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Analysis of data characterizing the chemical composition of atmospheric precipitation was presented, with an emphasis on components responsible for neutralization of rain acidity. For this purpose, chemometric methods were applied. Based on a principal component analysis (PCA) a strong correlation between precipitation pH and potassium and ammonium ions in the heating period (October–March) and potassium and sodium ions in the non‐heating period (April–September) was observed. Additionally, a classification of eight variables, i.e., Na+, K+, Mg2+, Ca2+, , , Cl?, and according to their similarities was made using a cluster analysis. Based on this study, two ions, potassium and ammonium, together with the pH value were classified into one group (cluster) in the heating period while in the non‐heating period ions of potassium and sodium were clustered together with the pH. The results of the cluster analysis indicated that the selected ions contributed the most to the neutralization of the atmospheric precipitation acidity. This relationship was confirmed by a discriminant analysis in which potassium and ammonium ions were selected as components of the highest potential for precipitation classification according to its acidity degree. The relationship between the precipitation pH and the number of non‐precipitation days preceding the precipitation was also analyzed. It was found that although the observed an increase of the pH value was not very high, nevertheless, the effect of the duration of the period preceding the precipitation on the pH value recorded on the day of the precipitation occurrence was quite evident.  相似文献   

3.
基于小波变换和支持向量机的中国大陆强震预测   总被引:2,自引:1,他引:2  
将小波变换和支持向量机用于中国大陆年度最大地震震级预测。 先用小波变换把中国大陆年度最大地震序列分解成几个不同尺度水平(频率)的子序列, 然后使用支持向量机对分解后的子序列分别进行预测, 最后通过重构几个子序列的支持向量机预测结果得到最终预测结果, 预测次年中国大陆最大地震震级。 与支持向量机和神经网络方法对比, 结果表明小波变换和支持向量机相结合方法具有更高的预测精度, 预测效果很好, 说明此方法可用于地震时间序列预测。  相似文献   

4.
Global digital elevation models (DEMs) are an invaluable source of information in large area studies. Of particular interest are shuttle radar topography mission (SRTM) data that are freely available for the scientific community worldwide. Prior to any application, global datasets should be evaluated using reference data of higher accuracy. Therefore, the main objective of this study was to assess the accuracy of the SRTM C-band (version 4) DEM and SRTM X-band DEM of mountainous areas located in Poland and to examine the quality of data in relation to topographic parameters, radar beam geometry, initial voids in data and the presence of forest cover. A DEM from the Central National Geodetic and Cartographic Inventory, Poland, served as a reference. The study consisted of three steps: (i) the computation of vertical errors of the SRTM C- and X-band DEMs, (ii) the examination of any systematic bias in the data, and (iii) the analysis of the relationships between the elevation errors and terrain slope, aspect, local incidence angle, occurrence of voids and land cover. We found that the SRTM C- and X-band DEMs have mean errors equal to 4.31 ± 14.09 and 9.03 ± 37.40 m and root mean square errors equal to 14.74 and 38.47 m, respectively. Only 82 % of the C-band DEM and 74 % of the X-band DEM vertical errors had absolute values below 16 m. We found that the most important factors determining the occurrence of high errors were the distribution of initial voids and high slope angles for the C-band DEM, and local incidence angle, slope, aspect and radar beam geometry for the X-band DEM. In both cases, the presence of forest cover increased the mean error by approximately 10 m.  相似文献   

5.
Climate change and runoff response were assessed for the Tizinafu River basin in the western Kunlun Mountains, China, based on isotope analysis. We examined climate change in the past 50 years using meteorological data from 1957 to 2010. Results of the Mann-Kendall non-parametric technique test indicated that temperature in the entire basin and precipitation in the mountains exhibited significant increasing trends. Climate change also led to significant increasing trends in autumn and winter runoff but not in spring runoff. By using 122 isotope samples, we investigated the variations of isotopes in different water sources and analysed the contributions of different water sources based on isotope hydrograph separation. The results show that meltwater, groundwater and rainfall contribute 17%, 40% and 43% of the annual streamflow, respectively. Isotope analysis was also used to explain the difference in seasonal runoff responses to climate change. As the Tizinafu is a precipitation-dependent river, future climate change in precipitation is a major concern for water resource management.
EDITOR A. Castellarin; ASSOCIATE EDITOR S. Huang  相似文献   

