The contributions of different acidifying processes to the total protonload (TPL) of the soil in control plots (C) and ammonium sulphate treatedplots (NS) were studied in a Norway spruce stand in Southwest Sweden during 1988–1998. The annual deposition of inorganic nitrogen and sulphate was on average 18 kg N and 20 kg S ha⁻¹. In addition the NS treated plots received 100 kg N and 114 kg S ha⁻¹annually. The amounts of nutrients added to the ecosystem by wet and dry deposition and the leaching at 50 cm depth were calculated. The net atmosphericproton load, the proton load by nitrogen transformations in the soil, the sulphate sorption/desorption in the soil and the excess base cation accumulation in biomass were calculated. There was no leaching of inorganic nitrogen from control plots during the study period. The net atmospheric proton deposition, originating from sulphuric and nitric acid deposition, was the main contributor to TPL in control plots. The addition of ammonium sulphate increased the leaching of ammonium, nitrate, sulphate, magnesium and calcium but not of potassium. The TPL in NS plots was about ten times that in control plots. The nitrogen transformation processes were the main contributors to TPL to NS soil, in the beginning by ammonium uptake and later also by nitrification. The pH decreased by 0.4 units in the mineral soil. The between-year variation in TPL during the eleven year period in C plots (200–1500 molcha⁻¹yr⁻¹) and in NS plots (1000–13000 molcha⁻¹yr⁻¹) was mainly dependent on the sorption or release of sulphate. Both in C and NS, the TPL was buffered mainly by dissolving solid aluminium compounds, most probably some Al(OH)₃phase.

The town Pozarevac water supply is endangered due to groundwater quality degradation on the only remaining water source Kljuc 1. Nitrate content presents critical parameter (MCL in potable water is 50 mg NO3/l) with values in cumulative samples up to 40-45 mg NO3/l, locally up to 70-100 mg NO3/l. Rapid water quality degradation on water source in the last few years is a consequence of the surrounding activities which have influenced on quality deterioration, excessive groundwater extraction, off-line of water source Meminac, unfavourable hydrologic conditions etc.

Concentrations of nitrate above defined levels for portable water are present in most of the groundwater sources in Velika Morava river alluvion. Some problems exists in Meminac and Kljuc, groundwater sources of Pozarevac town. Some detail investigations were organized in 2002. Survey of groundwater quality in the wide surrounding of Kljuc confirmed some earlier made assumptions about influence of agriculture and sewage water, and their contribution to existing groundwater quality.