Wpływ imisji z Elektrowni "Dolna Odra" na gleby leśne i uprawne w latach 1977-1996

The results of long-term studies (1977 - 1996) presented in this paper showed how the precipitation chemistry (tab. 1) affected the properties of surface horizons (0 - 20 cm) of weakly buffered forest and arable soils (tab. 2 and 3) developed from sandy parent materials which dominate on the area under the emissions from “Dolna Odra” power plant. From this source of in the period 1981 - 1996 was yearly emitted 52 - 100 thousands tons of SO₂ and 21 - 34 thousands tons of NOx. The level of emissions of these pollutants, which substantially changed the chemistry of precipitation, decreased in years 1992 - 1996 to the yearly averages of 55 thousands tons of SO₂ and 23 thousands tons of NOx. To illustrate changes over the time (1977 - 1996) the concentrations and amounts of compounds which reached as wet and dry deposition the nine gauges located within the distance of 0.2 - 3.5 km from power plant were presented as the means for five years periods. The changes of properties and content of the compounds in composite samples sampled from surface horizons (0 - 20 cm) from 7 sites of forest as well as arable soils were presented in similar way. During the years 1992 - 1996 with wet and soluble part of dry deposition the following amounts (expressed as yearly means in kg/km²) reached the surface of precipitation gauges: H⁺ 17, S-SO₄ 1677, N-NH₄ 696, N-NO₃ 316, N-NO₂ 5, Ca 3166, Mg 300, K 667, Na 605 and P-PO₄ 29. As compared to the years 1977 - 1981 in this period the substantially less the majority of compounds were entered with precipitation to the surface of forest and arable soils (H⁺ 40%, S-SO₄ 41%, N-NH₄ 47%, N-NO₃ 10%, N-NO₂ 49%, Mg 41%, K 41% and P-PO₄ 70%). Only amounts of calcium and sodium were similar During the years 1992 - 1996 in forest soils the increase of exchangeable and hydrolitical acidity respectively 20 and 10% was observed as compared to the beginning of the study (1977 - 1981) and in arable soils only 16% increase of hydrolitic acidity was found, accompanied with decrease of degree of base saturation respectively 8 and 12%. The content of soluble in 2.5% CH₃COOH K and P decreased in forest soils respectively 22 and 52% when in arable soils only P (24%). In arable soils increase of soluble Mg, K and Na respectively 25, 31 and 83% was found. Both in forest and arable soils substantial decrease of sulphur accumulation was observed (respectively 41 and 30%).