Water Resources Research Act Program

Principal Investigators: Gigi Richard

Abstract: This work is expected to be performed in cooperation with the ongoing Selenium Management Program implemented by the U.S. Bureau of Reclamation (BOR). Salinity and selenium (Se) levels of several rivers in Colorado originate from a concentration of natural sources of dissolved solids in surface waters and alluvial groundwater after irrigation and evapotranspiration (ET) in agriculture. The purpose of this project is to study a managed aquatic plant ecosystem (i.e., floating wetland), comprised of macrophytic/halophytic plant species. This ecosystem will be evaluated as a tool for sequestering Se and certain salts affecting water quality in the Lower Gunnison River Basin (LGRB). A mix of plants known for their desalinization potential will be selected from research-based species evaluations published in the scientific literature. The project will utilize floating wetland technology that has been commercially developed through Beemats, LLC (http://beemats.com/). Evaluation of the extraction potential (e.g., root surface microbes, tissue uptake) for certain salts and Se will be performed on plants grown in controlled greenhouse mesocosms. The mesocosm approach permits a simple mass balance to be done, with allowances for the volatilized fraction (dimethylselenide, DMSe). Water quality analysis will be conducted using handheld meters for electrical conductivity (EC), pH, salinity and dissolved oxygen (DO). Additional water quality analyses will be performed by an EPA-certified laboratory to measure Se levels and speciation in mesocosm water samples and digested plant tissues. A component analysis will be performed at outdoor field sites, to assess plant uptake and survivability.