Spatial Distributions of Legacy Contaminants in Sediments of Lakes Huron and Superior

The sediments of Lake Superior, Lake Huron, and Georgian Bay were sampled in 2001 and 2002 in order to evaluate the extent of surficial sediment contamination of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCs), polycyclic aromatic hydrocarbons (PAHs), and metals. Sediment concentrations of PCBs, OCs, PAHs, and mercury were generally low and up to 2 orders of magnitude less than in Lakes Erie and Ontario. In contrast, concentrations of metals such as arsenic, copper, and nickel were comparable to those in Lakes Erie and Ontario. These elevated Lakes Superior and Huron metal concentrations were attributed to naturally occurring metals within the bedrock, soil, and sediment of the study region. Concentrations of all contaminants were typically below the Canadian Sediment Quality Probable Effect Level (PEL) guidelines. With regard to spatial patterns, most contaminants were focused primarily in the depositional basins and atmospheric deposition was likely the major source of these chemicals to the lakes. The major exception was for metals (not including mercury) whose patterns were also influenced by natural sources as well as extensive mining activity. A comparison between surficial sediment contamination of samples collected as part of this survey and those collected in the late 1960s/early 1970s using similar methods showed that concentrations of DDT, PCB, lead, and mercury were generally similar between these two time periods. These results are not consistent with production and usage patterns that have declined substantially in the past 3 decades. We hypothesize that the lack of temporal trends is an artifact due to slow sediment accumulation rates as well as differences in analytical protocols between the two time periods.     

炼焦粉尘中多环芳烃的赋存特性

通过对焦化厂不同地点的粉尘采样,并进行粒度分级、超声波预处理及高效液相色谱分析,得到多环芳烃（PAHs）的赋存特性。在采集的样品中,地面除尘站粉尘仓的粉尘中PAHs的含量最高,达到1880．83μg／g。在焦化粉尘中,PAHs明显表现出对小粒径粉尘的富集特性,粉尘中单组分的PAHs含量差别较大,以4～6环的PAHs居多。此外,地面除尘站粉尘仓的粉尘样品中含有大量的苯并[a]芘。     

丁烷层流预混火焰多环芳烃生成化学动力学模拟

近年来,随着环保要求的不断提高,碳氢燃料燃烧过程中多环芳烃(polycyclic aromatic hydrocarbons,PAHs)形成、生长和氧化的详细反应动力学研究成为热点。该文通过更新的层流预混火焰中描述丁烷热分解、氧化,苯的形成,多环芳烃生成及氧化等过程的详细机制反应模型,对层流预混C4H10/O2/Ar稳态火焰中芳香烃和多环芳烃的形成和生长进行动力学模拟计算,获得火焰中反应区和燃尽区反应物、主要燃烧产物、中间组分及PAHs的浓度分布,同时采用敏感系数分析法确定了丁烷火焰中影响PAHs生成的主要基元反应。研究结果表明:采用的更新机制模型能够很好地预测丁烷火焰中大多数低分子量的脂肪烃、燃烧副产物、中间组分及PAHs的浓度分布;丙炔基(H2CCCH)的化合反应是苯环生成的主要反应序列;萘(C10H8)生成的主要步骤是环戊二烯基(c-C5H5)的化合反应,活化分子茚基与c-C5H5反应可以形成大量的菲(C14H10);同时模型更近一步论证了PAHs生成的"脱氢加乙炔"机制。     

微孔沸石对卷烟烟气中多环芳烃去除的机理研究

通过多环芳烃（polycyclic aromatic hydrocarbon,PAHs）荧蒽（fluoranthene,Flu）和蒽（anthracene,Ant）在微孔沸石Y、ZSM-5和NaA上的吸附和催化裂解实验,探讨了沸石对卷烟烟气中PAHs选择性去除作用机理。实验结果表明：Y型沸石能吸附和催化裂解Flu和Ant;ZSM-5沸石能吸附和催化裂解Ant而不能吸附Flu;NaA沸石受孔径限制,不能吸附和催化裂解Ant和Flu。然而,将这些沸石添加到卷烟中,它们都不同程度地减少了烟气中B[a]P、Ant和Flu的含量。结合沸石吸附PAHs的红外图谱及量子化学计算结果：微孔沸石对卷烟烟气中PAHs的去除不是直接吸附或催化降解,而是吸附了形成PAHs的中间体/前体从而减少了PAHs的生成。     

Effect of Dietary Red Meat on Colorectal Cancer Risk—A Review

Heme iron overload has been implicated as the main cause of the increased risk of cancer due to the consumption of red meat. However, fish and shellfish, teas, and spices contain up to five times more iron than red meat. There is insufficient evidence that iron intake in dietary red meat is the primary causal factor for colorectal cancer. In addition, harmful substances produced during the preparation of red meat, including heterocyclic amines (HCAs), polycyclic aromatic hydrocarbons (PAHs), N‐nitroso compounds, and acrylamide, are extrinsic factors that increase carcinogenicity. HCAs are produced during the cooking of red meat, poultry meat, and fish. PAHs may also be produced during the cooking of diverse food groups, such as dairy products, fruits, vegetables, and cereals. The average daily intake of red meat among Korean individuals is 62 g; the amount of PAHs entering the body via red meat is less than the average amount of PAHs the body is exposed to in the air. Therefore, it is difficult to conclude that dietary red meat is the main cause of colorectal cancer. Rather, there may be an intricate influence of multiple factors, including fruit and vegetable intake, alcohol consumption, smoking, overweight, obesity, and stress.     

