Atmospheric sulfur hexafluoride in-situ measurements at the Shangdianzi regional background station in China

We present in-situ measurements of atmospheric sulfur hexafluoride（SF6） conducted by an automated gas chromatograph–electron capture detector system and a gas chromatography/mass spectrometry system at a regional background site, Shangdianzi,in China, from June 2009 to May 2011, using the System for Observation of Greenhouse gases in Europe and Asia and Advanced Global Atmospheric Gases Experiment（AGAGE）techniques. The mean background and polluted mixing ratios for SF6 during the study period were 7.22 × 10-12（mol/mol, hereinafter） and 8.66 × 10-12, respectively. The averaged SF6 background mixing ratios at Shangdianzi were consistent with those obtained at other AGAGE stations located at similar latitudes（Trinidad Head and Mace Head）, but larger than AGAGE stations in the Southern Hemisphere（Cape Grim and Cape Matatula）. SF6 background mixing ratios increased rapidly during our study period, with a positive growth rate at 0.30 × 10-12year-1. The peak to peak amplitude of the seasonal cycle for SF6 background conditions was 0.07 × 10-12, while the seasonal fluctuation of polluted conditions was 2.16 × 10-12. During the study period, peak values of SF6 mixing ratios occurred in autumn when local surface horizontal winds originated from W/WSW/SW/SWS/S sectors, while lower levels of SF6 mixing ratios appeared as winds originated from N/NNE/NE/ENE/E sectors.     

Efficiency analysis for organic agricultural producers: the role of soil-improving inputs

Greater emphasis is being placed on indicators of agri-environmental efficiency of organic production systems. Linking environmental measures with profitability measures based on net income is the only way to develop such indicators. A stochastic production frontier model that explicitly incorporates farm decisions about acquiring and managing organic soil-improving inputs is used to measure efficiency. The results confirm that on-farm self-sufficiency in soil-improving inputs is positively related to farm-level efficiency.     

A preliminary validation of a new measure of occupational health and safety

INTRODUCTION: This article describes the validation of an instrument designed to conduct an Occupational Health and Safety (OHS) self-diagnosis using workers observations of tangible facts and actions in the workplace. The instrument puts the emphasis on observable factors that make it possible to act proactively before accidents actually occur. METHOD: Three companies were recruited from the printing sector in Québec based on their OHS performance (low, medium, and high), their interest in the project, and their availability. The master sample was composed of 269 people. Partial least squares (PLS) and vanishing tetrad analyses were used to study the behavior of the formative scales developed. RESULTS: The results indicate that partial revision of the instrument will be necessary to reach a fully satisfying level of validity. With regards to the statistical approach adopted, the use of a macro called CTA-SAS 2.0 developed by Bollen and Ting [Bollen, K.A., & Ting, K.-F. (1993). Confirmatory tetrad analysis. In P.V. Marsden (Ed.), Social methodology.Vol.23 (pp.147-176). Cambridge, MA: Blackwell, 23] has proven to be effective in providing a suitable statistical treatment of the latent formative variables on which our instrument's development is based. CONCLUSION: The results suggest that the instrument appears to be relatively robust and appropriate to diagnose OHS leading measures. IMPACT ON INDUSTRY: In the long run, this instrument will make it possible for companies to draw a more refined picture of OHS evolution, even in the absence of occupational injuries.     

水中氯化物测定的不确定度评定

根据硝酸银滴定法测定水中氯化物的含量，分析了该方法测量不确定度的来源，评定了水中氯化物的测量不确定度，在各不确定度中，以标准溶液配制与样品分析时滴定消耗的硝酸银体积引入的不确定度较大。     

PROBLEMS IN WEIGHTING OF HYETOGRAPHS1

ABSTRACT: It was found that the conventional weighting factor application to hyetograph ordinates results in artificially attenuated storm patterns. A modified weighting procedure is suggested which allows adjustments in the storm timing, peak intensity, and volume but conserves the storm pattern observed at the raingage nearest to the watershed point of interest. The systematic underestimation of peak flood flows, which result from conventional hyetograph weighting, can be avoided by conserving the hyetograph shape from the raingage nearest to any subarea of a modeled watershed and merely applying weighting factors to the rainfall volumes and temporal center of gravity of several hyetographs.     

