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131.
松科1井南孔选址、岩心剖面特征与特殊岩性层的分布 总被引:6,自引:0,他引:6
松科1井南孔是松辽盆地白垩系科学钻探工程两个钻孔中的一个,位于松辽盆地北部中央坳陷区齐家古龙凹陷敖南鼻状构造的翼部。通过对松科1井南孔嫩二段底部到泉三段顶部连续取心资料的详细描述,建立松科1井南孔岩心剖面,识别出5种常见岩性(泥岩、粉砂质泥岩、泥质粉砂岩、粉砂岩和细砂岩)和8种特殊岩性(白云岩、火山灰、油页岩、灰质泥岩、泥灰岩、重结晶灰岩、介形虫碎屑灰岩和介形虫灰岩)。特殊岩性出现的总层数为172层,总厚度为14.516m,分布在青一段,青二、三段,姚二、三段,嫩一段和嫩二段地层中。对松科1井的精细岩心描述和对特殊岩性的识别是后续研究工作开展的基础。 相似文献
132.
Impact of land use covers upon karst processes in a typical Fengcong depression system of Nongla, Guangxi, China 总被引:2,自引:0,他引:2
Cheng Zhang Jianguo Pei Yunqiu Xie Jianhua Cao Lanling Wang 《Environmental Geology》2008,55(8):1621-1626
The direction and intensity of karst processes can be deeply affected by soil physical and chemical variations which were
resulted from land use. Taking Nongla Fengcong depression area, Mashan County, Guangxi as an example, authors discussed the
impact of land use on karst processes based on the data of field limestone tablet. The results showed that the corrosional
rates at varied soil depth are quite different. Corrosional rate in woodland and orchard is mostly bigger than 20 mg/a, which
is much higher than that in tilled land and shrub. Generally, corrosional rate decreased from orchard, woodland, tilled land,
fallow land and shrub successively, in which soil organic matter (OM) and soil pH are two major controlling factors: corrosion
process is controlled remarkably by soil OM in woodland and orchard. The higher the organic matter content is and the less
the pH value is, the higher the corrosional rate is. Owing to lower organic matter content, the corrosional rate is mainly
affected by soil CO2 in tilled land and shrub. 相似文献
133.
Xiaoan Zuo Halin Zhao Xueyong Zhao Yirui Guo Yulin Li Yayong Luo 《Environmental Geology》2008,54(5):1111-1120
A survey was conducted in an 11-year recovery mobile dune (RMD11) and a 20-year recovery mobile dune (RMD20), in Horqin Sandy
Land, Northern China, to determine plant distribution at the mobile dune scale and its relevance to soil properties and topographic
features. The results showed that (1) vegetation cover and species number increased from dune top to bottom in the restoration
process of mobile dune; (2) the average value of soil organic C, total N, pH, relative height of sampling site, very fine
sand content and soil water contents (40−60 and 60−80 cm) of RMD11 were less than that of RMD20, respectively, and there were
significant differences (P < 0.05) between the two dunes; (3) soil resources were redistributed by shrub restoration and relative height of sampling
site on dune. The distribution of sand pioneer plant, Agriophyllum squarrosum, was positively related to the relative height of sampling site and soil water content, while that of other herbaceous plants
was positively related to soil nutrients in the restoration process of mobile dune. These results suggest that at mobile dune
scale, plant distributions are determined by a combination of soil properties and topographic feature. Much effort should
be made to preserve the interdune lowland and to improve the level of soil nutrients on mobile dune. 相似文献
134.
Zhou Haiyan Zhou Xun Chai Rui Yu Lan Liu Chunhui Li Liangping 《Environmental Geology》2008,53(7):1483-1489
Thermal groundwater occurs in bedrock aquifers consisting of the dolomite of the Wumishan Group of the Jixianin System and
the Cambrian carbonate in the Xiaotangshan geothermal field near the northern margin of the North China Plain, China. The
hot water in the geothermal field of basin-type discharges partly in the form of the Xiaotangshan hot spring under natural
conditions. The hot water has TDS of less than 600 mg/L and is of Na·Ca-HCO3 type. The geothermal water receives recharge from precipitation in the mountain area with elevation of about 500 m above
sea level to the north of the spring. Thermal groundwater flows slowly south and southeast through a deep circulation with
a residence time of 224 years estimated with the Ra–Rn method. The Xiaotangshan hot spring dried up in the middle of the 1980s
owing to the increasing withdrawal of the hot water in the geothermal field in the past decades. The water level of the geothermal
system still falls continually at an annual average rate of about 2 m, although water temperature changes very little, indicating
that the recharge of such a geothermal system of basin-type is limited. Over-exploitation has a dramatic impact on the geothermal
system, and reduction in exploitation and reinjection are required for the sustainable usage of the hot water. 相似文献
135.
Response of groundwater chemistry to water deliveries in the lower reaches of Tarim River,Northwest China 总被引:2,自引:0,他引:2
Yongjin Chen Kefa Zhou Yaning Chen Weihong Li Jiazhen Liu Tao Wang 《Environmental Geology》2008,53(6):1365-1373
In this paper, we analysed the monitored data from nine groundwater-monitoring transects in the lower reaches of Tarim River
during the five times of stream water deliveries to the river transect where the stream flow ceased. The results showed that
the groundwater depth in the lower reaches of Tarim River rose from −9.30 m before the conveyances to −8.17 and −6.50 m after
the first and second conveyances, −5.81 and −6.00 m after the third and fourth the conveyance, and −4.73 m after the fifth.
