Relation of Organic Contaminant Equilibrium Sorption and Kinetic Uptake in Plants

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• 作者：Hui Li ; Guangyao Sheng ; Cary T. Chiou ; and Ouyong Xu
• 刊名：Environmental Science & Technology
• 出版年：2005
• 出版时间：July 1, 2005
• 年：2005
• 卷：39
• 期：13
• 页码：4864 - 4870
• 全文大小：157K
• 年卷期：v.39,no.13(July 1, 2005)
• ISSN：1520-5851

文摘

Plant uptake is one of the environmental processes thatinfluence contaminant fate. Understanding the magnitudeand rate of plant uptake is critical to assessing potentialcrop contamination and the development of phytoremediationtechnologies. We determined (1) the partition-dominatedequilibrium sorption of lindane (LDN) and hexachlorobenzene(HCB) by roots and shoots of wheat seedlings, (2) thekinetic uptake of LDN and HCB by roots and shoots of wheatseedlings, (3) the kinetic uptake of HCB, tetrachloroethylene(PCE), and trichloroethylene (TCE) by roots and shootsof ryegrass seedlings, and (4) the lipid, carbohydrate, andwater contents of the plants. Although the determinedsorption and the plant composition together suggest thepredominant role of plant lipids for the sorption of LDN andHCB, the predicted partition with lipids of LDN and HCBusing the octanol-water partition coefficients is notablylower than the measured sorption, due presumably tounderestimation of the plant lipid contents and to the factthat octanol is less effective as a partition medium thanplant lipids. The equilibrium sorption or the estimated partitioncan be viewed as the kinetic uptake limits. The uptakesof LDN, PCE, and TCE from water at fixed concentrationsincreased with exposure time in approach to steadystates. The uptake of HCB did not reach a plateau withinthe tested time because of its exceptionally high partitioncoefficient. In all of the cases, the observed uptakes werelower than their respective limits, due presumably tocontaminant dissipation in and limited water transpirationby the plants.