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1.
This work studies the effects of wood amendments on soil microbial community functioning and on the potential of this community for linuron degradation. For this purpose, soil dehydrogenase activity and the number of live bacteria, which represent broad scale measurements of the activity and viability of soil organisms, were assessed in soil treated with linuron and either amended with pine or oak wood or unamended (sterilized and non-sterilized). The overall results show that the microbial community had a significant role in linuron degradation. The linuron half-life values indicated a slower degradation rate in pine and oak amended soils than in unamended ones. This is attributed both to the higher sorption of linuron by these soils compared to the unamended ones and a consequent lower bioavailability of the herbicide for microbial degradation, and to the use of the pine and oak as an alternative carbon source by degrading microorganisms. Linuron did not affect the microbial community in terms of dehydrogenase activity and number of live bacteria, presumably because it had adapted to the herbicide. However, the dehydrogenase activity was significantly higher in the soils amended with pine or oak than in the non-amended ones, indicating that the presence of a carbon source favoured the overall bacterial community.  相似文献   

2.
在陕北丘陵沟壑区,以油松纯林为对照,通过对油松与沙棘行状混交、带状混交和宽行混交沙棘平茬、宽行混交沙棘不平茬的油松树高、地径、树冠、顶梢生长、存活率等的监测研究,结果表明,不同方式混交的油松在栽后前3 a的生长状况与纯林无差异。当混交林的沙棘覆盖度达到70%以上后,行状混交和宽行混交沙棘不平茬的油松生长量开始下降,栽后6～7 a大量死亡,第8 a基本死完;宽行混交沙棘平茬的油松,随着平茬沙棘的萌生,油松的生长量大于纯林,在萌生沙棘生长的第3 a,沙棘覆盖度达40%～45%时,油松的生长量明显大于对照;带状混交的油松,当沙棘侵入油松林带后,油松的生长量大于对照,当沙棘的覆盖度达40%～45%时,油松生长速度与纯林的差异明显。不同年份的降水量对油松的生长影响显著,但滞后1 a。  相似文献   

3.
A red Rioja wine was aged in barrels made of Spanish oak wood (Quercus robur, Quercus petraea,Quercus pyrenaica, and Quercus faginea) during 21 months. The concentrations of some volatile compounds [syringaldehyde, vanillin, eugenol, maltol, guaiacol, 4-ethylphenol, cis and trans isomers of beta-methyl-gamma-octalactone, 2-furfuraldehyde, 5-methyl-2-furfuraldehyde, 5-(hydroxymethyl)-2-furfuraldehyde, and furfuryl alcohol] were studied in these wines and compared with those of the same wine aged in barrels made from French oak of Q. robur (Limousin, France) and Q. petraea (Allier, France) and American oak of Quercus alba (Missouri). Similar concentrations of these compounds were found in wines aged in Spanish and French oak wood barrels, and significantly different concentrations were found with respect to wines aged in barrels made of American oak wood, indicating a different behavior. Thus, wines with different characteristics were obtained, depending on the kind of wood. Also, the kind of wood had an important influence on sensory characteristics of wine during the aging process. Spanish oak wood from Q. robur, Q. petraea, and Q. pyrenaica can be considered to be suitable for barrel production for quality wines, because a wine aged in barrels made of these Spanish oak woods showed similar and intermediate characteristics to those of the same wine aged in French and American oak woods usually used in cooperage.  相似文献   

4.
The evolution of low molecular weight polyphenols in Spanish oak heartwood of Quercus robur,Quercus petraea, Quercus pyrenaica, and Quercus faginea was studied by HPLC, in relation to the processing of wood in barrel cooperage. The polyphenolic composition of Spanish woods subjected to natural seasoning for 3 years and to the toasting process was studied in relation to those of French oak of Q. robur (Limousin) and Q. petraea (Allier) and American oak of Q. alba (Missouri), which are habitually used in cooperage. The concentrations of benzoic and cinnamic acids and aldehydes of Spanish woods increased during seasoning depending on the duration of this process and in the same way as those of French and American woods. The process having the main influence on the phenolic composition of wood was the toasting. It led to high increases in the concentration of phenolic aldehydes and acids, especially cinnamic aldehydes (sinapic and coniferylic aldehydes), followed by benzoic aldehydes (syringaldehyde and vanillin) and benzoic acids (syringic and vanillic acids). This polyphenolic composition in Spanish oak species evolved during toasting as in French and American oak, but quantitative differences were found, which were especially important in American species with respect to the others.  相似文献   

