| Polycyclic Aromatic Hydrocarbons(PAHs) is a common and persistent organic pollutants in the environment. PAHs is composed of two or more than two of the benzene ring and its source is mainly incomplete combustion of oil, coal, wood, organic compounds and other. PAHs that can be enriched in water, soil and organism are harmful on the environment and human health. Therefore, a sensitive and efficient method for detection of PAHs is established, and its source is analyzed, which can effectively control the emission of PAHs and achieve the purpose of protecting the environment and human health.In this paper, snow and ice collected in Hailuogou in January 2015 are taken as research objects. The snow melt water and suspended particles are separated by sand core filtration apparatus. After separation, collecting snow melt water into the suction bottle and particulate matter onto glass fiber membrane, the aim was to determine the content and distribution characteristics of dissolved and adsorbed PAHs in ice and snow. The dissolved PAHs were enriched by C18 solid phase extraction of disk membranes. The PAHs in particles was enriched by ultrasonic extraction, and the extraction conditions were optimized including the type of the extraction agent, the dosage of the extraction agent and the ultrasonic time. Across high resolution and high sensitivity appraisal ability of GC-MS/MS, after optimizing instrumental conditions and chromatographic conditions, and this method that GC-MS/MS detected different forms of PAHs in ice and snow in Hailuogou is established. The GC conditions were as follows: AB-5MS capillary column( 0.25 mm×0.25 ?m×30 m), inlet temperature of 300 ?, no shunt; Heating procedures : the initial temperature of 50 ?, after 2 min, increasing to 300 ? to at the speed of 6 ?/min, keeping 5 min; The MS/MS conditions: EI source(electron impact source), electron energy= 70 ev, transmission line temperature was 280 ?, ion source temperature was 250 ?, solvent delay time was 10 min, collision gas is argon, scanning in SRM mode, the scanning range of quality was 50-500. And By MS/MS conditions, ion cluster of 16 PAHs and the optimal collision can be determined.Naphthalene content is standard for standard curve of 16 kinds of PAHs, linear range in 0.001~1 ?g/L, correlation coefficient R2= 0.9990~0.9998. The recovery rate of 16 kinds of dissolved PAHs was 82.9%~98.1%, RSD= 1%~1.4%,LOD= 0.0006~0.0033 ?g/L. The recovery rate of 16 kinds of adsorbed PAHs was 73%~98%, RSD= 1.9%~13.8%,LOD= 2.75~831.7 ng/L.Across the best experimental conditions, the different forms of PAHs sourcing snow and ice samples at three different altitudes in Hailuogou was successfully detected in the experiment. The analysis results show that the average content of dissolved PAHs was 0.0015~0.062 ?g/L?0.0011~0.046?g/L?0.0016~0.043 ?g/L. the average content of adsorbed PAHs was 10.58~754.25 ?g/L?18.83~312.23 ?g/L?5.58~326.53 ?g/L. The 2~3 ring accounting for the total amount of 82%~85% is the main form of dissolved PAHs, 4 ring PAHs content is 12%~15%, and the content of naphthalene was the highest, followed by phenanthrene. However, only 3 kinds of PAHs which was over 4 ring with high molecular weight were detected. The data shows that the dissolved PAHs which is mainly composed of low ring PAHs is easy to migrate with the atmosphere, and the PAHs adsorbed on the particulate matter is mainly composed of the high ring PAHs. Using ratio method to analyze the source of PAHs, according to the ratio of characteristic compounds, the sources of dissolved and adsorbed PAHs are belong to the mixed source of coal combustion and automobile exhaust. |
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