Sarah Z. Rosengard, Jose Mauro S. Moura, Robert G. M. Spencer, Carl Johnson, Ann McNichol, Brenna Boehman, Valier Galy
{"title":"亚马逊河干流中颗粒有机碳的热反应性和分子多样性","authors":"Sarah Z. Rosengard, Jose Mauro S. Moura, Robert G. M. Spencer, Carl Johnson, Ann McNichol, Brenna Boehman, Valier Galy","doi":"10.1029/2024JG008660","DOIUrl":null,"url":null,"abstract":"<p>The Amazon River mobilizes one of the largest fluxes of particulate organic carbon (POC) from land to coastal ocean sediments, playing an important role in the long-term sequestration of biospheric organic carbon in the ocean. Ramped oxidation (RPO) analyses of suspended sediments collected from the Amazon River mainstem, Solimões River, Madeira River, and Tapajós River presented an opportunity to parse riverine POC by thermal reactivity, extract the activation energy distributions of specific biomolecular pools in these samples, and characterize the molecular diversity of POC across the floodplain. The thermal reactivity data imply that POC from the Amazon River basin spans a wide but relatively homogenous activation energy range across samples, suggesting that the degradation history of the organic carbon comprising riverine suspended particles is relatively constant across depths within the mainstem and different tributary locations. Coupling activation energy distributions to stable and radiocarbon isotopic analyses shows that ca. 85% of mainstem POC derives from a range of partially degraded terrestrial sources, likely organic matter from mineral soil horizons, and that a similar range of soil sources influences the biomolecular diversity in tributary samples. In agreement with earlier assessments, ca. 10% of the riverine POC flux is fresh vegetation and up to 5% of it is petrogenic organic matter. Expanded RPO analyses of samples across the Amazon river-to-ocean continuum would provide an opportunity to track the fate of these different organic matter pools downstream that is uniquely different from, but complementary to, past compound-specific and bulk analyses of riverine POC.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 6","pages":""},"PeriodicalIF":3.5000,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008660","citationCount":"0","resultStr":"{\"title\":\"The Thermal Reactivity and Molecular Diversity of Particulate Organic Carbon in the Amazon River Mainstem\",\"authors\":\"Sarah Z. Rosengard, Jose Mauro S. Moura, Robert G. M. Spencer, Carl Johnson, Ann McNichol, Brenna Boehman, Valier Galy\",\"doi\":\"10.1029/2024JG008660\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>The Amazon River mobilizes one of the largest fluxes of particulate organic carbon (POC) from land to coastal ocean sediments, playing an important role in the long-term sequestration of biospheric organic carbon in the ocean. Ramped oxidation (RPO) analyses of suspended sediments collected from the Amazon River mainstem, Solimões River, Madeira River, and Tapajós River presented an opportunity to parse riverine POC by thermal reactivity, extract the activation energy distributions of specific biomolecular pools in these samples, and characterize the molecular diversity of POC across the floodplain. The thermal reactivity data imply that POC from the Amazon River basin spans a wide but relatively homogenous activation energy range across samples, suggesting that the degradation history of the organic carbon comprising riverine suspended particles is relatively constant across depths within the mainstem and different tributary locations. Coupling activation energy distributions to stable and radiocarbon isotopic analyses shows that ca. 85% of mainstem POC derives from a range of partially degraded terrestrial sources, likely organic matter from mineral soil horizons, and that a similar range of soil sources influences the biomolecular diversity in tributary samples. In agreement with earlier assessments, ca. 10% of the riverine POC flux is fresh vegetation and up to 5% of it is petrogenic organic matter. Expanded RPO analyses of samples across the Amazon river-to-ocean continuum would provide an opportunity to track the fate of these different organic matter pools downstream that is uniquely different from, but complementary to, past compound-specific and bulk analyses of riverine POC.</p>\",\"PeriodicalId\":16003,\"journal\":{\"name\":\"Journal of Geophysical Research: Biogeosciences\",\"volume\":\"130 6\",\"pages\":\"\"},\"PeriodicalIF\":3.5000,\"publicationDate\":\"2025-06-18\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008660\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Geophysical Research: Biogeosciences\",\"FirstCategoryId\":\"93\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1029/2024JG008660\",\"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}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Geophysical Research: Biogeosciences","FirstCategoryId":"93","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1029/2024JG008660","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}
The Thermal Reactivity and Molecular Diversity of Particulate Organic Carbon in the Amazon River Mainstem
The Amazon River mobilizes one of the largest fluxes of particulate organic carbon (POC) from land to coastal ocean sediments, playing an important role in the long-term sequestration of biospheric organic carbon in the ocean. Ramped oxidation (RPO) analyses of suspended sediments collected from the Amazon River mainstem, Solimões River, Madeira River, and Tapajós River presented an opportunity to parse riverine POC by thermal reactivity, extract the activation energy distributions of specific biomolecular pools in these samples, and characterize the molecular diversity of POC across the floodplain. The thermal reactivity data imply that POC from the Amazon River basin spans a wide but relatively homogenous activation energy range across samples, suggesting that the degradation history of the organic carbon comprising riverine suspended particles is relatively constant across depths within the mainstem and different tributary locations. Coupling activation energy distributions to stable and radiocarbon isotopic analyses shows that ca. 85% of mainstem POC derives from a range of partially degraded terrestrial sources, likely organic matter from mineral soil horizons, and that a similar range of soil sources influences the biomolecular diversity in tributary samples. In agreement with earlier assessments, ca. 10% of the riverine POC flux is fresh vegetation and up to 5% of it is petrogenic organic matter. Expanded RPO analyses of samples across the Amazon river-to-ocean continuum would provide an opportunity to track the fate of these different organic matter pools downstream that is uniquely different from, but complementary to, past compound-specific and bulk analyses of riverine POC.
期刊介绍:
JGR-Biogeosciences focuses on biogeosciences of the Earth system in the past, present, and future and the extension of this research to planetary studies. The emerging field of biogeosciences spans the intellectual interface between biology and the geosciences and attempts to understand the functions of the Earth system across multiple spatial and temporal scales. Studies in biogeosciences may use multiple lines of evidence drawn from diverse fields to gain a holistic understanding of terrestrial, freshwater, and marine ecosystems and extreme environments. Specific topics within the scope of the section include process-based theoretical, experimental, and field studies of biogeochemistry, biogeophysics, atmosphere-, land-, and ocean-ecosystem interactions, biomineralization, life in extreme environments, astrobiology, microbial processes, geomicrobiology, and evolutionary geobiology