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1.
GU Shangyi WAN Guojiang MAO Jianquan 《中国地球化学学报》2007,26(4):434-438
The Pinxiang weathering profile is well developed on Early Triassic dacite lavas of the Baisi Formation. At the top of the profile is developed a red clay zone which is characterized mineralogically by kaolinite, iron oxide minerals, quartz, and a small amount of illite, montmorillonite and vermiculite. In going downwards the red clay zone gives way to a saprolite zone in which plagioclase pseudomorphs have been well preserved although replaced by kaolinite. Beneath the saprolite zone is the saprock zone characterized by less weathering for dacite. At the bottom of the weathering profile is the parent material, dacite, which is composed mainly of plagioclase, quartz, K-feldspar and biotite which have been largely altered into chlorite owing to submarine extrusion of dacite lavas. Some layers in the weathering profile show obvious sodium enrichment and potassium depletion relative to others. In the Al2O3-(CaO* Na2O)-K2O triangular diagram, the weathering trends of these layers in the middle stage are remarkably deviated from normal ones. Both mineralogy and micro-morphology of these layers indicate such deviation resulted from sodic metasomatism of orthoclase. 相似文献
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N. V. Lebedeva O. L. Zimina N. N. Fateev A. L. Nikulina I. V. Berchenko N. I. Meshcheryakov 《Geochemistry International》2018,56(4):332-343
The first data were obtained on the total mercury content in hydrobionts and their habitat in Grønfjorden, Spitsbergen, at the waste discharge sites of the settlement of Barentsburg in early spring 2017. The Hg concentration was below the detection limit in the water and varied from 7.1 to 42.3 ng/g of dry weight in the bottom sediments. Mercury concentration in the hydrobionts increased toward the inner fjord and was higher near the mouth of the Grøndalen River, which flows into the fjord. Elevated Hg concentrations at the mouth of the Grøndalen River indicate that much of the toxic metal is brought to the inner part of the fjord with riverine runoff, and this Hg source is likely more important than the surface supply of Hg transferred from local surface pollution centers at Barentsburg. The Hg concentration depended on the position of the marine organisms in the trophic chain and was the highest in the detritophage mollusks Thyasira gouldi, Cardium sp., and Macoma calcarea, the specialized predatory sea snail Cryptonatica affinis, and the cod Gadus morhua, which is a benthosophage–secondary predator. The total Hg concentrations in the hydrobionts and their habitat in Grønfjorden were generally relatively low and close to the background one. 相似文献
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Karen R. Burow Bryant C. Jurgens Kenneth Belitz Neil M. Dubrovsky 《Environmental Earth Sciences》2013,69(8):2609-2621
A regional assessment of multi-decadal changes in nitrate concentrations was done using historical data and a spatially stratified non-biased approach. Data were stratified into physiographic subregions on the basis of geomorphology and soils data to represent zones of historical recharge and discharge patterns in the basin. Data were also stratified by depth to represent a shallow zone generally representing domestic drinking-water supplies and a deep zone generally representing public drinking-water supplies. These stratifications were designed to characterize the regional extent of groundwater with common redox and age characteristics, two factors expected to influence changes in nitrate concentrations over time. Overall, increasing trends in nitrate concentrations and the proportion of nitrate concentrations above 5 mg/L were observed in the east fans subregion of the Central Valley. Whereas the west fans subregion has elevated nitrate concentrations, temporal trends were not detected, likely due to the heterogeneous nature of the water quality in this area and geologic sources of nitrate, combined with sparse and uneven data coverage. Generally low nitrate concentrations in the basin subregion are consistent with reduced geochemical conditions resulting from low permeability soils and higher organic content, reflecting the distal portions of alluvial fans and historical groundwater discharge areas. Very small increases in the shallow aquifer in the basin subregion may reflect downgradient movement of high nitrate groundwater from adjacent areas or overlying intensive agricultural inputs. Because of the general lack of regionally extensive long-term monitoring networks, the results from this study highlight the importance of placing studies of trends in water quality into regional context. Earlier work concluded that nitrate concentrations were steadily increasing over time in the eastern San Joaquin Valley, but clearly those trends do not apply to other physiographic subregions within the Central Valley, even where land use and climate are similar. 相似文献
