To mitigate impacts from point (wastewater treatment plants and industry) and diffuse sources (agriculture, forestry, unconnected wastewater pipes, storm water and atmospheric deposition), the protection, restoration and creation of wetlands are proposed as a solution. Hydrologists within the strategic research programme Baltic Ecosystem Adaptive Management (BEAM), are investigating the effects of wetlands on nutrient retention at a landscape-scale.

The role of wetlands on reducing nutrient loads ...

A number of studies have assessed the role of wetlands in retaining nutrients at local catchment scales, often focusing on the effectiveness of single wetlands.

- Generally, there is evidence that such wetlands can retain nutrients under favourable conditions, says Andrew Quin at the Department of Physical Geography and Quaternary Geology. However, for nutrient retention, the effectiveness of having multiple wetlands distributed throughout the landscape also needs to be investigated.

... undetectable at a landscape-scale

Total nitrogen retention from catchments to the Baltic Sea (where blue areas signify low levels of retention and red high levels), for the South Baltic River Basin District, Sweden. By Andrew Quin.

By analysing data on nutrient retention (PLC5 data) with data on wetlands (SMD; Eng: Swedish Land Cover Data) for both the North and the South Baltic River Basin Districts in Sweden the nutrient retention was investigated. Results reveal that the effect of wetlands on nutrient retention at a landscape-scale are undetectable. Landscape features which have a significant effect on nutrient retention include large lakes and the transport distance from sources to the sea via rivers and lakes.

- The implication of these results is that water management policies promoting the protection, restoration and construction of wetlands for their nutrient retention effects will need to take into account the effectiveness of such measures relative to other landscape features which are much more effective at retaining nutrients, Andrew Quin explains.

More information

BEAM Short Research Films

Wetlands and nutrient retention