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We simultaneously measured bacterial production (BP), bacterial respiration (BR), alkaline phosphatase activity ( phos) and ectoaminopeptidase activity ( prot) in relation to biogeochemical parameters, nutritive resources and in situ temperature over a 1-year survey at the long-term observatory the SOLEMIO station (Marseille bay, NW Mediterranean Sea). Despite its proximity to the coast, oligotrophic conditions prevailed at this station (yearly mean of Chl a = 0.43 μg dm, NO = 0.55 μmol dm and PO = 0.04 μmol dm). Episodic meteorological events (dominant winds, inputs from the Rhone River) induced rapid oscillations (within 15 days) in temperature and sometimes salinity that resulted in rapid changes in phytoplankton succession and a high variability in C/P ratios within the particulate and dissolved organic matter. Throughout the year, BP ranged from 0.01 to 0.82 μg C dm− h− and bacterial growth efficiency varied from 1 to 39 %, with higher values in summer. Enrichment experiments showed that BP was limited most of the year by phosphorus availability (except in winter). A significant positive correlation was found between in situ temperature, BP, BR and phos. Finally, we found that temperature and phosphate availability were the main factors driving heterotrophic bacterial activity and thus play a fundamental role in carbon fluxes within the marine ecosystem. [ABSTRACT FROM AUTHOR]

Carbohydrates are important components of the carbon cycle and may be used as indicators of the origin and the diagenetic status of marine and terrestrial organic matter. Nevertheless, comprehensive studies of both particulate (PCHO) and dissolved (DCHO) carbohydrates in rivers are scarce, and the seasonal and interannual variability of these compounds in relationship to the bulk particulate (POM) and dissolved organic matter (DOM) is largely unknown. For the period 2007-2009, we sampled once per month POM and DOM and measured the total suspended matter (TSM), POM, DOM, PCHO, and DCHO for the Rhône River, which flows into the Mediterranean Sea. Using these measurements, we estimated for the above parameters annual fluxes for the period 2001-2010. The estimated carbohydrate fluxes averaged 0.061±0.043x1010 moles C y-1 for PCHO and 0.041±0.0062x1010 moles C y-1 DCHO, representing 8% and 7% of the annual flux of POC and DOC, respectively. During flood and low-water periods, POM variations were reflected into the PCHO pool, whereas this was not observed for DOC and DCHO, indicating a decoupling between particulate and dissolved organic matter. Our results also showed that flood and low-water periods may be differentiated using the ratios PCHO/DCHO and POC/DOC, which had a significant linear relationship. Based on the carbohydrate abundances in both the PCHO and DCHO pools, we conclude that this material mainly derives from allochthonous sources (vascular plants, bacteria and soils). Moreover, during flood events, an enrichment in mannose in POM was observed, probably reflecting an angiosperm source (leaves or grasses). By expanding our results to the northwestern Mediterranean Sea (Gulf of Lions), we found that the total organic carbon (TOC) fluxes of the Rhône River accounted for ~1% of the standing stock of seawater TOC. Considering that glucose is the most abundant carbohydrate in both particulate and dissolved organic matter pools (~33 %), its annual flux in the northwestern Mediterranean Sea was estimated to 19.2x108 moles glucose-C. [ABSTRACT FROM AUTHOR]

Seawater samples were collected in surface waters (2 and 5m depths) of the Bay of Marseilles (Northwestern Mediterranean Sea; 5° 17' 30" E, 43°14' 30" N) during one year from November 2007 to December 2008 and studied for total organic carbon (TOC) as well as chromophoric dissolved organic matter (CDOM) optical properties (absorbance and fluorescence). The annual mean value of surface CDOM absorption coefficient at 350 nm [aCDOM(350)] was very low (0.10±0.02 m-1) with in comparison to values usually found in coastal waters, and no significant seasonal trend in aCDOM(350) could be determined. By contrast, the spectral slope of CDOM absorption (SCDOM) was significantly higher (0.023±0.003 nm-1) in summer than in fall and winter periods (0.017±0.002 nm-1), reflecting either CDOM photobleaching or production in surface waters during stratified sunny periods. The CDOM fluorescence, assessed through excitation emission matrices (EEMs), was dominated by protein-like component (peak T; 1.30-21.94 QSU) and marine humic-like component (peak M; 0.55-5.82 QSU), while terrestrial humic-like fluorescence (peak C; 0.34-2.99 QSU) remained very low. This reflected a dominance of relatively fresh material from biological origin within the CDOM fluorescent pool. At the end of summer, surface CDOM fluorescence was very low and strongly blue shifted, reinforcing the hypothesis of CDOM photobleaching. Our results suggested that unusual Rhône River plume eastward intrusion events may reach Marseilles Bay within 2-3 days and induce local phytoplankton blooms and subsequent fluorescent CDOM production (peaks M and T) without adding terrestrial fluorescence signatures (peak C). Besides Rhône River plumes, mixing events of the entire water column injected humic (peaks C and M) CDOM from the bottom into the surface and thus appeared also as an important source of CDOM in surface waters of the Marseilles Bay. Therefore, the assessment of CDOM optical properties, within the hydrological context, pointed out several biotic (in situ biological production, biological production within Rhône River plumes) and abiotic (photobleaching, mixing) factors controlling CDOM transport, production and removal in this highly urbanized coastal area. [ABSTRACT FROM AUTHOR]

