Norwegian Institute for Air Research
Netherlands Institute for Ecology
Tyndall Centre for Climate Change Research
Institute for Environmental Studies, Free University Amsterdam
University of Plymouth
Centre for Social and Economic Research on the Global Environment
Land-Ocean Interactions in the Coastal Zone
 


Nutrient Dynamics in European Water Systems
Synthesis Results

2. Characterisation of Nutrient Sources (1 of 4)

 
The European coastal zones are areas of great concern because of growing problems associated with increasing inputs of nutrients since the late 1960s. These have resulted in a higher incidence of harmful algal blooms and other eutrophication phenomena and cause deleterious impacts on fisheries and tourism. At world scale, efficient assessment tools for nutrient management are also urgently needed for the developing countries where explosive industrialisation, urbanisation and demography heavily impact on the environment.
 
2.1 Atmospheric nutrient inputs
 

Terrestrial inputs of nitrogen are often dominated by riverine transport, especially in the winter. However, atmospheric deposition of nitrogen compounds has been shown to be a significant terrestrial input to the coastal seas, especially in summer and fall. As an example, the atmospheric contribution to the total land based nitrogen input has reported to be in the order of 30% for the total North Sea (North Sea Task Force, 1993).

Wet deposition represents 81% of nitrogen deposition: 38% from agricultural activity (NH3 and NH4+), and 72% due to emissions from combustion sources (Hertel et al., 2002).

A remarkable finding of this study is that ship traffic is a very significant source of marine deposited nitrogen (Figure 2.1(a)).
Figure 2.1(a). Total annual NOx emissions for the model domain given in ton NO2 per 16.67km x 16.67km grid. The shipping routes are clearly identified by their emissions on the map (Hertel et al., 2002).
Figure 2.1(a). Total annual NOx emissions for the model domain given in ton NO2 per 16.67km x 16.67km grid. The shipping routes are clearly identified by their emissions on the map (Hertel et al., 2002).
 

Due to their reactivity and due to scavenging by sea salt aerosol, a significant fraction of the gaseous species such as NH3 and HNO3 may be removed from the atmosphere in the first 10-20km across the coastline (de Leeuw et al., 2001).

As a result, the magnitude of inputs drastically decreases with the distance from the coast (Figure 2.1(b)).

In particular, HNO3 reacts directly with sea spray aerosol and evidence of the sea spray reaction is presented; HNO3+NaCl =NaNO3+ HCl . Current atmospheric chemistry transport models do not include such reactions. Work is underway in several groups to implement heterogenous chemistry involving HNO3.

 
Figure 2.1(b). Modelled concentration profiles of nitirc acid for various distances from the coast (from de Leeuw et al., 2001).
Figure 2.1(b). Modelled concentration profiles of nitric acid for various distances from the coast (de Leeuw et al., 2001).
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