Comparative study on organic constituents in polluted and unpolluted inland aquatic environments—III: Phenols and aromatic acids in polluted and unpolluted waters

Phenols and aromatic acids were analysed in polluted river waters in the Tokyo area and in water from an unpolluted river, brook, reservoir and in pond waters from the Ogasawara (Bonin) Islands. The phenolic acids (p-hydroxybenzoic, vanillic, syringic, p-coumaric and ferulic acids) and o- and m-hydroxybenzoic acids were found in the waters of the Tokyo area and Ogasawara Islands at a concentration of generally less than 1 μg 1⁻¹, but pentachlorophenol, bisphenol A, terephthalic and trimesic acids were not identified in the waters of the Ogasawara Islands. It was confirmed that the major sources of these phenolic acids are vascular plants and their detritus, while pentachlorophenol, bisphenol A and terephthalic acids are mainly attributed to human activities. It was also established that these phenolic acids are commonly distributed in polluted and unpolluted waters.The p-coumaric and ferulic acids as carbon (CFC)/total organic carbon and CFC/extractable organic carbon with ethyl acetate values suggested that the contribution of vascular plants and their detritus to the waters between the Tokyo area and Ogasawara Islands are near equal. According to the syringic acid/vanillic acid ratios, it is probable that the relative contribution of angiosperms to gimnosperms for the waters of the Tokyo area is smaller than those of the Ogasawara Islands.     

Model studies in aqueous chlorination: The chlorination of phenols in dilute aqueous solutions

A study of the chlorination of four phenols in dilute aqueous solution at initial pH's of 6.0 and 3.5 is described. Extensive chlorination is observed under these mild reaction conditions. Identification of the products indicates that the reactions occurring involve chlorination to more highly chlorinated phenols, oxidation to chlorinated p-benzoquinones, chlorine addition to the aromatic ring to form chlorinated 2,5-cyclohexadienones, and addition of 2 moles of chlorine or one each of chlorine and hypochlorous acid to give chlorinated cyclohexenones and chlorinated hydroxycyclohexenones.     

Phenolic acids as indicators of pollution with liquid manure. A method for their detection

Detection of a combination of 2 or 3 of the phenolic acids m-hydroxybenzoic acid, m-hydroxyphenylacetic acid and m-hydroxyphenylpropionic acid by a method described indicates whether a water sample contains liquid manure. The method using thin-layer chromatography on cellulose is designed on the basis of results from qualitative and quantitative determinations of the phenolic acids in liquid manure by paper chromatography and gas chromatography respectively. It was developed in order that illegal discharges of liquid manure could be detected. The phenolic acids is extracted with ethyl acetate from a volume of acidified sample equalling 1 mg of oxygen consumed (measured with potassium permanganate). The ethyl acetate is evaporated and the residue dissolved in ethanol. After spotting of a 1 μl, aliquot on a cellulose TLC plate the chromatogram is developed by capillary ascent with the solvent n-propanol:n-butanol: 25°_o NH₃:water (4:4:1:1, by vol). The solvent front is allowed to advance 10 cm. This takes about 2·5 h. The air-dried plate is sprayed with a diazotized p-nitroaniline reagent to make the phenolic acids visible. The application of the method has been tested with different sources of waste water. The phenolic acids was detectable in 23 out of 28 samples of stored liquid manure. A degradation study, where liquid manure was diluted 100 times with stream water and then aerated, showed decomposition of the phenolic acids after a few days. However the addition of NaOH to samples prevents decomposition of the phenolic acids.     

