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Willard S Moore - One of the best experts on this subject based on the ideXlab platform.
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characterizing sources of groundwater to a tropical coastal lagoon in a karstic area using Radium Isotopes and water chemistry
Marine Chemistry, 2008Co-Authors: Megan B Young, Willard S Moore, Meagan Eagle Gonneea, Derek A Fong, Jorge A Herrerasilveira, Adina PaytanAbstract:Radium Isotopes ( 223 Ra, 224 Ra, 226 Ra, and 228 Ra) and water chemistry were used to identify two chemically distinct sources of submarine groundwater discharge (SGD) in Celestun Lagoon, Yucatan, Mexico. Low salinity groundwater discharging from springs within the lagoon has previously been identified and extensively sampled for nutrient concentrations. However, a second type of groundwaterdischargingintothelagoonwasdetectedduringthisstudyusingRadiumisotopeactivitymeasurements.Thissecondtype of groundwater is characterized by moderate salinities (within the range of lagoon salinities) and very elevated Radium activities in comparison to the low salinity groundwater, mixed lagoon water, and seawater. Further analysis showed that the two types of groundwater also have distinct chloride, strontium, and sulfate ratios, along with slightly different nutrient concentrations. Groundwater discharge occurs through large and small springs scattered throughout the lagoon, and both types of groundwater were detected discharging from one of the larger springs. The relative proportions of low salinity groundwater and brackish high Radium groundwater varied over the tidal cycle. In order to better understand the relative contributions of each type of groundwater to the lagoon, athreeend-member mixingmodel basedonthe distinct chemical andisotopic compositions ofbothtypes ofgroundwater and of seawater was used to estimate the distribution of each water type throughout the lagoon in different seasons. This study suggests that substantial groundwater discharge to the lagoon can occur during both dry and rainy seasons. The presence of two groundwater sources has implications for monitoring and protection of the Celestun Lagoon Biosphere Reserve, since the two sources may have different susceptibilities to anthropogenic contamination depending on their respective recharge area and recharge rates. © 2007 Elsevier B.V. All rights reserved.
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radon and Radium Isotopes as tracers of submarine groundwater discharge results from the ubatuba brazil sgd assessment intercomparison
Estuarine Coastal and Shelf Science, 2008Co-Authors: William C Burnett, Willard S Moore, Richard N Peterson, Joselene De OliveiraAbstract:Abstract We determined groundwater flow rates shortly after the wet season into an embayment near Ubatuba, Brazil as part of an international intercomparison experiment for submarine groundwater discharge (SGD) assessment techniques. Our estimated rates were determined by the combined use of continuous radon measurements and assessment of Radium isotope patterns. The spatial distribution of the short-lived Radium Isotopes (223Ra and 224Ra) provided the means for independent evaluations of radon losses by mixing and atmospheric evasion. We were thus able to construct a well-constrained mass balance for radon that included a groundwater flux term. Our results showed that the groundwater discharge into this embayment from the fractured crystalline rock aquifer is not steady-state but varies with tidal modulation and rain-induced forcing. Tidally modulated and rain-induced flow rates were comparable during this period. The SGD rates estimated from radon ranged from 1 cm/day to 29 cm/day (cm3/cm2 day) with a mean and standard deviation of 13 ± 6 cm/day. These estimates were mostly similar to a dye-dilution automatic seepage meter (15 ± 19 cm/day) and were within the broad ranges estimated by manual and continuous heat seepage meters but lower than indicated by an artificial tracer test performed nearshore.