烤肉中多环芳烃的污染情况和健康风险评价

通过HPLC法测定45批烤肉中15种PAHs的含量,分析烤肉中 PAHs的组成特征和毒性分布情况,定量评价吃烧烤频率对于社会人群终生患癌的风险。结果表明:烤肉中15种PAHs组成特征和毒性分布情况表示,PAHs含量组成以二环、三环、四环芳烃为主(87%);而毒性分布方面,主要致癌的风险物质为重质PAHs,以五环PAHs毒性含量最高(81%);健康风险评价表明,社会人群终身患癌风险(ILCR)和摄入烧烤频率(EF)具有正比关系的函数关系(ILCR=3.07692×10-7 EF),大量频繁地摄入烤肉会带来一定的致癌风险,而低频率的摄入烧烤食品,比如一年内三到四次,烧烤食品带来的致癌风险可忽略不计。     

分子印迹-气相色谱-串联质谱法检测烤肉中的14种多环芳烃

目的比较5种不同萃取净化法结合气相色谱-串联质谱法检测烤肉中14种多环芳烃含量的效果。方法样品经提取后,比较中性氧化铝柱、HLB小柱、分子印迹技术、GPC凝胶色谱净化技术、QuEChERS法5种不同萃取净化法的净化效果,确定烤肉中14种多环芳烃检测的最合适前处理技术。结果比较5种净化技术,分子印迹柱和GPC方法在烤肉制品中平均回收率为80%～100%,其他技术的回收率偏低,不符合实验要求。使用分子印迹柱作为前处理方法时, 14种多环芳烃在5～200 ng/mL范围内呈良好线性,相关系数均大于0.995,平均回收率在76.42%～106.8%之间,相对标准偏差为0.8%～7.8%,方法定量限为0.76～1.21μg/kg。结论比较5种方法的净化结果,分子印迹柱和GPC凝胶色谱均能满足检测需求,但分子印迹柱稳定性更好,成本更低,更适用于烤肉中14种多环芳烃残留的检测。     

Evaluation of Polycyclic Aromatic Hydrocarbons Contamination in the Sediments of the Johor Strait,Peninsular Malaysia

In May 2013, sediment samples were collected from five stations in the Straits of Johor, near the southern tip of Peninsular Malaysia, in order to evaluate the distribution and sources of polycyclic aromatic hydrocarbons (PAHs). The concentrations of 16 United States Environmental Protection Agency PAHs varied from 650.5 to 1441.2 ng g ^?1 dry weight (dw) with a mean value of 985.5 ng g ^?1 dw. PAHs can be classified as moderate level pollution in the collected samples. When comparing PAHs in this study with that of the sediment quality guidelines (SQGs), it was found that the total PAHs, low molecular weight (LMW), and high molecular weight (HMW) PAHs might incur minimal adverse biological effects. The diagnostic ratios of individual PAHs indicated both petrogenic and pyrogenic origins with predominantly pyrogenic sources, the findings of which are further supported by the results from principal component analysis (PCA). The PCA results reveal contributions of 44.44%, 32.3%, and 18.96% for traffic-related, coal combustion, and petroleum-related products, respectively. These findings indicate that the effective monitoring and significant improvement resulting from the implementation of environmental regulations in Malaysia might have caused a shift in the source of petroleum hydrocarbons in the Straits of Johor's aquatic ecosystems from petrogenic to pyrogenic origins.     

Isolation and Characterization of Phenanthrene-Degrading Bacteria from PAHs Contaminated Mangrove Sediment of Thane Creek in Mumbai,India

Polycyclic aromatic hydrocarbons (PAHs), including phenanthrene, are commonly found as pollutants in soils, estuarine, and sediments, as well as in terrestrial and other aquatic ecosystems. In this context, the phenanthrene-degrading bacteria were isolated and characterized in contaminated mangrove surface sediment, on the coast of Thane Creek, Mumbai, India by enrichment method, using phenanthrene as the sole source of carbon and energy. The phylogenetic diversity of the isolates were evaluated by 16S rRNA gene analysis and characterized as Bacillus mojavensis strain KSS001, Bacillus firmus strain KSS002, Bacillus flexus strain KSS003, Bacillus vietnamensis strain KSS004, and Bacillus amyloliquefaciens strain KSS005. Each isolate was grown on the phenanthrene up to 100 mg/L and the biodegradation ability was evidenced using a gas chromatography–flame ionization detector. Further, the mean value of phenanthrene degradation by 5 bacterial isolates after incubation in mineral salt medium for 7 days was 63% at 100 mg/L. The study reports that mangrove sediments of Thane Creek, Mumbai, contain a diverse population of phenanthrene-degrading bacteria that have the potential and capability to degrade PAHs contaminated sites, and are consequently recommended for bioremediation.