Quantitative Structrue-activity/Property Relationships For Environmental Activities/Properties Of Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbons(PAHs)are persistent organic pollutants widely distributed in all environmental medias.The casual production of PAHs as a by-product in human activities is currently the main cause of PAHs pollution,hard to completely eradicate at the source.The generation of PAHs contributes to the residue of PAHs in environment and may pose threats to the ecological environment and human health.After entering the ecological environment,PAHs migrate and transform in various environmental medias,and therefore increase the level of exposure of humans and other living things to PAHs.There are a variety of PAHs,and humans just have a little knowledge of the number of their varieties,and the bioactivity or toxicity effect of the known PAHs,since the limited detection technologies restrict people from further understanding them.The internal causes restricting the environmental activity of PAHs were analyzed from the perspective of PAHs' structural properties.The main research results include:(1)Quantum chemical parameters computed using Density Funtional Theory(DFT)quantum chemistry methods at the B3LYP/6-31G(d)and M06-2X/6-31G(d)level,and partial least squares(PLS)analysis with an optimized procedure were used to generate QSAR models for predicting biodegradation of PAHs in soils.The correlation coefficient of the optimal models were both 0.989,moreover,the results of the internal cross-validation and external test showed these QSAR models display high fitting precision and good prediction.The log t1/2 values predicted by these QSAR models are very close to those observed in experiments.The PLS analysis also indicated that PAHs with larger electronic spatial extent(Re),Energy of next highest occupied molecular orbit(ENHOMO)or Energy of next lowest unoccupied molecular orbit(ENLUMO)tend to more readily biodegradated by microorganism.(2)Quantum chemical parameters computed using Density Funtional Theory quantum chemistry methods at the M06-2X/6-31G(d)level,and partial least squares(PLS)analysis with an optimized procedure were used to generate QSAR models for Soil-Porewater Partitioning Behavior and Bioaccumulation in Enchytraeus crypticus of PAHs in historically Contaminated Soils.The correlation coefficients of the optimal models were 99.4%,99.4%,99.1%,98.7%,99.0%,99.2%,98.7% and 98.7% respectively,moreover,the results of the internal crossvalidation and external test showed these QSAR models display high fitting precision and good prediction.Values predicted by these QSAR models are very close to those observed in experiments.The PLS analysis also indicated that average molecular polar polarizability(?)and total molecular energy(ET)play decisive roles in Soil-Porewater Partitioning Behavior and Bioaccumulation in Enchytraeus crypticus of PAHs in historically Contaminated Soils.Moreover,with the increasment of molar heat capacity at constant volume(CV)value,more capable of further distribution character in soil strengthens,while its accumulative effect in enchytraeid in soil is enhanced as well.(3)Quantum chemical parameters computed using Density Funtional Theory quantum chemistry methods at the M06-2X/6-31G(d)level,and partial least squares(PLS)analysis with an optimized procedure were used to generate QSPR models for predicting polyethylene(PE)to water distribution coefficient of PAHs.The correlation coefficient of the optimal models were 98.2%,96.6%,99.6%,99.7% respectively.Moreover,the results of the internal crossvalidation and external tests showed these QSPR model display high fitting precision and good prediction.The log KPE values predicted by these QSPR models are very close to those observed in experiments.The PLS analysis also indicated that with the increasment of ET,Re or molecule thermal energy(ETH),or the decreasement of CV value,the PAHs molecules become more capable of distributing in soil components.Furthermore,PE to water distribution coefficient of PAHs increases with entropy(S),but if the water is a solid-fluid system and the solid component ratio is high,the change of entropy in the system manifests as a sum of the entropy decrease during adsorption and the entropy increase during desorption.(4)Quantum chemical parameters computed using Density Funtional Theory quantum chemistry methods at the M06-2X/6-31G(d)level,and partial least squares(PLS)analysis with an optimized procedure were used to generate QSAR models for bioacessibility of PAHs in fuel soot.The correlation coefficients of the optimal models were 97.2%,97.3%,97.2% respectively.Moreover,the results of the internal cross-validation and external test showed this QSAR model display a high fitting precision and good prediction.Values predicted by these QSAR models are very close to those observed in experiments.As is shown in model K7d-I and K7d-II,the PLS analysis indicated that ET,Re and S are significant independent variables of these two models.PAHs with larger ET,Re or S tend to more readily distribute in the digestive tract from digestive juice.the lowest unoccupied molecular orbital energie(ELUMO),frontier molecular orbital energy gap [(ELUMO–EHOMO)2] and ET are of significant importance to model k-min.PAHs with higher ELUMO or ET,or lower(ELUMO–EHOMO)2 have stronger bioacessibility in digestive system.