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1.
1 Introduction Vanadium (V) is a relatively abundant elemenwhich is widely distributed in nature; howeverworkable V deposits are very rare (World HealthOrganization, 2001). Vanadium is a trace elementwhich may be beneficial and possibly essential fohuman…  相似文献   

2.
Tea bush is one of the plants cultivated in acidic soil, and is a typical hyper-accumulator of F and Al. Brick tea is a kind of brick-formed tea compressed using the older and coarse leaves and branches of tea trees. Brick tea mixed with milk is drunk as a daily indispensable beverage for Mongols, Ewenki, and other minority nationalities in the pastoral and semi-pastoral areas of Northwest China. It is reported that drinking brick tea can result in dental and skeletal fluorosis due to the high F content in it. Because Alzheimer's disease (AD) is related with Al in human brain, and Al has potential toxicities for skeletal and neural systems,  相似文献   

3.
Studies on the helium, lead and sulfur isotopic composition were performed of the Gejiu super-large Sn-polymetallic ore deposit. The results indicated that the ore-forming materials came from different sources and the deposit is a product of superimposed mineralization. The deposit is characterized by multi-source and multi-period mineralization, which experienced submarine hydrothermal deposition and Late Yanshanian magmatic hydrothermal mineralization. It is held that the Gejiu super-large Sn-polymetallic ore deposit is a multi-genesis deposit.  相似文献   

4.
China is rich in Middle and Carboniferous fossil corals. The coral faunas in different regions have varying characteristics and can be divided into distinct assemblages. The coral fauna in South China is dominated by the order Caninida and contains numerous endemic elements; that in North China has a lot of Middle Carboniferous corals which are monotonous in species, with Late Carboniferous solitary corals being predominant. The coral fauna in Junggar mainly contains large bi-zoned solitary caninids, while that in southern Khingan is similar to that in South China due to the presence of abundant tri-zoned compound corals. In northern Tibet the coral fauna is also similar to that in South China, but in southern Tibet it is of a cold-water type. Therefore, the Middle and Late Carboniferous coral geography of China can be divided into the Tethys, Boreal and Gondwana Realms.  相似文献   

5.
An almost complete juvenile dinosaur skull with lower jaw was discovered from the Early Cretaceous Yixian Formation in Beipiao, Liaoning Province, China. Here, the specimen is described and a cladistic analysis is performed in order to find its phylogenetic relationships. The result shows that this specimen represents a new genus of Psittacosauridae, Hongshanosaurus houi, gen. et sp. nov., and confirms the monophyletic status for Ceratopsia and Marginocephalia. However, Heterodontosaurus is found to be the sister taxon to Marginocephalia, rather than a basal Omithopoda.  相似文献   

6.
There is a zone of blastomylonites containing hornblende gneisses of Lewisian Inliertype in the northeast-east of Yell,Shetland.This zone with a north—northwesterlytrend consists of blastomylonised hornblende-banded gneiss,hornblende-feldspar gneissand mica-felsie-gneiss with lenses of hornblende gneiss.It is indicated that theblastomylonite zone is actually a ductile shear zone and the sense of shear is dextral.This contributes to understanding the details of tectonic evolution in this area,and thiszone is probably a part of tectonic system of the British Caledonides.  相似文献   

7.
Under the action of tectonic stress ore fluids carrying ore-forming materials can migrate from a higher stress district to a lower one.This is a fact which has been widely accepted by geological cir-cles.However,can the components migrate in solid rocks under the action of stress?This problem has long attracted the attention of many geologists.The author has made a series of simulating experi-tal system.The results show that mylonite was produced as a consequence of shear flowage deformation in dolomite .The contents of the elements in porphyryclast and flowage deformation matrix were analyzed by means of electron microprobe,and the results show that Pb and Zn are obvi-ously concentrated in the shear-flowage deformation zone.Furthermore,Pb is concentrated in its cen-tre while Zn is concentrated on its margins .Newly-formed micro-grained galena can be detected locally.  相似文献   

