Removal of 210 Po from aqueous media and its thermodynamics and kinetics

Erenturk, Sema; Kaygun, Aysun

doi:10.1016/j.jenvrad.2017.01.010

Cited by 10 publications

(2 citation statements)

References 28 publications

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“…50 In reducing, low-or near-neutral pH waters, in slightly oxic to slightly reducing conditions, the polonous cation (Po 2+ , with core valence +2) and the ion-pair complex with Cl (PoCl + ; Figure 7) may occur; such cations are strongly sorbable at near-neutral and higher pHs. Laboratory experiments demonstrated strong sorption of 210 Po at neutral and near-neutral pH but inefficient sorption at higher pH, 93 consistent with the occurrence of 210 Po as H 2 PoO 3 (or PoO 3 −2 ) rather than Po 2+ or PoCl + . Under the most strongly reducing conditions, the predominant aqueous species is indicated as hydrogen polonide, HPo − (Po −2 , with core valence −2), 51 which being anionic may also be mobile at high pH.…”

supporting

confidence: 59%

Occurrence and Geochemistry of Lead-210 and Polonium-210 Radionuclides in Public-Drinking-Water Supplies from Principal Aquifers of the United States

Szabó

Stackelberg

Cravotta

2020

Environ. Sci. Technol.

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On the basis of lifetime cancer risks, lead-210 (210Pb) and polonium-210 (210Po) ≥ 1.0 and 0.7 pCi/L (picocuries per liter), respectively, in drinking-water supplies may pose human-health concerns. 210Pb and 210Po were detected at concentrations greater than these thresholds at 3.7 and 1.5%, respectively, of filtered untreated groundwater samples from 1263 public-supply wells in 19 principal aquifers across the United States. Nationally, 72% of samples with radon-222 (222Rn) concentrations > 4000 pCi/L had 210Pb ≥ 1.0 pCi/L. 210Pb is mobilized by alpha recoil associated with the decay of 222Rn and short-lived progeny. 210Pb concentrations ≥ 1.0 pCi/L occurred most frequently where acidic groundwaters inhibited 210Pb readsorption (felsic-crystalline rocks) and where reducing alkaline conditions favored dissolution of iron–manganese- (Fe–Mn-) oxyhydroxides (which adsorb 210Pb) and formation of lead–carbonate complexes (enhancing lead (Pb) mobility). 210Po concentrations ≥ 0.7 pCi/L occurred almost exclusively in confined Coastal Plain aquifers where old (low percent-modern carbon-14) groundwaters were reducing, with high pH (>7.5) and high sodium/chloride (Na/Cl) ratios resulting from cation exchange. In high-pH environments, aqueous polonium (Po) is poorly sorbed, occurring as dihydrogen polonate (H2PoO3(aq)) or, under strongly reducing conditions, as a hydrogen-polonide anion (HPo–). Fe–Mn- and sulfate-reduction and cation-exchange processes may mobilize polonium from mineral surfaces. Po2+ occurrence in low-to-neutral-pH waters is attenuated by adsorption.

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supporting

confidence: 59%

Occurrence and Geochemistry of Lead-210 and Polonium-210 Radionuclides in Public-Drinking-Water Supplies from Principal Aquifers of the United States

Szabó

Stackelberg

Cravotta

2020

Environ. Sci. Technol.

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“…210 Po concentrations correlated with those of sodium and the ratios of Na:Cl and Na:Ca (Table SI.5). 210 Po is documented in laboratory studies to be inefficiently sorbed in high-pH solutions, consistent with the occurrence found in the high-pH geochemical environments of the CP aquifers, because 210 Po species are neutrally or negatively charged and are inefficiently sorbed at high pH; this behavior contrasts with the strong sorption observed in most environments . In contrast with 210 Po, the 226 Ra concentrations were much lower than 1 pCi/L in the waters with the highest Na:Cl ratios (Figure ).…”

Section: Resultssupporting

confidence: 69%

Gross Alpha-Particle Activity and High ²²⁶Ra Concentrations Do Not Correspond with High ²¹⁰Po in the Atlantic and Gulf Coastal Plain Aquifers of the United States

et al. 2023

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210 Po, which is of human-health concern based on lifetime ingestion cancer risk, is indirectly regulated in drinking water through the U.S. Environmental Protection Agency's gross alphaparticle activity (GAPA) maximum contaminant level of 15 pCi/L (picocuries per liter). This regulation requires independent measurement of 226 Ra for samples exceeding the GAPA screening level of 5 pCi/L. There is no such requirement for 210 Po. Co-occurrence of 226 Ra and 210 Po, alpha-emitting 238 U-decay-series progeny, might be helpful in locating high-210 Po waters but is unverified. Relations among 210 Po, 226 Ra, and GAPA evaluated for samples from 257 public-supply wells from Coastal Plain aquifers showed that concentrations of 226 Ra correlated with GAPA but neither correlated with 210 Po concentrations. The highest concentrations of 226 Ra and 210 Po were found under differing geochemical conditions. The highest 226 Ra occurred in low-pH oxidizing waters and in neutral-pH reducing waters, where geochemical conditions render Fe−Mnhydroxide sorbents inefficient. 210 Po was highest (10.1 pCi/L) in reducing waters with high pH (>7.5, which results from progressive cation exchange), where 226 Ra was lowest�exchanged to clay minerals. Because 226 Ra and 210 Po did not co-occur, the GAPA screening might not be protective for 210 Po. Independent 210 Po analysis is prudent, especially where groundwater is reducing with high pH and low 226 Ra concentrations.

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Active Carbon/PAN composite adsorbent for uranium removal: Modeling adsorption isotherm data, thermodynamic and kinetic studies

Aslani

Amik

2021

Applied Radiation and Isotopes

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Removal of 210 Po from aqueous media and its thermodynamics and kinetics

Cited by 10 publications

References 28 publications

Occurrence and Geochemistry of Lead-210 and Polonium-210 Radionuclides in Public-Drinking-Water Supplies from Principal Aquifers of the United States

Occurrence and Geochemistry of Lead-210 and Polonium-210 Radionuclides in Public-Drinking-Water Supplies from Principal Aquifers of the United States

Gross Alpha-Particle Activity and High ²²⁶Ra Concentrations Do Not Correspond with High ²¹⁰Po in the Atlantic and Gulf Coastal Plain Aquifers of the United States

Active Carbon/PAN composite adsorbent for uranium removal: Modeling adsorption isotherm data, thermodynamic and kinetic studies

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Removal of 210 Po from aqueous media and its thermodynamics and kinetics

Cited by 10 publications

References 28 publications

Occurrence and Geochemistry of Lead-210 and Polonium-210 Radionuclides in Public-Drinking-Water Supplies from Principal Aquifers of the United States

Occurrence and Geochemistry of Lead-210 and Polonium-210 Radionuclides in Public-Drinking-Water Supplies from Principal Aquifers of the United States

Gross Alpha-Particle Activity and High 226Ra Concentrations Do Not Correspond with High 210Po in the Atlantic and Gulf Coastal Plain Aquifers of the United States

Active Carbon/PAN composite adsorbent for uranium removal: Modeling adsorption isotherm data, thermodynamic and kinetic studies

Contact Info

Product

Resources

About

Gross Alpha-Particle Activity and High ²²⁶Ra Concentrations Do Not Correspond with High ²¹⁰Po in the Atlantic and Gulf Coastal Plain Aquifers of the United States