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411.
The groundwater table has been declining at a rate of 0.65 m/yr in Luancheng County since large scale groundwater extraction
carried out in the 1960s. The drop of precipitation, substantial increase in agricultural output, variations of crop planting
structure and construction of water conservancy projects in the headwater area all tie up with the decline of the groundwater
table. On the basis of analyzing the hydrogeological conditions and the water resources utilization of Luancheng County, a
three-dimensional groundwater flow model was developed to simulate the county’s groundwater flow through finite-difference
method using Visual Modflow software. We divide the research field into four parts after analyzing the hydrogeological condition.
Based on parameter calibration and adjustment using measured data, the hydraulic conductivity and specific yield were simulated.
Using the calibrated model, we analyze the agricultural water saving potentiality and its influence on the groundwater. The
results are as follows: (1) if we decrease the amount of water extracted by 0.14xl08 m3, the average groundwater table of the five observation wells in December will rise by 0.33 m; (2) if we decrease the water
by 0.29x 108m3, the average groundwater table of the five observation wells in December will rise by 0.64 m; and (3) if we increase the
water by 0.29 x 108m3, the average groundwater table of the five observation wells in December will decline by 0.45 m. So we can draw a conclusion
that controlling the agricultural water use is an important way to prevent the decline of groundwater table. 相似文献
412.
Soil sediment samples of 10 layers with a spacing of 10 cm each were collected in different floodplain zones adjacent to Huolin
River in the Xianghai Nature Reserve, and contents of total N, total P and organic matters were analyzed. The results showed
that contents of total N, total P and organic matters were generally decreasing with the increase of distance from sample
locations to the river channel, and contents of the three items were generally higher in the upper soil layer than that in
the lower soil layer. The content variations displayed how flooding functions influenced nutrient matter content variations
in floodplain soils since the flood inundation frequencies of the sample locations varied. The correlation analysis displayed
that there were remarkable relativities between total N, total P and organic matters within definite spatial distance from
the Huolin River channel. 相似文献
413.
Simon J. van Donk Xuewen Huang Edward L. Skidmore Alan B. Anderson Dick L. Gebhart Valerie E. Prehoda Elizabeth M. Kellogg 《Journal of Arid Environments》2003,54(4):687-703
Military training activities reduce vegetation cover, disturb crusts, and degrade soil aggregates, making the land more vulnerable to wind erosion. The objective of this study was to quantify wind erosion rates for typical conditions at the Marine Corps Air Ground Combat Center, Twentynine Palms, CA, U.S.A. Five Big Spring Number Eight (BSNE) sampler stations were installed at each of five sites. Each BSNE station consisted of five BSNE samplers with the lowest sampler at 0·05 m and the highest sampler at 1·0 m above the soil surface. Once a month, sediment was collected from the samplers for analysis. Occurrence of saltating soil aggregates was recorded every hour using Sensits, one at each site. The site with the most erosion had a sediment discharge of 311 kg m−1 over a period of 17 months. Other sites eroded much less because of significant rock cover or the presence of a crust. Hourly sediment discharge was estimated combining hourly Sensit count and monthly sediment discharge measured using BSNE samplers. More simultaneously measured data are needed to better characterize the relationship between these two and reconstruct a detailed time-series of wind erosion. This measured time-series can then be used for comparison with simulation results from process-based wind erosion models such as the Wind Erosion Prediction System (WEPS), once it has been adapted to the unique aspects of military lands. 相似文献
414.
通过对建宁黄埠地区金矿地质特征、矿化特点、成矿地质规律的研究,认为该区成矿年龄为91Ma,提出了北西西向碎裂带为主要的含矿构造,并指出该区具有较好的找金远景。 相似文献
415.
416.
阐述了新疆煤炭工业发展中存在的主要问题,分析了新疆煤田地质工作的发展方向及当前工作重点,并对新疆煤炭工业的可持续发展战略提出了政策性建议。 相似文献
417.
Multi-parameter studies (stable isotopes in carbonate and organic matter, pigment,organic carbon and nitrogen contents) from a 660-yr continuous sediment core from Lake Cheng-hai, a closed, eutropic lake in southern China, provide information on lake historical eutrophi-cation. During the last 660 years, great changes have taken place in productivity and eutrophi-cation of Lake Chenghai in response to human activities. In 1690, the productivity of the lakebegan to increase as Lake Chenghai became closed from agriculture in the lake‘‘ s watershed. In 1942, Lake Chenghai evolved to eutrophic state, marked by an increase in organic carbon, ni-trogen, CaC03, pigment contents and obvious negative values of stable isotopes, which is more or less simultaneous with the large-scale population immigration during the period. In 1984, in-tensive human activities induced modern lacustrine productivity and eutrophic level. Human-in-duced trophic changes during the past few decades have affected the Lake Chenghai ecosystem tosuch an extent that it has never experienced before in the last 660 years. 相似文献
418.
The bulk composition of organic matter and saturated and aromatic hydrocarbons extracted from 16 samples collected from two Kuperschiefer profiles in the Rudna mine,Southwest Poland has been analyzed to study the role of organic matter during base metal enrichment in the Kupferschiefer shale.The results indicated that the extract yields and saturated hydrocarbon yields decreased with increasing base metal contents.GC and GC/MS analyses indicated that n -alkanes and alkylated aromatic compounds were depleted and may have served as hydrogen donators for thermochemical sulfate reduction.The enrichment of base metal is closely connected with the destruction of hydrocarbons. 相似文献
419.
From the studies of ore deposit geologic settings,sulfur isotopes,lead isotopes,carbon isotopes and oxygen isotopes,fluid inclusions and petrochemistry in this paper,the authors have drawn a conclusion that the ore-forming hydrothermal solutions are the high-temperature magmatic hydrothermal solutions for the gold ore deposit,and at the same time,the involvemety of crustal materials can not be ruled out .It is the first time that the authors have proposed that the Laozuoshan gold-ploymetallic ore deposit in Heilongjiang Province was formed in the calc-alkaline series environment at the margin of an active continent. 相似文献
420.
1IntroductionTheHongshijinggolddepositislocatedinthenorthofLuobupouLakeofRuoqiang ,about 30 0kmsouthwestofHamiCity ,Xinjiang .ItwasdiscoveredbytheSixthGeologicalTeamofXinjiangduringgeo chemicalexploration .TheHongshijinggolddeposit,whichoccursinthegold bearingformationcomposedofMiddleandLateCarboniferousvolcanicandpyroclasticrocks ,isabrittle ductileshearzonetypegolddepositcontrolledbyariftbelt.TheHongshijinggolddepositislocatedinthesouthwestoftheHongshi jing -Maotoushanmineralizationb… 相似文献