Edgar Karofeld

Emäksisen tuhkalaskeuman vaikutus rahkasammaliin Niinsaarensuolla Koillis-Virossa

Karofeld E. Emäksisen tuhkalaskeuman vaikutus rahkasammaliin Niinsaarensuolla Koillis-Virossa.

Tiivistelmä

In north-east Estonia the precipitation of calcium-rich strongly alkaline fly ash from thermal power stations has caused significant changes in the local ombrotrophic mires. Sphagnum mosses disappeared from Niinsaare bog during the 1970s in the period of the highest air pollution. Their disappearance was probably caused mainly by the combination of high pH values and an increased concentration of calcium in the bog water. In Niinsaare bog, the present mean pH value of bog water is 5.3 ± 0.6 and the mean calcium concentration 11.6 ± 1.6 mg l-1, compared with 3.7 ± 0.4 and 1.9 ± 0.2 mg l-1 in the uncontaminated Nigula bog respectively. During the last decade, following the reduction of fly ash emission, the Sphagnum mosses started to reappear in Niinsaare bog. Nine Sphagnum patches dominated mainly by S. angustifolium, S. fallax and S. magellanicum were studied from June 1991 to September 1995. During one year, the distance between the centre and edges of these patches increased on an average by 5.1 ± 2.7 cm and the area by 29 ± 21.5 %. This indicates that the degeneration of Sphagna in NE Estonian bogs is not yet irreversible and, by reducing the air pollution in long term, the restoration of Sphagnum carpet is possible. Key words: atmospheric pollution, degeneration and recurrence of Sphagna, ombrotrophic mire.

Avainsanat
atmospheric pollution; degeneration and recurrence of Sphagna; ombrotrophic mire

Vastaanotettu 31.10.2017 Julkaistu 1.1.1996

Katselukerrat 1130

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