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1.
Aromatic sulfonates can be found in drinking water. Thus, they must have passed water treatment and survived ozonation. Degradation of aromatic sulfonates can be achieved by the UV/H2O2‐process. Since drinking water is often treated with chlorine as a disinfectant, the formation of disinfection by‐products has to be considered. Therefore, the production of AOX (on activated carbon adsorbable organic halogens) after chlorination of the sulfonates with and without preoxidation was investigated. Instead of the analysis of the individual degradation products, the determination of the sum parameter AOX was used as a fast screening method. The investigated sulfonates were: anthraquinone‐2‐sulfonate, naphthalene‐2‐sulfonate, 2‐aminonaphthalene‐1‐sulfonate, and 4,4′‐diaminostilbene‐2,2′‐disulfonate. All sulfonates containing amino groups showed high potentials of AOX formation. The preoxidation with ozone increased the potentials of AOX formation in general. Treating the sulfonates by using the UV/H2O2‐process, the formation potentials run to zero after going through a maximum value. 相似文献
2.
Degradations of reactive brilliant red X‐3B solution by both conventional UV irradiation and microwave electrodeless UV irradiation were investigated. Degradation processes were studied by UV–VIS spectrophotometry, total organic carbon (TOC), high performance capillary electrophoresis (HPCE), conductivity, pH value, and ion chromatography. The results of color removal (%) and TOC removal (%) showed that the degradation by microwave electrodeless UV irradiation was more effective than by conventional UV irradiation. The results of UV–VIS absorption spectra and HPCE analyses indicated that the degradation of reactive brilliant red X‐3B was occurred at the conjugation system first, the benzene ring and the naphthalene ring later. The reactive brilliant red X‐3B was cleaved into some new small compounds and eventually most of the organic substances were mineralized to CO2 and H2O. The results of the conductivity analysis suggested that the degradation has mainly occurred in the first 40 min of reaction. The pH value of reactive brilliant red X‐3B solution was decreased first and then was increased. The results of inorganic anions analysis hinted that many of the N, Cl, and S elements from reactive brilliant red X‐3B were still attached in organic molecules. 相似文献
3.
In this paper, size‐exclusion chromatography (SEC) was used to determine the metal concentration in different size fractions of a bog lake water. Two methods were applied: (a) preparative SEC with off‐line metal concentration analysis and (b) direct coupling of an analytical SEC system on‐line with an inductively‐coupled plasma mass spectrometer (ICP‐MS). In the preparative SEC measurements, maximum concentrations were found for different metal ions in different size fractions of the natural organic matter (NOM). Normalization of metal concentrations to dissolved organic carbon concentration (DOC) yielded two maxima in the high and in the very low molecular‐weight fractions. Whereas good recoveries were found for Al, Fe, and Ni, only 40% were obtained for Pb. This indicates that Pb formed labile complexes with NOM, and hence could strongly interact with the column material. In the experiments with the analytical SEC‐ICP‐MS system, the same trends were observed, but with even lower recoveries than in the preparative system. Sample preconcentration and storage were also investigated with respect to decrease in metal concentration. During the ultrafiltration preconcentration step Al and Fe were removed only to a small extent, whereas about half of the initial Pb was lost. This indicates that Al and Fe were mainly bound to high molecular‐weight fractions of NOM. In contrast to that, Al and in particular Fe were removed from solution more than proportionally with respect to DOC because of aggregation of the NOM during storage, whereas Pb and Ni were concentrated relative to the DOC. 相似文献
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Degradation and formation of refractory DOM by bacteria during simultaneous growth on labile substrates and persistent lake water constituents 总被引：3，自引：0，他引：3
Dr. Annette Geller 《Aquatic Sciences - Research Across Boundaries》1985,47(1):27-44
Changes in molecular size distribution associated with degradation of refractory DOM (macromolecules, apparent mol wt. ≥1500)
by 3 strains of bacteria were investigated by Sephadex G-15 gel permeation chromatography and DOC analysis of the eluates.
Macromolecules and bacteria were isolated from the same lake water sample, one taken in summer and one in winter. The decompositional
changes of the DOM fraction were compared with respect to substance- and bacterial species-specific differences, and with
respect to the action of photolysis and co-substrate supplementation. The metabolite patterns resulting from the simultaneous
growth of the bacteria on the persistent DOM fraction and the labile co-substrate, glutamic acid were analyzed. The macromolecules
differed in accessible components, and the bacteria degraded most effectively the DOM fraction of the parent lake water sample.
