Evidence for an Unrecognized Secondary Anthropogenic Source of Organosulfates and Sulfonates: Gas-Phase Oxidation of Polycyclic Aromatic Hydrocarbons in the Presence of Sulfate Aerosol
In the present study, formation of aromatic organosulfates (OSs) from the photo-oxidation of polycyclic aromatic hydrocarbons (PAHs) was investigated. Naphthalene (NAP) and 2-methylnaphthalene (2-MeNAP), two of the most abundant gas-phase PAHs and thought to represent “missing” sources of urban SOA, were photochemically oxidized in an outdoor smog chamber facility in the presence of nonacidified and acidified sulfate seed aerosol. Effects of seed aerosol composition, acidity and relative humidity on OS formation were examined. Chemical characterization of SOA extracts by ultra performance liquid chromatography coupled to electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry revealed the formation of OSs and sulfonates from photo-oxidation in the presence of sulfate seed aerosol. Many of the organosulfur compounds identified in the smog chamber extracts were also measured in urban fine aerosol collected at Lahore, Pakistan, and Pasadena, USA, demonstrating that PAH photo-oxidation in the presence of sulfate aerosol is a hitherto unrecognized source of anthropogenic secondary organosulfur compounds, and providing new PAH SOA tracers.
(Environmental Science and Technology. vol. 49, n° 0013-936X, pp. 6654-6664, 12/05/2015)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
On The Impact of a Series of Severe Storms on a Double-Barred Sandy Coast: Dune Erosion and Megacups Embayments
The winter of 2013/2014 was outstanding in terms of the available energy to move sediment and caused large-scale unprecedented erosion of the Gironde coast (France), comprising the onset of megacusp embayments cutting the dune with a typical alongshore and cross-shore lengthscale of O (100 m) and O(10 m), and a dune erosion scarp height often exceeding 10 m. Megacusps are found to be coupled to the outer crescentic sandbar and triggered by the outstandingly high-energy, long-period and normally-incident storm wave event Hercules on January 6-7. Our observations indicate that both the antecedent outer sandbar morphology and storm wave characteristics, including period and angle of incidence, govern patterns of beach and dune erosion along open multiple-barred sandy coasts during severe storms.
(11/05/2015)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, WRL, UNSW, BRGM, OASU, UB, INSU - CNRS, ULR, CNRS, INRAE
Trilobites and inarticulate brachiopods from the Devonian Floresta Formation of Colombia: a review
The study of Devonian Colombian trilobites and inarticulate brachiopods allows to recognize two biostratigraphic levels within the Floresta Formation. The first level, in the lower part of the formation, is late Emsian in age, and yields 14 distinct trilobite taxa, including Colombianaspis carvalhoae gen. et sp. nov. The second one, in the upper part of the formation, is assigned to the Givetian based on the co-occurrence of the genera Dipleura and Greenops; this is the first record of a Givetian age for the upper part of the Floresta Formation. The inarticulate brachiopods collected from the uppermost part of the formation suggest a Givetian age. Inarticulate brachiopods as well as the trilobites show close affinities with the North Eastern Americas Realm, but they also suggest European affinities. The late Emsian occurrence of calmoniids from Colombia is indicative of restricted faunal exchanges with the Malvinokaffric Realm.
(Bulletin of Geosciences. vol. 90, n° 1214-1119, pp. 331-358, 01/05/2015)
UNAL, CR2P, MNHN, UPMC, CNRS, LDO, INSU - CNRS, UBO EPE, CNRS
Atmospheric particulate mercury in the megacity Beijing: Spatio-temporal variations and source apportionment
Particulate mercury (HgP) concentrations in weekly aerosol samples (PM2.5 and TSP) from Beijing, China, were measured for a complete year. In addition, spatial differences were measured for a shorter time period at four different sites and potential source materials were analyzed. Average HgP concentrations in PM2.5 samples were 0.26 ng/m3 for day-time PM2.5, 0.28 ng/m3 for night-time PM2.5, and 0.57 ng/m3 for TSP samples, respectively. Coal combustion was identified as the major source of HgP in Beijing. Other sources included industrial activities as well as red color on historical buildings as a minor contribution. Spatial differences were pronounced with highest concentrations in the inner city (inside the 3rd ring road). The results further showed a strong seasonality with highest concentrations in winter and lowest in summer due to local meteorological conditions (precipitation in summer and stagnant conditions and low mixing layer height in winter) as well as seasonal sources, such as coal combustion for heating purposes. Day–night differences also showed a seasonal pattern with higher night-time concentrations during summer and higher day-time concentrations during winter. Compared to other cities worldwide, the HgP concentrations in Beijing were alarmingly high, suggesting that airborne particulate Hg should be the focus of future monitoring activities and mitigation measures.
