Fluorescence excitation–emission matrix spectra coupled with parallel factor and regional integration analysis to characterize organic matter humification

The present several humification indexes cannot provide the whole fluorescence information on organic matter composition and the evaluation results from them are inconsistent sometimes. In this study, fluorescence excitation–emission matrix spectra coupled with parallel factor analysis and fluorescence regional integration analysis were utilized to investigate organic matter humification, and the projection pursuit cluster (PPC) model was applied to form a suitable index for overcoming the difficulties in multi-index evaluation. The result showed that the ratio between the volume of humic- and fulvic-like fluorescence region and the volume of protein-like fluorescence region not only revealed the heterogeneity of organic matter, but also provided more accurate information on organic matter humification. In addition, the results showed that the PPC model could be used to characterize integrally the humification, and the projected characteristic value calculated from the PPC model could be used as the integrated humification evaluation index.     

Insights on the solubilization products after combined alkaline and ultrasonic pre-treatment of sewage sludge

This work provides insights on the solubilization products after a simultaneous combination of alkaline and ultrasonic(ALK + ULS) pre-treatment of sewage sludge.Soluble chemical oxygen demand(SCOD) increased from 1200 to 11,000 mg/L after such treatment. Organics with molecular weight around 5.6 k Da were solubilized because of the synergistic effect of ultrasound and alkali. Organics with molecular weight larger than300 k Da increased from 7.8% to 60%, 16% and 42.3% after ULS, ALK and ALK + ULS treatment, respectively. Excitation emission matrix fluorescence spectroscopy analysis identified soluble microbial product-like and humic acid-like matters as the main solubilization products. Sludge anaerobic biodegradability was significantly enhanced with the simultaneous application of ALK + ULS pre-treatment. ALK + ULS pre-treatment resulted in 37.8% biodegradability increase compared to the untreated sludge. This value was higher compared to the biodegradability increase induced by individual ALK pre-treatment(5.7%) or individual ULS pre-treatment(20.7%) under the same conditions applied.     

Different analysis techniques for fluorescence excitation-emission matrix spectroscopy to assess compost maturity

Assessment of compost maturity is essential for achieving high quality compost. In this study, fluorescence excitation-emission matrix spectroscopy combined with different analysis techniques was applied to improve the sensitivity of compost maturity assessment. Results showed that composts in two parallel piles could be believed mature after 37 d when combined with the evolution of temperature, chemical and biological indices in the two piles. Pearson correlation between the common maturity indices and fluorescence analysis parameters demonstrated that fluorescence regional integration (FRI) had a higher correlation coefficient than that of fluorescence intensities and the ratios of peaks, suggesting that FRI technique is more suitable to characterize the maturity of compost than the other two analysis techniques, i.e., peak intensity and peak ratio. Furthermore, the fluorescence spectroscopy combined with FRI analysis could be used as a valuable industrial and research tool for assessing compost maturity.     

Copper and cadmium effects on growth and extracellular exudation of the marine toxic dinoflagellate Alexandrium catenella: 3D-fluorescence spectroscopy approach

