Assessing fecal contamination in groundwater from the Tulum region, Quintana Roo, México [recurso electrónico] / Cheyenne Morgan

Tesis (Master of Sciences) .-- Northern Illinois University, 2011.

Little is known about the extent of pollution in groundwater that occurs along the Riviera Maya located along the eastern coast of the Yucatan Peninsula. Underlying the Yucatan Peninsula in Mexico is a highly permeable fractured karst limestone that increases the potential for rapid transport of microbial and chemical contaminants from the surface to belowground aquifers. With rampant growth in many areas throughout the peninsula there is a potential to release from wastewater a large number of contaminants including pathogens. The objective of this research project was to test multiple groundwater samples near Tulum, Quintana Roo that ranged from protected to impacted to determine the occurrence and source of fecal contamination and link this information to the hydrogeologic setting. The membrane filtration and MPN methods were used for the quantification of total coliforms and E. coli. Sample coliform counts exceeded Mexican Drinking Water Standards (0 MPN/100mL). Testing for Bacteroides indicated that fecal contamination was indeed occurring in the region´s groundwater. Bacteroides levels were highest in water samples with known human impact, averaging 1.0 x 10^6 and 4.4 x 10^3 molecular markers/100 mL across impacted and non-impacted source waters, respectively. Geochemical data indicates a saline water intrusion with possible seasonal trends of meteoric water influx and increased microbial metabolism. We determined the fate and transport of fecal indicators within the karstic system of the Yucatan Peninsula will aid in identification of point sources of groundwater pollution, knowledge vital to the design of remediation strategies for this seriously degraded aquifer.