The effect of seasonal rainfall on nutrient input and biological productivity in the Yax Chen cave system (Ox Bel Ha), Mexico, and implications for μXRF core studies of paleohydrology

Lakes and speleothems from Mexico's Yucatan Peninsula have been used extensively over the past decades for paleoclimate studies, however aquifer condition and its response to climate change has received little attention. Cenotes (sinkholes) and coastal caves have been shown to record the paleohydrology of the aquifer, but there is little information on sedimentation in these cave systems and its response to climate change. Newly developed μXRF instrumentation for the analysis of cores can achieve subannual resolution due to small measurement increments, but short period studies examining weathering inputs and rainfall have not yet been undertaken, hindering paleoenvironmental interpretations of lake and cave sediment records. This study examines the spatial and temporal relationship of cave sediment geochemistry in the anchialine cave system of Yax Chen (Quintana Roo, Mexico). Sediment traps (n = 51) were placed at seventeen stations along the 2.7 km flooded cave system, which transitions from mangrove to upland forest terrain, with cenotes of variable size and frequency along its length. Sediment traps were collected every ~6 months from May 2013–May 2017 along with rainfall and groundwater level data. There are distinct responses of lithogenic (Fe, Ti, Sr - limestone weathering) and biogenic influenced (Si, K, S - phytoplankton and mangrove sediment) elements in the sediment samples associated with seasonal rainfall and hurricanes. While lithogenic elements (Ti/K) show a direct relationship seasonal rainfall, the sedimentation of biologically influenced (Si/Ti) elements exhibit a 6–12 month lagged response with large rainfalls such as Hurricane Ingrid in 2013 and other tropical storms throughout the study period.