岩溶地下河水中多环芳烃、脂肪酸分布特征及来源分析

为探究重庆青木关岩溶地下河水中多环芳烃(PAHs)和脂肪酸的含量组成、分布特征、来源及污染水平,2013年雨季和旱季分别于地下河中进行水样采集,并利用气相色谱-质谱联用仪(GC-MS)对水样中PAHs和脂肪酸的组分进行定量分析.结果表明,青木关地下河水中PAHs和脂肪酸的含量范围分别为77.3~702 ng·L~(-1)和3 302~45 254 ng·L~(-1).组成上,PAHs以2~3环为主,其比例高于90%,脂肪酸碳数范围为C10~C28,以饱和直链脂肪酸为主,其次为单不饱和脂肪酸.分布特征上,雨季:地下河水中各采样点PAHs的含量差异较小,脂肪酸的含量在入口、出露处和出口呈现依次降低的趋势,其中出露处和出口脂肪酸的含量较为接近;旱季:地下河水中PAHs含量在入口、出露处和出口呈现先降后升的趋势,脂肪酸含量在各采样点较为接近.总体上,地下河水中PAHs和脂肪酸的含量都表现为雨季显著高于旱季.来源分析表明,青木关地下河水中PAHs主要来源于该河流域煤和木材、农作物秸秆等生物质的燃烧;脂肪酸主要来自该河流域内硅藻、绿藻等水生藻类和细菌,其中以水生藻类的贡献占主导.地下河水受到PAHs中轻度污染,相对于旱季,雨季污染更严重.

Distribution Characteristics and Source Identification of Polycyclic Aromatic Hydrocarbons, Fatty Acids in Water of Karst Underground River

In order to explore the contents, composition, distribution characteristics, sources and pollution level of polycyclic aromatic hydrocarbons(PAHs) and fatty acids in water of Qingmuguan karst underground river in Chongqing, water samples were respectively collected from underground river in rainy season and dry season, 2013 and polycyclic aromatic hydrocarbons, fatty acids of the water samples were quantitatively analyzed by Gas Chromatography-Mass Spectrometer(GC-MS). The results showed that the contents of PAHs and fatty acids in water of Qingmuguan karst underground river ranged from 77.3 to 702ng·L^-1 and 3302 to 45254 ng·L^-1, respectively. In terms of composition, the PAHs profiles were dominated by (2-3) rings PAHs in water samples, which accounted for more than 90% of the total PAHs contents, while the carbon numbers of fatty acids ranged from C₁₀ to C₂₈, and fatty acids profiles were dominated by saturated straight chain fatty acids, followed by mono-unsaturated fatty acids. In terms of the distribution characteristics, the contents of PAHs had minor difference at each sample point in water of underground river in rainy season. At the entrance, exposed and exits, the contents of fatty acids reduced in turn, moreover the contents of fatty acids were close at the exposed and exits. dry season:at the entrance, exposed and exits, the contents of PAHs in water of underground river decreased firstly and then increased. The contents of fatty acids were close at each sample point in water of underground river. As a whole, the contents of PAHs and fatty acids in water of underground river in rainy season were significantly higher than those in dry season. Source analysis indicated that the PAHs in water of Qingmuguan underground river were mainly originated from the combustion of coal and biomass (wood, crop straw, etc) at the underground river catchment. The fatty acids were mainly originated from aquatic algae (diatoms and green alga, etc), and bacteria, with the contribution of aquatic algae dominated. The water of underground river was suffered the middle to mild pollution by PAHs, and compared with the dry season, the rainy season was more severely polluted.