长江三角洲上新世以来磁性地层及天文调谐年代标尺

长江三角洲地区的磁性地层认识存在很大不确定性.为建立一个可靠的年代标尺,为区内沉积环境和气候演化研究提供约束,在年代地层和磁性地层基础上,以频率磁化率为信号源、ETP为靶曲线,通过轨道调谐方法对区内LZK1孔开展了天文年代标尺研究,建立了年代序列框架.结果显示,M/B界线埋深约为143.0m、Ga/M界线埋深约为219.0m、Gi/Ga界线埋深约为296.6m.受气候和沉积环境控制,沉积旋回特征清楚,沉积速率具有明显的阶段性.调谐后的频率磁化率显示了显著的125ka、96ka、41ka、23ka、22ka、18ka等轨道周期,并在轨道周期上与ETP曲线高度相关,相关性超过了95%检验标准. 100ka、41ka和23ka周期的带通滤波曲线与偏心率、斜率和岁差在振幅和相位上吻合较好,但局部时间段有差异,可能与低沉积速率、沉积速率突变或短时间尺度的地层缺失等因素有关.研究表明,在具有短暂沉积缺失的持续沉降区域,只要保证样品分辨率,可以通过轨道调谐方法建立可靠的年代框架.</p

成都城区PM_(2.5)季节污染特征及来源解析

于2009&mdash;2010年各季节典型月在成都城区采集了大气PM_(2.5)样品,对PM_(2.5)的质量浓度及其主要化学成分(含碳组分、水溶性无机离子和元素)进行了测定. 结果显示:成都城区PM_(2.5)平均质量浓度高达(165.1&plusmn;85.1)&mu;g&middot;m~(-3),是国家环境空气质量标准年均PM_(2.5)限值的4.7倍. OC、EC和水溶性二次离子(SO_4~(2-),NO_3~-和NH_4~+)的平均浓度分别为(22.6&plusmn;10.2)&mu;g&middot;m~(-3),(9.0&plusmn;5.4)&mu;g&middot;m~(-3)和(62.8&plusmn;44.3)&mu;g&middot;m~(-3),分别占PM_(2.5)浓度的13.7%、5.5%和38.0%. PM_(2.5)及其主要化学成分浓度季节特征明显,即秋冬季高于春夏季. 利用正交矩阵因子分析(PMF)对成都城区PM_(2.5)的来源进行解析,结果表明,土壤尘及扬尘、生物质燃烧、机动车源和二次硝酸盐/硫酸盐的贡献率分别为14.3%、28.0%、24.0%和31.3%. 就季节变化而言,生物质燃烧源贡献率在四个季节均维持在较高水平;土壤尘及扬尘的贡献率在春季显著提高;机动车源的贡献率在夏季中表现突出;而二次硝酸盐/硫酸盐的贡献率在秋冬季中则最为显著.</p

浓香菜籽油和精炼菜籽油氧化稳定性 及挥发性成分的差异Differences of oxidative stability and volatile components between fragrant and refined rapeseed oils

