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1.
分析榆林市城区春季环境空气污染特征,选取榆林市红石峡(J1)、环保监测大楼(J2)、实验中学(J3)、世纪广场(J4)4个大气自动监测点,分别进行 PM10与 PM2.5的分析。结果表明,与国内其他大中型城市相比,榆林市PM10、PM2.5为轻度污染,ρ( PM2.5)/ρ( PM10)小于50%,属于粗颗粒物污染型;4个监测点 PM10和 PM2.5的日均浓度变化趋势基本一致,呈波峰、波谷变化,但浓度在区域分布上表现略有差异;小时浓度均呈现较明显的双峰变化趋势,上午和夜间各出现一个峰,而下午浓度变得相对较低。  相似文献   

2.
Water soluble components of PM10 Chongqing, China   总被引：1，自引：0，他引：1  
The concentrations of water soluble ions (Na+, NH4 +, K+, Mg2+, Ca2+, NO3 -, Cl-, and SO 4 2- ) in PM10 samples collected on cellulose filters by a medium-volume cascade impactor were determined, which were obtained from three kinds of areas in Chongqing: industrial area (Jiulongpo district), commercial and residential area (Jiangbei district) and background area (Jinyun Mountain in the Beibei district). The results showed that except for the background site, the annual average values of PM10 are 23% – 61% higher than the national air quality standard (GradeII) (0.1 mg/m3), even that the value of the control site is still 20% higher than American standard (0.05 mg/m3). This implied that serious pollution of fine particles occurred in Chongqing. Nine kinds of soluble ions in water of PM10 were analyzed by ion chromatography (IC) and the annual average concentrations follow the order of [SO 4 2- ] > [NO3 -] > [Cl-] > [F-], and [Ca2+] > [NH4 +] > [K+] > [Na+] > [Mg2+]. Their values were different in these areas: the industrial area > the commercial and living area > the control area. As for NH4 +, K+, Ca2+, NO3 - and SO 4 2- , their seasonal average concentrations show a similar variation trend: the values in spring and fall were higher than those in summer and winter. The seasonal average concentrations of [Cl-], [F-], [Na+] and [Mg2+] are much lower than those of other ions. However, the concentrations of [Na+] changed more greatly in different seasons than those of the other three ions. Correlation coefficients showed that the three areas have been polluted by coal smoke and dust to different extents, while some local resources of pollution should be taken into consideration as well.  相似文献   

3.
Nineteen trace metals in PM10 were measured by X-ray fluorescence spectroscopy （XRF） at three sites in Chongqing. The special and seasonal variations of trace metals in PM10 samples collected in the downtown were different from those in the background area of Jinyunshan. The source identification indicated that particulate materials were contributed mainly by two sources.  相似文献   

4.
为了解元素(尤其是重金属元素)在不同粒径大气颗粒物中的分布规律、污染特征及来源,于2016年在石家庄市采集PM1、PM2.5和PM10样品。利用等离子体质谱仪(ICP-MS)测定了Al、Ti、V、Cr、Mn、Fe、Cu、Zn、As、Sb、Hg、Pb和Cd共13种元素的质量浓度,采用富集因子(EF)法分析各种元素在PM1、PM2.5和PM10中的分布特征,并通过主成分分析法讨论了这些元素的主要来源。富集因子分析显示出Al、Fe、Ti、Mn受人为因素影响较少(EF<10),其他元素则出现显著至极强的人为影响,尤其是Cd元素(EF>103),并发现颗粒物粒径较小时,富集因子较大,即人为因素影响更重。主成分分析表明：PM1中元素有工业冶炼及燃煤活动、机动车燃油排放、生活燃煤3个来源,PM2.5中元素有地壳源、电厂及居民生活燃煤、金属冶炼等工业活动、机动车尾气4个来源,PM10中元素有化石燃料燃烧和地壳源、与机动车相关的道路扬尘及工业尘、垃圾焚烧及机动车排放与磨损、燃煤活动4个来源。  相似文献   

