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Micropollutants: challenges in hydrogeology 总被引：2，自引：1，他引：1
Andreas Musolff 《Hydrogeology Journal》2009,17(4):763-766
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<正>Ophiolites are the best archives of the evolutionary history of ocean basins from their rift–drift and seafloor spreading stages to subduction initiation and final closure(Dilek and Furnes,2014).Mongolia,the major domain of the Central Asian Orogenic Belt,represent the accretionsubduction belts with remnants of ophiolites.Ophiolites are distributed in the Northern,Western,South and 相似文献
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Groundwater in China’s permafrost region is vital for humans and cold-climate ecosystems. Permafrost responses to global warming have significantly changed the spatio-temporal patterns and distribution of properties associated with the groundwater system. The main areas of current and past studies on permafrost hydrogeology in China include four aspects: groundwater distribution and dynamics in permafrost regions, interplay between groundwater and permafrost, the impact of permafrost degradation on groundwater, and the regional effect of groundwater changes on the environment in permafrost regions. Over the last 10 years, the development and use of coupled heat-transport and groundwater models have focused on the hydrogeology of permafrost, and on groundwater development and distribution in permafrost regions. Progress in groundwater-related research on issues surrounding permafrost regions of China are comprehensively summarized and discussed in this review paper, which should provide a theoretical basis for further study of the groundwater system and its effects on the ecological environment under climate change. 相似文献
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G. Simon Dr. D. H. M. Alderton Prof. E. F. Stumpfl Dr. T. Bleser 《Mineralogy and Petrology》1995,53(1-3):115-124
Summary Tellurantimony, Sb2Te3 has been recorded for the first Lime in Europe. It occurs in the epithermal precious metal deposits of western Romania: Nagyag (now Sacaramb), Stanija, and Magura-Hondal. The optical properties, chemical composition, and mineral associations of the tellurantimony are described. Significant contents of Pb, Au, Ag, and As have been noted, and these seem to be related to the specific occurrence and association. The tellurantimony-bearing assemblages probably formed under conditions of highf
Te2 and mean to lowf
S2.
Tellurantimon in Rumänien: Das erste Vorkommen in Europa
Zusammenfassung Zum ersten Mal wurde in Europa Tellurantimon (Sb2Te3) gefunden. Es tritt in epithermalen Lagerstätten von Edelmetallen in W-Rumänien auf. Nagyag (jetzt Sacaramb), Stanija und Magura-Hondol. Hier werden die optischen Eigenschaften, die chemische Zusammensetzung und die Mineralvergesellschaftungen von Tellurantimon beschrieben. Deutliche Gehalte an Pb, Au, Ag und As scheinen in Zusammenhang mit der Besonderheit dieser Vorkommen und dieser Vergesellschaftung zu stehen. Die Tellurantimonführenden Zusammensetzungen wurden wahrscheinlich unter hoherf Te2 und niedriger is mittlererf s2 gebildet.相似文献
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Pauline L. Smedley 《Journal of African Earth Sciences》1996,22(4):459-470
Arsenic concentrations in groundwaters from two areas in Ghana, the Obuasi area in the Ashanti region and the Bolgatanga area of the Upper East region vary from <1–64 μg 1−1 and <1–141 μg 1−1, respectively. Sulphide minerals such as arsenopyrite and pyrite are present in the Birimian basement rocks of both areas and these form the dominant As sources. The basement aquifer is overlain by a variable thickness (ranging from <10 m to >40 m) of weathered regolith and lateritic soil. Arsenic concentrations are low in the shallowest groundwaters, but increase at greater depths (40–70 m below ground level in Obuasi and 20–40 m in Bolgatanga). At depths greater than this, total As concentrations are relatively low. The lateral and vertical variations in dissolved As concentrations are controlled by ambient pH and redox conditions and by the relative influences of sulphide oxidation and sorption. In the weathered regolith and lateritic soils, oxidation has been extensive. Shallow groundwaters are oxidizing and acidic. Under these conditions, As is readily oxidized to As(V) and may precipitate as ferric arsenate or be sorbed onto ferric hydroxide surfaces. At greater depth, groundwaters have longer contact times with the aquifer minerals and pH values are therefore higher (>6.0 in Obuasi and >6.5 in Bolgatanga). The oxidation of sulphide minerals may proceed, but dissolved O is consumed during the process and mildly reducing conditions (Eh 200–300 mV) result. Sorption of As onto ferric hydroxide minerals is less favoured under such pH and redox conditions and the element is relatively mobile. At the greatest abstraction depths, groundwaters are more reducing (Eh ≤200 mV; dissolved O <0.1 mg 1−1) and few electron acceptors are available in the system to drive sulphide oxidation. Dissolved As concentrations therefore remain relatively low. The mildly reducing groundwaters in the sulphide-bearing basement aquifer are therefore of the poorest potable quality with respect to dissolved As concentrations. 相似文献
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Review: Micro-organic contaminants in groundwater in China 总被引：1，自引：0，他引：1
Weihong Dong Wei Xie Xiaosi Su Chuanlei Wen Zhipeng Cao Yuyu Wan 《Hydrogeology Journal》2018,26(5):1351-1369
