Accumulation of heavy metals in forest dwarf shrubs and dominant mosses as bioindicators of atmospheric pollution
This article discusses the environmental concerns about heavy metal accumulation in dominant forest mosses and dwarf shrubs. Samples of two different species of mosses, such as glittering wood moss (Hylocomium splendens) and feathermoss (Pleurozium schreberi), and two species of dwarf shrubs, that is European blueberry (Vaccinium myrtillus) and lingonberry (Vaccinium vitis-idaea), were collected from specifically chosen areas with evident anthropogenic pollution (vicinity of an airport and close to heavy road traffic) and from contamination-free, secluded forest areas in Lithuania and Sweden. Instrumental analysis of heavy metals, including cadmium, chromium, copper, lead and zinc, revealed that the selected plant species tend to accumulate zinc and copper the most and chromium the least. Forest mosses, used as indicators of airborne pollution, accumulated less heavy metals than dwarf shrubs, indicating more metal accumulation from the soil. The results also revealed that forest dwarf shrub leaves even picked from areas with known anthropogenic pollution sources were safe to use, since concentrations of cadmium and lead remained below the maximum permissible level. A multivariate data analysis model with two principle components explained more than 70% of the data variation. The heavy metal content in soil was the most distinctive factor separating the Lithuanian and Swedish sites. Cadmium and chromium soil contents were more significant in the Lithuanian soils, whereas copper, lead, and zinc were more significant in the Swedish soils.