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1.
土壤氧气可获得性对双季稻田温室气体排放通量的影响 总被引:5,自引:0,他引:5
为探讨土壤氧气可获得性(SOA)对双季稻田温室气体排放的影响,利用静态箱气相色谱法对多种管理措施影响下稻田温室气体排放通量和土壤氧化还原电位(Eh)、pH值及田间淹水深度(H)等3种SOA因子进行了观测。结果表明,甲烷(CH4)排放最集中的Eh值、pH值和H范围分别为-100-0mV、5 < pH < 6和1-5cm,3个范围内分别观测到48.8%、61.1%和77.0%的CH4排放,其中H对CH4排放影响最明显,单独由其就可解释37.8%的CH4排放通量(P < 0.0001)。对于氧化亚氮(N2O),观测到较多的负通量,其纯排放最密集的3种SOA因子的范围分别是:0-100mV、5 < pH < 6和1-5cm,而200-300mV是其排放的临界Eh范围,高于此范围N2O排放极少。厌氧的反硝化过程是双季稻田N2O产生的主导过程。可为水稻田温室气体排放机理研究提供基础数据。 相似文献
2.
Wolfgang Heinen Anne Marie Lauwers 《Origins of life and evolution of the biosphere》1996,26(2):131-150
The reaction of iron sulfide (FeS) with H2S in water, in presence of CO2 under anaerobic conditions was found to yield H2 and a variety of organic sulfur compounds, mainly thiols and small amounts of CS2 and dimethyldisulfide. The same compounds were produced when H2S was replaced by HCl, in the H2S-generating system FeS/HCl/CO2. The identification of the products was confirmed by GC-MS analyses and the incorporation of H2 in the organic sulfur compounds was demonstrated by experiments in which all hydrogen compounds were replaced by deuterium compounds. Generation of H2 and the synthesis of thiols were both dependent upon the relative abundance of FeS and HCl or H2S, i.e. the FeS/HCl- or FeS/H2S-proportions. Whether thiols or CS2 were formed as the main products depended also on the FeS/HCl-ratio: All conditions which create a H2 deficiency were found to initiate a proportional increase in the amount of CS2. The quantities of H2 and thiols generated depended on temperature: the production of H2 was significantly accelerated from 50°C onward and thiol synthesis above 75°C. The yield of thiols increased with the amount of FeS and HCl (H2S), given a certain FeS/HCl-ratio and a surplus of CO2. A deficiency of CO2 results in lower thiol systhesis. The end product, pyrite (FeS2), was found to appear as a silvery granular layer floating on the aqueous surface. The identity of the thiols was confirmed by mass spectrometry, and the reduction of CO2 demonstrated by the determination of deuterium incorporation with DCl and D2O. The described reactions can principally proceed under the conditions comparable to those obtaining around submarine hydrothermal vents, or the global situation about 4 billion years ago, before the dawn of life, and could replace the need for a reducing atmosphere on the primitive earth. 相似文献
3.
Measurement of bacterial sulfate reduction in sediments: Evaluation of a single-step chromium reduction method 总被引:31,自引:8,他引:23
A procedure which includes the Total Reduced Inorganic Sulfur (TRIS) in a single distillation step is described for the radiotracer measurement of sulfate reduction in sediments. The TRIS includes both Acid Volatile Sulfide (AVS: H2S + FeS) and the remaining Chromium Reducible Sulfur (CRS: S0, FeS2). The single-step distillation was simpler and faster than the consecutive distillations of AVS and CRS. It also resulted in higher (4–50%) sulfate reduction rates than those obtained from the sum of35S in AVS and CRS. The difference was largest when the sediment had been dried after AVS but before CRS distillation. Relative to the35S-AVS distillation alone, the35S-TRIS single-step distallation yielded 8–87% higher reduction rates. The separation and recovery of FeS, S0 and FeS2 was studied under three distillation conditions: 1) cold acid, 2) cold acid with Cr2+, and 3) hot acid with Cr2+. The FeS was recovered by cold acid alone while pyrite was recovered by cold acid with Cr2+. A smaller S0 fraction, presumably of the finer crystal sizes, was recovered also in the cold acid with Cr2+ while most of the S0 required hot acid with Cr2+ for reduction to H2S. 相似文献
4.
