High-molecular weight sulfur-containing aromatics refractory to weathering as determined by Fourier transform ion cyclotron resonance mass spectrometry

Biomarkers and low-molecular weight polyaromatic compounds have been extensively studied for their fate in the environment. They are used for oil spill source identification and monitoring of weathering and degradation processes. However, in some cases, the absence or presence of very low concentration of such components restricts the access of information to spill source. Here we followed the resistance of high-molecular weight sulfur-containing aromatics to the simulated weathering condition of North Sea crude oil by ultra high-resolution Fourier transform ion cyclotron resonance mass spectrometry. The sulfur aromatics in North Sea crude having double bond equivalents (DBE) from 6 to 14 with a mass range 188-674 Da were less influenced even after 6 months artificial weathering. Moreover, the ratio of dibenzothiophenes (DBE 9)/naphthenodibenzothiophenes (DBE 10) was 1.30 and 1.36 in crude oil and 6 months weathered sample, respectively reflecting its weathering stability. It also showed some differences within other oils. Hence, this ratio can be used as a marker of the studied crude and accordingly may be applied for spilled oil source identification in such instances where the light components have already been lost due to environmental influences.     

Detailed characterization of polar compounds of residual oil in contaminated soil revealed by Fourier transform ion cyclotron resonance mass spectrometry

Effects of remediation technologies on polar compounds of crude oil in contaminated soils have not been well understood when compared to hydrocarbons. In this study, ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to characterize the changes in NSO polar compounds of crude oil and residual oil after long-term natural attenuation, biostimulation and subsequent ozonation following biostimulation of contaminated soils. N₁ and O₁ species, which were abundant in the crude oil, were selectively biodegraded, and species with higher double bond equivalent values and smaller carbon numbers appeared to be more resistant to microbial alteration. O₂-O₆ species were enriched by biodegradation and contained a large number of compounds with a high degree of unsaturation. Ozone could react with a variety of polar compounds in residual oil after biodegradation and showed high reactivity with polar species containing aromatic or multi-aliphatic rings, including the residual N₁ and O₁ species, naphthenic acids and unsaturated O₃-O₆ compounds. Fatty acids and O₃-O₈ species dominated by saturated alkyl compounds were resistant to ozonation or the primarily incomplete ozonation products. Principal component analysis of identified peaks in the FT-ICR MS spectra provided a comprehensive overview of the complex samples at the molecular level and the results were consistent with the detailed analysis. Taken together, these results showed the high complexity of polar compounds in residual oils after biodegradation or ozonation in contaminated soil and would contribute to a better understanding of bioremediation and ozonation processes.     

海啸波近岸共振响应的数值模拟及分析

应用有限差分方法求解非线性浅水长波方程,建立了海啸波产生和传播的二维数值模型;对太平洋地震引起的夏威夷群岛海啸波进行模拟,并将模拟结果和测站实测值进行比较,验证了模型的正确性。利用快速傅里叶变换对数值模拟结果进行谱分析,得到整个计算区域的能量谱分布,并给出了发生能量聚集的位置及相应的谱峰周期。讨论了海啸波传播到近岸时可能产生的共振响应现象,发现海啸波和近岸的共振响应不仅与近岸复杂地形有关,还与海啸波传播到近岸时的波浪入射方向有关。     

铝塑包装废物的热解特性研究

利用热重-差热-傅立叶变换红外光谱联用仪对铝塑包装废物热解特性进行分析,并对物料性质、纸质存在对热解过程的影响进行研究. 结果表明:铝塑包装废物热解主要发生于438～500 ℃,最大失重速率出现在470～475 ℃;产物中主要是—C—C—以及少量的—CC—与芳香烃;反应温度由50 ℃升至850 ℃,铝塑包装废物依次经历聚乙烯熔融软化、热解,铝熔融,铝与焦状物反应等过程;铝塑包装废物中含纸质时,在312.4～363.2 ℃增加了一个失重过程,同时高温时的热解反应更为复杂.      

Flocculating characteristic of activated sludge flocs: Interaction between Al3+ and extracellular polymeric substances

Aluminum flocculant can enhance the flocculating performance of activated sludge.However,the binding mechanism of aluminum ion(Al 3+) and extracellular polymeric substances(EPS) in activated sludge is unclear due to the complexity of EPS.In this work,threedimensional excitation emission matrix fluorescence spectroscopy(3DEEM),fluorescence quenching titration and Fourier transform infrared spectroscopy(FT-IR) were used to explore the binding behavior and mechanism between Al 3+ and EPS.The results showed that two fluorescence peaks of tyrosineand tryptophan-like substances were identified in the loosely bound-extracellular polymeric substances(LB-EPS),and three peaks of tyrosine-,tryptophanand humic-like substances were identified in the tightly boundextracellular polymeric substances(TB-EPS).It was found that these fluorescence peaks could be quenched with Al 3+ at the dosage of 3.0 mg/L,which demonstrated that strong interactions took place between the EPS and Al 3+.The conditional stability constants for Al 3+ and EPS were determined by the Stern-Volmer equation.As to the binding mechanism,the-OH,N-H,C=O,C-N groups and the sulfurand phosphorus-containing groups showed complexation action,although the groups in the LB-EPS and TB-EPS showed different behavior.The TB-EPS have stronger binding ability to Al 3+ than the LB-EPS,and TB-EPS play an important role in the interaction with Al 3+.     

