Scientists Measure Storm Impact on River Pollution

Excess concentrations of phosphate and nitrate in river water originating from fields, crops and sewers are some of the major pollutants affecting Britain’s rivers and estuaries.

These nutrient-enriched waters can cause severe problems, such as stimulating the growth of excess algae including toxic species (red tides) that can cause shellfish poisoning in humans. The subsequent breakdown of excess algal biomass also depletes oxygen from the water and can cause widespread death to fish.

Using the Hampshire Avon and Stour rivers and Christchurch Harbour in Dorset as examples, the team will spend 12 months measuring nutrient water quality and examining pollution levels when sediments in the estuary are stirred up by storms. They will also look at how sudden storms affect the input of nutrients and biological activity in the estuary.

The work is crucial because climate change means that the intensity and frequency of storms are likely to increase.

Results of the study will be used to create a powerful statistical model of the distribution of excess phosphates and nitrates, how they transfer from rivers, through estuaries and into the coastal seas and the role that storms play in this process. The team anticipate that this will allow policy makers to make more informed decisions about how to reduce nitrate and phosphate pollution in our estuaries.

Researchers at UEA are part of a consortium including the University of Southampton, the University of Portsmouth, and the National Oceanography Centre in Southampton - which together have won a Natural Environmental Research Council (NERC) grant of more than a million pounds.

Dr Jan Kaiser, from UEA’s School of Environmental Science, said: “Under normal conditions, biological processes in rivers help remove excess nutrients and pollutants from the water. But during storms, run-off from fertilised fields and discharge from sewage treatment plants can suddenly increase.

“This can lead to a larger proportion of excess nutrients remaining in the water – resulting in the stimulation of algal blooms, oxygen loss and fish deaths in estuaries and river mouths.

“Current monitoring programmes are insufficient to capture the rapid changes during storms. Our research will use custom-built state-of-the-art technology to close this gap in our understanding.”

Approximately 40 per cent of the world's population live within 100 km of the coast and estuaries making them some of the most vulnerable sites for impact from man's activities.

Previously most water quality monitoring in rivers and estuaries has taken place at fixed times that are spaced too far apart to capture storms when they occur. The project is the first in the UK to monitor water quality in estuaries using sensors and weather prediction technology to anticipate a storm.