China’s lakes are plagued by cadmium(Cd)pollution.Dissolved organic matter(DOM)significantly regulates Cd(II)transport properties at the sediment-water interface.Understanding the effects of different DOM components ...China’s lakes are plagued by cadmium(Cd)pollution.Dissolved organic matter(DOM)significantly regulates Cd(II)transport properties at the sediment-water interface.Understanding the effects of different DOM components on the transportation properties of Cd(II)at the sediment-water interface is essential.In this study,typical DOM from different sources was selected to study Cd(II)mobility at the sediment-water interface.Results showed that terrestrial-derived DOM(fulvic acids,FA)and autochthonous-derived DOM(α-amylase,B1)inhibit Cd(II)sequestration by sediments(42.5%and 5.8%,respectively),while anthropogenic-derived DOM(sodium dodecyl benzene sulfonate,SDBS)increased the Cd(II)adsorption capacity by sediments by 2.8%.Fluorescence quenching coupling with parallel factor analysis(EEM-PARAFAC)was used to characterize different DOM components.The results showed that FA contains three kinds of components(C1,C3:protein-like components,C2:humic-like components);SDBS contains two kinds of components(C1,C2:protein-like components);B1 contains three kinds of components(C1,C2:protein-like components,C3:humic-like components).Three complex reaction modelswere used to characterize the ability of Cd(II)complex with DOM,and it was found that the humic-like component could hardly be complex with Cd(II).Accordingly,humic-like components compete for Cd(II)adsorption sites on the sediment surface and inhibit Cd(II)adsorption fromsediments.Fourier transform infrared spectroscopy(FTIR)of the sediment surface before and after Cd(II)addition was analyzed and proved the competitive adsorption theory.This study provides a better understanding of the Cd(II)mobilization behavior at the sediment-water interface and indicates that the input of humic-like DOM will increase the bioavailability of Cd.展开更多
The dissolved organic matter(DOM)with high mobility and reactivity plays a crucial role in soil.In this study,the characteristics and phytotoxicity ofDOMreleased fromthe hydrochars prepared from different feedstocks(c...The dissolved organic matter(DOM)with high mobility and reactivity plays a crucial role in soil.In this study,the characteristics and phytotoxicity ofDOMreleased fromthe hydrochars prepared from different feedstocks(cowmanure,corn stalk and Myriophyllum aquaticum)under three hydrothermal carbonization(HTC)temperatures(180,200 and 220°C)were evaluated.The results showed that the hydrochars had high dissolved organic carbon content(20.15 to 37.65 mg/g)and its content showed a gradual reduction as HTC temperature increased.Three fluorescent components including mixed substance of fulvic acid-like and humic acid-like substances(C1,30.92%-58.32%),UVA humic acid-like substance(C2,25.27%-29.94%)and protein-like substance(C3,11.74%-41.92%)were identified in hydrochar DOM by excitation emission matrix spectra coupled with parallel factor analysis.High HTC temperature increased the relative proportion of aromatic substances(C1+C2)and humification degree of hydrochar DOM from cow manure,while it presented adverse effects on the hydrochar DOM from corn stalk and Myriophyllum.aquaticum.The principal component analysis suggested that feedstock type and HTC temperature posed significant effects on the characteristics of hydrochar DOM.Additionally,seed germination test of all hydrochar DOM demonstrated that the root length was reduced by 8.88%-26.43%in contrast with control,and the germination index values were 73.57%-91.12%.These findings provided new insights into the potential environmental effects for hydrochar application in soil.展开更多
Lake Baiyangdian is one of China’s largest macrophyte-derived lakes,facing severe challenges related to water quality maintenance and eutrophication prevention.Dissolved organic matter(DOM)was a huge carbon pool and ...Lake Baiyangdian is one of China’s largest macrophyte-derived lakes,facing severe challenges related to water quality maintenance and eutrophication prevention.Dissolved organic matter(DOM)was a huge carbon pool and its abundance,property,and transformation played important roles in the biogeochemical cycle and energy flow in lake ecosystems.In this study,Lake Baiyangdian was divided into four distinct areas:Unartificial Area(UA),Village Area(VA),Tourism Area(TA),and Breeding Area(BA).We examined the diversity of DOM properties and sources across these functional areas.Our findings reveal that DOM in this lake is predominantly composed of protein-like substances,as determined by excitation-emission matrix and parallel factor analysis(EEM-PARAFAC).Notably,the exogenous tyrosine-like component C1 showed a stronger presence in VA and BA compared to UA and TA.Ultrahigh-resolution mass spectrometry(FT-ICR MS)unveiled a similar DOM molecular composition pattern across different functional areas due to the high relative abundances of lignan compounds,suggesting that macrophytes significantly influence the material structure of DOM.DOM properties exhibited specific associations with water quality indicators in various functional areas,as indicated by the Mantel test.The connections between DOM properties and NO_(3)-N andNH3-Nwere more pronounced in VA and BA than in UA and TA.Our results underscore the viability of using DOM as an indicator for more precise and scientific water quality management.展开更多
Dissolved organic carbon(DOC)constitutes the largest organic carbon reservoir in the ocean and plays a vital role in the oceanic carbon cycle.However,research on DOC in Antarctica has been limited,largely due to diffi...Dissolved organic carbon(DOC)constitutes the largest organic carbon reservoir in the ocean and plays a vital role in the oceanic carbon cycle.However,research on DOC in Antarctica has been limited,largely due to difficulties in sample collection.In this study,we investigate chromophoric dissolved organic matter(CDOM)in the Cosmonaut Sea and Cooperation Sea,Antarctica.The relative abundances of CDOM,as indicated by the absorption coefficient at 254 nm(a_(254)),exhibit significant variability,ranging from 1.29 m^(-1) to 8.37 m^(-1).The diatom species B is the primary contributor to CDOM in the region influenced by the Antarctic slope current.Using excitation-emission matrix fluorescence spectroscopy coupled with parallel factor analysis(EEM-PARAFAC),we identify three fluorescent components:one protein-like component(C1)and two humic-like components(C2 and C3).Our findings indicate that strong microbial activity in the euphotic zones of the Cosmonaut Sea and Cooperation Sea serves as a primary pathway for the removal of protein-like substances while also acting as a significant source of humic-like substances.Microbial degradation likely accounts for the decoupling of the vertical distribution of DOC and phytoplankton.Furthermore,the intrusion of modified circumpolar deep water(mCDW)into the euphotic zones of open ocean areas influences the distribution of CDOM at depths shallower than 200 m.These results have important implications for enhancing our understanding of the dynamics of CDOM and DOC in east Antarctica,as well as for improving assessments of the carbon cycle.展开更多
The copper complexing of dissolved organic matter released from hydrochar(HDOM)affects the former’s environmental behavior.In this study,how hydrothermal temperatures(180,220 and 260℃)influence the molecular-level c...The copper complexing of dissolved organic matter released from hydrochar(HDOM)affects the former’s environmental behavior.In this study,how hydrothermal temperatures(180,220 and 260℃)influence the molecular-level constitutions and Cu(II)binding features of HDOM were elucidated via fourier transform ion cyclotron resonance mass spectrometry and multi-spectroscopic analysis.The findings demonstrated that the almost HDOM molecules had the traits of lower polarity and higher hydrophobicity.As the hydrothermal temperature increased,the molecules with particularly high relative strength gradually disappeared,average molecular weight,percentages of CHON and aliphatic compounds of HDOM reduced while the percentages of CHO and aromatic compounds increased.In general,the fluorescence quenching of Cu(II)weakened as hydrothermal temperature rose and the Cu(II)binding stability constants of fluorophores in HDOM were 4.50–5.31.In addition,the Cu(II) binding order of fluorophores in HDOM showed temperature heterogeneities, andpolysaccharides or aromatic rings of non-fluorescent substances had the fastest responsesto Cu(II) binding. Generally, fluorescent components tend to bind Cu(II) at relatively traceconcentrations (0–40 μmol/L), whereas non-fluorescent substances tend to the bind Cu(II)at relatively higher concentrations (50–100 μmol/L). This study contributed to the predictionof the potential environmental behaviors and risks of Cu(II) at the molecular level afterhydrochar application.展开更多
