Anthropogenic 236U and 129I in the Mediterranean Sea: First comprehensive distribution and constrain of their sources

Castrillejo, Maxi; Casacuberta, Núria; Christl, Marcus; García-Orellana, Jordi; Vockenhuber, Christof; Synal, H.-A.; Masqué, Pere

doi:10.1016/j.scitotenv.2017.03.201

Cited by 26 publications

(12 citation statements)

References 65 publications

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“…Potential temperature versus salinity plots allow us to identify the water masses sampled (Figure 2). Modified Atlantic Waters (MAW) were partially mixed with Winter Intermediate Waters (WIW) at the first sampling depth of 100 m. Below, 250 m and 500 m depth samples correspond to Levantine Intermediate Waters (LIW), except for the 250 m sample of St. 21, which falls on the WIW layer (Castrillejo et al, 2017). All the other samples from 1000 m depth to the bottom were taken within the Western Mediterranean Deep Waters (WMDW).…”

Section: Resultsmentioning

confidence: 99%

Balancing Rare Earth Element distributions in the Northwestern Mediterranean Sea

García-Solsona

Jeandel

2020

Chemical Geology

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Elemental concentrations of Rare Earth Elements (REE) and isotopic compositions of Neodymium ( Nd ) have been measured in three water column profiles in the North Western Mediterranean Sea. Clear enrichments of REE are observed when comparing to adjacent Atlantic waters suggesting REE inputs along the circulation in this area. For the first time, relative proportions of external sources including submarine groundwater discharges (SGD) have been quantified for the studied area. Atmospheric deposition is estimated to be the most important external source for all the REE with an average contribution of 44%, followed by diffusion from porewaters, which provide a 30%. Dissolved riverine fluxes account for 11%, SGD for 10% and dissolution of remobilized surface sediments the remaining 6%. Mass balances accounting for seawater transport and identified external sources have been delineated for the three main water masses (Modified Atlantic Waters, Levantine Intermediate Waters and Western Mediterranean Deep Waters). They show that the balances of REE in this area are Highlights Significance of dissolved REE transport and external inputs in the NW Mediterranean Sea Determination of REE fluxes associated with SGD and dissolution of reworked sediments Importance of reversible scavenging for REE in seawater

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Section: Resultsmentioning

confidence: 99%

Balancing Rare Earth Element distributions in the Northwestern Mediterranean Sea

García-Solsona

Jeandel

2020

Chemical Geology

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“…The preparation of samples for 236 U measurements followed the method of Casacuberta et al () and Castrillejo et al (). Samples were collected in calibrated 3‐ to 5‐L plastic bottles, acidified to pH 2 with concentrated HNO 3 , and spiked with about 3pg 233 U (IRMM_051 spike).…”

Section: Methodsmentioning

confidence: 99%

“…129 I transport and distribution in the North Atlantic and Arctic Ocean have also been subject to modeling approaches (Karcher et al, ; Orre et al, ). This is less the case for 236 U, which has only emerged as a new water mass tracer in recent years (Casacuberta et al, ; Castrillejo et al, ; Christl et al, ; Christl, Lachner, et al, ; Christl et al, ; Qiao et al, ; Sakaguchi et al, , ; Steier et al, ). For the Fram Strait, so far only one study presented the 129 I distribution (Alfimov, Aldahan, & Possnert, ), while no 236 U data from this domain were available up to date.…”

Section: Introductionmentioning

confidence: 99%

Tracing Atlantic Waters Using ¹²⁹I and ²³⁶U in the Fram Strait in 2016

et al. 2019

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In this study 129I and 236U concentrations in seawater samples collected onboard R/V Polarstern during the PS100 expedition in the Fram Strait in 2016 are presented. The overall aim of the study was to investigate the distribution of these long‐lived radionuclides along the transect located at 79°N. The combination of both radionuclides was used for the first time in the Fram Strait to trace ocean circulation pathways of Atlantic waters. Results show that both 129I and 236U concentrations as well as 236U/238U ratios are about two times higher (> 600 × 107 at kg(−1), > 20 × 106 at kg(−1), and 2.8 × 10−9, respectively) in the cold and fresh outflowing surface waters from the Arctic Ocean (Polar Surface Water, PSW) compared to inflowing Atlantic origin waters (300 × 107 at kg(−1) 129I, 12 × 106 at kg(−1) 236U, and 1.4 × 10−9 236U/238U). A comparison with the different 129I and 236U input functions for the Atlantic branches entering the Arctic Ocean reveals that the middepth Atlantic origin waters outflowing the Arctic Ocean show more influence of the Barents Sea Branch Water than the Fram Strait Branch Water. The high radionuclide concentrations observed in the PSW indicate substantial influence of the Norwegian Coastal Current. This current carries a significantly larger proportion of 129I and 236U releases from European reprocessing plants than the aforementioned Atlantic branches. We estimate surface water transit times from the northern Norwegian Coast through the Arctic to the PSW of 12–19 years, less than for the middepth Barents Sea Branch Water (16–23 years).

