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
(0.5–1.0 g); PAHs and MAs were measured by GC–MS and LC–HILIC–MS,
respectively. Detection limits range from 0.05–2.1 ng for PAHs and
0.01–0.1 ng for MAs. We applied the method to 10 samples from a
∼ 400-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 (r = 0.75, p < 0.05) between the major
MA (levoglucosan) and non-alkylated PAHs (Σ15). We investigated
multiple diagnostic PAH and MA ratios and found that although not all were
applicable as paleo-fire proxies, ratios that combine PAHs with MAs are
promising tools for identifying different fire regimes and inferring the
type of fuel burned. In the 1950s and 1960s, levoglucosan and Σ15
concentrations roughly doubled compared to other times in the last 400 years, suggesting greater fire activity at Mayapan during these two decades.
The higher concentrations of fire markers may have been a consequence of
land clearance at the site and exploration of the cave by Carnegie
Institution archaeologists.