Organically bound tritium (OBT) and carbon-14 accumulation in the sediments off the mouth of the Rhône river

Jean‐Baptiste, Philippe; Fontugne, M.; Fourré, Élise; Charmasson, Sabine; Marang, Laura; Siclet, F.

doi:10.1007/s12665-019-8081-y

Cited by 6 publications

(4 citation statements)

References 35 publications

(41 reference statements)

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“…During this period, the particulate organic carbon discharged during the flood and deposited in the Rhône pro-delta was a mixture of fresh POC (∆ 14 C=–110‰) and an older particulate carbon removed from the river catchment basin or resuspended from the bottom of the river. Previous studies of prodelta sediment cores show that OM 14 C activity during this period ranged between ∆ 14 C=–600‰ and ∆ 14 C=–400‰ depending on the distance from the mouth of the Rhône river (Cathalot et al 2013; Toussaint et al 2013; Jean-Baptiste et al 2018b submitted). Far offshore, under typical marine influence, DIC from Mediterranean Seawater and phytoplankton had 14 C activities around ∆ 14 C=–50‰ during the pre-nuclear period (Siani et al 2000; Tisnérat-Laborde et al 2013).…”

Section: Methodsmentioning

confidence: 82%

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Isotopic Signature (δ¹³C, ∆¹⁴C) of DIC in Sediment Pore Waters: An Example from the Rhone River Delta

Dumoulin

Pozzato²,

Rassman³

et al. 2018

Radiocarbon

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A better understanding of the dynamics of different particulate organic matter (OM) pools in the coastal carbon budget is a key issue for quantifying the role of the coastal ocean in the global carbon cycle. To elucidate the benthic component of this carbon cycle at the land-sea interface, we investigated the carbon isotope signatures (δ13C and ∆14C) in the sediment pore waters dissolved inorganic carbon (DIC) in addition to the sediment OM to constrain the origin of the OM mineralized in sediments. The study site is located at the outlet of the Rhône River (Mediterranean Sea), which was chosen because this river is one of the most nuclearized rivers in Europe and nuclear 14C can serve as a tracer to follow the fate of the OM discharged by the river to the coastal sea. The ∆14C results found in the pore waters DIC show a general offset between buried and mineralized OM following a preferential mineralization model of young and fresh particles. For example, we found that the sediment OM has values with a mean ∆14C=–33‰ at sampling stations near the river mouth whereas enriched ∆14C values around +523‰ and +667‰ respectively were found for the pore waters DIC. This indicates complete mineralization of a riverine fraction of OM enriched in 14C in the river conduit during in-stream photosynthesis. In shelf sediments, the ∆14C of pore waters DIC is slightly enriched (+57‰) with sediment OM reaching –570‰. A mixing model shows that particles mineralized near the river mouth are certainly of riverine phytoplanktonic origin whereas OM mineralized on the shelf is of marine origin. This work highlights the fact that pore waters provide additional information compared to sediments alone and it seems essential to work on both pools to study the carbon budget in river prodelta.

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Section: Methodsmentioning

confidence: 82%

“…At stations A and Z, pore waters DIC-δ 13 C values reached, at depth, values around –23‰ to –25‰, which is slightly higher than that of sediment organic carbon which has varied between –25.5 to –27.5‰ (Lansard et al 2009; Jean-Baptiste et al 2018b submitted) during the last 50 years.…”

Section: Resultsmentioning

confidence: 99%

Isotopic Signature (δ¹³C, ∆¹⁴C) of DIC in Sediment Pore Waters: An Example from the Rhone River Delta

Dumoulin

Pozzato²,

Rassman³

et al. 2018

Radiocarbon

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“…To our knowledge, only three recent studies report OBT analyses along the profile of sedimentary archives. One of them was collected in the upper Rhône River (Eastern France) 1 and the other one at the mouth of this same river 41 , but, in both of these cases, OBT levels recorded reflected a pronounced labelling reaching several thousand Bq/L related to technogenic tritium releases from watchmaking workshops located in the upstream catchments of the Rhône River (residues of tritiated paints, i.e. tritiated polystyrenes 1,9,42 .…”

Section: Pioneering Research Resultsmentioning

confidence: 99%

Evidence for tritium persistence as organically bound forms in river sediments since the past nuclear weapon tests

