Comparative biomonitoring of atmospheric quality in five zones of Córdoba city (Argentina) employing the transplanted lichen Usnea sp.

The lichen Usnea sp. was transplanted to five zones plus a control one in the city of Córdoba, with different levels of industrial and traffic pollution. The chlorophyll a+b, hydroperoxy conjugated dienes, malondialdehyde concentration, chlorophyll b/chlorophyll a, phaeophytin a/chlorophyll a, DW/FW ratio and sulfur accumulation were determined. A pollution index (PI) was calculated to compare the air quality of the zones biomonitored. It was observed that the content of chlorophylls a+b increased parallel to the level of pollutants emitted by traffic, but at the same time, there was an increase in the degradation of chlorophyll a. These results indicate that chlorophylls would be affected by air pollutants emitted by traffic and as a compensatory mechanism the lichen would increase their synthesis. Significant differences were observed in hydroperoxy conjugated dienes concentration and sulfur content in samples transplanted to high traffic level sampling points. At the same time, a higher sulfur content was observed in lichens transplanted to sampling points located in downtown, in neighboring areas or with high industrial level, suggesting an additive effect of industrial with traffic pollutants. PI results allow us to differentiate areas with different air quality in the city, the highest pollution levels being observed in the downtown area with high traffic. Two other areas near downtown with high traffic are also in this category. Except for downtown and a far away zone with high industrial density, the other areas showed higher PIs at high traffic sites. The lowest PIs were observed in the control zone and at the low traffic sampling points.