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Zinc And Cadmium Distribution And Leaching In A Metalliferous Peat

Authors
  • McBride, Murray B.1
  • Barrett, Katherine A.1
  • Martinez, C. Enid2
  • 1 Cornell University, Department of Crop and Soil Sciences, Ithaca, NY, 14853, US , Ithaca
  • 2 Penn State University, Department of Crop and Soil Sciences, University Park, Pennsylvania, PA, 16802, US , Pennsylvania
Type
Published Article
Journal
Water Air & Soil Pollution
Publisher
Springer-Verlag
Publication Date
Dec 17, 2005
Volume
171
Issue
1-4
Pages
67–80
Identifiers
DOI: 10.1007/s11270-005-9013-x
Source
Springer Nature
Keywords
License
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Abstract

Peat soils with a gradient of naturally high Cd and Zn (up to 190 and 70,000,mg/kg, respectively) were sampled at several depths from a wetland overlying Zn-rich dolomitic bedrock. Total concentrations of Zn, Cd and S were generally much higher in the seasonally water-saturated subsoils than at the surface. Leaching studies with intact soil columns showed the subsoils generally have a greater tendency to release Zn, Cd and S than the topsoils. Zn and Cd leaching were correlated to sulfate dissolution, with 6 successive leaching events removing up to 4% and 13% of the total Zn and S, respectively, from the most metal-rich subsoils. Relative leaching losses were less from the surface soils, not exceeding 1% and 3% of total Zn and S. Because Zn was relatively more soluble and extractable by 0.01,M CaCl2 than Cd, Zn/Cd ratios in column leachates and field-sampled groundwater were higher than the soil Zn/Cd ratios. Consequently, the potential for loss of Zn from the soil by leaching was higher than that of Cd, particularly from the subsoil. Nevertheless, some soil layers of the profile were enriched in total Zn relative to Cd, indicated by Zn/Cd ratios well above that of the Cd-rich sphalerite in the parent dolomitic rock. This enrichment may be explained by historical migration and re-immobilization of Zn as sulfides. The low solubility of Cd in the peats despite high total Cd suggests preferential immobilization of this metal by organic sulfur or sulfide.

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