Application of pyrolysis-gas chromatography-mass spectrometry to the characterization of humic substances resulting from decay of aquatic plants in sediments and waters

Pyrolysis-GC-MS, elemental analysis and i.r. spectroscopy reveal major differences between humic substances from aquatic plants (algae and aquatic phanerogams) and lagoonal, marine and lacustrine deposits. Algae are enriched in proteins and their pyrolysis yields numerous nitrogenous by-products (alkylpyrroles, nitriles and alkylpyridines) along with aromatic compounds which are thought to reflect the decomposition of individual amino-acids (styrene, toluene, phenol and p-cresol). These compounds are less abundant in the pyrolysis products of humic substances from phanerogams with increasing amounts of methoxyphenols, characteristics of lignins.In the deposits of the Kerguelen Islands and of a “blue lake” in Greenland, the importance of algal populations is emphasized by pyrolysis products corresponding to nitrogenous and carbohydrate derivatives. Phenols and cresols in the pyrochromatograms of these samples are interpreted as evidence of polypeptides rather that lignin: p-cresol is much more abundant than the other cresols, suggesting the formation of phenols by way of tyrosine.Lagoonal sediments, in contrast, seem typical of intermixed development of algae and phanerogams.Differences between fulvic and humic acids are emphasized by the development of polyphenols and protein derivatives in humic acids compared to polysaccharide derivatives in fulvic acids. Other constituents revealed by PY-GC-MS include N-acetyl aminosugars, phthalates and aliphatic compounds.     

Ozonation des phenols et des acides phenoxyacetiques

The study of the ozonization of phenol, substituted phenols and some phenoxyacetic acids (2-4-D and MCPA) was carried out taking into consideration on the one hand the rate and the mechanism of the reaction leading to the opening of the aromatic cycle and on the other the consumption of ozone in relation to the degree of degradation.We were able to show that in a diluted solution the opening of the aromatic cycle could be obtained with a ratio O₃/ΦOH roughly equal to 5 and that the reaction rate depended on the amount of ozone produced.The existence of reactional intermediates and the development of a u.v. spectrum of the substances during the ozonization allowed us to show that the reaction could evolve with the formation of o and p benzoquinone and that the nature and position of the substituent along the aromatic cycle seemed to be a determinant factor in the orientation of the reaction.The degradation of the substances is influenced by the pH, both as far as the rate and the reactional mechanism are concerned.The decrease in the rate of consumption of ozone resulting from the opening of the aromatic cycle leads us to define an optimum production of ozone, which depends on the concentration in aromatics to be degraded and susceptible of leading to the formation of substances which will be more easily biodegradable.     

Measurement of phenols dearomatization via electrolysis: The UV-Vis solid phase extraction method

Dearomatization levels during electrochemical oxidation of p-methoxyphenol (PMP) and p-nitrophenol (PNP) have been determined through UV-Vis spectroscopy using solid phase extraction (UV-Vis/SPE). The results show that the method is satisfactory to determine the ratio between aromatic compounds and aliphatic acids and reaction kinetics parameters during treatment of wastewater, in agreement with results obtained from numerical deconvolution of UV-Vis spectra. Analysis of solutions obtained from electrolysis of substituted phenols on antimony-doped tin oxide (SnO₂Sb) showed that an electron acceptor substituting group favored the aromatic ring opening reaction, preventing formation of intermediate quinone during oxidation.     

不同消毒剂作用于富里酸生成羰基类化合物情况

在自行建立的羰基类化合物检测方法基础之上,以富里酸为模型物,考察不同消毒剂(臭氧、氯胺、二氧化氯、紫外、臭氧/紫外、臭氧/过氧化氢)作用于富里酸生成羰基类化合物的情况。结果表明:不同消毒剂作用于富里酸均生成一定量的羰基类化合物,主要有甲醛、乙醛、丙醛、丁醛、乙二醛、甲基乙二醛、甲酸、乙酸、富马酸、原儿茶酸、苯甲酸、3-羟基苯甲酸、o-硝基苯甲酸。芳香类有机酸可能是富里酸氧化的主要产物。具有选择性的强氧化剂臭氧可以进一步与化学性质活泼的芳香羧酸反应,生成小分子醛和酸。在水处理过程中,羰基类化合物将成为消毒副产物新的前体物质。     