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Ⅰ.INTRODUCTION Diatomaceous earth is known to occur in the vicinity of Shanwang,(Long.118°34'E,Lat.36°32'N)Linchü district,Shantung.The sitewhich has furnished the material discussed in this report,lies 2 li and 相似文献
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A.R. Selby 《Geotechnical and Geological Engineering》1999,17(3-4):351-371
Tunnelling through soils results in ground loss, causing surface settlements and transverse movements. Where the tunnel drive passes below an existing structure, it is important to estimate the effects upon the structure. However, the free ground deformations should not simply be imposed upon a structure, because the structure contributes to stiffening of the ground. A computational soil-structure interaction analysis is required, to otain detailed stress–deformation response. First, linear finite element and Lagrangian finite difference methods are used to estimate ground movements due to a tunnel in free ground, and the results are compared with values based on empirical equations. The two linear methods and an additional hybrid FE method are then used to assess with soil-structure interaction; two cases of a typical short wall and a long wall lying across the route of tunnels of different depths. The results support the validity of the hybrid method which is used to estimate interactive ground settlements for comparison with a reported case of tunnelling below a building in central London. A more detailed case study is then undertaken to assess building damage caused by gross settlements during tunnelling in mixed soils, at a site in Workington, west Cumbria. A survey allowed estimation of free ground movements. Analysis by the hybrid method on the soils plus uncracked structures indicated intolerable horizontal stresses. Re-analysis with major cracks introduced into the structures resulted in close agreement between measured and computed settlements. 相似文献
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Xiaoyu ZHAO Wuyi WANG Hairong LI Fujian FENG Lizhen WANG 《中国地球化学学报》2006,25(B08):80-81
Brick-tea-type fluorosis is a peculiar endemic disease in China, which had been discovered in minority areas of western China since 1980, and distributed mainly in Tibet, Inner Mongolia, Gansu, Xinjiang, Qinghai and parts of Sichuan Province. The prevalence rate of fluorosis in Tibetan and Mongolian nationality people was higher. Epidemiological investigation showed that fluorosis morbidity and degrees were different in different brick-tea drinking areas, and it was probably caused by drinking various kinds of brick tea from different regions. Therefore, we collected 33 samples of brick tea from six provinces where minority nationalities were accustomed to drinking a large quantity of brick tea. F concentrations were determined by the combustion hydrolysis-ion selective electrode method. The results showed that among the brick teas, the F concentrations ranged from the minimum 74.1 mg/kg in Yunnan Province to the maximum 991.2 mg/kg in Sichuan Province. Besides, there was a great difference among the various kinds of brick tea, and F concentrations decreased in the order of Kang brick tea, Green brick tea, Black brick tea, Mi brick tea, Fu brick tea, Chitsu ping tea, Puerh tea, and Tuo tea. The average F concentration in brick teas was 431.92 mg/kg. 相似文献
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Baiyun Cave in Naigu Shilin,Yunnan Karst,China 总被引：1，自引：3，他引：1
The Baiyun cave is a 380 m long karst cave in the Naigu Shilin, situated 70 km southeast of Kunming, Yunnan Province, China. The prevailing orientations of the cave passages are N110°-120°E and N0°-10°W and those of the fissures in the cave are N30°-40°W and N20°-30°W. The cave is developed in the thick-bedded Lower Permian Qixia Formation. The cave has an active water flow and is currently at the near water-table stage. There are large amounts of different infills of cave sediments. The cave shows different stages of paragenesis. The palaeomagnetic analysis of cave sediments shows that their ages are younger than 780 ka B.P. (the Brunhes Chron). The upper part of the sampled profile belongs to the reverse Blake event (112.3-117.9 ka B.P.). The formation of the Baiyun cave is directly connected with the development of the Naigu Shilin. The formation of karst underground and surface features depends on the regional tectonic deformation and the Cenozoic extension of the study area. 相似文献
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Zhengyu BAO Shengying QIAO Yueming HOU 《中国地球化学学报》2006,25(B08):4-4
