Considerations sur les formes physico-chimiques du cobalt, manganese, zinc, chrome et fer dans une eau de mer enrichie ou non de matiere organique     

Marchand  Michel 《ICES Journal of Marine Science》1974,35(2):130-142

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Detection of manure-derived organic compounds in rivers draining agricultural areas of intensive manure spreading     

Emilie Jardé  Gérard Gruau  Laurence Mansuy-Huault 《Applied Geochemistry》2007

It is essential to have suitable tools able to trace the fate of manure organic matter in the environment to assess whether manure disposal on the soils of catchments could affect the organic quality of rivers. Sterol compounds – mainly expressed as C_29 + 28/C₂₇ and 5β/C₂₇ ratios – have been shown to be specific molecular tracers of pig, dairy and poultry manures in soils. The objective of this study was to measure C_29 + 28/C₂₇ and 5β/C₂₇ ratios in five Brittany rivers (Elorn, Yar, Léguer, Min Ran and Couesnon) draining agricultural catchments receiving massive annual inputs of pig, poultry and dairy manures and compare these ratios with ratios published for enriched soils and manure samples. The particulate organic fractions from the studied rivers yielded steroid signatures typical of animal manures. More specifically, a stanol compound diagnostic of pig slurry – the 5β-stanol known as coprostanol – was found to be very widespread, with particularly high concentrations in one of the rivers (Elorn). The C_29 + 28/C₂₇ and 5β/C₂₇ ratios of the particulate fractions of the rivers were compared with ratios measured directly in pig, dairy and poultry manure samples, as well as with the breeding activities on river catchments. These comparisons show that the steroid profiles of the five investigated rivers correlate closely with the types of manure (i.e. pig, poultry or dairy) spread on soils in their catchments. For instance, the C_29 + 28/C₂₇ and 5β/C₂₇ ratios in the Elorn river are similar to the values typical of pig slurry (e.g. 5β/C₂₇ > 4); compared with other catchments, the soils in this area receive by far the largest amount of pig slurry. By contrast, the Yar river drains a catchment receiving only poultry and dairy manures, and its soils exhibit C_29 + 28/C₂₇ and 5β/C₂₇ ratios similar to those of dairy and poultry manures (e.g. 5β/C₂₇ ∼ 1). Thus, this study indicates that the organic quality of rivers is modified in catchments where there is intense manure spreading on soils. It also provides evidence that rivers draining areas receiving different manure types may exhibit differences in the long-term evolution of their OM content. Indeed, two of the investigated river catchments receive dominantly dairy and poultry manure, and exhibit clear long-term upward trends in OM. On the other hand, one catchment receiving high proportions of pig slurry clearly shows a long-term downward trend in OM contents. A survey of the literature shows that the relative amount of OM and N received by soils in agricultural catchments could be the key parameter in determining the direction of the long-term OM trend of the river, rather than the absolute amount and/or type of manure that is applied to the soil. In any case, the present study suggests that sterol/stanol compounds may be of diagnostic value in determining whether a stream or a river is undergoing contamination by manure-derived organic matter.  相似文献   

Kinetic Study of the Reactions of Ozone with Polycyclic Aromatic Hydrocarbons Adsorbed on Atmospheric Model Particles   总被引：1，自引：0，他引：1  

Emilie Perraudin  Hélène Budzinski  Eric Villenave 《Journal of Atmospheric Chemistry》2007,56(1):57-82

In this experimental study, rate constants were measured for the reactions of ozone with 13 polycyclic aromatic hydrocarbons (PAHs) adsorbed on different types of particles. Graphite and silica were chosen to model, respectively, carbonaceous and mineral atmospheric particles. The pseudo-first order rate constants were obtained from the fit of the experimental decay of particulate PAH concentrations versus time. Second order rate constants were calculated considering the ozone gaseous concentration. At room temperature, rate constants varied, in the case of graphite particles, between (1.5 ± 0.5) × 10⁻¹⁷ and (1.3 ± 0.7) × 10⁻¹⁶ cm³ molecule⁻¹ s⁻¹ for chrysene and dibenzo[a,l]pyrene, respectively, and, in the case of silica particles, between (1.5 ± 0.3) × 10⁻¹⁷ and (1.4 ± 0.3) × 10⁻¹⁶ cm³ molecule⁻¹ s⁻¹ for fluoranthene and benzo[a]pyrene, respectively. Different granulometric parameters (particle size, pore size) and different PAH concentrations were tested in the case of silica particles. Heterogeneous reactions of ozone with particulate PAHs are shown to be more rapid than those occurring in the gas-phase, and may be competitive with atmospheric photodegradation.  相似文献   

