In a comprehensive review article published in Environmental Earth Sciences, authors Yingbo Dong, Xujiao Guan, and Hai Lin investigate the multifaceted role of biochar in addressing the global challenge of soil pollution. As industrialization and modern agricultural practices have increased the presence of heavy metals and pesticides in the environment, there is a critical need for sustainable solutions that can both clean the land and manage the carbon cycle. The researchers find that biochar, a carbon-rich material produced from the high-heat processing of organic waste like wood or manure, offers a dual benefit: it remediates contaminated soils while simultaneously acting as a powerful tool for carbon sequestration.

The study details that biochar treats heavy metal pollution through a complex variety of chemical and physical pathways. For toxic elements such as lead, cadmium, and mercury, biochar utilizes its extensive surface area and special chemical groups to trap these metals, making them less likely to move through the soil or be absorbed by crops. The findings show that adding specific types of biochar can reduce the bioavailability of copper by fifty-one percent and lower lead availability by as much as ninety-nine percent in certain conditions. These results are highly dependent on the soil’s acidity, with biochar often increasing the pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More of acidic soils by up to one full unit, which further encourages metals to settle into stable, harmless forms.

For organic pollutants like pesticides and industrial chemicals, biochar acts as both a filter and a biological catalyst. Its porous structure physically traps molecules through a process called pore filling, while its unique carbon framework creates electrical interactions that hold onto contaminants. Beyond just holding onto these chemicals, biochar creates a favorable habitat and provides nutrients for degrading bacteria, such as Rhodococcus, which actively break down organic matter. In experimental settings, corn-derived biochar was able to remove nearly ninety-eight percent of tetracycline antibiotics from the soil, illustrating its high effectiveness against emerging contaminants.

In addition to cleaning the dirt, biochar provides measurable improvements to the atmosphere by trapping greenhouse gases. The researchers highlight that biochar application directly introduces stable carbon into the soil that resists breaking down for a long time. More importantly, the presence of biochar in the soil can reduce nitrous oxide emissions—a gas far more potent than carbon dioxide—by eighty-two percent. This happens because biochar encourages the growth of specific microbes that carry the nosZ gene, which helps finish the process of turning nitrogen gases into harmless nitrogen in the air. Furthermore, biochar improves the way plants take in carbon from the sun, increasing the photosynthetic rate by twenty-two to sixty-two percent, which further pulls carbon dioxide out of the sky and stores it in plant tissue and the surrounding soil.

The review emphasizes that the success of these applications is governed by “precision environmental management,” meaning the starting material and the temperature it is processed at must be carefully selected for the intended goal. For instance, woody materials processed at very high temperatures are best for long-term carbon storage because they create the most stable carbon structures. Conversely, biochar made from manure is often better at treating heavy metals because of its high mineral content. While challenges remain regarding how biochar ages over many years, the study concludes that this technology provides a vital path toward achieving the synergistic goals of a healthy environment and a neutral carbon footprint.

Source: Dong, Y., Guan, X., & Lin, H. (2026). Biochar for simultaneous soil remediation and carbon sequestration: application, mechanism, and development prospect – a comprehensive review. Environmental Earth Sciences, 85(98).