Trace Metals in Atmospheric Particles

Abstract

Samples of PM2.5 and PM10 were collected at urban and rural sites in Agra, India and sequentially extracted for chemical fractionation of major crustal elements (Na, K, Ca, Mg) and some heavy metals (Si, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn,V, As). The metals were analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES) in each fraction. The annual average mass concentrations of PM10 at urban and rural site were 179.3±31.7 and 144.7±41.3 and#956;g m-3 while the annual average mass concentrations of PM2.5 at urban and rural site were 112.1±50.3and 97.8±41.7 and#956;g m-3, respectively. Seasonal variation of both PM2.5 and PM10 were characterized by high levels in winter followed by post-monsoon, summer and monsoon. Si, Fe, Mg, Na, K and Ca had high concentrations (174-30700 ng m-3) while Cd, As, V, Ni, Mn, Cr, Pb, Cu and Zn had lower concentrations (7.8-652 ng m-3) at both sites. The significant seasonal variations of elements were observed. Four major sources of elements, i.e., industries/road traffic, soil dust, coal/fuel oil burning in PM10 while three major sources of elements, i.e., industries/road traffic, soil dust, biomass/coal/fuel oil burning in PM2.5 were identified using source apportionment models (PCA/APCS and PMF). The higher percentage of Na, K, Ca and Mg was found in the soluble and exchangeable fraction (F1), while higher percentage of most of metals was found in residual fraction (F4). Contamination factors (CF), risk assessment code (RAC) and enrichment factor (EF) were estimated to assess the environmental risk and to distinguish sources of elements. This study evaluated the potential hazard to young children (0-7 years) due to exposure to lead using the U.S. EPA Integrated Exposure Uptake Biokinetic (IEUBK) Model. Non-carcinogenic and carcinogenic risks were assessed for infants, toddlers, children, teens and adults. Inhalation was the major pathway of metal exposure followed by ingestion and dermal contact. No carcinogenic and non-carcinogenic risks were observed for all age groups through ingestion and dermal contact. For inhalation exposure, HI value of Cd, As and Ni was higher than 1 for all age groups in PM10 at urban site while at rural site in PM10 HI value of only Cd was higher than 1. The carcinogenic risk via inhalation exposure for all age groups to As in PM10 samples at urban site was above the acceptable level (1×10and#8722;4). newline