5.
The effect of management practices on soil potential for regulating the residual concentration of pesticides was examined in samples from a Calcic Haploxeralf in Toledo (central Spain). Sorption-desorption of alachlor and linuron was found to depend on inputs of lignocelullosic wastes or cattle manure for the past 16 years. For a given herbicide, the soil sorption capacity (K(f)) follows the order control < crop residues < manure, which is consistent with the organic C content in the soil samples. Some structural characteristics of the soil humic acid as revealed by visible and infrared spectroscopies and analytical pyrolysis were useful to forecast the sorption-desorption intensity. Simple and multiple linear correlation analyses illustrate enhanced sorption of alachlor and linuron in soil plots where slightly altered soil organic matter accumulated (positive correlations with the intensity of infrared lignin signature band and with the methoxyphenol yields after pyrolysis of the humic acids and negative correlation with the aromaticity as pointed out by the optical density at 465 nm). Linuron showed a preference for soils with humic acids of low molecular weight and low degree of internal cross-linking, as inferred from the positive correlation with the ratio between optical densities at 465 and 665 nm. Under the conditions of the present experiment, agricultural practices including organic amendments seem to have a beneficial effect in the control of leaching and sorption of pesticides.  相似文献   

6.
土壤中黑碳对农药敌草隆的吸附-解吸迟滞行为研究   总被引：6，自引：0，他引：6  
采用批处理振荡法和连续稀释法分别测定了敌草隆在人工添加黑碳土壤和自然形成的不同有机质和黑碳含量的土壤中的吸附一解吸行为。吸附结果表明，人工添加黑碳的土壤对敌草隆的吸附强度和吸附容量以及吸附等温线的非线性均随土壤黑碳添加浓度的增加而逐步增大；自然土壤的吸附容量和吸附强度随土壤总有机质含量增加而增加，但吸附等温线的非线性则与土壤中黑碳对有机质的相对含量有关，黑碳比例越高，等温线非线性越大。解吸实验结果表明，无论是人工添加黑碳的土壤还是自然土壤，对敌草隆的解吸迟滞作用均随土壤黑碳含量增高而愈明显。  相似文献   

7.
The evolution of almost 40 oak-related volatile compounds and the sensorial characteristics of red wines from four Spanish denominations of origin (DOs) (Bierzo, Toro, Ribera de Duero, and Rioja) during aging in barrels made of Rebollo oak wood, Quercus pyrenaica, were studied and compared to the same wines aged in American and French oak barrels. Each oak wood added unique and special characteristics to the wine, and in addition, each wine showed a different ability to extract the compounds, which result in these characteristics from the oak wood. In general, wines aged in Q. pyrenaica wood were characterized by high levels of eugenol, guaiacol, and other volatile phenols. In regards to compounds like cis-whiskylactone or maltol, the behavior of this wood is very similar to that of American oaks. When considering phenolic aldehydes and ketones, the levels of these compounds are intermediate between those of French and American woods and depend greatly on the type of wine. The type of oak, on the other hand, does not affect the chromatic characteristics of the wines. In sensory analysis, the biggest differences are found in the olfactory phase. Among the four DOs studied, wine aged in Q. pyrenaica presented the highest notes of wood, with more aromas of roasting, toasting, milky coffee, spices, or wine-wood interactions. The wines aged in barrels made of Q. pyrenaica wood were highly regarded, and preference was shown for them over those same wines when they had been aged in barrels of American or French oak.  相似文献   