8.
The Qinling Mountains separating the northern from the southern China plate is a key region for the study of structural evolution of eastern Asia. It is composed of the Palaeozoic fold belt in its northern part and the Variscan and Indosinian fold belts in its southern part. The evolution of the former is marked by the closure of a northward subducting oceanic basin in the early stage, followed by southward obduction of ophiolites and intracontinental thrusting during the Variscan; whereas that of the latter is represented by intracontinental, shallow crustal deformation on the basis of a large-scale detachment structure(with a horizontal slip of at least of 100 km). Since the late Palaeozoic, however, both of the belts have been cut by a series of east-west sinistral strike-slip faults.  相似文献   

9.
By using the Lagrange‘s intermediate value theorem,it is derived mathematically that the structur-al distortion of a coordination polyhedron may lead to an increase in bond-valence sum of the cen-tral atom of ion .The applicabilities of the bond-valence model are discussed in the following two cases:the modeling of crystal structure ,and the indication of distortion degree of a coordination polyhedron.Also it is shown that a distorted polyhedron should be in favor of a longer average bond length or a smaller coordination number.  相似文献   

10.
Just like in sedimentary stratigraphy, the volcanostratigraphic boundary is an important factor for constructing volcanostratigraphic framework. The fundamental factor of volcanostratigraphic boundaries is to classify the types and define their characteristics. Based on field investigation and cross-wells section analysis of Mesozoic volcanostratigraphy in NE China, 5 types of volcanostratigraphic boundaries have been recognized, namely eruptive conformity boundary(ECB), eruptive unconformity boundary(EUB), eruptive interval unconformity boundary(EIUB), tectonic unconformity boundary(TUB) and intrusive contacts boundary(ICB). Except ICB, the unconformity boundaries can be divided into angular unconformity and paraconformity. The time spans and signs of these boundaries are analyzed by using age data of some volcanic fields that have been published. The time spans of ECB and EUB are from several minutes to years. In lava flows, cooling crust is distributed above and below ECB and EUB; in pyroclastic flows, airfalls and lahars, a fine layer below these boundaries has no discernable erosion at every part of the boundary. EUB may be curved or cross curved and jagged. The scale of ECB/EUB is dependent on the scale of lava flow or pyroclastic flows. The time span of EIUB is from decades to thousands of years. There is also weathered crust under EIUB and sedimentary rock beds overlie EIUB. In most instances, weathered crust and thin sedimentary beds are associated with each other laterally. The boundary is a smooth curved plane. The scale of EIUB is dependent on the scale of the volcano or volcano groups. The characteristics of TUB are similar to EIUB’s. The time interval of TUB is from tens of thousands to millions of years. The scale of TUB depends on the scale of the basin or volcanic field. Both the lab data and logging data of wells in the Songliao Basin reveal that the porosity is greatly related to the boundaries in the lava flows. There is a high-porosity belt below ECB, EUB or EIUB, and the porosity decreases when it is apart from the boundary. The high-porosity belt below ECB and EUB is mainly contributed by primary porosity, such as vesicles. The high-porosity belt below EIUB is mainly contributed by primary and secondary porosity, such as association of vesicles and spongy pores, so the area near the boundary in lava flows is a very important target for reservoirs.  相似文献   

11.
p-nitrotoluene is an important organic intermediate widely used in pesticide, foamed plastics, dyestuff and medicine industries. In this paper, Crusian carps (Carassius auratus) were exposed to dilute p-nitrotoluene solutions with different concentrations of 0, 20, 40, 80, 120, 160, 240 and 320 μg/L; the subsequent physiological responses to the chemical were observed, and the variation characteristics of blood corpuscles, ovaries and oocytes were studied by bio-microscopy. Results showed that even very low concentrations of p-nitrotoluene would lead to toxicosis and even the death of Carassius auratus. The bio-microscopic structures revealed that, compared with the compartment of Carassius auratus growing in the p-nitrotoluene-free water (the control group), the lower concentrations of p-nitrotoluene (for example no more than 80 μg/L) would result in the faster disintegration of erythrocytes and the significant enlargement of oocytes, while the higher contents of p-nitrotoluene (no less than 240 μg/L in this case) would inhibit the division of cells and their further growth, even degenerate blood corpuscles and ovaries, suggesting stronger estrogenic activities. The study is financially supported by the Development Foundation of Science and Technology under Shandong Provincial Education Department (No. J05D51).  相似文献   

