Knapp Angela N.

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Last Name
Knapp
First Name
Angela N.
ORCID
0000-0001-5575-3382

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  • Dataset
    Dissolved nitrite and ammonium concentration data from R/V Atlantis (AT15-61) cruise in Jan-Feb 2010 and R/V Melville (MV1104) cruise in Mar-Apr 2011 in the Eastern Tropical South Pacific
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2021-05-07) Casciotti, Karen L. ; Santoro, Alyson E. ; Knapp, Angela N.
    Dissolved nitrite ([NO2-]) and ammonium ([NH4+]) concentration data were collected on two cruises in the Eastern Tropical South Pacific. Data from R/V Atlantis (AT15-61) cruise collected in Jan-Feb 2010 and data from R/V Melville (MV1104) cruise collected in Mar-Apr 2011 as part of the Microbial Nitrification project. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/820165
  • Dataset
    Nutrients, nitrate isotopes, and DON isotopes data from samples collected in the Gulf of Mexico on R/V Nancy Foster cruises NF1704 and NF1802 in May 2017 and May 2018
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2021-01-04) Knapp, Angela N. ; Landry, Michael R.
    This data set includes water column inorganic nutrient and dissolved organic nitrogen (DON) concentration and nitrate+nitrite d15N and d18O and DON δ15N measurements from May 2017 and May 2018 cruises in the North/Central Gulf of Mexico that were used together with sinking particulate N data to construct δ15N budgets. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/834984
  • Dataset
    Processed CTD data from cruises R/V Atlantis (AT15-61) in Jan-Feb 2010 and R/V Melville (MV1104) in Mar-Apr 2011 in the Eastern Tropical South Pacific
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2021-05-07) Casciotti, Karen L. ; Capone, Douglas G. ; Santoro, Alyson E. ; Berelson, William M. ; Knapp, Angela N.
    Processed CTD data from cruises R/V Atlantis (AT15-61) in Jan-Feb 2010 and R/V Melville (MV1104) in Mar-Apr 2011 in the Eastern Tropical South Pacific For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/827861
  • Dataset
    Water column nitrate+nitrite d15N and d18O and total dissolved nitrogen d15N measurements from R/V Ka`imikai-O-Kanaloa cruise KOK1806 (HOT LAVA) in July 2018
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2019-06-18) Knapp, Angela N.
    This data set includes water column nitrate+nitrite and total dissolved nitrogen d15N measurements. These measurements were used to address the source of nitrate+nitrite in surface waters observed after the 2018 Kilauea eruption entered the ocean, leading to enhanced surface ocean chlorophyll. The results are consistent with an upwelling source of nitrate+nitrite from ~400 m driven by hot lava entering the ocean, leading to increased buoyancy of waters, driving "roils" (see F. J. Sansone, and J. A. Resing, 1995, J. Geophys. Res. Oceans). These data are also used as evidence that biological nitrogen fixation did not contribute to the nitrate+nitrite observed in surface waters. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/770818
  • Dataset
    DOP concentration observations from the global ocean between 1990 and 2021 (DOP N2 fixation and export production project)
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2021-10-06) Knapp, Angela N. ; Letscher, Robert T. ; Liang, Zhou
    DOP (Dissolved Organic Phosphorus) concentration observations in the global ocean between 1990 and 2021 over multiple deployments. DOP concentrations in this study were calculated as the difference between TDP concentrations and PO43- concentrations of samples. For DOP concentrations reported here, TDP concentrations were measured by the ash/hydrolysis method based on Monaghan and Ruttenberg, 1999. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/855139
  • Dataset
    Water column nitrate+nitrite d15N and d18O from samples collected during R/V Pelican and R/V F.G. Walton Smith cruises in the Gulf of Mexico and Florida Straits between 2011 and 2018
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2019-11-26) Knapp, Angela N.
    This data set includes water column nitrate+nitrite d15N and d18O measurements from the Gulf of Mexico and Florida Straits. These measurements were used to address whether Mississippi River nitrate is entrained in Loop Current waters and potentially exported from the Gulf of Mexico to the North Atlantic. Water samples were collected during R/V Pelican and R/V F.G. Walton Smith cruises in the Gulf of Mexico and Florida Straits between 2011 and 2018. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/782518
  • Dataset
    DOP concentration observations from the global ocean between 1990 and 2021 (DOP N2 fixation and export production project)
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-10-18) Knapp, Angela N. ; Letscher, Robert T. ; Liang, Zhou
    DOP (Dissolved Organic Phosphorus) concentration observations in the global ocean between 1990 and 2021 over multiple deployments. DOP concentrations in this study were calculated as the difference between TDP concentrations and SRP concentrations of samples. For DOP concentrations reported here, TDP concentrations were measured by the ash/hydrolysis method based on Monaghan and Ruttenberg, 1999. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/855139
  • Dataset
    DOP concentration observations from the global ocean between 1990 and 2021 (DOP N2 fixation and export production project)
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-02-15) Knapp, Angela N. ; Letscher, Robert T. ; Liang, Zhou
    DOP (Dissolved Organic Phosphorus) concentration observations in the global ocean between 1990 and 2021 over multiple deployments. DOP concentrations in this study were calculated as the difference between TDP concentrations and SRP concentrations of samples. For DOP concentrations reported here, TDP concentrations were measured by the ash/hydrolysis method based on Monaghan and Ruttenberg, 1999. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/855139
  • Dataset
    Water column nitrate plus nitrite isotope measurements from seawater collected November 2019 aboard R/V L’Atalante in the Western Tropical South Pacific.
