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1.
The role of biodegradation and photo-oxidation in the transformation of terrigenous organic matter 总被引:1,自引:0,他引:1
Xiaojuan Feng Katherine M. Hills Andr J. Simpson Joann K. Whalen Myrna J. Simpson 《Organic Geochemistry》2011,42(3):262-274
Microbial and photochemical decomposition are two major processes regulating organic matter (OM) transformation in the global carbon cycle. However, photo-oxidation is not as well understood as biodegradation in terms of its impact on OM alteration in terrigenous environments. We examined microbial and photochemical transformation of OM and lignin derived phenols in two plant litters (corn leaves and pine needles). Plant litter was incubated in the laboratory over 3 months and compositional changes to OM were measured using nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry. We also examined the susceptibility of soil organic matter (SOM) to ultraviolet (UV) radiation. Solid-state 13C NMR spectra showed that O-alkyl type structures (mainly from carbohydrates) decreased during biodegradation and the loss of small carbohydrates and aliphatic molecules was observed by solution-state 1H NMR spectra of water extractable OM from biodegraded litters. Photochemical products were detected in the aliphatic regions of NaOH extracts from both litter samples by solution-state 1H NMR. Photo-oxidation also increased the solubility of SOM, which was attributed to the enhanced oxidation of lignin derived phenols and photochemical degradation of macromolecular SOM species (as observed by diffusion edited 1H NMR). Overall, our data collectively suggests that while biodegradation predominates in litter decomposition, photo-oxidation alters litter OM chemistry and plays a role in destabilizing SOM in soils exposed to UV radiation. 相似文献
2.
Hydrodynamic study of karstic and intergranular aquifers using isotope geochemistry in Basara basin, Sulaimani, North-Eastern Iraq 总被引:1,自引:1,他引:0
The study area is located in the border of the high and low folded zone having a semi-arid climate area. This study initiated in 2009–2010, deals essentially with the investigation of the stable isotope (18O and deuterium 2H) as well as radioactive isotope represented by tritium 3H in rain, carbonate springs, intergranular aquifer, and surface water in order to investigate the source and relative ages of the groundwater and to show the influence of the altitude variations of the isotope composition. In this study and for the first time in the area, a local meteoric water line have been drawn with an empirical formula δ 2H?=?7.7δ 18O?+?14.4. The δ 18O–altitude effect was determined using isotopic data for several samples taken from groundwater and surface water; it was approximated at ?0.79?‰/100 m for the entire area of the study. The output of the tritium concentrations in the springs and water well samples revealed to the conclusion that the values closely resembles to the present time tritium concentration in precipitation. 相似文献
3.
The 18O/16O ratio of CO2 is a potentially powerful tracer of carbon dioxide fluxes from the soil to the atmosphere, which is influenced by complex interactions involving both biotic and abiotic soil processes. We use a simplified experimental approach and numerical simulations to examine in isolation the 18O exchange between CO2 and soil water associated with the abiotic invasion of atmospheric CO2 into soil. This allowed us to verify, in particular, whether the 18O of the retro-diffusion flux of CO2 from the soil reflects 18O equilibration with water at the soil surface, or at some depth. Sterile soil samples with known water isotopic composition were placed in a closed box attached to a specially designed flow chamber and the changes in δ18O of CO2 between the chamber inlet and outlet, due only to invasion effects, were determined. Numerical simulations constrained by the laboratory gas exchange measurements indicated that between the two commonly used diffusion models [Penman, H.L. (1940). Gas and vapor movements in soil, 1: the diffusion of vapors through porous solids. Int. J. Agric. Sci.30, 437-462; Moldrup, P., Olesen, T., Yamaguchi, T., Schjonning, P., Rolston, D.E. (1999). Modeling diffusion and reaction in soils, IX, the Backingham-Burdine-Campbell equation for gas diffusivity in undisturbed soil. Soil Sci.164, 542-551], only the former provided good agreement with the measurements over a wide range of soil water contents. Based on the model calculations constrained by experimental data, and on comparison of characteristic diffusion/reaction times, we conclude that the depth required for full CO2-water 18O equilibration ranges between 2 and 8.5 cm. The depth depends, in order of importance, on (1) soil moisture content; (2) temperature, which dominates the rate of hydration isotopic exchange; (3) CO2 residence time, which is determined by the time of replacement of the column air above the soil; and (4) soil structure, including porosity, tortuosity and grain size, with the later probably influencing the water surface area exposed to CO2 exchange. Using field data from a semi-arid forest site in Israel, numerical simulations indicated that the 18O full equilibrium depth varied at this site between 4 cm (January) and 8 cm (November), being sensitive mostly to temperature and soil water content. Deepening of the equilibration depth as the soil dries should limit the effects of 18O evaporative enrichment at the surface on the isotopic composition of the soil-atmosphere CO2 flux. 相似文献
4.