Sulphate-reducing bacteria isolated from submerged soil samples of paddy fields effectively precipitated copper from aqueous solution with maximum effect (75%) at 25 ppm Cu2+. As the copper concentration was increased to 100 ppm, precipitation efficiency decreased significantly. The use of bacteria to precipitate heavy metal ions from aqueous effluents is discussed. 相似文献
5.
K. A. Ayotade 《Plant and Soil》1977,46(2):381-389
Summary The sulphide-ion electrode was used to study the kinetics and reactions of free hydrogen sulphide in solution of flooded rice
soils. The observed sulphide potential obeyed the Nernst equation over a range of sulphide-ion concentration from 10-1 to 10-19
M.
Peak H2S concentrations were lowest in neutral soils high in iron and manganese; moderately high in soils low in iron or high in
organic matter; and highest in acid sulphate soil low in iron. Harmful concentrations of H2S may be present in acid sulphate and acid soils low in iron during the first few weeks after flooding. The concentrations
in acid sulphate soils can be drastically lowered by liming.
There was thermodynamic evidence for the presence of FeS and ZnS in the solutions of most soils. 相似文献
6.
The isotope exchange between35S-labeled sulfur compounds of sulfate (SO4
2–), elemental sulfur (S0), polysulfide (Sn
2–), hydrogen sulfide (HS–: H2S + HS– + S2–), iron sulfide (FeS), and pyrite (FeS2) was studied at pH 7.6 and 20 °C in anoxic, sterile seawater. Isotope exchange was observed between S0, S2
2– HS–, and FeS, but not between35S labeled SO4
2– or FeS2 and the other sulfur compounds. Polysulfide mediated the isotope exchange between S0 and bisulfide (HS–). The isotope exchange between S0 and Sn
2–) reached 50% of equilibrium within < 2 min while exchange between S2
2– and HS– approached equilibrium within 0.5-1 h. In all the experiments HS–, revealed a fraction exchange from 0.79 to 1.00. Isotope exchange between S2– and FeS took place only via S2
2– and/or HS–. The isotope exchange between iron sulfide and the other sulfur compounds was not complete within 24 h as shown by a fraction exchange of 0.07–0.83. This lack of equilibrium (fraction exchange < 1) was due to the isotope exchange between dissolved compounds and surfaces of sulfur particles. The isotopic exchange reactions limit the usefulness of radiotracers in process studies of the inorganic sulfur species. Exchange reactions will also affect the stable isotope distribution among the sulfur species. The kinetics of the isotopic exchange reactions, however, depend on both pH and temperature. 相似文献
7.
A popular sequential extraction procedure (Tessier et al. 1979) designed t o extract metals partitioned in various sediment
phases, was evaluated for its selectivity. Amorphous FeOOH, FeS, and FeS2 were added separately to natural lake sediments and sequentially extracted. The selectivity of the sequential procedure for
the added solid phases was evaluated by determining the difference in the mass of Fe extracted from treated and control sediments.
In the experiments where sulfide minerals were added, total S was measured in the residual solids in order to confirm selectivity
of the method. Concentrations of total carbon remaining in the solid phase after each extraction step were also measured to
determine the selectivity of the sequential procedure for carbon.
The procedure was moderately selective for Fe added as FeOOH; a mean of 77 ± 12% (p < 0.05) of the Fe added was extracted in the step designed to reduce Fe-Mn oxyhydroxides. In experiments where FeS was added,
a mean of 69 ± 11% (p < 0.05) of the Fe added as FeS was extracted in the fraction designed to oxidize sulfides and organic matter. Approximately
25% of the Fe added as FeS may have been extracted prematurely. Although less precise, total S analyses confirmed that much
of the FeS was extracted in the oxidation step, yielding 104 ± 87% (p < 0.05) of the S added as FeS. The procedure was highly selective for FeS2; 92 ± 14% (p < 0.05) of the Fe added as pyrite was extracted in the sulfide extraction step. Extraction of 80 ± 54% (p < 0.05) of S added as pyrite confirmed that FeS2 were selectively extracted in the sulfide extraction step. Carbon in the sediments was also selectively extracted in the
oxidation step (77 ± 2.4% of total C; p < 0.05). The applications and limitations of sequential extraction procedures as limnological research tools are discussed
in light of our results.
