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31.
Methylmercury speciation in the dissolved phase of a stratified lake using the diffusive gradient in thin film technique 总被引:1,自引:0,他引:1
Olivier Clarisse Delphine Foucher Holger Hintelmann 《Environmental pollution (Barking, Essex : 1987)》2009,157(3):987-993
The diffusive gradient in thin film (DGT) technique was successfully used to monitor methylmercury (MeHg) speciation in the dissolved phase of a stratified boreal lake, Lake 658 of the Experimental Lakes Area (ELA) in Ontario, Canada. Water samples were conventionally analysed for MeHg, sulfides, and dissolved organic matter (DOM). MeHg accumulated by DGT devices was compared to MeHg concentration measured conventionally in water samples to establish MeHg speciation. In the epilimnion, MeHg was almost entirely bound to DOM. In the top of the hypolimnion an additional labile fraction was identified, and at the bottom of the lake a significant fraction of MeHg was potentially associated to colloidal material. As part of the METAALICUS project, isotope enriched inorganic mercury was applied to Lake 658 and its watershed for several years to establish the relationship between atmospheric Hg deposition and Hg in fish. Little or no difference in MeHg speciation in the dissolved phase was detected between ambient and spike MeHg. 相似文献
32.
Marie Revel Christophe Colin Stefano Bernasconi Nathalie Combourieu-Nebout Emmanuelle Ducassou Francis E. Grousset Yann Rolland Sebastien Migeon Delphine Bosch Pierre Brunet Yulong Zhao Jean Mascle 《Regional Environmental Change》2014,14(5):1685-1696
The Nile delta sedimentation constitutes a continuous high-resolution record of Ethiopian African monsoon (EAM) regime intensity. Multi-proxy analyses performed on hemipelagic sediments deposited on the Nile deep-sea fan allow the quantification of the Saharan aeolian dust and the Blue/White Nile River suspended matter frequency fluctuations during the last 21,000 years. The radiogenic strontium and neodymium isotopes, clay mineralogy, elemental composition and preliminary palynological analyses reveal large changes in source components, oscillating between a dominant aeolian Saharan contribution during the Last Glacial Maximum (LGM) and the late Holocene (~4,000–2,000 years), a dominant Blue/Atbara Nile River contribution during the early Holocene (15,000–8,000 years) and a probable White Nile River contribution during the middle Holocene (8,000–4,000 years). The following main features are highlighted: (1) The rapid shift from the LGM arid conditions to the African Humid Period (AHP) started at about 15,000 years. The AHP extends until 8,000 years, and we suggest that the EAM maximum between 15,000 and 8,000 years is responsible for a larger Blue/Atbara Nile sediment load and freshwater input into the eastern Mediterranean Sea. (2) The transition between the AHP and the arid late Holocene is gradual and occurs in two main phases between 8,400–6,500 years and 6,500–3,200 years. We suggest that the main rain belt shifted southward from 8,000 to ~4,000 years and was responsible for progressively reduced sediment load and freshwater input into the eastern Mediterranean Sea. (3) The aridification along the Nile catchments occurred from ~4,000 to 2,000 years. This dry period, which culminates at 3,200 year, seems to coincide with a re-establishment of increased oceanic primary productivity in the western Mediterranean Sea. Such a pattern imposes a large and rapid northward shift of the rain belt over the Ethiopian highlands (5–15°N) since 15,000 years. Precipitation over Ethiopia increased from 15,000 to 8,000 years. It was followed by a gradual southward shift of the rain belt over the equator from 8,000 to 4,000 years and finally a large shift of the rain belt south the equator between 4,000 and 2,000 years inducing North African aridification. We postulate that the decrease in thermohaline water Mediterranean circulation could be part of a response to huge volumes of freshwater delivered principally by the Nile River from 15,000 to 8,000 years in the eastern Mediterranean. 相似文献
33.
