【作者】 张栩嘉；

【导师】 赵元慧；

【作者基本信息】 东北师范大学 ， 环境科学， 2013， 博士

【摘要】 有机污染物对不同物种种间毒性相关性及毒性差异的比较研究是一种非常有价值的生态毒理学数据估算方法,它不但有助于我们用一种物种的毒性来估算其它物种的毒性,还有助于我们深入探讨有机污染物的毒性作用机理。虽然研究者已经证明有机污染物对不同生物物种的毒性不同,并试图建立结构与活性相关方程来预测有机污染物对不同物种的毒性,但对于种间毒性的理论基础却很少有报道。应用有机污染物的分类方法比较有机污染物对不同物种的毒性,不但有助于我们区分非反应性和反应型化合物的毒性,还有助于我们深入理解有机污染物对生物的毒性机理。因此,本论文以大量的工业有机污染物为研究对象,通过研究有机污染物对8种水生生物的种间毒性相关性,以及系统比较有机污染物对两种水生生物的毒性机理,得出如下结果。首先,本研究通过部分有机污染物对发光菌、江水微生物、绿藻、大型溞、鲤鱼、梨形四膜虫、黑呆头鱼和古比鱼的毒性数据,研究了有机污染物对八种水生生物毒性的相关性,结果表明有机物对海洋微生物与淡水微生物及鱼之间的毒性具有良好的相关性,这说明他们之间具有相同或相近的毒性机理和生物富集过程。另一方面,有机污染物对绿藻类和梨形四膜虫或与大型溞的毒性相关性较差,这表明有机污染物对这些水生生物的毒性机理具有较大的差别。通过引入正辛醇／水分配系数log Kow和最低空轨道能ELUMO可以改进种间毒性的相关性。苯甲酸类有机物对发光菌、大型溞和鲤鱼的毒性表现出了明显的不同,它们很容被单细胞的发光菌吸收,但是对于大型溞和鱼来说,多细胞生物的皮肤和脂肪对苯甲酸类化合物的生物吸收有很强的抑制作用,因此表现出较低的毒性。我们以此研究结果为基础,在理论上建立了物种间毒性的相关方程,并对这些相关结果进行了解释。第二,本研究应用了758种大型溞的毒性数据和993种梨形四膜虫的毒性数据分类比较了有机化合物的毒性作用机理类型。结果表明化合物的毒性作用机理具有物种依赖性。醇、醛、酮、醚、酯和部分取代苯类化合物对这两种生物的毒性作用机理相同,苯胺及其取代物对这两种生物的毒性作用机理不同。在此基础上,根据基线和极性麻醉型化合物的毒性数据,分别建立了化合物对大型溞和梨形四膜虫毒性与log Kow的相关方程,计算实测毒性与基线模型预测毒性的比值,预测了不同类型有机污染物的剩余毒性。结果发现应用临界毒性比值(TR)和过剩毒性虽然能区分非反应和反应性化合物,但是没有剩余毒性的化合物并不意味着没有反应性；得出实验误差不会影响临界毒性比值的确定,实验误差仅仅会增加对化合物毒性作用机理类别的判定：有机污染物的毒性作用机理分类的判定应该基于其在生物体内的临界浓度值(CBR),应用体外浓度来判别有机污染物的毒性类别会产生误差；同时发现生物富集因子的预测误差也会导致化合物的错误分类并出现离群值。第三,本研究测定取代苯酚、苯胺和苯甲酸类化合物在pH值为6、7.8和9的条件下对大型溞的24h急性毒性,计算了化合物在不同pH值条件下的中性态分子所占比例F0。发现取代苯酚和苯甲酸类化合物的毒性和Fo都随着pH的升高而降低,而取代苯胺类化合物的毒性和Fo和都随着pH的升高而略有升高,但苯胺类化合物的离子化程度较低,在设定pH值内主要以非离子态形式存在,导致离子化率对毒性的影响很小。在pH从6-9的范围内,pH-pKa的范围接近-1-3的酸性化合物毒性随pH变化较显著,而pH-pKa的范围接近-3-1的碱性化合物毒性随pH变化较显著。研究结果表明离子化率是影响苯酚类化合物毒性的重要因素,引入log F0进入到苯酚类化合物的疏水性模型,可以增加模型的决定系数。对于氯代苯甲酸类化合物,毒性与疏水性的相关性较好,但是羟基苯甲酸类化合物的毒性与疏水性参数的相关性很差,引入量子化学参数EHOMO和取代羟基个数NON,可以改进苯甲酸类化合物的模型的质量。氯代苯甲酸类化合物的毒性基本低于基线毒性,这是由于大型溞的脂质外壳对离子态化合物的吸收有很强的阻碍作用的结果。更多还原

