Bulk deposition in a rural area located around a large coal-fired power station, northeast Spain

This work focuses on bulk deposition in a rural area located around a large coal-fired power station in northeast Spain. Deposition chemistry was characterised by high concentrations of SO42−, Ca2+ and NH4+, which were relatively high when compared with other rural areas. Monthly bulk deposition evolution of major ions was the result of two superimposed patterns: one pattern related to the volume of precipitation and the other showed the seasonal influence of the major ionic sources. A major local origin was attributed to bulk deposition of SO42−, NH4+, and Ca2+, whereas a relatively higher contribution of an external source was deduced for NO3−, Na+ and Cl−. The SO42− concentrations showed a significant correlation with the local SO2 emissions. High levels of Ca2+ were due to the high alkalinity of soils in the study area, although an external origin was attributed to the frequent air mass intrusions from the Sahara. Sources of NH4+ were related to intensive livestock farming in the area. Total suspended particles exert a marked influence over bulk deposition and neutralisation. Thus, despite the high emissions of SO2 in the area, neutral pH values have always been attained given that the concentrations of Ca2+ and NH4+ account for the total neutralisation of NO3− and SO42−.