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1.
The Novosibirsk H5/6 ordinary chondrite has signs of shock metamorphism, such as dark shock-melt veins (SMVs) crossing the chondrite host rock. The plagioclase composition grains (Ab78An14Or7) with jadeite were found in the host-rock fragments inside the SMVs. Jadeite has an unusual radial-concentric spherulite-like microtexture. The spherulite-like jadeite formed from the molten plagioclase grain under high-pressure and high-temperature conditions during an impact event. The crystallization was accompanied by sodium-potassium differentiation between coexisting jadeite and residual melt. The PT-conditions of jadeite formation were estimated to be 3-14 GPa and 1400-2150 °C. Jadeite crystallization, Na-K differentiation, and the pressure-temperature estimates of jadeite formation in the Novosibirsk chondrite are very close to those in the Chelyabinsk LL5 chondrite. The spherulite-like microtexture and jadeite-glass coexistence, most likely, point to a high cooling rate of the SMVs at the pressure release stage of the metamorphic process.  相似文献   

2.
《中国地球化学学报》2006,25(B08):235-236
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3.
All the indium-rich deposits with indium contents in ores more than 100×10- 6 seems to be of cassiterite-sulfide deposits or Sn-bearing Pb-Zn deposits, e.g., in the Dachang Sn deposit in Guangxi, the Dulong Sn-Zn deposit in Yunnan, and the Meng'entaolegai Ag-Pb-Zn deposit in Inner Mongolia, the indium contents in ores range from 98×10-6 to 236×10-6 and show a good positive correlation with contents of zinc and tin, and their correlation coefficients are 0.8781 and 0.7430, respectively. The indium contents from such Sn-poor deposits as the Fozichong Pb-Zn deposit in Guangxi and the Huanren Pb-Zn deposit in Liaoning are generally lower than 10×10-6, i.e., whether tin is present or not in a deposit implies the enrichment extent of indium in ores. Whether the In enrichment itself in the ore -forming fluids or the ore-forming conditions has actually caused the enrichment/depletion of indium in the deposits? After studying the fluid inclusions in quartz crystallized at the main stage of mineralization of several In-rich and In-poor deposits in China, this paper analyzed the contents and studied the variation trend of In, Sn, Pb and Zn in the ore-forming fluids. The results show that the contents of lead and zinc in the ore-forming fluids of In-rich and -poor deposits are at the same level, and the lead contents range from 22×10-6 to 81×10-6 and zinc from 164×10-6 to 309×10-6, while the contents of indium and tin in the ore-forming fluids of In-rich deposits are far higher than those of In-poor deposits, with a difference of 1-2 orders of magnitude. Indium and tin contents in ore-forming fluid of In-rich deposits are 1.9×10-6-4.1×10-6 and 7×100-6-55×10-6, and there is a very good positive correlation between the two elements, with a correlation coefficient of 0.9552. Indium and tin contents in ore-forming fluid of In-poor deposits are 0.03×10-6-0.09×10-6 and 0.4×10-6--2.0×10-6, respectively, and there is no apparent correlation between them. This indicates, on one hand, that In-rich ore-forming fluids are the material basis for the formation of In-rich deposits, and, on the other hand, tin probably played a very important role in the transport and enrichment of indium.  相似文献   

4.
The first data were obtained on the total mercury content in hydrobionts and their habitat in Grønfjorden, Spitsbergen, at the waste discharge sites of the settlement of Barentsburg in early spring 2017. The Hg concentration was below the detection limit in the water and varied from 7.1 to 42.3 ng/g of dry weight in the bottom sediments. Mercury concentration in the hydrobionts increased toward the inner fjord and was higher near the mouth of the Grøndalen River, which flows into the fjord. Elevated Hg concentrations at the mouth of the Grøndalen River indicate that much of the toxic metal is brought to the inner part of the fjord with riverine runoff, and this Hg source is likely more important than the surface supply of Hg transferred from local surface pollution centers at Barentsburg. The Hg concentration depended on the position of the marine organisms in the trophic chain and was the highest in the detritophage mollusks Thyasira gouldi, Cardium sp., and Macoma calcarea, the specialized predatory sea snail Cryptonatica affinis, and the cod Gadus morhua, which is a benthosophage–secondary predator. The total Hg concentrations in the hydrobionts and their habitat in Grønfjorden were generally relatively low and close to the background one.  相似文献   

