Date of Award
Master of Science (MS)
The deep biosphere in cold, dark sub-seafloor ultramafic rocks (i.e., those rocks rich in Fe and Mg) is stressed by exceedingly high pH of through-going solutions, transient, if any, inorganic carbon availability, and little known organic carbon inventories. As a test of heterotrophic carbon use, serpentinite-associated waters (from groundwater sampling wells and associated surface seepages in tectonically uplifted mantle units in ophiolites) were tested for differences with respect to aqueous geochemistry and microbial growth assays in EcoPlates™ - BioLog Inc. This work focuses on two field locations for water sampling: the Coast Range Ophiolite, CA, USA, and the Zambales Ophiolite, Philippines. Characteristics of each sampling site are presented (pH, ORP, Conductivity, temperature, lithology, %DO, depth, and Ca2+/Mg2+ ratios). Complementary EcoPlate™ results [prefabricated 96-well plates, seeded with triplicate experiments for determining microbiological community response to difference organic carbon sources; a triplicate control experiment with no carbon source is built in to the plate] are also presented. Waters from selected California sites [7 discrete groundwater monitoring wells and 5 hydrologically connected sites] and Philippines sites [4 Zambales Ophiolite springs/seepages] sourced in serpentinites were analyzed. EcoPlate™ average well-color development (AWCD), which demonstrates microbial activities averaged per plate (as in Garland and Mills, 1991), differs across sites. Correlations of AWCD with environmental data are evaluated. Clarifying the geochemical-biological relationships that bear out in these analyses informs discourse on the energetic limits of life in serpentinizing systems, with relevance to ultramafic-hosted life on continents and in the seabed.
Scott, Tabitha Juliann, "HABITABILITY OF ULTRABASIC, SERPENTINITE-ASSOCIATED WATERS FROM COAST RANGE AND PHILIPPINES OPHIOLITES" (2014). Open Access Master's Theses. Paper 467.