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      Enhanced Carbonate Dissolution Associated With Deglacial Dysoxic Events in the Subpolar North Pacific

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          Abstract

          Here we use volume density ( ρ V) measurements as a metric of size‐normalized weights for Neogloboquadrina pachyderma, a planktonic foraminifer, from upper OMZ and abyssal depth sites in the Gulf of Alaska over the past ∼20,000 years to test for covariation between carbonate preservation and OMZ intensity. We find that dissolution of N. pachyderma is most intense at the upper OMZ site where oxygenation is generally lower than at the abyssal site. We also examine Uvigerina peregrina, a benthic foraminifer, at the upper OMZ site and find that the lowest ρ V measurements in both taxa occur during deglacial and early Holocene dysoxic events. We use computed tomography images to confirm that changes in ρ V are related to shell thickness, observe dissolution features, and test for growth influences on ρ V. Further, we use stepwise selection of multiple regression models in which coregistered environmental proxies are potential predictors of ρ V and find that the best supported models retain negative associations between ρ V and the concentration of redox‐sensitive metals and the relative abundance of dysoxia‐tolerant and opportunistic benthic foraminifera, indicating that low ρ V is associated with low‐oxygen conditions and pulsed availability of organic matter at the seafloor. Taken together, our results suggest the primary driver of carbonate dissolution here is related to organic carbon respiration at the seafloor. This highlights the importance of metabolic dissolution in understanding the inorganic carbon cycle and the role regions with high‐organic carbon export, such as OMZs, can have as CO 2 sources as metabolic dissolution intensifies.

          Key Points

          • Both benthic and planktonic foraminiferal fossils have lower shell density due to dissolution during dysoxic events in the Gulf of Alaska

          • Dissolution occurs primarily at the seafloor and is associated with high benthic organic carbon respiration

          • Metabolic dissolution is an important contributor to the inorganic carbon cycle in oxygen minimum zones and may enhance this CO 2 source

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          Most cited references106

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          NIH Image to ImageJ: 25 years of image analysis

          For the past twenty five years the NIH family of imaging software, NIH Image and ImageJ have been pioneers as open tools for scientific image analysis. We discuss the origins, challenges and solutions of these two programs, and how their history can serve to advise and inform other software projects.
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            3D Slicer as an image computing platform for the Quantitative Imaging Network.

            Quantitative analysis has tremendous but mostly unrealized potential in healthcare to support objective and accurate interpretation of the clinical imaging. In 2008, the National Cancer Institute began building the Quantitative Imaging Network (QIN) initiative with the goal of advancing quantitative imaging in the context of personalized therapy and evaluation of treatment response. Computerized analysis is an important component contributing to reproducibility and efficiency of the quantitative imaging techniques. The success of quantitative imaging is contingent on robust analysis methods and software tools to bring these methods from bench to bedside. 3D Slicer is a free open-source software application for medical image computing. As a clinical research tool, 3D Slicer is similar to a radiology workstation that supports versatile visualizations but also provides advanced functionality such as automated segmentation and registration for a variety of application domains. Unlike a typical radiology workstation, 3D Slicer is free and is not tied to specific hardware. As a programming platform, 3D Slicer facilitates translation and evaluation of the new quantitative methods by allowing the biomedical researcher to focus on the implementation of the algorithm and providing abstractions for the common tasks of data communication, visualization and user interface development. Compared to other tools that provide aspects of this functionality, 3D Slicer is fully open source and can be readily extended and redistributed. In addition, 3D Slicer is designed to facilitate the development of new functionality in the form of 3D Slicer extensions. In this paper, we present an overview of 3D Slicer as a platform for prototyping, development and evaluation of image analysis tools for clinical research applications. To illustrate the utility of the platform in the scope of QIN, we discuss several use cases of 3D Slicer by the existing QIN teams, and we elaborate on the future directions that can further facilitate development and validation of imaging biomarkers using 3D Slicer. Copyright © 2012 Elsevier Inc. All rights reserved.
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              Expanding oxygen-minimum zones in the tropical oceans.

              Oxygen-poor waters occupy large volumes of the intermediate-depth eastern tropical oceans. Oxygen-poor conditions have far-reaching impacts on ecosystems because important mobile macroorganisms avoid or cannot survive in hypoxic zones. Climate models predict declines in oceanic dissolved oxygen produced by global warming. We constructed 50-year time series of dissolved-oxygen concentration for select tropical oceanic regions by augmenting a historical database with recent measurements. These time series reveal vertical expansion of the intermediate-depth low-oxygen zones in the eastern tropical Atlantic and the equatorial Pacific during the past 50 years. The oxygen decrease in the 300- to 700-m layer is 0.09 to 0.34 micromoles per kilogram per year. Reduced oxygen levels may have dramatic consequences for ecosystems and coastal economies.
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                Author and article information

                Contributors
                (View ORCID Profile)
                (View ORCID Profile)
                Journal
                Paleoceanography and Paleoclimatology
                Paleoceanog and Paleoclimatol
                American Geophysical Union (AGU)
                2572-4517
                2572-4525
                April 2021
                April 22 2021
                April 2021
                : 36
                : 4
                Affiliations
                [1 ] Department of Geology and Geophysics Texas A&M University College Station TX USA
                Article
                10.1029/2020PA004206
                b39ac665-2081-4552-bdf0-8bfb75071412
                © 2021

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