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Coupled physical, chemical, and microbiological measurements suggest a connection between internal waves and surf zone water quality in the Southern California Bight

dc.contributor.author Wong, SHC
dc.contributor.author Santoro, AE
dc.contributor.author Nidzieko, NJ
dc.contributor.author Hench, JL
dc.contributor.author Boehm, AB
dc.date.accessioned 2015-10-21T16:21:37Z
dc.date.issued 2012-02-15
dc.identifier.issn 0278-4343
dc.identifier.uri https://hdl.handle.net/10161/10768
dc.description.abstract Internal waves have been implicated in the cross-shore transport of scalars such as larvae, nutrients, and pollutants at locations around the world. The present study combines physical measurements with a comprehensive set of surf zone water quality measurements to evaluate the possible impact of cross-shore internal wave transport on surf zone water quality during two study periods. An array of oceanographic moorings was deployed in the summer of 2005 and 2006 at 10-20. m depth offshore of the beach to observe internal waves. Concurrently, surf zone water quality was assessed twice daily at night at an adjacent station (Huntington State Beach) by measuring concentration of phosphate, dissolved inorganic nitrogen (DIN), silicate, chlorophyll a, fecal indicator bacteria (FIB), and the human-specific fecal DNA marker in Bacteroidales. The baroclinic component accounted for about 30% of the total variance in water column velocity, indicating the importance of density-driven flow during the summer when the water column was stratified. Arrival of cold subthermocline water in the very nearshore (within 1. km of the surf zone) was characterized by strong baroclinic onshore flow near the bottom of the water column. The near bottom, baroclinic, cross-shore current was significantly lag-correlated with the near bottom temperature data along a cross-shore transect towards shore, demonstrating shoreward transport of cold subthermocline water. Wavelet analysis of temperature data showed that non-stationary temperature fluctuations were correlated with buoyancy frequency and the near bottom cross-shore baroclinic current. During periods of large temperature fluctuations, the majority of the variance was within the semi-diurnal band; however, the diurnal and high frequency bands also contained a substantial fraction of total variance. The bottom cross-shore baroclinic current was proposed as a proxy for shoreward transport potential by internal waves and was positively correlated with phosphate concentration in both years, silicate in 2005, and fecal indicator bacteria measurements in 2006. The results suggest internal waves are an important transport mechanism of nutrient-rich subthermocline water to the very nearshore in the Southern California Bight, and may facilitate the transport of FIB into the surf zone or enhance persistence of land-derived FIB. © 2011 Elsevier Ltd.
dc.publisher Elsevier BV
dc.relation.ispartof Continental Shelf Research
dc.relation.isversionof 10.1016/j.csr.2011.12.005
dc.title Coupled physical, chemical, and microbiological measurements suggest a connection between internal waves and surf zone water quality in the Southern California Bight
dc.type Journal article
duke.contributor.id Hench, JL|0123888
pubs.begin-page 64
pubs.end-page 78
pubs.organisational-group Civil and Environmental Engineering
pubs.organisational-group Duke
pubs.organisational-group Earth and Ocean Sciences
pubs.organisational-group Marine Science and Conservation
pubs.organisational-group Nicholas School of the Environment
pubs.organisational-group Pratt School of Engineering
pubs.publication-status Published
pubs.volume 34


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