Sources And Fate Of Polycylclic Aromatic Hydrocarbons (PAHs) In Air Of Hangzhou

Polycyclic aromatic hydrocarbons (PAHs), a kind of POPs are ubiquitous in air, contributing more than 1/3 of the total carcinogenic chemicals, with the source of oil-leak, traffic emissions, environmental tobacco smoke, fuel-burning, cooking oil-fumes, and, so on. PAHs pollution in air emphasized threat on the whole human. And the understanding of occurrence, sources and fates for PAHs in environment is the basis of controlling POPs pollution efficiently, thus reducing personal intake and protecting human health.In China, rapid economic development has lead to heavy air pollution, especially in major cities, although with the government effective measures.The paper took Hangzhou as a case, firstly had a comprehensive investigation into PAHs pollution in indoor and outdoor air with occupational and non-occupational PAHs intakes through breath. Then fate for PAHs in arterial air including dry, wet deposition, runoff and exchange of PAHs between air and road dust was emphasized. Deep-insight into PAHs production, characteristics in discharges and affecting factors were achieved for the dominant PAHs sources, such as traffic discharges, cooking practice, tobacco smoke and coke plant, consequently to determine the first PAHs sources fingerprints, providing detailed source information for source analysis. At the same time, it was also helpful to cut PAHs production from sources. A new parametre was established to conduct source analysis for Sediment. The main conclusions were below:(1) Conventional cooking practise have leaded to heavy PAHs pollution in kitchens air. Average PAHs pollution in commercial kitchens air were 17.23 ng/m3 with BaP all exceeded the national air standard. Residential kitchens presented an mean PAHs concentration of 7.634 ng/m3 and 83% BaP exceeded the limitation.(2) Fate of PAHs in air was discussed with the result shown, dry deposit mostly cleaned 4-5 ring PAHs, while wet deposit emphasized on 3 ring PAHs. Runoff had a larger contribution to low-molecular-weight PAHs in waterbody than high-molecular-weight PAHs. Air was the chief reserve for 2-ring PAHs, and 3-4 ring PAHs in air may entered waterbody through many routes. Road dust was home for 4-5 ring PAHs in air.(3) PAHs fingerprints for typical sources were achieved. Characteristics anddeterminate factors of PAHs discharge from typical sources was investigated. PAHs in oil fume were dominated by cooking practise, oil type and temperature. Frying and roasting produced much more PAHs than boiling. In the studied three edible oil, lard oil produce least PAHs followed by soybean oil and seed oil with good relation to oil temperature. PAHs in traffic emissions were in good relation to oil consumed, mileage. Diesel engine emit more PAHs of less toxic, compared to gasoline engine. 2-4 ring PAHs is predominant in diesel engine emission, accounting for 97% of the total PAHs. In gasoline engine discharges, 4-ring PAHs were the most predominant, having 58% contributions. 2-3 ring and 5 ring PAHs accounting for 19% 10% 13%, respectively for total PAHs. Vehicle of longer mileages discharged more toxic PAHs. PAHs in tobacco smoke were in good relation to tar content, having nothing to do with nicotin content.(4) A new parameter was introduced to source analysis for PAHs in sediment, with the result showed that, PAHs in sediment from Qiantang River, West Lake and Inland river mainly came form oil-leak, and PAHs in canal mostly came from ship-engine discharges.