The Gironde Estuary, one of the largest European ones, presents temporary low dissolved oxygen content in its fluvial section close to the Bordeaux urban area. In a context of population growth and ...of long-term environmental changes, the development of a high-frequency monitoring programme of the fluvial-estuarine system of the Gironde, called MAGEST (MArel Gironde ESTuary), had appeared essential to address current and future water-quality issues/evaluations. The objectives of the MAGEST survey program are to establish a reference database to improve the knowledge of the Gironde Estuary functioning, encompassing the aspects of hydrology, sediment dynamics and biogeochemistry. Through examples of results from intratidal to seasonal time scales, we demonstrate how such a long-term, high-frequency monitoring of a fluvio-estuarine system is of valuable interest to extract the main trends of its functioning and of the water quality in relation to external forcings (climatology, urban wastes, land use, ...) and to predict the future evolution of an estuary with global and environmental changes.
From 2008 to 2014, the MAREL-Iroise buoy, located in the Bay of Brest, collected high-frequency measurements of partial pressure of CO2 (pCO2) and ancillary hydrographic parameters, in conjunction ...with a comprehensive sampling regime of two additional carbonate system variables total alkalinity (AT), and dissolved inorganic carbon (DIC). Biological processes drive variations in AT and DIC throughout the year, except in winter, when primary production is negligible and large freshwater inputs occur. Annually, the Bay of Brest generally behaves as a source of CO2 to the atmosphere (0.14±0.20molCm−2yr−1), showing inter-annual variability significantly linked to annual net community production (NCP). The presence of a large community of benthic filter feeders leads to high levels of particulate organic matter (POM) and opal deposition during the spring diatom bloom. Over the following few months, benthic POM remineralisation reduces the spring CO2 deficit relative to the atmosphere, and remineralisation of biogenic silica supplies further late spring primary production. The result is an inverse spring NCP – air-sea CO2 flux relationship, whereby greater NCP in early spring results in lower fluxes of CO2 into the Bay in late spring. This recycling mechanism, or silicic acid pump, also links the spring and summer NCP values, which are both determined by the peak wintertime nutrient concentrations. The carbonate system is further affected by the benthic community in winter, when CaCO3 dissolution is evident from notable deviations in the ΔAT:ΔDIC ratio. This study highlights the necessity of individual study of coastal, temperate ecosystems and contributes to a better understanding of what determines coastal areas as sinks or sources of CO2 to the atmosphere.
•The Bay of Brest generally behaves as a source of CO2 to the atmosphere.•Inter-annual variability in air-sea CO2 exchange is linked to net community production.•Springtime net community production is determined by the winter, river dissolved silica supply.•Total alkalinity and dissolved inorganic carbon variability is driven by biology.
High-frequency pCO2 and ancillary data were recorded for seven years during the first deployment of a CARbon Interface OCean Atmosphere (CARIOCA) sensor in the surface waters of a temperate coastal ...ecosystem, the Bay of Brest, which is impacted by both coastal (via estuaries) and oceanic (North Atlantic via the Iroise Sea) water inputs. The CARIOCA sensor proved to be an excellent tool to constrain the high pCO2 variability in such dynamic coastal ecosystem. Biological processes (e.g. pelagic photosynthesis/respiration) were the main drivers of the seasonal and diurnal pCO2 dynamics throughout seven years of observations. Autotrophic processes were responsible for abrupt pCO2 drawdown of 100 to 200 mu atm in spring. During the spring bloom, diurnal variations were driven by diel biological cycle. The average daily drawdown due to autotrophy (observed during highest daily PAR) was equivalent to 10 to 60% of the total pCO2 drawdown observed every year during the spring season. From late summer to fall, heterotrophic processes increased pCO2 in the surface water of the Bay back to the pre-bloom level. The average daily increase due to heterotrophy (observed during lowest daily PAR) corresponded to 10 to 70% of the total pCO2 increase observed every year during the late summer to fall period. Air-sea CO2 fluxes estimates based on hourly, daily and monthly calculations showed that careful consideration of the diurnal variability was needed to accurately estimate air-sea CO2 fluxes in the Bay of Brest. Sampling only during daytime or night-time would induce 8 to 36% error on monthly air-sea CO2 fluxes. This would in turn reverse the direction of the fluxes at annual level for the Bay. The annual emissions of CO2 from the surface waters of the Bay to the atmosphere showed relatively low inter-annual variations with an average of +0.7+/-0.4molCm-2yr super(-1) computed for the study period. Further, air-sea CO2 fluxes computed for the adjacent inner-estuaries and Iroise Sea for an annual cycle were +17+/-3molCm-2yr super(-1) and -0.2+/-0.2molCm-2yr super(-1), respectively. The spatial gradient showed a clear pattern from strong source to sink of CO2, from the inner-estuaries to the open oceanic waters of the North Atlantic. We suggest that semi-enclosed Bays act as buffers for sea to air emissions of CO2 from inner estuaries to adjacent costal seas.
