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Daniel Conley

Daniel Conley

Professor

Daniel Conley

Phosphorus burial in vivianite-type minerals in methane-rich coastal sediments

Författare

  • L. Joëlle Kubeneck
  • Wytze K. Lenstra
  • Sairah Y. Malkin
  • Daniel J. Conley
  • Caroline P. Slomp

Summary, in English

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 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.

Avdelning/ar

  • Kvartärgeologi

Publiceringsår

2021-04

Språk

Engelska

Publikation/Tidskrift/Serie

Marine Chemistry

Volym

231

Dokumenttyp

Artikel i tidskrift

Förlag

Elsevier

Ämne

  • Geochemistry

Nyckelord

  • Iron
  • Phosphorus cycle
  • Sediments
  • Vivianite

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0304-4203