ON THE ASSESSMENT OF SULFUR DEPOSITION ON FORESTS GROWING OVER THE AREAS OF INDUSTRIAL-IMPACT

A method of calculation of sulphur deposition values on forests subjec t to long-term industrial influence is presented. Investigations were conducted in the vicinities of nickel smelters of Kola peninsula. Sulp hur dioxide (SO2) is the major phytotoxicant emitted by these enterpri ses. Depositions of sulphur were calculated on the basis of ground air layer pollution. To determine it a mathematical model was applied. Fi eld surveys of forest ecosystems response to air contamination were ca rried out and areas of different forest damage degree were identified. More than 4300 km(2) of the territory of Kola peninsula is under the impact of nickel enterprises. Average SO? concentration over the area of slight damage to forests is about 20 mu g/m(3). It corresponds to t he critical level proposed for forest ecosystems (UN ECE, 1993). Sulph ur deposition over the area of slight damage Varies from 0.6 to 1.0 g/ m(2) yr(-1) for coniferous forests. For deciduous forests it is about 1.0 g/m(2) yr(-1). These values are close to target loads for highly s ensitive ecosystems (Nilsson et al., 1991), but they exceed critical l oads for the northern regions of Europe (Dawning et al., 1993).