共查询到20条相似文献，搜索用时 15 毫秒
1.
Induction of cytochrome P4501A in fish is a well-known indicator of exposure to polycyclic aromatic hydrocarbons (PAHs) and determination of PAH metabolites in bile by fixed wavelength fluorescence (FF) or synchronous fluorescence spectroscopy (SFS), has become an useful method in monitoring programs. In this work the relationship between cytochrome P4501A (EROD activity) and levels of biliary PAH metabolites was measured in the European eel Anguilla anguilla, in both field and laboratory conditions: organisms were sampled on a seasonal basis from the Orbetello lagoon (Tuscany) to characterize the natural variability of these biological parameters, while in laboratory eels were intraperitoneally injected with benzo[a]pyrene to investigate temporal and dose-dependent induction patterns. Results showed that induction of cytochrome P450 and accumulation of PAHs metabolites in bile are not necessarily correlated either in field, or in laboratory investigations; different seasonal changes were measured in natural conditions and slight variations in dose and time response patterns were also obtained in laboratory exposures. 相似文献
2.
3.
The hazardous effect of a toxic compound is determined by its intrinsic toxicity and its environmental fate, governed by dynamic biogeochemical processes. A high persistence to microbial breakdown and biotransformation in higher organisms, combined with high lipophilicities1,2, leads to high bioaccumulation rates of PCB's, increasing the risk of chronic exposure. In laboratory studies with juvenile sole (Solea solea), bioaccumulation was influenced by differences between values of biological half-times of congeners, PCB patterns in food and water, differences between lipid contents of organs and changes in lipid speciation of some organs. In the field, highly similar PCB patterns are usually found within each of the compartments water, seston, sediment and within animal species. However, between them patterns differ.3–6 This is best explained by assuming that the patterns of congeners in organisms are ultimately determined by the pattern in solution and biological half-times of individual congeners; the latter can be influenced by differences in biotransformation capacity between species. 相似文献
4.
5.
K. I. Pavlov V. N. Mukhin V. G. Kamenskaya V. M. Klimenko 《Izvestiya Atmospheric and Oceanic Physics》2016,52(7):737-744
The investigation of female physiological reactions to different meteorological conditions and space weather is relevant, since there are little experimental findings in this field. The purpose of this work is to determine how the level of cerebral-cortex activity in women depends on the meteorological and cosmophysical parameters of weather and space processes. We studied electroencephalograms (EEGs) recorded at rest in the sitting position and with eyes closed. We performed four series of measurements of brain bioelectrical activity from February to June 2013. We found that the level of cortical activity recorded by EEG changed significantly during these 6 months. Significant differences were detected between the cortical activity and the parameters of weather and space processes; namely, an increase in the air temperature and a decrease in the wind speed and cosmic-ray energy result in a decrease in the activity rate of the right occipital lobe. 相似文献
6.
V. A. Ozheredov 《Izvestiya Atmospheric and Oceanic Physics》2012,48(7):730-737
It is known that long periods of adverse weather have a negative effect on the human cardiovascular system. A number of studies have set a lower limit of around 5 days for the duration of these periods. However, the specific features of the negative dynamics of the main weather characteristics—air temperature and atmospheric pressure—remained open. To address this problem, the present paper proposes a conjunctive method of the theory of pattern recognition. It is shown that this method approaches a globally optimal (in the sense of recognition errors) Neumann critical region and can be used to solve various problems in heliobiology. To illustrate the efficiency of this method, we show that some quickly relaxing short sequences of temperature and pressure time series (the so-called temperature waves and waves of atmospheric pressure changes) increase the risk of cardiovascular diseases and can lead to serious organic lesions (particularly myocardial infarction). It is established that the temperature waves and waves of atmospheric pressure changes increase the average morbidity rate of myocardial infarction by 90% and 110%, respectively. Atmospheric pressure turned out to be a more biotropic factor than air temperature. 相似文献
7.
This is a Part I of a paper of nonlinearities of wind waves in the deep open ocean. First, considerations are given in order to verify the theoretical expression for bound waves from observed data. We compare the contribution of bound waves and double Bragg scattering to the second-order scattering, and we show that the contribution of bound waves is larger, and that bound waves can be detected by measuring the Doppler spectra of HF (high-frequency) radio wave scattering from the sea surface. Moreover, if the theory of the HF radio wave scattering from the sea surface is verified, so is the second-order perturbation theory for bound waves. Then, the contributions of bound waves to ocean wave spectra are investigated on the basis of the nonlinear theory. The bound waves are shown to modify frequency spectra and wave directional distributions at higher frequencies, and it is shown that although the modifications of frequency spectra are smaller for a two-dimensional field case than for a one-dimensional field case, they are not negligible at higher frequencies. On the other hand, the modifications of wave directional distributions are shown to be significant at higher frequencies. These discussions become significant only when bound wave predictions are verified in the open ocean. Consequently, it is shown that nonlinearities of water waves are important in considering both radio wave scattering from the sea surface and the detailed structures of ocean wave spectra at high frequencies. 相似文献
8.
9.
10.