(Atmospheric Environment. vol. 109, n° 1352-2310, pp. 251-261, 01/05/2015)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
When deep diagenesis in Arctic Ocean sediments compromises manganese-based geochronology
We used a diagenetic model to test the hypothesis that manganese-rich layers in gas hydrate-bearing Arctic Ocean sediments are reliable time markers for interglacial periods. In the model, diagenesis is fuelled by two sources of reactive carbon: particulate organic carbon settling to the sediment surface, and methane diffusing up from deep gas hydrate deposits. The model includes oxidation of organic carbon and soluble reduced manganese by oxygen supplied continuously from an invariant bottom-water oxygen reservoir; reduction of particulate manganese by hydrogen sulfide generated through anaerobic methane oxidation; transport of dissolved oxygen and manganese by diffusion; and advective transport of particulate components by burial. Particulate organic matter and particulate manganese are only supplied to the sediment during interglacials. Sulfate reduction is not modeled explicitly; instead, the effect of anaerobic methane oxidation on Mn reduction is simulated at the lower boundary of the model by prescribing that particulate manganese is reduced there to soluble Mn(II). The soluble reduced Mn then diffuses upward and is oxidatively precipitated to Mn(IV) by downward diffusing oxygen. The upward flux of soluble Mn(II) is thus a function of the rate at which particulate manganese is advected into the Mn-reduction layer at the bottom of the model; it is not synchronous with events at the sediment–water interface. Model runs reveal that, under idealized but realistic conditions for the Arctic Ocean, oxidation of upward-diffusing Mn(II) generates post-depositional manganese enrichments that cannot readily be distinguished from the manganese-rich sediment layers that accumulate during interglacials. This compromises the use of manganese-rich layers as proxies for interglacial periods. In contrast, manganese-rich layers may be used as first-order markers of interglacial periods in sediments where gas hydrates or other forms of reactive carbon are absent.
(Marine Geology. vol. 366, n° 0025-3227, pp. 62-68, 27/04/2015)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Oceanography: Fresh news from the Atlantic
The Atlantic overturning circulation plays a key role in large-scale climate but how it varies is not well known. Now a study proposes that the weakening it may have experienced in the late 1970s is unprecedented over the last millennium.
(Nature Climate Change. vol. 5, n° 1758-678X, pp. 411-412, 23/04/2015)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Photochemical Aging of Secondary Organic Aerosols Generated from the Photooxidation of Polycyclic Aromatic Hydrocarbons in the Gas-Phase
Aging processes of secondary organic aerosol (SOA) may be a source of oxygenated organic aerosols; however the chemical processes involved remain unclear. In this study we investigate photochemical aging of SOA produced by the gas-phase oxidation of naphthalene by hydroxyl radicals and acenaphthylene by ozone. We monitored the SOA composition using a high-resolution time-of-flight aerosol mass spectrometer (HR-AMS). We initiated SOA aging with UV photolysis alone and with OH radicals in the presence or absence of light and at different NOx levels. For naphthalene, the organic composition of the particulate phase seems to be dominated by highly oxidized compounds such as carboxylic acids, and aging data may be consistent with diffusion limitations. For acenaphthylene, the fate of oxidized products and the moderately oxidized aerosol seem to indicate that functionalization reactions might be the main aging process were initiated by the cumulative effect of light and OH radicals.
(Environmental Science and Technology. vol. 49, n° 0013-936X, pp. 5407-5416, 22/04/2015)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Mercurial exposure of residents of Santarém and Oriximiná cities (Pará, Brazil) through fish consumption
A survey of the mercurial exposure of residents of Santarém and Oriximiná showed a differential mercurial impregnation between men and women. At the level of both cities, the mean hair mercury concentrations were 1.5 ± 0.5 (90th and 95th percentiles: 2.8 and 4.3) and 2.52 ± 0.09 μg g Hg/g (90th and 95th percentiles: 4.7 and 8.1) for women and men, respectively. The mercurial contamination appeared significantly closely linked to the daily amount of consumed fish. Carnivore species pescada branca (Plagioscion squamosissimus) and apapá (Pellona castelnaeana) and non-carnivore species pacú (Mylossoma duriventre) and aracú (Schizodon fasciatus) were consumed by 22, 19, 55 and 25 % of people, respectively, and the mean mercury concentrations within fish flesh were 1.44 ± 0.11, 1.66 ± 0.19, 0.48 ± 0.09 and 0.49 ± 0.06 μg/g dry weight, respectively. Men aged above 35 were significantly more contaminated than those below. The mean hair concentrations of men were 5.20 ± 1.25 and 1.50 ± 0.22 μg/g, for those aged above 35 and below, respectively. The probability for women of childbearing age from both cities to present a hair mercury concentration above 1 μg Hg/g (corresponding to the US Environmental Protection Agency reference dose) was equal to 0.30 (95 % confidence interval of 0.24-0.36). The probability of hair mercury concentration to be above the lowest observable adverse effect level (LOAEL) (0.3 μg Hg/g) was equal to 0.79 (95 % confidence interval: 0.73-0.86).
