Macrobenthos and multi-molecular markers as indicators of environmental contamination in a South American port (Mar del Plata,Southwest Atlantic)     

Mariano J. Albano  Paulo da Cunha Lana  Claudia Bremec  Rodolfo Elías  César C. Martins  Natalia Venturini  Pablo Muniz  Silvia Rivero  Eduardo A. Vallarino  Sandra Obenat 《Marine pollution bulletin》2013

We evaluated benthic habitat quality along a presumed contamination gradient in the Mar del Plata port (Southwestern Atlantic) by coupling biological and chemical proxies in a multidisciplinary approach. Organic matter and photosynthetic pigment contents were higher in silty-clay bottoms of the inner port sites. Levels of all fecal steroids decreased from the inner sites to the port inlet. High concentrations of coprostanol in the inner sites seemed to derive from a permanent population of sea lions rather than from sewage outfalls due to coprostanol/epicoprostanol ratio (IV) values <2.5. PAHs levels were also higher in the inner sector, related to both biomass combustion and petroleum combustion associated to local marine traffic. High disturbance and low ecological status were reflected in low benthic diversity and high AMBI values in the inner sites.  相似文献   

Study of the structure and kinematics of the NGC 7465/64/63 triplet galaxies     

O. A. Merkulova  G. M. Karataeva  V. A. Yakovleva  A. N. Burenkov 《Astronomy Letters》2012,38(5):290-304

We analyze new observational data obtained at the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences with the multimode SCORPIO instrument and the Multi-Pupil Fiber Spectrograph for the group of galaxies NGC 7465/64/63. For one of the group members (NGC 7465), the presence of a polar ring has been suspected. We have constructed the large-scale brightness distributions, the ionized-gas velocity and velocity dispersion fields for all three galaxies as well as the line-of-sight velocity curves based on emission and absorption lines and the stellar velocity field in the central region for NGC 7465. As a result of our analysis of the data obtained, we have discovered an inner stellar disk (r ?? 0.5 kpc) and a warped gaseous disk in NGC 7465, in addition to the main stellar disk. Based on a joint study of our photometric and spectroscopic data, we have established that NGC 7464 is an irregular IrrI-type galaxy whose structural and kinematic peculiarities most likely resulted from its gravitational interaction with NGC 7465. The velocity field of the ionized gas in NGC 7463 turns out to be typical of barred spiral galaxies, and the warp of the outer parts of its disk could arise from a close encounter with one of the galaxies of the environment.  相似文献   

PGC 60020: a polar-ring galaxy     

O. A. Merkulova  G. M. Karataeva  V. A. Yakovleva  A. N. Burenkov 《Astrophysical Bulletin》2012,67(4):374-384

We present an analysis of new observations of a peculiar galaxy PGC60020, obtained with the 6-m BTA telescope of the SAO RAS with a multimode SCORPIO instrument. The observational data includes direct images in the B, V, R _c photometric bands and long-slit spectra in the red range (the H?? line spectral region). Based on the analysis of these data it was found that PGC60020 belongs to the type of classical polar-ring galaxies. Its main body is an S0 galaxy, around the major axis of which a disk of gas, dust and stars is rotating in the plane inclined at an angle of about 60° to the galactic plane. A loop-shaped structure stretches from the southern part of this disk (possibly, a tidal tail) towards the SDSS J 171745.58+404137.1 galaxy.  相似文献   

Seismic stratigraphical record of Lake Levinson‐Lessing,Taymyr Peninsula: evidence for ice‐sheet dynamics and lake‐level fluctuations since the Early Weichselian     

Elodie Lebas  Sebastian Krastel  Bernd Wagner  Raphael Gromig  Grigory Fedorov  Marlene Baumer  Natalia Kostromina  Haflidi Haflidason 《Boreas: An International Journal of Quaternary Research》2019,48(2):470-487

