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81.
Conservation evaluation of nine Hong Kong mangals 总被引:1,自引:1,他引:0
A comparative analysis of the conservation value of nine Hong Kong mangals spread across Hong Kong has been undertaken. The analysis is based on both biological and socio-economic attributes. Biological attributes used in the analysis include plant species richness, benthic and arboreal gastropod species richness, occurrence of rare species within each site, and site representativeness. A review of the past and present development and development plans around and within each site has been undertaken to assess the comparative degree of hazard to each mangal. The drastic decline of mangal habitats throughout Hong Kong highlights the need for conservation of what remains today. Priorities and strategies for conservation of these nine mangals are discussed with particular emphasis on the preservation of biodiversity and the management of these habitats as education and research sites.Department of Applied Biology & Chemical Technology, Hong Kong Polytechnic 相似文献
82.
The Allodon River, a tributary of the Rhône, has suffered considerably from the recent expansion of human activities in the Geneva region. This study documents changes in its benthic fauna by comparing species richness before and after 1986 and by considering the possibilities of recolonization by drift.
Résumé L'Allondon, affluent du Rhône, est une rivière qui a considérablemen t souffert d'une expansion récente des activités humaines dans la région genevoise. Cette étude met en lumière l'évolution de certains éléments de la faune benthique en comparant les richesses specifiques avant et après 1986, année critique pour la macrofaune benthique du bassin genevois. Elle met en évidence les possibilités de recolonisation par dérive de certains recours de l'Allondon à partir d'affluents moins perturbés.相似文献
83.
A combined palynological and phytosociological methodological approach was used in the reconstruction of precultural forest vegetation in a small model area of Bílý Kí-Janík in the Moravskoslezské Beskydy mountains (northwest Slovakia). Two pollen diagrams show the predominance of Fagus sylvatica, Abies alba and Picea abies in past natural mixed forests. The present-day occurrence and distribution of forest herbs allow the differentiation of five past vegetation types with above mentioned forest climax trees covering the area before the beginning of human interference. A map of reconstructed natural vegetation is presented which can be used for revitalization of present secondary spruce plantations, heavily affected by air pollution. 相似文献
84.
在海拔3700m高原选择50名男性青年的体重、立定跳远、引体向上、仰卧起坐、60m和2000m跑速度6项指标进行高原移居青年体制综合评价方法的研究。通过用百分位法制定各项指标评分标准,以各项指标评分相加作为体质总分,并用各项指标的简单相关系数与多元逐步回归方程的标准化偏回归系数的乘积(贡献率)分配“权重”,建立综合评价总分的计算式:Y=0.05X1+0.16(X4+X6)+0.21(X2+X3+X 相似文献
85.
Richters Valda Elliott Gary Sherwin Russell P. 《In vitro cellular & developmental biology. Plant》1978,14(5):458-464
Summary The lungs of 12 mice, half of which were exposed to continuous 0.5 ppm nitrogen dioxide for 3 weeks, were explanted in culture,
and the instances of macrophage congregation were quantitated according to numbers of target cells involved, categories of
congregation from three to 11 or more, numbers of macrophages participating in each category for the total cultures, and the
influence of delaying explantation for 24 and 96 hr. A total of 9042 macrophages and 2140 epithelial and spindle target cells
were counted in the outgrowths from 306 explants. The incidence of macrophage congregation (or numbers of target cells) was
greater for the cultures from the NO2-exposed animals, both with respect to total incidences between groups (p→0), and the 0-hr (p<0.001) and 24-hr (p<0.01) culture
subgroups. In addition, the values for T3 to T6 macrophage congregation were individually and consistently greater for the exposed animal group. Postmortem interval stress
at 96 hr appeared to result in large colonies, but they were reduced greatly in number. Also the incidence of macrophage congregation
fell by 28% as compared to 0-hr and 24-hr subgroups.
Supported by Grants NHLI No. HL 17412 and EPA No. R. 800881. 相似文献
86.
Paul A. del Giorgio Alicia L. Vinocur Ruben J. Lombardo Hector G. Tell 《Hydrobiologia》1991,224(3):129-154
The phytoplankton of the River Lujan (Buenos Aires, Argentina) was studied for a period of 18 months, together with physical and chemical variables, in relation to a pollution gradient. 167 taxa were recorded within a seasonal succession characterized by dominance of diatoms with a brief summer green algae facies. A combination of several biotic indices and multivariate analysis was employed to assess the impact of pollution on the phytoplankton community. The biotic indices used were species diversity and richness, algal quotients (green algae/diatom ratio, Centrales/Pennales ratio) and the SD succession rate index. Multivariate procedures included cluster analysis and ordination by PCA of both species and samples, stepwise discriminant analysis and multiple discriminant analysis of variance (MANOVA). Results indicate that community dynamism is attenuated at the more polluted sites, concomitant with an increased predominance of a broad-tolerance algal assemblage, co-dominated by Cyclotella meneghiniana and Nitzschia stagnorum. The changes in the community structure and dynamics described herein involved alterations in the distribution and relative proportions of the algae, rather than modifications in the basic species composition. These changes may not be readily detectable by methods which over-simplify the ecological information, such as systems of indicator species and biotic indices, designed to assess the degree of pollution. The suitability of multivariate analysis and biotic indices in river phytoplankton studies is further discussed. 相似文献
87.
