Etude de la composition chimique de la basse atmosphère des régions cotières antarctiques (station française de Dumont d'Urville)- Antarctique

The geographical and meteorological conditions of polar regions make them of the utmost interest for many environmental studies. Located far away trom continents ( where local sources like wind blow dust, biospheric emissions from vegetation and soils or anthropegenic sources dominate) Antarctic regions have been recognized as having the cleanest atmospheric environment of Southern hemisphere. ln this context, coastal Antarctic areas are particulary well adapted for studying the biogenic emissions from the circumpolar ocean. At the end of 1990, a european program was etablished for the thorough tropospheric chemistry study at the french station (Dumont d' Urville) in Antarctica.The fust part of our study concerned the potential contamination of our site by the base (Dumont d'Urville). It should that the humain activity has a low impact on our sampling, while nearby pingouins rookeries were emitting large amounts of NH3, NH4+, C2O42-, Ca2+, K+, in the atmosphere. The study of atmospheric sulphur species (sulfate and methanesulfonate) showed that sea salt aerosols are fractionned during the winter. The sulfate concentrations in these aerosols are depleted compared to sea water concentrations. Moreover, the Cl-/ Na + ratio are higher in these fractionned aerosols than in sea water. The inter annual variability of atmospheric sulfate concentrations showed a perturbation during the 1991-1992 austral summer. This perturbation is attribued to the gravitational sedimentation of the volcanic plume emitted by the Cerro Hudson eruption. The seasonnality of methanesulfonic acid and non sea salt sulfate is linked to the biological primary productivity of the austral ocean. Also, we demonstrated that the differences in atmospheric concentrations between Dumont d'Urville, Mawson and Georg von Neumayer could be explain by differences in the primary productivity in the sectors of the polar ocean influencing each station. Finally, the atmospheric concentrations of nitrogen species (NH4+, N03-, HN03) suggest that ammonium concentrations measured at Mawson (67.6°S, 62.5°E) are certainly contamined by local rookeries. The sedimentation of Polar Stratospheric Cloud is probably responsable for the saisonnality we observed in the nitrogen oxydes concentrations measured in coastal antarctic areas.L'atmosphère des régions polaires peut être considérée comme une atmosphère de "bruit de fond" à l'échelle d'un hémisphère, et constitue, de ce fait, un terrain privilégié pour appréhender la réponse de l'atmosphère à des phénomènes naturels globaux. Les régions côtières antarctiques sont, elles, particulièrement bien adaptées à l'étude des émissions en provenance de l'océan Austral. Un programme d'étude de la chimie de la troposphère a donc débuté à Dumont d'Urville (66°40' Sud, 140°01Est) fin 1990. Des prélèvements atmosphériques effectués simultanément à Dumont d'Urville et sur une île éloignée de la station ont montré que les activités humaines sur la base n' influençaient pas de manière significative la collecte atmosphérique. En revanche, la présence d'une avifaune abondante perturbe les concentrations atmosphériques en NH3 NH4, C2024 2-, K+, Ca 2+. L'étude des composés soufrés atmosphériques (acide méthanesulfonique et sulfate) a mis en évidence l'existence d'un fractionnement du au gel de l'aérosol marin durant l' hiver. Ce fractionnement se traduit par un déficit de sulfate et une augmentation du rapport Cl -/Na +. Nous avons pu mettre en évidence la présence d'une perturbation en sulfate durant l'été 1991 - 1992 dans la troposphère des régions côtières antarctiques. Cette perturbation est provoquée par la sédimentation du nuage volcanique émis lors de l'éruption du Cerro Hudson (15 août 1991). Par ailleurs, nous avons montré que le cycle saisonnier de ces composés soufrés est corrélé aux variations saisonnières de l'activité phytoplanctonique dans l'Océan Austral. De plus, la variabilité géographique des concentrations atmosphériques peut être expliquée par une différence de productivité entre les différents secteur de l'Océan circumpolaire. Enfin, l'étude des composés azotés atmosphériques (NH4+, HNO3, NO3-) a montré que les valeurs de NH4+ mesurées à Mawson (67.6°S, 62.5°E) sont certainement influencées par l' activité animale. Les variations saisonnières du nitrate atmosphérique peuvent être provoquées par la sédimentation des nuages stratosphériques polaires .