5.
介绍了构成空气污染的最主要来源大气矿物质颗粒物PM10～2.5。通过分析PM对生物体内细胞的各种生化作用、自由基及尘载微生物毒性的研究,结合动物实验和流行病学调查,阐述PM的危害机理。指出目前对PM2.5以及更细的颗粒物如纳米物质的生物活性与效应研究较少,未把PM自身特性的生物响应纳入研究内容,尚未建立细颗粒物对生物机体(如微生物和低等植物)危害的总体结果与评价;今后应从界面反应等多因子重点揭示其毒理学机理,以多学科对PM生物活性和生态毒性进行深入研究。  相似文献   

6.
1Introduction Particleswithanaerodynamicdiameterof< 10μmarerecognizedasinhalabaleparticlesandhave beenfoundtobewidelyassociatedwithhealthprob lems(Chapmanetal.,1997).Theywouldalsoinflu enceclimateandvisibilitythroughanumberofimpor tantatmosphericprocesses(Horvath,1993). Rapiddevelopmentofurbanconstructionandrap idgrowthofpopulationhaveexacerbatedChongqing’s pollution.Althoughsulfurdioxidehasbeenreducedby morethan60%incontrasttothevaluein1991,the concentrationsofparticulatematterarestil…  相似文献   

7.
本次工作以四川省绵阳市颗粒物(PM_(2.5)和PM_(10))污染变化特征为研究对象,利用绵阳市国控监测站结合西南科技大学自建监测站获得的PM_(2.5)、PM_(10)质量浓度数据,对2017年9月至2018年9月期间绵阳市城郊PM_(2.5)和PM_(10)质量浓度进行了分析,探讨了两者的季节变化和日变化,以及两者之间的相关性,阐释了污染颗粒的可能来源,并对比了城区与郊区的日变化差异。结果表明,绵阳市PM_(2.5)、PM_(10)质量浓度季节间差异较大,污染程度整体上呈现冬季春季秋季夏季的特征,冬季灰霾天数最多,人为排放、地形和天气为主要影响因素。PM_(2.5)和PM_(10)质量浓度具有良好的线性关系,相关系数为0.8771。颗粒物质量浓度郊区整体低于城区,城区相对郊区变化更为平稳,但郊区受扬尘影响程度高。  相似文献   

8.
<正>由于近十几年中国工业化扩张、城市化及经济增长速度加快,全国范围内灰霾事件越来越多的受人关注,特别是经济发达并且人口稠密的长江三角洲、珠江三角洲以及京津唐地区。亚洲发展报告提供的资料显示,中国500个大城市中只有1%的城市空气质量达到世界卫生组织发布的标准。频发的灰霾事件引起人们对健康的关注的同时,也引起中国政府对治理空气质量的重视。耶鲁-南京信息工程大学大气环境中心研究团队首次报道了中国190个城市PM2.5(直径小于2.5微米的颗粒物)污染物的时空分布特征,同时分析了  相似文献   

9.
Baumgartner and Rumble (1988) apply a kinetic continuum theory for stable isotope transport to unidimensional infiltration of fluid into rock. Their numerical applications are restricted to the simplified case of rapid isotope exchange between phases, where the sharp isotope fronts of pure advection are distended by dispersive mechanisms only. However, kinetic limitations of isotope exchange are potentially an equally important distending mechanism, and it will only rarely be possible to ascribe front gradients to diffusion/dispersion alone. Abrupt isotopic changes at vein boundaries are more often a secondary signal of lithologic change than the expression of a retarded advective front. At such boundaries, diffusion and dispersion play a role that is comparable to, or greater than, that of advection, so that the detailed shapes of isotope fronts depend upon boundary conditions for the infiltration process. Zerodimensional box models have legitimate, if limited, uses in the modelling of fluid-rock interaction, and are reexamined.  相似文献   

