乌鲁木齐大气混合层厚度和稳定度与大气污染的关系          下载免费PDF全文

李振杰  金莉莉  何清  缪启龙  买买提艾力·买买提依明 《干旱区地理》2019,42(3):478-491

利用乌鲁木齐市4座10层100 m梯度气象塔2013年6月~2014年4月气象观测资料和7个环境监测站[WTBX]AQI[WTBZ]资料，计算并分析了大气混合层厚度和稳定度特征，探讨了大气混合层厚度和稳定度与污染的关系。结果表明：乌鲁木齐市混合层厚度夏季郊区高、城区低，冬季从南郊—城区—北郊随地势降低依次降低；夏季和冬季分别在1 559～1 772 m和526～1 156 m之间。地面至2 km以上每500 m高度间隔统计混合层厚度，500～1 000 m出现频率最多；月变化为6～9月基本在500 m以上，且每个高度区间其概率均超过10%，10月～次年2月1 500 m以上区间概率明显减小；日变化为中午13:00～16:00达到最高值，下午和傍晚迅速下降。白天较大的感热输送提供充足的热力条件，这也体现出白天以不稳定层结为主，夜间则以稳定层结为主。大气稳定度分类结果，夏季郊区和城区不稳定（A～C类）所占比例差不多，冬季北郊稳定（E、F类）所占比较最大、城区最弱。[WTBX]AQI指数冬季最大，从南郊—城区—北郊依次增大，这与采暖期污染物多、南郊比北郊地势高有利于扩散输送有关。总体来看，乌鲁木齐大气混合层厚度空间分布与气象要素、大气稳定度、地形等密切相关，对AQI[WTBZ]指数分布有重要影响，这对近地层大气污染状况预报有着重要的指导意义。  相似文献   

The impact of northern Indian Ocean rivers on the Bay of Bengal using NEMO global ocean model     

Srivastava Atul  Gera Anith  Momin Imran M.  Mitra Ashis Kumar  Gupta Ankur 《海洋学报(英文版)》2020,39(3):45-55

The effect of river runoff over the northern Indian Ocean(NIO) especially over the Bay of Bengal(Bo B) has been studied using global Nucleus for European Modelling of the Ocean(NEMO). Two sensitivity experiments, with and without river runoff are conducted and the influence of river runoff on the Indian Ocean hydrography,stratification and circulation features are studied. It is found that due to river runoff surface salinity over the northern Bo B decreases by more than 5 and the East India Coastal Current strengthens by 2 cm/s during post monsoon season. The fresh river water reaches up to 15°N in the Bo B and is the main cause for low salinity there.Sea surface temperature in the northwestern Bo B increases by more than 0.2℃ due to the river runoff in summer monsoon while surface cooling upto 0.2℃ is seen in north-west part of Bo B in winter season. The seasonal mixed layer depth in the region is found to be dependent on river runoff. The effect of vertical shear and Brunt Vaisala frequency on stratification is also examined. The ocean water becomes highly stratified up to 3 035 m due to the river runoff. It is found that the energy required for mixing is high in the northern and coastal Bo B.  相似文献   

Precipitation variability assessment of northeast China: Songhua River basin   总被引：1，自引：0，他引：1  

Muhammad Imran Khan  Dong Liu  Qiang Fu  Muhammad Azmat  Mingjie Luo  Yuxiang Hu  Yongjia Zhang  Faiz M Abrar 《Journal of Earth System Science》2016,125(5):957-968

Variability in precipitation is critical for the management of water resources. In this study, the research entropy base concept was applied to investigate spatial and temporal variability of the precipitation during 1964–2013 in the Songhua River basin of Heilongjiang Province in China. Sample entropy was applied on precipitation data on a monthly, seasonally, annually, decade scale and the number of rainy days for each selected station. Intensity entropy and apportionment entropy were used to calculate the variability over individual year and decade, respectively. Subsequently, Spearman’s Rho and Mann–Kendall tests were applied to observe for trends in the precipitation time series. The statistics of sample disorder index showed that the precipitation during February (mean 1.09, max. 1.26 and min. 0.80), April (mean 1.12, max. 1.29 and min. 0.99) and July (mean 1.10, max. 1.20 and min. 0.98) contributed significantly higher than those of other months. Overall, the contribution of the winter season was considerably high with a standard deviation of 0.10. The precipitation variability on decade basis was observed to increase from decade 1964–1973 and 1994–2003 with a mean value of decadal apportionment disorder index 0.023 and 0.053, respectively. In addition, the Mann–Kendall test value (1.90) showed a significant positive trend only at the Shangzhi station.  相似文献   

Geospatial assessment of soil erosion intensity and sediment yield: a case study of Potohar Region,Pakistan   总被引：2，自引：0，他引：2  

Saleem Ullah  Amjad Ali  Muhammad Iqbal  Muhammad Javid  Muhammad Imran 《Environmental Earth Sciences》2018,77(19):705

