羊栖菜生物炭对镉污染土壤性质及镉形态的影响

为了研究生物炭对实际镉(Cd)污染土壤理化性质和Cd化学形态的影响,首先以海洋生物质(羊栖菜)、农林废弃物(水稻秸秆、山核桃壳)为原料制备了三种生物炭,并比较了三种生物炭对水溶液中Cd的吸附效果,从而优选出对Cd吸附最佳的生物炭。通过在Cd污染的土壤中施用不同用量的优选生物炭,测定污染土壤基本理化性质和Cd化学形态的变化,初步探讨了生物炭对实际Cd污染土壤理化性质和土壤Cd污染的钝化效果。结果表明,三种生物炭中羊栖菜炭对重金属Cd的吸附效果最佳。污染土壤添加羊栖菜炭后可以明显提高污染土壤p H、有效磷、速效钾、全氮和有机质,且随添加量增加而幅度增大。不同量的羊栖菜炭的施入均有效降低了污染土壤有效态Cd含量,使得土壤重金属Cd由交换态向碳酸盐结合态、铁锰氧化物结合态、有机结合态和残渣态转化。综上所述,羊栖菜炭显著降低了土壤重金属Cd的生物有效性和生态毒性,从而显著降低重金属Cd的危害。

Effects of biochar derived from Sargassum fusiforme on the properties and cadmium forms of cadmium-contaminated soil

In order to investigate the effect of biochar on the physicochemical property and cadmium(Cd) forms present in Cd-contaminated soil, three biochars derived from Sargassum fusiforme, rice straw, and pecan shell were prepared. Thereafter, the Cd adsorption abilities of these biochars were investigated. After applying different dosages of biochar on the Cd-contaminated soil, the changes in physicochemical property and chemical forms of Cd were studied. The results showed that the biochar derived from Sargassum fusiforme displayed the best Cd adsorption ability. Meanwhile, the pH, available phosphorus, rapidly available potassium, total nitrogen, and organic matter content increased along with the dosage of biochar. In addition, all dosages of biochar could decrease the content of exchangeable Cd and enhance the formation of carbonate-bound Cd, Fe-Mn oxide-bound Cd, organic-bound Cd, and residual form of Cd. In summary, biochar application decreased the bioavailability of Cd, and reduced the harmful forms of Cd.