An organic carbon budget for coastal Southern California determined by estimates of vertical nutrient flux, net community production and export

Haskell, William Z.; Prokopenko, Maria G.; Hammond, Douglas E.; Stanley, Rachel H. R.; Berelson, William M.; Baronas, J. Jotautas; Fleming, John C.; Aluwihare, Lihini I.

doi:10.1016/j.dsr.2016.07.003

Cited by 17 publications

(56 citation statements)

References 56 publications

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“…This method provides a conservative estimate of OD1 by ignoring light attenuation caused 270 by dissolved organic matter. Average OD1 for these deployments was 12.3 m while the average euphotic depth, as defined by the 1% light level, was 38.3 m. This is consistent with in situ measurements of the euphotic depth from temporally overlapping cruises at the SPOT site that observed an average euphotic depth of 40 m (Haskell et al, 2016). Our estimates for the first optical and euphotic depths are also within the range of regional data collected during the CCE LTER process cruises from 2006-2008(Mitchell, 2014).…”

Section: Surface To Subsurface Connectivitysupporting

confidence: 74%

Contextualizing time-series data: Quantification of short-term regional variability in the San Pedro Channel using high-resolution in situ glider data

Teel¹,

Liu²,

Seegers³

et al. 2017

Preprint

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Oceanic time-series have been instrumental in providing an understanding of biological, physical, and chemical dynamics in the oceans and how these processes change over time. However, the extrapolation of these results to larger oceanographic regions requires an understanding and characterization of local versus regional drivers of variability. Here we use highfrequency spatial and temporal glider data to quantify variability at the coastal San Pedro Ocean Time-series (SPOT) site in 20 the San Pedro Channel (SPC) and provide insight into the underlying oceanographic dynamics for the site. The dataset was dominated by four water column profile types: active upwelling, offshore influence, subsurface chlorophyll maximum, and surface bloom. On average, waters across the SPC were most similar to offshore profiles. On weekly timescales, the SPOT station was on average representative of 64% of profiles taken within the SPC, and SPOT was least similar to SPC locations that were closest to the Palos Verdes Peninsula. Subsurface chlorophyll maxima with co-located chlorophyll and particle 25 maxima were common in 2013 and 2014 suggesting that these subsurface chlorophyll maxima might contribute significantly to the local primary production. These results indicate that high-resolution in situ glider deployments can be used to determine the spatial domain of time-series data, allowing for broader application of these datasets and greater integration into modeling efforts.

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Section: Surface To Subsurface Connectivitysupporting

confidence: 74%

Contextualizing time-series data: Quantification of short-term regional variability in the San Pedro Channel using high-resolution in situ glider data

Teel¹,

Liu²,

Seegers³

et al. 2017

Preprint

Self Cite

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“…This result is similar to estimates by Haskell et al . [] who determined K z = 1.5(0.6) × 10 −5 m 2 s −1 at the base of the mixed layer during fall and winter in the Southern California Bight, using a wind speed‐based parameterization of turbulence due to shear [ Haskell et al ., ]. The average vertical biological

O_{2}

flux was −3.5(4.6) mmol

O_{2}

m −2 d −1 , and the range was −19.0 to −0.1 mmol

O_{2}

m −2 d −1 .…”

Section: Calculationsmentioning

confidence: 99%

“…Haskell et al . [] found mixed layer NCP to be 10(15) mmol C m −2 d −1 in inshore California waters near Los Angeles during October 2013, lower than NCP during our study. GPP was 230(37) mmol C m −2 d −1 during the same time period [ Haskell et al , ], which is similar to GPP during our study.…”

Section: Synthesis and Comparison With Prior Workmentioning

confidence: 99%

Impact of recently upwelled water on productivity investigated using in situ and incubation‐based methods in Monterey Bay

