太湖流域水体中硝基多环芳烃的赋存水平、生物累积与生态风险评价研究

Nitrated-Polycyclic Aromatic Hydrocarbons (NPAHs), which are nitro-derivatives of PAHs, showing similar properties and sources, have been one of the global environmental pollutants. It is reported that the carcinogenicities of NPAHs are 10 times to parent PAHs, and the mutagenic effects are 100000 times to parent PAHs. Therefore, to investigate their environmental behavior in aquatic environment is significant for understanding the ecological effects. However, the related researches are extremely limited. In this project, Taihu lake is selected as a typical area to study the occurrence, environmental behavior and bioavailability of NPAHs, followed by assessing the ecological risk. Occurrence patterns, pollution level, and distribution characterization would be obtained through the sampling and analysis of surface water, suspended particles, sediments and aquatic lives in whole Tai lake using the established pretreatment and instrumental analysis method. Transportation and partition of NPAHs among of different medium will be discussed by calculating the concentration ratio of NPAHs between sediment and suspended particles, water and aquatic lives. According to the pollutant status, some typical sections with different pollution characteristics will be chosen to study the possible ecological and biological factors which may affect the bioavailability of sediment-bound NPAHs in aquatic organisms. Moreover, bioaccumulation and transformation of sediment-bound NPAHs in benthic organisms will be studied using three laboratory model organisms. Additional, Tenax and nd-SPME will be introduced to evaluate the bioavailability of NPAHs in sediment. Finally, ecological risk caused by NPAHs in Taihu lake will be comprehensive analysis via several models after calculating the toxic equivalent of NPAHs.

硝基多环芳烃是多环芳烃的氧化加成衍生物，具有与多环芳烃类似的性质与来源，已成为全球性污染物之一，且致癌性是母体PAHs的10倍，致突变性则是母体PAHs的100000倍，研究其在水环境当中的环境行为对评估其生态效应至关重要。然而，目前相关的研究极为匮乏。本项目拟以太湖为典型区域，研究硝基多环芳烃在太湖流域主要水体的赋存、环境行为和生物有效性，并评价其生态风险。通过采集水、悬浮颗粒物、沉积物及水生生物进行仪器分析，了解其赋存形态和种类，评估其污染水平和分布规律；探讨硝基多环芳烃在各介质间的分配与转化规律；依据污染源特征和污染水平，选取代表性区域，研究生态、生物因素对硝基多环芳烃生物可利用性的影响；以多个处于不同营养层的实验室模式生物研究底栖水生生物对底泥中硝基多环芳烃的生物积累，采用仿生萃取技术评估底泥中硝基多环芳烃的生物有效性；计算硝基多环芳烃的毒性当量，综合评价其生态风险。

硝基多环芳烃具有与母体PAHs的同源性，已成为全球性污染物之一。本研究以硝基PAHs和16种优控PAHs为研究对象，建立其在水环境多介质中高效、灵敏的前处理及仪器分析方法；选择太湖流域为研究区域，对流域内主要水体中硝基PAHs的赋存种类、浓度水平进行调查研究，分析其分布特征和污染来源、在水环境多介质中的分配规律；以处于不同营养层的实验室模式生物研究底栖水生生物对底泥中硝基PAHs的生物积累，仿生萃取技术研究底泥中硝基PAHs的生物有效性，并与母体PAHs进行比较，最终评价PAHs衍生物在该流域的环境健康风险。建立了针对水、底泥和生物体的前处理与分析方法，方法检测限低，回收率高，准确性好，可满足实际样品的分析要求。对太湖湖体和主要入湖河流太滆运河的水及底泥样品分析结果表明，硝基多环芳烃均有检出，太湖枯水期ΣNPAHs浓度为46.6-212 ng/L，平水期浓度为nd-135 ng/L，丰水期浓度为18.1-181 ng/L，2-nFlu、9-nPhe、9-nAnt和2+3-nFla是主要污染物。底泥中硝基多环芳烃的浓度介于3.21-49.14 ng/g之间，平均值为30.74 ng/g，3-硝基荧蒽、1,3-二硝基芘、1,6-二硝基芘和1,8-二硝基芘是主要污染物。来源分析表明，化石燃料燃烧仍然是其最主要来源。硝基多环芳烃在底泥/水界面分配行为研究结果表明，NPAHs和PAHs在沉积物和水之间的分配受疏水作用的影响显著。采用斑马鱼和中华圆田螺研究其对NPAHs的富集能力，结果表明斑马鱼对水中硝基多环芳烃在28天可达到富集平衡，斑马鱼富集水中NPAHs的过程是一个受外界浓度控制的分配过程。中华圆田螺对沉积物中NPAHs的富集在暴露 28 d后，基本达到平衡，对沉积物中 NPAHs 的BSAF处于 1.02-1.96之间，说明中华圆田螺对沉积物中 NPAHs的富集程度较低。采用自制ZIF-8/h-BN固相微萃取纤维探针进行生物有效性研究，并与Tenax萃取法进行比较，结果表明，SPME提取法的NPAHs提取量与中华圆田螺富集量的相关数高于Tenax提取法。因此ZIF-8/h-BN纤维SPME技术更能准确地评估沉积物中NPAHs的生物有效性。本研究为深入探讨NPAHs的环境过程与毒性效应提供了技术与数据支撑，对控制其污染具有重要意义。