Effects of organic matter and microbial community structure on BA (barite) availability and phytoremediation in flooded soils

Barium (Ba) is a toxic, non-essential and overlooked contaminant. In wetland environments, barite (BaSO4) spillage can occur (e.g., by drilling fluids) and sulfate can undergo dissolutive reduction through carbon microbial respiration, releasing Ba. Thus, we investigated Ba contamination and soil amending with different carbon sources (biochar- BC, rice straw-RS, and sewage sludge-SS) effects over soil microbial community and Ba availability. Natural soil (NS), artificially-contaminated soil (CT), and barite-contaminated soils amended with BC, RS, and SS were incubated under reducing conditions for 120 days. We determined, over time, the microbial community structure, diversity, composition, and network, as well the changes on soil pH, redox potential (Eh), and Ba exchangeable contents (BaEX). Ba affected soil microbial communities and decreased the soil microbial capacity to form highly connected communities.