Article

Estuaries and Coasts

, Volume 34, Issue 2, pp 256-268

Open Access This content is freely available online to anyone, anywhere at any time.

Submarine Groundwater Discharge to a High-Energy Surf Zone at Stinson Beach, California, Estimated Using Radium Isotopes

  • Nicholas R. de SieyesAffiliated withEnvironmental Water Studies, Department of Civil and Environmental Engineering, Stanford University Email author 
  • , Kevan M. YamaharaAffiliated withEnvironmental Water Studies, Department of Civil and Environmental Engineering, Stanford University
  • , Adina PaytanAffiliated withInstitute of Marine Sciences, Earth & Planetary Sciences Department, University of California Santa Cruz
  • , Alexandria B. BoehmAffiliated withEnvironmental Water Studies, Department of Civil and Environmental Engineering, Stanford University

Abstract

Two 14-day experiments conducted in the dry summer (July 2006) and wet winter (March 2007) seasons, respectively, examined tidal, wave-driven, and seasonal variability of submarine groundwater discharge (SGD) at Stinson Beach, CA, using natural radium tracers. Tide stage, tide range, breaker height, and season each explained a significant degree of radium variability in the surf zone. A mass balance of excess radium in the surf zone was used to estimate SGD for each season, confirming larger discharge rates during the wet season. Our results indicate median groundwater discharge rates of 6 to 8 L min−1 m−1 in July 2006 and 38 to 43 L min−1 m−1 in March 2007. SGD from 200 m of Stinson Beach in March 2007 contributed a flux of phosphate and dissolved inorganic nitrogen approximately equal to that associated with all local creeks and streams within 6 km of the study site at that time.

Keywords

Submarine groundwater discharge Radium Nutrient flux California coast