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1.
This work illustrates the toxicological impact of pesticide methyl parathion (MP) (dust—2 % active ingredient, a.i.) on growth and reproduction performance in tropical earthworms: Metaphire posthuma (endogeic), Lampito mauritii (anecic) and Allolobophora parva (epigeic). A total of three concentrations (a.i. g kg?1 dry test soil), 1.00 (T 1), 1.125 (T 2) and 2.25 (T 3) of MP, were applied in test substrate to examine the impact on mortality, individual live weight changes and reproduction patterns in test species over 60 days under laboratory conditions. MP caused significant mortality in all tested species, and median lethal dose (LD50) for L. mauritii, M. posthuma and A. parva was 24.85, 23.64 and 22.67 mg a.i., respectively. The individual live weight loss was 27.0–37.0 % in L. mauritii, 36.0–57.1 % in M. posthuma and 1.2–11.0 % in A. parva in different test concentrations. The pesticide-exposed worms produced less cocoons than control, but in L. mauritii, an unusual reproduction (hormesis) was recorded. Results suggested the species-specific toxicity of MP against tropical earthworms.  相似文献   

2.
The kinetics of Mn(II) oxidation by the bacterium Leptothrix discophora SS1 was investigated in this research. Cells were grown in a minimal mineral salts medium in which chemical speciation was well defined. Mn(II) oxidation was observed in a bioreactor under controlled conditions with pH, O2, and temperature regulation. Mn(II) oxidation experiments were performed at cell concentrations between 24 mg/L and 35 mg/L, over a pH range from 6 to 8.5, between temperatures of 10°C and 40°C, over a dissolved oxygen range of 0 to 8.05 mg/L, and with L. discophora SS1 cells that were grown in the presence of Cu concentrations ranging from zero to 0.1 μM. Mn(II) oxidation rates were determined when the cultures grew to stationary phase and were found to be directly proportional to O2 and cell concentrations over the ranges investigated. The optimum pH for Mn(II) oxidation was approximately 7.5, and the optimum temperature was 30°C. A Cu level as low as 0.02 μM was found to inhibit the growth rate and yield of L. discophora SS1 observed in shake flasks, while Cu levels between 0.02 and 0.1 μM stimulated the Mn(II) oxidation rate observed in bioreactors. An overall rate law for Mn(II) oxidation by L. discophora as a function of pH, temperature, dissolved oxygen concentration (D.O.), and Cu concentration is proposed. At circumneutral pH, the rate of biologically mediated Mn(II) oxidation is likely to exceed homogeneous abiotic Mn(II) oxidation at relatively low (≈μg/L) concentrations of Mn oxidizing bacteria.  相似文献   

3.
Assessment of chemistry of groundwater infiltrated by pit-toilet leachate and contaminant removal by vadose zone form the focus of this study. The study area is Mulbagal Town in Karnataka State, India. Groundwater level measurements and estimation of unsaturated permeability indicated that the leachate recharged the groundwater inside the town at the rate of 1 m/day. The average nitrate concentration of groundwater inside the town (148 mg/L) was three times larger than the permissible limit (45 mg/L), while the average nitrate concentration of groundwater outside the town (30 mg/L) was below the permissible limit. The groundwater inside the town exhibited E. coli contamination, while groundwater outside the town was free of pathogen contamination. Infiltration of alkalis (Na+, K+) and strong acids (Cl?, SO4 2?) caused the mixed Ca–Mg–Cl type (60 %) and Na–Cl type (28 %) facies to predominate groundwater inside the town, while, Ca–HCO3 (35 %), mixed Ca–Mg–Cl type (35 %) and mixed Ca–Na–HCO3 type (28 %) facies predominated groundwater outside/periphery of town. Reductions in E. coli and nitrate concentrations with vadose zone thickness indicated its participation in contaminant removal. A 4-m thickness of unsaturated sand + soft, disintegrated weathered rock deposit facilitates the removal of 1 log of E. coli pathogen. The anoxic conditions prevailing in the deeper layers of the vadose zone (>19 m thickness) favor denitrification resulting in lower nitrate concentrations (28–96 mg/L) in deeper water tables (located at depths of ?29 to ?39 m).  相似文献   

