Factors Influencing Heavy Metal Distribution in Six Oklahoma Benchmark Soils

Abstract

Six contrasting benchmark Oklahoma soils underlain by sedimentary rock were selected and sampled by horizon to parent material or a 2‐m depth. Total Co, Cu, Ni, Pb, and Zn concentrations by horizon in total soil and clay fractions were determined by x‐ray fluorescence. Total concentration of heavy metals in these soils is dependent on clay content. There are fivefold more Cu, twofold more Zn and Ni, and 1.5‐fold more Co and Pb in the clay fraction than in the total soil. The clay fraction of surface horizons contains a greater concentration of Cu, Zn, and Co than subsoil horizons due to biogeochemical cycling of these micronutrients from the subsoil to the surface during melanization. Biogeochemical cycling reduces the total amount of heavy metal loss from surface to subsoil horizons by clay translocation but doesn't offset the illuviation of total heavy metals sorbed to clay. Higher levels of total heavy metals in each profile for each element are found in the B horizons than the A horizons (77% of the samples). Characterization of soil for total heavy metal content should include a sample from the B horizon especially in soil with higher clay content in the B than the A horizon. Soil parent material discontinuities cause changes in concentration of several heavy metals within two of the six soil profiles. Identification of soil parent material discontinuities is not a consistent factor causing change in heavy metal concentration within the soils studied.

A comparison of the rhizosphere-based method with DTPA, EDTA, CaCl2, and NaNO3 extraction methods for prediction of bioavailability of metals in soil to barley

“…The comparison using simple correlation analysis demonstrated that the rhizosphere-based method was better than other single extraction methods for the evaluation of bioavailability of Cr, Cu, Zn, and Cd in soils to barley roots (Table 3), although it failed to assess the bioavailability of Ni and Pb because Ni and Pb are non-essential elements to plants (Lee et al, 1997). The research of Pitchel et al (1999) also suggested that none of the extractants reflected the uptake of Ni into the plants.…”

Contents and main fractions of trace elements in Typic Argiudolls of the Argentinean Pampas

“…The bioavailable forms are related to several properties and reactions within the soils (Fergusson, 1991;Lee et al, 1997) and chemical extractants developed to represent plant absorption, may extract trace elements from several fractions (Tack and Verloo, 1995). Among the tested extractants, DTPA is one of the commonest (Fergusson, 1991;Tack and Verloo, 1995), although its effectiveness varies with different trace elements (Pais and Jones, 1997).…”

Assessment of Physicochemical Properties and Heavy Metals Contents in Selected Dumpsites in Afikpo, Afikpo North, Ebonyi State, Nigeria

“…Some of the components are biodegradable while others are not. Soil is a natural reservoir of metals whose concentrations are associated with several factors such as biological and biogechemical cycling, parent material and mineralogy, soil age, organic matter, soil pH, redox concentrations and microbial activities (Greenland and Hayes, 2000;Lee et al, 1997;Ma et al, 1997). Report has shown that the decomposition or oxidation of waste releases additional heavy metals into the surrounding soil and groundwater (Obasi et al, 2015(Obasi et al, :2013(Obasi et al, :2012Agiratas et al, 1999, Nupe et al, 2008Uba et al, 2008;Elaigwu et al, 2007).…”