Fen Management Handbook - Scottish Natural Heritage

4.2.3 Point and diffuse sources of nutrients
Figure 4.2
Diagram to show point and diffuse sources
of nutrients
Sewage Plant
Factory
Source: Diffuse (purple), point source (orange)
Nutrient enrichment from water and aerial sources can be described as being from
either a ‘diffuse’ or ‘point’ source. Point source enrichment is related to a single
or focussed discharge e.g. the release of effluent from a sewage treatment plant
(N and P), emissions from a motorway (NO x ) or intensive pig and poultry farming
(NH 3 ).
Diffuse enrichment caused by land-based activities, both rural and urban, can be
dispersed across a catchment. Agriculture is not the only cause but is the single
biggest threat of diffuse enrichment to water and wetlands, contributing about
60% of nitrates, 25% of phosphorus and 70% of sediments entering water bodies
(DEFRA, 2008).
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