Lichen Usnea barbata as biomonitor of airborne elements deposition in the Province of Tierra del Fuego (southern Patagonia, Argentina)

Lichen Usnea barbata was tested as a possible biomonitor of atmospheric deposition in a supposedly pristine environment Tierra del Fuego (Argentina). Lichen samples were collected in 2005 and again in 2006 in 71 sites covering almost the entire region. The aim of the study was to evaluate the bioaccumulation of 26 elements in order to define the background levels in the region. The quantification was carried out by the sector field inductively coupled plasma mass spectrometry. No relevant temporal accumulation patterns between 2005 and 2006 sampling campaigns were observed. Then, the results were submitted to multivariate statistical analysis (cluster and principal component analyses). Cluster analysis produced a dendrogram where the 71 sites were divided into four clusters at (Dlink/Dmax)100<30. The areas and the elements were correlated according to the element concentrations by principal component analysis. Four significant components that accounted for 67% were obtained. Cluster 1 was mainly composed of sites of Ushuaia–Road 3 (E area) and it was characterized by high levels of Cd, Co, Ni, Pb, Sb, and W in lichens.The present study has revealed the good capacity of U. barbata to reflect the baseline levels of elements in the environment at a regional scale level. The presence of certain level of elements in lichens agrees with the hypothesis that Tierra del Fuego is not a relatively pristine environment as occasionally supposed. However, when comparing our results with other countries, Tierra del Fuego lichens have a very low content of the measured elements.