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chapter 5 uranium and thorium series nuclides as tracers of submarine groundwater discharge
Radioactivity in the Environment, 2008Co-Authors: Mathew A Charette, Willard S Moore, William C BurnettAbstract:Publisher Summary A number of U- and Th-series Isotopes have become popular tools for quantifying submarine groundwater discharge (SGD). These isotopic techniques enable large-scale estimates of various components of SGD, allowing detailed studies on the processes involved. Radium Isotopes have proven to be useful tracers of total SGD in many environments on both small- and large scales. The existence of four naturally occurring Radium Isotopes makes Ra particularly useful for quantifying multiple sources of SGD. The utility of 222 Rn as a tracer of SGD has been demonstrated in a wide range of environments from coastal embayments to the coastal ocean. The approach for quantifying SGD using 222 Rn is similar to Radium ( 226 Ra), except for a few key differences. The 222 Rn signature of SGD is best observed near the source because of its short half-life. In contrast, 226 Ra has the ability to integrate the SGD signal over much wider spatial scales. Finally, of the intercomparison studies conducted till date, there appears to be no systematic difference in the two techniques based on the coastal hydrogeologic setting, though a wider range of estimates has been typically observed in areas with fractured crystalline rock aquifers and where springs have been a major conduit for SGD. More recently, the geochemical budget for uranium has been shown to be impacted by SGD. As uranium is enriched in seawater relative to most coastal groundwater, the observed depletion of uranium in estuarine and coastal waters may provide an estimate of the seawater component of SGD that recharges coastal aquifers, or submarine groundwater recharge (SGR). Additionally, new isotope techniques for in situ study are under development including underwater g-spectrometry and continuous radon monitoring. These techniques may be more useful for location of SGD discharges rather than estimation of their magnitudes.
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seasonal changes in the Radium 226 distribution on the southeastern usa continental shelf implications for changing submarine groundwater discharge
IAHS-AISH publication, 2007Co-Authors: Willard S MooreAbstract:Enrichments of Radium Isotopes in coastal waters have served as indicators of submarine groundwater discharge (SGD). Because coastal waters exchange with the open ocean on a time scale of weeks to months, seasonal patterns of Radium isotope distribution may be used to indicate changes in SGD through the year. Here I report the seasonal distributions of 226 Ra measured in surface waters of the continental shelf of southeastern USA. The study area encompassed most of the South Atlantic Bight. Activities of 226 Ra were highest off the coast of Georgia. In summer, these high activities extended throughout the study area; but during spring and winter they decreased markedly off the coast of South Carolina. The primary source of excess 226 Ra (that is activities in excess of open ocean values) is SGD. Because the activities of 226 Ra in SGD vary little with season, the lower excess activities off South Carolina imply lower rates of SGD during the spring and winter.
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23 seasonal changes in the Radium 226 distribution on the southeastern usa continental shelf implications for changing submarine groundwater discharge
Tunnelling and Underground Space Technology, 2007Co-Authors: Willard S MooreAbstract:Enrichments of Radium Isotopes in coastal waters have served as indicators of submarine groundwater discharge (SGD). Because coastal waters exchange with the open ocean on a time scale of weeks to months, seasonal patterns of Radium isotope distribution may be used to indicate changes in SGD through the year. Here I report the seasonal distributions of 226 Ra measured in surface waters of the continental shelf of southern USA. The study area encompassed most of the South Atlantic Bight. Activities of 226 Ra were highest off the coast of Georgia. In summer, these high activities extended throughout the study area; but during the spring and winter they decreased markedly off the coast of South Carolina. The primary source of excess 226 Ra (that is activities in excess of open ocean values) is SGD. Because the activities of 226 Ra in SGD vary little with season, the lower excess activities off South Carolina imply lower rates of SGD during the spring and winter.
William C Burnett - One of the best experts on this subject based on the ideXlab platform.
