Immission-load-related dynamics of S-SO42− in precipitation and in lysimetric solutions penetrating through beech ecosystems

The paper presents the results of a 23-year study of sulphate sulphur dynamics in beech ecosystems exposed to different immission loads. The amounts of S-SO₄²⁻ in precipitation water entering the ecosystems were: the Kremnické vrchy Mts, a clear-cut area 519 kg ha⁻¹ (24.7 kg ha⁻¹ per year), a beech forest 476 kg ha⁻¹ (22.7 kg ha⁻¹ per year); the Štiavnické vrchy Mts an open place 401 kg ha⁻¹ (24.6 kg ha⁻¹ per year), a beech forest 324 kg ha⁻¹ (19.1 kg ha⁻¹ per year). The average SO₄²⁻ concentrations in lysimetric solutions penetrating through surface humus to a depth of Cambisol 10 and 25 cm were increased as follows: in the Kremnické vrchy Mts from 12.71 to 16.17 mg l⁻¹ and in the Štiavnické vrchy Mts from 18.73 to 28.80 mg l⁻¹. The S-SO₄⁻² amounts penetrating the individual soil layers in the Kremnické vrchy Mts were as follows: in case of surface humus on clear-cut area 459 kg ha⁻¹ (20.9 kg ha⁻¹ per year), in beech forest 433 kg ha⁻¹ (19.7 kg ha⁻¹ per year); below 10 cm organo-mineral layer of the mentioned plots penetrated 169–171 kg ha⁻¹ (7.7–7.8 kg ha⁻¹ per year), and below 25 cm mineral layer 155–255 kg ha⁻¹ (7.1⁻¹1.6 kg ha⁻¹ per year) – a higher amount was found on clear-cut area with an episodic lateral flow of soil solutions. In beech forest of the Štiavnické vrchy Mts penetrated below surface humus 424 kg ha⁻¹ S-SO₄²⁻ (18.9 kg ha⁻¹ per year), below 10 cm mineral layer 458 kg ha⁻¹ S-SO₄²⁻ (19.9 kg ha⁻¹ per year), and below 25 cm mineral layer as much as 599 kg ha⁻¹ S-SO₄²⁻ (26.0 kg ha⁻¹ per year). This fact was caused by frequent lateral flow of soil solutions. The results indicate that the assumption about lower immission load of the beech ecosystem in the Kremnické vrchy Mts is wrong, at least in the case of S-SO₄²⁻. The testing has revealed that the studied beech ecosystems differ very significantly in sulphur amounts penetrating under 0.10 m and 0.25 m. The inter-annual differences were insignificant.