Role Of Transgenic Poplar And Strengthening Measures In Atrazine-Polluted Soil Remediation

The soil in many regions of China is contaminated by the unreasonably using of pesticides. Atrazine is one of the herbicides that is widely used in China. Its environmental effects and threats are becoming more of a concern. Phytoremediation, the use of plants and their associated microbes for environmental cleanup, has gained acceptance in the past 10 years. It has the advantages of cost-effective, noninvasive alternative and no secondary pollution. So it has a bright future for application to the cleaning-up of contaminated soil. Transgenic poplar (Populus deltoides×nigra, DN34) was taken as plant materials to remediate atrazine-contaminated soil, with sawdust, peat, inorganic fertilizer and mycorrhiza as additives, in the Research Greenhouse of Chinese Academy of Forestry in this study.The research into the phytoremediation effectiveness and strengthening measures in cleaning-up of atrazine-polluted soil by using transgenic poplar, by means of GC/MS, BIOLOG and Li-6400 instruments and methods was conducted. The degradation dynamic of atrazine, effects of additives, physiological changes of poplars, microbial community structure and microbial activity, and the soil enzyme activity were ??ied in this experimental research, for the sake of identifying the role of this poplar in phytoremediation, and offering references for the further practical application.The main findings are summarized as follows:1. The effect of phytoremediation for atrazine-contaminated soil is noticeable. The change in total amount of atrazine's residue with time met a kinetic equation C=5.979e-0.02t. The phytoremediation efficiencies vary according to the kinds of additive. The effects of 1% peat and mycorrhiza were the most significant judging from degradation effect, tree height, ground diameter, biomass and etc.2. Plant photosynthetic responses: It was found that there was a significant change in the net photosynthesis of leaves (Pn) but no significant change in intercellular CO2 concentration (Ci) both on the condition of atrazine stress and the application of mycorrhiza. Generally, atrazine stress has an stimulating effect on the stomatal conductance (Gs) of poplar leaves, but the high light intensity makes Gs drop, and CO2 acquisition to be affected. Atrazine stress leads to the increase of transpiration rates and the faster cycle, and hence requires more water supplies to secure normal growth.3. The microbial biomass carbon and microbial diversity was found to be promoted in atrazine-polluted soil, with more obvious performance for the phytoremediation treatment group. During the whole experiment period, the changes in Evenness index and Shannon index were not significant, while McIntosh index significant under different treatments. Phytoremediation was also beneficial to the recovery of the enzyme activities, which is more significant during the late experiment period. The soil enzymes was significantly correlated with microbial biomass carbon under both control and phytoremediation treatment condition.