Emilio D’Ugo Stefania Marcheggiani Ilaria Fioramonti Roberto Giuseppetti Roberto Spurio Karim Helmi Delphine Guillebault Linda K. Medlin Ivan Simeonovski Bas Boots Ulrich Breitenbach Latife Koker Meric Albay Laura Mancini 《Food and environmental virology》2016,8(3):206-214
The transmission of water-borne pathogens typically occurs by a faecal–oral route, through inhalation of aerosols, or by direct or indirect contact with contaminated water. Previous molecular-based studies have identified viral particles of zoonotic and human nature in surface waters. Contaminated water can lead to human health issues, and the development of rapid methods for the detection of pathogenic microorganisms is a valuable tool for the prevention of their spread. The aims of this work were to determine the presence and identity of representative human pathogenic enteric viruses in water samples from six European countries by quantitative polymerase chain reaction (q-PCR) and to develop two quantitative PCR methods for Adenovirus 41 and Mammalian Orthoreoviruses. A 2-year survey showed that Norovirus, Mammalian Orthoreovirus and Adenoviruses were the most frequently identified enteric viruses in the sampled surface waters. Although it was not possible to establish viability and infectivity of the viruses considered, the detectable presence of pathogenic viruses may represent a potential risk for human health. The methodology developed may aid in rapid detection of these pathogens for monitoring quality of surface waters. 相似文献
34.
Reyhan Akçaalan Meric Albay Latife Koker Julia Baudart Delphine Guillebault Sabine Fischer Wilfried Weigel Linda K. Medlin 《Environmental monitoring and assessment》2018,190(1):42
Monitoring drinking water quality is an important public health issue. Two objectives from the 4 years, six nations, EU Project μAqua were to develop hierarchically specific probes to detect and quantify pathogens in drinking water using a PCR-free microarray platform and to design a standardised water sampling program from different sources in Europe to obtain sufficient material for downstream analysis. Our phylochip contains barcodes (probes) that specifically identify freshwater pathogens that are human health risks in a taxonomic hierarchical fashion such that if species is present, the entire taxonomic hierarchy (genus, family, order, phylum, kingdom) leading to it must also be present, which avoids false positives. Molecular tools are more rapid, accurate and reliable than traditional methods, which means faster mitigation strategies with less harm to humans and the community. We present microarray results for the presence of freshwater pathogens from a Turkish lake used drinking water and inferred cyanobacterial cell equivalents from samples concentrated from 40 into 1 L in 45 min using hollow fibre filters. In two companion studies from the same samples, cyanobacterial toxins were analysed using chemical methods and those dates with highest toxin values also had highest cell equivalents as inferred from this microarray study. 相似文献
35.
Delphine Cottin Damien Roussel Natacha Foucreau Frédéric Hervant Christophe Piscart 《Die Naturwissenschaften》2012,99(4):259-264
In the global warming context, we compared the thermal tolerance of several populations of the crustacean Gammarus pulex (Amphipoda: Gammaridae) along a latitudinal thermal gradient in the Rh?ne Valley. To disentangle the effect of regional (North
vs. South) and local (site-specific) factors, the ecophysiological responses of populations were investigated at two levels
of biological organisation: whole organism level considering body size [critical thermal maximum (CTmax), mean speed of locomotion
(MS), time mobile (TM)] and organelle function level [mitochondrial respiratory control ratios (RCRs)]. CTmax and RCRs, but
not MS and TM, revealed a significantly higher thermal tolerance in southern populations compared to northern ones. Nevertheless,
temperatures ≥ 30°C were deleterious for all populations, suggesting that populations located in the warmer limit of the species
distribution will be more threatened by climate change as they live closer to their upper thermal limits. The strong differences
observed between populations indicate that the species-level thermal tolerance used in predictive models may not be informative
enough to study the impact of global warming on species distributions. This work also reveals that an appropriate choice of
indicators is essential to study the consequences of global warming since the response of organisms at the whole body level
can be influenced by local conditions. 相似文献
36.
Modelling radionuclide transfers between seawater and marine species on a short time scale basis requires being able to take into account the transfer kinetics. This means (1) to implement the effect of the biological half-lives of radionuclides together with the concentration factor in the calculation of transfers and (2), to get these kinetic parameters for each element and species. Biological half-lives are usually determined from laboratory labelling experiments with the challenge to match natural environmental conditions. The present work proposes a simple model that implements the effect of kinetic parameters in the calculation of transfers. This model is also used to derive the biological half-life and the concentration factor for 137Cs from time-series measurements of environmental concentrations in seawater and in the brown alga Fucus serratus, as an example. These transfer parameters are finally used to predict the Cs activities in Fucus serratus on the English Channel shores. 相似文献
37.
Höhener Patrick Guers Delphine Malleret Laure Boukaroum Ouassim Martin-Laurent Fabrice Masbou Jérémy Payraudeau Sylvain Imfeld Gwenaël 《Environmental Chemistry Letters》2022,20(6):3927-3942
Environmental Chemistry Letters - The transfer of pesticides from agricultural soils to food and drinking water is a major health issue. There are actually few robust methods to identify,... 相似文献