圆形烟道断面烟气测试中采样点距烟道内壁的距离讨论

本文根据圆形烟道采样点划分原则，给出了一种方便适用的采样点距烟道内壁的距离公式，并就现有文献中采样点距烟壁的距离值表格的误差进行了修正。     

γ能谱分析环境质量气溶胶核素活度浓度探测下限敏感性分析

根据敏感性分析原理,导出探测下限敏感性分析公式,分析探测下限与探测效率、采样体积、谱仪系统本底以及测量时间的敏感性,表明采样体积敏感性最高、谱仪本底敏感性次之、探测效率和测量时间敏感性相同且最低。实际工作中可以采用压制样品减小样品高度方式来有效降低探测下限。     

厌氧—好氧生物膜水处理技术

由河北省徐水县环保仪器厂开发、河北省环保局推荐的ＬＰＣＵ系列流量计适用于各行业污水排放的计量和比例水样采样。 主要技术内容 一、基本原理 该流量计采用计量和采样两项专利,微电脑控制自动显示和打印水位瞬时流量、累计流量,自动采样设置时间的比例水样。 二、技术关键 抛物堰口的抛物线切割精度和显示液位精度;电脑控制采样泵的比例水样采集的微电脑计算器。 主要技术指标 电源电压２２０Ｖ ,功率３０Ｗ,环境温度－１０～４５℃,相对湿度≥８５％,流量计精度≤土２．５％ ,采样精度≤土２．５％。 主要设备及运行管理 一、…     

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     

二氧化氮分析方法最低检出限的确定

环境空气中二氧化氮的分析方法为盐酸萘乙二胺分光光度法,根据吸收液体积与采样体积的不同方法最低检出限分别为0.010mg/m3(1)、0.005mg/m3(2),而在现场操作与实验室分析过程中为了更准确、方便、快捷、操作性强,对吸收液体积与采样体积作了一定的调整,因此方法的最低检出限通过实验室空白样品的测定重新确定。     

可编程计算器在烟尘测试中的应用

用小型可编程计算器编制烟尘现场采样及结果统计的程序，避免了复杂的公式计算以及查阅各种图表，不仅给现场测试人员减少负担和不安全的因素，而且为烟尘测试实现快速、高精、化繁就简的计算创造了条件，起到了事半功倍的效果。     

提高污水流量计准确测量方法的探讨

介绍了国内污水流量监测质量的相关技术要求,通过产品技术、建设安装以及检定校准等流量计应用三个方面来保证流量计监测数据的可靠性、真实性与准确性。根据污水流量计在现场的应用过程,提出安装、校准等方面存在的具体问题:超声波明渠流量计安装不规范,渠道液面不稳定;一些企业未进行流量计的检定和校准;流量计送检时间较长,无备用流量计;流量计缺少系统性日常运维。提出了流量计日常运行管理的相关建议:保证明渠流量计准确进行数据监测,要求企业开展流量计检定工作,优化流量计现场检定方法,制定污水流量计的维护制度。     

垃圾焚烧烟气排放指标换算

不同的国家和地区采用焚烧烟气排放指标不相同，特别是由于采用的参比状态不同，不能直接比较烟气排放指标的高低。本文根据国外目前采用的几种参比状态，提出不同参比状态下的转换公式，并计算出在同一参比状态下欧美等国家和地区采用的焚烧烟气排放指标。     

活动式大罐收气装置及油气混输新工艺的应用

为了解决东营地区油罐每天都向大气排放工业废气，对环境造成污染的问题，研制了“活动式大罐收气装置”新工艺，用于回收联合站储油罐挥发气。该装置通过玻璃钢管线与油罐连接，油罐挥发气沿玻璃钢管线输至机房内气液分离器，分离出气中的水和轻质油，由天然气压缩机加压，经流量计计量后进入油田天然气气管网。该工艺推广后，经监测结果表明，所有采样点总烃含量低于国家标准２．０ｍｇ／ｍ３。目前全油田３０个联合站安装了此设施，每年回收天然气５１２５万ｍ３，轻质油７０００ｔ。     

