Geochemistry, Mineralogy and Microbiology of Molybdenum in Mining-Affected Environments

Abstract

Abstract:Molybdenum is an essential element for life, with growing production due to a constantly expanding variety of industrial applications. The potentially harmful effects of Mo on the environment, and on human and ecosystem health, require knowledge of Mo behavior in mining-affected environments. Mo is usually present in trace amounts in ore deposits, but mining exploitation can lead to wastes with very high Mo concentrations (up to 4000 mg/kg Mo for tailings), as well as soil, sediments and water contamination in surrounding areas. In mine wastes, molybdenum is liberated from sulfide mineral oxidation and can be sorbed onto secondary Fe(III)-minerals surfaces (jarosite, schwertmannite, ferrihydrite) at moderately acidic waters, or taken up in secondary minerals such as powellite and wulfenite at neutral to alkaline pH. To date, no Mo-metabolising bacteria have been isolated from mine wastes. However, laboratory and in-situ experiments in other types of contaminated land have suggested that several Mo-reducing and -oxidising bacteria may be involved in the cycling of Mo in and from mine wastes, with good potential for bioremediation. Overall, a general lack of data is highlighted, emphasizing the need for further research on the contamination, geochemistry, bio-availability and microbial cycling of Mo in mining-affected environments to improve environmental management and remediation actions.

Mobilization of Metal(oid) Oxyanions through Circumneutral Mine Waste-Rock Drainage

“…64−66 To prevent such detrimental environmental effects, the processes controlling oxyanion concentrations in mine drainage need to be understood. Although selected studies have investigated the occurrence, (bio)geochemical dynamics, and toxicity of As, Mo, Sb, and Se in mine wastes (e.g., for As, 22−25 Mo, 14,26,27 Sb, 28,29 and Se 30−32 ), the majority of these laboratory and field studies has focused on their behavior under acidic conditions, with relatively little attention given to neutral- or alkaline-pH waters (e.g., for As 15,33 ). Therefore, the potential sources and environmental fates of these elements in NRD systems remain poorly explored.…”

Investigation on the Sources and Impact of Trace Elements in the Annual Snowpack and the Firn in the Hansbreen (Southwest Spitsbergen)

“…This latter mineral is typical of granitoid rocks outcropping in different Arctic regions (e.g, N-Norway and E-Greenland), and only small outcrops of these rocks were found in the northernmost Svalbard (Johansson et al, 2002). In coal mining regions, however, Mo is usually present in trace amounts in ore deposits, but it can be enriched due to exploitation (Frascoli and Hudson-Edwards, 2018). Also, Mo associated with over bank deposits from Triassic rocks has low content in sediments.…”

Mo Contamination in Rivers near the Erdenet Mining Area, Mongolia: Field Evidence of High Mobility of Mo at pH >8

“…The quality of surface water is important for life on Earth . Understanding the mobility of trace elements in natural waters and the ability to predict changes in that mobility are important research topics in environmental geochemistry. , Molybdenum (Mo) is one of the transition elements that are essential for living organisms, but it is harmful in large doses. − Since the turn of the century, considerable attention has been paid to the environmental behavior of Mo in natural waters. , In 2011, the World Health Organization (WHO) established a guideline concentration of 70 μg/L for Mo in drinking water on the basis of toxicological evidence and the essential daily human requirement for Mo . The U.S. Environmental Protection Agency determined a lifetime advisory level of 40 μg/L Mo in surface water.…”

“…The samples with Mo concentrations that exceed 70 μg/L were only 0.1% of samples from U.K. rivers and were not reported in samples from rivers in India 13 and France. 14 Reviews of Mo concentrations in rivers affected by mining activities 3,4 have identified increased Mo concentrations in pore water in tailings dumps and acidic mine drainage water, 15,16 although most mining-affected river waters do not exceed the WHO guideline level, except for an area around the Climax molybdenum mine (United States) during the 1970s. 15 The Erdenet mine in Mongolia is one of the world's largest copper−molybdenum mines.…”