不同有机物料对水稻根表铁膜及砷镉吸收转运的影响

通过盆栽试验研究了油菜秸秆、蚕豆秸秆、泥炭、猪粪堆肥和生物炭这5种有机物料对贵州石灰岩黄壤区某砷（As）和镉（Cd）复合污染稻田土壤As/Cd有效性、水稻根表铁膜及As/Cd吸收转运的影响.结果表明，施用有机物料显著提高了有机质和水稻生物量；除油菜秸秆对土壤pH值影响不明显外，施用有机物料显著提高土壤pH值，使土壤有效Cd含量降低34.77%~82.69%；猪粪堆肥和生物炭使土壤有效As含量显著提高，油菜秸秆和泥炭处理使土壤有效As含量显著降低；施用有机物料有助于水稻根表铁膜的形成，并使其中Cd、As含量分别提高17.73%~151.03%和28.49%~94.86%，使水稻糙米Cd含量降低15.87%~79.45%，As含量降低27.04%~82.51%，降幅以生物炭处理最大；有机物料还显著降低Cd在根-茎-叶-籽粒的转运系数及As从茎向籽粒转运系数.相关分析表明，土壤pH、有效Cd和铁膜Cd含量是影响籽粒Cd累积的主要因素，土壤pH、有机质和铁膜As含量是影响籽粒As累积的主要因素.有机物料通过改变土壤pH、有机质含量及铁膜中As和Cd含量，影响水稻对As和Cd的吸收和转运.

Effects of Different Organic Materials on Absorption and Translocation of Arsenic and Cadmium in Rice

A pot experiment was carried out to study the impacts of five organic materials (rape straw, broad bean stalk, peat, pig manure compost, and biochar) on the availability of arsenic (As) and cadmium (Cd) in soil, the amount of iron plaque on the root surface, as well as the uptake and translocation of As and Cd in rice grown in an As/Cd co-contaminated yellow paddy soil. The results indicated that the application of organic materials significantly increased the contents of the soil organic matter and the yield of rice. The application of broad bean stalk, peat, pig manure compost, and biochar remarkably increased the soil pH, while the application of rape straw exerted no significant influence. The addition of organic matter reduced the available Cd content by 34.77%-82.69%. However, the effects of organic materials on the availability of As varied with the organic materials. The soil-available As content was significantly increased by the application of pig manure compost and biochar, while it was significantly decreased by adding rape straw and peat. The application of organic materials increased As and Cd contents in the Fe plaques on rice root surface by 28.49%-94.86% and 17.73%-151.03%, respectively. It also reduced the As and Cd contents in brown rice by 27.04%-82.51% and 15.87%-79.45%, respectively. The largest decrease was observed in the biochar treatment. The application of organic materials also remarkably reduced the translocation efficiency of Cd from the root-stem-leaf-grain and that of As from the stem to grain. The correlation analysis revealed that the soil pH, available Cd, and Cd content in the Fe plaques are the major factors influencing the accumulation of Cd in the rice grain. Furthermore, the soil pH, soil organic matter, and As content in the Fe plaques are the major factors influencing the accumulation of As in the rice grain. Therefore, it has been concluded that organic materials could influence the uptake and translocation of As and Cd in rice through changing the soil pH, organic matter content, and As and Cd contents in the Fe plaques.