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applications of radon and Radium Isotopes to determine submarine groundwater discharge and flushing times in todos os santos bay brazil
Journal of Environmental Radioactivity, 2017Co-Authors: Vanessa Hatje, Karina Kammer Attisano, Marcelo Friederichs Landim De Souza, B P Mazzilli, Joselene De Oliveira, Tamires De Araujo Mora, William C BurnettAbstract:Todos os Santos Bay (BTS) is the 2nd largest bay in Brazil and an important resource for the people of the State of Bahia. We made measurements of radon and Radium in selected areas of the bay to evaluate if these tracers could provide estimates of submarine groundwater discharge (SGD) and flushing times of the Paraguacu Estuary and BTS. We found that there were a few areas along the eastern and northeastern shorelines that displayed relatively high radon and low salinities, indicating possible sites of enhanced SGD. A time-series mooring over a tidal cycle at Marina do Bonfim showed a systematic enrichment of the short-lived Radium Isotopes 223Ra and 224Ra during the falling tide. Assuming that the elevated Radium Isotopes were related to SGD and using measured Radium activities from a shallow well at the site, we estimated groundwater seepage at about 70 m3/day per unit width of shoreline. Extrapolating to an estimated total shoreline length provided a first approximation of total (fresh + saline) SGD into BTS of 300 m3/s, about 3 times the average river discharge into the bay. Just applying the shoreline lengths from areas identified with high radon and reduced salinity results in a lower SGD estimate of 20 m3/s. Flushing times of the Paraguacu Estuary were estimated at about 3-4 days based on changing Radium isotope ratios from low to high salinities. The flushing time for the entire BTS was also attempted using the same approach and resulted in a surprisingly low value of only 6-8 days. Although physical oceanographic models have proposed flushing times on the order of months, a simple tidal prism calculation provided results in the range of 4-7 days, consistent with the Radium approach. Based on these initial results, we recommend a strategy for refining both SGD and flushing time estimates.
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natural radon and Radium Isotopes for assessing groundwater discharge into little lagoon al implications for harmful algal blooms
Estuaries and Coasts, 2014Co-Authors: William C Burnett, Richard N Peterson, Hugh L Macintyre, Justin D Liefer, Richard VisoAbstract:Naturally occurring Isotopes of radon (222Rn) and Radium Isotopes (223,224,226,228Ra) were used as tracers to assess submarine groundwater discharge (SGD) into Little Lagoon, AL (USA), a site of recurring harmful algal blooms (HABs). The Radium isotopic data suggests that there are two groundwater sources of these tracers to the lagoon, a shallow (A1) and deeper (A2) aquifer. We estimated the fraction of each source via a three-end-member mixing model consisting of Gulf of Mexico seawater, shallow and deep groundwater. The estimated lagoonwide SGD rates based on a Radium mass balance and the mixing model were 1.22 ± 0.53 and 1.59 ± 0.20 m3 s-1 for the shallow and deep groundwater discharges, respectively. To investigate temporal variations in SGD, we performed several radon surveys from 2010 through 2012, a period of generally declining groundwater levels due to a drought in the southeastern USA. The total SGD rates based on a radon mass balance approach were found to vary from 0.60 to 2.87 m3 s-1. We observed well-defined relationships between nutrients and chlorophyll-a in lagoon waters during a period when there was an intense diatom bloom in April 2010 and when no bloom existed in March 2011. A good correlation was also found between Radium (groundwater-derived) and nutrients during the April 2010 period, while there was no clear relationship between the same parameters in March 2011. Based on multivariate analysis of chemical and environmental factors, we suggest that nutrient-rich inputs during high SGD may be a significant driver of algal blooms, but during low SGD periods, multiple drivers are responsible for the occurrence of algal blooms.
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significant lateral inputs of fresh groundwater into a stratified tropical estuary evidence from radon and Radium Isotopes
Marine Chemistry, 2010Co-Authors: Richard N Peterson, Isaac R Santos, Bradley D Eyre, William C BurnettAbstract:Abstract River discharges are usually gauged at sites farther upstream than estuarine tidal reaches. As a result, global estimates of river water and nutrient fluxes to the ocean are likely underestimated as they often neglect groundwater discharge occurring in estuaries downstream of river gauging stations. We used radon and Radium Isotopes as tracers of groundwater discharge into the Sebastian River Estuary, a gaining stream in Florida, USA. We developed a spatially-distributed mass balance model that accounts for radon sources and sinks in waters above and below the estuarine pycnocline. Radium Isotopes ( 224 Ra, 223 Ra, and 226 Ra) were not enriched in groundwater relative to surface water and thus had limited usefulness as tracers at this specific site. The detection of fresh groundwater just beneath the sediment:water interface overlain by brackish bottom water implies that fresh groundwater dominates over saline groundwater in this salt wedge estuary. Lateral groundwater inputs from sandy banks into waters above the estuarine pycnocline were about 6-fold higher than inputs into waters below the pycnocline. Groundwater discharge rates into the surface layer of the estuary estimated from a radon mass balance ranged from 5 to 18 m 3 /s (or 18 to 62 cm/day if uniformly distributed throughout the entire estuary area). The fluxes into the bottom layer ranged from 0.8 to 1.1 m 3 /s (or 2.8 to 3.9 cm/day). These groundwater inputs augmented river discharges gauged upstream of the estuary tidal reaches by about 260% during the dry period and 135% during the wet period. As nutrient and other dissolved species are often highly enriched in groundwaters, groundwater probably controls surface water quality in this and other Florida estuaries.