6.
陈越  潘保柱  吴利  胡恩  赵耿楠  张森 《湖泊科学》2022,34(5):1630-1641
浮游动物作为食物链中重要的初级消费者,其群落结构特征是水生态系统健康评价的重要指标之一.本研究于2017年秋季和2018年春季对渭河干流及秦岭北麓五条典型支流开展了系统的水环境及浮游动物群落调查.结果表明,渭河干流营养盐浓度整体高于秦岭北麓支流,干流浊度远高于支流.两次调查共鉴定出浮游动物种类数136种(原生动物65种,轮虫44种,枝角类15种,桡足类12种),其中2017年秋季渭河干流浮游动物种类数、密度和生物量分别为14种、9.02 ind./L和0.0051 mg/L,秦岭北麓支流为37种、42.78 ind./L和0.0229 mg/L;2018年春季渭河干流浮游动物种类数、密度和生物量分别为52种、292.89 ind./L和0.1734 mg/L,秦岭北麓支流为68种、70.15 ind./L和0.0508 mg/L.秋季渭河干流下游浮游动物种类数、密度和生物量最低,而春季随上、中、下游三者均依次增大;秋季秦岭支流中罗敷河浮游动物密度和生物量最高,而春季灞河最高.春、秋两季干支流间浮游动物优势种差异较小,但秋季优势种种类数少于春季.秋季渭河干流中游Shannon-Wiene...  相似文献   

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A case study on the responses of streamflow to climate change in the Toutun River basin was carried out based on data analysis of streamflow, precipitation, and temperatures during the past 50 years.Temporal series of the streamflow change in the Toutun River basin was analyzed and tested using the Mann-Kendall nonparametric test. Results revealed that the annual runoff of the Toutun River had been in a monotonic decreasing trend for the past 50 years. Compared with the 1950s and 1960s, the annual runoff in the 1990s decreased by 4.0×105 m3 and 7.2×105 m3. The precipitation did not show monotonic trend during the past 50 years, but the annual temperature increased by 1.12℃ since the 1950s. Further data analysis indicated that the monthly runoff of the Toutun River decreased significantly from August to October, with precipitation displaying the similar pattern of seasonal change. Analysis suggests that the reduction of streamflow in the Toutun River basin is possibly caused by the seasonal change of precipitation, especially the precipitation reduction in summer, and temperature increases.  相似文献   

9.
A growing body of work is illuminating the importance of dust as a component of soil development and biogeochemical cycling in alpine environments of the Rocky Mountains. Nonetheless, important questions remain about the dust system in this region due to a paucity of focused studies and direct measurements. This project involved deployment of modified marble dust traps in the alpine zone of the Uinta Mountains of Utah to trap modern atmospheric dust over a two year period. Results indicate that dust accumulation rates are similar to values previously reported for the Wind River Range of Wyoming, but less than values for south‐western Colorado, suggesting a south‐to‐north decrease in regional dust flux. The overall mean grain size of Uinta dust is similar to values reported by prior studies in Colorado, indicating a general uniformity in grain size distribution. Uinta dust is dominated by quartz, plagioclase, K‐feldspar, and illite with trace amounts of kaolinite, chlorite, and amphibole. In contrast, only quartz and K‐feldspar are present in the Uinta bedrock, confirming an exotic origin for the dust arriving in the alpine zone. Exotic mineralogies have also been reported in dust from other mountain ranges in the western United States, indicating that eolian delivery of allochthonous minerals is a widespread process. Geochemical analysis reveals that Bi, Na, P, Zn, Sn, Cu, Cd, Ba, Ni, W, Sb, Pb, and Tl in Uinta dust are elevated 10 to > 80‐times above their abundances in local bedrock. These results support reports of anthropogenic elemental enrichment in lake sediments from Colorado and Utah. Patterns of elemental loading suggest that certain elements are delivered by winds arriving from different directions, raising the possibility that some elements could be associated with unique source areas. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