Estimation of spatial extent of soil erosion, one of the most serious forms of land degradation, is critical because soil erosion has serious implications on soil fertility, water ecosystem, crop productivity and landscape beauty. The primary objective of the current study was to assess and map the soil erosion intensity and sedimentation yield of Potohar region of Pakistan. Potohar is the rainfed region with truncated and complex topography lying at the top of the Indus Basin, the world’s largest irrigation networks of canals and barrages. Spatially explicit Revised Universal Soil Loss Equation (RUSLE) Model integrated with Remote Sensing-GIS techniques was used for detecting/mapping of erosion prone areas and quantification of soil losses. The results show that the Potohar region is highly susceptible to soil erosion with an average annual soil loss of 19 tons ha^?1 year^?1 of which the maximum erosion (70–208 tons ha^?1 year^?1) was near the river channels and hilly areas. The sediment yield due to the erosion is as high as 148 tons ha^?1 year^?1 with an average of 4.3 tons ha^?1 year^?1. It was found that 2.06% of the total area falls under severe soil erosion, 13.34% under high erosion, 15.35% under moderate soil erosion while 69.25% of the area lies in the low (tolerable) soil erosion. Chakwal and Jhelum districts of the region are seriously affected by erosion owing to their topography and soil properties. The information generated in this study is a step forward towards proper planning and implementation of strategies to control the erosion and for protection of natural resources. It is, hence, necessary that suitable water harvesting structures be made to control water to prevent soil erosion and provision of water in the lean season in this region. Tree plantation and other erosion control practices such as strip cropping can also minimize soil erosion in this region.  相似文献   

Geology and Mineral Chemistry of Uranium- and Thorium-bearing Minerals in Rare-Metal (NYF) Pegmatites of Um Solimate,South Eastern Desert,Egypt     

Mohamed A. ALI  Ahmed E. ABDEL GAWAD  Mohamed M. GHONEIM 《《地质学报》英文版》2021,95(5):1568-1582

The garnet muscovite granitic pegmatite of Um Solimate, in southern Egypt, represents a promising asset for strategic and economic metals, especially Bi–Ni–Ag–Nb–Ta as well as U and Th. The ore bodies occur as large masses, pockets and/or veins of very coarse-grained pegmatites, which consist mainly of K-feldspar, quartz and albite with subordinate muscovite, garnet, and biotite. Radiometric data revealed that eU- and eTh-contents of the pegmatites reach up to 39 ppm and 82 ppm, respectively. The studied pegmatites are enriched in primary U and Th minerals (uraninite, coffinite, thorianite and uranothorite) as well as Hf-rich zircon and monazite, which give rise to anomalous radioactive zones. Niobium-tantalium-bearing minerals (i.e. ferrocolumbite, microlite and uranopyrochlore), xenotime, barite, galena, fluorite, and apatite are ubiquitous, and, consequently, the studied pegmatites belong tothe Niobium–Yttrium–Fluorine-type (NYF) family. The noble metal mineralization includes argentite (Ag2S), native Ni and Bi as well as bismite and bismoclite. In addition, beryl and tourmaline are observed in pegmatites near the contact with metasediments and ultramafic bodies. The observed compositional variations of Ta/(Ta+Nb) and Mn/(Mn+Fe) ratios in columbite (0.08–0.45 and 0.11–0.57, respectively) and Hf contents in zircon (3.54–6.46 wt%) may reflectan extreme degree of magmatic fractionation leading to formation of the pegmatite orebody.  相似文献   

A numerical technique for analysing pebble-form variations, applied in Loch Earn, Scotland     

JOHN MCMANUS  ALI H. A. ALRASOUL 《Sedimentology》1987,34(4):707-713

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Differentiation of environments of dolomite formation, Lower Cretaceous of Central Tunisia     

ALI M'RABET 《Sedimentology》1981,28(3):331-352

Combined field, sedimentological, mineralogical, isotopic and geochemical study of the Lower Cretaceous dolomites of Central Tunisia has demonstrated considerable diversity in origin. Environments of dolomite formation include deep phreatic, karst, lacustrine and evaporitic sabkha. All four groups of dolomite are composed of non-stoichiometric and/or disordered crystals which are more or less rich in calcium and in iron. Petrographic fabrics are of three types: replacement, recrystallization and cementation. These three fabrics are proposed among the various criteria for the different environments of dolomitization. Average isotope (δ¹⁸ O and δ¹³ C) contents for these four dolomite groups range from ?10·5 to +0·4%_o (PDB) and ?3·9 to + 3·7%_o respectively. The distribution of strontium is related both to the degree of recrystallization and to the palaeosalinity. Ferrous iron, also very common, is regarded as an indicator of relatively deep reducing conditions, mainly in meteoric groundwaters. Sodium distribution is related to inclusions within the dolomite, its distribution being relatively constant in all four groups; it cannot be regarded as a reliable criterion for palaeosalinity of dolomitizing fluids. This study confirms that dolomitization may occur under widely different palaeoenvironments, either at the surface or during burial. With the exception of the sabkha environment, dolomitizing fluids seem to have been essentially meteoric.  相似文献   

