The biosorption characteristics of Cs（I） ions from aqueous solution using exopolymers （PFC02） produced from Pseudomonas fluorescens C-2 were investigated as a function of pH, biosorbent dosage, contact time and in...The biosorption characteristics of Cs（I） ions from aqueous solution using exopolymers （PFC02） produced from Pseudomonas fluorescens C-2 were investigated as a function of pH, biosorbent dosage, contact time and initial concentration. pH played a major role in the adsorption process, and the optimum pH for the removal of Cs（I） was 8.0. Langmuir, Freundlich and Dubinin-Radushkevich （D-R） models were applied to describe the biosorption isotherm of the Cs（I） ions by PFC02. The Lagergren first-order, pseudo second-order kinetic and intraparticle diffusion models were used to test the kinetic data. Langmuir model and D-R model fitted the equilibrium data better than the Freundlich isotherm. The monolayer adsorption capacities of PFC02 as obtained from Langmuir isotherm at 25°C was found to be 32.63 mg/g. From the D-R isotherm model, the mean free energy was calculated as 26.73 kJ/mol, indicating that the biosorption of cesium was chemisorption. The biosorption process was rapid, and the kinetic rates were best fitted to the pseudo second-order model, which indicated the biosorption process operated through chemisorption mechanism. FT-IR analysis of PFC02 showed the possible functional groups responsible for cesium adsorption were hydroxyl, carboxyl, carbonyl and sulphonate groups. SEM analysis showed the porous structure of the material while EDX analysis confirmed the adsorption of Cs（I） on PFC02. Cesium adsorbed onto the PFC02 could be desorbed efficiently using 1 mol/L HNO 3 , and the enrichment factor was 50.0. Furthermore, PFC02 could be reused five times with only about 8.25% regeneration loss. The developed method was successfully utilized for the removal of Cs（I） ions from aqueous solution.展开更多
Three sequencing batch reactors supplied with different carbon sources were investigated. The system supplied with glucose gained the best enhanced biological phosphorus removal although all of the three reactors were...Three sequencing batch reactors supplied with different carbon sources were investigated. The system supplied with glucose gained the best enhanced biological phosphorus removal although all of the three reactors were seeded from the same sludge. With the measurement of poly-β-hydroxyalkanoate （PHA） concentration, phosphorus content in sludge and extracellular exopolymers （EPS） with scanning electron microscopy （SEM） combined with energy dispersive spectrometry （EDS）, it was found that the biosorption effect of EPS played an important role in phosphorus removal and that the amount of PHA at the end of anaerobic phase was not the only key factor to determine the following phosphorus removal efficiency.展开更多
Phosphorus removal performance in an aerobic/aerobic sequencing batch reactor (SBR) supplied with glucose as carbon source was investigated. It was found that there was no phosphate release concomitant with the storin...Phosphorus removal performance in an aerobic/aerobic sequencing batch reactor (SBR) supplied with glucose as carbon source was investigated. It was found that there was no phosphate release concomitant with the storing of poly-β-hydroxyalkanoate (PHA) during the anaerobic phase. Whereas, glycogen was soon built up followed by rapid consumption, at the same time, glucose was depleted rapidly. Based on the analysis of different fractions of phosphorus in activated sludge, the relative ratio of organically bound phosphorus in sludge changed at the end of anaerobic and aerobic phases. The ratios were 45.3% and 51.8% respectively. This showed that the polyphosphate broke down during the anaerobic phase to supply part of energy for PHA synthesis. The reason why there was no phosphate release might be the biosorption effect of extracellular exopolymers (EPS). It was also proved by the analysis of EPS with scanning electron microscopy (SEM) combined with energy dispersive spectrometry (EDS). The phosphorus weight percentage of EPS at the end of anaerobic phase was 9.22%.展开更多
Extracellular polymeric substances(EPS)are present externally to the microorganisms and play an important role in attachment and biofilm formation.These polymers possess antibacterial and antifouling activities.In thi...Extracellular polymeric substances(EPS)are present externally to the microorganisms and play an important role in attachment and biofilm formation.These polymers possess antibacterial and antifouling activities.In this study,the antifouling activity of EPS produced by an epibiotic bacterium associated with macroalga Ulva lactuca was assessed against fouling bacteria and barnacle larvae.Results indicate that the EPS isolated from the epibiotic bacterium inhibits the biofilm formation of the bacteria without much antibacterial activity.Also,the EPS reduced the settlement of barnacle larvae on the hard substrate under laboratory conditions.The epibiotic bacterium was identified as Kocuria flava based on 16 S rRNA gene sequencing.The EPS was further analysed using Fourier transform infrared(FT-IR),nuclear magnetic resonance(NMR)and X-ray diffraction(XRD)to understand the biochemical composition.NMR analysis revealed the presence of polysaccharides,proteins,acetyl amine and succinyl groups.Scanning electron microscope analysis indicated that the EPS consisted of aggregated and irregular sphere-shaped particles.展开更多
