Taihu Lake is one of the five biggest lakes in China. Surface water samples from 26 sampling sites of Taihu Lake were collected. Furthermore wet chemical analysis （CODCr and BOD5） and measurement of three dimensiona...Taihu Lake is one of the five biggest lakes in China. Surface water samples from 26 sampling sites of Taihu Lake were collected. Furthermore wet chemical analysis （CODCr and BOD5） and measurement of three dimensional excitation-emission matrix （3DEEM） spectra in the laboratory have been conducted. Using parallel factor analysis （PARAFAC） model, three components of colored dissolved organic matter （CDOM） have been identified successfully, based on the analysis of 3DEEM data. The characteristics of the three components also have been described by comparing them to some components of CDOM, identified in earlier researches. Meanwhile, spatial variations of concentration for the three components in Taihu Lake have been analyzed, and the result indicates that the concentration of component 1 depends more on the situation of wastewater pollution and can be used as the indicator of wastewater pollution. The relationship between the concentrations of the three components and results of the wet chemical analysis show that none of the three components can be used as indicators of gross organic matter in water. However, the concentrations of all the three components have obvious linear relationships with the BOD5 value, especially for component 1 （r = 0.72878）. Finally, the potential applications of the composition analysis based on 3DEEM and PARAFAC model in water quality monitoring have been illuminated.展开更多
Humic acid （HA） is known to be a complex organic compound with varying structural and functional characteristics. In this study, three-dimensional excitation emission matrix fluorescence spectroscopy （3DEEM）, ultr...Humic acid （HA） is known to be a complex organic compound with varying structural and functional characteristics. In this study, three-dimensional excitation emission matrix fluorescence spectroscopy （3DEEM）, ultraviolet-visible （UV-Vis） and Fourier-transform infrared （FT-IR） were applied to study the fluorescence characteristics and structure of two typical soil HAs in China. The effects of concentration of HA, pH and ionic strength on the fluorescence behaviors were investigated. The results indicate that ionic strength over the range from 0 to 0.05mol L^-1 NaNO3 did not affect the 3DEEM of HA. The concentration of HA and pH of the test solution had obvious effects on the 3DEEM. When the concentration of soil HA was lower than 10mg L^-1, HA has only one obvious fluorescence peak. However, there were several fluorescence peaks for HA in high concentration （≥50mg L^-1）, and its Ex/Em maximum wavelength shifted towards longer wavelength with increasing the concentration of HA. The fluorescence intensity of HA enhanced with the increase of pH, and achieved maximum at pH 10. The effect of pH on the fluorescence intensity of black soil HA （BHA） was the severest and a polycondensation of BHA existed with the change of pH. At the same condition, the fluorescence intensity of red soil HA （RHA） was stronger than that of BHA. At the excitation wavelength of 340nm, the maximum emission peak positions of RHA and BHA were 474 and 504nm at pH 6.0, and their fluorescence quantum yields （QY） were 2.1-2.5% and 1.5-1.9%, respectively. Based on the maximum emission peak positions and fluorescence quantum yield, RHA and BHA can be distinguished.展开更多
A membrane bioreactor(MBR)with ordinary aeration(reactor R1)and a MBR with microporous aeration(reactor R2)are conducted in parallel to investigate the characteristics of oily sludge and its effect on membrane fouling...A membrane bioreactor(MBR)with ordinary aeration(reactor R1)and a MBR with microporous aeration(reactor R2)are conducted in parallel to investigate the characteristics of oily sludge and its effect on membrane fouling.The results indicate that the order of membrane fouling rate from high to low is:reactor R1 dissolved oxygen(DO)(1 mg/L)>reactor R2 DO(1 mg/L)>reactor R1 DO(4 mg/L)>reactor R2 DO(4 mg/L).Membrane fouling rate is not related to oily sludge concentration but to oily sludge sedimentation performance and the small particle oily sludge is the key factor to affect the membrane fouling.The soluble microbial products(SMP)are examined by three-dimensional excitation-emission matrix(3DEEM)fluorescence spectra.3DEEM spectra demonstrate that the main organic substances of the SMP in two reactors are tyrosine aromatic protein,fulvic acid-like substances and soluble microbial products under DO are1 mg/L and 4 mg/L,respectively.The proportion sum of fulvic acid-like substances and soluble microbial products is the key factor affecting membrane fouling,and membrane fouling accelerates as the ratio increases.展开更多
