Humic-like dissolved organic matter(DOM),usually regarded as refractory,is a major component of DOM in marine sediment pore waters.However,its bio-reactivity remains poorly explored in natural environments,which makes...Humic-like dissolved organic matter(DOM),usually regarded as refractory,is a major component of DOM in marine sediment pore waters.However,its bio-reactivity remains poorly explored in natural environments,which makes its roles in supporting subsurface microbial communities and regulating long-term carbon cycling elusive.Here,the bio-reactivity of humiclike DOM was evaluated by modeled reaction rates together with its interactions with microbial communities in five sediment cores collected from the eutrophic Pearl River Estuary to the oligotrophic deep-sea basin in the northern South China Sea.We revealed contrasting relationships between humic-like DOM and microbes in the coastal and deep-sea sediments.In eutrophic coastal sediments,specific microbial groups enriched in the deep layers co-varied with humic-like DOM,while most microbial groups were significantly correlated with protein-like DOM,microbial transformation of which likely resulted in the production of humic-like DOM.On the contrary,in energy-limiting deep-sea sediments,over 70%of the microbial groups were found closely correlated with humic-like DOM,a net consumption of which was demonstrated in deep layers.The consumption of humic-like DOM in deep-sea sediments reduced its total production flux in the uppermost~5-meter layer to about one-tenth of that in coastal sediments,which could consequently decrease the refractory DOM flux to the overlying seawater and influence long-term oceanic carbon cycling.展开更多
A controlled experiment was designed to resolve the influence of nitrogen abundance on sediment organic matters in macrophyte-dominated lakes using fluorescence analysis.Macrophyte biomass showed coincident growth tre...A controlled experiment was designed to resolve the influence of nitrogen abundance on sediment organic matters in macrophyte-dominated lakes using fluorescence analysis.Macrophyte biomass showed coincident growth trends with time, but different variation rates with nitrogen treatment. All plant growth indexes with nitrogen addition(N, NH4Cl100, 200, 400 mg/kg, respectively) were lower than those of the control group. Four humiclike components, two autochthonous tryptophan-like components, and one autochthonous tyrosine-like component were identified using the parallel factor analysis model. The results suggested that the relative component changes of fluorescence in the colonized sediments were in direct relation to the change of root biomass with time. In the experiment, the root formation parameters of the plants studied were significantly affected by adding N in sediments, which may be related to the reason that the root growth was affected by N addition.Adding a low concentration of N to sediments can play a part in supplying nutrients to the plants. However, the intensive uptake of NH4^+may result in an increase in the intracellular concentration of ammonia, which is highly toxic to the plant cells. Hence, our experiment results manifested that organic matter cycling in the macrophyte-dominated sediment was influenced by nitrogen enrichment through influencing vegetation and relevant microbial activity.展开更多
Dissolved organic matter (DOM) plays an important role in heavy metal speciation and distribution in the aquatic environment especially for eutrophic lakes which have higher DOM concentration. Taihu Lake is the thir...Dissolved organic matter (DOM) plays an important role in heavy metal speciation and distribution in the aquatic environment especially for eutrophic lakes which have higher DOM concentration. Taihu Lake is the third largest freshwater and a high eutrophic lake in the downstream of the Yangtze River, China. In the lake, frequent breakout of algae blooms greatly increased the concentration of different organic matters in the lake sediment. In this study, sediment samples were collected from various part of Taihu Lake to explore the spatial difference in the binding potential of DOM with Cu. The titration experiment was adopted to quantitatively characterize the interaction between Cu(II) and DOM extracted from Taihu Lake sediments using ion selective electrode (ISE) and fluorescence quenching technology. The ISE results showed that the exogenous DOM had higher binding ability than endogenous DOM, and DOM derived from aquatic macrophytes had a higher binding ability than that derived from algae. The fluorescence quenching results indicated that humic substances played a key role in the complexation between DOM and Cu(II) in the lake. However, because of the frequent breakout of algae blooms, protein-like matters are also main component like hnmic matters in Taihu Lake. Therefore, the metals bound by protein-like substances should be caused concern as protein-like substances in DOM were unstable and they will release bound metal when decomposed.展开更多
