摘要
稀土元素在土壤中的含量和分馏特征对它们在环境中的分布、迁移、转化、归宿以及生态效应都有重要的影响。铁锰氧化物矿物的表面作用已被认为是表生环境中元素活化迁移和污染的重要机制之一。本研究以亚热带北端的长江三角洲地区和亚热带南端的珠江三角洲地区的典型水稻土和潮土剖面为例,探讨了铁锰体系对土壤稀土元素含量和地球化学分馏的影响。研究结果表明:铁锰氧化物中以晶质态氧化铁与土壤稀土元素的结合作用为主,并且对潮土的作用要比水稻土更为显著。游离态氧化铁对水稻土Ce富集和Eu亏缺均有积极贡献;锰氧化物可能会通过对二价Eu的氧化而减少其在土壤中的亏缺程度。水稻土和潮土中稀土元素在剖面中的分馏程度也受到铁锰氧化物含量的影响,低含量的铁锰氧化物会使不同发生层之间稀土元素的分馏差异增大。Eu在铁游离度高的南亚热带水稻土中会通过还原并随Sr元素一起淋失。
Contents and geochemical fractionation of rear earth elements （REE） in soil both have important impacts on distribution,migration,transformation and fate of the REE in the environment. The surface functions of iron/manganese oxide minerals on elements have been thought to be one of the important mechanisms of activation, migration and pollution of the elements in the biotic and abiotie environment. Typical soil profiles of paddy soil and Chao soil were selected in the Yangtze River Delta region and the Pearl River Delta region, representing the northern tip and southern tip of the sub-tropical zone in China, respectively, for analysis of effects of iron/manganese oxides on contents and geochemical fractionation of REEs. Results show that among the iron/manganese oxides, crystalline iron oxides bind REEs in the soils, which is more significant in Chao soil than in paddy soil. Free iron oxides in paddy soil have a positive effect on accumulation of Ce and depletion of Eu,while manganese oxides reduce the extent of Eu deficiency probably through oxidation of Eu from bivalent cation to trivalent cation. Moreover,the content of iron/manganese oxides also affect REE fraetionation in the soil profiles, that is,the lower the content of iron/manganese oxides,the bigger the difference of REE fractionation between soil layers. In paddy soils high in free iron,in the southern subtropical zone, Eu is readily reduced and leached with Sr from the soils, which is contrary to the paddy soils in the northern subtropical zone.
出处
《土壤学报》
CAS
CSCD
北大核心
2010年第4期639-645,共7页
Acta Pedologica Sinica
基金
国家自然科学基金项目(40901152)
国家重点基础研究发展规划项目(2002CB410810)资助
关键词
水稻土
潮土
稀土
分馏
土壤剖面
Paddy soil
Chao soil
REE
Fractionation
Soil profile
