土垫旱耕人为土中某些痕量元素的迁移富集特征及其成因

MIGRATION AND ENRICHMENT OF SOME TRACE ELEMENTS IN EARTH-CUMULI-ORTHIC ANTHROSOLS

土壤中元素的分布特征反映了多个成土因素综合作用下土壤发生过程的结果。为探讨人为因素和自然成土因素在土垫旱耕人为土（壤土）形成过程中的影响，本研究在黄土高原区关中平原西部的渭河三级阶地上采集两个典型的土垫旱耕人为土剖面，以马兰黄土作为成土强度的参照样品，采用Zr作为稳定元素，研究痕量元素Cu、Zn、Pb、Rb、Sr的分布特征及其成因。结果表明，受介质的吸附、碳酸钙等易淋溶组分的淋溶淀积、作物吸收等因素影响，痕量元素Cu、Zn、Pb、Rb在剖面上总体呈中高型分布，即在干润淋溶土表层（2A层）和黏质化B层（2Bt层）含量有所增加而表现为富集；而Sr则发生强烈迁移，在2A层、2Bt层含量显著降低。在埋藏耕作层（Aupb层）、亚耕层（Aup2层）和现代耕作层（Aup1层），自下而上，Cu、Zn、Pb的含量呈缓慢增加趋势，但只有Zn的富集系数在YL01剖面0～15cm内大于1．1，说明土壤发生过程是导致土垫旱耕人为土剖面中某些层次元素相对富集的主要原因，而人类活动对土垫旱耕人为土痕量元素的影响很弱，且主要在表层。

Distribution characteristics of elements in soil reflect the result of pedogenic process under the integrated impact of a number of natural and anthropogenic factors. In order to understand influences of human activities and natural processes on formation and evolution of Earth-cumuli-Orthic Anthrosols, two typical profiles of Earth-cumuli-Orthic Anthrosols were collected on the third terrace of the Weihe River in the central-west Loess Plateau for analysis of distribution characteristics of trace elements, including Cu, Zn, Pb, Rb, Sr. Results show that Cu, Zn, Pb, and Rb were relatively enriched in the buried paleo-surface horizon （2A） and paleo-argillic horizon （2Bt）, where natural pedogenic eluviation and illuviation was playing a main role. Under the relatively warm and moist climate, Sr leaching was strong, showing entirely contrary distribution characteristics with obvious loss in the horizons of 2A and 2Bt. From the buried plow horizon （Aupb） to the sub-plow horizon （ Aup2 ） and the modern plow horizon （ Aup1 ）, contents of Cu, Zn and Pb increased slowly. According to the calculated relative enrichment coefficient, only Zn in Aup1 horizon of YL01 profile was obviously enriched with an enrichment coefficient higher than 1.1 , showing that the influence of human activities on the contents of trace elements in Earth-cumuli-Orthic Anthrosols is generally quite weak.