Photolysis was the prerequisite for the reduction of the inaccessible bulk of the macromolecules. Glutamic acid enhanced the
degradation of the macromolecules. The enhancement effect was impaired by the build up of waste products which balanced the
losses of the DOM fraction. Three formation modes of refractory metabolites could be distinguished: formation of intensely
UV absorbing small sized products which were poor in DOC during degredation of (1) the macromolecules of winter, and (2) of
glutamic acid, and formation of (3) apparent high molecular weight substances from glutamic acid in cultures containing the
macromolecules of summer which probably results from a stable linkage between the small sized metabolites of the amino acid
and the DOM fraction.
The research was supported by the Deutsche Forschungsgemeinschaft. 相似文献
6.
The degradation pathway for the oxidation of EDTA in the UV/H2O2-process was investigated. In absence of iron ions, the mineralization of EDTA is dominated by the reaction of the HO-radicals generated by the photolysis of H2O2. The organic degradation products iminodiacetate (IMDA), glycinate, oxamate, glyoxylate, oxalate and formate, and the inorganic degradation products carbon dioxide, ammonia, nitrate, nitrite, and cyanate were found. In the presence of iron ions, photolytic decarboxylation processes inside the complex get an important role during degradation, and the organic degradation products ethylenediaminetriacetate (ED3A), ethylenediaminediacetate (EDDA), ethylenediaminemonoacetate (EDMA) were also found. By combining product studies with balances of carbon and nitrogen, the degradation pathway in the UV/H2O2-process could be elucidated. The degradation of EDTA was fast (kdeg = 0.012 s–1), and no toxic degradation products were identified. Therefore, the process is well suited for the elimination of EDTA in water treatment. 相似文献
7.
A preparative method was developed to sample dissolved organic carbon (DOC) and heavy metals (Ni, Mn) from polluted surface waters. Main focus was set on the preparative production of freeze‐dried samples mainly composed of organic ligands from heavy metal complexes. First characterizations were done in the aqueous phase. Finally, freeze‐dried samples provide stable organic matter for multiple characterizations. Acid mine drainage of the former mining area of Ronneburg (Germany) hold elevated concentrations of heavy metals and low concentrations of DOC. Municipal wastewater, passing the spoil pile, held elevated concentrations of DOC and low concentrations of heavy metals. Dissolved components smaller than 0.45 μm and larger than 1 nm were concentrated by nanofiltration. Organic heavy metal complexes were isolated from this solution by size‐exclusion chromatography (SEC). Different size classes of molecules were collected from the column effluent, depending on their elution time, and were characterized by UV spectroscopy, ICP‐OES, and DOC measurements. All samples held organic heavy metal compounds with different retention times. The organic heavy metal complexes in acid mine drainage had higher retention times than complexes from municipal wastewater. Most interestingly, we found different affinities of heavy metals to different size classes of DOC. This affinity of the heavy metals differs with size and origin of the DOC. 相似文献
8.
The organic composition and organic‐inorganic interaction in paper mill sludge (PS) solvent extracts (hexane, ethyl acetate, acetone and ethanol) and humic fractions, humic acid (HA) and humin (HU) were studied by electron paramagnetic resonance spectroscopy (EPR), proton and carbon‐13 nuclear magnetic resonance spectroscopy (1H NMR; 13C NMR), Fourier‐transformed infrared spectroscopy (FTIR), and ultraviolet‐visible spectroscopy (UV‐vis). The strategy of fractionating the PS, sequentially, with organic solvents of increasing polarity is a reliable analytical procedure for humic substance sample separation because it results in more purified fractions. FTIR, 1H NMR and 13C NMR results showed that hexane extract consisted mainly of aliphatic hydrocarbon structures. Their contents in the extracts decreased as the polarity of the extracting solvent increased and the content of oxygen functional groups increased. Carboxylic and carboxylate functional groups were found in the acetone extract, and ester and ether functions were predominantly found in the ethanol extract. EPR spectra revealed some Fe3+ complexes with rhombic structure (g1 = 4.3; g2 = 9.0) in the humic fractions and in all solvent extracts, except hexane. Quasi‐octahedral Fe3+ complexes (g = 2.3; ΔHpp ≤ 400 G) were found in the HU fraction and in the acetone extract. The organic free radical content in the HA fraction was higher than the non‐fractionated PS sample and HU fraction. 相似文献
9.
