Sources, degradation, and thermal stability of organic matter in riparian soils along two major rivers of China

IF 5.4 1区农林科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Catena Pub Date : 2025-02-05 DOI:10.1016/j.catena.2025.108783

Le Wang , Peng Yao , Zheng Wang , Bin Zhao , Nan Wang , Xiwen Ye , Chao Gao

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引用次数: 0

Abstract

Riparian zones function as critical interfaces for the cycling of organic matter (OM) among terrestrial, aquatic, and oceanic environments. However, the characteristics of OM in riparian soils are not yet well understood. This study examined total organic carbon (TOC), stable carbon isotopic composition (δ¹³C), lignin phenols, and thermal gravimetric properties of OM in riparian soils along the Changjiang and Huanghe. The primary objective of this study was to enhance our understanding of the sources, distribution, degradation, and thermal stability of soil OM in these two major river systems in China. The TOC and lignin contents (Λ₈) in riparian soils along the Changjiang were found to be relatively higher than those in the Huanghe soils. Both river systems exhibited considerable spatial heterogeneity and seasonal variability. Analyses of δ¹³C, carbon-to-nitrogen (C/N) ratios, and Λ₈ indicate that the OM in the soils of both river systems primarily originates from terrestrial higher plants and aquatic vegetation, but modified by microbial processes. However, the lignin decay parameters and the ratios of TOC and Λ₈ to specific surface area (SSA) suggest that the degradation of OM in these soils is less extensive compared to that in riverine particulate matters and coastal sediments. This indicates a substantial loss of terrestrial OM and an addition of marine OM during the transport from soils to rivers and estuaries. The carbon reactivity index (CRI) of the soils, as determined by thermogravimetric analysis, ranged from 50% to 100%, which is generally lower than that observed in coastal sediments, suggesting that the OM in these soils exhibits greater thermal reactivity. This study addresses a critical knowledge gap regarding the lignin and thermal stability of OM in China’s terrestrial ecosystems, providing a foundation for a better understanding of the fate of terrestrial OM as it transitions from land to ocean.

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中国两条主要河流河岸土壤有机质的来源、退化和热稳定性

河岸带是陆地、水生和海洋环境中有机物循环的关键界面。然而，河岸土壤中有机质的特征尚未得到很好的了解。研究了长江黄河沿岸河岸土壤有机质的总有机碳（TOC）、稳定碳同位素组成（δ13C）、木质素酚类和热重特性。本研究的主要目的是提高我们对中国这两大水系土壤有机质的来源、分布、退化和热稳定性的认识。沿江岸岸土壤TOC和木质素含量（Λ8）相对高于黄河岸岸土壤。两河水系均表现出明显的空间异质性和季节变异性。δ13C、碳氮比（C/N）和Λ8的分析表明，两个水系土壤中的有机质主要来源于陆生高等植物和水生植被，但受到微生物作用的改变。然而，木质素衰变参数以及TOC和Λ8与比表面积（SSA）的比值表明，与河流颗粒物和海岸沉积物相比，这些土壤中OM的降解不那么广泛。这表明在从土壤到河流和河口的运输过程中，陆地有机质大量损失，海洋有机质增加。热重法测定的土壤碳反应指数（CRI）在50% ~ 100%之间，普遍低于沿海沉积物，表明有机质具有更强的热反应性。本研究解决了中国陆地生态系统中木质素和有机质热稳定性方面的关键知识空白，为更好地了解陆地有机质从陆地向海洋过渡的命运提供了基础。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Catena 环境科学-地球科学综合

CiteScore

10.50

自引率

9.70%

发文量

816

审稿时长

54 days

期刊介绍： Catena publishes papers describing original field and laboratory investigations and reviews on geoecology and landscape evolution with emphasis on interdisciplinary aspects of soil science, hydrology and geomorphology. It aims to disseminate new knowledge and foster better understanding of the physical environment, of evolutionary sequences that have resulted in past and current landscapes, and of the natural processes that are likely to determine the fate of our terrestrial environment. Papers within any one of the above topics are welcome provided they are of sufficiently wide interest and relevance.