【作者】 聂利红；

【导师】 刘宪斌；

【作者基本信息】 天津科技大学 ， 环境工程， 2009， 硕士

【摘要】 PAHs作为天津海岸带的典型污染物质,因具有持久性、生物难降解性及高毒性,对环境中的生物及人类健康造成严重的威胁,导致河口及其海岸带生境退化,目前人们逐渐意识到采取有效措施对生态环境进行修复的必要性和紧迫性。因此,调查有代表性潮间带沉积物及生物体泥螺中PAHs含量,并研究泥螺对PAHs的生物可利用性及沉积物中PAHs的解吸行为,对评价受污染沉积物的生态风险、选择合理的修复技术及制定合理的修复策略都具有十分重要的意义。本文选取受PAHs污染且有代表性的潮间带为生态示范区,采用气相色谱-质谱联用仪（GC-MS）研究了该区表层沉积物及优势种泥螺体内PAHs含量及分布特征。结果表明,沉积物和泥螺体内均以二环和三环萘、芴、菲、蒽为主,根据Long提出的沉积物风险评价标准,萘、芴、菲、蒽超出风险低值,对潮间带生态具有潜在危害,其中石油输入是主要污染源,并混有化石燃料的不完全燃烧。以菲为PAHs代表污染物,通过室内模拟试验探讨其对泥螺的毒性效应及生物累积效应,通过测定BSAF（Biota-Sediment Accumulation Factor）值研究泥螺对菲的生物可利用性。结果表明,菲对泥螺7d的理论LC₅₀值为73.6mg/kg,且LC₅₀随污染暴露试验时间的延长而减小;泥螺对不同浓度水平菲的BSAF值不同,随着菲污染水平的升高,泥螺体内菲累积量显著增大。新鲜染毒的菲易被生物利用,BSAF值＞1,而老化100 d沉积物中的菲被“锁定”,减缓它的释放速率,导致其生物可利用性降低,BSAF值＜1。采用循环吸附/解吸实验法,研究了菲在沉积物中的吸附和解吸行为,并用DED（Dual-Equilibrium Desorption）模型对解吸行为进行了预测。结果表明,菲在沉积物中的吸附符合传统线性模型,解吸曲线明显偏离吸附曲线,存在不可逆解吸现象,且DED模型的预测值与实验结果相吻合。总之,研究泥螺对PAHs的生物可利用性,可以为河口及潮间带的环境监测、生态风险评价及生物修复提供科学依据。更多还原

【Abstract】 As one of typical persistent pollutants in Tianjin’s coastal zone, PAHs have the properties of persistence, bio-refractory and high toxicity, which has caused serious harm to environment, organism and human health. Now people gradually are realizing the necessity and urgency of taking effective measures to restore damaged ecological environment. Therefore, quantitatively analyzing the concentrations and distribution of PAHs in surface sediments and dominant species Bullacta exarata sampled from the typical intertidal zone, studying on the bioavailability of PAHs to Bullacta exarata and desorption behaviors of PAHs in sediment have great significance for ecological risk assessment, selecting reasonable remediation technologies and making feasible reparation strategy.Concentrations and distribution of 10 PAHs in surface sediments and Bullacta exarata sampled from the typical damaged intertidal zone were quantitatively analyzed by GC/MS, the main polluted sources in this area were discussed. The results showed that the concentrations of 2,3 ringed PAHs compounds in all detected PAHs were the most dominant both in sediments and organisms. The main source of PAHs in the studying area might be petroleum-derived contamination mixing incomplete combustion of the fossil fuel. According to sediment quality criterion, the concentration of naphthalene, fluorene, phenanthrene and anthracene exceed the risk low (ERL) values, which might be a certain potential toxic effect to the ecosystem of intertidal zone.The acute toxicity and bioaccumulation of Phe selected as a representative PAHs to Bullacta exarata was studied by simulation experiments in lab. The testing result showed that the theoretical median lethal concentration (LC50) value of Phe to Bullacta exarata was 73.6 mg/kg and the LC50 value was decreased with the increase of exposure time. At different contamination levels of Phe, the BSAF values were various for Bullacta exarata. With Phe concentration increasing in sediments, the accumulation of Phe in Bullacta exarata was increases significantly. Phe fresh spiked in sediments was biological utilized easily correspondingly with BSAF>1, when Phe in sediemnt was aged for 100d, Phe would be sequestrated by organic matters, which slowed down the releasing rate and reduced the bioavailability, so BSAF was less than 1.The sorption/desorption behavior of Phe in sediments from ecological demonstration area were studied using multiple cycles of sorption/desorption experiments and the desorption data were predicted using a new desorption model ’Dual-Equilibrium Desorption (DED) model’. The result showed that the sorption of both naphthalene and Phe agree well with the conventional linear sorption isotherm. While the desorption curve which showed an irreversible phenomenon was deviation from sorption isotherm but it could be predicted well with the DED model. In summary, this paper had a preliminary study on the bioavailability of PAHs contaminants to Bullacta exarata, which provided scientific basis for the environmental monitoring, ecological risk assessment and bioremediation of estuary and intertidal zone.更多还原