The French coast of the eastern English Channel (ECC) is
classified as a potential eutrophication zone by the Oslo and Paris (OSPAR) Convention and as moderate to poor according to the phytoplankton
...quality element of the Water Framework Directive (WFD). It is regularly
affected by Phaeocystis globosa bloom events, which have detrimental effects on the marine
ecosystem, economy, and public health. In this context and to improve our
observation strategy, MAREL Carnot, a multi-sensor oceanographic station,
was installed in the eastern English Channel in 2004 at the Carnot wall in
Boulogne-sur-Mer. The aim of this station was to collect high-frequency
measurements of several water quality parameters to complement conventional
low-resolution monitoring programs. The purpose of this paper is to describe
the MAREL Carnot dataset and show how it can be used for several research
objectives. MAREL Carnot collects high-frequency, multi-parameter
observations from surface water as well as meteorological measurements and
sends the data in near real-time to an onshore data center. In this paper,
we present several physical, chemical, and biological parameters measured by
this station. We also demonstrate that the MAREL Carnot dataset can be used
to assess environmental or ecological statuses and conduct research in the
field of marine phytoplankton ecology and oceanography. In addition, we
show that this dataset may indirectly aid in improving European
environmental management strategies. The MAREL
Carnot dataset is publicly accessible via https://doi.org/10.17882/39754 (MAREL Carnot,
2023).
High-frequency pCO
2 and ancillary data were recorded for seven years during the first deployment of a CARbon Interface OCean Atmosphere (CARIOCA) sensor in the surface waters of a temperate coastal ...ecosystem, the Bay of Brest, which is impacted by both coastal (via estuaries) and oceanic (North Atlantic via the Iroise Sea) water inputs. The CARIOCA sensor proved to be an excellent tool to constrain the high pCO
2 variability in such dynamic coastal ecosystem. Biological processes (e.g. pelagic photosynthesis/respiration) were the main drivers of the seasonal and diurnal pCO
2 dynamics throughout seven years of observations. Autotrophic processes were responsible for abrupt pCO
2 drawdown of 100 to 200
μatm in spring. During the spring bloom, diurnal variations were driven by diel biological cycle. The average daily drawdown due to autotrophy (observed during highest daily PAR) was equivalent to 10 to 60% of the total pCO
2 drawdown observed every year during the spring season. From late summer to fall, heterotrophic processes increased pCO
2 in the surface water of the Bay back to the pre-bloom level. The average daily increase due to heterotrophy (observed during lowest daily PAR) corresponded to 10 to 70% of the total pCO
2 increase observed every year during the late summer to fall period. Air–sea CO
2 fluxes estimates based on hourly, daily and monthly calculations showed that careful consideration of the diurnal variability was needed to accurately estimate air–sea CO
2 fluxes in the Bay of Brest. Sampling only during daytime or night-time would induce 8 to 36% error on monthly air–sea CO
2 fluxes. This would in turn reverse the direction of the fluxes at annual level for the Bay. The annual emissions of CO
2 from the surface waters of the Bay to the atmosphere showed relatively low inter-annual variations with an average of +
0.7
±
0.4
mol
C
m
−2
yr
−
1
computed for the study period. Further, air–sea CO
2 fluxes computed for the adjacent inner-estuaries and Iroise Sea for an annual cycle were +
17
±
3
mol
C
m
−2
yr
−
1
and −
0.2
±
0.2
mol
C
m
−2
yr
−
1
, respectively. The spatial gradient showed a clear pattern from strong source to sink of CO
2, from the inner-estuaries to the open oceanic waters of the North Atlantic. We suggest that semi-enclosed Bays act as buffers for sea to air emissions of CO
2 from inner estuaries to adjacent costal seas.
