Wednesday, November 7, 2007
293-16
Soils-Based Evidence for a Former Salt-Marsh; Jarosite and Buried a Horizons (Humboldt County, CA).
Anthony Baker1, Marie Petersen2, Rosemary M. Records2, Susan Edinger-Marshall2, David A. Risberg2, and Carrie B. Alexander2. (1) Biological Sciences, Humboldt State Univ., 1 Harpst Street, Arcata, CA 95521, (2) Forestry and Wildland Resources, Humboldt State Univ., 1 Harpst St., Arcata, CA 95521
Acid sulfate soils occur in drained coastal wetland areas. Rocky Gulch, a reclaimed salt marsh adjacent to Humboldt Bay , California was surveyed and sampled by undergraduate students in soil classification and soil microbiology courses at Humboldt State University . Buried A horizons/debris lines mark former surfaces of the salt marsh, possibly used as a log pond in the late 1800s. Jarosite, confirmed by x-ray diffraction, occurs at different depths in soil profiles, where drainage has occurred. The bacteria Acidithiobacillus ferrooxidans is commonly associated with the formation of jarosite. DNA extraction, amplification and sequencing of putative A. ferrooxidans from this site is underway.