低空急流与阿勒泰暖区大--暴雪   总被引：2，自引：0，他引：2  

晋绿生  赵俊荣 《沙漠与绿洲气象(新疆气象)》2004,27(2):13-15

分析了冬季产生新疆低空急流的大型环流特征及低空急流与阿勒泰暖区大-暴雪的关系。结果表明，在中高纬度欧亚范围内呈现“双阻型”，中亚中纬度高空维持纬向强急流锋区的情况下，若有巴尔喀什湖以南的暖湿气流向北输送，则有利于造成阿勒泰暖区大-暴雪的新疆低空急流产生。高低空急流的位置及强度可作为降雪量和大-暴雪落区的短期预报指标。  相似文献   

重金属迁移转化模型研究   总被引：14，自引：0，他引：14       下载免费PDF全文

何用  李义天 《水科学进展》2004,15(5):576-583

大量重金属污染物迁移转化的现象和研究成果都表明重金属以泥沙颗粒为载体迁移转化,描述重金属在天然水体中的迁移转化必须紧紧抓住泥沙颗粒运动及重金属与泥沙之间的转化关系进行.为此在对现有的重金属迁移转化数学模型进行概括分类的基础上,根据水沙运动与污染物相互作用关系,分析了泥沙颗粒运动及重金属吸附解吸不平衡过程,并结合水沙数学模型,建立了重金属迁移转化的耦合模型.同时在模型合理性分析的基础上,对模型进行了计算分析,分析表明模型能够合理地反映重金属污染物在水体中的迁移转化过程.  相似文献   

云南会泽超大型铅锌矿床成因研究中的几个问题   总被引：6，自引：0，他引：6  

黄智龙  李文博  张振亮  韩润生  陈进 《矿物学报》2004,24(2):105-111

位于川-滇-黔铅锌多金属成矿域中南部云南会泽超大型铅锌矿床可能是一种新的铅锌矿床类型，该类铅锌矿床明显特征是规模大、品位富、伴生有用元素多，暗示其成矿环境较为特殊。从成矿时代、成矿物质来源、成矿流体来源与演化，以及峨眉山玄武岩与成矿的关系等方面分析了会泽超大型铅锌矿床的研究进展及国内外研究现状，认为矿床成矿时代与西南大面积峨眉山玄武岩成矿时代相近，成矿物质和成矿流体具有“多源性”，成矿流体存在均一化过程，区域大规模流体运移在该区铅锌成矿过程中具有重要意义，峨眉山玄武岩岩浆活动与铅锌成矿具有密切的成因联系，矿床可能为“均一化成矿流体贯入成矿”的产物。  相似文献   

Transport of dissolved methoxy-nonafluorobutane through a saturated column     

Kenneth Y. Lee  Jeong-Yub Lee  James J. Mellett 《Environmental Geology》2004,46(6-7):883-889

Solute transport experiments were conducted in a one-dimensional saturated column using dissolved methoxy-nonafluorobutane (HFE-7100), a Novec engineered fluid developed by the 3M Corporation, as the solute. Novec engineered fluids are considered dense non-aqueous phase liquids (DNAPLs) because they are immiscible with water and have a specific gravity greater than one. The HFE-7100 fluid is safer and environmentally friendlier than common DNAPL contaminants such as tetrachloroethylene (PCE) or trichloroethylene (TCE); thus, it is an ideal substitute DNAPL for laboratory groundwater contamination research. Three sets of solute transport experiments were conducted. The first set of experiments was conducted in a glass-bead-packed column using dissolved HFE-7100 as the solute. The second set of experiments was conducted in a sand-packed column using dissolved HFE-7100 as the solute. The third set of experiments was conducted in a sand-packed column using dissolved PCE as the solute. The dissolved HFE-7100 column breakthrough concentrations were compared with dissolved PCE breakthrough concentrations. Results show that the one-dimensional solute transport equation was successful in describing the transport behavior of dissolved HFE-7100. This study demonstrates that the HFE-7100 fluid can be used as a safer substitute DNAPL for groundwater contaminant dissolution and transport research.  相似文献   

Environmental geochemistry of Zarshuran Au-As deposit, NW Iran   总被引：2，自引：1，他引：2  

Soroush Modabberi  Farid Moore 《Environmental Geology》2004,46(6-7):796-807

Zarshuran deposit is the most famous and important As-Au mine in Iran. However, there is no information on the impact of mining activity on the surrounding environment, especially on water systems. This paper attempts to document the concentration of arsenic and associated elements in waters and sediments resulting from the mining history of Zarshuran, a period covering hundreds of years. Water and sediment samples collected from Zarshuran Stream indicate high content of some potentially toxic elements, especially of As which ranges from 0.028 to 40 ng/l in water and 182 to 36,000 mg/kg in sediment samples. Mining activity, exposure of a large volume of mining wastes to weathering, and the anomalously high background of trace metals in the mining area are considered to be the main sources of heavy metal pollution.  相似文献   

Particularités de la contamination crustale des phonolites : exemple du Velay oriental (Massif central)     

Jean-Marie Dautria  Jean-Michel Liotard  Danièle Briot 《Comptes Rendus Geoscience》2004,336(11):971-981