10.
Distribution of hydrous components in jadeite of the Dabie Mountains   总被引:1,自引:0,他引:1  
Two kinds of jadeite occur in the jadeite-quartzite from the Dabie Mountains, Eastern China: associated either with weak or strong deformation. The former shows a uniform composition while the latter shows both uniform and zoning composition. These jadeites were examined with infrared (IR) spectroscopy. All jadeite displays hydroxyl (OH) stretching bands, implying that hydrous components commonly exist in jadeite. The concentration of the hydrous components in the jadeite with weak deformation is homogenous, whereas the concentration of the hydrous components in strongly deformed samples is variable. The correlation between the intensity of OH-band absorbance and compositional zoning of jadeite with strong deformation indicates that Na-rich jadeite can accommodate more OH than Na-poor jadeite. Its interpretation is that there is more Na associated with greater OH availability in the initial crystallization environment. Our data of the comparatively high OH concentrations recorded in the core of the jadeite which contains relative high vacancies in M2 site imply that both OH content and the vacancies in M2 site could decrease during exhumation of the jadeite-quartzite. The decrease of OH solubility in jadeite would result in the formation of H2O fluid during the early exhumation of UHP metamorphic rocks. The H2O fluid transformed from OH during exhumation could trigger and enhance the early retrograde metamorphism of the host rocks and facilitate plastic deformation of jadeite grain by dislocation creep and diffusion creep.  相似文献   

11.
基于问卷调查法、统计学方法、情景分析法和专家分析法,根据单位应用标准情况、人员掌握标准情况、标准实施反馈情况设计调查问卷,开展地震标准实施情况调查评估。研究结果表明,地震行业存在对地震标准重视程度不够、普及不均衡等问题。针对存在的问题,提出加强地震标准宣贯力度、建立并执行地震标准清单制度、强化地震标准实施监督等建议,为促进地震标准的实施提供参考。  相似文献   

12.
Geology of the Grove Mountains in East Antarctica   总被引:2,自引:0,他引:2  
Grove Mountains consists mainly of a series of high-grade (upper amphibolite to granulite facies) metamorphic rocks, including felsic granulite, granitic gneiss, mafic granulite lenses and charnockite, intruded by late tectonic gneissic granite and post-tectonic granodioritic veins. Geochemical analysis demonstrates that the charnockite, granitic gneiss and granite belonged to aluminous A type plutonic rocks, whereas the felsic and mafic granulite were from supracrustal materials as island-arc, oceanic island and middle oceanic ridge basalt. A few high-strained shear zones disperse in regional stable sub-horizontal foliated metamorphic rocks. Three generations of ductile deformation were identified, in which D1 is related to the event before Pan-African age, D2 corresponds to the regional granulite peak metamorphism, whereas D3 reflects ductile extension in late Pan-African orogenic period. The metamorphic reactions from granitic gneiss indicate a single granulite facies event, but 3 steps from mafic granulite, with P-T condition of M1 800°C, 9.3×105 Pa; M2 800–810°C, 6.4 × 105 Pa; and M3 650°C have been recognized. The U-Pb age data from representative granitic gneiss indicate (529±14) Ma of peak metamorphism, (534±5) Ma of granite emplacement, and (501±7) Ma of post-tectonic granodioritic veins. All these evidences suggest that a huge Pan-African aged mobile belt exists in the East Antarctic Shield extending from Prydz Bay via Grove Mountains to the southern Prince Charles Mountains. This orogenic belt could be the final suture during the Gondwana Land assemblage.  相似文献   

