Study of biological determinants of chlordecone transfer in the plant

L’objectif de cette thèse est de comprendre pourquoi certaines plantes sont en mesure d’absorber plus de polluants organiques que d’autres. Il s’agit d’appréhender les paramètres qui, à l’échelle de la plante, régissent l’absorption dans les racines puis le transfert vers les parties aériennes. La chlordécone a été retenue comme molécule d’étude, pour ses caractéristiques physico-chimiques propices à l’étude des transferts sol-plante (faible volatilité et relative hydrophobicité) mais également à cause des enjeux forts autour des sols contaminés dans les Antilles Françaises. Dans un premier temps, nous avons décidé de mettre en relation les processus liés à la croissance de la plante avec la capacité à accumuler la chlordécone lors d’essais en laboratoire. Des graminées modèles, comme le blé ou le miscanthus, nous ont permis d’identifier les traits biologiques impliqués dans l’absorption puis la translocation de la molécule dans les différentes parties de la plante. A l’issue de cette première phase, l’efficience de la transpiration, qui traduit également la capacité de la plante à utiliser l’eau, est apparue comme le principal déterminant de la concentration de la chlordécone dans la plante. Dans un second temps, nous avons cherché à évaluer le potentiel de contamination de la flore spontanée des parcelles contaminées de Guadeloupe, à travers un échantillonnage stratifié, c’est-à-dire orienté par des connaissances à priori ou par certains déterminants mis en évidence lors de la phase de laboratoire. Dans 70% des cas, l’analyse de cette flore spontanée nous a permis de mettre en évidence le risque significatif de dépassement des seuils réglementaires dans la viande animale nourrie avec la couverture végétale des parcelles contaminées. Des pratiques culturales, comme l’intensification du travail du sol, sont également apparues comme étant significativement corrélées à l’augmentation des quantités de chlordécone retrouvées dans la plante.The objective of this thesis is to understand the reasons why some plants are able to absorb more organic pollutants than others. The aim is to understand the parameters that, at the plant level, control the penetration into the roots and then the transfer to the aerial parts. Chlordecone was selected as a study molecule for its physico-chemical characteristics suitable for the study of soil-plant transfers (lowvolatility and relative hydrophobicity) but also because of the high stakes around contaminated soils in the FrenchWest Indies. Initially, we decided to relate the processes linked to plant growth to the capacity to accumulate chlordecone during laboratory tests. Model grasses, such as wheat ormiscanthus, allowed us to identify the biological traits involved in the absorption and then translocation of the molecule in the different parts of the plant. At the end of this first phase, the efficiency of transpiration, which also reflects the plant’s ability to use water, emerged as the main determinant of the concentration of chlordecone in the plant. In a second phase, we sought to assess the potential for contamination of the spontaneous flora of the contaminated fields in Guadeloupe, through stratified sampling, i.e. sampling oriented by a priori knowledge or by certain determinants highlighted during the laboratory phase. In 70% of the cases, the analysis of this spontaneous flora enabled us to highlight the significant risk of exceeding regulatory thresholds in animal meat fed with the plant cover of the contaminated plots. Cultivation practices, such as intensified tillage, also appeared to be significantly correlated with the increase in the amount of chlordecone found in the plant

Étude des déterminants biologiques de l'absorption de la chlordécone par la plante