In this study, metal contamination experiments were conducted to investigate the effects of copper and cadmium on the growth of the marine toxic dinoflagellate Alexandrium catenella and on the production of dissolved organic matter (Dissolved Organic Carbon: DOC; Fluorescent Dissolved Organic Matter: FDOM). This species was exposed to increasing concentrations of Cu²⁺ (9.93 × 10⁻¹⁰–1.00 × 10⁻⁷ M) or Cd²⁺ (1.30 × 10⁻⁸–4.38 × 10⁻⁷ M), to simulate polluted environments. The drastic effects were observed at pCu²⁺ = 7.96 (Cu²⁺: 1.08 × 10⁻⁸ M) and pCd²⁺ = 7.28 (Cd²⁺: 5.19 × 10⁻⁸ M), where cyst formation occurred. Lower levels of Cu²⁺ (pCu²⁺ > 9.00) and Cd²⁺ (pCd²⁺ > 7.28) had no effect on growth. However, when levels of Cu²⁺ and Cd²⁺ were beyond 10⁻⁷ M, the growth was totally inhibited. The DOC released per cell (DOC/Cell) was different depending on the exposure time and the metal contamination, with higher DOC/Cell values in response to Cu²⁺ and Cd²⁺, comparatively to the control. Samples were also analyzed by 3D-fluorescence spectroscopy, using the Parallel Factor Analysis (PARAFAC) algorithm to characterize the FDOM. The PARAFAC analytical treatment revealed four components (C1, C2, C3 and C4) that could be associated with two contributions: one, related to the biological activity; the other, linked to the decomposition of organic matter. The C1 component combined a tryptophan peak and a characteristic humic substances response, and the C2 component was considered as a tryptophan protein fluorophore. The C3 and C4 components were associated to marine organic matter production.     

交替冻融对东北典型土壤腐殖质的影响

以受季节性冻融过程影响显著的东北地区的黑土、暗棕壤和水稻土为例,采用实验室模拟的方法,研究交替冻融循环过程（分别在-20℃和20℃下处理）对土壤腐殖质的影响。研究表明：交替冻融后,黑土和暗棕壤松结态腐殖质质量分数分别增加了39%和28%,HA/FA分别上升了45%和35%;水稻土松结态腐殖质质量分数和HA/FA分别下降了18%和31%。三维荧光结果进一步验证,黑土、暗棕壤在交替冻融中土壤芳香化程度增高,HA/FA上升,而水稻土则相反。黑土和暗棕壤松结态腐殖质和HA/FA升高,主要是微生物分解作用和土壤大团聚体破坏等原因造成,水稻土松结态腐殖质和HA/FA降低,主要是水稻土的缺氧环境造成。     

神农架大九湖泥炭地孔隙水溶解有机碳特征及其影响因素

溶解性有机碳（Dissolved Organic Carbon, DOC）是泥炭地碳循环的重要组成部分。以往的研究大多集中在北方泥炭地,而对亚热带季风区泥炭地DOC动力学的认识十分有限。利用紫外可见光光谱（UV-Vis）和三维荧光光谱结合平行因子分析法（EEM-PARAFAC）研究了神农架大九湖泥炭地孔隙水的DOC浓度与化学组成及其影响因素。EEM-PARAFAC的结果表明：大九湖泥炭地孔隙水DOC主要包含3种类腐殖质组分。紫外可见光和荧光指标表明,泥炭孔隙水DOC表观分子较小,而芳香度较高。深度剖面数据表明,泥炭孔隙水DOC浓度随深度降低,0~10 cm深度浓度最高为24.16 mg/L,150~160 cm深度浓度最低为9.72 mg/L,并且深层DOC以微生物代谢产生的新鲜有机物为主,具有较低的腐殖化度。此外,氧化还原电位（ORP）与DOC浓度及化学性质关系密切。以上结果表明,在亚热带泥炭地中,微生物来源或受微生物改造的有机物是泥炭孔隙水DOC的重要组成部分;垂向输送或选择性保存是影响该亚热带亚高山泥炭地DOC动力学的重要因素。     

