Polycyclic Aromatic Hydrocarbons (PAHs) in speleothems.

<p>Secondary mineral deposits in caves, such as stalagmites, constitute valuable paleoclimate archives because they are largely protected from degradation by stable in-cave conditions and can be precisely dated In addition to established climate proxies such as stable isotopes and trace elements, organic proxies have become increasingly attractive in recent years for the study of paleo vegetation, wildfires, and hydrodynamics. [1]</p> <p>Biomass burning events are major sources of atmospheric particulate matter that influences global and local climate. [2] Investigating fire proxies in paleoclimate archives may therefore help determine the interactions of climate, hydrology, and fire activity.</p> <p>Polycyclic Aromatic Hydrocarbons (PAHs) are organic molecules made up of two or more fused aromatic rings. They stem from the incomplete combustion of organic matter. Their persistence in the environment makes them useful for the reconstruction of fire events from paleoenvironmental archives like sediments, peat, ice cores, and soils. [3-6] Their presence has also been reported in speleothems, however, only a limited range of PAHs seem to be transported into the cave and subsequently preserved in speleothem carbonate. [7, 8]</p> <p>We present a new sample preparation method for the extraction of PAHs from speleothem and the subsequent extraction of levoglucosan, an anhydrosugar derived from the combustion of cellulose that also constitutes a marker for biomass burning. We apply this method to speleothems from Cenote Ch'en Mul, Mayapan, on the Yuc&#225;tan peninsula, and White Moon Cave, California, to investigate the relationship between PAHs and levoglucosan. Such tandem approach will deepen our understanding of paleo-fire dynamics and strengthen proxy-based reconstructions.</p> <p>[1]&#160;A. Blyth et al. <em>Quat. Sci. Rev</em>. 149 (2016) 1-17 [2]&#160;P. Yao et al. <em>J. of Glaciology</em> 59 (2013) 599-611 [3]&#160;Tan et al. <em>Palaeogeography, Palaeoclimatology, Palaeoecology</em> 560 (2020) 110015 [4]&#160;Argiriadis et al. <em>Microchem. J.</em> 156 (2020) 104821 [5]&#160;Vecchiato et al. <em>Sci. Rep.</em> (2020) 10:10661 [6]&#160;Chen et al. <em>ACS Earth Space Chem</em>. 2018, 2, 1262&#8722;1270 [7]&#160;Argiriadis et al. <em>Anal. Chem.</em> 2019, 91, 7007&#8722;7011 [8]&#160;Perrette et al. <em>Chem. Geol.</em> 251 (2008) 67&#8211;76</p>