Iron fractions responsible for the variation of Cd bioavailability in paddy soil under variable pe+pH conditions
Iron fractions responsible for the variation of Cd bioavailability in paddy soil under variable pe+pH conditions
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不同pH条件下水稻土中镉生物利用度变化的铁组分
DOI：
10.1016/j.chemosphere.2020.126355
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发表时间：
2020
期刊：
影响因子：
8.8
通讯作者：
Han Yun
中科院分区：
文献类型：
--
作者：
Li Shanshan;Chen Shibao;Wang Meng;Lei Xiaoqin;Zheng Han;Sun Xiaoyi;Wang Lifu;Han Yun
土壤中铁与水稻对镉的吸收密切相关，土壤pe + pH显著影响铁的氧化还原行为。本研究旨在探讨不同pe + pH条件对根际铁氧化物转化的影响机制及其对水稻Cd积累的影响。采用盆栽试验研究了土壤pe + pH对土壤铁氧化物形态和铁膜形成的影响，以及这些变化对水稻吸收Cd的影响。不同的灌溉策略，70%持水量（DY），连续淹水（FL），和交替淹水/每周干燥（AWD），用于实现不同的土壤pe + pH值水平。结果表明，低pe + pH条件（FL和AWD处理下）更有利于根际土壤中结晶态氧化铁向无定形态的转化和IP在水稻根上的沉淀。无定形铁氧化物的增加，导致根际土壤镉的有效性降低，更多的镉固定在铁氧化物。此外，水稻根表吸附的Cd与IP反应，抑制Cd的土壤到根的运输。这两种机制共同作用，使低pe + pH条件下水稻地上部Cd浓度比高pe + pH（DY处理）降低14.1-33.1%。这些结果表明，降低土壤pH值有效地减少镉在水稻植株中的积累，可能是通过固定的无定形铁氧化物对镉和螯合的铁菌斑对镉。
Iron (Fe) in soil is closely related to cadmium (Cd) uptake by rice plants, and soil pe + pH significantly influences Fe redox behavior. This study aimed to explore the influential mechanisms of varying pe + pH conditions on the transformation of iron oxides in the rhizosphere and the subsequent effect on Cd accumulation in rice plants. A two-month pot experiment was conducted to investigate the effect of soil pe + pH on the fractions of iron oxides and formation of iron plaque (IP), as well as the effect of these changes on Cd uptake by rice plants (Oryza sativaL.). Different irrigation strategies, 70% water holding capacity (DY), continuous flooding (FL), and alternate flooding/drying weekly (AWD), were used to achieve various soil pe + pH levels. The results showed that low pe + pH conditions (under the FL and AWD treatments) were more beneficial to the transformation of crystalline iron oxides into amorphous forms in rhizosphere soil and the precipitation of IP on rice roots. The increase of amorphous iron oxides resulted in the reduction of Cd availability in rhizosphere soil by immobilizing more Cd on Fe oxides. Moreover, Cd adsorbed on rice root surfaces reacted with IP, inhibiting Cd soil-to-root transport. The two mechanisms combinatively functioned at decreasing Cd concentration in rice shoots by 14.1–33.1% at low pe + pH conditions compared to that of the high pe + pH (DY treatment). These results indicate that lowering soil pe + pH effectively reduced Cd accumulation in rice plants, probably through the immobilization of amorphous Fe oxides on Cd and sequestration of iron-plaque on Cd.