Source Apportionment of PM_(2.5)Bound PAHs in Tropical Tiruchirappalli City,India

摘要

The aim of this study is to investigate the distribution and sources of polycyclic aromatic hydrocarbons(PAHs)as per the priority list of USEPA,bound to fine particulate matter(PM_(2.5))prevalent in Tiruchirappalli,an urban city of India.The sampling was carried out for 24 h continuously in each station to study the PM_(2.5) deposition.The PAHs deposited on the filter paper was estimated using ultrasonic centrifuge solid-phase extraction method and further analyzed with gas chromatography mass spectroscopy(GC-MS).The results showed that the range of PAHs concentrations in the study period was between 1.0 and 90.20 ng/m~3.The seasonal variation of all the 16 PAHs varied from 38.78 ng/m~3 in monsoon,32.06 ng/m~3 in winter,12.54 ng/m~3 in summer and 8.88 ng/m~3 pre-monsoon.The annual average concentration of PAHs observed was 22.51 ng/m~3 with PAHs of higher molecular weight in abundance accounting for almost 90.81 % while the PAHs of lower molecular weight contributing to 9.23 %.Higher PAHs levels of 35.41 ng/m~3 were recorded during cold months followed by 10.71 ng/m~3 during warm months.Diagnostic ratio source analysis and principal component analysis established that vehicular emissions and off-road combustion sources were the major sources.The mean benzo(a)pyrene toxicity equivalent calculated for samples was 2.83 ng/m~3 and the mean contribution of the carcinogenic potency of benzo(a)pyrene was observed to be 41.13 %.