12.
In this study the effects of polybrominated diphenyl ether compounds (PBDEs), BDE-47 and BDE-99 on carassius aurats were discussed. The reproductive capacity viability and proliferation percent decreased with increasing BDE-47and BDE-99 concentrations (p<0.05), presenting a dose-dependent manner. Physiological biomarkers such as cholesterol (CHL), acetylcholinesterase (AChE), ethoxyresorufin-O-deethylase (EROD) and vitamin were studied to reveal the toxicological effects of BDE-47 and BDE-99 exposure. CHL levels generally decrease with increasing BDE-47 exposure. However, there were no significant differences between the samples and the control. As to BDE-99, the CHL level decreased as compared with the control level when the BDE-99 concentrations reached 20 μg/L (p<0.05). The degree of inhibition of the AChE increased with the increase of DE-47and BDE-99 concentrations. The EROD activity during 72 hours' exposure significantly increased to 20 μg/L for BDE-47 (p<0.05), however, EROD activity was not significantly different at different concentrations of BDE-99 (p<0.05). Carassius aurats hepatocytes reacted to the BDE-47 exposure with increasing EROD activities in the dose dependent manner. Although at lower concentrations, the induced effects of BDE-47 and BDE-99 were not significantly different, though BDE-47 showed strong induced effects on the EROD activity with increasing concentrations in carassius aurats hepatocytes. In contrast, BDE-99 did not influence EROD activity consistently. The VA level of carassius aurats was significantly different from that of the controls for BDE-99 (p<0.001), as far as the VA level was significantly lower of carassius aurats than the controls for BDE-47 (p<0.001). CHL, AChE, EROD, and VA levels in carassius aurats were differently affected by BDE-47 and BDE-99 exposures, therefore, they would be good indicators for exposure.  相似文献   

13.
《Geochimica et cosmochimica acta》1999,63(19-20):3003-3008
Hydroxamate siderophores are biologically-synthesized, Fe(III)-specific ligands which are common in soil environments. In this paper, we report an investigation of their adsorption by the iron oxyhydroxide, goethite; their influence on goethite dissolution kinetics; and their ability to affect Pb(II) adsorption by the goethite surface. The siderophores used were desferrioxamine B (DFO-B), a fungal siderophore, and desferrioxamine D1, an acetyl derivative of DFO-B (DFO-D1). Siderophore adsorption isotherms yielded maximum surface concentrations of 1.5 (DFO-B) or 3.5 (DFO-D1) μmol/g at pH 6.6, whereas adsorption envelopes showed either cation-like (DFO-B) or ligand-like (DFO-D1) behavior. Above pH 8, the adsorbed concentrations of both siderophores were similar. The dissolution rate of goethite in the presence of 240 μM DFO-B or DFO-D1 was 0.02 or 0.17 μmol/g hr, respectively. Comparison of these results with related literature data on the reactions between goethite and acetohydroxamic acid, a monohydroxamate ligand, suggested that the three hydroxamate groups in DFO-D1 coordinate to Fe(III) surface sites relatively independently. The results also demonstrated a significant depleting effect of 240 μM DFO-B or DFO-D1 on Pb(II) adsorption by goethite at pH > 6.5, but there was no effect of adsorbed Pb(II) on the goethite dissolution rate.  相似文献   

