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8. Sediment source fingerprinting: benchmarking recent outputs, remaining challenges and emerging themes

Author

Collins, Adrian L., Blackwell, Martin, Boeckx, Pascal, Chivers, Charlotte-Anne, Emelko, Monica, Evrard, Olivier, Foster, Ian, Gellis, Allen, Gholami, Hamid, Granger, Steve, Harris, Paul, Horowitz, Arthur J., Laceby, J. Patrick, Martinez-Carreras, Nuria, Minella, Jean, Mol, Lisa, Nosrati, Kazem, Pulley, Simon, Silins, Uldis, da Silva, Yuri Jacques, Stone, Micheal, Tiecher, Tales, Upadhayay, Hari Ram, and Zhang, Yusheng

Published
2020
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16. Sensitivity of source sediment fingerprinting to tracer selection methods.

Author

Chalaux-Clergue, Thomas, Bizeul, Rémi, Batista, Pedro V. G., Martínez-Carreras, Núria, Laceby, J. Patrick, and Evrard, Olivier

Subjects
FISHER discriminant analysis, SOIL erosion, SEDIMENTS, SEDIMENT sampling, WATER conservation, SOIL conservation
Abstract

In a context of accelerated soil erosion and sediment supply to water bodies, sediment fingerprinting techniques have received an increasing interest in the last 2 decades. The selection of tracers is a particularly critical step for the subsequent accurate prediction of sediment source contributions. To select tracers, the most conventional approach is the three-step method, although, more recently, the consensus method has also been proposed as an alternative. The outputs of these two approaches were compared in terms of identification of conservative properties, tracer selection, modelled contributions and performance on a single dataset. As for the three-step method, several range test criteria were compared, along with the impact of the discriminant function analysis (DFA). The dataset was composed of tracer properties analysed in soil (three potential sources; n = 56) and sediment core samples (n = 32). Soil and sediment samples were sieved to 63 µ m and analysed for organic matter, elemental geochemistry and diffuse visible spectrometry. Virtual mixtures (n = 138) with known source proportions were generated to assess model accuracy of each tracer selection method. The Bayesian un-mixing model MixSIAR was then used to predict source contributions on both virtual mixtures and actual sediments. The different methods tested in the current research can be distributed into three groups according to their sensitivity to the conservative behaviour of properties, which was found to be associated with different predicted source contribution tendencies along the sediment core. The methods selecting the largest number of tracers were associated with a dominant and constant contribution of forests to sediment. In contrast, the methods selecting the lowest number of tracers were associated with a dominant and constant contribution of cropland to sediment. Furthermore, the intermediate selection of tracers led to more balanced contributions of both cropland and forest to sediments. The prediction of the virtual mixtures allowed us to compute several evaluation metrics, which are generally used to support the evaluation of model accuracy for each tracer selection method. However, strong differences or the absence of correspondence were observed between the range of predicted contributions obtained for virtual mixtures and those values obtained for actual sediments. These divergences highlight the fact that evaluation metrics obtained for virtual mixtures may not be directly transferable to models run for actual samples and must be interpreted with caution to avoid over-interpretation or misinterpretation. These divergences may likely be attributed to the occurrence of a not (fully) conservative behaviour of potential tracer properties during erosion, transport and deposition processes, which could not be fully reproduced when generating the virtual mixtures with currently available methods. Future research should develop novel metrics to quantify the conservative behaviour of tracer properties during erosion and transport processes. Furthermore, new methods should be designed to generate virtual mixtures closer to reality and to better evaluate model accuracy. These improvements would contribute to the development of more reliable sediment fingerprinting techniques, which are needed to better support the implementation of effective soil and water conservation measures at the catchment scale. [ABSTRACT FROM AUTHOR]

Published
2024
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20. Sensitivity of source sediment fingerprinting modelling to tracer selection methods.

