Influence of soil moisture and bioamendments on the speciation and bioavailability of chromium in contaminated soils

Chromium (Cr) is a strategic and dangerous heavy metal with many applications in the leather tanning and chemical industries. Cr has gained importance due to the greater understanding of its persistence and toxicity in ecosystems. To protect our environment from severe contamination threats, it is essential to remove Cr. But, before developing a remediation strategy, it is necessary to understand various factors and soil parameters that influence the bioavailability and fractionation of heavy metals. The investigation was conducted in a laboratory closed incubation experiment with bioamendments in a completely randomized design with three replications for 60 days. The study examined the impact of amendments like farmyard manure, composted poultry manure, pressmud compost, and biochar on Cr speciation in contaminated soil under different moisture conditions. The findings revealed that organic amendments substantially impacted soil chemical parameters such as pH, Cr mobility, and bioavailability. The significant reduction of bioavailable fractions was observed in biochar (75 to 80%) amended soil, followed by farmyard manure and poultry manure (60 to 70%). As a result, bioamendments can effectively reduce the bioavailability of Cr in contaminated soil and play a significant role in designing a bioremediation technology for the chromium contaminated soil.