Preliminary characterization of bound extracellular polymeric substances（bEPS） of cyanobacteria is crucial to obtain a better understanding of the formation mechanism of cyanobacterial bloom. However,the characteriz...Preliminary characterization of bound extracellular polymeric substances（bEPS） of cyanobacteria is crucial to obtain a better understanding of the formation mechanism of cyanobacterial bloom. However,the characterization of bEPS can be affected by extraction methods. Five sets（including the control） of bEPS from Microcystis extracted by different methods were characterized using three-dimensional excitation and emission matrix（3DEEM） fluorescence spectroscopy combined chemical spectrophotometry; and the characterization results of bEPS samples were further compared. The agents used for extraction were NaOH,pure water and phosphate buffered saline（PBS） containing cationic exchange resins,and hot water. Extraction methods affected the fluorescence signals and intensities in the bEPS. Five fluorescence peaks were observed in the excitation and emission matrix fluorescence spectra of bEPS samples. Two peaks（peaks T1 and T2） present in all extractions were identified as protein-like fluorophores,two（peaks A and C） as humic-like fluorophores,and one（peak E） as a fulvic-like substance.Among these substances,the humic-like and fulvic-like fluorescences were only seen in the bEPS extracted with hot water. Also,NaOH solution extraction could result in strong fluorescence intensities compared to the other extraction methods. It was suggested that NaOH at pH 10.0 was the most appropriate method to extract bEPS from Microcystis. In addition,dialysis could affect the yields and characteristics of extracted bEPS during the determination process. These results will help us to explore the issues of cyanobacterial blooms.展开更多
基金Project supported by the Knowledge Innovation Project of ChineseAcademy of Sciences (No. KGCX2-SW-111).
文摘Taihu Lake is one of the five biggest lakes in China. Surface water samples from 26 sampling sites of Taihu Lake were collected. Furthermore wet chemical analysis （CODCr and BOD5） and measurement of three dimensional excitation-emission matrix （3DEEM） spectra in the laboratory have been conducted. Using parallel factor analysis （PARAFAC） model, three components of colored dissolved organic matter （CDOM） have been identified successfully, based on the analysis of 3DEEM data. The characteristics of the three components also have been described by comparing them to some components of CDOM, identified in earlier researches. Meanwhile, spatial variations of concentration for the three components in Taihu Lake have been analyzed, and the result indicates that the concentration of component 1 depends more on the situation of wastewater pollution and can be used as the indicator of wastewater pollution. The relationship between the concentrations of the three components and results of the wet chemical analysis show that none of the three components can be used as indicators of gross organic matter in water. However, the concentrations of all the three components have obvious linear relationships with the BOD5 value, especially for component 1 （r = 0.72878）. Finally, the potential applications of the composition analysis based on 3DEEM and PARAFAC model in water quality monitoring have been illuminated.
基金Acknowledgements： This work is supported by the Project of the Educational Administration Foundation of Shanghai Municipal Government （No. 05Ja05054 and No. 05DZ01）, Shanghai Leading Academic Discipline Project （No. T0402） and Hunan Provincial Natural Science Foundation of China.
