Metals in Low‐elevation, Southern Appalachian Forest Floor and Soil

Abstract

AbstractLitter and humus, and surficial (0–5 cm) and deeper (25–30 cm) mineral soil were collected from two, 90‐yr‐old forests to measure readily‐available, potentially‐available, and total‐pool quantities of metals in low elevation, southern Appalachian soils. Soils of the two forested watersheds are either in the Evard or Tate series, a fine‐loamy, mesic family of Typic Hapludults. Concentrations of Ca, K, Mg, Mn, Cd, Co, Cu, Pb, and Zn in soils were determined by three extraction methods (water soluble, weak acid, and total dissolution). Total soil Ca, K, Mg, and Mn pools were two or more orders of magnitude greater than trace metal pools. Total soil metal pools at both depths followed a trend of K ≫ Ca ≥ Mg > Mn ≫ Zn > Cu ≫ Pb ≥ Co ≫ Cd. Fractions of the total metal pools that were readily and potentially available generally decreased with depth.Litter and humus trace metal concentrations of two low elevation watersheds in the Coweeta Basin contain lower concentrations of Cu, Zn, and Pb than commonly reported for the northeastern USA. Aerial deposition of Cd, Co, and Pb was indicated by the surficial forest floor enrichment in those elements compared to the mineral soil. The largest trace metal pool in forest floor litter and humus was for lead, and was presumably from long‐range transport, deposition and subsequent retention on humic materials. Metals measurement in the relatively pristine organic forest floor and mineral soil at Coweeta will be useful for future evaluations of trace metal impacts on southern Appalachian forest ecosystems.