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1.
Nitrogen dioxide gas was rapidly absorbed by soil. After a 15 min incubation at 25°C, soil at a moisture content of 16% absorbed 99% of the NO2 introduced into the gas-phase volume of a closed system. The presence of microorganisms hatl no influence on the rate of absorption of the gas by soil. The absorption of NO2 by sandy clay loam soil was not an oxygen- or temperature-dependent process nor did it depend upon the moisture content of the soil. These physical factors acquired significance only in determining the initial rate of absorption of the gas and the rate at which NO2 diffused through the soil. Exposure of soil to NO2 resulted in substantial increases in the levels of NO inf2 sup? N in the soil. Chemical oxidation of the NO inf2 sup? N resulted in an increase in NO inf3 sup? N levels. During a 14-day incubation, NO inf2 sup? N concentrations in sterile soil exposed to an atmosphere containing 100 μg ml?1 of NO2 decreased from 190 μg g?1 of soil to 105 μg g?1 with an accompanying increase in NO inf3 sup? N from 2 μg g? 1 to 63 μg g?1 of soil. Nitrogen dioxide severely inhibited the growth of both aerobic and anaerobic asymbiotic N2-fixing bacteria in soil. After a 48 h incubation at 25°C, soil aggregates exposed to an atmosphere containing 100 μg ml?1 of NO2 contained 88% and 98% fewer aerobic and anaerobic N2-fixing bacteria, respectively. C2H2-reduction measurements showed that nitrogenase synthesis and activity in artificial soil aggregates amended with 2% glucose were inhibited by 20% and 48%, respectively, when exposed to atmospheric concentrations of 35 and 3.5 μg ml?1 of NO2, respectively.  相似文献   

2.
This paper describes the use of dry free hanging filters, as passive samplers to determine ozone in the ambient air. The filters, with a diameter of 25?mm, were impregnated with 5,5??-disodium indigo disulphonate (IDS), a reagent for ozone. From the amount of reacted indigo compound, found on the filter, and the ozone concentration in the ambient air, a pseudo rate constant k 1, of the reaction between ozone (O3) and IDS on the filter, is calculated. The range of measurement is between 9 and 205???g/m3 ambient ozone. The dry filter method is specific for ozone, while the Dutch standard method NEN2789, based on an aqueous solution of IDS, has to be corrected for the presence of NO x . From wind tunnel and field experiments, k 1 proved to vary between 0.7 and 1.5?×?10?6?m3?s?1 (??g O3)?1 at wind velocities between 1 and 3?m/s and at an exposure time of 60?min. Within these conditions, ozone concentrations have been determined with free hanging filters in four busy streets in Yogyakarta, Indonesia and at two background sites using an average value of k 1 of 1.2?×?10?6. Subsequently, the traffic NO emission was estimated from the difference of the O3 concentrations at both sides of a road. For an arbitrary situation, an NO emission of 255???g/s per metre road length was calculated. The filter method is inexpensive and practical, needs no electricity, is easily assembled and can be used to perform measurements in remote areas. It is shown here that this simple measurement technique may support air quality studies, e.g., in developing countries.  相似文献   

3.
Land development has caused runoff of red soil into the ocean on the north side of Okinawa Island, Japan. In an attempt to clarify the impacts of this “red soil pollution” on the oxidizing power of seawater, we studied the formation of hydroxyl radical (?OH), the most potent oxidant in the environment, in red soil-polluted waters using a 313-nm monochromatic light. ?OH was photochemically formed in the red soil-polluted water samples, and the formation rates of ?OH decreased as salinity increased, i.e., as red soil-polluted river water gets mixed with seawater. The photo-formation rates of ?OH showed good correlations with dissolved Fe concentrations (R 2?=?0.96) and [NO2 ?]?+?[NO3 ?] concentrations (R 2?=?0.87), while a negative and weak correlation was found with dissolved organic carbon concentrations (R?=??0.78). Theoretical calculation showed that direct photolysis of NO3 ?, Fe(OH)2+, and hydrogen peroxide all together accounted for less than 10% of the observed ?OH formation in the red soil-polluted waters. Comparison between filtered and unfiltered samples showed that red soil particles were not the main sources of ?OH, and the photolysis of NO2 ? could account for at most 78% of the observed ?OH formation rates. We found that the Fenton’s reaction (a reaction between Fe(II) and H2O2) could possibly account for the observed formation of ?OH in the red soil-polluted waters.  相似文献   

