Biochar can help reduce cadmium contamination in soils, especially in urban areas and acidic or medium-textured soils. It can decrease cadmium bioavailability by up to 70% in urban soils and by around 40% in acidic or medium-textured soils. However, in fine-textured soils, biochar may actually increase cadmium bioavailability. The effectiveness of biochar depends on factors like the type of biochar and soil, as well as the production conditions of the biochar. Overall, biochar's impact on cadmium contamination is mainly influenced by changes in soil pH and organic carbon content, as well as the properties of the biochar itself.