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421.
422.
Tao Zhen Shen ChengDe Gao QuanZhou Sun YanMin Yi WeiXi Li YingNian 《中国科学D辑(英文版)》2007,50(7):1103-1114
High-resolution sampling, measurements of organic carbon contents and 14C signatures of selected four soil profiles in the Haibei Station situated on the northeast Tibetan Plateau, and application
of 14C tracing technology were conducted in an attempt to investigate the turnover times of soil organic carbon and the soil-CO2 flux in the alpine meadow ecosystem. The results show that the organic carbon stored in the soils varies from 22.12×104 kg C hm−2 to 30.75×104 kg C hm−2 in the alpine meadow ecosystems, with an average of 26.86×104 kg C hm−2. Turnover times of organic carbon pools increase with depth from 45 a to 73 a in the surface soil horizon to hundreds of
years or millennia or even longer at the deep soil horizons in the alpine meadow ecosystems. The soil-CO2 flux ranges from 103.24 g C m−2 a−1 to 254.93 gC m−2 a−1, with an average of 191.23 g C m−2 a−1. The CO2 efflux produced from microbial decomposition of organic matter varies from 73.3 g C m−2 a−1 to 181 g C m−2 a−1. More than 30% of total soil organic carbon resides in the active carbon pool and 72.8%281.23% of total CO2 emitted from organic matter decomposition results from the topsoil horizon (from 0 cm to 10 cm) for the Kobresia meadow. Responding to global warming, the storage, volume of flow and fate of the soil organic carbon in the alpine meadow
ecosystem of the Tibetan Plateau will be changed, which needs further research.
Supported by the National Natural Science Foundation of China (Grant Nos. 40231015, 40471120 and 40473002) and the Guangdong
Provincial Natural Science Foundation of China (Grant No. 06300102) 相似文献
423.
北山古寺滑坡位于北山古寺旅游景区山坡处,第四系上更新统坡积残积土层中.通过对滑坡的发育特征及周边工程地质环境的调查,认为滑坡区的构造条件、地貌特征、地层岩性、水文地质条件是造成滑坡的内在原因,而暴雨与旅游开发则是滑坡发生的诱发因素.经评价,该滑坡体稳定性差(稳定系数小于1.35),故建议采取以滑坡后缘锚索,前缘和中段设置挡土墙,中轴设降水盲沟,周边设排水沟等工程措施为主,结合植树造林、工程管理等为辅的综合防治措施. 相似文献
424.
425.
中国云南东部晋宁、江川地区的伊迪卡拉(震旦)系顶部灯影组旧城段新发现了多样的宏体化石群,除了丰富的Vendotaenia与Tyrasotaenia类化石以外,以形体较大的Tawuia类和Longfengshaniaceae科等具固着构造的底栖多细胞藻类化石占据优势,另有一些形态奇特、亲缘关系不明的宏体化石,该组合与华南陡山沱组和灯影组石板滩段的宏体化石组合相比存在着明显的差别。依据形态特征,本文概述了部分产自江川旧城段的具有不同类型固着构造的底栖藻类和归属不明的宏体化石特征。华南滇东地区旧城段形态多样的宏体藻类化石的发现,进一步表明伊迪卡拉纪末期存在后生植物的多样化发展。这一时期浮游微生物和后生植物的共同繁盛可能为早寒武世“澄江生物群”的爆发奠定了生态基础。 相似文献
426.
我国炼焦煤资源丰富,但优质炼焦煤一直处于短缺局面。根据全国已有煤质数据分析,从优质(主要考虑挥发分指标)、环保(主要考虑硫分和灰分指标)两个方面结合有害微量元素含量,将炼焦煤划分为四种类型,确定了优质环保型炼焦煤资源的评价步骤,对全国五个赋煤区优质环保型炼焦煤的资源量等级进行了统计分析。 相似文献
427.
