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  • 1
    Publication Date: 2010-06-26
    Description: Concentrations of dissolved inorganic carbon (DIC) decrease in the surface mixed layers during spring and summer in most of the oligotrophic ocean. Mass balance calculations require that the missing DIC is converted into particulate carbon by photosynthesis. This DIC uptake represents one of the largest components of net community production in the world ocean. However, mixed-layer waters in these regions of the ocean typically contain negligible concentrations of plant nutrients such as nitrate and phosphate. Combined nutrient supply mechanisms including nitrogen fixation, diffusive transport and vertical entrainment are believed to be insufficient to supply the required nutrients for photosynthesis. The basin-scale potential for episodic nutrient transport by eddy events is unresolved. As a result, it is not understood how biologically mediated DIC uptake can be supported in the absence of nutrients. Here we report on high-resolution measurements of nitrate (NO(3)(-)) and oxygen (O(2)) concentration made over 21 months using a profiling float deployed near the Hawaii Ocean Time-series station in the North Pacific subtropical gyre. Our measurements demonstrate that as O(2) was produced and DIC was consumed over two annual cycles, a corresponding seasonal deficit in dissolved NO(3)(-) appeared in water at depths from 100 to 250 m. The deep-water deficit in NO(3)(-) was in near-stoichiometric balance with the fixed nitrogen exported to depth. Thus, when the water column from the surface to 250 m is considered as a whole, there is near equivalence between nutrient supply and demand. Short-lived transport events (〈10 days) that connect deep stocks of nitrate to nutrient-poor surface waters were clearly present in 12 of the 127 vertical profiles.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Johnson, Kenneth S -- Riser, Stephen C -- Karl, David M -- England -- Nature. 2010 Jun 24;465(7301):1062-5. doi: 10.1038/nature09170.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Monterey Bay Aquarium Research Institute, Moss Landing, California 95039, USA. johnson@mbari.org〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20577212" target="_blank"〉PubMed〈/a〉
    Keywords: Atmosphere/chemistry ; Carbon Dioxide/analysis/metabolism ; Ecosystem ; Hawaii ; Nitrates/*analysis/chemistry/*metabolism ; Nitrogen/analysis/chemistry/metabolism ; Oxygen/analysis/metabolism ; Pacific Ocean ; Salinity ; Seasons ; Seawater/*chemistry ; Ships ; Solubility ; Time Factors ; *Tropical Climate
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2014-11-29
    Description: The recent increase in anthropogenic emissions of reactive nitrogen from northeastern Asia and the subsequent enhanced deposition over the extensive regions of the North Pacific Ocean (NPO) have led to a detectable increase in the nitrate (N) concentration of the upper ocean. The rate of increase of excess N relative to phosphate (P) was found to be highest (~0.24 micromoles per kilogram per year) in the vicinity of the Asian source continent, with rates decreasing eastward across the NPO, consistent with the magnitude and distribution of atmospheric nitrogen deposition. This anthropogenically driven increase in the N content of the upper NPO may enhance primary production in this N-limited region, potentially leading to a long-term change of the NPO from being N-limited to P-limited.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kim, Il-Nam -- Lee, Kitack -- Gruber, Nicolas -- Karl, David M -- Bullister, John L -- Yang, Simon -- Kim, Tae-Wook -- New York, N.Y. -- Science. 2014 Nov 28;346(6213):1102-6. doi: 10.1126/science.1258396.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Environmental Sciences and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Republic of Korea. ; School of Environmental Sciences and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Republic of Korea. ktl@postech.ac.kr. ; Environmental Physics Group, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Zurich, Switzerland. ; Daniel K. Inouye Center for Microbial Oceanography, University of Hawaii at Manoa, 1950 East West Road, Honolulu, HI 96822, USA. ; Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration (NOAA), Seattle, WA 98115, USA. ; Ocean Circulation and Climate Research Division, Korea Institute of Ocean Science and Technology, Ansan, 426-744, Republic of Korea.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25430767" target="_blank"〉PubMed〈/a〉
    Keywords: Asia ; Humans ; Nitrates/*analysis ; Nitrogen/*analysis ; Pacific Ocean ; Phosphates/analysis ; Seawater/*chemistry ; Water Pollutants, Chemical/*analysis ; *Water Pollution
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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