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191.
Stream fish bioassessment methods assume that fish assemblages observed in sample sites reflect responses to local stressors, but fish assemblages are influenced by local factors as well as regional dispersal to and from connected streams. We hypothesized that fish movement to and from refugia and source populations in connected rivers (i.e., riverine dispersal) would weaken or decouple relations between fish community metrics and local environmental conditions. We compared fish-environment relations between streams that flow into large rivers (mainstem tributaries) and streams that lack riverine confluences (headwater tributaries) at multiple spatial grains using data from the USEPA's Environmental Monitoring and Assessment Program in the mid-Atlantic highlands, USA (n = 157 sites). Headwater and mainstem tributaries were not different in local environmental conditions, but showed important differences in fish metric responses to environmental quality gradients. Stream sites flowing into mainstem channels within 10 fluvial km showed consistently weaker relations to local environmental conditions than stream sites that lacked such mainstem connections. Moreover, these patterns diminished at longer distances from riverine confluences, consistent with the hypothesis of riverine dispersal. Our results suggest that (1) the precision of fish bioassessment metrics may be improved by calibrating scoring criteria based on the spatial position of sites within stream networks and (2) the spatial grain of fish bioassessment studies may be manipulated to suit objectives by including or excluding fishes exhibiting riverine dispersal. 相似文献
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193.
This study focuses on the verification of test interpretations for different state analyses of diffusion experiments. Part 1 of this study identified that steady, quasi-steady and equilibrium state analyses for the through- and in-diffusion tests with solution reservoirs are generally feasible where the tracer is not highly sorptive. In Part 2 we investigate parameter identifiability in transient-state analysis of reservoir concentration variation using a numerical approach. For increased generality, the analytical models, objective functions and Jacobian matrix necessary for inverse analysis of transient-state data are reformulated using unified dimensionless parameters. In these dimensionless forms, the number of unknown parameters is reduced and a single dimensionless parameter represents the sorption property. The dimensionless objective functions are evaluated for individual test methods and parameter identifiability is discussed in relation to the sorption property. The effects of multiple minima and measurement error on parameter identifiability are also investigated. The main findings are that inverse problems for inlet and outlet reservoir concentration analyses are generally unstable and well-posed, respectively. Where the tracer is sorptive, the inverse problem for the inlet reservoir concentration analysis may have multiple minima. When insufficient measurement data is collected, multiple solutions may result and this should be taken into consideration when inversely analyzing data including that of inlet reservoir concentration. Verification of test interpretation by cross-checking different state analyses is feasible where the tracer is not highly sorptive. In an actual experiment, test interpretation validity is demonstrated through consistency between theory and practice for different state analyses. 相似文献
194.
矿区铁路安全管理信息系统的研究 总被引:1,自引:0,他引:1
针对我国矿区铁路运输安全管理落后的现状,分析矿区铁路运输安全管理的主要特点,设计了矿区铁路安全管理信息系统的总体结构。以徐沛铁路运输系统为例,基于B/S模式开发了徐沛铁路安全管理信息系统,实现了对职工的安全培训考核、职工安全档案管理、运输事故信息的录入与统计分析、各类安全文档的管理、技术措施的审批和安全直通车的功能。该系统已在徐沛铁路运输安全管理中得到成功应用,也可应用于其他矿区铁路安全管理。 相似文献
195.
Study on Fish and Amphibian Embryo-Larval Toxicity Test 总被引:1,自引:0,他引:1
Zhang Tong 《Environmental monitoring and assessment》1999,55(3):363-369
In China, it is necessary to establish short-term biomonitoring methods for evaluating the chronic toxicity of industrial wastewater. In this paper, the aquatic toxicity of four important pollutants in petrochemical wastewater, including acrylonitrile, acetonitrile, sulphocyanic sodium and dimethyl formamide, was studied with fish and amphibian embryo-larval toxicity tests using Cyprinus carpio and Rana nigromaculata as test organisms. The objective is to present some useful data for establishing short-term chronic toxicity test methods used to perform biomonitoring in China. The results indicate that the chronic toxicity of acrylonitrile to fish and amphibians was the highest of the four test pollutants, followed by NaSCN, acetonitrile and DMF. The sensitivity of the carp embryo- larval test to chemicals was greater than that of the R. nigromaculata embryo-larval test. 相似文献
196.
孙文科 《防灾减灾工程学报》2001,21(2):30-33
以某大楼的基底反力监测为例 ,阐述了建筑物基底反力实时监测的原理与方法。监测分析结果表明 ,对在建建筑物进行的基底反力实时监测直接反映了土体受力状态 ,可间接得出桩基的受力情况。 相似文献
197.
对由实验定筛选的中华鳖出血肠炎病病原菌的最佳防治药物为本正交试验的第6组,即A2B3C1,其抑菌圈达21.5mm.临床应用中采用中西结合复方制剂,即用第6组试验药物再加上中药白头翁汤(加减),其疗效更佳. 相似文献
198.
本文应用地震学综合定量预报方法,结合区域地震活动特点,在华东地区进行了分区实际预报效能检验.结果表明该方法在华东地区有5个区域通过R值检验,效果较好,有4个区域未能通过R值检验;并对通过检验的区域地震活动趋势进行了分析. 相似文献
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200.
用蚕豆根尖细胞微核技术检测乌鲁木齐河水质 总被引:2,自引:0,他引:2
应用蚕豆根尖细胞微核技术对乌鲁木齐水质进行检测,测定各样点水样诱导的蚕豆根尖微核千分率及综合污染指数,并进行F检验,结果表明,各样点MCN‰有显著性差异,20个样点中有11个样点 的综合污染指数大于2,4个样点水样的综合污染指数大于3.5,和对照组相比有显著差异。所获得数据表明乌鲁木齐河水质受到较为了严重的致突变性污染。 相似文献