8.
Different sorption behaviors for wine polyphenols in contact with oak wood   总被引：1，自引：0，他引：1  
The evolution of polyphenols of enological interest- monomeric anthocyanins, (+)-catechin, (-)-epicatechin, gallic acid, and trans-resveratrol-in the presence of oak wood was investigated in aging-model conditions. Disappearance kinetics showed that, except for gallic acid, all of the wine polyphenols tend to disappear from the model wine in presence of oak wood, to reach an equilibrium after 20 days of contact. At equilibrium, the higher disappearance rates were obtained for monomeric anthocyanins and trans-resveratrol with values of 20 and 50%, respectively. For monomeric anthocyanins, the rate of disappearance seemed to be independent of their nature. In order to evaluate the contribution of sorption to oak wood in the disappearance phenomena, sorption kinetics were determined for trans-resveratrol and malvidin-3-glucoside through the extraction and the quantification of the fraction sorbed to wood. These curves showed that the wood intake of trans-resveratrol and malvidin-3-glucoside followed a two-step behavior, with a higher rate during the first 2 days, likely due to a surface sorption mechanism, and then a slower rate to reach the equilibrium, which could be related to a diffusion mechanism. The comparison of disappeared and sorbed amounts at equilibrium showed that a minor part of the disappeared monomeric anthocyanins were sorbed by wood. In contrast, half of the concentration decrease of trans-resveratrol in wine finds its origin in a sorption mechanism by oak wood. Results in real wine show similar sorption kinetics.  相似文献   

9.
The evolution of tannins in Spanish oak heartwood of Quercus robur L., Quercus petraea Liebl.,Quercus pyrenaica Wild., and Quercus faginea Lam. was studied in relation to the processing of wood in barrel cooperage. Their evolution was compared with that of French oak of Q. robur (Limousin, France) and Q. petraea (Allier, France) and American oak of Quercus alba L. (Missouri), which are habitually used in cooperage. Two stages of process were researched: the seasoning of woods during 3 years in natural conditions and toasting. Total phenol and total ellagitannin contents and optical density at 420 nm of wood extracts were determined. The ellagitannins roburins A-E, grandinin, vescalagin, and castalagin were identified and quantified by HPLC, and the molecular weight distribution of ellagitannins was calculated by GPC. During the seasoning process the different ellagitannin concentrations decreased according to the duration of this process and in the same way as those in French and American woods. The toasting process also had an important influence on the ellagitannin composition of wood. Roburins A-E, grandinin, vescalagin, and castalagin decreased during this process in the Spanish wood species, in the same proportion as in the French and American ones. Also, the seasoning and toasting processes lead to qualitative variations in the structure of ellagitannins, especially in the molecular weight distribution, as was evidenced by GPC analysis of their acetylated derivatives.  相似文献   

10.
Pesticide sorption or binding to soil is traditionally characterized using batch slurry techniques. The objective of this study was to determine linuron sorption in field-moist or unsaturated soils. Experiments were performed using low-density (i.e., 0.25 g mL(-)(1)) supercritical carbon dioxide to remove linuron from the soil water phase, thus allowing calculation of sorption coefficients (K(d)) at low water contents. Both soil water content and temperature influenced sorption. K(d) values increased with increased water content, if less than saturated. K(d) values decreased with increased temperature. K(d) values for linuron sorption on silty clay and sandy loam soils at 12% water content and 40 degrees C were 3.9 and 7.0 mL g(-)(1), respectively. Isosteric heats of sorption (DeltaH(i)) were -41 and -35 kJ mol(-)(1) for the silty clay and sandy loam soils, respectively. The sorption coefficient obtained using the batch method was comparable (K(f) for sandy loam soil = 7. 9 microg(1)(-)(1/)(n)() mL(1/)(n)() g(-)(1)) to that obtained using the SFE technique. On the basis of these results, pesticide sorption as a function of water content must be known to more accurately predict pesticide transport through soils.  相似文献   

