A durable and inexpensive pump profiler to monitor stratified water columns with high vertical resolution

Hudson, Jeffrey M.; MacDonald, Daniel J.; Estes, Emily R.; Luther, George W.

doi:10.1016/j.talanta.2019.02.076

Cited by 9 publications

(7 citation statements)

References 26 publications

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“…Molecular samples were collected on the same cast where chemical samples were collected either from Niskin bottles (CB2019) or using an underwater pump profiling system (CB2020) to obtain higher vertical sampling resolution (Hudson et al 2019). Particles were then filtered onto Sterivex filters (0.22 μ m) using a peristaltic pump.…”

Section: Methodsmentioning

confidence: 99%

“…The equilibrium N 2 O concentration (N 2 O equlibrium ) was calculated based on the solubility of N 2 O (Weiss and Price 1980) and the gas transfer velocity (k) was estimated based on the parameterization of Wanninkhof (2014). Molecular samples were collected on the same cast where chemical samples were collected either from Niskin bottles (CB2019) or using an underwater pump profiling system (CB2020) to obtain higher vertical sampling resolution (Hudson et al 2019). Particles were then filtered onto Sterivex filters (0.22 μm) using a peristaltic pump.…”

Section: Sample Collection For Chemical and Molecular Analysesmentioning

confidence: 99%

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Nitrous oxide production in the Chesapeake Bay

Tang

Tracey

Carroll

et al. 2022

Limnology & Oceanography

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Estuaries at the global scale are significant but highly uncertain sources of atmospheric nitrous oxide (N 2 O), which is an intense greenhouse gas and ozone depletion agent. As the largest estuary in the United States, the Chesapeake Bay is suggested to be a spatially and temporally variable source and sink of N 2 O. However, limited observations of N 2 O cycling preclude us from estimating and predicting its net N 2 O flux. To improve our mechanistic understanding of the processes that control the N 2 O flux at the point of production, we applied multiple 15 N tracers ( 15 NH þ 4 , 15 N-urea, 15 NO À 2 , and 15 NO À 3 ) to separately track N 2 O production from nitrification and denitrification under in situ and manipulated O 2 concentrations in the Chesapeake Bay. Nitrification was the major N 2 O production pathway in oxic waters (up to 7.5 nmol N 2 O L À1 d À1 ). In contrast, denitrification dominated N 2 O production from hypoxic/anoxic waters (up to 20 nmol N 2 O L À1 d À1 ). N 2 O production from urea was observed for the first time in estuarine waters. The contribution from urea was small, but interestingly, showed a depth pattern distinct from other N 2 O precursors. Experimentally lowering the O 2 concentration substantially enhanced N 2 O production. Therefore, the expansion of hypoxic and anoxic zones in the Chesapeake Bay under climate change as suggested by some climate models may favor the production of N 2 O, potentially providing positive feedback on warming. Overall, our study provides mechanistic constraints on N 2 O dynamics that could benefit modeling studies to better estimate the N 2 O flux in the Chesapeake Bay and other coastal environments.

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Section: Methodsmentioning

confidence: 99%

Section: Sample Collection For Chemical and Molecular Analysesmentioning

confidence: 99%

Nitrous oxide production in the Chesapeake Bay

Tang

Tracey

Carroll

et al. 2022

Limnology & Oceanography

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“…Voltammetric microelectrodes are advantageous because they can achieve high vertical resolution (mm to cm scale) in both sediment cores and the overlying water, while minimally disturbing the sample matrix. [26][27][28][29] Additionally, they can quantify multiple redox-active species (e.g., O 2 , Fe(II), Mn(II), reduced sulfur species), and identify Fe(III)-organic complexes that exist as stable chelates under reducing conditions simultaneously without or minimally altering their native oxidation states. 18 This enables us to rapidly analyze and quantify porewater chemical species as a function of depth and, more importantly, measure the redox-active species in their in situ redox state.…”

Section: Introductionmentioning

confidence: 99%

“…18 This enables us to rapidly analyze and quantify porewater chemical species as a function of depth and, more importantly, measure the redox-active species in their in situ redox state. 18,22,23,28,29 Finally, microelectrodes are robust, relatively inexpensive, and can be coupled with Bluetooth enabled portable, battery-operated potentiostats. These attributes make this system amenable to a wide variety of eld applications.…”

Section: Introductionmentioning

confidence: 99%

“…These attributes make this system amenable to a wide variety of eld applications. 18,20,22,27,29 Our goal was to quantify redox-active species associated with O 2 , Mn and Fe TEA in high, vertical spatial resolution (mm) in Toolik Lake sediment porewater and a microbial iron mat adjacent to the Oksrukuyik Creek (both in Arctic Alaska). Further, we coupled our voltammetric measurements with 16S rRNA gene sequencing to assess how geochemical gradients are inuenced by the composition of the microbial communities at our sites.…”

Section: Introductionmentioning

confidence: 99%

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