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671.
Regoli F Gorbi S Frenzilli G Nigro M Corsi I Focardi S Winston GW 《Marine environmental research》2002,54(3-5):419-423
An integrate approach will be discussed for investigations on oxidative stress in xenobiotic toxicity. While the analysis of individual antioxidants is useful for their sensitivity and to understand the mode of action of a stressor, the integration with the analysis of the total antioxidant capacity provides a more holistic assessment of the overall biological significance of such variations. TOSC has a greater predictive value on the health condition of the organisms and allows to discriminate the different role of specific ROS in oxidative stress syndrome. 相似文献
672.
Distribution of trace and major elements in sediment and pore waters of the Lena Delta and Laptev Sea 总被引:1,自引:0,他引:1
Sediment cores collected during the SPASIBA expedition in 1991 were analysed for their trace- and major element concentrations. Leachable (0.1 N HCl) as well as residual concentrations were determined. Fe and Mn were measured in the interstitial waters to characterize redox conditions. Lateral distribution patterns of solid phase Cu, Cd, Ni, Pb and Zn show a small increase in concentration from the Lena Delta in seaward direction. In general concentrations of these metals are very low and similar to natural background values. With some exceptions, solid phase profiles with depth of all investigated elements do not show strong variations. No enrichment of Pb and Zn in surface layers was found. Remobilization processes and transport of particles enriched in Mn are responsible for Mn accumulation in a particular area. Pore-water concentrations of dissolved Mn in the latter sediments are very high (> 700 μM) and suggest strong Mn reduction directly below the sediment-water interface. In contrast to Mn, the depth profiles of Cd show a surface layer with lower concentrations and an increase deeper down the sediment. The C/N ratio in the sediment decreases from 13 in the Lena mouth to 9 in the more marine part of the Laptev Sea. Surface sediments in the Laptev Sea are very uniform and homogeneous and show only small concentration gradients. 相似文献
673.
X-band sea-clutter nonstationarity: influence of long waves 总被引:1,自引:0,他引:1
In this paper, we deal with the problem of modeling the backscattering from sea surface for low-grazing-angle and high-resolution radar systems. Based on the electromagnetic two-scale model, we analyzed both the amplitude and frequency modulations induced on the small-scale Bragg resonant waves by the large-scale surface tilt and advection due to the swell presence. Evidence of sea-clutter nonstationarity has been verified and the relationship between the variations of clutter spectral features, such as texture, Doppler centroid, and bandwidth, have been studied by processing real sea-clutter data recorded by the IPIX radar of McMaster University, Hamilton, ON, Canada. An autoregressive nonstationary process is proposed and validated to model the physical phenomenon. 相似文献
674.
V. A. Frol’kis I. L. Karol’ A. A. Kiselev Yu. E. Ozolin V. A. Zubov 《Izvestiya Atmospheric and Oceanic Physics》2007,43(4):413-422
This is a study of the sensitivity of model results (atmospheric content of main gas constituents and radiative characteristics of the atmosphere) to errors in emissions of a number of atmospheric gaseous pollutants. Groups of the model variables most dependent on these errors are selected. Two variants of emissions are considered: one without their evolution and the other with their variation according to the IPCC scenario. The estimates are made on the basis of standard statistical methods for the results obtained with the detailed onedimensional radiative—photochemical model of the Main Geophysical Observatory (MGO). Some approaches to such estimations with models of higher complexity and to the solution of the inverse problem (i.e., the estimation of the necessary accuracy of external model parameters for obtaining the given accuracy of model results) are outlined. 相似文献
675.
V. M. Kushnir 《Physical Oceanography》1997,8(1):29-38
Experimentally-derived data are used to scrutinize structural peculiarities of the upper boundary of deep near-bottom layer
in the Black Sea. Thermal fluxes through the layer’s upper boundary have been evaluated and compared with the geothermal fluxes.
Although there is significant divergence between the individual evaluations, the quantities at issue generally agree with
one another. It is shown that in evaluating thermal fluxes, it is necessary to consider fine structure of the differential-diffusive
type. Stability of the upper boundary of the deep near-bottom layer has been examined, and diagrams of stability/instability
resulting from the development of convection have been plotted.
Translated by Vladimir A. Puchkin. 相似文献
676.
M.E. vinogradov E.A. Shushkina V.I. Vedernikov N.P. Nezlin V.I. Gagarin 《Deep Sea Research Part II: Topical Studies in Oceanography》1997,44(9-10)
Data collected from 20 years of observations by the P. P. Shirshov Institute of Oceanology (about 250 comprehensive ecosystem stations) are summarized to evaluate the primary production and biomass of the principal groups of plankton in the Pacific Ocean. The stations were classified into geographical regions according to satellite determined criteria. The areas of these regions were evaluated according to CZCS data from 1978 to 1986. The total value of primary production was evaluated as 26·9 Gt C year−1. Taking the “bottle effect” correction into account, this value may be as high as 45.6 Gt C year−1. Total biomass values of phytoplankton (134 Mt C), bacteria (86 Mt C), protozoa (26 Mt C) and mesoplankton (184 Mt C) were also calculated. Seasonal variabilities of all these values were remarkably insignificant. 相似文献
677.
The BIO Mark 8 thrust anemometer measures the drag of the wind on a perforated table tennis ball mounted on a vertical beam. The tri-axial displacement of the beam is sensed by eddy current proximity sensors. This anemometer has a flat frequency response from 0 to 10 Hz and can measure wind from 0 to 28 m s−1 at temperature from − 19 to + 28°C. It is designed for remote operation for extended periods of time such as on stable towers at sea. 相似文献
678.
Kazufumi Takayanagi George T. F. Wong Margaret J. Filardo 《Journal of Oceanography》1989,45(2):129-133
Nitrate reductase activity and the concentrations of selenite and selenate were monitored for six months at the mouth of Chesapeake Bay (USA). A positive correlation was found between nitrate reductase activity and the concentration of selenite, suggesting that selenite may be formed in coastal waters and nitrate reductase may be involved in the process. 相似文献
679.
Freezing as a method of sample preservation for the analysis of dissolved inorganic nutrients in seawater 总被引:1,自引:0,他引:1
John E. Dore Terrence Houlihan Dale V. Hebel Georgia Tien Luis Tupas David M. Karl 《Marine Chemistry》1996,53(3-4)
It is often desirable or necessary to store collected seawater samples prior to analysis for dissolved inorganic nutrients. It is therefore important to establish preservation and storage techniques that will ensure sample integrity and will not alter the precision or accuracy of analysis. We have performed a series of experiments on the storage of nutrient samples collected at the oligotrophic North Pacific benchmark Station ALOHA, using both standard autoanalyses and low-level techniques. Our results reveal that for oligotrophic oceanic waters, the immediate freezing of an unfiltered water sample in a clean polyethylene bottle is a suitable preservation method. This procedure is simple, it avoids potentially contaminating sample manipulations and chemical additions, and it adequately preserves the concentrations of nitrate + nitrite, soluble reactive phosphate, and soluble reactive silicate within a single water sample. 相似文献
680.