Wetter winters may increase river pollution

Warmer, wetter winters could lower the quality of our rivers, according to warnings from environmental scientists.

As farmers try to cope with waterlogged soil following one of the wettest Januarys on record a team of researchers, including Dr Bob Evans of Anglia Ruskin University, has begun work on a new project to better understand nutrient runoff from agricultural land and work out how it affects the quality of our rivers.

The Nutrients in Catchments to 2050 project involves researchers at Lancaster University, the UK Met Office Hadley Centre, Bangor University and Liverpool University and has associated partners at the James Hutton Institute, University of East Anglia, Rothamsted Research and Anglia Ruskin University.

Nutrients such as phosphorus and nitrogen are essential for plant and animal growth, but too many nutrients cause excessive plant growth and algal blooms in rivers and lakes.  These suffocate fish and other organisms and require costly remediation by water companies.

Fertilisers and manures washed off in storms are a major source of nutrients, with more than 60% of the nitrogen and 25% of the phosphorus in our rivers coming from agriculture.

Professor Phil Haygarth, of the Lancaster Environment Centre, is leading the three-year Natural Environment Research Council-funded study.  He said: “Most of this nutrient transport occurs in a few large and intense rain events, particularly if these coincide with periods of bare soil or recently applied manure or fertiliser.

“If future climate trends suggest more frequent, more extreme rainfall events, then nutrient runoff could increase, unless we plan land management activities to account for this.”

Dr Evans, from Anglia Ruskin’s Global Sustainability Institute, said: “For the last 10 years I have monitored runoff and erosion in the upper part of the River Wissey catchment in Norfolk, as well as assessing sources of pollutants in other catchments in East Anglia.

“It is runoff containing sediment, nutrients and pesticides that over the short term is the major impact of erosion, and land use is the main driver of erosion.  If you change land use from mainly crops to mainly grass, or rejig the layout of farmers’ fields, then erosion and runoff will be greatly curtailed.

“The frequency at which some pesticides reach watercourses was one of the reasons for certain herbicides being banned.  Now a major problem is Metaldehyde, which is found in slug pellets, and this can’t be taken out of water.”