In order to study the major ion chemistry and controls of groundwater, 65 groundwater samples were collected and their major ions measured from wells within Lhasa River Basin. Groundwater has the characteristics of slightly alkaline and moderate total dissolved solid (TDS). TDS concentration ranged from 122.0 to 489.9 mg/L with a median value of 271.2 mg/L. Almost all the groundwater samples suited for drinking and irrigation. The major cations of groundwater are Ca2+ and Mg2+, accounting for 59.6 and 31.3% of the cations, respectively. Meanwhile, HCO3? and SO42? constituted about 56.7 and 36.9% of the anions, respectively, in Lhasa River Basin. The hydrochemical type of groundwater is HCO3-SO4-Ca-Mg. The chemical composition of groundwater samples located in the middle of Gibbs model, which indicates that the major chemical process of groundwater is controlled by rock weathering. Carbonate weathering was the dominant hydro-geochemical process controlling the concentration of major ions in groundwater within Lhasa River Basin, but silicate weathering also plays an important role. 相似文献
The completion and operation of the Three Gorges Reservoir in China have increased the frequency of geo-hazards and dangers in the area. To monitor and to warn of geo-hazards effectively, the Chinese government has invested billions of funds for constructing a monitoring and warning engineering system. Similar to other social infrastructure investments, a reasonable assessment of investment returns is necessary. Therefore, this study proposes an economic benefit assessment model, which considers both the expected and the actual values. The economic benefit of the geo-hazard monitoring and warning engineering in the Three Gorges Reservoir areas is evaluated. Based on the engineering characteristics, the model reasonably defines the frontier of the input and output and adds the casualties and the losses of ecological environment into the economic benefit evaluation index system. A case study on the Zhangjiawan landslide in Guojiaba Town, Zigui County, was conducted. The evaluation results show that (1) land has the largest benefit in direct reductional loss (total of 56.7 %), while the largest indirect reductional losses of the hazard-bearing bodies are in agricultural production and ecological environment (total of 97.6 %); (2) the costs-to-expected return ratio of landslide monitoring and warning engineering is 1:280, whereas the cost-to-actual benefit ratio is 1:30; (3) the accumulation of relevant information and the public knowledge of geological disasters should be strengthened.
The Huanghebei Coalfield, one of the coal production bases in North China, was considered as a coalfield without coal‐bed methane (CBM) during past decades. In recent years, however, CBM has been discovered in coal‐bearing successions. In order to understand the CBM geological characteristics and accumulation process in this area, fifteen coal samples were collected and analyzed with respect to coal maceral and reflectance. The result shows that the gas distribution is uneven and the content varies in different areas even for the same coal bed. The storage of CBM is affected by geological factors such as burial depth, geological structures, and magmatic intrusion, among which the former two are more important in the formation of CBM. Deep burial of coal beds with the presence of cap‐rock mudstone can seal CBM. The CBM is also accumulated and preserved at the place where normal faults are distributed. Magmatic intrusion causes contact metamorphism and controls the CBM formation by heating the coal‐bearing successions. The obtained data indicate the geological conditions in northeastern Zhaoguan Mine are preferable for CBM formation and conservation; recent exploration estimates the CBM geological reserves up to 282.16 Mm3 and average of reserve abundance at 0.1662 × 108 m3 km?2. The Changqing Mine is a potential prospect in terms of CBM exploration since its geological conditions (structures and burial depth) are similar to the Zhaoguan Mine and its cap rock is even better. 相似文献
Landslides - Talus slopes play an important role in landscape evolution in some mid-altitude mountains. In this study, we analyzed talus slope activity on Xiaowutai Mountain in the Northern Taihang... 相似文献
Biodegradation is one of the main natural attenuation processes in groundwater contaminated with petroleum hydrocarbons. In this work, preliminary studies have been carried out by analyzing the concentrations of total petroleum hydrocarbons (TPH), dissolved inorganic carbon (DIC), dominant terminal electron accepters or donors, as well as δ13CDIC and δ34SSO4, to reveal the biodegradation mechanism of petroleum hydrocarbons in a contaminated site. The results show that along groundwater flow in the central line of the plume, the concentrations of electron acceptors, pH, and Eh increased but TPH and DIC decreased. The δ13CDIC values of the contaminated groundwater were in the range of ?14.02 to ?22.28 ‰PDB and ?7.71 to 8.36 ‰PDB, which reflected a significant depletion and enrichment of 13C, respectively. The increase of DIC is believed to result from the non-methanogenic and methanogenic biodegradation of petroleum hydrocarbon in groundwater. Meanwhile, from the contaminated source to the downgradient of the plume, the 34S in the contaminated groundwater became more depleted. The Rayleigh model calculation confirmed the occurrence of bacterial sulfate reduction as a biodegradation pathway of the petroleum hydrocarbon in the contaminated aquifers. It was concluded that stable isotope measurements, combined with other biogeochemical measurements, can be a useful tool to prove the occurrence of the biodegradation process and to identify the dominant terminal electron-accepting process in contaminated aquifers. 相似文献