Indicators for hydraulic and pollution retention assessment of stormwater infiltration basins

Infiltration basins are frequently used for stormwater management even though their long-term evolution is not well understood nor controlled. The two main problems encountered are clogging which compromises the hydraulic capacity of the basin and possible contamination of underlying soil and groundwater. This paper defines a framework for evaluating the hydraulic and pollution retention performance of infiltration basins in the long-term. Sets of context and performance indicators are proposed, along with two complementary modes of evaluation. Context indicators are identified in order to define the clogging and contamination states of the basins. Performance indicators are developed to assess several aspects of basin performance: drainage duration, overflow frequency, predictive life period, particle filtration and pollution trapping. Modes of evaluation include field investigation and long-term simulation modeling. Indicators are tested on five infiltration basins in suburban Lyon (France). Both context indicators and hydraulic performance indicators are reliable and their evaluation is representative of basin behavior. This is not the case for pollution retention performance indicators. Their assessment is difficult because of data quality. Field data has high uncertainties. The model is satisfactory for the hydraulic simulation and the evolution of clogging. Improvements are necessary for pollution flow simulation and the acquisition of better quality data is required.     

室内环境中化学污染物质测定法研究

室内环境中化学污染物质的测定是研究和解决室内环境问题的基础。本文以甲醛和挥发性有机化合物两种室内环境中的主要化学污染物质为例,介绍了目前世界各国采用的各种测定法及其动向,并探讨了测定时期、测定时间、采样点布置等有关问题,提出了一些看法供参考。     

地应力壶与临震预测

设计和安装了地应力壶，在１９７７～１９７８年进行了观测。用日变曲线异常进行临震预测。在地震三要素预测中，发震时间预测较准确；在地点上震中方位角预测较准，震中距难以预测；震级预测误差较大。     

SALINITY INCREASES IN THE NAVAJO AQUIFER IN SOUTHEASTERN UTAH1

ABSTRACT: Salinity increases in water in some parts of the Nava-jo aquifer in southeastern Utah have been documented previously. The purpose of this paper is to use bromide, iodide, and chloride concentrations and del oxygen-18 and deuterium values in water from the study area to determine if oil-field brines (OFB) could be the source of increased salinity. Mixing-model results indicate that the bromide-to-chloride X 10,000 weight ratio characteristic of OFB in and outside the study area could not be causing the bromide depletion with increasing salinity in the Navajo aquifer. Mixing-model results indicate that a mixture of one percent OFB with 99 percent Navajo aquifer water would more than double the bromide-to-chloride weight ratio, instead of the observed decrease in the weight ratio with increasing chloride concentration. The trend of the mixing line representing the isotopically enriched samples from the Navajo aquifer does not indicate OFB as the source of isotopically enriched water; however, the simulated isotopic composition of injection water could be a salinity source. The lighter isotopic composition of OFB samples from the Aneth, Ratherford, White Mesa Unit, and McElmo Creek injection sites relative to the lsmay site is a result of continued recycling of injection water mixed with various proportions of isotopically lighter make-up water from the alluvial aquifer along the San Juan River. A mixing model using the isotopic composition of the simulated injection water suggests that enriched samples from the Navajo aquifer are composed of 36 to 75 percent of the simulated injection water. However, chloride concentrations predicted by the isotopic mixing model are up to 13.4 times larger than the measured chloride concentrations in isotopically enriched samples from the Navajo aquifer, indicating that injection water is not the source of increased salinity. Geochemical data consistently show that OFB and associated injection water from the Greater Aneth Oil Field are not the source of salinity increases in the Navajo aquifer.