Drainage basin of the Gulf of Lions is largely dominated by vineyards which require the extensive use of Cu fungicides, leading to continuous copper accumulation in surface soils. In this area, soils depict among the highest Cu pollution levels in Europe. In order to draw up a global budget of Cu fluxes to the Gulf of Lions, our approach is based on long-term monitoring of Cu levels in riverine suspended sediments of the Rhone river and coastal Mediterranean river, as well as atmospheric deposits. These compartments have the particularity to be strongly influenced by extreme events typical of the region such as floods and Saharan dust episodes. In coastal rivers, Cu originates mainly from anthropogenic activities linked to viticulture while in the Rhone, calculated enrichment factors show weak anthropogenic influences. Atmospheric deposition often shows high Cu concentration and is both influenced by natural and anthropogenic sources. A main objective was also to decipher the Cu fluxes into their natural and anthropogenic components. A prerequisite was to determine natural backgrounds in the different compartments which surprisingly converge to similar values representative of both local geological nature of rocks in and the Saharan dust signature. Our study suggests that the Rhone River accounts on average for about 88% of both SPM fluxes and natural Cu fluxes to the Gulf of Lions. The contribution of the atmosphere and coastal rivers increases however to about 47% for anthropogenic Cu fluxes. They act as strong sources of contamination during more than a half of the year, from spring to fall, as they dominate the transfer of anthropogenic Cu to the sea. This represents a more continuous exposure for ecosystems whereas natural copper is generally delivered in the form of short pulses in relation to flood events and Saharan dust deposition during autumn and winter., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Human activities affect terrestrial and aquatic habitats leading to changes at both individual and population levels in wild animal species. In this study, we investigated the phenotype and demographics of the Mediterranean pond turtle Mauremys leprosa (Schweigger, 1812) in contrasted environments of Southern France: two peri-urban rivers receiving effluents from wastewater treatment plants (WWTP), and another one without sewage treatment plant. Our findings revealed the presence of pesticides and pharmaceuticals in the three rivers of investigation, the highest diversities and concentrations of pollutants being found in the river subsections impacted by WWTP effluents. Principal component analysis and hierarchical clustering identified three levels of habitat quality, with different pollutant concentrations, thermal conditions, nutrient, and organic matter levels. The highest turtle densities, growth rates, and body sizes were estimated in the most disturbed habitats, suggesting potential adult benefits derived from harsh environmental conditions induced by pollution and eutrophication. Conversely, juveniles were the most abundant in the least polluted habitats, suggesting adverse effects of pollution on juvenile survival or adult reproduction. This study suggests that turtles living in polluted habitats may benefit from enhanced growth and body size, at the expense of reproductive success., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Rationale: Ferulic and p-coumaric acids are important biological and structural components of plant cell walls and possess antioxidant and antimicrobial properties. These phenolic acids are widespread in environmental samples. However, when they are present at very low concentrations or in very complex lipid extracts, their identification and quantification can be challenging., Methods: The electron ionization mass spectrometry (EI-MS) fragmentation pathways of ferulic and p-coumaric acid trimethylsilyl (TMS) derivatives were investigated. These pathways were deduced by (i) low-energy collision-induced dissociation (CID) gas chromatography (GC)/EI-MS/MS, (ii) accurate mass measurement, and (iii) 13 C labelling. These compounds were then characterized and quantified in multiple reaction monitoring (MRM) mode in total lipid extracts of deposited atmospheric particles using highly specific transitions based on the main fragmentation pathways elucidated., Results: Low-energy CID-MS/MS analyses, accurate mass measurement and 13 C labelling enabled us to elucidate EI-MS fragmentations of ferulic and p-coumaric acid TMS derivatives. Some specific fragmentations proved useful for subsequent characterization and quantification of these compounds. As an application of some of the described fragmentations, trace amounts of these phenolic acids were characterized and quantified in MRM mode in wet- and dry-deposited atmospheric particles containing low proportions of organic matter., Conclusions: EI-MS fragmentations of ferulic and p-coumaric acid TMS derivatives exhibit specific fragment ions that can be very useful for the quantification of trace amounts of both phenolic acids in environmental samples., (© 2022 John Wiley & Sons Ltd.)