Simulated photo-degradation of fluorescent dissolved organic matter(FDOM) in Lake Baihua(BH) and Lake Hongfeng(HF) was investigated with three-dimensional excitationemission matrix(3 DEEM) fluorescence combined with t...Simulated photo-degradation of fluorescent dissolved organic matter(FDOM) in Lake Baihua(BH) and Lake Hongfeng(HF) was investigated with three-dimensional excitationemission matrix(3 DEEM) fluorescence combined with the fluorescence regional integration(FRI),parallel factor(PARAFAC) analysis,and multi-order kinetic models.In the FRI analysis,fulvic-like and humic-like materials were the main constituents for both BH-FDOM and HF-FDOM.Four individual components were identified by use of PARAFAC analysis as humic-like components(C1),fulvic-like components(C2),protein-like components(C3) and unidentified components(C4).The maximum 3 DEEM fluorescence intensity of PARAFAC components C1-C3 decreased by about 60%,70% and 90%,respectively after photo-degradation.The multi-order kinetic model was acceptable to represent the photo-degradation of FDOM with correlation coefficient(Radj2)(0.963-0.998).The photo-degradation rate constants(kn) showed differences of three orders of magnitude,from 1.09 × 10-6 to 4.02 × 10-4 min-1,and half-life of multi-order model(T1/2n)ranged from 5.26 to 64.01 min.The decreased values of fluorescence index(FI) and biogenic index(BI),the fact that of percent fluorescence response parameter of Region I(PⅠ,n) showed the greatest change ratio,followed by percent fluorescence response parameter of Region II(PⅡ,n,while the largest decrease ratio was found for C3 components,and the lowest T1/2n was observed for C3,indicated preferential degradation of protein-like materials/components derived from biological sources during photodegradation.This research on the degradation of FDOM by 3 DEEM/FRI-PARAFAC would be beneficial to understanding the photo-degradation of FD OM in natural environments and accurately predicting the environmental behaviors of contaminants in the presence of FDOM.展开更多
Introduction Natural organic matter(NOM)present in source water has significant impact on water treatment processes and on the quality of drinking water.NOM is a complex mixture of diverse groups of organic compound...Introduction Natural organic matter(NOM)present in source water has significant impact on water treatment processes and on the quality of drinking water.NOM is a complex mixture of diverse groups of organic compounds,humic and fulvic acids,proteins,peptides,carbohydrates,and heterogeneous materials展开更多
In order to understand the transport and humification processes of dissolved organic matter(DOM) within sediments of a semi-arid floodplain at Rifle,Colorado,fluorescence excitation–emission matrix(EEM) spectrosc...In order to understand the transport and humification processes of dissolved organic matter(DOM) within sediments of a semi-arid floodplain at Rifle,Colorado,fluorescence excitation–emission matrix(EEM) spectroscopy,humification index(HIX) and specific UV absorbance(SUVA) at 254 nm were applied for characterizing depth and seasonal variations of DOM composition.Results revealed that late spring snowmelt leached relatively fresh DOM from plant residue and soil organic matter down into the deeper vadose zone(VZ).More humified DOM is preferentially adsorbed by upper VZ sediments,while non-or lesshumified DOM was transported into the deeper VZ.Interestingly,DOM at all depths undergoes rapid biological humification process evidenced by the products of microbial by-product-like(i.e.,tyrosine-like and tryptophan-like) matter in late spring and early summer,particularly in the deeper VZ,resulting in more humified DOM(e.g.,fulvic-acid-like and humic-acid-like substances) at the end of year.This indicates that DOM transport is dominated by spring snowmelt,and DOM humification is controlled by microbial degradation,with seasonal variations.It is expected that these relatively simple spectroscopic measurements(e.g.,EEM spectroscopy,HIX and SUVA) applied to depth-and temporally-distributed pore-water samples can provide useful insights into transport and humification of DOM in other subsurface environments as well.展开更多
Critical algal blooms in great lakes increase the level of algal organic matters(AOMs),significantly altering the composition of natural organic matters(NOMs) in freshwater of lake.This study examined the AOM's c...Critical algal blooms in great lakes increase the level of algal organic matters(AOMs),significantly altering the composition of natural organic matters(NOMs) in freshwater of lake.This study examined the AOM's characteristics of Nitzschia palea(N.palea),one kind of the predominant diatom and an important biomarker of water quality in the great lakes of China,to investigate the effect of AOMs on the variation of NOMs in lakes and the process of algal energy.Excitation–emission matrix fluorescence(EEM) spectroscopy,synchronous fluorescence(SF) spectroscopy and deconvolution UV–vis(D-UV) spectroscopy were utilized to characterize AOMs to study the effects of nutrient loading on the composition change of AOMs.From results,it was revealed that the phosphorus is the limiting factor for N.palea's growth and the generation of both total organic carbon and amino acids but the nitrogen is more important for the generation of carbohydrates and proteins.EEM spectra revealed differences in the composition of extracellular organic matter and intracellular organic matter.Regardless of the nitrogen and phosphorus concentrations,aromatic proteins and soluble microbial products were the main components,but the nitrogen concentration had a significant impact on their composition.The SF spectra were used to study the AOMs for the first time and identified that the protein-like substances were the major component of AOMs,creating as a result of aromatic group condensation.The D-UV spectra showed carboxylic acid and esters were the main functional groups in the EOMs,with –OCH_3,–SO_2NH_2,–CN,–NH_2,–O– and –COCH_3functional groups substituting into benzene rings.展开更多
