2022 Projects

The main geology of the peninsula is karst. The karst is evident on the surface with collapse features and cenotes throughout the whole area. The lack of soil and the surface conduits allow contaminant releases at the surface to spread into the freshwater. Drinking water comes from an unconfined aquifer located 10-50 m below the surface with a saline water interface below that. This unconfined and coastal aquifer gradient is influenced by increased pumping for freshwater supplies and by diurnal tidal action.

As tourism increases so does the need for fresh water. The well field for southern Cancún and Puerto Morelos is just west of the Cancún International Airport along the Ruta de los Cenotes. This well field contains over 75 wells, each pumping fresh water out of the aquifer. Without the pumping, the aquifer flows into the ocean. The research questions are: Does the pumping at the well field reverse the hydraulic gradient so water flows into the well field? How large is the cone of depression? What is the zone of influence of the well field? Is the coast aquifer elevation influenced by the diurnal tidal action? Do major rain events change the direction of flow?

This project will use the elevation of groundwater around the well field to model the groundwater flow. Elevation will be determined by surveying the water levels in cenotes throughout the region. Pressure transducers will be used to monitor water levels over the month. The data will be used to generate groundwater flow models using GFlow or Modflow. The outcomes from this research will allow for better planning and management of the limited freshwater resources in the Yucatán Peninsula.

The Yucatán Peninsula has some unique geological features called cenotes, which are natural passageways that connect activities on the surface to the groundwater below.  Cenotes are commonly used for recreation, and represent a major portion of the tourism industry in the Cancún area.  A desirable trait of popular cenotes is the clear blue water that is often found in advertisements and other publications. This year, we are particularly interested in one cenote that has only recently been opened to the public, yet shows some signs of eutrophication – the excessive richness of nutrients, frequently due to runoff from the land, which causes a dense growth of plant life and a depletion of dissolved oxygen.  Previously, the water in this cenote has been cloudy and green in color – not desirable traits for recreation. In this study, we will focus on this one cenote to work towards the following goals

• Perform a detailed assessment of inorganic nutrients, chlorophyll, dissolved oxygen to determine the level of eutrophication in the cenote
• Examine the potential factors that may contribute to influx of nutrients for this specific cenote
• In conjunction with the owner of the cenote, develop a plan to improve the water quality.

This project will involve the chemical analysis of nitrogen (NO₂^-, NO₃^-, NH₄⁺), phosphorous (PO₄^-3), dissolved oxygen (O₂, aq), turbidity, chlorophyll concentration, and other important geochemical parameters to fully characterize the water quality of the cenote.  It will also involve examining the surrounding area to determine potential sources of nutrient pollution leading to eutrophication, particularly those related to surface runoff.  Using these results and the relevant literature on the remediation of eutrophic bodies of water, we will also develop a remediation plan that can be shared with the owner of the cenote in an attempt to provide some meaningful solutions.  A key part of this project will be working with the local people to identify potential issues and work towards a solution. Students will learn to create a sampling plan, collect and preserve water samples from cenotes and perform different types of chemical and biological analyses.

This project will consist of one faculty mentor and 1-2 students. While candidates are suggested to have background in general chemistry, biology/environmental science/earth science, all interested students are welcome.

This project will use geophysics to better understand the karst hydrogeology along the Holbox Fracture Zone (HFZ) west of Cancún and north of Leona Vicario. Geophysical surveys have proven useful in investigations along the Ruta de los Cenotes in mapping the water table, freshwater/saltwater interface and in identifying fractures and karst conduits that link the surface to the water table (Carpenter et al., 2013; Cerda-Garcia et al., 2017; Garcia et al., 2018). Equipment available in Mexico (through CICY and borrowed from the National University, UNAM) include a 4-electrode resistivity unit with stainless-steel and porous pot electrodes for soundings and SP surveys, a 72-electrode automatic switching resistivity system for 2D surveys, a time-domain electromagnetic system (TEM) for deeper soundings and profiles, as well as a variety of GPS instruments for precisely locating and determination of survey stations. A drone with a video camera will also be employed to aerially record survey lines.

There has been increased national attention to the presence of “emerging contaminants” or “contaminants of emerging concern” (CECs) in surface water and groundwater. Two of particular concern and areas for research collaboration are per- and polyfluoroalkyl substances (PFAS) and microplastics (MP). 

PFAS are referred to as “Forever Chemicals” because of their persistence, widespread distribution in the environment, and potential human-health impacts.  Since they were first created in the 1950s, there are over 600 different chemicals have been created within in this class of compounds with common names being Teflon, Gore-tex, water proofing, and fire retarders. Recently, Illinois has adopted PFAS standards since there is not a federal drinking water standard.  Illinois’ proposed standard for perfluorobutane sulfonic acid (PFBS) is 0.14 mg/L with PFOA and PFOA combined not to exceed 0.000021 mg/L. Compared to other states such as Michigan, Illinois has less known contaminated sites but there is still a lot of work that needs to be done to locate and understand these compounds fate and transport in our soil and groundwater. One area of research that has not been done associated with PFAS is enhanced detection, fate, and transport of the compound especially after a release into the environment.  A potential research project between USGS and NIU will increase the capabilities for detection of these compounds in soil and water at both institutions while examining fate and transport of PFAS in sediments found throughout the state of Illinois.

Micro- and nano-plastics (MP) are ubiquitous in the environment. The term “microplastics” was first described over a decade ago to refer to plastic pellets, fibers, foams, and films with particles <5 mm with the lower bound of  ~1 µm (nanoplastics). The explosion in plastic production and usage has resulted in an equally massive increase in plastic pollution affecting aquatic, terrestrial, and atmospheric environments. As the human population continues to increase, so does the production of disposable packaging materials and single-use items. MP are rapidly accumulating within our natural environment, yet the identification of microplastics in food, organisms, and the environment remains a huge challenge. Because these microplastic materials are exposed to solar radiation, mechanical stresses and microbial action in the environment, the particle sizes are degraded to very small nanoplastics and the parent polymeric structure can be substantially modified in collected samples.  MP in water research has focused almost exclusively on marine environments while surface and groundwater is limited and mostly relates to detection. Within this initiative, we will investigate the sources of MP; occurrence, fate, and transport of MP; and how MP change aquifer properties. Surface water and groundwater sampling often relies on plastic based equipment and bottleware; therefore, we will determine the best practices for sampling for microplastics in groundwater through experiments in the laboratory.