Methane and trace element samples were collected on GEOTRACES GP15 Pacific Meridional Transect (PMT) cruise conducted between the Aleutian Islands (57 °N) and Tahiti (20 °S) from September to November 2018. Uncertainty in methane air-sea exchange fluxes was determined using a propagation of errors approach. Fluxes ranged from -0.88 to 4.9 µmol CH4 m-2 d-1. Average CH4 flux along the Alaskan margin was 2.2 ± 2.9 µmol CH4 m-2 d-1. Methane fluxes decreased moving southward and increased to their open ocean maximum around 20 °N before declining in equatorial waters. Near 20 °N, phosphorus-limiting conditions were observed, suggesting methylphosphonate (MPn) utilization may have occurred to elevate CH4 fluxes. Methane fluxes measured at open ocean stations ranged from -0.31 to 2.9 µmol CH4 m-2 d-1, matching those reported in previous studies. Atmospheric methane and near-surface dissolved methane concentrations differed significantly between the hemispheres (paired Student’s t test, p < 0.01). The temperate North Pacific average CH4 fluxes (0.40 ± 0.76 µmol CH4 m-2 d-1) significantly differed from average fluxes measured in the subtropical North Pacific (1.5 ± 0.80 µmol CH4 m-2 d-1; p < 0.01) and the equatorial Pacific (0.92 ± 0.44 µmol CH4 m-2 d-1; p < 0.05). Lanthanum (La) to ytterbium (Yb) ratios and light rare earth element (LREEs) to heavy (HREEs) ratios were lower in South Pacific compared to North Pacific, indicating possible methane oxidation through use of LREEs as enzyme co-factors.
","abstract_html":"<p>Methane and trace element samples were collected on GEOTRACES GP15 Pacific Meridional Transect (PMT) cruise conducted between the Aleutian Islands (57 °N) and Tahiti (20 °S) from September to November 2018. Uncertainty in methane air-sea exchange fluxes was determined using a propagation of errors approach. Fluxes ranged from -0.88 to 4.9 µmol CH<sub>4</sub> m<sup>-2</sup> d<sup>-1</sup>. Average CH<sub>4</sub> flux along the Alaskan margin was 2.2 ± 2.9 µmol CH<sub>4</sub> m<sup>-2</sup> d<sup>-1</sup>. Methane fluxes decreased moving southward and increased to their open ocean maximum around 20 °N before declining in equatorial waters. Near 20 °N, phosphorus-limiting conditions were observed, suggesting methylphosphonate (MPn) utilization may have occurred to elevate CH<sub>4</sub> fluxes. Methane fluxes measured at open ocean stations ranged from -0.31 to 2.9 µmol CH<sub>4</sub> m<sup>-2</sup> d<sup>-1</sup>, matching those reported in previous studies. Atmospheric methane and near-surface dissolved methane concentrations differed significantly between the hemispheres (paired Student’s t test, p < 0.01). The temperate North Pacific average CH<sub>4</sub> fluxes (0.40 ± 0.76 µmol CH<sub>4</sub> m<sup>-2</sup> d<sup>-1</sup>) significantly differed from average fluxes measured in the subtropical North Pacific (1.5 ± 0.80 µmol CH<sub>4</sub> m<sup>-2</sup> d<sup>-1</sup>; p < 0.01) and the equatorial Pacific (0.92 ± 0.44 µmol CH<sub>4</sub> m<sup>-2</sup> d<sup>-1</sup>; p < 0.05). Lanthanum (La) to ytterbium (Yb) ratios and light rare earth element (LREEs) to heavy (HREEs) ratios were lower in South Pacific compared to North Pacific, indicating possible methane oxidation through use of LREEs as enzyme co-factors.</p>","abstract_has_math":false,"creators":["Raney, Sarah"],"institution":null,"degree_name":"Master of Science (MS)","degree_level":"Masters Thesis","degree_discipline":null,"degree_department":null,"school":null,"contributors":["Dr. Alan Shiller","Dr. Christopher Hayes","Dr. Kevin Dillon"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2022,"date_issued":"2022-05-01T07:00:00Z","date_published":"2022-05-01T07:00:00Z","updated_at":"2026-07-24T05:45:33Z","subjects":["methane","biogeochemistry","oceanography","Pacific","air-sea exchange","trace elements","Environmental Chemistry"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://aquila.usm.edu/masters_theses/890","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Dr. Alan Shiller","Dr. Christopher Hayes","Dr. Kevin Dillon"]},{"key":"dc:creator","label":"Author","values":["Raney, Sarah"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2022-05-31T07:00:00Z"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Masters Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science (MS)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["methane","biogeochemistry","oceanography","Pacific","air-sea exchange","trace elements","Environmental Chemistry"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://aquila.usm.edu/masters_theses/890"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Methane and trace element samples were collected on GEOTRACES GP15 Pacific Meridional Transect (PMT) cruise conducted between the Aleutian Islands (57 °N) and Tahiti (20 °S) from September to November 2018. Uncertainty in methane air-sea exchange fluxes was determined using a propagation of errors approach. Fluxes ranged from -0.88 to 4.9 µmol CH4 m-2 d-1. Average CH4 flux along the Alaskan margin was 2.2 ± 2.9 µmol CH4 m-2 d-1. Methane fluxes decreased moving southward and increased to their open ocean maximum around 20 °N before declining in equatorial waters. Near 20 °N, phosphorus-limiting conditions were observed, suggesting methylphosphonate (MPn) utilization may have occurred to elevate CH4 fluxes. Methane fluxes measured at open ocean stations ranged from -0.31 to 2.9 µmol CH4 m-2 d-1, matching those reported in previous studies. Atmospheric methane and near-surface dissolved methane concentrations differed significantly between the hemispheres (paired Student’s t test, p < 0.01). The temperate North Pacific average CH4 fluxes (0.40 ± 0.76 µmol CH4 m-2 d-1) significantly differed from average fluxes measured in the subtropical North Pacific (1.5 ± 0.80 µmol CH4 m-2 d-1; p < 0.01) and the equatorial Pacific (0.92 ± 0.44 µmol CH4 m-2 d-1; p < 0.05). Lanthanum (La) to ytterbium (Yb) ratios and light rare earth element (LREEs) to heavy (HREEs) ratios were lower in South Pacific compared to North Pacific, indicating possible methane oxidation through use of LREEs as enzyme co-factors.
"]},{"key":"dc:title","label":"Title","values":["Understanding Biogeochemical and Physical Controls on Methane Air-Sea Exchange Fluxes in the Pacific Ocean"]}]}],"canonical_facts":{"dc:contributor":["Dr. Alan Shiller","Dr. Christopher Hayes","Dr. Kevin Dillon"],"dc:creator":["Raney, Sarah"],"dc:date.available":["2022-05-31T07:00:00Z"],"dc:description.abstract":["Methane and trace element samples were collected on GEOTRACES GP15 Pacific Meridional Transect (PMT) cruise conducted between the Aleutian Islands (57 °N) and Tahiti (20 °S) from September to November 2018. Uncertainty in methane air-sea exchange fluxes was determined using a propagation of errors approach. Fluxes ranged from -0.88 to 4.9 µmol CH4 m-2 d-1. Average CH4 flux along the Alaskan margin was 2.2 ± 2.9 µmol CH4 m-2 d-1. Methane fluxes decreased moving southward and increased to their open ocean maximum around 20 °N before declining in equatorial waters. Near 20 °N, phosphorus-limiting conditions were observed, suggesting methylphosphonate (MPn) utilization may have occurred to elevate CH4 fluxes. Methane fluxes measured at open ocean stations ranged from -0.31 to 2.9 µmol CH4 m-2 d-1, matching those reported in previous studies. Atmospheric methane and near-surface dissolved methane concentrations differed significantly between the hemispheres (paired Student’s t test, p < 0.01). The temperate North Pacific average CH4 fluxes (0.40 ± 0.76 µmol CH4 m-2 d-1) significantly differed from average fluxes measured in the subtropical North Pacific (1.5 ± 0.80 µmol CH4 m-2 d-1; p < 0.01) and the equatorial Pacific (0.92 ± 0.44 µmol CH4 m-2 d-1; p < 0.05). Lanthanum (La) to ytterbium (Yb) ratios and light rare earth element (LREEs) to heavy (HREEs) ratios were lower in South Pacific compared to North Pacific, indicating possible methane oxidation through use of LREEs as enzyme co-factors.
"],"dc:identifier":["https://aquila.usm.edu/masters_theses/890"],"dc:subject":["methane","biogeochemistry","oceanography","Pacific","air-sea exchange","trace elements","Environmental Chemistry"],"dc:title":["Understanding Biogeochemical and Physical Controls on Methane Air-Sea Exchange Fluxes in the Pacific Ocean"],"thesis:degree_level":["Masters Thesis"],"thesis:degree_name":["Master of Science (MS)"]},"updated_at":"2026-07-24T05:45:33Z"}