Polycyclic aromatic hydrocarbons in a small eastern siberian river: sources,delivery pathways,and behavior     

Mikhail Yu Semenov  Irina I. Marinaite  Nadezhda V. Bashenkhaeva  Natalia A. Zhuchenko  Olga I. Khuriganova  Elena V. Molozhnikova 《Environmental Earth Sciences》2016,75(11):954

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Geochemical mobility of arsenic in the surficial waters from Argentina     

Alicia Daniela Robles  Paula Polizzi  María Belén Romero  Leila Natalia Chiodi Boudet  Sandra Medici  Agustín Costas  Marcela Gerpe 《Environmental Earth Sciences》2016,75(23):1479

The presence of arsenic (As) in surface water constitutes an important environmental risk, where mobility and adsorption processes are responsible for its behavior in the sediment–water interface. Therefore, the assessment of adsorption, mobility and water availability of arsenic in freshwater sediments, with agricultural, livestock and urban soil uses was performed. Arsenic concentrations in sediments ranged from 5.4 to 15.9 mg kg^?1 (total) and 2.8 to 6.5 mg kg^?1 (labile), and those of iron and manganese were 11,563–23,500 and 140.6–662.1 mg kg^?1, respectively. The As levels in water were significantly lower than those of sediments. Results would suggest that As co-precipitation and adsorption on Fe oxides are probably the major route of immobilization, determining its low lability. Manganese did not present an outstanding contribution to the retention, and cation-exchange capacity, pH and organic matter of sediments did not show an influence on the mobility of As.  相似文献   

Seasonal and inter-annual dynamics of mesoplankton in the northwestern Japan Sea     

Natalia T. Dolganova  Yury I. Zuenko 《Progress in Oceanography》2004,61(2-4):227

Based upon four decades of observations in the northwestern part of the Japan Sea, the seasonal and inter-annual variations of zooplankton abundance and species composition in the epipelagic layer are considered. Seasonal characteristics of the zooplankton community are described in detail for five domains that occur within this part of the Japan Sea. Inter-decadal variation was not significant, but inter-annual variation was considerable and generally opposite to water temperature changes in the upper layer. Exceptional years such as 1996 were noted when a maximum abundance of zooplankton in summer occurred along with a slowing of the seasonal pattern of succession.  相似文献   

Mobilization of metals from riverine suspended matter in seawater   总被引：1，自引：0，他引：1  

Vladimir M. Shulkin  Natalia N. Bogdanova 《Marine Chemistry》2003,83(3-4):157

Suspended matter from rivers in the Russian Far East was leached by seawater to assess the extent of Zn, Cd, Pb, and Cu release from the land-derived solids to estuarine and coastal waters. The concentration of solids in the leaching experiments was 0.25 g/l. The suspended matter used varied in metal content from background levels to heavily contaminated.The concentration of Zn, Cd, Pb, and Cu in the leaching solution after 1, 4, 24, 48, and 96 h was determined by anodic stripping voltammetry. Measurable Cd was transferred from river suspended matter to seawater with both background and elevated Cd concentrations, though the amount of Cd released was different. The increase in Zn and Pb in solution was observed only at the enriched concentration of metals in the suspended solids. The Cu transfer into solution was more pronounced from material with elevated Cu concentration, but the amount of degradable organic matter in the solid phase was more important.The losses of metals from the riverine solids varied from 60% to 80% of total concentration for Cd to negligible for Pb, independent of contamination. The Zn loss depended on the initial concentration in the solids and decreased from 11–16% for the heavily contaminated suspended matter to 3–8% for the moderately enriched ones and to negligible for the pristine solids. Cu loss varied from 1% to 30% of total content, with no clear dependence on concentration in the suspended matter.The significance of additional input of dissolved metals to estuarine and coastal waters from remobilization was assessed by comparison with the initial concentration of dissolved metals in river water. Such experiments could be used to assess the water quality impact of atmospheric fallout of contaminated solids and storm drainage from the urbanized areas, in addition to river suspended matter studies.  相似文献   

Water exchange and water quality in the coastal zone in the presence of structures     

Izmail Kantardgi  Felix Mairanovsky  Natalia Sapova 《Coastal Engineering》1995,26(3-4)

The water exchange and water quality around coastal structures are considered by analytical, numerical and experimental methods. Water exchange for a small yacht harbour at the Black Sea coast is discussed as an application example. Physical and numerical experiments were carried out to determine the wave induced current field and to correlate the water exchange inside the area around the harbour mole. A hydraulic approach was applied to estimate the water exchange intensities for typical zones. The proposed mathematical model is an irregular wave-current model which includes the interaction between waves and current and a modified breaking criterion. The evolution of salinity concentration during the experimental investigations shows the water exchange intensity. A satisfactory agreement between calculated and measured concentration evolution was obtained.  相似文献   

Semiconductors exposed to oils in pressure-tolerant electronic systems     

Daniel E. Gilbert  John R. Hauser  James W. Harrison  Jimmie J. Wortman 《Ocean Engineering》1974,2(6):265-273

The present study indicates that most semiconductor components are fabricated such that they are not affected by operation in a dielectric oil environment. A quantitative estimate of the conditions under which oil-soluble ions will invert semiconductor surfaces and interfere with proper device operation is developed. The results are discussed in terms of pressure-tolerant electronic systems—solid-state components operated immersed in chemically inert dielectric oils when these components are subject to, and experience, ambient hydrostatic pressures of the ocean depths. The feasibility of pressure-tolerant electronic systems is demonstrated.  相似文献   