文摘Humic acid （HA） is known to be a complex organic compound with varying structural and functional characteristics. In this study, three-dimensional excitation emission matrix fluorescence spectroscopy （3DEEM）, ultraviolet-visible （UV-Vis） and Fourier-transform infrared （FT-IR） were applied to study the fluorescence characteristics and structure of two typical soil HAs in China. The effects of concentration of HA, pH and ionic strength on the fluorescence behaviors were investigated. The results indicate that ionic strength over the range from 0 to 0.05mol L^-1 NaNO3 did not affect the 3DEEM of HA. The concentration of HA and pH of the test solution had obvious effects on the 3DEEM. When the concentration of soil HA was lower than 10mg L^-1, HA has only one obvious fluorescence peak. However, there were several fluorescence peaks for HA in high concentration （≥50mg L^-1）, and its Ex/Em maximum wavelength shifted towards longer wavelength with increasing the concentration of HA. The fluorescence intensity of HA enhanced with the increase of pH, and achieved maximum at pH 10. The effect of pH on the fluorescence intensity of black soil HA （BHA） was the severest and a polycondensation of BHA existed with the change of pH. At the same condition, the fluorescence intensity of red soil HA （RHA） was stronger than that of BHA. At the excitation wavelength of 340nm, the maximum emission peak positions of RHA and BHA were 474 and 504nm at pH 6.0, and their fluorescence quantum yields （QY） were 2.1-2.5% and 1.5-1.9%, respectively. Based on the maximum emission peak positions and fluorescence quantum yield, RHA and BHA can be distinguished.
基金National Natural Science Foundation of China(No.21173026)Key Program of the Natural Science Foundation of Hubei Province(No.2013CFA107).
文摘A membrane bioreactor(MBR)with ordinary aeration(reactor R1)and a MBR with microporous aeration(reactor R2)are conducted in parallel to investigate the characteristics of oily sludge and its effect on membrane fouling.The results indicate that the order of membrane fouling rate from high to low is:reactor R1 dissolved oxygen(DO)(1 mg/L)>reactor R2 DO(1 mg/L)>reactor R1 DO(4 mg/L)>reactor R2 DO(4 mg/L).Membrane fouling rate is not related to oily sludge concentration but to oily sludge sedimentation performance and the small particle oily sludge is the key factor to affect the membrane fouling.The soluble microbial products(SMP)are examined by three-dimensional excitation-emission matrix(3DEEM)fluorescence spectra.3DEEM spectra demonstrate that the main organic substances of the SMP in two reactors are tyrosine aromatic protein,fulvic acid-like substances and soluble microbial products under DO are1 mg/L and 4 mg/L,respectively.The proportion sum of fulvic acid-like substances and soluble microbial products is the key factor affecting membrane fouling,and membrane fouling accelerates as the ratio increases.
基金supported by the Natural Scientific Foundation of China (Nos.40825004,40971252,41301544)the Water Pollution Control and Management Project (No.2012ZX07101-010)the Shandong Province Natural Science Foundation of China (No.ZR2012DQ003)
文摘Preliminary characterization of bound extracellular polymeric substances（bEPS） of cyanobacteria is crucial to obtain a better understanding of the formation mechanism of cyanobacterial bloom. However,the characterization of bEPS can be affected by extraction methods. Five sets（including the control） of bEPS from Microcystis extracted by different methods were characterized using three-dimensional excitation and emission matrix（3DEEM） fluorescence spectroscopy combined chemical spectrophotometry; and the characterization results of bEPS samples were further compared. The agents used for extraction were NaOH,pure water and phosphate buffered saline（PBS） containing cationic exchange resins,and hot water. Extraction methods affected the fluorescence signals and intensities in the bEPS. Five fluorescence peaks were observed in the excitation and emission matrix fluorescence spectra of bEPS samples. Two peaks（peaks T1 and T2） present in all extractions were identified as protein-like fluorophores,two（peaks A and C） as humic-like fluorophores,and one（peak E） as a fulvic-like substance.Among these substances,the humic-like and fulvic-like fluorescences were only seen in the bEPS extracted with hot water. Also,NaOH solution extraction could result in strong fluorescence intensities compared to the other extraction methods. It was suggested that NaOH at pH 10.0 was the most appropriate method to extract bEPS from Microcystis. In addition,dialysis could affect the yields and characteristics of extracted bEPS during the determination process. These results will help us to explore the issues of cyanobacterial blooms.