The biosorption of Pb^2+ by the organic components(exopolymer,nonliving body bacterium and living bacterium) on the dominant bacterium obtained from the surface coatings in natural waters and the effects of biosorptio...The biosorption of Pb^2+ by the organic components(exopolymer,nonliving body bacterium and living bacterium) on the dominant bacterium obtained from the surface coatings in natural waters and the effects of biosorption time,temperature and initial pH were investigated.The results showed that Pb^2+ biosorption process by the organic components above was divided into fast phase and slow phase,biosorption equilibrium time was 360,120 and 150 min respectively;the biosorption ability of exopolymer is much higher than nonliving body bacterium and living body bacterium,the maximum biosorption amount of Pb^2+ was all reached at pH=6,the effect of temperature on the biosorption ability of nonliving body bacterium and living body bacterium was negligible;both the Longmuir and Freundlish could describe the course of the biosorption of on Pb^2+ by the organic components.the biosorption ability of exopolymer is much higher than nonliving body bacterium and living body bacterium;the thermodynamics experiments also carried on when the Cd^2+ was present,the biosorption of Pb^2+ by the three organic components was also followed the Langmuir and Freundlich(equation),but the biosorption amount and the saturated biosorption amount of Pb^2+ was decreased.展开更多
The Southern Ocean is an important carbon sink pool and plays a critical role in the global carbon cycling.The Amundsen Sea was reported to be highly productive in inshore area in the Southern Ocean.In order to invest...The Southern Ocean is an important carbon sink pool and plays a critical role in the global carbon cycling.The Amundsen Sea was reported to be highly productive in inshore area in the Southern Ocean.In order to investigate the influence of transparent exopolymer particles(TEP)on the behavior of dissolved organic carbon(DOC)in this region,a comprehensive study was conducted,encompassing both open water areas and highly productive polynyas.It was found that microbial heterotrophic metabolism is the primary process responsible for the production of humic-like fluorescent components in the open ocean.The relationship between apparent oxygen utilization and the two humic-like components can be accurately described by a power-law function,with a conversion rate consistent with that observed globally.The presence of TEP was found to have little impact on this process.Additionally,the study revealed the accumulation of DOC at the sea surface in the Amundsen Sea Polynya,suggesting that TEP may play a critical role in this phenomenon.These findings contribute to a deeper understanding of the dynamics and surface accumulation of DOC in the Amundsen Sea Polynya,and provide valuable insights into the carbon cycle in this region.展开更多
Transparent exopolymer particles(TEPs)are ubiquitous throughout the oceans,and their sedimentation is considered an efficient biological carbon sink pathway.To investigate the role of coastal TEPs in sinking carbon fr...Transparent exopolymer particles(TEPs)are ubiquitous throughout the oceans,and their sedimentation is considered an efficient biological carbon sink pathway.To investigate the role of coastal TEPs in sinking carbon from the upper layer,samples were collected in the spring and summer of 2011 in the Changjiang River(Yangtze River)Estuary,a typical coastal water.The concentrations and sinking rates of TEPs were measured,and potential sedimentation flux of TEPs was estimated.TEPs concentrations ranged from 40.00μg/L to 1040.00μg/L(mean=(209.70±240.93)μg/L)in spring and 56.67μg/L to 1423.33μg/L(mean=(433.33±393.02)μg/L)in summer,and they were higher at bloom stations than at non-bloom stations during both cruises.A significant positive correlation between TEPs concentration and chlorophyll a(Chl a)concentration was detected,suggesting that phytoplankton was the primary source of TEPs in this area.TEPs sinking rates ranged from 0.08 m/d to 0.57 m/d with a mean of(0.28±0.14)m/d in spring and 0.10 m/d to 1.08 m/d with a mean of(0.34±0.31)m/d in summer.The potential sedimentation flux of TEP-C ranged from 4.95 mg/(m2·d)to 29.40 mg/(m2·d)with a mean of(14.66±8.83)mg/(m2·d)in spring and 6.80 mg/(m2·d)to 30.45 mg/(m2·d)with a mean of(15.71±8.73)mg/(m2·d)in summer,which was^17.81%to 138.27%(mean=65.15%±31.75%)of sedimentation flux of phytoplankton cells in the study area.Due to the increase of TEPs concentrations and their sinking rates,sedimentation fluxes of TEPs at the bloom station were obviously higher than at the non-bloom station during both cruises.This study indicates that TEPs serve as a carbon sink in the Changjiang River Estuary,especially during bloom events,and their sedimentation should be taken into account when we study the carbon sedimentation in the coastal sea.展开更多