Oxidation of aromatic compounds by haemoglobin

Klibanov et al. have recently developed new methods for the elimination of phenols and aromatic amines. These involve two enzyme systems. Polyphenol oxidase with oxygen and horseradish peroxidase (HRP) with hydrogen peroxide, which permit the precipitation of these pollutants from wastewaters. Another study, using HRP, has shown that phenols at the low concentration usually found in drinking water, can be removed but with no apparent precipitate. However, these processes seem to be limited by the cost of the catalyst. In this work, the possibilities for oxidation of a phenolic compound such as methoxyphenol, by free or immobilized HRP, haemoglobin or blood haemolysate, in the presence of hydrogen peroxide, were investigated. Results indicate that haemoglobin can replace HRP with regard to its activity and cost. Removal of phenol was studied with free blood-haemolysate. More than 90% of this aromatic compound disappeared. Two conversion products were identified, 4,4′- and 2,2′-dihydroxybiphenyl, but not in sufficient quantity to account for all phenol removed.Nearly complete removal of benzidine and o-dianisidine, two carcinogenic aromatic amines often found in surface water, was obtained with immobilized blood haemolysate.Enzymatic oxidation by haemoglobin appear to be efficient and useful in the removal of micropollutants from drinking water.     

Disappearance of aromatic hydrocarbons and organic sulfur compounds from fish flesh reared in crude oil suspension

Eels (Anguilla Japonica Temminck et Schlegel) were reared in sea water containing a crude oil suspension (50 ppm for 10 days for aromatic hydrocarbons, 2500 ppm for 3 days for organic sulfur compounds), then transferred to clean sea water. The disappearance of aromatic hydrocarbons and organic sulfur compounds from eel flesh was examined. The concentration ratio (concentration of eel flesh/concentration of water) of benzene, toluene, m- or p-xylene and o-xylene at 10 days was 3.5, 13.2, 23.6 and 21.4 respectively.Benzene, toluene, m- or p-xylene and o-xylene disappeared after the transfer to clean sea water, and the half-life period was 0.5, 1.4, 2.6 and 2.0 days respectively in the first phase which lasted 0–5 days.Organic sulfur compounds in cel flesh decreased as the time spent in clean sea water increased, but were still present after 30 days.The results suggest that aromatic hydrocarbons and organic sulfur compounds could serve as markers of oil pollution in fish.     

Equilibrium approaches to natural water systems—6. Acid-base properties of a concentrated bog-water and its complexation reactions with aluminium(III)

A filtered bog-water, concentrated by means of a freezing technique, has been studied with respect to acid-base properties and aluminium(III) complexation reactions. Sampling was performed during autumn and winter periods with a resulting acidity or alkalinity due to oxic (autumn) or anoxic (winter) conditions. The measurements were performed as potentiometric titrations in constant ionic media (0.02, 0.1 and 0.6 M NaCl) with the use of a glass electrode. The samples show buffer ranges at 3 pH 5 and pH 7.5. The first is ascribed to the presence of carboxylate groups and is characterized by fast equilibria. The second is due to phenolic OH⁻ groups and precipitation reactions with resulting sluggish equilibria. For one sampling period comprehensive measurements were undertaken to study the possible polyelectrolytic character of the organic acids. Due to the small increase in apparent carboxylate pKa-values with the degree of dissociation at low (0.02 M) as well as at high (0.6 M) ionic strength, the possible polyelectrolytic feature of the acids was neglected. Instead, a good fit to data was obtained by introducing a di-protic acid (H₂L) as a model compound. Furthermore the medium dependence of the two acidity constants could satisfactorily be fitted to the expression:

Full-size image (1K)

, where K is the constant at infinite dilution, a and b parameters of which b has been adjusted to present data. The following K values were obtained: pK₁ = 3.65 and pK₂ = 4.30. The complexation with Al(III) could be described by the formation of AlL⁺, AlL₂⁻ and the ternary species AlLH₋₁. The stability constants (log k₁ = 4.4 (winter), 4.2 (autumn); log k₂ = 4.2, 4.7; pKa (AlL⁺) = 4.2, 4.2) show no significant trend with sampling period but indicate a stability of the complexes greater than for phtalic acid but lower than for oxalic acid. Finally, the theoretical solubility of the clay mineral kaolinite in the presence of bog-water was computer modelled. The calculations show up on a 10-fold increase with respect to soluble aluminium at pH = 5.     

