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641.
642.
基于遥感(RS)和地理信息系统(GIS)技术,对兴化市的生态环境状况作分析。以2005年和2012年的影像图为数据源,经过图像预处理,通过解译与分类,得到该市2个时期土地利用状况的变化情况。在此基础上,对2个时期的土地利用类型作对比,结果表明,耕地面积减少明显,城镇、农村居民点和其他建设用地面积增加突出。分别计算2个时期的生物丰度指数和植被覆盖指数,并分析了影响生态环境的主要因素。 相似文献
643.
于2010年6月—10月每月对青木关地下河水进行监测,利用15N同位素技术并结合水化学指标,分析地下河的水化学特征以及硝态氮来源的时空变化特征。结果表明,地下河出口丁家龙洞硝态氮质量浓度(5.08 mg/L)比入口天池2号点(0.842 mg/L)高6倍多。天池2号点处δ15N为-0.705%~+0.706%,主要受到人造化肥和天然土壤矿化的有机氮的影响,总体变化幅度不大,地下水受外界影响较小。出口丁家龙洞处的δ15N为-2.15%~+3.78%,平均值为+1.01%,总体值高,且变化幅度大。 相似文献
644.
Terry Sohl Ryan Reker Michelle Bouchard Kristi Sayler Jordan Dornbierer Steve Wika 《Journal of Land Use Science》2016,11(4):476-499
The landscape of the conterminous United States has changed dramatically over the last 200 years, with agricultural land use, urban expansion, forestry, and other anthropogenic activities altering land cover across vast swaths of the country. While land use and land cover (LULC) models have been developed to model potential future LULC change, few efforts have focused on recreating historical landscapes. Researchers at the US Geological Survey have used a wide range of historical data sources and a spatially explicit modeling framework to model spatially explicit historical LULC change in the conterminous United States from 1992 back to 1938. Annual LULC maps were produced at 250-m resolution, with 14 LULC classes. Assessment of model results showed good agreement with trends and spatial patterns in historical data sources such as the Census of Agriculture and historical housing density data, although comparison with historical data is complicated by definitional and methodological differences. The completion of this dataset allows researchers to assess historical LULC impacts on a range of ecological processes. 相似文献
645.
上海市城市化进程中热环境响应的空间评价 总被引:1,自引:0,他引:1
利用Landsat TM/ETM+ 遥感数据解译与反演得到上海市1997~2009年的土地利用/覆盖类型图及热岛强度分布图,并分析其演变趋势,引入温度-植被指数(TVX)并采用TVX空间法定量研究了以建设用地扩张、生态用地减少为特点的城市化过程引起的热环境效应.研究表明,1997~2009年,上海市人口呈现从中心城至郊区的流动趋势;热岛强度分布与城市化建设密切相关,呈现“葫芦串-葡萄串-摊大饼型”的蔓延模式;以牺牲生态用地为代价的建设用地扩张造成研究区域地表温度的上升及植被覆盖度的下降,其中林地减少所引起的热环境效应最大.研究可为城市规划决策过程中不同城市化空间的拓展情景提供其可能的环境响应结果,从而完善气候变化适应性对策,推进城市生态系统的可持续发展. 相似文献
646.
堆浸铀尾矿用作地下充填法采场的充填料是处理铀尾矿的一种方法。将铀尾矿作为充填料时,其内残留的镭衰变产生的氡气会从其表面析出,污染井下作业环境。基于氡在介质中纯扩散的理论,研究了在尾矿介质孔隙率为0.3、铀尾矿中镭活度浓度为3 400 Bq/kg、干燥时铀尾矿的射气系数为0.1、铀尾矿的密度为2.5×103kg/m3的条件下,含水饱和度、孔隙率、覆盖层厚度等物理参数对铀尾矿充填体氡析出的影响规律。结果表明:无覆盖层时,含水饱和度在0~0.25的范围内,随含水饱和度增加,铀尾矿介质表面氡析出率先增加后减小,含水饱和度从0增加到0.12时,铀尾矿介质表面氡析出率从5 Bq/(m2·s)增加到11 Bq/(m2·s),含水饱和度从0.12增加到0.25时,铀尾矿介质表面氡析出率从11 Bq/(m2·s)减小到10.5 Bq/(m2·s);有覆盖层时,铀尾矿介质厚度为3 m,添加孔隙率为0.05的覆盖层,当覆盖层厚度从0增加到0.1 m时,介质表面氡析出率减小67.5%,当覆盖层厚度增加到0.5 m时,介质表面氡析出率减小91.8%。 相似文献
647.
648.
简要介绍了HZ型防尘密闭罩的研究设计和工程应用情况。实际应用结果表明:HZ型防尘密闭罩能有效地密闭尘源,又不妨碍工人操作和维护检修,并可使排风量平均降低约40%,是一项值得推广的实用技术。 相似文献
649.
Spatial Distribution and Temporal Change of Carbon Storage in Timber Biomass of Two Different Forest Management Units 总被引:2,自引:0,他引:2
Forests make up large ecosystems and can play an important role in mitigating the emissions of CO2, the most important greenhouse gas. However, they are sources of atmospheric carbon when they are disturbed by human or natural
causes. Storage of carbon through expansion and adaptive management of forest ecosystems can assist in reducing carbon concentrations
in atmosphere. This study proposes a methodology to produce spatially explicit estimates of the carbon storages (aboveground
plus belowground) depending on land use/cover changes in two different forest ecosystems during various periods. Carbon storages
for each forest ecosystem were projected according to inventory data, and carbon storages were mapped in a geographic information
system (GIS). Results showed that total carbon stored in above and belowground of both forest ecosystems increased from one
period to other because of especially increase of productive forest areas and decline of degraded forest areas as well as
protection of spruce forests subject to insect attacks. 相似文献
650.
Hydro-chemical Survey of Groundwater of Hisar City and Assessment of Defluoridation Methods Used in India 总被引:1,自引:0,他引:1
Ground water quality of Hisar city was assessed for its suitability for drinking purposes. Samples collected from the Bore-wells
(forms a part of municipal water supply) and handpumps (direct consumption) were analyzed for the various physico-chemical
parameters including pH, electrical conductivity, total dissolved salts, total hardness, total alkalinity, sodium, potassium,
calcium, magnesium, carbonate, bicarbonate, chloride and sulfate. The concentrations of magnesium, sodium, potassium, sulfate
and especially of chloride were found moderately higher than the WHO standards for the drinking water. Further a comparison
of fluoride (F−) levels in groundwater of various cities and towns of Haryana state was performed. The relatively higher concentrations of
F− in groundwater of Haryana raise the risk of fluorosis and hence groundwater must be used with proper treatment. Promising
defluoridation methods using locally available materials and technologies are discussed for the prevention and control of
fluorosis. Data were assessed statistically to find the suitable markers of ground water quality as an aid to monitoring groundwater
quality. 相似文献