ECOLOGICAL RISK ASSESSMENT OF HEAVY METALS FROM ROAD DUST IN IASI, ROMANIA

The increased level of heavy metals in urban environment, especially in urban air and street dust becomes a health threat for the inhabitants. This work presents the results of ecological environmental risk induced by heavy metals in samples of urban dust from Iasi city. 12 samples of dust from the roads of Iasi City were collected in late March 2016 and analyzed with an LA-ICP-MS system for 13 heavy metals that are potentially toxic in the environment (Ag, As, Ba, Cd, Co, Cr, Cu, Mn, Hg, Ni, Pb, V and Zn). Results were compared with the thresholds in the Romanian legislation. From the 13 elements, 7 are found in concentrations bellow the normal values in soils. The elements exceeding the threshold are As (5.5 mg/kg), Cr (263 mg/kg), Cu (79.9 mg/kg), Ni (92.3 mg/kg), Pb (40.2) and Zn (2453 mg/kg). The main sources of heavy metals in urban street dust are the emissions from transport. Heavy metals emissions from road transport have their source from fuel burning, engine oil, tyre wear, brake wear and road abrasion. Assessment of the ecological risk of heavy metals found in the urban dust was done using the Hakanson Potential Ecological Risk Index (HPERI). This index takes into consideration the heavy metal concentration in a sample, the reference concentration anda biological toxicity factor for each element. The results of the HPERI showed that 8 out of the 12 samples have a moderate ecological risk. Also, comparing the 13 elements, with the highest ecological risk is Zn, followed by Ni, Cr, Pb and As.