【作者】 于海瀛；

【导师】 陈景文；

【作者基本信息】 大连理工大学 ， 环境工程， 2008， 硕士

【摘要】 有机化合物的空气／颗粒物分配系数（K_p）能表征有机化合物在大气中的分配和环境归趋，K_p的大小受到其正辛醇／空气分配系数(K_OA)的显著影响。K_OA本身也是非常重要的理化性质参数，可以评价有机化合物在空气和多种环境有机相之间的分配，是进行生态风险评价的基础数据。实验测定K_p和K_OA会消耗大量的人力物力，受到标准样品缺乏的限制并滞后于有机化合物的合成和使用，因此有必要发展这两种参数的理论预测模型。首先以18种正构烷烃、21种多氯联苯（PCBs）、16种二噁英（PCDD／Fs）和13种多环芳烃（PAHs）为研究对象，应用半经验分子轨道PM3算法计算了这些化合物的16种理论分子描述符，分别采用偏最小二乘法（PLS）和支持向量机（SVM）进行回归分析，建立K_p的定量结构-活性关系（QSAR）模型，并以PCDD／Fs为例，建立K_p的温度依附性模型。所建立的模型具有较好的准确性和稳健性，误差随机分布，可用于应用域内化合物的logK_p值的预测。分子间色散力、电荷转移作用和分子位阻效应是影响化合物在空气相和颗粒物相间分配的主导因素，并且分子位阻对化合物在颗粒相中的分配起阻碍作用。PCDD／Fs的温度依附模型结果表明环境温度确实是影响有机化合物在两相之间分配的重要因素，温度在模型中以T²的形式表现出来。PLS和SVM两种方法的模型结果对比表明，SVM方法能够更充分地提取化合物分子结构参数与其K_p值之间的信息，使得模型拟合和预测效果提高，也表明影响化合物分子在空气和颗粒物两相间分配的分子结构因素与K_p之间可能存在某些非线性关系。应用OMNISOL SM5.0模型计算246个有机化合物在正辛醇溶剂中的溶解自由能，并根据热力学平衡方程计算这些化合物的logK_OA值。计算值与实验值之间存在较好的相关性。受到计算软件发展的限制，能量计算本身存在一定误差，影响K_OA的计算准确性，但是在可以接受的计算精确度的前提下这种不准确性可以通过相应的线性关系进行校正。因此可以采用该方法计算有机化合物的K_OA以及更多的平衡分配系数。更多还原

【Abstract】 The partition coefficient between particulate and gas phases （K_p） for organic pollutants areof great importance to characterize the behavior of organic pollutants in atmosphere, and thevalue of K_p is notably correlated to K_OA, octanol/gas partition coefficient. K_OA is a veryimportant physicochemical parameter for describing the partition of organic chemicalsbetween air and environmental organic phases and is basic data needed by ecological riskassessment. Experimental determination of both K_p and K_OA are time- consuming, expensiveand limited by standard sample, which lag behind the synthesis and use of organic chemicals.It is thus of theoretical and practical importance to develop predicting models for K_p and K_OA.Partial least squares （PLS） and support vector mechanism （SVM） regression with 16theoretical molecular structural descriptors calculated by PM3 arithmetic were used todevelop quantitative structure-activity relationship （QSAR） model for K_p of 18 aliphatichydrocarbons, 21 polycyclic aromatic hydrocarbons （PAHs）, 16 polychlorinated biphenyls（PCBs） and 13 polychlorinated dibenzo-p-dioxins/dibenzofurans （PCDD/Fs）. The temperaturedependence model of PCDD/Fs was also developed to reveal the effect of environmentaltemperature on the partition process.The obtained models have good predictive ability, robustness, and nonsystematic residuals,which can be used for estimating K_p of chemicals within applicability domain. Intermoleculardispersion interactions, charge-transfer interactions and hindrance effects of molecular sizedetermine the values of K_p, with the hindrance effects playing a negative role in the partitionto particulate phase. The result of temperature dependence model of PCDD/Fs indicates thatenvironmental temperature is an important factor controlling the partition of organicchemicals between gas and particle phases, and included in the form of square in the model.The comparison of models developed by PLS and SVM indicates that SVM methord canextract the information of relationship between molecular structural parameters and K_p moreadequately than PLS, resulted in the model with better goofness-of-fitting and predictivepower. This phenomenon reveals that there may be some nonlinear relationship betweenmolecular structures which affect the partition and K_p.The values of logK_OA of 246 organic chemicals were obtained by thermodynamicequilibrium equation basing solvation free energy calculated using OMNISOL SM5.0. Though the calculated logK_OA values are not very exact because of the shortcoming ofsoftware, there is good correlationship between calculated and observed values of logK_OA. Sowe can adjust the calculated values by this correlationship to obtain more accurate logK_OAvalues.更多还原