et al. 2017

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Photosynthetic conversion of CO2 to organic carbon and the transport of this carbon from the surface to the deep ocean is an important regulator of atmospheric CO2. To understand the controls on carbon fluxes in a productive region impacted by upwelling, we measured biological productivity via multiple methods during a cruise in Monterey Bay, California. We quantified net community production and gross primary production from measurements of O2/Ar and O2 triple isotopes ( 17Δ), respectively. We simultaneously conducted incubations measuring the uptake of 14C, 15NO3−, and 15NH4+, and nitrification, and deployed sediment traps. At the start of the cruise (Phase 1) the carbon cycle was at steady state and the estimated net community production was 35(10) and 35(8) mmol C m−2 d−1 from O2/Ar and 15N incubations, respectively, a remarkably good agreement. During Phase 1, net primary production was 96(27) mmol C m−2 d−1 from C uptake, and gross primary production was 209(17) mmol C m−2 d−1 from 17Δ. Later in the cruise (Phase 2), recently upwelled water with higher nutrient concentrations entered the study area, causing 14C and 15NO3− uptake to increase substantially. Continuous O2/Ar measurements revealed submesoscale variability in water mass structure and likely productivity in Phase 2 that was not evident from the incubations. These data demonstrate that O2/Ar and 15N incubation‐based NCP estimates can give equivalent results in an N‐limited, coastal system, when the nonsteady state O2 fluxes are negligible or can be quantified.

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“…Monthly, multiyear time-series of productivity, based on incubations measuring the uptake of 14 C-labeled dissolved inorganic carbon (DIC) and 15 NO − 3 have been reported previously (Pennington and Chavez, 2000;Wilkerson et al, 2000), and numerous process-oriented biological studies have been conducted (Pilskaln et al, 1996;Kudela and Dugdale, 2000;Ward, 2005;Ryan et al, 2009;Johnson, 2010;Smith et al, 2014aSmith et al, , 2016 , but can be challenging to apply in systems where recently-upwelled water is observed at the surface; this low O 2 water may bias estimates low if not accurately accounted for (Munro et al, 2013;Teeter, 2014;Haskell et al, 2016b). Furthermore, inferring carbon export below the mixed layer from techniques within the mixed layer is complicated by the fact that lateral transport of surface waters and oceanic fronts may cause a spatial and/or temporal decoupling between carbon fixation and export (Olivieri and Chavez, 2000;Estapa et al, 2015;Nagai et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Insight into chemical, biological, and physical processes in coastal waters from dissolved oxygen and inert gas tracers

Manning¹

2017

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In this thesis, I use coastal measurements of dissolved O 2 and inert gases to provide insight into the chemical, biological, and physical processes that impact the oceanic cycles of carbon and dissolved gases. Dissolved O 2 concentration and triple isotopic composition trace net and gross biological productivity. The saturation states of inert gases trace physical processes, such as air-water gas exchange, temperature change, and mixing, that affect all gases.First, I developed a field-deployable system that measures Ne, Ar, Kr, and Xe gas ratios in water. It has precision and accuracy of 1 % or better, enables near-continuous measurements, and has much lower cost compared to existing laboratory-based methods. The system will increase the scientific community's access to use dissolved noble gases as environmental tracers.Second, I measured O 2 and five noble gases during a cruise in Monterey Bay, California. I developed a vertical model and found that accurately parameterizing bubble-mediated gas exchange was necessary to accurately simulate the He and Ne measurements. I present the first comparison of multiple gas tracer, incubation, and sediment trap-based productivity estimates in the coastal ocean. Net community production estimated from 15 NO -3 uptake and O 2 /Ar gave equivalent results at steady state. Underway O 2 /Ar measurements revealed submesoscale variability that was not apparent from daily incubations.Third, I quantified productivity by O 2 mass balance and air-water gas exchange by dual tracer ( 3 He/SF 6 ) release during ice melt in the Bras d'Or Lakes, a Canadian estuary. The gas transfer velocity at >90 % ice cover was 6 % of the rate for nearly ice-free conditions. Rates of volumetric gross primary production were similar when the estuary was completely ice-covered and ice-free, and the ecosystem was on average net autotrophic during ice melt and net heterotrophic following ice melt. I present a method for incorporating the isotopic composition of H 2 O into the O 2 isotope-based productivity calculations, which increases the estimated gross primary production in this study by 46-97 %.In summary, I describe a new noble gas analysis system and apply O 2 and inert gas observations in new ways to study chemical, biological, and physical processes in coastal waters.

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An organic carbon budget for coastal Southern California determined by estimates of vertical nutrient flux, net community production and export

Cited by 17 publications

References 56 publications

Contextualizing time-series data: Quantification of short-term regional variability in the San Pedro Channel using high-resolution in situ glider data

Contextualizing time-series data: Quantification of short-term regional variability in the San Pedro Channel using high-resolution in situ glider data

Impact of recently upwelled water on productivity investigated using in situ and incubation‐based methods in Monterey Bay

Insight into chemical, biological, and physical processes in coastal waters from dissolved oxygen and inert gas tracers

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