soil Genome sequencing and assembly
The super-stable mineralized materials, CaAl- / MgAl- layered double hydroxides (CaAl-LDH / MgAl-LDH), are widely used for the remediation of heavy metal contaminated water or soils. However, it is unclear about the remediation effects of CaAl-LDH and MgAl-LDH on the cadmium (Cd) bioavailability and microecological environment in Cd-contaminated paddy soils . A field experiment was carried out to compare the impacts of CaAl-LDH, MgAl-LDH, and conventional soil stabilizers (lime (LM), and biochar (BC)) on soil chemical properties, soil available Cd content, total Cd content in rice grains, as well as bacterial communities. The results showed that CaAl-LDH, MgAl-LDH, LM, and BC treatments enhanced soil pH, cation exchange capacity (CEC), available phosphorus (AP), and exchangeable calcium (ExCa), while reducing soil Cd availability (15.75 - 53.33%) during the different growth stages and Cd concentration (51.70 - 80.95%) in rice grains, with the lowest Cd accumulation under the MgAl-LDH and CaAl-LDH treatments. Compared with CK, the richness (Chao 1) and diversity (Shannon) of bacterial communities increased after the applications of soil amendments, with the changes in their community structure by enhancing the relative abundances of Bacteroidota, Myxococcota, and Bacillota and reducing that of Verrucomicrobiota. Soil pH, CEC, AP, and ExCa were key factors for the shifts of bacterial community structure. Soil microbiome analysis revealed that the increase in relative abundances of Firmicutes and Bacteroidota associated with Cd fixation, thus lowering Cd phytoavailability. Meanwhile, the partial least square-structural equation modelling (PLS-SEM) elucidated that soil amendments mainly influenced soil pH, CEC, and nutrients (AP and EX.Ca ) availability, thus decreasing soil Cd availability. Soil amendments influenced soil pH and CEC that reducing rice Cd concentration. Overall, these results demonstrated that CaAl-LDH and MgAl-LDH are more effective than lime and biochar for the remediation Cd-contaminated paddy soil, and emphasizing the core role of these soil amendments by modifying soil properties, affecting soil Cd availability, and shaping bacterial community, ultimately reducing Cd accumulation in rice grains.