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“…[1][2][3][4] Besides a minor amount of naturally produced 236 U, 5 the majority of environmental 236 U was released through anthropogenic nuclear activities, including atmospheric nuclear weapon tests, 1,6-8 authorized discharges of nuclear reprocessing plants 9 and nuclear accidents [10][11][12] . The pulse injection of anthropogenic 236 U results in a wide scale of 236 U/ 238 U atomic ratios (10 -13 -10 -6 ) in the global oceanic systems (Figure 1), 1,7,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]29,30 which roughly corresponds to a range of (10 3 -10 9 ) atoms/kg for 236 U concentrations in seawater.This makes 236 U a suitable transient tracer to investigate the oceanic circulation patterns, water masses mixing, and transit time.Recent developments of the AMS technique enable the measurement and tracer application of another long-lived anthropogenic uranium isotope 233 U (t1/2 = 0.16 Myr) in the environment. 3,30,31 Different from 236 U, the only massive emission of anthropogenic 233 U occurred during the global fallout of nuclear weapons testing (GF).…”

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confidence: 99%

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On the Quality Control for the Determination of Ultratrace-Level ²³⁶U and ²³³U in Environmental Samples by Accelerator Mass Spectrometry

et al. 2021

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Our recent attempt to determine ultra-trace level 236 U and 233 U in small volume seawater samples was challenged by high and unstable procedure blanks in our environmental radioactivity laboratory, which used to be a spent fuel research facility. Through intercomparison experiments with different laboratories and background checks on the chemical reagents and laboratory dust, the resuspended U-bearing dust was identified as the dominating source of the 236 U and 233 U contamination.With the implementation of background control (especially dust control) measures, the procedure blanks and detection limits of 236 U and 233 U for the radiochemical separation procedure has been significantly improved by three orders of magnitudes. With well-controlled blanks, the analytical precision for 236 U and 233 U predominantly relies on the AMS counting statistics. Background check and dust control are strongly recommended before the analyses of environmental level long-lived radionuclides (such as 236 U and 233 U) that are conducted in the former or active nuclear facilities, even if clearance of radioactivity relevant for radioprotection was achieved.The long-lived uranium isotope 236 U (t1/2 = 23.4 Myr) has become a popular tracer in oceanic studies because of improved measurement techniques by accelerator mass spectrometry (AMS) and its excellent properties, including high solubility, long residence time, and conservative features. [1][2][3][4] Besides a minor amount of naturally produced 236 U, 5 the majority of environmental 236 U was released through anthropogenic nuclear activities, including atmospheric nuclear weapon tests, 1,6-8 authorized discharges of nuclear reprocessing plants 9 and nuclear accidents [10][11][12] . The pulse injection of anthropogenic 236 U results in a wide scale of 236 U/ 238 U atomic ratios (10 -13 -10 -6 ) in the global oceanic systems (Figure 1), 1,7,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]29,30 which roughly corresponds to a range of (10 3 -10 9 ) atoms/kg for 236 U concentrations in seawater.This makes 236 U a suitable transient tracer to investigate the oceanic circulation patterns, water masses mixing, and transit time.Recent developments of the AMS technique enable the measurement and tracer application of another long-lived anthropogenic uranium isotope 233 U (t1/2 = 0.16 Myr) in the environment. 3,30,31 Different from 236 U, the only massive emission of anthropogenic 233 U occurred during the global fallout of nuclear weapons testing (GF). In contrast, little 233 U is produced by nuclear reactors and released from reprocessing plants or nuclear accidents. 3 The representative level of the 233 U/ 236 U atomic ratio in natural reservoirs exposed to GF is estimated to be (1.40 ± 0.15) × 10 -2 by a recent study on a peat core (Black forest, Germany), 3 while the documented levels in the discharges of the nuclear reprocessing plant at La Hague are 10 -7 -10 -6 (HELCOM MORS Discharge database). 32 In the Irish Sea, an average 233 U/ 236 U atomic ratio of (0.12 ±...

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Anthropogenic 236U and 129I in the Mediterranean Sea: First comprehensive distribution and constrain of their sources

Cited by 26 publications

References 65 publications

Balancing Rare Earth Element distributions in the Northwestern Mediterranean Sea

Balancing Rare Earth Element distributions in the Northwestern Mediterranean Sea

Tracing Atlantic Waters Using ¹²⁹I and ²³⁶U in the Fram Strait in 2016

On the Quality Control for the Determination of Ultratrace-Level ²³⁶U and ²³³U in Environmental Samples by Accelerator Mass Spectrometry

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Anthropogenic 236U and 129I in the Mediterranean Sea: First comprehensive distribution and constrain of their sources

Cited by 26 publications

References 65 publications

Balancing Rare Earth Element distributions in the Northwestern Mediterranean Sea

Balancing Rare Earth Element distributions in the Northwestern Mediterranean Sea

Tracing Atlantic Waters Using 129I and 236U in the Fram Strait in 2016

On the Quality Control for the Determination of Ultratrace-Level 236U and 233U in Environmental Samples by Accelerator Mass Spectrometry

Contact Info

Product

Resources

About

Tracing Atlantic Waters Using ¹²⁹I and ²³⁶U in the Fram Strait in 2016

On the Quality Control for the Determination of Ultratrace-Level ²³⁶U and ²³³U in Environmental Samples by Accelerator Mass Spectrometry