Biochar-derived dissolved organic matter(BCDOM),an essential component of biochar,plays a vital role in regulating the physicochemical and biological properties of soils during biochar application.However,the influenc...Biochar-derived dissolved organic matter(BCDOM),an essential component of biochar,plays a vital role in regulating the physicochemical and biological properties of soils during biochar application.However,the influence of BCDOM on soil organisms has not been clearly explained.Hence,this review aims to discuss the factors affecting BCDOM and its interaction with soil substances including organic pollutants,heavy metals,and microorganisms.Results displayed that the quantity of BCDOM ranges from 0.17 to 37.03 mg/g,which was influenced by feedstock,preparation methods of biochar,and extraction methods.With the decrease in lignin content of feedstocks,carbonization temperature,and acidity of extraction solution,the content of BCDOM increased.Through complexation and adsorption,protein-like components in BCDOM interact with heavy metals,promoting the adsorption and immobilization of heavy metals onto biochar.Furthermore,BCDOM enhances the adsorption of organic pollutants by biochar throughπ−πinteractions,hydrogen bonding,and redox processes.More importantly,BCDOM promotes plant growth by enhancing microbial activities,providing nutrients,and improving soil properties.However,the transport and fate of BCDOM in soil have not been well studied,and more researches are needed to explore the interaction mechanisms between BCDOM and soil organisms.展开更多
Temperate glaciers are highly sensitive to variations in climate and environmental conditions.Investigating the chemical composition of dissolved organic matter(DOM)in glacier snow is essential for understanding its c...Temperate glaciers are highly sensitive to variations in climate and environmental conditions.Investigating the chemical composition of dissolved organic matter(DOM)in glacier snow is essential for understanding its characteristics,sources,and transformation processes within glacial systems.This study aims to elucidate the chemical composition and transformation of DOM in snow environment by analyzing samples collected from snowpits,surface snow,and snow meltwater at Baishui Glacier No.1 on Mt.Yulong during May and June.The average concentrations of dissolved organic carbon(DOC)in snow meltwater collected in May(1.63±0.63 mg L^(-1))and June(1.54±0.35 mg L^(-1))were both significantly higher than those measured in snowpit samples from May(0.74±0.10 mg L^(-1))and June(0.54±0.10 mg L^(-1)),as well as in surface snow samples from May(0.65±0.31 mg L^(-1))and June(0.69±0.30 mg L^(-1)).However,the concentrations of DOC in samples from the same category did not show significant variation between May and June.Using excitation-emission matrix(EEM)fluorescence spectroscopy coupled with parallel factor(PARAFAC)analysis,three protein-like components(C_(1),C_(2),and C_(3))and one humic-like component(C_(4))were identified.The protein-like components accounted for more than 75%of the total DOM in all snow samples,indicating that the fluorescent DOM originated from biological or microbial sources.Significant differences in the relative proportions of the four fluorescent components were observed between snowpit samples from May and June,whereas no significant variations were noted in the other sample types.Furthermore,a clear transformation from protein-like to humic-like components was observed during the transition from snowpits to snow meltwater.Further analysis using Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS)revealed that DOM in these snow samples was predominantly composed of aliphatic and peptide-like compounds(30.9%-50.9%),suggesting a substantial microbial contribution.FT-ICR MS data also demonstrated compositional shifts in DOM among snowpit,surface snow,and meltwater samples.Specifically,aliphatic and peptide-like compounds were progressively transformed into unsaturated compounds with high oxygen content,polyphenolic species,and condensed aromatic compounds during their transition from snowpit to meltwater.Therefore,the relative contribution of terrestrial-derived DOM increased during the transition from snowpit to snowmelt.Furthermore,an increase in heteroatom content in the DOM of meltwater samples indicated continuous chemical transformations likely driven by biological activity and/or photochemical processes during snowmelt and leaching.展开更多
Dissolved organic matter(DOM)is very important in aquatic environments,yet it is challenging to characterize DOM as a highly complex mixture of thousands of molecules,and the knowledge of the effects of different degr...Dissolved organic matter(DOM)is very important in aquatic environments,yet it is challenging to characterize DOM as a highly complex mixture of thousands of molecules,and the knowledge of the effects of different degradation processes on different molecules remains limited.This study examined the distribution and degradation of DOM in a large subtropical river using optical techniques and Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR-MS).At the molecular level,DOM was mainly composed of CHO and lignin-like compounds,which was related to the dominance of forestland in the watershed and resulted in a low biological lability index(MLBL).The modified aromaticity index(AI_(mod)),unsaturation degree(DBE),and humic content(HIX)decreased while MLBL,H/C,absorption spectral slope(S_(275–295)),and biological index(BIX)increased in the estuarine zone due to the increasing autochthonous contribution.Photo-and microbial degradation resulted in a similar decrease in the bulk dissolved organic carbon,while they showed opposite effects on the DOM composition.Photo-degradation removed all fluorescent components and decreased molecular weight,HIX,AI_(mod),DBE,%CHO,%lignin-like,%tannin-like,and%condensed aromatic-like compounds.In contrast,bio-degradation preferentially consumed lipid-like,protein-like,and carbohydrate-like compounds,with increases in%ligninlike,%tannin-like,%condensed aromatic-like compounds,and humic-like fluorescent components.Overall,the application of ultra-high resolutionmass spectrometry provided valuable insights into the composition and behavior of DOM at themolecular level and revealed the contrasting effects of photo-and microbial degradation on different compounds.These results have implications for better understanding the composition and transformation of aquatic DOM.展开更多
Spring dinoflagellate blooms are always severe in the Three Gorges Reservoir(TGR),China,threatening water ecological health.Many dinoflagellates are capable of mixotrophism,yet the influence of dissolved organic matte...Spring dinoflagellate blooms are always severe in the Three Gorges Reservoir(TGR),China,threatening water ecological health.Many dinoflagellates are capable of mixotrophism,yet the influence of dissolved organic matter(DOM)on their growth and blooms in spring remains unclear.This study characterized the source and composition of DOM from sediment,soil,and plant,and assessed their effects on the growth of bloom-forming algal species(Peridiniopsis sp.and Microcystis aeruginosa)under different temperatures.The results showed that sediment and soil DOM promoted Peridiniopsis sp.growth,plant DOM slightly inhibited it.However,DOM had no significant effect on M.aeruginosa growth.The promotion of sediment and soil DOM on Peridiniopsis sp.growth was higher at 15℃and 20℃ than at 25℃.Moreover,the effect of DOM on Peridiniopsis sp.growth was more significant than that of high nitrogen and phosphorus.Fulvic acid-like,humic-like and tyrosine-like substances of DOM in sediment and soil might be the effective components promoting the Peridiniopsis sp.growth,while tryptophan-like substance of plant DOM might hinder it.Sediment and soil DOM might promote the Peridiniopsis sp.growth mainly by providing adequate organic carbon,increasing protein content,and improving photosynthesis.The findings will provide important information for the formation and control of dinoflagellate blooms in TGR.展开更多
