Roles of reactive iron mineral coatings in natural attenuation in redox transition zones preserved from a site with historical contamination

Han Hua, Xin Yin, Donna Fennell, James A. Dyer, Richard Landis, Scott A. Morgan, Lisa Axe

Research output: Contribution to journalArticlepeer-review

Abstract

In this study, a protocol was developed to identify reduction-oxidation (redox) transition zones in an effort to exploit natural source zone depletion processes. A sediment core with a total length of 18-m was collected from a site with historical contamination that includes chlorinated benzenes where the redox condition was preserved. In the four redox transition zones investigated, reactive iron coatings are characterized with a suite of analyses under anaerobic conditions. To distinguish surface coating mineralogy, X-ray diffraction, X-ray fluorescence, and field-emission scanning electron microscopy with an energy dispersive X-ray analyzer were applied along with a six-step sequential extraction process. The cycling of Fe and S, as an important contribution and indicator of ongoing natural attenuation processes for constituents of concern (COC), was delineated by using data from multiple and complementary analyses for isolating and identifying iron phases. Along with groundwater chemistry, contaminant concentrations, and microbial genera, attenuation of COCs is expected to be active and sustainable in redox transition zones, where there is an abundance of reactive iron mineral coatings cycling through biogeochemical reactions. Reactions in other redox transition zones may be limited where iron mineral coatings are not dominant.

Original languageEnglish (US)
Article number126600
JournalJournal of Hazardous Materials
Volume420
DOIs
StatePublished - Oct 15 2021

All Science Journal Classification (ASJC) codes

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis

Keywords

  • Biogeochemical degradation
  • Chlorinated benzene
  • Natural attenuation
  • Reactive iron mineral coatings
  • Redox transition zones

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