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921.
Monitoring Changes in Freshwater Macroinvertebrate Communities Along a Salinity Gradient Using Artificial Substrates 总被引:1,自引:0,他引:1
Scientists strive to develop efficient sampling protocols, reducing both the number of samples and processing time required,
which can be adapted for use in a broad range of ecosystems. We investigated the accuracy and usefulness of artificial substrates
in monitoring the impact of rising salinity on freshwater macroinvertebrate communities. We sampled seven sites along a salinity
gradient (from 0.2gL-1 to 2.6gL-1) over a 19-km stretch of the Meurthe River, in northeastern France. All other parameters remained stable in this section
of the river. Artificial substrate samples, each consisting of six liters of pebbles, were removed from the river at one-month
intervals and examined. Results obtained indicated the same qualitative impairments as those found in samples collected using
a Surber net. The use of artificial substrates was found to be a viable alternative method for assessing biological changes
in river quality due to increasing salinity disturbance when Surber sampling cannot be performed. 相似文献
922.
Cyrys J Pitz M Hazenkamp-von Arx ME Künzli N Heinrich J 《Environmental monitoring and assessment》2006,119(1-3):161-171
As part of the European Community Respiratory Health Survey (ECRHS) PM2.5 (particles collected with an upper 50% cut point of 2.5 μm aerodynamic diameter) was measured using an EPA-WINS (Environmetal Protection Agency Well Impactor Ninety-six) sampler. The monitoring schedule was restricted to 7 days per month for one year. Simultaneously, during this one year study period a collocated Harvard Impactor (HI) was run on a daily basis in Erfurt, Germany. Here we validated the reliability of annual, seasonal and monthly means estimated using the ECRHS scheme (measurements taken less than 25% of the whole study period) with the ‘true’ long-term averages, which were estimated using all available daily means.The daily PM2.5 means, obtained by both instruments operated in parallel, were only slightly different (the mean difference between EPA-WINS and HI was 1.8 μg m−3 and 2.8 μg m−3 for the winter means). The values obtained by the two instruments were highly correlated (r = 0.95).In view of that negligible difference, no additional bias was seen with respect to the annual and the winter means estimated by the two different sampling strategies (the difference was 1.7 μg m−3 and 2.7 μg m−3, respectively). Monthly means, however, can only be considered to be a crude estimate that may substantially under- or overestimate the true monthly mean value. 相似文献
923.
924.
Performance Evaluation of the SLEUTH Model in the Shenyang Metropolitan Area of Northeastern China 总被引:5,自引:0,他引:5
Xiaoqing Wu Yuanman Hu Hong S. He Rencang Bu Jeff Onsted Fengming Xi 《Environmental Modeling and Assessment》2009,14(2):221-230
Performance evaluation is crucial for the development and improvement of an urban cellular automata model, such as SLEUTH.
In this paper, we employed multiple methods for map comparison and model validation to evaluate the simulation performance
of the SLEUTH urban growth model in the Shenyang metropolitan area of China. These multiple methods included the relative
operating characteristic (ROC) curve statistic, multiple-resolutions error budget, and landscape metrics. They were used to
quantitatively examine model performance in terms of the amount and spatial location of urban development, urban spatial pattern
and prediction ability. The assessment results showed that SLEUTH performed well in the way of the quantitative simulation
of urban growth for this case study. Similar to other urban growth models, however, the simulation accuracy for spatial location
of new development at the pixel scale and urban spatial pattern still needs to be improved greatly. These inaccuracies might
be attributed to the structure and nature of SLEUTH, local urban development characteristics, and the temporal and spatial
scale of its application. Finally, many valuable suggestions had been put forward to improve simulation performance of SLEUTH
model for spatial location of urban development in the Shenyang metropolitan area. 相似文献
925.
水环境中多环芳烃的污染现状及研究进展 总被引:1,自引:0,他引:1
概述了多环芳烃(PAHs)的属性和主要来源,介绍了其在不同环境介质中的分析方法、污染状况、迁移转化及风险评估现状,提出了进一步加强复杂环境基质中PAHs分析方法、不同环境介质中PAHs迁移转化特征,以及PAHs环境生态风险和人体健康风险等方面研究的建议。 相似文献
926.
用定电位电解法测定SO2时,会出现多种影响测试结果的各种因素。本文对此进行了讨论,结果表明,采取有效措施可降低干扰,极大的提高了污染源监测和在线比对监测的可靠性和准确性。 相似文献
927.
928.
929.
固体测汞仪采用热分解齐化原子吸收光度法,此方法可以直接测定土壤中汞的含量。通过实验分析表明:此方法相关系数r≥0.999,检出限为0.01 ng,精密度为6.0%~9.1%,准确度为0%~6.7%,加标回收率为95%~107%。本方法具有简便、快速、准确、干扰少、成本低等优点,适合大批量土壤样品的测定。 相似文献
930.
近岸海域富营养化评价方法的研究进展和比较 总被引:3,自引:0,他引:3
富营养化是沿海经济和社会发展面临的主要环境问题,近些年基于科学研究成果与经验,国外近岸海域富营养化评价方法已有长足进步,与之相比,中国现行方法仍处于初级阶段。通过文献资料分析,总结了奥斯陆-巴黎委员会、赫尔辛基委员会、欧盟水框架指令、美国海洋和大气管理局等富营养化评价方法的特点,并在应用范围、评价指标体系、标准、数据要求、程序及结果等方面进行了比较。针对中国目前近岸海域监测现状提出建议,为建立适合中国近岸海域富营养化特点的评价方法提供借鉴和参考。 相似文献