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radon and Radium isotope assessment of submarine groundwater discharge in the yellow river delta china
Journal of Geophysical Research, 2008Co-Authors: Richard N Peterson, William C Burnett, Isaac R Santos, Makoto Taniguchi, Jianyao Chen, Tomotoshi IshitobiAbstract:[1] Naturally occurring chemical tracers were used to assess the magnitude of submarine groundwater discharge (SGD) during two different sampling periods at a coastal site south of the Yellow River delta, China. We used salinity and pH as indicators of the terrestrial and recirculated seawater components of discharging groundwater and Radium Isotopes to quantify offshore transport rates. We then used an hourly time series of multiple Radium Isotopes (224Ra, 223Ra, and 226Ra) to quantify SGD rates and also used 222Rn and seepage meters to independently quantify SGD rates as a comparison to the Radium results. Offshore transport rates were found to range from 3.3 to 4.7 cm s−1. Modeled time series Radium activities indicated average SGD rates ranging from 4.5 to 13.9 cm d−1 in September 2006 and from 5.2 to 11.8 cm d−1 in July 2007. Temporal trends associated with the Radium approach agree with SGD patterns revealed by automated seepage meters deployed nearby, but the absolute fluxes are about 70% lower than those determined by the seepage meters. Modeled SGD rates based on 222Rn (mean = 13.8 cm d−1 in 2006 and 8.4 cm d−1 in 2007) agree with those determined by the Radium analysis. Differences in derived SGD rates between the different Radium Isotopes (226Ra highest; 224Ra lowest) are likely results of uncertainties in the background activities and our limited selection of appropriate groundwater/pore water end-member values. Scaling our results to the entire Yellow River delta, we find SGD fluxes (and corresponding nitrate fluxes) 2–3 times that of the Yellow River.
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radon and Radium Isotopes as tracers of submarine groundwater discharge results from the ubatuba brazil sgd assessment intercomparison
Estuarine Coastal and Shelf Science, 2008Co-Authors: William C Burnett, Willard S Moore, Richard N Peterson, Joselene De OliveiraAbstract:Abstract We determined groundwater flow rates shortly after the wet season into an embayment near Ubatuba, Brazil as part of an international intercomparison experiment for submarine groundwater discharge (SGD) assessment techniques. Our estimated rates were determined by the combined use of continuous radon measurements and assessment of Radium isotope patterns. The spatial distribution of the short-lived Radium Isotopes (223Ra and 224Ra) provided the means for independent evaluations of radon losses by mixing and atmospheric evasion. We were thus able to construct a well-constrained mass balance for radon that included a groundwater flux term. Our results showed that the groundwater discharge into this embayment from the fractured crystalline rock aquifer is not steady-state but varies with tidal modulation and rain-induced forcing. Tidally modulated and rain-induced flow rates were comparable during this period. The SGD rates estimated from radon ranged from 1 cm/day to 29 cm/day (cm3/cm2 day) with a mean and standard deviation of 13 ± 6 cm/day. These estimates were mostly similar to a dye-dilution automatic seepage meter (15 ± 19 cm/day) and were within the broad ranges estimated by manual and continuous heat seepage meters but lower than indicated by an artificial tracer test performed nearshore.