Dissolved organic matter(DOM)in rivers plays a key role in the global carbon cycle and aquatic ecosystems,yet its spatiotemporal dynamics across complex terrains remains inadequately characterized.To address this gap,...Dissolved organic matter(DOM)in rivers plays a key role in the global carbon cycle and aquatic ecosystems,yet its spatiotemporal dynamics across complex terrains remains inadequately characterized.To address this gap,we conducted seasonal sampling along the Luan River and examined how DOM composition varies over space and time in response to environmental drivers.Using parallel factor analysis(PARAFAC),we identified two humic-like components(C1+C2,Em>380 nm)and one protein-like component(C3,Em<380 nm).DOM fluorescence intensity was lowest in winter,while C1 and C3 levels peaked in autumn and C2 in summer(p<0.05).Spatially,C1 and C3 levels were highest downstream regions,whereas C2 peaked in the midstream section(p<0.05).Microbial sources dominated DOM in spring,winter,and in both headwater and downstream areas(FI>1.9).Principal coordinates analysis(PCoA)combined with multi-response permutation process(MRPP)confirmed significant spatiotemporal differences in DOM composition(p<0.05).Random forest modeling showed humic-like components were more sensitive to environmental changes.Redundancy analysis(RDA)and Mantel tests identified temperature as the dominant seasonal driver of DOM variation(p<0.05),while dissolved total phosphorus(DTP)and nitrate nitrogen(NO_(3)^(-)-N)were the key spatial determinants.Significant correlations were also observed between NO_(3)^(-)-N and ammonium nitrogen(NH_(4)^(+)-N),as well as between DTP and DOM,suggesting shared origins and compositional linkages(p<0.05).Our findings highlight the pronounced seasonal and spatial heterogeneity of DOM in multi-terrain river systems,offering valuable insights into carbon dynamics and ecosystem functioning in river systems.展开更多
Woodchip bioreactors are an eco-friendly technology for removing nitrogen(N)pollution.However,there needs to be more clarity regarding the dissolved organicmatter(DOM)characteristics and bacterial community succession...Woodchip bioreactors are an eco-friendly technology for removing nitrogen(N)pollution.However,there needs to be more clarity regarding the dissolved organicmatter(DOM)characteristics and bacterial community succession mechanisms and their association with the N removal performance of bioreactors.The laboratory woodchip bioreactors were continuously operated for 360 days under three influent N level treatments,and the results showed that the average removal rate of TN was 45.80 g N/(m^(3)·day)when the influent N level was 100 mg N/L,which was better than 10 mg N/L and 50 mg N/L.Dynamic succession of bacterial communities in response to influent N levels and DOM characteristics was an important driver of TN removal rates.Medium to high N levels enriched a copiotroph bacterial module(Module 1)detected by network analysis,including Phenylobacterium,Xanthobacteraceae,Burkholderiaceae,Pseudomonas,and Magnetospirillaceae,carrying N-cycle related genes for denitrification and ammonia assimilation by the rapid consumption of DOM.Such a process can increase carbon limitation to stimulate local organic carbon decomposition to enrich oligotrophswith fewer N-cycle potentials(Module 2).Together,this study reveals that the compositional change ofDOMand bacterial community succession are closely related to N removal performance,providing an ecological basis for developing techniques for N-rich effluent treatment.展开更多
Dissolved organic matter(DOM)represents the largest pool of reactive carbon on the Earth and plays a crucial role in various biogeochemical processes and ecosystem functions.However,it is understudied for a global und...Dissolved organic matter(DOM)represents the largest pool of reactive carbon on the Earth and plays a crucial role in various biogeochemical processes and ecosystem functions.However,it is understudied for a global understanding of DOM molecular properties such as molecular weight,stoichiometry,and oxidation state,and the linkages among them across Earth systems.Here,a meta-analysis of 2707 sites in 204 literatures was conducted by synthesizing four representative molecular properties of DOM,i.e.,mass,double bond equivalent(DBE),modified aromaticity index(AI_(mod)),and nominal oxidation state of carbon(NOSC).By exploring H/C and O/C ratios,we examined the relationships among these DOM properties across waters and land systems,and their geographical patterns and environmental drivers.We found that,compared to land system,the mass,DBE,and AI_(mod) were all significantly higher in water systems,with river sediments exhibiting the highest values.The DOM oxidation state indicated by NOSC was greater on average in wastewater(NOSC=0.226±0.06)and marine water(NOSC=0.133±0.06)than in other habitats.Compared to waters,the mass in land system showed more strongly positive correlations with oxidation states such as NOSC and O/C,and the NOSC showed stronger relations to bioavailability properties such as DBE,AI_(mod),and H/C.Among all the properties,H/C and AI_(mod) contributed to the most variations in global DOM properties.In waters,NOSC monotonically increased towards high latitudes,while DBE and AI_(mod) showed significant hump-shaped patterns indicating peaked unsaturation and aromaticity at mid-latitudes of approximately absolute 30°–50°.The variations in DOM properties were significantly correlated with environmental factors such as annual mean temperature and pH.Collectively,we revealed the spatial distribution and environmental drivers of DOM molecular properties across Earth ecosystems,which could shed light on our comprehensive understanding of DOM characteristics and its dynamics.展开更多
The abiotic oxidation of divalentmanganese(Mn(Ⅱ))and the formation of Mn oxides are important geochemical processes,which control the mobility and availability of Mn as well as element cycling and pollutant behavior ...The abiotic oxidation of divalentmanganese(Mn(Ⅱ))and the formation of Mn oxides are important geochemical processes,which control the mobility and availability of Mn as well as element cycling and pollutant behavior in soils.It was found that iron(oxyhydr)oxides can catalyze Mn(Ⅱ)oxidation,but the effects of the coexisting dissolved organic matter(DOM)molecules on the catalysis of different iron(oxyhydr)oxides for Mn(Ⅱ)oxidation are poorly understood.Herein,we investigated Mn(Ⅱ)oxidation under the impacts of the interactions between iron(oxyhydr)oxides(i.e.,ferrihydrite,goethite and hematite)and DOM molecules.Simultaneously,we elucidated the variations of DOM composition and properties.Our results indicated that the catalysis of iron(oxyhydr)oxides for Mn(Ⅱ)oxidation was significantly inhibited by DOM.Moreover,DOM had less inhibiting effect on the catalysis of ferrihydrite for Mn(Ⅱ)oxidation and the formation of Mn oxides(e.g.,hausmannite and buserite)relative to goethite and hematite,whichwas partially because of the higher electron transfer capacities of ferrihydrite.Meanwhile,DOM molecules with high nominal oxidation state of carbon(NOSC),molecular weight,unsaturation and aromaticity were selectively adsorbed and oxidized by Mn oxides,including the oxygenated phenols and polyphenols.The newly formed molecules mainly belonged to phenols depleted of oxygen and aliphatics.Furthermore,NOSC was a key molecular characteristic for controlling DOM composition during DOM adsorption and oxidation by Mn oxides when iron minerals were present.Overall,our research contributes to understanding Mn(Ⅱ)oxidation mechanisms under heterogeneous systems and behaviors of DOM molecules in the environment.展开更多
By using the ultraviolet absorption spectrum,the fluorescence spectrum and three dimensional fluorescence spectra,the composition of dissolved organic matter(DOM) and the humification degree,etc.in the sediment of hyd...By using the ultraviolet absorption spectrum,the fluorescence spectrum and three dimensional fluorescence spectra,the composition of dissolved organic matter(DOM) and the humification degree,etc.in the sediment of hydro-fluctuation belt(Yunyang part) were analyzed.The relationship between the test parameters and the pollution degree in the region was discussed.The research results of UV spectrum data E3/E4 showed that in 4 sampling sites which included Huangshi Town,Gaoyang Town,Shuangjiang Town and Quma Town,the humification degree in the sediment of hydro-fluctuation belt in Shuangjiang Town sampling site was lower,and the aromaticity was smaller.Moreover,the effect of human factor was comparatively smaller.The fluorescence index value which represented the source of humus in DOM was 1.62-1.88.It showed that the biological and terrestrial source both existed.Three dimensional spectra results showed that the pollution degrees in 4 sampling sites were all smaller,and some prevention measures should be taken early.展开更多
