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Use of optical properties for evaluating the presence of pyrogenic organic matter in thermally altered soil leachates.
Environmental Science: Processes & Impacts ( IF 4.3 ) Pub Date : 2020-04-29 , DOI: 10.1039/c9em00413k
Garrett McKay 1 , Amanda K Hohner , Fernando L Rosario-Ortiz
Affiliation  

The increased frequency and severity of wildfires in forested watersheds has the potential to significantly impact the quantity and quality of water extractable organic matter (WEOM) exported from these ecosystems. This study examined the optical properties of WEOM from laboratory heated soil in order to understand physicochemical changes occurring in the organic matter as a result of heating, as well as test the usefulness of optical parameters for assessing the presence of pyrogenic organic matter. WEOM absorbance and fluorescence spectral shape and intensity varied systematically as a function of soil heating temperature. Notably, absorbance and fluorescence intensity, specific ultraviolet absorbance, apparent fluorescence quantum yield, specific fluorescence emission intensity, and maximum fluorescence emission wavelength exhibited consistent changes with heating temperature and indicated that WEOM in heated soil leachates was lower in molecular weight and more aromatic than in unheated samples. The lower molecular weight in heated soil WEOM was corroborated with size-exclusion chromatography measurements. This work increases the understanding of the molecular changes occurring in WEOM as a result of wildfire and indicates that optical measurements (i.e., absorbance and fluorescence) could be used for watershed monitoring of post-fire pyrogenic organic matter.

中文翻译:

利用光学性质评估热蚀土壤渗滤液中热解有机质的存在。

森林流域野火的频率和严重性增加,可能会严重影响从这些生态系统输出的可提取水的有机物(WEOM)的数量和质量。这项研究检查了实验室加热土壤中WEOM的光学性质,以了解加热导致有机物发生的物理化学变化,并测试光学参数对评估热解有机物的有效性。WEOM吸光度和荧光光谱的形状和强度随着土壤加热温度的变化而系统地变化。值得注意的是,吸光度和荧光强度,比紫外线吸收率,表观荧光量子产率,比荧光发射强度,最大荧光发射波长随加热温度呈现出一致的变化,表明加热的土壤渗滤液中的WEOM分子量比未加热的样品低,且芳香度更高。用尺寸排阻色谱法证实了加热土壤WEOM中的较低分子量。这项工作增加了对野火导致WEOM中发生的分子变化的理解,并表明光学测量(即吸光度和荧光)可用于分水岭监测火后热源有机物。用尺寸排阻色谱法证实了加热土壤WEOM中的较低分子量。这项工作增加了对野火导致WEOM中发生的分子变化的理解,并表明光学测量(即吸光度和荧光)可用于火后热源有机物的分水岭监测。用尺寸排阻色谱法证实了加热土壤WEOM中的较低分子量。这项工作增加了对野火导致WEOM中发生的分子变化的理解,并表明光学测量(即吸光度和荧光)可用于分水岭监测火后热源有机物。
更新日期:2020-02-11
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