Composition and photo-reactivity of organic matter from permafrost soils and surface waters in interior Alaska.,Environmental Science: Processes & Impacts

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Composition and photo-reactivity of organic matter from permafrost soils and surface waters in interior Alaska.
Environmental Science: Processes & Impacts ( IF 4.3 ) Pub Date : 2020-06-22 , DOI: 10.1039/d0em00097c
Kristin R Gagné ₁ , Sara C Ewers , Carl J Murphy , Ronald Daanen , Katey Walter Anthony , Jennifer J Guerard

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Yedoma permafrost soils are especially susceptible to abrupt thaw due to their exceptional thickness and high ice content. Compared to other mineral soils, yedoma has a high organic carbon content, which has shown to be particularly biolabile. The organic carbon in these deposits needs to be characterised to provide an identification toolkit for detecting and monitoring the thaw, mobilisation and mineralisation of yedoma permafrost. This study characterised organic carbon isolates from thermokarst lakes (either receiving inputs from thaw of original yedoma or refrozen-thermokarst deposits, or lacking recent thaw) during winter and summer seasons within the Goldstream Creek watershed, a discontinuous permafrost watershed in interior Alaska, to identify the extent to which thermokarst-lake environments are impacted by degradation of yedoma permafrost. Waters from lakes of varied age and thermokarst activity, as well as active layer and undisturbed yedoma permafrost soils were isolated and characterised by functional group abundance (multiCP-MAS ¹³C and SPR-W5-WATERGATE ¹H NMR), absorbance and fluorescence, and photobleaching ability. DOM isolated from winter and summer seasons revealed differing composition and photoreactivity, suggesting varied active layer and permafrost influence under differing ground water flow regimes. Water extractable organic matter isolates from permafrost leachates revealed variation in terms of photoreactivity and photolability, with the youngest sampled permafrost isolate being the most photoreactive and photolabile. As temperatures increase, release of permafrost organic matter is inevitable. Obtaining a holistic understanding of DOM composition and photoreactivity will allow for a better prediction of permafrost thaw impacts in the coming decades.

中文翻译：

来自阿拉斯加内部多年冻土和地表水的有机物的组成和光反应性。

Yedoma多年冻土由于其异常的厚度和高的冰含量特别容易突然解冻。与其他矿质土壤相比，稻草具有较高的有机碳含量，已显示特别不稳定。需要对这些矿床中的有机碳进行特征化处理，以提供鉴定工具包，以检测和监测多年生冻土的融化，动员和矿化。这项研究的特征是，在冬季和夏季，在Goldstream Creek流域（阿拉斯加内部的不连续多年冻土流域，来确定喀斯特湖环境受到永冻土的降解的影响程度。分离并鉴定了具有不同年龄和热岩溶活动的湖泊中的水以及活动层和不受干扰的多年生冻土，并通过官能团丰度对其进行了表征（multiCP-MAS¹³ C和SPR-W5-WATERGATE¹ H NMR），吸光度和荧光以及光漂白能力。从冬季和夏季分离出的DOM显示出不同的组成和光反应性，表明在不同的地下水流方案下，不同的活性层和多年冻土影响。从多年冻土渗滤液中提取的水可提取的有机物分离物显示出光反应性和光稳定性方面的变化，最年轻的永冻土采样样品具有最高的光反应性和光不稳定性。随着温度升高，永久冻土有机物的释放是不可避免的。全面了解DOM的组成和光反应性，将可以更好地预测未来几十年的冻土融化影响。

更新日期：2020-07-23

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