The impact of burning on the structure and mineral composition of bat guano

IF 1.3 4区 地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY
J. Lundberg, D. McFarlane
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引用次数: 4

Abstract

Here we addressed the question of whether burning of guano produces a characteristic suite of morphological changes and/or unique mineralogical products. The changes observed in our experimental burning of guano (both fresh and decayed) included colour change (blackening), grain size and morphological change (grain size generally reduced, morphology rendered generally less distinct), alteration of minerals by dehydration (e.g., gypsum to anhydrite, brushite to whitlockite), and production of new minerals or compounds (e.g., augelite, bayerite, giniite, graphite, oldhamite, strontium apatite, tridymite). The key morphological feature we found that may be diagnostic of burning was severe damage to crystals from rapid dehydration (cracks and striations, leading to eventual fragmentation). The key mineralogical feature we found was production of graphite. The high temperature exotic minerals that were produced (giniite, augelite, tridymite, oldhamite) were all found not to be high temperature obligate. Evidence gleaned from the literature suggests that a great number of the minerals associated with high temperatures can also be synthesized in low temperature settings such as weathering or microbial action (exemplified in the extremely complex biology and biochemistry of decaying guano). While the presence of any one of these minerals is not diagnostic of fire, it could be argued that the suite taken as a whole is moderately strong evidence for burning. In future studies, the chemistry of carbon aromaticity may prove to be the best diagnostic test for pyrolysis. A survey of the conditions under which documented spontaneous ignition occurs leads us to conclude that spontaneous ignition of guano inside a cave is an extremely unlikely event, and any suggestion/assertion to this effect should be rigorously supported.
燃烧对蝙蝠粪结构和矿物组成的影响
在这里,我们讨论了鸟粪燃烧是否会产生一系列特征性的形态变化和/或独特的矿物学产物的问题。在我们对鸟粪(新鲜和腐烂的)的实验燃烧中观察到的变化包括颜色变化(变黑)、粒度和形态变化(粒度通常减小,形态通常不那么明显)、脱水引起的矿物变化(例如,石膏变硬石膏、刷石变白榴石),以及生产新的矿物或化合物(例如,辉石、bayerite、giniite、石墨、oldhamite、锶磷灰石、tridymite)。我们发现的可能诊断燃烧的关键形态特征是快速脱水对晶体的严重损伤(裂纹和条纹,导致最终碎裂)。我们发现的主要矿物学特征是石墨的生产。所产生的高温外来矿物(白榴石、辉石、鳞辉石、奥氏体)均不属于高温专性矿物。从文献中收集到的证据表明,大量与高温相关的矿物也可以在低温环境中合成,如风化或微生物作用(腐烂鸟粪极其复杂的生物学和生物化学就是一个例子)。虽然这些矿物中任何一种的存在都不能诊断为火灾,但可以说,从整体上看,这套矿物是燃烧的有力证据。在未来的研究中,碳芳香性化学可能被证明是热解的最佳诊断测试。对记录在案的自燃发生条件的调查使我们得出结论,洞穴内鸟粪自燃是极不可能发生的事件,任何对此的建议/断言都应得到严格支持。
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来源期刊
International Journal of Speleology
International Journal of Speleology 地学-地球科学综合
CiteScore
3.10
自引率
23.10%
发文量
12
审稿时长
>12 weeks
期刊介绍: The International Journal of Speleology has the aim to get cave and karst science known to an increasing number of scientists and scholars. The journal therefore offers the opportunity to all scientists working in and on karst to publish their original research articles or their review papers in an open access, high quality peer reviewed scientific journal at no cost. The journal offers the authors online first, open access, a free PDF of their article, and a wide range of abstracting and indexing services.
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