Abstract
The nitrate content of bulk precipitation samples in Hungary has increased about seven timesrelative to its original value, during the last 8 decades. At the same time, the concentration ofammonium ion has somewhat decreased. The increase of nitrate is significant in all seasons, especially in spring months. The ammonium concentration has decreased in fall and in winter, while it has increased in spring and summer. The present spring concentration maxima of nitrateand ammonium have developed since the turn of this century. The trends observed can beexplained by the increased tropospheric concentration of air pollutants in this region.