Using isotopic dilution to assess chemical extraction of labile Ni, Cu, Zn, Cd and Pb in soils

Abstract

Highlights: Stable isotope dilution can inform underlying mechanisms during chemical extraction

The labile fractions of metals and arsenic in mining‐impacted soils are explained by soil properties and metal source characteristics

“…The element lability in contaminated soils and mining wastes is a more relevant indicator for environmental risk than total concentrations (Hamon et al, 2008). The median %E values of Cu, Zn, and Cd for the soil samples were 10-20% lower than the median of previously reported values for Cu (17%, n = 87), Zn (23%, n = 101), and Cd (30%, n = 105) obtained using the same protocol (Buekers et al, 2007;Garforth et al, 2016;Hamon et al, 2008;Marzouk et al, 2013b). Labile fractions of Ni and Pb were very comparable with the same set of reported values.…”

“…A main reason for the discrepancies is the type of sampled analyzed, as T A B L E 3 Significant (p < .01) linear regression parameters (m 1 to m 4, Equation 4) from stepwise multivariate analysis of labile fractions (%E) of Ni, Cu, Zn, Cd, Pb, and As as a function of soil chemical properties and contamination source attributes Mao et al (2017). in the case of Buekers et al (2007), where high fractions of labile Cu and Cd correspond to control-uncontaminated soils. When field-contaminated soils are analyzed (as in Garforth et al (2016) and Marzouk et al (2013b), the discrepancies are more related to soil chemical properties (mainly to lower pH values and oxalate-extractable Fe contents compared with the values of the present work). Median As %E values are in good agreement with the median of reported values in contaminated soils (8.2; n = 27) determined with similar protocols (De Brouwere et al, 2004).…”

“…When field‐contaminated soils are analyzed (as in Garforth et al. (2016) and Marzouk et al. (2013b), the discrepancies are more related to soil chemical properties (mainly to lower pH values and oxalate‐extractable Fe contents compared with the values of the present work).…”

“…Isotopic dilution (ID) is well recognized as a reference method to determine metal and metalloid E‐values in soils using either radioactive or stable isotopes, the latter allowing multi‐element determination in single‐step extractions (Garforth, Bailey, Tye, Young, & Lofts, 2016). In contrast to other labile metals’ single extractions, ID is robust across different types of electrolytes, solid/liquid ratios, pre‐equilibration times, and separation methods, and it is measured at native soil pH and ionic strength with minimum solid phase disturbance (Hamon, Parker, & Lombi, 2008; Young et al., 2006).…”

Toxicity threshold of lead (Pb) to nitrifying microorganisms in soils determined by substrate-induced nitrification assay and prediction model

“…Some authors have reported that Pb fixation by soil organic matter is an important factor associated with accumulation of Pb in soils with higher organic matter content (Li et al 1996;Garforth et al 2016). Soils that have high organic matter content may fix or immobilize Pb in the upper horizon, reducing its bioavailability and thus reducing its toxicity to organisms.…”