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61.
本文通过对地形通视分析的基本设想的描述及其实践途径中有关问题的探讨,结合实例阐明了计算机自动进行通视分析的基本方法和处理技巧,并附有具体程序。 相似文献
62.
The status of the ecological environment and a proposed protection strategy in Sanya Bay,Hainan Island,China 总被引:8,自引:0,他引:8
Huang L Tan Y Song X Huang X Wang H Zhang S Dong J Chen R 《Marine pollution bulletin》2003,47(1-6):180-186
Sanya Bay encompasses a high diversity of natural habitats, ranging from coral reefs, rocky and sandy shores and mudflats to mangroves. Seasonal physicochemical and biological investigations were conducted from 1998 to 1999 and again in April 2000. Water-related environmental quality in Sanya Bay is in good condition. The levels of dissolved oxygen, nitrogen, phosphorus and heavy metals are within the first class of National Seawater Quality Standards for China. Annual mean values of chlorophyll a of 0.93 mg m(-3) and phytoplankton primary productivity of 440.8 mgC m(-2)d(-1), respectively, were found in the waters, both of which show a significant correlation with inorganic nitrogen. A mean new productivity of 144.6 mgC m(-2) d(-1) was recorded in summer. Sanya Bay is rich in natural resources and biodiversity with 235 species of phytoplankton and 129 species of zooplankton identified in the survey. The annual mean abundance of phytoplankton and zooplankton were 1564 x 10 cells m(-3) and 121 individuals m(-3), respectively, with an annual mean zooplankton biomass of 129 mg m(-3). A total of 243 species of fish were sampled in the survey including many of high economic value. Three hundred and eighty-four species of benthos in 121 families were found by mud sampling and trawling. The average biomass of benthic organisms was 11.55 gm(-2), with a density of 31 individuals m(-2). Molluscs were the dominant group, followed by crustaceans; coelenterates exhibited the lowest biomass. One hundred and twenty-six species from 48 families of intertidal organisms were collected by frame sampling, with a mean annual biomass of 644.7 gm(-2) and average density of 816 individuals m(-2). The highest biomass of 1673.5 gm(-2) was collected in a coral reef region, while the highest density of 1219 individuals m(-2) occurred in a mangrove region. The coastline is characterized by coral reefs that accounts for 30% of the total coastline length in the bay, so coral reefs are a key ecosystem that are important for maintaining the regional marine resources and biodiversity. We need to pay much more attention to such diverse marine resources to maintain the integrity and function of these coastal ecosystems. 相似文献
63.
断陷湖盆隐蔽油藏预测及勘探的关键技术--高精度地震探测基础上的层序地层学研究 总被引:82,自引:6,他引:76
近十余年世界的我国隐蔽油藏勘探取得了巨大进展,其关键技术是高精度的三维地震及在此基础上的层序地层学研究,二者的结合已被油气产业部门当作勘探中的“权威性技术”。断陷湖盆在我国东部含油气资源的重要性居首位,控制层序形成演化的诸因素中,构造,古气候和在区域古地理格局中的位置对湖盆的类型和演化起着决定作用,需要按照断陷湖盆的沉积构造演化特征建立有预测功能的层序构成模式,在成熟的勘探区,重新建立等时层序地层格架,进行体系域精度的工业制图,阐明沉积体系的分布规律,使用高精度地球物理技术对圈闭定位,并对构造坡折带和低位域扇体给予重点注意,用这种技术方法指导隐蔽油气藏的勘探,已经并必将有许多重要发现。 相似文献
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Several studies have suggested that geostatistical techniques could be employed to reduce overall transactions costs associated
with contracting for soil C credits by increasing the efficacy of sampling protocols used to measure C-credits. In this paper,
we show how information about the range of spatial autocorrelation can be used in a measurement scheme to reduce the size
of the confidence intervals that bound estimates of the mean number of C-credits generated per hectare. A tighter confidence
interval around the mean number of C-credits sequestered could increase producer payments for each hectare enrolled in a contract
to supply C-credits. An empirical application to dry land cropping systems in three regions of Montana shows that information
about the spatial autocorrelation exhibited by soil C could be extremely valuable for reducing transactions costs associated
with contracts for C-credits but the benefits are not uniform across all regions or cropping systems. Accounting for spatial
autocorrelation greatly reduced the standard errors and narrowed the confidence intervals associated with sample estimates
of the mean number of C-credits produced per hectare. For the payment mechanism considered in this paper, tighter confidence
intervals around the mean number of C-credits created per hectare enrolled could increase producer payments by more than 100
percent under a C-contract. 相似文献
66.
TAN Jingjing HUANG Diying REN Dong 《《地质学报》英文版》2007,81(5):688-696
Three new fossil species of the genus Mesocupes of fossil cupedids,M.angustilabialis sp. nov.,M.latilabialis sp.nov.and M.collaris sp.nov.,are described from the Jiulongshan Formation of Inner Mongolia,China.These new species are the first three records of fossil Mesocupes in China as well as the oldest ones in the world now.This finding also extends the geographical distribution of this genus from Central to East Asia.In addition,based on the ratio of the length of the last to the penultimate abdominal ventrites of new beetles distinctly lower than that of the species from the Karabastau Formation,the age of Daohugou fossil-bearing beds might be older than that of Karatau assemblage and consequently of Middle Jurassic. 相似文献
67.
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69.
Regional land use change is the main cause of the ecosystem carbon storage changes by affecting emission and sink process.However,there has been little research on the influence of land use changes for ecosystem carbon storage at both temporal and spatial scales.For this study,the Qihe catchment in the southern part of the Taihang Mountains was taken as an example;its land use change from 2005 to 2015 was analyzed,the Markov-CLUE-S composite model was used to predict land use patterns in 2025 under natural growth,cultivated land protection and ecological conservation scenario,and the land use data were used to evaluate ecosystem carbon storage under different scenarios for the recent 10-year interval and the future based on the carbon storage module of the In VEST model.The results show the following:(1) the ecosystem carbon storage and average carbon density of Qihe catchment were 3.16×107 t and 141.9 t/ha,respectively,and decreased by 0.07×107 t and 2.89 t/ha in the decade evaluated.(2) During 2005–2015,carbon density mainly decreased in low altitude areas.For high altitude area,regions with increased carbon density comprised a similar percentage to regions with decreased carbon density.The significant increase of the construction areas in the middle and lower reaches of Qihe and the degradation of upper reach woodland were core reasons for carbon density decrease.(3) For 2015–2025,under natural growth scenario,carbon storage and carbon density also significantly decrease,mainly due to the decrease of carbon sequestration capacity in low altitude areas;under cultivated land protection scenario,the decrease of carbon storage and carbon density will slow down,mainly due to the increase of carbon sequestration capacity in low altitude areas;under ecological conservation scenario,carbon storage and carbon density significantly increase and reach 3.19×107 t and 143.26 t/ha,respectively,mainly in regions above 1100 m in altitude.Ecological conservation scenario can enhance carbon sequestration capacity but cannot effectively control the reduction of cultivated land areas.Thus,land use planning of research areas should consider both ecological conservation and cultivated land protection scenarios to increase carbon sink and ensure the cultivated land quality and food safety. 相似文献
70.