The influence of hydrogeology and carbon sources on speleothem δ13C based on long-term monitoring in Furong Cave, southwest China
The stable carbon isotopic composition of speleothems is an important but incompletely understood parameter in paleoclimatological and paleoenvironmental reconstruction, recording changes in vegetation and hydrology. This study systematically assesses the influences of karst hydrology, cave environment, and carbon sources on the δ13C values of farmed calcite in Furong Cave, located in Chongqing, southwest China. Six drip sites (MP1-MP5) were monitored between 2009 and 2019, and Δ14C data (Δ14C is the difference in the 14C/12C ratio between a sample and a standard, expressed in permille, ‰) of soil organic matter, drip water and farmed calcite (calcite precipitated on a glass substrate) were obtained. A linear relationship was found between the seasonal variability of pCO2 in cave air and δ13CCc of the farmed calcite in “Great Hall” characterised by a relatively stable microenvironment. The growth rate and δ13CCc values of the farmed calcite was not be affected by the drip rate unless the drip rate decreased to <1 drip/min for a long time, leading to a decrease in growth rate and higher δ13CCc values because of longer CO2 degassing. MP2 and MP9 show faster drip rates, higher δ13CDIC and lower Δ14C than MP1 and MP3, which suggests that the “old carbon” in MP9 is derived from the host rock. MP4 and MP5 are characterised by slower drip rates and lower δ13CDIC and δ13CCc, and the Δ14C values of the farmed calcite are lower than those of MP9. The slow drip rate indicates that less infiltration water reaches MP4 and MP5, and soil CO2 derived from the decomposition of “old” organic matter enters the fractures that lead to these drip sites. The fast drip rate of MP9 suggests that the fissures feeding this drip site are mostly water-saturated, limiting the exchange between soil CO2 and CO32− and allowing more “old carbon” from the bedrock to dissolve leading to higher δ13CDIC. This study emphasizes that in addition to changes in the cave environment, the source(s) of the carbon may be a more important factor controlling the δ13C values of drip water (and speleothem) than drip rate.
(Chemical Geology. vol. 662, n° 0009-2541, pp. 122210, 07/06/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Satellite-derived sandy shoreline trends and interannual variability along the Atlantic coast of Europe
AbstractMonitoring sandy shoreline evolution from years to decades is critical to understand the past and predict the future of our coasts. Optical satellite imagery can now infer such datasets globally, but sometimes with large uncertainties, poor spatial resolution, and thus debatable outcomes. Here we validate and analyse satellite-derived-shoreline positions (1984–2021) along the Atlantic coast of Europe using a moving-averaged approach based on coastline characteristics, indicating conservative uncertainties of long-term trends around 0.4 m/year and a potential bias towards accretion. We show that west-facing open coasts are more prone to long-term erosion, whereas relatively closed coasts favor accretion, although most of computed trends fall within the range of uncertainty. Interannual shoreline variability is influenced by regionally dominant atmospheric climate indices. Quasi-straight open coastlines typically show the strongest and more alongshore-uniform links, while embayed coastlines, especially those not exposed to the dominant wave climate, show weaker and more variable correlation with the indices. Our results provide a spatial continuum between previous local-scale studies, while emphasizing the necessity to further reduce satellite-derived shoreline trend uncertainties. They also call for applications based on a relevant averaging approach and the inclusion of coastal setting parameters to unravel the forcing-response spectrum of sandy shorelines globally.
(Scientific Reports. vol. 14, n° 2045-2322, 06/06/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Sunscreen use during recreational activities on a French Atlantic beach: release of UV filters at sea and influence of air temperature
Organic UV filters are emerging contaminants in personal care products such as sunscreens. The toxicity of numerous of these UV filter compounds has been demonstrated in several marine taxa. However, whilst the biological impact has already been largely demonstrated, the anthropogenic drivers leading to UV filter contamination still need to be identified. In this work, a survey was conducted on a site of the French Atlantic Coast (i) to describe beachgoers’ behaviours (sunscreen use and beach frequentation), (ii) provide an estimation of the UV filters released at sea and (iii) highlight the effect of air temperature on these behaviours and on the release of UV filters. In parallel with these estimations of the UV filters released at sea, in situ chemical measurements were performed. By comparing the results of both approaches, this interdisciplinary work provides an insight of how the observations of beachgoers’ behaviour modulations and attendance level fluctuations could be used to prevent UV filter contaminations and ultimately manage the ecotoxicological risk.
(Environmental Science and Pollution Research. vol. 31, n° 0944-1344, pp. 41046-41058, 06/06/2024)
LIENSs, INSU - CNRS, ULR, CNRS, CNRS, AMU, CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LCE, AMU, INC-CNRS, CNRS
Carottes sédimentaires : Un enregistrement de la qualité chimique du milieu ?