With XAD-series and ion exchange resins, dissolved organic matter （DOM） from Lake Hongfeng in Southwestern China Plateau was isolated into 6 fractions, i.e., humic acid （HA）, fulvic acid （FA）, hydrophobic neutra...With XAD-series and ion exchange resins, dissolved organic matter （DOM） from Lake Hongfeng in Southwestern China Plateau was isolated into 6 fractions, i.e., humic acid （HA）, fulvic acid （FA）, hydrophobic neutrals （HON）, hydrophilic acids （HIA）, hydrophilic bases （HIB） and hydrophilic neutrals （HIN）. Those fractions were characterized by high performance size exclusion chromatography, fluorescence spectroscopy and UV absorbance. Among the 6 fractions, FA was predominant and accounted for 51% of the total DOM. The weight-average （Mw） and number-averaged （Mn） molecular weight of these fractions ranged from 1688 to 2355 Da and from 1338 to 1928 Da, respectively. A strong correlation was observed between specific UV absorbance at 280 nm, E2/E3 （absorbance at 250 nm to 365 nm）, and the molecular weight for DOM fractions. UV-Vis fulvic-like fluorescence peaks were found in all fractions. Proteinlike fluorescence peaks existed in HON may indicate that microbial activity was severely in Lake Hongfeng. There was a significant relationship between fluorescence intensities and specific UV absorbance at 254 nm for those DOM fractions, suggesting their similar luminescence characteristics. The values of fluorescence index （f450/500） indicated that hydrophobic fractions may derive from terrestrial sources, and the hydrophilic fractions from microbial and terrestrial origins. Those results suggest that there were inter-relationships between molecular weight, fluorescence and absorbance characteristics, and also subtle consistencies between the hydrophilic and hydrophobic properties and the sources for these 6 fractions from Lake Hongfeng.展开更多
The main objective of the study was to investigate the characteristics of dissolved organic matter （DOM） in leachate with different landfill ages through the chemical, spectroscopic, and elemental analysis. Humic ac...The main objective of the study was to investigate the characteristics of dissolved organic matter （DOM） in leachate with different landfill ages through the chemical, spectroscopic, and elemental analysis. Humic acid （HA）, fulvic acid （FA）, and hydrophilic （HyI） fractions were isolated and purified by the XAD-8 resin combined with the cation exchange resin method. The analytical results of fluorescence excitation-emission matrix spectroscopy （EEMs） revealed that the fluorescence peaks were protein-like fluorescence for young landfill leachate, while the fluorescence peaks for medium and old landfill leachate were humic-like and fulvic-like fluorescence, respectively. Elemental analysis showed that carbon, hydrogen, and nitrogen content decreased with landfill age, while the oxygen content increased. Moreover, the nitrogen content in these isolated fractions followed： HA 〉 HyI 〉 FA. The results of elemental analysis, FT-IR, and fluorescence EEMs also confirmed that aromatic carbons and portions of aliphatic functional groups were more abundant in leachate samples with increasing landfill age.展开更多
Wastewater dissolved organic matter （DOM） from different processing stages of a sewage treatment plant in Xiamen was characterized using fluorescence and absorption spectroscopy. Parallel factor analysis modeling of...Wastewater dissolved organic matter （DOM） from different processing stages of a sewage treatment plant in Xiamen was characterized using fluorescence and absorption spectroscopy. Parallel factor analysis modeling of excitation-emission matrix spectra revealed five fluorescent components occurring in sewage DOM： one protein-like （C1）, three humic-like （C2, C4 and C5） and one xenobiotic-like （C3） components. During the aerated grit chamber and primary sedimentation tank stage, there was only a slight decrease in fluorescence intensity and the absorption coefficient at 350 nm （a 350 ）. During the second aeration stage, high concentration of protein-like and short-wavelength-excited humic-like components were significantly degraded accompanied by significant loss of DOC （80%） and a 350 （30%）, indicating that C1 and C2 were the dominant constituents of sewage DOM. As a result, long-wavelength- excited C4 and C5 became the dominant humic-like components and the DOM molecular size inferred from the variation of spectral slope S （300–650 nm） and specific absorption （a 280 /DOC） increased. Combination use of F max of C1 and the ratio of C1/C5, or a 350 may provide a quantitative indication for the relative amount of raw or treated sewage in aquatic environment.展开更多
Fly ash was used as a low-cost adsorbent for removing dissolved organic matter （DOM） in secondary effluent. Batch experiments were conducted under various adsorbent dosages, pH, contact time, temperatures and DOM fr...Fly ash was used as a low-cost adsorbent for removing dissolved organic matter （DOM） in secondary effluent. Batch experiments were conducted under various adsorbent dosages, pH, contact time, temperatures and DOM fractional characteristics. Under the optimum conditions of fly ash dosage of 15 g/L, temperature of 303 K and contact time of 180 min, a removal of 22.5% of the dissolved organic carbon （DOC）, 23.7% of UV-254, 25.9% of the trihalomethanes precursors in secondary effluent was obtained. The adsorption of DOM fractions onto fly ash all followed the pseudo second-order kinetic model, and the hydrophilic fraction adsorption by fly ash also fitted the intraparticle diffusion model quite well. Freundlich and Langmuir models were applicable to the fly ash adsorption and their constants were evaluated. The maximum adsorption capacities of the adsorptions revealed that fly ash was more effective in adsorbing hydrophilic fraction than the acidic fractions. Structure changes of the DOM fractions after fly ash adsorption were also characterized via spectrum analyzing. Those mechanisms presented critical step toward improved efficiencies of fly ash adsorption via further surface-modification.展开更多
This study investigated the potential role of soil colloids and dissolved organic matter(DOM)in transporting Cd through in situ undisturbed paddy soil monoliths.Brilliant Blue was used as a tracer to assess the effect...This study investigated the potential role of soil colloids and dissolved organic matter(DOM)in transporting Cd through in situ undisturbed paddy soil monoliths.Brilliant Blue was used as a tracer to assess the effect of preferential flow on Cd down migration.Experimental results showed that deep penetration of Cd and Brilliant Blue into the soil profile took place due to the preferential flow through macropores,mainly earthworm channels,with much of chemicals thus bypassing the soil matrix.Dye tracer and Cd distribution within the soil matrix was fairly restricted to several centimeters.Colloid restrained the migration of both dye and Cd in the matrix and preferential flow area.DOM facilitated the transport of Cd and Brilliant Blue in matrix and macropores by about 10 cm over that of the control.Pearson's is correlation analysis revealed strong associations between Brilliant Blue concentrations,exchangeable Cd and total Cd concentrations in three studied plots indicating that they had taken the same preferential flow pathway.展开更多
Effects of dissolved organic matter (DOM) on adsorption and desorption of Hg were investigated in two kinds of soils, Xanthi-Udic Ferralosols (XUF) and Typic Purpli-Udic Cambosols (TPUC). The DOM was obtained from hum...Effects of dissolved organic matter (DOM) on adsorption and desorption of Hg were investigated in two kinds of soils, Xanthi-Udic Ferralosols (XUF) and Typic Purpli-Udic Cambosols (TPUC). The DOM was obtained from humus soil (DOMH), rice straw (DOMR), and pig manure (DOMP). The presence of DOM obviously reduced Hg maximum adsorption capacity with up to 40% decreases over the control, being an order of DOMH (250.00 mg/kg)< DOMR (303.03 mg/kg) < DOMP (322.58 mg/kg) < CK (control 416.67 mg/kg) for the...展开更多
基金supported by the National Natural Science Foundation of China(Nos.42307524,and 51879103).