The inactivation of enzymes is of great interest for many industrial applications. The effectiveness of photoinactivation of alpha‐amylase, catalase, and urease with 222 nm radiation was investigated in comparison to that at 254 nm. The enzymes were irradiated with different fluence rates of 222 nm radiation emitted by a KrCl‐excimer lamp and with 254 nm radiation produced by a low‐pressure mercury lamp. The relative activities were calculated before and after irradiation. Degradation caused by UV‐radiation was assessed by SDS‐PAGE analysis. The results clearly demonstrated that inactivation of the proteins is much more effective with the 222 nm excimer lamp compared to the 254 nm mercury lamp. Irradiation with the excimer lamp and a UV‐fluence rate of 1000 J/m2 was sufficient to reduce the relative activities of amylase and urease to 15% and that of catalase to 60%. After irradiation with 4000 J/m2, the enzyme activity was almost completely inhibited. In contrast, after irradiation with the mercury lamp with an UV‐fluence rate of 4000 J/m2, the relative activity was still above 85%. The gel patterns showed no visible degradation after irradiation at 254 nm, but a strong and unspecific degradation was obvious after treatment at 222 nm, presumably caused by cleavage of the peptide bonds. 相似文献
10.
Anomalous behaviour of specific electrical conductivity (SEC) was observed at a karst spring in Slovenia during 26 high‐flow events in an 18‐month monitoring period. A conceptual model explaining this anomalous SEC variability is presented and reproduced by numerical modelling, and the practical relevance for source protection zoning is discussed. After storm rainfall, discharge increases rapidly, which is typical for karst springs. SEC displays a first maximum during the rising limb of the spring hydrograph, followed by a minimum indicating the arrival of freshly infiltrated water, often confirmed by increased levels of total organic carbon (TOC). The anomalous behaviour starts after this SEC minimum, when SEC rises again and remains elevated during the entire high‐flow period, typically 20–40 µS/cm above the baseflow value. This is explained by variable catchment boundaries: When the water level in the aquifer rises, the catchment expands, incorporating zones of groundwater with higher SEC, caused by higher unsaturated zone thickness and subtle lithologic changes. This conceptual model has been checked by numerical investigations. A generalized finite‐difference model including high‐conductivity cells representing the conduit network (“discrete‐continuum approach”) was set up to simulate the observed behaviour of the karst system. The model reproduces the shifting groundwater divide and the nearly simultaneous increase of discharge and SEC during high‐flow periods. The observed behaviour is relevant for groundwater source protection zoning, which requires reliable delineation of catchment areas. Anomalous behaviour of SEC can point to variable catchment boundaries that can be checked by tracer tests during different hydrologic conditions. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
11.
M. Feuillade J. Feuillade V. Fiala 《Aquatic Sciences - Research Across Boundaries》1990,52(4):345-359
The effect of light intensity on the release of dissolved organic carbon during photosynthesis on NaH14CO3 was investigated using the phytoplanktonic CyanobacteriumOscillatoria rubescens. The released products were fractionated by molecular size and chemical identifications attempted using combined thin-layer electrophoresis and chromatography, and high pressure liquid chromatography.Within the range of irradiances tested (from 6 to 60 µmole m–2 sec–1), though the upper one inhibited photosynthesis ofO. rubescens, light had little effect on the quantity and composition of the excreted products. The released carbon was always lower than 3% of the incorporated carbon, and mainly composed (62 to 86%) by small molecular weight compounds. The prevailing identified compounds were amino acids which represented more than 20% of the excreted carbon. Among organic acids, glycolic acid accounted for less than 2% of the recovered radioactivity. Glucose was the only identified sugar.Abbreviations EOC
excreted organic carbon
- DOC
dissolved organic carbon
- PER
percent extracellular release
- LMW
low molecular weight
- HMW
high molecular weight
- AA
amino acids
- µmoles
m–2 sec–1 = µEinsteins m–2 sec–1 相似文献
12.
