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811.
A comparison of current techniques for measuring elevations in the beach and near-shore zones is presented. Techniques considered
include traditional methods such as ground survey along transects and airborne stereophotogrammetry, and also newer methods
based on remote sensing such as airborne scanning laser altimetry (LiDAR). The approach taken was to identify a representative
group of users of beach elevation data, elicit their requirements regarding these data, then assess how well the different
methods met these requirements on both technical and financial grounds.
Potential users of beach height measurements include those concerned with coastal defence, coastal environmental management
economic exploitation of the intertidal zone, and coastal flood forecasting. Three test areas in the UK were identified covering
a range of such users and also different beach types. A total of 17 basic user requirements were elicited. For each requirement
each method was scored according to the degree to which it could meet the requirement. Total scores were calculated and each
method ranked. This was undertaken for all the requirements together, for a subset relating to survey of narrow beaches, and
for a subset relating to survey of wide beaches. Approximate costs were also established for the top six methods.
Airborne stereophotogrammetry proved to be the best method technically, but was also the most expensive. Ground survey provides
very good technical performance on narrower beaches at moderate cost. Airborne LiDAR can achieve good technical performance
on both narrow and wide beaches at lower cost than ground survey. The satellite-based waterline method was also inexpensive
and gave good results on wide beaches. An overall conclusion is that, while the traditional methods of ground survey and airborne
stereophotogrammetry remain the best for engineering-related surveys requiring high levels of accuracy, airborne LiDAR in
particular looks set to have a significant impact on beach survey for applications for which a vertical accuracy of 20 cm
is acceptable, provided that its technology evolves satisfactorily. 相似文献
812.
用放射免疫法分别测定了DBTCl对妊娠d6雌小鼠和成年雄小鼠外周血液中雌二醇和睾丸酮水平的影响.每天按小鼠体重一次腹腔注射0.025~0.400μg/kgd-1DBTCl,共染毒7d.实验条件为(22±2)℃和光暗=12h12h.结果表明,处理组睾丸酮和雌二醇的含量随处理剂量的增加而增加,当w(DBTCl)≥0.05μg/kg时,二者呈明显的剂量-效应关系.雌二醇含量的增加比睾丸酮更为显著CK雄性小鼠睾丸酮浓度为(2.88±0.72)ng/mL,在0.40μg/kg剂量组达到(9.95±2.5)μg/mL时,约为CK的3.5倍;而CK和0.40ng/kg剂量组妊娠小鼠雌二醇浓度分别为(30.32±5.43)ng/mL和(287.57±51.13)ng/mL,相差约9.5倍.文中还就DBTCl对小鼠血液中激素含量的影响机理进行了初步探讨.图1表2参20 相似文献
813.
The surface colour and temperature fields of the Mediterranean Sea, as appearing in time series, of basin-wide images available in the CZCS (1979–1985) and AVHRR (1982–1991) historical archives, differentiate between basin interior and continental margins affected by coastal patterns, river plumes, and mesoscale features. The original data were processed to apply calibration factors, to correct for atmospheric contamination, and to estimate chlorophyll-like pigment concentration and surface temperature. Composites were derived, as monthly and annual means, using a fixed equal-area projection with a 1-km2 pixel grid. Enhanced pigment values and lower temperatures along the northern coastal areas (i.e. the Ligurian, Provençal and Balearic basins, as well as the Adriatic, and Aegean Seas) have been associated with the impact of runoff from continental margins (i.e. both a direct impact due to the sediment load and one induced on the planktonic flora by the associated nutrient load) and with vertical mixing due to the prevailing winds (i.e. the Mistral in the northwest, the Bora in the Adriatic, the Etesians in the Aegean). The pattern of increasing pigments and decreasing temperatures in seen to develop in the monthly images from the coastal zone towards the open sea from summer to winter, and then back from winter to summer. The southern coastal areas show different values, namely lower pigments and higher temperatures (except in areas where the data are altered by signal contamination). It is suggested that differences in geomorphology and meteorology of the basin margins have an impact on both water biogeochemistry and dynamics, influencing the biooptical and thermal properties of the various sub-basins, and of the entire Mediterranean region. 相似文献
814.