4.
Sandy loam soil, with added glucose, was incubated anaerobically under N2 and subjected to repeated 1-h C2H2 reduction assays. In the presence of 1% glucose the addition of 50 μg NH4+ ?N/g or of 20 μg NO?3 N/g (untreated soil contained 1.2 μg NH+4?N and 7.10 μg NO?3-N/g) caused at least some suppression of nitrogenase activity. Activity developed when the KCl-extractable soil inorganic nitrogen concentration dropped below 35 μg/g. In the presence of 0.1 or 0.05% glucose the addition of 5 μg NH+4?N/g caused some suppression of nitrogenase activity. However, activity developed when the soil NH4+-N concentration dropped below about 4 μg/g. With 0.1% glucose and 5 μg added NO?2 N/g, activity did not develop until the soil NO?2 -N concentration dropped to zero. Added NO?3 N was rapidly reduced and denitrified to NO?2- N, N2O-N and NH+4 N and furthermore caused some inhibition of CO2 evolution. The data from NH4?-addition experiments are consistent with a nitrogenase repression/ derepression threshold of 4 and 35μg NH+4-N/g at 0.05 and 1% glucose concentrations, respectively. The data from NO?2- and NO?3-addition experiments suggest a combination of repression and toxicity effects in the presence of added NO?3 N.  相似文献   

5.
Atmospheric gases and particulates were collected using four-stage filter-pack in Chunchon from January through December in 1999. Particulate SO4 2? and NO3 ?, and gaseous HNO3, SO2 and NH3 were analyzed. Annual average concentration of SO4 2?(S), NO3 ?(S), HNO3 (g), SO2(g) and NH3(g) were 5.75µg/m3, 4.98µg/m3, 0.33ppb, 1.52ppb and 7.25ppb, respectively. Annual dry deposition fluxes were estimated using the measured concentration and dry deposition velocity published by other research group. Annual dry deposition of S was 287kg · (km)?2·y?1, which accounted for about 30% of total S deposition. For N deposition, dry deposition is predominant; about 70% of total N deposition was through dry process mostly as forms of NH3 and HNO3.  相似文献   

6.
Nitrogen dioxide (NO2) is one of the major atmospheric pollutants, and the concentration of NO2 is regarded as one of the indicators of air quality. In the past decades, China has experienced rapid economic growth and severe NO2 pollution to match. We evaluate the trends and spatiotemporal patterns of tropospheric NO2 over mainland China from 2005 to 2014 using vertical column density (VCD) datasets retrieved from the Ozone Monitoring Instrument (OMI). Results show that from 2005 to 2014, NO2 pollution regions have enlarged at the national scale, and high NO2 VCDs are mainly concentrated over highly populated regions in eastern China. The year 2011 is the turning point. Tropospheric NO2 VCDs first significantly increase by 0.19?×?1015 molec cm?2?year?1 (R 2?=?0.94, P?=?0.002) from 2005 to 2011, and then decrease by 0.21?×?1015 molec cm?2?year?1 (R 2?=?0.97, P?=?0.016) from 2011 to 2014. Since 2011, tropospheric NO2 VCDs over central-east China decrease remarkably. Tropospheric NO2 VCDs is higher in November (3.630?×?1015 molec/cm2), December (4.758?×?1015 molec/cm2), and January (4.863?×?1015 molec/cm2), while lower in July (1.684?×?1015 molec/cm2), August (1.627?×?1015 molec/cm2), and September (1.703?×?1015 molec/cm2), indicating that winter and spring are the most polluted seasons. Due to the huge gap in population density and industry development between western and eastern China, the spatial pattern of tropospheric NO2 VCDs shows large west-east difference.  相似文献   

