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eNews March 2019

UNM Researcher Studies Hydrogeologic Influences of Valles Geothermal System: Project on upper Jemez River focuses on natural trace elements

By Victoria Pena-Parr, University of New Mexico Communication & Marketing

University of New Mexico graduate student Jon Golla conducts his research along the Jemez River in the natural laboratory of the Valles Caldera located in northern New Mexico. Golla’s research focuses on his passions involving aqueous geochemistry and geothermal systems.

His scientific interests stem from an unfamiliarity with potable water during his childhood and from an early exposure to geothermal energy in the Philippines, so the opportunity to work on the waters associated with the Valles Caldera Geothermal System was part of what drew him to graduate study at UNM. Through this research, Golla is gaining a better understanding of the proximal and distal hydrogeologic influences of Valles Geothermal System on the upper Jemez River.

He received a $6,000 grant to help fund his research titled, Surface Water Quality Implications of Valles Caldera Geothermal Fluids on Jemez Watershed: A Holistic Hydrogeochemical Investigation as part of the Student Water Research Grants program through the New Mexico Water Resources Research Institute (NM WRRI).

“Known as New Mexico’s version of Yellowstone, the Valles Caldera is a highly mineralized geothermal system, which are known for usually having a significant environmental footprint,” Golla said. “The Jemez Mountains are well-known for its world-class, high temperature, liquid-dominated Valles Caldera Geothermal system. The Valles Caldera Geothermal system is what gives the Jemez Hot Springs their natural heat. These geothermal fluids find their way into the Jemez River.”

Golla specifically focuses on the natural trace element salinization of the Jemez River. Shallow magmatic activity provides heat to the system and creates a natural convection current of geothermal waters, which are usually mixtures of deeply derived fluids and infiltrating precipitation. These circulating fluids become much more saline than other natural waters (i.e., river, groundwater, etc.) because minerals in rocks are more readily dissolved at higher temperatures. Such saline waters are expressed at the surface of the iconic Soda Dam and Jemez Springs as springs, which discharge into and impair the water quality of the Jemez River.

His research goals as part of the project include discovering how these dissolved species are introduced into the system, which is marked by elevated concentrations in the river; how far downstream this geothermal signature is carried; and which processes (i.e., dissolved species captured by or transformed into solids) are potentially responsible for removal in-stream. The research group collects multiple water samples along the study reach to provide a continuous spatial mapping of geochemical behavior.

“We are measuring and assessing concentrations of heavy metals (arsenic, uranium, lead, etc.) that only require trace exposure to induce adverse health effects and are usually not regularly analyzed in routine water quality surveys,” Golla said. “Most importantly, water from the Jemez River is used by stakeholders, including Jemez and Zia Pueblos, for domestic, recreational, and irrigational uses.”

Golla’s research builds upon previous knowledge published by Los Alamos National Laboratory scientists and extends the suite of measured dissolved elemental species by including metals (like arsenic, lead, and uranium), which are usually found in trace amounts in natural waters but are more abundant in the inflowing thermal spring waters due to enhanced water-rock interaction at depth.

“This work is confirming the significant role that groundwater contributions to surface water plays in affecting water quality,” added UNM Department of Earth and Planetary Sciences Professor Laura Crossey, Golla’s advisor. “As we look to a future with potential decreases in snowmelt, it may be that these groundwater contributions cause our rivers to become more saline and impair their use. Studies such as Jon’s can help improve our prediction of water quality as we improve our climate-based forecast models for water quantity, both critical factors for water management in our semi-arid region.”

This study also supplements the New Mexico Environment Department’s recently approved Total Maximum Daily Load development and the U.S. Environmental Protection Agency’s ongoing New Mexico Water Quality Management Plan.

“Personally, I think New Mexico is very lucky to have a world-class geothermal system,” Golla said. “Due to its relatively undisturbed state, the Valles Caldera is a natural laboratory to study continental hydrothermal processes.”