► We assessed pCO
2 dynamics from diurnal to inter-annual level in the Bay of Brest. ► Pelagic biological processes controlled pCO
2 dynamics from spring to fall. ► Integrating pCO
2 diurnal variability is imperative for air–sea CO
2 fluxes estimates. ► Bays act as buffers for sea to air CO
2 emissions from estuaries to coastal seas.
The Gironde Estuary, one of the largest European ones, presents temporary low dissolved oxygen content in its fluvial section close to the Bordeaux urban area. In a context of population growth and ...of long-term environmental changes, the development of a high-frequency monitoring programme of the fluvial-estuarine system of the Gironde, called MAGEST (MArel Gironde ESTuary), had appeared essential to address current and future water-quality issues/evaluations. The objectives of the MAGEST survey program are to establish a reference database to improve the knowledge of the Gironde Estuary functioning, encompassing the aspects of hydrology, sediment dynamics and biogeochemistry. Through examples of results from intratidal to seasonal time scales, we demonstrate how such a long-term, high-frequency monitoring of a fluvio-estuarine system is of valuable interest to extract the main trends of its functioning and of the water quality in relation to external forcings (climatology, urban wastes, land use, ...) and to predict the future evolution of an estuary with global and environmental changes.
The deposition of transparent conductive oxides (TCO) usually employs harsh conditions that are frequently harmful to soft/organic underlayers. Herein, successful use of an industrial pulsed laser ...deposition (PLD) tool to directly deposit indium tin oxide (ITO) films on semitransparent vacuum‐deposited perovskite solar cells without damage to the device stack is demonstrated. The morphological, electronic, and optical properties of the PLD deposited ITO films are optimized. A direct relation between the PLD chamber pressure and the solar cell performance is obtained. The semitransparent perovskite solar cells prepared exclusively by vacuum‐assisted techniques had fill factors of 78% and exceeded 18% in power conversion efficiencies. This demonstrates that the direct deposition of TCO‐based top electrodes without protective buffer layers is possible and leads to efficient devices.
Pulsed laser deposition can be employed to deposit indium tin oxide (ITO) topcontacts directly on thin organic semiconductor layers without damage, leading to efficient semitransparent perovskite solar cells without protective buffer layers exceeding 18% PCE.
Assessing the cheese-making properties (CMP) of milks with a rapid and cost-effective method is of particular interest for the Protected Designation of Origin cheese sector. The aims of this study ...were to evaluate the potential of mid-infrared (MIR) spectra to estimate coagulation and acidification properties, as well as curd yield (CY) traits of Montbéliarde cow milk. Samples from 250 cows were collected in 216 commercial herds in Franche-Comté with the objectives to maximize the genetic diversity as well as the variation in milk composition. All coagulation and CY traits showed high variability (10 to 43%). Reference analyses performed for soft (SC) and pressed cooked (PCC) cheese technology were matched with MIR spectra. Prediction models were built on 446 informative wavelengths not tainted by the water absorbance, using different approaches such as partial least squares (PLS), uninformative variable elimination PLS, random forest PLS, Bayes A, Bayes B, Bayes C, and Bayes RR. We assessed equation performances for a set of 20 CMP traits (coagulation: 5 for SC and 4 for PCC; acidification: 5 for SC and 3 for PCC; laboratory CY: 3) by comparing prediction accuracies based on cross-validation. Overall, variable selection before PLS did not significantly improve the performances of the PLS regression, the prediction differences between Bayesian methods were negligible, and PLS models always outperformed Bayesian models. This was likely a result of the prior use of informative wavelengths of the MIR spectra. The best accuracies were obtained for curd yields expressed in dry matter (CYDM) or fresh (CYFRESH) and for coagulation traits (curd firmness for PCC and SC) using the PLS regression. Prediction models of other CMP traits were moderately to poorly accurate. Whatever the prediction methodology, the best results were always obtained for CY traits, probably because these traits are closely related to milk composition. The CYDM predictions showed coefficient of determination (R2) values up to 0.92 and 0.87, and RSy,x values of 3 and 4% for PLS and Bayes regressions, respectively. Finally, we divided the data set into calibration (2/3) and validation (1/3) sets and developed prediction models in external validation using PLS regression only. In conclusion, we confirmed, in the validation set, an excellent prediction for CYDM R2 = 0.91, ratio of performance to deviation (RPD) = 3.39 and a very good prediction for CYFRESH (R2 = 0.84, RPD = 2.49), adequate for analytical purposes. We also obtained good results for both PCC and SC curd firmness traits (R2 ≥ 0.70, RPD ≥1.8), which enable quantitative prediction.
