不同地区土壤中分蘖期水稻根表铁氧化物的形成及其对砷吸收的影响

Effect of Iron Plaque Formation of Root Surface on As Uptake by Rice Seedlings Grown on Different Types of Soils

通过土壤盆栽试验研究了14种不同土壤中种植水稻后，其根表铁膜形成量的情况，及其对苗期水稻吸收和转运砷的影响．结果表明，生长在不同土壤中的水稻其根表铁膜的形成量有显著的差异，铁膜形成量最大为61．97mg／g，最小仅为1．15mg／g，分析表明土壤中非晶质态氧化铁含量的不同是其主要的影响因素之一．同时测定了根表铁膜中砷的含量，铁膜上吸附的砷浓度最大为1376mg／kg，最小低于检测限，其与根表铁膜形成量之间存在着显著的正相关性（r=0．85，17,=14，P〈0．05），而与土壤溶液中有效态的砷浓度无显著的相关性；水稻植株地上部砷浓度（0．400～12．98mg／kg）和地下部砷浓度（3．860～576．2mg／kg）与根表铁膜的形成量之间也都存在着显著的正相关性（r=0．88，n=14，P〈0．05；r=0．91，n=14，P〈0．05），与土壤溶液中有效态的砷浓度无显著的相关性；水稻根系对砷的吸收能力（SAU，0．005～0．670mg／g）与根表铁膜形成量之间也为显著的正相关性（r=0．91，n=14，P〈0．05）；根表铁膜形成量与砷的转运之间无显著的相关性．结果表明，在此次试验中土壤的非晶质态氧化铁的含量是水稻根表铁膜形成的影响因素之一，根表铁膜的存在成为了根际砷的富集库，起到了促进根际砷吸收的作用，但对砷的转运没有显著的影响．

The objective of study was to investigate the effect of the amount of iron plaque of root surface on As uptake by rice seedlings grown on ld types of soils. These results indicated that there were significant differences in the amounts of iron plaque （ 1. 15-61.97 mg/g） formed on rice root surface among different soils, The amount of non-crystalloid Fe oxide in different submerged soils is one of main influencing factors. There was a significant positive correlation between As concentrations in iron plaque （0-1 376 mg/kg） and the amount of iron plaque（ r = 0. 85, n = 14 ,p 〈 0.05 ） , but no significant correlation with the extractable As concentration of 14 types of soils. There were also significant positive correlation between As concentrations in shoot （0. 400-12.98 mg/kg） and root （3. 860- 576.2 mg/kg） and the amounts of iron plaque respectively but not significant correlation with the extractable As concentrations of 14 types of soils （ r = 0. 88, n = 14 ,p 〈 0.05 ; r = 0. 91, n = 14 ,p 〈 0. 05 ）. Moreover, there was a significant positive correlation between specific arsenic uptake （0. 005-0. 670 mg/g） and the amount of iron plaque （ r = 0. 91, n = 14,p 〈 0. 05 ）. However, there was no significant correlation between shoot-As% and the amount of iron plaque. These results showed that the iron plaque on root surface was the pool of As in rhizosphere and increased As uptake but did not affect As transportation from rice root to shoot.