Koch Boris P.

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Koch
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Boris P.
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  • Article
    Analytical and computational advances, opportunities, and challenges in marine organic biogeochemistry in an era of "Omics"
    (Frontiers Media, 2020-09-02) Steen, Andrew D. ; Kusch, Stephanie ; Abdulla, Hussain A. ; Cakić, Nevenka ; Coffinet, Sarah ; Dittmar, Thorsten ; Fulton, James M. ; Galy, Valier ; Hinrichs, Kai-Uwe ; Ingalls, Anitra ; Koch, Boris P. ; Kujawinski, Elizabeth B. ; Liu, Zhanfei ; Osterholz, Helena ; Rush, Darci ; Seidel, Michael ; Sepulveda, Julio ; Wakeham, Stuart G.
    Advances in sampling tools, analytical methods, and data handling capabilities have been fundamental to the growth of marine organic biogeochemistry over the past four decades. There has always been a strong feedback between analytical advances and scientific advances. However, whereas advances in analytical technology were often the driving force that made possible progress in elucidating the sources and fate of organic matter in the ocean in the first decades of marine organic biogeochemistry, today process-based scientific questions should drive analytical developments. Several paradigm shifts and challenges for the future are related to the intersection between analytical progress and scientific evolution. Untargeted “molecular headhunting” for its own sake is now being subsumed into process-driven targeted investigations that ask new questions and thus require new analytical capabilities. However, there are still major gaps in characterizing the chemical composition and biochemical behavior of macromolecules, as well as in generating reference standards for relevant types of organic matter. Field-based measurements are now routinely complemented by controlled laboratory experiments and in situ rate measurements of key biogeochemical processes. And finally, the multidisciplinary investigations that are becoming more common generate large and diverse datasets, requiring innovative computational tools to integrate often disparate data sets, including better global coverage and mapping. Here, we compile examples of developments in analytical methods that have enabled transformative scientific advances since 2004, and we project some challenges and opportunities in the near future. We believe that addressing these challenges and capitalizing on these opportunities will ensure continued progress in understanding the cycling of organic carbon in the ocean.
  • Article
    Particulate organic carbon deconstructed: molecular and chemical composition of particulate organic carbon in the ocean
    (Frontiers Media, 2020-06-26) Kharbush, Jenan J. ; Close, Hilary G. ; Van Mooy, Benjamin A. S. ; Arnosti, Carol ; Smittenberg, Rienk H. ; Le Moigne, Frederic A. C. ; Mollenhauer, Gesine ; Scholz-Böttcher, Barbara ; Obreht, Igor ; Koch, Boris P. ; Becker, Kevin W. ; Iversen, Morten H. ; Mohr, Wiebke
    The dynamics of the particulate organic carbon (POC) pool in the ocean are central to the marine carbon cycle. POC is the link between surface primary production, the deep ocean, and sediments. The rate at which POC is degraded in the dark ocean can impact atmospheric CO2 concentration. Therefore, a central focus of marine organic geochemistry studies is to improve our understanding of POC distribution, composition, and cycling. The last few decades have seen improvements in analytical techniques that have greatly expanded what we can measure, both in terms of organic compound structural diversity and isotopic composition, and complementary molecular omics studies. Here we provide a brief overview of the autochthonous, allochthonous, and anthropogenic components comprising POC in the ocean. In addition, we highlight key needs for future research that will enable us to more effectively connect diverse data sources and link the identity and structural diversity of POC to its sources and transformation processes.
  • Article
    Leads in Arctic pack ice enable early phytoplankton blooms below snow-covered sea ice
    (Nature Publishig Group, 2019-01-17) Assmy, Philipp ; Fernández-Méndez, Mar ; Duarte, Pedro ; Meyer, Amelie ; Randelhoff, Achim ; Mundy, Christopher J. ; Olsen, Lasse M. ; Kauko, Hanna Maria ; Bailey, Allison ; Chierici, Melissa ; Cohen, Lana ; Doulgeris, Anthony P. ; Ehn, Jens K. ; Fransson, Agneta ; Gerland, Sebastian ; Hop, Haakon ; Hudson, Stephen R. ; Hughes, Nick ; Itkin, Polona ; Johnsen, Geir ; King, Jennifer A. ; Koch, Boris P. ; Koenig, Zoe ; Kwasniewski, Slawomir ; Laney, Samuel R. ; Nicolaus, Marcel ; Pavlov, Alexey K. ; Polashenski, Christopher M. ; Provost, Christine ; Rösel, Anja ; Sandbu, Marthe ; Spreen, Gunnar ; Smedsrud, Lars H. ; Sundfjord, Arild ; Taskjelle, Torbjørn ; Tatarek, Agnieszka ; Wiktor, Jozef ; Wagner, Penelope M. ; Wold, Anette ; Steen, Harald ; Granskog, Mats A.
