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981.
Patterns of Spatial Autocorrelation in Stream Water Chemistry 总被引:2,自引:0,他引:2
Peterson EE Merton AA Theobald DM Urquhart NS 《Environmental monitoring and assessment》2006,121(1-3):569-594
Geostatistical models are typically based on symmetric straight-line distance, which fails to represent the spatial configuration, connectivity, directionality, and relative position of sites in a stream network. Freshwater ecologists have explored spatial patterns in stream networks using hydrologic distance measures and new geostatistical methodologies have recently been developed that enable directional hydrologic distance measures to be considered. The purpose of this study was to quantify patterns of spatial correlation in stream water chemistry using three distance measures: straight-line distance, symmetric hydrologic distance, and weighted asymmetric hydrologic distance. We used a dataset collected in Maryland, USA to develop both general linear models and geostatistical models (based on the three distance measures) for acid neutralizing capacity, conductivity, pH, nitrate, sulfate, temperature, dissolved oxygen, and dissolved organic carbon. The spatial AICC methodology allowed us to fit the autocorrelation and covariate parameters simultaneously and to select the model with the most support in the data. We used the universal kriging algorithm to generate geostatistical model predictions. We found that spatial correlation exists in stream chemistry data at a relatively coarse scale and that geostatistical models consistently improved the accuracy of model predictions. More than one distance measure performed well for most chemical response variables, but straight-line distance appears to be the most suitable distance measure for regional geostatistical modeling. It may be necessary to develop new survey designs that more fully capture spatial correlation at a variety of scales to improve the use of weighted asymmetric hydrologic distance measures in regional geostatistical models. 相似文献
982.
生物膜法A/O系统处理腈纶废水工业试验 总被引:5,自引:0,他引:5
本工业试验规模为1400—1600t/d,装置A/O容积比1:3,当平均停留时间22.6h,回流比3.2,水温约35℃左右时,平均去除率CODcr达88.36%、BOD597.49%、TN77.67%、AN99.41%。出水各项指标平均值为CODCr53.57mg/L、BOD55.6mg/L、TN14.94mg/L、NH3-N6.92mg/L、AN1.02mg/L、NaSCN2.67mg/L,SS仅20mg/L,因此不设二沉池。 相似文献
983.
Takayoshi Yamaguchi Sonam Ngodup Mitsuhiro Nose Shinya Takeda 《Journal of Land Use Science》2016,11(4):401-416
Farmland abandonment has been a significant issue in mountain regions. Thus, many studies have attempted to uncover its driving factors. Most existing studies take a large- or meso-scale view of mountain regions, and there are a few studies that provide community-level analysis. Therefore, it is unclear how ecological and sociopolitical factors are actually combined to influence farmland abandonment at a community level. Thus, we conducted a field survey in the mountain village of Ladakh, northern India, beginning in 2009 and tried to understand the farmland abandonment occurrence process from the viewpoint of traditional altitudinal models of land use. Using data collected during the survey, a relationship between altitude and farmland abandonment was established. However, this relationship was complex, combining traditional forms of land use system in the village. The altitudinal model of land use was very common in mountain regions; thus, discussions of current land use issues should be based on an understanding of such traditional altitudinal systems. 相似文献
984.
Mariella Tataranni Claudio Lardicci 《Environmental pollution (Barking, Essex : 1987)》2010,158(1):26-34
The aim of this study was to analyse the variability of four different benthic biotic indices (AMBI, BENTIX, H′, M-AMBI) in two marine coastal areas of the North-Western Mediterranean Sea. In each coastal area, 36 replicates were randomly selected according to a hierarchical sampling design, which allowed estimating the variance components of the indices associated with four different spatial scales (ranging from metres to kilometres). All the analyses were performed at two different sampling periods in order to evaluate if the observed trends were consistent over the time. The variance components of the four indices revealed complex trends and different patterns in the two sampling periods. These results highlighted that independently from the employed index, a rigorous and appropriate sampling design taking into account different scales should always be used in order to avoid erroneous classifications and to develop effective monitoring programs. 相似文献
985.