Measurement of uronic acids (URAs) which are a group of acidic sugar, would be useful for the understanding of dynamics of bacterial extracellular polymeric substances (EPS) in marine environments. However, the URA an...Measurement of uronic acids (URAs) which are a group of acidic sugar, would be useful for the understanding of dynamics of bacterial extracellular polymeric substances (EPS) in marine environments. However, the URA analysis using traditional hydrolysis method which is used for neutral sugar analysis poses serious problems in URA that is unstable under hydrolysis. We developed the methanolysis method, which deploymerizes polysaccharides while retaining quantitative information. Our method was applied to coastal seawater, and the URAs distribution was compared with that of transparent exopolymer particles (TEP) which are acidic sugar containing particles. Since the relationship of URA with TEP was relatively weak, URA-containing polysaccharides present in bacterial EPS would not participate as a structural component of TEP.展开更多
To understand the response of transparent exopolymer particles(TEP)to the changes in phytoplankton communities caused by melting sea ice,we collected samples from the polynya and open ocean affected by the Antarctic c...To understand the response of transparent exopolymer particles(TEP)to the changes in phytoplankton communities caused by melting sea ice,we collected samples from the polynya and open ocean affected by the Antarctic circumpolar current in the Amundsen Sea.TEP,pigments,and other environmental factors were analyzed.The results showed that high TEP content was mainly found in the polynya,and was higher in the surface layer than in the deep layer.The main factor that affected TEP distribution was the phytoplankton community.In the polynya area,the phytoplankton were dominated by low-iron Haptophyta.In the Antarctic circumpolar current region affected by ice-melting water,the dominant species was diatom type II.Our results revealed that low-iron Haptophyta may be the main contributors to TEP content.展开更多
Transparent exopolymer particles(TEPs)are a class of transparent gel-like polysaccharides,which have been widely detected in almost every kind of feed water to membrane systems,including freshwater,seawater and wastew...Transparent exopolymer particles(TEPs)are a class of transparent gel-like polysaccharides,which have been widely detected in almost every kind of feed water to membrane systems,including freshwater,seawater and wastewater.Although TEP have been thought to be related to the membrane fouling,little information is currently available for their influential mechanisms and the pertinence to biofouling development.The present study,thus,aims to explore the impact of TEPs on biofouling development during ultrafiltration.TEP samples were inoculated with bacteria for several hours before filtration and the formation of“protobiofilm”(pre-colonized TEP by bacteria)was examined and its influence on biofouling was determined.It was observed that the bacteria can easily and quickly attach onto TEPs and form protobiofilms.Ultrafiltration experiments further revealed that TEP-protobiofilms served as carriers which facilitated and accelerated transport of bacteria to membrane surface,leading to rapid development of biofouling on the ultrafiltration membrane surfaces.Moreover,compared to the feed water containing independent bacteria and TEPs,more flux decline was observed with TEP-protobiofilms.Consequently,it appeared from this study that TEP-protobiofilms play a vital role in the development of membrane biofouling,but unfortunately,this phenomenon has been often overlooked in the literature.Obviously,these findings in turn may also challenge the current understanding of organic fouling and biofouling as membrane fouling caused by TEP-protobiofilm is a combination of both.It is expected that this study might promote further research in general membrane fouling mechanisms and the development of an effective mitigation strategy.展开更多
