TRACKING THE PRIMARY SOURCES OF FECAL POLLUTION IN THE RECHARGE AND CONTRIBUTING ZONES OF EDWARDS AQUIFER IN BEXAR COUNTY, TX USING MOLECULAR TOOLS

The Edwards Aquifer, located in south-central Texas, is one of the most prolific aquifers in the United States. The Edwards Aquifer is a Karst Aquifer which means that its topography is composed of soluble rocks and characterized by underground drainage systems of sinkholes, springs, water wells, and streams. The Edwards Aquifer satisfies the industrial, agricultural, domestic and recreational needs of more than two million people in the region. Karst systems are extremely vulnerable to animal and human contamination because of its distinctive high porosity and permeability; therefore a rapid movement of water from the land surface into and through the subsurface is present. The rapid movement of water limits the time available for physical and biogeochemical reactions that would otherwise reduce the concentration of pollutants and lessen the damage. Sewage contamination of water represents a major risk for environmental and human health and it is important to identify the sources of fecal contamination since it is essential to control water quality and mitigate pollution.

This project has duration of three years starting on January 2018 and concluding on 2020. The sampling events started on January 23, 2018 and its scheduled weekly for the rest of the project´s duration. The water quality parameters performed on site include pH, temperature, dissolved oxygen, and dissolved nitrogen. Samples are collected in sterilized 1 L Nalgene bottles, stored on ice, and transported to the lab for filtration. Samples are then filtered through a 0.45 μm pore-size membrane, labeled and stored at -80.0° c until DNA extraction. DNA is extracted from filter samples using The Dneasy Powerlyzer Powersoil Kit (by Qiagen) protocol, and stored at -20.0° c until further studies. When DNA has been extracted from the samples PCR- based methods will be applied to identify human and animal sources of fecal Bacteroidales. Since the Edwards Aquifer Project is on the early stages, there are not definite results, however early on next year there will be the completion of one year worth of data and results will be analyzed to be presented in the conference.