Water Dynamics and Structure in the Estuary of the Partizanskaya River (Nakhodka Bay,Sea of Japan)     

Semkin  P. Yu.  Tishchenko  P. Ya.  Lobanov  V. B.  Sergeev  A. F.  Barabanshchikov  Yu. A.  Mikhailik  T. A.  Pavlova  G. Yu.  Kostyleva  A. V.  Shkirnikova  E. M.  Tishchenko  P. P.  Chizhova  T. L. 《Water Resources》2019,46(1):29-38

Water Resources - Field studies of the seasonal and daily dynamics of the mixing zone were carried out in the microtidal estuary of the Partizanskaya River. The position of the mixing zone was...  相似文献   

Formation mechanisms of the midlatitudinal <Emphasis Type="Italic">NmF2</Emphasis> semiannual anomaly under daytime quiet geomagnetic conditions at low solar activity     

A. V. Pavlov  N. M. Pavlova 《Geomagnetism and Aeronomy》2017,57(4):406-413

The F-region peak electron densities NmF2 measured during daytime quiet geomagnetic conditions at low solar activity on January 22, 2008, April 8, 1997, July 12, 1986, and October 26, 1995, are compared. Ionospheric parameters are measured by the ionosonde and incoherent scatter radar at Millstone Hill and calculated with the use of a 1D nonstationary ionosphere–plasmasphere model of number densities and temperatures of electrons and ions at middle geomagnetic latitudes. The formation of the semiannual anomaly of the midlatitudinal NmF2 under daytime quiet geomagnetic conditions at low solar activity is studied. The study shows that the semiannual NmF2 anomaly occurs due to the total impact of three main causes: seasonal variations in the velocity of plasma drift along the geomagnetic field due to the corresponding variations in the components of the neutral wind velocity; seasonal variations in the composition and temperature of the neutral atmosphere; and the dependence of the solar zenith angle on a number of the day in the year at the same solar local time.  相似文献   

Timing,magnitude and geochemistry of major Southeast Asian volcanic eruptions: identifying tephrochronologic markers     

Caroline Bouvet De Maisonneuve  Olga Bergal-Kuvikas 《第四纪科学杂志》2020,35(1-2):272-287

We review the current knowledge about Southeast Asian volcanoes and their eruption histories, and focus on identifying tephrochronologic markers representing major explosive eruptions in order to further future palaeoclimate and volcanological studies. Forty-one volcanic edifices in Southeast Asia have been classified as large calderas by Whelley et al. (2015) and thus have, or are likely to have, produced large explosive eruptions with a Volcanic Explosivity Index (VEI) of 6–8. Unfortunately, only 20 such eruptions have known ages, spanning from 1.2 Ma to 1991 ad , and fewer have geochemical data that can be used for tephrostratigraphic correlations. Volcanic products from different geodynamic regions and different sources can generally be distinguished on major element plots (e.g. K₂O versus CaO) of matrix glass composition. However, the distinction of multiple eruptions from the same source often requires additional data such as trace element compositions of matrix glass and/or mineral compositions. Biotite, but also magnetite compositions (MgO and TiO₂ content in particular) appear to be very discriminating. Up to nine tuffs in addition to the three to four Toba tuffs can be utilised as widespread tephrochronologic markers and span a range from 1.2 to 1.6 Ma to recent. As only a few Holocene major eruptions have been well characterised and dated, many large calderas are still unstudied, and many distal tephra layers are still lacking a source, more tephrochronologic markers can certainly be defined in the future.  相似文献   

The Varvarinskoye Complex Copper–Gold Deposit in Northern Kazakhstan: Mineral Types and Ore Composition     

Antonenko  A. A.  Zhukov  N. M.  Pavlova  Z. N.  Goikolova  T. V. 《Geology of Ore Deposits》2020,62(4):314-331

