Cadmium background concentrations to establish reference quality values for soils of São Paulo State, Brazil

• Published in: Environmental monitoring and assessment 2014-03, Vol.186 (3), p.1399-1408
• Main Authors: de Oliveira, Vinicius Henrique, de Abreu, Cleide Aparecida, Coelho, Ricardo Marques, Melo, Leônidas Carrijo Azevedo
• Format: Article
• Language: English
• Subjects: aluminum; Assessments; Atmospheric Protection/Air Quality Control/Air Pollution; Brazil; Cadmium; Cadmium - analysis; Cadmium - standards; Cation exchange; cation exchange capacity; Cation exchanging; Correlation analysis; Earth and Environmental Science; Ecology; Ecotoxicology; Environment; Environmental Management; Environmental Monitoring; Food contamination & poisoning; Heavy metals; Iron; lead; Metals; Monitoring/Environmental Analysis; Multivariate Analysis; Organic matter; Oxisols; principal component analysis; Principal components analysis; Rock; Sedimentary rocks; Soil - chemistry; Soil contaminants; Soil Pollutants - analysis; Soil Pollutants - standards; Soil types; Soils; Studies; Topography; Topsoil; Trace elements; Ultisols; Vegetation; zinc
• ISSN: 0167-6369; 1573-2959
• DOI: 10.1007/s10661-013-3462-2

Proper assessment of soil cadmium (Cd) concentrations is essential to establish legislative limits. The present study aimed to assess background Cd concentrations in soils from the state of São Paulo, Brazil, and to correlate such concentrations with several soil attributes. The topsoil samples (n = 191) were assessed for total Cd contents and for other metals using the USEPA 3051A method. The background concentration was determined according to the third quartile (75th). Principal component analysis, Spearman correlation, and multiple regressions between Cd contents and other soil attributes (pH, cation exchange capacity (CEC), clay content, sum of bases, organic matter, and total Fe, Al, Zn, and Pb levels) were performed. The mean Cd concentration of all 191 samples was 0.4 mg kg⁻¹, and the background concentration was 0.5 mg kg⁻¹. After the samples were grouped by parent material (rock origin) and soil type, the background Cd content varied, i.e., soils from igneous, metamorphic, and sedimentary rocks harbored 1.5, 0.4, and 0.2 mg kg⁻¹ of Cd, respectively. The background Cd content in Oxisols (0.8 mg kg⁻¹) was higher than in Ultisols (0.3 mg kg⁻¹). Multiple regression demonstrated that Fe was primarily attributed to the natural Cd contents in the soils (R ² = 0.79). Instead of a single Cd background concentration value representing all São Paulo soils, we propose that the concentrations should be specific for at least Oxisols and Ultisols, which are the primary soil types.