This paper aims at quantifying current riverine fluxes of microplastics (MPs) in two Mediterranean river catchments, a large one and a small one, namely the Rhône and the Têt, which are discharging to the Gulf of Lion in the Northwestern Mediterranean Sea. MP fluxes change markedly through time and space in both river systems. However, no clear relationships between MP concentrations and hydroclimatic conditions have been observed. In the Rhône River a non-linear dilution pattern of MPs in total suspended matter (TSM) during flood conditions could be observed. Although dilution is important, samples during floods exert a strong control on average MP fluxes. Compared to the Rhône River, average MP concentrations in the Têt River were throughout greater and more variable in shape and polymer composition. However, as the study year was exceptionally dry, the average specific MP flux, 76 g km - 2  y - 1 , is only slightly larger than the non-flooding value of the Rhône River. We further monitored MP concentrations in shoreline sediments at the mouth of the Têt River to test whether these sediments can represent MP transport in the river. Besides fibers, which probably are easily washed out and transported offshore, MP concentrations and compositions are in agreement with MP loads upstream the river. We also examined the potential role of atmospheric deposition as a source of MP to the Têt River. The average atmospheric MP deposition of 6 kg km - 2 y - 1 exceeds by far the river average specific MP flux. Moreover, all MPs in atmospheric deposits were fibers, which in terms of mass are of minor importance in the bulk river fluxes. Atmospheric MP deposits may either have been overestimated and/or may be removed from surface waters by efficient removal processes (such as waste water treatment plants)., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Rationale: Riverine particulate organic matter is generally considered to be refractory with respect to further decomposition in the ocean. In order to check the validity of this paradigm, there is a real need for tracers sufficiently stable and specific to monitor the degradation of terrestrial higher plant material in the environment. 3β-hydroxy-urs-12-en-11-one and 3β-hydroxy-olean-12-en-11-one (autoxidation products of α- and β-amyrin) were previously proposed for such use., Methods: EIMS fragmentation pathways of 3β-hydroxy-urs-12-en-11-one and 3β-hydroxy-olean-12-en-11-one TMS derivatives were investigated. These pathways were deduced by: (i) low energy CID-GC/MS/MS, (ii) accurate mass measurement and (iii) deuterium labelling. Quantification of these compounds in total lipid extracts of natural samples was then carried out in MRM mode., Results: CID-MS/MS analyses, accurate mass measurement and deuterium labelling experiments allowed us to elucidate EIMS fragmentations of 3β-hydroxy-urs-12-en-11-one and 3β-hydroxy-olean-12-en-11-one TMS derivatives. Some specific fragmentation pathways, useful in addition to chromatographic retention times for further characterization, could be selected. As an application of some of the described fragmentations, TMS derivatives of these oxidation products were characterized and quantified in MRM mode in different natural samples., Conclusions: EIMS fragmentations of 3β-hydroxy-urs-12-en-11-one and 3β-hydroxy-olean-12-en-11-one TMS derivatives exhibit specific fragment ions, which appear to be very useful for the quantification of these oxidation products in natural samples (riverine particulate matter, wet and dry deposited atmospheric particles)., (This article is protected by copyright. All rights reserved.)