Investigation Of Se Transfer And Distribution In Soil-crop System Under Heavy Metals And Sulphur Conditions

Amelioration of Se level in food chain is a problem which many researchers have been paying close attention to for many years. Theoretic bases for improving bioconcentration of Se and drawing soil standard of Se can been sustained by investigation of transfer and distribution of Se under S and heavy metals conditions in soil-plant systems in area polluted by acid rain and heavy metals.The transfer and distribution of Se in soil-swamp cabbage system was investigated under both mono- and multi-pollutions of Cu, Zn, Pb and Cd by pot experiments. And the transfer and distribution of Se in brassica campestris, swamp cabbage and rice were investigated under both mono- treatment of Cd, S and multi-treatment of Cd, S and Se. The results showed that:(1) Bioconcentration factors(BCF) of Se in the stem and leaf was lower than that of the root for swamp cabbage under mono- and multi-pollutions of Cu, Zn, Pb and Cd. Cd in soil promoted the absorption of Se in the root and restrained the transfer from the root to the stem and leaf,and the correlation coefficient was the highest; Cu and Zn promoted the absorption of Se; The influence of Pb on the absorption of Se was little, and the same rule as that of Cd was shown. Cu, Zn and Pb improved the absorption of Se ,and Cd restrained the absorption of Se for the stem and leaf under multi-pollution conditions; Correlation coefficients between the content of Se and the content of Cd ,Cu were higher than that of Zn, Pb. Meanwhile, negative correlation for Cu and positive correlation for Cd were also revealed.(2) Under mono-treatment of Cd condition, Cd restrained the absorption of Se and significant negative correlation was revealed in the stem and leaf for swamp cabbage; Cd promoted the absorption of Se and significant positive correlation was shown in the root for brassica campestris. For multi-treatment of Cd-S-Se in the experimental conditions, doping Cd restrained the absorption of Se for swamp cabbage; Cd restrained the absorption of Se in the root and promoted the transfer from the root to the stem and leaf for brassica campestris. For mono-treatment of S in the experimental conditions, S inhibited the absorption of Se in the root and promoted the transfer from the root to the stem and leaf, and significant correlation was shown for swamp cabbage. S little promoted the absorption of Se in the root and restrained the transfer for brassica campestris.For multi-pollution of Cd-S-Se in the experimental conditions, with increasing of S content, S improved the absorption of Se in the root and restrained the transfer from the root to the stem and leaf for swamp cabbage ;S restrained the absorption of Se for brassica campestris, and the correlation was significant.(3) For mono-treatment of Cd or S in the experimental conditions,the lower content Cd or S promoted the absorption of Se and the higher content Cd or S restrained the absorption of Se in unpolished rice; Little correlation between content of Se in unpolished rice and content of Cd in soil was shown, and positive correlation between the content of Se in unpolished rice and the content of S in soil was significant. But in multi-treatment of Cd, S and Se, the absorption of Se was little affected by S, the main affected factors was the content Cd and Se. Se promoted the absorption of Se but Cd restrained the absorption of Se in unpolished rice.Under the conditions of mono- treatment of Cd, S and multi-treatment of Cd, S and Se, the transfer and distribution of Se in soil-crop system not only depended on the content of Se and coexisting elements,but also were influenced by the different vegetables, the different organs in the same vegetable and the different concentration for every coexisting element.