Article

Water, Air, and Soil Pollution

, Volume 146, Issue 1, pp 35-54

The Chemical Composition of Precipitation in Madrid

  • C. HontoriaAffiliated withDepartamento de Edafología, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid
  • , A. SaaAffiliated withDepartamento de Edafología, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid
  • , J. AlmoroxAffiliated withDepartamento de Edafología, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid
  • , L. CuadraAffiliated withCentro de Ciencias Medioambientales, CSIC, C/Serrano
  • , A. SánchezAffiliated withCentro de Ciencias Medioambientales, CSIC, C/Serrano
  • , J. M. GascóAffiliated withDepartamento de Edafología, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid

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Abstract

The present study examines the chemical characteristics of first-fraction precipitation samples collected over a period of one year in Madrid, and patterns of temporal and spatial variation observed in their composition. One hundred and sixty-four samples of wet precipitation collected on an event basis were analysed for anions, cations, pH and electrical conductivity. Precipitation in Madrid was neutral, with only 3% of samples showing pH < 5.6. Dominant ions were calcium andsulphates. Calcium was the principal neutralizing agent, explaining 64% of all nitrates and sulphates. The marine influence did not appear to be relevant, while the soil seemed to play an important role in the composition of precipitation. Precipitation chemistry displayed seasonal differences, with higher concentrations of sulphates and chloride in autumn and winter and of calcium and sodium in the summer. There was an inverse relationship between concentrations and sample volumes; while the correlation between concentrations and the time elapsedsince the last rain event was positive, though poor for normalized concentrations. Four variables (sample volume, days elapsed since the last rain event, maximum wind gust direction and season) explained to a large extent (more than 90% for some sampling stations) the variability of certain chemical variables.

correlation meteorological conditions precipitation volume Spain urban precipitation chemistry