Short‐Term Aging of Pod‐Derived Biochar Reduces Soil Cadmium Mobility and Ameliorates Cadmium Toxicity to Soil Enzymes and Tomato

Abstract

Contamination of agricultural soil with cadmium (Cd) has become a global concern because of its adverse effects on ecohealth and food safety. Soil amendment with biochar has become one of the phytotechnologies to reduce soil metal phyto-availability and its potential risks along the food chain. Biochar, derived from cocoa pod, was evaluated in soil Cd fractions (exchangeable, reducible, oxidizable, and residual) by modified Commission of the European Communities Bureau of Reference sequential extraction and its efficacy to ameliorate Cd toxicity to soil enzymes and leaf bioactive compounds. A pot experiment was conducted using Cd-spiked soil at 10 mg/kg with tomato (Solanum lycopersicum L.) at a biochar application rate of 1 and 3% (w/w) for 6 wk. The addition of biochar significantly reduced (p < 0.05) the exchangeable, reducible, and residual fractions by at least approximately 23%, with a consequential decrease in Cd root uptake and transport within tomato tissues. The activity of soil enzymes (catalase, dehydrogenase, alkaline phosphatase, and urease) was affected by Cd toxicity. However, with the exception of dehydrogenase, biochar application significantly enhanced the activity of these enzymes, especially at the 3% (w/w) rate. As for the secondary metabolites we studied, Cd toxicity was observed for glutathione, terpenoids, and total phenols. However, the biochar application rate of 1% (w/w) significantly ameliorated the effects of toxicity on the secondary metabolites. In conclusion, biochar demonstrated the potential to act as a soil amendment for Cd immobilization and thereby reduce the bioavailability of Cd in soil, mitigating food security risks.

Effect of bagasse biochar on soil organic carbon fixation in manganese pollution sugarcane fields

“…On the one hand, it may be due to the combination of heavy metals and the active protein gene of the enzyme, reducing the binding site of the enzyme, thereby inhibiting the synthesis of the enzyme. On the other hand may be heavy metals make protein deformation, thereby reducing enzyme activity, inhibition of enzyme synthesis [53]. (2) The content of MBC in uncontaminated sugarcane soil was higher than that in manganese-contaminated sugarcane soil, indicating that the activity of microorganisms changed more when biochar was applied to uncontaminated sugarcane soil.…”

Effects of Waste Cement on the Extractability of Cd, Soil Enzyme Activities, Cadmium Accumulation, Activities of Antioxidant Enzymes, and Malondialdehyde (MDA) Content in Lettuce

“…Heavy metals can directly affect soil enzymes and change their activity and diversity. A large number of studies have confirmed that heavy metals are harmful to soil enzyme activities [2,[24][25][26]. Soil enzymatic activities represent the degree to which the terrestrial ecosystems are affected by heavy metals [27][28][29].…”

#EnvChem2020: Chemistry of the Whole Environment Research

“…The method was successfully able to distinguish seven common polymers collected from the sea and shoreline of the Greek island of Samos in the Aegean Sea. Ogunkunle et al (2020) report the results of a pot experiment to demonstrate the effectiveness of cocoa-pod derived biochar to reduce the mobility of Cd in contaminated soils, enhance soil enzyme activity, and reduce Cd uptake by tomato plants. Agricultural soils become contaminated with Cd from several sources, including as an impurity in fertilisers.…”