4.
The objective of this study was to determine the influence of a range of salinities (5%., 15%., and 25%.) on the acute toxicity of atrazine to nauplii of the copepodEurytemora affinis and larvae of the sheepshead minnow,Cyprinodon variegatus. Ninety-six-hour LC50 values for the copepod were 0.5 mg 1?1, 2.6 mg 1?1, and 13.2 mg 1?1 at salimities of 5%., 15%. and 25%. respectively. A comparison of LC50 values between adjacent salinities showed a statistical difference between 15%. and 25%. but not between 5%. and 15%.. Atrazine was more toxic toE. affinis at the lowest salinity. The 96-h LC50s for the sheepshead minnow were 16.2 mg 1?1, 2.3 mg 1?1, and 2.0 mg 1?1 at salinities of 5%., 15%., and 25%., respectively. There was a statistical difference between LC50 values at 5%. and 15%. but not between 15%. and 25%.. In contrast toE. affinis results, atrazine was more toxic toC. variegatus at the highest salinity. The toxicity data from these species suggest that development of estuarine water quality criteria is warranted.  相似文献   

5.
Passive treatment systems are widely used for remediation of acid mine drainage (AMD), but existing designs are prone to clogging or loss of reactivity due to Al- and Fe-precipitates when treating water with high Al and heavy metal concentrations. Dispersed alkaline substrate (DAS) mixed from a fine-grained alkaline reagent (e.g. calcite sand) and a coarse inert matrix (e.g. wood chips) had shown high reactivity and good hydraulic properties in previous laboratory column tests. In the present study, DAS was tested at pilot field scale in the Iberian Pyrite Belt (SW Spain) on metal mine drainage with pH near 3.3, net acidity 1400–1650 mg/L as CaCO3, and mean concentrations of 317 mg/L Fe (95% Fe(II)), 311 mg/L Zn, 74 mg/L Al, 20 mg/L Mn, and 1.5–0.1 mg/L Cu, Co, Ni, Cd, As and Pb. The DAS-tank removed an average of 870 mg/L net acidity as CaCO3 (56% of inflow), 25% Fe, 93% Al, 5% Zn, 95% Cu, 99% As, 98% Pb, and 14% Cd, but no Mn, Ni or Co. Average gross drain pipe alkalinity was 181 mg/L as CaCO3, which increased total Fe removal to 153 mg/L (48%) in subsequent sedimentation ponds. Unfortunately, the tank suffered clogging problems due to the formation of a hardpan of Al-rich precipitates. DAS lifetime could probably be increased by lowering Al-loads.  相似文献   

6.
In this study, the joint effects of Cd(Ⅱ), Pb(Ⅱ) and atrazine (ATR) on Solidago Canadensis L. were investigated. The results showed that soil containing Cd, Pb and ATR could inhibit root elongation of Solidago Canadensis L., and that there was a positive linear relationship between the inhibitory rate of root elongation and the concentrations of Pb(Ⅱ). The mixture of Cd(Ⅱ) and Pb(Ⅱ)-ATR in soil showed a significant adverse effect on root and shoot biomass of Solidago Canadensis L. Acetylsalicylic acid (ASA) contents increased slightly at the lower concentrations of Cd(Ⅱ)-ATR, then decreased when Cd(Ⅱ)-ATR concentrations were higher than those of 1.0 TUmix(Cd+ATR). The toxic effect of Pb(Ⅱ)-ATR on the ASA contents of Solidago Canadensis L. was greater than that of Cd(Ⅱ)-ATR. Soluble sugar contents firstly decreased and then increased with increasing concentrations of Cd(Ⅱ)-ATR and displayed fluctuation with increasing concentrations of Pb(Ⅱ)-ATR. Total protein contents in-creased with increasing concentrations of Cd(Ⅱ) and Pb(Ⅱ)-ATR , relative to the control sample. The NP-SH con-tents showed a significant increase up to 12.2 mg/gfw of Cd(Ⅱ)-ATR, followed by a significant decline to 4.5 mg/gfw after 14 days of exposure. The effect of Pb(Ⅱ)-ATR was similar to that of Cd(Ⅱ)-ATR but the amount of NP-SH was not higher than that of Cd(Ⅱ)-ATR.  相似文献   

7.
This study examined the effects of humic acids (HA) and Fe(III)–HA complex on the photodegradation of atrazine, one of the most widely used herbicides. It was shown that the photolysis of atrazine proceeded via first-order reaction kinetics and that atrazine photodegradation was inhibited by the presence of HA, whereas the rate for atrazine photolysis was promoted in solutions containing both HA and Fe(III). Interactions of Fe(III) with HA were characterized by SEM, EDX, UV–Vis and FTIR, revealing that Fe(III)–HA complex was formed by ligand exchange between oxygen groups of HA and Fe(III). Using fluorescence spectrometry the stability constant (Kc) and the fraction of fluorophores available for complexation (f) were obtained as log Kc = 4.28 and f = 74%. Photoformed Fe(II) by ligand-to-metal charge-transfer (LMCT) within the Fe(III)–HA complex was the most important factor involved in photolysis of atrazine, since Fe(II) was the reactant to generate hydroxyl radical. Thus, the rate of atrazine photodegradation in natural sunlit waters is dependent on both the amount of iron present and the interaction between HA and iron.  相似文献   