High resolution simulation of recent Arctic and Antarctic stratospheric chemical ozone loss compared to observations     

Om Prakash Tripathi  Sophie Godin-Beekmann  Franck Lefèvre  Marion Marchand  Andrea Pazmiño  Alain Hauchecorne  Florence Goutail  Hans Schlager  C. Michael Volk  B. Johnson  G. König-Langlo  Stefano Balestri  Fred Stroh  T. P. Bui  H. J. Jost  T. Deshler  Peter von der Gathen 《Journal of Atmospheric Chemistry》2006,55(3):205-226

Simulations of polar ozone losses were performed using the three-dimensional high-resolution (1^∘ × 1^∘) chemical transport model MIMOSA-CHIM. Three Arctic winters 1999–2000, 2001–2002, 2002–2003 and three Antarctic winters 2001, 2002, and 2003 were considered for the study. The cumulative ozone loss in the Arctic winter 2002–2003 reached around 35% at 475 K inside the vortex, as compared to more than 60% in 1999–2000. During 1999–2000, denitrification induces a maximum of about 23% extra ozone loss at 475 K as compared to 17% in 2002–2003. Unlike these two colder Arctic winters, the 2001–2002 Arctic was warmer and did not experience much ozone loss. Sensitivity tests showed that the chosen resolution of 1^∘ × 1^∘ provides a better evaluation of ozone loss at the edge of the polar vortex in high solar zenith angle conditions. The simulation results for ozone, ClO, HNO₃, N₂O, and NO _y for winters 1999–2000 and 2002–2003 were compared with measurements on board ER-2 and Geophysica aircraft respectively. Sensitivity tests showed that increasing heating rates calculated by the model by 50% and doubling the PSC (Polar Stratospheric Clouds) particle density (from 5 × 10⁻³ to 10⁻² cm⁻³) refines the agreement with in situ ozone, N₂O and NO _y levels. In this configuration, simulated ClO levels are increased and are in better agreement with observations in January but are overestimated by about 20% in March. The use of the Burkholder et al. (1990) Cl₂O₂ absorption cross-sections slightly increases further ClO levels especially in high solar zenith angle conditions. Comparisons of the modelled ozone values with ozonesonde measurement in the Antarctic winter 2003 and with Polar Ozone and Aerosol Measurement III (POAM III) measurements in the Antarctic winters 2001 and 2002, shows that the simulations underestimate the ozone loss rate at the end of the ozone destruction period. A slightly better agreement is obtained with the use of Burkholder et al. (1990) Cl₂O₂ absorption cross-sections.  相似文献   

Etude physico-chimique des résidus de pyrolyse de la sporopollénine     

Pierre Libert  André Marchand  Marie-France Achard 《Geochimica et cosmochimica acta》1976,40(2):143-148

Two parameters are chosen to characterize the pyrolysis residues of sporopollenin: the first one is the $\text{d}{}_{1600}\text{d}{}_{1700}$ ratio, where d₁₆₀₀ and d₁₇₀₀ are the optical densities of the absorption bands at 1600 and 1700 cm^?1, respectively; the second one is the paramagnetic susceptibility χ_p measured by E.P.R.Those two quantities increase rapidly above 300°C, which confirms previous results that the sporopollenin structure undergoes important modifications at this temperature. A striking similarity is observed between the properties of sporopollenin residues and those of natural kerogens.  相似文献   

Quantitative geography: Revolution or counter-revolution?Quantitative geographie: Revolution oder konterrevolution?La géographie quantitative: Révolution ou contre-révolution?     

Bernard Marchand 《Geoforum》1974,5(1):15-23

There has been a crisis of the so-called “quantitative geography” for a few years. It is partly due to a poor use of mathematics, often presented for its own sake. There are also deeper reasons: refusal of rational formalization; and more emphasis on social and political studies.This paper tries to snow that a formal language (i.e., vocabulary and syntax) is necessary. Linguistics show how a language can be perverted by ideology into a myth. This has happened with traditional geography and is still present in some recent radical studies.  相似文献   

Milankovitch and sub‐Milankovitch forcing of the Oxfordian (Late Jurassic) Terres Noires Formation (SE France) and global implications     

S. Boulila  B. Galbrun  L. A. Hinnov  P.‐Y. Collin  J. G. Ogg  D. Fortwengler  D. Marchand 《Basin Research》2010,22(5):717-732