Micro-organic contaminants (MOs) in groundwater, which may have adverse effects on human health and ecosystems worldwide, are gaining increased attention in China. A great deal of research has been conducted to investigate their sources, occurrences and behavior in aquifers. This paper reviews the main sources, distribution, concentrations and behavior of a wide range of MOs in groundwater in China. These MOs include well-established persistent organic pollutants—polycyclic aromatic hydrocarbons (PAHs), hexachlorocyclohexanes (HCHs), polychlorinated biphenyls (PCBs), endocrine disrupting chemicals (poly brominated diphenyl ethers (PBDEs), phthalic acid esters (PAEs), bisphenol A (BPA)—and some contaminants of emerging concern such as pharmaceutical and personal care products (antibiotics, caffeine, shampoos) and perfluorinated compounds (PFCs). The results reveal that the main MOs in groundwater are PAHs, organochlorine pesticides (OCPs), PBDEs, PAEs, and antibiotics. Moreover, some PFCs such as perfluorobutane sulfonic acid (PFBS), perfluorobutanoic acid (PFBA) and perfluorooctanoic acid (PFOA) have only recently been observed in groundwater as emerging organic contaminants. Additionally, most MOs are distributed in populated and industrialized areas such as the southeast coast of China. Finally, industrial emissions, wastewater treatment plant effluents and agricultural wastewater are found to be dominant sources of MOs in groundwater. Based on the existing pollution levels, regulation and amelioration of MOs are warranted. 相似文献
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V. Pawlowsky-Glahn 《Mathematical Geology》2005,37(7):671-672
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Antoinette M. Mannion 《GeoJournal》1993,31(4):347-354
Biotechnology is the manipulation of organisms to carry out specific processes. It has various applications that are relevant to many aspects of geography. At a fundamental level biotechnology is directed at manipulating energy flows, especially those in agriculture. Improved crop varieties, disease and pest control, as well as nutrient enhancement can all be achieved by biotechnology, culminating in increased agricultural productivity. There are significant environmental advantages though there are also constraints imposed by economic considerations. Mineral extraction, metal recycling and pollution abatement can also be improved by biotechnology which thus contributes to more efficient resource use and enhanced environmental quality. Food and fuel energy, notably biomass fuels, can also be so produced. The manifold implications of this technology for earth and social sciences thus require its inclusion in geographical studies. 相似文献
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《International Journal of Coal Geology》2005,61(3-4):141-196
The review presented covers: (a) historical introduction; (b) some analytical comments; (c) some peculiarities of the As geochemistry in environment; (d) an estimation of coal Clarke value of As; (e) some coals enriched in As; (f) mode of As occurrence in coal; (g) factors influencing the As distribution in coal matter and coal bed; (h) genetic topics; (i) some topics related to environmental impact of As by the coal combustion.The World average As content in coals (coal Clarke of As) for the bituminous coals and lignites are, respectively, 9.0±0.8 and 7.4±1.4 ppm. On an ash basis, these contents are higher: 50±5 and 49±8 ppm, respectively. Therefore, As is a very coalphile element: it has strong affinity to coal matter — organic and (or) inorganic but obligatory authigenic. The coalphile affinity of As is like that for Ge or S.There is strong regional variability of As distribution due to geologic variability of the individual coal basins. For example, bituminous coals in Eastern Germany, Czech Republic and SE China are enriched in As, whereas the coals in South Africa or Australia are very depleted compared to coal Clarke of As. In general, some relationship exists between As content and its mode of occurrence in coals. Typically, at high As content, sulphide sites dominate (pyrite and other more rare sulphides), whereas at low As content, Asorg dominates, both being authigenic. A contribution of the terrigenic As (in silicates) is usually minor and of the biogenic Asbio (derived from coal-forming plants) is poorly known.Both organic and inorganic As can exist not only as chemically bound form but also in the sorbed (acid leacheable) arsenate form. With increasing coal rank, sorbed exchangeable arsenate content decreases, with a minimum in the coking coals (German data: the Ruhr coals).Relations of As content in coal to ash yield (or its partitioning in sink–float fractions) and to coal petrographic composition are usually complicated. In most cases, these relations are controlled by main site (form) of As — Aspyr or Asorg. If Aspyr dominates, an As accumulation in heavy fractions (or in high-ash coals) is observed, and if Asorg dominates, it is enriched in medium-density fractions (or low- and medium-ash coals). Arsenic is in part accumulated in the inertinite vs. vitrinite (Asorg ?).There are four genetic types of As accumulation on coal: two epigenetic and two syngenetic: (1) Chinese type—hydrothermal As enrichment, sometimes similar to known Carlin type of As-bearing telethermal gold deposits; (2) Dakota type—hypergene enrichment from ground waters draining As-bearing tufa host rocks; (3) Bulgarian type—As enrichment resulting from As-bearing waters entered coal-forming peat bogs from sulphide deposit aureoles; (4) Turkish type—volcanic input of As in coal-forming peat bog as exhalations, brines and volcanic ash.During coal combustion at power plants, most of the initial As in coal volatilizes into the gaseous phase. At the widely used combustion of pulverized coal, most of Asorg, Aspyr and “shielded” As-bearing micromineral phases escape into gaseous and particulate phase and only minor part of Asclay remains in bottom ash. The dominant fraction of escaping As is in fly ash. Because 97–99% of the fly ash is collected by electrostatic precipitators, the atmospheric emission of As (solid phase and gaseous) is usually assumed as rather minor (10–30% from initial As in coal). However, fly