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Characterizing Zinc Speciation in Soils from a Smelter‐Affected Boreal Forest Ecosystem
Author(s) -
Hamilton Jordan G.,
Farrell Richard E.,
Chen Ning,
Feng Renfei,
Reid Joel,
Peak Derek
Publication year - 2016
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2015.03.0145
Subject(s) - environmental chemistry , soil water , genetic algorithm , zinc , ecosystem , chemistry , soil ph , environmental science , ecology , soil science , biology , organic chemistry
HudBay Minerals, Inc., has mined and/or processed Zn and Cu ore in Flin Flon, MB, Canada, since the 1930s. The boreal forest ecosystem and soil surrounding these facilities have been severely impacted by mixed metal contamination and H 2 SO 4 deposition. Zinc is one of the most prevalent smelter‐derived contaminants and has been identified as a key factor that may be limiting revegetation. Metal toxicity is related to both total concentrations and speciation; therefore, X‐ray absorption spectroscopy and X‐ray fluorescence mapping were used to characterize Zn speciation in soils throughout the most heavily contaminated areas of the landscape. Zinc speciation was linked to two distinct soil types. Group I soils consist of exposed soils in weathered positions of bedrock outcrops with Zn present primarily as franklinite, a (ZnFe 2 O 4 ) spinel mineral. Group II soils are stabilized by an invasive metal‐tolerant grass species, with Zn found as a mixture of octahedral (Fe oxides) and tetrahedral Mn oxides) adsorption complexes with a franklinite component. Soil erosion influences Zn speciation through the redistribution of Zn and soil particulates from Group I landscape positions to Group II soils. Despite Group II soils having the highest concentrations of CaCl 2 –extractable Zn, they support metal‐tolerant plant growth. The metal‐tolerant plants are probably preferentially colonizing these areas due to better soil and nutrient conditions as a result of soil deposition from upslope Group I areas. Zinc concentration and speciation appears to not influence the colonization by metal‐tolerant grasses, but the overall soil properties and erosion effects prevent the revegetation by native boreal forest species. Core Ideas Zinc was found to be a mixture of franklinite, aqueous Zn, and adsorption species. Absence or presence of an invasive grass species influences Zn speciation and concentrations. The presence of invasive grasses allows tetrahedrally coordinated Zn adsorption species. Zinc–Al hydroxy interlayer material shows the potential to reduce Zn phytotoxicity.