8.
This study consisted of the determination of the trace metals and some physiochemical properties in drinking water samples from the Brong Ahafo region of the Republic of Ghana, where drinking water samples are not treated before it is consumed. The purpose was to ascertain the quality of water from these sources. Samples were taken from fifteen sampling points and analyzed for the following parameters Fe, Cu, Mn, Zn, Al, NO3 ?, NO2 ?, SO4 2, PO4 2?, and F? using the procedure outline in the palintest photometer method. The data showed the variation of the investigated parameters in samples as follows: pH 5.57-7.54, conductivity (EC) 35-1216 us/cm, turbidity 3.25-72.50 NTU,PO4 2?1 0.32-9.30 mg/L,F 0.32-1.05 mg/L,NO3 ? 0.09-0.99 mg/L,NO2 ? 0.006-0.114 mg/L, SO4 2? 3.33-8.02 mg/L, Cu 1.19-2.75 mg/L Fe 0.05-0.85mg/L, Zn 0.04-0.15 mg/L, Mn 0.003-0.011 mg/L and Al 0.05-0.15 mg/L. The concentrations of most of the investigated parameters in the drinking water samples from Brong Ahafo region were within the permissible limits of the World Health Organization drinking water quality guidelines. There were no correlations between metal concentrations in the drinking water samples.  相似文献   

9.
The relation between sinkhole density and water quality was investigated in seven selected carbonate aquifers in the eastern United States. Sinkhole density for these aquifers was grouped into high (>25 sinkholes/100 km2), medium (1–25 sinkholes/100 km2), or low (<1 sinkhole/100 km2) categories using a geographical information system that included four independent databases covering parts of Alabama, Florida, Missouri, Pennsylvania, and Tennessee. Field measurements and concentrations of major ions, nitrate, and selected pesticides in samples from 451 wells and 70 springs were included in the water-quality database. Data were collected as a part of the US Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program. Areas with high and medium sinkhole density had the greatest well depths and depths to water, the lowest concentrations of total dissolved solids and bicarbonate, the highest concentrations of dissolved oxygen, and the lowest partial pressure of CO2 compared to areas with low sinkhole density. These chemical indicators are consistent conceptually with a conduit-flow-dominated system in areas with a high density of sinkholes and a diffuse-flow-dominated system in areas with a low density of sinkholes. Higher cave density and spring discharge in Pennsylvania also support the concept that the high sinkhole density areas are dominated by conduit-flow systems. Concentrations of nitrate-N were significantly higher (p < 0.05) in areas with high and medium sinkhole density than in low sinkhole-density areas; when accounting for the variations in land use near the sampling sites, the high sinkhole-density area still had higher concentrations of nitrate-N than the low sinkhole-density area. Detection frequencies of atrazine, simazine, metolachlor, prometon, and the atrazine degradate deethylatrazine indicated a pattern similar to nitrate; highest pesticide detections were associated with high sinkhole-density areas. These patterns generally persisted when analyzing the detection frequency by land-use groups, particularly for agricultural land-use areas where pesticide use would be expected to be higher and more uniform areally compared to urban and forested areas. Although areas with agricultural land use and a high sinkhole density were most vulnerable (median nitrate-N concentration was 3.7 mg/L, 11% of samples exceeded 10 mg/L, and had the highest frequencies of pesticide detection), areas with agricultural land use and low sinkhole density still were vulnerable to contamination (median nitrate-N concentration was 1.5 mg/L, 8% of samples exceeded 10 mg/L, and had some of the highest frequencies of detections of pesticides). This may be due in part to incomplete or missing data regarding karst features (such as buried sinkholes, low-permeability material in bottom of sinkholes) that do not show up at the scales used for regional mapping and to inconsistent methods among states in karst feature delineation.  相似文献   

