Effect of montmorillonite biochar composite amendment on thallium bioavailability in contaminated agricultural soils and its mitigated health risk

Recent advances in clay minerals for groundwater pollution control and remediation

Clay minerals are abundant on Earth and have been crucial to the advancement of human civilization. The ability of clay minerals to absorb chemicals is frequently utilized to remove hazardous compounds from aquatic environments. Moreover, clay-based adsorbent products are both environmentally acceptable and affordable. This study provides an overview of advances in clay minerals in the field of groundwater remediation and related predictions. The existing literature was examined using data and information aggregation approaches. Keyword clustering analysis of the relevant literature revealed that clay minerals are associated with groundwater utilization and soil pollution remediation. Principal component analysis was used to assess the relationships among clay mineral modification methods, pollutant properties, and the Langmuir adsorption capacity (Qmax). The results demonstrated that pollutant properties affect the Qmax of pollutants adsorbed by clay minerals. Systematic cluster analysis was utilized to classify the collected data and investigate the relationships. The pollution adsorption mechanism of the unique structure of clay minerals was investigated based on the characterization results. Modified clay minerals exhibited changes in surface functional groups, internal structure, and pHpzc. This review provides a summary of recent clay-based materials and their applications in groundwater remediation, as well as discussions of their challenges and future prospects.

Thallium content in vegetables and derivation of threshold for safe food production in soil: A meta-analysis

Soil thallium (Tl) pollution is a serious environmental problem, and vegetables are the primary pathway for human exposure to Tl. Therefore, it is important to investigate the characteristics of soil Tl uptake by vegetables. In this study, the meta-analysis approach was first applied to explore the relationship between Tl content in vegetables and soil environment, as well as key factors influencing soil physical-chemical properties, and to derive soil thresholds for Tl. The results indicated that various types of vegetables have different capabilities for Tl accumulation. Vegetables from contaminated areas showed high Tl accumulation, and the geomean Tl content in different types of vegetables was in the following order: leafy > root-stalk > solanaceous vegetables. Taro and kale had significantly higher capability to accumulate soil Tl among the 35 species studied, with Tl bioconcentration factor values of 0.060 and 0.133, respectively. Pearson correlation analysis and meta-analysis revealed that the Tl content in vegetables was significantly correlated with soil pH and Tl content in soil. The linear predictive model for Tl accumulation in vegetables based on soil Tl content described the data well, and the fitting coefficient R2 increased with soil pH value. According to potential dietary toxicity, the derived soil Tl thresholds for all, leafy and root-stalk vegetables increased with an increase in soil pH, and were in the range of 1.46-6.72, 1.74-5.26 and 0.92-6.06 mg/kg, respectively. The soil Tl thresholds for kale, lettuce and carrot were in the range of 0.24-4.89, 2.94-3.32 and 3.77-14.43 mg/kg, respectively. Ingestion of kale, beet, sweet potato, potato, taro, pepper, turnip, Chinese cabbage, eggplant and carrot poses potential health risks. The study provides scientific guidance for vegetable production in Tl-contaminated areas and can help with the selection of vegetable species suitable for avoiding the absorption of Tl from contaminated soil.