5.
Tunnelling through soils results in ground loss, causing surface settlements and transverse movements. Where the tunnel drive passes below an existing structure, it is important to estimate the effects upon the structure. However, the free ground deformations should not simply be imposed upon a structure, because the structure contributes to stiffening of the ground. A computational soil-structure interaction analysis is required, to otain detailed stress–deformation response. First, linear finite element and Lagrangian finite difference methods are used to estimate ground movements due to a tunnel in free ground, and the results are compared with values based on empirical equations. The two linear methods and an additional hybrid FE method are then used to assess with soil-structure interaction; two cases of a typical short wall and a long wall lying across the route of tunnels of different depths. The results support the validity of the hybrid method which is used to estimate interactive ground settlements for comparison with a reported case of tunnelling below a building in central London. A more detailed case study is then undertaken to assess building damage caused by gross settlements during tunnelling in mixed soils, at a site in Workington, west Cumbria. A survey allowed estimation of free ground movements. Analysis by the hybrid method on the soils plus uncracked structures indicated intolerable horizontal stresses. Re-analysis with major cracks introduced into the structures resulted in close agreement between measured and computed settlements.  相似文献   

6.
《中国地球化学学报》2006,25(B08):250-250
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7.
A field survey of soils and herbaceous species growing in the Lanping Pb/Zn mining area in Yunnan Province, China, was conducted. Two major mining areas, Jiayashan and Beichang, were selected to investigate soil properties, herbaceous distribution and hea…  相似文献   

8.
A May 2007 tornado destroyed 95% of aging, declining Greensburg, Kansas. The city took the opportunity to build back “stronger, better, and greener,” enforcing upgraded codes, requiring city-owned buildings to meet LEED Platinum level standards, and recommending energy-efficiency housing in a new Sustainable Comprehensive Plan. Using information collected from surveys of Greensburg tornado survivors, interviews, and publications, we examined the housing-related recovery, including the emergency provision of temporary shelter and rebuilding permanently. Although temporary shelter kept residents nearby for rebuilding, given the gap between insurance policy limits on the aging housing stock and rebuilding costs, housing affordability is a critical issue in Greensburg’s recovery. Local, state, and federal support have made construction of municipal buildings at LEED Platinum level and some affordable and green housing projects possible. However, far greater public and private sector funding for affordable workforce housing, in conjunction with broader economic and job development, is needed.  相似文献   

9.
Wetland is the conjunction of lake and terrene where human activities are concentrated. From the viewpoints of material transport and cycling in the terrene-lake system, wetland is the buffer where sand and mud, heavy metals, pollutants and nutrients are tarried. In this paper, we provide a case study based on the temporal and spatial distribution of elements in the Wangling River catchment, a small sub-catchment of Longgan Lake in the middle reaches of the Yangtze River. We have found that wetland can buffer major heavy metals such as Cr, Cu, etc.significantly, but has a little buffer function to some active elements such as Fe and Mn, which are always transported as solutions. Human activities not only influence the distribution of elements, but also weaken the buffer function of wetland. Intensive human activities in the Longgan Lake area in the past 70 years have been recorded in stream, wetland and lake sediments, especially the human activity events such as deforesting and reclaiming on a large scale in 1958 and the 1980‘s. Human activities caused the increase of sedimentation rates since the 1950‘ s, as well as the increase of elements‘ concentrations. The extensive use of fertilizers and pesticides since the 1960‘ s have led to the increase of total P concentrations. Increasing SO2 emission accelerate the process of cation exchange in soil, and enhance the leaching of Mn out of soils. Permanent storing of water causes the soil gleyification that also intensifies the leaching of Mn.These are two major reasons for the obvious increase of manganese concentrations in recent 20 years in Longgan Lake. Intensive human activities since the 1950s‘ have intensified the population in this region and thus destroyed the buffer function of wetland.  相似文献   

10.
Italy has a long-standing tradition of earthquake investi-gations. Seismologists can rely on one of the longest and most detailed records of historical seismic#y, 20 years of homogeneous and reliable instrumental data, systematic and widespread active stress data and a comprehensive database of potential seismogenic sources. Here wed escribe these datasets and discuss how they may help usanticipate the large earthquakes of the future.  相似文献   