7.
Following the Deepwater Horizon explosion and crude oil contamination of a marsh ecosystem in AL in June 2010, hydrocarbon-degrader microbial abundances of aerobic alkane, total hydrocarbon, and polycyclic aromatic hydrocarbon (PAH) degraders were enumerated seasonally. Surface sediment samples were collected in October and December of 2010 and in April and July of 2011 along 40?C70-m transects from the high tide to the intertidal zone including Spartina alterniflora-vegetated marsh, seagrass (Ruppia maritima)-dominated sediments, and nonvegetated sediments. Alkane and total hydrocarbon degraders in the sediment were detected, while PAH degraders were below detection limit at all locations examined during the sampling periods. The highest counts for microbial alkane degraders were observed at the high tide line in April and averaged to 8.65?×?105 of cells/g dry weight (dw) sediment. The abundance of alkane degraders during other months ranged from 9.49?×?103 to 3.87?×?104, while for total hydrocarbon degraders, it ranged between 5.62?×?103 and 1.14?×?105 of cells/g dw sediment. Pore water nutrient concentrations (NH 4 + , NO 3 ? , NO 2 ? , and PO 4 3? ) showed seasonal changes with minimum values observed in December and April and maximum values in October and July. Concentrations of total petroleum hydrocarbons in sediments averaged 100.4?±?52.4 and 141.9?±?57.5?mg/kg in January and July, 2011, respectively. The presence of aerobic microbial communities during all seasons in these nearshore ecosystems suggests that an active and resident microbial community is capable of mineralizing a fraction of petroleum hydrocarbons.  相似文献   

8.
This study evaluated the toxic effects of arsenic (As) on the growth, total antioxidant activity, total content of phenolic compounds, and content of photosynthetic pigments of Azolla filiculoides. The aquatic fern was propagated and exposed to Yoshida nutrient solution contaminated with sodium arsenate (Na2HAsO4??7H2O) at six concentrations (5, 10, 20, 30, 60, and 120???g?As?mL?1), including the control without As contamination. Azolla cultures were kept under environmental chamber conditions?26??C, 12?h photoperiod and 80% HR for 96?h. Increased As concentrations (>30???g?mL?1) significantly diminished growth of A. filiculoides and the total content of chlorophyll and total phenolic compounds, but significantly enhanced of total carotenoid?+?xanthophylls content. The concentrations of 5 and 10???g?As?mL?1 significantly stimulated the growth of A. filiculoides. This aquatic fern tolerates As concentrations lower than 30???g?mL?1, and its maximum As accumulation (28???g?g?1 dry weight) was achieved when exposed to 60???g As mL?1, but showing clear symptoms of As toxicity.  相似文献   

9.
The efficiency of UV- and VUV-based processes (UV, VUV, UV/H2O2, and VUV/H2O2) for removal of sulfamethoxazole (SMX) in Milli-Q water and sewage treatment plant (STP) effluent was investigated at 20??C. The investigated factors included initial pH, variety of inorganic anions (NO 3 ? and HCO 3 ? ), and humic acid (HA). The results showed that the degradation of SMX in Milli-Q water at both two pH (5.5 and 7.0) followed the order of VUV/H2O2 > VUV > UV/H2O2 > UV. All the experimental data well fitted the pseudo-first order kinetic model and the rate constant (k) and half-life time (t 1/2) were determined accordingly. Indirect oxidation of SMX by generated ?OH was the main degradation mechanism in UV/H2O2 and VUV/H2O2, while direct photolysis predominated in UV processes. The quenching tests showed that some other reactive species along with ?OH radicals were responsible to the SMX degradation under VUV process. The addition of 20?mg?L?1 HA significantly inhibited SMX degradation, whereas, the inhibitive effects of NO 3 ? and HCO 3 ? (0.1?mol?L?1) were observed as well in all processes except in UV irradiation for NO 3 ? . The removal rate decreased 1.7?C3.6 times when applying these processes to STP effluent due to the complex constituents, suggesting that from the application point of view the constituents of these complexes in real STP effluent should be considered carefully prior to the use of UV-based processes for SMX degradation.  相似文献   

