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221.
222.
本文从色度学的角度阐述了颜色是人的主观感受,为了对每一个颜色均能明确地描述和定义,借助色度空间概念,把色调的颜色空间转化为立体的数学模型.根据矿山现场工作环境特点及对国内外相关标准中逆反射色域分析,建立逆反射型矿山安全标志的色域选择理念,并对两种不同的测色方法进行了分析研究. 相似文献
223.
Boxman AW Peters RC Roelofs JG 《Environmental pollution (Barking, Essex : 1987)》2008,156(3):1252-1259
In a Scots pine forest the throughfall deposition and the chemical composition of the soil solution was monitored since 1984. (Inter)national legislation measures led to a reduction of the deposition of nitrogen and sulphur. The deposition of sulphur has decreased by approximately 65%. The total mineral-nitrogen deposition has decreased by ca. 25%, which is mainly due to a reduction in ammonium-N deposition (−40%), since nitrate-N deposition has increased (+50%). The nitrogen concentration in the upper mineral soil solution at 10 cm depth has decreased, leading to an improved nutritional balance, which may result in improved tree vitality. In the drainage water at 90 cm depth the fluxes of NO3− and SO42− have decreased, resulting in a reduced leeching of accompanying base cations, thus preserving nutrients in the ecosystem. It may take still several years, however, before this will meet the prerequisite of a sustainable ecosystem. 相似文献
224.
The relationship between diversity profiles,evenness and species richness based on partial ordering 总被引:4,自引:0,他引:4
Rousseau Ronald Van Hecke Piet NIjssen David Bogaert Jan 《Environmental and Ecological Statistics》1999,6(2):211-223
Problems with the notion of evenness, such as ambiguity, proliferation of indices, choice of indices, etc. can be overcome by a more fundamental, mathematical approach. We show that the Lorenz curve is an adequate representation of evenness. The corresponding Lorenz order induces a partial order in the set of equivalent abundance vectors. Also diversity can adequately be studied through a partial order and represented by a curve derived from the classical Lorenz curve. This curve is known as the intrinsic diversity profile (or k-dominance curve) and was introduced by Patil and Taillie (1979) and Lambshead et al. (1981). 相似文献
225.
David Fowler Rognvald Smith Jennifer Muller John Neil Cape Mark Sutton Jan Willem Erisman Hilde Fagerli 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):41-47
Emissions of sulphur and oxidized nitrogen compounds in Europe have been reduced following a series of control measures during
the last two decades. These changes have taken place during a period in which the primary gases and the wet deposition throughout
Europe were extensively monitored. Since the end of the 1970s, for example land based sulphur emissions declined by between
90 and 70% depending on the region. Over the same period the total deposition of sulphur and its partitioning into wet and
dry deposition have declined, but the spatial pattern in the reduction in deposition differs from that of emission and has
changed with time. Such non-linearities in the emission-deposition relationship are important to understand as they complicate
the process of assessing the effects of emission reduction strategies. Observed non-linearities in terrestrial sulphur emission-deposition
patterns have been identified in north west Europe due to increases in marine emissions, and are currently slowing the recovery
of freshwater ecosystems. Changes in the relative amounts of SO2 and NH3 in air over the last two decades have also changed the affinity of terrestrial surfaces for SO2 and have therefore changed the deposition velocity of SO2 over substantial areas. The consequence of this effect has been the very rapid reduction in ambient SO2 concentration in some of the major source areas of Europe, where NH3 did not change much. Interactions between the different pollutants, generating non-linearities are now being incorporated
in long-range transport models to simulate the effects of historical emission trends and to provide projections into the future.
This paper identifies non-linearities in emission deposition relationships for sulphur and nitrogen compounds in Europe using
data from the EMEP long-rang transport model and measured concentration fields of the major ions in precipitation and of SO2 and NO2 in surface air. 相似文献
226.
Brian P. Leaderer Rebecca T. Zagraniski Jan A. J. Stolwijk 《Environmental management》1977,1(1):31-37
A method is presented here by which the actual numbers of individuals in the U.S. population who would be expected to suffer respiratory illness as a result of exposure to ambient nitrogen dioxide (NO2) concentrations in excess of the Federally-designated ambient air quality standard can be estimated. At the same time we have attempted to quantify how these adverse health effects would be alleviated by various degrees of reductions in current ambient concentrations. In addition, the health benefit expected to be derived by various NOx emission control strategies will be examined utilizing the health benefit estimation method presented.It is estimated that there were approximately 33.2×106 excess cases of respiratory illnesses in the U.S. in 1973 associated with ambient NO2 concentrations in excess of the national ambient standard. A reduction of approximately 50 to 60 percent below 1973 NO2 levels is needed to essentially eliminate excess respiratory illness associated with ambient NO2 concentration. 相似文献
227.
