Quantitative Models for the Structure and Photodegradation of Polycyclic Aromatic Hydrocarbons

Based on the quantum chemical descriptors,quantitative structure-property relationship（QSPR） models have been developed to estimate and predict the photodegradation rate constant（logK） of polycyclic aromatic hydrocarbons（PAHs） by use of linear method（multiple linear regression,MLR） and non-linear method（back propagation artificial neural network,BP-ANN）.A BP-ANN with 3-3-1 architecture was generated by using three quantum chemical descriptors appearing in the MLR model.The standard heat of formation（HOF）,the gap of frontier molecular orbital energies（ΔELH） and total energy（TE） were inputs and its output was logK.Leave-One-Out（LOO） Cross-Validated correlation coefficient（R^2CV） of the established MLR and BP-ANN models were 0.6383 and 0.7843,respectively.The nonlinear BP-ANN model has better predictive ability compared to the linear MLR model with the root mean square error（RMSE） for training and validation sets to be 0.1071,0.1514 and the squared correlation coefficient（R^2） of 0.9791,0.9897,respectively.In addition,some insights into the molecular structural features affecting the photodegradation of PAHs were also discussed.

Influence of vehicle population on atmospheric levels of carcinogenic polycyclic aromatic hydrocarbons

Application of the linear regression between vehicle types/numbers and PAH contents (Particle + Vapor) within a radius of 60 and 300 miles can be employed to assess the impact of long range atmospheric transportation (LRAT) to the level of PAHs in the rural atmosphere of Whitbourne,UK.In general,higher R-values coupled with lower P-values were found in those samples within a radius of 300 miles,whereas lower R-values were detected in those samples within a radius of 60 miles.R-values of PAH concentrations vs.all vehicle numbers within radius of 300 miles ranged from 0.51 to 0.92 with the arithmetic mean of 0.75 ± 0.12,whilst those R-values within a radius of 60 miles ranged from 0.05 to 0.61 with the arithmetic mean of 0.11 ± 0.28.This supports the hypothesis that PAHs in Whitbourne undergo LRAT.

Rush-hour aromatic and chlorinated hydrocarbons in selected subway stations of Shanghai,China

Air samples were collected simultaneously at platform,mezzanine and outdoor in five typical stations of subway system in Shanghai,China using stainless steel canisters and analyzed by gas chromatography-mass selective detector （GC-MSD） after cryogenic pre-concentration.Benzene,toluene,ethylbenzene and xylenes （BTEX） at the platforms and mezzanines inside the stations averaged （10.3±2.1）,（38.7±9.0）,（19.4±10.1） and （30.0±11.1） μg/m 3,respectively;while trichloroethylene （TrCE）,tetrachloroethylene （TeCE） and para-dichlorobenzene （pDCB）,vinyl chloride and carbon tetrachloride were the most abundant chlorinated hydrocarbons inside the stations with average levels of （3.6±1.3）,（1.3±0.5）,（4.1±1.1）,（2.2±1.1） and （1.2±0.3） μg/m 3,respectively.Mean levels of major aromatic and chlorinated hydrocarbons were higher indoor （platforms and mezzanines） than outdoor with average indoor/outdoor （I/O） ratios of 1.1–9.5,whereas no significant indoor/outdoor differences were found except for benzene and TrCE.The highly significant mutual correlations （p0.01） for BTEX between indoor and outdoor and their significant correlation （p0.05） with methyl tert-butyl ether （MTBE）,a marker of traffic-related emission without other indoor and outdoor sources,indicated that BTEX were introduced into the subway stations from indoor/outdoor air exchange and traffic emission should be their dominant source.TrCE and pDCB were mainly from indoor emission and TeCE might have both indoor emission sources and contribution from outdoor air,especially in the mezzanines.

