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1.
Bo Peng Xiaoya Tang Changxun Yu Changyin Tan Chunyan Yin Guang Yang Qian Liu Kesu Yang Xianglin Tu 《Environmental Earth Sciences》2011,64(5):1455-1473
This paper reports a geochemical study of trace metals and Pb isotopes of sediments from the lowermost Xiangjiang River, Hunan
province (P. R. China). Trace metals Ba, Bi, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, Mo, Cd, Sn, Sb, Pb, Tl, Th, U, Zr, Hf, Nb and
Ta were analyzed using ICP-MS, and Pb isotopes of the bulk sediments were measured by MC-ICP-MS. The results show that trace
metals Cd, Bi, Sn, Sc, Cr, Mn, Co, Ni, Cu, Zn, Sb, Pb and Tl are enriched in the sediments. Among these metals, Cd, Bi and
Sn are extremely highly enriched (EF values >40), metals Zn, Sn, Sb and Pb significantly highly (5 < EF < 20), and metals
Sc, Cr, Mn, Co, Ni, Cu and Tl moderately highly (2 < EF < 5) enriched in the river sediments. All these metals, however, are
moderately enriched in the lake sediments. Geochemical results of trace metals Th, Sc, Co, Cr, Zr, Hf and La, and Pb isotopes
suggest that metals in the river sediments are of multi-sources, including both natural and anthropogenic sources. Metals
of the natural sources might be contributed mostly from weathering of the Indosinian granites (GR) and Palaeozoic sandstones
(PL), and metals of anthropogenic sources were contributed from Pb–Zn ore deposits distributed in upper river areas. Metals
in the lake sediments consist of the anthropogenic proportions, which were contributed from automobile exhausts and coal dusts.
Thus, heavy-metal contamination for the river sediments is attributed to the exploitation and utilization (e.g., mining, smelting,
and refining) of Pb–Zn ore mineral resources in the upper river areas, and this for the lake sediments was caused by automobile
exhausts and coal combustion. Metals Bi, Cd, Pb, Sn and Sb have anthropogenic proportion of higher than 90%, with natural
contribution less than 10%. Metals Mn and Zn consist of anthropogenic proportion of 60–85%, with natural proportion higher
than 15%. Metals Sc, Cr, Co, Cu, Tl, Th, U and Ta have anthropogenic proportion of 30–70%, with natural contribution higher
than 30%. Metals Ba, V and Mo might be contributed mostly from natural process. 相似文献
2.
黑色页岩与土壤重金属污染 总被引：6，自引：1，他引：5
本文利用ICP—MS等技术分析了湘中地区黑色页岩及其相应土壤的重金属含量,在对分析结果进行统计分析的基础上,探讨了黑色页岩与土壤重金属污染的关系。研究表明,黑色页岩是富集多种重金属元素的特殊岩石。以黑色页岩岩系为母岩的土壤,不仅明显富集Cu、Cd、Cr、Co、Pb、Zn、Mo、Ni、V、U、Sn、Sb、T1、Th等多种重金属元素,而且受到Mo、Sb、Cd、U、Tl、Cu、V、Sn、Th等重金属的污染,其中以Mo、Cd、Sb、U、Tl等的污染尤为严重。黑色页岩土壤重金属污染在一些地方已产生明显的负面环境效应,值得关注。 相似文献
3.
Bo Peng Adam Piestrzynski Jadwiga Pieczonka Meilian Xiao Yaozhu Wang Shurong Xie Xiaoyan Tang Changxun Yu Zhi Song 《Environmental Geology》2007,52(7):1277-1296
The mineralogy and geochemistry of the waste rocks distributed at Taojiang Mn-ore deposit, central Hunan province, China,
were studied using X-ray powder diffraction (XRD), electron microprobe analysis (EMPA) fitted with energy dispersive spectrometer
(EDS) and inductively coupled plasma mass spectrum (atomic emission spectra) ICP-MS (AES), with the aim of predicting the
environmental impacts of weathering of the waste rocks. The mineralogical results from microscope observation and XRD and
EMPA studies show that the waste rock is composed of black shale and minor Mn carbonates. The oxidation of sulfide minerals
such as galena, pyrite and chalcopyrite is accompanied by decomposition of Mn carbonates and K-feldspar during exposure to
atmospheric O2. The geochemical characteristics of major, rare earth elements (REE) and trace elements of the waste rocks also show that
the waste rock can be divided into black shale and Mn carbonate, and both of them are currently under chemical weathering.
