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161.
162.
Seven carboxylic acids in rainwater were simultaneously determined using ion chromatography for 13 months in two different
sites, Guiyang and Shangzhong, southwest of China. Results showed formic, acetic and oxalic acids were the three predominant
carboxylic acids. Their volume-weighted average concentrations were 14.24, 9.35, 2.79 μmol/L in Guiyang and 4.95, 1.35, 2.31 μmol/L
in Shangzhong, respectively. A distinctive diurnal pattern in carboxylic acid concentrations (daytime>nighttime, t test, p < 0.05) was observed during the growing season in Guiyang. Shangzhong witnessed higher concentration of these acids during
the growing season than that during the non-growing season. Direct emissions from growing vegetation or soils probably account
for the main provenance of the acids in the rural area. However, the opposite trend were found in Guiyang and the anthropogenic
sources during the non-growing season were the main reason. By comparison of our result with the previous data about 20 years
ago, we calculated that at least 42% of acetic acids and 69% of formic acid originated from the anthropogenic sources in Guiyang.
Furthermore, the ratio of formate/acetate in gas phase larger than 1 suggest the oxidation of unsaturated hydrocarbons from
the human activity and/or natural sources were the main origin of carboxylic acids in Guiyang. While The F/A ratio in gas
phase was less than 1 in Shangzhong which indicate the direct emissions from biogenic sources. Oxalic acid was in similar
amounts in both sites, indicating the common source of the acid. 相似文献
163.
阿克苏河流域无站控制区地表水资源及可利用量评价 总被引:1,自引:0,他引:1
阿克苏河是"四源一干"中最大的源流,多年平均地表径流总量为80.6×108m3,入塔里木河水量34.2×108m3,占阿拉尔站以上3条源流输水量的73.5%,对塔里木河的形成、发展、演变和生态环境起着决定作用.无站控制区调查面积7 110 km2,占流域总面积的14.2%.2005—2007年对中国境内阿克苏河无站控制区主要19条河(沟)洪水水量、洪水沟基流和17条泉水水量野外调查计算,阿克苏河流域无站控制区间地表水资源总量为6.68×108m3.其中,洪水沟总洪量0.6050×108m3,洪水沟基流总量2.0569×108m3,泉水天然补给量4.0185×108m3.在6.68×108m3的地表水资源总量中,可利用量为3.2×108m3. 相似文献
164.
云南金宝山铂钯矿Sr-Nd-Os同位素组成:岩浆成因及演化分析 总被引:2,自引:0,他引:2
金宝山铂钯矿是峨眉山大火成岩省具有典型意义的岩浆Ni-Cu-PGE矿床,成矿岩体岩矿石Rb-Sr,Sm-Nd,Re-Os同位素特征表明:成矿岩浆为地幔柱成因并受到岩石圈地幔和地壳混染作用的影响。εNd(260 Ma)=-1.78~+0.81,介于地幔柱与岩石圈地幔之间但明显靠近地幔柱的同位素组成。γOs(260 Ma)=20~60,高于任何端元类型的地幔储集库,体现地壳混染作用的效果。模式分析认为,成矿岩浆形成演化过程中大约有10%的岩石圈地幔熔体混合并受到5%左右的下地壳混染。 相似文献
165.
集合卡曼滤波由于易于使用而被广泛地应用到陆面数据同化研究中,它是建立在模型为线性、误差为正态分布的假设上,而实际土壤湿度方程是高度非线性的,并且当土壤过干或过湿时会发生样本偏斜.为了全面评估它在同化表层土壤湿度观测来反演土壤湿度廓线的性能,特引入不需要上述假设的采样重要性重采样粒子滤波,比较非线性和偏斜性对同化算法的影响.结果显示:不管是小样本还是大样本,集合卡曼滤波都能快速、准确地逼近样本均值,而粒子滤波只有在大样本时才能缓慢地趋近;此外,集合卡曼滤波的粒子边缘概率密度及其偏度和峰度与粒子滤波完全不同,前者粒子虽不完全满足正态分布,但始终为单峰状态,而后者粒子随同化推进经历了单峰到双峰再到单峰的变化. 相似文献
166.
Located in the central Eurasian continent and far from oceans, northwestern China is characterized as an extremely dry environment
with much higher evaporation than the available precipitation. This area is one of the most severe, unique and typical arid
regions in the world. Therefore, this area is not only sensitive to regional climate changes, but may also be closely linked
to global change. Climate studies of this region are representative and have a typical significance. However, it is hard to
get a comprehensive understanding of the regional climate change because of the lack of meteorological records. Because of
its accuracy, continuity, high-resolution, variable measurement accuracy, sensitivity to climatic factors, wide distribution,
easy sampling and ease of obtaining a large volume of copies, dendro-science may be the perfect high-resolution climate index.
Currently, dendrochronology is widely used in various fields of past environment change. A lot of researches have been developed
around the Tianshan and Qilian Mountains. Dendroclimatology, dendroecology and dendrohydrology are applied in these areas.
With ring width and density, as well as isotope data, we can reconstruct past environment changes. Long-term chronologies
that developed from the middle Qilian Mountains and Qaidam Basin are important for learning paleo-climate change. Through
the dendro-science achievements in northwest China as the text introduced, we can see that dendro-science still has a long
way to go. This paper summarizes the tree-ring related studies since the early part of the last century in northwest China,
which may help give an overview of the dendrochronology studies in this area. 相似文献
167.
通过对乌鲁木齐市区域水文地质,实测水化学资料及前人有关地下水水化学研究成果,总结了市区地下水水化学变化规律,同时对1996-2000年乌鲁木齐市地下水环境质量状况进行了水文地质化学综合评价。结果表明,1996-2000年间乌鲁木齐地下水污染面积减少,污染程度减轻,水体质量好转,地下水环境状况有明显改善。这一结果与近年来政府环境保护政策的贯彻落实,及各部门采取的防止地下水污染措施密切相关。 相似文献
168.
169.
北京地区沙尘天气监测预报预警业务系统 总被引:3,自引:1,他引:3
在北京地区沙尘天气发生、发展的天气学分析研究和沙尘数值模式预报研究以及卫星遥感监测沙尘等方法的应用基础上 ,对相关的研究成果进行应用开发、集成 ,形成一套完整的业务系统。该系统由沙尘天气历史数据库、沙尘天气动态监测、沙尘天气概念模型、沙尘数值预报和沙尘天气预警 5个子模块组成。在近两年的北京市沙尘天气预报服务中 ,本系统得到充分的应用 ,提高了沙尘天气预报服务的效率 ,在实际业务中发挥了重要作用 ,可应用于气象业务部门及相关部门。 相似文献
170.
利用波形对比分析与多台到时对比的方法找出了流动台站记录的地震波形常规分析中存在的问题,提高了流动台资料的利用率。 相似文献