The environmental and geomorphological impacts of historical gold mining in the Ohinemuri and Waihou river catchments, Coromandel, New Zealand

0506313 - ÚACH 2020 RIV NL eng J - Článek v odborném periodiku
Clement, A. J. H. - Nováková, Tereza - Hudson-Edwards, K. A. - Fuller, I. C. - Macklin, M. G. - Fox, E. G. - Zapico, I.
The environmental and geomorphological impacts of historical gold mining in the Ohinemuri and Waihou river catchments, Coromandel, New Zealand.
Geomorphology. Roč. 295, OCT (2017), s. 159-175. ISSN 0169-555X. E-ISSN 1872-695X
Institucionální podpora: RVO:61388980
Klíčová slova: Mining-contaminated river * Floodplain sedimentation * Mine tailing discharge * Historical gold mining * Ohinemuri River * Waihou River
Obor OECD: Environmental sciences (social aspects to be 5.7)
Impakt faktor: 3.308, rok: 2017
Způsob publikování: Open access

Between 1875 and 1955 approximately 250,000 Mg yr(-1) of mercury-, arsenic-, and cyanide-contaminated mine tailings were discharged directly into the Ohinemuri River and its tributaries, in the Coromandel Region, North Island, New Zealand. A devastating flood on 14 January 1907 deposited large amounts of mine waste across the floodplain of the Ohinemuri and Waihou rivers in the vicinity of the township of Paeroa. The 1907 mine-waste flood deposit was located as a dirty yellow silt in cores and floodplain profiles, with a thickness ranging from 0.15-0.50 m. Geochemical analysis of the mine waste shows.elevated concentrations of Pb (similar to 200-570 mg kg(-1)) and As (similar to 30-80 mg kg(-1)), compared to early Holocene background concentrations (Pb < 30 mg kg(-1), As < 17 mg kg(-1)). Bulk sediment samples recovered from the river channel and overbank deposits also show elevated concentrations of Pb (similar to 110 mg kg(-1)), Zn (similar to 140-320 mg kg(-1)), Ag (similar to 3 mg kg(-1)), and Hg (similar to 0.4 mg kg(-1)). Using the mine-waste deposit as a chronological marker shows that sedimentation rates increased from similar to 0.2 mm yr(-1) in the early Holocene, to 5.5-26.8 mm yr(-1) following the 1907 flood. Downstream trends in the thickness of the flood deposit show that local-scale geomorphic factors are a significant influence on the deposition of mine waste in such events. Storage of mine waste is greatest in the upstream reaches of the floodplain. The volume of mine waste estimated to be stored in the Ohinemuri flood plain is similar to 1.13 M m(3), an order of magnitude larger than recent well-publicised tailings-dam failures, such as the 1996 South America Porco, 2000 Romanian Baia Mare and Baia Borsa accidents, and constituted, and was recognised at the time, a significant geomorphological and environmental event. The mine-waste material remains in the floodplain today, representing a sizable legacy store of contaminant metals and metalloids that pose a long-term risk to the Ohinemuri and Waihou ecosystems.
Trvalý link: http://hdl.handle.net/11104/0297592