Geostatistical analyses and hazard assessment on soil lead in Silvermines area, Ireland David McGrath a , Chaosheng Zhang b, *,OwenT.Carton a a Teagasc, Johnstown Castle Research Centre, Wexford, Ireland b Department of Geography and Environmental Change Institute, National University of Ireland, Galway, Ireland Received 1 November 2002; accepted 25 July 2003 ‘‘Capsule’’: A probability map was produced that was useful for hazard assessment and decision support. Abstract SpatialdistributionandhazardassessmentofsoilleadintheminingsiteofSilvermines,Ireland,wereinvestigatedusingstatistics, geostatisticsandgeographicinformationsystem(GIS)techniques.PositivelyskeweddistributionandpossibleoutlyingvaluesofPb and other heavy metals were observed. Box–Cox transformation was applied in order to achieve normality in the data set and to reduce the effect of outliers. Geostatistical analyses were carried out, including calculation of experimental variograms and model fitting. The ordinary point kriging estimates of Pb concentration were mapped. Kriging standard deviations were regarded as the standard deviations of the interpolated pixel values, and a second map was produced, that quantified the probability of Pb con- centration higher than a threshold value of 1000 mg/kg. These maps provide valuable information for hazard assessment and for decision support. # 2003 Elsevier Ltd. All rights reserved. Keywords: Geostatistics; Box-Cox transformation; Kriging standard deviation; Lead; Probability map; Hazard assessment 1. Introduction Numerous soil surveys have been carried out for Pb and for other metals at a national scale (e.g. McGrath and Loveland, 1992; Holmgren et al., 1993; Bak et al., 1997) and also in urban and industrial areas (e.g., Davies, 1983; Cullbard et al., 1988; Pouyat and McDonnell, 1991). These surveys have served to quan- tify levels in different situations and have produced an understanding of background and anthropogenic sour- ces for metals in soils (Zhang et al., 1999; Vreca et al., 2001). At and near historic mining sites, particularly high concentrations of Pb in soils may cause especially serious environmental pollution problems (Davies, 1983) extending even to death in animals (Wardrope and Graham, 1982). For affected areas it is essential to gain an understanding of the size of the affected area, level of soil Pb concentration and of its spatial dis- tribution within the area (Markus and McBratney, 2001). In addition the likely future impact of Pb on animals under recommended management conditions at local and, even farm, level (TEAGASC, 2001) needs to be ascertained. Geostatistics provides an advanced methodology which facilitates quantification of the spatial features of soil parameters and enables spatial interpolation (Bur- gess and Webster, 1980; Webster, 1994; Dobermann et al.,1997;Steinetal.,1997;Zhangetal.,2000;Carlonet al., 2001). In addition, geostatistics (Markus and McBratney, 1996; Goovaerts, 1999, 2001) and GIS (Korre et al., 2002) have become useful tools for the study of spatial uncertainty and hazard assessment. Between 1999 and mid 2002 there have been at least five recorded incidents of Pb poisoning, each of which hasresultedinthedeathofoneortwobovines,onfarms intheSilverminesarea,CountyTipperary,Ireland.Fol- lowing the first incident, an inter-agency group, com- prising several organizations, was established and given the task of overseeing a major investigation into the 0269-7491/$ - see front matter # 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2003.07.002 Environmental Pollution 127 (2004) 239–248 www.elsevier.com/locate/envpol * Corresponding author. Fax: +353-91-525700. E-mailaddresses: dmcgrath@johnstown.teagasc.ie(D.McGrath), chaosheng.zhang@nuigalway.ie (C. Zhang), ocarton@johnstown.tea- gasc.ie (O.T. Carton).