Geology of Ore Deposits - The Varvarinskoye copper–gold deposit, large in terms of Au and small in terms of Cu, was discovered in 1979 in the western part of the Torgai trough in Kazakhstan....  相似文献   

Large‐scale regional delineation of riparian vegetation in the arid and semi‐arid Pilbara region,WA          下载免费PDF全文

Masoomeh Alaibakhsh  Irina Emelyanova  Olga Barron  Mehdi Khiadani  Garth Warren 《水文研究》2017,31(24):4269-4281

Multiscene Landsat 5 TM imagery, Principal Component Analysis, and the Normalized Difference Vegetation Index were used to produce the first region‐scale map of riparian vegetation for the Pilbara (230,000 km²), Western Australia. Riparian vegetation is an environmentally important habitat in the arid and desert climate of the Pilbara. These habitats are supported by infrequent flow events and in some locations by groundwater discharge. Our analysis suggests that riparian vegetation covers less than 4% of the Pilbara region, whereas almost 10.5% of this area is composed of groundwater dependent vegetation (GDV). GDV is often associated with open water (river pools), providing refugia for a variety of species. GDV has an extremely high ecological value and are often important Indigenous sites. This paper demonstrates how Landsat data calibrated to Top of Atmosphere reflectance can be used to delineate riparian vegetation across 16 Landsat scenes and two Universal Transverse Mercator spatial zones. The proposed method is able to delineate riparian vegetation and GDV, without the need for Bidirectional Reflectance Distribution Function correction. Results were validated using ground truth data from local and regional scale vegetation surveys.  相似文献   

Observations on a solar saltworks near Burgas, Bulgaria     

Penka Pavlova  Kostadinka Markova  Stephan Tanev  Joseph S. Davis 《International Journal of Salt Lake Research》1998,7(4):357-368

Data on biota and nutrients in solar ponds of a saltworks near Burgas, Bulgaria, were obtained. Surveys of the biota were undertaken, and records from management officials gave information on biological and physical conditions related to salt production. The decrease in the quality and quantity of sodium chloride harvested that began 10 to 15 years before the study, may be related to the high levels of plankton, combined nitrogen and phosphate, and the large accretion of bottom sediments and density of benthic communities. Biological management can improve the quality and quantity of the sodium chloride produced by the saltworks.  相似文献   

The Project for Intercomparison of Land-surface Parameterization Schemes (PILPS) phase 2(c) Red-Arkansas River basin experiment:: 2. Spatial and temporal analysis of energy fluxes   总被引：3，自引：0，他引：3  

Xu Liang  Eric F. Wood  Dennis P. Lettenmaier  Dag Lohmann  Aaron Boone  Sam Chang  Fei Chen  Yongjiu Dai  Carl Desborough  Robert E. Dickinson  Qingyun Duan  Michael Ek  Yeugeniy M. Gusev  Florence Habets  Parviz Irannejad  Randy Koster  Kenneth E. Mitchell  Olga N. Nasonova  Joel Noilhan  John Schaake  Adam Schlosser  Yaping Shao  Andrey B. Shmakin  Diana Verseghy  Kirsten Warrach  Peter Wetzel  Yongkang Xue  Zong-Liang Yang  Qing-cun Zeng 《Global and Planetary Change》1998,19(1-4)

The energy components of sixteen Soil-Vegetation Atmospheric Transfer (SVAT) schemes were analyzed and intercompared using 10 years of surface meteorological and radiative forcing data from the Red-Arkansas River basin in the Southern Great Plains of the United States. Comparisons of simulated surface energy fluxes among models showed that the net radiation and surface temperature generally had the best agreement among the schemes. On an average (annual and monthly) basis, the estimated latent heat fluxes agreed (to within approximate estimation errors) with the latent heat fluxes derived from a radiosonde-based atmospheric budget method for slightly more than half of the schemes. The sensible heat fluxes had larger differences among the schemes than did the latent heat fluxes, and the model-simulated ground heat fluxes had large variations among the schemes. The spatial patterns of the model-computed net radiation and surface temperature were generally similar among the schemes, and appear reasonable and consistent with observations of related variables, such as surface air temperature. The spatial mean patterns of latent and sensible heat fluxes were less similar than for net radiation, and the spatial patterns of the ground heat flux vary greatly among the 16 schemes. Generally, there is less similarity among the models in the temporal (interannual) variability of surface fluxes and temperature than there is in the mean fields, even for schemes with similar mean fields.  相似文献   

