赤泥对Cd污染稻田水稻生长及吸收累积Cd的影响

Effects of Red-mud on Rice Growth and Cadmium Uptake in Cadmium Polluted Soil

采用田间小区试验,研究了不同赤泥施用量对酸性Cd污染稻田(潮泥田)水稻生长及吸收累积Cd的影响。结果表明,赤泥施用量为4948kg·hm-2时水稻产量达到最高,其主要作用是促进了水稻有效穗的形成。同时施用赤泥能显著提高土壤pH,降低土壤有效态Cd含量和减少水稻Cd累积。与不施赤泥的对照相比,施用赤泥3000kg·hm-2的处理水稻增产12.4%(P<0.05),水稻根Cd降低22.0%(P<0.05),糙米Cd(0.14mg·kg-1)降低40.8%(P<0.01),并达到国家粮食卫生标准(GB2715—2005);当赤泥施用量增至9000kg·hm-2时,土壤pH提高12.0%(P<0.01),有效态Cd含量降低24.9%(P<0.05),水稻根系、茎叶和糙米Cd分别降低55.7%(P<0.01)、54.5%(P<0.01)和69.9%(P<0.01)。表明利用赤泥修复中轻度酸性Cd污染土壤是可行的,并能起到改良土壤和促进水稻增产的效果。试验所用赤泥重金属含量很低,不会造成二次污染。但将赤泥大面积应用于酸性Cd污染稻田还需要系统研究应用参数,并采取农机配套和激励机制来鼓励农民自发行动的积极性。

A field plot experiment was conducted to study the effect of different amount of red mud application on the growth of rice and Cd uptake by rice in acidic Cd polluted soil （ Alluvial Loamy Paddy Soil ）. The results showed that rice reached the highest yield as application of red mud up to 4 948 kg·hm-2. The main reason of yield promotion by red mud was that red mud is favor to form the rice effective ear. Meanwhile, red mud application increased the soil pH significantly and decreased the soil available Cd content and rice Cd accumulation. Compared with the control of no red mud application, rice yield was increased by 12.4% （P〈0.05）, root Cd content was decreased by 22.0% （P〈 0.05）, and the brown rice Cd content （0.14 mg·kg^-1） was decreased by 40.8%（P〈0.01 ） after red mud application up to 3 000 kg·hm-1; Further when red mud reached 9 000 kg·hm-2, the soil pH was increased by 12.0%（P〈0.01 ）, soil available Cd content was declined by 24.9% （P〈0.05）, and the Cd content of root, straw and brown rice were decreased by 55.7%（P〈0.01 ）, 54.5%（P〈0.01 ） and 69.9%（P〈0.01 ） respectively. It could be concluded that it was feasible for remediation of acidic soil moderately or slightly contaminated by Cd using red mud due to its improvement of soil pH and decrease of soil Cd activity. Specially, the secondary pollution of red mud could be avoided due to its very low heavy metal content. But it was necessary to study application parameters systematically for the widespread application of red mud in acidic paddy soil polluted by Cd. Moreover, the relevant agricultural machinery and incentive mechanism should be adopted to encourage the farmers spontaneously.