Alliances in winter flocks of willow tits; effects of rank on survival and reproductive success in male-female associations 总被引:1,自引:0,他引:1
Jan Ekman 《Behavioral ecology and sociobiology》1990,26(4):239-245
Summary The value of being dominant in winter flocks of willow tits may not only be a matter of personal survival for males, although their survival probability was highest among flock members. Winter flocks of willow tits contain male-female subunits, and the dominant pair may be viewed as an alliance based on mutual benefits. Dominant males provide their mates with protection in winter, and females return the help in reproductive success. Survival was directly related to rank only within sexes. Mates of dominant males survived significantly better than low-ranked males even though these females were subordinate to these males in direct interactions. Mates of dominant males were relatively spared from costs of low rank as they were subject to aggression less often than expected. Presumably dominant males prevented such attacks, as they excluded other flock members from high tree sections where their mates fed. Males should gain from improving the survival probability of their mates since it was not always possible to replace lost mates in spring populations having a male-biased sex ratio. Dominance in avian winter flocks may thus have more indirect effects than merely to improve the personal survival probability through resource priority. The benefits of being a dominant suggest that subordinate willow tits join groups because there is no space available for them to take up a territory as dominants. 相似文献
228.
Mature male dab (Limanda limanda) acclimated at 10° and 16°C were orally administered a single dose of 0.5 mg/kg 3,3′,4,4′-tetrachlorobiphenyl (CB77). At both temperatures, levels of cytochrome P450 1A (CYP1A) protein and 7-ethoxyresorufin O-deethylase (EROD) activity showed a two to six fold induction 40 days after CB77 treatment compared to control groups. Maximum responses of both EROD activity and CYP1A protein for the warm-acclimated fish were observed at 5 days after treatment. For the cold-acclimated fish a slow, progressive elevation for both EROD activity and CYP1A protein was observed and maximum responses were measured 40 days after treatment. Absolute EROD activity and CYPIA protein levels of fish from both temperatures were equally high at 40 days after treatment. Since in the control groups EROD activity and CYP1A protein levels were higher in the cold-acclimated fish, the magnitude of induction was higher in the warm acclimated ones. The highest concentrations of CB77 in muscle of fish from both temperatures were found at 5 and 10 days after treatment. The liver somatic index (LSI) showed 1.5 fold significantly higher values for the fish acclimated at 10°C. 相似文献
229.
Jan Müller 《Journal of Environmental Planning and Management》2004,47(5):757-771
The cost-benefit ratio of heathland maintenance measures was assessed in the Lueneburg Heath nature reserve in North-West Germany. This nature reserve contains large areas of heathland and is of substantial ecological and historical importance. The heathland can only be preserved by regular maintenance. For this assessment the costs of the maintenance measures were traced and a survey of visitors was carried out. The willingness-to-pay of the visitors for the heathland maintenance was determined as an assessment of the benefit created. Furthermore, the social acceptance of each maintenance measure was examined as this variable can influence the economic data considerably. These aspects represent a basis for the assessment of the net costs and benefits and for the calculation of the net present value (NPV) provided by the maintenance of the area. The results show a substantial positive net benefit of the heathland maintenance as a whole and varying acceptance of the different maintenance measures. 相似文献
230.
Removal of Phosphorus in Constructed Wetlands with Horizontal Sub-Surface Flow in the Czech Republic
Jan Vymazal 《Water, Air, & Soil Pollution: Focus》2004,4(2-3):657-670
The major processes responsible for phosphorus (P) removal in constructed wetlands with horizontal sub-surface flow (HSF CWs) are adsorption, precipitation and plant uptake if the biomass is harvested. The filtration materials frequently used in HSF CWs, i.e., gravel or crushed rock, provide only limited adsorption and plants are not regularly harvested. As a result, the removal of P in HSF CWs is usually low and typically amounts to only 40 to 60% during the treatment of municipal or domestic sewage. The average inflow and outflow P concentrations for vegetated beds of Czech HSF CWs were 6.6 mg L-1 and 3.6 mgL-1, respectively. The average P removal was 45.7%. Despite a wide fluctuation of inflow phosphorus loading rates in the Czech CWs (10.9 – 356 g P m-2 a-1) the retention of P is well predictable. The CWs in the Czech Republic are relatively new and therefore, it is not possible to evaluate long-time performance of P removal. However, results from systems that have been in operation for longer periods (maximum of 9 years) indicate that P removal decreases over years probably as a result of limited sorption capacity. The amount of P removed by aboveground Phragmites biomass is very low and usually does not exceed 5% of the total removed P in the beginning of operation. As the sorption decreases over years and macrophyte biomass increases at the same time the importance of P bound in biomass becomes higher but it rarely exceeds the level of 20% of the total P removed. 相似文献