Ammonium in coastal Antarctic aerosol and snow: Role of polar ocean and penguin emissions

Year-round aerosol samples collected in the boundary layer at coastal Antarctic sites (Dumont D'Urville, Neumayer, and Halley) indicate a seasonal cycle of ammonium concentrations with a minimum in winter (April–September). A large intersite difference appears in the summer (November–February) maxima values, from ∼12.5 ng m−3 at Neumayer to 140–230 ng m−3 at Dumont D'Urville. At Dumont D'Urville, ammonium concentrations are the largest ever reported from Antarctic sites, and the large summer maxima are associated with large enrichments with respect to sea salt for potassium and calcium. In addition, seasonal ammonium variations at Dumont D'Urville are in phase with a well-marked seasonal cycle of oxalate concentrations which exhibit maxima of 5–10 ng m−3 in spring and summer and minima of less than 0.5 ng m−3 in winter. Such a composition of aerosols present in the boundary layer at Dumont D'Urville in summer is linked to the presence of a large Adélie penguin population from the end of October to March at the site. Ornithogenic soils (defined as guano-enriched soils), together with the bacterial decomposition of uric acid, are a source of ammonium, oxalate, and cation (such as potassium and calcium) aerosol, in addition to a subsequent large ammonia loss from ornithogenic soils to the atmosphere. The total breeding population of 5 million Adélie penguins widely distributed around the Antarctic continent may emit, at most, some 2.5 × 10−4 Mt of NH3-N during the summer months. In contrast, Halley and Neumayer Stations are far less exposed to penguin colony emissions. At Neumayer, ammonium concentrations peak from January to March and are in phase with the increase of biogenic sulfur species. Here the NH4+/(MSA + nss SO4−) molar ratio is close to 13% in summer aerosol and to 40% in winter aerosol. Using this summer ratio, which may be related to ammonia and sulfur oceanic emissions occurring south of 50°S in summer and estimated DMS emissions in these regions at this time, we derive an upper limit of 0.064 Mt NH3-N emitted per year by the high-latitude Southern Ocean in summer. This study indicates a very limited ammonia neutralization of acidic sulfate aerosols at high southern latitudes, except in the vicinity of ornithogenic soils occupied by large penguin colonies

Sulfur-containing species (sulfate and methanesulfonate) in coastal antarctic aerosol and precipitation

The concentrations of sulfur-containing species (sulfate and methanesulfonate (MSA)) of aerosols collected at three coastal Antarctic sites (Neumayer, Dumont d\u27Urville, and Halley) have been studied in order to investigate the natural sulfur cycle at high southern latitudes. The multiple-year data sets indicate annual mean concentrations of MSA and non-sea-salt (nss) sulfate of 38 and 151 ng m(-3) at Neumayer (1983-1995) and 20 and 147 ng m(-3) at Dumont d\u27Urville (1991-1995). On the basis of the study of a more limited time period (1991 and 1992), the Halley data set indicates significantly lower MSA and nss sulfate concentrations, 15 and 50 ng m(-3), respectiveley. The concentrations of both species exhibit a consistent and strong seasonal cycle with maxima from December to March and minima from May to September (from 2 to 4 and from 17 to 50 ng m(-3), for MSA and nss sulfate, respectively). These data, together with radionuclide studies (Pb-210 and Be-10), indicate that the marine biogenic source dominates the sulfur budget of the boundary layer of these regions throughout the year. The contribution of other sources, such as the long-range transported sulfur from continents and to a lesser extent the stratospheric sulfate reservoir, remains weak when averaged over the year. Differences in the seasonal pattern of the two sulfur-containing species, as well as intersite differences in the summer concentrations, are compared to several factors, mainly the spatial and temporal variations of the chlorophyll content of the surface ocean water and the seasonality of the sea ice cover. This permits investigation of the respective influence of marine regions emitting dimethylsulfide located either near the Antarctic continent (south of 60 degrees S) or at more temperate latitudes. A strong correlation is found between the chlorophyll content of the Antarctic ocean and the level of total nss sulfur. Furthermore, nss sulfate and MSA deposition fluxes determined from firn and ice cores extracted at sites located at various distances from the ocean and various altitudes allow assessment of the spatial variation of the marine biogenic sulfur input in Antarctica