【Abstract】 Interspecies correlation and comparing interspecies difference of toxicity and is a valuable method used to estimate toxicological data. It not only allows the prediction of toxicity to a number of other species but it is also helpful in the interpretation of mechanisms. Although some authors realized the differences between toxicities to different aquatic organisms and tried to develop interspecies correlations for these species, little attention has been paid to the theoretical considerations of toxic mechanism of action between species. Comparing interspecies difference of toxicity using structural classification method not only allows the discrimination of excess toxicity from narcotic, but it is also helpful in the interpretation of mechanisms. This paper based on a large number of industrial organic pollutants, through the study of the interspecies correlations of toxicity between eight species of aquatic organisms and comparing the toxic mechanism of action between two species, concluded main conclusions as followed:First, this study examines the interspecies correlations of toxicity between species of Vibrio fischeri, river bacteria, algae, Daphnia magna, carp, Tetrahymena pyriformis, fathead minnow and guppy. The results show that there are good interspecies correlations between marine bacterium and fresh water bacteria or fish and fish. It is suggested that compounds share the same bio-uptake and toxic mechanism of action between the species. On the other hand, poor interspecies relationships were found between toxicities to algae and T. pyriformis or D. magna. It is suggested that compounds have different toxic mechanisms of action between these species. Interspecies relationships can be improved by inclusion of the octanol/water partition coefficient or the energy of the lowest unoccupied molecular orbital. Benzoic acids show very different toxicity contributions to the three species, V. fischeri, D. magna and carp. They can be easily absorbed into the unicellular bacteria, V. fischeri. On the contrary, the skin and lipid content of multicellular organisms, such as D. magna and fish, can strongly inhibit the bio-uptake for ionisable compounds, which results in the different toxic effect between V. fischeri and D. magna or carp. Good correlation coefficients were observed between toxicities to V. fischeri and D. magna or fishes by inclusion of hydrophobic and ionization parameters.Second, the toxicity data of758chemicals to Daphnia magna and993chemicals to Tetrahymena pyriformis were used to discriminate the excess toxicity from narcotic effect levels of organic compounds and examine the similarity and difference of toxicity to different species. The result showed that mode of toxic action of chemicals is species dependent. The results showed that some classes (e.g. alkanes, alcohols, ethers, aldehydes, esters and benzenes) shared same modes of toxic action to both D. magna and T. pyriformis. However, some classes may share different modes of toxic action to T. pyriformis and D. magna (e.g. anilines and their derivatives). On this basis, We carried out linear regression analysis between log KOW and the toxicity for baseline or polor narcosis chemicals to D. magna and T. pyriformis, respectively. The toxic ratio (TR) calculated from baseline model over the experimentally determined values were used to measured the excess toxicity of different chemicals. For the interspecies comparison, same reference threshold need to be used between species toxicity. The excess toxicity indicates that toxicity enhancement is driven by reactive or specific toxicity. However, not all the reactive compounds exhibit excess toxicity. In theory, the TR threshold should not be related with the experimental uncertainty. The experimental uncertainty only brings the difficulty for discriminating the toxic category of chemicals. The real threshold of excess toxicity which is used to identify baseline from reactive chemicals should be based on the critical concentration difference inside body, rather than critical concentration outside body (i.e. EC50or IGC50). The experimental bioconcentration factors can be greatly different from predicted bioconcentration factors, resulting in different toxic ratios and leading to mis-classification of toxic category and outliers.Third, the24h acute immobilization toxicity of substituted phenols, anilines and benzoic acids was determined for the freshwater crustacean Daphnia magna under the condition of pH equal6,7.8and9. The fraction of neutral form (FO)was calculated for substituted phenols, anilines and benzoic acids at three different pH conditions. The toxicity and FO were higher for phenols and benzoic acids at lower pH values but they were higher for anilines at higher pH values. The toxicity data suggested that the effect of pH was most pronounced when pH-pKa was in the range of1to3for acids, and-3to1for bases. It is a important influencing factor of ionization for the toxicity of phenols. Inclusion of log FO with log KOW can improve the determinate coefficient of the phenols models. Ionization degree is very low for anilines at all three pH condition and neutral form is accounts for absolute advantage, so the effect of ionization to anilines is smaller than phenols. The correlation of the toxicity for benzoic acids and hydrophobicity parameter is very poor, and inclusion of EHOMO and the number of hydroxyl (NOH) with log KOW can improve the determinate coefficient of the models.更多还原