Anthropogenic landcover impacts fluvial dissolved organic matter composition in the Upper Mississippi River Basin
Anthropogenic landcover impacts fluvial dissolved organic matter composition in the Upper Mississippi River Basin
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DOI：
10.1007/s10533-021-00852-1
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发表时间：
2021-10
期刊：
影响因子：
4
通讯作者：
D. Vaughn;A. Kellerman;K. Wickland;R. Striegl;D. Podgorski;J. Hawkings;J. Nienhuis;M. Dornblaser
中科院分区：
文献类型：
--
作者：
D. Vaughn;A. Kellerman;K. Wickland;R. Striegl;D. Podgorski;J. Hawkings;J. Nienhuis;M. Dornblaser
土地覆盖的变化改变了自然碳循环；然而，大多数土地覆盖研究集中于森林向农业或城市的转变，很少两者兼顾。我们研究了上游密西西比河流域低阶溪流和河流中溶解有机碳（DOC）浓度和溶解有机物质（DOM）分子组成的差异，这些河流排水于三种主要土地覆盖（森林、农业和城市）之一。流经森林和城市地表的河流具有更高的DOC浓度，可能是由碳源、微生物加工和土壤扰动的差异驱动的。使用傅里叶变换-离子回旋共振质谱法，24%的指定分子式在所有土地覆盖中都是常见的。农业和城市河流中N-、S-杂原子式（CHON、CHOS、CHONS）的相对丰度更高，农业河流DOM含有更多含N的公式，而城市河流DOM含有更多含S的公式。农业和城市河流DOM中较高的N-、S-杂原子配方丰度，以及脂肪族、N-脂肪族、高度不饱和和酚类（低O/C）化合物类别的富集，可能是由与农业和城市影响相关的人为输入、本地生产和微生物处理增加造成的。森林河流DOM中N-、S-杂原子式的丰度降低，以及浓缩芳烃、多酚类和高度不饱和酚类（高O/C）化合物类别的富集，可能反映了周围富有机森林土壤和植被的更大贡献。总体而言，从森林到农业的土地覆盖变化降低了DOC浓度，而从森林到农业或城市的变化增加了原生的、可能更具生物稳定性的DOM贡献，并对河流生物地球化学循环产生影响。
Landcover changes have altered the natural carbon cycle; however, most landcover studies focus on either forest conversion to agriculture or urban, rarely both. We present differences in dissolved organic carbon (DOC) concentrations and dissolved organic matter (DOM) molecular composition within Upper Mississippi River Basin low order streams and rivers draining one of three dominant landcovers (forest, agriculture, and urban). Streams draining forest and urban landcovers have greater DOC concentrations, likely driven by differences in carbon sourcing, microbial processing, and soil disturbance. Using Fourier transform-ion cyclotron resonance mass spectrometry, 24% of assigned molecular formulae are common across all landcovers. Relative abundances of N-,S- heteroatomic formulae (CHON, CHOS, CHONS) are higher for agricultural and urban streams, with agricultural stream DOM having more N-containing formulae compared to urban stream DOM, which has more S-containing formulae. Higher N-,S- heteroatomic formulae abundance, along with enrichment in aliphatic, N-aliphatic, and highly unsaturated and phenolic (low O/C) compound categories within agricultural and urban stream DOM are likely to result from increased anthropogenic inputs, autochthonous production, and microbial processing associated with agricultural and urban impacts. Reduced N-,S- heteroatomic formulae abundances in forested stream DOM, along with enrichments in condensed aromatics, polyphenolics, and highly unsaturated phenolic (high O/C) compound categories, likely reflect greater contributions from surrounding organic-rich forest soil and vegetation. Overall, landcover change from forested to agriculture lowers DOC concentrations and changes from forested to agriculture or urban increases autochthonous, and presumably more biolabile, DOM contributions with ramifications for stream biogeochemical cycling.