10.
The present work discusses the startup and operation of different biotrickling filters during the simultaneous removal of NH3, H2S, and ethyl mercaptan (EM) for odor control, focusing on (a) the impact of pH control in the stability of the nitrification processes during reactor startup and (b) the crossed effects among selected pollutants and their by-products. Two biotrickling filters were packed with poplar wood chips (R1 and R2A), while a third reactor was packed with polyurethane foam (R2B). R2A and R2B presented a pH control system, whereas R1 did not. Loads of 2?C10?g N?CNH3 m?3?h?1, 5?C16?g S?CH2S m?3?h?1, and 1?C6?g EM m?3?h?1 were supplied to the bioreactors. The presence of a pH control loop in R2A and R2B proved to be crucial to avoid long startup periods and bioreactors malfunctioning due to biological activity inhibition. In addition, the impact of the presence of different concentrations of a series of N species (NH 4 + , NO 2 ? , and NO 3 ? ) and S species (SO 4 2? and S2?) on the performance of the two biotrickling filters was studied by increasing their load to the reactors. Sulfide oxidation proved to be the most resilient process, since it was not affected in any of the experiments, while nitrification and EM removal were severely affected. In particular, the latter was affected by SO 4 2? and NO 2 ? , while nitrification was significantly affected by NH 4 + . The biotrickling filter packed with polyurethane foam was more sensitive to crossed effects than the biotrickling filter packed with poplar wood chips.  相似文献   

11.
In order to enhance the photocatalytic activity of the TiO2 films, Co surface doped TiO2-SiO2 composite films were synthesized by the improved sol-gel method, in which tetrabutyl titanate (Ti(OC4H9)4) and tetraethyl orthosilicate were chosen as the precursors and cobaltous nitrate hexahydrate (Co(NO3)2·6H2O) was chosen as cobalt source. The field emission scanning electron microscopy and X-ray diffraction results indicated that the films were composed of nanoparticles or aggregates. The photoluminescence results revealed that the recombination rate of the photogenerated electrons and holes was prohibited via SiO2 composite and Co doping in TiO2 film. The Brunauer?CEmmett?CTeller results showed that the surface area of the modified TiO2 was 301.7?m2?g?1, while that of the pure TiO2 was 68.4?m2?g?1. The photocatalytic activities of the films were evaluated by degradation of an organic dye in aqueous solution. With the SiO2 composite and Co doping, the modified TiO2 films with high photocatalytic activity and clearly responsive to the visible light were obtained. The mechanisms of photoactivity enhancement for composite films have also been discussed.  相似文献   

12.
It is known from the literature that the reaction 2 NO2(aq) + Cl-(aq) → NO3-(aq) + ClNO(g) takes place in the presence of NO2 and sea salt aerosol. This work indicates that the reaction is first order in Cl- and second order in NO2(aq) and the rate coefficient was determined to be 8.9 ± 2.1) × 1010 M-2 s-1 at 293 K. The study shows that the formation rate of nitrate in liquid sea salt aerosol is not influenced by pH in the range between 5.1 and 7.5. The uptake of ammonia in liquid sea salt particles in the present experimental system is governed by the rate of the reaction CO2(aq) + H2O → H2CO3. The addition of NH3 to NO2 and dry sea salt particles does not change the extent of nitrate formation in the particles. The dry aerosol shows an unexpected content of ammonium which increases with decreasing relative humidity. The nitrate formation in frozen sea salt particles at 266 K exposed to only NO2, is about 5 times lower than for the corresponding droplets at 293 K.  相似文献   

