The Plant Lipid Determination In An Uptake-Based Model For Predicting Phytoremediation Of Organic Contamination

Phytoremediation is a potential'green', cost-effective, and secure technology that uses plants for the in-situ cleanup of contaminated sites. It is a promising remediation technique for soils contaminated with organic compounds.The partition-limited model for plant passive uptake of organic chemicals from soil or water associated the extent of uptake with plant compositions and physical-chemical properties of the organic chemicals. While the lipids data of the plant, which were the key factor that may influence the accuracy of model predictions, were limited, unavailable and conflicting, so the correct measurement of the plant lipids was of great importance.The plant lipid content in leaf lettuce and spinach was extracted by organic solvent using Soxhlet, vibrating and ultrasonic extraction. The uptake of diuron and phenanthrene by these plants was investigated, and the results were used to evaluate a partition-limited model for plant uptake of organic chemicals.The lipid content in leaf lettuce extracted by Soxhlet, vibrating and ultrasonic methods were 3.78-32.27%, 1.14-23.56% and 1.17-23.79% (w/w) respectively and 2.39-23.79% in spinach (Soxhlet extraction). The experimental results showed that the lipid content extracted was positively correlated with the polarity parameter of solvent, and not influenced by the other physiochemical properties such as dipole moment, density, boiling point, etc. The plant-water partition coefficient of phenanthrene (2972.60L/kg for the leaf lettuce and 2422.20L/kg for the spinach) was much larger than that of diuron (84.53L/kg for the leaf lettuce) resulted from the K_ow of phenanthrene was much greater than that of diuron. So the carbohydrate compound in the plant should be considered in the plant uptake of less lipophilic diuron.By comparing the predicted and observed concentrations in the two plant species, the optimum method was selected as soxhlet extraction, and the appropriate extracting solvent was determined to be acetone, mixed solvent acctontrile:acetone(1:2)for leaf lettuce; acetontrile, mixed solvent acctontrile:acetone(3:2) for spinach, respectively. Results of this study would provide useful information for partition-limited model prediction based on the soil contamination levels, chemical properties and plant compositions.