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231.
Qing-wei Yang Qing Zeng Fei Xiao Xue-lian Liu Jin Pan Jin-feng He Zhi-yong Li 《Environmental Earth Sciences》2013,68(4):1127-1134
Up to date, very few studies have examined the phytoextraction ability of hyperaccumulators in the real soils contaminated with heavy metals following the identification of the hyperaccumulators using hydroponics tests. In the present study, amended with a chemical-mobilizing agent of ethylene diamine triacetic acid (EDTA), the manganese accumulation, tolerance and the hyperaccumulating ability of two hyperaccumulators Phytolacca americana L. (Phytolaccaceae) and Polygonum hydropiper L. (Polygonaceae) proved by previous hydroponics tests were examined using pot experiments with paddy soils contaminated with Mn (1,047 ± 53 mg kg?1) collected from one site in the vicinity of one manganese mine in Xiushan county of Chongqing, China. Results showed that the root and shoot biomass of P. americana and the chlorophyll production of P. hydropiper were significantly inhibited by EDTA treatments while the chlorophyll production of P. americana was oppositely obviously promoted by EDTA. It is noteworthy that, with or without EDTA treatment, the shoot Mn concentrations of both plant species were significantly below the hyperaccumulator threshold, indicating these two plants concealed their hyperaccumulating ability in the studied soils. Thus, further detailed studies need to be conducted to promote the metal hyperaccumulating capacity of these two plant species under comparably low Mn-contaminated soil conditions as shown in this study before the successful application of these Mn hyperaccumulators identified in laboratories to the phytoextraction of lightly or moderately Mn-contaminated agricultural soils. 相似文献
232.
The occurrence and development of riparian forests, which were mainly dominated by mesophytes species related closely with
surface water. Since there was no water discharged to the lower reaches of Tarim River in the past three decade years, the
riparian forests degrade severely. The groundwater table, the saline content of the groundwater, as well as the content of
free proline, soluble sugars, plant endogenous hormones (abscisic acid (ABA), and cytokinins (CTK)) of the leaves and relative
rates of sap flow of the Populus euphratica Oliv. (arbor species), Tamarix ramosissima Ldb. (bush species), and Apocynum venetum L. (herb species) were monitored and analyzed at the lower reaches of the Tarim River in the study area where five positions
on a transect were fixed at 100 m intervals along a sampling direction from riverbank to the sand dunes before and after water
release. The physiological responses and acclimation strategies of three species to variations in water and salinity stress
were discussed. It was found that A. venetum population recovered to groundwater table ranging from −1.73 to −3.56 m, and when exposed to saline content of the groundwater
ranging from 36.59 to 93.48 m mol/L; P. euphratica appeared to be more sensitive to the elevation of groundwater table than the A. venetum and T. ramosissima at groundwater table ranging from −5.08 to −5.80 m, and when exposed to saline content of the groundwater ranging from 42.17
to 49.55 m mol/L. T. ramosissima tended to be the best candidate species for reclamation in this hyper-arid area because it responded to groundwater table
ranging from −1.73 to −7.05 m, and when exposed to saline content of the groundwater ranging from 36.59 to 93.48 m mol/L.
These results explained the distribution patterns of desert vegetation in the lower reaches of the Tarim River. Understanding
the relationships among ecological factors variables, physiological response and acclimation strategies of plant individuals
could provide guidance to sustainable management, reclamation and development of this and similar regions. 相似文献
233.
