Two-Year Hydrocarbon Variations in Sediments of the Ring of Cenotes, Yucatan, Mexico.

Pollutant input to groundwater could result in karstic aquifers water quality degradation. In the karstic aquifer of Yucatan several anthropogenic activities take place without water sanitation or waste management, thus, these activities could be a source of contaminants to sinkholes (locally known as "cenotes"), which are the most relevant features in the karstic platform. In this context, this study monitored total n-alkanes (TAL) and polycyclic aromatic hydrocarbons (PAHs) in sediments of sinkholes at the ring of cenotes in Yucatan over a two year full hydrologic cycle (rainy-dry-rainy-dry seasons). Total PAHs measured in this study ranged from 1.7 to 1450 ng/g, and from 0.01 to 7520.8 ng/g for TAL. Spatially significant variations were only found between the eastern and central zones in dry season, probably as result of the environmental and hydrological changes. Main probable origin of hydrocarbons was found to be pyrogenic, resulting from local customs such as constant garbage burning and seasonal farmfields burning. Although PAHs did not show concentrations of concern yet, current socioeconomic development and no water sanitation envisages future threats to the karstic aquifer water quality for human supply.