汾河流域水系和表层沉积物中多环芳烃的空间变化规律及其生态风险研究

Spatial Variety and Ecological Risk of Polycyclic Aromatic Hydrocarbons(PAHs) in Water and Surface Sediments of Fenhe River Basin,China

本研究在汾河流域上、中、下游及其部分支流布设29个采样点,对其水体和表层沉积物多环芳烃(PAHs)的空间分布规律及生态风险进行了分析和讨论。结果表明,汾河流域水相中丰水期PAHs总量浓度范围是0.530~16.002μg·L^(-1),平均浓度为(2.738±3.078)μg·L^(-1),枯水期PAHs总量浓度范围是0.588~12.916μg·L^(-1),均值为(2.762±3.132)μg·L^(-1)。就空间分布而言,汾河流域整体呈现上游污染较轻,中下游污染严重的特点。PAHs的组成规律显示,丰水期和枯水期PAHs含量均以低环(2~3环)为主,不同采样期低环PAHs所占比例分别为96.5%和90.4%。与其他15个研究地区水体PAHs含量比较,汾河流域水体中PAHs污染程度的国内外对比处于中等到较高程度的污染。丰水期和枯水期水体中PAHs来源于石油源和植物、木材、煤的燃烧,主要受到流域煤化工、燃煤电厂排放污染物的影响。地表水健康风险评价结果显示,汾河流域丰水期和枯水期分别有13.8%和20.7%的点位存在一定的健康风险。汾河流域沉积相中16种PAHs平均浓度为(3.774±1.987)μg·g-1,其污染主要集中在流域中下游地区。PAHs的组成规律显示,PAHs含量集中在低环(2~3环),约占总量的75%左右。与本研究提到的河流、湖泊及港口沉积物中PAHs含量比较,汾河流域沉积物中PAHs污染程度仍处于中等偏高的污染水平。丰水期沉积相中PAHs以燃烧源和石油源为主,部分来自典型石油类产品的输入。表层沉积物生态风险评价结果显示,对于提出的12种PAHs的生态风险的效应区间低值(ERL值)或效应区间中值(ERM值)以及苯并(b)荧蒽(Bb F)和苯并(k)荧蒽(Bk F)这2类没有最低安全值的PAHs化合物来说,汾河上、中、下游流域均有采样点的PAHs可能存在着对生物的潜在生态风险。通过本研究可全面地了解该流域多环芳烃的空间分布规律及其可能的来源,并且为汾河流域多环芳烃污染的控制和生态风险评价提供科学依据。

The spatial variety and ecological risk of polycyclic aromatic hydrocarbons （PAHs） in water and surface sediments were analyzed based on 29 samples collected from upstream region to downstream region, as well as some of its tributaries of Fenhe River Basin. The results showed that the average concentrations of PAHs in waterbody were （2.738±3.078） μg ·L^-1 and （2.762±3.132） μg· L^-1 in wet and dry season, respectively. The total PAHs concentrations ranged from 0.530 to 16.002 μg· L^-1, and from 0.588 to 12.916 μg ·L^-1 in wet and dry season, respectively. The spatial distribution of PAHs indicated the slight pollution in the upstream and the severe pollution in the middle and lower reaches. The low molecular weight PAHs （2-ring and 3-ring） were the most common components in waterbody both in wet and dry season with the ratio to the total PAHs by 96.5% and 90.4%, respectively. Comparing with other 15 areas in the world, PAHs concentration in waterbody of Fenhe River ranged from moderate pollution to higher pollution. The results from the source analysis of PAHs suggested that petroleum PAHs and the combustion of plants, wood and coal were the main source both in wet and dry season. The possible reasons were the discharges of coal chemical industry and power plants. The results of ecological risk assessment 13.8% and 20.7% of the whole sampling sites showed the potential health risk in waterbody in wet and dry period, respectively. The average concentration of total 16 PAHs in sediment was （3.774±1.987） μg ·g^-1, which occurred mainly in the middle and lower reaches of the Fenhe River. The low molecular weight PAHs （2-ring and 3-ring） were the most common components in sediment with the approximate ratio of 75% to the total PAHs contents. Comparing with other areas in the world, PAHs concentration in sediment of Fenhe River reached higher pollution. The PAHs in sediments were mainly from the incomplete combustion of coal and wood, and partly from petroleum in wet season. The results of ecological risk assessment in surface sediment showed potential ecological risk for creatures based on reference to ERM value or ERL value for 12 PAHs, as well as the existence of BbF and BkF.