11.
The urban environment quality is of vital importance as the majority of people now live in cities. Due to the continuous urbanization and industrialization with rapidly increasing economy in China, metals are continuously emitted into soils, imposing a great threat on human health. Urban soils might be affected by industrial activities, transport, agricultural practice, and waste disposal. An extensive survey was conducted in the highly urbanized Zhangzhou City （Fujian Province, China） using a systematic sampling strategy. Concentrations of Hg, Cd, Pb, Zn, Cu, As, Cr and Ni were measured on 108 topsoil samples collected from parks （0-15 cm）, residential areas and suburban agricultural soils. Statistic approach （cluster analysis） was adopted for identification of natural and anthropogenic influence on heavy metal contents. The maps of metal concentrations in surface soils were made based on geographical information system （GIS） data. All of these aim at assessing the distribution of these heavy metals in the urban environment.  相似文献   

12.
《中国地球化学学报》2006,25(B08):60-60
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13.
Backgrounds： Coal is and will remain a major energy resource worldwide with P.R. China and the U.S. the leading producers. It has long been known that coal mining causes health problems such as coal workers＇ pneumoconiosis （CWP） and chronic obstructive pulmonary disease （e.g., emphysema）. Yet, there are no accurate methods for predicting their occurrence. The goals of the present study are to determine whether bioavailable iron （BAI） is the active component in coal dust-induced lung diseases and to develop a model using BAI for the prediction of coal＇s pneumoconiotic potency. Methods： Thirty coal samples from Utah （UT）, West Virginia （WV） and Pennsylvania （PA） coalmine regions with a low, moderate, and high prevalence of CWP, respectively,  相似文献   

14.
F, Cl, S and P were determined, using electron microprobe, in magmatic inclusions trapped within minerals and glass mesostasis from Wudalianchi volcanic rocks. The initial volcanic magma from Wudalianchi corresponds to the basanitic magma crystallized near the surface ( pressure < 91 Mpa ). The potential H2O content of this magma is in the range 2 — 4 wt. %. The initial composition of volcanic magmas varies regularly from early to late volcanic events. From the Middle Pleistocene to the recent eruptions (1719 – 1721 yr.), the basicity of volcanic magma tends to increase, as reflected by an increase in MgO and CaO contents and by a progressive decrease in SiO2 and K2O contents. Meanwhile. from early (Q2 ) to late (Q3) episodic eruptions of the Middle Pleistocene, the initial concentrations of chlorine in volcanic magmas range from 1430 – 1930 ppm to 1700 ppm and decrease to 700 — 970 ppm for the first episodic eruption during the Holocene (Q 4 1 ). The chlorine concentrations of volcanic magmas of recent eruption (Q 4 2 ) are increased again to 2600 – 2870 ppm. A parallel evolution trend for phosphorus and chlorine concentrations in magmas has been certified: 1500 – 5970 ppm (Q2)→ 3500 – 4210 ppm (Q3)→ 1100– 3500 ppm (Q 4 1 )→ 6800– 7900 ppm (Q 4 2 ). The fluorine contents of volcanic magmas, from early to late volcanic events, show the same trend: 770 – 2470 ppm → 200–700 ppm → 700 – 800 ppm. During the crystallization-evolution of volcanic magmas, fluorine and phosphorus tend to be enriched in residual magmas as a result of crystal-melt differentiation. for example. the fluorine contents reach 5000– 6800 ppm and the phosphorus contents, 2.93wt.% in residual magmas. An appreciable amount of chlorine may be lost from water rich volcanic magmas prior to eruption as a result of degassing. Apparently, water serves as a gas carrier for the chlorine. The chlorine contents of residual magmas may decrease to 100 – 300 ppm. The volcanic magmas from Wudalianchi are poor in sulfur, normally ranging from 200 to 400ppm. On account of the behavior of sulfur in magmas and the strontium and oxygen isotopic analyses ((87Sr /86Sr)i=0.70503– 0.70589; δ18O = + 5.50 – + 6.89 ‰ ), it can be considered that the basanitic magmas in the Wudalianchi volcanic area came from the upper mantle and have not yet been contaminated probably by continental crust materials.  相似文献   

