Biodegradation of two superabsorbent polymers, a crosslinked, insoluble polyacrylate and an insoluble polyacrylate/ polyacrylamide copolymer, in soil by the white-rot fungus, Phanerochaete chrysosporium was investigated. The polymers were both solubilized and mineralized by the fungus but solubilization and mineralization of the copolymer was much more rapid than of the polyacrylate. Soil microbes poorly solublized the polymers and were unable to mineralize either intact polymer. However, soil microbes cooperated with the fungus during polymer degradation in soil, with the fungus solubilizing the polymers and the soil microbes stimulating mineralization. Further, soil microbes were able to significantly mineralize both polymers after solubilization by P. chrysosporium grown under conditions that produced fungal peroxidases or cellobiose dehydrogenase, or after solubilization by photochemically generated Fenton reagent. The results suggest that biodegradation of these polymers in soil is best under conditions that maximize solubilization.

Prolonged effects of the multicomponent air pollution complexes emitted from the cement production in Kunda and oil shale processing in Kohtla-Jaerve, North-East estonia, on the forest ecosystems are discussed. It was found that atmospheric input substantially affects biogeochemical cycling in forest. The comparatively high concentrations of alkaline dusts and ash and various gaseous pollutants in the atmosphere of the investigated areas over 40 years have caused qualitative and quantitative changes in the forest soil, soil water and precipitation and in the state of forest and trees. Although the levels of air pollutants emitted by the industry have seriously decreased in recent years, alkalisation of the growth environment of trees is still essential in some regions. Alkalisation of soil and soil water in the vicinity of Kunda and Kohtla-Jaerve complicated mineral nutrition processes and disbalanced mineral elements composition in tissues, which resulted in a decrease in the increment and quality of trees