10.
The Late-Cretaceous Catalão I contains stockworks of thin dykes of phoscorite-series rocks, which can be subdivided into P1 (olivine-bearing, phoscorites) and P2/P3 (olivine-lacking, nelsonites). Dolomite carbonatites (DC) are intimately associated with nelsonites, as pockets and dykes. The P2 apatite nelsonite, the P3 magnetite nelsonite, and, to a lesser extent DC, host the Catalão I niobium mineralization. C–O isotopes signatures in carbonates reveal several distinct magmatic and post-magmatic processes. Limpid carbonates with stable isotopic mantle-like composition show Rayleigh fractionation and are interpreted as primary, while those with brittle-turbid aspect, and higher oxygen isotope composition, probably underwent recrystallization by interaction with H2O-rich fluids. A group of samples shows higher oxygen compositions and lower carbon values, which could be explained by degassing of carbonatite magma during cooling. A degassing pattern, parallel to magmatic degassing but at higher oxygen and lower carbon compositions, observed in carbonate veins, may indicate degassing of fracture filling fluids. Furthermore, C–O isotopes of carbonate from monazite-bearing carbonatite have a positive correlation, indicating a distinct, late-stage carbo-hydrothermal event. Though the Catalão I nelsonites and phoscorites are of igneous origin, they underwent several post-magmatic events, which sometimes overprinted partially or entirely the magmatic isotope signature.  相似文献   

11.
1Introduction Tracemetalsarereleasedtotheatmosphereduring combustionoffossilfuelsandwood,aswellasemis sionsfromavarietyofprocessesactingoncrustalmin erals,includingvolcanism,erosionandsurfaceweath ering.Onaglobalscale,resuspendedsurfacedusts havemadeagreatcontributiontothetotalnaturale missionoftracemetalstotheatmosphere,withCr,Mn andVaccountingfor>50%andCu,Mo,Ni,Pb,Sb andZnaccountingfor>20%,whilevolcanicactivity probablygeneratedasmuchas20%atmosphericCd,Hg,As,Cr,Cu,Ni,PbandSb(Pacyna,19…  相似文献   

12.
In the Dragon Belly cave helictites, a special type of irregular speleothem, are found, which grew on stalactites in all vertical and horizontal directions without any affinity to gravity. Microstructural and mineralogical analyses of this stalactite–helictite system indicate that its evolution is initiated by clogging of the central stalactite channel at its tip, probably when the cave was flooded by muddy water. Clogging caused the formation of secondary channels (≈0.2 mm in diameter) for water passage through the outer surface of the stalactite, where helictites start to grow. The secondary channel passes into the central channel of the helictite.The helictites consist of stacked idiomorphic calcite crystals with uniform orientation. Growth of calcite is essentially controlled by water transfer through the central channel and via canalicules (narrow channels of ≈0.05 mm in diameter) following the crystal boundaries of the calcite mesocrystal induced by capillary hydrostatic forces. At straight parts of the helictites calcite crystals are almost uniform in size, but at bended parts crystals are significantly smaller inside (≤0.1 mm in length) than outside of the bend (≤0.5 mm). It is proposed that the difference in calcite volume (larger crystals) vs. the inside of the bend leads to a helix form, which explains the origin of the term helictite.The Sr and Ba concentrations measured by laser ablation along helictites can be explained by cation incorporation during calcite precipitation close to equilibrium. Dilution effects caused by seasonality control the elemental distribution in the helictite, which result in a positive correlation between Sr and Ba. Variability of Mg is unrelated with Sr and Ba, and is probably due to the incongruent dissolution of Mg–calcite from the host rock.  相似文献   

13.
使用TH1500C智能中流量(80~120 L/min)大气采样器采集了北京市区5个功能区和郊区的大气颗粒物(TSP/PM_(10)/PM_(2.5))样品,利用电感耦合等离子体质谱仪和原子荧光谱仪分析测试了大气颗粒物中Al,Fe,Mn,As,Hg,Cd,和Cr等21种元素,并通过计算元素的富集因子探讨了大气颗粒物中元素的来源。结果表明,冬季大气颗粒物PM10中Cd,Cr,As,Hg的浓度比春季的分别增幅233%,306%,298%和141%;在PM2.5中的增幅分别为442%,309%,310%和256%。Cd,Cr,As,Hg和Se等元素均表现出在PM_(2.5)中富集的趋势,并且其在冬季的浓度明显高于春季。认为冬季燃煤取暖对大气颗粒物中的污染元素贡献较大,主要贡献元素为Cd,As和Hg。  相似文献   

