Association between soil organic carbon and calcium in acidic grassland soils from Point Reyes National Seashore, CA

IF 3.9 3区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES

Biogeochemistry Pub Date : 2023-07-07 DOI:10.1007/s10533-023-01059-2

Mike C. Rowley, Peter S. Nico, Sharon E. Bone, Matthew A. Marcus, Elaine F. Pegoraro, Cristina Castanha, Kyounglim Kang, Amrita Bhattacharyya, Margaret S. Torn, Jasquelin Peña

{"title":"Association between soil organic carbon and calcium in acidic grassland soils from Point Reyes National Seashore, CA","authors":"Mike C. Rowley, Peter S. Nico, Sharon E. Bone, Matthew A. Marcus, Elaine F. Pegoraro, Cristina Castanha, Kyounglim Kang, Amrita Bhattacharyya, Margaret S. Torn, Jasquelin Peña","doi":"10.1007/s10533-023-01059-2","DOIUrl":null,"url":null,"abstract":"<div><p>Organo-mineral and organo-metal associations play an important role in the retention and accumulation of soil organic carbon (SOC). Recent studies have demonstrated a positive correlation between calcium (Ca) and SOC content in a range of soil types. However, most of these studies have focused on soils that contain calcium carbonate (pH?>?6). To assess the importance of Ca-SOC associations in lower pH soils, we investigated their physical and chemical interaction in the grassland soils of Point Reyes National Seashore (CA, USA) at a range of spatial scales. Multivariate analyses of our bulk soil characterisation dataset showed a strong correlation between exchangeable Ca (Ca<sub>Exch</sub>; 5–8.3 c.mol<sub>c</sub> kg<sup>?1</sup>) and SOC (0.6–4%) content. Additionally, linear combination fitting (LCF) of bulk Ca K-edge X-ray absorption near-edge structure (XANES) spectra revealed that Ca was predominantly associated with organic carbon across all samples. Scanning transmission X-ray microscopy near-edge X-ray absorption fine structure spectroscopy (STXM C/Ca NEXAFS) showed that Ca had a strong spatial correlation with C at the microscale. The STXM C NEXAFS K-edge spectra indicated that SOC had a higher abundance of aromatic/olefinic and phenolic C functional groups when associated with Ca, relative to C associated with Fe. In regions of high Ca-C association, the STXM C NEXAFS spectra were similar to the spectrum from lignin, with moderate changes in peak intensities and positions that are consistent with oxidative C transformation. Through this association, Ca thus seems to be preferentially associated with plant-like organic matter that has undergone some oxidative transformation, at depth in acidic grassland soils of California. Our study highlights the importance of Ca-SOC complexation in acidic grassland soils and provides a conceptual model of its contribution to SOC preservation, a research area that has previously been unexplored.</p></div>","PeriodicalId":8901,"journal":{"name":"Biogeochemistry","volume":"165 1","pages":"91 - 111"},"PeriodicalIF":3.9000,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10533-023-01059-2.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Biogeochemistry","FirstCategoryId":"93","ListUrlMain":"https://link.springer.com/article/10.1007/s10533-023-01059-2","RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENVIRONMENTAL SCIENCES","Score":null,"Total":0}

引用次数: 0

Abstract

Organo-mineral and organo-metal associations play an important role in the retention and accumulation of soil organic carbon (SOC). Recent studies have demonstrated a positive correlation between calcium (Ca) and SOC content in a range of soil types. However, most of these studies have focused on soils that contain calcium carbonate (pH?>?6). To assess the importance of Ca-SOC associations in lower pH soils, we investigated their physical and chemical interaction in the grassland soils of Point Reyes National Seashore (CA, USA) at a range of spatial scales. Multivariate analyses of our bulk soil characterisation dataset showed a strong correlation between exchangeable Ca (Ca_Exch; 5–8.3 c.mol_c kg^?1) and SOC (0.6–4%) content. Additionally, linear combination fitting (LCF) of bulk Ca K-edge X-ray absorption near-edge structure (XANES) spectra revealed that Ca was predominantly associated with organic carbon across all samples. Scanning transmission X-ray microscopy near-edge X-ray absorption fine structure spectroscopy (STXM C/Ca NEXAFS) showed that Ca had a strong spatial correlation with C at the microscale. The STXM C NEXAFS K-edge spectra indicated that SOC had a higher abundance of aromatic/olefinic and phenolic C functional groups when associated with Ca, relative to C associated with Fe. In regions of high Ca-C association, the STXM C NEXAFS spectra were similar to the spectrum from lignin, with moderate changes in peak intensities and positions that are consistent with oxidative C transformation. Through this association, Ca thus seems to be preferentially associated with plant-like organic matter that has undergone some oxidative transformation, at depth in acidic grassland soils of California. Our study highlights the importance of Ca-SOC complexation in acidic grassland soils and provides a conceptual model of its contribution to SOC preservation, a research area that has previously been unexplored.

Abstract Image

查看原文本刊更多论文

加州雷耶斯岬国家海岸酸性草地土壤有机碳和钙的关系

有机-矿物和有机-金属结合在土壤有机碳的保持和积累中起着重要作用。近年来的研究表明，在一系列土壤类型中，钙(Ca)与有机碳含量呈正相关。然而，这些研究大多集中在含有碳酸钙(pH?>?6)的土壤上。为了评估低pH土壤中CA - soc关联的重要性，我们在一定的空间尺度上研究了Reyes国家海岸(CA, USA)草地土壤中CA - soc的物理和化学相互作用。多变量分析表明，可交换性钙(CaExch;5-8.3 c.molc kg?1)和SOC(0.6-4%)含量。此外，体Ca k -边缘x射线吸收近边缘结构(XANES)光谱的线性组合拟合(LCF)表明，在所有样品中Ca主要与有机碳相关。扫描透射x射线显微镜近边缘x射线吸收精细结构光谱(STXM C/Ca NEXAFS)表明，Ca与C在微观尺度上具有很强的空间相关性。STXM C NEXAFS K-edge谱图表明，与Ca结合的有机碳具有更高的芳香/烯烃和酚C官能团丰度，相对于与Fe结合的C官能团。在高Ca-C结合区域，STXM C NEXAFS光谱与木质素的光谱相似，峰强度和位置的变化适中，与氧化C转化一致。通过这种关联，Ca似乎优先与在加州酸性草地土壤深处经历了一些氧化转化的植物样有机物相关。我们的研究强调了酸性草地土壤Ca-SOC络合的重要性，并提供了其对SOC保存贡献的概念模型，这是一个以前未被探索的研究领域。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Biogeochemistry 环境科学-地球科学综合

CiteScore

7.10

自引率

5.00%

发文量

112

审稿时长

3.2 months

期刊介绍： Biogeochemistry publishes original and synthetic papers dealing with biotic controls on the chemistry of the environment, or with the geochemical control of the structure and function of ecosystems. Cycles are considered, either of individual elements or of specific classes of natural or anthropogenic compounds in ecosystems. Particular emphasis is given to coupled interactions of element cycles. The journal spans from the molecular to global scales to elucidate the mechanisms driving patterns in biogeochemical cycles through space and time. Studies on both natural and artificial ecosystems are published when they contribute to a general understanding of biogeochemistry.