The major alkalies and alkaline elements (Ca, Mg, Na, K, Rb, Sr and Cs) and major elements (Fe, S and P) and heavy metals
(Sc, V, Cr, Th, U, Sn, Co, Ni, Cu, Zn, Pb, Mo, Cd, Sb, an Tl) are being released during weathering. The mobility of alkalis
and alkaline elements Ca, Mg, Na, K, Rb, Sr and Cs is controlled by decomposition of Mn carbonates. The dispersion of Cr,
Sc and Th (U) might be related to weathering of K-feldspar, and the release of the heavy metals Co, Ni, Cu, Zn, Pb, Mo, Cd
Sb and Tl is dominated by the breaking of sulfide minerals. The REE of the waste rocks and surrounding soils and the spidery
distribution patterns of heavy metals in the waste rocks, the surrounding soils and the surface waters show that weathering
of the waste rocks and bedrock might be the sources of heavy metal contamination for the surrounding soils and surface water
system for the mining area. This is predicted by the mass-balance calculation by using Zr as an immobile element. Therefore,
it is urgently necessary take measures to treat the waste rocks distributed throughout the area for the local environmental
protection. 相似文献
4.
5.
对湘中桃江锰矿废矿堆的废石进行了主量元素、稀土元素、微量元素和重金属元素的地球化学分析。野外观察及分析结果表明:组成废矿堆的岩石主要是赋矿围岩中奥陶统黑色页岩和原生碳酸锰矿石。这些废石富含Cu、Pb、Zn、Cr、Tl、Sb、U等重金属元素。废石暴露地表而遭受风化分解,导致Sc、V、Cr、U、Cd、Th等重金属元素淋滤释出,在废石样品中均表现出不同程度的迁移特征,且以V、Cd、U的迁移性最为强烈。此外,黑色页岩中Ni、Cu、Zn、Pb、Tl、Sb也明显发生淋失。这些重金属元素如Cd、Tl等毒性极强,进入矿区周围不断积聚,便可能对环境造成严重的影响。故对区内分布的废矿堆作为重金属污染源应高度重视。 相似文献
6.
湘中安化黑色页岩土壤玉米的元素地球化学分析 总被引：1，自引：0，他引：1
利用等离子质谱(ICP-MS)等分析技术,对产于安化东坪、烟溪黑色页岩土壤上的玉米进行元素地球化学分析.结果.表明:尽管东坪、烟溪黑色页岩土壤重金属元素富集的程度及其元素组合特征明显不同,但生长在其上的玉米有相似的主量元素和重金属元素的富集特征.玉米中Cd、Cr、Sc、Tl、Zn等重金属相对富集,以Cd的富集尤为明显;而Ba、Co、Cu、Fe、Mo、Ni、Pb、Sb、U、V等重金属相对亏损.黑色页岩土壤重金属污染的环境地球化学效应表现为Sc、Cr、Cd、Tl等生物毒性重金属元素在玉米中富集,而Ba、V、Co、Ni、Mo、Rb、Sr等生物必需微量金属在玉米中亏损. 相似文献
7.