Abordaje del maltrato infantil dentro del núcleo intrafamiliar en la provincia de Chiclayo

TesisLa presente tesis lleva por título “Abordaje del Maltrato Infantil Dentro del Núcleo Intrafamiliar en la Provincia de Chiclayo”; y la razón que nos motivó ha realizar un análisis minucioso de esta problemática es que desde años anteriores ha existido y nos pareció de mucha importancia este problema, ya que la sociedad antiguamente no le daba la debida atención, mas sin embargo ahora en nuestros tiempos ha despertado gran interés en la sociedad ayudar a los niños que han sufrido algún tipo de maltrato. Con el paso del tiempo esta situación ha ido incrementando y la gente no sabe el porqué está sucediendo, por esa razón nos decidimos a investigar este tema ya que vamos a dar a relucir las causas y características que originan estos maltratos y buscar las formas de cómo ayudar a estos niños que han sufrido algún tipo de maltrato. Para poder ahondar nuestra investigación nos trazamos como objetivos: Ubicar, resumir conceptos básicos inherentes a esta problemática; conocer la causa que genera el maltrato infantil; saber qué consecuencias tienen los niños que han sido maltratados en el paso del tiempo en el ámbito psicológico, físico y emocional; dar a conocer algunas instituciones en las que se puede recurrir en busca de ayuda para un niño que ha sido maltratado; dar la iniciativa a fin de que los padres le den una buena educación a sus hijos sin tener que recurrir a la agresión, ya que puede tener consecuencias en el futuro. El uso intencionado de la fuerza física u omisión de cuidado por parte de los padres viene siendo lo que es el maltrato. La mayor parte de los padres que abusan de sus hijos, habían sufrido ellos también la misma situación por parte de sus progenitores. Existen diferentes maneras de cómo se puede maltratar a un infante los cuales pueden ser: física, emocional, psicológica o mental, por abandono o negligencia ó por abuso sexual. Al paso del tiempo el maltrato puede producir consecuencias en el desarrollo del niño una de ellas es que afecta en su crecimiento, en su conducta, también puede causar traumas psicológicos o trastornos mentales. Después de haber sido maltratado un niño puede presentar una serie de conductas como de inferioridad, rechazo, inseguridad y miedo. Esta investigación plantea cuáles son las características del maltrato, cuáles son las consecuencias, así mismo los tipos de maltrato que se dan en los niños, pero también se dará información sobre las instituciones a las cuales se puede acudir para ayudar a los niños maltratados

Impacts environnementaux du PDU nantais 2000-2010 - synthèse des scénarios Eval-PDU

Exemple d'évaluation des impacts environnementaux du PDU 2000-2010 de Nantes Métropole à partir de simulations numériques de scénarios alternatifs sur la période 2002-2008. Le projet Eval-PDU a été consacré au développement et à l'application d'un ensemble de modèles adaptés à l'évaluation des impacts environnementaux (pollution, gaz à effet de serre, bruit) de différentes actions sur les transports et la mobilité urbaine. Un premier modèle sert à analyser les déplacements dans l'agglomération nantaise en fonction de la population et de sa répartition, des lieux d'emploi et d'activité, des voiries et moyens de transport existants. A partir de cette estimation du trafic automobile, un deuxième modèle sert à calculer les émissions de polluants par les Îhicules. Un troisième modèle permet de suivre la dispersion de ces polluants dans l'atmosphère et leur répartition dans l'agglomération. Un quatrième modèle s'intéresse au bruit généré par le trafic et à sa diffusion dans la ville. Pour appliquer la méthode Eval-PDU, plusieurs scénarios ont été élaborés. Tout d'abord deux scénarios historiques ont été choisis s'appuyant sur les situations réelles de l'agglomération nantaise en 2002 et 2008, tant du point de vue des données socio-économiques, de la voirie et des réseaux de transport publics, que des pratiques de déplacement des habitants. Ces deux scénarios ont permis de caler le modèle et de Îrifier que les évolutions constatées entre ces deux dates étaient correctement prises en compte. Des politiques alternatives ont été synthétisées dans trois scénarios et diverses variantes. Quelques résultats marquants de la simulation de ces scénarios par nos modèles sont présentés et discutés ci-dessous. A la lecture de ce document, on gardera à l'esprit les remarques qui précèdent: il s'agit d'éléments d'information pour alimenter le débat sur les politiques de transport et de mobilité en ville, certainement pas de chiffres absolus. Au-delà d'indications globales à l'échelle de l'agglomération, les informations plus locales (quartier ou voie) sont souvent les plus intéressantes