14.
水动力学条件对鱼类生长影响的试验研究   总被引:7,自引:1,他引:6       下载免费PDF全文
以鲫鱼为研究对象,将其放入流速渐变环形水槽的不同水动力分区中进行实验,研究水动力学条件对鱼类生长的影响。通过对水槽流场的三维数值模拟,得到其中与鲫鱼生长相联系的水动力学细部特征,将模拟结果与实测流场数据比较分析,结果可靠。细部特征采用流速、流速梯度和动能梯度3个水动力学特征量进行量化分析,并结合鲫鱼相对日增长率,得到鱼类生长与水动力学特征量之间的定量关系。流速对鲫鱼有一个短期的胁迫作用,0.20m/s流速比较适宜鲫鱼的生长;鲫鱼的体重相对日增长率随着水流动能梯度增大而下降,两者呈现负相关性,0.009J/(kg·m)为鲫鱼生长所需动能梯度的一个阈值。通过量化鱼类生长对水动力学条件的需求,可为生态水利规划提供定量化的依据。  相似文献   

15.
The objectives of this study were to determine cadmium and lead concentrations in the breast milk of healthy lactating women who were living in Zarrinshahr, an industrial area of Iran and to investigate the effect of mother’s age, parity and smoking habits in families living in the vicinity of areas contaminated with heavy metals. Cadmium and lead concentrations were determined by graphite furnace atomic absorption spectrometry in 44 milk samples from healthy lactating women collected on first to sixth postpartum week. Accuracy of the analysis was checked by various methods including the use of reference material. The mean ± standard deviation of cadmium and lead concentrations in human milk were 2.44 ± 1.47 μg/L (range 0.62–6.32 μg/L) and 10.39 ± 4.72 μg/L (range 3.18–24.67 μg/L), respectively. There was a positive correlation between the concentrations of lead in milk samples and mother’s age and parity (P < 0.05). Also the concentration of cadmium in breast milk significantly increased (P < 0.05) in mothers who were actively and/or passively exposed to smoking. The results of this study showed that lead and cadmium concentrations in milk samples from lactating women in Zarrinshahr were high. This can be a major public health hazard for the inhabitants living in this industrial region of Iran.  相似文献   

16.
The Omerli reservoir is located on the northeastern side of the Istanbul City. It is one of the most important sources of drinking water with a surface area of 23.1 km2 and a volume of 220 × 106 m3 in the Marmara Region. Water quality characteristics of the lake investigated from May 2002 to April 2003 enabled us to identify the effect of waste loads on water quality of Omerli Lake. The following parameters were measured in the lake water: temperature (16.1°C), conductivity (250 μS/cm), secchi disk depth (1.9 m), dissolved oxygen (DO) (9.36 mg/L), nutrients [ortho-phosphate (78.9 μg/L), nitrate + nitrite (707.5 μg/L) and ammonia-nitrogen (264 μg/L)], chlorophyll a (9.43 μg/L), total organic carbon (3.33 mg/L), total suspended solids (4.54 mg/L), total poly aromatic hydrocarbon (t-PAH) (0.69 μg/L) and copper (24.5 μg/L). T-PAH (16.5 mg/g-dry-w), Cu (96.5 μg/g-dry-w), organic carbon (org-C) (2.0%) and N (0.44%) were determined in the surface sediment. The values of chlorophyll a and DO in the upper layer were relatively high and low secchi disk depths indicates eutrophic state. There are five channels discharging water, including waste water, into the lake. All channels were sampled during six occasions in order to cover variations between seasons. The following parameters were measured: total organic carbon, total phosphorus, total kjeldahl nitrogen, ammonia and total suspended solids with the flow rates. The Göçbeyli stream has the highest flow into the lake (1.5 × 108 m3/year) but most of the nutrients were discharged from the Pa?aköy channel. It is accounting for 81% of ammonia and 80% of total phosphorus into the lake. Three scenarios were run using AQUATOX model: (1) all existing inflows are discharging into the lake (present situation); (2) none is discharging; (3) all are discharging except the Pa?aköy channel. The first scenario produced concentrations consistent with measurements in the lake. In all stations, a phytoplankton peak value was predicted during November and December 2002, and January 2003. In the second scenario, as expected, a significant decrease in the concentrations was predicted. In the third scenario, a small improvement in the water quality was obtained. To significantly improve the state of the lake, instead of entering Pa?aköy channel, wastewater should bypass the lake.  相似文献   