固定污染源废气中二氧化硫测定方法探讨

用碘量法测定污染源废气中二氧化硫时,用去离子水代替二氧化硫吸收液,并加入淀粉指示剂和碘标准溶液,采样过程中二氧化硫使紫色的吸收液退色,完全退色后,停止采样,记录采样体积,并根据加入的碘标准溶液量计算出废气中二氧化硫浓度。此方法操作方便、易于掌握,准确度能满足污染源监测的要求,通过比对实验,结果表明本方法是可行的。     

WATER QUALITY SAMPLING SCHEMES FOR VARIABLE FLOW CANALS AT REMOTE SITES1

ABSTRACT: Growing interest in water quality has resulted in the development of monitoring networks and intensive sampling for various constituents. Common purposes are regulatory, source and sink understanding, and trend observations. Water quality monitoring involves monitoring system design; sampling site instrumentation; and sampling, analysis, quality control, and assurance. Sampling is a process to gather information with the least cost and least error. Various water quality sampling schemes have been applied for different sampling objectives and time frames. In this study, a flow proportional composite sampling scheme is applied to variable flow remote canals where the flow rate is not known a priori. In this scheme, historical weekly flow data are analyzed to develop high flow and low flow sampling trigger volumes for auto‐samplers. The median flow is used to estimate low flow sampling trigger volume and the five percent exceedence probability flow is used for high flow sampling trigger volume. A computer simulation of high resolution sampling is used to demonstrate the comparative bias in load estimation and operational cost among four sampling schemes. Weekly flow proportional composite auto‐sampling resulted in the least bias in load estimation with competitive operational cost compared to daily grab, weekly grab sampling and time proportional auto‐sampling.     

碘量法测定溶解氧的取样技巧及改进方法

本文通过周密的设计和反复实验,分别从取样时间、取样位置和取样体积三方面进行了分析,并且从去离子水、地表水和污水进行对比实验数据中得出一个取样的最佳方案,从而对现有碘量法测定溶解氧的分析提出了修改意见。     

Characterization of waste materials originating from Quebec supermarkets and an assessment of recycling potential

This study evaluated, both qualitatively and quantitatively, waste materials from several major Quebec grocery stores. Averaged over nine sampling dates, cardboard, paper and wood products represented 43 and 74% of waste material, based on weight and volume, respectively while organic matter including fruits, vegetables, baked goods and meat products represented 40 and 10% of waste material based on weight and volume. Plastics, wrapping and bagging materials, represented over 7 and 13% of waste material based on weight and volume, respectively, and other recyclable waste materials such as glass, metal and various miscellaneous objects, represented 4 and 2% of waste material based on weight and volume. On average, 60.6 kg waste/employee per week was generated by the three stores. Store size was not a determining factor in the composition of grocery store waste material. These results suggest that costs associated with supermarket waste disposal may be substantially reduced by source-separation of recyclable and compostable materials while reducing pressure for incineration or landfill. Therefore, the adoption of recycling and source-separation programs, and studies to determine problems and costs associated with the implementation of such programs are recommended.     

CONTRASTING WATER QUALITY FROM PAIRED DOMESTIC/PUBLIC SUPPLY WELLS,CENTRAL HIGH PLAINS1

ABSTRACT: Closely located domestic and public supply wells were sampled using identical sampling procedures to allow comparison of water quality associated with well type. Water samples from 15 pairs of wells with similar screened intervals completed in the central High Plains regional aquifer in parts of Kansas, Oklahoma, and Texas were analyzed for more than 200 water quality constituents. No statistically significant differences were observed between the concentrations of naturally‐derived constituents (major ions, trace elements, and radon) in paired wells. However, differences in water quality between paired wells were observed for selected anthropogenic compounds (pesticides and tritium), in that some public supply wells produced water that was more recently recharged and contained constituents derived from surface activities. The presence of recently recharged water and compounds indicative of anthropogenic activities in some public supply wells was likely due to operational variations (pumping rate and pumping cycles), as demonstrated in a particle tracking simulation. Water containing surface‐derived anthropogenic compounds from near the water table was more quickly drawn to high volume public supply wells (less than five years) than domestic wells (greater than 120 years) with small pumping rates. These findings indicate that water quality samples collected from different well types in the same area are not necessarily directly comparable. Sampling domestic wells provides the best broad‐scale assessment of water quality in this aquifer setting because they are less susceptible to localized contamination from near the water table. However, sampling public supply wells better represents the quality of the used resource because of the population served.     