13.
Origin of the Kunlun Mountains by arc-arc and arc-continent collisions   总被引:12,自引:0,他引:12  
Abstract The Kunlun Mountains were formed by early Mesozoic arc-arc and arc-continent collisions. The Middle Kunlun Are was the outer volcanic arc of the Paleozoic Asiatic continent, and the arc-related magmatic activities from the Proterozoic to Mesozoic are recorded by numerous volcanic and plutonic rocks of the area. Several back-arc basins and relic arcs exist north of the arc and the north Kunlun arc is one of these. The Kudi mélange of Kunlun was formed in a south-dipping subduction zone when the basin between the north and middle Kunlun arcs was consumed by the process of back-arc basin collapse, and the ophiolite mélange marked the suture zone where the two arcs collided. The Mazar mélange was formed in the north-dipping subduction zone under the middle Kunlun arc, and the mélange marks the main Paleotethys suture where the Qogir-Karamilan rocks of the Qangtang block (a fragment of Gondwanaland) is sutured on to Laurentia. The geology of Kunlun emphasizes the importance of arc-arc and arc-continent collisions in mountain-building processes.  相似文献   

14.
Strain analyses for the Shuanghe pluton show that the main strain planes suffered distinct deformation. The main strain value (XZ) is up to 1.59-2.18, and the value of Flinn index (K) ranges from 0.11 to 0.82. Anisotropy of magnetic susceptibility (AMS) measurements reveal that the orientations of the magnetic foliation and lineation gently dip SE, consistent with the macroscopic foliation of the pluton. The value of anisotropy degree (P) ranges from 1.109 to 1.639, and the shape parameter (7) from 0.079 to 0.534. These studies prove that the pluton was deformed under strong compression. Quartz c-axis textures, defined by monoclinic or triclinic asymmetry, usually developed the high maxima paralleling the b-axis, which is defined by the developed in the high-ultrahigh pressure rocks (UHP) which were captured in the pluton or country rocks. It is concluded that the Shuanghe pluton emplaced under regional compression slightly after the formation of UHP, and it is characterized by synkinematic granitic deformation.  相似文献   

15.
In this article the properties of regularized kriging (RK) are studied. RK is obtained as a result of relaxing the universal kriging (UK) non-bias condition by using the support vectors methodology. More specifically, we demonstrate how RK is a continuum of solutions in function of the regularizing parameter, which includes as particular and extreme cases, simple kriging (SK) and UK, and as an intermediate case, Bayesian kriging (BK). Likewise, expressions are obtained for the mean, variance and mean squared error (MSE), as also the expression for the corresponding estimator of the coefficients of the mean. Finally, we investigate the relationship between RK and the support vector machines. By means of simulations we compare the MSE for RK with those for BK and UK, for different association models, for different levels of noise, and for differently sized mean coefficients. The RK results prove to be an improvement on the UK and BK results, and, moreover, these improvements are proportionally greater for greater levels of noise.  相似文献   

16.
王晨晖  刘立申  任佳  袁颖  王利兵  陈凯男 《地震》2020,40(3):142-152
为有效解决地震伤亡人数预测所需影响因子多、运算量大、模型训练烦琐等问题,构建了主成分分析法(PCA)和遗传算法(GA)优化的支持向量机(SVM)模型,采用PCA对地震伤亡人数影响因子进行降维以去除贡献率较低的主成分,将贡献率较大的主成分作为支持向量机的输入变量,以地震伤亡人数作为输出变量,利用GA对SVM模型性能参数进行优化,建立基于PCA-GA-SVM的地震伤亡人数预测模型,并对测试样本进行预测,结果表明:与SVM模型、 GA-SVM模型和PCA-GA-BP模型相比, PCA-GA-SVM模型的预测准确率和运行效率分别提高4.73%、 1.14%、 9.99%和47.05%、 36.76%、 44.55%。结果显示, PCA-GA-SVM模型预测精度高,泛化能力强,能够科学合理地对地震伤亡人数作出预测。  相似文献   

