Feasibility of pXRF to evaluate chosen heavy metals in soil highly influenced by municipal waste disposal—A monitoring study of a former sewage farm

Abstract

Sewage disposal onto agricultural land may result in the high accumulation of organic wastes, which questions the applicability of typical elemental analysis used for the soil components. To monitor the contamination status of agricultural soils at a former sedimentation basin, after the long‐term cessation of wastewater irrigation, 110 locations (15–20 cm depth) and 4 boreholes (up to 100 cm depth) were sampled to determine pH, loss on ignition, and concentration of Ni, Cu, Pb, Zn, and Cr. Additionally, the applicability of portable X‐ray fluorescence (pXRF) for the soil samples highly influenced by the organic wastes was evaluated. The study revealed the presence of a relatively homogenous sewage waste layer (depth of 20 cm), characterized by slightly acidic to neutral pH (6.3–7.5), high organic matter (OM) accumulation (up to 49%), and elevated concentration (mg kg −1) ranges between: Pb (5–321), Cu (31–2828), Ni (10–193), Cr (14–966), and Zn (76–6639). The pXRF analysis revealed metal concentration increase in mineral samples (up to 50%). The regression models and correction factors demonstrated high correlation and significance of pXRF measurement with response to increasing OM content, with the lowest r 2 = 0.86 obtained for Ni. Correlation of pXRF and AES measurement illustrated element‐dependent response for soils high in organics. Zn, Cu, and Cr pXRF analysis led to a slight underestimation in lower values, but overall good correlations (0.87; 0.89; and 0.88 respectively). Pb and Ni pXRF measurement revealed higher deviation from the reference in both lower and higher concentrations (0.74 and 0.70, respectively).

Portable X-ray Fluorescence Analysis of Organic Amendments: A Review

“…The basic search in SCOPUS provided 23 records of which only 13 papers [28][29][30][31][32][33][34][35][36][37][38][39][40] deals with organic amendments. The other papers focused on soils or archaeological studies and were discarded.…”

“…In a recent study, Sut-Lohmann et al [38] compared the feasibility of common laboratory methods (microwave plasma-AES and pXRF) to evaluate element concentrations in soil highly influenced by sewage waste. The lowest correlation between both methods was obtained for Ni (R 2 = 0.70, stronger points scattering), although the correlations were satisfactory for the other elements (Pb, Cu, Zn and Cr).…”

“…This same sample calcination strategy was already used by Vodyanitskii et al [52] to measure the metals Ba, Sr, V, Cr, Ni, Cu, Zn, Zr, Pb, Y, La, and Ce, although in this case, a nonportable laboratory instrument was used. Sut-Lohmann et al [38] found that OM removal in the soil sample influences its density and effective volume, which interferes with pXRF elemental analysis. However, if the data were corrected for organic matter, the influence of the matrix on the pXRF measurements was reduced.…”