Study On The Fate Of Phthalate Acid Esters In Potamogeton Crispus L. Microcosm Simulating Haihe River

In this thesis, Potamogeton crispus L., which is a kind of typical submerged plant in Haihe River, was selected. Dibutyl phthalate (DBP) and Di-ethylhexyl phthalate (DEHP), two kinds of phthalates esters (PAEs) which were listed as priority persistent organic pollutants by the US EPA and China, were selected as typical organic contaminants. The environmental behavior and fate of DBP and DEHP in Potamogeton crispus L. Microcosm of Haihe River was studied by two approaches: stimulating laboratory microcosm experiments and multimedia fugacity model.Results of the laboratory microcosm experiments showed that concentrations of DBP and DEHP in water and sediments from the Potamogeton crispus L. microcosm were lower than those from the control microcosm during the experiment. At the end of the experiments, DBP and DEHP mainly distributed in sediment, and followed by in water. The two PAEs, especially DEHP which is a stronger hydrophobic compound, could be enriched in Potamogeton crispus L. The average enrichment coefficients (BCF) of Potamogeton crispus L. were 22.4 L/kg for DBP and 180.7 L/kg for DEHP. Removal efficiencies of loaded DBP and DEHP in the Potamogeton crispus L. microcosm (94.2% for DBP, 60.8% for DEHP) were 4.1 and 15.3 percentage points higher than those in the control microcosm (91.0% for DBP, 45.5% for DEHP). The retained percentages of loaded DBP and DEHP were -0.6% and 30.7% in the Potamogeton crispus L. microcosm, and 4.7% and 37.7% in the control microcosm, respectively, indicating that Potamogeton crispus L. can not only enhance the degradation of DBP and DEHP, but also decrease the amount of their residue, reducing the internal pollution sources.LevelⅣ(unsteady state) multimedia fugacity model and LevelⅢ(steady state) multimedia fugacity model were established and successfully applied to the experimental data for DBP in Haihe River. For Potamogeton crispus L. microcosm, when the system reaches steady state, DBP mass percentage in each phase were: 5.26% in water, 90.16% in sediment, and 4.58% in Potamogeton crispus L.; for control microcosm, DBP mass percentage in each phase were: 8.87% in water and 91.13% in sediment. In the system, DBP was mainly removed by microbial degradation in sediment (account for 87.24% in Potamogeton crispus L. microcosm and 76.06% in control microcosm of the total removal); for Potamogeton crispus L. microcosm, DBP removal in plant accounts for 4.54% of the total removal, rank only second to sediment, so it should not to be neglected.In addition, sensitivity analysis of model has been made. It is indicated that, for the Potamogeton crispus L. microcosm, water-sediment organic carbon distribution coefficient (Koc) and sedimentation velocity of suspended particles (Uspm) have significant influence on the calculated DBP concentration in water. Koc, degradation rate of DBP constant in sediment (ksR), organic carbon fraction of sediment (foc) and density of sediment (ρs) have significant influence on the calculated DBP concentration in sediment. Koc, Uspm, DBP uptake rate constant by plant (Ku), density of plant (ρp) and water-plant partition coefficient (Kpw) have significant influence on the calculated DBP concentration in plant. For control microcosm, sensitive parameters for water and sediment are the same as those for the Potamogeton crispus L. microcosm.