Request for offprints 相似文献
8.
pH值和Fe、Cd处理对水稻根际及根表Fe、Cd吸附行为的影响 总被引:2,自引:0,他引:2
通过营养液-蛭石联合培养试验,设置系列pH值(4.5—7.5)和Fe、Cd处理,研究不同pH值及Fe、Cd浓度对水稻和蛭石表面Fe、Cd吸附的影响。结果表明,不同pH值处理下的根际氧化还原电位和酸度不同,0.9 mg/L Cd处理下的根际氧化势低于0.5 mg/L Cd,50 mg/L Fe处理下的根际酸度高于30 mg/L Fe处理。根表吸附Fe、Cd组分和数量都受根际Eh、pH值制约,根表Fe、Cd吸附量在处理pH值6.0时最低,并分别在处理pH值7.5和处理pH值4.5达到最高。但根系表面对Fe、Cd的吸附机制与蛭石表面不同,蛭石吸附Fe主要为晶态Fe,占到总沉积Fe的73%—87%;水稻根表沉积Fe以非晶态Fe为主,占总沉积Fe的91%—95%;与处理pH值和根际Eh间有显著的相关性(蛭石晶态Fe:ppH=0.011、pEh=0.042;水稻根表非晶态Fe:ppH=0.050、pEh=0.004)。蛭石表面交换态Fe及交换态Cd与处理pH值和Eh间存在显著的相关性(pH值:pFe<0.001、pCd=0.009;Eh:pFe=0.016、pCd=0.002),而根表交换态Fe及交换态Cd仅与处理pH值间有显著的相关性(pFe=0.007,pCd=0.048)。不同Fe、Cd浓度处理对根际Eh、pH值的升降和根表Fe、Cd吸附均有影响。与对照相比,增Cd处理可以降低根际Eh和升高pH值,减少溶液Cd浓度并增加根表Cd吸附量;增Fe处理则可以升高根际Eh和降低pH值,增加溶液Fe、Cd浓度并减少根表Fe、Cd吸附量。这是水稻应对Fe、Cd浓度胁迫的生理反应之一。 相似文献
9.
采用静态箱-气相色谱法观测冬季水分管理和水稻覆膜栽培对川中丘陵地区冬水田全年的CH_4排放通量。试验设置持续淹水(CF)、冬季直接落干+稻季淹水(TF)与冬季覆膜落干+稻季覆膜(PM)3个处理。结果表明,冬季休闲期,CF、TF和PM处理CH_4排放分别为16.1、1.4 g/m~2和2.7 g/m~2;水稻生长期,CF、TF和PM处理CH_4排放分别为57.7、27.7 g/m~2和13.5 g/m~2。相较于CF处理,TF与PM处理分别减少其全年CH_4排放60.6%和78.0%。TF与PM处理水稻生长期CH_4排放峰值分别较CF处理低33.0%和56.1%。休闲期,TF、PM处理厢面与厢沟区域CH_4排放与土壤温度显著正相关(P0.05),与土壤氧化还原电位(土壤Eh)显著负相关(P0.05),而CF处理CH_4排放仅与土壤温度显著正相关(P0.05)。水稻生长期,CF处理CH_4排放与土壤温度显著正相关(P0.05),与土壤Eh显著负相关(P0.05),TF处理CH_4排放仅与土壤Eh显著负相关(P0.05),PM处理厢沟CH_4排放与土壤Eh显著正相关(P0.05)。各处理水稻生长期土壤可溶性有机碳含量(DOC)与微生物生物量碳含量(MBC)显著高于休闲期(P0.05)。研究结果为进一步研究冬水田全年CH_4排放规律及寻求有效的减排措施提供数据支撑和科学依据。 相似文献
10.
