Borges Alberto V.

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Borges
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Alberto V.
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  • Article
    Ideas and perspectives: a strategic assessment of methane and nitrous oxide measurements in the marine environment
    (European Geosciences Union, 2020-11-26) Wilson, Samuel T. ; Al-Haj, Alia N. ; Bourbonnais, Annie ; Frey, Claudia ; Fulweiler, Robinson W. ; Kessler, John D. ; Marchant, Hannah K. ; Milucka, Jana ; Ray, Nicholas E. ; Suntharalingam, Parvadha ; Thornton, Brett F. ; Upstill-Goddard, Robert C. ; Weber, Thomas S. ; Arévalo-Martínez, Damian L. ; Bange, Hermann W. ; Benway, Heather M. ; Bianchi, Daniele ; Borges, Alberto V. ; Chang, Bonnie X. ; Crill, Patrick M. ; del Valle, Daniela A. ; Farías, Laura ; Joye, Samantha B. ; Kock, Annette ; Labidi, Jabrane ; Manning, Cara C. ; Pohlman, John W. ; Rehder, Gregor ; Sparrow, Katy J. ; Tortell, Philippe D. ; Treude, Tina ; Valentine, David L. ; Ward, Bess B. ; Yang, Simon ; Yurganov, Leonid N.
    In the current era of rapid climate change, accurate characterization of climate-relevant gas dynamics – namely production, consumption, and net emissions – is required for all biomes, especially those ecosystems most susceptible to the impact of change. Marine environments include regions that act as net sources or sinks for numerous climate-active trace gases including methane (CH4) and nitrous oxide (N2O). The temporal and spatial distributions of CH4 and N2O are controlled by the interaction of complex biogeochemical and physical processes. To evaluate and quantify how these mechanisms affect marine CH4 and N2O cycling requires a combination of traditional scientific disciplines including oceanography, microbiology, and numerical modeling. Fundamental to these efforts is ensuring that the datasets produced by independent scientists are comparable and interoperable. Equally critical is transparent communication within the research community about the technical improvements required to increase our collective understanding of marine CH4 and N2O. A workshop sponsored by Ocean Carbon and Biogeochemistry (OCB) was organized to enhance dialogue and collaborations pertaining to marine CH4 and N2O. Here, we summarize the outcomes from the workshop to describe the challenges and opportunities for near-future CH4 and N2O research in the marine environment.
  • Article
    An intercomparison of oceanic methane and nitrous oxide measurements
    (Copernicus Publications on behalf of the European Geosciences Union, 2018-10-05) Wilson, Samuel T. ; Bange, Hermann W. ; Arévalo-Martínez, Damian L. ; Barnes, Jonathan ; Borges, Alberto V. ; Brown, Ian ; Bullister, John L. ; Burgos, Macarena ; Capelle, David W. ; Casso, Michael A. ; de la Paz, Mercedes ; Farías, Laura ; Fenwick, Lindsay ; Ferrón, Sara ; Garcia, Gerardo ; Glockzin, Michael ; Karl, David M. ; Kock, Annette ; Laperriere, Sarah ; Law, Cliff S. ; Manning, Cara C. ; Marriner, Andrew ; Myllykangas, Jukka-Pekka ; Pohlman, John W. ; Rees, Andrew P. ; Santoro, Alyson E. ; Tortell, Philippe D. ; Upstill-Goddard, Robert C. ; Wisegarver, David P. ; Zhang, Gui-Ling ; Rehder, Gregor
    Large-scale climatic forcing is impacting oceanic biogeochemical cycles and is expected to influence the water-column distribution of trace gases, including methane and nitrous oxide. Our ability as a scientific community to evaluate changes in the water-column inventories of methane and nitrous oxide depends largely on our capacity to obtain robust and accurate concentration measurements that can be validated across different laboratory groups. This study represents the first formal international intercomparison of oceanic methane and nitrous oxide measurements whereby participating laboratories received batches of seawater samples from the subtropical Pacific Ocean and the Baltic Sea. Additionally, compressed gas standards from the same calibration scale were distributed to the majority of participating laboratories to improve the analytical accuracy of the gas measurements. The computations used by each laboratory to derive the dissolved gas concentrations were also evaluated for inconsistencies (e.g., pressure and temperature corrections, solubility constants). The results from the intercomparison and intercalibration provided invaluable insights into methane and nitrous oxide measurements. It was observed that analyses of seawater samples with the lowest concentrations of methane and nitrous oxide had the lowest precisions. In comparison, while the analytical precision for samples with the highest concentrations of trace gases was better, the variability between the different laboratories was higher: 36% for methane and 27% for nitrous oxide. In addition, the comparison of different batches of seawater samples with methane and nitrous oxide concentrations that ranged over an order of magnitude revealed the ramifications of different calibration procedures for each trace gas. Finally, this study builds upon the intercomparison results to develop recommendations for improving oceanic methane and nitrous oxide measurements, with the aim of precluding future analytical discrepancies between laboratories.
  • Article
    Rapid decline of the CO2 buffering capacity in the North Sea and implications for the North Atlantic Ocean
    (American Geophysical Union, 2007-10-06) Thomas, Helmuth ; Prowe, A. E. Friederike ; van Heuven, Steven ; Bozec, Yann ; Baar, Hein J. W. de ; Schiettecatte, Laure-Sophie ; Suykens, Kim ; Kone, Mathieu ; Borges, Alberto V. ; Lima, Ivan D. ; Doney, Scott C.
    New observations from the North Sea, a NW European shelf sea, show that between 2001 and 2005 the CO2 partial pressure (pCO2) in surface waters rose by 22 μatm, thus faster than atmospheric pCO2, which in the same period rose approximately 11 μatm. The surprisingly rapid decline in air-sea partial pressure difference (ΔpCO2) is primarily a response to an elevated water column inventory of dissolved inorganic carbon (DIC), which, in turn, reflects mostly anthropogenic CO2 input rather than natural interannual variability. The resulting decline in the buffering capacity of the inorganic carbonate system (increasing Revelle factor) sets up a theoretically predicted feedback loop whereby the invasion of anthropogenic CO2 reduces the ocean's ability to uptake additional CO2. Model simulations for the North Atlantic Ocean and thermodynamic principles reveal that this feedback should be stronger, at present, in colder midlatitude and subpolar waters because of the lower present-day buffer capacity and elevated DIC levels driven either by northward advected surface water and/or excess local air-sea CO2 uptake. This buffer capacity feedback mechanism helps to explain at least part of the observed trend of decreasing air-sea ΔpCO2 over time as reported in several other recent North Atlantic studies.