Bo Peng Xiaoyan Tang Changxun Yu Shurong Xie Meilian Xiao Zhi Song Xianglin Tu 《Environmental Geology》2009,57(2):421-434
The acid mine drainage (AMD) discharged from the Hejiacun uranium mine in central Hunan (China) was sampled and analyzed using
ICP-MS techniques. The analyzing results show that the AMD is characterized by the major ions FeTotal, Mn, Al and Si, and is concentrated with heavy metals and metalloids including Cd, Co, Ni, Zn, U, Cu, Pb, Tl, V, Cr, Se,
As and Sb. During the AMD flowing downstream, the dissolved heavy metals were removed from the AMD waters through adsorption
onto and co-precipitation with metal-oxhydroxides coated on the streambed. Among these metals, Cd, Co, Ni, Zn, U, Cu, Pb and
Tl are negatively correlated to pH values, and positively correlated to major ions Fe, Al, Si, Mn, Mg, Ca and K. The metals/metalloids
V, Cr, Se, As and Sb are conservative in the AMD solution, and negatively-correlated to major ions Na, Ca and Mg. Due to the
above different behaviors of these chemical elements, the pH-negatively related metals (PM) and the conservative metals (CM)
are identified; the PM metals include Cd, Co, Ni, Zn, U, Cu, Pb and Tl, and the CM metals V, Cr, Se, As and Sb. Based on understanding
the geochemistry of PM and CM metals in the AMD waters, a new equation: EXT = (Acidity + PM)/pH + CM × pH, is proposed to
estimate and evaluate extent of heavy-metal pollution (EXT) of AMD. The evaluation results show that the AMD and surface waters
of the mine area have high EXT values, and they could be the potential source of heavy-metal contamination of the surrounding
environment. Therefore, it is suggested that both the AMD and surface waters should be treated before they are drained out
of the mine district, for which the traditional dilution and neutralization methods can be applied to remove the PM metals
from the AMD waters, and new techniques through reducing the pH value of the downstream AMD waters should be developed for
removal of the CM metals. 相似文献
8.
Accumulation and sources of heavy metals in urban topsoils: a case study from the city of Xuzhou, China 总被引：8，自引：0，他引：8
The knowledge of the variability, the anthropogenic versus natural origin and corresponding environmental risk for potentially harmful elements in urban topsoils is of importance to assess human impact. The aims of the present study were: (1) to assess the distribution of heavy metals (Sn, Li, Ga, Ba, Fe, Mn, Co, Be, Ti, Al, Hg, Cr, Sb, As, Bi, Pd, Pt, Au, Ni, Cd, Zn, Cu, Pb, Se, Mo, Sc and Ag) in urban environment; (2) to discriminate natural and anthropogenic contributions; and (3) to identify possible sources of pollution. Multivariate statistic approaches (principal component analysis and cluster analysis) were adopted for data treatment, allowing the identification of three main factors controlling the heavy metal variability in Xuzhou urban topsoils. Results demonstrate that Hg, Cr, Sb, As, Bi, Pd, Pt, Au, Ni, Cd, Br, Zn, Cu, S, Pb, Se, Mo, Sc and Ag could be inferred to be tracers of anthropogenic pollution, whereas Al, Ti, Ga, Li, V, Co, Pt, Mn and Be were interpreted to be mainly inherited from parent materials. Iron, Ba, Sn, Pd and Br were interpreted to be affected by mixed sources. 相似文献
9.
Raimundo Jiménez Ballesta Paz Conde Bueno Juan A. Martin Rubi Rosario Garcia Giménez 《Central European Journal of Geosciences》2010,2(4):441-454
To evaluate trace element soil contamination, geochemical baseline contents and reference values need to be established. Pedo-geochemical baseline levels of trace elements in 72 soil samples of 24 soil profiles from the Mediterranean, Castilla La Mancha, are assessed and soil quality reference values are calculated. Reference value contents (in mg kg?1) were: Sc 50.8; V 123.2; Cr 113.4; Co 20.8; Ni 42.6; Cu 27.0; Zn 86.5; Ga 26.7; Ge 1.3; As 16.7; Se 1.4; Br 20.1; Rb 234.7; Sr 1868.4; Y 38.3; Zr 413.1; Nb 18.7; Mo 2.0; Ag 7.8; Cd 4.4; Sn 8.7; Sb 5.7; I 25.4; Cs 14.2; Ba 1049.3; La 348.4; Ce 97.9; Nd 40.1; Sm 10.7; Yb 4.2; Hf 10.0; Ta 4.0; W 5.5; Tl 2.3; Pb 44.2; Bi 2.2; Th 21.6; U 10.3. The contents obtained for some elements are below or close to the detection limit: Co, Ge, Se, Mo, Ag, Cd, Sb, Yb, Hf, Ta, W, Tl and Bi. The element content ranges (the maximum value minus the minimum value) are: Sc 55.0, V 196.0, Cr 346.0, Co 64.4, Ni 188.7, Cu 49.5, Zn 102.3, Ga 28.7, Ge 1.5, As 26.4, Se 0.9, Br 33.0 Rb 432.7, Sr 3372.6, Y 39.8, Zr 523.2, Nb 59.7, Mo 3.9, Ag 10.1, Cd 1.8, Sn 75.2, Sb 9.9, I 68.0, Cs 17.6, Ba 1394.9, La 51.3, Ce 93.5, Nd 52.5, Sm 11.2, Yb 4.2, Hf 11.3, Ta 6.3, W 5.2, Tl 2.1, Pb 96.4, Bi 3.0, Th 24.4, U 16.4 (in mg kg?1). The spatial distribution of the elements was affected mainly by the nature of the bedrock and by pedological processes. The upper limit of expected background variation for each trace element in the soil is documented, as is its range as a criterion for evaluating which sites may require decontamination. 相似文献
10.