Baoping Xin Di Zhang Xian Zhang Yunting Xia Feng Wu Shi Chen Li Li 《Bioresource technology》2009,100(24):6163-6169
The bioleaching mechanism of Co and Li from spent lithium-ion batteries by mixed culture of sulfur-oxidizing and iron-oxidizing bacteria was investigated. It was found that the highest release of Li occurred at the lowest pH of 1.54 with elemental sulfur as an energy source, the lowest occurred at the highest pH of 1.69 with FeS2. In contrast, the highest release of Co occurred at higher pH and varied ORP with S + FeS2, the lowest occurred at almost unchanged ORP with S. It is suggested that acid dissolution is the main mechanism for Li bioleaching independent of energy matters types, however, apart from acid dissolution, Fe2+ catalyzed reduction takes part in the bioleaching process as well. Co2+ was released by acid dissolution after insoluble Co3+ was reduced into soluble Co2+ by Fe2+ in both FeS2 and FeS2 + S systems. The proposed bioleaching mechanism mentioned above was confirmed by the further results obtained from the experiments of bioprocess-stimulated chemical leaching and from the changes in structure and component of bioleaching residues characterized by XPS, SEM and EDX. 相似文献
11.
《Animal : an international journal of animal bioscience》2014,8(6):931-937
This in vitro study aimed at understanding how abiotic, that is chemical and electrochemical potentials, and biotic factors combine to impact the outputs of rumen volatile fatty acid (VFA). Using a 48-run design optimized by means of an exchange algorithm, the curvilinear effects of pH, Eh and partial pressure of dihydrogen (H2) on fermentation yields were investigated in 6-h batch cultures of mixed rumen microbes, fed on glucose so as to bypass the enzymatic hydrolysis and conversion steps preceding the glycolytic pathway. The role played by rumen microbiota in the expression of these effects was explored by testing three inocula grown on feeds supplying a microflora adapted to fibre, slowly degradable or readily degradable starch as the dominant dietary polysaccharide. Data were fitted to 2nd-order polynomial models. In fibre-adapted cultures, the yields of major VFA were mainly influenced by pH and H2 partial pressure, in opposite ways. In wheat grain-adapted cultures, the VFA yields underwent the opposite influences of pH, in a curvilinear way for propionate, and Eh since acetate production yield was not significantly modified by any factor. In maize grain-adapted cultures, acetate production yield was not modified by any factor but H2 in a quadratic way when the production yields of higher VFA underwent opposite influences of pH and Eh. In conclusion, the effects of environmental factors were dependent on the nature of the inoculum, a major source of variation, and more particularly on its adaptation to high- or low-fibre diets. These effects were loosely interrelated, the pH being the most active factor before the Eh and H2 partial pressure. 相似文献
12.
Ulderico Ulissi Seitaro Ito Seyed Milad Hosseini Alberto Varzi Yuichi Aihara Stefano Passerini 《Liver Transplantation》2018,8(26)
As the theoretical limit of intercalation material‐based lithium‐ion batteries is approached, alternative chemistries based on conversion reactions are presently considered. The conversion of sulfur is particularly appealing as it is associated with a theoretical gravimetric energy density up to 2510 Wh kg?1. In this paper, three different carbon‐iron disulfide‐sulfur (C‐FeS2‐S) composites are proposed as alternative positive electrode materials for all‐solid‐state lithium‐sulfur batteries. These are synthesized through a facile, low‐cost, single‐step ball‐milling procedure. It is found that the crystalline structure (evaluated by X‐ray diffraction) and the morphology of the composites (evaluated by scanning electron microscopy) are greatly influenced by the FeS2:S ratio. Li/LiI‐Li3PS4/C‐FeS2‐S solid‐state cells are tested under galvanostatic conditions, while differential capacity plots are used to discuss the peculiar electrochemical features of these novel materials. These cells deliver capacities as high as 1200 mAh g(FeS2+S)?1 at the intermediate loading of 1 mg cm?2 (1.2 mAh cm?2), and up to 3.55 mAh cm?2 for active material loadings as high as 5 mg cm?2 at 20 °C. Such an excellent performance, rarely reported for (sulfur/metal sulfide)‐based, all solid‐state cells, makes these composites highly promising for real application where high positive electrode loadings are required. 相似文献
13.
The neutralization of acidic coal mine lakes by additions of natural organic matter: a mesocosm test
Cylindrical polyethylene enclosures 3 m in length and 1 m in diameter reaching from the surface to the bottom were constructed in an acid (pH=3.1) lake on a coal surface mine in southern Illinois. Wheat straw was added to the enclosures to test the effects of dissimilatory sulfate reduction on water chemistry. Added straw increased sulfide concentrations, raised pH to 6.5, reduced O2 and increased acid neutralizing capacity of the enclosed water columns when compared with a control enclosure and with the open lake. Generation of acid neutralizing capacity exceeded the standing stock of sulfide indicating that sulfide was removed either by precipitation of FeS or outgassing of H2S. The pH and acid neutralizing capacity within the enclosures eventually returned to the level of the surrounding lake because of water exchange around the enclosure walls. Our results show that additions of organic matter to acid surface mine lakes result in the generation of acid neutralizing capacity. 相似文献
14.
