The Desert Research Institute (DRI) and the University of Hawai’i Cancer Center are leading research and published a study in Environmental Science and Technology on February 16th. The study uses data from groundwater wells in the western Great Basin to predict the probability of elevated arsenic in groundwater. The study also shows the location and number of private well users at risk. Carson Valley, Carson Desert Basin (including the town of Fallon, Nevada), and the Truckee Meadows (Reno) hold the highest number of groundwater well users at risk according to the study, showing 22% of 174 domestic wells in Northern Nevada had exceeded EPA guidelines.
Daniel Saftner, M.S, a hydrogeologist at DRI and lead author on the study, said that in that region we have a higher probability for elevated arsenic when compared to the rest of the country; the geothermal and tectonic processes that characterize the Great Basin also contribute to these concentrations of natural arsenic in the groundwater.
The region’s mountains are the primary source of the arsenic, Steve Bacon, Ph.D., DRI geologist, and study co-author said; owing to the arsenic-rich volcanic and meta-sedimentary rocks that form the mountains eroding, and their sediments being transported to the valleys below. When water percolates through the sediment it then carries the arsenic into the groundwater supply. The deeper and older the water pocket, the higher the level of arsenic contained; it can also migrate upwards via faults into shallower water pockets.
Saftner added that the study’s main goal is to add to an understanding of the unique geologic factors contributing to the higher arsenic in this study. It’s important to consider the role of the environment as pertaining to human health- and where we can influence what our long-term health will look like.
The research team will use data collected via the Healthy Nevada Project to train and test the predictive model; this includes samples from 163 domestic wells primarily located in the aforementioned areas. This data would then be supplemented with 749 groundwater samples compiled from USGS National Water Information System. Tectonic, geothermal, geologic, and hydrologic variables are then used by the model to predict the probability of arsenic levels across the region.
Monica Arienzo, Ph.D., associate research professor at DRI and study co-author, and Saftner, said that community members can use their hazard map to see what risk is at their location; hopefully motivating them to have their water tested. This will allow people to then take steps to limit exposure, such as installing a water treatment system. Findings from the study are potentially useful to a range of different applications, including water utilities or managers who tap shallow aquifers for their water supply.
The research team hopes to use their model to look more closely at the health impacts of prolonged arsenic exposure. Joe Grzymski, Ph.D., research professor at DRI concluded that the Healthy Nevada Project’s genetic data and health records are being paired with environmental data to help determine associations between health outcomes and levels of arsenic in the community’s groundwater.