Thallium (Tl) is an extremely harmful metal that is substantially distributed in the environment. It can threaten human health via consumption of food potentially derived from Tl-contaminated agricultural production. Little information is available on how to utilize biochar to remediate Tl contamination in agricultural soils. More efforts are urgently needed to be devoted to developing effective techniques to empower biochar with high selectivity of Tl in agricultural soils. In this review, we provided comprehensive information on Tl contamination in agricultural soils. We also discussed recent developments and assessed the current status of biochar applications. We briefly reviewed the bridge between biochar preparation technology and utilization wherein further developments can exhibit potential in terms of Tl remediation. Hence, biochar is expected to exhibit excellent Tl remediation performance in contaminated agricultural soils with promising application prospects. The obtained knowledge provides further insights into the remediation of Tl contamination in agricultural soils.

Vegetable gardens are increasingly common in urban areas and can provide numerous societal benefits; however, contamination with potential toxic elements (PTEs) due to urbanization and industrialization is cause for concern. The present study aimed to assess the source of contamination and pollution levels in urban garden soils, as well as the health risks for adults and children consuming vegetables grown in such environments. Various types of vegetable samples and their corresponding soils from 26 community gardens were collected throughout Chengdu City in southwestern China. The results showed that leafy vegetables, particularly lettuce leaves and Chinese cabbage, had relatively higher levels of Cd (0.04 mg/kg FW) and Pb (0.05 mg/kg FW), while higher levels of As (0.07 mg/kg FW), Cr (0.07 mg/kg FW), and Hg (0.003 mg/kg FW) were found in amaranths, tomatoes, and Houttuynia cordatas, respectively. The pollution indices revealed that the vegetable purplish soils were relatively more polluted by Cd and As, and the concentrations of these metals in vegetables were correlated with their concentrations in the soils. Principal component analysis grouped the PTEs in two dimensions that cumulatively explained 62.3% of their variation, and hierarchical clustering identified two distinct clusters indicating that Cr originated from a unique source. The health risk assessment revealed that exposure to As and Cd induced the greatest non-carcinogenic risk, whereas Cr was most likely to cause cancer risks. Furthermore, contaminated vegetable consumption was riskier for children than adults. The critical factors contributing to PTE contamination in vegetable gardens were determined to be vegetable species, total soil element content, soil pH, and soil organic matter content. Overall, Cr and As pollution present the greatest concern, and community health care services must enact more effective regulatory and preventative measures for urban gardens in terms of PTEs.