This work investigated the application of several fluorescence excitation–emission matrix analysis methods as natural organic matter(NOM) indicators for use in predicting the formation of trihalomethanes(THMs) an...This work investigated the application of several fluorescence excitation–emission matrix analysis methods as natural organic matter(NOM) indicators for use in predicting the formation of trihalomethanes(THMs) and haloacetic acids(HAAs). Waters from four different sources(two rivers and two lakes) were subjected to jar testing followed by 24 hr disinfection by-product formation tests using chlorine. NOM was quantified using three common measures: dissolved organic carbon, ultraviolet absorbance at 254 nm, and specific ultraviolet absorbance as well as by principal component analysis, peak picking,and parallel factor analysis of fluorescence spectra. Based on multi-linear modeling of THMs and HAAs, principle component(PC) scores resulted in the lowest mean squared prediction error of cross-folded test sets(THMs: 43.7(μg/L)^2, HAAs: 233.3(μg/L)^2). Inclusion of principle components representative of protein-like material significantly decreased prediction error for both THMs and HAAs. Parallel factor analysis did not identify a protein-like component and resulted in prediction errors similar to traditional NOM surrogates as well as fluorescence peak picking. These results support the value of fluorescence excitation–emission matrix–principal component analysis as a suitable NOM indicator in predicting the formation of THMs and HAAs for the water sources studied.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.42141003,41921006&41867057)the National Key Research and Development Program of China(Grant No.2020YFA0608300)+4 种基金the“Shanghai Jiao Tong University 2030”Program(Grant No.WH510244001)partially by the Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(Grant No.SMSEGL20SC01)the Center for Ocean Research in Hong Kong and Macao(CORECORE is a joint research center for ocean research between QNLM and HKUST)The SO269 cruise(SOCLIS-South China Sea-natural Laboratory under climatic and human induced stress,BMBF FKZ 03G0269)was a contribution to the bilateral Sino-German project MEGAPOL-Megacity’s fingerprint in Chinese marginal seas:Investigation of pollutant fingerprints and dispersal within the framework of WTZ China of the German government and was founded by BMBF(Grant No.03F0786A)。
文摘Humic-like dissolved organic matter(DOM),usually regarded as refractory,is a major component of DOM in marine sediment pore waters.However,its bio-reactivity remains poorly explored in natural environments,which makes its roles in supporting subsurface microbial communities and regulating long-term carbon cycling elusive.Here,the bio-reactivity of humiclike DOM was evaluated by modeled reaction rates together with its interactions with microbial communities in five sediment cores collected from the eutrophic Pearl River Estuary to the oligotrophic deep-sea basin in the northern South China Sea.We revealed contrasting relationships between humic-like DOM and microbes in the coastal and deep-sea sediments.In eutrophic coastal sediments,specific microbial groups enriched in the deep layers co-varied with humic-like DOM,while most microbial groups were significantly correlated with protein-like DOM,microbial transformation of which likely resulted in the production of humic-like DOM.On the contrary,in energy-limiting deep-sea sediments,over 70%of the microbial groups were found closely correlated with humic-like DOM,a net consumption of which was demonstrated in deep layers.The consumption of humic-like DOM in deep-sea sediments reduced its total production flux in the uppermost~5-meter layer to about one-tenth of that in coastal sediments,which could consequently decrease the refractory DOM flux to the overlying seawater and influence long-term oceanic carbon cycling.
基金supported by the National Basic Research Program (973) of China (No. 2012CB417004)the National Natural Science Foundation of China (Nos. U1202235,41173118, 41301544)the Shandong Provincial Natural Science Foundation (No. ZR2012DQ003)
文摘A controlled experiment was designed to resolve the influence of nitrogen abundance on sediment organic matters in macrophyte-dominated lakes using fluorescence analysis.Macrophyte biomass showed coincident growth trends with time, but different variation rates with nitrogen treatment. All plant growth indexes with nitrogen addition(N, NH4Cl100, 200, 400 mg/kg, respectively) were lower than those of the control group. Four humiclike components, two autochthonous tryptophan-like components, and one autochthonous tyrosine-like component were identified using the parallel factor analysis model. The results suggested that the relative component changes of fluorescence in the colonized sediments were in direct relation to the change of root biomass with time. In the experiment, the root formation parameters of the plants studied were significantly affected by adding N in sediments, which may be related to the reason that the root growth was affected by N addition.Adding a low concentration of N to sediments can play a part in supplying nutrients to the plants. However, the intensive uptake of NH4^+may result in an increase in the intracellular concentration of ammonia, which is highly toxic to the plant cells. Hence, our experiment results manifested that organic matter cycling in the macrophyte-dominated sediment was influenced by nitrogen enrichment through influencing vegetation and relevant microbial activity.