17.
5.12汶川8级大地震表明龙门山断裂带仍然是一个构造活动带,为了达到防震减灾的目的.对其进行深入研究是很有必要的。通过龙门山北段毛坝一竹园坝实测构造地质剖面.分析野外实测构造的变形特征.根据变形强弱差异,将毛坝一竹同坝之问分为4个构造变形带,并总结各个构造带的变形特征以及变形序列。在野外研究基础上.首次提出竹园坝断裂.并指出竹园坝断裂是龙门山前山带的主干断裂之一,是喜马拉雅山运动的直接结果。最后.再结合前人资料讨论龙门山北段的构造演化。  相似文献   

18.
Based on GPS measurements conducted from 1992 to 2006, we present the current crustal movement velocity field for approximately 400 sites in the Tianshan Mountains and their adjacent areas, and estimate slip rates on the major faults using a 2-D elastic dislocation model. Our studies show slip rates within the range of 1―4 mm/a on the NW-SE trending strike-slip faults (such as Talas-Fergana fault) in the Tianshan Mountains. We also found the slip rates on the approximately WE-SN trending gently-dipping detachment fault vary from 10―13 mm/a for the southwest Tianshan Mountains to 2―5 mm/a for the eastern Tianshan Mountains, and to 6―12 mm/a for the Kyrgrz Tianshan. The GPS velocity field reveals that the total convergence is not uniformly distributed across the Tianshan Mountains, with 80%―90% of the N-S shortening absorbed along the southern and northern edges, and relatively little deformation accommodated within the interior. This first-order feature of strain pattern is explained best by underthrusting of adjacent blocks beneath the Tianshan Mountains along a basal detachment fault. We found the occurrence of historical M7―8 earthquakes somewhere in the locked ramp that connects the creeping and locking segments of the detachment, thereby resulting in elastic strain concentration and accumulation around it. The elastic strain confined in the upper crustal layer above the detachment ultimately releases through infrequent great earthquakes in the Tianshan Mountains, resulting in considerable folding and faulting at their margins. The Tianshan Mountains propagated outward and rose progressively as a wedge-shaped block.  相似文献   

19.
Yan Liu  Jianhui Xu  Xinyu Lu  Lei Nie 《水文研究》2020,34(12):2750-2762
Due to limitations in transport and communication infrastructures and difficulties in accessing glaciers, it is challenging to monitor snow and glaciers. In this study, the enhanced Utah Energy Balance (UEB) with a glacier melt model and snow above and below the forest ablation algorithm is used to assess the contributions of snow and glacier melting in three typical inland river basins (MRB, URB and KRB) in the middle Tianshan Mountains of China from 2002 to 2014. Forced by the spatial downscaling of the China meteorological forcing dataset (CMFD) coupled with other parameters, the model simulates the total surface water balance using surface water input from snowmelt, glacial melt and rainfall. Model simulations reveal that although the MRB, URB and KRB are all located on the northern slopes of the Tianshan Mountains, there are obvious differences in their water resource composition characteristics. Different from the URB, which is mainly replenished by glacial melt and had an average annual percentage of glacial melt of approximately 39% of the total surface water from 2009 to 2014, the MRB and KRB are mainly supplied by snowmelt and rainfall and both had an average annual percentage of snowmelt of approximately 37%. Although snowmelt is an important source of water to inland rivers, especially during the snowmelt season, the contributions of snowmelt in these three basins are very small especially for the URB, which had a contribution of 17%. This study effectively verifies the applicability of the CMFD and provides important scientific and technological support for determining the spatiotemporal variations in snow and glacial melt in the middle Tianshan Mountains, where meteorological observation data are scarce and some observational data, such as radiation data, are incomplete.  相似文献   

20.
鄱阳湖乐安河流域水质监测优化布点   总被引:4,自引:0,他引:4  
采用鄱阳湖乐安河流域13个监测断面1995-2002年8年的污染指标的监测平均值作为原始数据,应用物元分析法对各监测断面进行优化.在确定最佳和最次理想点的基础上,建立标准物元矩阵和节域物元矩阵,并结合综合关联函数,选出优化点位.同时应用相关分析中的距离分析和K-均值聚类法确定各监测点所属类别.综合这三种优化结果,最终确定乐安河流域可以由传统的13个监测点位优化为9个监测点位.  相似文献   

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