文摘China’s lakes are plagued by cadmium(Cd)pollution.Dissolved organic matter(DOM)significantly regulates Cd(II)transport properties at the sediment-water interface.Understanding the effects of different DOM components on the transportation properties of Cd(II)at the sediment-water interface is essential.In this study,typical DOM from different sources was selected to study Cd(II)mobility at the sediment-water interface.Results showed that terrestrial-derived DOM(fulvic acids,FA)and autochthonous-derived DOM(α-amylase,B1)inhibit Cd(II)sequestration by sediments(42.5%and 5.8%,respectively),while anthropogenic-derived DOM(sodium dodecyl benzene sulfonate,SDBS)increased the Cd(II)adsorption capacity by sediments by 2.8%.Fluorescence quenching coupling with parallel factor analysis(EEM-PARAFAC)was used to characterize different DOM components.The results showed that FA contains three kinds of components(C1,C3:protein-like components,C2:humic-like components);SDBS contains two kinds of components(C1,C2:protein-like components);B1 contains three kinds of components(C1,C2:protein-like components,C3:humic-like components).Three complex reaction modelswere used to characterize the ability of Cd(II)complex with DOM,and it was found that the humic-like component could hardly be complex with Cd(II).Accordingly,humic-like components compete for Cd(II)adsorption sites on the sediment surface and inhibit Cd(II)adsorption fromsediments.Fourier transform infrared spectroscopy(FTIR)of the sediment surface before and after Cd(II)addition was analyzed and proved the competitive adsorption theory.This study provides a better understanding of the Cd(II)mobilization behavior at the sediment-water interface and indicates that the input of humic-like DOM will increase the bioavailability of Cd.
基金supported by the Director Fund Project provided by the Institute of Plant Nutrition,Resources and Environment,Beijing Academy of Agriculture and Forestry Sciences(No.YZS202101)the Youth Fund Project provided by Beijing Academy of Agriculture and Forestry Sciences(No.QNJJ202125)China Agriculture Research System of MOF and MARA.
文摘The dissolved organic matter(DOM)with high mobility and reactivity plays a crucial role in soil.In this study,the characteristics and phytotoxicity ofDOMreleased fromthe hydrochars prepared from different feedstocks(cowmanure,corn stalk and Myriophyllum aquaticum)under three hydrothermal carbonization(HTC)temperatures(180,200 and 220°C)were evaluated.The results showed that the hydrochars had high dissolved organic carbon content(20.15 to 37.65 mg/g)and its content showed a gradual reduction as HTC temperature increased.Three fluorescent components including mixed substance of fulvic acid-like and humic acid-like substances(C1,30.92%-58.32%),UVA humic acid-like substance(C2,25.27%-29.94%)and protein-like substance(C3,11.74%-41.92%)were identified in hydrochar DOM by excitation emission matrix spectra coupled with parallel factor analysis.High HTC temperature increased the relative proportion of aromatic substances(C1+C2)and humification degree of hydrochar DOM from cow manure,while it presented adverse effects on the hydrochar DOM from corn stalk and Myriophyllum.aquaticum.The principal component analysis suggested that feedstock type and HTC temperature posed significant effects on the characteristics of hydrochar DOM.Additionally,seed germination test of all hydrochar DOM demonstrated that the root length was reduced by 8.88%-26.43%in contrast with control,and the germination index values were 73.57%-91.12%.These findings provided new insights into the potential environmental effects for hydrochar application in soil.
基金supported by the National Key Research and Development Program of China(No.2022YFC3204000).
文摘Lake Baiyangdian is one of China’s largest macrophyte-derived lakes,facing severe challenges related to water quality maintenance and eutrophication prevention.Dissolved organic matter(DOM)was a huge carbon pool and its abundance,property,and transformation played important roles in the biogeochemical cycle and energy flow in lake ecosystems.In this study,Lake Baiyangdian was divided into four distinct areas:Unartificial Area(UA),Village Area(VA),Tourism Area(TA),and Breeding Area(BA).We examined the diversity of DOM properties and sources across these functional areas.Our findings reveal that DOM in this lake is predominantly composed of protein-like substances,as determined by excitation-emission matrix and parallel factor analysis(EEM-PARAFAC).Notably,the exogenous tyrosine-like component C1 showed a stronger presence in VA and BA compared to UA and TA.Ultrahigh-resolution mass spectrometry(FT-ICR MS)unveiled a similar DOM molecular composition pattern across different functional areas due to the high relative abundances of lignan compounds,suggesting that macrophytes significantly influence the material structure of DOM.DOM properties exhibited specific associations with water quality indicators in various functional areas,as indicated by the Mantel test.The connections between DOM properties and NO_(3)-N andNH3-Nwere more pronounced in VA and BA than in UA and TA.Our results underscore the viability of using DOM as an indicator for more precise and scientific water quality management.
基金The National Natural Science Foundation of China under contract Nos 42276255,41976228,42176227 and 42306262the National Polar Special Program under contract Nos IRASCC 01-01-02,IRASCC 02-02-03,and IRASCC 02-02-05the Scientific Research Fund of the Second Institute of Oceanography under contract Nos JG2211 and JG2212.
文摘Dissolved organic carbon(DOC)constitutes the largest organic carbon reservoir in the ocean and plays a vital role in the oceanic carbon cycle.However,research on DOC in Antarctica has been limited,largely due to difficulties in sample collection.In this study,we investigate chromophoric dissolved organic matter(CDOM)in the Cosmonaut Sea and Cooperation Sea,Antarctica.The relative abundances of CDOM,as indicated by the absorption coefficient at 254 nm(a_(254)),exhibit significant variability,ranging from 1.29 m^(-1) to 8.37 m^(-1).The diatom species B is the primary contributor to CDOM in the region influenced by the Antarctic slope current.Using excitation-emission matrix fluorescence spectroscopy coupled with parallel factor analysis(EEM-PARAFAC),we identify three fluorescent components:one protein-like component(C1)and two humic-like components(C2 and C3).Our findings indicate that strong microbial activity in the euphotic zones of the Cosmonaut Sea and Cooperation Sea serves as a primary pathway for the removal of protein-like substances while also acting as a significant source of humic-like substances.Microbial degradation likely accounts for the decoupling of the vertical distribution of DOC and phytoplankton.Furthermore,the intrusion of modified circumpolar deep water(mCDW)into the euphotic zones of open ocean areas influences the distribution of CDOM at depths shallower than 200 m.These results have important implications for enhancing our understanding of the dynamics of CDOM and DOC in east Antarctica,as well as for improving assessments of the carbon cycle.
基金supported by the National Natural Science Foundation of China(No.42307090)the Open Subject from State Environmental Protection Key Laboratory of Aquatic Ecosystem Health in theMiddle and Lower Reaches of Yangtze River(No.AEHKF2023008).
文摘The copper complexing of dissolved organic matter released from hydrochar(HDOM)affects the former’s environmental behavior.In this study,how hydrothermal temperatures(180,220 and 260℃)influence the molecular-level constitutions and Cu(II)binding features of HDOM were elucidated via fourier transform ion cyclotron resonance mass spectrometry and multi-spectroscopic analysis.The findings demonstrated that the almost HDOM molecules had the traits of lower polarity and higher hydrophobicity.As the hydrothermal temperature increased,the molecules with particularly high relative strength gradually disappeared,average molecular weight,percentages of CHON and aliphatic compounds of HDOM reduced while the percentages of CHO and aromatic compounds increased.In general,the fluorescence quenching of Cu(II)weakened as hydrothermal temperature rose and the Cu(II)binding stability constants of fluorophores in HDOM were 4.50–5.31.In addition,the Cu(II) binding order of fluorophores in HDOM showed temperature heterogeneities, andpolysaccharides or aromatic rings of non-fluorescent substances had the fastest responsesto Cu(II) binding. Generally, fluorescent components tend to bind Cu(II) at relatively traceconcentrations (0–40 μmol/L), whereas non-fluorescent substances tend to the bind Cu(II)at relatively higher concentrations (50–100 μmol/L). This study contributed to the predictionof the potential environmental behaviors and risks of Cu(II) at the molecular level afterhydrochar application.