14.
The F–(Ba–Pb–Zn) ore deposits of the Zaghouan District, located in NE Tunisia, occur as open space fillings or stratabound orebodies, hosted in Jurassic, Cretaceous and Tertiary layers. The chondrite-normalized rare earth element (REE) patterns may be split into three groups: (i) “Normal marine” patterns characterizing the wallrock carbonates; (ii) light REE (LREE) enriched (slide-shaped) patterns with respect to heavy REE (HREE), with small negative Ce and Eu anomalies, characteristic of the early ore stages; (iii) Bell-shaped REE patterns displaying LREE depletion, as well as weak negative Ce and Eu anomalies, characterizing residual fluids of subsequent stages. The 87Sr/86Sr ratios (0.707654–0.708127 ± 8), show that the Sr of the epigenetic carbonates (dolomite, calcite) and ore minerals (fluorite, celestite) are more radiogenic than those of the country (Triassic, Jurassic, Cretaceous, lower Miocene) sedimentary rocks. The uniformity of this ratio, throughout the District, provides evidence for the isotopic homogeneity and, consequently, the identity of the source of the mineralizing fluids. This signature strongly suggests that the radiogenic Sr is carried by Upper Paleozoic basinal fluids.The δ34S values of barite, associated to mineralizations, are close to those of the Triassic sea water (17‰). The δ34S values of sulfide minerals range from − 13.6‰ to + 11.4‰, suggesting two sulfur-reduced end members (BSR/TSR) with a dominant BSR process.Taking account of the homogeneity in the Pb-isotope composition of galenas (18.833–18.954 ± 0.001, 15.679–15.700 ± 0.001 and 38.690–38.880 ± 0.004, for the 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios respectively), a single upper crustal source for base-metals is accepted. The Late Paleozoic basement seems to be the more plausible source for F–Pb–Zn concentrated in the deposits. The genesis of the Zaghouan District ore deposits is considered as the result of the Zaghouan Fault reactivation during the Late Miocene period.  相似文献   

15.
According to the myth, ooid-rich sediments in Cleopatra Beach (Sedir Island, Turkey) were brought by ships from Alexandria Beach (Egypt) by the Roman leader, Marcus Antonius, for his lover Cleopatra. Ooids of both beaches have been compared in terms of sedimentology, mineralogy and geochemistry to determine reality of the myth of love. Sieve analyses exhibit that sediments of Cleopatra Beach are slightly better sorted than Alexandria Beach sediments, and have relatively smaller sized ooids, interpreted to represent a relatively less agitated environment. All ooids are composed mainly of aragonite characterized by high Sr contents (>8600 mg/kg). Hierarchical Cluster Analysis, the cross-plot of δ18Oaragonite versus δ13Caragonite values of ooids, and the presence of detrital grains such as gneiss and schist hint on two distinct groups of samples that correspond to the Cleopatra and Alexandria Beach ooids. These results suggest that the myth may not be realistic, and the ooids on the shore of Sedir Island were formed in-situ, e.g., during the Late Holocene.  相似文献   

16.
The objective of this work was to study sorption–desorption and/or precipitation–dissolution processes of Hg(II) compounds considering an eventual contact of soils with Hg-bearing wastes. In addition, this study contributes new data about Hg(II) chemistry in alkaline systems. Saline and alkaline soils with low organic matter (<1 %) and high clay content (60–70 %) were obtained near a chlor-alkali plant. Batch techniques were used to perform the experiments using 0.1 M NaNO3 solutions. Total Hg(II) concentrations ranged from 6.2 × 10?8 to 6.3 × 10?3 M. Sorption of Hg(II) was evaluated at two concentration ranges: (a) 6.2 × 10?8 to 1.1 × 10?4 M, and (b) 6.4 × 10?4 to 6.3 × 10?3 M. At low Hg(II) concentrations, adsorption occurred with a maximum sorption capacity ranging from 4 to 5 mmol/kg. At high Hg(II) concentrations, sorption–precipitation reactions occurred and maximum sorption capacity ranged from 17 to 31 mmol/kg. The distribution of Hg(II) hydrolysis products showed that Hg(OH)2 was the predominant species under soil conditions. According to sorption experiments, X-ray diffraction and chemical speciation modelling, the presence of Hg(OH)2 in the interlayer of the interstratified clay minerals can be proposed. Hg(OH)2 was partially desorbed by repeated equilibrations in 0.1 M NaNO3 solution. Desorption ranged from 0.1 to 0.9 mmol/kg for soils treated with 5.8 × 10?5 M Hg(II), whereas 2.1–3.8 mmol/kg was desorbed from soils treated with 6.3 × 10?3 M Hg(II). Formation of soluble Hg(II) complexes was limited by low organic matter content, whereas neutral Hg(OH)2 was retained by adsorption on clay mineral surfaces.  相似文献   

