Phosphorus burial in vivianite-type minerals in methane-rich coastal sediments
Kubeneck, L. Joëlle; Lenstra, Wytze K.; Malkin, Sairah Y.; Conley, Daniel J.; Slomp, Caroline P.
(2021) Marine Chemistry, volume 231
(Article)
Abstract
Sediments are a key sink for phosphorus (P) in coastal systems. This allows coastal areas to act as a filter for P that is transported from land to sea. Recent work suggests that vivianite-type ferrous iron (Fe(II))-P minerals may be more important as a sink for P in coastal sediments
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than previously thought. Here, we investigate the occurrence of such vivianite-type minerals in sediments of three eutrophic coastal sites with contrasting dynamics with respect to iron (Fe) and sulfur (S), covering a salinity range of 0 to 7. We only find authigenic vivianite-type minerals at the low and intermediate salinity sites, where Fe is available in excess over sulfide production. Sequential extractions combined with SEM-EDS and μXRF analysis point towards substitution of Fe in vivianite-type minerals by other transition metal cations such as magnesium and manganese, suggesting potentially different formation pathways modulated by metal cation availability. Our results suggest that vivianite-type minerals may act as a key sink for P in sediments of many other brackish coastal systems. Climate change-driven modulations of coastal bottom water salinity, and hence, Fe versus S availability in the sediment, may alter the role of vivianite-type minerals as a P burial sink over the coming decades. Model projections for the Baltic Sea point towards increased river input and freshening of coastal waters, which could enhance P burial. In contrast, sea level rise in the Chesapeake Bay area is expected to lead to an increase in bottom water salinity and this could lower rates of P burial or even liberate currently buried P, thereby enhancing eutrophication.
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Keywords: Iron, Phosphorus cycle, Sediments, Vivianite, Oceanography, General Chemistry, Environmental Chemistry, Water Science and Technology
ISSN: 0304-4203
Publisher: Elsevier
Note: Funding Information: We thank the captain, crew and scientific participants for their assistance during sampling on the R/V Electra in March 2017 and R/V Rachel Carson in September 2018, respectively. Furthermore, we would like to thank Coen Mulder, Arnold van Dijk, Tilly Bouten, Niels van Helmond, Andrew McCarthy, Cindy Palinkas, Emily Russ and Laura Lapham for analytical assistance. We thank the two anonymous reviewers for the insightful and constructive feedback. This research was funded by NWO-Vici grant 865.13.005 and the Netherlands Earth System Science Center (NESSC; to C. P. Slomp), the Swedish Agency for Marine and Water Management (Havs- och vattenmyndigheten, DNR 1960-2018 ), the EU Seventh Framework Programme and Formas (Sweden) (BONUS/COCOA grant 2112932-1 ), as well as the Olaf Schuiling Fund , Utrecht University (to L. J. Kubeneck) and start-up funding from Horn Point Laboratory and NSF grant (grant OCE-1756877 ; to S. Y. Malkin). The Swedish Meteorological and Hydrological Institute, as well as the Chesapeake Bay Program, are acknowledged for open source data on water quality. Funding Information: We thank the captain, crew and scientific participants for their assistance during sampling on the R/V Electra in March 2017 and R/V Rachel Carson in September 2018, respectively. Furthermore, we would like to thank Coen Mulder, Arnold van Dijk, Tilly Bouten, Niels van Helmond, Andrew McCarthy, Cindy Palinkas, Emily Russ and Laura Lapham for analytical assistance. We thank the two anonymous reviewers for the insightful and constructive feedback. This research was funded by NWO-Vici grant 865.13.005 and the Netherlands Earth System Science Center (NESSC; to C. P. Slomp), the Swedish Agency for Marine and Water Management (Havs- och vattenmyndigheten, DNR 1960-2018), the EU Seventh Framework Programme and Formas (Sweden) (BONUS/COCOA grant 2112932-1), as well as the Olaf Schuiling Fund, Utrecht University (to L. J. Kubeneck) and start-up funding from Horn Point Laboratory and NSF grant (grant OCE-1756877; to S. Y. Malkin). The Swedish Meteorological and Hydrological Institute, as well as the Chesapeake Bay Program, are acknowledged for open source data on water quality. Publisher Copyright: © 2021 The Authors
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