基金Project(2020YFC1908802)supported by the National Key Research and Development Project of China。
文摘Biochar-derived dissolved organic matter(BCDOM),an essential component of biochar,plays a vital role in regulating the physicochemical and biological properties of soils during biochar application.However,the influence of BCDOM on soil organisms has not been clearly explained.Hence,this review aims to discuss the factors affecting BCDOM and its interaction with soil substances including organic pollutants,heavy metals,and microorganisms.Results displayed that the quantity of BCDOM ranges from 0.17 to 37.03 mg/g,which was influenced by feedstock,preparation methods of biochar,and extraction methods.With the decrease in lignin content of feedstocks,carbonization temperature,and acidity of extraction solution,the content of BCDOM increased.Through complexation and adsorption,protein-like components in BCDOM interact with heavy metals,promoting the adsorption and immobilization of heavy metals onto biochar.Furthermore,BCDOM enhances the adsorption of organic pollutants by biochar throughπ−πinteractions,hydrogen bonding,and redox processes.More importantly,BCDOM promotes plant growth by enhancing microbial activities,providing nutrients,and improving soil properties.However,the transport and fate of BCDOM in soil have not been well studied,and more researches are needed to explore the interaction mechanisms between BCDOM and soil organisms.
基金supported by grants from the Sichuan Natural Science Foundation Project(2024NSFSC0793)Dagu Glacier Research Institute(Center)project of Aba Normal College(AS-DTPT 2023072)the support of Youth Innovation Promotion Association CAS(2021429)。
文摘Temperate glaciers are highly sensitive to variations in climate and environmental conditions.Investigating the chemical composition of dissolved organic matter(DOM)in glacier snow is essential for understanding its characteristics,sources,and transformation processes within glacial systems.This study aims to elucidate the chemical composition and transformation of DOM in snow environment by analyzing samples collected from snowpits,surface snow,and snow meltwater at Baishui Glacier No.1 on Mt.Yulong during May and June.The average concentrations of dissolved organic carbon(DOC)in snow meltwater collected in May(1.63±0.63 mg L^(-1))and June(1.54±0.35 mg L^(-1))were both significantly higher than those measured in snowpit samples from May(0.74±0.10 mg L^(-1))and June(0.54±0.10 mg L^(-1)),as well as in surface snow samples from May(0.65±0.31 mg L^(-1))and June(0.69±0.30 mg L^(-1)).However,the concentrations of DOC in samples from the same category did not show significant variation between May and June.Using excitation-emission matrix(EEM)fluorescence spectroscopy coupled with parallel factor(PARAFAC)analysis,three protein-like components(C_(1),C_(2),and C_(3))and one humic-like component(C_(4))were identified.The protein-like components accounted for more than 75%of the total DOM in all snow samples,indicating that the fluorescent DOM originated from biological or microbial sources.Significant differences in the relative proportions of the four fluorescent components were observed between snowpit samples from May and June,whereas no significant variations were noted in the other sample types.Furthermore,a clear transformation from protein-like to humic-like components was observed during the transition from snowpits to snow meltwater.Further analysis using Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS)revealed that DOM in these snow samples was predominantly composed of aliphatic and peptide-like compounds(30.9%-50.9%),suggesting a substantial microbial contribution.FT-ICR MS data also demonstrated compositional shifts in DOM among snowpit,surface snow,and meltwater samples.Specifically,aliphatic and peptide-like compounds were progressively transformed into unsaturated compounds with high oxygen content,polyphenolic species,and condensed aromatic compounds during their transition from snowpit to meltwater.Therefore,the relative contribution of terrestrial-derived DOM increased during the transition from snowpit to snowmelt.Furthermore,an increase in heteroatom content in the DOM of meltwater samples indicated continuous chemical transformations likely driven by biological activity and/or photochemical processes during snowmelt and leaching.
基金supported by Fujian Provincial Natural Science Foundation of China(Nos.2023J01456 and 2021J01626)the National Natural Science Foundation of China(No.41976042)the Oceanic Interdisciplinary Program of Shanghai Jiao Tong University(Nos.SL2022ZD207 and SL2023MS019).
文摘Dissolved organic matter(DOM)is very important in aquatic environments,yet it is challenging to characterize DOM as a highly complex mixture of thousands of molecules,and the knowledge of the effects of different degradation processes on different molecules remains limited.This study examined the distribution and degradation of DOM in a large subtropical river using optical techniques and Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR-MS).At the molecular level,DOM was mainly composed of CHO and lignin-like compounds,which was related to the dominance of forestland in the watershed and resulted in a low biological lability index(MLBL).The modified aromaticity index(AI_(mod)),unsaturation degree(DBE),and humic content(HIX)decreased while MLBL,H/C,absorption spectral slope(S_(275–295)),and biological index(BIX)increased in the estuarine zone due to the increasing autochthonous contribution.Photo-and microbial degradation resulted in a similar decrease in the bulk dissolved organic carbon,while they showed opposite effects on the DOM composition.Photo-degradation removed all fluorescent components and decreased molecular weight,HIX,AI_(mod),DBE,%CHO,%lignin-like,%tannin-like,and%condensed aromatic-like compounds.In contrast,bio-degradation preferentially consumed lipid-like,protein-like,and carbohydrate-like compounds,with increases in%ligninlike,%tannin-like,%condensed aromatic-like compounds,and humic-like fluorescent components.Overall,the application of ultra-high resolutionmass spectrometry provided valuable insights into the composition and behavior of DOM at themolecular level and revealed the contrasting effects of photo-and microbial degradation on different compounds.These results have implications for better understanding the composition and transformation of aquatic DOM.
基金supported by the National Key Research and Development Program(No.2021YFC3201003)。
文摘Spring dinoflagellate blooms are always severe in the Three Gorges Reservoir(TGR),China,threatening water ecological health.Many dinoflagellates are capable of mixotrophism,yet the influence of dissolved organic matter(DOM)on their growth and blooms in spring remains unclear.This study characterized the source and composition of DOM from sediment,soil,and plant,and assessed their effects on the growth of bloom-forming algal species(Peridiniopsis sp.and Microcystis aeruginosa)under different temperatures.The results showed that sediment and soil DOM promoted Peridiniopsis sp.growth,plant DOM slightly inhibited it.However,DOM had no significant effect on M.aeruginosa growth.The promotion of sediment and soil DOM on Peridiniopsis sp.growth was higher at 15℃and 20℃ than at 25℃.Moreover,the effect of DOM on Peridiniopsis sp.growth was more significant than that of high nitrogen and phosphorus.Fulvic acid-like,humic-like and tyrosine-like substances of DOM in sediment and soil might be the effective components promoting the Peridiniopsis sp.growth,while tryptophan-like substance of plant DOM might hinder it.Sediment and soil DOM might promote the Peridiniopsis sp.growth mainly by providing adequate organic carbon,increasing protein content,and improving photosynthesis.The findings will provide important information for the formation and control of dinoflagellate blooms in TGR.
