Identification of pollution sources by means of moss bags.

Moss bags containing Scleropodium purum were exposed for 30 days in an industrial area in which a chlor-alkali plant (CAP) and a concrete factory (CF) are located close to one another (121 m). Following the exposure, the transplanted mosses were analyzed to determine levels of Hg, Zn, Ni, and Cr. The enrichment factors (EFs) of the metals (final concentration/initial concentration) were calculated; the mean values obtained were 26.4 for Hg, 6.6 for Zn, 1.07 for Ni, and 1.0 for Cr. Dispersion of Cr and Ni was closely related, probably because they were dispersed together on the same particle. The spatial structure of the data was examined, and significant fits to the semivariograms were found for Hg, Zn, and Cr, using kriging to interpolate the data. Using this technique, it was possible to estimate where the maximum concentrations of elements occurred, allowing us to distinguish from which focal point they were emitted: Hg from the CAP, and Zn and Cr from the CF. The combined use of moss bags and geostatistical techniques allowed characterization of the emissions and identification of focal points of contamination in the study area.