Plant wax n-alkane and n-alkanoic acid abundances, carbon and hydrogen isotopic compositions in eleven soil profiles along a Serengeti transect

Soil profiles were collected along a transect across the Serengeti ecosystem, in Tanzania from 2-3S and 34-35.5E, 1153 to 1677 m above sea level and 0 to 1.6 m soil depth. The samples are modern soils and the temporal span of the soil depth profiles is unconstrained, likely centuries to millennia. The survey is intended to observe C4 grassland vegetation signals in the carbon isotopic composition of soil bulk organics and n-alkanes and n-alkanoic acids that are commonly used as proxies for past vegetation. These modern calibrations can inform reconstructions of East African paleoenvironments using the same proxies in geological archives. Bulk organic data include total organic carbon concentration and carbon isotopic composition obtained by elemental analyzer cavity ring down spectroscopy. Compound specific data are reported for the n-alkanes and n-alkanoic acids; data for each homologous series include concentrations obtained by gas chromatography flame ionization detection, as well as carbon and hydrogen isotopic composition obtained by gas chromatography isotope ratio mass spectrometry, performed 2018-2019 at the University of Southern California. For more information, please consult the associated manuscript on the organics: Zhang, et al. (2021). A publication on carbonates in the same soil profiles can be found at: Beverly et al. (2021). That study includes stable carbon isotopic data on soil carbonates, available from http://doi.org/10.5281/zenodo.4919027.

本数据集沿坦桑尼亚塞伦盖蒂（Serengeti）生态系统的样带采集了土壤剖面，采样区域位于南纬2°~3°、东经34°~35.5°，海拔1153~1677米，土壤采样深度为0~1.6米。所采样品均为现代土壤，其深度剖面的时间跨度未受限定，推测为百年至千年尺度。本采样调查旨在探究土壤块状有机质（bulk organics）、正构烷烃（n-alkanes）与正构烷酸（n-alkanoic acids）的碳同位素组成中的C4草原植被信号——此类组分常被用作古植被重建的代用指标。上述现代校准数据可为利用相同代用指标分析地质记录中的东非古环境提供科学参考。块状有机质数据涵盖总有机碳浓度及碳同位素组成，测定采用元素分析仪-腔环衰荡光谱法（elemental analyzer cavity ring down spectroscopy）。针对正构烷烃与正构烷酸的化合物特异性分析数据已公开，每一同系物的相关数据包括：气相色谱-火焰离子化检测器（gas chromatography flame ionization detection）测得的浓度，以及气相色谱-同位素比质谱法（gas chromatography isotope ratio mass spectrometry）测得的碳、氢同位素组成；相关分析工作于2018-2019年在美国南加州大学（University of Southern California）完成。更多详细信息可参阅相关有机质研究论文：Zhang等（2021）。针对同一土壤剖面中碳酸盐组分的研究成果可参见Beverly等（2021），该研究包含土壤碳酸盐的稳定碳同位素数据，可从http://doi.org/10.5281/zenodo.4919027获取。