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991.
Tatu Anttila Veli-Matti Kerminen Markku Kulmala 《Atmospheric environment (Oxford, England : 1994)》2002,36(39-40)
In this theoretical investigation, we elucidated several factors governing the ability of organic, water-soluble vapours to participate into either the secondary organic aerosol formation or particle condensational growth in the atmosphere. The corresponding requirements for physico-chemical properties of the vapour were estimated. These estimates were also compared with the properties of several difunctional carboxylic acids identified in the atmosphere. Our analysis indicates that while many of the considered compounds are expected to contribute to the total particle mass in the atmosphere, their role in particle condensational growth process remains uncertain. This uncertainty emerges from the fact that the saturation ratio of an organic vapour does not alone determine its ability to act as a “nonvolatile” compound. Instead, the hygroscopic and chemical properties of the vapour, as well as the particle pH and size, have also to be taken into account. 相似文献
992.
Calvo-Iglesias MS Fra-Paleo U Crecente-Maseda R Díaz-Varela RA 《Environmental management》2006,38(6):921-933
The aim of this work is the analysis of the dynamics in cultural landscapes, focused on the spatial distribution of changes
in land cover and landscape patterns, and their possible linkages. These dynamics have been analyzed for the years 1957 and
2000 in a sector of the north of Galicia (NW Spain) characterized with diverse landscapes. Afforestation processes linked
to agriculture abandonment and forestry specialization were the main processes observed in the study area, with the exception
of the southern mountainous sector that was dominated by ploughing of scrubland for conversion into grassland, reflecting
a specialization in livestock production. The structural changes that have taken place in most of the study area were related
to the heterogeneity aspects, although the mountainous sectors were characterized by changes in heterogeneity and fragmentation.
According to the tests performed, the comparison of the spatial distribution of both dynamics showed a certain statistical
significance, reflecting the interrelationship between patterns and processes. This approach could be useful for the identification
of areas with similar characteristics in terms of spatial dynamics so as to define more effective and targeted landscape planning
and management strategies. 相似文献
993.
The dynamics of yielding capacity of small cranberry (Oxycoccus palustris Pers.) were studied in three permanent sampling plots in a natural bog in southern Karelia for 28 years (1975–2002). The yield of berries varied from year to year from 1 to 179 g/m2 depending on phytocenotic and, to a greater extent, climatic factors. The proportion between the number of ripe berries and the number of flowers varied from 10 to 66%. No distinct periodicity in the abundance of fruiting was revealed.__________Translated from Ekologiya, No. 4, 2005, pp. 264–268.Original Russian Text Copyright © 2005 by Yudina, Maksimova. 相似文献
994.
A system dynamics model based on the dynamic interactions among a number of system components is developed to estimate CO(2) emissions from the cement industry in India. The CO(2) emissions are projected to reach 396.89 million tonnes by the year 2020 if the existing cement making technological options are followed. Policy options of population growth stabilisation, energy conservation and structural management in cement manufacturing processes are incorporated for developing the CO(2) mitigation scenarios. A 42% reduction in the CO(2) emissions can be achieved in the year 2020 based on an integrated mitigation scenario. Indirect CO(2) emissions from the transport of raw materials to the cement plants and finished product to market are also estimated. 相似文献
995.
Gurnell AM Morrissey IP Boitsidis AJ Bark T Clifford NJ Petts GE Thompson K 《Environmental management》2006,38(4):580-596
A conceptual model of the morphological development of the riparian margins of newly cut river channels is presented, suggesting
early feedbacks between vegetation growth and bank form. To test the model, observations of long and cross profiles, bank
sediment and seed deposition, and bank vegetation development were collected over the first 2 years of river flows through
a reach of the River Cole, West Midlands, UK. The newly created channel had a sinuous planform and varying asymmetric trapezoidal
cross section in sympathy with the planform. No imposed bedforms or bank reseeding were included in the design. Over the 2
years, development of bedforms was rapid, with bed sediment sorting and bank profile adjustment occurring more steadily and
progressively. Six classes of bank profile were identified by the end of the study period, illustrating close associations
with sediment aggradation, vegetation colonization, and growth patterns. Vegetation colonization of the banks was seeded predominantly
from local sources during the summer and from hydrochory (transport by the river) during the winter. Colonizing vegetation
on the riverbanks appeared to act as a significant propagule source by the second summer and as an increasingly important
roughness element, trapping both propagules and sediment, within the second year and providing early feedback into bank evolution.
