KESS 2 researcher’s prize for work on cutting river pollution from disused mines

Aaron Todd Receives First Prize

Swansea University KESS 2 researcher Aaron Todd has been awarded first prize at a prestigious international conference for his research on tackling river pollution from disused mines. Based at the Department of Geography in Swansea University, Aaron is carrying out a PhD on quantifying river pollution and has utilised salt dilution flow gauging; a technique for quickly and easily estimating the flow of a small stream. He has been conducting his fieldwork at Nant y Mwyn lead mine in Carmarthenshire, which was abandoned in 1932.

Wales has over 1,300 abandoned metal mines, all of which impact upon the environment to some degree. Aaron’s research helps monitor pollution from the mine flowing into the Towy river and estuary. Nant y Mwyn is a particularly dramatic example, polluting almost the whole length of the Towy with zinc to a level above the EU Water Framework Directive chemical standards. Treatment of these sites can only happen if the routes and processes of pollutant transfer can be mapped and understood.

Aaron Todd collecting river samples

He recently presented his research to experts at the International Mine Water Association Conference in New Zealand and was awarded first prize, which came with a £1500 bursary. Aaron also gave a second presentation on behalf of his fellow KESS 2 PhD researcher, Stuart Cairns.

Aaron explained:

“I’ve used a variety of methods to assess the flows of water and resultant pollution across the Nant y Mwyn site, including salt dilution flow gauging, which I recently used and taught in the Philippines. I also use synoptic sampling and tracer injection, which, while reasonably common in the US, remains fairly rare in the UK.

Stuart Cairns has been researching the use of biochar – pyrolyzed biomass – to remove contaminants from a variety of impacted waters, such as motorway run off. He and I trialled its use at two metal mines: first at Nant y Mwyn and subsequently at Parys Mountain in Anglesey, which is what I spoke about at the conference. We found that the biochar can remove over 90% of the metals of concern in just a minute, which is a very promising result.

KESS 2 enabled me to attend this international conference as the scholarship’s travel budget covered my flights, hotel, and conference fees.”

Pete Stanley, Abandoned Mines Senior Specialist Advisor at Natural Resources Wales, which part-sponsors Aaron’s research, said:

“Aaron’s research at Nant y Mwyn has helped bring greater clarity on the polluting pressures present. This has enabled flow gauging stations to be installed at key point sources which, when combined with wider diffuse sources, steers ongoing feasibility and design of staged anti-pollution intervention works.

Nant y Mwyn has become a key site within the Metal Mine Programme as it is the principal polluting mine on the Afon Tywi. Work here will improve a longer length of river   than at any other Welsh mine.”

Knowledge Economy Skills Scholarships (KESS 2) is a pan-Wales higher level skills initiative led by Bangor University on behalf of the HE sector in Wales. It is part funded by the Welsh Government’s European Social Fund (ESF) convergence programme for West Wales and the Valleys.


Using Tracer Injection and Synoptic Sampling, and Salt Dilution Flow to Gauge Metal Fluxes in a Temperate Watershed in the UK. Todd, Aaron Martin Lawrence; Robertson, Iain; Walsh, Rory P.D.; Byrne, Patrick; Edwards, Paul; Williams, Tom (2022): [direct link]

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