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  • 1
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    Aggregation of a diatom bloom in a mesocosm: The role of transparent exopolymer particles (TEP) (1995)
    Elsevier
    In:  Deep Sea Research Part II: Topical Studies in Oceanography, 42 (1). pp. 99-109.
    Details
    Publication Date: 2016-08-02
    Description: The role of TEP (Transparent Exopolymer Particles) in the flocculation of a diatom bloom was studied under controlled conditions in a mesocosm. The concentration of TEP increased exponentially during growth, flocculation and senescence of the bloom. Aggregation began dominating the particle dynamics of TEP during the early growth phase of the bloom, several days prior to the appearance of large flocs and nutrient depletion. TEP aggregated with themselves and with phytoplankton due to the high stickiness of TEP, but phytoplankton was not observed to aggregrate with itself. The production of TEP, estimated from changes in concentration, did not increase after nutrients were depleted. The concentration of TEP was a linear function of chl a and particulate organic carbon (POC), indicating that production of TEP was linked to growth rather than standing stocks of phytoplankton. The ratio between TEP and phytoplankton appeared to be one of the factors determining the onset of the flocculation of the bloom. The concentration of TEP may have been decreased by bacterial degradation. Bacterial degradation of TEP may explain the low TEP to chl a values, the decrease in stickiness of particles as the bloom progressed, and the retarded onset of flocculation.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/0967-0645(95)00006-C
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    The role of aggregation for the dissolution of diatom frustules (2003)
    Elsevier
    In:  FEMS Microbiology Ecology, 46 (3). pp. 247-255.
    Details
    Publication Date: 2020-03-20
    Description: Observations that the majority of silica dissolution occurs within the upper 200 m of the ocean, and that sedimentation rates of diatom frustules generally do not decrease significantly with depth, suggested reduced dissolution rates of diatoms embedded within sinking aggregates. To investigate this hypothesis, silica dissolution rates of aggregated diatom cells were compared to those of dispersed cells during conditions mimicking sedimentation below the euphotic zone. Changes in the concentrations of biogenic silica, silicic acid, cell numbers, chlorophyll a and transparent exopolymer particles (TEP) were monitored within aggregates and in the surrounding seawater (SSW) during two 42-day experiments. Whereas the concentration of dispersed diatoms decreased over the course of the experiment, the amount of aggregated cells remained roughly constant after an initial increase. Initially only 6% of cells were aggregated and at the end of the experiment more than 60% of cells were enclosed within aggregates. These data imply lower dissolution rates for aggregated cells. However, fluxes of silica between the different pools could not be constrained reliably enough to unequivocally prove reduced dissolution for aggregated cells.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/S0168-6496(03)00199-5
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Sustained deposition of contaminants from the Deepwater Horizon spill (2016)
    NATL ACAD SCIENCES
    In:  EPIC3Proceedings of the National Academy of Sciences of the United States of America, NATL ACAD SCIENCES, ISSN: 0027-8424
    Details
    Publication Date: 2016-07-04
    Description: The 2010 Deepwater Horizon oil spill resulted in 1.6–2.6 × 1010 grams of petrocarbon accumulation on the seafloor. Data from a deep sediment trap, deployed 7.4 km SW of the well between August 2010 and October 2011, disclose that the sinking of spill-associated substances, mediated by marine particles, especially phytoplankton, continued at least 5 mo following the capping of the well. In August/September 2010, an exceptionally large diatom bloom sedimentation event coincided with elevated sinking rates of oil-derived hydrocarbons, black carbon, and two key components of drilling mud, barium and olefins. Barium remained in the water column for months and even entered pelagic food webs. Both saturated and polycyclic aromatic hydrocarbon source indicators corroborate a predominant contribution of crude oil to the sinking hydrocarbons. Cosedimentation with diatoms accumulated contaminants that were dispersed in the water column and transported them downward, where they were concentrated into the upper centimeters of the seafloor, potentially leading to sustained impact on benthic ecosystems.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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    PAPER (OA)
  • 4
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    Biogeochemical processes affecting the fate of discharged Deepwater Horizon gas and oil new insights and remaining gaps in our understanding (2021)
    Oceanography Society
    Details
    Publication Date: 2022-05-27
    Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Farrington, J. W., Overton, E. B., & Passow, U. Biogeochemical processes affecting the fate of discharged Deepwater Horizon gas and oil new insights and remaining gaps in our understanding. Oceanography, 34(1), (2021): 76–97, https://doi.org/10.5670/oceanog.2021.118.
    Description: Research funded under the Gulf of Mexico Research Initiative provided new insights into the biogeochemical processes influencing the fate of petroleum chemicals entering the Gulf of Mexico from the Deepwater Horizon (DWH) accident. This overview of that work is based on detailed recent reviews of aspects of the biogeochemistry as well as on activities supported by the US Natural Resource Damage Assessment. The main topics presented here are distribution of hydrocarbons in the water column; the role of photo-oxidation of petroleum compounds at the air-sea interface; the role of particulates in the fate of the DWH hydrocarbons, especially marine oil snow (MOS) and marine oil snow sedimentation and flocculent accumulation (MOSSFA); oil deposition and accumulation in sediments; and fate of oil on beaches and in marshes. A brief discussion of bioaccumulation is also included. Microbial degradation is addressed in a separate paper in this special issue of Oceanography. Important future research recommendations include: conduct a more robust assessment of the mass balance of various chemical groupings and even individual chemicals during specific time intervals; seek a better understanding of the roles of photo-oxidation products, MOS, and MOSSFA and their relationships to microbial degradation; and determine the fates of the insoluble highly degraded and viscous oil residues in the environment.
    Description: We acknowledge the efforts of several hundred researchers within the Gulf of Mexico Research Initiative, the BP- and US government-funded DWH Natural Resource Damage Assessment efforts, the US National Science Foundation Rapid Response Program, NOAA Sea Grant, and several other sources of funding too numerous to mention that contributed to advancing knowledge of the fates of gas and oil inputs from the DWH accident. Adrian Burd, Joel Koska, Elizabeth Kujawinski, Samantha Joye, Antonietta Quigg, and Collin Ward co-led GoMRI synthesis workshops and/or were lead authors of recent papers reviewing key aspects of biogeochemical fates of DWH inputs.
    Repository Name: Woods Hole Open Access Server
    Type: Article
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    PAPER (OA)
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