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Quantifying the benthic source of nutrients to the water column of Upper Klamath Lake, Oregon

September 12, 2007

Executive Summary

Five sampling trips were coordinated in April, May and August 2006, and May and July 2007 to sample the water column and benthos of Upper Klamath Lake, OR (Fig. 1; Table 1), before, during and after the annual cyanophyte bloom of Aphanizomenon flos-aquae (AFA). A pore-water profiler was designed and fabricated to obtain the first high-resolution (centimeter-scale) estimates of the vertical concentration gradients for diffusive-flux determinations. Estimates based on molecular diffusion may underestimate benthic flux because solute transport across the sediment-water interface can be enhanced by processes including bioturbation, bioirrigation and ground-water advection. Water-column and benthic samples were also collected to help interpret spatial and temporal trends in diffusive-flux estimates. Data from these samples complement geochemical analyses of bottom-sediments taken from Upper Klamath Lake (UKL) in 2005.

This ongoing study provides information necessary for developing process-interdependent solute-transport models for the watershed (that is, models integrating physical, geochemical and biological processes), and supports efforts to evaluate remediation or load-allocation strategies. To augment studies funded by the U.S. Bureau of Reclamation (USBR), the Department of Interior supported an additional full deployment of pore-water profilers in July 2007, during the summer AFA bloom. Results from this recent field trip are not fully completed. Data not presented herein will be included in a subsequent publication, scheduled for March 2009.

Publication Year 2007
Title Quantifying the benthic source of nutrients to the water column of Upper Klamath Lake, Oregon
DOI 10.3133/ofr20071276
Authors James S. Kuwabara, Dennis D. Lynch, Brent R. Topping, Fred Murphy, James L. Carter, Nancy S. Simon, Francis Parcheso, Tamara M. Wood, Mary K. Lindenberg, Katryn Wiese, Ronald J. Avanzino
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Open-File Report
Series Number 2007-1276
Index ID ofr20071276
Record Source USGS Publications Warehouse
USGS Organization Toxic Substances Hydrology Program; U.S. Geological Survey