Global study reveals extensive impact of metal mining contamination on rivers and floodplains, suggesting need for new safeguards to address spike in demand for ‘green’ minerals

A groundbreaking study, published today in Science, has provided new insights into the extensive impact of metal mining contamination on rivers and floodplains across the world, with an estimated 23 million people believed to be affected by potentially dangerous concentrations of toxic waste.

Led by Professors Mark Macklin and Chris Thomas, Directors of the Lincoln Centre for Water and Planetary Health at the University of Lincoln, UK – working with Dr Amogh Mudbhatkal from the University’s Department of Geography – the study offers a comprehensive understanding of the environmental and health challenges associated with metal mining activities.

Using a new georeferenced global database of 185,000 metal mines compiled by the team and employing a combination of process-based modelling and empirical testing, the research assessed the global scale of metal mining contamination in river systems and its repercussions for human populations and livestock.

The study modelled contamination from all known active and inactive metal mining sites, including tailings storage facilities – used to store mine waste – and looked at potentially harmful contaminants such as lead, zinc, copper, and arsenic, which are transported downstream from mining operations, and often deposited along river channels and floodplains for extended periods.

“Our new method for predicting the dispersal of mine waste in river systems worldwide provides governments, environmental regulators, the mining industry and local communities with a tool that, for the first time, will enable them to assess the offsite and downstream impacts of mining on ecosystem and human health,” said Professor Mark Macklin, who led the multi-disciplinary, international team behind the research:

“We expect that this will make it easier to mitigate the environmental effects of historical and present mining and, most importantly, help to minimise the impacts of future mining development on communities, while also protecting food and water security.”

Released against the backdrop of growing demand for metals and minerals to feed the demands of the green energy transition, the new results highlight the widespread reach of the contamination, affecting approximately 479,200 kilometres of river channels and encompassing 164,000 square kilometres of floodplains on a global scale.

According to the findings released today, approximately 23.48 million people reside on these affected floodplains, supporting 5.72 million livestock and encompassing over 65,000 square kilometres of irrigated land. Due to a lack of available data for several countries, the team behind the study believe these numbers to be a conservative estimate.

Various pathways exist for humans to become exposed to these contaminant metals including from direct exposure through skin contact, accidental ingestion, inhalation of contaminated dust, and through the consumption of contaminated water and food grown on contaminated soils.

This poses an additional hazard to the health of urban and rural communities in low-income countries and communities dependent on these rivers and floodplains, especially in regions already burdened with water-related diseases. In industrialised nations in Western Europe, including the UK, and the United States, this contamination constitutes a major and growing constraint to water and food security, compromises vital ecosystem services, and contributes to antimicrobial resistance in the environment.

“Rapid growth in global metal mining is crucial if the world is to make the transition to green energy”, said Professor Chris Thomas who led the analysis and modelling,” Much of the estimated global contamination we have mapped is a legacy from the industrial era – rightly, modern mining is being encouraged to prioritise environmental sustainability. Our methods, which also work at local scales, add an important new approach in this process for which have set up an applied unit of our research centre ‘Water and Planetary Health Analytics’ to work with the sector.”

Professor Deanna Kemp from the University of Queensland’s Sustainable Minerals Institute, who was part of the team behind the study, called the results “sobering.”

“At a basic level, these findings remind us that mining can cause extensive downstream damage over long periods of time,” Kemp said. “Many people benefit from mining and metals, but we must do more to understand and prevent the negative effects on people who live and work in affected areas.”

ENDS

Notes to Editors:

For media enquiries, including interview requests, please contact Callum Thomas in the University of Lincoln Press Office on 01522 835746 or at [email protected].

More information, including a copy of the paper, can be found online at the Science press package at https://www.eurekalert.org/press/scipak/. Full study title: Impacts of metal mining on river systems: a global assessment

Additional quotes:
Professor Paul Brewer from Aberystwyth University commented: “These very significant findings demonstrate the scale of the threat posed to people, ecosystems, and the wider environment from metal mining activity across the world.  For the first time, we have been able to establish that the number of people exposed to contaminant metals sourced from the long-term discharge of mining waste into rivers is almost 50 times greater than the number directly affected by acute tailings dam failures. The new modelling approach used in this study provides industry and regulatory agencies with a tool for assessing the potential downstream impacts of metal mining activity on human populations and the environment. This will benefit future generations as we will be able to develop better, data-informed strategies for identifying and managing land contaminated by metal mining.”

The full list of contributing Institutions:

• Lincoln Centre for Water and Planetary Health, University of Lincoln, Lincoln, UK.
• Innovative River Solutions, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand.
• Centre for the Study of the Inland, La Trobe University, Melbourne, Australia.
• University of Namibia, Windhoek, Namibia.
• Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, Ceredigion, UK.
• Environment & Sustainability Institute and Camborne School of Mines, University of Exeter, Penryn, Cornwall, UK.
• Institute for Environmental Studies, Vrije Universiteit Amsterdam, Amsterdam, Netherlands.
• Department of Inland Water Systems, Deltares, Delft, Netherlands Institute for Environmental Studies, Vrije Universiteit Amsterdam, Amsterdam, Netherlands.
• Monash University Indonesia, Jakarta, Indonesia.
• Centre for Development Support, University of the Free State, Bloemfontein, South Africa.
• School of Natural Sciences, Bangor University, Bangor, Gwynedd, UK.
• Centre for Social Responsibility in Mining, Sustainable Minerals Institute, The University of Queensland, St Lucia, Australia.
• Ministry of Earth Sciences, Government of India, New Delhi, India.

About the University of Lincoln, UK:

The University of Lincoln is proud of its reputation for putting students at the heart of everything it does. We are rated in the top 40 UK universities for student satisfaction in the Guardian University Guide 2024 and in the top 50 UK universities overall in the Complete University Guide 2024. We hold a top five-star score in the QS Stars ratings system of global universities and are placed among the world’s top 150 young universities in The Times Higher Education Young University Rankings 2023. Almost £400 million has been invested in our spectacular waterfront Brayford Pool Campus in the heart of Lincoln, providing a modern, student-centred environment for students from more than 100 nations. The University of Lincoln is known for a pioneering approach to working with employers and our unique relationships with companies such as Siemens Energy and the Lincolnshire Co-op demonstrate our innovative industry-engaged approach, which has been acknowledged through a series of national awards over the past decade. Through our research, we are striving to change society for the better. Working with regional, national, and international partners, our academics are engaged in ground-breaking studies that are challenging the status quo and making a tangible difference to the world around us. More than three quarters of our research was judged to be internationally excellent or world leading in the Research Excellence Framework 2021.