Research Article
Du RY, Wen D, Zhao PH, Chen Y
Abstract
Conventional approaches for phytoremediation of heavy metal-contaminated soils face challenges in farmland werlands. The combined use of functional microorganisms is a promising option to enhance phytoremediation. Two heavy metal-resistant model strains, designated DBM1 (rhizosphere Arthrobacter) and DBM2 (non-rhizosphere Bacillus), were isolated from polluted farmland soils downstream of a multi-metal mine. The effects of these two bacterial strains on soil metal availability and plant (rice and red ramie) growth were determined under greenhouse conditions. Both microbes (especially DBM2) significantly reduced metal availability and increased pH level in lowcontaminated soil, but the passivation ability of DBM2 disappeared in high-contaminated soil. Soil metal availability was markedly increased by DBM1 after addition of carbon source, while it was reduced by DBM1 or DBM2 with pH increase after addition of nitrogen, phosphorous, or modified fly-ash amendment. Both microbes significantly increased plant biomass and reduced total metal contents of low-metal accumulating rice. For high-metal accumulating red ramie, DBM1 significantly increased plant biomass while DBM2 increased total metal contents. Proper selection of microbial species to match plants for phytoremediation is the key to improve microbe-assisted phytoremediation efficiency in mining-contaminated soils.