A possible new disinfection by-product--2-chloro-5-oxo-3-hexene diacyl chloride (COHC)--in formation of MX by chlorinating model compounds

MX was widely considered as one of the most important disinfection by-products (DPBs) and as the strong carcinogen in the chlorinated drinking water. Some model compounds which have been classified into four families were chlorinated at laboratory conditions. MX was produced only in the chlorinated substituted aromatic aldehydes and amino acids, while a possible new compound (COHC) was found in some substituted aromatic aldehydes, chlorinated substituted aromatic acids and phenols. Through the analysis of the peaks presented in mass spectrum, the composition and structure of the new compound are proposed as 2-chloro-5-oxo-3-hexene diacyl chloride (COHC) which could cause interference in the detection of MX. COHC has also been found in drinking water and extracted chlorinated fulvic acid solution from the sediment and water of Tai Lake, so it should bring about more attention.     

Dissolved organic compounds in reused process water for steam-assisted gravity drainage oil sands extraction

The in situ oil sands production method called steam-assisted gravity drainage (SAGD) reuses process wastewater following treatment. However, the treatment and reuse processes concentrate contaminants in the process water. To determine the concentration and dynamics of inorganic and organic contaminants, makeup water and process water from six process steps were sampled at a facility employing the SAGD process in Alberta, Canada. In the groundwater used for the makeup water, the total dissolved organic carbon (DOC) content was 4 mg/L. This significantly increased to 508 mg/L in the produced water, followed by a gradual increase with successive steps in subsequent water treatments. The concentrations and dynamics of DOC constituents in the process water determined by gas chromatography-mass spectrometry showed that in the produced water, volatile organic compounds (VOCs) such as acetone (33.1 mg/L) and 2-butanone (13.4 mg/L) predominated, and there were significant amounts of phenolic compounds (total 9.8 mg/L) and organic acids including naphthenic acids (NAs) corresponding to the formula C_nH_2n+ZO_X for combinations of n = 4 to 18, Z = 0 and −2, and X = 2 to 4 (53 mg/L) with trace amounts of polycyclic aromatic hydrocarbons (PAHs) such as naphthalene and phenanthrene. No organic contaminants, except for saturated fatty acids, were detected in the groundwater. The concentration of DOC in the recycled water was 4.4-fold higher than that in the produced water. Likewise, the total concentrations of phenols and organic acids in the recycled water were 1.7- and 4.5-fold higher than in the produced water, whereas the total concentrations of VOCs and PAHs in the recycled water were reduced by over 80%, suggesting that phenols and organic acids are selectively concentrated in the process water treatment. This comprehensive chemical analysis thus identified organic constituents that were concentrated in the process water and which interfere with subsequent water treatments in the SAGD process.     

Analytical problems in the determination of photoproducts of hydroxamic acids

Results of studies of the photodegradation of aromatic hydroxamic acids, to compounds suspected to be carcinogenic and mutagenic, have stimulated an interest in the analysis of these acids and their photoproducts.In this paper, results are reported of investigations on the influence of phosphate buffer concentration, buffer/methanol ratio and eluent pH on the separation of photoproducts formed after irradiation of N-phenyl-benzenecarbohydroxamic, N-methyl-2-naphthalenecarbohydroxamic and N-/p-tol/-2-naphthalenecarbohydroxamic acids.The best separation conditions were achieved using a 0.1 M buffer concentration and an eluent pH_e of 4.0–5.2. At a pH_e lower than 3.5, on-column hydrolysis of the hydroxamic acids was observed.     