Céline Defouilloy Rémi Duhamel François Robert 《Geostandards and Geoanalytical Research》2013,37(4):417-427
The isotopic ratio of hydrogen was measured in an iron meteorite and terrestrial native iron using an IMS 3f ion microprobe. The extraterrestrial D/H ratio (93 ± 9 × 10?6) was close to the terrestrial value (105 ± 6 × 10?6), and both samples had low H concentrations (7 ± 4 and 33 ± 11 ng g?1 for the iron meteorite and the terrestrial sample, respectively). Experiments on artificially D‐enriched samples showed that the measured hydrogen signal is a combination of indigenous H and terrestrial atmospheric contamination. This contamination comes from the isotope exchange reaction between water adsorbed on the sample surface and atmospheric water, and would be continuously added to the indigenous H in the ion crater by the adsorbed water sinking into the crater during sputtering. Experiments showed that this contamination represents up to 20% of the signal but was within the uncertainty of the measured D/H ratio. 相似文献
5.
《Applied Geochemistry》2006,21(10):1668-1673
The authors report a preliminary study of the light stable isotopic (δD, δ13C and δ18O) values for bulk archaeological birch bark tars, over a geographical (e.g. Greece to Norway) and chronological (9500–3000 BP) range. For δ13C an increase in fractionation with increase in latitude is observed in samples from Greece which are less depleted than those from northern Europe. There is no clear difference between the samples from northern Europe. There is no apparent trend in δ13C value with the 14C age of the sample. Due to biosynthetic fractionation all the samples are significantly depleted in 2H and enriched in 18O relative to the global meteoric water line. This study indicates that archaeological birch bark tar from Greece can be distinguished from those of northern Europe; this separation is probably based on the extreme geographical range of the samples examined here. But this does provide evidence that the birch bark tars were probably made locally rather than traded. 相似文献
6.
Hydrological characteristics of karstic groundwater in the northeast Viet Nam as studied by isotopic techniques 总被引:1,自引:0,他引:1
Dang Duc Nhan Nguyen Van Lam Ha Chu Ha Long Dao Dinh Thuan Dang Anh Minh Vo Thi Anh 《Environmental Earth Sciences》2013,70(2):521-529
The stable water isotopic composition (δ2H and δ18Ο), tritium (3H) activity, dissolved organic carbon, alkalinity, as well as the composition of carbon 13 (δ13C) in dissolved inorganic carbon (DIC) of 36 water samples taken from 16 resurgences in the northeast provinces of Viet Nam in the dry (Mar 2008) and rainy (June 2008) seasons were analyzed to elucidate hydrological characteristics of the karstic aquifers in the area. The stable water isotopic composition of the water samples collected clearly demonstrated that the karstic groundwater in the region was recharged from the local meteorological water. The tritium activity in the samples was found to be in between 3 and 4 TU, falling in the range of the 3H activity in the local precipitation and thus meaning that the traveling of recharge water to the resurgences was very short. Concentrated and diffuse allogenic recharges seem to be important sources of karstic groundwater in the study region. Water in the karstic aquifers could be classified into three types as: (a) water from karstic areas with dense vegetation cover that causes DIC be depleted in carbon 13 (13δ<?12‰ vs. Pee Dee Belemnite standard of Vienna, VPDB); (b) water from karstic areas with poor vegetation cover that originates DIC with carbon 13 composition ranging from ?11 to ?12‰; and (c) surface water from lakes, springs and rivers that has DIC with enriched carbon 13 (δ13C >?10‰). This implies that there are several sources of carbon dioxide contributing to the DIC in water of the karstic aquifers in the study region. Among other potential sources, the atmospheric CO2, CO2 from carbonate rock dissolution, biomineralization of soil organic matters and plant roots respiration seem to be important sources of the DIC in the waters of this region. The results show high vulnerability towards anthropogenic contaminants of karstic groundwater in the study region. 相似文献
7.