Bodvin Torjan Indergaard Mentz Norgaard Erik Jensen Arne Skaar Arne 《Hydrobiologia》1996,335(1):83-86
A method has been developed for the determination of H2S and FeS in sediments. FeS is converted into H2S which is flushed from the samples directly into an excess of chlorine bleach, NaC1O or KClO with some Zn2+ added. Either the excess can be titrated back potentiometrically with As2O3, or the sulphate formed can be measured colorimetrically. The precision is primarily controlled by the homogeneity of the
sediment suspensions and can be better than 99%. 相似文献
15.
In-situ partial pressures of hydrogen in anoxic profundal lake sediments reached values of up to 5 Pa which were more than 5 orders of magnitude lower than the partial pressures of methane. Analysis of gas bubbles collected from anoxic submerged paddy soil showed H2 partial pressures in the range of 1.8 ± 1.3 Pa being ca. 4 orders of magnitude lower than the CH4 partial pressures. H2 emission rates, on the other hand, were less than 3 orders of magnitude lower than the CH4 emission rates indicating that H2 and CH4 were oxidized to a different extent in the rhizosphere of the soil before they reached the atmosphere, or that H2 was produced by the plants. More than 70% of the emitted H2 reached the atmosphere via plant-mediated flux. The rest was emitted via ebullition from the anoxic soil and, in addition, was produced in the paddy water. A significant amount of H2 was indeed found to be produced in the water under conditions where thallic algae and submerged parts of the rice plants produced oxygen by photosynthesis. Very little H2 was emitted via molecular diffusion through the paddy water; in addition, this amount was less than expected from the degree of supersaturation and the diffusional emission rate of CH4 indicating a relatively high rate of H2 consumption in the surface film of the paddy water. The total H2 source strength of rice paddies and other freshwater environments was estimated to be less than 1 Tg yr-1, being negligible in the atmospheric budget of H2. 相似文献
16.
Nanosilver (10−9 m) refers to particles comprising 20–15,000 silver atoms, exhibiting high stability and specific surface area. At present, nanosilver has been used in agricultural cultivation and production. This study examined the effects of nanosilver on growth and development of rice root systems. Study results showed that fresh weight of rice belowground organs and root length both increased significantly by 5% and 25%, respectively, after rice radicles were treated with 2 ppm of nanosilver for three days. However, the H2O2 level reached its peak at 2 days from treatment, but the activities of the antioxidant enzymes CAT, APX, and GR were inhibited by 2 ppm of nanosilver treatment. The results showed that nanosilver treatment inhibited the antioxidant enzyme activity of rice roots. The treatment of rice radicles with 5 μM H2O2 promoted root development and the same was observed when nanosilver was used for treatment. Moreover, ascorbic acid (AsA) is a H2O2 scavenger and therefore rice root development was inhibited when AsA was added to rice radicles together with either treatment of nanosilver or H2O2. In summary, nanosilver treatment of rice radicles promoted root growth and development via the regulation of H2O2 and not the O2•− pathway. 相似文献
17.
The effects of CaCO3, Zn sources and levels on the yield of submerged paddy and uptake of Zn, P and N to paddy were studied in green-house at Haryana Agricultural University, Hissar. Powdered CaCO3 was mixed at 0,4 and 8 per cent and Zn was added at 0,5 and 10 ppm through ZnSO4.7H2O, ZnO and Zn EDTA separately. Dry weight at tillering and heading and grain and straw at maturity decreased significantly with 4 and 8 per cent CaCO3 in comparison to the control. Increasing Zn application increased the dry weight and grain yield. Zn EDTA gave highest yield of paddy followed by ZnSO4.7H2O and ZnO.Increasing the application of CaCO3 from 0–8 per cent decreased the concentration and uptake of Zn and increasing Zn application from 0–10 ppm increased concentration and uptake of Zn in paddy at tillering, heading and maturity. Zn EDTA gave the highest concentration and uptake of Zn followed by ZnSO4.7H2O and ZnO. There was interaction between Zn sources and CaCO3.The concentration and uptake of N and P in paddy dry matter at tillering and heading and straw and grain at maturity decreased as compared to control with increasing CaCO3 addition. The concentration and uptake of N increased and that of P decreased in paddy dry matter straw and grain with increasing Zn application. The highest concentration of N was observed with ZnO, followed by ZnSO4.7H2O and Zn EDTA. But highest uptake of N was observed with Zn EDTA followed by ZnSO4.7H2O and ZnO. As regards concentration and uptake of P, it was highest with ZnO followed by ZnSO4.7H2O and Zn EDTA. 相似文献
18.
