Response of soil microbial communities to red mud-based stabilizer remediation of cadmium-contaminated farmland

Abstract

In this work, a field test was conducted to investigate the effects of heavy metal stabilizer addition on brown rice and microbial variables in a cadmium (Cd)-contaminated farmland from April to October in 2016. Compared with the control, red mud-based stabilizer (RMDL) effectively reduced the concentration of Cd in brown rice (with the removal rate of 48.14% in early rice, 20.24 and 47.62% in late rice). The results showed that adding 0.3 kg m RDML in early rice soil or soil for both early and late rice increased the microbial biomass carbon (MBC), the number of culturable heterotrophic bacteria and fungi, and the catalase activity in soil at different stages of paddy rice growth. Furthermore, there was no notable difference in the diversity of the bacterial species, community composition, and relative abundance at phylum (or class) or operational taxonomic unit (OTU) levels between the control and treatment (RMDL addition) groups. In a word, RMDL could be highly recommended as an effective remediation stabilizer for Cd-contaminated farmland, since its continuous application in paddy soil cultivating two seasons rice soil could effectively decrease the Cd content in brown rice and had no negative impact on soil microorganisms.

Effects of Amendments and Indigenous Microorganisms on the Growth and Cd and Pb Uptake of Coriander (Coriandrum sativum L.) in Heavy Metal-Contaminated Soils

“…The combined application of IMOs and n-HAP exhibited synergistically decreased DTPA-extractable Cd and Pb concentrations in slightly contaminated soil; however, no synergistic effect was observed in moderately contaminated soil. Some studies have revealed that stabilising amendments in the heavy-metal-polluted soil aided the recovery of soil bacterial diversity and soil microbial metabolic activities related to Cd and Pb transformation and enriched genera related to nutrient activation, particularly at low metal concentrations [ 68 , 69 , 70 , 71 ]. Our results suggest that n-HAP, along with several taxa, may improve the immobilisation efficiencies of DTPA-extractable Cd and Pb in slightly contaminated soil, whereas IMOs from moderately contaminated soil developed many strains tolerant to HMs, thereby activating the available Cd in moderately contaminated soil.…”

A Comparison of Different Remediation Technologies of Contaminated Agricultural Soils

“…Organic stabilizers such as animal manure, crop residues, sewage sludge, and industrial organic waste also can inert and remediate heavy metals. Red mud-based stabilizers and montmorillonite-biochar composite materials have been used to remediate pollutants effectively [15] .…”

Overview of Known Alkaliphilic Bacteria from Bauxite Residue

“…Due to environmental issues and the high cost associated with managing and disposing of it, there is a growing concern about the proper disposal of this waste. Alternative uses of BR have been studied in the ceramics industry [4], stabilizer soil [5] and metal recovery, among others [2]. However, there are some limitations, such as excess in moisture, hazardous rating of bauxite residue, viable logistics in the transport of waste and the low aggregate value in BR.…”