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Nitrogen Loadings from Land to the Marine Environment: 1990-2006
Nitrogen loadings (ktonnes)
Nitrogen Loadings (ktonnes) |
Source | 1990 | 1995 | 2000 | 2004 | 2005 | 2006 |
|---|
Industrial | 6.5 | 5.1 | 4.6 | 4.4 | 3.6 | 4.1 |
|---|
Riverine | 46.5 | 59.8 | 62.7 | 55.5 | 42.7 | 46.6 |
|---|
Waste water treatment works | 15.6 | 16.0 | 11.6 | 15.0 | 13.4 | 15.1 |
|---|
Total | 68.6 | 80.8 | 78.9 | 74.9 | 56.7 | 65.8 |
|---|
Increased concentrations of nitrogen inputs in the marine environment may lead to eutrophication. Although most estuaries and coastal waters are not significantly affected by inputs of nutrients, localised impacts can occur, and in certain areas Nitrate Vulnerable Zones have been established to reduce diffuse contributions of nitrogen from agricultural sources.
Riverine inputs make up the greater part of nitrogen loads from land to Scotland's marine waters contributing 71% of the total. These inputs are dominated by contributions from diffuse sources such as agriculture and atmospheric deposition, and vary in size in response to the prevailing weather conditions.
In addition to the 65.8 ktonnes of nitrogen inputs from land in 2006, it is estimated that a further 9.4 ktonnes of nitrogen was unloaded into the marine environment from fish farming. Although locally aquaculture may be an important contributor of nitrogen, SEPA's routine surveys indicate that direct anthropogenic inputs of nutrients to west coast marine waters are insignificant in comparison with those resulting from the oceanic and coastal currents which occur around the coasts of Scotland.
Source: Scottish Environment Protection Agency
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