Air pollution modeling and exposure assessment during pregnancy in the French Longitudinal Study of Children (ELFE)

We developed a nation-wide exposure model to NO2, PM10 and PM2.5 at a fine spatial and temporal resolution for France in order to study air pollutants exposure during pregnancy for the French Longitudinal Study of Children (ELFE). The exposure to air pollutants was estimated daily for years 2010 and 2011 by combining three simulation models at the national and regional scale (CHIMERE) and at the local urban scale (ADMS-Urban or SIRANE). The spatial resolution was 4 km for the national scale model, 3–4 km for regional models and from 10 to 200 m for urban-scale models. We developed a confidence index (from 0 to 10) based on the target plot to identify the best model to estimate exposure for a given address, year and pollutant. Air pollution exposure during pregnancy was then estimated using each modeling scale for the 17,427 women participating in the ELFE cohort. We described the exposure of the women during different time windows of pregnancy using each of the three models and using the most suitable model as estimated by the confidence index. The exposure estimates obtained from the three models were quite similar and highly correlated (spearman correlation between 0.64 and 0.96), especially for the national and regional models. For NO2 and PM10 predicted by the urban models, the minimum values were lower and the maximum values and the variability were higher, compared to the regional and national models. The averaged confidence indexes were comprised between 5.6 and 8 depending on the pollutant, year and exposure model considered. The best confidence index was observed for urban modeling (10) and the lowest for the regional modeling (0). In average during pregnancy, using the most suitable model, women were exposed to 21 μg/m3 for NO2, 16 μg/m3 for PM2.5 and 24 μg/m3 for PM10. To our knowledge, this is the first study combining three modeling tools available at different scales to estimate NO2, PM10 and PM2.5 concentrations at a fine spatial and temporal resolution over a large geographical area. The confidence index provides guidance in the choice of the exposure model. These exposure estimates will be used to investigate potential effects of air pollutants on the pregnant woman health and on health of the fetus and development of the child

Maternal Ambient Exposure to Atmospheric Pollutants during Pregnancy and Offspring Term Birth Weight in the Nationwide ELFE Cohort

International audienceBackground: Studies have reported associations between maternal exposure to atmospheric pollution and lower birth weight. However, the evidence is not consistent and uncertainties remain. We used advanced statistical approaches to robustly estimate the association of atmospheric pollutant exposure during specific pregnancy time windows with term birth weight (TBW) in a nationwide study. Methods: Among 13,334 women from the French Longitudinal Study of Children (ELFE) cohort, exposures to PM2.5, PM10 (particles < 2.5 mu m and <10 mu m) and NO2 (nitrogen dioxide) were estimated using a fine spatio-temporal exposure model. We used inverse probability scores and doubly robust methods in generalized additive models accounting for spatial autocorrelation to study the association of such exposures with TBW. Results: First trimester exposures were associated with an increased TBW. Second trimester exposures were associated with a decreased TBW by 17.1 g (95% CI, -26.8, -7.3) and by 18.0 g (-26.6, -9.4) for each 5 mu g/m(3) increase in PM2.5 and PM10, respectively, and by 15.9 g (-27.6, -4.2) for each 10 mu g/m(3) increase in NO2. Third trimester exposures (truncated at 37 gestational weeks) were associated with a decreased TBW by 48.1 g (-58.1, -38.0) for PM2.5, 38.1 g (-46.7, -29.6) for PM10 and 14.7 g (-25.3, -4.0) for NO2. Effects of pollutants on TBW were larger in rural areas. Conclusions: Our results support an adverse effect of air pollutant exposure on TBW. We highlighted a larger effect of air pollutants on TBW among women living in rural areas compared to women living in urban areas