10.
The Ganges River water and riverbank shallow groundwater were studied during a single wet season using the hydrochemical and isotopic composition of its dissolved load. The dissolved concentrations of major ions (Cl?, SO4 2?, NO3 ?, HCO3 ?, Ca2+, Na+, Mg2+, and K+), trace elements (barium (Ba) and strontium (Sr)) and stable isotopes (O and D) were determined on samples collected from the Ganges River and its riverbank shallow aquifers. In the present study, the shallow groundwater differs significantly from the Ganges River water; it shows distinct high concentrations of Ca2+, Mg2+, HCO3 ?, Ba, and Sr due to water–rock interaction and this in particular suggests that the Ganges River may not contribute significantly to the riverbank shallow aquifers during wet season. Besides, the sum of the total cationic charge (∑+, in milliequivalents per liter) in the groundwater shows high values (2.48 to 13.91 meq/L, average 9.12 meq/L), which is much higher than the sum of the cations observed in the Ganges water (1.36 to 3.10 meq/L, average 1.94 meq/L). Finally, the more depleted stable isotopic (δ 18O and δ 2H) compositions of the Ganges River water are in contrast to those of the riverbank aquifer having enriched stable isotopic values during the wet season and the riverbank groundwater thus has a purely local origin from precipitation.  相似文献   

11.
A 10?5 M (2.2 ppm) concentration of atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) reduced the rate of photosynthesis, chlorophyll content, and cell numbers in unialgal cultures of Nitzschia sigma Grun. and Thalassiosira fluviatilis Hustedt isolated from a salt marsh habitat. Results with lower atrazine concentrations indicated an ability to maintain chlorophyll production and cell division with reduced photosynthesis. The effects of a 10?5 M concentration of atrazine in unialgal cultures were also evident in microecosystems and in the field at the same concentration, although atrazine effects were less severe in the field than in microecosystems or cultures. Cell number and productivity of the diatoms from microecosystems not treated with atrazine agreed well with field data and previously published data. Diatom species diversity was not affected by 10?5 M atrazine in microecosystems or in the field but the number of Cymatosira belgica Grun. was increased. Diatom assemblages in atrazine-treated vs non-treated microecosystems were very similar (SIMI>0.838). Results were less conclusive in the field but the trend was toward a lower level of similarity. Based on the least effect level of atrazine to diatoms, the maximum safe level for atrazine in the salt marsh is 10 ppb.  相似文献   

12.
In order to better understand the spatiotemporal variations and interrelationships of greenhouse gases (GHG), monthly surface fluxes and profile concentrations of GHG (CO2, N2O and CH4) in karst areas in the Guizhou Province, southwest China, were measured from June 2006 to May 2007. GHG fluxes showed high variability, with a range of 460.9?C1,281.2?mg?m?2?h?1 for CO2, ?25.4 to 81.5???g?m?2?h?1 for N2O and ?28.7 to ?274.9???g?m?2?h?1 for CH4, but no obvious seasonal change trends of the fluxes existed. Profile concentrations of CO2, N2O and CH4 varied between 0.5 and 31.5?mL?L?1, 0.273 and 0.734, and 0.1 and 3.5???L?L?1, respectively. In general, concentrations of CO2 and N2O increased with depth, while CH4 had an inverse trend. However, in October, November and January, the reversal of depth patterns of GHG concentrations took place below 15?cm, close to the soil?Crock interface. The spatiotemporal distribution of CO2 in soil profile was significantly positively correlated with that of N2O (p?<?0.05?C0.01) and negatively correlated with that of CH4 (p?<?0.01). The correlation analysis showed that soil temperature and moisture may be responsible for GHG dynamics in the soils, rather than the exchange of GHG between land and atmosphere.  相似文献   

13.
Preliminary measurements were carried out of the solubility of the O2-buffering assemblage bismuth + bismite (Bi2O3) in aqueous liquid–vapor and vapor-only systems at temperatures of 220, 250 and 300 °C. All experiments were carried out in Ti reaction vessels and were designed such that the Bi solids were contained in a silica tube that prevented contact with liquid water at any time during the experiment. Two blank (no Bi solids present) liquid–vapor experiments at 220 °C yielded Bi concentrations (±1σ) in the condensed liquid of 0.22 ± 0.02 mg/L, whereas the solubility measurements at this temperature yielded an average value of approximately 6 ± 9 mg/L, with replicate experiments ranging from 0.3 to 26 mg/L. Although the 6 mg/L value is associated with a considerable degree of uncertainty, the experiments do indicate transport of Bi through the vapor phase. Measured Bi concentrations in the condensed liquid at 250 °C were in the same range as those at 220 °C, whereas those at 300 °C were significantly lower (i.e., all below the blank value). Vapor-only experiments necessarily contained much smaller initial volumes of water, thereby making the results more susceptible to contamination. Single blank runs at 220 and 300 °C yielded Bi concentrations of 82 and 16 mg/L, respectively. Measured concentrations (±1σ) of Bi in the vapor-only solubility experiments at 220 °C were 235 ± 78 mg/L for an initial water volume of 0.5 mL, and at 300 °C were 56 ± 30 mg/L and 33 ± 21 for initial water volumes of 1 and 2 mL, respectively, suggesting strong preferential partitioning of Bi into the vapor. The results indicate a negative dependence of Bi solubility on temperature, but are inconclusive with respect to the dependence of Bi solubility on water density or fugacity.  相似文献   

