Analysis of bulk precipitation chemistry in Serbia for the period from 1982 to 2010

Abstract

Bulk precipitation samples collected daily through bulk collectors at eight meteorological stations in Serbia were analyzed for their chemical composition. The data covers time series, from 20 to 28 years, in the period between 1982 and 2010. The most abundant ion in the samples was sulfate. Only 0.17% of all samples were from strong acid rains (pH < 3.5). The relatively high average pH values (5.94-6.26) of the collected precipitation indicate the neutral or alkaline nature of local rainwater. Trends in both the annual amount and the composition of precipitation were tested by the nonparametric Mann-Kendall test and Sen’s slope estimator. Significant increasing trend of precipitation was identified for almost all stations. Rebuilding activities after the bombing of Serbia in 1999 were identified as a possible anthropogenic cause of the sharp increase of some ions (Ca2+) in the first year following the bombing. The origin of air masses arriving at one particular station was examined using two-dimensional backward trajectories. Western sectors (W, SW and NW) accounted for almost half (44.3%) of all rainy days, while eastern sectors (SE, E and NE) brought only 10.4% of all rainy days. The distribution, per sector, of volume-weighted concentrations of sulfate, nitrate, ammonium, calcium, potassium, magnesium, chloride and sodium ions, as well as the amount of precipitation and its pH values for one station, was also analyzed. Rainwater from the SE and S sectors was the most polluted.