Health risk assessments of polycyclic aromatic hydrocarbons and chlorinated/brominated polycyclic aromatic hydrocarbons in urban air particles in a haze frequent area in China

The potential threats of polycyclic aromatic hydrocarbons(PAHs)and chlorinated/brominated PAHs(Cl/Br-PAHs)to human health from particulate matter in the urban ambient air were studied using human health risk assessments.The risk to human health caused by exposure to PAHs was evaluated in Shijiazhuang,China,from January to December 2018.The PAHs concentration range was 16.02e475.21 ng/m3 and the toxic equivalent was 13.605 ng/m3.For adults,the average carcinogenic risk caused by respiratory exposure was 5.163×10^-6 and the resulting loss of life expectancy was 32.10 min.The human health risks of respiratory exposure to Cl/Br-PAHs in atmospheric samples from the Haidian District,Beijing,China,were evaluated from November 2017 to July 2018.The concentration ranges for the Cl-and Br-PAHs were 60.38e482.17 pg/m3 and 1.32e25.35 pg/m3,respectively.The average carcinogenic equivalent concentrations were 0.3274 pg/m3 and 0.0061 pg/m3 for the Cl-and Br-PAHs,respectively.For adults the average carcinogenic risks caused by respiratory exposure were 1.243×10^-10 and 2.316×10^-12 for the Cl-and Br-PAHs,respectively.The resulting loss of life expectancy values were 0.001 min(Cl-PAHs)and 0.00 min(Br-PAHs).The pollution concentrations and toxic equivalents of the Cl/Br-PAHs in Beijing and of the PAHs in Shijiazhuang both showed toxicity was high in the winter.The average carcinogenic risk for exposure of adults to PAHs in Shijiazhuang was low with certain potential hazards.The concentration of Cl-PAHs in Beijing was higher than that of Br-PAHs,and the average carcinogenic risk for exposure of adults to Cl/Br-PAHs was very low with slight harm.

Quantitative structure–biodegradability relationships for biokinetic parameter of polycyclic aromatic hydrocarbons

Prediction of the biodegradability of organic pollutants is an ecologically desirable and economically feasible tool for estimating the environmental fate of chemicals. In this paper,stepwise multiple linear regression analysis method was applied to establish quantitative structure biodegradability relationship（QSBR） between the chemical structure and a novel biodegradation activity index（qmax） of 20 polycyclic aromatic hydrocarbons（PAHs）. The frequency B3LYP/6-311＋G（2df,p） calculations showed no imaginary values, implying that all the structures are minima on the potential energy surface. After eliminating the parameters which had low related coefficient with qmax, the major descriptors influencing the biodegradation activity were screened to be Freq, D, MR, EHOMOand To IE. The evaluation of the developed QSBR mode, using a leave-one-out cross-validation procedure, showed that the relationships are significant and the model had good robustness and predictive ability. The results would be helpful for understanding the mechanisms governing biodegradation at the molecular level.

Occurrence of polycyclic aromatic hydrocarbons in the estuarine sediments of the Taihu Lake and their associated toxic effects on aquatic organisms

Polycyclic aromatic hydrocarbons(PAHs)are ubiquitous toxic organic pollutants in the natural environment that are strongly associated with socioeconomic activities.Exploring the distribution,sources,and ecological toxicity of PAHs is essential to abate their pollution and biological risks.The 16 priority PAHs in different lakeside city estuarine sediments in the northern Taihu Lake in China were determined using gas chromatography-mass spectrometry.Results showed that total concentrations of PAHs(ΣPAHs)ranged from 672.07 to 5858.34 ng g^(^(-1)),with a mean value of 2121.37 ng g^(^(-1)).High-molecular-weight PAHs(4-6 rings)were dominant,accounting for 85%of theΣPAHs detected.Due to the barrier of gate/dam in the estuarine area,the concentrations of PAHs in the sediments were significantly different between the river mouth and lake side.Changes in total organic carbon(TOC)content and the spatial distribution of PAHs in the sediments were consistent.Sediment pollution assessment explored using the fuzzy evaluation model indicated 75%of slight PAH pollution.Some estuarine sediments(22%)concentrated in the east of the Wuli Lake in the Meiliang bay of the Taihu Lake were moderately or heavily polluted.The PAHs may lead to occasional detrimental biological consequences in the area.Diagnostic ratios and principal component analysis-multiple linear regression suggested vehicle emission and natural gas combustion as the primary PAH contributors(81%).