Bioavailability of organic pollutants in boreal waters with varying levels of dissolved organic material

Dissolved organic matter (DOM) in 20 surface waters in Eastern Finland were characterized to examine relationships between structural and compositional properties of DOM and partition coefficients (K_p) describing sorption of four model contaminants to DOM and the bioavailability of contaminants by Daphnia magna. The hydrophobic acids (HbA), hydrophobic neutrals (HbN) and hydrophilic (HI) fractions of DOM were separated by XAD-8 resin. The K_Ps were measured by equilibrium dialysis. Model contaminants were benzo(a)pyrene (BaP), naphthalene (NAPH), 3.3′,4.4′-tetrachlorobiphenyl (TCB) and dehydroabietic acid (DHAA).DOM concentrations varied from 2.0 to 38.3 mg org. C/l in the water series. The percentage of HbA and the aromaticity of DOM, as indicated by the absorptivity at 270 nm (A₂₇₀) and hydrogen/carbon ratio (H/C ratio), increased with increasing DOM concentration. Significant correlations were observed between K_P of BAP, A₂₇₀ and HbA content of the DOM from different sources. For the other contaminants similar kinds of relationships between K_ps and quality parameters of DOM could not be found.The bioavailability of model compounds was decreased by increasing DOM concentration in the water series. For all four model contaminants, measured bioconcentration factors (BCF) correlated well with the A₂₇₀ of a water and HbA content of the DOM. These results show that the total DOM concentration is an important factor controlling the bioavailability of xenobiotics in natural waters. Besides the quantity also the quality of DOM, like proportion of HbA, can contribute in bioavailability.     

4-Aminoantipyrine as a chromogenic agent for aromatic amine determination in natural water

Reaction of 4-aminoantipyrine (4-AAP) with aromatic amines was investigated. The study showed the merits and limitations of 4-AAP as a chromogenic agent for the colorimetric determination of aromatic amies in water. Maximum colour development was reached within one minute and the colour maintained its stability for 10 min. 4-AAP is not a sensitive chromogenic reagent for the determination of chloro-, nitro-, p-substituted amines nor for polycyclic aromatic amines. Molar absorptivity of the 4-AAP-dye complexes was discussed and shown to be affected by steric hinderance and lability of the lone pair of electrons of the amino nitrogen.     

Removal of aromatic compounds from water on biologically activated carbon

We have carried out an assessment of the content of aromatic compounds (o-nitrophenol, o-aminobenzoic acid) in grains of activated carbon of a biofilter at the stage of stationary water treatment. It was found that the removal degree of aromatic compounds by the biofilm of biologically activated carbon in great measure is determined by the value of the decreasing of Gibbs free energy of adsorption (−ΔG _a ). It is shown that due to the competing action of the biofilm part of the accessible surface of activated carbon is not used for adsorption of organic matter.     

Cinetiques et mecanismes de l'action oxydative de l'hypochlorite sur les acides α-amines lors de la desinfection des eaux

