Implication and application of stable carbon and oxygen isotopes of pedogenic carbonates in soils 土壤次生碳酸盐碳氧稳定同位素古环境意义及应用
2.
The central concept of entisols is that of soils that have little or no evidence of development of pedogenic horizons 新成土的主要特性在于其只有极弱度的或没有土壤发生层的发育特征。
3.
( 2 ) there is stage of soil formation from the evolution of pedogenic environment in the weihe valley during holocene . soil formation shows the law of evolving from warm and wet strong soil formation period to cold and dry dust deposition period ( weak soil formation period ) and to warm and wet strong soil formation period again . the loess - soil sequence is a compound soil sectional system of different kinds of soil evolution under different bio - environment and pedogenic processes （ 2 ）通过对全新世渭河流域成壤环境演变问题的讨论，揭示了全新世渭河流域土壤的发育具有阶段性，表现为由温湿的强成壤期向冷干的沉积期（弱成壤期）演变、再向温湿的强成壤期演变的规律；黄土一古土壤序列是不同生物气候环境下、不同成壤过程发育的不同土壤类型演替而形成的复合型土壤剖面体系；而且由于冬夏季风环流及其环境效应在空间上的差异，使得复合型土壤剖面体系也存在着南北差异。
4.
The main results are following : ( 1 ) the variation of clay / silt ratio can indicate the secondary clay action of dust depositions ; the variations of magnetic susceptibility and total fe content are inferred to be records of the changeable intensity of bio - pedogenesis ; the variations of sr content and rb / sr ratio can indicate bio - pedogenesis , dissolving and leaching action ; the content of total organic carbon ( toc ) can reflect variation of climate and vegetation during soil formation , it indicates the intensity of weathering and bio - pedogenesis ; the content variation of caco3 can show the intensity of dissolving - leaching action and secondary deposit , which was noted as pseudomycilia in pores and fissures in the sediment , so it can indicate the intensity bio - pedogenesis quite well . these proxy indexes also reflect obvious regional difference of pedogenic environment and the intensity bio - pedogenesis ; namely , secondary clay action , dissolving - leaching action and bio - pedogenesis are all much stronger in south than that in north 实验结果表明：粘粒粉沙比值能很好地指示粉尘堆积物的次生粘化作用；磁化率和全铁很好地指示生物风化成壤作用； sr和rb sr比值能很好的指示生物风化成壤作用和淋溶作用；总有机碳( toc )含量的高低，在一定程度上反应了土壤发育过程中气候和植被状况的变化，指示着成壤过程中腐殖质化的程度； caco3含量的变化，可以反映了黄土古土壤形成时的风化成壤作用的强弱程度，指示成壤过程中的淋溶作用和次生碳酸盐化作用；并且各指标所指示的成壤环境和成壤强度存在明显的区域差异，即渭河流域土壤的生物风化成壤作用、次生粘化作用和淋溶作用均表现出南部强于北部。
5.
In this study , three typical high - resolution holocene soil profiles in the weihe valley were studied using particle - size analysis , measurement of magnetic susceptibility , total fe , toc , caco3 , rare earth elements and others . the results provide new insights into pedogenic environmental evolution and human impact of cultivation on soil development in this climatically sensitive semiarid zone 通过对各指标实验结果及其成壤环境意义的分析，探讨了全新世渭河流域成壤环境的演变以及土壤发育的特点；并借助历史文献和环境考古的成果，分析了人类活动与成壤环境之间的相互作用及其人地关系演变的过程。