14.
《Applied Geochemistry》2006,21(2):289-304
Mineral springs from Daylesford, Australia discharge at ambient temperatures, have high CO2 contents, and effervesce naturally. Mineral waters have high HCO3 and Na concentrations (up to 4110 and 750 mg/L, respectively) and CO2 concentrations of 620–2520 mg/L. Calcium and Mg concentrations are 61–250 and 44–215 mg/L, respectively, and Si, Sr, Ba, and Li are the most abundant minor and trace elements. The high PCO2 of these waters promotes mineral dissolution, while maintaining low pH values, and geochemical modelling indicates that the CO2-rich mineral water must have interacted with both sediments and basalts. Amorphous silica concentrations and silica geothermometry indicate that these waters are unlikely to have been heated above ambient temperatures and therefore reflect shallow circulation on the order of several hundreds of metres. Variations in minor and trace element composition from closely adjacent spring discharges indicate that groundwater flows within relatively isolated fracture networks. The chemical consistency of individual spring discharges over at least 20 a indicates that flow within these fracture networks has remained isolated over long periods. The mineral water resource is at risk from mixing with potentially contaminated surface water and shallow groundwater in the discharge areas. Increased δ2H values and Cl concentrations, and lower Na concentrations indicate those springs that are most at risk from surface contamination and overpumping. Elevated NO3 concentrations in a few springs indicate that these springs have already been contaminated during discharge.  相似文献   

15.
离子色谱法同时测定铀矿浸出液中的阳离子   总被引：1，自引：0，他引：1  
对铬铁矿中亚铁的测定方法进行了探讨。首先对已有方法进行了验证和筛选,然后对Li2SO4助熔剂的助溶作用及其反应机理进行了研究,从而推荐了H2SO4-H3PO4-V2O5-V(Ⅳ)-Li2SO4和H2SO4-H3PO4-Ce(SO4)2-Li2SO4两种改进型的溶剂体系用于铬铁矿试样中亚铁的测定,所得结果具有良好的重现性。  相似文献   

16.
Atrazine (2-chloro-4-ethylamino-6-isopropylamine-s-triazine) concentrations of 1,000 ppm either killed or eliminated the escape response (considered to be analogous to death) ofUca pugnax in laboratory experiments in August 1977. Adverse effects were observed at concentrations as low as 100 ppm and the severity was dependent on size and sex of the crab. However, in subsequent experiments, each with a new group of crabs, the effects of atrazine became smaller and smaller until a November experiment when no deleterious effects were observed even when exposed to 1,000 ppm. Experiments in August, 1978 confirmed the data obtained 1 year earlier. Ecological and physiological considerations of this seasonal variation in response are discussed. Crabs fed for 20 days with detritus wetted with 10?4 M atrazine were not adversely affected. Crabs exposed to a single application of 0, 100, 1,000, and 10,000 ppm atrazine in the field and in microecosystems were adversely affected only by the 10,000-ppm rate. Toxicity of atrazine to the larval stage of the crab was not investigated.  相似文献   

