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1.
Accurate assessment of deep geothermal resources remains a challenge from the practical point of view. Parameter uncertainties and partial knowledge of initial conditions limit the prediction of subsurface temperatures using a variety of thermal models strongly unreliable, and the temperature is highly dependent on the radiogenic heat production in the geological layers mainly affected by a number of factors including the concentrations of uranium, thorium and potassium, and rock density. In this paper, geostatistical methods were applied to investigate the spatial distribution of radiogenic elements (e.g., uranium, thorium, potassium) and their corresponding concentrations and radiogenic heat production. A representative region measuring 35 km?×?80 km in the southwestern Québec, and covering the domains of Portneuf-Mauricie, Morin Terrane and Parc des Laurentides in the Grenville Province was selected for this study because of its easy accessibility. Analysis results show that the concentrations of uranium, thorium and potassium for most rocks of the Grenville basement in the research region are in the range of 1–2 ppm, 3–10 ppm and 1–4%, respectively. Furthermore, 90% of the total samples analysed in this study show a uranium concentration of less than 3 ppm, 64% of the samples show a thorium concentration of less than 5 ppm, and 56% of the samples show a potassium concentration of less than 3%. This paper engaged both the ordinary kriging interpolation and sequential Gaussian simulation (SGS) methods to study the spatial distribution of radiogenic elements. Using density data for specific rocks, the distribution of radiogenic heat production in the study area of the southwestern Grenville Province was also simulated using the SGS method. Conclusively, results show that the difference between the minimum and the maximum value of radiogenic heat production is 30%, considering a significant proportion of heterogeneity in rock density.  相似文献   

2.
Ecotourism environmental impact assessment is a traveling activity relevant influence prediction and appraisal. And the setting-up of the index system is very important to implement the appraisal of environmental impact of ecological travel. According to the index system, natural ecological environment, humane social environment, the environment of tourist resources and the atmosphere of capacity of tourist environment, four major systems form the first index. Each system formed the second index of several key elements. In addition, it is a key step to appraise the sureness of the factor weight, which influences the rationality of the result directly. Daily method of weighting has the Delphi＇s and the AHP. According to ＂Grade form of characteristic value of Standard of rating for quality of tourist attractions＂ which the National Tourism Administration issues, the paper takes the Jingshan mountains ecological tourist zone as an example and adopts AHP to weight the factors mainly, assisted with the Delphi＇s by the help of computer. The Jingshan ecological tourist zone is good. The result of calculation, comprehensive value of 8.35 after establishment, shows that it doesn＇t change dramatically, attributing to the index of natural ecological environment like atmosphere, quality of surface water, acoustics environment and vegetation coverage. Improvement of traffic states and sanitation caused by the project in the region increases the comprehensive value, while the water and soil loss in partial area caused by construction decrease.  相似文献   

3.
The direct determination of most trace elements in natural water samples is still very difficult even if the high-sensitivity atomic analytical instrument, such as ICP-MS, is available. The reasons are (1) the natural concentrations of most trace elements…  相似文献   

4.
It is very important to strengthen the research about the heavy metal pollution of soil in vulnerable ecological regions of the south-central arid area of Northwest China for regulating and guiding local industrial and municipal activities and for protecting the environment. In this study, 48 surface soil samples were collected in the desert–loess transitional zone in the south of the Tengger Desert. The distributions of elements (heavy metal based) and the differences between urban and natural soils were analyzed. We observed that As, Pb, Cu, Zn and S were clearly enriched in the Baiyin area, and Ni and Cr were mainly enriched in the Zhongwei area. V, Mn, Ti, Bi, Co and W were enriched in the southeast margin of the Tengger Desert, where there is relatively little human activity. Over the entire study area, Ce, La and Nd were widely distributed across regions whether with strong or weak human activity. Based on the distributions of elements, we suggest that in the desert–loess transitional zone in the south of the Tengger Desert, the distribution and abundances of element As, Pb, Cu, Zn, S, Ni and Cr are strongly related to the human activities in the area, but the elements V, Mn, Ti, Bi, Co, W, Ce, La and Nd are derived mainly from natural sources.  相似文献   

