Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Environmental Engineering and Earth Science

Committee Chair/Advisor

Dr. Diana Vanegas

Committee Member

Dr. Cindy Lee

Committee Member

Dr. Arelis Moore

Committee Member

Dr. Catherine Mobley


In Colombia, ethnic communities have traditionally been responsible stewards of natural resources. They recognize the importance of these resources for their livelihood, as well as their ancestral and cultural heritage. El Tiple, a rural Afro-Colombian community, has been affected by the incursion of private corporations that promoted the expansion of sugarcane monocrops in their territory. Since the introduction of the monoculture industry, local freshwater sources have been depleted due to intensive water use for irrigation of the sugarcane crops. Additionally, the intensive usage of agrochemicals has been linked with loss of native flora, damages to family farms, and pollution of surface water. For example, glyphosate, the most used herbicide, is aerially sprayed over the sugarcane fields via light aircrafts and drones. Glyphosate was classified by the International Agency for Research on Cancer (IARC) and the World Health Organization (WHO) as probably carcinogenic to humans, and human exposure to glyphosate can disrupt the endocrine and reproductive systems. While highly accurate laboratory techniques for pesticide measurement exist, continued glyphosate screening in several potentially affected sites is currently unconceivable due to limitations of conventional laboratory techniques, such as the need for complex sample pre-treatments, controlled environmental conditions, high-cost analysis, etc.

This project aims to connect pollution science and monitoring technology with the environmental justice struggles in El Tiple. The objectives of this work are (i) to develop a low-cost field-deployable sensor for measuring organophosphorus pesticides, such as glyphosate, in water; (ii) to conduct a water quality assessment and determine human health risks associated with water ingestion in the community of El Tiple, Colombia; and (iii) to identify assets, knowledge, needs, and challenges in El Tiple, Colombia, to inform the design of a training protocol on the use of water quality monitoring tools.

For the sensor development, a three-electrode system was fabricated via laser-inscribed graphene. The working electrode was functionalized with copper nanoparticles that have a high affinity toward organophosphate compounds. The sensor showed a limit of detection (LOD) of 3.42 ± 1.69 µM for glyphosate and 17.78 ± 7.68 µM for AMPA. The LOD for glyphosate is lower than the maximum residue limit (MRL) in drinking water (4.14 µM), as established by the United States Environmental Protection Agency (EPA).

The water pollution assessment was conducted based on a mixed-methods approach framed within the community-based participatory research (CBPR) approach. Surveys and focus groups were conducted with community participants to determine the exposure frequency of water ingestion. Four water sampling campaigns were conducted in El Tiple to measure water quality parameters such as pH, turbidity, total coliforms, fecal coliforms, pesticides, and several metals. Results from this work indicate that the concentration of total coliforms, glyphosate, and some hazardous metals (mercury, lead, and arsenic) exceeds the regulatory thresholds in several water sources, including deep wells, agricultural irrigation channels, and the Cauca River. Concerning levels of arsenic were found in the filtrates of low-cost household filters recently donated to the community by an energy company. The hazard index associated with water consumption indicates serious risk from exposure to toxic metals/metalloids via ingestion for individuals that rely exclusively on groundwater consumption.

Finally, assets, challenges, and needs in El Tiple were identified using community meetings, surveys, and interviews with community members and staff from governmental organizations in Colombia. The community of El Tiple has a strong and organized internal social structure based on five community associations and ten local institutions. The community youth are engaged in leadership and participatory programs involving formal education, workshops, and recreational activities. Government “abandonment” was identified as a major impediment for community welfare. A tailored educational program for environmental monitoring in El Tiple can potentially target the youth population through articulation with well-established community organizations. Information generated from the environmental monitoring program could be used to support local decision-making processes and state policies aimed at protecting vulnerable citizens and the environment.

Author ORCID Identifier

Available for download on Saturday, August 31, 2024