Author

Chalaux-Clergue, Thomas, Bizeul, Rémi, Batista, Pedro V. G., Martinez-Carreras, Nuria, Laceby, J. Patrick, and Evrard, Olivier

Subjects
FISHER discriminant analysis, ORGANIC geochemistry, SOIL erosion, SEDIMENTS, WATERSHED management, SEDIMENT sampling, DRILL core analysis
Abstract

In a context of accelerated soil erosion and sediment supply to water bodies, sediment fingerprinting techniques have received an increasing interest in the last two decades. The selection of tracers is a particularly critical step for the subsequent accurate prediction of sediment source contributions. To select tracers, the most conventional approach is the so-called three-step method, although, more recently, the consensus method has also been proposed as an alternative. The outputs of these two approaches were compared in terms of identification of conservative properties, tracer selection, contribution modelling tendency and performance on a single dataset. As for the tree-step method, several range test criteria were compared, along with the impact of the discriminant function analysis (DFA). The dataset was composed of tracing properties analysed in soil (through the consideration of three potential sources; n = 56) and sediment core samples (n = 32). Soil and sediment samples were sieved to 63 µm and analysed for organic matter, elemental geochemistry and diffuse visible spectrometry. Virtual mixtures (n = 138) with known source proportions were generated in order to assess model accuracy of each tracer selection method. The Bayesian un-mixing model MixSIAR was used to predict source contributions on virtual mixtures and actual sediments. The different methods tested in the current research can be distributed into three groups according to their more or less restrictive identification of conservative properties, which were found to be associated with different sediment source contribution tendencies. The less restrictive selections of tracers were associated with a dominant and constant contribution of forests to sediment, whereas the most restrictive selections were associated with dominant and constant contributions of cropland to sediment. In contrast, intermediately restrictive selection of tracers led to more balanced contributions of both cropland and forest to sediment production. Virtual mixtures allowed to compute several evaluation metrics, which supported a better understanding of each tracer selection modelling accuracy. However, strong divergences were observed between the predicted contributions of virtual mixtures and the predicted sediment source contributions. These divergences may likely be attributed to the occurrence of a non-(fully) conservative behaviour of potential tracing properties during erosion, transport and deposition processes, which could not be reproduced when generated the virtual mixtures. Among the compared tracer selection methods, the three-step method using the mean ± SD and hinge range test criteria provided the most reliable tracer selection methods. In the future, it would be fundamental to generate more reliable metrics to assess conservativeness, to support more reliable modelling and more realistic virtual mixture generation to correctly evaluate modelling accuracy. These improvements may contribute to trustworthy sediment fingerprinting techniques for supporting efficient soil conservation and watershed management. [ABSTRACT FROM AUTHOR]

Published
2023
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25. Radionuclide contamination in flood sediment deposits in the coastal rivers draining the main radioactive pollution plume of Fukushima Prefecture, Japan (2011–2020)

Author

Evrard, Olivier, primary, Chartin, Caroline, additional, Laceby, J. Patrick, additional, Onda, Yuichi, additional, Wakiyama, Yoshifumi, additional, Nakao, Atsushi, additional, Cerdan, Olivier, additional, Lepage, Hugo, additional, Jaegler, Hugo, additional, Vandromme, Rosalie, additional, Lefèvre, Irène, additional, and Bonté, Philippe, additional

Published
2021
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26. What were the main sources of sediment and associated radiocesium transported during the heavy 2019 typhoons in rivers draining the main Fukushima radioactive plume, Japan ?

Author

Evrard, Olivier, primary, Durand, Roxanne, additional, Nakao, Atsushi, additional, Laceby, J. Patrick, additional, Lefèvre, Irène, additional, Wakiyama, Yoshifumi, additional, Hayashi, Seiji, additional, Asanuma-Brice, Cécile, additional, and Cerdan, Olivier, additional

Published
2021
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36. Combining colour and magnetic properties with geochemical tracers to improve discrimination of sediment sources in the Conceição River Catchment, Southern Brazil

Author

Ramon, Rafael, Tiecher, Tales, Evrard, O., Laceby, J. Patrick, Caner, Laurent, Minella, Jean P.G., Barros, Cláudia, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Géochimie Des Impacts (GEDI), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Universidade Federal do Rio Grande do Sul [Porto Alegre] (UFRGS), Alberta Environment and Parks (AEP), Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Poitiers-Institut de Chimie du CNRS (INC), Universidade Federal de Santa Maria = Federal University of Santa Maria [Santa Maria, RS, Brazil] (UFSM), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Poitiers-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Universidade Federal de Santa Maria (UFSM)

Subjects
[SDE.MCG]Environmental Sciences/Global Changes, [SDE]Environmental Sciences, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, [SDV.SA.SDS]Life Sciences [q-bio]/Agricultural sciences/Soil study, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment
Abstract

