Exposure and effects assessment of persistent organohalogen contaminants in arctic wildlife and fish

Persistent organic pollutants (POPs) encompass an array of anthropogenic organic and elemental substances and their degradation and metabolic byproducts that have been found in the tissues of exposed animals, especially POPs categorized as organohalogen contaminants (OHCs). OHCs have been of concern in the circumpolar arctic for decades. For example, as a consequence of bioaccumulation and in some cases biomagnification of legacy (e.g., chlorinated PCBs, DDTs and CHLs) and emerging (e.g., brominated flame retardants (BFRs) and in particular polybrominated diphenyl ethers (PBDEs) and perfluorinated compounds (PFCs) including perfluorooctane sulfonate (PFOS) and perfluorooctanic acid (PFOA) found in Arctic biota and humans. Of high concern are the potential biological effects of these contaminants in exposed Arctic wildlife and fish. As concluded in the last review in 2004 for the Arctic Monitoring and Assessment Program (AMAP) on the effects of POPs in Arctic wildlife, prior to 1997, biological effects data were minimal and insufficient at any level of biological organization. The present review summarizes recent studies on biological effects in relation to OHC exposure, and attempts to assess known tissue/body compartment concentration data in the context of possible threshold levels of effects to evaluate the risks. This review concentrates mainly on post-2002, new OHC effects data in Arctic wildlife and fish, and is largely based on recently available effects data for populations of several top trophic level species, including seabirds (e.g., glaucous gull (Larus hyperboreus)), polar bears (Ursus maritimus), polar (Arctic) fox (Vulpes lagopus), and Arctic charr (Salvelinus alpinus), as well as semi-captive studies on sled dogs (Canis familiaris). Regardless, there remains a dearth of data on true contaminant exposure, cause-effect relationships with respect to these contaminant exposures in Arctic wildlife and fish. Indications of exposure effects are largely based on correlations between biomarker endpoints (e.g., biochemical processes related to the immune and endocrine system, pathological changes in tissues and reproduction and development) and tissue residue levels of OHCs (e.g., PCBs, DDTs, CHLs, PBDEs and in a few cases perfluorinated carboxylic acids (PFCAs) and perfluorinated sulfonates (PFSAs)). Some exceptions include semi-field studies on comparative contaminant effects of control and exposed cohorts of captive Greenland sled dogs, and performance studies mimicking environmentally relevant PCB concentrations in Arctic charr. Recent tissue concentrations in several arctic marine mammal species and populations exceed a general threshold level of concern of 1 part-per-million (ppm), but a clear evidence of a POP/OHC-related stress in these populations remains to be confirmed. There remains minimal evidence that OHCs are having widespread effects on the health of Arctic organisms, with the possible exception of East Greenland and Svalbard polar bears and Svalbard glaucous gulls. However, the true (if any real) effects of POPs in Arctic wildlife have to be put into the context of other environmental, ecological and physiological stressors (both anthropogenic and natural) that render an overall complex picture. For instance, seasonal changes in food intake and corresponding cycles of fattening and emaciation seen in Arctic animals can modify contaminant tissue distribution and toxicokinetics (contaminant deposition, metabolism and depuration). Also, other factors, including impact of climate change (seasonal ice and temperature changes, and connection to food web changes, nutrition, etc. in exposed biota), disease, species invasion and the connection to disease resistance will impact toxicant exposure. Overall, further research and better understanding of POP/OHC impact on animal performance in Arctic biota are recommended. Regardless, it could be argued that Arctic wildlife and fish at the highest potential risk of POP/OHC exposure and mediated effects are East Greenland, Svalbard and (West and South) Hudson Bay polar bears, Alaskan and Northern Norway killer whales, several species of gulls and other seabirds from the Svalbard area, Northern Norway, East Greenland, the Kara Sea and/or the Canadian central high Arctic, East Greenland ringed seal and a few populations of Arctic charr and Greenland shark.     