基金Basic Research Project of Universities in Hebei Province,Affiliated with Shijiazhuang City,Grant/Award Number:241791187ANatural Science Foundation of Hebei Province,Grant/Award Number:E2024208033+1 种基金Hebei Province graduate student innovation ability training program,Grant/Award Number:CXZZSS2025068Hebei Provincial Key Research Projects,Grant/Award Number:21373904D。
文摘Dissolved organic matter(DOM)in rivers plays a key role in the global carbon cycle and aquatic ecosystems,yet its spatiotemporal dynamics across complex terrains remains inadequately characterized.To address this gap,we conducted seasonal sampling along the Luan River and examined how DOM composition varies over space and time in response to environmental drivers.Using parallel factor analysis(PARAFAC),we identified two humic-like components(C1+C2,Em>380 nm)and one protein-like component(C3,Em<380 nm).DOM fluorescence intensity was lowest in winter,while C1 and C3 levels peaked in autumn and C2 in summer(p<0.05).Spatially,C1 and C3 levels were highest downstream regions,whereas C2 peaked in the midstream section(p<0.05).Microbial sources dominated DOM in spring,winter,and in both headwater and downstream areas(FI>1.9).Principal coordinates analysis(PCoA)combined with multi-response permutation process(MRPP)confirmed significant spatiotemporal differences in DOM composition(p<0.05).Random forest modeling showed humic-like components were more sensitive to environmental changes.Redundancy analysis(RDA)and Mantel tests identified temperature as the dominant seasonal driver of DOM variation(p<0.05),while dissolved total phosphorus(DTP)and nitrate nitrogen(NO_(3)^(-)-N)were the key spatial determinants.Significant correlations were also observed between NO_(3)^(-)-N and ammonium nitrogen(NH_(4)^(+)-N),as well as between DTP and DOM,suggesting shared origins and compositional linkages(p<0.05).Our findings highlight the pronounced seasonal and spatial heterogeneity of DOM in multi-terrain river systems,offering valuable insights into carbon dynamics and ecosystem functioning in river systems.
基金supported by the National Key Research and Development Program of China (Nos.2018YFE0105600 and 2020YFC1806803)the New Zealand MBIE Catalyst Fund (No.92846082).
文摘Woodchip bioreactors are an eco-friendly technology for removing nitrogen(N)pollution.However,there needs to be more clarity regarding the dissolved organicmatter(DOM)characteristics and bacterial community succession mechanisms and their association with the N removal performance of bioreactors.The laboratory woodchip bioreactors were continuously operated for 360 days under three influent N level treatments,and the results showed that the average removal rate of TN was 45.80 g N/(m^(3)·day)when the influent N level was 100 mg N/L,which was better than 10 mg N/L and 50 mg N/L.Dynamic succession of bacterial communities in response to influent N levels and DOM characteristics was an important driver of TN removal rates.Medium to high N levels enriched a copiotroph bacterial module(Module 1)detected by network analysis,including Phenylobacterium,Xanthobacteraceae,Burkholderiaceae,Pseudomonas,and Magnetospirillaceae,carrying N-cycle related genes for denitrification and ammonia assimilation by the rapid consumption of DOM.Such a process can increase carbon limitation to stimulate local organic carbon decomposition to enrich oligotrophswith fewer N-cycle potentials(Module 2).Together,this study reveals that the compositional change ofDOMand bacterial community succession are closely related to N removal performance,providing an ecological basis for developing techniques for N-rich effluent treatment.
基金supported by the National Natural Science Foundation of China(Nos.U24A20578,42225708,42377122,92251304)the Basic Research Program of Jiangsu Province(No.BK20240111)+1 种基金the Key Laboratory of Lake and Watershed Science for Water Security(No.NKL2023-QN04)the Science and Technology Planning Project of Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences(No.NIGLAS2022GS09).
文摘Dissolved organic matter(DOM)represents the largest pool of reactive carbon on the Earth and plays a crucial role in various biogeochemical processes and ecosystem functions.However,it is understudied for a global understanding of DOM molecular properties such as molecular weight,stoichiometry,and oxidation state,and the linkages among them across Earth systems.Here,a meta-analysis of 2707 sites in 204 literatures was conducted by synthesizing four representative molecular properties of DOM,i.e.,mass,double bond equivalent(DBE),modified aromaticity index(AI_(mod)),and nominal oxidation state of carbon(NOSC).By exploring H/C and O/C ratios,we examined the relationships among these DOM properties across waters and land systems,and their geographical patterns and environmental drivers.We found that,compared to land system,the mass,DBE,and AI_(mod) were all significantly higher in water systems,with river sediments exhibiting the highest values.The DOM oxidation state indicated by NOSC was greater on average in wastewater(NOSC=0.226±0.06)and marine water(NOSC=0.133±0.06)than in other habitats.Compared to waters,the mass in land system showed more strongly positive correlations with oxidation states such as NOSC and O/C,and the NOSC showed stronger relations to bioavailability properties such as DBE,AI_(mod),and H/C.Among all the properties,H/C and AI_(mod) contributed to the most variations in global DOM properties.In waters,NOSC monotonically increased towards high latitudes,while DBE and AI_(mod) showed significant hump-shaped patterns indicating peaked unsaturation and aromaticity at mid-latitudes of approximately absolute 30°–50°.The variations in DOM properties were significantly correlated with environmental factors such as annual mean temperature and pH.Collectively,we revealed the spatial distribution and environmental drivers of DOM molecular properties across Earth ecosystems,which could shed light on our comprehensive understanding of DOM characteristics and its dynamics.
基金supported by the National Natural Science Foundation of China(Nos.42207309 and 22306087)the Natural Science Foundation of Hunan Province(Nos.2022JJ40369 and 2023JJ40547)the Program for Education Department of Hunan Province,China(No.21B0405).
文摘The abiotic oxidation of divalentmanganese(Mn(Ⅱ))and the formation of Mn oxides are important geochemical processes,which control the mobility and availability of Mn as well as element cycling and pollutant behavior in soils.It was found that iron(oxyhydr)oxides can catalyze Mn(Ⅱ)oxidation,but the effects of the coexisting dissolved organic matter(DOM)molecules on the catalysis of different iron(oxyhydr)oxides for Mn(Ⅱ)oxidation are poorly understood.Herein,we investigated Mn(Ⅱ)oxidation under the impacts of the interactions between iron(oxyhydr)oxides(i.e.,ferrihydrite,goethite and hematite)and DOM molecules.Simultaneously,we elucidated the variations of DOM composition and properties.Our results indicated that the catalysis of iron(oxyhydr)oxides for Mn(Ⅱ)oxidation was significantly inhibited by DOM.Moreover,DOM had less inhibiting effect on the catalysis of ferrihydrite for Mn(Ⅱ)oxidation and the formation of Mn oxides(e.g.,hausmannite and buserite)relative to goethite and hematite,whichwas partially because of the higher electron transfer capacities of ferrihydrite.Meanwhile,DOM molecules with high nominal oxidation state of carbon(NOSC),molecular weight,unsaturation and aromaticity were selectively adsorbed and oxidized by Mn oxides,including the oxygenated phenols and polyphenols.The newly formed molecules mainly belonged to phenols depleted of oxygen and aliphatics.Furthermore,NOSC was a key molecular characteristic for controlling DOM composition during DOM adsorption and oxidation by Mn oxides when iron minerals were present.Overall,our research contributes to understanding Mn(Ⅱ)oxidation mechanisms under heterogeneous systems and behaviors of DOM molecules in the environment.
基金Supported by Talent Introduction Talent Plan of Chongqing ThreeGorge University(2007-SXXYRC-006)Accented Term of ChongqingThree Gorge University(10ZD-14)+1 种基金Special Term of National Water Body Pollution Control and Treatment Major Project(2009ZX07104-003-02)Special Term of National Science and Technology Supportm Plan Major Project(2008BAD98B04)
文摘By using the ultraviolet absorption spectrum,the fluorescence spectrum and three dimensional fluorescence spectra,the composition of dissolved organic matter(DOM) and the humification degree,etc.in the sediment of hydro-fluctuation belt(Yunyang part) were analyzed.The relationship between the test parameters and the pollution degree in the region was discussed.The research results of UV spectrum data E3/E4 showed that in 4 sampling sites which included Huangshi Town,Gaoyang Town,Shuangjiang Town and Quma Town,the humification degree in the sediment of hydro-fluctuation belt in Shuangjiang Town sampling site was lower,and the aromaticity was smaller.Moreover,the effect of human factor was comparatively smaller.The fluorescence index value which represented the source of humus in DOM was 1.62-1.88.It showed that the biological and terrestrial source both existed.Three dimensional spectra results showed that the pollution degrees in 4 sampling sites were all smaller,and some prevention measures should be taken early.
