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321.
针对含有两种或两种以上Aroclor多氯联苯混合物的样品,研究其简便易行的定性、定量方法。将复杂样品中的多氯联苯分别折算成Aroclor 1016、1242、1260含量,在定性的同时予以定量。3种不同组分混合样品的加标回收率分别为68.2%~80.6%、67.9%~74.2%、67.1%~76.8%,实际土壤样品的测定结果与已有研究结果相吻合。方法缺点为无法识别和计算各Aroclor之间的准确比例,可用于应急监测复杂组分样品中多氯联苯的测定。 相似文献
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G.B. Senay J.P. Verdin R. Lietzow A.M. Melesse 《Journal of the American Water Resources Association》2008,44(4):969-979
Abstract: Accurate and reliable evapotranspiration (ET) datasets are crucial in regional water and energy balance studies. Due to the complex instrumentation requirements, actual ET values are generally estimated from reference ET values by adjustment factors using coefficients for water stress and vegetation conditions, commonly referred to as crop coefficients. Until recently, the modeling of reference ET has been solely based on important weather variables collected from weather stations that are generally located in selected agro‐climatic locations. Since 2001, the National Oceanic and Atmospheric Administration’s Global Data Assimilation System (GDAS) has been producing six‐hourly climate parameter datasets that are used to calculate daily reference ET for the whole globe at 1‐degree spatial resolution. The U.S. Geological Survey Center for Earth Resources Observation and Science has been producing daily reference ET (ETo) since 2001, and it has been used on a variety of operational hydrological models for drought and streamflow monitoring all over the world. With the increasing availability of local station‐based reference ET estimates, we evaluated the GDAS‐based reference ET estimates using data from the California Irrigation Management Information System (CIMIS). Daily CIMIS reference ET estimates from 85 stations were compared with GDAS‐based reference ET at different spatial and temporal scales using five‐year daily data from 2002 through 2006. Despite the large difference in spatial scale (point vs. ~100 km grid cell) between the two datasets, the correlations between station‐based ET and GDAS‐ET were very high, exceeding 0.97 on a daily basis to more than 0.99 on time scales of more than 10 days. Both the temporal and spatial correspondences in trend/pattern and magnitudes between the two datasets were satisfactory, suggesting the reliability of using GDAS parameter‐based reference ET for regional water and energy balance studies in many parts of the world. While the study revealed the potential of GDAS ETo for large‐scale hydrological applications, site‐specific use of GDAS ETo in complex hydro‐climatic regions such as coastal areas and rugged terrain may require the application of bias correction and/or disaggregation of the GDAS ETo using downscaling techniques. 相似文献
324.
Yuandong Zhang Shirong Liu Xiaohua Wei Jingtao Liu Guobin Zhang 《Journal of the American Water Resources Association》2008,44(5):1144-1153
Abstract: To combat its growing ecological problems, China has implemented a large‐scale Natural Forest Protection Program (NFPP). Under the umbrella of this program, the Sloping Land Conversion Program (SLCP) was established in 1999 to return cultivated land with slopes of 25° or more to perennial vegetation. However, the regional impacts on water resource management that are incurred by afforestation have not been carefully evaluated, especially in the subalpine region of southwestern China. The purpose of the present study was to provide reference values for the SLCP by evaluating the potential impact of afforestation on water yield under different climatic regimes. Accordingly, evapotranspiration (ET) in cropland (CL), shrubland, and general forest was calculated using a modification of Thornthwaite’s method, and in coniferous forest, broad‐leaved forest (BF), and mixed coniferous and broad‐leaved forest (MF) using the Surface Energy Balance Algorithm for Land (SEBAL) model. The results of both approaches showed that afforestation reduces water yield by 9.6‐24.3% depending on the types of conversion and climatic conditions. Water‐yield reduction is greatest (>143.4 mm, or 24.3%) when CL is converted to BF in dry climate conditions. Compared with the other forest types studied, coniferous plantations prevented water‐yield reduction by as much as 9.6% because of their relatively low levels of ET. It is expected that implementation of the SLCP, together with continuing climate change, will further pressure regional water resources. Thus, the effectiveness of afforestation must be evaluated in a broader context while taking into account its positive ecological aspects, such as soil‐erosion control, the preservation of biodiversity, and the significant carbon sequestration provided by forests. 相似文献
325.
比较分析法是监测部门分析数据的常用方法,使用EXCEL的数据库和列表函数可方便快捷地获得复杂条件下同比、环比或其它比较分析的结果。掌握EXCEL的单元格引用,可极大减轻大量重复类型公式的输入,迅速地完成数据比较分析。以城市环境空气监测数据的比较分析为例,展示了一种快速实现比较分析的方法与步骤。 相似文献
326.
确定水质参照状态是近岸海域营养物及其响应指标基准制定的关键,基于现场观测数据分析确定参照状态并提出推荐基准值是一种重要的方法.以辽河口近岸海域为例,根据1995年~1999年和2003年~2009年的数据分析,主要应用频数分析法确定了参照状态,并结合1976年的数据分析,提出了该海域营养物(溶解无机氮、总氮、活性磷酸盐、总磷)及响应指标(叶绿素、溶解氧)的推荐基准值.分析显示,辽河口近岸海域营养物溶解无机氮、总氮、活性磷酸盐和总磷的推荐基准值分别为0.11, 0.19, 0.006, 0.032mg/L;响应指标叶绿素、溶解氧的推荐基准值分别为0.0009, 6.14mg/L. 相似文献
327.
中国生命周期参考数据库的建立方法与基础模型 总被引:28,自引:11,他引:28
缺乏完善的本地化LCA(Life Cycle Assessment)数据库是国内广泛开展LCA研究与应用的主要障碍.本文总结提出了建立中国生命周期参考数据库(Chinese Reference Life Cycle Database,CLCD)的基本方法,包括环境影响类型与物质名录的选择、单元过程清单数据的收集与审核、生命周期清单数据的建模与计算、CLCD数据库的建立等4个方面.按照上述方法,以电力、煤炭、燃油、运输等基础性产品为核心,初步建立了可扩展的中国基础工业系统的生命周期模型,收集了单元过程的全国平均清单数据,通过模型计算获得了这些基础性产品的生命周期清单数据,从而得到了CLCD基础数据库,为下一步扩展为更完善的CLCD数据库提供了方法与模型基础. 相似文献
328.
我国土壤水分状况的估算 总被引:7,自引:1,他引:7
根据改进的彭曼公式估算出的年干燥度,依据《中国土壤系统分类(修订方案)》中有关土壤水分状况的定量诊断指标,对我国的土壤水分状况进行估算,初步将我国划分为3个土壤水分区,6个土壤水分亚区,为我国土壤资源的定量评价与管理提供了科学依据 相似文献
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