Trace Metal Geochemistry in Spodosols of the Northeastern United States

Long‐term or postglacial (≈ 12 000‐year) net fluxes of Pb, Cu, Zn, Ni, Cr, and Co through three Spodosols, formed from different parent materials, were calculated using mass‐balance modeling. Metal contents in vegetation and O horizons were also estimated and measured, respectively. Total metal contents in mineral horizons were fractionated into different operationally defined pedogenic phases using a sequential extraction technique. With few exceptions, the three soils had significant leaching losses for all trace metals (from 7–508 kg ha−1), the greatest losses generally occurring in the E and upper horizons. The magnitude of losses by leaching varied with parent material, as a result of differences in weatherabilities of mineral suites. Combined metal contents in vegetation and O horizons, which may originate from anthropogenic additions as well as mineral weathering, are significantly large in some cases; however, these metal amounts are apparently not large enough to offset long‐term leaching losses from the underlying mineral soil profiles. Some B and C horizons had net accumulations of extractable Pb, Cu, and/or Ni‐bearing phases. Based on the sequential extraction procedure used, the extractable metal forms are probably pedogenic Fe oxide‐ and/or organic‐bound phases. One soil apparently gained Cu (≈38 kg ha−1), which may have been from atmospheric deposition.