The nutrient time bomb

Scientists from the Natural Environment Research Council have been tracking how rainwater moves through the layers of soil and rock in lowland catchment areas (drainage basins) to end up in rivers and groundwater – a major source of the UK’s drinking water. Through this Lowland Catchment Research (LOCAR) Programme the scientists are now able to predict the rate at which rainwater flows through the ground and have also found that, as it moves through the soil, the water becomes contaminated with agricultural chemicals.

Some of the polluted water finds a rapid route to the river through cracks in the ground. But around 70% of the water soaks slowly through permeable layers of soil and rock – such as the chalky downs of southern England – taking many years to reach the water table below, but still carrying its cocktail of nutrients.

Professor Howard Wheater, one of the LOCAR research team, said, “As the use of agricultural chemicals has increased, the amount of chemicals in the chalk has built up – creating a time bomb of pollution just waiting to find its way into our drinking water. We have fed our findings into a model that predicts when this pollution will reach the rivers, helping catchment managers to draw up a timetable for taking remedial action.”

This is just one of the results being presented at the LOCAR ‘Go with the Flow’ conference in London, at which the new findings from the programme will be outlined to users such as policy makers and water companies.