Direct molecular evidence for the degradation and mobility of black carbon in soils from ultrahigh-resolution mass spectral analysis of dissolved organic matter from a fire-impacted forest soil
Direct molecular evidence for the degradation and mobility of black carbon in soils from ultrahigh-resolution mass spectral analysis of dissolved organic matter from a fire-impacted forest soil
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DOI：
10.1016/j.orggeochem.2005.11.003
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发表时间：
2006-01-01
影响因子：
3
通讯作者：
Hatcher, PG
中科院分区：
文献类型：
--
作者：
Hockaday, WC;Grannas, AM;Hatcher, PG
用电喷雾离子化质谱法研究了在温带森林土壤中100多年来木炭颗粒自然降解所产生的水溶性产物的分子组成。可检测的产品是广泛取代含氧官能团的稠合芳环结构，表明炭黑的氧化和溶解发生在百年的时间尺度上。在森林土壤孔隙沃茨的溶解有机物（DOM）中也检测到许多相同的物种。我们介绍了碳归一化双键当量（DBE/C）的计算作为一个结构的决定因素，通过质谱分析得到的经验公式。阈值DBE/C值为0.7作为一个标准，用于识别与稠合芳环结构（CARS）的物种。从以前的研究中的高分辨质谱的比较表明，许多CARS直接从土壤中提取的BC具有相同的质量（1 ppm内）和经验公式的CARS检测火山灰土壤腐殖酸（HA）从日本，亚马逊河流域里奥内格罗DOM。水溶性稠环芳烃存在于内的相似性，并从火灾影响的土壤的地理和气候不同的生态系统的出口表明，本文报道的CARS是土壤中的黑碳降解的分子指纹。了解这些分子种类的生产机制，反应性和命运应该为BC降解和循环提供新的见解。在这个网站的土壤碳颗粒渗透的丝状微生物，这表明腐殖真菌可能是重要的土壤BC降解过程。(c)2005爱思唯尔有限公司保留所有权利。
The molecular composition of water-soluble products generated by the natural degradation of charcoal particles over a period of 100 years in a temperate forest soil has been investigated by ultrahigh resolution mass spectrometry with electrospray ionization. The detectable products are condensed aromatic ring structures extensively substituted with oxygen-containing functional groups, indicating that oxidation and dissolution of charcoal black carbon occurs on a centennial timescale. Many of the same species are also detected within the dissolved organic matter (DOM) of the forest's soil pore waters. We introduce the calculation of carbon normalized double bond equivalents (DBE/C) as a structural determinant for the empirical formulas obtained by mass spectral analysis. A threshold DBE/C value of 0.7 serves as a criterion for identifying species with condensed aromatic ring structures (CARS). A comparison with ultrahigh resolution mass spectra from previous studies shows that many of the CARS extracted directly from soil BC have the same mass (within 1 ppm) and empirical formulas as CARS detected in volcanic ash soil humic acid (HA) from Japan, and Amazonian Rio Negro DOM. The similarity of water-soluble condensed aromatics present within, and exported from fire-impacted soils of geographically and climatically disparate ecosystems indicates that the CARS reported herein are the molecular fingerprint of black carbon degradation in soils. Understanding the production mechanisms, reactivity, and fate of these molecular species should provide new insight to BC degradation and cycling. The soil charcoal particles at this site are infiltrated by filamentous microorganisms, suggesting that saprophytic fungi may be important to soil BC degradation processes. (c) 2005 Elsevier Ltd. All rights reserved.