Effects of alternating wetting and drying versus continuous flooding on chromium fate in paddy soils.
Effects of alternating wetting and drying versus continuous flooding on chromium fate in paddy soils.
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DOI：
10.1016/j.ecoenv.2014.12.030
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发表时间：
2015-03
影响因子：
6.8
通讯作者：
Wendan Xiao;X. Ye;Xiaoe Yang;Tingqiang Li;Shouping Zhao;Qi Zhang
中科院分区：
文献类型：
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作者：
Wendan Xiao;X. Ye;Xiaoe Yang;Tingqiang Li;Shouping Zhao;Qi Zhang
土壤中的人为铬（Cr）污染通过食物链对人类健康构成巨大威胁。了解铬在适合水稻生长的条件范围内的归宿势在必行。本研究通过温室条件下的盆栽试验，研究了灌溉管理对稻田孔隙水 Cr(VI) 浓度动态和水稻 Cr 分布的影响。连续淹水（CF）处理的土壤氧化还原电位表明，在整个水稻生育期，还原条件一直存在，而干湿交替（AWD）处理的土壤氧化还原电位则表明，土壤条件在还原和好氧之间交替变化。由于土壤氧化还原电位是影响水稻土Cr(VI)还原的重要因素，不同灌溉管理下Cr(VI)浓度的动态变化明显不同。在CF处理中，孔隙水Cr(VI)浓度随着种植后时间的推移而降低，而在AWD处理中，孔隙水Cr(VI)浓度随着灌溉周期交替增加和减少。在水稻生长季的大部分时间里，CF 处理中的六价铬浓度低于 AWD 处理。此外，水稻组织中的Cr浓度受到灌溉的显着影响，AWD处理中的Cr浓度相对较高，这可能归因于AWD处理中孔隙水Cr(VI)浓度较高。因此，对于Cr污染的水稻土，最好采用CF而非AWD管理来减少水稻中Cr的积累，从而降低对人类健康的潜在风险。
Anthropogenic chromium (Cr) pollution in soils poses a great threat to human health through the food chain. It is imperative to understand Cr fate under the range of conditions suitable for rice growth. In this study, the effects of irrigation managements on dynamics of porewater Cr(VI) concentrations in rice paddies and Cr distribution in rice were investigated with pot experiments under greenhouse conditions. Soil redox potential in continuous flooding (CF) treatments showed that reducing conditions remained for the whole duration of rice growing period, while soil redox potential in alternating wetting and drying (AWD) treatments showed that soil conditions alternately changed between reducing and oxic. As soil redox potential is an important factor affecting Cr(VI) reduction in paddy soils, dynamics of Cr(VI) concentration were clearly different under different irrigation managements. In CF treatments, porewater Cr(VI) concentrations decreased with time after planting, while in AWD treatments porewater Cr(VI) concentrations were increased and decreased alternately response to the irrigation cycles. Chromium(VI) concentrations in the CF treatments were lower than those in AWD treatments for most part of rice-growing season. Moreover, Cr concentrations in rice tissues were significantly influenced by irrigation with relatively higher values in the AWD treatments, which might be attributed to the higher porewater Cr(VI) concentrations in AWD treatments. Therefore, it would be better to use CF than AWD management in Cr-contaminated paddy soils to reduce Cr accumulation in rice, and thus to reduce the potential risk to human health.