根际环境中铅的形态转化

Conformation transformation of lead in rhizosphere.

用根际箱试验研究了红壤植麦和植稻后根际中Pb的形态转化 ,讨论了与Cd复合处理对Pb形态的影响 .结果表明 ,Pb在红壤根际、非根际的主要形态为酸解态 +碳酸盐态、交换态和铁锰氧化物结合态 .交换态Pb都是根际 >非根际 ;不同Pb处理浓度和Pb Cd交互作用都对Pb的形态分布产生影响 ,小麦根际随加入Cd浓度增大 ,根际交换态Pb和铁锰氧化物结合态Pb下降 ;水稻根际交换态Pb与Cd复合处理浓度密切相关 ,5mgCd·kg-1复合处理 ,根际交换态Pb的活化较单元素弱 ,10mgCd·kg-1复合处理 ,根际交换态Pb的活化较单元素要强 .

With rhizoboxes,this study dealt with the distribution and conformation transformation of lead in the rhizosphere and non-rhizosphere of wheat and rice grown on red soil. The results showed that the predominant forms of lead were acid dissolved and Carb-Pb (bound to carbonates),Exch-Pb (exchangeable-Pb),and FeMnO-Pb (boud to iron and manganese oxides). Exch-Pb in the rhizosphere of both rice and wheat was much higher than those in the non-rhizosphere, which means that the activation process in the rhizosphere was very strong,and bio-available Pb greatly increased. Various levels of Pb treatment and Pb-Cd interaction also had certain effects on the distribution of lead. In treatment of low Pb concentration,FeMnO-Pb was higher than Exch-Pb,but the contrary result was observed in treatment of high Pb concentration. Both Exch-Pb and FeMnO-Pb in wheat rhizosphere decreased with an increase of Cd. Exch-Pb in rice rhizosphere was correlative to the Cd content in soil. Compared with the treatment in the absence of Cd, the activation of Exch-Pb in rice rhizosphere was weaker in 5 mg Cd·kg -1 treatment, but stronger in 10 mg Cd·kg -1 treatment.