Fractionation and Mobility of Copper, Lead, and Zinc in Soil Profiles in the Vicinity of a Copper Smelter

TLDR

The study examined four soil profiles near a Polish copper smelter to assess the distribution, chemical fractions, and mobility of Cu, Pb, and Zn relative to soil properties. Contamination was confined to surface horizons, with Cu, Pb, and Zn levels 7–115, 30, and 6 times higher than subsurface, respectively; metal distribution varied by soil texture, but highly contaminated soils consistently showed low residual fractions and high NH₄OAc‑extractable fractions, with mobile fractions comprising <10 % of subsurface and ~50 % of surface metals, and mobility indices positively correlated with total metal content and negatively with clay.

Abstract

ABSTRACT Four soil profiles located near a copper smelter in Poland were investigated for the distribution and chemical fractions of Cu, Pb, and Zn and their mobility in relation to soil properties. Contamination with heavy metals was primarily restricted to surface horizons and the extent of contamination was 7‐ to 115‐fold for Cu, 30‐fold for Pb, and 6‐fold for Zn as compared with subsurface horizons. In the less‐contaminated fine‐textured soil, the metals were distributed in the order: residual &gt;&gt; Fe–Mn oxides occluded &gt; organically complexed &gt; exchangeable and specifically adsorbed, while the order for sandy soils was: residual &gt; organically complexed &gt; Fe–Mn oxides occluded &gt; exchangeable and specifically adsorbed. The contaminated surface horizons of these profiles showed no consistent pattern of metal distribution. However, the common features of highly contaminated soils were very low percentage of residual fraction and the dominance of the NH 4 OAc extractable fraction. The sum of mobile metal fractions was generally &lt;10% in subsurface horizons, while in the contaminated surface horizons these fractions made up 50% of the total metal contents. Soil properties contributed more to the relative distribution of the metal fractions in the studied profiles than did the distance and direction to the source of pollution. The amounts of metal extracted by 0.01 M CaCl 2 accounted for only a small part of the same metals extracted by NH 4 OAc. The mobility indexes of metals correlated positively and significantly with the total content of metals and negatively with the clay content.