Mine water discharges and invertebrate testing

Rachel from the University of Hull joined us recently to perform a series of test on mine water discharges and their impact on aquatic life.

You may have noticed orange-stained water around the local area, this ‘ochre’ is caused by dissolved iron from the mines being oxidised when it meets the outside air and becoming a solid. Whilst not toxic to humans, it looks unsightly and reduces the number and diversity of invertebrates in the stream, also coating gravel which reduces spawning opportunities for fish.

An Ultrameter II was used to take readings at the source and also downstream of the discharges, these measurements included temperature, pH, conductivity, total dissolved solids and oxidation reduction potential. Flow is also measured so the rate at which water is leaving the mine is known.

Invertebrate sampling starts by agitating the stream-bed to dislodge any creatures present and catch them in a net.

After removing the large rocks and debris, the invertebrates are filtered out.

Then taken back to the laboratory for a detailed analysis of numbers and species found, and what that indicate about water quality.

We found that where mine-water remediation such as settling ponds and reed-beds already existed, water looked clear and wildlife could be found just a short distance away from the source of the discharges, for example leeches, frogs and fish.

Whilst there were many encouraging signs, we did also visit some sites where no remediation currently takes place and the discoloured water flows straight into the beck, a recommendation of this project will be that something is done about these discharges.

If you’re aware of any other places in the local area where this happens, we would love to hear from you.


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