黄土高原次生林演替过程土壤有机碳库及其化学组成响应特征

为探明黄土高原次生林演替过程中土壤有机碳库及其化学组成演化特征,选取陕北黄土高原黄龙山林区次生林演替初级阶段(山杨林)、过渡阶段(山杨、辽东栎混交林)和顶级阶段(辽东栎林)样地为研究对象,分析不同土层深度(0～10、 10～20、 20～30、 30～50和50～100 cm)土壤有机碳含量、储量和化学组成变化特征.结果表明：(1)土壤有机碳含量和储量随次生林演替过程显著增加(P<0.05),土壤有机碳含量随土层深度增加显著降低,土壤有机碳储量从初级阶段的64.8Mg·hm^-2增加至顶级阶段的129.2Mg·hm^-2,增加了99%.(2)次生林演替过程中,表层(0～30 cm)土壤有机碳中结构简单、相对易分解的脂肪族碳组分相对含量减少,结构复杂、相对难分解的芳香族碳组分相对含量增加,表明表层土壤有机碳化学组成稳定性随次生林演替过程显著提高,而深层(30～100cm)土壤有机碳化学组成稳定性表现为先增加后降低,即过渡阶段>顶级阶段>初级阶段.(3)次生林演替过程中,初级阶段和过渡阶段土壤有机碳化学组成稳定性随土层深度增加显著增...     

污水再生过程中消毒副产物前体物转化规律

采用大孔吸附树脂将污水中的消毒副产物(DBP)前体物分离为亲水性物质(HPI)、强疏水性物质(HPO)和弱疏水性物质(TPI)这3个组分,通过三维荧光光谱、傅里叶红外光谱和核磁共振对再生水处理各沿程前体物进行表征,并测定各沿程出水的消毒副产物生成势(DBPFP).结果表明,生活污水中DBPs前体物主要组分为腐殖质和脂肪烃,以HPI为主.一级处理(沉淀)基于HPO与水互斥的物理性能对疏水性腐殖质有较好的去除效果,腐殖质的去除会导致含碳消毒副产物生成势(CDBPFP)的降低.此外由于DON/DOC的增加,含氮消毒副产物生成势(N-DBPFP)有所增加.二级处理(生物处理)对腐殖质和脂类均有较好的去除效果,但会产生大量疏水性的溶解性微生物产物(SMP),因此生物处理后DBPs前体物主要表现为疏水性.SMP的累积会导致C-DBPFP和N-DBPFP的大幅增加.深度处理(滤布滤池)能截留部分腐殖质和疏水性的SMP,因此前体物HPO占比减少,HPI占比增加.深度处理可以通过对SMP的去除来降低C-DBPFP和N-DBPFP.     

用移动富氏谱分析近场地震波的脉冲成分

采用移动富氏分析的方法，将不同时间同一频率成分的富氏谱连成曲线，分析地震波随时间变化时频率成分的变化状态。 采用移动富氏谱分析方法分析了两条典型近场地震波的脉冲成分及动力学和地震工程学意义。     

基于油冷管失效的振动试验方法的研究

本文研究了普通轿车变速箱油冷器连接管路的典型失效模式。通过采集实车振动谱,采用快速傅立叶变换成PSD图谱并分析频域特点,选择特征点能量修正试验台架规范的输入,从而复现失效模式达到充分验证的目的。     

武汉城市污水中微塑料的分离、鉴定及其微观特征分析

为研究武汉城市污水中微塑料的分布特点及其表面形貌特征,采用以连续浮选分离装置为基础进行改进设计的微塑料提取装置对污水中微塑料进行分离,通过用65%硝酸和30%过氧化氢混合液（体积比为1:3）对污水样品进行消解,并采用筛网（300、600、1 000目）（100目=0.147 mm）和滤膜（1 μm玻璃纤维滤膜和20 nm氧化铝滤膜）分离技术建立起对水体微塑料和纳米塑料的分离富集方法.通过傅里叶变换红外光谱（FTIR）、扫描电镜-X射能谱分析联用（SEM-EDS）等方法对所提取微塑料颗粒的组成成分、赋存特征、表面形貌特征进行分析.结果表明:①提取装置的平均回收率在92%以上.②污水中微塑料类型主要为碎片类、泡沫类、薄膜类和纤维类.③FTIR结果证实,该方法所提取的微塑料颗粒中有聚乙烯、聚丙烯等成分,且发现了羰基、聚酯类物质存在,说明提取到的微塑料中可能有可降解塑料颗粒.④SEM-EDS结果显示,各类微塑料表面粗糙、撕裂程度不同,存在不同程度的风化痕迹,并在其表面发现Si、Cu、O、Al、Na、Ca、Ba等元素的富集.研究显示:改进的微塑料分离方法能够实现对污水中微塑料的高效提取;同时,明确了武汉城市污水微塑料的表面形貌特征及赋存特征,为未来武汉城市污水中微塑料污染的针对性治理提供理论依据.