摘要
正构烷烃(n-alkanes)是土壤有机质中的稳定组分,明确黑土中正构烷烃的组成及赋存机制对揭示黑土有机质来源和成土环境的变化具有重要意义。本研究对松嫩平原三种成土模式的均腐土开展研究,分别是相对稳定地形条件下自然发育的海伦剖面、非稳定地形条件下受侵蚀堆积过程影响的依安剖面以及动物扰动过程明显的绥化剖面,采用超声萃取法提取土壤中游离态正构烷烃,并对其分布特征和单体碳同位素组成进行分析。研究结果显示,海伦和依安剖面正构烷烃分布呈现单峰型,主峰为C_(31)且奇偶优势明显,而绥化剖面呈双峰型,主峰为C_(23)和C_(31)。海伦和绥化剖面正构烷烃浓度(ΣC_(25~35))和碳优势指数(CPI)自下而上增加且绥化剖面值波动更明显,而依安剖面ΣC_(25~35)和CPI值在埋藏层显著增加,表明正构烷烃可以反映黑土的侵蚀堆积和扰动过程,即埋藏层有利于正构烷烃的固存,而扰动可能会干扰正构烷烃原位记录的指示意义。正构烷烃链长比值(Ratio)及其碳同位素(δ^(13)C_(alk))结果指示土壤有机质主要来源于陆生高等植物,以C3植物为主。全新世以来松嫩平原黑土区主要以草本植物占优势,但在黑土发育过程中木本植物比例逐渐增加。结合^(14)C年代数据认为冰消期气候条件可能有助于黑土初步发育,而早中全新世相对暖湿的气候则加速了黑土形成。
【Objective】Normal alkanes(n-alkanes)are relatively stable components of soil organic matter.Identifying the composition and occurrence mechanisms of n-alkanes in black soil is of great significance,as it can reveal the source of organic matter and the changes in the soil-forming environment.The purpose of this study was to evaluate the influence of soil-forming processes on the n-alkane index of black soil and to explore the indicative significance of n-alkanes in black soil.【Method】In this study,samples from three typical soil formation processes of Isohumosols in the Songnen Plain were collected,including the HL profile naturally developed under relatively stable terrain conditions,the YA profile affected by erosion and accumulation under unstable terrain conditions and the SH profile with evident animal disturbance processes.The ultrasonic extraction method was utilized to extract free n-alkanes from the soil.The distribution characteristics and compound-specific carbon isotopes were analyzed.【Result】The results showed that the HL and YA profiles were unimodal,with the main peak being C31 and the odd-even predominance,while the SH profiles were bimodal,with the main peak being C_(23) and C_(31).The ΣC_(25~35) and CPI values of HL and SH sections decreased with the depth of the section,while theΣC25~35 and CPI values of the YA section increased in the buried layer.The mean δ^(13)Calk values of HL and YA profiles ranged from-29.30 to-30.27‰ and-29.79 to-32.60‰,respectively.Our results indicate that the buried layer is found to enhance the retention of n-alkanes,while disturbance may disrupt other indicators of n-alkanes in situ records.Furthermore,the analysis of n-alkanes and their carbon isotopes suggests that soil organic matter primarily originates from terrestrial higher plants,particularly C3 plants.Since the Holocene period,herbaceous plants dominate the black soil area of the Songnen Plain,with the proportion of woody plants gradually increasing during the development of black soil.Combining the data from 14C dating,it is inferred that the climatic conditions during the last deglaciation likely played a role in the initial development of black soil,while the warm and wet climate of the Middle Holocene contributed to the maturity of black soil.【Conclusion】These results confirm that n-alkanes in black soil can reflect the impact of soil erosion-deposition and disturbance on n-alkanes.Thus,this study will provide a basis for revealing the changes in organic matter sources during the formation of black soil and reflect the soil-forming environment of black soil.
作者
邱梓菲
师永辉
李婧婧
杨飞
隆浩
张甘霖
QIU Zifei;SHI Yonghui;LI Jingjing;YANG Fei;LONG Hao;ZHANG Ganlin(State Key Laboratory of Lake Science and Environment,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 211135,China;University of Chinese Academy of Sciences,Beijing 100049,China;State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 211135,China)
出处
《土壤学报》
北大核心
2025年第4期1038-1048,共11页
Acta Pedologica Sinica
基金
国家自然科学基金项目(42130715)
国家重点研发计划项目(2023YFD1500101)资助。
关键词
正构烷烃
黑土
松嫩平原
单体碳同位素
土壤发生
n-Alkanes
Black soil
Songnen Plain
Compound-specific carbon isotope
Pedogenesis
