| Smog, acid rains and depletion in the troposphere ozone layer have incited managers to tackle these issues with measures leading to a reduction of the atmospheric emissions. Since 1974 most environmental legislation referring to atmospheric deposition is governed by international agreements:
In June 1999 the European Commission presented a proposal for a directive setting national emission ceilings (NECs) for four air pollutants that cause acidification and the formation of ground-level ozone: sulphur dioxide (SO2), nitrogen oxides (NOx), volatile organic compounds (VOCs), and ammonia (NH3). After two years of negotiation, it was adopted by the Council of Ministers and the European Parliament in July 2001.
The aim of the directive is to gradually improve, through a stepwise reduction of the four pollutants, the protection of both human health and the environment throughout the EU. By means of EU strategies to combat acidification and ground-level ozone, the directive establishes interim environmental quality targets that are to be attained by 2010.
These targets constitute the first step towards the achievement of the long-term objectives of not exceeding the so-called critical loads, and of effective protection of human health against risks from air pollution, as laid down in the Fifth Environmental Action Programme. This NEC directive is the key legislation for the achievement of those environmental objectives, as well as for attaining the EU air quality standards for a number of pollutants, including SO2, NO2, fine particles (PM10), and ozone.
The effects of atmospheric emissions are furthermore not restricted to smog and acid rains, and it is now recognized as an important input of nutrients to the coastal area. As an example, for the North Sea that is surrounded with industrial sources of atmospheric emissions, the atmospheric contribution to the total land based nitrogen input has been reported to be on the order of 30% for the total North Sea (North-Sea-Task-Force, 1993).
Although delivered as a diffuse flux in contrast to localized river inputs (Jickells, 1998), the atmospheric nutrient input can be locally distributed and episodic (de Leeuw et al., 2003a) . As a consequence, the assessment of the effects of atmospheric deposition on the coastal ecosystem requires a monitoring with a high resolution matching the spatio-temporal distribution of these events.
Our ability to recognize to which extent individual emission’s sanitation contribute to an abatement of the nutrient deposition on sea, requires the assessment of the relevant processes acting on the trajectories and transformations of the aerosols between their emission and their deposition in the coastal area. |