17.
On the basis of a worldwide review of Claraia,Pseudoclaraia andEumorphotis,especially their important species,two range zones are recog-nized:the Pseudoclaraia wangi range zone——Upper Griesbachia——and the Claraia stachei-C.aurita-Eumorphotis multiformis acme zone——Upper Griesbachian to Lower Smithian .This result revises both the traditional Chinese concept regarding these fossils as limited in Lower Scythian andthe viewpoint of some Eurasian researchers who hold Eumorphotis multifor-mis to be Upper Scythian.The paleogeographical distribution of the three genera is controlledprimarily by temperature(latitude)and secondarily by physiographic separa-tions.Distribution of these fossils is subdivided into four realms and five prov-inces.The Eastern Asia province of the Tethys realm is suggested as thesource area of these fossils.The striking contrast between the composition ofthe species along the southern and northern margins of the Tethys,togetherwith other distributional characters,supports the pla  相似文献   

18.
Doklady Earth Sciences - In the northern part of the Siberian Platform, east of the Anabar Shield, several massifs of alkaline rocks with carbonatites identified (Tomtor, Bogdo, Promezhutochnyi)...  相似文献   

19.
Anomalous concentrations of numerous major and minor elements significantly exceeding the threshold limit values (TLV) for drinking water were registered in the area of the Tyrnyauz Tungsten–Molybdenum Combine (TTMC). The maximal excess of the TLV (by one or two orders of magnitude) were obtained for Mo (up to 11 mg/L), W (4.4 mg/L), As (1.5 mg/L), Mn (8.4 mg/L), and Tl (up to 3.3 μg/L) in water of the Bolshoi Mukulan Brook flowing through the mines and three brooks flowing out from the base of the embankment of the tailing store no. 1. They are the major pollutants for water of the Baksan River. Upon flowing out to the plain, water of the Baksan River shows significant excess of the TLVs (in summer) for Al, Fe, Mn, Be, Si, Ti, Tl, and Hg.  相似文献   

20.
The Let?eng-la-Terae kimberlite (Lesotho), famous for its large high-value diamonds, has five distinct phases that are mined in a Main and a Satellite pipe. These diatreme phases are heavily altered but parts of a directly adjacent kimberlite blow are exceptionally fresh. The blow groundmass consists of preserved primary olivine with Fo86?88, chromite, magnesio-ulvöspinel and magnetite, perovskite, monticellite, occasional Sr-rich carbonate, phlogopite, apatite, calcite and serpentine. The bulk composition of the groundmass, extracted by micro-drilling, yields 24–26 wt% SiO2, 20–21 wt% MgO, 16–19 wt% CaO and 1.9–2.1 wt% K2O, the latter being retained in phlogopite. Without a proper mineral host, groundmass Na2O is only 0.09–0.16 wt%. However, Na-rich K-richterite observed in orthopyroxene coronae allows to reconstruct a parent melt Na2O content of 3.5–5 wt%, an amount similar to that of highly undersaturated primitive ocean island basanites. The groundmass contains 10–12 wt% CO2, H2O is estimated to 4–5 wt%, but volatiles and alkalis were considerably reduced by degassing. Mg# of 77.9 and 530 ppm Ni are in equilibrium with olivine phenocrysts, characterize the parent melt and are not due to olivine fractionation. 87Sr/86Sr(i)?=?0.703602–0.703656, 143Nd/144Nd(i)?=?0.512660 and 176Hf/177Hf(i)?=?0.282677–0.282679 indicate that the Let?eng kimberlite originates from the convective upper mantle. U–Pb dating of groundmass perovskite reveals an emplacement age of 85.5?±?0.3 (2σ) Ma, which is significantly younger than previously proposed for the Let?eng kimberlite.  相似文献   

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