Delimitation of atmospheric isocontamination areas in the Universidad Nacional de Colombia campus by analysis of bioindicators (epiphytic lichens)

A map of areas of atmospheric isocontamination was elaborated in the campus of the university, using the bioindicator capacity of lichens to detect changes in air quality. Four areas of contamination were determined according to Le Blanc and De Sloover methodology (1970): maximum contamination, high contamination, moderate contamination and low contamination. The polluted areas for mobile sources are located towards the entrances located at 26 and 45 streets. The perimeter of the campus is also very polluted mainly towards the 38 and 30 avenues and 26 streets. The contamination of these areas relates with the absence of barriers or arboreal hedges in this perimeter. Fixed sources of contamination such as chimneys, exhausts, boilers and extractors of laboratories and the extended parking areas influence the areas of maximum contamination, to the interior of the university. Physicochemical measurements of fixed emissions are scarce or null for most of the cases. The less polluted sector of the campus is located towards its center as a result of the protective effect of groves and constructions, giving an effect of continuous barrier that blocks the external emissions efficiently