Pekka Pakarinen , Ahti Mäkinen

Suosammalet, -jäkälät ja männyn neulaset raskasmetallien kerääjinä

Pakarinen P., Mäkinen A. Suosammalet, -jäkälät ja männyn neulaset raskasmetallien kerääjinä.

Tiivistelmä

This paper presents the results of heavy metal (trace element) analyses of plant samples collected from three undrained ombrotrophic bogs in southern Finland (60—61°N, Fig. 1). The species studied included three mosses — Sphagnum fuscum, S. balticum, S. majus — and four lichens — Cladonia stellaris (= C. alpestris), C. arbuscula, C. rangiferina, Hypogymnia (= Parmelia) physodes. Also the needles of stunted bog pines Pinus silvestris) were collected and separated according to age (current vs. 1—2-year-old needles). Collective samples (5—10 replicates) consisting only of the living top part were taken (lichens 4—5 cm, hollow mosses 3—6 cm, hummock mosses 2 cm). The samples were dry-ashed at + 500° C, then dissolved with cone, hydrochloric acid, diluted with distilled water and analysed for metals with Varian Techtron AA-1200 atomic absorption spectrophotometer at Botany Dept., University of Helsinki. Duplicate samples were also digested directly with HNO3 and HCl for control. The results of the former method are presented in Figs. 2—4 on oven-dry ( + 70°C) weight basis. Among bryophytes, the contents of Pb, Zn and Mn were in all cases highest in hummock species Sphagnum fuscum and lowest in the wet-hollow species S. majus. Among lichen species, the concentrations of lead and zinc decrease in the order: Hypogymnia physodes (epiphyte) > Cladonia rangiferina > C. stellaris, C. arbuscula. In Pinus the needles from the current year contain less metals than the needles from previous years. A comparison of different plant groups depends upon the element analysed (see Figs. 2—4). Mn content is highest in pine needles followed by Sphagnum fuscum and lowest in lichens and hollow mosses. Zn content is greatest in the epiphytic lichen Hypogymnia followed by pine needles, then by bog mosses and reindeer lichens. As opposed to zinc, the content of lead is lowest in pine needles which fact suggests a low absorption capacity of atmospheric heavy metals by pine needles. On the other hand, zinc and manganese seem to be actively translocated by pine. Consequently, needle analysis does not appear to be an appropriate method for monitoring the deposition of heavy metals. Both lichens and mosses (with the exception of hollow species), however, seem to be efficient accumulators of zinc and lead at least. If the annual primary production of mosses can be determined, it becomes possible also to estimate the deposition rate per surface area of some heavy metals.

Vastaanotettu 31.10.2017 Julkaistu 1.1.1976

Katselukerrat 547

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