High‐resolution analysis (2277 samples) of magnetic susceptibility (MS) was performed on ～700‐m‐thick Early–Middle Oxfordian marine marls of the Terres Noires Formation, SE France. MS variations within these sediments record sub‐Milankovitch to Milankovitch frequencies with long‐term eccentricity (405 kyr and ～2 Myr) being the most prominent. The 405 kyr cycle was used as a high‐resolution geochronometer for astronomical calibration of this poorly constrained interval of Late Jurassic time. The estimated duration of this Early–Middle Oxfordian interval concurs with the current International Geologic Time Scale GTS2004 (～4 Myr), but the estimated durations of the corresponding ammonite zones are notably different. The calibration improves the resolution and accuracy of the M‐sequence magnetic anomaly block model that was previously used to establish the Oxfordian time scale. Additionally, the 405 kyr cyclicity is linked to third‐order sea‐level depositional sequences observed for Early–Middle Oxfordian time. Strong ～2 Myr cycles are consistent with long‐term eccentricity modulation predicted for the Late Jurassic. These cycles do not match second‐order sequences that have been documented for European basins; this raises questions about the definition and hierarchy of depositional sequences in the Mesozoic eustatic chart. Our results require substantial revisions to the chart, which is frequently used as a reference for the correlation of widely separated palaeogeographic domains. Finally, a long‐term trend in the MS data reflects a progressive carbonate enrichment of the marls expressing an Early Oxfordian global cooling followed gradually by a warming in the Middle Oxfordian. This trend also records a major transgressive interval likely peaking at the Transversarium ammonite zone of the Middle Oxfordian.  相似文献   

Water Biogeochemistry of a Mangrove-Dominated Estuary Under a Semi-Arid Climate (New Caledonia)     

Audrey Leopold  Cyril Marchand  Jonathan Deborde  Michel Allenbach 《Estuaries and Coasts》2017,40(3):773-791

Mangrove water biogeochemistry has been frequently studied under tropical climates, but less is known regarding mangroves in semi-arid climates. In this study, we examine the carbon and nutrient biogeochemistry in a mangrove tidal creek and in the main branch of a semi-arid estuary in New Caledonia. Porewater seepage represents a source of nutrients (DON, NH₄ ⁺, and DIP), carbon (DOC and CO₂), and alkalinity for the water column, but seawater dilution of the mangrove inputs is observed. Spatial and tidal variations in CO₂ fluxes along the tidal creek suggest that porewater seepage is a driver of CO₂ emission into the atmosphere. Large seasonal and spatial differences in the biogeochemical functioning of the main channel are observed and are mainly related to the seasonal rainfall pattern. During the rainy season, the watershed influences the entire estuary, which exhibits a typical positive circulation. During the dry season, the estuary turns into a salt-plug region with positive and negative circulations in the upper and lower reaches, respectively. In this case, the upper and lower reaches seem to function independently, and the biogeochemical functioning of their water column is not controlled by the same processes. Surprisingly, pCO₂@27 °C values tend to be higher during the dry season, as do the total alkalinity (TAlk) values, while the pH values exhibit an opposite trend. Moreover, the TAlk values are higher in the lower reaches during the wet season and in the upper reaches during the dry season. These results indicate high in situ biogeochemical reactions and high porewater influence during the dry season, likely because of a low flushing rate and high water residence time after salt plug establishment. Although our results suggest that salt plugs may significantly affect the water column’s biogeochemistry and may promote CO₂ emissions of mangrove-derived carbon, further investigations, especially mass balance studies, are required to quantify their role in the biogeochemical functioning of such estuarine systems.  相似文献   

Metal concentrations in the milk and tissues of a nursing Tursiops truncatus female     

Frodello JP  Viale D  Marchand B 《Marine pollution bulletin》2002,44(6):551-554

Metal concentrations measured in the organs of beached whales are published regularly. Few of these, however, describe metal levels in nursing females. In the present study, mercury, lead, copper and zinc levels were measured in the milk and tissues of a female Bottlenose dolphin. Results reveal that metal pollutants pass from the tissue into the milk.  相似文献   

High albedo dune features suggest past dune migration and possible geochemical cementation of aeolian sediments on Mars     

Emilie Gardin  Mary C. Bourke  Pascal Allemand 《Icarus》2011,212(2):590-596

High albedo features are identified in association with barchan dunes in an equatorial inter-crater dune field on Mars using images from the MRO mission. This paper describes the morphometric properties of these features and their association with the present barchan dune field. We propose that these features are cemented aeolian deposits that form at the foot of the dune avalanche face. A possible terrestrial analog exists at White Sands National Monument, in south-central New Mexico, USA. The presence of these features suggests past episodes of dune migration in inter-crater dunefields and liquid water in the near sub-surface in sufficient quantity to cause the cementation of aeolian dune sediment.  相似文献