The objective of this thesis is to understand the reasons why some plants are able to absorb more organic pollutants than others. The aim is to understand the parameters that, at the plant level, control the penetration into the roots and then the transfer to the aerial parts. Chlordecone was selected as a study molecule for its physico-chemical characteristics suitable for the study of soil-plant transfers (lowvolatility and relative hydrophobicity) but also because of the high stakes around contaminated soils in the FrenchWest Indies. Initially, we decided to relate the processes linked to plant growth to the capacity to accumulate chlordecone during laboratory tests. Model grasses, such as wheat ormiscanthus, allowed us to identify the biological traits involved in the absorption and then translocation of the molecule in the different parts of the plant. At the end of this first phase, the efficiency of transpiration, which also reflects the plant’s ability to use water, emerged as the main determinant of the concentration of chlordecone in the plant. In a second phase, we sought to assess the potential for contamination of the spontaneous flora of the contaminated fields in Guadeloupe, through stratified sampling, i.e. sampling oriented by a priori knowledge or by certain determinants highlighted during the laboratory phase. In 70% of the cases, the analysis of this spontaneous flora enabled us to highlight the significant risk of exceeding regulatory thresholds in animal meat fed with the plant cover of the contaminated plots. Cultivation practices, such as intensified tillage, also appeared to be significantly correlated with the increase in the amount of chlordecone found in the plant.L’objectif de cette thèse est de comprendre pourquoi certaines plantes sont en mesure d’absorber plus de polluants organiques que d’autres. Il s’agit d’appréhender les paramètres qui, à l’échelle de la plante, régissent l’absorption dans les racines puis le transfert vers les parties aériennes. La chlordécone a été retenue comme molécule d’étude, pour ses caractéristiques physico-chimiques propices à l’étude des transferts sol-plante (faible volatilité et relative hydrophobicité) mais également à cause des enjeux forts autour des sols contaminés dans les Antilles Françaises. Dans un premier temps, nous avons décidé de mettre en relation les processus liés à la croissance de la plante avec la capacité à accumuler la chlordécone lors d’essais en laboratoire. Des graminées modèles, comme le blé ou le miscanthus, nous ont permis d’identifier les traits biologiques impliqués dans l’absorption puis la translocation de la molécule dans les différentes parties de la plante. A l’issue de cette première phase, l’efficience de la transpiration, qui traduit également la capacité de la plante à utiliser l’eau, est apparue comme le principal déterminant de la concentration de la chlordécone dans la plante. Dans un second temps, nous avons cherché à évaluer le potentiel de contamination de la flore spontanée des parcelles contaminées de Guadeloupe, à travers un échantillonnage stratifié, c’est-à-dire orienté par des connaissances à priori ou par certains déterminants mis en évidence lors de la phase de laboratoire. Dans 70% des cas, l’analyse de cette flore spontanée nous a permis de mettre en évidence le risque significatif de dépassement des seuils réglementaires dans la viande animale nourrie avec la couverture végétale des parcelles contaminées. Des pratiques culturales, comme l’intensification du travail du sol, sont également apparues comme étant significativement corrélées à l’augmentation des quantités de chlordécone retrouvées dans la plante

Growth parameters influencing uptake of chlordecone by Miscanthus species

Because of its high persistence in soils, t1/2 = 30 years, chlordecone (CLD) was classified as a persistent organic pollutant (POP) by the Stockholm Convention in 2009.The distribution of CLD over time has been heterogeneous, ranging from banana plantations to watersheds, and contaminating all environmental compartments. The aims of this study were to (i) evaluate the potential of Miscanthus species to extract chlordecone from contaminated soils, (ii) identify the growth parameters that influence the transfer of CLD from the soil to aboveground plant parts. CLD uptake was investigated in two species of Miscanthus, C4 plants adapted to tropical climates. M. sinensis and M. × giganteus were transplanted in a soil spiked with [14C]CLD at environmental concentrations (1 mg kg− 1) under controlled conditions. Root-shoot transfer of CLD was compared in the two species after two growing periods (2 then 6 months) after transplantation. CLD was found in all plant organs, roots, rhizomes, stems, leaves, and even flower spikes. The highest concentration of CLD was in the roots, 5398 ± 1636 (M. × giganteus) and 14842 ± 3210 ng g− 1 DW (M. sinensis), whereas the concentration in shoots was lower, 152 ± 28 (M. × giganteus) and 266 ± 70 ng g− 1 DW (M. sinensis) in soil contaminated at 1 mg kg− 1. CLD translocation led to an acropetal gradient from the bottom to the top of the plants. CLD concentrations were also monitored over two complete growing periods (10 months) in M. sinensis grown in 8.05 mg kg− 1 CLD contaminated soils. Concentrations decreased in M. sinensis shoots after the second growth period due to the increase in organic matters in the vicinity of the roots. Results showed that, owing to their respective biomass production, the two species were equally efficient at phytoextraction of CLD

A Bayesian network approach for the identification of relationships between drivers of chlordecone bioaccumulation in plants

