ORIGINAL ARTICLE Multiple discriminant analysis of the Drava River alluvial plain sediments Zoran Peh Æ Robert S ˇ ajn Æ Josip Halamic ´ Æ Lidija Galovic ´ Received: 20 September 2007 / Accepted: 22 October 2007 / Published online: 14 November 2007 Springer-Verlag 2007 Abstract Three discriminant function models are raised and cross-compared in order to distinguish geochemical patterns characteristic for the Drava River floodplain sed- iments. Based on data representing total element concentrations in samplescollected from alluvium (A), terrace (T), and unconsolidated bedrock (B) at the border of a floodplain, four element clusters emerged accounting for discrimination between the referred groups of sedi- ments.The most prominent is contaminant/carbonate cluster characteristic for alluvium. The other two are: sil- icate cluster typical for unconsolidated geological substrate (Neogenesedimentary rocks);and naturallydispersed heavy metal cluster separating terrace from the former two groups.Modelsintroducing depth intervals and single profilesas grouping criteria revealidenticalsediment- heavy metal matrices. The second important issue of this paper is possibility of reclassification of samples originally assigned to one of the a priori defined groups of sediments, based on established geochemical pattern. The mapped geological unitscan be reconsidered by the post hoc assignments to a differentgroupif geologicalborder between alluvium and terrace or between terrace and bedrock can not be established geologically with absolute certainty. Keywords Floodplain sediments Heavy metals Multiple discriminant analysis Drava River Slovenia Croatia Introduction The modern floodplains are potential repositories for a wide range of contaminants among which heavy metals represent by farthe greatest threato human health and environment. The release of metal-rich waste into the flu- vial environment often combines variousanthropogenic sources such as mining operations, industrial and urban wastes, transport, agricultural activity,deforestation, and others. This impact is recorded in the vertical overbank profiles of river alluvium,sometimeswith dramatic increase of heavy metal concentration, mainly in the uppe part (e.g. Macklin et al. 1994, 2006; Swennen et al. 1994, 1998;Swennen and Van Der Sluys 2002; Langedall and Ottesen 1998; Ciszewski 2002;Bølviken et al. 2004; Pavlovic et al. 2004; Cappuyns et al. 2006), or,generally, in depth-integrated surficial overbank sediment samples o topsoil developed on floodplains (e.g. Ottesen et al. 1989; McConneletal. 1993;O ´ dor etal. 1997;Rognerud et al. 2000; Bidovec et al. 1999; Halamic ´ et al. 2003; Romic and Romic 2003). However, in longer terms, heavy metals may be also introduced into the soil and hydrosphere by natura processes—weathering, erosion and transport—easily blending anthropogenic signalwith a naturalone and causing the pattern of metal distribution in alluvial plain sediments more difficult to assess. The problem is magni- fied by the fact thatfloodplains join togethervarious distinctgeomorphicand hydrologicfeatures,which directly influence their geochemical signature. It has long beenrecognized thatdispersionpatterns, storage and Z. Peh (&) J. Halamic ´ L. Galovic ´ Croatian Geological Institute, Sachsova 2, P.O. Box 268, HR-10000 Zagreb, Croatia e-mail: zpeh@hgi-cgs.hr R. S ˇ ajn Geological Survey of Slovenia, Dimic ˇeva 14, 1000 Ljubljana, Slovenia e-mail: robert.sajn@geo-zs.si 123 Environ Geol (2008) 55:1519–1535 DOI 10.1007/s00254-007-1102-2