Relative proportions of polycyclic aromatic hydrocarbons differ between accumulation bioassays and chemical methods to predict bioavailability

Chemical methods to predict the bioavailable fraction of organic contaminants are usually validated in the literature by comparison with established bioassays. A soil spiked with polycyclic aromatic hydrocarbons (PAHs) was aged over six months and subjected to butanol, cyclodextrin and tenax extractions as well as an exhaustive extraction to determine total PAH concentrations at several time points. Earthworm (Eisenia fetida) and rye grass root (Lolium multiflorum) accumulation bioassays were conducted in parallel. Butanol extractions gave the best relationship with earthworm accumulation (r² ≤ 0.54, p ≤ 0.01); cyclodextrin, butanol and acetone-hexane extractions all gave good predictions of accumulation in rye grass roots (r² ≤ 0.86, p ≤ 0.01). However, the profile of the PAHs extracted by the different chemical methods was significantly different (p < 0.01) to that accumulated in the organisms. Biota accumulated a higher proportion of the heavier 4-ringed PAHs. It is concluded that bioaccumulation is a complex process that cannot be predicted by measuring the bioavailable fraction alone.     

Configuration predictions of large liquefied petroleum gas (LPG) pool fires using CFD method

Liquefied petroleum gas (LPG) has potential pool fire risks due to its flammability. The configuration of pool fires plays a significant role when applying the solid flame model or point source model to assess the risks from heat radiation. However, no existing correlations can precisely predict the configuration of large LPG (100% propane) pool fires. To enhance the fundamental understanding on how pool diameter and wind velocity can influence the configuration of large LPG pool fires, an experimentally validated Computational Fluid Dynamics (CFD) model is employed to simulate fires using different burning rate models. Fire temperature profiles, flame heights, and flame tilts predicted by the CFD model were compared with empirical models and experimental data. Accordingly, new correlations for flame height and flame tilt as functions of pool diameter D and wind velocity u_w have been developed. The comparisons demonstrate that the new correlations have the best overall accuracy in the prediction of flame height and tilt for large LPG pool fires under different conditions (10 m ≤ D ≤ 20 m, 0 ≤ u_w ≤ 3 m·s⁻¹).     

土壤中芘、菲、萘、苯对小麦的生态毒性影响

采用生物培养和物理化学试验,研究了芘、菲、萘、苯对土壤中小麦的生态毒性.结果表明,芘对小麦根毒害的敏感区间浓度为0～300mg/kg;土壤中芘的50%小麦根伸长抑制率浓度为500mg/kg.PAHs的生态毒性与其溶解度和结构有关,且随着溶解度的增大和苯环数目的减少而增加.PAHs会降低土壤的土水势,土水势降低的程度随着PAHs溶解度的增大而增大.     

南京大气气溶胶中多环芳烃源识别及污染评价

采用GC、GC-MS等方法,研究了南京市不同功能区夏、冬季大气气溶胶中多环芳烃(PAHs)的污染状况和污染来源,并对不同功能区的PAHs进行了污染评价.结果表明,南京市各功能区气溶胶中PAHs总量在19.73～497.40ng/m³之间,且冬季高于夏季,细颗粒中含量高于粗颗粒.通过一些特征标志PAHs的比值,可判断夏季各功能区的PAHs污染主要来自于汽车尾气(主要是柴油型)的排放,冬季则为汽车尾气和燃煤污染.采用苯并(a)芘(BaP)及苯并(a)芘等效致癌浓度(BaPE)来评价5个功能区气溶胶中PAHs的污染状况,夏季除交通干道超过国家标准(BaP,10ng/m³),居民区细颗粒中略超过居民区标准(BaP,5ng/m³)外,空气质量良好.而冬季各功能区PAHs基本上均严重超标.     

