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Processes affecting the chemical composition of Blue Lake, an alluvial gold-mine pit lake in New Zealand


Barker, SLL and Kim, JP and Craw, D and Frew, RD and Hunter, KA, Processes affecting the chemical composition of Blue Lake, an alluvial gold-mine pit lake in New Zealand, Marine and Freshwater Research, 55 pp. 1-11. ISSN 1323-1650 (2004) [Refereed Article]

Copyright Statement

Copyright 2004 CSIRO

DOI: doi:10.1071/MF03174


Blue Lake is an abandoned, water-filled alluvial gold-mine pit in Central Otago, New Zealand. Alluvial gold mining is generally considered to be chemically benign, unless mercury is added to assist gold separation. The major element, trace metal and isotopic composition of the pit lake was compared to nearby, unaffected streams. Blue Lake was found to be enriched in the major cations, with levels that were 2–5 times higher than in unaffected streams. Furthermore, Cu, Ni and Zn concentrations exceeded 10 nmol L–1 in Blue Lake; these levels were 2–30 times higher than those in nearby, unaffected streams. Processes affecting the lake’s characteristics include evaporative concentration, and the oxidation and dissolution of locally derived sulfide and sulfate minerals. Localised acidification in surface and ground waters around the lake leads to the mobilisation of Zn and Ni, resulting in lake waters being strongly enriched in these trace metals (concentrations greater than 40 nmol L–1), whereas surrounding stream waters have much lower Ni and Zn concentrations (less than 5 nmol L–1). Ongoing evaporative concentration, and the continuing mobilisation of trace metals, implies that metal enrichment in lake waters will continue to occur. The present study demonstrated that the ‘benign’ process of alluvial gold mining can have significant chemical consequences in resulting water bodies.

Item Details

Item Type:Refereed Article
Keywords:mine pit lake, geochemistry, New Zealand, alluvial gold mine, mining impact, sulfide dissolution, trace metals
Research Division:Earth Sciences
Research Group:Atmospheric sciences
Research Field:Atmospheric composition, chemistry and processes
Objective Division:Environmental Management
Objective Group:Terrestrial systems and management
Objective Field:Evaluation, allocation, and impacts of land use
UTAS Author:Barker, SLL (Dr Shaun Barker)
ID Code:129308
Year Published:2004
Web of Science® Times Cited:12
Deposited By:CODES ARC
Deposited On:2018-11-22
Last Modified:2018-12-17

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