The presence of diatoms is accompanied by the production of a large amount of extracellular polymeric substances,which are mainly composed of carbohydrates.Transparent exopolymer particles(TEP)are a large class of ext...The presence of diatoms is accompanied by the production of a large amount of extracellular polymeric substances,which are mainly composed of carbohydrates.Transparent exopolymer particles(TEP)are a large class of extracellular polymeric substances with high stickiness that promotes the formation of aggregates and marine snow,which affects marine bio-carbon pump efficiency.The purpose of this research was to determine how temperature increases affect the allocation of cellular carbohydrates and the formation and aggregation of TEP.The results showed that the responses of two different diatom species(Thalassiosira weissflogii and Skeletonema marinoi)differed according to temperature.The cell density and chlorophyll a concentration of the former were not significantly correlated with temperature,while those of the latter were significantly decreased with increasing temperature.This indicates that the two species of diatom may have different heat tolerance ranges.A temperature increase will promote significant formation of TEP by both types of diatoms,including aggregation of S.marinoi as the temperature rises,meaning that the high temperature will produce an aggregate with a larger particle size and thus may increase the sedimentation rate of organic carbon.Moreover,the TEP aggregation of T.weissflogii did not increase;therefore,its particle size was smaller,and so it may remain on the sea surface at high temperatures for longer periods.These influences have a profound impact on the biogeochemical cycling of carbon.展开更多
The quantification of transparent exopolymer particles(TEP) by colorimetric method is of large error and low repeatability,one major reason of which is related to the absence of clear definition and evaluation for par...The quantification of transparent exopolymer particles(TEP) by colorimetric method is of large error and low repeatability,one major reason of which is related to the absence of clear definition and evaluation for part steps of the original method.It is obscure that the 80% sulfuric acid solution,acted as the extraction solution in the determination of TEP,is prepared based on a volume ratio or mass ratio.Furthermore,the change of solubility of recently available Gum Xanthan(GX) from the market means that the original protocol is no longer applicable,and the grinding of GX stock solution with a tissue grinder is replaced by shaking with a rotating shaker in the study to prevent the excessive dissolution of GX.We found that different preparation techniques could result in the varied concentrations of 80% H_(2)SO_(4).The duration of shaking during the preparation of standard solution significantly affected the slope of the calibration curve,which caused different correction results of TEP.The impacts of different extraction solution concentrations and shaking time of GX solution on the quantification of TEP were investigated based on the field sampling and laboratory analysis.The extraction capacities of H_(2)SO_(4) with different concentrations for Alcian Blue were distinct,but had limited effect on the final measuring result of TEP.The change of the standard curve slope came along with the variation of shaking time,which markedly altered the detection limit and calibration result,and the extended shaking time was in favor of the determination of low-concentration TEP.It was suggested that the extraction solution concentration,shaking time and filtration volume of standard solution are required to be well controlled and selected to obtain more accurate results for TEP with different concentrations.展开更多
Microgels are plankton-derived transparent exopolymer particles(TEP)and have a significant impact on global marine carbon cycle.We investigated the influence of biogeochemical variables on the pattern of TEP abundance...Microgels are plankton-derived transparent exopolymer particles(TEP)and have a significant impact on global marine carbon cycle.We investigated the influence of biogeochemical variables on the pattern of TEP abundance and its associated carbon(TEP C)distribution through a vertical transect of the northern South China Sea(nSCS)during summer,2014.The average TEP concentration was 58.32±30.56μg Xeq./L.Vertically,it was higher in the subsurface water column and lower at 200-m water depths.As chlorophyll a(chl a),TEP,and TEP C were highly concentrated at the bottom of the study transect,mainly on the continental shelf bottom and slope regions.Among biotic factors,cyanobacteria,especially Trichodesmium thiebautii showed significant positive correspondences with TEP through studied water columns in nSCS.In addition,TEP showed a positive correlation with chl-a distribution and clustered closely with diatom as well.It indicates a combined contribution of them on TEP sourcing accordingly.Nutrient concentrations were also high due to estuarine diluted water from Zhujiang(Pearl)River in the season that may intrigue those scenarios.Significant positive correlation(P<0.05)among biotic and abiotic parameters also supported the statement.Furthermore,mentionable contribution of TEP-derived TEP C was found after comparing the particulate organic carbon data,which may signify the importance of TEP in local carbon cycle in the nSCS.展开更多
以 Pseudomonas sn Gx。-1发酵培养得到的细菌胞外聚合物作吸附剂,研究其对水中重金属Cr(VI)的吸附。吸附剂对Cr(VI)吸附的最佳pH初值为05-20。Cr(VI)的吸附分三个阶段:srnin达乃％的快速吸附阶段;10-40min达表观一级反应动力学吸附阶段...以 Pseudomonas sn Gx。-1发酵培养得到的细菌胞外聚合物作吸附剂,研究其对水中重金属Cr(VI)的吸附。吸附剂对Cr(VI)吸附的最佳pH初值为05-20。Cr(VI)的吸附分三个阶段:srnin达乃％的快速吸附阶段;10-40min达表观一级反应动力学吸附阶段;50min以后趋于平衡。吸附过程符合Freundlich和Langmuir吸附等温方程。展开更多