Twelve goethite samples with different degrees of substitution of Al for Fe were synthesized at 22-48 °C and pH values of 1.5-14 under closed system conditions and used to study the effects of Al substitution on the hydrogen isotopic fractionation between goethite and its ambient water. The syntheses followed two pathways: (1) Fe3+ hydrolysis in high pH aqueous solutions; (2) oxidation of Fe2+ to Fe3+ in mid to low pH solutions. XRD and SEM analyses indicated that, irrespective of temperature and pH, goethite was the predominant product of the syntheses in all of the experiments (with degrees of Al substitution as high as ∼13 mol %). “High temperature nonstoichiometric” (HTN) water is present in all of the samples and rapidly exchanges D/H with ambient vapor at room temperature. Uncertainties in the value of the apparent D/H fractionation factor (αe-v) between HTN water and ambient exchange water at 22 °C lead to significant uncertainties in determinations of the δD values of structural hydrogen (δDs) in goethites which contain high proportions of HTN water. As determined for the samples of this study, αe-v has a nominal value of 0.942 (±0.02). δDs values determined using an αe-v value of 0.942 indicate that Al substitution increases the δD value of structural hydrogen in goethite by about 1.4 (±0.4)‰ for each increase in Al of 1 mol %. This dependence on Al is of the same sign as, but somewhat larger in magnitude than, the effect of Al predicted by a published model (∼0.7‰ per mol % Al). The overall uncertainties in the current results suggest that an increase of ∼1‰ per mol % Al, as adopted by previous studies, may be a reasonable estimate with which to adjust δ Ds values of natural goethites to those of the pure FeOOH endmember and could be valid for degrees of Al substitution of up to at least 15 mol %. These synthesis experiments also yield a hydrogen isotopic fractionation factor (DαG-W) between pure goethite (α-FeOOH) and liquid water of 0.900 (±0.006), which is analytically indistinguishable from the published value of 0.905 (±0.004). Thus, use of an DαG-W value of 0.905 in applications to the FeOOH component of natural goethites is supported by the current study. 相似文献
8.
Assessment of interconnection between surface water and groundwater in Sawa Lake area,southern Iraq,using stable isotope technique 总被引:1,自引:0,他引:1
Interaction between surface water represented by the Euphrates River, natural springs, and Sawa Lake with groundwater (11 wells) in southern Iraq was investigated in this study. Water samples were collected for hydrochemistry and stable isotope (2H and 18O) analysis. Sampling of water from determined stations (10 stations along the Euphrates, 3 springs, and Sawa Lake) were carried out during two stages; the first was in October 2013(dry season) and the second one was in March 2014 (wet season). The aim of the research is to assess the interaction of groundwater–surface water, which includes Al-Atshan River (branch of the Euphrates River), Sawa Lake, and the groundwater in the study area by using hydrochemistry and stable isotope techniques. The results indicate that surface waters have a different type of water from that of groundwater. In δ 2H and δ 18O diagrams, all groundwater, springs, and Sawa Lake waters are plotted below the Global Meteoric Water Line (GMWL) and the local meteoric water line (LMWL) indicating the influence of evaporation processes and seasonal variation. The LMWL deviates by a d-excess about +13.71 toward the East Mediterranean meteoric water line (EMWL) indicating that the origin of the vapor source is the Mediterranean Sea. The river water has different isotopic compositions from that of groundwater, springs, and Sawa Lake. The final conclusion is that there is no clear influence of the groundwater on the river water while there is an intermixing between the groundwater in the different locations in the study area. 相似文献
9.
J. S. Chen X. X. Sun W. Z. Gu H. B. Tan W. B. Rao H. Z. Dong X. Y. Liu Z. G. Su 《Geochemistry International》2012,50(5):455-465
Despite its extreme aridity, the Badain Jaran Desert is rich in groundwater. In the southeastern part of the desert, it is
characterized by coexistence of high megadunes and a great number of lakes. Deuterium and oxygen 18 isotope compositions as
well as hydrochemistry of groundwater, lake water, soil water and river water were investigated in detail to gain an insight
into their relationships and the origin of the ground-water. The results show that the groundwater and the lake water are
genetically related, but unrelated to local precipitation and the leakage of Heine River at northern slope of Qilian mountain.
