Historical and future needs for geospatial iodide occurrence in surface and groundwaters of the united states of america

Naushita Sharma, Tanju Karanfil, Paul Westerhoff

Research output: Contribution to journalReview articlepeer-review

26 Scopus citations


While iodide (I-) is critical for biological systems, it can serve as a precursor to organic iodinated disinfection byproducts (I-DBPs) of human health concern during water treatment. Thus, understanding potential I- occurrence in fresh waters is critical. Although I- occurrence data are sparse in surface water (SW) or groundwater (GW) used for drinking water supplies, data exist for other locations. We analyzed historical I- occurrence for â 9200 SW and GW sampling locations in the United States to understand potential I- sources and also spatial and temporal variability. I- ranged from below detection limits (<1 μg/L) to 95th percentile concentrations of 320 and 1300 μg/L (median = 12 and 13 μg/L), respectively, in SW and GW. I- appears to be influenced by halite basins, organic-rich shale/oil formations, saltwater intrusion, and rainfall, with median Br-/I- mass ratios of 10 and 17 μg/μg in SW and GW, respectively. Our results demonstrated considerable variability in iodine sources and speciation, which can impact I-DBP formation at WTPs. We advocate for occurrence studies to measure I-, IO3 -, and total iodine in raw and finished drinking waters to fill critical data gaps necessary to understand the potential formation of I-DBPs that impact public health.

Original languageEnglish (US)
Pages (from-to)379-388
Number of pages10
JournalEnvironmental Science and Technology Letters
Issue number7
StatePublished - May 28 2019

ASJC Scopus subject areas

  • Environmental Chemistry
  • Ecology
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis


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