International audience; An important step in the sediment source fingerprinting approach is the selection of the appropriate tracing parameters to maximise source discrimination. In order to reduce uncertainties and increase discrimination between sources it may be necessary to use multiple tracing parameters. Accordingly, this study investigates the discrimination and apportionment of sediment sources in a rural agricultural catchment obtained by combining colour, magnetic, and geochemical fingerprinting approaches. The Conceição River catchment (804 km 2) has predominantly deep and highly weathered Ferralsols with land-use consisting of croplands (73%), pastures (18%), forests (8%) and other uses (1%). A total of 189 samples were taken from the main sediment sources, including: Crop-lands (CR, n=78), pastures (P, n=24), unpaved roads (UR, n=38), gullies (G, n=15) and stream bank (SB, n=34). Sediment samples were taken from the surface bed (n=10) of the river and with time integrated samplers (n=4). Twenty-two geochemical tracers, 6 magnetic properties and 24 colour parameters were analyzed. Tracers were selected following a three step procedure, including: (i) a conservative range test (95% confident interval), (ii) a Kruskal-Wallis H test, and (iii) discriminant function analysis (DFA). The DFA was performed using four different sets of variables: (i) geochemical variables only (G); (ii) geochemical+magnetic+colour (GMC); (iii) geochemi-cal+colour (GC); (iv) geochemical+magnetic (GM). The selected tracers were introduced into a modified version of the classical Solver-based mixing model that in order to determine the relative contribution of different sources to in-stream sediment through simultaneously minimizing mixing model difference. The G and GC DFAs both resulted 69% of samples correct classified (SCC) as no colour parameters were selected by the DFA. The GMC and GM approaches improved the discrimination, both resulting in 76% of SCC. For the G and GC approaches, the average source contribution for the 12 sediment samples were P 47%, SB 29%, CR 19%, UR 5% and G 0%. For the GMC and GM approaches, the contribution of each source was P 41%, SB 37%, CR 14%, UR 8% and G 0%. These results are counterintuitive to field observations where cropland is anticipated to contribute more sediment than pastures. Future research should use artificial mixtures to validate these results. Both magnetic and colour parameters hold potential to improve discrimination between sources, particularly magnetic parameters in catchments with high weathered soils.

Published
2019

37. Comparing conventional and alternative sediment tracing methods to quantify the sources of sediment transiting rivers of South Pacific Islands

Author

Sellier, Virginie, Evrard, O., Navratil, O., Laceby, J. Patrick, Legout, Cédric, Lefèvre, Irène, Allenbach, Michel, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Géochimie Des Impacts (GEDI), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Environnement, Ville, Société (EVS), École normale supérieure de Lyon (ENS de Lyon)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université Lumière - Lyon 2 (UL2)-Université Jean Moulin - Lyon 3 (UJML), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-École Nationale des Travaux Publics de l'État (ENTPE)-École nationale supérieure d'architecture de Lyon (ENSAL)-Centre National de la Recherche Scientifique (CNRS), Environmental Monitoring and Science Division of Alberta (EMSD), Alberta Government, Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université de la Nouvelle-Calédonie (UNC), Institut de sciences exactes et appliquées (ISEA), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Environnement Ville Société (EVS), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-École nationale supérieure d'architecture de Lyon (ENSAL)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-École Nationale des Travaux Publics de l'État (ENTPE)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Jean Moulin - Lyon 3 (UJML), Université de Lyon-Université Lumière - Lyon 2 (UL2)-École normale supérieure - Lyon (ENS Lyon), and Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Recherche pour le Développement (IRD)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
[SDE.MCG]Environmental Sciences/Global Changes, [SDE]Environmental Sciences, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, [SDV.SA.SDS]Life Sciences [q-bio]/Agricultural sciences/Soil study, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, [SDU.STU.AG]Sciences of the Universe [physics]/Earth Sciences/Applied geology
Abstract