Multivariate statistical techniques, i.e., correlation coefficient analysis, principal components analysis (PCA), and hierarchical
cluster analysis (CA), were applied to the total and water-soluble concentrations of potentially hazardous metals in sediments
associated with the Sarcheshmeh mine, one of the largest Oligo-Miocene porphyry copper deposits in the world. The samples
were analyzed for hazardous metal concentration levels by inductively coupled plasma mass spectrometry method. Results indicate
that the contaminant metals As, Cd, Cu, Mo, S, Sb, Sn, Se, Pb, and Zn were positively correlated with the total concentrations.
These hazardous metals also have strong association in the PCA and CA results. Different anthropic versus natural sources
of contaminant metals were distinguished by using CA method. Water-soluble fraction of hazardous metals showed that the hydro-geochemical
behavior of these metals in sediments is different considerably. Elements such as Cd, Co, Cr, Cu, Fe, Mn, Ni, S, and Zn are
readily water soluble from contaminated samples, especially from evaporative mineral phases, while the release of As, Mo,
Sb, and Pb into the water is limited by adsorption processes. Results obtained from the application of multivariate techniques
on the water-soluble fraction data set show that the hazardous metals are categorized into three groups including (1) Ni,
S, Co, Cu, Cr, and Fe; (2) Se, Mn, Cd, and Zn; and (3) Sb, As, Mo, and Sn. This classification describes the hydro-geochemical
behavior of hazardous metals in water–sediment environments of the Sarcheshmeh porphyry copper mine and can be used as a basis
in remedial and treatment strategies. 相似文献
11.
云浮黄铁矿利用过程中微量毒害元素的环境化学活动性 总被引：13，自引：3，他引：13
为了解云浮黄铁矿利用过程中微量毒害元素的环境地球化学行为，客观评价它们对环境质量的影响，利用元素结合形态的连续提取实验方法，分析了云浮黄铁矿及其工业废渣中Co,Ni,Cu,Zn,As,Se,Cd,Sn,Sb,Pb和Tl等11种毒害元素的形态及化学活动性。结果表明，黄铁矿中大部分微量毒害元素都有着极强的化学活动性，各元素活动态浸出比例依次为Co96.3%,Se91.9%,Cu90.3%,Cd90.0%,Pb89.7%,Zn88.6%,Sb82.5%,Ni80.6%，Sn70%,Tl55.1%和As31.9％，元素As和Tl主要赋存于硫化物和硅酸盐矿物相中，另有少量的Cu,Pb和Sb可能赋存于碳酸盐矿物相中，其他元素则主要赋存于硫化物矿物相中。与黄铁矿相比，飞灰和灰渣中各元素可交换态和碳酸盐结合态所占的比例明显减少。废渣中各元素的化学活动性表现出很大的差别，其中Cu,Zn和Cd的化学活动性最强，活性态浸出比例在90％以上；其次是Co,Ni,Se,Pb和Tl，浸出比例在50％左右；Sb,As和Sn的稳定性较高，浸出比例分别为1％、5％和14％左右；飞灰中微量毒害元素的活动性均高于灰渣。 相似文献
12.
