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Part 4: Findings & Discussion

A CITIZEN SCIENCE INVESTIGATION OF UK WATER QUALITY
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Our Findings:

Nitrate Findings: 

Nitrates: 48.43% of all test results and 45.83% of sites failed to meet an acceptable concentration of nitrate.

Nearly 50% of tested waterways are failing to meet acceptable levels of nitrate pollution. If more stringent thresholds were used, over 80% of tested waterways would fail. In light of these findings, it is clear that nitrate pollution is an issue for our waterways and must be urgently addressed.

Nitrite Findings:

Nitrites: 9.44% of all test results and 16.67% of sites failed to meet an acceptable concentration of nitrite.

With more test sites passing the acceptable threshold, these findings reveal that nitrite pollution is not as prevalent at testing sites as nitrates. This suggests that nitrite pollution is not currently as serious an issue as nitrate pollution. However, given the difference in threshold between the WHO guidelines and those of aquarium maintenance experts, clearer guidelines are needed on acceptable levels of nitrite concentration in our waterways.

Phosphorus/Phosphate Findings:

Phosphate: 69.17% of all test results and 68.75% of sites failed to meet an acceptable concentration of phosphate.

Critically, 68.75% of sites with three or more readings failed to meet an acceptable phosphate standard. Such negative findings suggest that urgent action is required if we are to protect biodiversity, water quality and ultimately meet our climate change targets. 

The Our Phosphorus Future project is currently working to limit pollution and set ambitious targets. A team of 100 scientists and industry experts developed a phosphorus report calling for ‘50:50:50’. This refers to a 50% reduction in global phosphorus pollution and a 50% increase in the recycling of phosphorus lost in residues and wastes, by 2050.

Total Coliform Bacteria Findings

Total coliform bacteria: 85.97% of all test results and 92.86% of sites were positive for total coliform bacteria.

The presence of total coliform bacteria at over 90% of testing sites clearly demonstrates the reach and severity of pollution from sewage discharge. Given the negative impacts upon human health and the environment, it is imperative that urgent action is taken to reduce polluting behaviour – only then will it be possible for water quality to improve.

pH Findings

pH: 74.09% of all test results and 78.26% of sites were within the tolerable pH range.

With nearly three quarters of readings falling within the recommended acceptable level, pH is not as much of an issue when compared to nitrate pollution and phosphate pollution. With approximately 25% of sites outside of the recommended tolerable pH range, it still remains essential to make improvements to the pH levels of our waterways.

Metal Findings

When high metal concentrations are found in a waterway this can be very problematic, and is likely the dominant pressure in the system. These metals come primarily from sources such as active and abandoned mines, metal-processing industries and, even though it is now banned, leaded petrol. Indeed, the EA estimated that over 1,500km of rivers in England are polluted by metals from mines.

Metals are often overlooked in environmental pollution studies despite often being extremely toxic and long-lasting in the environment. Unlike other forms of pollution, metals do not degrade over time. As a result, pollution from over a hundred years ago can still negatively affect the environment and biodiversity today.When high metal concentrations are found in a waterway this can be very problematic, and is likely the dominant pressure in the system. These metals come primarily from sources such as active and abandoned mines, metal-processing industries and, even though it is now banned, leaded petrol. Indeed, the EA estimated that over 1,500km of rivers in England are polluted by metals from mines.

Key Terminology

  • Predicted No Effect Concentration (PNEC) = the concentration below which a specified percentage of species in an ecosystem are expected to be protected.
  • Bioavailability = The amount of an element or compound, such as a metal, that is accessible to an organism for uptake or adsorption.
  • Environmental Quality Standard (EQS) = Standards which are set to protect water bodies from the harmful effects of the contaminants that could flow through them.

Key Metal Findings:

The majority of the site’s surface water was found to be within acceptable limits for the 31 metals tested. However, there were the following five instances of failure: (please put the below in bold, with the number in soulmaze)

  1. One site was above the Environmental Quality Standard (EQS) for copper.
  2. One site was above the EQS for zinc.
  3. One site was above the WHO drinking water standard for manganese.
  4. Four sites were above the proposed short term predicted no-effect concentration (PNEC) for iron.
  5. Six sites were above the UK Drinking Water Standard for potassium.
When high metal concentrations are found in a waterway this can be very problematic, and is likely the dominant pressure in the system.
 
None of the waterbody sites sampled were identified by the EA in the latest available data (2019) as ‘impacted’ by pollution from abandoned metal mines. Given that elevated levels of certain metals were identified, it illustrates that current monitoring efforts may not be capturing the true extent of metal pollution.
 
Impact of climate change:
 
With predictions of heavier rainfall and increased frequency of storms due to climate change, sediment is expected to be disturbed more often. If contaminated, this would cause heavy metals in the sediment to rise to the surface before resettling as well as spreading the pollution over a wider area. Therefore, it is highly important that sediment pollution is investigated and understood. As such, future studies should compare surface water samples to sediment samples.
 
To see a full breakdown of results and a case study for the River Thames and River Trent, please see the full report.

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