A multi‐channel, high‐resolution seismic reflection survey using a Micro‐GI airgun was carried out in the framework of the Russian‐German project PLOT (Paleolimnological Transect) on Lake Levinson‐Lessing, Taymyr Peninsula, in 2016. In total, ~70 km of seismic reflection profiles revealed in unprecedented detail the glacial and postglacial sedimentary infill of the lake basin. Five main seismic units have been recognized and interpreted as glacial (Unit V), subglacial and proglacial (Unit IV), marine (Unit III), fluvial‐lacustrine (Unit II) and lacustrine (Unit I) sediments. Of particular significance are imbricated, south‐orientated structures present in the southernmost part of the lake basin within Unit V and a large topographic ridge recognized in front of those structures. We interpret these structures as push moraines and an end moraine, respectively, left by the glacier after its retreat. The depositional pattern of the units above the moraines documents past lake‐level fluctuations. We interpret Unit IV, Unit III and Unit I as highstand deposits, and Unit II as lowstand deposits. Gas‐charged sediments dominate the northern part of the lake basin, whilst they occur only sporadically and in limited spatial extent in the central and southern parts of the lake. In the latter areas, the seismic and echo‐sounder data suggest recent tectonic activity. Our study contributes to the reconstruction of environmental conditions in the Taymyr Peninsula directly following the Early Weichselian deglaciation and shows that deep tectonic lake basins affected by several glaciations can preserve important palaeoenvironmental records, which contributes significantly to our understanding of palaeoenvironmental changes in the Taymyr Peninsula and the central Russian Arctic.  相似文献   

Surface moisture area during rainfall–run‐off events to understand the hydrological dynamics of a basin in a plain region          下载免费PDF全文

María Guadalupe Ares  Mauro Holzman  Ilda Entraigas  Marcelo Varni  Luisa Fajardo  Natalia Vercelli 《水文研究》2018,32(10):1351-1362

The understanding of the hydrology of plain basins may be improved by the combined analysis of rainfall–run‐off records and remote sensed surface moisture data. Our work evaluates the surface moisture area (SMA) produced during rainfall–run‐off events in a plain watershed of the Argentine Pampas Region, and studies which hydrological variables are related to the generated SMA. The study area is located in the upper and middle basins of the Del Azul stream, characterized by the presence of small gently hilly areas surrounded by flat landscapes. Data from 9 rainfall–run‐off events were analysed. MODIS surface reflectance data were processed to calculate SMA subsequent to the peak discharge (post‐SMA), and previous to the rainfall events (prev‐SMA), to consider the antecedent wetness. Rainfall–run‐off data included total precipitation depth (P), maximum intensity of rainfall over 6 hr (I6max), surface run‐off registered between the beginning of the event and the day previous to the analysed MODIS scene (R), peak flow (Qp), and flood intensity (IF). In contrast with other works, post‐SMA showed a negative relationship with the R. Three groups of cases were identified: (a) Events of low I6max, high prev‐SMA, and low R were associated with slow and weakly channelized flow over plain areas, leading to saturated overland flow (SOF), with large SMA; (b) events of high I6max, low prev‐SMA, and medium to high R were rapidly transported along the gentle slopes of the basin, related to Hortonian overland flow (HOF) and low post‐SMA; and (c) events of medium to high I6max and prev‐SMA with medium R were related to heterogeneous input‐antecedent‐run‐off conditions combined: Local spatial conditions may have produced HOF or SOF, leading to an averaged response with medium SMA. The interactions between the geomorphology of the basin, the characteristics of the events, and the antecedent conditions may explain the obtained results. This analysis is relevant for the general knowledge of the hydrology of large plains, whose functioning studies are still in their early stages.  相似文献   

Andesitic Plinian eruptions at Mt. Ruapehu: quantifying the uppermost limits of eruptive parameters     

Natalia Pardo  Shane Cronin  Alan Palmer  Jonathan Procter  Ian Smith 《Bulletin of Volcanology》2012,74(5):1161-1185