南宁市街区挥发性有机物暴露水平初步分析

通过多层吸附管采样和热脱附-气相色谱-质谱联用对南宁市街区及市郊青秀山的挥发性有机物(VOCs)暴露水平进行了分析.结果显示:南宁市街道大气VOCs中一些毒害性苯系物的质量浓度较高,其中苯、甲苯的平均质量浓度分别达到47.5和159.2 μg/m3,分别是对照点青秀山的2.9和2.0倍;苯及其取代物的特征显示,南宁市街区VOCs主要来自机动车的尾气,同时一些公共活动场所苯系物比值和变化特征有所不同,显示出除交通尾气外的其他来源对挥发性有机物的贡献.      

地下水石油污染高效生物降解研究

考察了高效复合微生物对地下水石油污染物降解效果,并建立了地下水污染质生物降解迁移数学模型.从石油污染的土壤中分离筛选到能够高效降解石油的菌株,经鉴定为假单胞菌属、黄杆菌属和微球菌属,这3种菌属24h对石油降解率分别为62%,56%和52%,且3种菌属组成的复合菌较单一菌属对石油降解率都要高,达85%.高效复合菌与石油配水一起进入模拟地下含水介质的反应器,在反应器前部均能形成一个稳定的生物带.石油配水流经该生物带,石油降解率可达60%以上,反应器出水石油降解率平均可达90%以上.建立的地下水污染质生物降解迁移数学模型对地下水有机污染质生物降解有较好的预测效果,计算值与实测值呈良好的相关性.     

多环芳烃光解活性的量子化学研究

应用量子化学从头算HF／6-311 G(d)和B3LYP／6-311 G(d)方法计算了16种PAHs的多种量子化学参数,选取六种参数为分子结构的描述符,采用最小二乘法对16种PAHs的光解半衰期进行逐步多元线性回归分析,得到两个PAHs光解半衰期的QSAR模型,模型具有较高的相关系数,可有效地用于预测PAHs的光解半衰期,结果表明,HF方法所得模型优于B3LYP方法所得的模型,所得模型与基于半经验PM3算法的QSAR模型相比较,HF从头算方法所建立的QSAR模型比半经验PM3算法的结果要好,在所考查的诸多参数中,分子最高占有轨道特征值EHOMO对PAHs光解半衰期起着决定作用,最后,运用所得模型预测了3种PAHs的光解半衰期。     

导数恒能量同步荧光法同时分析咔唑、苯并(a)芘、苝和2,3-苯并蒽

建立了咔唑、苯并(a)芘、苝和2,3-苯并蒽四组分同时测定的导数恒能量同步荧光分析法,该法简便快速,无需对混合物进行分离,只需一次扫描,就可实现四组分的同时鉴别和定量测定．该方法用于海水、自来水和大气飘尘的分析,取得了良好的效果,回收率分别为94％-104％,91．7％-104％和82．3％-112．5％．     

大庆贴不贴泡周边土壤及地下水石油烃污染规律

贴不贴泡是大庆某石油化工总厂生产废水排放场地,其作用相当于一个水面较大的氧化塘.在纳污泡周边分别采集土壤及地下水样品,以研究其对周边土壤及地下水的污染状况.结果显示:纳污泡附近地下水及表层土壤受到不同程度石油烃污染,但除第1个采样点外,其余各采样点污染程度随距离变化不明显;土壤纵向以40～60cm厚度层污染最为严重.说明大庆地区草甸黑土对石油烃滞留能力很强,使石油烃在其中的迁移速度很低,特别是水平迁移速度更小,才使污染近30年的场地地下水受到的石油烃污染不是十分严重.表层土壤的污染主要是由于雨季纳污泡内污水溢出造成的.      

优势短杆菌对多环芳烃的降解性能

本研究从长期被焦化废水污染的污泥中分离出一株优势短杆菌研究该菌株及其在无机离子存在下对蒽、菲、芘的降解性能.结果发现该菌株对蒽、菲、芘均有良好的降解效果,Fe³⁺对降解过程有促进作用,反应10h后,蒽、菲、芘转化率分别可达约75%,87%,及62%.总有机碳(TOC)的测定结果表明,该菌株在106h内能分别将反应瓶中加入的蒽、菲、芘所产生的总有机碳去除50%、90%及50%.