工业化规模生物堆修复焦化类PAHs污染土壤的效果 总被引:3,自引:0,他引:3
现场建立处理能力为450 m3工业化规模的生物堆对焦化类PAHs污染土壤进行为期8个月的修复,运行过程中控制土壤C∶N∶P=100∶10∶1、水分10%~20%(质量百分比)、堆内氧气不低于7%(体积百分比)。结果表明:O2与CO2浓度呈负相关。系统连续运行时,微生物数量增加至107数量级,高出自然状态下土壤中微生物数量1~2个数量级。除NO3-在运行后期显著增加外,其余土壤因子均无明显变化。PAHs的降解主要出现在前6个月,之后进入"拖尾"阶段,土壤中各PAH浓度基本不再降低。运行结束后,堆体0.5 m处土壤中含2、3、4、5和6个苯环PAHs的降解率分别介于56.3%~99.5%、34.8%~71.6%、30.7%~40.6%、28.6%~39.2%和39.3%,16种PAHs的平均去除率为65.1%。1.5 m处土壤中含2、3、4、5和6个苯环PAHs的降解率分别介于50.9%~99.8%、57.7%~60.9%、55.9%~63.0%、27.3%~57.1%和52.2%,16种PAHs的平均去除率为71.4%。 相似文献
986.
气候变化加剧了极端天气和水文事件的发生,降水是区域干旱与洪水事件最直接驱动因素。以TRMM/PR月累积降水反演遥感数据为基础,利用经验正交函数EOF(Empirical Orthogonal Function)方法对长江流域降水时空变化模式进行提取,并对比分析了主要模式振幅强弱与极端水文事件的对应关系。结果表明在流域尺度上EOF方法及TRMM/PR数据可以较好地识别降水主要模式,通过时空尺度变换成功揭示主要降水模式强弱与流域极端水文事件的对应关系。鉴于日益丰富的巨量水文气象时空数据,EOF方法在模式提取、水文模拟、极端事件预估及灾害适应性研究等方面具有应用潜力 相似文献
987.
Sangiorgi G Ferrero L Perrone MG Bolzacchini E Duane M Larsen BR 《Environmental pollution (Barking, Essex : 1987)》2011,159(12):3545-3552
A novel approach for measuring vertical profiles of HCs and particle number concentrations was described and applied in the low troposphere over Milan (Italy) during typical spring and summer days. Particle profiles yielded nearly homogeneous concentrations below the mixing height, with level-to-ground concentration ratios of 92-97%, while HCs showed a more pronounced decrease (74-95%). Vertical mixing and photochemical loss of HCs were demonstrated to cause these gradients. Much lower concentrations were observed for the profiles above the mixing height, where the HC mixtures showed also a different composition, which was partially explained by the horizontal advection of air with HC sources different to those prevailing at the site. The application of pseudo-first order kinetics for reactions between HCs and the hydroxyl radical allowed for the estimation of the vertical mixing time scale in the order of 100 ± 20 min. 相似文献
988.
989.
大型石油储罐消防设计研究 总被引:1,自引:1,他引:0
根据我国大型储罐设置的特点,分析了大型石油储罐在储存、转运过程中潜在的火灾危险。通过对千例石油火灾案例统计分析,获得了石油储罐发生火灾的主要原因。在此基础上,从石油储罐工艺设计、布局、防火和灭火等角度出发,分析大型石油储罐常用的类型、材料和防腐处理技术;研究储罐的布置间距;总结大型储罐消防设计中采用的防、灭火技术措施。论文研究的成果,可供实践工程参考。 相似文献
990.
煤炭应急供应的储备机制研究 总被引:2,自引:0,他引:2
借鉴关于石油储备的研究,界定煤炭应急储备的含义,分析煤炭储备的功能。根据我国煤炭供应的特点,探讨煤炭应急储备模式,提出我国煤炭应急储备的基本构想,指出我国煤炭应急储备应以地方储备、企业储备、现货储备为主,应急储备和日常储备相结合。从煤炭消费量、自给率、运输条件、经济实力4个方面分析影响储备规模的因素,测算各省区的储备规模。结合煤炭应急储备的基本构想和煤炭应急储备计划、轮换、动用的要求,提出煤炭储备管理的二级储备体系和三级管理体系,以及政府监督、市场运作、企业主导的储备运行模式。该研究成果对我国煤炭应急储备体系的建设具有很好的借鉴和参考意义。 相似文献