珠江三角洲稻田土壤砷及其向水稻籽粒迁移特征

采集珠江三角洲区域水稻(Oryze sativa L.)植株的根系、秸秆、稻谷和对应的耕层土壤(0～15锄)样品,分析土壤和水稻植株中砷含量,初步研究土壤砷与土壤基本理化性质的关系及砷在土壤-水稻系统中的迁移规律.结果表明,土壤砷含量在1.83～18.14 mg·kg~(-1)之间,土壤砷与土壤有机质、砂粒含量呈显著负相关,与土壤粉粒含量呈显著正相关.糙米中的砷含量在0.21～0.43mg·kg~(-1)之间,均未超过国家食品卫生标准(0.7mg·kg~(-1)),砷在水稻植株中的分布规律为根>秸秆>颖壳>糙米.糙米砷含量与秸秆砷含量呈极显著正相关,与秸秆中P/As、Si/As摩尔比呈极显著负相关,因此,降低秸秆中As的积累、增加秸秆中P、Si的积累可降低水稻籽粒中的砷含量.

Soil arsenic concentration in paddy fields and its transfer to rice(Oryza sativa L .) grain in Pearl River Delta

The rice(Oryza sativa L .) root, straw, grain and corresponding surface soils(0-15cm) were collected in paddy fields of Pearl River Delta area, the arsenic concentrations in soils and different parts of rice plant were analyzed, and the correlations between soil arsenic and basic soil properties, arsenic transfer in soil -rice system were studied in this paper. The results indicated that soil arsenic concentrations ranged from 1.83 to 18.14 mg·kg~(-1), soil arsenic negatively correlated with soil organic matter, sand content, positively correlated with soil silt content. The arsenic concentrations in rice grain ranged from 0.21 to 0.43mg·kg~(-1), met the requirement of the national food hygiene standards(0.7mg·kg~(-1)). The distribution of arsenic in different parts of rice plant was root > straw > husk > rice grain. Arsenic concentrations in rice grain had significantly positive correlation with rice straw, whereas significantly negative correlation with Si/As molar ratio, P/As molar ratio, which suggested decreasing As accumulation, and increasing Si and P accumulation in rice straw can decrease As concentration in rice grain.