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

2004 ◽  
Vol 55 (2) ◽  
pp. 201 ◽  
Author(s):  
Shaun L. L. Barker ◽  
Jonathan P. Kim ◽  
Dave Craw ◽  
Russell D. Frew ◽  
Keith A. Hunter
Keyword(s):  
New Zealand ◽  
Trace Metals ◽  
Gold Mining ◽  
Gold Mine ◽  
Pit Lake ◽  
Evaporative Concentration ◽  
Blue Lake ◽  
Alluvial Gold ◽  
Mine Pit Lake ◽  
Lake Waters

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.

scholarly journals Speciation and Spatial Distribution of Trace Metals in Sediments Around Gold Mining Areas in Northern Côte D’Ivoire

2021 ◽  
Author(s):  
Koffi Pierre Dit Adama N'GORAN ◽  
Donourou Diabaté ◽  
N’Guessan Louis Berenger Kouassi ◽  
Koffi Marcellin Yao ◽  
Kakou Charles Kinimo ◽  
...  
Keyword(s):  
Cluster Analysis ◽  
Spatial Distribution ◽  
Trace Metals ◽  
Enrichment Factor ◽  
Hierarchical Cluster Analysis ◽  
Gold Mining ◽  
Principal Component ◽  
Hierarchical Cluster ◽  
Gold Mine ◽  
Ecological Risks

Abstract The purpose of this study was to investigate the spatial distribution, possible sources, and potential ecological risks associated with traces metals Cu, Mn and Ni in sediments around gold mine areas in northern Côte d’Ivoire. The sampling was conducted in industrial and artisanal and small-scale gold mining sites in Korhogo and Tengrela. Analysis of variance was performed to ascertain spatial differences. The possible sources of pollution were identified using the enrichment factor, principal component, and hierarchical cluster analysis. Trace metals Cu, Ni and Mn concentrations in sediments did not vary across the stations. The same spatial mapping distribution trend was observed for Ni, while those of Cu and Mn differed among the stations. The geoaccumulation index indicated low to moderate contamination of Cu, Mn and Ni at Korhogo and Tengrela. The results of principal component and hierarchical cluster analysis indicated that Cu, Ni, and Mn were generated both by anthropogenic and natural inputs, which were confirmed by the enrichment factor. The potential ecological risks indicated that Cu, Mn and Ni could pose low risk to organisms at Korhogo and Tengrela. This study provides first trace metals data in sediments across Korhogo and Tengrela gold mine areas. The sequential extraction procedure proposed by the Community Bureau of Reference (BCR) showed that a major portion (between 59.68 to 79.22 %) of Cu, Ni and Mn is highly associated with the residual fraction, showing their low mobility.

Mercury in soils impacted by alluvial gold mining in the Peruvian Amazon

2021 ◽  
Vol 288 ◽  
pp. 112364
Author(s):  
Manuel Gabriel Velásquez Ramírez ◽  
Claudia Maribel Vega Ruiz ◽  
Ronald Corvera Gomringer ◽  
Martin Pillaca ◽  
Evert Thomas ◽  
...  
Keyword(s):  
Gold Mining ◽  
Peruvian Amazon ◽  
Alluvial Gold

scholarly journals GEOCHEMICAL ASSESSMENT OF TRACE METALS IN SOIL, STREAM WATER AND SELECTED FOOD CROPS AT KIBI GOLDFIELDS ENVIRONMENT, GHANA

2020 ◽  
Vol 4 (1) ◽  
pp. 71-76
Author(s):  
Douglas Baah Siaw ◽  
Solomon S.R. Gidigasu ◽  
Anthony Andrews ◽  
Emmanuel Gikunoo ◽  
Gordon Foli
Keyword(s):  
Trace Metals ◽  
Stream Water ◽  
Control Site ◽  
Food Crops ◽  
Eastern Region ◽  
Conservative Tracer ◽  
Guideline Values ◽  
Alluvial Gold ◽  
Translocation Factors ◽  
Impacted Site

This study assesses environmental receptors impacted by alluvial gold mining at Kibi Goldfields Limited in the Eastern region of Ghana to establish trace metals contamination risk. Specific objectives are to determine concentrations of (1) As, Cr, Ni and Pb in soils, drainage and food crops, using X-ray fluorescence, (2) Cl- in drainage using standard methods. Mean concentrations of As, Cr and Ni in soils are higher at impacted sites than control sites; while Pb and As concentrations in drainage exceeds the maximum contamination guideline values in drinking water. Using Cl- as a conservative tracer, As and Pb are adsorbing from water, while Cr and Ni are desorbing into water. In the food crops, bioaccumulation factors of As and Ni are profound at the impacted site than control sites; Except Cr in cocoyam at impacted sites, translocation factors are negligible in the food crops. Cr bioaccumulates in in cocoyam and plantain at the control site, while Ni bioaccumulates in only plantain at the impacted sites. Overall, the metal contamination is of concern in the receptors, except Pd in plants. Results from this study can be used for trace metals risk assessment in the environment.