    The Arctic icescape is rapidly transforming from a thicker multiyear ice cover to a thinner and largely seasonal first-year ice cover with significant consequences for Arctic primary production. One critical challenge is to understand how productivity will change within the next decades. Recent studies have reported extensive phytoplankton blooms beneath ponded sea ice during summer, indicating that satellite-based Arctic annual primary production estimates may be significantly underestimated. Here we present a unique time-series of a phytoplankton spring bloom observed beneath snow-covered Arctic pack ice. The bloom, dominated by the haptophyte algae Phaeocystis pouchetii, caused near depletion of the surface nitrate inventory and a decline in dissolved inorganic carbon by 16 ± 6 g C m−2. Ocean circulation characteristics in the area indicated that the bloom developed in situ despite the snow-covered sea ice. Leads in the dynamic ice cover provided added sunlight necessary to initiate and sustain the bloom. Phytoplankton blooms beneath snow-covered ice might become more common and widespread in the future Arctic Ocean with frequent lead formation due to thinner and more dynamic sea ice despite projected increases in high-Arctic snowfall. This could alter productivity, marine food webs and carbon sequestration in the Arctic Ocean.
  • Article
    Selective preservation of organic matter in marine environments; processes and impact on the sedimentary record
    (Copernicus Publications on behalf of the European Geosciences Union, 2010-02-05) Zonneveld, K. A. F. ; Versteegh, G. J. M. ; Kasten, S. ; Eglinton, Timothy I. ; Emeis, Kay-Christian ; Huguet, Carme ; Koch, Boris P. ; de Lange, Gert J. ; de Leeuw, J. W. ; Middelburg, Jack J. ; Mollenhauer, Gesine ; Prahl, Fredrick G. ; Rethemeyer, J. ; Wakeham, Stuart G.
    The present paper is the result of a workshop sponsored by the DFG Research Center/Cluster of Excellence MARUM "The Ocean in the Earth System", the International Graduate College EUROPROX, and the Alfred Wegener Institute for Polar and Marine Research. The workshop brought together specialists on organic matter degradation and on proxy-based environmental reconstruction. The paper deals with the main theme of the workshop, understanding the impact of selective degradation/preservation of organic matter (OM) in marine sediments on the interpretation of the fossil record. Special attention is paid to (A) the influence of the molecular composition of OM in relation to the biological and physical depositional environment, including new methods for determining complex organic biomolecules, (B) the impact of selective OM preservation on the interpretation of proxies for marine palaeoceanographic and palaeoclimatic reconstruction, and (C) past marine productivity and selective preservation in sediments. It appears that most of the factors influencing OM preservation have been identified, but many of the mechanisms by which they operate are partly, or even fragmentarily, understood. Some factors have not even been taken carefully into consideration. This incomplete understanding of OM breakdown hampers proper assessment of the present and past carbon cycle as well as the interpretation of OM based proxies and proxies affected by OM breakdown. To arrive at better proxy-based reconstructions "deformation functions" are needed, taking into account the transport and diagenesis-related molecular and atomic modifications following proxy formation. Some emerging proxies for OM degradation may shed light on such deformation functions. The use of palynomorph concentrations and selective changes in assemblage composition as models for production and preservation of OM may correct for bias due to selective degradation. Such quantitative assessment of OM degradation may lead to more accurate reconstruction of past productivity and bottom water oxygenation. Given the cost and effort associated with programs to recover sediment cores for paleoclimatological studies, as well as with generating proxy records, it would seem wise to develop a detailed sedimentological and diagenetic context for interpretation of these records. With respect to the latter, parallel acquisition of data that inform on the fidelity of the proxy signatures and reveal potential diagenetic biases would be of clear value.