Sibele Cristina Do Nascimento

During the twentieth century, inadequate management of mine waste at the Mount Lyell Copper Mine affected the ecology of the Queen–King Rivers and Macquarie Harbour, western Tasmania, Australia. Over the past two decades, the water quality of the river system has been measured semi-annually to investigate the long-term hydrochemical and environmental impacts caused by these historical mine practices and the waste associated with the Mount Lyell mine to the Queen–King Rivers. At sample sites below the confluence of Haulage Creek, the water pH was below pH 3.5, remaining below pH 5 across all sites to Macquarie Harbour. Local baseline rivers ranged from pH 4.0 to 8.4. Elemental concentrations of dissolved metals in water samples downstream of Haulage Creek were above the Australian and New Zealand Environment and Conservation Council (ANZECC) water quality guidelines. Copper, Fe, and Zn were not attenuated along the length of the river, with concentrations remaining elevated to the King River Delta. Mineralogical analyses demonstrated secondary minerals in sediments at Haulage Creek and pyrite concentrated at the King River Delta. Static tests on mining-affected sediments indicated risk of AMD and metal(loid) leaching in the river system. Since 2016, after flooding of the Prince Lyell mine, dissolved metal levels in the Queen–King Rivers have decreased; however, concentrations remain above guidelines. Almost three decades after legacy mine waste disposal ended, it still poses a long-term risk to the downstream environment, implying that without effective management of these historical mine wastes, the Queen–King Rivers will continue to be severely impacted. Graphical Abstract

During the 20th century, inadequate management of mine waste at Mount Lyell Copper Mine has affected the water quality and ecology of the Queen and King Rivers and Macquarie Harbour, Western Tasmania, Australia. Over the past two decades the water quality of the Queen–King Rivers from the mine site to Macquarie Harbour has been measured annually to investigate the hydrochemical impact of historical mine activities and wastes. This study evaluates the long-term environmental impacts caused by neglective mine waste management associated with the Mount Lyell mine to the Queen–King River systems. At all sample sites below the confluence of Haulage Creek, seepage from the historical waste at Mount Lyell was found to influence water pH, consistently measured at below pH 3.5, remaining below pH 5 across all sites to Macquarie Harbour. Local baseline rivers ranged in pH from 5.1 to 8.4 over 16 sampling seasons. Elemental concentrations of dissolved Al, Co, Cu, Fe and Zn in collected water samples immediately downstream of Haulage Creek were above ANZECC water quality guidelines . Copper, Fe and Zn were not sufficiently attenuated along the length of the river with concentrations remaining elevated to the King River Delta in Macquarie Harbour. XRD analyses demonstrated secondary minerals in sediments at Haulage Creek and pyrite highly concentrated at the King River Delta. Static tests on mining-impacted sediments indicated high risk of acid and metalliferous drainage (AMD) and metal(loid) leaching in the river system.Since 2014, when care and maintenance was initiated at Mount Lyell, dissolved metal levels in the Queen–King Rivers have decreased, however concentrations remain above ANZECC guidelines. This poses a long-term risk to the downstream environment and implies that without effective management of AMD (metallurgical recovery an option) from these historical mine wastes, the Queen–King River system will continue to be severely impacted .