Effective soil thermal conductivity (λeff) describes the ability of a multiphase soil to transmit heat by conduction under unit temperature gradient. It is a critical parameter for environmental science, earth and planetary science, and engineering applications. Numerous models are available in the literature, but their applicability is generally restricted to certain soil types or water contents (θ). The objective of this study was to develop a new model in the similar form of the Johansen 1975 model to simulate the λeff(θ) relationship of soils of various soil textures and water contents. An exponential type model with two parameters is developed and a new function for calculating dry soil thermal conductivity is presented. Performance of the new model and six other normalized models were evaluated with published datasets. The results show that the new model is able to well mimic λeff(θ) relationship of soils from sand to silt loam and from oven dry to full saturation. In addition, it has the best performance among the seven models under test (with root-mean-square error of 0.059 W m?1 °C?1, average deviations of 0.0009 W m?1 °C?1, and Nash–Sutcliffe efficiency of 0.994). The new model has potential to improve the reliability of soil thermal conductivity estimation and be incorporated into numerical modeling for environmental, earth and engineering studies. 相似文献
<正>1 Introduction Rare-metal granites are widely distributed in South China.The Daping porphyritic granitic Ta-Nb deposit,located in the Yongding area of south Fujian province,South China,is a large rare-metal deposit recently discovered.Few studies have been made of its petrology,mineralogy,geochemistry,chronology and metallogeny.In recent years,several exploratory drillings have been done in this deposit.These drilling holes,from 380 to 600 相似文献
To restore China’s degraded ecological environment, the government has launched an environmental restoration project named
the “Grain for Green Project” (GGP) in 1999. From 1999 to 2010, the government will spend 40 billion dollars to convert 147
million ha of croplands and 173 million ha of wastelands into forestlands and grasslands in 25 provinces, municipalities and
autonomous regions. A primary goal is to replace cropping and livestock grazing in fragile areas with trees and grass. Given
the tremendous scale and great number of participants in the project, the attitudes of the affected farmers and the future
development in the area where GGP is implemented have a direct influence on the success of the project. To gain a clear idea
about the farmers’ attitudes towards the project and put forward the development models for the forestlands converted from
croplands, two case sites in the mountain-gorge region in Nujiang River are selected as the study areas, and the methods of
field survey and semi-structured interview are adopted to make interviews with more than 100 households in 2002 and 2003 in
order to quantify the farmers’ opinions about the GGP and how it has affected their livelihood, socio-cultural and industrial
structures, etc. The results are as follows: 1) the project has a certain influence on the farmers with better economic basis
and exerts greater influence on the farmers living in the low-elevation regions than on those living in the regions with middle-high
elevation; 2) the production models of the local farmers has changed from cultivation and animal husbandry to forestry and
sidelines due to the project and the income structure has changed from animal husbandry as main income source to state subsidy
and sideline as main income sources; 3) the reduction in the grain income and decrease in the quantity of livestock because
of the project have led to the diminution in the total income of the farmers; 4) the project has resulted in changes in the
lifestyles and architecture styles of the local farmers, and the traditional “huotang” culture has gone away after the implementation
of the project; 5) energy utilization has changed from firewood to methane and electricity in the wake of the implementation
of the project. The above-mentioned study results have indicated that the GGP has truly exerted influence on the livelihood
and production of the local farmers. Therefore, it is very necessary to make a research into the development models in the
forestlands converted from croplands to resolve the problems of the farmers’ livelihood and production. The study results
will provide some references for the sustainable development of the mountain-gorge regions. 相似文献