The Orange County Sanitation District (OCSD) diverted wastewater discharge (5.3 × 108 l d−1) from its primary deep (56 m) outfall 8 km offshore, to a secondary shallower (16 m) outfall 1.6 km offshore for a period of three weeks. It was anticipated that the low salinity and density of the effluent would cause it to rise to the surface with limited dilution, elevating nutrient concentrations in near-surface waters and stimulating phytoplankton blooms in the region. Three Teledyne Webb Slocum gliders and a Liquid Robotics surface wave glider were deployed on transects near the outfalls to acquire high spatial and temporal coverage of physical and chemical parameters before, during, and after the wastewater diversion. Combined autonomous underwater vehicle (AUV) and MODIS-Aqua satellite ocean color data indicated that phytoplankton biomass increased in the upper water column in response to the diversion, but that the magnitude of the response was spatially patchy and significantly less than expected. Little evidence of the plume or its effects was detectable 72 h following the diversion. The effluent plume exhibited high rates of dilution and mixed throughout the upper 20 m and occasionally throughout the upper 40 m during the diversion. Rapid plume advection and dilution appeared to contribute to the muted impact of the nutrient-rich effluent on the phytoplankton community in this coastal ecosystem.
|Original language||English (US)|
|Number of pages||11|
|Journal||Estuarine, Coastal and Shelf Science|
|State||Published - Jun 28 2016|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: Matthew Ragan, Xiao Liu, Carl Oberg, Dario Diehl, Kendra Hayashi Negrey, Christopher Wahl, and Evan Randall-Goodwin were integral members of the glider team during the diversion. Arvind Pereira assisted with computer programming, glider operations, and data processing. Nick Rollins and Mattias Cape assisted with Matlab coding. Captain Ray Arntz and Captain Kyaa Heller of the SunDiver assisted with glider deployments. We also thank the staff members of the Wrigley Marine Science Center, especially Lauren Czarnecki, Kellie Spafford, Captain Trevor Oudin, and Captain Gordon Boivin, for their consistent support throughout the diversion glider effort. This research was supported by National Oceanic and Atmospheric Administration grants NA11NOS4780052, NA11NOS4780030, and NA08OAR4320894, National Science Foundation through RAPID award OCE1251573, Orange County Sanitation District research funds, the University of Southern California Provost Fellowship and Gold Family Graduate Fellowship, and King Abdullah University of Science and Technology. This is NOAA ECOHAB publication number 823.
ASJC Scopus subject areas
- Aquatic Science