土壤中多环芳烃衍生物污染特征及迁移转化

本文综述了氯代多环芳烃(ClPAHs)和硝基多环芳烃(NPAHs)在不同区域和不同利用类型土壤中的污染水平和赋存形态,采用EPISuite软件和密度泛函理论计算获得了ClPAHs和NPAHs的极性、土壤吸附系数、快速生物降解性、轨道能级等性质,并分析了取代基种类、数量以及位置对PAHs衍生物性质和环境归趋的影响.重点总结了ClPAHs和NPAHs在土壤中的吸附-解吸、光降解、氧化还原、生物降解等迁移转化行为.最后,基于现有研究现状,希望未来能够优化检测方法、建立土壤污染数据库、丰富迁移转化数据和机理,为土壤PAHs污染特征和迁移转化研究提供更准确、全面信息.

烟气中氯代芳构化合物催化氧化的研究进展

焚烧是固体废物处理的重要方式,但由此产生的烟气中含有氯代芳构化合物(chlorinated aromatic hydrocarbons,CAHs),对环境和健康构成威胁.催化氧化技术因其高去除率、低能耗、低二次污染等优点被认为是去除烟气中CAHs最有效的方法之一.本文系统介绍了常见的催化剂种类,包括贵金属催化剂、过渡金属氧化物催化剂和分子筛催化剂,并比较了它们的优缺点.同时,深入探讨了催化氧化反应的机制、催化剂失活原因和再生方法,并强调了催化剂的组分、载体、结构和制备方法等对催化剂活性的重要影响.最后,根据文献研究,对CAHs的催化氧化进行了展望.未来研究应进一步优化催化剂设计,提高反应效率,并将其应用于实际焚烧烟气治理.

气相色谱法检测红树林湿地土壤中氯/溴代多环芳烃

建立了气相色谱-电子捕获检测器(GC-ECD)法检测红树林湿地土壤中18种氯/溴代多环芳烃(Cl/Br-PAHs)同类物,探究了土壤样品的前处理方法,并验证了方法的有效性.该方法的检出限和加标回收率分别为0.21~3.75ng/g dw和64.9%~106.4%,相对标准偏差为0.42%~14.13%.与GC-MS方法相比,GC-ECD方法对于多数Cl/Br-PAHs的准确度和灵敏度相当,且该方法稳定性更好,测定成本更低,可以满足湿地土壤中Cl/Br-PAHs的定性定量分析.采用所建立的方法对广西红树林湿地土壤样品进行了检测,结果显示,湿地土壤样品中Cl/Br-PAHs的总含量范围为163.24~244.45ng/g dw.

南京某地农业土壤中有机污染分布状况研究

对某大型矿业企业周边农业土壤中两类POPs物质——15种多环芳烃和有机氯农药（DDTs和HCHs）的残留量进行了调查。结果表明，PAHs检出率为100％，总残留量范围为312．2～27580.9μg·kg^-1且以四环以上多环芳烃组分为主。不同样区土壤PAHs残留量受常年风向影响明显。农业土壤中有机氯农药六六六和滴滴涕均有检出，但残留水平不高，分别为3．60μg·kg^-1（0．81～9，43μg·kg^-1）和11．13μg-kg^-1（3．31～43．81μg·kg^-1）。土壤有机氯农药的残留以P，p^′-DDE和P，p^′-DDT为主。土壤中HCHs的各异构体组分含量特征为a〉β〉γ〉δ。部分采样点土壤仍可能有新的有机氯污染物来源。

氯代芳烃脱氯速率常数的QSPR研究

测定了钯 /铁 ( Pd/Fe)催化还原水中 8种氯代芳烃的反应速率常数 ;以 PM3算法计算了表征氯代芳烃分子结构的量子化学参数 ,并用一元回归分析对氯代芳烃的分子结构与其催化还原脱氯速率进行了定量结构 -性质相关 ( QSPR)研究 .QSPR模型证明 ,化合物的分子结构决定着催化脱氯反应的快慢 .