不同变质程度煤的碳结构特征及其演化机制

应用X射线衍射(XRD)与核磁共振碳谱测试(13C-NMR)相结合的方法,对5个不同变质程度煤(WMC长焰煤、LL3焦煤、LL4焦煤、CZ无烟煤与SH无烟煤)的碳结构特征及其演化进行了研究。结果表明：(1)变质程度是影响煤中碳结构演化的最重要因素。随着煤变质程度的增加,煤中芳碳率增大,芳香核缩聚程度增加,芳香结构单元排列趋于有序。(2)变质环境对煤的碳结构演化具有重要影响。高温低压环境下,WMC煤中芳香结构单元发生超前演化,形成一系列堆垛高度大延展度小的芳香结构体系;脂肪类物质中,一方面脂肪侧链发生快速热解,形成较多的环甲基,另一方面煤中已有的脂肪环发生热解断裂,形成新的脂肪链,导致支链化程度增加。(3)中等变质程度的LL4与LL3煤中发生了显著的脂环化作用,导致其季碳含量明显增高,支链化程度降低。(4)随着变质程度增加,CZ与SH煤样中,脂肪环发生断裂,形成新的脂肪链致使支链化程度增加,成为高变质程度煤中形成更大芳香体系的前奏。     

By‐products formation in catalytic combustion of aromatic compounds over a pt‐based catalyst

By‐products formation in the catalytic combustion of different aromatic compounds has been experimentally investigated. A commercial Pt‐based catalyst, in the shape of a short monolith, has been employed. Toluene, styrene, o‐xylene and cumene have been tested at low concentrations for conversions in the range 5–50%. The results confirm the formation of benzene in the combustion of toluene and styrene, as previously observed by other researchers, but in a very small amount; testing cumene, significant amounts of acetone have been found in the outlet flow. Some hypothesis about the reaction mechanism are put forward.     

HPLC determination of polycyclic aromatic hydrocarbons (PAHs) in the littoral urban sewage area of cortiou (Marseille,France)

A selective method for determining polycyclic aromatic hydrocarbons (PAHs) in sediments using solid‐phase extraction and RP‐HPLC with fluorescence and UV detection is described. The complete analytical method is used to surface sediments from the creek of Cortiou (France). Sewage from the urban area of Marseille is delivered to the creek. PAH levels in sediments (µg/g) range between 2.251 µg/g (for the benzo(a)anthracene) and 相似文献   

Fatty acids,sterols, and tocopherols composition in seed oil extracts from four moroccan ecotypes of Ceratonia siliqua L.

Morphological characterization was investigated by agro-morphological criteria related to carob seed size in four different moroccan regions collected in 2018 and 2019. There was no significant difference (p ≤ 0.05) on the seeds lengths and widths. However, a significant difference between seeds thickness and total seeds weight per pod (p ≤ 0.05) were observed between these four populations. The fatty acid, sterol, tocopherol, hydrocarbon, and the unoxygenated composition of carob seed extracts (Ceratonia siliqua L.) were studied. The mean fat yield of the seeds obtained is 1.53%–2.17%, 2.14%–2.15%, 1.61%–1.62%, 1.71%–1.75% for, respectively, the P1 (Meknes), P2 (Fez), P3 (Khemisset), and P4 (Marrakech) in 2018 and 2019. The seed oil was extracted with hexane and the analysis of the fatty fraction was performed by gas chromatography–mass spectrometry (GC–MS). Results show that the major fatty acids for 2018 and 2019 are linoleic acid (61.48%–61.52%, 52.12%–52.14%, 57.76%–58.15%, 61.33%–61.52%), palmitic acid (15.78%–15.81%, 16.44%–16.45%, 19.11%–18.37%, 20.24%–20.32%), oleic acid (11.03%–11.04%, 8.72%–8.82%, 8.51%–8.61%, 8.41%–8.53%), stearic acid (4.35%–3.14%, 5.40%–5.43%, 3.12%–3.13%, 0.96%–1.56%), and cerotic acid (0.62%–0.53%, 4.51%–4.52%, 4.03%–4.06%, 3.84%–3.87%). The unsaturated fatty acids (69.39% in 2018 and 69.68% in 2019) are the most dominant in the four seed extracts compared to the saturated fatty acids. In addition, the oil carob seeds analysis revealed the presence of γ-tocopherol, α-tocopherol and four sterols that included campesterol, stigmasterol, and β-sitosterol. Moreover, the determination of hydrocarbon and un-oxygenated compounds confirmed the existence of major compounds such as heptadecane, 2-methyltriacontane, 1-iodo hexadecane and 1-iodo octadecane. The hierarchical analysis based on the morphological and chromatographic characterization of the seeds allowed the identification of three groups. Consequently, the first group consisted of populations from Marrakesh (P4) and Khemisset (P3), the second group consisted of the P1 from Meknes, and the P2 from Fez constituted the third group.     