基金supported by the National Nat- ural Science Foundation of China (No. 30970309)the Natural Science Foundation of He'nan Province (No. 082102220009)the Natural Science Foundation of He'nan Province Education Department (No. 2009A610001)
文摘The biosorption characteristics of Cs（I） ions from aqueous solution using exopolymers （PFC02） produced from Pseudomonas fluorescens C-2 were investigated as a function of pH, biosorbent dosage, contact time and initial concentration. pH played a major role in the adsorption process, and the optimum pH for the removal of Cs（I） was 8.0. Langmuir, Freundlich and Dubinin-Radushkevich （D-R） models were applied to describe the biosorption isotherm of the Cs（I） ions by PFC02. The Lagergren first-order, pseudo second-order kinetic and intraparticle diffusion models were used to test the kinetic data. Langmuir model and D-R model fitted the equilibrium data better than the Freundlich isotherm. The monolayer adsorption capacities of PFC02 as obtained from Langmuir isotherm at 25°C was found to be 32.63 mg/g. From the D-R isotherm model, the mean free energy was calculated as 26.73 kJ/mol, indicating that the biosorption of cesium was chemisorption. The biosorption process was rapid, and the kinetic rates were best fitted to the pseudo second-order model, which indicated the biosorption process operated through chemisorption mechanism. FT-IR analysis of PFC02 showed the possible functional groups responsible for cesium adsorption were hydroxyl, carboxyl, carbonyl and sulphonate groups. SEM analysis showed the porous structure of the material while EDX analysis confirmed the adsorption of Cs（I） on PFC02. Cesium adsorbed onto the PFC02 could be desorbed efficiently using 1 mol/L HNO 3 , and the enrichment factor was 50.0. Furthermore, PFC02 could be reused five times with only about 8.25% regeneration loss. The developed method was successfully utilized for the removal of Cs（I） ions from aqueous solution.
文摘Three sequencing batch reactors supplied with different carbon sources were investigated. The system supplied with glucose gained the best enhanced biological phosphorus removal although all of the three reactors were seeded from the same sludge. With the measurement of poly-β-hydroxyalkanoate （PHA） concentration, phosphorus content in sludge and extracellular exopolymers （EPS） with scanning electron microscopy （SEM） combined with energy dispersive spectrometry （EDS）, it was found that the biosorption effect of EPS played an important role in phosphorus removal and that the amount of PHA at the end of anaerobic phase was not the only key factor to determine the following phosphorus removal efficiency.
文摘Phosphorus removal performance in an aerobic/aerobic sequencing batch reactor (SBR) supplied with glucose as carbon source was investigated. It was found that there was no phosphate release concomitant with the storing of poly-β-hydroxyalkanoate (PHA) during the anaerobic phase. Whereas, glycogen was soon built up followed by rapid consumption, at the same time, glucose was depleted rapidly. Based on the analysis of different fractions of phosphorus in activated sludge, the relative ratio of organically bound phosphorus in sludge changed at the end of anaerobic and aerobic phases. The ratios were 45.3% and 51.8% respectively. This showed that the polyphosphate broke down during the anaerobic phase to supply part of energy for PHA synthesis. The reason why there was no phosphate release might be the biosorption effect of extracellular exopolymers (EPS). It was also proved by the analysis of EPS with scanning electron microscopy (SEM) combined with energy dispersive spectrometry (EDS). The phosphorus weight percentage of EPS at the end of anaerobic phase was 9.22%.
基金The Deanship of Scientific Research of King Abdulaziz University under contract No.G-153-150-39。
文摘Extracellular polymeric substances(EPS)are present externally to the microorganisms and play an important role in attachment and biofilm formation.These polymers possess antibacterial and antifouling activities.In this study,the antifouling activity of EPS produced by an epibiotic bacterium associated with macroalga Ulva lactuca was assessed against fouling bacteria and barnacle larvae.Results indicate that the EPS isolated from the epibiotic bacterium inhibits the biofilm formation of the bacteria without much antibacterial activity.Also,the EPS reduced the settlement of barnacle larvae on the hard substrate under laboratory conditions.The epibiotic bacterium was identified as Kocuria flava based on 16 S rRNA gene sequencing.The EPS was further analysed using Fourier transform infrared(FT-IR),nuclear magnetic resonance(NMR)and X-ray diffraction(XRD)to understand the biochemical composition.NMR analysis revealed the presence of polysaccharides,proteins,acetyl amine and succinyl groups.Scanning electron microscope analysis indicated that the EPS consisted of aggregated and irregular sphere-shaped particles.
