生物质炭对土壤-水稻系统中Cd迁移累积的影响

探究生物质炭添加对Cd污染土壤中Cd形态、植株对Cd的吸收分配及土壤肥力的影响,为污染稻田粮食安全提供科学依据。在湖南省长沙市Cd污染稻田进行田间定位试验,设置5个生物质炭添加量处理(0,10,20,30,40t/hm~2),分析生物质炭对Cd在土壤中形态转化和水稻器官中分配的影响。结果表明:生物质炭通过将土壤中酸溶态Cd钝化为可还原态Cd以减少在水稻器官中的累积,钝化量随着生物质炭增加而增加,土壤酸溶态Cd较CK降低3.83%～19.08%;且茎对根和糙米对茎的转运系数随生物质炭的添加分别降低4.23%～9.30%和1.39%～8.33%;土壤酸溶态Cd含量直接影响糙米中Cd含量,且受土壤pH和土壤有机碳的调控。Cd污染稻田添加生物质炭可以提高土壤肥力,降低土壤Cd生物有效性,20t/hm~2生物质炭添加量可以作为研究区周边Cd污染稻田修复的参考标准。

Effects of Biochar Amendment on Translocation and Accumulation of Cd in Soil-Rice System

In order to provide scientific basis for food safety in rice fields, a field trial was conducted in Changsha, Hunan Province to investigate the effects of biochar amendment on the form of cadmium (Cd), the uptake and distribution of Cd and soil fertility of rice field polluted by Cd. Five biochar application treatments (0, 10, 20, 30 and 40 t/hm²) were set to analysis the effects of the biochar amendment on the migration of Cd in the soil and the distribution of Cd in the rice organs. The results showed that the biochar reduced the accumulation of Cd in the rice organs by passivating the acid-soluble Cd into the reducible Cd in the soil, and the amount of passivation increased with the increasing of biochar, the acid-soluble Cd decreased by 3.83%~19.08% in biochar treatments compared with CK. After the biochar applying, the translocation coefficient of Cd for stem to root and brown rice to stem were decreased by 4.23%~9.30% and 1.39%~8.33%, respectively. The decision analysis showed that the content of the acid-soluble Cd in soil directly affected the Cd content in the brown rice, and was regulated by soil pH and organic carbon in the soil. In conclusion, biochar amendment could improve the soil fertility and decrease the Cd bioavailability in the Cd polluted rice field. The addition of 20 t/hm² biochar could be taken as a reference standard for remediation of the rice field polluted by Cd around the research area.