Pan Wu Changyuan Tang Congqiang Liu Lijun Zhu TingQuan Pei Lijuan Feng 《Environmental Geology》2009,57(7):1457-1467
The chemical characteristics, formation and natural attenuation of pollutants in the coal acid mine drainage (AMD) at Xingren
coalfield, Southwest China, are discussed in this paper based on the results of a geochemical investigation as well as geological
and hydrogeological background information. The chemical composition of the AMD is controlled by the dissolution of sulfide
minerals in the coal seam, the initial composition of the groundwater and the water–rock interaction. The AMD is characterized
by high sulfate concentrations, high levels of dissolved metals (Fe, Al, Mn, etc.) and low pH values. Ca2+ and SO4
2− are the dominant cation and anion in the AMD, respectively, while Ca2+ and HCO3
− are present at significant levels in background water and surface water after the drainage leaves the mine site. The pH and
alkalinity increase asymptotically with the distance along the flow path, while concentrations of sulfate, ferrous iron, aluminum
and manganese are typically controlled by the deposition of secondary minerals. Low concentrations of As and other pollutants
in the surface waters of the Xingren coalfield could be due to relatively low quantities being released from coal seams, to
adsorption and coprecipitation on secondary minerals in stream sediments, and to dilution by unpolluted surface recharge.
Although As is not the most serious water quality problem in the Xingren region at present, it is still a potential environmental
problem.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
234.
通过对具有不同初始含水率和干密度的两种压实黏质砂土的脱湿曲线进行测试、分析和对比,并结合核磁共振技术,探讨了干密度、初始含水率和土样组分对压实黏质砂土脱湿过程的影响规律。利用核磁共振测得了试样在各级吸力下的T2时间(横向弛豫时间)分布曲线,定性地探讨了不同吸力下试样中的水分分布特征,揭示了干密度、初始含水率和土样组分对试样脱湿过程的微观机制影响。试验结果表明:干密度仅在低基质吸力条件下对试样脱湿过程产生重要影响,而在高吸力条件下初始含水率和试样组分起主导作用;核磁共振结果证实在压实黏质砂土中,小孔隙结构主要由初始含水率和试样组分控制,而大孔隙的结构主要取决于干密度;试样组分对压实土的内部结构和孔隙大小分布的影响比初始含水率大。 相似文献
235.
东天山-北山金矿集区是我国重要的金矿集区之一。近年来,该矿集区东部的大青山金矿综合运用多种勘查方法,取得了显著的找矿成果。为了查明成矿期构造特征,进一步指导找矿,通过对已取得勘查资料的综合整理及矿区成矿构造的详细观测解剖,采用野外观察与室内分析相结合、宏观与微观相结合的研究方法,对控矿结构面、成矿期的构造特征及矿体分布规律进行研究。研究表明:大青山金矿床主矿体均位于NEE走向的压扭性逆断层中,主含矿断层受控于矿区北西部的F13;主矿体具有薄而富、尖灭再现的特征,整体向SW侧伏,矿体围岩蚀变强烈,主要为绢云母化、绿泥石化、碳酸盐化;成矿期构造应力场为NW-SE方向挤压,自现有矿体向SW寻找深部新矿是有意义的。 相似文献
236.
A new multidimensional scaling (MS) technique, referred to as the Pijk model, is formulated on the basis of associations among triple objects (samples or variables), instead of pairs of objects as used in the usual MS methods, such as factor analysis. The computational scheme provided for this method is the reduction of an original problem to a standard eigenvalue-eigenvector problem. The major goal of the technique is simplification and reduction of data structures and the rescaling of original objects into a new and reduced space, so that patterns and relations of the original objects can be conventiently examined in two-dimensional factor plots. The Pïjk method is illustrated and tested by using a set of geochemical data related to the epithermal gold and silver vein deposits in the Walker Lake quadrangle of Nevada and California. The characteristics of element associations suggested in the Pijk analysis are consistent with field observations. A preliminary comparison between the new method and the ordinary factor analysis also is made on the basis of the same data set. Results are encouraging in that analysis by the Pijk model captures triple-object associations that might be missed by the ordinary factor analysis which considers only pair-variable correlations 相似文献
237.