文摘The biosorption of Pb^2+ by the organic components(exopolymer,nonliving body bacterium and living bacterium) on the dominant bacterium obtained from the surface coatings in natural waters and the effects of biosorption time,temperature and initial pH were investigated.The results showed that Pb^2+ biosorption process by the organic components above was divided into fast phase and slow phase,biosorption equilibrium time was 360,120 and 150 min respectively;the biosorption ability of exopolymer is much higher than nonliving body bacterium and living body bacterium,the maximum biosorption amount of Pb^2+ was all reached at pH=6,the effect of temperature on the biosorption ability of nonliving body bacterium and living body bacterium was negligible;both the Longmuir and Freundlish could describe the course of the biosorption of on Pb^2+ by the organic components.the biosorption ability of exopolymer is much higher than nonliving body bacterium and living body bacterium;the thermodynamics experiments also carried on when the Cd^2+ was present,the biosorption of Pb^2+ by the three organic components was also followed the Langmuir and Freundlich(equation),but the biosorption amount and the saturated biosorption amount of Pb^2+ was decreased.
基金funded by the National Natural Science Foundation of China(Grant nos.42276255 and 41976227)project“Impact and Response of Antarctic Seas to Climate Change,IRASCC 2020-2022”(Grant nos.01-01-02A and 02-02-05).
文摘The Southern Ocean is an important carbon sink pool and plays a critical role in the global carbon cycling.The Amundsen Sea was reported to be highly productive in inshore area in the Southern Ocean.In order to investigate the influence of transparent exopolymer particles(TEP)on the behavior of dissolved organic carbon(DOC)in this region,a comprehensive study was conducted,encompassing both open water areas and highly productive polynyas.It was found that microbial heterotrophic metabolism is the primary process responsible for the production of humic-like fluorescent components in the open ocean.The relationship between apparent oxygen utilization and the two humic-like components can be accurately described by a power-law function,with a conversion rate consistent with that observed globally.The presence of TEP was found to have little impact on this process.Additionally,the study revealed the accumulation of DOC at the sea surface in the Amundsen Sea Polynya,suggesting that TEP may play a critical role in this phenomenon.These findings contribute to a deeper understanding of the dynamics and surface accumulation of DOC in the Amundsen Sea Polynya,and provide valuable insights into the carbon cycle in this region.
基金Foundation item:The National Key Research and Development Project of China under contract No.2019YFC1407805the National Natural Science Foundation of China under contract Nos 41876134,91751202,31700425,41676112 and 41276124+1 种基金the Tianjin 131 Innovation Team Program under contract No.20180314the Changjiang Scholar Program of Chinese Ministry of Education(T2014253)to Jun Sun.
文摘Transparent exopolymer particles(TEPs)are ubiquitous throughout the oceans,and their sedimentation is considered an efficient biological carbon sink pathway.To investigate the role of coastal TEPs in sinking carbon from the upper layer,samples were collected in the spring and summer of 2011 in the Changjiang River(Yangtze River)Estuary,a typical coastal water.The concentrations and sinking rates of TEPs were measured,and potential sedimentation flux of TEPs was estimated.TEPs concentrations ranged from 40.00μg/L to 1040.00μg/L(mean=(209.70±240.93)μg/L)in spring and 56.67μg/L to 1423.33μg/L(mean=(433.33±393.02)μg/L)in summer,and they were higher at bloom stations than at non-bloom stations during both cruises.A significant positive correlation between TEPs concentration and chlorophyll a(Chl a)concentration was detected,suggesting that phytoplankton was the primary source of TEPs in this area.TEPs sinking rates ranged from 0.08 m/d to 0.57 m/d with a mean of(0.28±0.14)m/d in spring and 0.10 m/d to 1.08 m/d with a mean of(0.34±0.31)m/d in summer.The potential sedimentation flux of TEP-C ranged from 4.95 mg/(m2·d)to 29.40 mg/(m2·d)with a mean of(14.66±8.83)mg/(m2·d)in spring and 6.80 mg/(m2·d)to 30.45 mg/(m2·d)with a mean of(15.71±8.73)mg/(m2·d)in summer,which was^17.81%to 138.27%(mean=65.15%±31.75%)of sedimentation flux of phytoplankton cells in the study area.Due to the increase of TEPs concentrations and their sinking rates,sedimentation fluxes of TEPs at the bloom station were obviously higher than at the non-bloom station during both cruises.This study indicates that TEPs serve as a carbon sink in the Changjiang River Estuary,especially during bloom events,and their sedimentation should be taken into account when we study the carbon sedimentation in the coastal sea.
