Immobilization of Cd in soil by biochar and new emerging chemically produced carbon

Abstract

Utilization of industrial and household wastes as fertilizer while wastewater as irrigation are common practices in developing country's agriculture. These practices played an imperative role in the accumulation of heavy metals in soil. Among different heavy metals, cadmium (Cd) contamination in soils has been rising to an alarming level. The contribution of natural activities is relatively low over anthropogenic activities for Cd buildup in the soil. Its toxicity adversely affects human health, soil and plant productivity. Instead of chemicals remediation, a nature-friendly biochar is suggested as a promising remedy to reclaim Cd-contaminated soils. Owing to high stability, greater surface area, and exchange sites, biochar can adsorb heavy metals. Thus, significantly reducing metals mobility, bioavailability, and uptake of heavy metals by the plant. It has active functional groups like ketones, carboxylic, and diols that bind the Cd and other metals. Biochar can also mitigate the harmful effect of Cd by improving plant chlorophyll contents, photosynthesis activity, SOP, POD and CAT enzyme activity through better availability of essential. Furthermore, the application of acidified biochar into alkaline soil is also gaining attention. It plays a vital role in declining soil pH, sodium adsorption ratio (SAR), and improving the availability of immobilized nutrients. Scientists are also working on acidified carbon (AC) chemical production to investigate its potential benefits in high pH soils. This review will help to provide the basis for understanding the potential benefits of thermopyrolyzed biochar and chemically produced AC, especially in Cd-contaminated sites. However, more advanced and in-depth investigations are required to use chemically produced carbon as an amendment against Cd and other heavy metals toxicity.

Keywords

• Acidified carbon
• Biochar
• Cadmium
• Heavy metals uptake
• Immobilization
• Rice