The horizontal extent of groundwater recharge was gradually enlarged along both sides of the channel of conveyance, i.e.,
from 250 m in width after the first conveyance to 1,050 m away from the channel after the fourth delivery. With the rising
groundwater level, the concentrations of major anions Cl−, SO42− and cations Ca2+, Mg2+, Na+, as well as total dissolved solids (TDS) in groundwater underwent a significant change. The spatial variations in groundwater
chemistry indicated that the groundwater chemistry at the transect near Daxihaizi Reservoir changed earlier than that farther
from it. In the same transect, the chemical variations were earlier in the monitoring well close to watercourse than that
farther away from the stream. In general, the concentration of the major ions and TDS at each monitoring well increased remarkably
when the water delivery started, and decreased with the continued water delivery, and then increased once again at the end
of the study period. Hence, the whole study period may be divided into three stages: the initial stage, the intermediate stage
and the later stage. According to the three stages of groundwater chemistry reaction to water delivery and the relationships
between groundwater chemical properties and groundwater depths, we educe that under the situation of water delivery, the optimum
groundwater depth in the lower reaches of the Tarim River should be −5 m. 相似文献
136.
Distribution of Cd,Pb, Zn and Cu and their chemical speciations in soils from a peri-smelter area in northeast China 总被引:2,自引:0,他引:2
An exploratory study on soil contamination of heavy metals was carried out surrounding Huludao zinc smelter in Liaoning province,
China. The distribution of total heavy metals and their chemical speciations were investigated. The correlations between heavy
metal speciations and soil pH values in corresponding sites were also analyzed. In general, Cd, Zn, Pb, Cu and As presented
a significant contamination in the area near the smelter, comparied with Environmental Quality Standards for Soils in China.
The geoaccumulation index showed the degree of contamination: Cd > Zn > Pb > Cu > As. There was no obvious pollution of Cr
and Ni in the studied area. The speciation analysis showed that the dominant fraction of Cd and Zn was the acid soluble fraction,
and the second was the residual fraction. Pb was mostly associated with the residual fraction, which constituted more than
50% of total concentration in all samples. Cu in residual fraction accounted for a high percentage (40–80%) of total concentration,
and the proportion of Cu in the oxidizable fraction is higher than that of other metals. The distribution pattern of Pb and
Zn was obviously affected by soil pH. It seemed that Pb and Zn content in acid solution fraction increased with increasing
soil pH values, while Cd content in acid soluble fraction accounted for more proportion in neutral and alkaline groups than
acidic one. The fraction distribution patterns of Cu in three pH groups were very similar and independent of soil pH values.
And the residual fraction of Cu took a predominant part (50%) of the total content. 相似文献
137.
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
138.
Concentrations of trace elements and heavy metals (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Se, Sr, V and Zn) in
the Danjiangkou Reservoir, the water source area of the Middle Route of China’s interbasin South to North Water Transfer Project,
were analyzed using an Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) and compared with the national and
international standards for drinking water. The results indicated that concentrations of As, Pb, Sb and Se in the Reservoir
exceeded the standards and they would pose health risk for residents in the region and the water receiving areas of the interbasin
water transfer project. Spatial and temporal variability of the trace elements and heavy metals in the Reservoir implies their
mixed sources of natural processing and anthropogenic activities in the upper drainage of the Reservoir. The research results
would help develop water resource management and conservation strategy for the interbasin water transfer project. 相似文献
139.
Unconsolidated sand, gravel and clay deposits near Beihai and in the Leizhou Peninsula in southern China form an unconfined
aquifer, aquitard and a confined aquifer. Water and soil samples were collected from the two aquifers in the coastal Beihai
area for the determination of chemical compositions, minerals and soluble ions. Hydrogeochemical modeling of three flow paths
through the aquitard are carried out using PHREEQC to determine water–rock interactions along the flow paths. The results
indicate that the dissolution of anorthite, fluorite, halite, rhodochrosite and CO2, and precipitation of potash feldspar and kaolinite may be occurring when groundwater leaks through the aquitard from the
unconfined aquifer to the confined aquifer. Cation exchanges between Na and Ca can also happen along the flow paths. 相似文献
140.
Qiang Wang Derek A. Wyman Jifeng Xu Yusheng Wan Chaofeng Li Feng Zi Ziqi Jiang Huaning Qiu Zhuyin Chu Zhenhua Zhao Yanhui Dong 《Contributions to Mineralogy and Petrology》2008,155(4):473-490
New chronological, geochemical, and isotopic data are reported for Triassic (219–236 Ma) adakite-magnesian andesite-Nb-enriched
basaltic rock associations from the Tuotuohe area, central Qiangtang terrane. The adakites and magnesian andesites are characterized
by high Sr/Y (25–45), La/Yb (14–42) and Na2O/K2O (12–49) ratios, high Al2O3 (15.34–18.28 wt%) and moderate to high Sr concentrations (220–498 ppm) and εND (t) (+0.86 to +1.21) values. Low enrichments of Th, Rb relative to Nb, and subequal normalized Nb and La contents, and enrichments
of light rare earth elements combine to distinguish a group of Nb-enriched basaltic rocks (NEBs). They have positive εND (t) (+2.57 to +5.16) values. Positive correlations between Th, La and Nb and an absence of negative Nb anomalies on mantle
normalized plots indicate the NEBs are products of a mantle source metasomatized by a slab melt rather than by hydrous fluids.
A continuous compositional variation between adakites and magnesian andesites confirms slab melt interaction with mantle peridotite.
The spatial association of the NEBs with adakites and magnesian andesites define an “adakitic metasomatic volcanic series”
recognized in many demonstrably subduction-related environments (e.g., Mindanao arc, Philippines; Kamchatka arc, Russia; and
southern Baja California arc, Mexico). The age of the Touhuohe suite, and its correlation with Triassic NEB to the north indicates
that volcanism derived from subduction-modified mantle was abundant prior to 220 Ma in the central Qiangtang terrane. 相似文献