Source Sector Contributions to Aerosol Levels in Pakistan          下载免费PDF全文

Muhammad Zeeshaan SHAHID  LIAO Hong  QIU Yu-Lu  Imran SHAHID 《大气和海洋科学快报》2015,8(5)

Urban air pollution in Pakistan is a serious challenge and it causes significant damage to human health and ecosystems. This paper presents a modelling study using the Weather Research and Forecasting Model coupled with Chemistry(WRF-Chem) to simulate the spatial distributions and temporal variations of aerosol concentrations over Pakistan, focusing on contributions of domestic emission sectors(transport, industry, residential, and energy) to mass concentrations of sulfate(SO2–4), nitrate(NO–3), ammonium(NH+4), black carbon(BC), and organic carbon(OC) during the months of January, April, July, and October in 2010. Sensitivity studies indicate that, averaged over January, April, July, and October of 2010, energy and industry sectors have the largest contributions to SO2–4 concentrations, each of which contributes about 10%?20% to SO2– 4over the polluted eastern Pakistan. The contributions from residential and transport sectors to NO–3 concentrations reach 40%?50% in central Pakistan. The residential sector has the highest contribution of 50%–80% to BC and OC loading in northeastern and southern Pakistan. Examination of sector contributions to aerosol levels in Lahore, the most polluted city in Pakistan, suggests that reductions in emissions in the residential sector should be an efficient measure for improving particulate matter air quality in this region.  相似文献   

Unnoticed but important: revealing the hidden contribution of community-based religious institution of the mosque in disasters     

Abdur Rehman Cheema  Regina Scheyvens  Bruce Glavovic  Muhammad Imran 《Natural Hazards》2014,71(3):2207-2229

The role of community-based religious institutions has been largely undocumented, underestimated and overshadowed in the disaster studies literature. This paper explores the role of the mosque, a community-based religious institution, in disaster management by documenting and analysing its role in rural settings in the aftermath of the 2005 earthquake in Pakistan. The study examines the role of the mosque in relation to key actors from the state, civil society and private sector during response, relief, recovery, reconstruction and rehabilitation phases of the Pakistan earthquake. Using qualitative research methods and a case study design, this article analyses primary data collected through 5 months of fieldwork (in 2009 and 2010). The findings demonstrate the multifaceted and distinct contribution of the mosque in cultural, economic, social and political aspects of the lives of the earthquake-affected communities. Possible challenges to engagement with the mosque, both gender inclusiveness and political controversy around its role, are also raised. This research suggests that state, civil society and private sector actors involved in disaster management need to understand complex relationships involving people and their religious institutions, and their impact on the social dimension of recovery. The findings of the study contribute to the scarce knowledge about the role of community-based religious institutions including churches, mosques, synagogues and temples and call for engagement: that is, acknowledging and valuing their role for building a synergy between secular and religious efforts for disaster risk reduction and post-disaster recovery.  相似文献   

Integrated Biostratigraphy, Depositional Setting and Geochemical Analyses for Petroleum Potential Evaluation of the Lower Cretaceous (Barremian – Albian) Strata of the Koppeh-Dagh Basin, Northeastern Iran     

Sharifi MOHAMMAD  Foroughi FARIBA  Ghasemi-Nejad EBRAHIM  Shekarifard ALI  Yazdi-Moghadam MOHSEN  Sarfi MEHDI 《《地质学报》英文版》2019,93(6):1885-1899

The lower Cretaceous rock units of the Koppeh-Dagh Basin of northeastern Iran were investigated here in terms of biostratigraphy, depositional setting and geochemical analyses to find out if they, alike other parts of the world, are rich in petroleum. For this purpose, a stratigraphic framework is established using calcareous nannofossil and palynological elements. A nannoplankton zonation based on which subzones of the zones CC7 – CC8 of Sissingh(1977) and their equivalent NC6 – NC8 of Roth(1978) was established indicating a Late Barremian–Albian age. Palynological assemblages led us to establish the local palynozone of Odontochitina operculata. A dominantly marginal basin to a transitional zone between shelf and basin under a dysoxic–anoxic condition with low to moderate sedimentation rates coincided with a gradual sea level rise was introduced as the environment of deposition for the strata via interpretation of the palynological parameters and quantitative palynology. The obtained data from Rock-Eval pyrolysis in compilation with palynofacies analysis reveals that the studied succession contains mainly gas-prone type III kerogen. The Spore Coloration Index(SCI) alongside with the Rock-Eval pyrolysis results(low values of HI and TOC) proves that these rock units locally produced natural gas during the time under consideration.  相似文献