Dissolved organic matter molecular composition controls potential biodegradability

IF 2.6 3区 地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS
Meiling Man, Myrna J. Simpson
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引用次数: 0

Abstract

Dissolved organic matter (DOM) is a heterogenous mixture of plant- and microbial-derived compounds at various stages of decomposition. However, there is a lack of detailed information about the biodegradability of DOM from different terrestrial sources that have varying molecular compositions. To circumvent this, incubation experiments were conducted for two months using DOM isolated from three different terrestrial sources: forest soil, peat and leonardite, all with distinct extents of diagenesis. The dissolved organic carbon (DOC), total dissolved nitrogen (TDN) contents, pH, and headspace CO2 production were measured. DOM composition was monitored using solution-state 1H nuclear magnetic resonance (NMR) and ultraviolet–visible (UV–VIS) analyses. To further understand microbial responses, microbial biomass and community composition was analyzed with phospholipid fatty acid (PLFA). DOM isolated from forest soil and peat demonstrated high biodegradability and decreased DOC concentrations, higher CO2 production rates and higher microbial biomass over the course of incubation. Forest soil-derived DOM composition had decreased aliphatic, and carbohydrate and peptide components in the early and late stages, respectively. Peat-derived DOM exhibited lower carbohydrate and peptide concentrations and higher carboxyl-rich alicyclic molecules (CRAM). In contrast, CRAM and aromatic enriched leonardite-derived DOM had low CO2 production and microbial biomass, and no major changes in DOM chemical composition, suggesting limited biodegradability. Further, CO2 production, microbial biomass, and DOM molecular weight and degradation indices were positively correlated with carbohydrates and peptides, and inversely related to CRAM and aromatic components. Overall, these results corroborated distinct biogeochemical dynamics with varied DOM molecular composition, and highlight that DOM enriched in bio-recalcitrant components limited microbial processing, and exhibited high geochemical stability.
溶解有机物的分子组成控制着潜在的生物降解性
溶解有机物(DOM)是植物和微生物衍生化合物在不同分解阶段的异质混合物。然而,缺乏关于不同陆地来源的DOM的生物降解性的详细信息,这些来源具有不同的分子组成。为了避免这种情况,利用从三种不同陆地来源分离的DOM进行了为期两个月的孵化实验:森林土壤、泥炭和褐铁矿,它们都具有不同程度的成岩作用。测定了溶解有机碳(DOC)、总溶解氮(TDN)含量、pH和顶空CO2产量。采用溶液态1H核磁共振(NMR)和紫外-可见(UV-VIS)分析监测DOM的组成。为了进一步了解微生物的反应,用磷脂脂肪酸(PLFA)分析了微生物生物量和群落组成。在培养过程中,从森林土壤和泥炭中分离出的DOM具有较高的生物可降解性,DOC浓度降低,二氧化碳产量增加,微生物生物量增加。森林土壤DOM组成在早期和后期分别减少脂肪、碳水化合物和多肽成分。泥炭衍生的DOM碳水化合物和多肽浓度较低,富含羧基脂环分子(CRAM)较高。相比之下,CRAM和芳香族富龙纳迪石衍生的DOM的CO2产量和微生物量都很低,DOM的化学成分没有发生大的变化,表明其生物降解性有限。CO2产量、微生物生物量、DOM分子量和降解指标与碳水化合物和多肽呈正相关,与CRAM和芳香成分呈负相关。总体而言,这些结果证实了不同DOM分子组成的不同生物地球化学动力学,并强调了富含生物顽固性成分的DOM限制了微生物的处理,并表现出较高的地球化学稳定性。
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来源期刊
Organic Geochemistry
Organic Geochemistry 地学-地球化学与地球物理
CiteScore
5.50
自引率
6.70%
发文量
100
审稿时长
61 days
期刊介绍: Organic Geochemistry serves as the only dedicated medium for the publication of peer-reviewed research on all phases of geochemistry in which organic compounds play a major role. The Editors welcome contributions covering a wide spectrum of subjects in the geosciences broadly based on organic chemistry (including molecular and isotopic geochemistry), and involving geology, biogeochemistry, environmental geochemistry, chemical oceanography and hydrology. The scope of the journal includes research involving petroleum (including natural gas), coal, organic matter in the aqueous environment and recent sediments, organic-rich rocks and soils and the role of organics in the geochemical cycling of the elements. Sedimentological, paleontological and organic petrographic studies will also be considered for publication, provided that they are geochemically oriented. Papers cover the full range of research activities in organic geochemistry, and include comprehensive review articles, technical communications, discussion/reply correspondence and short technical notes. Peer-reviews organised through three Chief Editors and a staff of Associate Editors, are conducted by well known, respected scientists from academia, government and industry. The journal also publishes reviews of books, announcements of important conferences and meetings and other matters of direct interest to the organic geochemical community.
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