生物模拟采样快速评价有机物的生物富集性
文献类型：学位论文
| 作者 | 周东星 |
| 学位类别 | 硕士 |
| 答辩日期 | 2014-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 许宜平 |
| 关键词 | 生物富集系数 生物模拟采样 三油酸甘油酯-醋酸纤维素复合膜 疏水性 取代酚 邻苯二甲酸酯 bioconcentration factor triolein-embedded cellulose acetate membrane biomimetic sampler hydrophobicity substituted phenols phthalate esters |
| 其他题名 | Rapidly Predicting Bioconcentration Potential of Organic Chemicals with TECAM Biomimetic Sampling |
| 学位专业 | 环境科学 |
| 中文摘要 | 随着对环境质量要求的不断提高，人们对化学物质环境管理的意识逐步增强，其中一类具有持久性(persistent)、生物累积性(bioaccumulative)和毒性(toxic)的化学物质(简称为PBT物质)成为化学物质管理关注的焦点。化学物质的生物富集数据通常用来评价对动物和人类的暴露危害，这些数据不仅是化学物质环境管理的生态毒理学基础数据，同时也是欧美国家环境风险评价程序的触发要素之一，对环境风险评价具有重要作用。 本论文通过利用实验室前期开发的一种新型生物模拟采样器三油酸甘油酯-醋酸纤维素半渗透复合膜（TECAM）对几类不同理化性质的有机化合物进行微耗式富集试验，通过动力学模型拟合得到化合物在TECAM中的膜富集系数（MCF），用以快速预测评价目标化合物的生物富集性；结合数据库中得到的辛醇-水分配系数（KOW）、生物富集系数（BCF），比较两种富集系数与KOW的相关性，建立MCF与BCF的相关关系模型。 可解离的酚类化合物在水中形态可随pH而发生变化，因此对12种取代酚的TECAM富集试验，讨论不同pH对富集效果的影响。结果表明：相比于低疏水性取代酚，TECAM对疏水性较强的取代酚富集效果更好，富集曲线更加明显，富集量更高；低pH（pH=2、4）水平下MCF和KOW、BCF的显著线性相关，而高pH（pH=6、8、10）水平下不存在相关关系，说明pH较大时的确能够影响取代酚类在水中的解离平衡而影响MCF。基于名义浓度得到的MCF，富集系数随pH总体变化与文献中主流报道一致——弱疏水性（强极性）化合物MCF随pH的增加而缓慢减小，可能是因为MCF受到化合物极性和pH两方面影响，而极性应该占更主要方面；强疏水性（弱极性）化合物的MCF总体趋势随pH的增大而显著降低，MCF在pH>pKa范围内更是剧烈下降，这与文献报道的BCF随pH的变化趋势一致。取代酚同分异构体之间MCF和BCF均随pH的变化趋势一致，但同分异构体结构差异也会影响其富集系数大小。 对12种邻苯二甲酸酯类化合物的TECAM富集试验，讨论生物代谢对富集系数的影响。结果表明：随疏水性的增强，PAEs在TECAM膜中具有不同的富集趋势（弱疏水性PAEs快速平衡，中疏水性PAEs先经历线性阶段随后到达曲线阶段，强疏水性PAEs一直处于线性阶段）；TECAM膜对PAEs的富集系数MCF先上升后下降，与BCF随KOW的变化趋势一致，且两种趋势都符合二次曲线模型；MCF整体高于BCF，原因是生物代谢导致BCF偏低，而TECAM对PAEs的富集不涉及代谢过程。 针对不同疏水性(logKow范围：1.11~8.6)和分子量(MW范围：108.14~641.7)的62种有机物，进一步综合讨论使用TECAM生物模拟采样预测评价生物富集性的可行性：对这些化合物的富集系数MCF与BCF、KOW的相关性，并利用MCF对BCF进行相关分析，以期建立初步预测模型，并对富集参数（如消除速率常数ke）与KOW的关系进行讨论。结果表明脂肪归一化后得到的两种富集系数随KOW的变化趋势，尤其线性关系的斜率非常一致，这说明使用TECAM被动式采样技术可以较好的预测评价有机物的生物富集性；部分化合物的BCF值比MCF值偏低，这主要是由于非持久性化合物的BCF受到体内生物代谢影响所致。强疏水性化合物的MCF与BCF均出现显著下降趋势(拐点)，主要原因可能是强疏水性化合物的高分子量影响TECAM和生物跨膜运输作用，抑制化合物在TECAM和生物体内的吸收，继而影响富集量。所有化合物消除速率常数随KOW变化分布比较散乱，但对每一类化合物分别进行二次曲线拟合，拟合得到较好的结果。化合物消除速率常数总体趋势随分子量的增加而降低，与生物富集消除速率常数有一致的结果。 尽管MCF不能表征生物体对邻苯二甲酸酯等非持久性化合物的代谢过程，但生物模拟采样法能够消除物种间、个体间差异影响，具有单一估算水生生物富集目标化合物的潜在能力，更利于化合物之间的评估比较；与模型预测BCF方法相比，通过具体实验快速测定的MCF，可同时考虑生物有效性和其他环境因子影响，更接近实际环境，减少方法不确定性。 |
| 英文摘要 | International and national chemical management programs seek to protect human health and the environment from the potential risks of hazardous chemicals as identified by the criteria of persistence (P), bioaccumulation (B), and toxic (T) properties. The bioaccumulation potential of a chemical in aquatic organisms, especially fish and mussels, is an important criterion in the assessment of environmental hazards. Bioaccumulation properties of chemicals are not only necessary ecotoxicological information for chemical management programs, but also one of the triggers of the U.S. EPA and the EU environmental risk assessment process. In this study, we developed a fast evaluation method for bioconcentration factors (BCFs) of organic chemicals, by using a new type of biomimetic sampler – triolein embedded cellulose acetate membrane (TECAM). Negligible depletion sampling experiments were established with TECAMs for selected several kinds of organic chemicals. The concentration