阿根廷应用和环境地球科学研究所Romina, Sanci课题组，使用同位素地球化学方法来研究阿根廷Chaco-Pampean平原部分土壤二氧化碳动力学的过程。这一研究成果发表在2024年3月8日出版的国际学术期刊《地球化学学报》上。

本研究评估了Chaco Pampean平原（阿根廷）不同土壤性质和环境条件(PL和PA单位)下，未受干扰土壤的CO₂通量以及植被、有机质和土壤气体的¹³C/¹²C比值。各层土壤有机质分解伴随着总有机碳δ¹³C (δ¹³C-TOC)值随土层深度的增加而增加。上层土壤剖面δ¹³C-TOC约ca.0-15 cm为该地区的植物群落约-33到-29‰，而δ¹³C-TOC在层位A以下变化更大，至约-24‰。土壤δ¹³C-TOC与土壤δ¹³C-CO₂在较深约50-60cm土层具有相似的值(约-24-26‰)。受扩散过程的影响，表层δ¹³C-TOC和δ¹³C-CO₂的差异较大(可达-4‰)。

由于大气CO₂渗透到土壤空气中，PL和PA单元的A层(约0-20 cm)中的δ¹³C-CO₂值最富集(约-15-17‰)。来源（大气δ¹³C-CO₂和土壤CO₂）之间的简单双组分混合模型证实了这一过程。从同位素上看，CO₂通量反映了C3植物的生物降解(源)、扩散迁移和CO₂交换(大气/土壤)。土壤含水量是扩散过程和地表CO₂排放量(12-60 g·m^-2·d^-1)的决定性因素。利用充气孔隙度参数和土壤氡梯度模型估算的CO₂扩散系数证实了这一情况。

据悉，二氧化碳地表排放量的幅度和空间变异性，以及涉及土壤向大气释放二氧化碳的过程是在气候变化背景下的相关问题。

附：英文原文

Title: Processes involving soil CO₂ dynamic in a sector of Chaco-Pampean plain, Argentina: An isotope geochemical approach

Author: Romina, Sanci, Hctor, Panarello

Issue&Volume: 2024-03-08

Abstract: The magnitude and spatial variability of CO₂ surface emissions and processes involving CO₂ released to the atmosphere from the soils are relevant issues in the context of climate change. This work evaluated CO₂ fluxes and ¹³C/¹²C ratio of vegetation, organic matter, and soil gases from no disturbed soils of Chaco Pampean Plain (Argentina) with different soil properties and environmental conditions (PL and PA units). Soil organic decomposition from individual layers was accompanied by δ¹³C of total organic carbon (δ¹³C-TOC) values more enriched to depth. δ¹³C-TOC values in the upper soil profile ~ ca. 0–15 cm were like the plant community of this area (~-33 to -29 ‰) while δ¹³C-TOC varied stronger bellow horizon A, till ~ -24‰. Both δ¹³C-TOC and soil ¹³C-CO₂ were similar (~-24 to 26 ‰) at deeper horizons (~ 50–60 cm). Toward the superficial layers, δ¹³C-TOC and δ¹³C-CO₂ showed more differences (till ~ 4 ‰), due influence of the diffusion process. Horizon A layer (~ 0–20 cm) from both PL and PA units contained the most enriched δ¹³C-CO₂ values (~-15–17 ‰) because atmospheric CO₂ permeated the soil air. A simple two-component mixing model between sources (atmospheric δ¹³C-CO₂ and soil CO₂) confirmed that process. Isotopically, CO₂ fluxes reflected the biodegradation of C3 plants (source), diffusive transport, and CO₂ exchange (atmosphere/soil). Soil moisture content appeared as a determining factor in the diffusion process and the magnitude of CO₂ surface emissions (12–60 g·m^-2·d^-1). That condition was confirmed by CO₂ diffusion coefficients estimated by air-filled porosity parameters and soil radon gradient model.

DOI: 10.1007/s11631-024-00678-2

Source: https://link.springer.com/article/10.1007/s11631-024-00678-2