17.
The impact of waste disposal on trace metal contamination was investigated in eleven wetlands in the Lake Victoria Basin. Samples of soil, water and plants were analysed for total Zn, Cu, Pb and Ni concentrations using flame atomic absorption spectrophotometry. The trace metal concentrations in soil were the highest in Katanga wetland with the highest mean concentrations of 387.5±86.5 mg/kg Zn, 171.5±36.2 mg/kg Pb, 51.20±6.69 mg/kg Cu and 21.33±2.23 mg/kg Ni compared to the lowest levels observed at Butabika (30.7±3.2 mg/kg Zn, 15.3±1.7 mg/kg Pb, 12.77±1.35 mg/kg Cu and 6.97±1.49 mg/kg Ni). Katanga receives waste from multiple industrial sources including a major referral city hospital while Butabika is a former solid waste dumpsite. Wetland soil near a copper smelter had a Cu concentration of 5936.3±56.2 mg/kg. Trace metal concentrations in industrial effluents were above international limits for irrigation water with the highest concentrations of 357,000 μg/L Cu and 1480 μg/L Zn at a Cu smelter and 5600 μg/L Pb at a battery assembling facility compared to the lowest of 50 μg/L Cu and 50 μg/L Zn in water discharged from Wakaliga dumpsite. Uptake of trace metals from soil differed from plant to plant and site to site. Higher levels of trace metals accumulated in the root rather than in the rhizome and the least amount was in the leaf. The study identifies industry as a potential source of trace metal contamination of water and the environment pent-up need for policy intervention in industrial waste management.  相似文献   

18.
超高效液相色谱法直接快速测定环境水样中硝基苯和苯胺   总被引:2,自引:1,他引:1  
黄毅  饶竹  刘艳  刘晨  郭晓辰 《岩矿测试》2012,31(4):666-671
建立了超高效液相色谱直接快速测定环境水样中硝基苯和苯胺的分析方法。取900μL水样与100μL乙腈混匀,用微孔滤膜(0.2μm,有机系)过滤。采用1.7μm小颗粒填料的BEH phenyl柱,以乙腈/醋酸铵溶液为流动相,硝基苯和苯胺分别用紫外和荧光检测器检测,分析时间仅1.1 min。硝基苯和苯胺的线性范围分别是0.485~4850μg/L和0.495~1978μg/L,方法检出限分别是0.194μg/L和0.099μg/L,相关系数均在0.995以上。硝基苯9.70μg/L、194μg/L、1940μg/L三个浓度水平回收率在98.3%~101%,相对标准偏差在1.11%~2.03%。苯胺9.89μg/L、198μg/L、1978μg/L三个浓度水平回收率在98.6%~104%,相对标准偏差在0.75%~5.85%。与传统液相分析方法相比,本方法线性范围更宽,灵敏度更高;直接进样简化了前处理环节,减少采样体积和有机试剂的使用;分析效率高,适用于地下水、地表水等多种水质样品中痕量到常量范围的硝基苯和苯胺快速测定。  相似文献   

