On the relationship between small atmospheric ions concentration and (1) smoke, (2) sulfur dioxide and (3) wind speed     

Dimitris A. Retalis 《Pure and Applied Geophysics》1977,115(3):575-581

In the present study the influence of smoke and sulfur dioxide concentrations and of wind velocity on the concentration of small positive and negative ions above Athens area (=37°58.3N, =23°43E,h=107 m) is examined.Between the above mentioned elements simple linear correlation and multiple linear correlation is attempted. This correlation is based on mean daily values of the elements, for the two-year period 1971–1972, for each month separately.From the above examination it has been ascertained that small ions concentration increases as smoke and/or sulfur dioxide concentration decreases. Also, small ions concentration increases as wind velocity increases.In addition, it was ascertained that sulfur dioxide contributes the least to the determination of the variance of small ions concentration, whilst the greatest contribution is made by smoke for the positive small ions or by wind velocity for the negative ones.  相似文献   

An analysis of change in alpine annual maximum discharges: implications for the selection of design discharges     

Attilio Castellarin  Alberto Pistocchi 《水文研究》2012,26(10):1517-1526

The paper presents an analysis of 17 long annual maximum series (AMS) of flood flows for Swiss Alpine basins, aimed at checking the presence of changes in the frequency regime of annual maxima. We apply Pettitt's change point test, the nonparametric sign test and Sen's test on trends. We also apply a parametric goodness‐of‐fit test for assessing the suitability of distributions estimated on the basis of annual maxima collected up to a certain year for describing the frequency regime of later observations. For a number of series the tests yield consistent indications for significant changes in the frequency regime of annual maxima and increasing trends in the intensity of annual maximum discharges. In most cases, these changes cannot be explained by anthropogenic causes only (e.g. streamflow regulation, construction of dams). Instead, we observe a statistically significant relationship between the year of change and the elevation of the catchment outlet. This evidence is consistent with the findings of recent studies that explain increasing discharges in alpine catchments with an increase in the temperature controlling the portion of mountain catchments above the freezing point. Finally, we analyse the differences in return periods (RPs) estimated for a given flood flow on the basis of recent and past observations. For a large number of the study AMS, we observe that, on average, the 100‐year flood for past observations corresponds to a RP of approximately 10 to 30 years on the basis of more recent observation. From a complementary perspective, we also notice that estimated RP‐year flood (i.e. flood quantile (FQ) associated with RP) increases on average by approximately 20% for the study area, irrespectively of the RP. Practical implications of the observed changes are illustrated and discussed in the paper. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Derivation of a curve number and kinematic-wave based flood frequency distribution     

R. S. KUROTHE  N. K. GOEL  B. S. MATHUR 《水文科学杂志》2013,58(4):571-584

Abstract

The physically-based flood frequency models use readily available rainfall data and catchment characteristics to derive the flood frequency distribution. In the present study, a new physically-based flood frequency distribution has been developed. This model uses bivariate exponential distribution for rainfall intensity and duration, and the Soil Conservation Service-Curve Number (SCS-CN) method for deriving the probability density function (pdf) of effective rainfall. The effective rainfall-runoff model is based on kinematic-wave theory. The results of application of this derived model to three Indian basins indicate that the model is a useful alternative for estimating flood flow quantiles at ungauged sites.  相似文献   

Combined use of spot samples and continuous integrated sampling in a study of storm runoff from a lowland catchment in the south of England     

A. Gkritzalis‐Papadopoulos  M. R. Palmer  M. C. Mowlem 《水文研究》2012,26(2):297-307

We have used two different sampling techniques to study the geochemical response of a small lowland rural catchment to episodic storm runoff. The first method involves traditional daily spot sampling and has been used to develop a standard end‐member mixing analysis (EMMA) of the relative contributions of ground water flow and surface runoff to the total stream flow. The second method utilizes a continuous sampling device, powered by an osmotic pump, to produce an integrated 24‐h sample of the stream flow. When combined with the EMMA results from the spot samples, analyses of the integrated samples reveal the presence of a third component that makes a significant contribution to the dissolved NO₃, Ca and K export from the catchment during the rising limb of the hydrographic profile of a storm event following a prolonged dry period. The storm occurred in the middle of the night, so that the response of the stream chemistry was not captured by the daily samples. We hypothesize that this third component is derived from the flushing of stored soil water that contains the geochemical signature of decaying vegetation. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

河北滦南滨海湿地土壤重金属污染特征及评价     

《海洋技术学报》2024,(1)

滨海湿地作为一种具有多种功能和蕴含丰富资源的生态系统，是人类重要的生存环境之一。湿地土壤重金属污染问题是当前湿地科学领域内的热点话题。为研究河北省滦南滨海湿地重金属污染特征，本文利用单因子指数法、内梅罗综合污染指数法和地累积指数法对重金属污染状况进行评价。结果表明：铜（Cu）、锌（Zn）、铬（Cr）、铅（Pb）、镉（Cd） 的单因子质量指数均小于1.0，说明研究区重金属含量小于土壤背景值，土壤未受到污染。内梅罗综合指数法Cu、Zn、Cr、Pb、Cd 指数均小于0.7，表明滦南湿地土壤重金属污染水平处于未污染。湿地各区域重金属地累积指数为无污染或较轻污染，其中Pb 污染为较轻污染，监测点主要与人类活动有关。利用地累积指数分析认为Pb 在湿地北区为轻度污染水平，经调查发现该区域主要为居民点，人类活动频繁，其他重金属均无污染。河北滦南滨河湿地土壤未受到重金属污染，湿地土壤环境较好。  相似文献   

