Arsenic dispersion over Central Chile assessed through forward and inverse modeling

We investigate the atmospheric transport of arsenic (As) emitted from a copper smelter and its potential impact on the air quality of the city of Santiago (33.5ºS, 70.8ºW, 500 m.a.s.l), with 5x106 inhabitants. Santiago is located in a basin in the central part of Chile bounded by the high Andes (4500 m altitude on average) to the east, a lower parallel mountain range to the west (1500 m altitude on average), and two east-to-west mountain chains to the north and south of the basin respectively. Anthropogenic arsenic is emitted to the atmosphere in connection with the smelting of metals such as gold and copper, coal combustion and herbicide use. The main single As source in Central Chile is Caletones (34º05'S, 70º27'W, 2400 m.a.s.l.) located some 150 km south of Santiago, with an emission rate of 1200 ton As/yr in 2000. There is some evidence that the influence of Caletones on the air quality of the Santiago basin increases in connection with intensive coastal lows (CLs), which are synoptic disturbances that bring down the subsidence inversion. However, the scarcity of observations representative of the regional-scale transport patterns, the complex topography of the area where Caletones is located and over which dispersion occurs, the extreme stability reached during CLs make it necessary to better assess the transport processes potentially responsible for these impacts. Here we assess this by means of inverse and forward modeling