文摘Measurement of uronic acids (URAs) which are a group of acidic sugar, would be useful for the understanding of dynamics of bacterial extracellular polymeric substances (EPS) in marine environments. However, the URA analysis using traditional hydrolysis method which is used for neutral sugar analysis poses serious problems in URA that is unstable under hydrolysis. We developed the methanolysis method, which deploymerizes polysaccharides while retaining quantitative information. Our method was applied to coastal seawater, and the URAs distribution was compared with that of transparent exopolymer particles (TEP) which are acidic sugar containing particles. Since the relationship of URA with TEP was relatively weak, URA-containing polysaccharides present in bacterial EPS would not participate as a structural component of TEP.
基金financially supported by National Polar Special Program “Impact and Response of Antarctic Seas to Climate Change” (Grant nos. IRASCC 02-02-01, 02-02-03, 02-02-04, and 02-02-05)。
文摘To understand the response of transparent exopolymer particles(TEP)to the changes in phytoplankton communities caused by melting sea ice,we collected samples from the polynya and open ocean affected by the Antarctic circumpolar current in the Amundsen Sea.TEP,pigments,and other environmental factors were analyzed.The results showed that high TEP content was mainly found in the polynya,and was higher in the surface layer than in the deep layer.The main factor that affected TEP distribution was the phytoplankton community.In the polynya area,the phytoplankton were dominated by low-iron Haptophyta.In the Antarctic circumpolar current region affected by ice-melting water,the dominant species was diatom type II.Our results revealed that low-iron Haptophyta may be the main contributors to TEP content.
基金This work was financially supported by the National Natural Science Foundation of China(Grant Nos.51808019 and 51708338).
文摘Transparent exopolymer particles(TEPs)are a class of transparent gel-like polysaccharides,which have been widely detected in almost every kind of feed water to membrane systems,including freshwater,seawater and wastewater.Although TEP have been thought to be related to the membrane fouling,little information is currently available for their influential mechanisms and the pertinence to biofouling development.The present study,thus,aims to explore the impact of TEPs on biofouling development during ultrafiltration.TEP samples were inoculated with bacteria for several hours before filtration and the formation of“protobiofilm”(pre-colonized TEP by bacteria)was examined and its influence on biofouling was determined.It was observed that the bacteria can easily and quickly attach onto TEPs and form protobiofilms.Ultrafiltration experiments further revealed that TEP-protobiofilms served as carriers which facilitated and accelerated transport of bacteria to membrane surface,leading to rapid development of biofouling on the ultrafiltration membrane surfaces.Moreover,compared to the feed water containing independent bacteria and TEPs,more flux decline was observed with TEP-protobiofilms.Consequently,it appeared from this study that TEP-protobiofilms play a vital role in the development of membrane biofouling,but unfortunately,this phenomenon has been often overlooked in the literature.Obviously,these findings in turn may also challenge the current understanding of organic fouling and biofouling as membrane fouling caused by TEP-protobiofilm is a combination of both.It is expected that this study might promote further research in general membrane fouling mechanisms and the development of an effective mitigation strategy.
