控制灌溉稻田土植系统Cd,Cr迁移转化

Migration and transformation of Cd and Cr in paddy soil-plant system under controlled irrigation

为研究不同灌溉模式下稻田土壤Cd,Cr淋失量差异及其对Cd,Cr迁移转化的影响,基于田间小区试验对土壤和水稻植株中Cd,Cr含量进行了分析.研究结果表明:与淹水灌溉相比,控制灌溉可减少水稻全生育期稻田土壤Cd,Cr淋失量53.3%和19.3%.控制灌溉降低了稻田土壤Cd,Cr含量,但处理间稻田土壤Cd,Cr含量不具有统计学意义.与淹水灌溉相比,控制灌溉0～20 cm土壤Cd,Cr含量分别下降了1.2%和0.6%.由于水分管理不同,导致控制灌溉表层土壤Cd,Cr的赋存形态与淹水灌溉的差异.大部分时间里控制灌溉的稻株地上部和地下部Cd,Cr累积量均高于淹水灌溉,说明控制灌溉增大了土壤Cd,Cr在植株体内的吸收.无论是控制灌溉还是淹水灌溉,稻穗Cd含量低于我国食品安全国家标准(0.2 mg/kg),而稻穗Cr含量略高于我国食品安全国家标准(1.0 mg/kg),存在着Cr超标的潜在风险.因此,这2种灌溉方式在预防重金属污染方面不可取,会影响人类健康.

The aim of this study is to determine the effects of irrigation pattern on leaching,migration,and transformation of Cd and Cr in a paddy soil-plant system.The concentrations of Cd and Cr in rice plant and paddy soil were measured in field plot experiments.The results showed that the leaching contents of Cd and Cr were reduced by 53.3% and 19.3% under controlled irrigation compared with flooding irrigation,thus the contents of Cd and Cr in paddy soil were decreased under the controlled irrigation;but there is no significant difference in Cd and Cr contents between controlled and flooding irrigation for the paddy soil after fertilization.The contents of Cd and Cr in 0-20 cm depth paddy soil were decreased by 1.2% and 0.6% in controlled irrigation compared with flooding one,suggesting irrigation pattern leads to different binding forms of Cd and Cr in the paddy soil.In most of time,the accumulated contents of Cd and Cr in the plant bodies above and under soil were higher in controlled irrigation than in flooding irrigation,implying the controlled irrigation can enhance Cd and Cr concentrations in plants.The Cd content in rice seeds was near the tolerance（0.2 mg/kg） in food products re-commended by National Food Safety Standard,China,but the Cr content was higher than the corresponding tolerance（1.0 mg/kg） in food products in controlled and flooding irrigation,thus there is a potential risk in Cr content over the tolerance.Clearly,these two kinds of irrigation are unhelpful in prevention from heavy metal pollution,and the rice seeds produced in those irrigation patterns can affect human health.