Study of atmospheric dispersion of pollutants in the industrial region of the Sado estuary using biomonitors

The region of Lisbon and south of Lisbon (Sado estuary) is densely industrialised, and therefore air pollution should be studied in a more detailed scale there. Also the topography of the Sado estuary region and the predominant wind direction from the north-west contribute to the influence of the industries located in the north onto this region. The region selected in this work includes a oil-fired power station. Transplants of the lichen Parmelia sulcata were suspended in nylon bags in a region within a rectangle of 15 km wide and 25 km long on a grid 2.5 km x 2.5 km, centred in a oil powered station. In each of the 47 places two sets of four transplants each were hung. Care was taken i) in covering the sets with a polyethylene roof to prevent leaching of elements in the lichen, ii) in building a hanging system which could rotate according to the wind direction, iii) in orienting one set towards the wind and the other set against the wind. For a 9 month period and every three months, one transplant of each set was collected. We have no knowledge of any other study on differentiation elemental uptake of Parmelia sulcata where the component wind direction is taken into account. Some information on local and distant sources is expected to be accessible. The transplants were analysed by INAA. Contents on Cl, Na, Ca, V and Zn are mapped and discussed. (author)