In the field of water treatment, one increased concern over the quality of the environment requires an understanding of the fate of compounds generated by the addition of chemicals. One area of considerable interest is the stability of chlorine compounds produced when chlorine is added to natural water or swimming pool water. It is desirable to be able to predict the lifetimes of these harmful compounds under various conditions. In this study we examine for a range of hypochlorite α-amino acid ratios and pH, the kinetics and mechanism of the decomposition of α(N-chloro) and α(N,N-dichloro) amino acid, one of the products of chlorination.The interaction of chlorine with amino acids has been studied by several investigators Langheld (1909) was the first who discussed the decomposition of the α(N-chloro) amino acids. He noted that hypochlorous acid salts react with α-amino acids in the same manner as they do with amines to form monochlorinated or dichlorinated derivatives. Then, the decomposition of chloro-amino acids leads to the corresponding aldehydes or ketones, ammonia, carbonic acid, and sodium chloride. As an intermediate step Langheld assumed an imine formation.Wright (1936) and Pereira et al. (1973) have investigated the decomposition products of α(N,N-dichloro) amino acids. Their results indicate rapid formation of carbon dioxide, chloride ion, and the corresponding nitrile.Recently, many authors have investigated the rates of α(N-chloro) amino acids decomposition and the stability of its products (William and Wendy, 1979; Yoshiro et al., 1980; Le Cloirec-Renaud, 1984). However, they have neither differentiated between the decomposition of α(N-chloro) amino acid and α(N,N-dichloro) amino acid, nor have they demonstrated the combined effect of pH and molar ratio of hypochlorite and α-amino acid.In this study the hypochlorite oxidation of simple α-amino acids in aqueous solution has been investigated in the dark. The concentration of α(N-chloro) amino acid and α(N,N-dichloro) amino acid was monitored by DPD-fast titrimetric method and by measuring the absorbance at 255 and 293 nm respectively, this is illustrated in Figs 3 and 4. These results and the amino acids determination (O-phtalaldehyde—2 mercapto ethanol method) suggest that the intermediates α(N-chloro) and α(N,N-dichloro) amino acid are formed rapidly at an initial stage. Then, they decompose spontaneously by first order kinetics as shown in Table 1, to give a mixture of aldehyde and nitrile.When equimolar (1:1 mmol) amounts of hypochlorite and amino acid are used at pH 7, only aldehyde, carbon dioxide, chloride and ammonia are formed. However the corresponding nitrile compound appears, when operating condition allow the formation of α(N,N-dichloro) amino acid (acid pH or basic aqueous solutions with high molar ratio of hypochlorite and amino acid). This is illustrated in Table 2. The rate constant shows a dependence on pH, which is caused by the various forms that can arise from addition of protons to or removal of protons from the amino and carboxyl groups of the molecule William and Wendy, 1979). We assume an intermediate step of imine for the decomposition of both compounds: α(N-chloro) and α(N,N-dichloro) amino acid (scheme 6). The reaction should be considered as a spontaneous decarbonylation followed by a rapid hydrolysis of the imine. Scheme 7 illustrated how α(N,N-dichloro) amino acid can lead to the corresponding nitrile and aldehyde, however the α(N-chloro) amino acid gives only the corresponding aldehyde.The products of decomposition of α(N-chloro) amino acid are relatively stable in aqueous solution. Although we noted at pH = 3.5–5 that aldehyde react with chloramines and lead to the formation of corresponding nitrile, as shown in scheme 9.It appears that α(N-chloro) and α(N,N-dichloro) amino acid formed during the chlorination of natural or swimming pool water will degrade in a few hours to what are probably irritating products (like as aldehydes). The production of decomposition are a function of molar ratio of hypochlorite and amino acid and pH. However, since most natural water has a pH in the range of 5.5–9, there will be little variation of the rate of decomposition with pH. It seems that it is only temperature dependent.     

Sorption of hydrophobic pollutants on natural sediments

The sorption of hydrophobic compounds (aromatic hydrocarbons and chlorinated hydrocarbons) spanning a concentration range in water solubility from 500 parts per trillion (ppt) to 1800 parts per million (ppm) on local (North Georgia) pond and river sediments was investigated. The sorption isotherms were linear over a broad range of aqueous phase pollutant concentrations. The linear partition coefficients (K_p) were relatively independent of sediment concentrations and ionic strength in the suspensions. The K_p ś were directly related to organic carbon content for given particle size isolates in the different sediments. On an organic carbon basis (K_{oc = Kp/fraction}) organic carbon), the sand fraction (> 50 μm particle size) was a considerably less effective sorbent (50–90% reduction in K_oc) than the fines fraction (> 50 μm particles). Differences in sorption within the silt and clay fractions were largely related to differences in organic carbon content. Reasonable estimates of K_ocś can be made from octanol/water distribution coefficients, which are widely catalogued or easily measured in the laboratory.     

