| Volatile organic compounds (VOCs), a kind of common organic pollutants in the air, have complex composition. It is one of the main reasons causing the formation of acid rain, photochemical smog and haze pollution when reaction with other pollutants such as particulate matter in the air. In this paper, the VOCs in the airs of Guangxi beibu gulf economic zone, including Nanning, Beihai, Qinzhou and Fangchenggang areas, were chosed as the research objects. The hot stripping gas chromatography-mass spectrum was used for the qualitative and quantitative analysis of the ambient air samples.the status of VOCs in urban areas, industrial area and suburbs were systemicly studied, the main sources of VOCs in the air, the features of space distribution and the variations with time, and the health risk assessment were discussed. The main conclusions were as follows:(1) According to the Ambient air-Determination of volatile organic compounds (HJ 644-2013), the analytical conditions are determined with the actual situation. There are 22 kinds of volatile organic compounds has been determined, then the coefficient of correlation r2= 0.984～1.000, and the detection limit were 0.1～0.8μg·m-3, the recovery of standard addition were 99.0～108%, the relative standard deviation were lower than 8.9%.(2) Average total amou nts of VOCs in the beibu gulf economic zone were between 1.8 and 31.2μg·m-3.The average concentrations of VOCs in the air of the four cities were in the following order:nanning (14.2μg·m-3)>beihai (13.9μg·m-3)> qinzhou (9.8μg·m-3)> fangchenggang (6.1μg·m-3). The BTEX content, which was accounted for 79.2% of the volatile mass quantity, was the main pollutants of VOCs in the air. Toluene had the largest proportion and was accounted for 33% to 49% of total VOCs.(3) The variation feature of VOCs in the air of beibu gulf economic zone showed that the VOCs concentration in the air of inland was higher than that of coastal, and the concentration in the air of urban areas was higher than that of suburban. The variation tendency of VOCs concentration in different functional areas of each beibu gulf city was in the order:urban areas (17.5μg·m-3)> industrial area (9.72μg·m-3)> suburban (4.32μg·m-3). It was also showed that the VOCs concentrations in urban and industrial area decreased from west to east, and from the inland to the coast. The concentrations of VOCs in the beibu gulf economic zone in 2014 was higher than 2009. The concentration of VOCs had an increasing trend from winter, spring, summer and autumn in Nanning 2014. The concentration of VOCs was gradually decreased in Nanning 2015, the highest was in winter and spring, the lowest was in summer. It had a slight rebound in autumn, but highly limited.(4) The health risk assessment of VOCs in the airs of nanning, beihai, qinzhou and fangchenggang was carried out, respectively. The data showed that there was no significant difference in the health risk assessment results obtained in the four cities. The health risk was noncancer and accepted. The cancer risk value of tetrachloroethylene was lower than 1×10-6, which was acceptable. While it was showed that chloroform,1,2-dichloroethane and benzene had no significant cancer risk effect with the cancer risk value of 1 ×10-6-1×10-4. |
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