水稻土镉污染与水稻镉含量相关性研究

Relationship Between Paddy Soils Cadmium Pollution and Cadmium Content in Rice

采用盆栽试验的方法,考察了水稻土中重金属镉(Cd)的浓度对水稻生长及Cd富集的影响以及Cd在水稻植株的分布情况,并进一步研究了糙米(可食部位)对Cd的富集量与土壤中Cd总量的关系。结果表明,在各个浓度Cd胁迫下,根、茎叶、稻壳、糙米相比,2个品种水稻都是根累积的Cd含量要高于茎叶和稻壳、糙米,即根>茎叶>稻壳>糙米;在水稻的茎叶细胞中,Cd主要分布在细胞壁,细胞可溶性成分,细胞器Cd的分布量较少,即细胞壁>可溶性部分>细胞器及膜部分;随Cd浓度增加,茎叶中的Cd积累量极显著增加,各细胞组分中的Cd含量均显著增加;根据国标GB 2762—2005对大米中Cd的限量标准(≤0.2 mg.kg-1),水稻土土壤总Cd临界值分别为2.0 mg.kg-(1博优225)、3.1 mg.kg-(1矮糯)。因此,在污染土壤上宜选种食用部位重金属积累低的水稻品种,以减少人类吸收重金属的风险。

Cadmium（Cd） is important contaminants in agricultural soil and threatening agriculture and human health. With the development of industry and agriculture, the soil heavy metal cadmium pollution becomes more and more serious. In this study, two high-yielding rice cultivars currently used in the local production, Boyou 225, Short glutinous treated with five levels of cadmium in a pot experiment was conducted to study the correlation between Cd accumulation of brown rice and that of paddy soils. Results showed that cadmium was not distributed uniformly in each part of rice plants. Most of the absorbed Cd assembled in the root, the upper, the less. The law of distribution of Cd in different organs of rice was： root 〉 stem 〉 rice husk 〉 kernels. In rice roots and stems and leaves, cadmium was mainly distributed in the cell wall. Soluble components of cells, cell distribution of low cadmium. That is, F1 （Cell wall ）〉 F3 （soluble part ）〉 F2 （cell organelles and membrane part）. The rice varieties exhibited the genetic character on the Cadmium accumulation. The Cadmium contents of the grains increased with the increasing Cd concentration in soil. According to the state limit of cadmium in rice, the standard （GB 2762-2005 ）, Content ≤ 0.2 mg·kg^- 1 In this study, tropical paddy soil total Cd threshold were Boyou225 （Cd total）= 2.0 mg· kg^-1; Short glutinous （Cd total）= 3.1 mg· kg^-1. Therefore, for reducing the risk of the humanity to heavy metal, the rice varieties with the low capability of accumulating heavy metal in grains could be planted in a polluted soil.