5 Environmental Geochemistry and Health Impacts (Posters)

This session welcomes research on contaminant occurrence, fate and transport, and impacts on human and environmental health. Interdisciplinary contributions with implications for environmental remediation and natural resources management are encouraged.

Monday, 18 May 2026
8:00 AM - 5:30 PM
Alvarado D/E

Comparing Arsenic and Manganese in Burned, Mineralized Rocky Mountain Watersheds

Paper number: 5-0
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Wildfires are increasing in frequency and severity across the Rocky Mountain region, raising concerns about their effects on water quality, especially in regions with legacy mining. This research investigates the similarities and differences in how wildfires have influenced the water chemistry in two mineralized watersheds: Gallinas Creek in San Miguel County, NM, affected by the 2022 Hermit’s Peak/Calf Canyon wildfire, and Fourmile Creek near Boulder, CO, affected by the 2010 Fourmile Canyon Fire. Though both watersheds share similar elevation, as well as a majority granitic geology, they differ in the extent and type of historical mining activities. The Fourmile Creek watershed was much more heavily mined, with gold and tungsten being the primary metals mined there (Murphy et al., 2020), while the Gallinas Creek watershed was less heavily mined, with copper being the primary resource mined there.

This study focuses on arsenic (As) and manganese (Mn), two redox-sensitive critical minerals with environmental and regulatory significance. High burn severity wildfires can cause chemically reducing soil and sediment conditions which increase the dissolution of Mn oxides (Smith et al. 2011). In addition to this, fire can expose and remobilize As and Mn rich mine tailings. Previous studies have found elevated concentrations of these constituents in streams following wildfires (Murphy, 2020; Murphy, 2015; Smith et al., 2011; Rust et al. 2022). Comparing the chemistry in these two areas can help water managers understand how future wildfires could affect the mobility of these minerals in other mined regions. Preliminary results suggest that Mn concentrations increased post-wildfire within the stream sediments of both watersheds, with Gallinas having a more pronounced increase. Fourmile had higher average As concentrations in both the filtered and unfiltered water samples, as well as the ash and stream sediments, while Gallinas had higher average Mn concentrations. However, the water chemistry data from Fourmile Creek contained a higher maximum Mn concentration than Gallinas Creek. These results will be presented via a poster depicting the similarities and differences of the two regions physically, as well as comparisons of As and Mn concentrations in the water, stream sediments, and ash from both sites. Further research in these two watersheds could include geochemical modeling and further investigation into possible correlations between As, Mn, and dissolved organic carbon.

Geological Society of America Abstracts with Programs. Vol. 58, No. 4

doi: 10.1130/abs/2026RM-410564

© Copyright 2026 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.