As a result, the time required for riparian margin development in the conceptual model was found to be considerably longer
than observed in the study river. In addition, the role of surface wash/bank failure in modifying the bank profile and transporting
seeds onto the upper bank face during the first year of bank development was found to be important in initiating rapid bank
vegetation colonization and surface stabilization. This set of processes had not been incorporated in the initial conceptual
model. In relation to channel restoration, this research illustrates that in small temperate rivers of modest energy the provision
of an initial, sinuous corridor is sufficient to induce rapid development of fluvial features and vegetation cover without
the need to construct bed forms or to seed the banks. 相似文献
996.
M. R. Trubina 《Russian Journal of Ecology》2006,37(5):306-315
Specific features in the distribution of plant species differing in their attitude toward thermal conditions have been studied in communities of the present-day timberline ecotone on Mount Iremel’ in the Southern Urals. It has been shown that the distribution of such species is characterized by significant spatial nonuniformity. Elevation above sea level, local conditions in habitats located at the same altitudinal level, and specific features of mountain slopes account for 13–84, 5–30, and 0.4–14% of the total variance of test parameters, respectively. The abundance of plants changes nonlinearly along the altitudinal gradient, whereas changes in the species diversity of different plant groups have an almost linear pattern. Marked differences between plant communities with respect to the proportions of species differently responding to changes in thermal conditions have been revealed on all slopes in the upper part of the timberline ecotone, upon transition from the slopes proper to the plateau-like areas of intermontane depressions. 相似文献
997.
AXEL Thomas 《长江流域资源与环境》2006,15(5):649-649
Modelling landscapes with GIS provides a powerful tool to analyze and model terrestrial ecosystemsfor land use planning.In order to gainrealistic results,input data has to represent the natural environmentas realistically as possible.While some of the fun… 相似文献
998.
I. V. Tikhonova 《Russian Journal of Ecology》2007,38(5):306-310
The results of ten-year observations on fluctuations in the sex of individual trees and the sex structure of tree stands in two insular pine forests in the south of Central Siberia are presented. It is noted that the ratio of sex types of pine trees has markedly changed since 1998–1999. Significant correlations between the sex structure of stands and anomalies of the annual average air temperature have been recorded since the early 1990s. The male generative sphere of pine has changed to the greatest extent. Periodicity and delay in the change of shoot sexualization in response to changes in temperature are discussed. 相似文献
999.
E. L. Vorobeichik 《Russian Journal of Ecology》2007,38(6):398-407
Spatial variation in the cellulolytic activity of the soil microflora during the growing season (from May to September) has been studied in spruce-fir forests exposed to emissions from the Middle Ural Copper-Smelting Plant. It has been shown that the average rate of decomposition of pure cellulose in polluted areas is significantly reduced, with its spatial variation being markedly increased. The spatial pattern of cellulolytic activity remains stable during the growing season, and the integrated parameters of frequency distributions in zones with different pollution levels change with time in the same direction. 相似文献
1000.
WOLF R Dombrowsky 《长江流域资源与环境》2006,15(5):647-647
The contribution redefines the concept of“terra-forming”and the basically technical term“waterworks”froma sociological interpretation of metabolism:since human reproduction emancipatedfrom mereparticipation fromnature,it became,at least,a systematic transformation of nature.Irrigation and drain-age became the twin brothers of agriculture and mining,the most i mportant modifiers of both metabolismand natureitself.Fromthe early“hydraulic”toward modern“industrial”societies,the systemic co… 相似文献