A model for the downward transfer of wind momentum is derived for growing waves. It is shown that waves, which grow due to an uneven pressure distribution on the water surface or a wave-coherent surface shear stress have horizontal velocities out of phase with the surface elevation. Further, if the waves grow in the x-direction, while the motion is perhaps time-periodic at any fixed point, the Reynolds stresses associated with the organized motion are positive. This is in agreement with several field and laboratory measurements which were previously unexplained, and the new theory successfully links measured wave growth rates and measured sub-surface Reynolds stresses. Wave coherent air pressure (and/or surface shear stress) is shown to change the speed of wave propagation as well as inducing growth or decay. From air pressure variations that are in phase with the surface elevation, the influence on the waves is simply a phase speed increase. For pressure variations out of phase with surface elevation, both growth (or decay) and phase speed changes occur. The theory is initially developed for long waves, after which the velocity potential and dispersion relation for linear waves in arbitrary depth are given. The model enables a sounder model for the transfer to storm surges or currents of momentum from breaking waves in that it does not rely entirely on ad-hoc turbulent diffusion. Future models of atmosphere-ocean exchanges should also acknowledge that momentum is transferred partly by the organized wave motion, while other species, like heat and gasses, may rely totally on turbulent diffusion. The fact that growing wind waves do in fact not generally obey the dispersion relation for free waves may need to be considered in future wind wave development models. 相似文献
11.
This is a Part II of a paper of nonlinearities of wind waves in the deep open ocean. As shown in Part I, bound waves in deep sea are detectable by extracting secondorder Doppler spectra from the Doppler spectra of HF (high-frequency) radio waves scattered from the sea surface. There is a remarkable agreement between the calculated and measured Doppler spectra, considering the noise levels in measured Doppler spectra and the uncertainties in directional properties. The theoretical expression for bound waves is thus verified. Furthermore, the upper limit in calculating the Doppler spectra for the second-order approximation is presented from field observations, although we cannot conclude that it is equivalent to the limitation of the second-order bound wave theory. It is shown that analysis of radio wave scattering by the sea surface is one useful means of understanding the nonlinear properties of ocean waves. 相似文献
12.
This paper is a short review of publications on the influence that solar activity and geomagnetic disturbances (cosmic weather)
have on physical-chemical systems. The effects of cosmic weather may some-times be detected by the presence of an uncontrolled
factor in these experiments. Direct reactions to cosmic weather are reliably identified in quantitative observations over
various test systems, mainly water solutions. The effects of cosmic weather are also found from the data obtained by monitoring
some simple physical systems, including semiconductors. All these effects are either cosmic physical rhythms or they are easily
registered sporadic heliogeophysical events (e.g., magnetic storms). There are convincing data that demonstrate the influence
that cosmic weather has on the accident rate in various engineering and physical systems. Researchers are at odds on the physical
nature of the main physical agent, but the contribution of electromagnetic fields to these processes is considered important. 相似文献
13.
The studies of the influence that a magnetic field (MF) with a frequency of 8 Hz has on the infradian rhythms of physiological
and metabolic processes indexes in animals have been carried out in order to verify the hypothesis on the synchronizing effect
of natural electromagnetic fields. It is shown that the MF effect has alternating characteristics of the time organization
of energetic physiological and metabolic processes in animal organisms in an infradian range and the partial smoothing of
biorhythmic deviations between individual-typological groups of organisms occurs for single processes. This (i) shows the
common system reaction mechanisms that the organisms of animals have to the effect of a certain factor and (ii) is evidence
of the synchronizing influence of the daily influence of magnetic fields of extremely low frequencies on populations of organisms
with initially different biorhythmic types. It has been concluded that the stable variations of electromagnetic background,
including natural, can serve as a timer for biorhythms in a wide range of periods. 相似文献
14.
东菲律宾海柱样沉积物的磁性特征 总被引：2，自引：0，他引：2
对东菲律宾海帕里西维拉海盆西侧F090102柱样进行了系统的古地磁和岩石磁学研究,测量了天然剩磁倾角、磁化率、饱和等温剩磁、非磁滞剩磁、-T曲线等磁学参数,进行了磁性地层的划分对比,识别出松山反极性时内的贾拉米洛和奥都维正极性亚时。对磁学参数及其有关比值的研究发现,岩心磁性矿物以低矫顽力磁铁矿为主,可能含有一定的钛磁铁矿。磁性矿物主要是陆源碎屑成因,岩心底段受到海底火山作用的影响。根据磁学参数随深度的变化将岩心分为3段,各段反映了沉积环境和古气候的变化。 相似文献
15.
Induction of cytochrome P4501A in fish is a well-known indicator of exposure to polycyclic aromatic hydrocarbons (PAHs) and determination of PAH metabolites in bile by fixed wavelength fluorescence (FF) or synchronous fluorescence spectroscopy (SFS), has become an useful method in monitoring programs. In this work the relationship between cytochrome P4501A (EROD activity) and levels of biliary PAH metabolites was measured in the European eel Anguilla anguilla, in both field and laboratory conditions: organisms were sampled on a seasonal basis from the Orbetello lagoon (Tuscany) to characterize the natural variability of these biological parameters, while in laboratory eels were intraperitoneally injected with benzo[a]pyrene to investigate temporal and dose-dependent induction patterns. Results showed that induction of cytochrome P450 and accumulation of PAHs metabolites in bile are not necessarily correlated either in field, or in laboratory investigations; different seasonal changes were measured in natural conditions and slight variations in dose and time response patterns were also obtained in laboratory exposures. 相似文献
16.
