Effects Of Plant Lipids Extraction Approaches On Phenanthrene Sorption By Plant

Plant lipids is an important parameter in some plant uptake models,since its predominant role in plant uptake and accumulation of hydrophobicorganic compounds. Definitions of lipids based on different extractionapproaches and solvents present great differences, while the lipidsextraction approach determines the performance of those models.Systematically investigating effects of lipids extraction approach on plantuptake of phenanthrene provides insights into a better understanding on therole of lipids in plant uptake of hydrophobic organic compounds, and canprovide accurate parameter for those plant uptake models as well.This thesis selected phenanthrene and pyrene as test PAHs, lettuce astest plant. Conventional plant lipids extraction via Soxhlet extraction withvarious polarities solvents, including n-hexane, carbon tetrachloride,benzene, methylene chloride, chloroform, tetrahdrofuran and acetone wasinvestigated. And its effects on plant uptake of phenanthrene and pyrenewere studied via equilibrium sorption. Then methanol, hexane and chloroform were served as extraction solvents, plant lipids extraction viathe combined technique of Soxhlet extraction and cellulase-hydrolysistreatment was addressed, its effects on plant uptake of phenanthrene werealso discussed.We concluded that:(1) within low-polarity range, the amount of lipidsextracted by Soxhlet extraction was significantly positive correlated withthe solvent polarity, and as the solvent polarity increasing, the extractedlipids went to the maximum，meanwhile the extracted polar substances alsoincreased;(2) the impacts on plant uptake of phenanthrene and pyreneexerted by Soxhlet extraction with various polarities solvents were theconsequences of both extents that solvents extract the non-polar lipids andthe polar substances;(3) since plant lipids can not be extracted completelyby Soxhlet extraction, while after cellulase-hydrolysis treatment, theun-extractable lipids became Soxhlet extractable, and the un-extractablelipids can not dissolve in n-hexane while can be dissolved by methanol;(4)the influences of the combined technique on sorption of phenanthrene bylettuce-originated sorbents, that obtained vis this technique, were consistentwith those on lettuce’s composition; and this was fundamentally caused byits influences on lipids contents in those sorbents;(5) the combinedtechnique can extract part of un-extractable lipids in lettuce, while theresidues of lettuce’s dry sample (about30%) can neither be extracted bysolvent nor be hydrolyzed by cellulase, and theirs strong affinity on phenanthrene indicated that the lipids contents in residues still remainedhigh after treatments by combined technique. We suggest that in the future,more effects should be focused on establishing a better lipids extraction anddetermination approach.