Eyrolle

Copard

Lepage

et al. 2019

Sci Rep

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Tritium of artificial origin was initially introduced to the environment from the global atmospheric fallout after nuclear weapons tests. Its level was increased in rainwaters by a factor 1000 during peak emissions in 1963 within the whole northern hemisphere. Here we demonstrate that tritium from global atmospheric fallout stored in sedimentary reservoir for decades as organically bound forms in recalcitrant organic matter while tritium released by nuclear industries in rivers escape from such storages. Additionally, we highlight that organically bound tritium concentrations in riverine sediments culminate several years after peaking emission in the atmosphere due to the transit time of organic matter from soils to river systems. These results were acquired by measuring both free and bound forms of tritium in a 70 year old sedimentary archive cored in the Loire river basin (France). Such tritium storages, assumed to be formed at the global scale, as well as the decadal time lag of tritium contamination levels between atmosphere and river systems have never been demonstrated until now. Our results bring new lights on tritium persistence and dynamics within the environment and demonstrate that sedimentary reservoir constitute both tritium sinks and potential delayed sources of mobile and bioavailable tritium for freshwaters and living organisms decades after atmospheric contamination.

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“…While waterborne nutriments, such as valuable amino-acids, might be most likely kept at extremely low concentrations due to biotic activity in the river, any other assimilable molecules, including xenobiotic contaminants or compounds of the degraded organic matter (Eyrolle et al, 2018;Jean-Baptiste et al, 2019), might also be involved in a direct and trophic 14C transfer to aquatic organisms (Saito et al, 1994;Shimizu et al, 1978;Tjeerdema & Crosby, 1988;Velisek et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

Short-term accumulation and elimination of carbon-14 in the common carp Cyprinus carpio under laboratory conditions

Audrey

Camilleri

Cavalié

et al. 2021

Journal of Environmental Radioactivity

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This study examined the short term transfer of carbon-14 (14C) in the common carp Cyprinus carpio under laboratory conditions. Various experiments were achieved in order to investigate direct or trophic transfer for 4 days, using waterborne 14C-labelled arginine or 14C-labelled food pellets respectively. Radiolabelled food was prepared with 14C-labelled arginine or glucose in order to test how transfer kinetics might vary with the biochemical form of 14C.Elimination experiments were achieved using fish fed for 5 days on radiolabelled food and then placed under starvation for 4 days. In all experiments, water, food and fish activities were monitored every day. Different fish fractions (whole body, muscle) were sampled in order to elucidate the role of muscle as a potential storage. Results suggested that direct water-to-fish absorption rate was 20% d-1 per fish. Carps incorporated 14.3% of the absorbed 14C. Fish activity did not increase over days, due to a strong decrease in 14C concentration in the water (resulting from aquarium sorption). During trophic transfer experiments, food was entirely ingested and 14C sources rapidly assimilated. For either arginine or glucose, results suggested that 19-20% of ingested 14C was incorporated, yielding a significant increase in fish activity over days. No difference in mass-specific activity was observed among muscle and whole body. Total activity in the muscle represented 29%-32% of whole body activity, this proportion reflecting the contribution of muscle to whole body weight. During elimination experiments, results showed a significant decrease in whole body total activity and massspecific activity with arginine. The decrease was not significant with glucose due to a great variability among fish. Results suggested that an essential amino-acid like arginine can be used as an energy source under starvation and that muscles can act as a storage for essential amino-acids.

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Organically bound tritium (OBT) and carbon-14 accumulation in the sediments off the mouth of the Rhône river

Cited by 6 publications

References 35 publications

Isotopic Signature (δ¹³C, ∆¹⁴C) of DIC in Sediment Pore Waters: An Example from the Rhone River Delta

Isotopic Signature (δ¹³C, ∆¹⁴C) of DIC in Sediment Pore Waters: An Example from the Rhone River Delta

Evidence for tritium persistence as organically bound forms in river sediments since the past nuclear weapon tests

Short-term accumulation and elimination of carbon-14 in the common carp Cyprinus carpio under laboratory conditions

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Organically bound tritium (OBT) and carbon-14 accumulation in the sediments off the mouth of the Rhône river

Cited by 6 publications

References 35 publications

Isotopic Signature (δ13C, ∆14C) of DIC in Sediment Pore Waters: An Example from the Rhone River Delta

Isotopic Signature (δ13C, ∆14C) of DIC in Sediment Pore Waters: An Example from the Rhone River Delta

Evidence for tritium persistence as organically bound forms in river sediments since the past nuclear weapon tests

Short-term accumulation and elimination of carbon-14 in the common carp Cyprinus carpio under laboratory conditions

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Isotopic Signature (δ¹³C, ∆¹⁴C) of DIC in Sediment Pore Waters: An Example from the Rhone River Delta

Isotopic Signature (δ¹³C, ∆¹⁴C) of DIC in Sediment Pore Waters: An Example from the Rhone River Delta