Porewater Evidence of Metal (Cu, Ni, Co, Zn, Cd) Mobilization in an Acidic, Ombrotrophic Bog Impacted by a Smelter, Harjavalta, Finland and Comparison with Reference Sites

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• 作者：Nicole Rausch ; Liisa Ukonmaanaho ; Tiina M. Nieminen ; Michael Krachler ; and William Shotyk
• 刊名：Environmental Science & Technology
• 出版年：2005
• 出版时间：November 1, 2005
• 年：2005
• 卷：39
• 期：21
• 页码：8207 - 8213
• 全文大小：221K
• 年卷期：v.39,no.21(November 1, 2005)
• ISSN：1520-5851

文摘

Porewaters were collected from three Finnish peat bogssubjected to varying inputs of atmospheric trace metals:Hietajärvi (HIJ), a low-background site, Outokumpu (OUT),near a Cu-Ni mine, and Harjavalta (HAR), near a Cu-Nismelter. Samples for metal analyses were collected at depthsranging from 10 to 70 cm using a purpose-built syringe-type sampler. Metal concentrations were determined usinginductively coupled plasma-sector field-mass spectrometry(ICP-SF-MS). Porewater concentrations at HIJ and OUT(Cd <0.3 nM, Co <1.4 nM, Cu, Ni <8 nM, Zn <250 nM) areindependent of metal concentrations in the solid phase(peat). At OUT there is a limited release of Ni to the porewaters,but concentrations in the aqueous phase are generallybelow 0.3% of the total concentration in any given peatsample. These data are consistent with the immobility ofthese metals after deposition from the air. In contrast,porewaters at HAR are enriched in trace metals comparedto the other sites by a factor of 2 (Zn), 10 (Cd), 20 (Co),and 100 (Cu and Ni) with dissolved fractions of Cu and Niaccounting for ca. 20% of the metal inventories in thecores. The elevated release of metals from solid phasesat HAR is consistent with the postdepositional migration ofmetals at this site and reflects the predominance ofoxide phases supplied to the bog surface and the muchlower pH values (<3.4). The elevated proton concentrationsnot only promote mineral dissolution but also competewith cation exchange processes and hinder the formationof metal complexes with organic ligands.