Bioaugmentation-assisted phytoremediation of lead and salinity co-contaminated soil by Suaeda salsa and Trichoderma asperellum.

The combined application of plant Suaeda salsa and indigenous fungus Trichoderma asperellum on the treatment of a lead (Pb) and salinity (Na and Ca) co-contaminated soil was investigated by a flowerpot experiment. As demonstrated by plant growth and selected antioxidant parameters, S. salsa was able to tolerate and grow in the co-contaminated soil, especially bioaugmented with T. asperellum, which promoted plant growth (9-23% and 5-13% increases for plant height and fresh weight, respectively) and appeared to alleviate plant oxidative damage (7-85% and 7-49% decreases for plant malondialdehyde and peroxidase levels, respectively). The SDS-PAGE fingerprints indicated that the total protein contents of S. salsa were affected under Pb and salinity stresses. The interactions of Na and Ca ions on the phytotoxicity of Pb remained hormesis phenomenon that low-dose alleviation and high-dose enhancement. The analysis of phytoextraction parameters and bioavailability demonstrated that Pb was mainly concentrated in plant roots and poorly translocated, indicating the phytostabilization served as a major repair pathway. On the contrary, the Na and Ca ions were concentrated in plant by the following order: shoot > root. Moreover, bioaugmentation of planted soil with T. asperellum generally led to the 9-42%, 13-58%, and 19-30% decreases of plant Pb, Na, and Ca concentrations and translocations, respectively, as well as a 6-21% decrease of soil Pb bioavailability. This study provided a bioaugmentation-assisted phytoremediation technique to make up the deficiencies of the long-term remediation for heavy metals and salinity.