5.
The Yellow River flows through an extensive area of aeolian desert and extends from Xiaheyan, Ningxia Province, to Hekouzhen, Inner Mongolia Province, for a total of 1,000 km. In the desert channel of the Yellow River, the major chemical components are SiO2, Fe2O3, Al2O3, Ti, CaO, MgO, Ba, P, Mn, Ce, Co in which SiO2, Al2O3, Fe2O3, and Ti have significant value as indicators of the sources of the coarse sediment. The spatial distribution of the elements’ weight percentages and the ratios of Si/Ti, Si/Al between sediment sources and riverbed sediment of the Gansu reach and the desert channel of the Yellow River, indicating that the coarse sediments deposited in the desert reach of the Yellow River are mostly controlled by the local sediment sources; and due to the higher mobility of the fine sediments, they are primarily contributed by the local sediment sources and the tributaries that originate from the loess area of the upper reach of Yellow River. The results of R-factor analysis illustrate that the first component score mainly shows negative values in the desert channel, suggesting that the coarse sediments in this reach contain a higher content of Si and a lower content of Mg + Ca + Al + Fe, which further proves that the Ningxia Hedong, Inner Mongolian Wulanbuhe, and Kubuqi deserts are the primary sources of the coarse sediment in the desert channel of the Yellow River.  相似文献   

6.
Three kinds of spatial analysis methods （geostatistics, concentration-area fractal model and the multifractal analysis called the moment method） were used for almost 50 elements, including heavy metals, disperse elements, rare elements and even others, in 6586 top soil （0-20 cm） samples and 1833 deep soil （150-200 cm） samples from Chengdu metropolitan area of 12400 km^2, southwestern China. The ranges of spatial correlation revealed by variograms are quite different for different kinds of elements in the top and deep soils. The most interest is the fact that the multifractal spectra of environmentally important elements such as Pb, Cr, Cd and Ni in top soils in the metropolitan area show systematic change from those in the deep soils, revealing a strong anthropogenic addition, while Hg, Zn, As, Cu and all common elements show no such kind of addition. In terms of multifractal properties based on the multifractal spectrum curves, those disperse and rare elements show great deviation from other major and trace elements, which is also of great interest.  相似文献   

7.
《Applied Geochemistry》2001,16(4):437-450
Partitioning of 41 elements between solids and water was studied by filtration and dialysis in situ in Czech freshwaters. Field-based distribution (partition) coefficients, KD, between suspended particulate matter (SPM) and filtrate (‘dissolved’ fraction) differed by 4 orders of magnitude. The highest KD values (log KD>2.0 l/g) were exhibited by Zr, Al, Ce, Pb, La, Ti, Fe, Sm, Th and Cr which are extremely insoluble in near-neutral water or generally poorly soluble (Zr,Ti). The KDs decrease with element and DOC loading due to the relative increase of the element in the low molecular fraction. Log KD mostly increased linearly with pH within a range from 3.5 to 9. KDU decreased at pH >6 due to carbonate complexation. The colloidal fraction (>1 kDa <0.4 μm) in a reservoir with a pH of 6.8 was mainly preferred by Fe, Pb, Be, Nb, Y, Al, Ni, U and Zr. When the colloidal fraction is not differentiated from true solution, then incorrect information about partitioning may be obtained and the highest KD may decrease.  相似文献   

8.
Trace and rare earth elements have been determined for cassiterite from deposits associated with the Mole Granite and hosted by granite, metasediments and metavolcanics. The REE of cassiterite is controlled by the REE of the the ore fluid and the rocks through which this fluid circulated. The REE distribution factor and LREE/HREE value of cassiterite is strongly influenced by the associated mineral assemblage, the fluid chemistry and the crystal chemical characteristics of the host mineral. Cassiterite from deposits hosted by granite have trace and rare earth element characteristics similar to those determined for the Mole Granite. Cassiterite from deposits hosted by metasediments or acid volcanics have most trace and rare earth element characteristics similar to those of the enclosing rocks and some characteristics similar to the Mole Granite. The ore fluid had chemical components derived from the parental granite and components acquired by passage through the metamorphosed aureole.  相似文献   

