Geothermally influenced surface waters are typically linked to high temperatures; however, they can also be associated with ambient temperature and have the distinct solute chemistry that identifies them as geothermal in origin. Few studies have been linked to diatom assemblages in ambient temperature, geothermally influenced waters. This study focused on the Sulphur Creek watershed in the Valles Caldera National Preserve, northern New Mexico. Seven representative sites were sampled monthly between May 2016-September 2016 for physicochemical parameters and diatom community composition. Ambient temperature waters with high conductivities, lower pH values (≤ 4.0), and increased Al+++, Fe++, SO4=, and SiO2 concentrations are observed at geothermally influenced sites within the Sulphur Creek watershed. Major ions and stable isotopes identified both calcium-bicarbonate and calcium-sulfate type waters and showed that geothermally influenced waters are causing episodic acidification of downstream Redondo Creek. Diatom community diversity, cell density, and relative abundance of species were found to be distinctly different in upstream circum-neutral reaches compared to communities found in geothermally influenced waters downstream. Diatom taxa observed in geothermally influenced waters were indicative of low pH environments like acid mine drainage (Pinnularia subcapitata, Eunotia exigua) and had lower diversity indices. Characterization of the watershed through hydrochemical analysis and diatom response to ambient temperature, geothermal inputs may help with ongoing assessment and classification efforts of unique waters such as those found within the Sulphur Creek watershed.
Surface waters, to high temperature, Sulphur Creek watershed, Valles Caldera National Preserve, northern New Mexico, geothermal
Fox, April. "Diatom community response to an acidic, ambient temperature, geothermal gradient." (2017). https://digitalrepository.unm.edu/wr_sp/162