11.
Abstract

The sorption of twelve pesticides (alachlor, atrazine, carbofuran, 2,4—D, 2,4—DB, methyl parathion, metoxuron, monuron, prometryne, propanil, silvex and spergon) was studied on two soil samples with a different carbonate content and treated with evergreen oak (Quercus ilex L. subsp. ballota) biomass at successive humification stages. The direct interaction between the above pesticides and lignocellulosic materials was also assayed independently. After the samples were suspended in 25 ppm pesticide solutions for 12 h, the concentrations in the supernatants were measured by derivatographic UV spectroscopy. The major fixations on the biomass of evergreen oak were found for spergon, prometryne and propanil. Except for atrazine, carbofuran, prometryne and silvex, composting the forest residue for 87 weeks significantly increased pesticide sorption. No correlations were found between the sorption values measured directly in the lignocellulosic materials and those in the soils amended with the latter, indicating the conspicuous influence of organo‐mineral interactions in the soil. Calcium carbonate played an important role in pesticide sorption: the lowest pesticide retentions were observed for the samples of the soil with the highest pH, where the addition of organic matter led to the greatest enhancements. The fixation of silvex and carbofuran increased considerably when the organic matter was added to the soil with the lowest pH, whereas in the calcic soil samples the major fixation corresponded to chlorinated phenoxy acids. Possible mechanisms involved in pesticide sorption in the systems studied are discussed.  相似文献   

12.
The effect of various oak wood seasoning methods, natural seasoning in open air, artificial seasoning in a kiln, and a mixed method that combines open air and kiln drying, on the chemical composition in American ( Quercus alba) and French ( Quercus petraea) oak was studied. The results confirm the evolution of ellagitannins in wood, low molecular polyphenols, and volatile compounds in relation to oak species and seasoning method. Natural seasoning in open air can be considered a superior method to mixed or artificial drying for wood seasoning in cooperage. It was more effective in reducing the excess of ellagitannins, especially in French oak wood. Moreover, the evolution of wood volatile compounds was more positive in the natural seasoning than mixed or artificial drying, since it led to woods with higher aromatic potential (larger concentrations of compounds such as volatile phenols, phenolic aldehydes, furanic compounds, and cis- and trans-beta-methyl-gamma-octalactones) than mixed or artificial methods. However, the three seasoning methods showed similar effectiveness regarding the desired reduction of off-flavors compounds.  相似文献   

13.
Abstract

The adsorption of selenium (Se) in the selenate form and its desorption by phosphate in four soils with different physiochemical properties were studied in the laboratory. To determine adsorption isotherms for selenate 25 mL of solutions containing 1 to 100 ppm of Se were added to 2.5 g of soil. Desorption isotherms were determined by resuspending the samples in phosphate solution. The selenate sorption process was adequately described by the Freundlich equation. In pine forest and woodland soils, characterized by the highest organic matter content and cation exchange capacity (CEC) values, the isotherms were classified as L type, since the amount of Se sorbed appeared to move towards saturation. The organic matter content played the most important part in the adsorption of Se, while pH appeared to have a small effect on the ability of the soil to adsorb Se. The high CaCO3 content of the pine forest soil may have contributed in increasing the Se adsorption notwithstanding the high pH value. The cultivated and arable soils showed a reduced sorption capacity. The sorption could be described by an S type curve. At low concentrations of Se the affinity of the solid phase was less than that of the liquid phase. By increasing the concentration of Se in solution, the affinity of the solid phase increased and the sorption was favored. Selenate desorption by water was negligible, whereas the amount of Se desorbed by phosphate varied among the different soils. The desorption experiments indicated that a significant portion of the sorbed Se was irreversibly retained. This suggests the existence of linkages which allow the release of Se in the soil solution only after physico‐chemical variation such as exchange with phosphate ions.  相似文献   

14.
A method for the screening of potential natural oak lactone precursors in oak wood extracts using LC-MS/MS combined with information-dependent acquisition was developed. The method was applied to extracts of American and French oak woods. As a result, cis-3-methyl-4-galloyloxyoctanoic acid (ring-opened cis-oak lactone gallate), (3S,4S)- and (3S,4R)-3-methyl-4-O-beta-D-glucopyranosyloctanoic acid (ring-opened cis- and trans-oak lactone glucoside), and (3S,4S)-3-methyl-4-O-(6'-O-galloyl)-beta-D-glucopyranosyloctanoic acid (ring-opened cis-oak lactone galloylglucoside) were identified as natural oak lactone precursors in the extracts by comparison with the respective synthetic reference compounds. In addition, the ring-opened oak lactone rutinoside was tentatively identified in the extracts. Three apparent isomers of the ring-opened cis-oak lactone galloylglucoside were also observed.  相似文献   

