Evaluation of Trace Elements and Aerosols in Air and Their Effects on Urban Environment of Punjab Area in Pakistan

Abstract

Sampling of the aerosol particulates was carried out in the atmosphere of Lahore, Faisalabad, Rawalpindi, Islamabad, khanispur, wah cantt, Sheikhupura and Gujrawala areas by using high volume portable dust sampler model L-30 MK III of Rotheroe and Mitchell Company (Ltd.) U.K. The total suspended particulate matter (TSP) and their size distribution in the atmosphere of the above mentioned areas were studied by making use of gravimetric and scanning electron microscopic techniques. The ratio-active material in the aerosol particulates in these cities was studied by using solid state nuclear track detector CN-85 for the estimation of α-emitting ratioactive particulates, while direct measurement of ϒ-rays emitters from sampled filter paper was carried out by using intrinsic germanium crystal detector with 17.6cm3 active area, a number of amplifiers and 4096 channel analyzer, CANBERRA series 85. Trace elemental composition of the aerosol particulates in the atmosphere of Punjab and from the mild steel welding electrodes was carried out by using neutron activation analysis (NAA), inductively coupled plasma atomic emission spectrometry (ICP-AES) and atomic adsorption spectrometric (ASS) techniques. The pH, conductivity, Na+, K+, Ca++,Mg++, Cl-, NO3-, SO4-2 and HCO3- were studied for various precipitation events and the results were compared with each other. The trace elements of Ni, Pb, Cd, and Hg in the precipitation events were studied by using ICP-AES techniques. Distribution of trace elements in aerosol particulates at different heights was studied by NAA in the atmosphere of Sheikhupura industrial area. The elements studied in the area of Punjab were Ce, Yb, Se, Cr, Hf, Cs, Sc, Rb, Fe, Co, Eu, La, Sb, Mo, Ba, Zn, Hg, Na, Gd, Sm, Nd, In, Pb and Cd. Interesting information was obtained with regard to the total suspended particulate matter (TSP) and size distribution of aerosol particulates in the atmosphere of the Punjab areas. The amount of TSP in the atmosphere of Punjab in working days was more than maximum permissible limits set by US-EPA. Relatively high amount of TSP was observed in atmosphere Islamabad during non-rainy days in the vicinity to the industrial area G-9/3 sector, however this amount is decreased after rain fall. A few pollens along with pulverized fly ash were observed in various areas. But some oil mist and fine oval shaped aerosol due to ordnance factory and cement industry were found in the atmosphere of Wah cant. Trace elemental analysis of the aerosol particulates in the atmosphere of the Punjab indicates that some of the elements like Ce, Yb, Hf, and Rb were present due to the characteristics of nature of that area while Co, Fe, Sc, Cs, Se and Cr were anthropogenic elements and represent some industrial activities in these areas. Eu, Na, Gd, Sm, Ba, and Nd elements were linked to the soil derived aerosols while La, Sb, Mo, Zn, Hg, Br, Pb, and Cd were considered to have originated through burning of fossils fuel and vehicle exhausts. Trace elements were found within the permissible limits, except for industrial areas of Shiekhupura, where Co, Cr, Cs, Eu, Fe and Sc were more than the average values of urban areas of the Punjab. Trace elemental analysis of the aerosol from the mild steel welding electrode indicates that very harmful elements like Cr, Co, Br, As, La, and Sb were present in high concentrations which may cause a serious health hazards to the welders. Analysis of the precipitation events indicates that the carbonates were dominant over the sulphates and hence the Ph of the most of precipitation events was basic in the atmosphere of Lahore and Sheikhupura. The amounts of toxic gases in the atmosphere of urban and industrial areas i.e SO2, CO, and NO2 were within the permissible in industrial area of Sheikhupura.