Sr and Nd isotopic compositions of one trachyte, eight phonolites and five basalts have been measured. The isotopic characteristics of the trachyte can be explained by a combined assimilation–fractional crystallization process within an upper crustal magmatic chamber. Some phonolites display isotopic signatures identical to basalts, suggesting that they have been protected against any crustal assimilation during their formation. Some others have low Sr contents, whereas they are enriched in radiogenic Sr (0.70451<⁸⁷Sr/⁸⁶Sr_i<0.71192), and display basaltic ¹⁴³Nd/¹⁴⁴Nd ratios. Both observations could be explained by very strong alkali feldspar fractionation and by subsequent very low assimilation of surrounding rocks (between 0.3 and 4%) during intrusion. To cite this article: J.-M. Dautria et al., C. R. Geoscience 336 (2004).  相似文献   

Recent Environmental Change and Atmospheric Contamination on Svalbard as Recorded in Lake Sediments – an Introduction   总被引：1，自引：1，他引：1  

H.J.B. Birks  Vivienne J. Jones  N.L. Rose 《Journal of Paleolimnology》2004,31(4):403-410

This paper outlines an interdisciplinary project on recent environmental change and atmospheric contamination on the high Arctic archipelago of Svalbard (76°30′N–80°30′N). It describes the rationale and aims of the project and summarises the location, climate, geology, vegetation, and land-use of Svalbard.  相似文献   

The use of heavy metal concentrations and dendrochronology in the reconstruction of sediment accumulation, Ma a Panew River Valley, southern Poland     

Dariusz Ciszewski  Ireneusz Malik 《Geomorphology》2004,58(1-4):161-174

Heavy metal concentrations were investigated in overbank sediments of the Mala Panew River, southern Poland. Samples were collected from seven vertical profiles located within channel infills of a 20th century floodplain at three sites, each up to 50 m wide. In each profile, 15–24 samples were collected and analysed for Ba, Cd, Cu, Pb, and Zn. Sequential extraction of these elements was carried out in the 0.063-mm fraction of selected samples. Additionally, the age of the oldest trees growing close to the profiles has been used to estimate the initiation of sediment accumulation there. Ba, Cu, and Pb, which occur mostly in less mobile, moderately reducible, and residual fractions, were used for sediment dating. Zn and Cd, which in 50–75% occur in the mobile exchangeable fraction, were not suitable for dating. Correlation of Ba, Cu, and Pb concentrations in vertical profiles with changes in the load of effluents discharged to the river showed abrupt changes in the thickness of the strongly polluted sediments across the floodplains. A comparison of the relative changes between heavy metal peaks in sediments of similar age in the different profiles suggests a variable rate of downward metal migration. In general, none of the heavy metals investigated seems to have been mobilised within the stratigraphic layers above the water table. In layers located at stratigraphically lower levels, the Zn and Cd peaks seem to migrate several centimetres to several decimetres down in the profile. In profiles inundated for several weeks every year, Zn and Cd, as well as the relatively less mobile Ba, Cu, and Pb, have migrated downward by several decimetres. The investigation shows that frequent fluctuations of the water table have blurred the original depositional metal patterns of metal concentrations within a period of less than 40 years.  相似文献   

塔城市一次暴雪天气的分析     

唐秀李新东  刘妮娜庄晓翠 《沙漠与绿洲气象(新疆气象)》2005,28(3):14-15,18

2003年2月22日塔城市出现一次暴雪天气过程。文章着重分析了此次天气过程的高空环流形势、地面形势、T—Td等，指出暖湿气流是造成暴雪的主要原因。  相似文献   

Distribution of trace metals in the Odra River system: Water–suspended matter–sediments     

Edeltrauda Helios Rybicka  Ewa Adamiec  Urszula Aleksander-Kwaterczak 《Limnologica》2005,35(3):185-198

Extensive investigations of trace metals concentrations in water, suspended particulate matter (SPM) and bottom sediments of the whole Odra River system were carried out over the years 1997–2000. The vertical distribution of selected metals and their mobility were also studied in the sediment cores from upper and middle river sections. Significant levels of metal contamination were found. Median concentrations (Cd, Pb, Cu, Zn and As) in the SPM and sediments were (mg kg⁻¹) 7.1 and 8.9 Cd, 128 and 146 Pb, 81 and 119 Cu, 1198 and 1204 Zn, 48 and 54 As, respectively. The highest metal pollution of the Odra River solids was found with cadmium, zinc, lead and arsenic, showing high similarity in their frequency distributions in both SPM and sediments. Cd, Zn and As appear to be of particular concern because of the high levels, that appear to be bioavailable, and their high mobility. The exchangeable and carbonate chemical forms of Cd and Zn reached up to 50% of their total amount. Besides the determination of total metal concentration, the metal chemical forms in river solids were investigated. The results of very wide studies of the Odra River system through 4 years suggest that metal pollution decreased, especially for Zn, Pb and Cu. Among all metals studied in the Odra River sediments, substantial reductions of Cd contamination were observed neither in the period after ’97 flood, nor if compared with the earlier results obtained before ’97. No essential differences of the metal contents were observed among the samples for the same river compartment, from the same locality, taken within the five sampling campaigns. The pattern of spatial and vertical metal distributions in the river solids indicates that a variety of sources might be responsible for the contamination; very intensive, historical and current mining and smelting activities probably are the most important ones.  相似文献