15.
Sorption-desorption of the azole fungicide triadimefon [1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2, 4-triazol-1-yl)-2-butanone] on eight soils and a series of single, binary, and ternary model soil colloids was determined using the batch equilibration technique. Regression analysis between Freundlich sorption coefficients (K(f)) and soil properties suggested that both clay and organic C (OC) were important in triadimefon sorption by soils, with increasing importance of clay for soils with high clay and relatively low OC contents. Triadimefon sorption coefficients on soil were not significantly affected by the concentration of electrolyte or the presence of soluble soil material in solution, but they were highly dependent on the soil:solution ratio due to the nonlinearity of triadimefon sorption on soil. Freundlich sorption isotherms slopes were very similar for all soils (0.75 +/- 0.02). Desorption did not greatly depend on the concentration at which it was determined and showed higher hysteresis for more sorptive soils. Results of triadimefon sorption on model sorbents supported that both humic acid and montmorillonite-type clay constituents contribute to triadimefon retention by soil colloids.  相似文献   

16.
The herbicide terbuthylazine is widely used within the EU; however, its frequent detection in surface and groundwater, together with its intrinsic toxicological properties, may pose a risk both for human and environmental health. Organic amendments have recently been proposed as a possible herbicide sorbent in soil, in order to limit herbicide movement from soil to water. The environmental fate of terbuthylazine depends not only in its mobility but also in its persistence. The latter is directly dependent on microbial degradation. For this reason, the effects of pine and oak residues on terbuthylazine soil microbial community functioning and on the potential of this community for terbuthylazine degradation were studied. For this purpose, degradation kinetics, soil dehydrogenase activity and the number of live bacteria were assessed in a clay loam soil treated with terbuthylazine and either amended with pine or oak wood or unamended (sterilised and non-sterilised). At day 65, 85?% of the herbicide applied still persisted in the sterile soil, 73?% in the pine-amended one and 63?% in the oak-amended and unamended ones. Pine residues increased the sorption of terbuthylazine to soil and hampered microbial degradation owing to its high terbuthylazine sorption capacity and a decrease in the bioavailability of the herbicide. On the contrary, in the presence of oak residues, the herbicide sorption did not increase significantly. The overall results confirm the active role of the soil microbial community in terbuthylazine degradation in amended and unamended soils and in a liquid enrichment culture performed using an aliquot of the same soil as the inoculum. In this clay loam soil, in the absence of amendments, the herbicide was found to be quite persistent (t 1/2?>?95?days), while in the enrichment culture, the same natural soil bacterial community was able to halve terbuthylazine in 24?days. The high terbuthylazine persistence in this soil was presumably ascribable to its texture and in particular to the mineralogy of the clay fraction.  相似文献   

17.
通过有机插层法对蒙脱土、高岭土进行改性,制备成纳米型蒙脱土、高岭土,并利用制备的纳米型高岭土、蒙脱土对溶液中铜的吸附效果及吸附机理进行了研究。结果表明,纳米型蒙脱土和高岭土对溶液中的铜具有很好的去除效果,其吸附等温线可以用Langmuir和Freundlich方程进行拟合。相比而言,蒙脱土比高岭土具有较高的吸附量和吸附亲和力参数。在溶液中铜离子浓度低于120 mg/L时,纳米型蒙脱土、高岭土对铜的最大去除率分别达到99.5%和94.3%,对溶液中铜的去除率随铜离子浓度增加和溶液的pH降低而降低。  相似文献   