15.
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16.
INTRODUCTIONThermalgroundwaterisfoundtohaveoccurredinthebedrockcarbonateaquifersofLowerPaleozoicandMeso toNeo ProterozoicErathemsnearTianjin ,China .Thebedrockaquifersexistinthelayersbetweenabout 10 0 0mandmorethan 4 0 0 0mbelowthelandsurface .Thethermalwaterhasbeensuccessfullydevelopedoverthepast2 0yearstoprovideasourceofhotwaterforavarietyofresidentialandindustri alpurposes.Geothermalwellstappingtheaquifersarecapa bleofproducingcommercialquantitiesofhotwaterwiththetemperaturesranging…  相似文献   

17.
Marine water samples, including both surface and bottom samples, were collected from the five sampling sites in Victoria Harbour during December 2004 and February 2005. The concentrations of trace metals （Cd, Co, Cr, Cu, Ni, Pb and Zn） in the suspended particulate matter （SPM） and dissolved phases as well as the Pb isotopic compositions of the suspended particulates were determined to assess the potential sources and transport pathways of metal contaminants in the harbour. The results showed that sewage discharges along the harbour dominated the SPM loadings in water, particularly in the dry season. The total concentrations of Co, Cr, Cu, Ni and Zn in water showed a close association with the SPM loadings, indicating that SPM was important in transporting these metals in the coastal environment. Dissolved phase was predominant for Cd in Victoria Harbour. The particulate phase was the major form of Pb in marine water.  相似文献   

18.
Please refer to the attachment(s) for more details  相似文献   

19.
In this research, chlorinated hydrocarbons （polychlorinated biphenyls and organochlorine pesticides） were measured by GC-ECD in sediments from the Hongfeng Reservoir area. The concentrations of total PCBs range from 3.2 to 31.6 ng/g, among which PCB28, PCB52 are the major congeners with the concentrations from 0.5 to 4.6 ng/g, and from 0.4 to 28.1 ng/g, respectively. The concentrations of these pollutants decrease from surface to bottom, while the concentrations at 1-4 cm are lower than at 5-8 cm, suggesting the decline of PCBs input. TOC concentrations of sediment are found in a significant positive correlation with those of PCBs, suggesting that PCBs are mainly adsorbed on organic matter and particles. HCHs and DDTs are the predominant organochlorine pesticides with the concentrations ranging from 1.6 to 8.9 ng/g （average 3.2 ng/g） and 0.9 to 25.7 ng/g （average 7.8 ng/g）, respectively. β-HCH and γ-HCH （lindane） are the predominant HCH isomers from sediments, and p, p＇-DDE and p, p＇-DDT are the predominant DDT isomers. DDT/DDE＋DDD and α-HCH/γ-HCH ratios range from 0.6 to 0.9 and 0.1 to 3.0, respectively, which indicates more use of lindane than technical mixtures of HCHs before, and also suggests changes in HCHs and DDTs in the environment. The high values of β-HCH and p, p＇-DDE also show that atmospheric input is one of the important sources of the Hongfeng Reservoir, because β-HCH and p, p＇-DDE are stable and have low Sw and Pv so that they can be easily transferred over a long range in atmosphere.  相似文献   

20.
Godwin Masuka 《Geoforum》2012,43(3):573-584
The paper examines the relations between farmers and The Cotton Company of Zimbabwe (COTTCO) in Rushinga district of Zimbabwe. Based on interviews with farmers and secondary data, it examines the practice of side marketing of contracted seed cotton. While a large body of literature has discussed the social and economic effects of contract farming on farmers, there are less critical studies on side marketing of crops by farmers in unstable economic and political environment such as Zimbabwe. The paper demonstrates that farmers taking advantage of the macroeconomic environment in Zimbabwe violated contracts by selling seed cotton to other buyers. In the process, farmers renegotiated the meaning of the contract and appealed to market rationality embedded in the neo-liberal ideology. For these farmers, side marketing was part of a survival strategy, albeit in imperfect markets and a difficult economic environment. Nonetheless, side marketing of seed cotton strained relations between farmers and COTTCO. The paper shows the tensions in contracts that require regulation by the state and the neo-liberal ideology that promote free markets and argue against strong regulation.  相似文献   

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