19.
Three wells in New Hampshire were sampled bimonthly over three years to evaluate the temporal variability of arsenic concentrations and groundwater age.All samples had measurable concentrations of arsenic throughout the entire sampling period and concentrations in individual wells had a mean variation of more than 7 μg/L.The time series data from this sampling effort showed that arsenic concentrations ranged from a median of 4 μg/L in a glacial aquifer well(SGW-65)to medians of 19μg/L and37 μg/L in wells(SGW-93 and KFW-87)screened in the bedrock aquifer,respectively.These high arsenic concentrations were associated with the consistently high pH(median≥8)and low dissolved oxygen(median0.1 mg/L)in the bedrock aquifer wells,which is typical of fractured crystalline bedrock aquifers in New Hampshire.Groundwater from the glacial aquifer often has high dissolved oxygen,but in this case was consistently low.The pH also is generally acidic in the glacial aquifer but in this case was slightly alkaline(median = 7.5).Also,sorption sites may be more abundant in glacial aquifer deposits than in fractured bedrock which may contribute to lower arsenic concentrations.Mean groundwater ages were less than 50 years old in all three wells and correlated with conservative tracer concentrations,such as chloride;however,mean age was not directly correlated with arsenic concentrations.Arsenic concentrations at KFW-87 did correlate with water levels,in addition,there was a seasonal pattern,which suggests that either the timing of or multiple sampling efforts may be important to define the full range of arsenic concentrations in domestic bedrock wells.Since geochemically reduced conditions and alkaline pHs are common to both bedrock and glacial aquifer wells in this study,groundwater age correlates less strongly with arsenic concentrations than geochemical conditions.There also is evidence of direct hydraulic connection between the glacial and bedrock aquifers,which can influence arsenic concentrations.Correlations between arsenic concentrations and the age of the old fraction of water in SGW-65 and the age of the young fraction of water in SGW-93 suggest that water in the two aquifers may be mixing or at least some of the deeper,older water captured by the glacial aquifer well may be from a similar source as the shallow young groundwater from the bedrock aquifer.The contrast in arsenic concentrations in the two aquifers may be because of increased adsorption capacity of glacio-fluvial sediments,which can limit contaminants more than fractured rock.In addition,this study illustrates that long residence times are not necessary to achieve more geochemically evolved conditions such as high pH and reduced conditions as is typically found with older water in other regions.  相似文献   

20.
To study arsenic(As) content and distribution patterns as well as the genesis of different kinds of water, especially the different sources of drinking water in Guanzhong Basin, Shaanxi province, China, 139 water samples were collected at 62 sampling points from wells of different depths, from hot springs, and rivers. The As content of these samples was measured by the intermittent flowhydride generation atomic fluorescence spectrometry method(HG-AFS). The As concentrations in the drinking water in Guanzhong Basin vary greatly(0.00–68.08 μg/L), and the As concentration of groundwater in southern Guanzhong Basin is different from that in the northern Guanzhong Basin. Even within the same location in southern Guanzhong Basin, the As concentrations at different depths vary greatly. As concentration of groundwater from the shallow wells(50 m deep, 0.56–3.87 μg/L) is much lower than from deep wells(110–360 m deep, 19.34–62.91 μg/L), whereas As concentration in water of any depth in northern Guanzhong Basin is 10 μg/L. Southern Guanzhong Basin is a newly discovered high-As groundwater area in China. The high-As groundwater is mainly distributed in areas between the Qinling Mountains and Weihe River; it has only been found at depths ranging from 110 to 360 m in confined aquifers, which store water in the Lishi and Wucheng Loess(Lower and Middle Pleistocene) in the southern Guanzhong Basin. As concentration of hot spring water is 6.47–11.94 μg/L; that of geothermal water between 1000 and 1500 m deep is 43.68–68.08 μg/L. The high-As well water at depths from 110 to 360 m in southern Guanzhong Basin has a very low fluorine(F) value, which is generally 0.10 mg/L. Otherwise, the hot springs of Lintong and Tangyu and the geothermal water in southern Guanzhong Basin have very high F values(8.07–14.96 mg/L). The results indicate that highAs groundwater in depths from 110 to 360 m is unlikely to have a direct relationship with the geothermal water in the same area. As concentration of all reservoirs and rivers(both contaminated and uncontaminated) in the Guanzhong Basin is 10 μg/L. This shows that pollution in the surface water is not the source of the high-As in the southern Guanzhong Basin. The partition boundaries of the high- and low-As groundwater area corresponds to the partition boundaries of the tectonic units in the Guanzhong Basin. This probably indicates that the high-As groundwater areas can be correlated to their geological underpinning and structural framework. In southern Guanzhong Basin, the main sources of drinking water for villages and small towns today are wells between 110–360 m deep. All of their As contents exceed the limit of the Chinese National Standard and the International Standard(10 μg/L) and so local residents should use other sources of clean water that are 50 m deep, instead of deep groundwater(110 to 360 m) for their drinking water supply.  相似文献   

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