title: Understanding the Radioactive Ingrowth and Decay of Naturally Occurring Radioactive Materials in the Environment: An Analysis of Produced Fluids from the Marcellus Shale.
abstract: BACKGROUND
  The economic value of unconventional natural gas resources has stimulated rapid globalization of horizontal drilling and hydraulic fracturing. However, natural radioactivity found in the large volumes of "produced fluids" generated by these technologies is emerging as an international environmental health concern. Current assessments of the radioactivity concentration in liquid wastes focus on a single element-radium. However, the use of radium alone to predict radioactivity concentrations can greatly underestimate total levels.
  
  
  OBJECTIVE
  We investigated the contribution to radioactivity concentrations from naturally occurring radioactive materials (NORM), including uranium, thorium, actinium, radium, lead, bismuth, and polonium isotopes, to the total radioactivity of hydraulic fracturing wastes.
  
  
  METHODS
  For this study we used established methods and developed new methods designed to quantitate NORM of public health concern that may be enriched in complex brines from hydraulic fracturing wastes. Specifically, we examined the use of high-purity germanium gamma spectrometry and isotope dilution alpha spectrometry to quantitate NORM.
  
  
  RESULTS
  We observed that radium decay products were initially absent from produced fluids due to differences in solubility. However, in systems closed to the release of gaseous radon, our model predicted that decay products will begin to ingrow immediately and (under these closed-system conditions) can contribute to an increase in the total radioactivity for more than 100 years.
  
  
  CONCLUSIONS
  Accurate predictions of radioactivity concentrations are critical for estimating doses to potentially exposed individuals and the surrounding environment. These predictions must include an understanding of the geochemistry, decay properties, and ingrowth kinetics of radium and its decay product radionuclides.
authors.affiliation: Interdisciplinary Human Toxicology Program, University of Iowa, Iowa City, Iowa, USA.
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Nelson
authors.forename: Eric S
authors.initials: ES
authors.lastname: Eitrheim
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Knight
authors.forename: Dustin
authors.initials: D
authors.lastname: May
authors.forename: Marinea A
authors.initials: MA
authors.lastname: Mehrhoff
authors.forename: Robert
authors.initials: R
authors.lastname: Shannon
authors.forename: Robert
authors.initials: R
authors.lastname: Litman
authors.forename: William C
authors.initials: WC
authors.lastname: Burnett
authors.forename: Tori Z
authors.initials: TZ
authors.lastname: Forbes
authors.forename: Michael K
authors.initials: MK
authors.lastname: Schultz
mesh_terms: D004603:Elements, Radioactive / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D000067071:Hydraulic Fracking; D007220:Industrial Waste / Q000032:analysis*; D010414:Pennsylvania; D011868:Radioisotopes / Q000032:analysis*; D062065:Wastewater / Q000737:chemistry*; D014875:Water Pollutants, Radioactive / Q000032:analysis*
chemical_list: D004603:Elements, Radioactive; D007220:Industrial Waste; D011868:Radioisotopes; D062065:Wastewater; D014875:Water Pollutants, Radioactive
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