Accumulation of Heavy Metals in Blueberry (Vaccinium myrtillus L.) and Dominant Mosses (Pleurozium schreberi (Willd. ex Brid.) Mitt.) as Bioindicators of the Expressway Influence on Forest Ecosystems

Abstract

The intensive use, development, and expansion of the road network is expanding the zones of direct impact of road transport on forest ecosystems. Issues related to the mobility of trace elements in forest ecosystems along motorways are very important due to the numerous environmental risks associated with the excessive accumulation of metals, the ability to migrate and accumulate in plants and animals, and the risk of transferring these elements to higher trophic levels. The aim of this article was therefore to determine the impact of road traffic on the basis of contents of trace metals Cd, Cr, Cu, Ni, Pb, and Zn and to describe the relationship of these contents in moss gametophytes and blueberry leaves taken in the vicinity of an existing and variously expanded expressway (S7, Poland, Europe). Analyses of transport impacts included the effects of distance and time of pollutant deposition and road transport on habitat and stand conditions. The highest contents of Cd, Cr, Cu, Ni, Pb, and Zn in moss tissues were found in fir stands and the contents were, respectively, 0.36 mg·kg−1, 5.91 mg·kg−1, 12.5 mg·kg−1, 3.26 mg·kg−1, 8.82 mg·kg−1, and 55.28 mg·kg−1. Mosses showed the best bioindication capacity of all of the studied ecosystem elements. The Pb, Zn, Cr, Cu, and Ni contents were particularly markedly elevated in moss tissues relative to non-anthropopressured areas and dependent on distance from the emitter (road). Blueberry proved to be a less useful bioindicator, as the contents of Cd, Cr, Cu, Ni, Pb, and Zn found were similar to the data from non-anthropopressured areas and were, respectively, 0.09 mg·kg−1, 0.98 mg·kg−1, 7.12 mg·kg−1, 2.49 mg·kg−1, 1.18 mg·kg−1, and 15.91 mg·kg−1 in fir stands and 0.04 mg·kg−1, 0.47 mg·kg−1, 6.63 mg·kg−1, 1.65 mg·kg−1, 0.72 mg·kg−1, and 17.44 mg·kg−1 in pine stands.