of chiral dicationic ionic liquids (DILs) were successfully synthesized and characterized by IR and NMR . The density of the whole family of ILs was measured and related physical properties including thermal expansion coefficient , molecular volume, standard molar entropy, and crystal energy were estimated by theoretical methods. Moreover, the viscosity, conductivity of DILs and the binary mixtures of ionic liquid + water were determined. The data were correlated with Arrhenius equation and VogeL-Fulcher-Tamman (VFT) equation and the results were discussed subsequently. Furthermore, the molar conductivity , dissociation equilibrium constant and critical micelle concentration of DIL solution were deduced by experimental or theoretical methods. At last, the influences of the carbon chain of ILs and temperature on density, viscosity and conductivity were discussed.
危险品化学品经营许可证（带存储）