The urban environment quality is of vital importance as the majority of people now live in cities. Due to the continuous urbanization and industrialization with rapidly increasing economy in China, metals are continuously emitted into soils, imposing a great threat on human health. Urban soils might be affected by industrial activities, transport, agricultural practice, and waste disposal. An extensive survey was conducted in the highly urbanized Zhangzhou City （Fujian Province, China） using a systematic sampling strategy. Concentrations of Hg, Cd, Pb, Zn, Cu, As, Cr and Ni were measured on 108 topsoil samples collected from parks （0-15 cm）, residential areas and suburban agricultural soils. Statistic approach （cluster analysis） was adopted for identification of natural and anthropogenic influence on heavy metal contents. The maps of metal concentrations in surface soils were made based on geographical information system （GIS） data. All of these aim at assessing the distribution of these heavy metals in the urban environment. 相似文献
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DUO Ji WEN Chunqi FAN Xiaoping GUO Jianci NI Zhiyao LI Xiaowen SHI Yuruo WEN Quan 《《地质学报》英文版》2006,80(6):954-956
A detrital zircon aged 4.1 Ga is discovered by the SHRIMP U-Pb method in a quartzite in Burang County, western Tibet. This is presently the oldest single-grain detrital zircon in China. The Th-U ratios of the two testing points of the 〉4.0 Ga zircon are between 0.76 and 0.86, indicating their magmatic origin. This discovery has offered an important age for investigating the geological evolution of the Qinghai-Tibet Plateau. 相似文献
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LIU Jianqiu WU Cairong WANG Shaohong CHEN Binghua FANG Yulin YU Mingtong 《《地质学报》英文版》2007,81(5):722-726
The paleoforest remains studied are distributed within a range of 18000 m^2 in the intertidal zone of the Qianhu Bay, Fujian Province. Eighty-nine ancient tree stumps can be clearly recognized in the paleoforest remains. Microscopic studies of 10 relatively low-carbonized stump samples definitely showed four species： Glyptostrobus pensUi （Staunt） Kouch, Schima superba Gardn., Cinnamomum Schaeffer, and Litsea Lam. The 14^C dating of some samples yielded the ages of 42560±350 to 〉43000 a B. P., corresponding to the late Late Pleistocene. 相似文献
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In February 2010, 19 fatalities and economic damage were caused by a regional landslide episode in the state of Michoacán, México. The municipalities of Angangueo, Ocampo, Tiquicheo de Nicolás Romero, Tuxpan, and Tuzantla were severely damaged, with Angangueo being the most affected. The event involved a series of debris flows, of which four were the most significant; these four caused 16 deaths in addition to considerable damage to roads, electricity, and the water supply system, with indirect consequences in crop production, cattle farming, and tourism. The area affected by these four flows was calculated as 282?km2, with an estimated 697,346?m3 of mobilized material. General observations indicated that the initiation sources of the debris flows were on deforested zones. The present research is concentrated on the Angangueo basin, an area situated within the Monarch Butterfly Biosphere Reserve. Given the lack of rain gauges in the area of interest, records from neighboring points were used to build a comprehensive overview of the extreme precipitation event that triggered the devastating debris flows. The nearest rain gauge, Laguna del Fresno, situated 21?km to the south, recorded 204?mm of rainfall from 1 to 5 February, equivalent to 30% of the mean annual rainfall. Moreover, during a 24-h period the El Bosque rain gauge recorded 144.5?mm of precipitation, the equivalent of 2,270% of the mean rainfall for the same month (6.36?mm). The occurrence of a hailstorm preceding the rainfall event is notable; conditions in the superficial soil layer would have included an increased pore water pressure. Presumably, before the 2,000-year return period extreme rainfall event, thawing of hail and consequent moisture and/or pore-pressure increase result in decreased frictional strength. This paper presents a spatial analysis of the distribution of these landslides, mainly debris flows, as well as general observations on the triggering mechanism, the strength properties of the materials involved, and the societal impact. 相似文献
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《Applied Geochemistry》2006,21(4):684-700
Selenium deficiency was suspected to be a factor in the aetiology of esophageal cancer in the Linxian and Cixian regions of the People’s Republic of China and vitamin trials in the Linxian area indicated that combined supplementation with β-carotene, vitamin E and Se reduced the mortality rate. In order to further evaluate the role of Se, the distribution of total Se in cultivated topsoils, grain, human hair and drinking water was studied in 15 villages in the Cixian area, People’s Republic of China, which in the 1980–1990s had one of the highest mortality rates from esophageal cancer in the world. This study demonstrated that total Se concentrations in drinking water, soil, grain and hair increase from the low esophageal cancer area to the high cancer area, contrary to the expected trend. This suggests that Se deficiency does not play a major role in the aetiology of esophageal cancer in the study area. Nitrate in drinking water is much higher in the area with high esophageal cancer mortality rate than in the low mortality rate area, and this may be a significant factor. Mycotoxins (especially fumonisin), nitrosamine and nitrosamine precursors in grain, in drinking water, and dietary β-carotene and Vitamin E remain as potential factors which need to be evaluated further. 相似文献