Mahendra Singh 《Plant and Soil》1981,62(2):305-308
Summary The effects of Zn, P, N and CaCO3 on tryptophan concentration in rice grain were studied in greenhouse at Haryana Agricultural University. Zinc application
upto 20 ppm increased tryptophan concentration in rice grain. Zn-EDTA gave highest increase followed by ZnSO4 and then ZnO. Liming at the rate of 4 and 8 per cent decreased tryptophan concentration significantly. Phosphorus application
upto 100 ppm also decreased tryptophan significantly but Zn in combination with P increased tryptophan and overcame negative
effect of P. Nitrogen application upto 120 ppm increased tryptophan concentration. There was positive interaction between
Zn and N. Ammonium sulphate gave highest tryptophan followed by ammonium nitrate and then urea.
The tryptophan concentration ranged between 766 ppm and 2011 ppm in paddy grain. The lowest tryptophan concentration was in
the plants treated with 8 per cent lime in absence of added Zn and highest with 10 ppm Zn through Zn-EDTA.
Department of Soils. 相似文献
19.
Isolation of Key Methanogens for Global Methane Emission from Rice Paddy Fields: a Novel Isolate Affiliated with the Clone Cluster Rice Cluster I 总被引:2,自引:0,他引:2
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Sanae Sakai Hiroyuki Imachi Yuji Sekiguchi Akiyoshi Ohashi Hideki Harada Yoichi Kamagata 《Applied microbiology》2007,73(13):4326-4331
Despite the fact that rice paddy fields (RPFs) are contributing 10 to 25% of global methane emissions, the organisms responsible for methane production in RPFs have remained uncultivated and thus uncharacterized. Here we report the isolation of a methanogen (strain SANAE) belonging to an abundant and ubiquitous group of methanogens called rice cluster I (RC-I) previously identified as an ecologically important microbial component via culture-independent analyses. To enrich the RC-I methanogens from rice paddy samples, we attempted to mimic the in situ conditions of RC-I on the basis of the idea that methanogens in such ecosystems should thrive by receiving low concentrations of substrate (H2) continuously provided by heterotrophic H2-producing bacteria. For this purpose, we developed a coculture method using an indirect substrate (propionate) in defined medium and a propionate-oxidizing, H2-producing syntroph, Syntrophobacter fumaroxidans, as the H2 supplier. By doing so, we significantly enriched the RC-I methanogens and eventually obtained a methanogen within the RC-I group in pure culture. This is the first report on the isolation of a methanogen within RC-I. 相似文献
20.
In this paper, the biological removal of H2S from air had been investigated using a self-made biofilter with efficient bioceramics and a polyhedral hollow ball. The biological removal efficiency of H2S had been analyzed at different experimental conditions, such as inlet H2S concentration, residence time, initial pH value, and reaction temperature etc. The results showed that the initial pH value had a slight effect on H2S removal efficiency from pH 3 to 9. The optimal initial pH value was 5.5, while the H2S removal efficiency was 100%. The H2S removal efficiency increased with increases in the nutrient solution spraying rate. The appropriate temperature was 25°C in the temperature range from 15 to 30°C. The H2S removal efficiency dropped with the increase of air input and inlet H2S concentration. After being isolated and screened, six strains of heterotrophic sulfide oxidizing bacteria and one strain autotrophic sulfide oxidizing bacteria were determined to be involved in the removal of H2S within the biofilter. The reaction kinetics of H2S was in accordance with first order reaction kinetics. 相似文献