Yang Guangming Pan Zhaolu Wu Xiuling Liu Xiangwen
China University of Geosciences Wuhan 《中国地质大学学报(英文版)》1991,(1)
Chevkinite specimen from a rare-earth mineral deposit in Sichuan,southwest ofChina have been studied in detail by means of transmission electron microscope(TEM).The selected area electron diffraction(SAED)and convergent beam electron diffraction(CBED)patterns,obtained from different crystal zone axis direction,proved coineidently that the space group of chevkinite is C2/m.Fringe lattice image obser-vation showed the mineral crystal is structurally uniform in microscale,and it is anideal specimen for electron diffraction analysis.The mineral studied here is similar to theone from Bayan Obo,Inner Mongolia,China,in chemical composition and REE distri-bution.The chemical formula of the crystal is(Ce,La,…,Ca)_4 Fe~2-(Fe,Ti,Nb)_2O_8 (Si_2O_7)_2 .From our study,we come to the conclusion that the space group of the natu-ral chevkinite is C2/m,instead of P2_1/a as synthetic one.Up to now,chevkinitecompositionally similar to the synthetic one,in which the complete replacements of Ce,La by Nd and Fe by Mg or Co o 相似文献
238.
某水电工程地应力场数值模拟研究 总被引:2,自引:2,他引:2
运用有限元法模拟位于深切河谷中的某水电工程区地应力场的形成过程,并与地应力的实测成果进行拟合分析。在此基础上,对研究区的一些特殊现象进行解释。 相似文献
239.
Li Yunlong Cheng Jianzhong Lee Xinqing Chen Yi Gao Weichang Pan Wenjie Tang Yuan 《中国地球化学学报》2019,38(1):1-7
Acta Geochimica - Biochar is a soil amendment for increasing soil quality and decreasing nutrient leaching. However, there is little information on the impact of biochar-based fertilizer (BF) on... 相似文献
240.
Recharge source and hydrogeochemical evolution of shallow groundwater in a complex alluvial fan system,southwest of North China Plain 总被引:4,自引:0,他引:4
Fadong Li Guoying Pan Changyuan Tang Qiuying Zhang Jingjie Yu 《Environmental Geology》2008,55(5):1109-1122
Many cities around the world are developed at alluvial fans. With economic and industrial development and increase in population,
quality and quantity of groundwater are often damaged by over-exploitation in these areas. In order to realistically assess
these groundwater resources and their sustainability, it is vital to understand the recharge sources and hydrogeochemical
evolution of groundwater in alluvial fans. In March 2006, groundwater and surface water were sampled for major element analysis
and stable isotope (oxygen-18 and deuterium) compositions in Xinxiang, which is located at a complex alluvial fan system composed
of a mountainous area, Taihang Mt. alluvial fan and Yellow River alluvial fan. In the Taihang mountainous area, the groundwater
was recharged by precipitation and was characterized by Ca–HCO3 type water with depleted δ18O and δD (mean value of −8.8‰ δ18O). Along the flow path from the mountainous area to Taihang Mt. alluvial fan, the groundwater became geochemically complex
(Ca–Na–Mg–HCO3–Cl–SO4 type), and heavier δ18O and δD were observed (around −8‰ δ18O). Before the surface water with mean δ18O of −8.7‰ recharged to groundwater, it underwent isotopic enrichment in Taihang Mt. alluvial fan. Chemical mixture and ion
exchange are expected to be responsible for the chemical evolution of groundwater in Yellow River alluvial fan. Transferred
water from the Yellow River is the main source of the groundwater in the Yellow River alluvial fan in the south of the study
area, and stable isotopic compositions of the groundwater (mean value of −8.8‰ δ18O) were similar to those of transferred water (−8.9‰), increasing from the southern boundary of the study area to the distal
end of the fan. The groundwater underwent chemical evolution from Ca–HCO3, Na–HCO3, to Na–SO4. A conceptual model, integrating stiff diagrams, is used to describe the spatial variation of recharge sources, chemical
evolution, and groundwater flow paths in the complex alluvial fan aquifer system. 相似文献