14 Precipitation Chemistry and Air Pollution
Antoni Escarre, Adoraci6n Carratala, Anna Avila, Juan Bellot,
Josep Pinol and Millan Millan
14.1 Introduction
Interest in precipitation chemistry greatly expanded as a result of the increasing rain acidity over northern Europe and northeastern North America
in the early 1970s. The links between air pollution, acid rain and forest health
have generated many thousands of publications in the last 25 years (e.g.
Drablos and Tollan 1980; Hutchinson and Havas 1980; Ulrich and Pankrath
1983). Precipitation chemistry is indeed relevant to monitor air pollution,
particularly in places distant from source areas, since the principal atmospheric pollutants, sulphur dioxide (S02) and nitrogen oxides (NOJ, can be
incorporated as sulphate and nitrate ions in bulk deposition. Changes in the
emission of these gases are reflected in variations in nitrate and sulphate in
precipitation.
Precipitation chemistry is also relevant in ecosystem nutrient cycles (e.g.
Johnson and Lindberg 1992; Likens and Bormann 1995). Nutrient inputs in
precipitation can make a major contribution to total ecosystem inputs and
even to total nutrient capital of the ecosystem in nutrient-poor sites. Nutrients in precipitation can proceed from a variety of natural and anthropogenic sources, including air pollution. For example, excessive atmospheric
deposition of nitrogen is affecting terrestrial and freshwater ecosystems in
many European countries (Aber 1992).
Bulk deposition is the input flux most often used in nutrient cycling studies because it is relatively easy to measure. Research on bulk precipitation
chemistry in the holm oak (Quercus ilex 1.) forests at Montseny and Prades
(NE Spain) began in 1978 and 1980, respectively. The characteristics of the
precipitation chemistry and the associated nutrient inputs to the ecosystem
are quite well established for these sites (Roda 1983; Avila 1988, 1996; Bellot
1989; Bellot and Escarre 1989; Pino11990; Roda et al. 1993).
In this chapter we first summarize the characteristics of precipitation
chemistry at our two holm oak sites, and infer the sources of delivered elements from ion relationships in precipitation. We then take a broader geoEcological Studies, Vol. 137
Ferran Rodil et al. (eds) Ecology of Mediterranean
Evergreen Oak Forests
© Springer-Verlag, Berlin Heidelberg 1999
Antoni Escarre, Adoraci6n Carratala, Anna Avila, Juan Bellot,
Josep Pinol and Millan Millan
14.1 Introduction
Interest in precipitation chemistry greatly expanded as a result of the increasing rain acidity over northern Europe and northeastern North America
in the early 1970s. The links between air pollution, acid rain and forest health
have generated many thousands of publications in the last 25 years (e.g.
Drablos and Tollan 1980; Hutchinson and Havas 1980; Ulrich and Pankrath
1983). Precipitation chemistry is indeed relevant to monitor air pollution,
particularly in places distant from source areas, since the principal atmospheric pollutants, sulphur dioxide (S02) and nitrogen oxides (NOJ, can be
incorporated as sulphate and nitrate ions in bulk deposition. Changes in the
emission of these gases are reflected in variations in nitrate and sulphate in
precipitation.
Precipitation chemistry is also relevant in ecosystem nutrient cycles (e.g.
Johnson and Lindberg 1992; Likens and Bormann 1995). Nutrient inputs in
precipitation can make a major contribution to total ecosystem inputs and
even to total nutrient capital of the ecosystem in nutrient-poor sites. Nutrients in precipitation can proceed from a variety of natural and anthropogenic sources, including air pollution. For example, excessive atmospheric
deposition of nitrogen is affecting terrestrial and freshwater ecosystems in
many European countries (Aber 1992).
Bulk deposition is the input flux most often used in nutrient cycling studies because it is relatively easy to measure. Research on bulk precipitation
chemistry in the holm oak (Quercus ilex 1.) forests at Montseny and Prades
(NE Spain) began in 1978 and 1980, respectively. The characteristics of the
precipitation chemistry and the associated nutrient inputs to the ecosystem
are quite well established for these sites (Roda 1983; Avila 1988, 1996; Bellot
1989; Bellot and Escarre 1989; Pino11990; Roda et al. 1993).
In this chapter we first summarize the characteristics of precipitation
chemistry at our two holm oak sites, and infer the sources of delivered elements from ion relationships in precipitation. We then take a broader geoEcological Studies, Vol. 137
Ferran Rodil et al. (eds) Ecology of Mediterranean
Evergreen Oak Forests
© Springer-Verlag, Berlin Heidelberg 1999