中国城市固体废弃物甲烷排放研究 总被引:2,自引:0,他引:2
The greenhouse effect of methane (CH4) is only inferior to that of carbon dioxide (CO2). As an important anthropogenic emission source, the calculation of the emission amount of CH4 from waste treatment in landfills plays an important role in compiling greenhouse gases inventory and in estimating the climate change effects caused by increasing of greenhouse gases. Based on the previous work, and according to the sampling and analysis on municipal solid waste (MSW) in typical cities, the degradable organic carbon (DOC) percentile was identified in typical cities in recent years. According to the IPCC greenhouse gases inventory guideline and default method of CH4 emission from MSW landfills, and in light of MSW managing situation in different regions, the amount of CH4 emission was calculated. The results show that the amount of CH4 emission decreases geographically from east to west and it increases temporally from 1994 to 2004 in China. 相似文献
428.
Comparison of Two Fading Filters anc Adaptively Robust Filter 总被引:1,自引:0,他引:1
YANG Yuanxi GAO Weiguang 《地球空间信息科学学报》2007,10(3):200-203
Two kinds of fading filters and their principles are introduced. An adaptive robust filter is given with corresponding principle. The basic abilities of the fading filters and adaptively robust filter in controlling the influences of the kinematic model errors are analyzed. A practical example is given. The results of the fading filter and adaptively robust filter are compared and analyzed. 相似文献
429.
A method to improve the alignment performance for GPS-IMU System 总被引:1,自引:0,他引:1
Zero velocity and zero east component of rotation rate relative to local geographic frame have been traditionally applied
as measurements for fine alignment of a GPS-IMU system. The performance of the fine alignment, however, will be affected by
several types of inertial sensor errors, which could cause part of the Kalman filter states to be unobservable. To overcome
this problem, a new method that utilizes the total outputs of the gyro triad and the accelerometer triad as part of the measurements
has been proposed by the authors. The initial results have confirmed the effectiveness of the method. In this paper, the observability
for both traditional and new alignment methods will be first reviewed. The results from computer simulations will then be
presented to compare the traditional and the new alignment methods for the purpose of evaluating the performance of the proposed
new method. Data acquired from real inertial sensors will also be applied to assess the traditional and new alignment methods
by analyzing their innovation sequences from the Klaman filter.
Based on a paper presented at the 18th International Technical Meeting of the Satellite Division of the Institute of Navigation,
Long Beach, California, September 2005. 相似文献
430.
The impacts of the seasonal and interannual SST variability in the East Asia coastal regions (EACRSST) on the East Asian summer monsoon (EASM) have been examined using a regional climate model (PδRCM9) in this paper. The simulation results show that the correlation between the EACRSST and the EASM is strengthened after the mid-1970s and also the variability of the EACRSST forcing becomes much more important to the EASM interannual variability after the mid-1970s. The impacts of the EACRSST on the summer precipitation over each sub-region in the EASM region become weak gradually from south to north, and the temporal evolution features of the summer precipitation differences over North and Northeast China agree well with those of the index of EASM (IEASM) differences.
The mechanism analyses show that different EACRSST forcings result in the differences of sensible and latent heat flux exchanges at the air-sea interface, which alter the heating rate of the atmosphere. The heating rate differences induce low level air temperature differences over East Asia, resulting in the differences of the land-sea thermal contrast (LSTC) which lead to 850 hPa geopotential height changes. When the 850 hPa geopotential height increases over the East Asian continent and decreases over the coast of East China and the adjacent oceans during the weakening period of weakens consequently. On the contrary, the EASM enhances during the strengthening period of the LSTC. 相似文献
The mechanism analyses show that different EACRSST forcings result in the differences of sensible and latent heat flux exchanges at the air-sea interface, which alter the heating rate of the atmosphere. The heating rate differences induce low level air temperature differences over East Asia, resulting in the differences of the land-sea thermal contrast (LSTC) which lead to 850 hPa geopotential height changes. When the 850 hPa geopotential height increases over the East Asian continent and decreases over the coast of East China and the adjacent oceans during the weakening period of weakens consequently. On the contrary, the EASM enhances during the strengthening period of the LSTC. 相似文献