17.
《Applied Geochemistry》2004,19(6):937-946
Analysis of stable isotopes and major ions in groundwater and surface waters in Belize, Central America was carried out to identify processes that may affect drinking water quality. Belize has a subtropical rainforest/savannah climate with a varied landscape composed predominantly of carbonate rocks and clastic sediments. Stable oxygen (δ18O) and hydrogen (δD) isotope ratios for surface and groundwater have a similar range and show high d-excess (10–40.8‰). The high d-excess in water samples suggest secondary continental vapor flux mixing with incoming vapor from the Caribbean Sea. Model calculations indicate that moisture derived from continental evaporation contributes 13% to overhead vapor load. In surface and groundwater, concentrations of dissolved inorganic carbon (DIC) ranged from 5.4 to 112.9 mg C/l and δ13CDIC ranged from −7.4 to −17.4‰. SO42, Ca2+ and Mg2+ in the water samples ranged from 2–163, 2–6593 and 2–90 mg/l, respectively. The DIC and δ13CDIC indicate both open and closed system carbonate evolution. Combined δ13CDIC and Ca2+, Mg2+, and SO42− suggest additional groundwater evolution by gypsum dissolution and calcite precipitation. The high SO42−content of some water samples indicates regional geologic control on water quality. Similarity in the range of δ18O, δD and δ13CDIC for surface waters and groundwater used for drinking water supply is probably due to high hydraulic conductivities of the karstic aquifers. The results of this study indicate rapid recharge of groundwater aquifers, groundwater influence on surface water chemistry and the potential of surface water to impact groundwater quality and vise versa.  相似文献   

18.
Four distinct components of natural remanent magnetization were isolated from a single site in welded tuffs in the Upper Cretaceous Kisin Group of the Sikhote Alin mountain range, Russia. In order to contribute toward a basis for an interpretation of multicomponent magnetization, rock magnetic experiments were performed on the welded tuffs. All four magnetization components essentially reside in magnetite. The lowest-temperature component up to 300 °C (component A: D=349.3°, I=60.9°, α95=7.3°, N=7) is a present day viscous magnetization. The third-removed component (component C: D=41.4°, I=51.8°, α95=3.5°, N=8), isolated over the temperature range of 450–560 °C, is a primary remanence. The second- and fourth-demagnetized components (component B: D=174.7°, I=−53.1°, α95=21.2°, N=3 and component D: D=188.1°, I=−64.5°, α95=4.0°, N=8, respectively) are secondary magnetizations related to a thermal event in Sikhote Alin between 66 and 51 Ma. Components B and D were acquired through different remagnetization processes. Component B is ascribed to a thermoviscous remanent magnetization carried by single-domain magnetite, and component D is a chemical remanent magnetization.  相似文献   

19.
杨胜科  崔文夏  赵钺  陈静  刘凯  李斌 《岩矿测试》2012,31(4):677-681
在碱性条件下过硫酸钠能氧化腐植酸发生化学发光反应。本研究以过硫酸钠-腐植酸化学发光体系为基础,建立了腐植酸的过硫酸钠氧化-流动注射化学发光测定方法,同时对测定方法的负高压及增益、泵速、过硫酸钠浓度、氢氧化钠浓度等影响因素进行了优化实验。方法的线性范围为0.1～500 mg/L(相关系数为0.9985),检出限为0.076 mg/L,对浓度为0.5 mg/L的腐植酸进行11次平行测定,相对标准偏差(RSD)为3.47%。利用该方法对5种不同地区地下水中的腐植酸进行测定,样品的加标回收率在98.33%～107.50%之间。该方法无需分离,简单易行,对实际样品测定结果满意。  相似文献   

20.
Concentrations and isotopic compositions were determined for H2, N2 and C extracted by stepwise pyrolysis from powdered meteorites, from residues of meteorites partially dissolved with aqueous HF, and from residues of meteorites reacted with HF-HCl solutions. The meteorites treated were the carbonaceous chondrites, Orgueil, Murray, Murchison, Renazzo and Cold Bokkeveld. Data determined for whole rock samples are in approximate agreement with previously published data. Acidification of the meteorites removed the inorganic sources of H2, so that H2 in the HF-HCl acid residues came primarily from insoluble organic matter, which makes up 70–80% fraction of the total carbon in carbonaceous meteorites. The δD in the organic matter differs markedly from previously determined values in organic matter in meteorites. The δD values of organic matter from acid residues of C1 and C2 carbonaceous chondrites range from +650 to + 1150%. The acid residues of the Renazzo meteorite, whose total H2 has a δD of +930‰, gave a δD value of +2500‰. Oxidation of the HF-HCl residue with H2O2 solution removes the high δD and the low δ15N components. The δ13C values range between ?10 and ?21 and δ15N values range between +40 and ?11. The δ15N of Renazzo is unusual; its values range between +150 and ?190.There is good correlation between δD and the concentration of H2 in the acid residues, but no correlation exists between δD, δ13C and δ15N in them. A simple model is proposed to explain the high δD values, and the relationships between δD values and the concentration of H2. This model depends on the irradiation of gaseous molecules facilitating reaction between ionic molecules, and indicates that an increase in the rate of polymerization and accumulation of organic matter on grains would produce an increase in the deuterium concentration in organic matter.  相似文献   

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