Nutrient Dynamics in European Water Systems
Synthesis Results
2. Characterisation of nutrient sources (2 of 4)
2.1 Atmospheric nutrient inputs
Large deposition of nitrogen may occur during short periods (de Leeuw et al., 2003). This is illustrated with an example for the ANICE experiment in August 1999 when the southern North Sea experienced a short period of strong south-easterly flow (Figure 2.1(c)).
In the Kattegat Strait, events of high atmospheric wet deposition could increase chlorophyll growth by approximately 20% or more (Hasager et al., 2003).
Chlorophyll
A green pigment present in green plants and cyanobacteria. Chlorophyll is essential in the transformation of light energy to chemical energy in photosynthesis. See Glossary for a complete list of terms.
Similarly, about 30% of new production off Ireland can be supported by atmospheric nitrogen inputs in May 1997 (Spokes et al., 2000).
Markaki et al. (2003) estimated the effect of phosphorus deposition by 38% of the new production observed in Crete during the summer and Autumn period.
Figure 2.1(c). Temporal variation of the concentratios of nitrate and ammonium in the fine and coarse fractions measured at Weybourne during the Anice experiments in August/September 1999 (de Leeuw et al., 2003).
The spatial distribution of nitrogen deposition to the North Sea (de Leeuw et al., 2003) shows strong gradients near the source areas. They have the effect of focusing atmospheric deposition into coastal areas (Figure 2.1(d)).
The assessment of nutrient deposition requires a fine gridded model dynamically coupled with a meteorological model.
Such gridding efforts are to be employed Europe-wide instead of focusing on the North Sea and the north-west Mediterranean Sea.
Both nitrogen and phosphorus deposition are to be addressed by monitoring efforts.
Figure 2.1(d). Total atmospheric nitrogen deposition to the North Sea in August 1999. Deposition values are given in kgNkm-2 (de Leeuw et al., 2003).