基金supported by the China’s Na-tional Basic Research Program (No. 2008CB418200)the National Knowledge Innovation Program of Chinese Academy of Sciences (No. kzcx2-yw-102)the Nation-al Natural Science Foundation of China (No. U0833603,40873079, 40703022).
文摘With XAD-series and ion exchange resins, dissolved organic matter （DOM） from Lake Hongfeng in Southwestern China Plateau was isolated into 6 fractions, i.e., humic acid （HA）, fulvic acid （FA）, hydrophobic neutrals （HON）, hydrophilic acids （HIA）, hydrophilic bases （HIB） and hydrophilic neutrals （HIN）. Those fractions were characterized by high performance size exclusion chromatography, fluorescence spectroscopy and UV absorbance. Among the 6 fractions, FA was predominant and accounted for 51% of the total DOM. The weight-average （Mw） and number-averaged （Mn） molecular weight of these fractions ranged from 1688 to 2355 Da and from 1338 to 1928 Da, respectively. A strong correlation was observed between specific UV absorbance at 280 nm, E2/E3 （absorbance at 250 nm to 365 nm）, and the molecular weight for DOM fractions. UV-Vis fulvic-like fluorescence peaks were found in all fractions. Proteinlike fluorescence peaks existed in HON may indicate that microbial activity was severely in Lake Hongfeng. There was a significant relationship between fluorescence intensities and specific UV absorbance at 254 nm for those DOM fractions, suggesting their similar luminescence characteristics. The values of fluorescence index （f450/500） indicated that hydrophobic fractions may derive from terrestrial sources, and the hydrophilic fractions from microbial and terrestrial origins. Those results suggest that there were inter-relationships between molecular weight, fluorescence and absorbance characteristics, and also subtle consistencies between the hydrophilic and hydrophobic properties and the sources for these 6 fractions from Lake Hongfeng.
文摘The main objective of the study was to investigate the characteristics of dissolved organic matter （DOM） in leachate with different landfill ages through the chemical, spectroscopic, and elemental analysis. Humic acid （HA）, fulvic acid （FA）, and hydrophilic （HyI） fractions were isolated and purified by the XAD-8 resin combined with the cation exchange resin method. The analytical results of fluorescence excitation-emission matrix spectroscopy （EEMs） revealed that the fluorescence peaks were protein-like fluorescence for young landfill leachate, while the fluorescence peaks for medium and old landfill leachate were humic-like and fulvic-like fluorescence, respectively. Elemental analysis showed that carbon, hydrogen, and nitrogen content decreased with landfill age, while the oxygen content increased. Moreover, the nitrogen content in these isolated fractions followed： HA 〉 HyI 〉 FA. The results of elemental analysis, FT-IR, and fluorescence EEMs also confirmed that aromatic carbons and portions of aliphatic functional groups were more abundant in leachate samples with increasing landfill age.
基金supported by the National Natural Science Foundation of China(No.40776041,40676046)the National High Technology Research and Development Program of China(No.2007AA091704)the Program for New Century Excellent Talents in Fujian Province University
文摘Wastewater dissolved organic matter （DOM） from different processing stages of a sewage treatment plant in Xiamen was characterized using fluorescence and absorption spectroscopy. Parallel factor analysis modeling of excitation-emission matrix spectra revealed five fluorescent components occurring in sewage DOM： one protein-like （C1）, three humic-like （C2, C4 and C5） and one xenobiotic-like （C3） components. During the aerated grit chamber and primary sedimentation tank stage, there was only a slight decrease in fluorescence intensity and the absorption coefficient at 350 nm （a 350 ）. During the second aeration stage, high concentration of protein-like and short-wavelength-excited humic-like components were significantly degraded accompanied by significant loss of DOC （80%） and a 350 （30%）, indicating that C1 and C2 were the dominant constituents of sewage DOM. As a result, long-wavelength- excited C4 and C5 became the dominant humic-like components and the DOM molecular size inferred from the variation of spectral slope S （300–650 nm） and specific absorption （a 280 /DOC） increased. Combination use of F max of C1 and the ratio of C1/C5, or a 350 may provide a quantitative indication for the relative amount of raw or treated sewage in aquatic environment.
基金supported by the National Nature Science Foundation of China (National Creative Research Groups)(No. 50821002)the Key Scientific and Technological Project of National Water Pollution Control and Management (No. 2009ZX07317-008)the Scientific and Technological Innovation Research Fund of Harbin (No.2010RFQXN111)
文摘Fly ash was used as a low-cost adsorbent for removing dissolved organic matter （DOM） in secondary effluent. Batch experiments were conducted under various adsorbent dosages, pH, contact time, temperatures and DOM fractional characteristics. Under the optimum conditions of fly ash dosage of 15 g/L, temperature of 303 K and contact time of 180 min, a removal of 22.5% of the dissolved organic carbon （DOC）, 23.7% of UV-254, 25.9% of the trihalomethanes precursors in secondary effluent was obtained. The adsorption of DOM fractions onto fly ash all followed the pseudo second-order kinetic model, and the hydrophilic fraction adsorption by fly ash also fitted the intraparticle diffusion model quite well. Freundlich and Langmuir models were applicable to the fly ash adsorption and their constants were evaluated. The maximum adsorption capacities of the adsorptions revealed that fly ash was more effective in adsorbing hydrophilic fraction than the acidic fractions. Structure changes of the DOM fractions after fly ash adsorption were also characterized via spectrum analyzing. Those mechanisms presented critical step toward improved efficiencies of fly ash adsorption via further surface-modification.
基金supported by the National Natural Science Foundation of China(No.40571073)
文摘This study investigated the potential role of soil colloids and dissolved organic matter(DOM)in transporting Cd through in situ undisturbed paddy soil monoliths.Brilliant Blue was used as a tracer to assess the effect of preferential flow on Cd down migration.Experimental results showed that deep penetration of Cd and Brilliant Blue into the soil profile took place due to the preferential flow through macropores,mainly earthworm channels,with much of chemicals thus bypassing the soil matrix.Dye tracer and Cd distribution within the soil matrix was fairly restricted to several centimeters.Colloid restrained the migration of both dye and Cd in the matrix and preferential flow area.DOM facilitated the transport of Cd and Brilliant Blue in matrix and macropores by about 10 cm over that of the control.Pearson's is correlation analysis revealed strong associations between Brilliant Blue concentrations,exchangeable Cd and total Cd concentrations in three studied plots indicating that they had taken the same preferential flow pathway.
基金the National Natural Sci-ence Foundation of China (No. 40673063, 40573065)
文摘Effects of dissolved organic matter (DOM) on adsorption and desorption of Hg were investigated in two kinds of soils, Xanthi-Udic Ferralosols (XUF) and Typic Purpli-Udic Cambosols (TPUC). The DOM was obtained from humus soil (DOMH), rice straw (DOMR), and pig manure (DOMP). The presence of DOM obviously reduced Hg maximum adsorption capacity with up to 40% decreases over the control, being an order of DOMH (250.00 mg/kg)< DOMR (303.03 mg/kg) < DOMP (322.58 mg/kg) < CK (control 416.67 mg/kg) for the...