Lead, zinc and arsenic contamination of pit lake waters in the Zeida abandoned mine (High Moulouya, Morocco)

2021 ◽  
pp. geochem2021-009
Author(s):  
Lamiae EL ALAOUI ◽  
Abdelilah Dekayir ◽  
Mohammed Rouai ◽  
EL Mehdi Benyassine
Keyword(s):  
Organic Matter ◽  
Iron Oxides ◽  
Environmental Issues ◽  
Abandoned Mine ◽  
Equal Proportion ◽  
Pit Lake ◽  
Content Type ◽  
Link Type ◽  
Supplementary Material ◽  
Lake Waters

In the Zeida abandoned mine, pit lake waters exhibit alkaline pH and high conductivity. The concentrations of the total dissolved lead and zinc are very low due to their adsorption on clay minerals and iron oxyhydroxides. Conversely, arsenic concentrations in two lakes (ZL1 and ZA) exceeded WHO water quality guidelines. The As content is relatively high in ZL1 lake and exists mainly as As(V). In ZA lake, As(III) occurs in low concentration compared to the total dissolved arsenic, while dimethylarsenic acid [H2AsO2(CH3)2, DMA) prevails. This means that arsenic was methylated by organic matter produced by microorganisms such as chlorella. The sequential extraction of floor sediments in two lakes shows that the bioavailable arsenic contents change between the two lakes. In ZA lake, the sediments show high concentrations of lead and arsenic compared to ZL1 sediment since it is surrounded by mining waste tailings, which are rich in such chemical elements. An arsenic leaching test of ZA sediment shows that bioavailable arsenic is distributed in equal proportion between clay/carbonates, sulfide-organic matter, and iron oxides (HFO) phases, while in ZL1, most of the arsenic is linked to hydrous iron oxides (HFO).Thematic collection: This article is part of the Hydrochemistry related to exploration and environmental issues collection available at: https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issuesSupplementary material:https://doi.org/10.6084/m9.figshare.c.5545316

scholarly journals Anthropogenic Vegetation in the River Valley Amalat

2019 ◽  
Vol 16 ◽  
pp. 00049
Author(s):  
Marina Tsyrenova ◽  
Evgenia Pyzhikova ◽  
Elena Vasilyeva
Keyword(s):  
Vegetation Cover ◽  
Gold Mining ◽  
Research Study ◽  
Gold Deposits ◽  
Open Pit ◽  
Current State ◽  
Disturbed Areas ◽  
Alluvial Gold ◽  
Anthropogenic Vegetation ◽  
Mining Methods

The article presents the results of a research study of anthropogenic affects of gold mining on forest landscapes in Northern Transbaikalia, Russia and processes of natural reclamation of vegetation cover of the disturbed areas. The study area is located northwest of the Maliy Amalat River, which flows along the Vitim Plateau; in the floodplains of its two tributaries the Aunik River and the Bagdarin River. It is an area where a large number of alluvial gold deposits have been discovered. Some of these deposits are currently being developed, some have already been explored, and some have been abandoned. The authors consider the current state of vegetation cover in a key area of the Amalat River basin, near villages of Malovsky and Bagdarin. The problem of natural resources development and conservation is becoming extremely important for the area under study because open-pit gold mining methods that are used here drastically change the environment and affect water, land and forest resources.

scholarly journals Mobilisation and Bioavailability of Arsenic Around Mesothermal Gold Deposits in a Semiarid Environment, Otago, New Zealand

2002 ◽  
Vol 2 ◽  
pp. 308-319 ◽  
Author(s):  
D. Craw ◽  
L. Pacheco
Keyword(s):  
New Zealand ◽  
Vadose Zone ◽  
Surface Waters ◽  
Gold Deposits ◽  
Processing Plant ◽  
Geological Time ◽  
Iron Oxyhydroxides ◽  
Mine Waters ◽  
Evaporative Concentration ◽  
Fe Oxyhydroxides

Arsenopyrite (FeAsS) is the principal arsenic (As) mineral in mineralised mesothermal veins (typically 5,000 mg/kg As) in southeastern New Zealand. Groundwater in contact with arsenopyrite-bearing rocks has elevated As concentrations (up to 0.1 mg/l). The arsenopyrite decomposes slowly on oxidation in soils and historic mine workings in a cool semiarid climate. Dissolved As is predominantly As(III) in association with arsenopyrite, but this is rapidly oxidised over days to weeks to As(V) in the vadose zone. Oxidation is facilitated by particulate Fe and/or Mn oxyhydroxides, and by bacteria in surface waters. Evaporative concentration of dissolved As(V) in the vadose zone causes precipitation of scorodite (Fe(III)As(V)O4.2H2O). Adsorption of As(V) to Fe oxyhydroxides in soils and groundwater pathways lowers dissolved As concentrations. Soils over mineralised veins typically have <200 mg/kg As, as most As is removed in solution on geological time scales. Most plants on the mineralised rocks and soils do not take up As, although some inedible species can fix up to 18 mg/kg As. Hence, bioavailability of As(V) is low in this environment, despite the substantial As flux.Similar As mobility is seen in an active gold mine processing plant and tailings. Arsenopyrite dissolves more rapidly on agitation, and mine waters can have dissolved As >200 mg/l, predominantly as As(V). This dissolved As decreases in tailings waters to near 2 mg/l, mainly as As(III) when in contact with arsenopyrite. Weak oxidation of evaporatively dried tailings causes cementation with scorodite and iron oxyhydroxides, and scorodite precipitation exerts some control on dissolved As(V) concentrations. High dissolved As in mine waters is lowered by adsorption to iron oxyhydroxides, and waters discharged from the mine site have negligible dissolved As.

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