GEOSCAN, résultats de la recherche


TitreGeochemical data quality control for soil, till and lake and stream sediment samples
AuteurMcCurdy, M W; Garrett, R G
SourceCommission géologique du Canada, Dossier public 7944, 2016, 40 pages, (Accès ouvert)
LiensCanadian Database of Geochemical Surveys, downloadable files
LiensBanque de données de levés géochimiques du Canada, fichiers téléchargeables
ÉditeurRessources naturelles Canada
Documentdossier public
Mediaen ligne; numérique
Sujetsanalyses géochimiques; interprétations géochimiques; levés géochimiques; collectes des données; méthodes de collecte de données de terrain; géochimie des sédiments de cours d'eau; géochimie de l'eau de cours d'eau; géochimie du sol; géochimie du till; géochimie des sediments lacustres; géochimie des eaux lacustres; géochimie
Illustrationstables; plots
ProgrammeNord-est du Québec-Labrador, géologie des dépôts meubles de la région d'Hudson/Ungava, GEM2 : La géocartographie de l'énergie et des minéraux
Diffusé2016 01 28
Résumé(Sommaire disponible en anglais seulement)
Geochemical data for lake and stream sediments, soils and tills received from commercial and government laboratories need to be evaluated for quality in terms of accuracy and precision before release. Quality control (QC) of National Geochemical Reconnaissance data is carried out using Microsoft Excel® with the Open Source R Project for Statistical Computing software (R Core Team, 2015) and 'rgr', 'The GSC Applied Geochemistry EDA Package' (Garrett 2013a, 2015a), that sits on top of R and provides the functionality required for many QA/QC tasks. Routines in 'rgr' are used to evaluate small (<20 samples) using graphical methods and larger batches using both graphical and statistical methods. Accuracy is estimated by inserting Certified Reference Materials (CRM) with accepted mean concentrations determined by different analytical methods. Precision is estimated using analytical duplicate pairs. For large batches of samples (>30 pairs of observations) an analysis of variance (ANOVA) is carried out using field duplicate pairs.
This document represents the first step in a process with the goal of building a consistent methodology for evaluating the quality of geochemical analytical data before they are released to the public. For the most part, the procedures described below, especially the construction of tables for Accuracy, Precision and ANOVA, are both time-consuming and tedious. However, there are a number of open source programs available that can be used in conjunction with R and Microsoft Excel® that could expedite the generation of statistics and the process of filling in the rows and columns of the tables. These include RExcel, an add-in to Excel that allows the use of R as a 'helper application' for Excel (Heiberger and Neuwirth, 2009). RStudio and Rcmdr are menu interfaces for R, also free and Open Source that could be integrated with R and Excel to create a system for evaluating the quality of geochemical data in a timely and efficient manner.
The reader is advised that the GSC has never had a single institutional approach to geochemical quality control. The procedures described herein have been developed by one group at one location (601 Booth Street, Ottawa). Other groups have instituted other procedures.
Résumé(Résumé en langage clair et simple, non publié)
Ce dossier public fournit des procédures graphiques et statistiques pour estimer l'exactitude et la précision de données géochimiques de sédiments des lacs et des cours d'eau provenant de laboratoires commerciaux et gouvernementaux. Ces procédures sont utilisées pour évaluer les données pour le Programme national de la reconnaissance géochimique à la Commission géologique du Canada.