Investigating the potential impact of louisiana coastal restoration on the trace metal geochemistry of constructed marshlands

Omolola A. Akintomide*, Segun A. Adebayo, Alexandra S. Trahan, Elizabeth Chamberlain, Karen H. Johannesson

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Coastal restoration through diversion of suspended sediments from the Lower Mississippi River (LMR) into hydrologically isolated marshlands of Mid-Barataria Bay and Mid-Breton Sounds in southern Louisiana has the potential to mobilize lead (Pb), and other trace elements. We investigate the potential impact(s) of the diversion on marsh porewater through analysis of modern riverbank and suspended sediments, compared to sediments from pre-industrial deltaic deposits of LMR. Sequential extraction methods were used to evaluate Pb, cobalt (Co), copper (Cu), nickel (Ni), and zinc (Zn) in the sediments. Our results show that metal contents are higher (e.g., 8-to 10-fold for Pb) in the modern sediments relative to pre-industrial deposits. Also, the reducible fraction, presumably iron/manganese (Fe/Mn) oxides/oxyhydroxides, is the chief reservoir of environmentally available metals. The substantially higher trace metal contents of the modern relative to pre-industrial sediments suggest that the modern sediments contain a sizeable amount of anthropogenic contributions. Furthermore, the concentration of the trace metals in the reducible fraction suggests bioavailability to marsh organisms upon reductive dissolution within the planned, constructed coastal marshes. Still, additional sediment samples from the marshlands during the diversion implementation phase will be necessary to support the preliminary findings in this contribution as it affects coastal marshes and vital local fisheries.

Original languageEnglish
Article number55
Number of pages26
JournalSoil Systems
Volume4
Issue number3
DOIs
Publication statusPublished - 5 Sep 2020
Externally publishedYes

Keywords

  • Contaminated sediment
  • Diversions
  • Fe/Mn oxides/oxyhydroxides
  • Lower Mississippi River
  • Redox conditions
  • Sequential extractions
  • Trace metals
  • Wetlands/marshlands

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