摘要
土壤次生碳酸盐碳氧稳定同位素特征是反映古气候与古环境的重要代用指标,其碳氧稳定同位素组成分别受土壤CO2中C同位素组成和大气水的O同位素控制。在一定深度的土壤中,土壤次生碳酸盐δ13C就主要受当地植物类型(C3植物和C4植物等)控制。土壤次生碳酸盐样预处理中剔除土壤中原生碳酸盐以及有机物污染尤为重要。土壤中次生碳酸盐C、O稳定同位素地球化学在土壤发生学、古气候恢复、古生态重建以及全球变化研究中应用日益广泛,但解译时可能受应用年代范围、成岩作用、原生和次生碳酸盐混杂、土壤碳酸盐多元发生等因素影响,其应用机理和范围还需进一步探讨。
Stable carbon and oxygen isotopes of pedogenic carbonates in soils provide a useful proxy indicator for inferring paleoclimatology and paleoclimate, and the composition of stable oxygen and carbon isotopes depend on the composition of oxygen isotope in meteoric water and the carbon isotopic composition in soil CO2 respectively. The soil CO2 is controlled by the mineralization of organic matters, the respiration of plant roots as well as atmosphere CO2. So in soils at certain depth, the δ13C value in pedogenic carbonates is determined by the local assemblage (e.g. C3 plant and C4 plant, etc.). The pretreatments to remove inherited carbonates and organic matters from pedogenic carbonates are particularly important. The geochemistry of stable carbon and oxygen isotopes of pedogenic carbonates has applied extensively in studies of discrimination of inherited carbonates from secondary carbonates, the reconstruction of paleohydrological features, paleoclimatology and paleoecology as well as global change. However, a few problems limit the application of the carbon and oxygen isotopic interpretation, e.g. the credibility of interpretation carbon and oxygen isotopic features relying on the date of pedogenic carbonates, the effect diagenesis on oxygen isotopic composition of buried paleosols, separating pedogenic carbonates from inherited carbonates for the comprehensive coalition and polygenesis of carbonates, etc. Nevertheless, for the boundary of C3/C4 plant ecotone can be inferred and the paleohydrological features and formation of paleosols may be guessed by use of stable carbon and oxygen isotopes of pedogenic carbonates other than analysis of pollen in lacustrine and marsh sediments, therefore, interpreting paleoenvironmental and paleoecological information will be applied intensively and extensively utilizing stable carbon and oxygen isotopes of pedogenic carbonates with the development of relevant branches of sciences.
出处
《地球科学进展》
CAS
CSCD
2003年第4期619-625,共7页
Advances in Earth Science
基金
国家重点基础研究发展规划项目子专题"全球变化背景下干旱河谷变化趋势与可持续发展研究"(编号:G1998040800)
教育部振兴行动计划项目"西南干旱河谷环境变化与生物适应性研究"(编号:008220 4127024)资助.
关键词
土壤次生碳酸盐
碳氧稳定同位素
古气候学
古生态学
Pedogenic carbonate
Stable isotopes of carbon and oxygen
Paleoclimatology
Paleoecology
