Past fire dynamics inferred from polycyclic aromatic hydrocarbons and monosaccharide anhydrides in a stalagmite from the archaeological site of Mayapan, Mexico

Abstract

Speleothems (cave stalagmites) contain inorganic and organic substances that can be used to infer past changes in local and regional paleoenvironmental conditions. Specific biomarkers can be employed to elucidate the history of past fires, caused by interactions among climate, regional hydrology, vegetation, humans, and fire activity. We conducted a simple solid-liquid extraction on pulverised carbonate samples to prepare them for analysis of 16 polycyclic aromatic hydrocarbons (PAHs) and three monosaccharide anhydrides (MAs). The preparation method requires only small samples (0.5-1.0ĝg); PAHs and MAs were measured by GC-MS and LC-HILIC-MS, respectively. Detection limits range from 0.05-2.1ĝng for PAHs and 0.01-0.1ĝng for MAs. We applied the method to 10 samples from a ĝ1/4ĝ400-year-old stalagmite from Cenote Ch'en Mul, at Mayapan (Mexico), the largest Postclassic Maya capital of the Yucatán Peninsula. We found a strong correlation (rĝCombining double low lineĝ0.75, pĝ