Adina Paytan - One of the best experts on this subject based on the ideXlab platform.
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methane transport through submarine groundwater discharge to the north pacific and arctic ocean at two alaskan sites
Limnology and Oceanography, 2016Co-Authors: Alanna L Lecher, J D Kessler, Katy J Sparrow, Fenix Garciatigreros Kodovska, Natasha Dimova, Joseph Murray, Slawek Tulaczyk, Adina PaytanAbstract:Here, we quantify the flux of methane to the coastal Arctic and North Pacific Oceans via submarine groundwater discharge (SGD), by use of naturally occurring Radium Isotopes as groundwater tracers, combined with methane concentration measurements of coastal groundwater. Our findings indicate the flux of methane through this process is much greater in the coastal North Pacific (35 6 27 mg m 21 d 21 ) than the Arctic Ocean (4.1 6 0.6 to 11.8 6 3.9 mg m 21 d 21 ). The dominant controls on methane flux through SGD were not methane concentrations in the aquifer but rather the hydrologic characteristics of each site that mitigated or intensified the SGD water volume flux (120 6 50 m 3 m 21 d 21 in the North Pacific compared to 12 6 4m 3 m 21 d 21 in the Arctic). Tidal pumping was observed to be an especially important control on SGD flux at the North Pacific site.
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characterizing sources of groundwater to a tropical coastal lagoon in a karstic area using Radium Isotopes and water chemistry
Marine Chemistry, 2008Co-Authors: Megan B Young, Willard S Moore, Meagan Eagle Gonneea, Derek A Fong, Jorge A Herrerasilveira, Adina PaytanAbstract:Radium Isotopes ( 223 Ra, 224 Ra, 226 Ra, and 228 Ra) and water chemistry were used to identify two chemically distinct sources of submarine groundwater discharge (SGD) in Celestun Lagoon, Yucatan, Mexico. Low salinity groundwater discharging from springs within the lagoon has previously been identified and extensively sampled for nutrient concentrations. However, a second type of groundwaterdischargingintothelagoonwasdetectedduringthisstudyusingRadiumisotopeactivitymeasurements.Thissecondtype of groundwater is characterized by moderate salinities (within the range of lagoon salinities) and very elevated Radium activities in comparison to the low salinity groundwater, mixed lagoon water, and seawater. Further analysis showed that the two types of groundwater also have distinct chloride, strontium, and sulfate ratios, along with slightly different nutrient concentrations. Groundwater discharge occurs through large and small springs scattered throughout the lagoon, and both types of groundwater were detected discharging from one of the larger springs. The relative proportions of low salinity groundwater and brackish high Radium groundwater varied over the tidal cycle. In order to better understand the relative contributions of each type of groundwater to the lagoon, athreeend-member mixingmodel basedonthe distinct chemical andisotopic compositions ofbothtypes ofgroundwater and of seawater was used to estimate the distribution of each water type throughout the lagoon in different seasons. This study suggests that substantial groundwater discharge to the lagoon can occur during both dry and rainy seasons. The presence of two groundwater sources has implications for monitoring and protection of the Celestun Lagoon Biosphere Reserve, since the two sources may have different susceptibilities to anthropogenic contamination depending on their respective recharge area and recharge rates. © 2007 Elsevier B.V. All rights reserved.
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the importance of submarine groundwater discharge to the near shore nutrient supply in the gulf of aqaba israel
Limnology and Oceanography, 2006Co-Authors: Gregory G Shellenbarger, Stephen G Monismith, Amatzia Genin, Adina PaytanAbstract:We used two short-lived Radium Isotopes (223Ra, 224Ra) and a mass balance approach applied to the Radium activities to determine the nutrient contribution of saline submarine groundwater discharge to the coastal waters of the northern Gulf of Aqaba (Israel). Radium isotope activities were measured along transects during two seasons at a site that lacked any obvious surficial water input. An onshore well and an offshore end member were also sampled. For all samples, nutrients and salinity data were collected. Radium isotope activities generally decreased with distance offshore and exhibited significant tidal variability, which is consistent with a shorederived tidally influenced source. Submarine groundwater contributes only 1–2% of the water along this coast, but this groundwater provides 8–46% of the nutrients. This saline groundwater is derived predominately from tidally pumped seawater percolating through the unconfined coastal aquifer and leaching Radium and nutrients. This process represents a significant source of nutrients to the oligotrophic nearshore reef.