9.
《中国地球化学学报》2006,25(B08):32-32
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10.
The major element composition of sound-producing sand is reported together with rare-earth elements (REE) and other selected elements for the first time. Rare-earth element concentrations in beach sands from Miyagi and Tottori in Japan were determined by induction-coupled, argon-plasma spectrometry (ICP-MS) to characterize the REE of sound-producing and silent sands relative to the parental rocks. Sound-producing sand beaches are very common and all over in Japan: five beaches in Miyagi and 2 in Tottori are selected with other silent sand beaches in the areas. Both sound-producing sand and silent sand samples from Miyagi and Tottori contain more than 60wt% of SiO2 and are composed mainly of quartz and feldspar. Miyagi sand samples are characterized by light REE enrichment and flat chondrite-normalized patterns that are similar to those of local source sandstone. However, all sand samples from Miyatojima in Miyagi show positive Eu anomalies, a characteristic feature not shown in other sand samples from Miyagi. Tottori sand samples also are characterized by high REE contents and remarkable positive Eu anomalies. The sands containing lower REE contents are due to high quartz and feldspar contents. Miyatojima sand samples and Tottori sand samples have high REE contents and show remarkable positive Eu anomalies due to the presence of feldspar. The best results are obtained using all of the geological methods and the Principal Component Analysis (PCA) as a measure of the similarity between sound-producing sand and silent sand. The difference between sound-producing sand and silent sand is obtained from the PCA results.  相似文献   

11.
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12.
《中国地球化学学报》2006,25(B08):276-276
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13.
Although eutrophication and trace element contamination are two key environmental problems in Dongting Lake, a systematic study of the distribution of trace elements in sediments of this lake has not previously been undertaken. In order to identify the current levels of trace metal contamination in Dongting Lake, the concentrations of trace elements （Cd, Cr Cu, Ni, Pb, Zn, As and Hg） in the sediments at 53 locations were investigated in this study. The lake, the second largest fresh-water lake in China, boasts three China wetlands of international importance. Dongting Lake which lies in the south of the middle Yangtze River is the most important reservoir lake in the Yangtze River drainage area, and is characterized by fast flow-through water, large runoff volume and short period of exchanging water （no more than 20 days）. The granulometric analysis result of sediments shows that a large proportion of the sediments measures at 2-63 μm in size; the result of mineralogical analysis shows that original mineral is the main composition of the sediments, followed by clay mineral and carbonate. The contents of copper, lead, zinc, cadmium, arsenic and mercury are higher than the background levels of soil （ Ⅰ Soil） in China, but lower than the threshold values for severely polluted soil （Ⅲ Soil） in China except Cd higher than that in Ⅲ Soil. The concentrations of trace elements analyzed are higher than the Threshold Effect Level of Interim Sediment Quality Guideline by Canada EPA and are lower than the Probable Effect Level. The assessment by geoaccumulation index shows that the contamination of Cd reached strong level in Dongting Lake. Study on speciation of metals by a BCR procedure indicates that the trace elements （Cu, Zn, Cr, and Ni） analyzed are mainly distributed in residual phases but Pb in Fe/Mn oxhydroxide phase and Cd in soluble and carbonate-bound fraction. The potential risk was the highest in East Dongting Lake based on the calculated contamination factors which are mostly probably caused by the deposition of the trace element pollutants via the Xiangjiang River and the discharge of the pollution sources in the vicinity of East Dongting Lake.  相似文献   

14.
太平洋深海沉积物中富集稀土元素(REY,包括钇),被认为是富有潜力的新型稀土资源。(含)沸石粘土、深海粘土和多金属软泥是主要的富含REY的沉积物类型,其中(含)沸石粘土和深海粘土在中、西北太平洋海盆大面积分布,而多金属软泥则多分布于靠近东太平洋洋脊热液活动的深海盆地中。目前关于中、西北太平洋海盆的深海粘土和(含)沸石粘土已有较多的研究,但关于多金属软泥中REY的研究较少。不同区域、不同类型深海沉积物中的稀土元素赋存状态有何差异?影响稀土富集的机制又是什么目前尚不清楚,也就进一步影响了对深海沉积物稀土资源的勘查和开发工作。本文分析对比了太平洋不同区域不同类型深海沉积物的地球化学特征及矿物学特征。结果表明,总体上,中、西北太平洋海盆深海沉积物中,尤其是(含)沸石粘土中的REY含量明显高于东太平洋海盆多金属软泥REY含量,其REY的富集主要与磷酸盐有关。超常富集REY(∑REY>2000×10^(-6))的沉积物中的CaO/P_(2)O_(5)比值趋向于一致(~1.4),几乎接近于磷灰石CaO/P2O5比值(~1.3),因此REY主要赋存载体为磷灰石,该区沉积物中REY的富集可能受到磷酸盐化的影响;东太平洋海盆多金属软泥明显受到热液影响,铁和锰的含量明显增加,但其∑REY含量集中于500×10^(-6)~800×10^(-6),不随铁和锰的增加而变化,REY的富集仍与磷酸盐关系密切,而与铁锰物质和铝硅酸盐关系不大。中、西北太平洋海盆富稀土的深海沉积物形成时处于较强的氧化环境,同时又有充足的含磷物质补给,才造成REY在该区沉积物中的超常富集;而东太平洋海盆多金属软泥虽然处于氧化环境,但缺少足够的磷补给,所以其∑REY含量通常低于中、西北太平洋海盆沸石粘土中∑REY含量。  相似文献   