基金supported by the National Natural Science Foundation of China(No.31500411)the Guangxi Zhuang Autonomous Region International Platform Project(No.2019AC17008)+4 种基金the Guangxi Beihai Science and Technology Research Focus(Nos.201995048202082021 and 2019D05)the U.S.National Science Foundation(No.OCE 0726369)the Special Fund for Asian Regional Cooperation‘2019 China-ASEAN Marine Science and Technology Cooperation Seminar Project’the China Asia-Pacific Economic Cooperation(APEC)Cooperation Fund Project‘APEC Typical Regional Coral Reef Ecosystem Comprehensive Assessment Technology and Management Cooperation Research’the‘Bilateral and Multilateral International Cooperation’Project of the Central Financial Allocation Program in 2019 and 2020。
文摘The presence of diatoms is accompanied by the production of a large amount of extracellular polymeric substances,which are mainly composed of carbohydrates.Transparent exopolymer particles(TEP)are a large class of extracellular polymeric substances with high stickiness that promotes the formation of aggregates and marine snow,which affects marine bio-carbon pump efficiency.The purpose of this research was to determine how temperature increases affect the allocation of cellular carbohydrates and the formation and aggregation of TEP.The results showed that the responses of two different diatom species(Thalassiosira weissflogii and Skeletonema marinoi)differed according to temperature.The cell density and chlorophyll a concentration of the former were not significantly correlated with temperature,while those of the latter were significantly decreased with increasing temperature.This indicates that the two species of diatom may have different heat tolerance ranges.A temperature increase will promote significant formation of TEP by both types of diatoms,including aggregation of S.marinoi as the temperature rises,meaning that the high temperature will produce an aggregate with a larger particle size and thus may increase the sedimentation rate of organic carbon.Moreover,the TEP aggregation of T.weissflogii did not increase;therefore,its particle size was smaller,and so it may remain on the sea surface at high temperatures for longer periods.These influences have a profound impact on the biogeochemical cycling of carbon.
基金The National Key Research and Development Project of China under contract No.2019YFC1407805the National Natural Science Foundation of China under contract Nos 41876134, 41676112 and 41276124+1 种基金the Tianjin 131 Innovation Team Program under contract No.20180314the Changjiang Scholar Program of Chinese Ministry of Education under contract No.T2014253。
文摘The quantification of transparent exopolymer particles(TEP) by colorimetric method is of large error and low repeatability,one major reason of which is related to the absence of clear definition and evaluation for part steps of the original method.It is obscure that the 80% sulfuric acid solution,acted as the extraction solution in the determination of TEP,is prepared based on a volume ratio or mass ratio.Furthermore,the change of solubility of recently available Gum Xanthan(GX) from the market means that the original protocol is no longer applicable,and the grinding of GX stock solution with a tissue grinder is replaced by shaking with a rotating shaker in the study to prevent the excessive dissolution of GX.We found that different preparation techniques could result in the varied concentrations of 80% H_(2)SO_(4).The duration of shaking during the preparation of standard solution significantly affected the slope of the calibration curve,which caused different correction results of TEP.The impacts of different extraction solution concentrations and shaking time of GX solution on the quantification of TEP were investigated based on the field sampling and laboratory analysis.The extraction capacities of H_(2)SO_(4) with different concentrations for Alcian Blue were distinct,but had limited effect on the final measuring result of TEP.The change of the standard curve slope came along with the variation of shaking time,which markedly altered the detection limit and calibration result,and the extended shaking time was in favor of the determination of low-concentration TEP.It was suggested that the extraction solution concentration,shaking time and filtration volume of standard solution are required to be well controlled and selected to obtain more accurate results for TEP with different concentrations.
文摘Microgels are plankton-derived transparent exopolymer particles(TEP)and have a significant impact on global marine carbon cycle.We investigated the influence of biogeochemical variables on the pattern of TEP abundance and its associated carbon(TEP C)distribution through a vertical transect of the northern South China Sea(nSCS)during summer,2014.The average TEP concentration was 58.32±30.56μg Xeq./L.Vertically,it was higher in the subsurface water column and lower at 200-m water depths.As chlorophyll a(chl a),TEP,and TEP C were highly concentrated at the bottom of the study transect,mainly on the continental shelf bottom and slope regions.Among biotic factors,cyanobacteria,especially Trichodesmium thiebautii showed significant positive correspondences with TEP through studied water columns in nSCS.In addition,TEP showed a positive correlation with chl-a distribution and clustered closely with diatom as well.It indicates a combined contribution of them on TEP sourcing accordingly.Nutrient concentrations were also high due to estuarine diluted water from Zhujiang(Pearl)River in the season that may intrigue those scenarios.Significant positive correlation(P<0.05)among biotic and abiotic parameters also supported the statement.Furthermore,mentionable contribution of TEP-derived TEP C was found after comparing the particulate organic carbon data,which may signify the importance of TEP in local carbon cycle in the nSCS.
文摘以 Pseudomonas sn Gx。-1发酵培养得到的细菌胞外聚合物作吸附剂,研究其对水中重金属Cr(VI)的吸附。吸附剂对Cr(VI)吸附的最佳pH初值为05-20。Cr(VI)的吸附分三个阶段:srnin达乃％的快速吸附阶段;10-40min达表观一级反应动力学吸附阶段;50min以后趋于平衡。吸附过程符合Freundlich和Langmuir吸附等温方程。
