AUTOMATIC BOTTLE SEALING MECHANISM FOR SEQUENTIAL SAMPLING OF VOLATILE ORGANICS IN WATER1

ABSTRACT: The design, construction, and evaluation of two automatic bottle sealing mechanisms for the collection of volatile organic compounds in water are described. Manually collected samples were either stored in uncapped bottles or in bottles capped with the automatic bottle sealing mechanisms. After 24 hours' storage, significant losses of volatile compounds from uncapped samples occurred even if the samples were stored at 4°C, but not for the samples capped with the automatic bottle sealing mechanisms. The mechanism for sealing the sample bottles was integrated into a commercial sampler with minor modifications to the sampler. The sampling system was then evaluated under controlled conditions to simulate actual field sampling. The results showed that the system was suitable for taking sequential discrete water samples automatically for 24 hours without significant losses of volatile organic compounds.     

RESERVOIR WATER QUALITY SAMPLING DESIGN1

ABSTRACT: The design of monitoring programs often serves as one of the major sources of error or uncertainty in water quality data. Properly designed programs should minimize uncertainty or at least provide a means by which variability can be partitioned into recognizable components. While the design of sampling programs has received recent attention, commonly employed strategies for limnological sampling of lakes may not be completely appropriate for many reservoirs. Based on NES data, reservoirs are generally larger, deeper, and morphologically more complex than natural lakes. Reservoirs also receive a majority of their inflow from a single tributary located a considerable distance from the point of outflow. The result is the establishment of marked physical, biological, and chemical gradients from headwater to dam. The existence of horizontal as well as vertical gradients, and their importance in water quality sampling design were the subject of intensive transect sampling efforts at DeGray Lake, a U.S. Army Corps of Engineers reservoir in southern Arkansas. Data collected were used to partition Variance, identify areas of similarity, and demonstrate how an equitable sampling program might be designed.     

预测流速法烟尘采样中采样嘴的选择及采样流量的计算

本文用公式计算出合理的采样嘴直径和采样流量,可以提高工作效率和数据的准确性     

自动等速采样仪控制系统设计

介绍了基于静压平衡法实现自动等速采样的原理，利用最新传感器感测技术、电子 器件以及控制技术实现烟道或排尘管道粉尘采样用自动等速采样仪控制系统的设计。     

APPLICATION OF THE PEBBLE COUNT NOTES ON PURPOSE,METHOD, AND VARIANTS1

ABSTRACT: The pebble count procedure (Wolman, 1954) is the measurement of 100 randomly selected stones from a homogeneous population on a river bed or bar, which yields reproducible size distribution curves for surficial deposits of gravel and cobbles. The pebble count is widely used in geomorphologr (and increasingly in river engineering) to characterize surficial grain size distributions in lieu of bulk samples, for which adequate sample sizes become enormous for gravels. Variants on the original method have been proposed, one of which, the so-called ‘zig-zag’ method (Bevenger and King, 1995), involves sampling along a diagonal line and drawing data points from many different geomorphic units. The method is not reproducible, probably because it incorporates stones from many different populations, and because an inadequate number of grains is sampled from any given population. Sampling of coarse bed material should be geomorphically stratified based on the natural sorting of grain sizes into distinct channel features. If a composite grain size is desired, the areas of the bed occupied by different populations can be mapped, pebble counts conducted on each, and a weighted average distribution computed.     

烟气二氧化硫分析仪采样计量泵的研制与应用

采样误差是抽样式污染源气体分析仪最大的误差来源之一。采样的气体浓度越高 ,越需要高精度的气体采样计量泵。文章介绍的计量泵精度可达 0 .1 1 %。应用该计量泵可以基本消除气体分析仪采样方面的计量误差     

Microsoft Word for Windows在环境质量报告书中的应用

叙述了ＭｉｃｒｏｓｏｆｔＷｏｒｄｆｏｒＷｉｎｄｏｗｓ软件在编写环境质量报告书中的应用内容。     

Statistical Analysis of Spatial Pattern: A Comparison of Grid and Hierarchical Sampling Approaches

Previous studies have combined random-site hierarchical sampling designs with analysis of variance techniques, and grid sampling with spatial autocorrelation analysis. We illustrate that analysis techniques and sampling designs are interchangeable using densities of an infaunal bivalve from a study in Poverty Bay, New Zealand. Hierarchical designs allow the estimation of variances associated with each level, but high-level factors are imprecisely estimated, and they are inefficient for describing spatial pattern. Grid designs are efficient for describing spatial pattern, and are amenable to conventional analysis. Our example deals with a continuous spatial habitat, but our conclusions also apply in disjunct or patchy habitats. The influence of errors in positioning is also assessed. The advantages of systematic sampling are reviewed, and more efficient hierarchical approaches are identified. The distinction between biological and statisticalsignificance in all analyses is emphasised.     

大辽河入海口水质在线自动监测系统取样工程的建设与维护

介绍一个以自吸喷射泵为取样泵的水质自动监测系统取样工程建设方案及其日常维护措施。适用于河口和四季分明水域建设水质自动监测站需要,更可在其他类型水域建站时借鉴使用。     

双程序双样品污染源监测采样方法探讨

本文针对当前环境监测四级站的污染源监测特点，提出了双程序双样品的监测采样方法．可避免排污企业受自身利益的驱使而对污染物排放采取弄虚作假的行为，使污染源监测更为客观公正，有利于污染源的监督管理。