15.
锂铍金属是世界关键金属资源,矿床类型多样,成矿作用发生在大陆地壳。但大陆地壳中锂铍元素的迁移-循环规律及不同锂铍矿床间的成因联系尚不清楚。本文系统地总结与梳理了大陆地壳结构与物质循环特征和不同类型锂铍金属矿床间的成因联系,提出大陆地壳锂铍循环-成矿系统的概念与模型,并将大陆地壳锂铍的迁移与循环划分为四个过程:变质过程、深熔过程、花岗岩浆过程、花岗质岩浆岩风化、淋滤与蚀变的浅-表生过程。沉积岩中锂铍元素在变质过程中可富集到一些变质矿物中,一些富锂铍黏土矿物也在变质过程转变成新的富锂铍变质矿物(如绿泥石、云母与堇青石);地壳深熔过程使得锂铍元素从变质矿物中释放出来并聚集在花岗岩浆中,麻粒岩相深熔(如黑云母脱水熔融与堇青石分解熔融)可能是锂铍大规模成矿的主要熔融方式;绝大多数锂铍矿床与花岗岩浆及其岩浆岩有关,是花岗岩浆与花岗质岩浆岩在不同演化阶段与不同方式富集成矿的结果;浅-表生过程对锂铍花岗岩-伟晶岩和流纹岩与流纹质凝灰岩的物理化学改造,可形成盐湖卤水型锂矿床、黏土型锂矿床以及各种次生锂铍矿床。变质过程中锂铍的迁移与富集机制,大型-超大型花岗岩-伟晶岩型锂铍矿床形成条件与关键控制因素等问题,是亟待研究与思考的科学问题。  相似文献   

16.
Several rivers researched around Taihu Lake in Chinese eastern plain are distributed to the west of the lake. Pollutants of different types from tributaries and inlets flow directly into the main rivers and finally into the lake. They change trace elements of rivers fi＇om which we can analyze. Researches about trace elements are helpful for understanding the pollutant characteristics, industrial structure and agricultural cultivation in the area of network rivers in the plain of China. Samples of water column, suspended matter and sediment were collected fi＇om the west rivers of Taihu Lake, which represent three typical rivers. Observation in the field and the primary composition analysis showed the Caoqiao River was mainly contaminated by industrial wastewater, the Liangxi River was discharged by domestic sewage and the Dapu River was principally input by farmland runoff. REE concentrations and their normalized curves showed obvious characters for rivers discharged by different sewages. The contents of total REE in water column followed the order of the Caoqiao River, the Dapu River and the Liangxi River fi＇om high to low. TREEs in suspended matter and sediments follow the order of the Dapu River 〉 the Caoqiao River 〉 the Liangxi River. REE normalized curves （for Australia shale） suggested that significant diversities were presented in water column, suspended matter and sediments, i.e., heavy REE enrichment in water, middle REE enrichment in suspended matter, and smooth curves for sediments. But the heavy pollution resulted in several anomalous curves in the same rivers. Some element ratios were selected as indices for polluted rivers based on their geochemical properties and diversities between rivers. The results displayed the discriminative indices for water column, suspended matter and sediment. The effective indices were Pb/Fe, Cr/Fe, Ni/Fe, Pb/Ni, Zn/Ni for water column, Cu/Al, Cu/Fe, Zn/Fe, K/Ca, K/Na, Pb/Co, Zn/Co for suspend matter and Pb/Fe, K/Ca, Ca/Mg, Zn/Ni for sediment, respectively. In general, rivers mainly discharged by industrial sewage have high ratios of Pb/Ni, K/Ca, are enriched in the middle REE and have positive Gd anomaly. The domestic sewage flowing into rivers reveals high ratios of Zn/Ni, Pb/Fe, and is enriched in the heavy REE, and has the positive Eu anomaly. If runoff of farmland enters into the rivers, it will have high ratios of Ca/Mg, K/Na, high lanthanum, and show the smooth normalized curves of REE.  相似文献   