利用烘箱法加速氧化试验分析研究浓香菜籽油和精炼菜籽油氧化稳定性及挥发性成分变化的差异。结果显示：基于过氧化值达到国标限量（≤5 mmol/kg）的精炼菜籽油、浓香菜籽油的预测货架期分别为64 d和80 d，浓香菜籽油的氧化稳定性明显优于精炼菜籽油；利用同时蒸馏萃取结合气相色谱-质谱联用法（SDE-GC-MS）对两种菜籽油中挥发性成分进行检测分析发现，在初始浓香菜籽油和精炼菜籽油中分别检出10类84种和6类51种挥发性成分，总量分别为11 110.78 μg/kg和3 831.28 μg/kg；浓香菜籽油中含量最高的是硫苷降解产物，其次是烯烃类和酚类物质，分别占总量的32.04%、22.74%、22.22%；精炼菜籽油中含量最高的是酚类物质，其次是醛类和酮类物质，分别占总量的30.32%、23.18%、16.39%，硫苷降解产物、杂环类、酯类、醇类物质均未检出。35 d的试验结束时，浓香菜籽油和精炼菜籽油中挥发性成分总量均大幅升高，分别为51 729.62 μg/kg和45 671.79 μg/kg，醛类物质成为两种菜籽油中含量最高的挥发性成分，分别占总量的60.30%和68.07%；浓香菜籽油中硫苷降解产物大幅降至仅占总量的2.64%，同时杂环类物质含量大幅降低，酮类、烯烃类、烷烃类物质含量大幅升高；精炼菜籽油中酮类、烷烃类、烯烃类物质含量升高，醇类物质从初始的未检出升高至占总量的13.10%。对挥发性成分进行主成分分析发现，造成两种初始菜籽油差异的挥发性成分主要为苯代丙腈、3-甲基-2-丁腈、2-蒎烯、5-己烯腈、4-乙烯基-2,6-二甲氧基-苯酚，这些物质为浓香菜籽油提供独特风味；在加速氧化试验后期，造成两种菜籽油差异的成分则主要为1-戊烯-3-醇、1-辛烯-3-醇、（E）-2-戊烯醛、(E)-2-庚烯醛、正己醛、壬醛、甲基庚烯酮、(E,E)-3，5-辛二烯-2-酮、白菖烯、甲基环己烯10种物质，且前5种物质与精炼菜籽油相关，多为亚油酸氧化产物，后5种物质则主要与浓香菜籽油相关。研究结果明确了不同工艺生产的菜籽油产品的综合品质差异，可为不同菜籽油产品精准的保质保鲜技术发展提供支持。 An Schaal oven accelerated oxidation experiment was used to examine the differences of oxidative stability and volatile components between fragrant and refined rapeseed oils.The results showed that based on the peroxide value reaching the national standard limit (≤ 5 mmol/kg), the predicted shelf life of refined and fragrant rapeseed oils were 64 d and 80 d, respectively, and the oxidative stability of fragrant rapeseed oil was considerably better than that of refined rapeseed oil. The simultaneous distillation extraction combined with gas chromatography-mass spectrometry (SDE-GC-MS)was used to detect the volatile components in the two kinds of rapeseed oil,and the results revealed that 84 volatile components of 10 categories and 51 volatile components of 6 categories were detected in the initial fragrant rapeseed oil and refined rapeseed oil, respectively, with total amounts of 11 110.78 μg/kg and 3 831.28 μg/kg. The most abundant component in fragrant rapeseed oil was glucosinolate degradation products, followed by alkene and phenols, accounting for 32.04%, 22.74% and 22.22% of the total, respectively. The most abundant component in refined rapeseed oil was phenols, followed by aldehydes and ketones, accounting for 30.32%,23.18% and 16.39% of the total, respectively, while glucosinolate degradation products, heterocyclic, esters and alcohols were not detected. At the end of the 35 d experiment, the total amount of volatile components in fragrant rapeseed oil and refined rapeseed oil increased significantly to 51 729.62 μg/kg and 45 671.79 μg/kg, respectively, and aldehydes became the highest volatile components in both rapeseed oils, accounting for 60.30% and 68.07% of the total, respectively.The glucosinolate degradation products in fragrant rapeseed oil decreased significantly to only 2.64% of the total,while the content of heterocyclic substances was significantly reduced and the contents of ketones, olefins and alkanes significantly increased.The content of ketones, alkanes and olefins in refined rapeseed oil increased, while the content of alcohols increased from the initial non-detect to 1310% of the total. The volatile component principal component analysis revealed that the differences between the two original rapeseed oils were mostly caused by benzoylpropionitrile, 3-methylcrotononitrile, 2-pinene, 5-hexenenitrile and 4-ethenyl-2,6-dimethoxyphenol,which contributed to fragrant rapeseed oil’s unique flavors. In the late stage of accelerated oxidation experiment, the differences between the two rapeseed oils were mainly caused by 1-penten-3-ol, 1-octen-3-ol, (E)-2-pentenal, (E)-2-heptenal, hexanal, nonanal, methylheptenone, (E,E)-3,5-octadien-2-one, leucocalyene and methylcyclohexene, and the first five substances were related to refined rapeseed oil, mostly linoleic acid oxidation products, while the latter five substances were mainly related to fragrant rapeseed oil. The results clarified the comprehensive quality differences of rapeseed oil products produced by different processes and could provide support for the development of precise quality and freshness preservation technology for different rapeseed oil products