岩溶区土壤镉生物有效性影响因素研究

为研究岩溶区土壤镉生物有效性的影响机制,以广西碳酸盐岩区土壤垂直剖面、水稻子实与根系土协同样品为基础,讨论了土壤pH、有机质含量、黏土矿物含量、碳酸盐含量对土壤镉生物有效性的影响。结果表明,pH、有机质、黏土矿物主要对镉的吸附产生影响,其对镉生物有效性的影响程度由强到弱依次为pH、黏土矿物、有机质,碳酸盐的作用则主要体现为对土壤酸化的缓冲。总体而言,广西岩溶发育强烈,土壤中不断形成表生条件下稳定的新生黏土矿物,加之岩溶区土壤丰富的碳酸盐与有机质,都对该地区碳酸盐岩母质土壤中镉的固定较为有利,但防止土壤酸化是防控其土壤镉污染风险的首要措施。

Study on factors affecting soil cadmium bioavailability in soil in karst area

Karst areas are the main soil cadmium content distribution areas in China. Explaining the mechanism of soil cadmium bioavailability in these areas is of great significance to understand the risks associated with soil cadmium of China. In this study, vertical soil profiles, rice seed, and its corresponding root-soil samples were collected in Guangxi and the effects of soil pH, organic matter, clay mineral, and carbonate on the bioavailability of cadmium in carbonate parent soil were discussed. Among them, it was determined that pH, organic matter, and clay minerals mainly affect the adsorption of cadmium. The bioavailability of cadmium is affected by pH, clay minerals, and organic matter in descending degree of strength order. The role of carbonate is mainly reflected as a buffer against soil acidification. In general, Guangxi has strong karst development and the soil is constantly forming new clay minerals that are stable under epigenetic conditions. In addition, the rich carbonate and organic matter in the soil of the karst areas are more favorable for the fixation of cadmium in the parent soil of carbonate rock; however, preventing soil acidification is the first measure to prevent and control the risk of soil cadmium pollution.