δD and δ18O values of deep soil water (lower than 40 cm) and groundwater plot on the same evaporation line E11, which shows that they
have the same recharge source. The point of intersection between E11 and LMWL suggests that the groundwater originates from
the water resource which has a weighted mean value that is lighter by some 6‰ δ18O than the local precipitation in Badain Jaran Desert. 3H data of water samples shows that the groundwater in Badain Jaran Desert originates from the water recharged after the nuclear
test. The deep fault zone underground maybe the water circulation channel based on Helium analysis of groundwater. The result
has guiding significance to rational exploitation and utilization of the local groundwater. 相似文献
10.
Friedemann Freund Heinz Wengeler Reinhard Martens 《Geochimica et cosmochimica acta》1982,46(10):1821-1829
Water dissolved in a nominally anhydrous oxide like MgO forms not only OH? ions, as is usually assumed, but also molecular H2 and peroxy anions O22?. The specific lattice site where this reaction occurs has been identified for the model-type MgO structure: it is the fully OH? compensated cation vacancy. In partially deuterated synthetic MgO, molecular D2 forms preferentially to H2, by a factor of the order of 4. Three methods have been used to study this very large D/H fractionation experimentally: mass spectrometry, electron spin resonance and infrared spectroscopy. All give consistent results and confirm that internal D/H fractionation occurs and is a function of the temperature. Theoretically the D/H fractionation is explained by the lower zeropoint energy of D2 with respect to H2, amplified by secondary processes through which the molecular hydrogen species become mobilized and eventually lost via diffusion. The possible consequences of such internal D/H fractionation processes are indicated for the interpretation of water and hydrogen release patterns, with varying D/H ratios, from terrestrial and extraterrestrial samples. 相似文献
11.
Hydrogen and oxygen stable isotope in water bodies is a widely used tracer in hydrological process studies. In order to provide a basis for stable isotopic characteristics in different water bodies at the high mountainous area of northwestern Tibetan Plateau, samples for river water, groundwater, soil water, and plant water were collected from 10 sites in the Qilian Mountains during July and August 2015, and then analyzed for δ18O and δD, respectively. Results indicated that the stable isotope values of soil water were mostly plotted below the global meteoric water line (GMWL), which suggested that evaporation made heavy isotope in soil water enriched. The stable isotope values of soil water were quite different in the top soil layer, but tended to be uniform in the deep soil layer. Furthermore, the stable isotope difference of plant water is related to climatic conditions, water isotopes utilized by plant, plant species, growing season, and so on. Additionally, the variation of δ18O values for river water and groundwater relatively coincided with each other, and this showed the recharge sources of above two water bodies may be consistent. The stable isotope values of river water and groundwater were mainly plotted on the upper left of GMWL, and the lower level of isotopic fractionation due to weak evaporation may accountable for this. 相似文献
12.
N. I. Bezmen V. A. Zharikov M. B. Epelbaum V. O. Zavelsky Y. P. Dikov N. I. Suk S. K. Koshemchuk 《Contributions to Mineralogy and Petrology》1991,109(1):89-97
The H2O and H2 solubilities in an albite melt at 1200° C and 2 kbar over the entire range of gas phase composition, from pure hydrogen to pure water were studied in gas-media pressure vessels. The water solubility initially increases with increasing hydrogen content until a maximum of 9.19 wt% H2O atXH
2
v
=0.1 is reached, withXH
2
v
>0.1 the water solubility decreases. The hydrogen solubility curve has a maximum atXH
2
v
=0.42 where the concentration reaches 0.206 wt% H2O. Over the entire compositional range1H NMR (nuclear magnetic resonance) spectra show distinct absorption lines due to protons bound to OH groups and to isolated firmly bound water molecules. In NMR and Raman spectra there were no bands attributable to the H–H vibrations of molecular hydrogen. The X-ray photo-electronic spectra of hydrogen-bearing glasses show the Si2p (99 eV) band which corresponds to the zero-valency silicon. The formation of OH groups and molecular water during interaction between hydrogen-bearing fluids and melts under reducing conditions has a qualitative effect, the same as for water dissolution. Another point of interest is that hydrogen-bearing melts undergo more depolymerization than do hydrous melts. 相似文献
13.
