标准样品在环境监测应用中几点问题的探讨

环境(有证)标准样品(CERM)已成为环境监测及其质量保证/质量控制(QA/QC)重要工具和常用方法,科学理解和合理使用CERM越来越重要。 文章将CERM在环境监测应用中的有关问题归结为"泛标样"倾向和对CERM特性值误区两个方面,结合典型案例,通过不确定度评定分析相关误区或偏颇,并提出选择性使用CERM、按规定条件使用CERM、全面了解掌握CERM特性值、合理运用CERM特性值范围和慎重评价CERM特性值范围内测定结果的差异等具体对策和建议。     

A comparison of SEM-EDS with ICP-AES for the quantitative elemental determination of estuarine particles

Suspended particulate matter (SPM) is a key component regulating the biogeochemistry of natural and contaminant moieties in estuaries. Individual particle analyses can complement conventional bulk analyses of SPM, but are rarely undertaken. This study used scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDS) of particles to quantify a range of elements in the reference estuarine sediment PACS-2. This approach was compared with a bulk SPM analysis based on inductively coupled plasma-atomic emission spectrometry (ICP-AES). The median concentrations of Al, Fe, Mg, and Ca for the two approaches were similar, and accuracy for both methods was good. SEM-EDS analysis was also satisfactory for K. Agreement was poorer for Mn and Ti, which were present at trace concentrations. Increasing the number of particles examined by SEM-EDS should improve the analysis. SEM-EDS analysis of SPM from the Tamar Estuary, UK, revealed marked geochemical differences between particle sub-populations.Selected article from 6th European Meeting on Environmental Chemistry, Belgrade, 2005, organised by Prof. Dr. Branimir Jovancicevic and the European Association of Chemistry and the Environment (ACE, www.research.plymouth.ac.uk/ace)     

SOIL MOISTURE SENSORS FOR URBAN LANDSCAPE IRRIGATION: EFFECTIVENESS AND RELIABILITY1

ABSTRACT: Granular matrix soil moisture sensors were used to control urban landscape irrigation in Boulder, Colorado, during 1997. The purpose of the study was to evaluate the effectiveness and reliability of the technology for water conservation. The 23 test sites included a traffic median, a small city park, and 21 residential sites. The results were very good. The system limited actual applications to an average of 73 percent of the theoretical requirement. This resulted in an average saving of $331 per installed sensor. The sensors were highly reliable. All 23 sensors were placed in service at least three years prior to the 1997 study during earlier studies. Of these, only two had failed by the beginning of the 1997 study, both due to external factors. Including replacement of these failed sensors, the total repair cost for the 1997 irrigation season was less than $270. The effort required to maintain each system was small, only about 6–7 minutes per visit. Each site was visited weekly for this study, but less frequent visits could be made in practice. The sensors observed in this study performed well, significantly reduced water consumption, and were easy to monitor and maintain. Soil moisture sensors appear to be a useful and economical tool for urban water conservation.     

Modeling Carbon and Water Budgets in the Lushi Basin with Biome-BGC

1 INTRODUCTIONEvapotranspiration (ET) is the key process controlling theexchange of energy and hydrologic flux for vegetatedsurface. Terrestrial net primary productivity (NPP)represents the carbon available for plant allocation toleaves, stems, roots, defensive compounds, reproductionand is the basic measure of biological productivity. Treegrowth, forage available for grazing, food productivity,and atmospheric CO2 levels are all strongly controlled byNPP (White et al., 2000). The exch…     

固定污染源烟气排放连续监测系统验收测试实例及存在问题

通过辖区内固定污染源烟气排放连续监测系统参比方法验收监测实例,归纳总结出CEMS参比方法验收监测程序,查找在资料调研、现场勘查、编制监测方案、现场监测、报告编制过程中存在的问题,并提出相应的对策措施及注意事项。     

极性有机化合物整合采样技术在水环境有机污染物监测中的应用

极性有机化合物整合采样技术(Polar organic chemical integrative samplers,POCIS)适用于极性有机污染物的采集,随着新型极性有机污染物的不断出现,该技术已经引起了科学家的广泛关注.本文概述了几种常用的被动采样装置,重点介绍了POCIS采样器的一般结构、富集原理、环境因素如流速、温度、pH、溶解性有机质、盐度及膜的污染等对采样速率的影响,讨论了针对极性物质检测的质量控制和保证以及性能参考物质,综述了POCIS在水环境有机污染物监测中的应用.最后,本文对POCIS的应用前景进行了展望.     