A Comparison of Sampling Designs for Monitoring Recreational Trail Impacts in Rocky Mountain National Park

The dual goals of the Organic Act of 1916 and Wilderness Act of 1964 are to protect natural resources and provide quality visitor experiences. Park managers need metrics of trail conditions to protect park resources and quality of visitor experiences. A few methods of sampling design for trails have been developed. Here, we describe a relatively new method, spatially balanced sampling, and compare it to systematic sampling. We evaluated the efficiency of sampling designs to measure recreation-related impacts in Rocky Mountain National Park. This study addressed two objectives: first, it compared estimates of trail conditions from data collected from systematic versus spatially balanced sampling data; second, it examined the relationship between sampling precision and sampling efficiency. No statistically significant differences in trail condition were found between the 100-m interval and the spatially balanced datasets. The spatially balanced probability-based dataset was found to be a good estimate of trail conditions when analyses were conducted with fewer sample points. Moreover, spatially balanced probability-based sampling is flexible and allows additional sample points to be added to a sample.     

Forecasting the number of soil samples required to reduce remediation cost uncertainty

Sampling scheme design is an important step in the management of polluted sites. It largely controls the accuracy of remediation cost estimates. In practice, however, sampling is seldom designed to comply with a given level of remediation cost uncertainty. In this paper, we present a new technique that allows one to estimate of the number of samples that should be taken at a given stage of investigation to reach a forecasted level of accuracy. The uncertainty is expressed both in terms of volume of polluted soil and overall cost of remediation. This technique provides a flexible tool for decision makers to define the amount of investigation worth conducting from an environmental and financial perspective. The technique is based on nonlinear geostatistics (conditional simulations) to estimate the volume of soil that requires remediation and excavation and on a function allowing estimation of the total cost of remediation (including investigations). The geostatistical estimation accounts for support effect, information effect, and sampling errors. The cost calculation includes mainly investigation, excavation, remediation, and transportation. The application of the technique on a former smelting work site (lead pollution) demonstrates how the tool can be used. In this example, the forecasted volumetric uncertainty decreases rapidly for a relatively small number of samples (20-50) and then reaches a plateau (after 100 samples). The uncertainty related to the total remediation cost decreases while the expected total cost increases. Based on these forecasts, we show how a risk-prone decision maker would probably decide to take 50 additional samples while a risk-averse decision maker would take 100 samples.     

ASSESSMENT OF SAMPLING ERROR ASSOCIATED WITH SOIL MOISTURE ESTIMATION DESIGNS1

A spectral formalism was developed and applied to quantify the sampling errors due to spatial and/or temporal gaps in soil moisture measurements. A design filter was developed to compute the sampling errors for discrete measurements in space and time. This filter has as its advantage a general form applicable to various types of sampling design. The lack of temporal measurements of the two‐dimensional soil moisture field made it difficult to compute the spectra directly from observed records. Therefore, the wave number frequency spectra of soil moisture data derived from stochastic models of rainfall and soil moisture were used. Parameters for both models were estimated using data from the Southern Great Plains Hydrology Experiment (SGP97) and the Oklahoma Mesonet. The estimated sampling error of the spatial average soil moisture measurement by airborne L‐band microwave remote sensing during the SGP97 hydrology experiment is estimated to be 2.4 percent. Under the same climate conditions and soil properties as the SGP97 experiment, equally spaced ground probe networks at intervals of 25 and 50 km are expected to have about 16 percent and 27 percent sampling error, respectively. Satellite designs with temporal gaps of two and three days are expected to have about 6 percent and 9 percent sampling errors, respectively.     

