ORIGINAL PAPER Source and background threshold values of potentially toxic elements in soils by multivariate statistics and GIS-based mapping: a high density sampling survey in the Parauapebas basin, Brazilian Amazon Prafulla Kumar Sahoo . Roberto Dall’Agnol . Gabriel Negreiros Saloma˜o . Jair da Silva Ferreira Junior . Marcio Souza da Silva . Gabriel Caixeta Martins . Pedro Walfir Martin e Souza Filho . Mike A. Powell . Clovis Wagner Maurity . Roˆmulo Simo˜es Angelica . Marlene Furtado da Costa . Jose´ Oswaldo Siqueira Received: 18 December 2018 / Accepted: 5 June 2019 Ó Springer Nature B.V. 2019 Abstract A high-density regional-scale soil geo- chemical survey comprising 727 samples (one sample per each 5 9 5 km grid) was carried out in the Parauapebas sub-basin of the Brazilian Amazonia, under the Itacaiu´ nas Basin Geochemical Mapping and Background Project. Samples were taken from two depths at each site: surface soil, 0–20 cm and deep soil, 30–50 cm. The ground and sieved (\ 75 lm) fraction was digested using aqua regia and analyzed for 51 elements by inductively coupled plasma mass spectrometry (ICPMS). All data were used here, but the principal focus was on the potential toxic elements (PTEs) and Fe and Mn to evaluate the spatial distribution patterns and to establish their geochemical background concentrations in soils. Geochemical maps as well as principal component analysis (PCA) show that the distribution patterns of the elements are very similar between surface and deep soils. The PCA, applied on clr-transformed data, identified four major associations: Fe–Ti–V–Sc–Cu–Cr–Ni (Gp-1); Zr–Hf– U–Nb–Th–Al–P–Mo–Ga (Gp-2); K–Na–Ca–Mg–Ba– Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10653-019-00345-z) con- tains supplementary material, which is available to authorized users. P. K. Sahoo (&) Á R. Dall’Agnol Á G. N. Saloma˜o Á J. da Silva Ferreira Junior Á M. S. da Silva Á G. C. Martins Á P. W. M. e Souza Filho Á C. W. Maurity Á J. O. Siqueira Instituto Tecnolo´gico Vale (ITV), Rua Boaventura da Silva, 955, Bele´m, PA 66055-090, Brazil e-mail: prafulla.sahoo@itv.org; prafulla.iitkgp@gmail.com P. K. Sahoo Department of Environmental Science and Technology, School of Environmental and Earth Sciences, Central University of Punjab, Bathinda 151001, India R. Dall’Agnol Á G. N. Saloma˜o Á P. W. M. e Souza Filho Á C. W. Maurity Á R. S. Angelica Programa de Po´s-graduac¸a˜o em Geologia e Geoquı ´mica, Instituto de Geocieˆncias (IG), Universidade Federal do Para´ (UFPA), Rua Augusto Correˆa, Bele´m, PA 66075-110, Brazil M. S. da Silva Programa de Po´s-graduac¸a˜o em Cieˆncias Ambientais, Instituto de Geocieˆncias (IG), Universidade Federal do Para´ (UFPA), Rua Augusto Correˆa, Bele´m, PA 66075-110, Brazil M. A. Powell Department of Renewable Resources, Faculty of Agriculture, Life and Environmental Sciences (ALES), University of Alberta, Edmonton, Canada M. F. da Costa Gereˆncia de Meio Ambiente - Minas de Caraja´s, Departamento de Ferrosos Norte, Estrada Raymundo Mascarenhas, S/N Mina de N4, Parauapebas, PA 68516-000, Brazil 123 Environ Geochem Health https://doi.org/10.1007/s10653-019-00345-z