Roles of EDTA on Phytoremediation of Combined Contamination in Dredged Sewage River Sediment
EDTA在植物修复复合污染河道疏浚底泥中的调控作用

Pot experiments were conducted to study the roles of EDTA in phytoremediation of heavy metal-organic contaminated dredged sewage river sediment by Lolium multiflorum L. 3 mmol x kg(-1) EDTA was added to sediment through three manners (once, twice and three times, respectively). The results showed that: with adding EDTA to the sediment. (1) The accumulation amount of heavy metals to Lolium multiflorum L. increased, especially by added EDTA three times. Compared with the control, the accumulation of Pb, Zn, Cu, Ni, Cd in shoots increased 2.74, 1.99, 1.59, 1.55 and 7.78 times by added EDTA three times. The net increment was 32.33 mg x kg(-1), 1 393.56 mg x kg(-1), 64.42 mg x kg(-1), 36.57 mg x kg(-1) and 10.33 mg x kg(-1), respectively. Furthermore, the concentration of chlorophyll decreased by 42% with 3 times EDTA addition, while the concentration of chlorophyll has no significant change with once EDTA addition. (2) pH hasn't much change, while NH4OAc and DTPA extractable heavy metal amount from sediment increased significantly. (3) The bulk percentage of big particle sediment increased. By added EDTA three times to sediment, the average particle size of sediment increased, while specific surface area and crystal lattice intensity decreased, which were contributed to the desorption of heavy metal from sediment particle. (4) Compared with the control, the amount of microorganism in sediment was increased 1.33 times and 1.47 times with adding EDTA twice and three times. The urease activity decreased, while the catalase activity hasn't much change. (5) TOC content was increased.