Evaluating the effects of spatial monitoring policy on groundwater quality portrayal

What size sample is sufficient for spatially sampling ambient groundwater quality? Water quality data are only as spatially accurate as the geographic sampling strategies used to collect them. This research used sequential sampling and regression analysis to evaluate groundwater quality spatial sampling policy changes proposed by California's Department of Water Resources. Iterative or sequential sampling of a hypothetical groundwater basin's water quality produced data sets from sample sizes ranging from 2.8% to 95% coverage of available point sample sites. Contour maps based on these sample data sets were compared to an original (control), mapped hypothetical data set, to determine at which point map information content and pattern portrayal are not improved by increasing sample sizes. Comparing series of contour maps of ground water quality concentration is a common means of evaluating the geographic extent of groundwater quality change. Comparisons included visual inspection of contout maps and statistical tests on digital versions of these map files, including correlation and regression products. This research demonstrated that, down to about 15% sample site coverage, there is no difference between contour maps produced from the different sampling strategies and the contout map of the original data set.     

IDENTIFICATION OF AN OPTIMAL SAMPLING STRATEGY FOR A CONSTRUCTED WETLAND1

ABSTRACT: The objective of this investigation was to determine the effect of sampling frequency and sampling type on estimates of monthly nutrient loads and flow‐weighted nutrient concentrations in a constructed wetland. Phosphorus and nitrogen loads and concentrations entering and leaving a subtropical wetland (the Everglades Nutrient Removal Project, ENRP) were calculated on the basis of three sampling frequencies. The first frequency included weekly composite samples (three daily samples composited for one week) and grab samples from August 1994 to July 1997, representing a base‐line condition for comparison with results using reduced sampling frequencies. The second and third sampling frequency included three and two composite samples per month, respectively, drawn from the weekly samples. Total phosphorus and nitrogen loads calculated using two and three samples per month were almost identical to results based on four samples per month (least‐squares regression coefficients ranged from 0.96 to 0.98). Results of monthly mean flow‐weighted nutrient concentrations, obtained using reduced sampling frequencies, also were strongly correlated to concentrations calculated using the base‐line sampling frequency (r²ranged from 0.82 to 0.93). Grab samples did not always provide good estimates of loads or concentrations, particularly at the inflow when data were highly variable. From the results of this study, we can recommend that bi‐weekly composite sampling be used to monitor nutrient concentrations and loads discharged from larger‐scale Everglades Stormwater Treatment Areas (STAs) now under construction. Because there are high costs associated with water sample collection and processing, studies to identify optimal sampling frequencies should be a key feature in the design of any comprehensive wetland‐monitoring program.     

ESTIMATION OF EPISODIC STREAM ACIDIFICATION BASED ON MONTHLY OR ANNUAL SAMPLING1

ABSTRACT: Programs of monthly or annual stream water sampling will rarely observe the episodic extremes of acidification chemistry that occur during brief, unpredictable runoff events. When viewed in the context of data from several streams, however, baseflow measurements of variables such as acid neutralizing capacity, pH and NO₃· are likely to be highly correlated with the episodic extremes of those variables from the same stream and runoff season. We illustrate these correlations for a water chemistry record, nearly two years in length, obtained from intensive sampling of 13 small Northeastern U.S. streams studied during USEPA's Episodic Response Project. For these streams, simple regression models estimate episodic extremes of acid neutralizing capacity, pH, NO₃·, Ca²⁺, SO₄^2?, and total dissolved Al with good relative accuracy from statistics of monthly or annual index samples. Model performances remain generally stable when episodic extremes in the second year of sampling are predicted from first-year models. Monthly or annual sampling designs, in conjunction with simple empirical models calibrated and maintained through intensive sampling every few years, may estimate episodic extremes of acidification chemistry with economy and reasonable accuracy. Such designs would facilitate sampling a large number of streams, thereby yielding estimates of the prevalence of episodic acidification at regional scales.