17.
The variations of groundwater quality in the unconfined zone of the Almonte-Marismas aquifer, upon which Doñana National Park is located, are analysed. Most sampled points are multiple piezometers, allowing for the vertical distribution study of the hydrogeochemical characteristics in the aquifer. Temperature, pH, electrical conductivity, dissolved oxygen and redox potential were determined in the field. A large number of parameters, including major ions and a large amount of minor and trace elements, were analysed. In the southern zone, where aeolian sands crop out, water composition in the shallower part of the aquifer is of the sodium chloride type, with low pH (5.5–6) and mineralization (<200 μS/cm) values. As water circulates through the aquifer, bicarbonate and calcium concentrations increase slightly. In agricultural or urban zones, nitrates and sulphates present their highest contents in the upper part of the aquifer. In zones with low pH levels (around 6), concentration of many trace metals (Al, Co, Cr, Cu, Ni, Zn, etc.) also shows a distribution similar to that of sulphates and nitrates, which indicates its fertilizer-linked origin. In zones with neutral or alkaline pH, regardless of high nitrate content, concentration of the above mentioned metals is very low due to its immobilisation by surface adsorption processes. The distribution of Br contents also shows the effects of agricultural pollution.  相似文献   

18.
Due to the unique chemical properties that are similar but still progressively change, the rare earth elements （REEs） are useful tracers of various geochemical processes in the lithosphere and hydrosphere. However, despite many studies of REE geochemistry in the ocean, the aqueous geochemistry of REEs in lake waters has been poorly documented. In the present study, two special karst lakes are chosen as case studies to investigate the distributions of dissolved REEs in lake water. Although the two lakes, Hongfeng and Aha, are both alkaline and have high pH from 7.9 to 8.7 and high carbonate concentrations, the Aha Lake has been more severely affected by acidic mining drainage with high Fe, Mn and SO42 concentrations. In the present study, the concentrations of dissolved rare-earth elements in lake waters were determined by inductively coupled plasma mass spectrometry. The result shows that the concentrations of dissolved REEs in the studied alkaline karst lakes, as compared to the concentrations of REEs in seawater, are much lower than the other investigated terrestrial surface waters in previous studies. The key factor controlling dissolved REE distributions is pH value which is negatively correlated with REE concentrations. Due to high concentration of carbonate ion and alkaline character of water chemistry, the shale （PAAS） normalized patterns of dissolved REEs show marked HREE enrichment in all water samples. This is primarily the result of the preferential formation of stronger carbonate complexes with the HREEs. In alkaline or intermediate waters, REE-carbonate complexes are the dominant and typical species, which account for about more than 90% of the total dissolved REEs.  相似文献   

19.
Total and bioavailable concentrations of rare earth elements (REEs) in the latesol of Hainan Province, China, were measured by ICP-MS, and the distribution characteristics of REEs were discussed in various latesol profiles. The results show that the total…  相似文献   

20.
The elemental geochemistry of major, minor and trace elements in iron–manganese cutans and the corresponding matrix soils, collected from three Alfisols in central China, are studied using their chemical compositions as well as correlation and factor analyses. Fe–Mn cutans accumulate high concentrations of MnO2 and Fe2O3. Mean values of these two elements in cutans are about 13.7 and 1.4 times higher than those in the matrix soils. pH, clay contents, extractable X-ray noncrystalline Fe (Feo) and the ratio of Feo to free Fe-oxide (Fed) in cutans are notably higher than those in the corresponding matrices. Cutans are also enriched in some bases and heavy metals. Averages of K, Na, Co and Pb concentrations are about 2.0, 1.4, 15.4 and 6.0 times higher than those in the matrices. Statistical analysis indicates that Co, Ni, Li, Cu and Zn are abundant in Mn minerals of cutans, while Pb exists mainly in iron minerals. Fe–Mn cutans constitute an active microzone of solid–solution–plant–air interaction, element movement and exchange in soils, which cause the contents of Fe- and Mn-oxides, elemental concentrations, and geochemical behavior of cutan to show marked differences in matrix soils.  相似文献   

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