硅肥耦合水分管理对复合污染稻田土壤As-Cd生物有效性及稻米累积阻控

选取湖南某矿区重金属镉、砷复合污染稻田土,以泰优390号为材料,通过盆栽试验研究湿润灌溉(CK)、农艺措施淹水(WF)、速溶硅肥结合淹水措施(FYsi)、矿物硅肥结合淹水措施(FKsi)及2种硅肥结合淹水(FYK)对土壤中As、Cd生物有效性及水稻糙米中As、Cd累积效应的影响.结果表明,淹水处理土壤p H值上升幅度为0.12~0.72个单位,均呈现先升高再下降,最后趋于中性的规律.淹水后,土壤Eh显著降低,FYsi、FKsi、FYK这3种配合硅肥的淹水处理土壤Eh值显著高于WF处理,与对照相比,淹水处理糙米中Cd含量降低了38.83%~65.05%,其中,WF、FYK处理对糙米Cd累积抑制效果最佳,糙米中Cd含量为0.98 mg·kg~(-1)、0.72 mg·kg~(-1);除WF处理糙米中As含量增加了36.64%外,FYsi、FKsi、FYK处理糙米中As的含量与对照相比分别降低了23.80%、38.10%、47.62%.FYsi、FYK处理对糙米As累积抑制效果最佳,糙米中As含量为0.13 mg·kg~(-1)、0.11 mg·kg~(-1).Cd各提取态含量与其在水稻糙米中的含量均呈现出极显著的正相关关系(P0.01);可交换态、TCLP提取态As与水稻糙米中As含量无显著相关关系.因此,FYsi、FKsi、FYK这3种施硅耦合淹水处理均可有效阻控稻米镉砷复合污染,其中FYK效果最佳.

Bioavailability of Silicon Fertilizer Coupled Water Management on Soil Bioavailability and Cumulative Control of Rice in Compound Contaminated Paddy Soils

The effect of wet irrigation (CK), agronomic measure flooding (WF), instantaneous silicon fertilizer combined with flooding measures (FYsi), mineral silicon fertilizer combined with flooding measures (FKsi), and a mix of two kinds of silicon fertilizer combined with flooding measures (FYK) on the bio-availability of As and Cd in soil and the accumulation of As and Cd in rice were investigated by pot experiments. The results showed that the pH of the soils combined with flooding measures was increased by 0.12-0.72 units with similar trends of an increase and then a decrease before finally become neutral. The Eh of the soil combined with flooding was significantly decreased, but the Eh of soil after flooding treated by FYsi, FKsi, and FYK combined with the flooding was significantly higher than that treated by WF, and the content of Cd in brown rice was reduced by 38.83%-65.05% compared with that treated by CK. The WF and FYK treatments can significantly reduce the accumulation of Cd in brown rice, resulting in the lowest Cd contents in brown rice of 0.98 and 0.72 mg·kg^-1, respectively. The contents of As in brown rice treated by FYsi, FKsi, and FYK were decreased by 23.80%, 38.10%, and 47.62%, respectively, compared with that with the CK treatment, except that the content of As in brown rice treated by WF increased by 36.64%. FYsi and FYK treatments had the best inhibitory effect on the accumulation of As in brown rice, with the lowest As contents of 0.13 mg·kg^-1 and 0.11 mg·kg^-1 in brown rice (P <0.01), respectively. There was an extremely significant correlation between the contents of extractable Cd and the total content of Cd in the brown rice (P <0.05), and there was no significant difference between the contents of extractable As and the total content of As in the brown rice. Therefore, FYsi, FKsi, and FYK can effectively inhibit the accumulation of Cd and As in rice grown in Cd-As compound polluted soil, and FYK showed the best performance.