International audience; Soil erosion and subsequent sediment transfer in rivers may be intense in tropical regions exposed to heavy rainfall. In New Caledonia, a French island located in the southwest of the Pacific Ocean, these problems are exacerbated by nickel open-mining activities. After more than 150 years of exploitation, the excessive sediment input from mining areas has strongly modified the morphology of rivers (hyper-sedimentation) and impacted the island's ecosystems designated a UNESCO World Heritage Site. Despite the severity of these problems, the contribution of mining activities to sediment transiting rivers of this region has not yet been quantified, and this estimation is required to guide the implementation of efficient management measures to mitigate the fine sediment supply to New Caledonian rivers and lagoons. To this end, a pilot sediment tracing study has been conducted in one of the first sites exploited for nickel mining, the 400-km$^2$ Thio River catchment. Sediment deposited during the February 25, 2015 flood was collected according to a 'tributary tracing ap-proach' on the main stem of the Thio River and its main tributaries classified in two types (rivers draining mining sites vs. those devoid of mining activity and where sediment is supplied by landslides, cattle trampling and erosion following forest fires). As nickel mining has mainly developed on peridotite massifs enriched in Mn and Fe oxides, mining sources generate orange or red-coloured sediments, whereas the areas devoid of mining activities rather supply grey material to the rivers. Accordingly, the applicability of alternative sediment tracing method such as spectrocolorimetry in the visible (VIS) range of the spectrum was investigated. The results of this method were compared to those obtained with conventional methods based on fallout radionuclides. Thorium (Th) contents estimated based on the measurement of Th-228 by gamma spectrometry provided a better discrimination between both sources than Cs-137 and unsupported Pb-210. This is likely explained by the low levels of fallout radionuclides (mainly Cs-137) in this region of the world, and by the natural Th enrichment in the volcano-sedimentary formation rocks, devoid of mining activities. On the contrary, the peridotite massif rocks concentrating the nickel mining activities were depleted in Th. Accordingly, the application of a distribution modelling approach based on Th contents showed that tributaries draining mining sites were the main source of sediment supplied to the Thio River (mean 59 %), although the contributions of no-mining sources was far from negligible. Similar results were found with the spectrocolorimetry parameters. After validation, these two methods will be applied to a sediment core collected in the Thio river deltaic plain to characterize potential changes in sediment source contributions over time. Potential applications in other catchments draining mines in New Caledonia will also be explored.

Published
2018

38. Tracing the sources and dynamics of contaminated sediment in coastal rivers draining the main Fukushima radioactive fallout plume using gamma-emitting radionuclides and carbon/nitrogen stable isotopes (2011-2017)

Author

Evrard, O., Laceby, J. Patrick, Onda, Yuichi, Hayashi, Seiji, Tsuji, Hideki, Huon, Sylvain, Lefèvre, Irène, Jaegler, Hugo, Landemaine, Valentin, Vandromme, Rosalie, Cerdan, Olivier, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Géochimie Des Impacts (GEDI), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Alberta Environment and Parks (AEP), Université de Tsukuba = University of Tsukuba, National Institute for Environmental Science [Fukushima], Institut d'écologie et des sciences de l'environnement de Paris (iEES), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), ANR-11-RSNR-0002,AMORAD,AMORAD1(2011), ANR-11-JAPN-0001,TOFU,Traçage des conséquences environnementales du tsunami provoqué par le séisme de TOhoku et de l'accident de FUkushima(2011), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Evrard, Olivier, AMORAD1 - - AMORAD2011 - ANR-11-RSNR-0002 - RSNR - VALID, and Great Tohoku Earthquake - Traçage des conséquences environnementales du tsunami provoqué par le séisme de TOhoku et de l'accident de FUkushima - - TOFU2011 - ANR-11-JAPN-0001 - JAPON - VALID

Subjects
[SDE] Environmental Sciences, [SDE.MCG] Environmental Sciences/Global Changes, [SDU.STU.GM] Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDE.MCG]Environmental Sciences/Global Changes, [SDE]Environmental Sciences, [SDU.STU.HY] Sciences of the Universe [physics]/Earth Sciences/Hydrology, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, [SDV.SA.SDS]Life Sciences [q-bio]/Agricultural sciences/Soil study, [SDV.SA.SDS] Life Sciences [q-bio]/Agricultural sciences/Soil study, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, [SDU.ENVI] Sciences of the Universe [physics]/Continental interfaces, environment
Abstract

International audience; Fieldwork was conducted every 6 months between 2011 and 2017 to monitor the dispersion of sediment contaminated with radionuclides in rivers draining the main Fukushima radioactive pollution plume (~500 km²). Fine sediment was systematically collected at the same locations (n=47) and analysed for gamma-emitting radionuclides (including 137Cs and 110mAg). A selection of samples was also analysed for carbon/nitrogen concentrations and isotopes. Organic matter analyses showed that paddy fields provided the main source of contaminated sediment to the rivers shortly after the accident. The spatial variations of the 110mAg:137Cs activity ratio in soils were used to demonstrate the very rapid export of sediment to the Pacific Ocean. However, this tool could only be used during the first campaigns, because of the quick decay of 110mAg. Overall, radiocesium concentrations measured in sediment deposits decreased by ~90% between 2011 and 2017. This may be explained by remediation works, by a massive export of material during typhoons and by the occurrence of landslides or channel bank erosion that supply material sheltered from the Fukushima fallout to the river network. Consequently, 6 years after the accident, most of the residual radioactive contamination is found in forests and in dam reservoirs. The analysis of sediment cores collected in a reservoir confirmed the significant storage of contaminated material in these lakes and that paddy fields provided their main source. Ongoing research focuses on the development of a soil erosion model and on the quantification of the impact of remediation works.