渤海波浪和潮汐风暴潮相互作用对波浪影响的数值研究 总被引：11，自引：2，他引：11
基于依赖波浪成长状态波令的表面风应力，提出了一个波浪和风暴潮潮汐运动相互作用的联合数值模式，实现了第三代波浪模式和三维风暴潮潮汐模式联合作用的数值研究，并结合渤海典型天气个例的研究，给出了渤海波浪和风暴潮潮汐相互作用对波浪影响的机制和大小量级的定量估计。研究表明，对不同天气过程，波浪和风暴潮潮汐相互作用对波浪影响的性质和大小不同；对强寒潮过程，对波浪影响主要由风暴潮所支配波高调制可达1m，在黄河口区一般达0．5m；对弱天气过程，对波浪影响主要由潮所控制，波高调制约在0．2m，联合作用模式给出的结果与实测更吻合。 相似文献
17.
We analyze the effect of geomagnetic activity on variations in quasi-static electric field strength and the horizontal geomagnetic
field component in the band of periods of tidal and planetary waves. Variations in oscillation intensities and periods in
the power spectra of these parameters synchronously with the K
p
index are shown. Taking into account the relationship of these parameters with the air pressure, we suggest a possible biophysical
mechanism of the relation between the state of the human cardiovascular system and geomagnetic activity by means of resonant
interaction with the environment. In periods of high geomagnetic activity, the air pressure and temperature vary due to an
increase in atmospheric transparency as a result of the Forbush decrease in the cosmic ray flux rate. It is these variations
that directly affect humans. 相似文献
18.
R. M. Kirk 《新西兰海洋与淡水研究杂志》2013,47(2):358-375
Abstract On shingle beaches, changes in foreshore elevation and sediment distribution landward of the break point are produced largely by variations in the uprush and backwash of waves. However, very little is known about the forces active in this zone. A field instrument system which senses and records some of the parameters thought to influence beach erosion and deposition in this zone has been constructed. The equipment is also suitable for the investigation of a number of other shore and nearshore processes including erosion on sandy and rocky shores, and flow processes affecting littoral biological communities. In the swash zone two sensing heads, a dynamometer and a depth recorder, sense variations in uprush and backwash velocities, energies, discharges, and depths of flow. Both devices are electromechanical and are coupled to a recording unit on land by PVC‐insulated cable. The dynamometer (two force plates mounted back‐to‐back on a compression spring and coupled to variable resistances) has been calibrated, statically and in a flume, to obtain velocity determinations accurate to within 10 cm . sec?1 of true flow speed. Average swash zone velocities lie between 100 and 300 cm . sec?1. A parallel‐wire resistance gauge mounted an a stilling tube records flow depths. As water level rises and falls in the tube it alters resistance in a control circuit. The land unit, amplifiers and a strip‐chart recorder, receives the output from the dynamometer and flow depth gauge. The recorder is equipped with a trip‐pen so that analysis of wave periods or other variables is possible in the field. With poles at known spacings across the shore and the trip‐pen records, velocity distributions across the swash zone can be obtained. Measurements of velocity made near the bed with the dynamometer can then be related to the local surface velocity profile. Problems with the instrument system include inability to record velocities at several points simultaneously, and unreliable records of backwash parameters with low breakers on shingle beaches because of the small volume of flow and rapid percolation of water into the beach face. 相似文献
19.
本文利用中日黑潮联合调查研究期间1986年5—6月和1989年7—8月航次水文与生物的同步取样资料,分析了东海测区内水系组成与浮游甲藻类及浮游桡足类等分布之间的对应关系。指出了不同生态类型的生物需要不同的物理海洋环境条件。同时,某些指示生物的分布又为区分水系、了解流系情况提供了良好的示性指标,并且从某些生物数量的变化还可以判断出水系混合与变性的程度。 相似文献
20.
全球性的气候变化严重地威胁着自然生态环境间的平衡。在影响生态系统功能的诸多因素中,太阳紫外辐射的增强逐渐成为最受关注的全球性环境问题之一。太阳紫外辐射对地球生物的生命过程有着举足轻重的影响。生物体一旦吸收了高能量的紫外辐射,则可对其各种生理过程产生影响,打破内稳态,尤其是紫外辐射对DNA的损伤作用,是诱导一系列生物效应的主要原因。本文综述了近年来与鱼类及水生无脊椎动物有关的紫外辐射研究。从紫外辐射对生物不同发育时期的影响、生物对紫外线响应方式、紫外辐射与其他因素复合影响三个层面进行总结。通过总结紫外辐射对鱼类及水生无脊椎动物的影响,可为预测紫外辐射在水生生态系统中的作用提供助力,为海洋生物对环境变化的生理响应研究提供参考。 相似文献