On the echo interference in sound backscattering by densely aggregated targets     

Gorska  Natalia; Chu  Dezhang 《ICES Journal of Marine Science》2005,62(4):771-778

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Origin of components in Chilean thermal waters     

François Risacher  Bertrand Fritz  Arturo Hauser 《Journal of South American Earth Sciences》2011,31(1):153-170

Thermal waters of northern (18°–27°S) and southern (37°–45°S) Chile occur in two very different climatic, geologic and hydrologic environments: arid closed basins with abundant evaporites in the north; humid climate and well drained valleys in the south. The origin and behavior of the main components of the two groups of waters are examined and compared to each other. The modeling of the alteration of volcanic rocks leads to water compositions very different from those observed both in the north and south. In addition to hydrothermal alteration and deep emanations, the Cl/Br ratio reveals a major contribution of saline waters to the two groups: infiltrating brines from salt lakes in the north; seawater in the south.In the north, concentrations of Cl, Br, Na, K, Ca, SO₄, Li, B, Si result from the mixing of alteration waters with recycled brines. Hydrothermal alteration is obscured by this massive saline input, except for Mg. δ³⁴S values are consistent with an origin of sulfate from salar brines, which are themselves derived from deep Tertiary gypsum. In the south, two processes account for the composition of thermal waters: mixing of alteration waters with seawater and deep magmatic contribution. The mixing process controls the concentration of Cl, Br, Na, Alk, Si, K, Ca, Mg. Magmatic inputs are detectable for SO₄, Li and B. δ³⁴S suggests that sulfate stems from the mixing of alteration waters with either marine SO₄ in coastal waters or with deep SO₂ in inland waters. In both the north and south, the Mg concentration is drastically lowered (<1 μmol/L) by the probable formation of a chlorite-type mineral. In the south, very small amounts of seawater (<1% in volume) are sufficient to imprint a clear signature on thermal waters. Not only coastal springs are affected by seawater mixing, but also remote inland springs, as far as 150 km from the sea. Subduction of marine sediments in the accretive margin could be the source of the marine imprint in thermal waters of southern Chile. Seawater may be expelled from the subducted lithosphere and incorporated into the mantle source.  相似文献   

Ejection of Martian meteorites     

Jrg Fritz  Natalia Artemieva  Ansgar Greshake 《Meteoritics & planetary science》2005,40(9-10):1393-1411

Abstract— We investigated the transfer of meteorites from Mars to Earth with a combined mineralogical and numerical approach. We used quantitative shock pressure barometry and thermodynamic calculations of post‐shock temperatures to constrain the pressure/temperature conditions for the ejection of Martian meteorites. The results show that shock pressures allowing the ejection of Martian meteorites range from 5 to 55 GPa, with corresponding post‐shock temperature elevations of 10 to about 1000 °C. With respect to shock pressures and post‐shock temperatures, an ejection of potentially viable organisms in Martian surface rocks seems possible. A calculation of the cooling time in space for the most highly shocked Martian meteorite Allan Hills (ALH) 77005 was performed and yielded a best‐fit for a post‐shock temperature of 1000 °C and a meteoroid size of 0.4 to 0.6 m. The final burial depths of the sub‐volcanic to volcanic Martian rocks as indicated by textures and mineral compositions of meteorites are in good agreement with the postulated size of the potential source region for Martian meteorites during the impact of a small projectile (200 m), as defined by numerical modeling (Artemieva and Ivanov 2004). A comparison of shock pressures and ejection and terrestrial ages indicates that, on average, highly shocked fragments reach Earth‐crossing orbits faster than weakly shocked fragments. If climatic changes on Mars have a significant influence on the atmospheric pressure, they could account for the increase of recorded ejection events of Martian meteorites in the last 5 Ma.  相似文献   

Linking soil water balance with flood spatial arrangement in an extremely flat landscape     

Natalia Vercelli  Marcelo Varni  Bruno Lara  Ilda Entraigas  María Guadalupe Ares 《水文研究》2020,34(1):21-32

In areas with very mild relief, water drains in a disordered way due to the lack of a developed drainage network, as it occurs in extremely flat sedimentary regions like the Argentine Pampas. The study analysed the flood spatial arrangements in 2014 by calculating landscape metrics and relating them to soil water balance. The study area is located at Del Azul creek lower basin (Pampa Ecoregion, Argentina). Daily soil water balances were obtained, and seven landscape metrics were calculated in 15 windows in five LandSat images, all along 2014, to explore the relationship between hydrological scenarios and spatial pattern summarized with principal component analysis. Water excess concentrated in winter (June and August); deficits were in late spring and summer (January and November), whereas the beginning of autumn (March) was an intermediate situation. Principal component 1 (44.7%) reflected area and shape metrics and correlated positively with water table level; principal component 2 (32.3%) summarized aggregation ones and was negatively associated with accumulated water excesses or deficits in previous 30 days and useful reserve. Both exhibited possible threshold-driven behaviour. Internal heterogeneity between NW and SE zones within the study area coincided with the existence of ancient alluvial fans. The results highlight the peculiarities of the flood spatial patterns in regions with very mild relief, where landforms usually determine water flows.  相似文献