东江流域主要支流溶解性有机质污染特征初探

溶解性有机质（DOM）是天然水体的重要组成部分,其组分构成及含量能够反映河流污染特征。研究利用三维荧光光谱技术对2014年3—4月东江流域8条一级支流下游DOM的荧光组分进行分析。通过寻峰法和平行因子分析（PARAFAC）识别出两种类腐殖质组分（Peak A和Peak B）和两种类蛋白质组分（Peak C和Peak D）;并结合常规水质指标,探索各支流的主要污染源,为东江流域水质管理提供科学依据。结果表明：1)东江流域淡水河和石马河两种类蛋白质显著高于其他支流,两种类腐殖质出现缺失现象。2）8条支流样点的DOM中,Peak C、Peak D与各常规水质参数相关性显著,说明东江流域DOM能够较好地反映水质情况。3）东江流域中上游支流自然生境良好,受到人为活动影响强度低。中游支流受农业及工业的双重污染,类腐殖质及类蛋白质的含量较上游河流有显著增加。下游支流受人为活动影响剧烈,河岸带自然生境破坏严重,河岸固化,使得类腐殖质缺失;工业废水及生活污水大量排放,类蛋白质含量显著上升。4）与国内外其他河流相比,东江流域各支流、珠江干流广州河段及河口、辽河流域太子河均呈现以类蛋白质为主要组分,与长江流域以及国外河流存在显著差异,说明东江流域人类产生的有机污染严重,亟须治理。     

三维荧光光谱评价污水处理厂COD去除效率

采用三维荧光光谱与平行因子法和荧光区域积分法相结合,对城市生活污水处理厂各反应流程的水样进行了快速表征和分析。结果表明,污水中主要荧光物质为类蛋白质和类胡敏酸物质,其中类蛋白质的平行因子得分和荧光区域积分值均与水样化学需氧量(COD)具有较好的相关性。进一步分析表明,类蛋白质与类胡敏酸的区域积分值之比可以反映污水处理厂溶解性COD的去除效果。该研究提供了一种快速且不需外加试剂的评价污水厂溶解性COD去除效率的方法。     

丙烯酸装置废水特征有机污染物及其荧光特性

采用吹扫捕集-气相色谱/质谱法(P&T-GC/MS),液液萃取-气相色谱/质谱法(LLE-GC/MS)等方法对丙烯酸装置废水中主要特征有机污染物进行了定性、定量分析,研究了废水和各主要特征污染物的三维荧光特性。结果表明,废水中共检出有机酸、苯系物、酯、醛、醇等24种有机污染物,其中含量较大的有乙酸55.13%,丙烯酸23%,甲醛21.81%,甲苯0.03%,4-羟基-2-丁酮0.02%,丙烯酸甲酯0.01%,正丁醇0.01%。丙烯酸废水中含有3个荧光峰,区域IV内的荧光峰(λex/em=290/355 nm)主要由废水中高浓度的丙烯酸产生,区域V内的2个荧光峰(λex/em=390/495 nm,λex/em=295/480 nm)由水中的腐殖质产生。丙烯酸抑制了甲苯、甲醛、乙酸等3种荧光物质对丙烯酸废水荧光强度的贡献。4种荧光物质的荧光基团影响力大小:碳碳双键+羧基> 苯环> 羰基> 羧基。     

不同垃圾渗滤液组合处理工艺中DOM的变化特征

为了快速表征垃圾渗滤液处理过程中有机物的特性变化,分别采用紫外光谱和三维荧光光谱对2种垃圾渗滤液处理工艺不同单元溶解性有机物(DOM)的变化进行了系统分析。结果表明,二级RO和厌氧+好氧+MBR+NF+RO工艺对渗滤液COD和NH3-N的去除率分别为98.7%、99.0%和98.8%、98.6%。随着处理过程的进行,2个处理工艺中DOM的SUVA254、E253/E203分别由0.74、0.33和0.46、0.12下降至0.015、0.014和0.010、0.012,有机物的芳香性和不饱和性下降,脂肪链芳香烃化合物开始增加。不同处理阶段渗透液DOM三维荧光光谱表明,随着处理过程的进行,类富里酸和类蛋白物质的含量逐渐下降,芳构化程度开始降低。其中二级RO系统对渗滤液中类富里酸物质的去除效果较好,而厌氧-好氧-MBR-NF-RO工艺中,类酪氨酸物质主要通过微生物降解去除,NF和RO膜对类富里酸和类腐殖酸物质的截留效果较好。