New tephro-stratigraphic studies of the Tongariro Volcanic Centre (TgVC) on the North Island (New Zealand) allowed reconstruction of some of the largest, andesitic, explosive eruptions of Mt. Ruapehu. Large eruptions were common in the Late Pleistocene, before a transition to strombolian-vulcanian and phreatomagmatic eruptive styles that have predominated over the past 10,000?years. Considering this is the most active volcano in North Island of New Zealand and the uppermost hazard limits are unknown, we identified and mapped the pyroclastic deposits corresponding to the five largest eruptions since ~27?ka. The selected eruptive units are also characterised by distinctive lithofacies associations correlated to different behaviours of the eruptive column. In addition, we clarify the source of the ~10–9.7?ka Pahoka Tephra, identified by previous authors as the product of one of the largest eruptions of the TgVC. The most common explosive eruptions taking place between ~13.6 and ~10?ka?cal?years BP involved strongly oscillating, partially collapsing eruptive columns up to 37?km high, at mass discharge rates up to 6?×?10⁸?kg/s and magnitudes of 4.9, ejecting minimum estimated volumes of 0.6?km³. Our results indicate that this volcano (as well as the neighbouring andesitic Mt. Tongariro) can generate Plinian eruptions similar in magnitude to the Chaitén 2008 and Askja 1875 events. Such eruptions would mainly produce pyroclastic fallout covering a minimum area of 1,700?km² ESE of the volcano, where important touristic, agricultural and military activities are based. As for the 1995/1996 eruption, our field data indicate that complex wind patterns were critical in controlling the dispersion of the eruptive clouds, developing sheared, commonly bilobate plumes.  相似文献   

Late Permian palaeomagnetic data east and west of the Urals     

Mikhail L. Bazhenov  Alexander N. Grishanov  Rob Van der Voo  Natalia M. Levashova 《Geophysical Journal International》2008,173(2):395-408

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Fog Events at Maceio Airport on the Northern Coast of Brazil During 2002–2005 and 2007     

Natalia Fedorova  Vladimir Levit  José Leonaldo de Souza  Aliton Oliveira Silva  Joao M. Sousa Afonso  Iedo Teodoro 《Pure and Applied Geophysics》2015,172(10):2727-2749

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Influence of High Energy Electromagnetic Pulses on the Dynamics of the Seismic Process Around the Bishkek Test Area (Central Asia)     

Teimuraz N. Matcharashvili  Tamaz L. Chelidze  Natalia N. Zhukova 《Pure and Applied Geophysics》2015,172(7):1893-1908

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Aerosol Measurements in the Atmospheric Surface Layer at L’Aquila,Italy: Focus on Biogenic Primary Particles     

Giovanni Pitari  Eleonora Coppari  Natalia De Luca  Piero Di Carlo  Loretta Pace 《Pure and Applied Geophysics》2014,171(9):2425-2441

Two year measurements of aerosol concentration and size distribution (0.25 μm < d < 30 μm) in the atmospheric surface layer, collected in L’Aquila (Italy) with an optical particle counter, are reported and analysed for the different modes of the particle size distribution. A different seasonal behaviour is shown for fine mode aerosols (largely produced by anthropogenic combustion), coarse mode and large-sized aerosols, whose abundance is regulated not only by anthropogenic local production, but also by remote natural sources (via large scale atmospheric transport) and by local sources of primary biogenic aerosols. The observed total abundance of large particles with diameter larger than 10 μm is compared with a statistical counting of primary biogenic particles, made with an independent technique. Results of these two observational approaches are analysed and compared to each other, with the help of a box model driven by observed meteorological parameters and validated with measurements of fine and coarse mode aerosols and of an atmospheric primary pollutant of anthropogenic origin (NO_x). Except in winter months, primary biogenic particles in the L’Aquila measurement site are shown to dominate the atmospheric boundary layer population of large aerosol particles with diameter larger than 10 μm (about 80 % of the total during summer months), with a pronounced seasonal cycle, contrary to fine mode aerosols of anthropogenic origin. In order to explain these findings, the main mechanisms controlling the abundance and variability of particulate matter tracers in the atmospheric surface layer are analysed with the numerical box-model.  相似文献