factor of a chemical in TECAM (MCF) was calculated through kinetics models. Relationships between selected log KOW values, MCFs and BCFs from database, as well as selected biotic and abiotic affected factors were discussed and compared. Negligible depletion sampling tests of 12 substituted phenols were taken using TECAMs in 12 hours. Uptake kinetics parameters and TECAM-concentration factors (MCFs) were evaluated. Results showed that there was significant positive correlation between logMCF and logKOW when pH=2 and 4, while no significant correlation when pH=6, 8 and 10. For weakly hydrophobic substituted phenols, the values of log MCF slowly decreased with the increase of pH, as not only the hydrophobicity of chemicals but also the pH values could influence MCFs while the hydrophobicity shown to be more important. For hydrophobic chlorophenols with lower pKa values, logMCF slowly decreased in the range of pH < pKa but abruptly decreased with increasing media pH in the range of pH > pKa. Different from weakly hydrophobic substituted phenols, MCFs of chlorophenols were more significantly influenced by pH. Negligible depletion sampling tests of 12 phthalates esters (PAEs) were taken using TECAMs in 24 hours. Results showed that there were different uptake trends with the increase of hydrophobicity for different PAEs. The MCFs of selected PAEs at first rose and then fell with the increase of KOW values, performed a quadratic trend which was similar to but better than the BCFs of selected PAEs. Metabolism should be taken into account in order to explain the difference between the MCFs and BCFs of PAEs. Furthermore, the relationships between MCF, BCF and KOW values of selected 62 chemicals with different physico-chemical properties were discussed. Results show that trends of two concentration factors with the increase of selected log KOW values were quite consistent and the slopes of two curves were highly close, suggested the feasibility of predicting BCFs by TECAM biomemitic sampling. There was no significant correlation between the elimination rate constant and logKOW data of all the selected chemicals, but good quadratic relationships could be found for each type of chemicals, respectively. Besides, the elimination rate constants were shown in a decrease trend with the increase of molecular weight, which was similar as the elimination rate constants for bioconcentration. Although TECAM-concentration factors (MCFs) could not represent the chemical processes in living organisms, it shown strong feasibility in predicting the direct bioconcentration potential of chemicals in aquatic organisms regardless the difference between individuals and species. Compared to the QSAR predition methods, the rapid evaluation method using TECAMs has the advantage of additional considerations for bioavailability and other actual environmental factors. |
| 公开日期 | 2015-07-08 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/15717]  |
| 专题 | 生态环境研究中心_环境水质学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 周东星. 生物模拟采样快速评价有机物的生物富集性[D]. 北京. 中国科学院研究生院. 2014. |
入库方式： OAI收割
来源：生态环境研究中心
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