In a previous study, we identified candidate causative variants located in 24 functional candidate genes for milk protein and fatty acid composition in Montbéliarde, Normande, and Holstein cows. We ...designed these variants on the custom part of the EuroG10K BeadChip (Illumina Inc., San Diego, CA), which is routinely used for genomic selection analyses in French dairy cattle. To validate the effects of these candidate variants on milk composition and to estimate their effects on cheesemaking properties, a genome-wide association study was performed on milk protein, fatty acid and mineral composition, as well as on 9 cheesemaking traits (3 laboratory cheese yields, 5 coagulation traits, and milk pH). All the traits were predicted from midinfrared spectra in the Montbéliarde cow population of the Franche-Comté region. A total of 194 candidate variants located in 24 genes and 17 genomic regions were imputed on 19,862 cows with phenotypes and genotyped with either the BovineSNP50 (Illumina Inc.) or the EuroG10K BeadChip. We then tested the effect of each SNP in a mixed linear model including random polygenic effects estimated with a genomic relationship matrix. We confirm here the effects of candidate causative variants located in 17 functional candidate genes on both cheesemaking properties and milk composition traits. In each candidate gene, we identified the most plausible causative variant: 4 are missense in the ALPL, SLC26A4, CSN3, and SCD genes, 7 are located in 5′UTR (AGPAT6), 3′ untranslated region (GPT), or upstream (CSN1S1, CSN1S2, PAEP, DGAT1, and PICALM) regions, and 6 are located in introns of the SLC37A1, MGST1, CSN2, BRI3BP, FASN, and ANKH genes.
A global compilation of in situ data is useful to evaluate the quality of ocean-colour satellite data records. Here we describe the data compiled for the validation of the ocean-colour products from ...the ESA Ocean Colour Climate Change Initiative (OC-CCI). The data were acquired from several sources (including, inter alia, MOBY, BOUSSOLE, AERONETOC, SeaBASS, NOMAD, MERMAID, AMT, ICES, HOT, GeP&CO) and span the period from 1997 to 2018. Observations of the following variables were compiled: spectral remote-sensing reflectances, concentrations of chlorophyll-a, spectral inherent optical properties, spectral diffuse attenuation coefficients and total suspended matter. The data were from multi-project archives acquired via open internet services or from individual projects, acquired directly from data providers. Methodologies were implemented for homogenisation, quality control and merging of all data. No changes were made to the original data, other than averaging of observations that were close in time and space, elimination of some points after quality control and conversion to a standard format. The final result is a merged table designed for validation of satellite-derived ocean-colour products and available in text format. Metadata of each in situ measurement (original source, cruise or experiment, principal investigator) were propagated throughout the work and made available in the final table. By making the metadata available, provenance is better documented, and it is also possible to analyse each set of data separately. This paper also describes the changes that were made to the compilation in relation to the previous version (Valente et al., 2016). The compiled data are available at https://doi.org/10.1594/PANGAEA.898188.
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