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《中国地球化学学报》2006,(Z1)
Since 1999, eco-geochemical survey has been carried out in more than 20 provinces, municipalities and autonomous regions in China. The eco-geochemical survey was named from Russia literature and defined as a subject on research mechanisms of transportatio… 相似文献
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Guangle QIU Xinbin FENG Shaofeng WANG Xuewu FU Ping LI 《中国地球化学学报》2006,25(B08):28-28
Mercury as a toxic element poses environmental concerns, especially in historically Hg-mined districts. The Wanshan Hg mine located in the eastern part of Guizhou Province, southwestern China, ranks the largest Hg-producing district in China. Mining at Wanshan was initiated in 221 B.C., but ceased in 2001. Approximately 22000 tons of Hg, 6000 tons of cinnabar and large quantities of mine-wastes had been produced at Wanshan. Significant quantities of calcines, which were piled irregularly near the old mine processing sites and retorts, continue to impact the local environments in the Wanshan area. In this study, a regional contamination of mercury in surface waters collected from the Meizixi, Dashuixi, Huandao and Gaolouping rivers, whose upstreams or branches originate from the hilly karstic area and receive drainage arising from the calcines, was investigated by determining all Hg species in a base-flow and a flood-flow season. Reactive, dissolved, particulate, and total Hg concentrations in surface water varied from 0.60 to 400 ng/L, 11 to 430 ng/L, 1.4 to 9210 ng/L, and 15 to 9260 ng/L, respectively. Total methylmercury in water samples ranges from 0.31 to 25 ng/L. The concentrations of total Hg and particulate Hg in water samples collected during the flood season are higher than those in the base-flow season, whereas, the concentrations of dissolved and reactive Hg are lower with the peak values observed in water samples collected in the base-flow season. A strong positive correlation between total Hg and particulate Hg is noticed in the water samples collected from Hg-mined areas with the proportion higher than 80%. 相似文献
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《Geoforum》2016
Cattle-raising, especially for dairy, has expanded in the Ecuadorian Andes since the late 1990s as smallholding farmers have shifted their livelihood activities away from crop-based agriculture due to changes in climate, market conditions, and rural out-migration. Non-migrants constructing cattle-based livelihoods are turning to cattle as the basis for “viable” livelihoods in order to remain in depopulating rural parishes. Non-migrant farmers express ideals such as autonomy and tranquility as reasons for their attachment to rural places. In turn, their livelihood activities remake these places materially. Drawing on Tim Ingold’s conceptualization of taskscape and landscape, I argue that cattle-based livelihoods create a taskscape prone to human–wildlife conflict. Since 2009, residents have reported dozens of Andean bear attacks on cattle. Cattle are vulnerable capital assets. They represent both an investment with daily and weekly dividends over many years, in the form of milk, and a long-term form of wealth storage. The turn to cattle-based livelihoods in this region has thus heightened human–bear conflict. The phenomenon of the human–bear conflict is therefore a product of shifting livelihoods and accompanying changes in the taskscape. This analysis demonstrates the importance of listening to narratives of place attachment and accounting for the cultural logics of livelihood choices when considering interventions to address human–wildlife conflict. 相似文献
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Special Xenoliths in an Aegirine-Augite Syenite Porphyry in Liuhe, Yunnan, China： Discovery and Implications 总被引：1，自引：1，他引：0
LIU Xianfan SONG Xiangfeng LU Qiuxia TAO Zhuan LONG Xunrong ZHAO Fufeng Chengdu University of Technology Sichuan China State Key Laboratory of Geological Processes Mineral Resources China University of Geosciences Hubei China No. Geological Party Sichuan Bureau of Geology Mineral Exploration Development Sichuan China 《《地质学报》英文版》2009,83(2)
Three special types of xenoliths have recently been found in an aegirine-augite syenite porphyry in Liuhe,Yunnan,China.Petrographical,petrochemical,electron microprobe,and scanning electron microscopy studies indicate that pure calcite xenocrysts and quartz-bearing topaz pegmatite xenoliths result from the degassing of mantle fluids during their migration,and that black microcrystalline iron-rich silicate-melt xenoliths are the product of the extraction of mantle fluids accompanying degassing and are com... 相似文献