Ⅲ变浅作用下列率谱和频率谱的实验研究     

张书文  史宏达 《海洋湖沼通报》1999,(1):11-15

为研究变浅作用下的非线性海浪，本文利用并矢相关谱估计方法，设计并进行了多种强度下，由深水传入近岸浪变浅作用下，列率谱和频率谱随水深和坡度变化的实验比较研究。  相似文献   

Potential neutrino signals in a northern hemisphere neutrino telescope from galactic gamma-ray sources     

C. Stegmann  A. Kappes  J. Hinton  F. Aharonian 《Astrophysics and Space Science》2007,309(1-4):429-433

Neutrino energy spectra have been calculated based on the recently measured energy spectra of Galactic very high energy γ-ray sources. Based on these neutrino spectra the expected event rates in the ANTARES neutrino telescope and KM3NeT, a future neutrino telescope in the Mediterranean Sea with an instrumented volume of one km³, have been calculated. For the brightest γ-ray sources we find event rates of the order of one neutrino per year. Although the neutrino event rates are comparable to the background from atmospheric neutrinos the detection of individual sources seems possible.  相似文献   

Quantitative estimation of helium-3 spatial distribution in the lunar regolith layer   总被引：2，自引：0，他引：2  

Wenzhe Fa 《Icarus》2007,190(1):15-23

³He (helium-3) in the lunar regolith implanted by the solar wind is one of the most valuable resources because of its potential as a fusion fuel. The abundance of ³He in the lunar regolith is related to solar wind flux, lunar surface maturity and TiO₂ content, etc. A model of solar wind flux, which takes account of variations due to shielding of the nearside when the Moon is in the Earth's magnetotail, is used to present a global distribution of relative solar wind flux over the lunar surface. Using Clementine UV/VIS multispectral data, the global distribution of lunar surface optical maturity (OMAT) and the TiO₂ content in the lunar regolith are calculated. Based on Apollo regolith samples, a linear relation between ³He abundance and normalized solar wind flux, optical maturity, and TiO₂ content is presented. To simulate the brightness temperature of the lunar surface, which is the mission of the Chinese Chang-E project's multichannel radiometers, a global distribution of regolith layer thickness is first empirically constructed from lunar digital elevation mapping (DEM). Then an inversion approach is presented to retrieve the global regolith layer thickness. It finally yields the total amount of ³He per unit area in the lunar regolith layer, which is related to the regolith layer thickness, solar wind flux, optical maturity and TiO₂ content, etc. The global inventory of ³He is estimated as 6.50×¹⁰⁸ kg, where 3.72×¹⁰⁸ kg is for the lunar nearside and 2.78×¹⁰⁸ kg is for the lunar farside.  相似文献   

Design hydrograph estimation in small and ungauged watersheds: continuous simulation method versus event‐based approach     

S. Grimaldi  A. Petroselli  F. Serinaldi 《水文研究》2012,26(20):3124-3134

The proper assessment of design hydrographs and their main properties (peak, volume and duration) in small and ungauged basins is a key point of many hydrological applications. In general, two types of methods can be used to evaluate the design hydrograph: one approach is based on the statistics of storm events, while the other relies on continuously simulating rainfall‐runoff time series. In the first class of methods, the design hydrograph is obtained by applying a rainfall‐runoff model to a design hyetograph that synthesises the storm event. In the second approach, the design hydrograph is quantified by analysing long synthetic runoff time series that are obtained by transforming synthetic rainfall sequences through a rainfall‐runoff model. These simulation‐based procedures overcome some of the unrealistic hypotheses which characterize the event‐based approaches. In this paper, a simulation experiment is carried out to examine the differences between the two types of methods in terms of the design hydrograph's peak, volume and duration. The results conclude that the continuous simulation methods are preferable because the event‐based approaches tend to underestimate the hydrograph's volume and duration. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Heavy metal release by peat erosion in the Peak District,southern Pennines,UK     

J. J. Rothwell  S. G. Robinson  M. G. Evans  J. Yang  T. E. H. Allott 《水文研究》2005,19(15):2973-2989

Upper North Grain (UNG) is a heavily eroding blanket peat catchment in the Peak District, southern Pennines, UK. Concentrations of lead in the near‐surface peat layer at UNG are in excess of 1000 mg kg⁻¹. For peatland environments, these lead concentrations are some of the highest globally. High concentrations of industrially derived, atmospherically transported magnetic spherules are also stored in the near‐surface peat layer. Samples of suspended sediment taken during a storm event that occurred on 1 November 2002 at UNG, and of the potential catchment sources for suspended sediments, were analysed for lead content and the environmental magnetic properties of anhysteretic remanent magnetization (ARM) and saturation isothermal remanent magnetization (SIRM). At the beginning of the storm event, there is a peak in both suspended sediment and associated lead concentration. SIRM/ARM values for suspended sediment samples throughout the storm reveal that the initial ‘lead flush’ is associated with a specific sediment source, namely that of organic sediment eroded from the upper peat layer. Using the magnetic ‘fingerprinting’ approach to discrimination of sediment sources, this study reveals that erosion of the upper peat layer at UNG is releasing high concentrations of industrially derived lead (and, by inference, other toxic heavy metals associated with industrial particulates) into the fluvial systems of the southern Pennines. Climate‐change scenarios for the UK, involving higher summer temperatures and stormier winters, may result in an increased flux both of sediment‐associated and dissolved heavy metals from eroding peatland catchments in the southern Pennines, adversely affecting the quality of sediment and water entering reservoirs of the region. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献