A gas tension device for the mesopelagic zone

Reed, Andrew; McNeil, Craig; D’Asaro, Eric A.; Altabet, Mark A.; Bourbonnais, Annie; Johnson, Bruce D.

doi:10.1016/j.dsr.2018.07.007

Cited by 8 publications

(12 citation statements)

References 31 publications

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“…tion of flow onto the instruments' sensing faces (Figure 1) are important for minimizing response times and maintaining neutral hydrostatic pressure within the system. Flow rate changes through the instrument loop following pulses in the discharge from the ship's seawater supply induce hydrostatic effects on GTD measurements analogous to pressure changes during depth profiling (Reed et al, 2018). The PIGI system was designed to minimize these flow-dependent effects and includes flow-rate monitoring for diagnosing such artifacts.…”

Section: Component~cost (Usd)mentioning

confidence: 99%

“…This limits the capacity for truly autonomous NCP derivation from underway platforms and volunteer observing ships (VOS). Recent technological advances in O 2 optodes and gas tension devices (GTDs; Tengberg et al, 2006;Reed et al, 2018) have enabled high-resolution, unattended measurements of seawater O 2 and N 2 (McNeil et al, 2005). Ongoing work by our group has evaluated the potential to estimate NCP from O 2 /N 2 ratios (i.e., ΔO 2 /N 2 ) in a manner analogous to ΔO 2 /Ar (manuscripts in preparation).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The Pressure of In Situ Gases Instrument (PIGI) for Autonomous Shipboard Measurement of Dissolved O2 and N2 in Surface Ocean Waters

Izett¹,

Tortell²

2020

Oceanog

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Section: Component~cost (Usd)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Pressure of In Situ Gases Instrument (PIGI) for Autonomous Shipboard Measurement of Dissolved O2 and N2 in Surface Ocean Waters

Izett¹,

Tortell²

2020

Oceanog

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“…In order to predict ecosystem-level responses to climate change impacts on marine biogeochemical cycling and biomass production, it is crucial that we significantly increase capacity for NCP observations. The development of O 2 optodes (Tengberg et al 2006) and gas tension devices (GTD; Reed et al 2018) capable of stable and accurate in-situ measurements provides new opportunities for autonomous NCP surveys on research vessels, ships of opportunity, or autonomous surface vehicles. Using observations of O 2 from the optode, and the seawater total dissolved gas pressure (i.e., the sum of all gas partial pressures) from the GTD, seawater nitrogen (N 2 ) concentrations can be estimated (McNeil et al 1995).…”

mentioning

confidence: 99%

ΔO₂/N₂′ as a tracer of mixed layer net community production: Theoretical considerations and proof‐of‐concept

Izett

Tortell

2021

Limnology & Ocean Methods

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We present a method to estimate net community production (NCP) from underway ΔO2/N2 observations. This approach, based on high‐resolution measurements using relatively low‐cost O2‐optode and gas tension device instrumentation, provides an alternative to NCP derivation from mass spectrometric analysis of ΔO2/Ar. To fully exploit ΔΟ2/Ν2 as an NCP tracer, it is necessary to account for differences in surface water argon (Ar) and nitrogen (Ν2) saturation states. Using a one‐dimensional mixed layer model, evaluated against field observations, we examined the divergence between ΔO2/Ar and ΔΟ2/Ν2 resulting from various physical processes. Results show that changes in sea surface temperature, bubble injection and vertical mixing can decouple mixed layer ΔO2/Ar and ΔΟ2/Ν2, while biological N2‐fixation has a negligible effect. Based on readily available environmental data, we developed a framework to correct for Ar and N2 solubility differences, yielding a new tracer, ΔΟ2/Ν2′, that is a near‐analog of ΔO2/Ar. Through model simulations and field measurements, we show that ΔΟ2/Ν2′ provides an excellent approximation to ΔO2/Ar, and that uncertainty and biases in ΔO2/N2′ are small relative to other errors in NCP calculations. This work demonstrates the potential for ΔO2/N2′ measurements to significantly expand NCP estimates from a variety of sampling platforms.