(Environmental Science and Pollution Research. vol. 22, n° 0944-1344, pp. 12150-12161, 18/04/2015)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Développement et applications de l'analyse dirigée par l'effet pour la recherche et l'identification de contaminants à risque pour les écosystèmes aquatiques
Les méthodes actuellement disponibles pour la surveillance de la qualité du milieu se réfèrent au suivi de composés définis par les réglementations et ne permettent pas d’appréhender l’(éco)toxicité réelle de tous les composés présents dans l’environnement (e.g. composés inconnus, produits de transformation, effets de mélange…). Dans ce contexte, une méthode d’analyse pluridisciplinaire intégrative, l’analyse dirigée par l’effet (EDA), a été développée. Cette approche bio-analytique vise à établir un lien de causalité entre une exposition aux contaminants et l’effet biologique observé. La démarche est basée sur la simplification séquentielle d’un échantillon guidée par les bio-essais afin d’individualiser puis identifier, par des techniques analytiques chimiques performantes, les composés biologiquement actifs. Les objectifs de cette thèse ont porté sur (1) le développement et la validation d’une méthodologie, allant du pré-traitement jusqu’au fractionnement, adaptée à différentes matrices environnementales ; (2) la mise en place d’une stratégie d’identification moléculaire par spectrométrie de masse haute résolution ; (3) l’application de la démarche EDA à plusieurs échantillons afin d’illustrer l’adaptabilité et l’apport d’une telle méthode à des problématiques environnementales. Ces travaux de thèse permettent de disposer aujourd’hui d’une démarche bio-analytique complète de la préparation d’échantillon à l’identification de molécules, et adaptée à tous types d’échantillons. Les différentes études environnementales réalisées au cours de ces travaux ont permis, entre autre, d’établir une liste de composés diverses non recherchés pouvant représenter un risque pour l’environnement.
(10/04/2015)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Submarine Earthquake History of the Çınarcık Segment of the North Anatolian Fault in the Marmara Sea, Turkey
The North Anatolian fault (NAF) in the Marmara Sea is a significant hazard for the city of Istanbul. The use of paleoseismological data to provide an accurate seismic risk assessment for the area is constrained by the fact that the NAF system is submarine; thus a history of paleoearthquakes can be inferred only by using marine sediment cores. Here, a record of turbidites was obtained in two cores and used to reconstruct the earthquake history along the Çınarcık segment, a main branch of the NAF. Klg04 was collected from a berm north of the fault, and Klg03 was positioned in the Çınarcık basin, south of the fault. The cores were correlated using long-term geo-chemical variations in the sediment, and turbidites deposited simultaneously at both sites were then identified. Radionuclide measurements suggest the most recent turbi-dite was triggered by the 1894 C.E. M w 7.3 earthquake. We conclude that the turbidites identified at both sites are earthquake generated, based on their particular sedimento-logical and geochemical signatures; the correlation of turbidites at berm and basin sites; and the match of the most recent turbidite with a nineteenth century historical earthquake. To date older turbidites, we used carbon-14 and paleomagnetic data to build an OxCal model with a local reservoir correction of 400 50 yr. The Çınarcık segment is found to have ruptured in 1509 C.E., sometime in the fourteenth century, in 989 C.E., and in 740 C.E., with a mean recurrence interval in the range of 256–321 years. Finally, we used the earthquake record obtained to review the rupture history of the adjacent segments over the past 1500 years.
(Bulletin of the Seismological Society of America. vol. 105, n° 0037-1106, pp. 622-645, 01/04/2015)
LGENS, INSU - CNRS, CNRS, ENS-PSL, PSL, LDEO, ULiège, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IPGP, INSU - CNRS, UPD7, UR, IPG Paris, CNRS, AGEs, ULiège