Nitrogen emissions have grown in Spain during the last 15 years. As precipitation scavenges gases and aerosols from the atmosphere, an effect on rainwater concentrations can be expected. However, time-series studies on wet N concentrations in the Iberian Peninsula are very scarce. This paper aims to fill this gap by analysing weekly rainfall N concentrations at a set of rural sites in Catalonia (NE Spain) from 1995/1996 to 2007 and a forest site monitored from 1983 to 2007. The sites encompass a range of rural environments and climate conditions, from the inland pre-Pyrenees (Sort) to the Mediterranean coast (Begur) and from north (Sort and Begur) to central (Palautordera and La Castanya) and south Catalonia (La Senia). We found a 1-year cycle for concentrations of NH 4+ and NO 3- whereby higher values were reached at the end of spring-early summer, except at the easternmost coastal site of Begur. Weekly NH 4+ concentrations decreased with time at all sites (except at La Senia) whilst NO 3- concentrations increased at all sites during the same period. Rainfall SO 42- concentrations decreased with time at all sites. The opposite trends in NO 3- and SO 42- concentrations determined a shift in the relative acid contribution of those anions during the 12-13-year period. To interpret the increasing trend, mean annual NO 3- concentrations were regressed against NO2 Spanish emissions and to some indicators of local anthropogenic activity. The increase at Sort and Palautordera showed good correlation with local anthropogenic indicators. Wet inorganic N deposition ranged between 4.2 and 6.7 kg ha-1 year-1. When including estimates of dry deposition, total annual deposition rose up to 10-20 kg ha -1 year-1, values that have been found to initiate adverse effects on Mediterranean-type forest ecosystems. © 2009 Springer Science+Business Media B.V.
|Journal||Water, Air, and Soil Pollution|
|Publication status||Published - 1 Mar 2010|
- Inter-annual trends
- Rural areas
- Seasonal cycle