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groundwater discharge potential association with fecal indicator bacteria in the surf zone
Environmental Science & Technology, 2004Co-Authors: Alexandria B Boehm, Gregory G Shellenbarger, Adina PaytanAbstract:Short-lived Radium Isotopes (223Ra and 224Ra) are used to investigate the potential association between groundwater discharge and microbial pollution at Huntington Beach, CA. We establish the tidally driven exchange of groundwater from the surficial beach aquifer across the beach face. Groundwater is found to be a source of nutrients (silica, inorganic nitrogen, and orthophosphate) to the surf zone, and these nutrients could possibly provide an environment for enhanced growth or increased persistence of fecal indicator bacteria (FIB). Ammonium and ortho-phosphate explain up to 12−20% of the variance in FIB levels in the surf zone. Elevated levels of FIB were only found in 1 of the 26 groundwater samples. However, FIB in the surf zone covary with Radium at fortnightly, diurnal, and semi-diurnal tidal periods. In addition, Radium accounts for up to 38% of the variance in log-FIB levels in the surf zone. A column experiment illustrates that Enterococcus suspended in Huntington Beach saline groundwater is not...
Goldkuhle A. - One of the best experts on this subject based on the ideXlab platform.
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Evolution of Octupole Deformation in Radium Nuclei from Coulomb Excitation of Radioactive Ra 222 and Ra 228 Beams
'American Physical Society (APS)', 2021Co-Authors: Butler P.a., Spagnoletti P, Abrahams K, Bowry M, Cederkäll J, Gaffney L.p., G. De ,angelis, H. De ,witte, Goldkuhle A.Abstract:6 pags., 5 figs., 1 tab.There is sparse direct experimental evidence that atomic nuclei can exhibit stable "pear" shapes arising from strong octupole correlations. In order to investigate the nature of octupole collectivity in Radium Isotopes, electric octupole (E3) matrix elements have been determined for transitions in Ra222,228 nuclei using the method of sub-barrier, multistep Coulomb excitation. Beams of the radioactive Radium Isotopes were provided by the HIE-ISOLDE facility at CERN. The observed pattern of E3 matrix elements for different nuclear transitions is explained by describing Ra222 as pear shaped with stable octupole deformation, while Ra228 behaves like an octupole vibrator.The support of the ISOLDE Collaboration and technical teams is acknowledged. This work was supported by the following Research Councils and Grants: Science and Technology Facilities Council (UK) Grants No. ST/P004598/1, No. ST/L005808/1, No. ST/ R004056/1; Federal Ministry of Education and Research (Germany) Grants No. 05P18RDCIA, No. 05P15PKCIA, and No. 05P18PKCIA and the “Verbundprojekt 05P2018”; National Science Centre (Poland) Grant No. 2015/18/M/ ST2/00523; European Union’s Horizon 2020 Framework research and innovation programme 654002 (ENSAR2); Marie Skłodowska-Curie COFUND Grant (EU-CERN) 665779; Research Foundation Flanders and IAP Belgian Science Policy Office BriX network P7/12 (Belgium); GOA/2015/010 (BOF KU Leuven); RFBR (Russia) Grant No. 17-52-12015; and the Academy of Finland (Finland) Grant No. 307685
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Evolution of Octupole Deformation in Radium Nuclei from Coulomb Excitation of Radioactive $^{222}\mathrm{Ra}$ and $^{228}\mathrm{Ra}$ Beams
'American Physical Society (APS)', 2020Co-Authors: Butler P.a., Spagnoletti P, Abrahams K, Bowry M, Cederkäll J, Gaffney L.p., De Angelis G., De Witte H., Goldkuhle A.Abstract:There is sparse direct experimental evidence that atomic nuclei can exhibit stable pear shapes arising from strong octupole correlations. In order to investigate the nature of octupole collectivity in Radium Isotopes, electric octupole ($E3$) matrix elements have been determined for transitions in $^{222,228}$Ra nuclei using the method of sub-barrier, multi-step Coulomb excitation. Beams of the radioactive Radium Isotopes were provided by the HIE-ISOLDE facility at CERN. The observed pattern