Remediation Performance and Mechanism of Heavy Metals by a Bottom Up Activation and Extraction System Using Multiple Biochemical Materials

Abstract

Soil contamination with heavy metals has caused serious environmental problems and increased the risks to humans and biota. Herein, we developed an effective bottom up metals removal system based on the synergy between the activation of immobilization metal-resistant bacteria and the extraction of bioaccumulator material (Stropharia rugosoannulata). In this system, the advantages of biochar produced at 400 °C and sodium alginate were integrated to immobilize bacteria. Optimized by response surface methodology, the biochar and bacterial suspension were mixed at a ratio of 1:20 (w:v) for 12 h when 2.5% sodium alginate was added to the mixture. Results demonstrated that the system significantly increased the proportion of acid soluble Cd and Cu and improved the soil microecology (microbial counts, soil respiration, and enzyme activities). The maximum extractions of Cd and Cu were 8.79 and 77.92 mg kg, respectively. Moreover, details of the possible mechanistic insight into the metal removal are discussed, which indicate positive correlation with the acetic acid extractable metals and soil microecology. Meanwhile, the "dilution effect" in S. rugosoannulata probably plays an important role in the metal removal process. Furthermore, the metal-resistant bacteria in this system were successfully colonized, and the soil bacteria community were evaluated to understand the microbial diversity in metal-contaminated soil after remediation.

Effects of amendments on heavy metal immobilization and uptake by Rhizoma chuanxiong on copper and cadmium contaminated soil

“…The amendment provided nutrition for plants and adjusted soil pH, which could be propitious to R. chuanxiong growth. Meanwhile, plant biomass increase, in turn, can dilute the account of heavy metals with a ‘dilution effect’ [ 46 ]. The results in this experiment indicated that application of amendments could promote R. chuanxiong growth.…”

Cadmium Exposure Alters Rhizospheric Microbial Community and Transcriptional Expression of Vetiver Grass

“…Rarefaction and Shannon curves tended to be plain (Supplementary Figures 1B,C), which indicated that the samples were suitable for further analysis (Wu et al, 2018). Alphadiversity indexes were widely used to evaluate microbial diversity (Xiao et al, 2017). It was observed that the alpha-diversity indexes, including Sobs, Shannon, Ace, and Chao, did not show a significant difference (p < 0.05) between -Cd and + Cd samples (Supplementary Table 4), indicating that Cd toxicity did not significantly affect the rhizospheric microbial diversity.…”

“…Among the most relevant alteration in the bacterial community, in response to Cd stress, was a decrease in the abundance of Actinobacteria (Ai et al, 2018;Sarria Carabalí et al, 2020). Previous studies also found that Actinobacteria was the most dominant phylum in environments such as plant rhizosphere, sewage sludges, hot springs, and freshwater habitats (Alvarez et al, 2017;Xiao et al, 2017). The reduction in the abundance of Actinobacteria might be related to the elimination of Cd-sensitive bacteria belonging to the phylum Actinobacteria due to high Cd toxicity (Sarria Carabalí et al, 2020).…”

Soil amendments for sustainable agriculture: Microbial organic fertilizers

“…Similarly, substantial enhancement in growth of bean plants was found with a consortium of AMF and beneficial fungi (Trichoderma harzianum T8) acting as a biocontrol agent (Eke et al, 2019). ( Xiao et al, 2017) Abbreviations: E, Exogenous; I, Indigenous.…”