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Understanding the Radioactive Ingrowth and Decay of Naturally Occurring Radioactive Materials in the Environment: An Analysis of Produced Fluids from the Marcellus Shale.

Nelson AW, Eitrheim ES, Knight AW, May D, Mehrhoff MA, Shannon R, Litman R, Burnett WC, Forbes TZ, Schultz MK - Environ. Health Perspect. (2015)

Bottom Line: However, natural radioactivity found in the large volumes of "produced fluids" generated by these technologies is emerging as an international environmental health concern.Specifically, we examined the use of high-purity germanium gamma spectrometry and isotope dilution alpha spectrometry to quantitate NORM.Accurate predictions of radioactivity concentrations are critical for estimating doses to potentially exposed individuals and the surrounding environment.

View Article: PubMed Central - PubMed

Affiliation: Interdisciplinary Human Toxicology Program, University of Iowa, Iowa City, Iowa, USA.

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.

No MeSH data available.


Related in: MedlinePlus

Natural thorium and uranium decay chains. Half-lives and decay information were obtained from the NuDat 2 Database (NNDC 2013). Abbreviations: d, days; h, hours; m, minutes; s, seconds; y, years.
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f1: Natural thorium and uranium decay chains. Half-lives and decay information were obtained from the NuDat 2 Database (NNDC 2013). Abbreviations: d, days; h, hours; m, minutes; s, seconds; y, years.

Mentions: The naturally occurring Ra isotopes of concern (226Ra and 228Ra) have been reported (in peer-reviewed literature) to exceed 670 Bq/L and 95 Bq/L, respectively, in produced fluids (Barbot et al. 2013; Haluszczak et al. 2013; Nelson et al. 2014; Rowan et al. 2011). However, little attention has been paid to other environmentally persistent alpha- and beta-emitting NORM such as uranium (U), thorium (Th), radon (Rn), bismuth (Bi), lead (Pb), and polonium (Po) isotopes (Figure 1). In reviewing a report of gross alpha levels in fluids from Marcellus Shale, we observed that reported Ra radioactivity concentrations were similar to maximum gross alpha levels (Barbot et al. 2013), indicating that Ra had been selectively extracted into the liquid wastes, while alpha-emitting daughters remained insoluble under the geochemical conditions of the fluid extraction process. Given that Ra decay products had likely existed in a steady-state radioactive equilibrium with Ra isotopes in the solid shale-formation matrix for millions of years prior to drilling activities, these observations prompted us to explore the radioactive equilibrium relationships of Ra decay products in produced fluids, particularly for the longer-lived alpha-emitters, 228Th (t1/2 = 1.91 years) and 210Po (t1/2 = 138 days) (half-lives were extracted from the NuDat 2 Database) [National Nuclear Data Center (NNDC) 2013].


Understanding the Radioactive Ingrowth and Decay of Naturally Occurring Radioactive Materials in the Environment: An Analysis of Produced Fluids from the Marcellus Shale.

Nelson AW, Eitrheim ES, Knight AW, May D, Mehrhoff MA, Shannon R, Litman R, Burnett WC, Forbes TZ, Schultz MK - Environ. Health Perspect. (2015)

Natural thorium and uranium decay chains. Half-lives and decay information were obtained from the NuDat 2 Database (NNDC 2013). Abbreviations: d, days; h, hours; m, minutes; s, seconds; y, years.
© Copyright Policy - public-domain
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4492269&req=5

f1: Natural thorium and uranium decay chains. Half-lives and decay information were obtained from the NuDat 2 Database (NNDC 2013). Abbreviations: d, days; h, hours; m, minutes; s, seconds; y, years.
Mentions: The naturally occurring Ra isotopes of concern (226Ra and 228Ra) have been reported (in peer-reviewed literature) to exceed 670 Bq/L and 95 Bq/L, respectively, in produced fluids (Barbot et al. 2013; Haluszczak et al. 2013; Nelson et al. 2014; Rowan et al. 2011). However, little attention has been paid to other environmentally persistent alpha- and beta-emitting NORM such as uranium (U), thorium (Th), radon (Rn), bismuth (Bi), lead (Pb), and polonium (Po) isotopes (Figure 1). In reviewing a report of gross alpha levels in fluids from Marcellus Shale, we observed that reported Ra radioactivity concentrations were similar to maximum gross alpha levels (Barbot et al. 2013), indicating that Ra had been selectively extracted into the liquid wastes, while alpha-emitting daughters remained insoluble under the geochemical conditions of the fluid extraction process. Given that Ra decay products had likely existed in a steady-state radioactive equilibrium with Ra isotopes in the solid shale-formation matrix for millions of years prior to drilling activities, these observations prompted us to explore the radioactive equilibrium relationships of Ra decay products in produced fluids, particularly for the longer-lived alpha-emitters, 228Th (t1/2 = 1.91 years) and 210Po (t1/2 = 138 days) (half-lives were extracted from the NuDat 2 Database) [National Nuclear Data Center (NNDC) 2013].

Bottom Line: However, natural radioactivity found in the large volumes of "produced fluids" generated by these technologies is emerging as an international environmental health concern.Specifically, we examined the use of high-purity germanium gamma spectrometry and isotope dilution alpha spectrometry to quantitate NORM.Accurate predictions of radioactivity concentrations are critical for estimating doses to potentially exposed individuals and the surrounding environment.

View Article: PubMed Central - PubMed

Affiliation: Interdisciplinary Human Toxicology Program, University of Iowa, Iowa City, Iowa, USA.

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.

No MeSH data available.


Related in: MedlinePlus