Article ID Journal Published Year Pages File Type
4420113 Ecotoxicology and Environmental Safety 2014 6 Pages PDF
Abstract

•P. commune accumulated a significantly higher concentration of Hg than P. schreberi.•Mosses grown in Hg contaminated sites show higher uptake capacities.•Retention of Hg was 10–14% in P. schreberi and 10–21% in P. commune.•Dying of leaf cells started after sixteen days of exposure of P. schreberi to Hg.•Negative effects of Hg started to become visible first in older leaves.

Because of its high mobility in ecosystems, mercury is one of the main toxic threats to the environment, and its concentration must be carefully controlled. To fulfill this need, we selected terrestrial mosses with different characteristic life forms: orthotropic and endohydric Polytrichum commune and plagiotropic and ectohydric Pleurozium schreberi. The concentrations of mercury were determined in both species growing together at sites situated approximately 0.75, 1.5, 3 and 6 km to the north, south, east and west, respectively of five known mercury polluters. The mercury concentrations reflected the emissions produced by the surrounding industry, reaching values of 0.44 mg kg−1 in P. schreberi and 0.79 mg kg−1 in P. commune in the vicinity of the chlor-alkali industry. To determine how long a load of Hg would remain in the mosses after mercury emitters restricted releases of Hg to the atmosphere, accumulation and desorption experiments were performed. We compared the two moss species collected from clean and moderately and heavily mercury-polluted sites. After eight days of exposure to mercury, P. schreberi accumulated up to 25 mg kg−1 of Hg, and P. commune accumulated up to 31 mg kg−1. Both in the field and in the experiment, P. commune accumulated significantly higher concentrations of Hg than did P. schreberi, most likely because of its surface morphology, which is likely to enhance the capture of metal from the atmosphere. After sixteen days of exposure, mercury changed the structure of the plasma membrane and affected organelles such as the nuclei and chloroplasts, leading to cell disintegration and death. The negative effects of mercury on the functioning of living cells appeared first in the older leaves of P. schreberi. After 64 days growing in the absence of Hg, P. schreberi clearly retained only 10–14% of the initially accumulated Hg, while P. commune retained 10–21%.

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