Peter H. Roos Walter D. Weißenfels Manfred van Afferden Frank Pfeifer Walter G. Hanstein 《Environmental Sciences Europe》2000,12(1):13-19
The goal of the present work is to assess the adverse effects of soil bound polycyclic aromatic hydrocarbons (PAH) which remain in soils after biological remediation. We focus on risk assessment for mammalian species with respect to the oral uptake of contaminated soil particles and compare the results of a biomarker test with those of an ecotoxicological assay, the bioluminescence inhibition test withVibrio fischeri. As a biomarker effect in mammals, we determined the liver microsomal cytochrome P450 enzyme CYP1A1 which is induced by PAH in exposed rats. After biological soil treatment, different amounts of PAH remain in the soil depending on the soil properties and initial pollutant composition. Particularly, higher condensated PAH resists biological treatment due to its hydrophobicity. In addition, high amounts of organic carbon in the soils affect remediation efficiency. In the bioluminescence inhibition test, eluates of all biologically treated soils studied do not reveal any or only low inhibitory effects. In contrast, the oral uptake of biologically treated contaminated soils leads to induction levels for CYP1A1 similar to those in the untreated samples. A good correlation is obtained between CYP1A1 levels and the amount of 5 and 6-ring PAH in the soil samples. The main result is that the remediation efficiency determined by the luminescence test is not reflected by the biomarker test, a finding which indicates the high bioavailability of residual PAH in soils. Consequently, new criteria for human risk assessment can be delineated. 相似文献
815.
G. S. Kalacheva E. S. Zadereev V. G. Gubanov I. V. Gribovskaya 《Russian Journal of Ecology》2000,31(2):113-117
The chemical composition of water conditioned by colonies ofMoina macrocopa and involved in the regulation of their life cycle was analyzed in comparison with water samples from natural water bodies.
Dechlorinated tap water was used as the control medium. The results showed that metabolism of crustaceans leads to an increase
in the concentrations of phosphorus and nitrogen in all forms, the appearance of protein and carbohydrate fractions, and changes
in the composition of lipid fractions in the water conditioned by their colonies. The contents of all organic components are
very low, which makes their identification difficult. Concentrations of substances identified in the conditioned water do
not exceed those occurring in nature. 相似文献
816.
Gradients of genetic distances (GGDs) between 26 adjacent cenopopulations of Scotch pine (Pinus sylvestris L.) along the transects through the distinct landscape-ecotopic isolation borders were analyzed graphically. The results
made it possible to reveal and quantitatively estimate gradients and borders of gene-pool structural patterns in populations
of this species in the central part of Northern Eurasia. In lowland areas, the most distinct borders were found between pine
populations growing on dry lands and bogs (Pineta sphagnosa) in the forest zone of the Transural region, as well as between the Arakaragaiskii and Amankaragaiskii island pine forests
in the steppe zone (Northern Turgai). In highland areas (the Urals and the Carpathians), the greatest GGDs were observed between
low-mountain (about 600 m above sea level) and middle-mountain (850–900 m) populations. Analysis of GGDs is a promising gene-geographic
method for determining population borders and studying the chorogenetic structure of species. 相似文献
817.
Climatic characteristics of the northern Moscow region and the periodicity of seedage in Norway spruce were analyzed retrospectively.
The relationship between the intensity of seedage and weather conditions in the period before seedage was revealed. 相似文献
818.
819.
The interactions of zebra mussels, invertebrates, fish, and microorganisms were studied experimentally. Trends in the distribution
of total bacterial biomass, the abundance of heterotrophic organisms, and their functional activities in water and grounds
were analyzed. The most favorable conditions for development of bacteria developed in June, in the presence of fish and without
zebra mussels. In experimental ecosystems with zebra mussels, a decrease in the abundance and activity of microorganisms and
a change of dominant yeast forms were observed. 相似文献
820.
Makarov M. I. Kadulin M. S. Turchin S. R. Malysheva T. I. Aksenova A. A. Onipchenko V. G. Menyailo O. V. 《Russian Journal of Ecology》2019,50(4):337-342
Russian Journal of Ecology - Abstract—The study of the effect of mycorrhiza symbiosis on the transformation of carbon and nitrogen compounds in soils is important in view of the necessity to... 相似文献