Published
2018

40. Reconstruction of uranium and plutonium isotopic signatures in sediment accumulated in the Mano Dam reservoir, Japan, before and after the Fukushima nuclear accident

Author

Jaegler, Hugo, primary, Pointurier, Fabien, additional, Diez-Fernández, Silvia, additional, Gourgiotis, Alkiviadis, additional, Isnard, Hélène, additional, Hayashi, Seiji, additional, Tsuji, Hideki, additional, Onda, Yuichi, additional, Hubert, Amélie, additional, Laceby, J. Patrick, additional, and Evrard, Olivier, additional

Published
2019
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45. Quantifying the transfer times of suspended sediment during floods with $^7$Be and $^{210}$Pb$_{xs}$ measurements in a drained lowland catchment of central France

Author

Evrard, O., Le Gall, Marion, Foucher, Anthony, Laceby, J. Patrick, Salvador-Blanes, Sébastien, Manière, Louis, Lefèvre, Irène, Cerdan, Olivier, Vandromme, Rosalie, Ayrault, Sophie, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Géochimie Des Impacts (GEDI), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), GéoHydrosystèmes COntinentaux (GéHCO EA6293), Université de Tours, Alberta Environment and Parks (AEP), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Tours (UT), and Evrard, Olivier

Subjects
[SDE] Environmental Sciences, [SDE.MCG] Environmental Sciences/Global Changes, [SDU.STU.GM] Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDE.MCG]Environmental Sciences/Global Changes, [SDE]Environmental Sciences, [SDU.STU.HY] Sciences of the Universe [physics]/Earth Sciences/Hydrology, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, [SDV.SA.SDS]Life Sciences [q-bio]/Agricultural sciences/Soil study, [SDV.SA.SDS] Life Sciences [q-bio]/Agricultural sciences/Soil study, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, [SDU.ENVI] Sciences of the Universe [physics]/Continental interfaces, environment
Abstract

International audience; Intensification of agriculture after WWII increased soil erosion and sediment supply to rivers in Northwestern Europe. The Louroux Pond catchment (25 km 2), located in the Loire River basin (central France), is representative of these intensively cultivated environments and subject to severe soil erosion and river siltation. This catchment was equipped with an extensive network of tile drains that were installed after 1945 to produce crops in this former wetland. In order to decrease the deleterious impacts induced by accelerated soil erosion in this region, there is a need to better understand sediment dynamics during flood events. To this end, natural fallout radionuclides were analysed in both sediment sources and suspended matter transiting the river network to quantify the respective proportions of recently eroded vs. resuspended material. Accordingly, 7Be and 210Pbxs concentrations were measured in overland flow and suspended sediment collected in the pond tributaries during a succession of floods that occurred during winter in 2013-2014 and in 2016. The results show that the mean fraction of recently eroded material transiting these rivers increased from 40 ± 20% to 80 ± 20 in 2013-2014, and from 65 ± 20% to 80 ± 20% in 2016. These results demonstrate an initial flush of sediment previously accumulated in the river channel during the first winter floods. Then, the fraction of sediment recently eroded from the hillslopes significantly increased during subsequent events. This research illustrates the added value of combining continuous river monitoring and fallout radionuclide analyses to improve our knowledge of sediment dynamics and to protect soil and water resources in these environments.

