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Jilbert, Tom; Asmala, Eero; Schröder, Christian; Tiihonen, Rosa; Myllykangas, Jukka-Pekka; Virtasalo, Joonas J; Kotilainen, Aarno T; Peltola, Pasi; Ekholm, Päivi; Hietanen, Susanna (2018): Water column, sediment and pore water data from Mustionjoki estuary, Finland, 2014-2015 [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.886792, Supplement to: Jilbert, T et al. (2018): Impacts of flocculation on the distribution and diagenesis of iron in boreal estuarine sediments. Biogeosciences, 15(4), 1243-1271, https://doi.org/10.5194/bg-15-1243-2018

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Abstract:
Iron (Fe) plays a key role in sedimentary diagenetic processes in coastal systems, participating in various redox reactions and influencing the burial of organic carbon. Large amounts of Fe enter the marine environment from boreal river catchments associated with dissolved organic matter (DOM) and as colloidal Fe oxyhydroxides, principally ferrihydrite. However, the fate of this Fe pool in estuarine sediments has not been extensively studied. Here we show that flocculation processes along a salinity gradient in an estuary of the northern Baltic Sea efficiently transfer Fe and OM from the dissolved phase into particulate material that accumulates in the sediments. Flocculation of Fe and OM is partially decoupled. This is likely due to the presence of discrete colloidal ferrihydrite in the freshwater Fe pool, which responds differently from DOM to estuarine mixing. Further decoupling of Fe from OM occurs during sedimentation. While we observe a clear decline with distance offshore in the proportion of terrestrial material in the sedimentary particulate organic matter (POM) pool, the distribution of flocculated Fe in sediments is modulated by focusing effects. Labile Fe phases are most abundant at a deep site in the inner basin of the estuary, consistent with input from flocculation and subsequent focusing. The majority of the labile Fe pool is present as Fe (II), including both acid-volatile sulfur (AVS)-bound Fe and unsulfidized phases. The ubiquitous presence of unsulfidized Fe (II) throughout the sediment column suggests Fe (II)-OM complexes derived from reduction of flocculated Fe (III)-OM, while other Fe (II) phases are likely derived from the reduction of flocculated ferrihydrite. Depth-integrated rates of Fe (II) accumulation (AVS-Fe + unsulfidized Fe (II) + pyrite) for the period 1970-2015 are greater in the inner basin of the estuary with respect to a site further offshore, confirming higher rates of Fe reduction in near-shore areas. Mössbauer 57Fe spectroscopy shows that refractory Fe is composed largely of superparamagnetic Fe (III), high-spin Fe (II) in silicates, and, at one station, also oxide minerals derived from past industrial activities. Our results highlight that the cycling of Fe in boreal estuarine environments is complex, and that the partial decoupling of Fe from OM during flocculation and sedimentation is key to understanding the role of Fe in sedimentary diagenetic processes in coastal areas.
Note that data for Figure 7 (Mössbauer profiles) and the PROFILE outputs presented in Figure 8 are not included in this dataset.
Coverage:
Median Latitude: 59.969895 * Median Longitude: 23.356408 * South-bound Latitude: 59.764387 * West-bound Longitude: 21.706720 * North-bound Latitude: 60.354667 * East-bound Longitude: 23.590867
Date/Time Start: 2001-01-01T00:00:00 * Date/Time End: 2015-06-30T00:00:00
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
15 datasets

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Datasets listed in this publication series

  1. Jilbert, T; Asmala, E; Schröder, C et al. (2018): Figure 1 (top and bottom panels) Mustionjoki transect temperature and dissolved oxygen June 2015. https://doi.org/10.1594/PANGAEA.886785
  2. Jilbert, T; Asmala, E; Schröder, C et al. (2018): Figure 1 (middle panel) Mustionjoki transect salinity June 2015. https://doi.org/10.1594/PANGAEA.886784
  3. Jilbert, T; Asmala, E; Schröder, C et al. (2018): Figure 2 A, B: Mustionjoki transect Fe-diss and Fe-part and salinity June 2015. https://doi.org/10.1594/PANGAEA.886786
  4. Jilbert, T; Asmala, E; Schröder, C et al. (2018): Figure 3 A, B: Mustionjoki transect suspended particulate matter N/C, del13C, and salinity June 2015. https://doi.org/10.1594/PANGAEA.886787
  5. Jilbert, T; Asmala, E; Schröder, C et al. (2018): Figure 3 B: Mustionjoki transect, surface water dissolved organic matter N/C, del13C, and salinity 2011. https://doi.org/10.1594/PANGAEA.886788
  6. Jilbert, T (2018): Figure 4: Sediment geochemistry in the Mustionjoki estuary transect September 2014. https://doi.org/10.1594/PANGAEA.886791
  7. Jilbert, T; Asmala, E; Schröder, C et al. (2018): Figure 4: Iron characteristics of surface sediments in the Mustionjoki estuary transect September 2014. https://doi.org/10.1594/PANGAEA.886793
  8. Jilbert, T; Asmala, E; Schröder, C et al. (2018): Figure 5 (center and right): Iron and sufur concentration in bulk sediment in the Mustionjoki estuary transect. https://doi.org/10.1594/PANGAEA.886795
  9. Jilbert, T; Asmala, E; Schröder, C et al. (2018): Figure 5: Organic carbon content in bulk sediment in the Mustionjoki estuary transect. https://doi.org/10.1594/PANGAEA.886796
  10. Jilbert, T; Asmala, E; Schröder, C et al. (2018): Figure 5 (left): Iron characteristics in the Mustionjoki estuary transect - sequential extraction data. https://doi.org/10.1594/PANGAEA.886794
  11. Jilbert, T; Asmala, E; Schröder, C et al. (2018): Figure 6AB: Iron characteristics in the Mustionjoki estuary transect in June 2015. https://doi.org/10.1594/PANGAEA.886797
  12. Jilbert, T; Asmala, E; Schröder, C et al. (2018): Figure 8: Depth profiles of porewater Fe, SO4, Stations A, D, J, Mustionjoki transect June 2015. https://doi.org/10.1594/PANGAEA.886798
  13. Jilbert, T; Asmala, E; Schröder, C et al. (2018): Figure 8: Depth profiles of porewater CH4, Stations A, D, J, Mustionjoki transect June 2015. https://doi.org/10.1594/PANGAEA.886799
  14. Jilbert, T; Asmala, E; Schröder, C et al. (2018): Figure 8: Depth profiles of porewater H2S, Stations A, D, J, Mustionjoki transect June 2015. https://doi.org/10.1594/PANGAEA.886800
  15. Jilbert, T; Asmala, E; Schröder, C et al. (2018): Figure 9: Fe/Al in surface sediments along Mustionjoki and Paimionjoki transects, HF digestion + ICP-OES. https://doi.org/10.1594/PANGAEA.886801