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-03-04) Knapp, Angela N. ; Forrer, Heather J.
    Here we present nitrate plus nitrite isotopic data from the TONGA 2019 research cruise to the Western Tropical South Pacific. These data were collected along a transect focusing on the impacts on biological productivity and the biological carbon pump from shallow hydrothermal sources of trace elements. Notably, these data show that the subsurface nitrate plus nitrite isotopes were low, 2 to 3 per mil, in the vicinity of the hydrothermal vents. Subsurface nitrate plus nitrite isotopes were higher, 4 to 7 per mil, at stations further from the vents. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/869963
  • Dataset
    Dissolved and sinking particulate organic nitrogen data from a large volume mesocosm experiment in the Noumea Lagoon, New Caledonia, measured from January to February 2013
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2019-11-21) Knapp, Angela N.
    This dataset includes water column dissolved organic nitrogen (DON) concentration and d15N data, as well as sinking particulate nitrogen d15N (“PNsink d15N”) data. These samples were collected inside triplicate (“M1”, “M2”, and “M3”) large volume (i.e., 2.3 m diameter, 15 m deep) mesocosm experiments deployed in a lagoon off of Noumea, New Caledonia. DON samples were collected at 6 m depth daily by a Teflon pump and PVC tubing. PNsink d15N samples were collected daily by SCUBA divers who removed a screw-top plastic bottle from the bottom of the plastic mesocosm. “Swimmers” were removed from the PNsink d15N samples prior to analysis. These measurements were made as part of project "VAriability of vertical and tropHIc transfer of diazotroph derived N in the south wEst Pacific" (VAHINE) to study the fate of fixed nitrogen in the oceanic pelagic food web and its potential impact on carbon export. The field campaign of VAHINE took place in the South West Pacific (New Caledonia) in January and February of 2013 and involved 16 scientists from France, Israel, Germany and the USA. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/739646
  • Article
    A global ocean dissolved organic phosphorus concentration database (DOPv2021)
    (Nature Research, 2022-12-16) Liang, Zhou ; McCabe, Kelly ; Fawcett, Sarah E. ; Forrer, Heather J. ; Hashihama, Fuminori ; Jeandel, Catherine ; Marconi, Dario ; Planquette, Hélène ; Saito, Mak A. ; Sohm, Jill A. ; Thomas, Rachel K. ; Letscher, Robert T. ; Knapp, Angela N.
    Dissolved organic phosphorus (DOP) concentration distributions in the global surface ocean inform our understanding of marine biogeochemical processes such as nitrogen fixation and primary production. The spatial distribution of DOP concentrations in the surface ocean reflect production by primary producers and consumption as an organic nutrient by phytoplankton including diazotrophs and other microbes, as well as other loss processes such as photolysis. Compared to dissolved organic carbon and nitrogen, however, relatively few marine DOP concentration measurements have been made, largely due to the lack of automated analysis techniques. Here we present a database of marine DOP concentration measurements (DOPv2021) that includes new (n = 730) and previously published (n = 3140) observations made over the last ~30 years (1990-2021), including 1751 observations in the upper 50 m. This dataset encompasses observations from all major ocean basins including the poorly represented Indian, South Pacific, and Southern Oceans and provides insight into spatial distributions of DOP in the ocean. It is also valuable for researchers who work on marine primary production and nitrogen fixation.
  • Article
    Dominant heterocyclic composition of dissolved organic nitrogen in the ocean: A new paradigm for cycling and persistence
    (National Academy of Sciences, 2023-11-28) Broek, Taylor A. B. ; McCarthy, Matthew D. ; Ianiri, Hope L. ; Vaughn, John S. ; Mason, Harris E. ; Knapp, Angela N.
    Marine dissolved organic nitrogen (DON) is one of the planet’s largest reservoirs of fixed N, which persists even in the N-limited oligotrophic surface ocean. The vast majority of the ocean’s total DON reservoir is refractory (RDON), primarily composed of low molecular weight (LMW) compounds in the subsurface and deep sea. However, the composition of this major N pool, as well as the reasons for its accumulation and persistence, are not understood. Past characterization of the analytically more tractable, but quantitatively minor, high molecular weight (HMW) DON fraction revealed a functionally simple amide-dominated composition. While extensive work in the past two decades has revealed enormous complexity and structural diversity in LMW dissolved organic carbon, no efforts have specifically targeted LMW nitrogenous molecules. Here, we report the first coupled isotopic and solid-state NMR structural analysis of LMW DON isolated throughout the water column in two ocean basins. Together these results provide a first view into the composition, potential sources, and cycling of this dominant portion of marine DON. Our data indicate that RDON is dominated by 15N-depleted heterocyclic-N structures, entirely distinct from previously characterized HMW material. This fundamentally new view of marine DON composition suggests an important structural control for RDON accumulation and persistence in the ocean. The mechanisms of production, cycling, and removal of these heterocyclic-N-containing compounds now represents a central challenge in our understanding of the ocean’s DON reservoir.