LONG-TERM CHANGES IN STREAMFLOW FOLLOWING LOGGING IN WESTERN OREGON AND ASSOCIATED FISHERIES IMPLICATIONS1

ABSTRACT: The long-term effect of logging on low summer streamflow was investigated with a data set of 36 years. Hydrologic records were analyzed for the period 1953 and 1988 from Watershed (WS) 1 (clear-cut logged and burned), WS 2 (unlogged control), and WS 3 (25 percent patch-cut logged and burned) in the H. J. Andrews Experimental Forest, western Cascade Range, Oregon. These records spanned 9–10 years before logging, and 21–25 years after logging and burning. Streamfiows in August were the lowest of any month, and were unaffected by occasional heavy rain that occurred at the beginning of summer. August streamfiows increased in WS 1 compared to WS 2 by 159 percent following logging in WS 1, but this increase lasted for only eight years following the start of logging in 1962. Water yield in August for 1970–1988 observed from WS 1 was 25 percent less than predicted from the control (WS 2, ANOVA, p=0.032). Water yield in August increased by 59 percent after 25 percent of the area of WS 3 was patch-cut logged and burned in 1963. In contrast to WS 1, however, water yields from WS 3 in August were consistently greater than predicted for 16 years following the start of logging, through to 1978. For the 10 years, 1979–1988, water yield observed in August from WS 3 was not different than predicted from the control (WS 2, ANOVA, p-0.175). The contrasting responses of WS 1 and 3 to logging are thought to be the result of differences in riparian vegetation caused by different geomorphic conditions. A relatively wide valley floor in WS 1 allowed the development of hardwoods in the riparian zone following logging, but the narrow valley of WS 3 and limited sediment deposits prevented establishment of riparian hardwoods. Low streamflows during summer have implications for salmonid survival. Reduced streamflow reduces the amount of rearing habitat, thus increasing competition. Combined with high water temperatures, reduced streamflow can lead directly to salmonid mortality by driving salmonids from riffles and glides, and trapping them in drying pools. Low streamflow also increases oxygen depletion caused by leaves from riparian red alders.     

DDSC振动控制器的功能、指标及技术分析

DDSC（双数据处理振动控制器）系统是美国Dactron公司90年代研制的用于振动试验控制的新型振动控制器，具有硬件可靠，指标先进，功能完善的特点，在振动控制中具有很高的实用性和性价比，本文从使用的角度对其功能和技术特点进行展开分析。     

Modeling Carbon and Water Budgets in the Lushi Basin with Biome-BGC

Abstract

In this article, annual evapotranspiration (ET) and net primary productivity (NPP) of four types of vegetation were estimated for the Lushi basin, a subbasin of the Yellow River in China. These four vegetation types include: deciduous broadleaf forest, evergreen needle leaf forest, dwarf shrub and grass. Biome-BGC—a biogeochemical process model was used to calculate annual ET and NPP for each vegetation type in the study area from 1954 to 2000. Daily microclimate data of 47 years monitored by Lushi meteorological station was extrapolated to cover the basin using MT-CLIM, a mountain microclimate simulator. The output files of MT-CLIM were used to feed Biome-BGC. We used average ecophysiological values of each type of vegetation supplied by Numerical Terradynamic Simulation Group (NTSG) in the University of Montana as input ecophysiological constants file. The estimates of daily NPP in early July and annual ET on these four biome groups were compared respectively with field measurements and other studies. Daily gross primary production (GPP) of evergreen needle leaf forest measurements were very close to the output of Biome-BGC, but measurements of broadleaf forest and dwarf shrub were much smaller than the simulation result. Simulated annual ET and NPP had a significant correlation with precipitation, indicating precipitation is the major environmental factor affecting ET and NPP in the study area. Precipitation also is the key climatic factor for the interannual ET and NPP variations.     

Automated Calibration of the METRIC‐Landsat Evapotranspiration Process

A remaining challenge to applying satellite‐based energy‐balance algorithms for operational estimation of evapotranspiration (ET) is the calibration of the energy‐balance model. Customized calibration for each image date is generally required to overcome biases associated with radiometric accuracy of the image, uncertainties in aerodynamic features of the landscape, background thermal conditions, and model assumptions. The CIMEC process (calibration using inverse modeling at extreme conditions) is an endpoint calibration procedure where near extreme conditions in the image are identified where the ET can be estimated and assigned. In the Mapping EvapoTranspiration at high Resolution with Internalized Calibration (METRIC?) energy‐balance model, two endpoints represent the dry and wet ends of the ET spectrum. Generally, user‐intervention is required to select locations in the image to produce best accuracy. To bring the METRIC and similar processes into the domain of less experienced operators, a consistent, reproducible, and dependable statistics‐based procedure is introduced where relationships between vegetation amount and surface temperature are used to identify a subpopulation of locations (pixels) in an image that may best represent the calibration endpoints. This article describes the background and logic for the statistical approach, how the statistics were developed, area of interest requirements and assumptions, adjustment for dry conditions in desert climates, and implementation in a common image processing environment (ERDAS Imagine).