Metabolic balance of coastal Antarctic waters revealed by autonomous pCO2 and ΔO2/Ar measurements

Tortell, Philippe D.; Asher, Elizabeth; Ducklow, Hugh W.; Goldman, Johanna A. L.; Dacey, John W. H.; Grzymski, Joseph J.; Young, Jodi N.; Kranz, Sven A.; Bernard, Kim S.; Morel, François M. M.

doi:10.1002/2014gl061266

Cited by 65 publications

(87 citation statements)

References 35 publications

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“…Due to the spatial variability in O 2 , we are not able to determine the rate of change in ∆(O 2 /Ar) with time, which is needed for a non-steady state calculation of NOP (Hamme et al, 2012;Tortell et al, 2014;Wilson et al, 2015;Palevsky et al, 2016a). For example, we can calculate a linear regression of ∆(O 2 /Ar) versus time over any 48 h period in Phase 2 (beginning 30 September 10:10 or later), with the 48 h period chosen to prevent diurnal cycling in O 2 from biasing the slope (Hamme et al, 2012).…”

Section: Measured At 50 M Depth; All Other Methods Integrated To the mentioning

confidence: 99%

“…transect cruises) or sampling at the same location occurs very far apart in time (much longer than the residence time of O 2 in the mixed layer, which is typically on the order of two weeks), making it necessary to assume the gases are at steady state in order to calculate NCP and GPP (Stanley et al, 2010;Giesbrecht et al, 2012;Munro et al, 2013). When a higher-frequency time-series of measurements is obtained (as occurred during this cruise), investigators can quantify the change in [O 2 ] and 17 ∆ with time and include these terms in the productivity estimates when appropriate (Hamme et al, 2012;Tortell et al, 2014;Wilson et al, 2015). Because the calculations of NCP and GPP from O 2 /Ar and triple oxygen isotope data can vary substantially between studies, we outline our calculations in section 4.5.…”

Section: O 2 Mass Balancementioning

confidence: 99%

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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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Section: Measured At 50 M Depth; All Other Methods Integrated To the mentioning

confidence: 99%

Section: O 2 Mass Balancementioning

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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“…This seasonal cycle is driven by the physical changes associated with ice retreat and its amplitude increases southward, with maximum biomass and productivity in coastal and shelf areas (Smith and Nelson, 1985;Arrigo and van Dijken, 2003,b;Arrigo et al, 2008a,b;Westwood et al, 2010;Wright et al, 2010). The Western Antarctic Peninsula (WAP) has chlorophyll concentrations that can reach up to 50 g L −1 in waters off Palmer Station (Tortell et al, 2014;Kranz et al, 2015;Young et al, 2015;PALTER database), while in East Antarctic waters maximum chlorophyll concentrations are commonly more than an order of magnitude less Wright et al, 2010). However, while the magnitude of the blooms may differ, the successional sequence of the phytoplankton in East and West Antarctic waters appear to be similar (e.g.…”

Section: Southern Ocean Primary Productivitymentioning

confidence: 99%

Southern Ocean phytoplankton physiology in a changing climate

Petrou

Kranz

Trimborn

et al. 2016

Journal of Plant Physiology

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119

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Please cite this article in press as: Petrou, K., et al., Southern Ocean phytoplankton physiology in a changing climate. J Plant Physiol (2016), http://dx.doi.org/10.1016/j.jplph.2016.05.004 ARTICLE IN PRESS a b s t r a c tThe Southern Ocean (SO) is a major sink for anthropogenic atmospheric carbon dioxide (CO 2 ), potentially harbouring even greater potential for additional sequestration of CO 2 through enhanced phytoplankton productivity. In the SO, primary productivity is primarily driven by bottom up processes (physical and chemical conditions) which are spatially and temporally heterogeneous. Due to a paucity of trace metals (such as iron) and high variability in light, much of the SO is characterised by an ecological paradox of high macronutrient concentrations yet uncharacteristically low chlorophyll concentrations. It is expected that with increased anthropogenic CO 2 emissions and the coincident warming, the major physical and chemical process that govern the SO will alter, influencing the biological capacity and functioning of the ecosystem. This review focuses on the SO primary producers and the bottom up processes that underpin their health and productivity. It looks at the major physico-chemical drivers of change in the SO, and based on current physiological knowledge, explores how these changes will likely manifest in phytoplankton, specifically, what are the physiological changes and floristic shifts that are likely to ensue and how this may translate into changes in the carbon sink capacity, net primary productivity and functionality of the SO.

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“…Water mass properties are strongly influenced by subsurface intrusions onto the continental shelf of warm, nutrient-and dissolved inorganic carbon (DIC)-rich Upper Circumpolar Deep Water (UCDW), which appears to be modulated by topographic depressions and canyons Dinniman et al, 2011;Martinson and McKee, 2012). In winter, respiration processes and the entrained deep CO 2 -rich water increase the DIC concentration in surface waters to supersaturated levels of CO 2 with respect to the atmosphere (Carrillo et al, 2004;Wang et al, 2009;Tortell et al, 2014;Legge et al, 2015). From austral spring through summer, sea ice retreats from north to south and from offshore to inshore (Smith and Stammerjohn, 2001).…”

Section: Introductionmentioning

confidence: 99%

Two decades of inorganic carbon dynamics along the West Antarctic Peninsula

et al. 2015

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Abstract. We present 20 years of seawater inorganic carbon measurements collected along the western shelf and slope of the Antarctic Peninsula. Water column observations from summertime cruises and seasonal surface underway pCO 2 measurements provide unique insights into the spatial, seasonal, and interannual variability in this dynamic system. Discrete measurements from depths > 2000 m align well with World Ocean Circulation Experiment observations across the time series and underline the consistency of the data set. Surface total alkalinity and dissolved inorganic carbon data showed large spatial gradients, with a concomitant wide range of arag (< 1 up to 3.9). This spatial variability was mainly driven by increasing influence of biological productivity towards the southern end of the sampling grid and meltwater input along the coast towards the northern end. Large inorganic carbon drawdown through biological production in summer caused high near-shore arag despite glacial and seaice meltwater input. In support of previous studies, we observed Redfield behavior of regional C / N nutrient utilization, while the C / P (80.5 ± 2.5) and N / P (11.7 ± 0.3) molar ratios were significantly lower than the Redfield elemental stoichiometric values. Seasonal salinity-based predictions of arag suggest that surface waters remained mostly supersaturated with regard to aragonite throughout the study. However, more than 20 % of the predictions for winters and springs between 1999 and 2013 resulted in arag < 1.2. Such low levels of arag may have implications for important organisms such as pteropods. Even though we did not detect any statistically significant long-term trends, the combination of ongoing ocean acidification and freshwater input may soon induce more unfavorable conditions than the ecosystem experiences today.

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Metabolic balance of coastal Antarctic waters revealed by autonomous pCO₂ and ΔO₂/Ar measurements

Cited by 65 publications

References 35 publications

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

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

Southern Ocean phytoplankton physiology in a changing climate

Two decades of inorganic carbon dynamics along the West Antarctic Peninsula

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