Structure et evolution d'un modele d'acide humique sous l'effet de l'ozonation

Humic acids are widely studied as complexing agents in surface waters, but little is known about the chemical structure of their potential sites of interaction with micropollutants. By means of powerful spectroscopic techniques such as u.v.-visible, infrared and electron spin resonance spectrometries run on a commercial model Fluka (AHF), we carried out the structural investigation of the concerned functional groups and studied their evolution under ozonation.Consecutively to the consumption of 1.24 mg ozone per mg of AHF, one can see (Table 1) that the decrease in phenol groups (21%) can be matched with that of aromaticity (16%). Moreover, an original study performed on ultrafiltration fractions: (1) M > 3.10⁵; (2) 3.10⁵ >M > 5.10⁴; (3) 5.10⁴ >M > 5.10³; (4) M < 5.10³ showed that half of the hydroxyl group disappears from fraction 1. Relatively high values of molar extinction coefficients (_254nm = 360,000 and _203nm = 458,000) suggest a polysubstitution state for aromatic cycles and this has been confirmed by infrared spectrometry. The relative position of benzenic substituents cannot be inferred from u.v. visible data (Table 2) but the well-resolved infrared spectra (Fig. 1 and Table 3) reveal the presence of phenolic, benzoate, phtalate and salicylate groups close to semiquinonic anion radicals, aromatic units being linked by some alcanoic chains, most of them formed by four methylene groups. The proposed structural scheme (Fig. 4) is in agreement with Murray and Linder's (1983).Investigation of the infrared characteristics of the four ultrafiltration fractions shows that these functional groups are not equally distributed over the molecular weight range. Polysubstituted aromatic cycles, phenolic and quinonic structures are mainly detected in fractions (1) and (2), whereas acid and ester groups are significantly observed in fractions (3) and (4).After ozonation, the 1720, 1700 and 1350 cm⁻¹ bands, assigned to stretching valence vibrations of aromatic esters are depressed. For fraction (I), ozonation of aromatic structures is substantial (Fig. 2 and Table 4), as it is expected for polysubstituted molecules (Decoret et al., 1984; Gilbert, 1978). Less substituted structures are divided on fractions (2) (3) and (4). Infrared spectra of fractions (3) and (4) are markedly disturbed. This reveals that quinonic and ethylenic groups increase as aromatic cycles do (780 cm⁻¹ band).Electron spin resonance investigation (Fig. 3 and Table 5) shows that AHF and its fractions (1) and (2) are endowed with electronic paramagnetism. As g values are close to 2.0040 and as this property disappears after ozonation, it must be due to semiquinonic anion radicals partly maintaining aggregative structures (Steelink et al., 1983; Wershaw et al., 1977), leading to quinonic structures by oxidation.     

Leaching patterns from wood of different tree species and environmental implications related to wood storage areas

Batch tests were carried out with sawdust obtained from oak (Quercus robur), maple (Acer platanoides), pine (Pinus sylvestris), beech (Fagus sylvatica) and wood chips from oak and pine. Leaching of organic compounds expressed as dissolved organic carbon (DOC) in mg/kg of dry mass took place during the first 24 h. The following additional variables were analysed: pH, conductivity, colour, phenols, tannins and lignin, and biochemical oxygen demand (BOD₇). When leachates obtained with oak wood chips and pine wood chips were compared, no significant difference was observed. However, in batch tests with sawdust, DOC released by oak (90 000 mg/kg) was significantly higher (P = 0.0001) than DOC released by pine (30 000 mg/kg). The results suggest that particle size is not the only variable affecting the leaching of organic compounds from wood. Regarding BOD, colour [platinum‐cobalt (Pt‐Co)], phenols, tannins and lignin, the leaching patterns differed among species, and oak was the species with the highest released values.