ASSESSMENT OF HEAVY METALS CONTAMINATION OF SOILS IN THE ZLATNA AREA USING THE MULTIPLE POLLUTION INDEX

In the Zlatna area of the Apuseni mountains of Romania, a mineral processing plant and smelter have been in function for several decades. Along this long period, large amounts of gaseous emissions (SO2, SO3, NOx) were released into the air, and particles rich in heavy metals fell on the ground. This long period of mining and smelter-refinery process caused heavy metals contamination of soils in this area. In order to assess the cumulative effect of heavy metals pollution in the Zlatna area, the multiple pollution index (MPI) was calculated. This index is the ratio between the soil heavy metal content, actually determined by chemical analysis, and a reference value obtained by calculation for each sample. The study of pollution index revealed the following: near the pollution source, the multiple pollution index is maintained in the excessive pollution class for the both study depths; the median value of this index decreases from very severe pollution class to severe pollution class in the second layer. The spatial distribution highlighted the decrease of this index with the distance from the pollution source, decrease provided statistically in the first two layers.