CHARACTERIZATION OF CONTAMINATION OF ANTHROPOGENIC ORIGIN ASSOCIATED WITH PB IN SANTO AMARO, BAHIA STATE, BRAZIL

The COBRAC (Brazilian lead mining Company), a subsidiary of the French company PENARROYA Oxide S.A. operated metallurgical facility from 1960 until 1993 in the city of Santo Amaro, Bahia, to produce ingots of lead ore from a mine in the municipality of Boquira, Bahia. From 1989 the company became 100% Brazilian and was named PLUMBUM Mining and Metallurgy LTDA. The industrial complex, located 300 m from the Subaé River, caused at the beginning of its operation a large die-off of plants and animals in the neighborhood due to pollutants emitted from the chimneys which were devoid of any type of filter. After demands of environmental agencies the company built a new, taller chimney with filters thus decreasing the amount of pollutants released. Together with the smoke, a metallurgy waste slag, considered innocuous in the 60s and 70s, was used without parsimony as pavement of streets and landfills, backyards and gardens made by throughout the city. This uncontrolled deposition increased the exposure of the population to contaminants contained in the slag, mainly lead and cadmium. In research developed by CPRM – the Geological Survey of Brazil in conjunction with UFBA- Bahia State Federal University in 2012 in the Subaé River basin, 43 samples of topsoil were collected from 0 to 20 cm depth, as well as 43 samples of subsurface soil, from depths of 20 to 70cm corresponding to the top of the B horizon. Background values were determined for 53 chemical elements showing that the lowest values occur in the High Subaé basin in the clay soils derived from sandstones of the Barreiras Formation when compared with the soil type named "vertissolo" derived from shales in the Lower Subae Basin. The elements Ba, Cd, Hg, P, Pb, S and Zn have average values, median and maximum values are much larger in the surface samples than in the B horizon samples, regardless of the soil type, contrary to the expected distribution with enrichment in the B horizon, confirming anthropogenic pollution with main source being theCOBRAC metallurgical plant.