Effect of amendments on soil Cd sorption and trophic transfer of Cd and mineral nutrition along the food chain
2020
Wang, Yimin M. | Tang, Dou D. | Yuan, Xu Y. | Uchimiya, Sophie M. | Li, Ji Z. | Li, Zhen Y. | Luo, Zi C. | Xu, Ze W. | Sun, Shi G.
Phytotoxicity of cadmium (Cd) and its trophic transfer along a terrestrial food chain have been extensively investigated. However, few studies focused on the role of amendments on the trophic transfer of Cd and associated nutrient elements. In a 60-day pot experiment, soil Cd availability, accumulation of Cd, Ca and Si in lettuce, and subsequent trophic transfer along lettuce-snail system were investigated with or without 3% (w/w) soil amendment (biochar or µHAP). Soil CaCl2 extractable Cd (CdCaCl2) contents decreased by both amendments. The µHAP increased the Freundlich adsorption capacity of Cd2+ to a greater extent (15.9 mmol/kg) than biochar (12.6 mmol/kg). Cd, Ca and Si accumulation in lettuce tissues (roots and shoots) varied with amendment species and soil Cd levels. Linear regression analysis showed that root Cd contents are negatively correlated with root Ca and Si contents (R2 = 0.962, p < 0.05). After 15 days snail feeding, nearly 90% content of Cd was found in snail viscera, while nearly 95% content of Ca was found in snail shells. Contents of Si distributed equally in snail tissues. Biomaganification of Cd, Ca and Si (TF > 1) was found in lettuce shoot - snail viscera system. Opposite tendency of TF values between Cd and nutrient elements (Ca and Si) from shoots to snail tissues indicated that µHAP, rather than biochar, amendment is applicable to remediate soil Cd contamination in our study.
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