基金Acknowledgements This work was financially supported by the National Basic Research Program of China (No. 2008CB418201), the National Natural Science Foundation of China (Grant No. 51278475) and Scientific Innovation Research of College Graduate in Jiangsu Province" (CXZZ11_0317). Catherine Bentsen kindly edited the English language of our manuscript.
文摘Dissolved organic matter (DOM) plays an important role in heavy metal speciation and distribution in the aquatic environment especially for eutrophic lakes which have higher DOM concentration. Taihu Lake is the third largest freshwater and a high eutrophic lake in the downstream of the Yangtze River, China. In the lake, frequent breakout of algae blooms greatly increased the concentration of different organic matters in the lake sediment. In this study, sediment samples were collected from various part of Taihu Lake to explore the spatial difference in the binding potential of DOM with Cu. The titration experiment was adopted to quantitatively characterize the interaction between Cu(II) and DOM extracted from Taihu Lake sediments using ion selective electrode (ISE) and fluorescence quenching technology. The ISE results showed that the exogenous DOM had higher binding ability than endogenous DOM, and DOM derived from aquatic macrophytes had a higher binding ability than that derived from algae. The fluorescence quenching results indicated that humic substances played a key role in the complexation between DOM and Cu(II) in the lake. However, because of the frequent breakout of algae blooms, protein-like matters are also main component like hnmic matters in Taihu Lake. Therefore, the metals bound by protein-like substances should be caused concern as protein-like substances in DOM were unstable and they will release bound metal when decomposed.
基金financially supported by the National Natural Science Foundation of China(No.41573130)BNU Interdisciplinary Research Foundation for First-Year Doctoral Candidates(No.BNUXKJC1802)
文摘Simulated photo-degradation of fluorescent dissolved organic matter(FDOM) in Lake Baihua(BH) and Lake Hongfeng(HF) was investigated with three-dimensional excitationemission matrix(3 DEEM) fluorescence combined with the fluorescence regional integration(FRI),parallel factor(PARAFAC) analysis,and multi-order kinetic models.In the FRI analysis,fulvic-like and humic-like materials were the main constituents for both BH-FDOM and HF-FDOM.Four individual components were identified by use of PARAFAC analysis as humic-like components(C1),fulvic-like components(C2),protein-like components(C3) and unidentified components(C4).The maximum 3 DEEM fluorescence intensity of PARAFAC components C1-C3 decreased by about 60%,70% and 90%,respectively after photo-degradation.The multi-order kinetic model was acceptable to represent the photo-degradation of FDOM with correlation coefficient(Radj2)(0.963-0.998).The photo-degradation rate constants(kn) showed differences of three orders of magnitude,from 1.09 × 10-6 to 4.02 × 10-4 min-1,and half-life of multi-order model(T1/2n)ranged from 5.26 to 64.01 min.The decreased values of fluorescence index(FI) and biogenic index(BI),the fact that of percent fluorescence response parameter of Region I(PⅠ,n) showed the greatest change ratio,followed by percent fluorescence response parameter of Region II(PⅡ,n,while the largest decrease ratio was found for C3 components,and the lowest T1/2n was observed for C3,indicated preferential degradation of protein-like materials/components derived from biological sources during photodegradation.This research on the degradation of FDOM by 3 DEEM/FRI-PARAFAC would be beneficial to understanding the photo-degradation of FD OM in natural environments and accurately predicting the environmental behaviors of contaminants in the presence of FDOM.
