Halogenated hydrocarbon formation in a moderately acidic salt lake in Western Australia - Role of abiotic and biotic processes
Halogenated hydrocarbon formation in a moderately acidic salt lake in Western Australia - Role of abiotic and biotic processes
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DOI：
10.1071/en14202
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发表时间：
2015-06
影响因子：
4.3
通讯作者：
A. Ruecker;P. Weigold;S. Behrens;M. Jochmann;X. L. O. Barajas;A. Kappler
中科院分区：
文献类型：
--
作者：
A. Ruecker;P. Weigold;S. Behrens;M. Jochmann;X. L. O. Barajas;A. Kappler
环境背景挥发性卤代有机化合物（VOX）会导致臭氧消耗和全球变暖。在这里，我们表明，在澳大利亚西部的酸性盐湖沉积物有助于这些化合物的全球自然排放，排放主要是生物起源。阐明VOX的主要源和汇是环境化学中的一项关键任务，因为它们的形成和降解对大气化学和地球气候产生重大影响。摘要挥发性有机卤素化合物（VOX）是已知的环境污染物，对平流层臭氧消耗有重要影响。从深海到森林土壤和南极洲的许多环境都显示了VOX的自然形成。最近，我们表明，VOX排放的pH中性盐湖在澳大利亚西部，他们主要是生物起源。在何种程度上，这种生物有机卤素形成在盐湖是pH值依赖性和VOX是否也形成在酸性条件下是未知的。因此，我们在受控实验室条件下，在生物和非生物（γ射线辐照）微观实验中量化了西澳大利亚州酸性盐湖（奥尔湖）的VOX排放。实验表明，生物卤化过程也发生在酸性条件下（pH值范围3.8-4.8），虽然排放量大约比pH值中性的湖泊沉积物低一个数量级（纳克/千克干沉积物范围）。检测到的物质包括溴化物质（如三溴甲烷）以及氯化化合物（如三氯甲烷）。在我们的微观世界中，乳酸盐和乙酸盐以及水铁矿的加入没有显示出对VOX形成的刺激。因此，铁代谢微生物的刺激及其对反应性铁物种形成的潜在影响并没有促进VOX排放，这表明所排放化合物的直接酶促形成。
Environmental context Volatile halogenated organic compounds (VOX) contribute to ozone depletion and global warming. Here we demonstrate that acidic salt lake sediments in Western Australia contribute to the global natural emission of these compounds and that the emissions are primarily of biotic origin. Elucidating major sources and sinks of VOX is a key task in environmental chemistry because their formation and degradation have major effects on atmospheric chemistry and thus earth climate. Abstract Volatile organohalogen compounds (VOX) are known environmental pollutants and contribute to stratospheric ozone depletion. Natural formation of VOX has been shown for many environments from the deep sea to forest soils and Antarctica. Recently, we showed that VOX are emitted from pH-neutral salt lakes in Western Australia and that they are mainly of biotic origin. To which extent this biotic organohalogen formation in salt lakes is pH-dependent and whether VOX are also formed under acidic conditions are unknown. Therefore, we quantified VOX emissions from an acidic salt lake in Western Australia (Lake Orr) in biotic and abiotic (γ ray-irradiated) microcosm experiments under controlled laboratory conditions. The experiments revealed that biotic halogenation processes also occurred under acidic conditions (pH range 3.8–4.8), though the emissions were approximately one order of magnitude lower (nanogram per kilogram dry sediment range) than from pH-neutral lake sediments. Among the detected substances were brominated, e.g. tribromomethane, as well as chlorinated compounds (e.g. trichloromethane). The addition of lactate and acetate, and ferrihydrite showed no stimulation of VOX formation in our microcosms. Hence, the stimulation of Fe-metabolising microorganisms and their potential effect on the formation of reactive Fe species did not promote VOX emissions, suggesting a direct enzymatic formation of the emitted compounds.