适合指示STPs尾水受纳海水综合质量的生物标志物筛选与应用

It is necessary to establish a assessment index system based biomarkers for evaluating the integrated quality of seawater receiving effluent from sewage water treatment plant (STPs). In this research, three common species of bivalves, named Mytilus edulis, Tapes philippinarum and Meretrix meretrix, will be used as indicaters, and the sea area receiving effluent from Tuandao STPs and Lichunhe STPs of Qingdao city is selected as the study area. First, bivalves are exposed to the mixture of effluent and artificial seawater, 13 biomarkers including vitellogenin(Vtg) in gonad and lipid peroxidation (LPO), metallothioneins, etc. in gills and visceras are measured. The biomarkers which have one-way response to effluent pollution will be selected according to their level change with exposure concentration and time. At same time, the suitable specie, organs and exposure time will also be decided.Second, caged mussels are placed in the area receiving effluent and clean area, the biomarkers selected above and chemicals such as PCBs, PAHs, etc. in soft tissue are determined simultaneously after exposure. Three sets of biomarkers will be composed according to the relevance between their levels and the contents of chemicals, their efficiency of discrimination between clean sites and polluted sites and the biomarkers with one-way response respectively. Then, integrated biomarkers response (IBR) index can be calculated based the activities or contents of biomarkers for each set. The most suitable assessment index system will be the set of biomarkers which IBR values has good relevance with pollutant contents in soft tissue and a clear discriminative power to contamination levels for different sites. At last, the integrated quality of coastal area receiving effluent is divided into four grades based on the range of IBR values by four points method.

筛选适宜的生物标志物评价指标体系对于评价尾水受纳海域综合质量十分必要。以青岛海域3种双壳类动物为指示生物，首先利用尾水-海水混合液对双壳类动物暴露培养，测定性腺的卵黄原蛋白(Vtg)、鳃和内脏的脂质过氧化(LPO)、金属硫蛋白(MTs)等13种生物标志物水平随暴露浓度、时间的变化，确定对尾水污染具有单向响应的生物标志物及其对应物种、器官种类和适宜暴露时间。然后在两座STPs的尾水受纳海域及清洁海域放置笼养贝类，根据生物标志物与体内PAHs、PCBs等污染物含量的相关性、生物标志物对清洁和纳污站位的区分效率以及室内暴露实验结果，设置3套生物标志物指标组合，分别计算对应的综合生物标志物响应（IBR）指数。根据各站位IBR指数值与污染物含量相关性以及IBR对站位间污染水平的判别力，确定适于尾水受纳海域环境质量综合评价指标体系。采用四分位法将IBR值分为四级，以分辨尾水受纳海域综合环境质量。

市政污水处理厂（STPs）的尾水能够在海洋生物体内产生多种逆境。近年来，有关受污染的海水对水生无脊椎动物早期生物学影响的研究受到关注。生物标志物的响应可用于人为污染逆境下生物体生理状态的评价，进而为区域环境质量评价提供有用信息。但是，这种研究常常需要选择一套生物标志物来指示污染的有害影响，然后对这些影响进行综合，以评价区域总体环境质量状况和对某站位的环境质量进行分级。本研究旨在通过春季、秋季的室内尾水暴露实验，测定双壳类文蛤鳃、内脏和血淋巴中10多种生物标志物随尾水浓度、暴露时间的同步变化，由此比较它们的响应灵敏性和相关性，进而筛选出敏感种类作为尾水-海水混合体系污染评价的指标，用于计算综合生物标志物响应指数（IBRv2），并提出混合体系污染水平的适宜分级模式和分级标准。春季和秋季分别以青岛市李村河污水处理厂和团岛污水处理厂的尾水作为实验材料（预先用海水晶调节盐度与天然海水一致），按设计的尾水体积比EVR（春季：1%、5%、10%、20%；秋季：1%、5%、10%、20%、30%、40%）用天然海水稀释后，对文蛤连续培养15d。结果表明，文蛤体内生物标志物对尾水暴露的响应敏感性随季节、暴露时间长短发生变化；血细胞LMS和血细胞MN几乎在整个暴露期间对任一浓度的尾水都能产生灵敏响应，而且测定方法简便快速，将在尾水污染综合评价中发挥重要作用；建立了三套生物标志物指标，均由4种生物标志物组成，分别适于春季尾水暴露3d（血细胞LMS，鳃GPx，鳃GSH，内脏GPx）、秋季尾水暴露9d（血细胞LMS，内脏GPx，内脏MTs，内脏AChE）和12d（血细胞LMS，血细胞MN，鳃GSH，鳃AChE）时的尾水-海水混合体系污染评价；利用每套指标所计算的IBRv2值均能够清晰地区分尾水污染水平，不仅证明所建立的评价指标体系的合理性，而且证明IBRv2评价模式在尾水排放海域综合质量评价中的良好应用潜力；将前人提出的逆境下单一生物标志物变化程度判断方法与IBRv2值的计算相结合，提出了尾水-海水混合体系污染水平分级标准，能真实反映出每个季节各种尾水浓度的差异，证明所提出的分级模式在海水综合环境质量评价中具有重要应用价值。根据文献查阅，国内外尚未见到有关这种分级模式的文献报道。