Mycorrhizal Remediation And Enhancements Of Cd And BDE-209 Co-Contaminated Soil By Solanum Nigrum

The inappropriate ways of producing, using and recycling of electronic products have caused serious heavy metals and polybrominated diphenyl ethers combined pollution, which threaten both the ecological environment and the health of residents lived nearby. Solanum nigrum, a hyperaccumulator of cadmium, was selected as repairing plant. The effects of two species of arbuscular mycorrhizal fungi(Glomus mosseae, Glomus intraradices), three kinds of chemical additives(citric acid, malic acid and β-cyclodextrin) and their combinations on the phytoremediation of cadmium(Cd)-decabrominated diphenyl ether(BDE-209)co-contanminated soil were investigated, for the first time. The main results were as follows:( 1) Both Glomus mosseae and β-cyclodextrin treatments increased the biomass of Solanum nigrum, while citric acid and malic acid decreased. Growing plants could significantly improve polyphenol oxidase, urease and dehydrogenase activities in soil. Citric acid, malic acid and β-cyclodextrin treatments also have certain positive effects on these enzyme activities. The combination of β-cyclodextrin and AMF(Arbuscular mycorrhiza fungi)could enhance the soil enzyme activities further, and the enhancement with Glomus mosseae(GM) was greater than that with Glomus intraradices(GI).( 2) Both GM and β-cyclodextrin treatments could strengthen the phytoremediation of cadmium, while citric acid and malic acid weakened and the combination of AMF further weakened. AMF could stabilize heavy metals: Solanum nigrum inoculated with AMF had more residual Cd in soil and plant, so as to reduce the toxicity of Cd for better growth.(3)Growing plants improved the removal of BDE-209 in soil, however, plant uptake accounted for a very small proportion of the dissipation of BDE-209 in soil. It indicated that plant uptake was not the main pathway of BDE-209 removal. Adding citric acid, malic acid andβ-cyclodextrin all could improve the removal of BDE-209 in soil, the combination of chemical additives and AMF improved the removal rate much further. When planting Solanum nigrum, the BDE-209 removal rate of treatment adding citric acid and inoculated with GM was up to 54.4%;treatment adding malic acid and inoculated with GI was up to 59.6%; treatment addingβ-cyclodextrin and inoculated with GM was up to 55.5%. More lower brominated PBDE congeners were detected in the plant tissues than those in soil. The main components werehexa-BDE, di-BDE and tetra-BDE in the shoots of Solanum nigrum, while deca-BDE in roots and soil. But the proportion of deca-BDE in roots was far less than that in soil. Addition of citric acid, malic acid and β-cyclodextrin could accelerate the degradation of BDE-209 in soil to a large extent, and the main congeners were nona-BDE. The combination of AMF and chemical additives could accelerate the degradation of BDE-209 in soil further more.(4)In conclusion, Solanum nigrum adding β-cyclodextrin and inoculated with AMF could increase the removal of BDE-209 in soil to a large extent, meanwhile accumulate Cd.Furthermore, the removal of BDE-209 in soil inoculated with GM was higher than that with GI.