稻田镉砷污染阻控原理与技术应用

我国农田土壤重金属污染治理已成为重大国家需求;水稻是重金属超标最为严重的粮食作物;镉/砷污染稻田是农田重金属污染治理的重点与难点。以农产品安全为目标,以定向调控重金属的活性、阻隔其转移的阻控技术,是农田重金属污染治理的新思路,对解决稻田重金属污染治理难题具有重大意义。铁是稻田中最为重要的活性元素,稻田铁循环是连接养分循环与镉/砷行为的枢纽;调控铁与碳/氮循环的耦合过程,可降低土壤中镉/砷向水稻根系迁移的活性,从而减少水稻植株吸收积累镉/砷。硅与硒等营养元素与水稻镉/砷吸收转运密切相关,外源施加硅/硒养分可降低水稻吸收、转运镉/砷的功能基因表达,提高其解毒功能基因表达,从而抑制镉/砷从水稻根系向籽粒的转运。基于以上原理研发了硅/硒营养调控的生理阻隔技术、铁循环调控的钝化技术,并研制了相应的产品。大田试验结果表明,生理阻隔和土壤钝化技术单独应用或组合应用,均可有效降低稻米中镉/砷含量,从而提高稻米的安全性,具有广阔的应用前景。

Principle and technique of arsenic and cadmium pollution control in paddy field

Control of heavy metal pollution of farmland soil in China has become a major national demand; compared to other cereals, rice is particularly susceptible to heavy metal accumulation with the highest proportion exceedling the safety standard; cadmium/arsenic pollution of paddy field is the emphasis and difficulty for control of heavy metal pollution in farmland. Aiming for the safety of agricultural products, control technique which directionally regulates activities of heavy metals and inhibits their transports provides a new thought for control of heavy metal pollution and is of great significance to solve the problem of remediation of heavy metal pollution in paddy field. Iron is the most important active element in paddy field. The iron cycle in paddy field is the hub connecting the cycling of nutrients and cadmium/arsenic behaviors; it can reduce the migration activities of cadmium/arsenic from soil to rice roots through regulating the coupling processes of iron and carbon/nitrogen cycle and thus decrease accumulations of cadmium/arsenic in rice plants. Silicon and selenium and other nutrients are closely related to the uptakes and transports of cadmium and arsenic in rice. Exogenous application of silicon/selenium nutrients can reduce the expression levels of genes accociated with absorptions and transports of cadmium/arsenic in rice and increase the gene expression of detoxification, thereby inhibiting transports of cadmium/arsenic from rice roots to grains. Based on the above principles, the silicon/selenium nutrient-regulated physiological barrier technology and the iron cycling-regulated passivation technology were developed, and corresponding products were also developed. The results of the field experiments showed that the physiological barrier and soil passivation techniques applied alone or in combination can effectively reduce the cadmium/arsenic contents in rice and thus increase rice safety. These technologies have broad application prospects.