泉州城市表层土壤中金属元素来源分析 总被引：4，自引：0，他引：4
采集了泉州市47个城市表层土壤样,用ICP-MS检测技术,研究了土壤中26种重金属元素的富集特征、环境风险及污染来源。富集因子结果显示,与泉州市土壤背景值相比,Li、Ni、Co、Cu、Zn、Sr、Cd、Sn、Sb、Pb、Ta在城市表层土壤中的富集因子大于1,而Ti、V、Cr、Fe、Mn、Ga、Ge、As、Rb、Y、Nb、Cs、Bi、Th、U的富集因子小于1。从功能区上看,工业区污染最为严重,其次依次为农业区、商住区、城市绿地、交通区。环境风险指数表明,泉州市城市表层土壤中重金属污染具有极高的环境风险,达到极高风险级别的样品占48.9%。采用多元统计分析方法对土壤样品中各金属元素来源进行解析,结果表明,研究区城市表层土壤中金属元素总体可分成5类：①交通运输类（Sn、Pb、Sb、Bi）;②工业因子类（Cr、Co、Ni、Fe、Mn）;③自然因子类别（Ga、Ge、Ti、V、Cu）;④混合因子类别（Zn、Cd、Sr、Th、U、Y、As、Cs、Nb、Ta、Rb）;⑤生活垃圾因子类别（Li）。 相似文献
13.
三峡沉积物中重金属污染累积及潜在生态风险评估 总被引：6，自引：0，他引：6
分析了三峡库区主要支流表层沉积物样品中15种重金属元素（Cd、Cu、Pb、Zn、Cr、Tl、V、Mn、C、Ni、Sr、Ag、Sb、Sn和Mo）的含量水平和分布规律,并采用内梅罗污染指数、地累积指数法和潜在生态风险指数法,初步评价了沉积物中重金属污染状况和潜在生态风险。研究结果表明：（1）三峡库区支流表层沉积物中重金属Cd、Zn和Cu等呈现污染加剧态势,其含量范围分别为0.36-1.22 mg/kg、55.8-182 mg/kg、24.0-93.1 mg/kg;（2）内梅罗单因子污染指数（Ii）和地累积指数（Igeo）指示研究区域中Ag、Sb和Sn等多种重金属污染累积效应显著;（3）研究区域中多种重金属内梅罗多因子污染指数（Pn）和潜在生态风险指数（RI）分别为3.41-11.1和204-568,表明研究区域为重度重金属污染,潜在生态风险较高;（4）三峡库区主要支流表层沉积物呈现出以Cd为主的多种重金属复合污染特征。 相似文献
14.
Concentration and distribution of elements in Late Permian coals from western Guizhou Province,China
《International Journal of Coal Geology》2005,61(1-2):119-137
With the aim of better understanding geochemistry of coal, 71 Late Permian whole-seam coal channel samples from western Guizhou Province, Southwest China were studied and 57 elements in them were determined. The contents of Al, Ca, Co, Cr, Cu, Fe, Ga, Hf, K, Li, Mn, Mo, Nb, Ni, Sn, Ta, Ti, Th, U, V, Zr, and REEs in the Late Permian coals from western Guizhou Province are higher than the arithmetic means for the corresponding elements in the US coals, whereas As, Ba, Br, F, Hg, P, Se, and Tl are lower. Compared to common Chinese coals, the contents of Co, Cr, Cu, Ga, Hf, Li, Mn, Mo, Ni, Sc, Sn, Ti, U, V, Zn, and Zr in western Guizhou coals are higher, and As, F, Hg, Rb, Sb, Tl, and W are lower. Five groups of elements may be classified according to their mode of occurrence in coal: The first two, Group A, Tm–Yb–Lu–Y–Er–Ho–Dy–Tb–Ce–La–Nd–Pr–Gd–Sm, and Group B, As–Sr–K–Rb–Ba–F–Ash–Si–Sn–Ga–Hf–Al–Ta–Zr–Be–Th–Na, have high positive correlation coefficients with ash yield and they show mainly inorganic affinity. Some elements from Group B, such as Ba, Be, Ga, Hf, and Th, are also characterized by significant aluminosilicate affinity. In addition, arsenic also exhibits high sulfide affinity (rS–Fe>0.5). The elements, which have negative or lower positive correlation coefficients with ash yield (with exceptions of Bi, Cs, Nb, Mn, Se, and Ti), are grouped in other four associations: Group C, Cr–V–Mo–U–Cd–Tl; Group D, Hg–Li–Sc–Ti–Eu–Nb–Cs–W; Group E, Bi–Sb; and Group F, Co–Ni–Cu–Pb–Zn–Mg–Se–Ca–Mn–S–Fe. The correlation coefficients of some elements, including Co, Cr, Cu, Fe, Hg, Li, Mo, Ni, P, S, Sc, U, V, and Zn, with ash yield are below the statistically significant value. Only Cr and Cu are negatively correlated to ash yield (−0.07 and −0.01, respectively), showing intermediate (organic and inorganic) affinity. Manganese and Fe are characterized by carbonate affinity probably due to high content of epigenetic veined ankerite in some coals. Phosphorus has low correlation coefficients with any other elements and is not included in these six associations. There are five possible genetic types of enrichment of elements in coal from western Guizhou Province: source rock, volcanic ash, low-temperature hydrothermal fluid, groundwater, and magmatic hydrothermal inputs. 相似文献
15.