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“…Deep-sea membrane inlets use a nonporous membrane, made out of a gas-permeable polymer like PDMS or Teflon AF, supported mechanically by a frit. Membrane inlets have been used successfully in the deep-sea by a variety of dissolved gas instruments [81][82][83][84][85][86][87][88][89]. Unfortunately, the total gas transport rate achievable with a depth-compatible membrane inlet is very low, which makes achieving a reasonable time response difficult.…”

Section: Technological Gap 1: Ocean Inorganic Carbon Systemmentioning

confidence: 99%

“…Nonporous membranes use gas-permeable polymers, such as PDMS or Teflon AF, to isolate seawater from an internal gas volume, and have been used by researchers in the deep-sea for a variety of dissolved gas instruments [81][82][83][84][85][86][87][88][89]139]. Tubular and flat membranes, on the order of 10-100 𝜇m thick, can be supported mechanically with a porous frit, or fabricated as a composite, to withstand deep-sea pressures [81-83, 86, 89, 139] i .…”

Section: Introductionmentioning

confidence: 99%

Developing in situ instrumentation to monitor anthropogenic change

Colson¹

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To predict and mitigate anthropogenic impacts on the ocean, we must understand the underlying systems that govern the ocean’s response to inputs (e.g. carbon dioxide, pollutants). Analytical models can be used to generate predictions and simulate intervention strategies, but they must be grounded with empirical observations. Unfortunately, there exists a technological gap: in situ instrumentation is often lacking or nonexistent for key parameters influenced by anthropogenic inputs. While discrete bottle samples can be collected and analyzed for these parameters, their limited spatiotemporal resolution constrains scientific inquiry. To help fill the technological gap, this dissertation presents the development of instrumentation for the ocean inorganic carbon system and microplastics. The first few chapters present the development process of CSPEC, a deep-sea laser spectrometer designed to measure the ocean carbon system through alternating measurements of the partial pressure of carbon dioxide (pCO2) and dissolved inorganic carbon (DIC). CSPEC uses tunable diode laser absorption spectroscopy (TDLAS) to measure the CO2 content of dissolved gas extracted via a membrane inlet. Chapter 2 derives membrane equilibration dynamics from first principles, thus enabling informed design decisions. The analytical results showed that cross-sensitivity to other dissolved gases can be introduced by the equilibration method, regardless of the specificity of the gas-side instrumentation. A new method, hybrid equilibration, leverages the membrane equilibration dynamics to improve time response without incurring cross-sensitivity. Chapter 3 presents POCO, a surface pCO2 instrument that employs TDLAS and a depth-compatible membrane inlet. Through laboratory and field-testing, POCO demonstrated that hybrid equilibration overcame the gas flux limitation of deep-sea membrane inlets. Chapter 4 presents CSPEC, which successfully mapped the carbon system near different hydrothermal features at 2000 m in Guaymas Basin, becoming one of the first DIC instruments field-tested at depth. Chapter 5 introduces impedance spectroscopy for quantifying microplastics directly in water. Microplastics were successfully counted, sized, and differentiated from biology in the laboratory: a step toward in situ quantification. The analytical tools and measurement systems presented in this dissertation represent a significant step towards increasing the spatiotemporal resolution of carbon system and microplastic measurements, thus enabling broader scientific inquiry in the future.

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A gas tension device for the mesopelagic zone

Cited by 8 publications

References 31 publications

The Pressure of In Situ Gases Instrument (PIGI) for Autonomous Shipboard Measurement of Dissolved O2 and N2 in Surface Ocean Waters

The Pressure of In Situ Gases Instrument (PIGI) for Autonomous Shipboard Measurement of Dissolved O2 and N2 in Surface Ocean Waters

ΔO₂/N₂′ as a tracer of mixed layer net community production: Theoretical considerations and proof‐of‐concept

Developing in situ instrumentation to monitor anthropogenic change

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A gas tension device for the mesopelagic zone

Cited by 8 publications

References 31 publications

The Pressure of In Situ Gases Instrument (PIGI) for Autonomous Shipboard Measurement of Dissolved O2 and N2 in Surface Ocean Waters

The Pressure of In Situ Gases Instrument (PIGI) for Autonomous Shipboard Measurement of Dissolved O2 and N2 in Surface Ocean Waters

ΔO2/N2′ as a tracer of mixed layer net community production: Theoretical considerations and proof‐of‐concept

Developing in situ instrumentation to monitor anthropogenic change

Contact Info

Product

Resources

About

ΔO₂/N₂′ as a tracer of mixed layer net community production: Theoretical considerations and proof‐of‐concept