H. Hagemann A. Lucken H. Bill J. Gysler-Sanz H. A. Stalder 《Physics and Chemistry of Minerals》1990,17(5):395-401
The polarized Raman spectra of four different beryl crystals were studied at room temperature in the range from 30 to 4000 cm-1. The spectra show significant differences between the samples studied, and corrections are proposed for the reference Raman spectra of beryl previously reported by Adams and Gardner (1974). Type II water is observed in two crystals; the corresponding symmetric Raman stretching band at 3595 cm-1 is extremely strong for an impurity (about 20% of the strongest beryl lattice mode). Another, sharper, band of similar intensity at 3605 cm-1 could possibly originate from a hydroxyl stretching mode. Additional weaker bands are observed around 1600 cm-1 and 3600–3750 cm-1. The first polarized Raman spectra of bazzite are presented and discussed. 相似文献
14.
Recharge sources and hydrogeochemical evolution of groundwater in the coal-mining district of Jiaozuo, China 总被引:2,自引:1,他引:1
Investigations in the Jiaozuo coal-mining district (China) aim to link water-inrush aquifers with the sources of groundwater recharge. Concentrations of TDS, HCO 3 – , Cl– and Na+ in the groundwater samples gradually decrease with increasing depth; in contrast, the factor 1 value of the Q-mode analysis gradually increases, which indicates that the deep groundwater may upflow, recharging the aquifers near the faulted zone. Some groundwater samples (above the local meteoric water line and ‘evaporation line 1’) may originate from recharge by infiltrating local rainfall. Spring and river samples are symmetrically distributed on the regression line of the Ordovician and Carboniferous limestone aquifer groundwater (δ2H?=?3.76?×?δ18O?–?31.77) and may, therefore, originate from groundwater recharge in the northern Taihang mountains. This mechanism is supported by the observation that groundwater levels change with rainfall. According to radiocarbon residence-time estimates, two groundwater sample sites may have been recharged during the late glacial stage. 相似文献
15.
To obtain information on the contribution of aromatic fragments to the chemical structure of humic substances, we carried out a study on the [1H]NMR and [13C]NMR spectra of humic and fulvic acids and their oxidative degradation products extracted from an Andosol soil.[1H]NMR spectra of all organic fractions present considerable adsorption between 7.4 and 8.8 ppm, due to the presence of aromatic protons.The percentages of aromatic protons in respect to the total amount of protons are as follows: FA 20%, HA 19%, degraded FA < 12%, degraded HA 14%. The values indicate that the contribution of aromatic structures to the humic substances is significant, also considering that they are highly substituted.The degraded fractions contain smaller amounts of aromatic protons, because degradation causes the opening of the aromatic rings. Thus results obtained from the degradation do not seem to be reliable for defining the importance of aromatic structures in humic substances.Also the [13C]NMR spectra show signals in the aromatic region which derive from unsubstituted carbon atoms, while signals originating from tertiary carbon atoms merge with the noise. We believe that, at present, [1H]NMR spectroscopy is more suited for studying the role played by aromatic compounds in organic soil fractions. 相似文献
16.
Juan Pablo de Rosas Alexander Dario Esquivel Diego Martinez Heimann Agustin E. Negri Flavia Lohaiza Diego Leonardo Valladares Alejandro I. Zavala Hugo Huck Jimena Juri Ayub 《Environmental Earth Sciences》2018,77(16):587
This work presents the results of a soil erosion study using the 7Be technique. This technique estimates the water erosion/deposition from the comparison between 7Be soil content of a reference site and an eroded or sedimented site. The soil samples were collected from an agricultural area of the semiarid region of Argentina near San Luis City, which has a marked rainfall season. The area has been used for crop cultivation, being subjected to plowing practices. The 7Be in the Reference Site was in the first centimeter of soil, showing the typical exponential decreasing of 7Be soil content with depth, with the 7Be inventories value being 340?±?50 Bq m?2 for the dry season and 571?±?48 Bq m?2 for the rainy season. The 7Be technique was applied to a potential eroded site subjected to traditional tillage practices (plowing). A net soil erosion value of 13.5 t ha?1 (1.35 kg m?2) was obtained. From the assumptions of the applied technique, we can draw the inference that this erosion was caused by rains produced in the month prior to the date of soil sampling. 相似文献
17.