The geochemistry and mineralogy of samples collected along depth profiles from an As-rich tailing deposit with abundant calcite was studied to determine the processes that influence the mobility of Fe, Zn, Cu, Ni, Cd, As, Sb, Cr and Tl. In spite of their near neutral pH, almost all of them are acid potential generators. Total concentrations decreased as: Fe > As > Zn > Pb > Cu > Sb > Cd > Cr > Ni > Tl. Soluble contents were lower and followed a slightly different order. Mobility decreased as: Tl > Cd, Zn, Cu, Sb, Ni, As > Fe, Pb > Cr. Higher soluble concentrations of Fe, Cu, Zn, As, Pb, and Ni were found in low-pH samples and of Sb and Tl in near-neutral samples. Sulfide oxidation processes are developing in the tailing’s dam. These processes do not have a trend with depth but occur mainly in acid layers. Near neutral layers formed by primary sulfides and calcite probably correspond to wastes produced from the processing of ore coming mainly from pods within the skarn, and acid layers with abundant secondary minerals from material mined from chimneys and mantos. The presence of calcite influences speciation, neutralizes acid mine drainage (AMD), and decreases the mobility of most toxic metals and metalloids (TMMs). However, a hard-pan layer was not observed in the studied profiles. Retention of TMM within tailings probably occurs through the formation of low solubility metal carbonates and from elevation of pH that promotes Fe hydroxides precipitation that may retain As, Sb and metals. Calcite occurrence promotes As, Cd, Cu, Fe, Zn, Pb, Cd and Cr retention, does not play a role on Tl and Ni mobilization, and increases Sb release. 相似文献
16.
攀枝花钒钛磁铁矿区土壤重金属地球化学特征及污染评价 总被引：9，自引：0，他引：9
为了解攀枝花钒钛磁铁矿区土壤重金属的特征及污染程度,采集了矿区表层土壤样品和两个土壤剖面,用多种分析方法有针对性地分析了Cu、Pb、Zn、Ti、V、Co、Ni、As、Cd、Cr、Hg、Mn十二种元素。在分析分布特征基础上,对重金属进行了污染物负荷指数评价,结果发现:1)攀枝花钒钛磁铁矿矿区表层土壤大部分属于中等污染,少数属于强污染,个别达到了极强污染;2)Co、V、Cu、Cd、Ti几种元素的最高污染系数大,Zn、Mn、Ni、Cr四种元素的最高污染系数次之,Hg、Pb两种元素的最高污染系数较小,As的最高污染系数最小;3)从各区域的污染物负荷指数来看,排土场周围和朱矿采矿场下游附近污染程度较大,远离矿区以及矿区上游污染较小。 相似文献
17.
18.
Yaping Liu Shugui Hou Sungmin Hong Soon-Do Hur Khanghyun Lee Yetang Wang 《Environmental Earth Sciences》2011,63(2):311-320
Samples collected from a 0.87 m snow pit at a high altitude site in the Cho Oyu range, Himalayas were measured for V, Cr,
Mn, Co, Ni, Cu, Zn, As, Rb, Sr, Cd, Sn, Sb, Ba, Tl, Pb, Bi, Th, and U using inductively coupled plasma mass spectrometry.
