Through the cooperation of the Canada Centre for Mineral and Energy Technology (CANNET) and the Land Resource Research Institute of Agriculture Canada, four soil samples have been prepared as compositional reference materials: a clayey soil, a sandy podzolic B horizon with a high organic content, a calcareous till, and a chernozemic A horizon. All have a wide range of compositions. Bulk samples of 180 to 280 kg of each were dried, ground to minus 74 pm, blended, tested for homogeneity and bottled in 200-g units. Thirty-six laboratories participated in the certification program by providing analytical results for 1 to 25 constituents for each of two bottles of each sample. Based on statistical analyses of the data, the four reference samples were certified for Al, Fe, Mn, K, Zn, Cu, Cr and Pb, and one or more were certified for Si, Na, Mg, Ca, P, Ti, Hg, Ni, Sr and V. Preliminary data were obtained for another 47 elements.
New mean values for up to 11 major and minor and up to 11 trace elements in soils SO‐1 to SO4 have been calculated by two procedures. Analytical results received by CCRMP subsequent to the certification program of 1979 were included. In one instance, the same procedure as used for certification wherein all results except those rejected on chemical and/or statistical considerations was followed, but little improvement over the 1979 calculations was obtained. The other procedure is proposed by the authors for use in identifying concentration range intervals wherein maximum interlaboratory consensus is observed. The application of this procedure has permitted the certification of the four soils for the content of 24 elements not previously certified.
Four reference soils have been prepared and certified through the cooperation of Energy, Mines and Resources Canada and Agriculture Canada. Their origin and details of preparation and characterization are presented. Thirty‐six laboratories participated in the international certification program by providing approximately 16000 results for 65 elements. One or more of the reference soils were certified for 18 elements and preliminary data were obtained for another 47.
This article describes a statistical analysis of small water systems' turbidity data within the framework of a logic model for the USEPA's Performance-Based Training (PBT) program. The logic model shows the theoretical linkages between optimization training for small system operators; operator application of optimization techniques; improvements in plant filtration performance; and public health protection. The analysis comprised two phases. For the first phase, the authors used Bayesian analysis of turbidity data to test the statistical significance of changes in finished water quality resulting from training for small water system operators. For the second phase, the authors estimated the potential health benefits resulting from measured improvements in filtration performance. Considering only the improved removal of the pathogen Cryptosporidium, the expected annual health benefit of PBT is about ten fewer cases of infection per thousand persons served (within a 95% credible interval 0 to 18 fewer infections), though there may be benefits associated with the removal of other pathogens. The article also describes factors contributing to uncertainty in the estimated potential health benefits. The proposed two-phase approach supports the USEPA's development of drinking water program indicators which are meaningful, measurable, broadly applicable and change-sensitive.
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