of $E$3 matrix elements for different nuclear transitions is explained by describing $^{222}$Ra as pear-shaped with stable octupole deformation, while $^{228}$Ra behaves like an octupole vibrator.There is sparse direct experimental evidence that atomic nuclei can exhibit stable pear shapes arising from strong octupole correlations. In order to investigate the nature of octupole collectivity in Radium Isotopes, electric octupole ($E3$) matrix elements have been determined for transitions in $^{222,228}$Ra nuclei using the method of sub-barrier, multi-step Coulomb excitation. Beams of the radioactive Radium Isotopes were provided by the HIE-ISOLDE facility at CERN. The observed pattern of $E$3 matrix elements for different nuclear transitions is explained by describing $^{222}$Ra as pear-shaped with stable octupole deformation, while $^{228}$Ra behaves like an octupole vibrator
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Evolution of Octupole Deformation in Radium Nuclei from Coulomb Excitation of Radioactive 222Ra and 228Ra Beams
'American Physical Society (APS)', 2020Co-Authors: Pa Butler, Spagnoletti P, Abrahams K, Bowry M, Cederkäll J, De Angelis G., De Witte H., Lp Gaffney, Goldkuhle A.Abstract:There is sparse direct experimental evidence that atomic nuclei can exhibit stable "pear" shapes arising from strong octupole correlations. In order to investigate the nature of octupole collectivity in Radium Isotopes, electric octupole (E3) matrix elements have been determined for transitions in ^{222,228}Ra nuclei using the method of sub-barrier, multistep Coulomb excitation. Beams of the radioactive Radium Isotopes were provided by the HIE-ISOLDE facility at CERN. The observed pattern of E3 matrix elements for different nuclear transitions is explained by describing ^{222}Ra as pear shaped with stable octupole deformation, while ^{228}Ra behaves like an octupole vibrator.status: publishe
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Evolution of Octupole Deformation in Radium Nuclei from Coulomb Excitation of Radioactive ^{222}Ra and ^{228}Ra Beams
'American Physical Society (APS)', 2020Co-Authors: Butler P. A., Spagnoletti P, Abrahams K, Bowry M, Cederkäll J, De Angelis G., De Witte H., Gaffney L. P., Garrett P. E., Goldkuhle A.Abstract:There is sparse direct experimental evidence that atomic nuclei can exhibit stable "pear" shapes arising from strong octupole correlations. In order to investigate the nature of octupole collectivity in Radium Isotopes, electric octupole (E3) matrix elements have been determined for transitions in ^{222,228}Ra nuclei using the method of sub-barrier, multistep Coulomb excitation. Beams of the radioactive Radium Isotopes were provided by the HIE-ISOLDE facility at CERN. The observed pattern of E3 matrix elements for different nuclear transitions is explained by describing ^{222}Ra as pear shaped with stable octupole deformation, while ^{228}Ra behaves like an octupole vibrator
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Evolution of Octupole Deformation in Radium Nuclei from Coulomb Excitation of Radioactive 222Ra and 228Ra Beams
'American Physical Society (APS)', 2020Co-Authors: Butler P. A., Spagnoletti P, Abrahams K, Bowry M, Cederkäll J, De Angelis G., De Witte H., Gaffney L. P., Garrett P. E., Goldkuhle A.Abstract:There is sparse direct experimental evidence that atomic nuclei can exhibit stable “pear” shapes arising from strong octupole correlations. In order to investigate the nature of octupole collectivity in Radium Isotopes, electric octupole (E3) matrix elements have been determined for transitions in 222,228Ra nuclei using the method of sub-barrier, multistep Coulomb excitation. Beams of the radioactive Radium Isotopes were provided by the HIE-ISOLDE facility at CERN. The observed pattern of E3 matrix elements for different nuclear transitions is explained by describing 222Ra as pear shaped with stable octupole deformation, while 228Ra behaves like an octupole vibrator.peerReviewe
Pieter Van Beek - One of the best experts on this subject based on the ideXlab platform.