In addition, major ions, oxygen stable isotopes, and microparticles were also measured to assist the interpretation of seasonal
variation of trace elements. The trace elements show a distinct seasonality, i.e., higher concentrations during the non-monsoon
season than those during the monsoon season. Significant correlation is observed between Ba and the other trace elements.
Crustal enrichment factor (EFc) analysis indicates that V, Mn, Co, Ni, Rb, Sr, and Th originate mainly from crustal dust, while anthropogenic inputs make
an important contribution to the other trace elements (i.e., Cu, Zn, As, Cd, Sn, Sb, Ti, Pb, Bi, and U). Evidence from air
mass back trajectories suggests that atmospheric trace element pollution reaching the studied area is transported dominantly
by Indian summer monsoon during the monsoon season, while it is transported mainly by the westerlies during the non-monsoon
season. 相似文献
19.
The mobilization, redistribution and fractionation of trace elements during chemical weathering processes have been investigated on a 4.05 m thick terra rossa profile overlying dolomite on the Yunnan-Guizhou Plateau, in Southwest China. In this in situ weathering profile, the ferromanganese concretions and the gibbsite spots coexist in the terra rossa saprolite. The mass-balance evaluation reveals that titanium, Nb and Hf in the terra rossa matrix are conservative elements during chemical weathering compared to Zr. The elements of Li, Sc, V, Cr, Fe, Ga, As, Mo, Cs, Ce, Ta, Tl, Pb and Th in the terra rossa matrix include additions from external sources. Beryllium, Mn, Co, Ni, Cu, Rb, Ba and La are depleted in the shallow parts of the terra rossa profile and enriched in the deep parts. The elements of Zn, Sr, Y, Cd, Sn and U in the terra rossa profile are lost during weathering. Compared to the terra rossa matrix, the ferromanganese concretions are significantly enriched in most trace elements, especially Mn, Co, Cd, Ce, Tl and Pb. In contrast, the gibbsite spots are depleted in all trace elements, except for U. The results regarding specific inter-element relationships indicate that most trace elements have different inter-element relationships in the ferromanganese concretions, the gibbsite spots and the terra rossa matrix. This suggests that the behavior of many trace elements during mobilization and redistribution differs from their behavior during incorporation into secondary mineral phases, especially the Mn and Fe oxides and/or oxyhydroxides in the ferromanganese concretions. It is worthy to note that the fractionation between Ce and Mn occurs under intensive chemical weathering conditions. Correspondingly, beryllium exhibits a similar geochemical behavior as that of rare earth elements (except for Ce) and Y during surface weathering. 相似文献
20.
The Ambassador U and multi-element deposit occurs on the SW margin of the Gunbarrel Basin, Western Australia. Low-grade, flat-lying
U mineralization averaging about 2 m thick at 0.03% U occurs in lignites at the redox front at the base of the weathering
profile within a laterally extensive palaeochannel network. Uranium is principally associated with organic matter within the
lignitic matrix, although rare discrete U minerals, such as coffinite and uraninite, are also present. The lignite is also
enriched in a suite of other elements, principally base metals and sulphur, with concentrations of 0.3 ≥ 1% Cu, Pb, Ni, Co,
Zn and total rare earth elements (REE) in some samples. Other element enrichments include: Cr, Cs, Sc, Se, Ta, Ti, Th, V and
Zr as detrital heavy minerals of Zr, Ti and REE (oxides and silicates) or authigenic minerals of Cu, Bi, Pb, Zn, Ni, Se, Hg,
Ti, Cr, Tl, V, U and REE (sulphides, vanadates, selenides, oxides, chlorides and native metals) and diffuse lignite impregnations.
The Ambassador deposit probably formed from the convergence of redox-active weathering processes to unique source/host rocks,
constrained within the palaeochannel. A proximal source of U and trace elements of lamproite/carbonatite origin is probable,
as constrained by U–Pb isotope and U–Th disequilibria studies. Uranium and other metals were precipitated syngenetically with
organic matter as it was deposited during a humid phase in the Late Eocene. Remobilization subsequently concentrated the metals
in the upper 2 m of the lignite. This may have occurred during one or more periods of weathering and associated diagenesis,
with the latest episode in the last 300,000 years. 相似文献