Applicability of in situ or transplanted lichens for assessment of atmospheric pollution in Patagonia, Argentina

This study is part of a project, in which the ultimate aim is to evaluate the applicability of lichens to assess atmospheric pollution in urban and in agricultural areas in northern Patagonia (Argentina). Two cities with different characteristics were selected for the evaluation: San Carlos de Bariloche, a touristic city, and Villa Regina, a city surrounded by agricultural areas, both located in Rio Negro Province. Different methods were considered, with comparative purposes, and aiming to detect the most suitable to evaluate atmospheric pollution in the area of relevance for the present project. The Index of Atmospheric Purity (IAP) was calculated; IAP values were mapped and lines of iso-contamination were drawn for both cities. Furthermore, they were compared with data of multi-elemental composition of lichen thalli analyzed by instrumental neutron activation analysis (INAA). The results indicate that the IAP is an accurate method to detect and evaluate atmospheric pollution in Bariloche, a result that can be extended to other cities with similar characteristics within the lake area of Patagonia. Instead, the index showed to be not appropriate for use in fruticulture areas, even when bio-accumulation of pesticides in transplanted thalli was detected, in the preliminary tests that have been done. As an alternative method, detection of algal layer vital signs, by red neutral staining of algae of in situ lichens and by electrical conductivity were also evaluated in preliminary tests; the results obtained could be related with the fumigation intensities.