Elevated concentrations of Cu and Zn have been found in the upper part of three sediment cores collected from Llangorse Lake, in south Wales. Palaeomagnetic evidence from one of the cores and 210Pb analysis of another, suggests that the increase in sediment Cu and Zn concentrations began during the eighteenth century. A sharp increase in the concentrations of these metals in the sediment profile appears to have occurred during the latter part of the eighteenth century and these concentrations remained high until the mid to late nineteenth century.The absence of known ore deposits and industry around the lake suggests that the lake and catchment soils were increasingly contaminated by long-range aerial transport of emissions from the expanding activity of Cu and Zn smelters located some 80 km upwind in the Swansea area during the Industrial Revolution. Evidence from agricultural crop returns indicates a significant increase in the amount of land devoted to tillage in the catchment, particularly to cereal production, during the late eighteenth and the first half of the nineteenth century which included the Napoleonic Wars. This agricultural shift appears to coincide with increased concentrations of Cu and Zn in the lake sediments. It is suggested that newly ploughed soils, contaminated with metals for many years by long-range aerial transport from the Swansea area, eroded, and were carried into the lake by catchment run-off and added to the sediment burden of Cu and Zn. A subsequent decline of Cu and Zn emissions due to the collapse of the non-ferrous smelting industry and reduced soil erosion because of a 50% reduction of tillage due to an agricultural depression in the second half of the 19th century may explain the fall in Cu and Zn concentrations in the upper part of the sediment profile. The most recent sediments (20th century) show the increase in heavy metals characteristic of many lakes around the world. 相似文献
88.
Macrobenthic community structure before and after pollution abatement in the Neches River estuary (Texas) 总被引:1,自引:1,他引:0
Macrobenthos and physicochemical conditions in the lower 39 km of the Neches River estuary were studied from August, 1984 to May, 1985. The results were compared with data collected in 1971–1972. Between 1972 and 1984 the permitted BOD waste load in the tidal Neches River was reduced from 123 125 kg d to 8717 kg d. River discharge and dissolved oxygen concentrations were consistently higher and salinity was lower, during the same seasons, during the 1984–1985 study. A total of 50 taxa of macrobenthos were collected in 1971–1972 and 104 taxa were collected in 1984–1985. The numbers of taxa per collection at each station in 1984–1985 were at least twice those found in 1971–1972. Minimum densities in 1984–1985 were much higher than the maximum densities in 1971–1972 at all stations. Patterns of dominance, Sorenson's similarity index, and diversity (
) values indicated improved water quality in 1984–1985. Statistical analysis of macrobenthic diversity indicated significant differences between upper estuary and lower estuary stations in 1971–1972. No significant differences were found in 1984–1985. Significant differences in numbers of taxa, macrobenthos densities, and
values between the two studies were found. Reductions of waste loads, increased river discharge, and deepening of the navigation channel were among the factors that probably contributed most to the changes in community structure of the macrobenthos observed. 相似文献
89.
本文通过酸性紫色土和石灰性紫色土中不同浓度Cd、Cu、Pb、As对水稻根系脱氢酶的影响研究,揭示了脱氢酶受抑制与产生抗性的过程。在低浓度时,土壤Cd、Cu、Pb、As对脱氢酶的影响较敏感,能因元素的不同性质反映土壤类型影响的差别。最后,以脱氢酶受抑制与初始抗性峰出现的转折点相应的土壤浓度为依据,确定了两种紫色土Cd、Cu、Pb、As的临界浓度。 相似文献
90.
Results of semi-quantitative observations and quantitative sampling of seagrasses at coastal and offshore sites along the
western Arabian Gulf are presented. Overall seagrass cover (all species together) shows significant positive correlation with
latitude, but not with salinity, temperature or depth. The same pattern is shown by Halodule uninervis (Forsk.) Aschers., the dominant species. Mean seagrass biomass ranged from 53–235 g m-2 (dry weight). These values are comparable with biomass estimates from regions in which environmental conditions are generally
less extreme than in the Gulf. Seagrass biomass is significantly negatively correlated with depth and sediment grain size.
No significant correlation is apparent between seagrass biomass and factors such as season, salinity, or concentrations of
nutrients and heavy metals measured. It is pointed out that any correlations observed are not necessarily taken to imply causality. 相似文献