Characteristics of extracellular fluorescent substances of aerobic granular sludge in pilot-scale sequencing batch reactor

The aerobic granular sludge was cultivated in a pilot-scale sequencing batch reactor （SBR）, and some of the granules were stored at 8 ℃ for 150 d. Extracellular polymeric substances （EPS） of sludge samples were extracted and analyzed during the granulation and storage process. The results show that the contents of protein and EPS increase along with the granulation process, while polysaccharides remain almost unchanged. The content of protein in EPS is almost two-fold larger than that of polysaccharides in granular sludge cultivated with municipal wastewater. Moreover, some of the granules disintegrate during storage, corresponding to the decrease of protein contents in EPS. Three peaks are identified in three-dimensional excitation emission matrix （EEM） fluorescence spectra of the EPS in the aerobic granules. Two peaks （A and B） are attributed to the protein-like fluorophores, and the third （peak C） is related to visible fulvic-like substances. Peak A gradually disappears during storage, while a new peak related to ultraviolet fulvic acid （peak D） is formed. The formation and the stability of aerobic granules are closely dependent on the quantity and composition of EPS proteins. Peak C has no obvious changes during granulation, while the fulvic-like substances present an increase in fluorescence intensities during storage, accompanied with an increase in structural complexity. The fulvie-like substances are also associated with the disintegration of the aerobic granules.

Characterization of chromophoric dissolved organic matter(CDOM) in the East China Sea in autumn using excitationemission matrix(EEM) fluorescence and parallel factor analysis(PARAFAC)

Samples of chromophoric dissolved organic matter （CDOM） in the East China Sea in autumn （October in 2011） were analyzed by excitation emission matrix （EEM） fluorescence spectroscopy combined with parallel factor analysis （PARAFAC）. Three terrestrial humic-like components （C1, C2 and C3） and one protein-like component （C4） were identified. Based on spatial dis- tributions, as well as relationships with salinity, the following assignments were made. The three humic-like components （CI, C2 and C3） showed conservative mixing behavior and came mainly from riverine input. The protein-like component （C4） was considered a combination of autochthonous production and terrestrial inputs and a biologically labile component. Path analysis of samples from the middle and bottom layers revealed that the causal effects on C1 were -78.46% for salinity, and -21.54% for apparent oxygen utilization （AOU）; those on C2 were -76.43% for salinity, and -23.57% for AOU; those on C3 were -70.49% for salinity, 7.01% for Chl-a, and -22.50% for AOU; those on C4 were -55.54% for salinity, 14.6% for Chl-a, and -29.86% for AOU in middle layer; and those on C4 were -57.37% for salinity, 29.02% for Chl-a, and -13.61% for AOU in bottom layer. Results indicated that CDOM in tile East China Sea was mainly affected by terrestrial inputs, and microbial ac- tivities also played a key role in biogeochemical processes of CDOM. The application of the EEM-PARAFAC model present- ed a unique opportunity to observe compositional changes in CDOM in the East China Sea. In addition, the humification index （HIX） suggested that CDOM from the East China Sea was less stable and stayed shorter in the environment.

Assessing the dynamics of chromophoric dissolved organic matter(CDOM) in the Yellow Sea and the East China Sea in autumn by EEMs-PARAFAC

In this study we have successfully characterized the fluorescent components of chromophoric dissolved organic matter(CDOM) in the Yellow Sea and the East China Sea in autumn using excitation-emission matrix fluorescence spectroscopy(EEMs) combined with parallel factor analysis(PARAFAC).PARAFAC aids the characterization of fluorescence CDOM by decomposing the fluorescence matrices into individual components.Four humic-like components(C1,C2,C3,and C4),one marine biological production component(C6),and two protein-like components(C5 and C7) were identified by PARAFAC.We researched the distributional patterns of fluorescence intensity,regression analyses between salinity,chlorophyll a concentration and fluorescence intensities of individual fluorophore,and regression analysis between salinity and fluorescence intensities percent of individual fluorophore.The results revealed that C2 and C4 showed conservative mixing behavior,while C1 and C3 possessed conservative mixing behavior in high salinity region and additional behavior in low and middle salinity region,which were considered to be derived from riverine and degradation of organic matter from resuspended and/or sinking particles and show non-conservative mixing behavior.In addition to riverine sources,the tryptophan-like C5 may receive widespread addition(likely from photo-degradation or biodegradation),while the most likely sources for the one marine humic-like C6 and tyrosine-like C7 were biological activity and microbial processing of plankton-derived CDOM,which were suggested to be of autochthonous origin and biologically labile.The application of EEM-PARAFAC modeling presents a unique opportunity to observe compositional changes,different mixing behavior and temporal variability in CDOM in the Yellow Sea and the East China Sea.

Evidence on the causes of the rising levels of COD_(Mn) along the middle route of the South-to-North Diversion Project in China:The role of algal dissolved organic matter

As the biggest inter-basin water transfer scheme in the world,the South-to-North Water Diversion Project(SNWD) was designed to alleviate the water crisis in North China.The main channel of the middle route of the SNWD is of great concern in terms of the drinking water quality.In this study,we tested the hypothesis that the dissolved organic matter(DOM) derived from the planktonic algae causes the rising levels of COD_(Mn) along the middle route by monitoring data on water quality(2015-2019,monthly resolution).The results showed that algal density in the main channel increased along the channel and was significantly correlated with COD_(Mn)(p <0.01).Five fluorescent components of DOM,including tyrosine-like(14.85%),tryptophan-like(22.48%),microbial byproduct-like(26.34%),fulvic acid-like(11.41%),and humic acid-like(24.92%) components,were detected.The level of tyrosine-like components increased along the channel and was significantly correlated with algal density(p<0.01),indicating that algae significantly changed the level of DOM in the channel.Algal decomposition and metabolism were found to be the main mechanisms that drive the changes in COD_(Mn).Therefore,controlling algal density would be an important measure to prevent further increase in CODMn and for the guarantee of excellent water quality.

Studies on the Interaction between Rutin and DNA in the Absence and Presence of β-Cyclodextrin by Electro- chemical and Spectroscopic Methods

The interactions between rutin or the inclusion complex of rutin-b-cyclodextrin and DNA were investigated by means of cyclic voltammetry, UV-vis absorption spectroscopy and fluorescence emission spectroscopy. The appar-ent binding constant of rutin with DNA is found to be 2.9×104 L/mol. The results showed that the ben-zopyranic-4-one plane of rutin mainly intercalated into DNA in the absence of b-cyclodextrin, while the catecholic portion of rutin was located in the double helix of DNA in the presence of b-cyclodextrin.