International audiencePlants were sampled from four different types of chlordecone-contaminated land in Guadeloupe (West Indies). The objective was to investigate the importance of biological and agri-environmental parameters in the ability of plants to bioaccumulate chlordecone. Among the plant traits studied, only the growth habit significantly affected chlordecone transfer, since prostrate plants concentrated more chlordecone than erect plants. In addition, intensification of land use has led to a significant increase in the amount of chlordecone absorbed by plants. The use of Bayesian networks uncovers some hypothesis and identifies paths for reflection and possible studies to identify and quantify relationships that explain our data

Database of metal concentrations measured in sediment cores (1965-2011) and bed and flood sediments (1987-2018) along the Rhône River

This database contains metal element concentrations from (1) river sediment cores and (2) bed and flood deposits acquired along the Rhône River by research teams (for 1: LEHNA-IPE) and monitoring programmes (for 2 : RMC Water Agency). This dataset focuses on six areas (geographical clusters: GC-1 to GC-6) located along the Rhône River corridor (ca. 512 km), after its confluence with the Arve River (near Geneva in Switzerland) to its delta near Arles (France). It presents the variations of metal concentrations for the following elements: Al, Fe, Cd, Cr, Cu, Ni, Pb, Zn during the period 1965-2018. It also includes the geo-accumulation values (Igeo) and enrichment factors (EFs) for Cd, Cr, Cu, Ni, Pb, and Zn. Extraction techniques (Aqua Regia or Total Extraction) and ancillary data such as total organic carbon content (TOC in % - pct), grainsize (fine fraction proportion: clay and silts < 63 µm), distance upstream of estuarine area (km UEA), sampling depth and date or expected age (for river sediment cores) are also reported

Metal pollution trajectories and mixture risk assessed by combining dated cores and subsurface sediments along a major European river (Rhône River, France)

International audienceIn European rivers, research and monitoring programmes have targeted metal pollution from bed and floodplain sediments since the mid-20th century by using various sampling and analysis protocols. We propose to characterise metal contamination trajectories since the 1960s based on the joint use of a large amount of data from dated cores and subsurface sediments along the Rhône River (ca. 512 km, Switzerland–France). For the reconstruction of spatio-temporal trends, enrichment factors (EF) and geo-accumulation (Igeo) approaches were compared. The latter index was preferred due to the recurrent lack of grain-size and lithogenic elements in the dataset. Local geochemical backgrounds were established near (1) the Subalps and (2) the Massif Central to consider the geological variability of the watershed. A high contamination (Igeo = 3–5) was found for Cd, Cu and Zn from upstream to downstream over the period 1980–2000. This pattern is consistent with long-term emissions from major cities and the nearby industrial areas of the Upper Rhône (Geneva, Arve Valley), and Middle Rhône (Lyon, Chemical Corridor, Gier Valley). Hotspots due to Cu and Zn leaching from vineyards, mining, and highway runoff were also identified, while Pb was especially driven by industrial sources. The recovery time of pollution in sediment varied according to the metals and was shorter upstream of Lyon (15–20 years) than downstream (30–40 years). More widely, it was faster on the Rhône than along other European rivers (e.g. Seine and Rhine). Finally, the ecotoxicological mixture risk of metal with Persistent Organic Pollutants (POPs) for sediment-dwelling organisms showed a medium “cocktail risk” dominated by metals upstream of Lyon, although it is enhanced due to POPs downstream, and southward to the delta and the Mediterranean Sea. Overall, this study demonstrates the heterogeneity of the contamination trends along large fluvial corridors such as the Rhône River

Evolution de la pollution métallique et du risque écotoxicologique le long du Rhône depuis 1960 : approche combinée à partir du suivi particulaire et d'archives sédimentaires datées

International audienc

Evolution de la pollution métallique et du risque écotoxicologique le long du Rhône depuis 1960 : approche combinée à partir du suivi particulaire et d'archives sédimentaires datées

International audienc

Evolution de la pollution métallique et du risque écotoxicologique le long du Rhône depuis 1960 : approche combinée à partir du suivi particulaire et d'archives sédimentaires datées

International audienc

Evolution de la pollution métallique et du risque écotoxicologique le long du Rhône depuis 1960 : approche combinée à partir du suivi particulaire et d'archives sédimentaires datées

International audienc