Polycyclic Aromatic Hydrocarbons in tropical Australian stalagmites: a framework for reconstructing paleofire activity - Research data

We investigate the possibility to use polycyclic aromatic hydrocarbons in stalagmites as proxies for paleofires at KNI-51, a shallow cave located in tropical Western Australia, where bushfire is a regular occurrence.
In order to test links between the stalagmite PAHs and fire above the cave, we performed a series of experiments using PAH distributions in stalagmite aragonite, sediment from the cave and overlying soil. In addition, the possibility of surface contamination was evaluated by measuring PAH abundances and distributions in sequential digestions. PAHs were measured in soils above the cave, in sediments from the stalagmite chamber floor as possible sources of these organic compounds, and at near annual resolution in three aragonite stalagmites to evaluate the degree of deposition and conservation. Signal replication of PAHs was also tested in two coeval stalagmites.
The results support the hypothesis that PAHs in KNI-51 stalagmite carbonate reflect paleofire activity within 3 km of the cave, and thus that stalagmites can serve as an important new high resolution proxy for landscape-scale fire activity. Given that karst is present in many fire-prone environments, and that stalagmites can be precisely dated and may grow continuously for millennia, the potential utility of a stalagmite-based paleofire proxy is high.

本研究旨在探讨在热带西澳大利亚的KNI-51浅洞（该洞位于常发生灌木丛火灾的地区）的钟乳石中，使用多环芳烃作为古火灾的替代指标的可能性。为了检验钟乳石中多环芳烃与洞穴上方火灾之间的联系，我们进行了一系列实验，这些实验涉及钟乳石方解石中的多环芳烃分布、洞穴沉积物以及上层土壤。此外，通过测量逐级消化过程中的多环芳烃丰度和分布，评估了表面污染的可能性。在洞穴上方的土壤中、钟乳石室地板的沉积物中（作为这些有机化合物的可能来源）以及三个方解石钟乳石中（以接近年度的分辨率）测量了多环芳烃，以评估沉积和保存的程度。还在两个同期钟乳石中测试了多环芳烃的信号复制。研究结果支持了以下假设：KNI-51钟乳石碳酸盐中的多环芳烃反映了洞穴周围3公里范围内的古火灾活动，因此钟乳石可以作为一种重要的、高分辨率的新景观尺度火灾活动替代指标。鉴于喀斯特地貌在许多易燃环境中普遍存在，且钟乳石可以精确定年并可能持续生长数千年，基于钟乳石的古火灾替代指标具有很高的潜在效用。