A sequential selective chemical degradation has been performed on the kerogen from the Nenjiang Formation of the southern Songliao Basin by using a series of mild chemical degradations (alkaline hydrolysis, cleavage of ether-bonds and sulfur-bonds, and ruthenium tetroxide (RuO4) oxidation). Subsequently, the GC-MS analyses are carried out on different degradation products. The results show that chemical degradations can release a great number of GC/MS-determinable biomarkers from insoluble kerogen, such as, alkaline hydrolysis products mainly comprise n-alkanes, fatty acids and alkanols; thiophene compounds are predominantly ether-bound to kerogen matrix; the products from the cleavage of sulfur-sulfur and sulfur-carbon bonds in the kerogen include fatty acids, alkanols and some n-alkanes with high carbon numbers; RuO4 oxidation products are predominantly monocarboxylic acids and α,ω-dicarboxylic acids. The distributions of main degradation products indicate that organic matter in this kerogen is predominantly derived from algae and bacteria, and that small amounts of high plant-derived organic matter are possibly combined into kerogen matrix at the late stage by sulfur bonds and other means. This study will provide an important approach for further discussing sources of organic matter in source rocks and their depositional paleoenvironments. 相似文献
13.
The purpose of the study is to gain a better understanding about the formation of THM (trihalomethanes), HAA (haloacetic acids), and AOX (adsorbable organic halogen) in river water (river Ruhr, Essen) through a chlorination kinetics approach. The effect of chlorination time and preozonation on the formation of THM, HAA, and AOX substances was studied. Preozonation can reduce the chlorine demand and the precursors for AOX and THM. THM generation was reduced further, when the ozone dosage consumed increased from 3.5 to 12.5 mg in the 1.4 L reaction vessel. AOX and TCAA (trichloroacetic acid) concentrations also decreased dramatically when 3.5 mg of ozone had reacted with the river water, but a higher dose of ozone did not further reduce AOX and TCAA formations. Besides, the characteristics of organic matter in raw water, ozonated water, and preozonated/chlorinated water was investigated. The results suggest the formation of low‐molecular‐weight acids with low UV absorbance when high‐molecular refractive matter is oxidized. 相似文献
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The degradation reactions of two monoazo pigments, namely, Red 53:1 and Red 48:2, by Fenton, photo‐Fenton and UV/H2O2 systems have been studied. The efficiencies of the Fenton reactions increased with temperature, but the formation of solid agglomerates was observed when the reactions were carried out above 50°C indicating a coagulant action of Fe+2 or Fe+3. Photo‐Fenton reactions irradiated by sunlight presented the best rate constants for cleavage of the azo bond and the naphthalene rings. The UV/H2O2 system exhibited the highest efficiency with respect to the consumption of H2O2. The presence of a carbonyl group in the ortho position of the naphthol ring hampered the oxidation of pigment Red 48:2 by hydroxyl radicals. This finding may be explained in terms of the acceptor character of the COOH group, and suggests the formation of a complex containing two six‐membered rings between Fe+3 and the pigment molecule. 相似文献
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17.
江苏省西部湖泊溶解性有机物光谱学特征和来源解析 总被引：11，自引：2，他引：9
利用光谱学手段研究江苏省西部湖泊表层水体中溶解性有机物(DOM)组成与结构,并对其来源进行分析.单位浓度可溶性有机碳在254和280 nm波长下的吸光度值(SUVA)测定结果表明,各湖泊芳香性程度及分子量大小依次为邵伯湖>天岗湖>白马湖>石臼湖>洪泽湖>固城湖>骆马湖>高邮湖>宝应湖.特定波长下吸光度的比值(E2/E3、E3/E4)显示邵伯湖和白马湖中的DOM结构复杂、分子量大、苯环多,以腐殖酸为主要成分;其它湖泊的DOM腐殖化程度较低,以富里酸为主.指数函数曲线斜率(S275～295nm)拟合结果也同样表明邵伯湖DOM分子量最大,而宝应湖最低.各湖泊荧光指数和生物指数分别处于1.13～1.30和0.47～0.67范围内,体现出DOM强烈的陆源性.四个主要荧光峰的相对荧光强度之间均存在良好的相关性,表明这些湖泊的类腐殖酸及类蛋白物质可能有着相同的来源.结合这些湖泊的特征及流域经济发展水平,可以初步推断经入湖河流携带的由农业及其下游产业产生的有机质是江苏西部湖泊中DOM的主要来源. 相似文献
18.