固相萃取-高效液相色谱法同时测定自来水中氯代多环芳烃和多环芳烃

建立了自来水中6种氯代多环芳烃和15种多环芳烃的固相萃取-高效液相色谱荧光检测分析方法.500 mL水样过C18固相萃取柱富集,经6 mL的50%甲醇水溶液淋洗,10 mL二氯甲烷-正己烷(1∶1)洗脱.目标化合物经色谱柱(SUPELCOSILTMLC-PAH柱,150 mm×4.6 mm,5μm)分离后,荧光检测,外标法定量.结果表明,21种目标化合物在线性范围内线性关系良好,相关系数均大于0.999;目标化合物的加标回收率为70%—98%,相对标准偏差(RSD) 0. 6%—8. 8%;方法的检出限(LOD,S/N=3)为0. 3—5. 0 ng·L^(-1),定量限(LOQ,S/N=10)为1.1—16.7 ng·L^(-1).方法简便快速,可用于自来水中氯代多环芳烃和多环芳烃的检测.

自动索氏抽提-凝胶渗透色谱(GPC)-气相色谱/质谱法测定沉积物中多环芳烃和有机氯农药

采用自动索氏抽提-凝胶渗透色谱(GPC)-气相色谱/质谱技术,建立了沉积物中多环芳烃和有机氯农药的检测方法.通过对自动索氏抽提提取条件、凝胶渗透色谱净化条件进行优化.以丙酮∶正己烷(V∶V=1∶1)作为提取溶剂,提取温度160℃,用乙酸乙酯∶环己烷(V∶V=1∶1)定容至40 mL,转移上GPC.GPC在线浓缩系统真空腔真空度为180 mbar/190 mbar,以乙酸乙酯∶环己烷(V∶V=1∶1)为流动相,流速为5 mL·min-1,并采用气相色谱-质谱法定性和定量分析.在优化条件下,16种多环芳烃和19种有机氯农药在10—1000μg·L-1范围内具有良好的线性关系(R2>0.99),检出限(S/N=3)为0.008—0.353μg·kg-1.加标水平为10、50、100μg·kg-1时,平均加标回收率分别为77.6%—106.1%、79.9%—108.7%和80.6%—107.8%,相对标准偏差(RSDs,n=5)均小于10%.

近红外光谱法测定柴油中的芳烃含量

研究了采用近红外光谱测定柴油中芳烃含量的方法。通过高效液相色谱分离、移动丝氢火焰检测器检测获得柴油中芳烃的基础数据。在５０００～１００００ｃｍ－１波长范围内，应用傅立叶变换近红外光谱仪，交互检验偏最小二乘方法对使用的光谱范围进行优化。所得校正模型对训练集样品预测的平均偏差为０２３％，对未知样品将近红外预测结果与ＨＰＬＣ的测定结果比较，平均偏差为０２７％。作为一种快速分析技术，近红外光谱测定柴油中的芳烃含量是简便可靠的方法。

污水处理厂芳香烃和氯代烃逸散速率研究

以哈尔滨某城市污水处理厂中的芳香烃（苯，甲苯，二甲苯）和氯代烃（三氯甲烷，四氯化碳三氯乙烯，四氯乙烯）为研究对象，应用不同的数学模型计算了在不同季节条件下其在格栅、初沉池、生化池（厌氧段和曝气段）、二沉池处理单元中的逸散速率．结果表明，芳香烃和氯代烃在生化池逸散速率最高，苯和三氯乙烯的逸散速率分别为1.92-5．22g／s和16.94-18.8g／s．芳香烃逸散速率不符合《大气污染物综合排放标准（GB16297-1996）》．芳香烃的逸散速率在生化池中下降很快，而氯代烃的逸散速率比较稳定．芳香烃和氯代烃在格栅的逸散速率最低，二甲苯和三氯甲烷的逸散速率分别为12.94x10-6-17．24x10-6g／s和1.88×10.-6.2．58×10-6g／s．在沉淀池中，芳香烃和氯代烃春季逸散速率平均为夏季的1.7倍．春季二沉池苯、甲苯和二甲苯的逸散速率分别为初沉池的59.2％，53.3％和4.5％；而二沉池氯代烃逸散速率增加了13％。

