Spatial distribution of Pb and Zn in soils under native vegetation in Southeast Brazil

In this study, we aim to determine semi-total or natural and available concentrations of Pb and Zn in topsoils (0 –20 cm depth) from 337 samples under native vegetation in the State of Minas Gerais, Brazil. Additionally, we sought to interpret the spatial geochemical variability using geostatistical techniques and quality reference values for these elements in soils were established. The semi-total concentrat ions were determined by flame and graphite furnace atomic absorption after microwave-assisted nitric acid digestion method. The available concentrations were extracted using the Mehlich-I extractor and determined by atomic absorption spectrometer. Spatial variability was modeled using semivariance e stimators: Matheron’s classic, Cressie and Hawkins’ robust, and Cressie median estimators, the last two being less sensitive to extreme values. This allowed the construction of digital maps through kriging of semi-total Pb and Zn contents using the median estimator, as well as other soil propert ies by the robust estimator. The dominance of acidic pH and low CEC values reflects highly weathered low-fertility soils. Semi-total Pb contents ranged from 2.1 to 278 mg kg−1 (median: 9.35 mg kg−1) whereas semi-total Zn contents ranged from 2.7 to 495 mg kg−1 (median: 7.7 mg kg−1). The available Pb contents ranged from 0.1 to 6.92 mg kg−1 (median: 0.54 mg kg−1) whereas available Zn contents ranged from 0.1 to 78.2 mg kg−1 (median: 0.32 mg kg−1). The highest Pb a...
Source: Environmental Geochemistry and Health - Category: Environmental Health Source Type: research