David Naftz
David Naftz
Dave has been a research hydrologist with the U.S. Geological Survey/Utah Water Science Center for over 25 years. He received his Ph.D. in Geochemistry from the Colorado School of Mines and is an adjunct faculty member at the University of Utah and Utah State University. Naftz has done research on a variety of water-quality and climate-related issues in the western United States and began his research on Great Salt Lake in 2001. His research interests on Great Salt Lake have included mercury and selenium geochemistry, nutrient cycling, historical reconstruction of anthropogenic pollutants, and submarine groundwater discharge. Although he easily becomes seasick, he has thoroughly enjoyed his time on the open water of this truly spectacular resource.
Abstract: Nutrient input modeling to Great Salt Lake
Great Salt Lake (GSL) receives wastewater discharges from > 15 treatment plants serving metropolitan areas along the Wasatch Front. Farmington Bay (FB), a causeway restricted bay of GSL, receives a substantial portion of this wastewater discharge. This bay is hypereutrophic with massive blooms of toxic cyanobacteria and concentrations of toxic nodularin have exceeded 200 g/L (Wurtsbaugh et al., 2009). Previous isotopic analyses (Naftz et al., 2008) have suggested that brine shrimp utilize particulate matter exported from FB; however, additional sampling is needed to confirm these results. To date (2010), only limited data have been collected to determine the annual nutrient inputs into GSL and how these nutrient inputs compare to the nutrient pool residing in Gilbert Bay. From 2003 through 2008, the USGS, in cooperation with the Utah Department of Natural Resources/Division of Wildlife Resources (UDNR/DWR) measured nutrient inputs from Bear River, FB, and Weber River to Gilbert Bay. Nutrients that were monitored included ammonia, phosphate, total nitrogen (dissolved and particulate), total phosphorus (dissolved and particulate), and total particulate carbon. The USGS loading software, LOADEST was used to estimate the daily mass loading of nutrients from the three input sites for the period of October 2003 through March 2008. In order to compare incoming nutrient loads to the residual nutrient pool in Gilbert Bay, the same nutrient species were concurrently monitored at four open-water lake sites. Model results found the mean monthly nitrogen (dissolved + particulate) load to Gilbert Bay was 360,000 kg. Although the Bear River watershed is > 2X larger than the Jordan River watershed, FB inflow provided > 51% of the dissolved nitrogen load to Gilbert Bay compared to ~ 46% of the dissolved nitrogen load from Bear River. Relative amounts of annual nutrient loads from Bear River were significantly reduced during lower-than-average runoff years. During water year 2006, riverine load of total nitrogen (dissolved + particulate) was about 8% of the mass residing in Gilbert Bay (70% epilimnion and 22% hypolimnion). In cooperation with UDNR/DWR, nutrient monitoring and modeling efforts on GSL are continuing with the inclusion of two additional inflow sites.
References
Naftz, D.L., Angeroth, C., Kenney, T., Waddell, B., Silva, S., Darnall, N., Perschon, C., and Whitehead, J., 2008, Anthropogenic influences on the input and biogeochemical cycling of nutrients and mercury in Great Salt Lake, Utah, USA: Applied Geochemistry, vol. 23, p. 1731–1744.
Wurtsbaugh, W.A., Naftz, D.L., and Bradt, S.R., 2009, Eutrophication, nutrient fluxes and connectivity between the bays of Great Salt Lake, Utah (USA): In, A. Oren, D. Naftz, P. Palacios and W.A. Wurtsbaugh (eds). Saline Lakes Around the World: Unique Systems with Unique
Values. Natural Resources and Environmental Issues, volume XV. S.J. and Jessie E.
Quinney Natural Resources Research Library, Logan, Utah, USA.
Eyes on the Prize - Charles Uibel
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