硅酸钠与腐殖肥对土壤Cd形态及油麦菜生物可给性的影响

Effects of sodium silicate and humic fertilizer on the speciation of cadmium in soil and the bioaccessibility of cadmium in Lactuca sativa L.

原位钝化技术是我国重金属污染农田土壤修复技术的研究热点,然而土壤改良后作物重金属的生物可给性及健康风险变化情况仍未可知。本研究以油麦菜为供试蔬菜,选择硅酸钠与腐殖肥2种典型土壤改良剂,通过盆栽试验研究了单一与复配改良剂对土壤理化性质改良、Cd赋存形态、油麦菜生长、Cd累积及其生物可给性的影响。结果表明:单施硅酸钠对油麦菜的生长具有一定的抑制作用,而单施腐殖肥则能显著提高其生物量,0.6%生物腐殖肥+0.3%硅酸钠复配处理对促进油麦菜生长、减少其对Cd的吸收效果最佳。不同处理下油麦菜胃阶段的生物可给性均高于小肠阶段,与不添加改良剂的对照相比,各处理均可降低儿童和成人对油麦菜Cd的摄入量,但不同消化阶段成人油麦菜Cd的生物可给量均高于儿童。单一与复配改良剂均可有效降低油麦菜的致癌风险与非致癌风险,其中0.6%生物腐殖肥+0.3%硅酸钠复配处理下油麦菜对儿童和成人的健康风险降幅分别达40.82%和30.21%。膳食摄取不同处理的油麦菜对人体带来非致癌危害的可能性较小,但可能会对儿童带来潜在致癌风险。

In situ immobilization technology is a research hotspot in the remediation of heavy metal pollution on farmland.However,the variations in heavy metal bioaccessibility and the health risks of amended soils are largely unknown.In this study,two soil amendments,sodium silicate and humic fertilizer,were selected to study the effects of single and combined amendments on the physicochemical properties and speciation of cadmium in soil,biomass,cadmium uptake,and cadmium bioaccessibility in lettuce in a pot experiment.The results showed that single application of sodium silicate inhibited the growth of lettuce,while humic fertilizer promoted growth.The combined application of 0.6%humic fertilizer and 0.3%sodium silicate had the optimum effect on promoting the growth of lettuce and reducing its accumulation of Cd.Under different treatments,the bioavailability of lettuce Cd in the stomach stage was higher than in the small intestine stage.Compared with the control,each treatment could reduce the intake of Cd in children and adults,but the bioaccessibility of Cd in adults at different digestion stages was higher than that in children.Single and combined amendments could effectively reduce the carcinogenic risk and non-carcinogenic risk of Cd in lettuce.Under the combined amendment treatment of 0.6%humic fertilizer and 0.3%sodium silicate,the health risks of lettuce Cd to children and adults were decreased by 40.82%and 30.21%,respectively.Dietary intake of lettuce with different treatments is less likely to cause non-carcinogenic harm to the human body,but it may still present potential carcinogenic risk to children.