能量分解前提下萃取剂的选择策略

煤焦油物质丰富、组成复杂,其中,含杂原子的芳香族化合物以及稠环芳烃具有极高的工业应用价值,但是难以通过石化行业获取。如何“破坏”杂原子芳香族化合物和稠环芳烃间的缔合作用,是高效分离的关键和萃取剂选择难点。若对待分离体系中各物质之间的“缔合结构”有清晰的认识,便可根据不同的能量范围设计萃取剂。据此,基于分子力场分析,获得了氮/硫杂原子芳香族化合物色散作用能的范围,约为 -15~-70 kJ/mol,比照分析低共熔溶剂萃取氮/硫杂原子芳香族化合物研究动态,对增强分子间相互作用的调控手段归类,印证了可以根据待分离体系不同的能量范围来选择萃取剂,这种萃取剂选择方法可以作为分离杂原子芳香族化合物和稠环芳烃的一种新策略。     

芳香族支链聚酰胺6的制备及共混纺丝研究

通过添加均苯四甲酸二酐水解聚合工艺制备芳香族支链聚酰胺6(PA6),采用熔融共混制备芳香族支链PA6/Ti O2母粒,然后与线型PA6共混纺丝,经拉伸后得到含芳香族支链PA6的共混纤维;研究了均苯四甲酸二酐含量对芳香族支链PA6流动性及热学性能的影响,以及芳香族支链PA6对芳香族支链PA6/Ti O2共混物结晶行为、可纺性及纤维力学性能等的影响。结果表明:随着均苯四甲酸二酐含量的添加,芳香族支链PA6的相对黏度逐渐降低,熔体流动指数增大,流动性增加,而结晶熔融温度逐渐降低;含芳香族支链PA6的共混体系纺丝温度较纯PA6降低4℃,芳香族支链PA6有助于提高PA6的可纺性,且纤维力学性能较好,含质量分数8%芳香族支链PA6的共混纤维的断裂强度为2.8 c N/dtex,断裂伸长率为45.4%。     

马来酸酐改性腰果壳油对丁苯橡胶性能的影响

以马来酸酐接枝共聚改性环氧基腰果壳油(M-CNSL)作为反应性增塑剂,研究M-CNSL用量对丁苯橡胶(SBR)硫化特性、物理性能和耐热空气老化性能的影响,并与芳烃油和未改性腰果壳油(CNSL)进行对比试验。结果表明:不同增塑剂对SBR的增塑作用从大到小依次为CNSL、芳烃油、M-CNSL,而其硫化胶的耐热空气老化性能没有明显差别;加入CNSL的SBR胶料焦烧时间和正硫化时间显著延长,硫化胶硬度、100%定伸应力较小,拉断伸长率较大;在0~25份用量范围内,添加CNSL或M-CNSL的硫化胶拉伸强度和撕裂强度均出现一个最大值,而添加芳烃油的硫化胶拉伸强度和撕裂强度随着增塑剂用量的增大而减小。硫化胶拉伸断面扫描电镜分析结果表明,M-CNSL的加入有利于白炭黑在胶料中的分散,起到了相容作用。     

芳烃抽提蒸馏装置生产运行问题分析

文章针对目前困扰芳烃抽提蒸馏装置正常运行的问题,通过化工计算软件绘出各种操作条件下环丁砜溶剂的特性曲线,进而找出问题的根源,并提出相应技术改造措施,希望为今后装置平稳运行和改造提供参考。     

几种C_6～C_8重整芳烃脱烯烃技术的工程比选

C6~C8重整芳烃脱烯烃的目的是为了生产合格的苯、甲苯以及二甲苯产品,本文介绍了国内外几种整芳烃脱烯烃的技术的概况,并以某芳烃抽提装置为例,根据不同的脱烯烃技术在流程、催化剂选用上的差异,从主要技术指标和经济指标的角度分析对比,从而选出适合作为特定装置的工程设计方案。