USING A HOT SPRINGS FIELD RESEARCH PROJECT TO TEACH UNDERGRADUATE BIOGEOCHEMISTRY

An on-going research project at the 52°C hot spring in Thermopolis, Wyoming, is a focus of our undergraduate research. Our field site is 60 miles north of campus, and state park facilities make an excellent field laboratory. For the past six years, our goal has been to characterize the microbial communities in the spring and to observe how the geochemistry varies with distance from the source, and with the variety of microbes. With the exception of the exponential loss of dissolved H₂S with distance from the source, the geochemistry is fairly flat, both geographically and temporally.

Introductory biogeochemistry is a required course for all geoscience majors and has prerequisites of chemistry, and biology or geology. Using global biogeochemical cycling as a unifying theme, the course topics trace the evolution of life along with the evolution of Earth. Students collect and analyze the water and microbes on a regualr basis. Most water testing is done in the field, although small quantities are collected and for more detailed analyses. Microbe morphology is described in situ as well as under 100x magnification. Selected samples have been analyzed by DNA fingerprinting and scanning electron microscopy.

This microbial community is dominated by long filamentous cyanobacteria in the warmest part of the channel, and mats developed under cooler temperatures along the edge and distant from the source. The filaments often exhibit a white film either at the tips or along the length of the filaments. Evidence confirms a deposition of carbonate material between the microbes, producing the white discoloration. Analyses of 16S rRNA show commonality with microbes existing in known saline environments. Total dissolved solids for this spring water are 25 mg/L on average, with a conductivity of 500 μ-Siemens. Gas bubbles are trapped in the cooler microbial mats and appear to be the result of chemosynthesis rather than out-gassing; a hypothesis that has yet to be tested.

Our research has been supported by small grants from university-based consortia. Under the new Community College Undergraduate Research Initiative (CCURI) program we will take our research to the next level: from description to understanding. This is an exciting and active way for our students to understand and become experts on Earth’s biogeochemical systems.