Nottingham University. UK: Potentially toxic microbes which pose a
threat to our drinking water have undergone a dramatic population
explosion over the last 200 years as a result of pollution, research
involving experts from The University of Nottingham has found.
The study, published in the journal Ecology Letters,
looked at more than 100 lakes in lowland and alpine areas of North
America and Europe and found that populations of cyanobacteria — also
known as blue-green algae — have significantly increased since the
1800s.
The research, conducted in collaboration with academics at McGill University
in Canada and other collaborators, is the first study to show that a
rise in the algae’s available nutrient sources nitrogen and phosphorus —
commonly resulting from industrial fertilisers and sewage discharge —
is the biggest potential culprit responsible for the increase in such a
large number of lakes, across such a large geographical area. The study
also found that climate change can exacerbate this problem, with water
management challenges likely to increase in a future warmer world.
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Water contamination
Most
municipal water treatment plants do not regularly look for
cyanobacterial toxins in the water supply. However, municipalities with a
known history of blooms typical monitor their surface water supplies
for cyanobacteria. When detected, the cells can be removed by adding
chemicals that bind them together, so they can be separated out.
Although this removes the cells, the cells may already have broken down
releasing toxins into the water.
In addition, environmental costs
associated with this alga were estimated to exceed $100 million per year
in both the UK and Australia.
PhD researchers Heather Moorhouse and Mark
Stevenson, based in the School of Geography at Nottingham’s University
Park Campus in the UK, and Dr Suzanne McGowan,
Head of the School of Geography at University of Nottingham Malaysia
Campus, took sample cores of sediment from lakes located in the major
lake districts of the British Isles including the English Lake District,
the West Midland Meres, Scottish lochs and upland lakes in Northern
Ireland and analysed them for pigments left behind by blue-green algae.
These pigments remain stable over
thousands of years and act as biomarkers revealing the past levels of
algae found in the water during the course of decades.
Rapid increase
The
analysis showed that during the last 200 years, more than half of the
lakes (58 per cent) had seen significant increases in concentrations of
blue-green algae pigments, whereas only three per cent showed a
significant decrease in the presence of the microorganism.
Lowland lakes in agricultural catchments
typical of those found in the UK were found to be especially susceptible
to cyanobacteria increases.
The study also found that since 1945 the
incidence of blue-green algae has increased more rapidly than the growth
of other types of water-borne algae.
More significant increases were observed
in the more temperate lowlands (61 per cent in North America and 70 Per
cent in Europe) which were closer to areas of agricultural activity than
in alpine areas (36 per cent).
Analysis of the trends in blue-green algae
spanning 10 countries across three continents showed that growth was
mainly regulated by a change in the amount of nutrients — phosphorus and
nitrogen — found within the lakes.
The research underlines the importance of
further study into how to more carefully control the inputs of nitrogen
and phosphorus-rich pollutants and ways of monitoring the resulting
toxins in our drinking water. It also demonstrates that effective
catchment nutrient control initiated by legislation such as the EU Water Framework Directive is important to the safety of our water supplies in the future.