(05/06/2024)
METIS, EPHE, PSL, INSU - CNRS, SU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GERS-LEE, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
Enhancing microplastic sampling efficiency with in-situ filtration instrumentation: a novel protocol for turbid estuarine waters
Conducting in situ observations to measure microplastic concentrations in the abiotic compartment is essential for enhancing our understanding of plastic pollution along the land-sea continuum. While numerous protocols have been devised to investigate microplastic (MP) pollution in oceans and rivers, mainly in surface waters and sediments, many may not be suitable for assessing MP contamination in coastal transition waters such as estuaries, where MPs can exhibit high mobility within the water column. Assessing MPs in tidal systems requires several samplings throughout the tidal cycle, which is challenging due to short sampling periods and the presence of suspended sediments. Sampling MPs in these environments is therefore challenging using nets (risk of clogging), bottles (limited water quantity), or pumps (potential sample contamination). To address this challenge, a new instrument, the Ascension profiler, has been introduced for in-situ water pumping and filtering, avoiding sample contamination. This device offers the flexibility of using filters with different mesh sizes and enables the filtration of large water volumes to ensure representative sampling even at high water depths. In our study, we propose an innovative in-situ sampling strategy protocol that accounts for the typical time scales of estuarine variability as well as the longitudinal salinity gradient using Ascension. We present all the preliminary tests made with the instrument to set up a protocol (water volume, pumping duration, filter size) adapted to the conditions of the macrotidal hyperturbid Gironde estuary. Furthermore, this new sampling method and protocol hold promise for application in other oceanic, coastal, and freshwater environments.
(03/06/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Effects of polystyrene nano- and microplastics and of microplastics with sorbed polycyclic aromatic hydrocarbons in adult zebrafish
(Science of the Total Environment. vol. 927, n° 0048-9697, pp. 172380, 01/06/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Life Cycle Assessment of an Aquifer Thermal Energy Storage System: Influence of design parameters and comparison with conventional systems
(Geothermics. vol. 120, n° 0375-6505, pp. 102996, 01/06/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ISM, UB, INC-CNRS, CNRS, UB, ENSAP Bordeaux, UBM, CNRS
PFAS degradation by anodic electrooxidation: Influence of BDD electrode configuration and presence of dissolved organic matter
Per- and poly-fluoroalkyl substances (PFAS) pose substantial environmental and human health risks. Electrochemical oxidation technology is a promising large-scale solution for PFAS degradation due to its simplicity and minimal waste generation. This study investigated the electrochemical performance of boron-doped diamond (BDD) electrodes in degrading PFAS using a recirculation cell with plate and mesh electrodes. The study found that increasing the current density from 6.4 mA/cm2 to 40 mA/cm2 resulted in a transition of the reaction rate from pseudo-first-order toward zero-order kinetics. The stepwise degradation mechanism and the formation of intermediate products were also explored. Carbon and fluorine molar balance analysis revealed that the missing intermediates do not contain fluoride atoms in their molecular formula. The shape and surface of the electrodes had a significant impact on their performance, in particular, improving the degradation of the most recalcitrant perfluorobutanoic acid. The influence of different fractions of dissolved organic matter (DOM) on perfluorohexanoic acid degradation shows that overall, DOM does not significantly inhibit its degradation. Some inhibition was observed in the presence of DOM enriched in carbohydrates, organics that are known to exert strong interaction properties with organic and inorganic surfaces. The synergistic effect of direct anodic oxidation and indirect degradation by reactive radical species enables the decomposition of both DOM and PFAS. Finally, high removal percentages of short (up to 96 %) and long-chain PFAS (up to 99 %) were obtained using BDD electrooxidation cells combining plate and mesh electrodes when treating reverse osmosis concentrate containing PFAS.
(Chemical Engineering Journal. vol. 489, n° 1385-8947, pp. 151355, 01/06/2024)
E-BICOM, IC2MP [Poitiers], UP, INC-CNRS, CNRS, IC2MP [Poitiers], UP, INC-CNRS, CNRS, LPTC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, MediaCat, IC2MP [Poitiers], UP, INC-CNRS, CNRS, FRH2 [CNRS], CNRS
Évaluation de l'impact de la pollution chimique dans les habitats utilisés par les jeunes stades de vie de poissons migrateurs en danger (SW, France)
(. vol. 931, 01/06/2024)
UR EABX, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, RiverLy, INRAE
Dieldrin accumulation, distribution in plant parts and phytoextraction potential for several plant species and Cucurbita pepo varieties
Dieldrin, an organochlorine pesticide (OCP) widely used for crop protection in the second half of the 20th century till the 70's, is worldwide still present in arable soils. It can be transferred to crops, notably cucurbits, depending on plant species and cultivars. Finding strategies to decrease OCP bioavailability in soil is therefore a main concern. Phytomanagement strategies could provide (i) ready-to-use short term solution for maintaining the production of edible plant parts with dieldrin concentrations below the Maximum Residue Limits (MRL) and (ii) long-term solution for dieldrin phytoextraction reducing progressively its bioavailability in the soil. This field study aimed at determining dieldrin accumulation capacities and allocation pattern in 17 non-Cucurbitaceae species and 10 Cucurbita pepo varieties, and assessing the dieldrin phytoextraction potential of these plant species when grown to maturity in a historically dieldrin-contaminated soil. Out of the non-Cucurbitaceae species, vetiver was the only one able to accumulate significant amounts of dieldrin, which mainly remained in its roots. All C. pepo varieties were able to uptake and translocate high dieldrin amounts into the shoots, leading to the highest phytoextraction potential. Despite the intraspecific variability in dieldrin concentration in zucchini plant parts, mainly in the reproductive organs, the phytoextraction capacity for shoots and fruits was high for all tested varieties (147 to 275 μg dieldrin plant− 1, corresponding to 5.6 % of the n-heptane extractable soil dieldrin), even for the one with low fruit dieldrin concentration. Both food safety and phytoextraction could be achieved by selecting productive zucchini varieties displaying low dieldrin concentration in fruits and high one in shoots.
(Science of the Total Environment. vol. 931, n° 0048-9697, pp. 172968, 01/06/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BioGeCo, UB, INRAE, UB, ENSAP Bordeaux, UBM, CNRS