Wang Dan, Li Xin, Wang Dai-chang, Rao Wei, Du Guang-hui, Yang Jun, Hua Dang-ling
Huan Jing Ke Xue. 2015 May;36(5):1877-87.
A pool culture experiment using exogenous Cd-polluted paddy soils was carried out to investigate the influence of different forms of sulfur fertilizers (sulfur and gypsum) on the formation of Fe-Mn plaque on rice root and the uptake of Cd by rice. The results showed that the redox potential ( Eh) was about--200-100 mV, the pH was 6.9-7.9 and the pe + pH was 4-10 in different growth periods of rice. The mass fractions of Fe and Mn plaque on rice root were 5000-13,000 mg · kg(-1) and 170-580 mg · kg(-1), respectively. The high sulfur treatment led to the formation of more Fe plaque than the low sulfur treatment, and the mass fractions of Fe plaque in both treatments were 9400 mg · kg(-1) and 8600 mg · kg(-1) respectively in the boot stage. Contents of Mn plaque, significantly different in the tiller stage by elemental sulfur treatment and gypsum treatment, were 600 mg · kg(-1) and 400 mg · kg(-1), respectively. The elemental S treatment led to the formation of more Mn plaque on rice root than the gypsum treatment. The excessive intake of Fe2+ might be prevented by the formation of the plaque which had little significant influence on the uptake of Mn2+. The mass fractions of Cd adsorbed by rice roots surface plaque were 78.8-131.1 mg · kg(-1) in tiller stage, 16.6-21.1 mg · kg(-1) in boot stage, and 3.0-9.2 mg · kg(-1) in mature stage. The high sulfur treatment led to higher adsorption of Cd by the plaque than the low sulfur treatment in the tiller stage and the boot stage, while opposite result was observed in the mature stage. The values of Cd on the plaque measured by ACA could not truly show its actual contents adsorbed. The mass fractions of Cd in the different parts of rice followed the order of roots > stem leaf > grain. The sulfur fertilizers applied significantly reduced the mass fractions of Cd uptake in different parts of rice, and the elemental sulfur treatment had better effects than the gypsum treatment before the mature stage in roots and stem leaf, and the gypsum sulfur treatment was better for grain. A certain amount of sulfur fertilizers could effectively prevent the migration of Cd from roots to stem and grain. The transfer coefficients of Cd from roots to stem leaf in the elemental sulfur treatment and the gypsum treatment were 0.13 and 0.25 in the boot stage, respectively, and the difference was significant. Elemental sulfur was more effective to prevent the Cd migration from roots to stem leaf, and the gypsum treatment was more active from roots to grain.
通过外源镉污染稻田土壤的池栽试验，研究了不同形态硫肥（硫磺和石膏）对水稻根表铁锰胶膜形成及水稻吸收镉的影响。结果表明，水稻不同生育期氧化还原电位（Eh）约为-200～-100 mV，pH为6.9～7.9，pe+pH为4～10。水稻根表铁、锰胶膜质量分数分别为5000～13000 mg·kg-1和170～580 mg·kg-1。高硫处理比低硫处理形成更多的铁胶膜，孕穗期两处理铁胶膜质量分数分别为9400 mg·kg-1和8600 mg·kg-1。分蘖期硫磺处理和石膏处理的锰胶膜含量差异显著，分别为600 mg·kg-1和400 mg·kg-1。硫磺处理比石膏处理在水稻根表形成更多的锰胶膜。铁胶膜的形成可阻止过量Fe2+的进入，对Mn2+的吸收影响不大。水稻根表胶膜吸附镉的质量分数在分蘖期为78.8～131.1 mg·kg-1，孕穗期为16.6～21.1 mg·kg-1，成熟期为3.0～9.2 mg·kg-1。高硫处理在分蘖期和孕穗期比低硫处理使胶膜对镉的吸附量更高，而成熟期则相反。原子吸收光谱法（ACA）测定的胶膜上镉值不能真实反映其实际吸附量。水稻不同部位镉质量分数顺序为根＞茎叶＞籽粒。施用硫肥显著降低了水稻各部位镉的吸收质量分数，分蘖期前根和茎叶中硫磺处理效果优于石膏处理，籽粒中石膏处理效果更好。一定量的硫肥能有效阻止镉从根向茎叶和籽粒的迁移。孕穗期硫磺处理和石膏处理镉从根向茎叶的转移系数分别为0.13和0.25，差异显著。硫磺更有效地阻止镉从根向茎叶的迁移，石膏处理从根向籽粒的转移更活跃。