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early diagenesis of Radium 226 and Radium 228 in lacustrine sediments influenced by former mining sites
Journal of Environmental Radioactivity, 2020Co-Authors: Arnaud Mangeret, Jean-louis Reyss, Antoine Thouvenot, Marina Sedercolomina, Lucie Stetten, Guillaume Morin, Marc Souhaut, Pieter Van BeekAbstract:Abstract Radium is a naturally occurring radioactive element commonly found at low levels in natural systems such as lacustrine or marine sediments. Anthropogenic activities including former uranium mining activities can lead to the dissemination of Radium Isotopes having high radiological toxicities, which potentially threaten the safety of nearby environments. Although Radium mobility in oxidized environments is known to be largely governed by sorption/desorption onto Fe and Mn oxyhydroxides and coprecipitation with sulfate minerals (e.g. barite), little is known regarding its behavior under reducing conditions, which are the conditions typically encountered in organic-rich systems such as wetlands and lake sediments. The present study aims at understanding the behavior of long-lived Radium Isotopes (226Ra and 228Ra), during early diagenesis of lake sediments contaminated by former uranium mining activities. Solid and pore water concentrations of 226Ra and 228Ra were determined using ultra low background gamma spectrometry, which allowed improvement of detection limits and measurement accuracy. This study shows that the downcore distribution of Radium Isotopes is closely related to the reductive dissolution of iron and manganese oxyhydroxides below the sediment-water interface. The resulting diffusive fluxes of 226Ra and 228Ra (4.1 10−25 and 4.7 10−28 mol cm−2.s−1) are however significantly lower than other Radium-impacted environments, such as uranium mill tailings pond and phosphate industry-impacted sediments, and are similar to those reported for natural marine environments. Hence, in the reduced lake sediments of Saint-Clement, the major fraction of Radium is trapped by the solid phase, while early diagenesis only induces a slight mobility of this radioelement.
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Combining airborne thermal infrared images and Radium Isotopes to study submarine groundwater discharge along the French Mediterranean coastline
Elsevier, 2017Co-Authors: Simon Bejannin, Marc Souhaut, Pieter Van Beek, Thomas Stieglitz, Joseph TamborskiAbstract:Study region: The French Mediterranean coastline, which includes karstic springs discharging into coastal seas and coastal lagoons. Study focus: We investigated submarine groundwater discharge (SGD), an important vector for many chemical elements that may impact the quality of the coastal environment. First, we acquired airborne thermal infrared (TIR) images to detect terrestrial groundwater inputs. Then we report in situ data (salinity; temperature; Radium Isotopes). We use these data i) to confirm the presence of groundwater discharge and to characterize the different systems, and ii) to quantify SGD fluxes and estimate the residence time of the water bodies. New hydrological insights for the region: Few studies have been conducted on SGD along the French Mediterranean coastline. The terrestrial groundwater spring inputs in La Palme and Salses-Leucate coastal lagoons are in the range (0.04–0.11) m3 s−1, ≤ 2% of the local river inputs. In comparison, total SGD estimates to La Palme lagoon (0.56–1.7 m3 s−1) suggest that the recirculation of lagoon water through the sediment is two orders of magnitude greater than the terrestrial groundwater inputs. At the Calanque of Port-Miou, the terrestrial groundwater flux to the coastal seas was between 0.6 and 1.2 m3 s−1 in July 2009. This study demonstrates the application of airborne TIR remote sensing for detecting surficial groundwater springs, and the inability of the method to detect deeper, submerged springs