Paul F. McMillan Brent T. Poe Thomas R. Stanton Richard L. Remmele 《Physics and Chemistry of Minerals》1993,19(7):454-459
We have obtained high quality Raman spectra for two H/D isotopically substituted hydrous aluminosilicate glasses with compositions along the NaAlSi3O8-SiO2 join. Consistent with the results of previous studies, the isotope shift for the band near 900 cm–1, whose intensity grows with increasing water content, is extremely small: v
h
/v
d
= 1.004 ± 0.004. The lack of a definite H/D isotope shift for this band does not, however, preclude its association with a vibration of a hydrous species in the glass, because of likely strong coupling between different vibrational modes of hydrated framework species. The 900 cm–1 band could well be due to a T — OH (T = Si, Al) stretching or bending vibration in the hydrous glass, as required by the presence of a combination band near 4500 cm–1 in near-infrared spectra. 相似文献
18.
The Southeast and the US Gulf Coast in particular are notably lacking isotope data in the water cycle despite the fact that moisture transport from the Gulf of Mexico (GOM) has a considerable influence on both regional and continental rainfall patterns. This study reports time-series of oxygen and hydrogen isotopes acquired over a 3-year period (2005-2008) from GOM-derived rainfall, cave dripwater and shallow groundwaters, and offers valuable insights on the links between factors controlling regional rainfall and the ubiquitous karst hydrology.Amount-weighted mean monthly rainwater δ18O and δD values in Tuscaloosa, Alabama range from −1.5 to −8.3‰ and −1.2 to −49.5‰, respectively, and show mean seasonal amplitudes of ∼4‰ (δ18O) and ∼25‰ (δD). In comparison d-excess values display large seasonal amplitudes of 10-20‰ resulting from differences in the degree of evaporation from falling raindrops between summer and winter months, and correlate well with the coeval air temperature (r2 = 0.59; p < 0.05). Deviations of the Gulf Coast Meteoric Water Line (GCMWL) slope and d-excess from the global meteoric water line (GMWL) are attributed to different rates of evaporation after condensation, and to humidity contrast between the cloud boundary layer and the surrounding atmosphere in the vapor source region, respectively. Rainfall amounts declined during the study interval from an excessive “wet” year, ascribed to six tropical storms incursions during an unusually active hurricane season in 2005, to an onset of a regional drought during 2007-2008 with monthly rainfall amounts substantially below normal values (30-year monthly means). An interannual trend of 18O and 2H enrichments is discerned from 2005 to 2008 (1.4‰ and 11.6‰, respectively) coeval with the decline in rainfall amounts.Dripwater samples from nearby DeSoto Caverns show weak δ18O and δD seasonal variations and record only 20% and 51% of the 18O and 2H enrichments, respectively, discerned in the rainwater 3-year time-trends. The seasonal and interannual amplitude attenuations in the dripwaters are attributed to a relatively thick overlying bedrock (∼30-40 m) and a relatively large, well-mixed, epikarst-storage reservoir. Residence time of water in the cave’s epikarst is estimated to be 1-3 months based on high-resolution flow-rate data.Our investigation suggests that global atmospheric circulation patterns (ENSO and Bermuda High) likely govern the interannual δ18O and δD isotope trends discerned in the water cycle compartments but much longer time-series are required to confirm our conjectures. The results of this study form a solid basis for future acquisition and interpretation of climate proxy records from regional speleothems. 相似文献
19.
Ab initio, molecular orbital calculations have been performed on a variety of hypothetical aluminosilicate molecules to investigate relationships among composition, structure, and infrared spectra of OH. Vibrational analyses of the full-optimized molecular geometries at the 3–21G** level were performed with Gaussian 92 to determine theoretical infrared spectra. Theoretical infrared OH frequencies, ν(OH), shift 10 to 100 cm?1 with ionic substitutions. The inverse correlation of theoretical infrared OH intensities with OH stretching frequencies in these aluminosilicate molecules is similar to that observed for aluminosilicate glasses (Paterson 1982). O-H bond lengths, H-bond distances, and H?nd angles correlate with frequency. The dominant factor affecting ν(OH) is the H-bond distance, if this distance is less than 2 Å. Beyond H-bond distances of 2 Å, structural and compositional effects exert competitive influences on ν(OH). 相似文献