Plasma-based techniques applied to the determination of 17 elements in partitioned top soils

Abstract

An investigation was carried out to characterize top soils collected in a prototypical urban area impacted by industrial and agricultural activities. Soils of the studied zone receive also the contribution of traffic from the urban area, marine aerosols from the Atlantic Ocean and dust from the Patagonian steppe. Top soil samples were sampled and then sieved in two fractions (F1 < 37 μm, and 37 < F2 < 50 μm) for subsequent digestion using an acid mixture containing HCl, HNO3 and HF (6:2:1). Elemental determination of Al, As, Ba, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sb, Ti, V and Zn was carried out by inductively coupled plasma optical emission spectrometry (ICP OES) and/or inductively coupled plasma-mass spectrometry (ICP-MS). Accuracy tests for the entire analytical procedure were performed by means of the certified reference material NIST SRM 2711 Montana soil. Limit of detection reached varied from 0.08 μg g− 1 (Cd) to 2.4 μg g− 1 (Ba). Elemental concentrations ranged from 0.10 ± 0.01 μg g− 1 (Mo) to 14.6 ± 0.6% (Ca). Aluminum, Ca, Fe, Mg and Ti (geological elements) were found at concentrations in the percentage order. The ratios of elemental concentrations Mo/Ca, Ni/Ca and Ti/Ca were identified as chemical markers suitable for distinguishing the different soil samples by exposing the relative differences in the 4-element chemical profile. The concentrations of metals and metalloids in size-fractionated top soils reported in this study will be an important tool for future studies aimed to characterize soil resuspension and its contribution to airborne particulate matter.