GEOSCAN, résultats de la recherche

Menu GEOSCAN


TitreGeochemical background
TéléchargerTéléchargement (publication entière)
AuteurGarrett, R G
SourcePresentations and recommendations from the workshop on the role of geochemical data in environmental and human health risk assessment, Halifax, 2010; par Rencz, A N (éd.); Kettles, I M (éd.); Commission géologique du Canada, Dossier public 6645, 2011 p. 22; 1 CD-ROM, https://doi.org/10.4095/287946
Année2011
ÉditeurRessources naturelles Canada
RéunionWorkshop on the role of geochemical data in environmental and human health risk assessment; Halifax; CA; mars 17-18, 2010
Documentdossier public
Lang.anglais
DOIhttps://doi.org/10.4095/287946
MediaCD-ROM; en ligne; numérique
Référence reliéeCette publication est contenue dans Rencz, A N; Kettles, I M; (2011). Presentations and recommendations from the workshop on the role of geochemical data in environmental and human health risk assessment, Halifax, 2010, Commission géologique du Canada, Dossier public 6645
Référence reliéeCette publication est reliée à Friske, P W B; Ford, K L; Kettles, I M; McCurdy, M W; McNeil, R J; Harvey, B A; (2010). North American soil geochemical landscapes project: Canadian field protocols for collecting mineral soils and measuring soil gas radon and natural radioactivity, Commission géologique du Canada, Dossier public 6282
Référence reliéeCette publication est contenue dans Rencz, A N; Kettles, I M; (2011). Presentations and recommendations from the workshop on the role of geochemical data in environmental and human health risk assessment, Halifax, 2010, Commission géologique du Canada, Dossier public 6645
Formatspdf
ProvinceColombie-Britannique; Alberta; Saskatchewan; Manitoba; Ontario; Québec; Nouveau-Brunswick; Nouvelle-Écosse; Île-du-Prince-Édouard; Terre-Neuve-et-Labrador; Territoires du Nord-Ouest; Yukon; Nunavut
SNRC1; 2; 3; 10; 11; 12; 13; 14; 15; 16; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 52; 53; 54; 55; 56; 57; 58; 59; 62; 63; 64; 65; 66; 67; 68; 69; 72; 73; 74; 75; 76; 77; 78; 79; 82; 83; 84; 85; 86; 87; 88; 89; 92; 93; 94; 95; 96; 97; 98; 99; 102; 103; 104; 105; 106; 107; 114O; 114P; 115; 116; 117; 120; 340; 560
Lat/Long OENS-141.0000 -50.0000 90.0000 41.7500
Sujetsanalyse environnementales; etudes de l'environnement; effets sur l'environnement; géochimie du sol; sols; études pédologiques; échantillons de sol; propriétés du sol; contamination des métaux lourds; pollution; substances polluantes; biogéochimie; levés biochimiques; levés géochimiques; géochimie; géologie de l'environnement; Cénozoïque; Quaternaire
Consultation
Endroit
 
Bibliothèque de Ressources naturelles Canada - Ottawa (Sciences de la Terre)
 
Bibliothèque de Ressources naturelles Canada - Calgary (Sciences de la Terre)
 
Commission géologique du Canada (Atlantique)
 
Bibliothèque de Ressources naturelles Canada - Vancouver (Sciences de la Terre)
 
Bibliothèque de Ressources naturelles Canada - Québec (Sciences de la Terre)
 
ProgrammeEcosystems Risk Characterization, Géoscience de l'environnement
LiensCanadian Database of Geochemical Surveys, downloadable files
LiensBanque de données de levés géochimiques du Canada, fichiers téléchargeables
Diffusé2011 01 01
Résumé(disponible en anglais seulement)
The concept of geochemical background is discussed, defined and a distinction made between natural background and ambient background. A key issue is that background is a range, not a single value. The range of background should span the measurements likely to be encountered during sampling and analysis in situations devoid of major mineral occurrences and severe impacts by anthropogenic contamination. The acceptance of 'ambient background' as a quantifiable estimate implies that some anthropogenic impact is acknowledged, but it does not 'overwhelm' the natural patterns of variation due to geology, pedology, etc. The role of both spatial, map, and statistical data displays is discussed, and how appraisal of survey data with these tools informs as to whether the data should be divided into subsets before estimating background ranges.
As an example, the data acquired by the US-EPA 3050B Aqua Regia (4:1 HCl-HNO3) variant for As and Pb in the <2 mm fraction of the 0-5 cm soil interval are discussed and background ranges estimated. It is demonstrated that the Maritimes 2007 data are poly-populational, and different background ranges should to be estimated for the three ecoprovinces present, the Appalachian and Acadian Highlands, the Northumberland Uplands and the Fundy Uplands. Several factors underlie the spatial definition one of which is geology, base metal ore occurrences, the Bathurst camp, lie in the Appalachian and Acadian Highlands ecoprovince; and widespread minor As occurrences associated with gold in mainland Nova Scotia occur in the Fundy Uplands ecoprovince.
Both statistical numerical methods and graphical methods are demonstrated. It is shown that different numerical procedures and whether data are logarithmically transformed, a common practice in applied geochemistry, lead to different estimates. This begs the question, which is right, or at least the best? It is shown how the a combination of graphical inspection to remove outliers likely not representative of background processes, e.g., data related to the presence of major mineral occurrences or discernable anthropogenic contamination, and the use of percentiles leads to useful estimates of background range. In conclusion, some more complex multivariate approaches to background estimation and gaining an understanding of the data are briefly presented, with their constraints. For univariate, an element at a time, estimates it is recommended that the hybrid approach of map and statistical data displays, the removal of nonbackground data from the data set(s) and the use of percentiles be adopted.
GEOSCAN ID287946