Published
2017

46. Investigating the temporal dynamics of suspended sediment during flood events with 7Be and 210Pbxs measurements in a drained lowland catchment

Author

Le Gall, Marion, Evrard, O., Foucher, Anthony, Laceby, J. Patrick, Salvador-Blanes, Sébastien, Manière, Louis, Lefevre, Irène, Cerdan, Olivier, Ayrault, Sophie, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Géochimie Des Impacts (GEDI), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), GéoHydrosystèmes COntinentaux (GéHCO EA6293), Université de Tours (UT), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), This work received financial support from the Loire-Brittany Water Agency (in the framework of the Tracksed and Drastic research projects)., AELB, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), and Université de Tours

Subjects
GéoHydrosystèmes Continentaux (GéHCO), [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, [SDV.SA.SDS]Life Sciences [q-bio]/Agricultural sciences/Soil study, Gif-sur-Yvette (France) 2 EA 6293, Panoply, Article, Tours (France) 3 Département Risques et Prévention, Faculté des Sciences et Techniques, Bureau de Recherches Géologiques et Minières, [SDE]Environmental Sciences, du CNRS, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Université F Rabelais de Tours, Orléans (France)
Abstract

International audience; Soil erosion is recognized as one of the main processes of land degradation in agricultural areas. High suspended sediment loads, often generated from eroding agricultural landscapes, are known to degrade downstream environments. Accordingly, there is a need to understand soil erosion dynamics during flood events. Suspended sediment was therefore sampled in the river network and at tile drain outlets during five flood events in a lowland drained catchment in France. Source and sediment fallout radionuclide concentrations (Be-7, Pb-210(xs)) were measured to quantify both the fraction of recently eroded particles transported during flood events and their residence time. Results indicate that the mean fraction of recently eroded sediment, estimated for the entire Louroux catchment, increased from 45 +/- 20% to 80 +/- 20% between December 2013 and February 2014, and from 65 +/- 20% to 80 +/- 20% in January 2016. These results demonstrate an initial flush of sediment previously accumulated in the river channel before the increasing supply of sediment recently eroded from the hillslopes during subsequent events. This research highlights the utility of coupling continuous river monitoring and fallout radionuclide measurements to increase our understanding of sediment dynamics and improve the management of soil and water resources in agricultural catchments.

Published
2017

47. The impact of typhoons on sediment connectivity: lessons learnt from contaminated coastal catchments of the Fukushima Prefecture (Japan)

Author

Chartin, Caroline, Evrard, O., Laceby, J. Patrick, Onda, Yuichi, Ottlé, Catherine, Lefevre, Irène, Cerdan, Olivier, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Géochimie Des Impacts (GEDI), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Tsukuba = University of Tsukuba, Modélisation des Surfaces et Interfaces Continentales (MOSAIC), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), ANR-11-RSNR-0002,AMORAD,AMORAD1(2011), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
flooding, soil erosion, storm events, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, radiocesium 16, sediment contamination, [SDU.STU.AG]Sciences of the Universe [physics]/Earth Sciences/Applied geology
Abstract

International audience; Sediment connectivity characterizes the physical transfer of sediment through different geomorphic compartments in catchments due to sediment detachment, transport and deposition. Quantifying and modelling sediment connectivity is therefore a key prerequisite to improving our understanding of the dispersion of particle-borne contaminants, especially in catchments exposed to highly erosive climates. The objective of this study is to provide novel insights into typhoon impacts on sediment connectivity from hillslopes to rivers. The dispersion of particle-bound caesium-137 (Cs-137) was investigated in two coastal catchments draining the main contamination plume from the Fukushima Daiichi Nuclear Power Plant accident. Five sampling campaigns were carried out from November 2011 to November 2015, after each typhoon season. The spatial and temporal evolution of Cs-137 contamination was investigated through the calculation of Cs-137 enrichment ratios in sediment relative to nearby soils. Rainfall erosivity (EI30) associated with the main typhoons that occurred prior to each sampling campaign were computed, mapped, and finally used to improve a topographic-based index of connectivity. From 2011 to 2015, mean contamination levels in Mano and Niida catchments decreased from 11.9kBqkg(-1) to 3.3kBqkg(-1) and from 34.1kBqkg(-1) to 8.0kBqkg(-1), respectively. Regional mean EI30 ranged from 262MJmmha(-1)h(-1) for typhoon Jelawat (in 2012) to 1695MJmmha(-1)h(-1) for typhoon Roke (in 2011). Typhoons Roke (2011) and Etau (2015) showed the highest connectivity from contaminated sources to the rivers, and induced a significant export of sediment to the ocean. In 2013 a slight increase in Cs-137 levels in river sediments occurred, likely resulting from initial decontamination works and the occurrence of two consecutive typhoons. Importantly, this research provides new insights into the connectivity of the main sources of sediments contaminated with radiocaesium in Fukushima Prefecture and their temporal evolution, which will help with ongoing decontamination efforts.

Published
2017

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