淮河上游多环芳烃的多介质污染特征与归趋

Polycyclic aromatic hydrocarbons (PAHs) containing two or more fused benzene rings are widely distributed persistent organic pollutants in various environmental media including organisms. Due to their persistent, toxic, mutagenic and carcinogenic properties, some of PAHs are on the list of US EPA priority pollutants. Anthropogenic sources of PAHs in the environment could be separated into pyrogenic and petrogenic origins. Combustion of biomass and fossil fuels in vehicular engines and power plant, coke production, and incineration of industrial and domestic wastes generates pyrogenic PAHs, while producing activities of petrogenic PAHs include the oil spills and petroleum re?ning, etc. Once PAHs were produced, they can be widely spread into the environment through atmospheric deposition and stream pathways, and eventually accumulate in aquatic sediments. The upper reach of Huaihe River Basin locates in Henan province and flows across extensive agricultural regions. In addition to being used for agriculture, Huaihe River is the main source of drinking water and industrial water in this basin. With the rapid growth of economy and urbanization, more and more wastes are discharged into the river. PAHs originated from incomplete combustion or pyrolysis of oil, gas, coal and wood could be transported into Huaihe River through runoff from non-point sources, atmospheric deposition, industrial discharge and other means. Potential adverse biological effects on ecosystems of residue PAHs might occur even with low dose of PAHs in this basin. Therefore, more investigations on the PAHs residues in upper reach of Huaihe River, such as atmosphere, water, SPM and sediment are imperative and necessary. The concentration, distribution, and sources of PAHs in different environmental media of this basin (such as water, suspended particulate matter, sdiments, atomsphere, fish etc) were completely analyzed and the composition characteristics of PAHs were discussed. The major sources of sedimentary PAHs in upper reach of Huaihe River were identified and their contributions were apportioned using diagnostic ratios and receptor models including PCA/MLR, PMF, UNMIX. The ecological risk assessment for each identified source category was quantitatively calculated by combining the BaP equivalents (BaPE) values with estimated source contributions. Additionally, the health risks of PAHs in this catchment were assessed. Based on field sampling data, distributions, transfer and fate of PAHs in various media are simulated through a dynamic fugacity model. This project provides a comprehensive study on the characteristics of contamination, transfer and fate of PAHs in various environment media in upper reach of Huaihe River. All the investigation would apply as the scientific proof for pollutant control of water in upper reach of Huaihe River, construction of POPs database and environment management.

多环芳烃是一类在环境中普遍存在的有机污染物，由于其毒性/致癌性、生物累积性和半挥发性并能在环境中持久存在，有16种PAHs被美国环保局列为优先控制污染物。河流中的水、沉积物、悬浮物以及水生生物，是PAHs的主要载体和最终归宿之一。本项目以淮河上游为研究对象，拟通过对水-悬浮物-沉积物、鱼类、水生植物、大气与降尘中PAHs的分析，揭示该河段主要介质中PAHs的污染水平，通过特征比值、PCA/MLR、PMF、UNMIX解析PAHs的来源，评估PAHs污染的生态与健康风险，进而构建该河段PAHs的Ⅳ级多介质逸度模型，模拟PAHs的分布、迁移与归趋特征，计算PAHs的输入、输出通量以及系统内部跨界面迁移通量，阐述对各环境介质中PAHs浓度影响较大的重要参数。本研究可为深入了解淮河上游水生态系统中PAHs的环境行为模式、准确评价PAHs的生态与健康风险，有效防治河流PAHs污染和环境管理提供理。

本项目以淮河上游为研究对象，测定了大气与降尘、水-悬浮物-沉积物、鱼类、水生植物中PAHs的含量。结果表明：淮河上游水相ΣPAHs浓度范围是80.0~421 ng/L，3环PAHs为主；悬浮物中ΣPAHs浓度范围是268~2817 ng/g，2环PAHs为主；表层沉积物中PAHs的浓度范围是3.96~379 ng/g，3~4环PAHs为主。因子分析/多元线性回归揭示淮河上游PAHs主要来源于化石燃料的燃烧（贡献62.0%）。采用同位素定年方法，第一次高分辨地分析了淮河上游PAHs的污染历史，表明从1912~2014年，柱芯沉积物ΣPAHs浓度变化范围为2.31~21.86 ng/g，平均沉积速率是0.58 cm/年，TOC和BC的含量对PAHs的浓度有一定的影响。PCA/MLR显示PAHs主要来源于化石燃料的燃烧且贡献率为60.1%。采用概率密度重叠面积法和安全阈值法评价了淮河上游水体中ΣPAH7对水生生物的联合生态风险，淮河上游水相、悬浮物和沉积物中ΣPAH7对水生生物的风险大小是沉积物相 > 悬浮物相 > 水相。气相样品和颗粒相样品中ΣPAHs总浓度范围分别为3.61～425 ng/m3和483～25365 ng/g，3环PHE是浓度最高的化合物。气相和颗粒相样品ΣPAHs浓度的最大值出现在冬季。在气相样品中，冬季以2环和3环PAHs为主，春夏季以4-6环PAHs为主；在沉降颗粒样品中，不同季节均为低环PAHs为主。PAHs的沉降通量范围为52～2071 ng/m2/d, ΣPAHs沉降通量的最高值和最低值分别出现在冬季、春季，高环数PAHs的沉降通量较为显著。淮河上游水生植物ΣPAHs的含量范围为2.55 ng/g-208 ng/g，以3环PAHs为主，PHE含量最高（208 ng/g）；无脊椎动物∑PAHs含量范围为401 ng/g-569 ng/g，以3环PAHs为主。鱼体中ΣPAHs浓度范围为753 ng/g- 2036 ng/g，以3~4环PAHs为主，各器官富集PAHs趋势为心>肝>肌肉。逸度模型结果表明沉积物是PHE在淮河上游的主要汇，降解是PHE在淮河上游的主要输出方式，PHE在系统内部的迁移方向为从大气到水，从水到沉积物，温度是影响PHE在淮河上游迁移的最主要参数。