ash disposal creates some difficult environmental problems because it is potentially toxic in natural waters and soils. The As leaching rate from ash disposal is greatly controlled by the ash chemistry. In natural environment, As can be readily leached from acid (SiO2-rich) bituminous coal ashes but can be very difficult from alkali (CaO-rich) lignite ashes.If the Aspyr form dominates, conventional coal cleaning may be an efficient tool for the removing As from coal. However, organic-bound or micromineral arsenic (“shielded” grains of As-bearing sulphides) are not removed by this procedure.Some considerations show that “toxicity threshold” of As content in coal (permissible concentration for industrial utility) may be in the range 100–300 ppm As. However, for different coals (with different proportions of As-forms), and for different combustion procedures, this “threshold” varies. 相似文献
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With improvements on high-pressure experimental techniques in multi-anvil apparatus and the development of new analytical tools, major progress has been made on diffusion in garnets in the past several decades. The data obtained in the experimental determination of diffusion coefficients in garnets are of fundamental importance for diffusion modeling and timescales of geological and planetary processes. In this review, we have compiled experimental data on self-diffusion (Si, O, cations), trace element diffusion (Li, Y, Ga, Cr, Sr, REEs), and interdiffusion (Ca–Fe/Mg, Si–Al) in garnet in the light of new advances and recent applications. In addition, some empirical relationships among diffusion parameters (pre-exponential factor D 0, activation energy E, ionic radius) are also discussed. We hope that this review can provide a useful data digest and guide to future study of diffusion in garnet. 相似文献
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《China Geology》2018,1(2):286-303
Nanogeology is a subject that is a combination of geology and nanoscale science, and it has been a frontier field in recent years. It is also a new subject with the features of intersectionality and multidisciplinary. Digging deeper into geological problems and nanoscale phenomena helps better revealing the more essential mechanisms and processes in geological science, which is also an evitable path in the development of geology. In this paper, we elaborate the concept, feature and main subdisciplines, and summarize three stages of nanogeology development from preliminary research in the 1990s to subject formation in China. After summarizing the researchers’ achievements in this field, we illustrate some primary research progresses of nanogeology in China as eight subdisciplines. On the basis of the above content, we propose the development prospect of nanogeology in China. There are many geologic problems with scientific values and economic benefits, such as research of geologic fundamental problems, resource exploration and development, mechanism study and prediction of geological activities (disasters), mechanism research and management of environmental pollution and others. Nanogeology has a great potential in China to solve all of these problems. As a result, the theories and methods of nanogeology will become enriching and advanced. It offers important theoretical basis and technological methods to deal with major issues concerning the national economy and the people’s livelihoods, such as the prediction of geological activities, as well as resource distribution and its exploration and utilization. 相似文献
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Raj Bala 《Geoforum》1982,13(3):257-262
This paper deals with the mode of emergence, population size, functional nature and distributional pattern of new towns in India as recorded at the 1971 Census. It was discovered that (i) an overwhelming majority of new towns were not new settlements but expanded villages. The rest owed their status to one of four situations: an independent town is carved out of an existing urban place; neighbouring towns are merged into a new unit; a declassified town in 1961 gets reclassified in 1971; and a new town is built, usually on planned lines; (ii) mode of emergence was the most vital factor in determining demographic attributes; (iii) new towns represented two contrasting tendencies in Indian urbanisation: concentrated urbanisation around metropolitan nodes and dispersed urbanisation in recently developing backward regions. 相似文献
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John J. Metz 《GeoJournal》1995,35(2):175-184
Despite billions of dollars provided by donors, Nepal's quest for development remains unfulfilled. Nepal's rugged topography is a serious obstacle, but this development failure has social roots. The first root is Nepal's power structure. A feudal elite, supported by British India, controlled Nepal until 1951, extracted and wasted the agricultural surplus, and excluded all modern influences. The post-1951 government adopted development as its goal and justification, but was still controlled by the same elite. Rivalries between the superpowers and between India and China produced a flow of foreign aid which has tripled each decade. Through its control of the state, Nepal's elite has directed and diverted foreign aid into channels which consolidate its power. This is manifested in the pervasive corruption, which is essential, not accidental, to the system. The second root of Nepal's development failure is inappropriate development theories, which have emphasized investment in infrastructure, but have ignored most of the 90% of the population who are subsistence farmers. The third root is the consistently dismal implementation of development projects by indigenous and expatriate development workers. The institutional ignoring of corruption amounts to collusion between foreign aid donors and indigenous elite. 相似文献