Delineation of riparian vegetation from Landsat multi‐temporal imagery using PCA          下载免费PDF全文

Masoomeh Alaibakhsh  Irina Emelyanova  Olga Barron  Neil Sims  Mehdi Khiadani  Alireza Mohyeddin 《水文研究》2017,31(4):800-810

A deficiency in crucial digital data, such as vegetation cover, in remote regions is a challenging issue for water management and planning, especially for areas undergoing rapid development, such as mining in the Pilbara, Western Australia. This is particularly relevant to riparian vegetation, which provides important ecological services and, as such, requires regional protection. The objective of this research was to develop an approach to riparian vegetation mapping at a regional scale using remotely sensed data. The proposed method was based on principal component analysis applied to multi‐temporal Normalized Difference Vegetation Index datasets derived from Landsat TM 5 imagery. To delimit the spatial extent of riparian vegetation, a thresholding method was required and various thresholding algorithms were tested. The accuracy of results was estimated for various Normalized Difference Vegetation Index multi‐temporal datasets using available ground‐truth data. The combination of a 14‐dry‐date dataset and Kittler's thresholding method provided the most accurate delineation of riparian vegetation.  相似文献   

The Distribution of Chemical Elements between Ecosystem Components in Belaya Bay,Lake Imandra,Murmansk Oblast     

Pavlova  A. S.  Sandimirov  S. S.  Kudryavtseva  L. P. 《Water Resources》2021,48(1):73-81

Water Resources - The effect of a large mining complex of Apatit JSC on the aquatic ecosystem of Lake Imandra is discussed. Hydrochemical data are given to characterize the pollution zone, and the...  相似文献   

Polychlorinated biphenyls (PCBs) and their hydroxylated metabolites (OH-PCBs) in livers of harbor seals (Phoca vitulina) from San Francisco Bay,California and Gulf of Maine     

June-Soo Park  Olga Ioanna Kalantzi  Dianne Kopec  Myrto Petreas 《Marine environmental research》2009,67(3):129-135

Bioaccumulation of endocrine disruptors in marine mammals positioned at the top of the food chain is of toxicological concern. Livers from four pups and ten adult harbor seals (Phoca vitulina) stranded in San Francisco Bay (SFB) and the Gulf of Maine (GOM) were analyzed for polychlorinated biphenyls (PCBs) and their hydroxylated metabolites (OH-PCBs). We used GC–ECD and GC–NCI/MS to investigate the presence of 28 PCBs and 8 OH-PCB metabolites, respectively. Σ₂₈PCB concentrations (di- to octa-CBs) ranged from 1.81 to 35.9 μg/g lipid with a median of 6.53 for the seal pups and 2.31 to 249 μg/g lipid with a median of 28.9 for the adult seals. Σ₈OH-PCB concentrations (penta- to hepta-OH-PCBs) ranged from 0.02 to 0.69 μg/g lipid with a median of 0.04 for the adult seals, i.e., at much lower concentrations than those for PCBs. Ratios of OH-PCBs to PCBs (0.24% on average) were comparable to those in beluga whale, but were lower than ratios in human livers. The OH-PCB profiles were slightly different between SFB and GOM seal livers, although similar PCB congener patterns were observed. Generally, 4-OH-CB107 was found predominantly in seal livers and was the only OH-PCB detectable in most of seal pup livers. This study provides information on OH-PCBs in seals, adding to the scarce exposure data for these chemicals.  相似文献