Influence of the physicochemical characteristics of pollutants on their uptake in moss Z. Varela a, * , J.A. Fern  andez b , C. Real b , A. Carballeira a , J.R. Aboal a a  Area de Ecología, Departamento de Biología Celular y Ecología, Facultad de Biología, Univ. Santiago de Compostela, 15782 Santiago de Compostela, Spain b  Area de Ecología, Departamento de Biología Celular y Ecología, Escuela Polit ecnica Superior, University Santiago de Compostela, 27002 Lugo, Spain highlights  Physicochemical characteristics of elements determine their uptake in moss.  Factor analysis identifies groups depend on elements binding properties.  Ionic and covalent nature of elements determines the radicals which they bind to. article info Article history: Received 30 July 2014 Received in revised form 25 November 2014 Accepted 27 November 2014 Available online 27 November 2014 Keywords: Biomonitoring Factor analysis Heavy metals Pseudoscleropodium purum abstract Bryophytes are commonly used as biomonitors to estimate the atmospheric deposition of heavy metals and metalloids. However, the tissue concentrations of these elements in moss do not always accurately reflect atmospheric levels. The aim of the present study was to investigate whether element uptake in moss is affected by the physicochemical characteristics of the elements. Factor analysis was used to identify any patterns of covariance in the accumulation of elements in samples of the moss Pseudo- scleropodium purum collected from the surroundings of different factories and from control sites. The variation in the concentrations of elements was similar in moss from both types of sites and was related to the binding properties of the elements. This suggests that the physicochemical characteristics of the elements determine the uptake of metals and metalloids from the atmosphere. Therefore, in studies that use multiple correlations among elements as indicators of a common origin of contaminants, erroneous conclusions may be reached by overlooking the adsorption properties of the moss. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Since the moss biomonitoring technique was first reported (Rühling and Tyler, 1968), bryophytes have been widely used as biomonitors to estimate the atmospheric deposition of heavy metals and metalloids. However, the concentrations of elements in moss samples do not always accurately reflect the atmospheric deposition of these elements (Aboal et al., 2010): the tissue burdens will not only depend on the amount of a particular contaminant in the atmosphere, but also on the physicochemical characteristics of the contaminants and the uptake processes. Although numerous biomonitoring studies have been carried out with moss, relatively little is known about the specific physi- cochemical mechanisms involved in the bioadsorption processes, in comparison with those in other organisms (algae, bacteria, fungus, plants; Gonz alez and Pokrovsky, 2014). In fact, there are no reports in the available literature about how the physicochemical charac- teristics of contaminants and of the uptake processes in mosses might affect the bioconcentration of different atmospheric con- taminants. Aspects such as the amount of a contaminant emitted by factory and the type of emission (gaseous or particulate, particle size, etc.) may have important effects on the uptake process. The physicochemical processes in mosses include aspects such as the affinity of contaminants for cation exchange sites (Nieboer and Richardson, 1980), competition by metals or metalloids for cation exchange sites (Couto et al., 2004) and synergistic uptake of con- taminants (Sun et al., 2009). Therefore, the objective of the present study was to determine whether the uptake of elements by moss is influenced by the physicochemical properties of the elements. Factor analysis was carried out with the aim of identifying any patterns of covariance in * Corresponding author. E-mail address: zulema.varela@usc.es (Z. Varela). Contents lists available at ScienceDirect Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv http://dx.doi.org/10.1016/j.atmosenv.2014.11.061 1352-2310/© 2014 Elsevier Ltd. All rights reserved. Atmospheric Environment 102 (2015) 130e135