The fluorescence and molecular weight characteristics of dissolved organic matter (DOM) in groundwater of Bangladesh were investigated to evaluate its multiple roles on arsenic (As) mobilization and poisoning. Fluorescence properties of DOM were measured in groundwater samples collected from two As contaminated areas of Bangladesh (Faridpur at the Ganges floodplain and Sonargaon at the Meghna floodplain) from different locations and depths. The three dimensional excitation–emission matrix (3DEEM) fluorescence spectra of groundwater samples showed two characteristic peaks around Ex/Em = 335–365 nm/435–480 nm for fulvic-like peaks and peak at around Ex/Em = 275–290 nm/310–335 nm for the protein-like materials. The similarity of fluorescence spectra of groundwater and surface water of both the study areas with high intensity of fluorescence and its strong correlation with DOC reflect the in situ generation of fluorescent DOM from sedimentary organic matter (SOM) and recent recharge of terrestrial labile organic carbon into shallow aquifer. High performance size-exclusion chromatography (HPSEC) analysis of DOM shows positive correlations between fluorescence intensities (FI) of small molecular fractions (0.65 kDa) and As concentrations, with the signatures of protein-like peaks of DOM in groundwater. This result provides new evidence that small molecular weight fraction of DOM in groundwater of Bangladesh can play an important role on As mobilization and toxicity. In addition, high concentration of fluorescence materials in DOM of As contaminated groundwater of Bangladesh may pose a threat to public health. 相似文献
19.
Photooxidation degradation of Reactive Brilliant Red K‐2BP (K‐2BP) aqueous solution by ultraviolet irradiation/sodium hypochlorite (UV/NaClO) was investigated. The effects of NaClO dosage, pH, temperature and initial dye concentrations were studied. A possible degradation pathway of K‐2BP was investigated. Acidic or neutral conditions were beneficial to the decolorization of K‐2BP aqueous solution. However, alkaline conditions facilitated chemical oxygen demand (COD) removal. Increasing the solution temperature from 20 to 50°C increased the removal of color and COD. However, at 60°C, the final percentage color and COD removal decreased by approximately 17 and 10%, respectively. Based on the products indentified and theoretical analysis, N=N cleavage and C‐N cleavage were possible initial steps in the degradation of K‐2BP. From the results of this work, we conclude that treatment of UV/NaClO is an efficient method to degrade K‐2BP in aqueous solution. 相似文献
20.
Frequent heavy rainfalls during the East Asian summer monsoon drastically increase water flow and chemical loadings to surface waters. A solid understanding of hydroclimatic controls on watershed biogeochemical processes is crucial for water quality control during the monsoon period. We investigated spatio‐temporal variations in the concentrations and spectroscopic properties of dissolved organic matter (DOM) and the concentrations of trace metals in Hwangryong River, Korea, during a summer period from the relatively dry month of June through the following months with heavy rainfall. DOM and its spectroscopic properties differed spatially along the river, and also depended on storm and flow characteristics around each sampling time. At a headwater stream draining a forested watershed, the concentrations (measured as dissolved organic carbon (DOC)), aromaticity (measured as specific UV absorbance at 254 nm), and fulvic acid‐ and protein‐like fluorescence of DOM were higher in stormflow than in baseflow waters. DOC concentrations and fluorescence intensities increased along the downstream rural and urban sites, in which DOC and fluorescence were not higher in stormflow waters, except for the ‘first flush’ at the urban site. The response of DOM in reservoir waters to monsoon rainfalls differed from that of stream and river waters, as illustrated by storm‐induced increases in DOM aromaticity and fulvic‐like fluorescence, and no significant changes in protein‐like fluorescence. The results suggest that surface water DOM and its spectroscopic properties differentially respond to changes in hydroclimatic conditions, depending on watershed characteristics and the influence of anthropogenic organic matter loadings. DOC concentrations and intensities of spectroscopic parameters were positively correlated with some of the measured trace metals (As, Co, and Fe). Further research will be needed to obtain a better understanding of climate effects on the interaction between DOM and trace metals. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献