基金supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)the National Natural Science Foundation of China,Alberta Innovates,and Alberta Health
文摘Introduction Natural organic matter(NOM)present in source water has significant impact on water treatment processes and on the quality of drinking water.NOM is a complex mixture of diverse groups of organic compounds,humic and fulvic acids,proteins,peptides,carbohydrates,and heterogeneous materials
基金partially performed at the Molecular Foundry,Lawrence Berkeley National Laboratorysupported as part of the Sustainable Systems Scientific Focus Area program at Lawrence Berkeley National Laboratorysupported by the U.S.Department of Energy,Office of Science,Office of Biological and Environmental Research,Subsurface Biogeochemical Research Program,through Contract No.DE-AC02-05CH11231 between Lawrence Berkeley National Laboratory and the U.S.Department of Energy
文摘In order to understand the transport and humification processes of dissolved organic matter(DOM) within sediments of a semi-arid floodplain at Rifle,Colorado,fluorescence excitation–emission matrix(EEM) spectroscopy,humification index(HIX) and specific UV absorbance(SUVA) at 254 nm were applied for characterizing depth and seasonal variations of DOM composition.Results revealed that late spring snowmelt leached relatively fresh DOM from plant residue and soil organic matter down into the deeper vadose zone(VZ).More humified DOM is preferentially adsorbed by upper VZ sediments,while non-or lesshumified DOM was transported into the deeper VZ.Interestingly,DOM at all depths undergoes rapid biological humification process evidenced by the products of microbial by-product-like(i.e.,tyrosine-like and tryptophan-like) matter in late spring and early summer,particularly in the deeper VZ,resulting in more humified DOM(e.g.,fulvic-acid-like and humic-acid-like substances) at the end of year.This indicates that DOM transport is dominated by spring snowmelt,and DOM humification is controlled by microbial degradation,with seasonal variations.It is expected that these relatively simple spectroscopic measurements(e.g.,EEM spectroscopy,HIX and SUVA) applied to depth-and temporally-distributed pore-water samples can provide useful insights into transport and humification of DOM in other subsurface environments as well.
基金the support of Fundamental Research Funds for the Central Universities (No.2015ZCQ-HJ-02)the National Natural Science Foundation of China (Nos.51578520,51378063,41273137 and 51108030)+1 种基金the Beijing Natural Science Foundation (No.8132033)Open Project of State Key Laboratory of Urban Water Resource and Environment,Harbin Institute of Technology (No.QAK201306)
文摘Critical algal blooms in great lakes increase the level of algal organic matters(AOMs),significantly altering the composition of natural organic matters(NOMs) in freshwater of lake.This study examined the AOM's characteristics of Nitzschia palea(N.palea),one kind of the predominant diatom and an important biomarker of water quality in the great lakes of China,to investigate the effect of AOMs on the variation of NOMs in lakes and the process of algal energy.Excitation–emission matrix fluorescence(EEM) spectroscopy,synchronous fluorescence(SF) spectroscopy and deconvolution UV–vis(D-UV) spectroscopy were utilized to characterize AOMs to study the effects of nutrient loading on the composition change of AOMs.From results,it was revealed that the phosphorus is the limiting factor for N.palea's growth and the generation of both total organic carbon and amino acids but the nitrogen is more important for the generation of carbohydrates and proteins.EEM spectra revealed differences in the composition of extracellular organic matter and intracellular organic matter.Regardless of the nitrogen and phosphorus concentrations,aromatic proteins and soluble microbial products were the main components,but the nitrogen concentration had a significant impact on their composition.The SF spectra were used to study the AOMs for the first time and identified that the protein-like substances were the major component of AOMs,creating as a result of aromatic group condensation.The D-UV spectra showed carboxylic acid and esters were the main functional groups in the EOMs,with –OCH_3,–SO_2NH_2,–CN,–NH_2,–O– and –COCH_3functional groups substituting into benzene rings.
基金funded in part by the Canadian Water Network and the Natural Sciences and Engineering Research Council of Canada Chair in Drinking Water Research at the University of Toronto
文摘This work investigated the application of several fluorescence excitation–emission matrix analysis methods as natural organic matter(NOM) indicators for use in predicting the formation of trihalomethanes(THMs) and haloacetic acids(HAAs). Waters from four different sources(two rivers and two lakes) were subjected to jar testing followed by 24 hr disinfection by-product formation tests using chlorine. NOM was quantified using three common measures: dissolved organic carbon, ultraviolet absorbance at 254 nm, and specific ultraviolet absorbance as well as by principal component analysis, peak picking,and parallel factor analysis of fluorescence spectra. Based on multi-linear modeling of THMs and HAAs, principle component(PC) scores resulted in the lowest mean squared prediction error of cross-folded test sets(THMs: 43.7(μg/L)^2, HAAs: 233.3(μg/L)^2). Inclusion of principle components representative of protein-like material significantly decreased prediction error for both THMs and HAAs. Parallel factor analysis did not identify a protein-like component and resulted in prediction errors similar to traditional NOM surrogates as well as fluorescence peak picking. These results support the value of fluorescence excitation–emission matrix–principal component analysis as a suitable NOM indicator in predicting the formation of THMs and HAAs for the water sources studied.