新型有机污染物氯代多环芳烃分析方法及其污染现状研究进展

氯代多环芳烃(Chlorinated polycyclic aromatic hydrocarbons,Cl-PAHs)作为多环芳烃的氯代衍生物,具有类似二英的致癌、致畸、致突变毒性,并且广泛存在于环境介质中,对生态环境和人类健康具有一定的潜在威胁.本文介绍了Cl-PAHs在不同环境介质中的分析方法、污染现状、迁移转化及其毒性效应,最后对其未来研究方向进行了展望.在今后,应该加强污泥和沉积物等复杂环境基质中Cl-PAHs的分析方法研究;系统研究ClPAHs在环境介质中的污染现状和迁移转化行为,并开展Cl-PAHs的环境风险和人体健康风险研究.

毒性评估软件TEST及其在农业污染化合物QSAR研究中的应用

应用美国环境保护署(United States Environmental Protection Agency,简称EPA)开发的TEST软件对典型农业污染化合物毒性的QSAR做初步预测。包括TEST软件利用QSAR方法预测化合物毒性所采用的描述符,毒性预测的外部检验方法。之后运行软件就对农产品污染较大的多环芳烃和氯代苯的毒性进行预测,预测值与试验值间的误差不大,TEST软件能快速输出分析结果。通过对毒性评估软件TEST的学习,最后就软件的优缺点进行简单的分析。

湛江近海域沉积物含氯多环芳烃对斑马鱼胚胎的毒性研究

为探究湛江近海域海洋沉积物中含氯多环芳烃的生物学毒性效应,选取湛江近海域2个地点(TS和JSW)采集样品,以含氯多环芳烃为目标,制备沉积物提取物,将斑马鱼胚胎胚胎暴露于不同浓度的沉积物提取物中,观测供试斑马鱼胚胎的死亡和畸形情况。结果表明:TS采样点沉积物提取物的LC50为15.98 mg/mL(48 h)和14.41mg/mL(96 h),JSW采样点沉积物提取物的LC50为19.89 mg/mL(48 h)和16.36 mg/mL(96 h),且致死效应呈现浓度依赖关系;TS和JSW 2个采样点沉积物中含氯多环芳烃能导致斑马鱼胚胎卵黄囊水肿、心包水肿、脊椎弯曲等致畸效应,其致畸效应与暴露浓度基本呈浓度依赖关系。湛江近海域沉积含氯多环芳烃物提取物对斑马鱼胚胎具有明显的致死作用和致畸毒性。

结构-活性关系对氯代多环芳烃性质的预测

氯代多环芳烃(chlorinated polycyclic aromatic hydrocarbons,Cl-PAHs)作为多环芳烃的氯代衍生物,具有类似二噁英的致癌、致突变毒性,并在环境中广泛存在.利用结构-活性关系及逸度模型对该新型有机污染物进行性质及环境归趋的预测.结果表明,随着氯原子取代数的增加,Cl-PAHs的毒性会有所增强,且在环境中更趋向富集于土壤和底泥中,具有与二噁英类似的环境行为.

近红外光谱法测定汽油中的芳烃含量

研究了采用近红外光谱测定汽油中芳烃含量的方法,通过汽油单体分析法获得汽油中芳烃的基础数据。在1000～2000nm波长范围内,应用傅立叶变换近红外光谱仪,交互检验偏最小二乘法对使用的近红外光谱数据进行优化,所得校正模型对训练集样品预测的相对平均误差为0.42%,相关系数为0.9696。对未知样品将近红外预测结果与GC的测定结果进行比较,相对平均误差为0.45%。作为一种快速分析技术,近红外光谱测定汽油中芳烃含量是简便可靠的方法。