18.
Adsorption and mobility of the herbicide linuron (3-3, 4-dichlorophenyl-1-methoxy-1-methylurea) in 35 irrigated soils with organic matter (OM) contents in the 0.43-2.59% range and in four natural soils with OM contents in the 4.16-11.69% range were studied using the batch equilibration technique. The adsorption isotherms were found to conform to the Freundlich adsorption equation. The Freundlich constant, K, and the distribution coefficient, K(d), were seen to be highly significantly correlated (p < 0.001) with the OM content when all soils or only those with an OM content above 2% were considered. There was also a significant correlation of K and K(d) with the OM content (p < 0.05) and of K(d) with the clay and silt plus clay contents (p < 0.1) when the soils with a OM content below 2% were considered. On the basis of the R(f)() values obtained by soil TLC, the pesticide was found to be slightly mobile in 77% and moderately mobile in 23% of the soils studied. The results of the leaching of linuron in soil columns unmodified and modified with two organic agricultural amendments, a city refuse compost, and two surfactants (one of them cationic and the other anionic) revealed that the leaching rate and the mass transfer of the herbicide to water were affected, increasing or decreasing according to the characteristics of the amendments and the doses added. These results also point to the usefulness of selected organic materials and surfactants in the development of physicochemical methods for preventing the pollution of soils, sediments and aquifers by hydrophobic pesticides.  相似文献   

19.
The efficacy and fate of pesticides in soil strongly depend on sorption reversibility that is known to decrease with increasing contact time (aging). We elucidated the aging dynamics of eight different pesticides in two contrasting agricultural soils of tropical Brazil (Ustox and Psamments), using batch equilibrium experiments and sequential extractions of field samples. Adsorption was best described by Langmuir isotherms for the entire and by Freundlich equations for the lower concentration range. In field samples, water extractable pesticide fractions mostly dissipated at least twice as fast as did the solvent extractable fractions. Hence, in comparison to 0 days K(OC) values, measured field K(OC) values were higher by a factor of 2.6-38 for the clayey Ustox and 2.1-72 for the sandy Psamments toward the end of the experimental period at 80 days after application. The extent of such aging basically increased with increasing polarity of the pesticide. An absolute enrichment of polar pesticides within the final exhaustive acetone--ethyl acetate--water extracts was observed during the experimental period, so that we may deduce that pesticides had redistributed into stronger sorption sites. The time course of the K(OC) development was well-described using a semiempirical equation, which had been employed for temperate soils before.  相似文献   

20.
《Geoderma》2007,137(3-4):269-278
Cadmium sorption, basic soil properties and water retention were jointly analyzed in an acidic sandy podzol under pine forest in the North of Germany. Samples were taken along a 10 m transect at a depth of 0.15 m with a sample-support of 0.15 m. The small-scale Cd sorption variability was upscaled in two steps. Firstly, it was simplified and, secondly, aggregated from the sample to the pedon scale. We evaluated different models to simplify Cd sorption variability at different levels of spatial aggregation. Our evaluation method was the numerical simulation of Cd transport in the topsoil where the variability of Cd sorption is the key input.We described Cd sorption with the Freundlich parameterization and tested three models to simplify its spatial variability. The reference model (model 1) had two and the simplified models only one spatially variable sorption parameter. Model 2 varied the parameter Kf of the Freundlich parameterization and set the exponent constant. Model 3 expressed only the linear variability of sorption. Each sample had a scaling factor that related to a constant sorption reference function. The Freundlich parameter Kf of the third simplification model (model 4), was derived by a local pedotransfer function. Its variability was, therefore, filtered by the available variation of a limited number of basic soil properties.The average sorption was at all aggregation levels not significantly different between the models. However, the corresponding uncertainty was smallest for model 3, intermediate for model 4 and largest for model 2. We evaluated the different sorption variability models with the simulation of Cd transport. The mean Cd concentrations in the topsoil predicted by the different models were statistically not different. However, at all support scales, the uncertainties of the predicted mean Cd concentrations and the RMSE's were smallest when model 3 was used, where the error was about 20% at the sample scale and decreased to below 10% at the pedon scale. Therefore, if measurements of sorption isotherms are available, we recommend to use model 3 to derive the mean sorption behavior with minimal uncertainty.  相似文献   

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