13.
The delafossite CuCrO2 is a promising candidate for the visible light driven catalysis. The NO2 ? removal by photoelectrochemical process is studied under mild conditions, close to that encountered in the natural environment. CuCrO2 exhibits a long term chemical stability with a corrosion rate of 0.34 μmol m?2 year?1 in KCl (0.5 M). A forbidden band of 1.3 eV has been evaluated from the diffuse reflectance spectrum. The flat band potential (?0.07 V SCE) determined from the Mott–Schottky plot is close to the photocurrent onset potential (0 V SCE). Hence, the conduction band is positioned at ?1.08 V SCE and thus lies below the NO2 ? level leading to a feasible reduction upon visible illumination. The conversion occurs in less than ～5 h with a quantum efficiency of ～0.5%. The possibility of identifying the reaction products via the intensity–potential characteristics was explored by using standard solutions. The decrease of the conversion rate over time is attributed to the competitive water reduction. In absence of catalyst, NO2 ? is oxidized to NO3 ? in air equilibrated solution and the reaction follows a first order kinetic with a half life of 21 h, NO3 ? has been identified by iodometry through copper titration.  相似文献   

14.
A total of 45 cyanobacterial strains isolated from rice fields near Loktak Lake in Manipur, India were tested for their rice root colonization capacity under light and under darkness. Twenty-one of these strains showed significant colonization of rice roots. The average colonization values were 637 and 381?μg chl a g?1 root dry wt in N2 medium and 792 and 451?μg chl a g?1 root dry wt in NO 3 ? medium under light and darkness, respectively. Thus, while the colonization was higher under light and in NO 3 ? medium, there was significant level of colonization under darkness in N2 medium (381?μg chl a g?1 root dry wt). A 16S rRNA gene fragment-based denaturing gradient gel electrophoresis analysis revealed difference in the competence of individual strains to colonize rice roots exposed to individual or mixed population. The colonization pattern of seven strains used in competition experiments was found to be biphasic. A 16S rRNA gene-based phylogenetic analysis revealed high level of molecular similarity among strains of Nostoc and Anabaena.  相似文献   

15.
Alan Olness  B.W. Dewey 《Geoderma》1982,28(2):117-128
Fine-textured soil cores were saturated with KNO3 solutions, withdrawn at periodic in tervals and examined for mineral N forms. Reduction of NO3? was correlated with time using a first-order rate function. Instantaneous initial NO3?-N reduction rates were determined by taking derivatives of the rate function and setting t = 0. Duplicate experiments gave maximum NO3?-N reduction rates of 1.0 μ N/g soil/h or ? 100 kg NO3?-N/ha/day. Calculated NO3? reduction rates increased with depth down to 30 cm. Net NO3?-N reduction ceased between 48 and 96 h after which net NO3?-N production of 0.016 to 0.29 μg N/g soil/h (～1.5 kg N/ha/day/0 to 20 cm) occurred. Net NH4+-N mineralization ranged from about 0.03 to 0.05 μg N/g soil/h (3.5 to 4.0 kg N/ha/day/0 to 30 cm). Both instantaneous initial NO3?-N loss rates and N mineralization rates are similar to results of laboratory studies elsewhere on similar soil types. This procedure for estimating N-transformations may be useful where other techniques are either not adequate or not feasible for field use.  相似文献   

16.
Long term continuous monitoring measurements of urban atmospheric concentrations of O3, NO2, NO, and SO2 were performed for the first time in Ciudad Real, a city in central-southern Spain. The measurements were carried out using the differential optical absorption spectroscopy (DOAS) technique, with a commercial system (OPSIS, Lund-Sweden), covering the summer and winter seasons (from 21st July 2000 to 23rd March 2001). Mean levels of O3, NO2 and SO2 monitored during this period were: 27 μg m?3, 50 μg m?3 and 7 μg m?3 respectively. The highest hourly averaged value of O3 (160 μg m?3) was measured during the summer period, while NO2 was enhanced in wintertime (highest values 90 μg m?3). In the coldest period, when central heating installations were operating, SO2 showed maximum levels of 20 μg m?3. The daily, weekly and seasonal analysis of the data shows that photochemical air pollution dominates in this urban atmosphere and is strongly influenced by levels of motor traffic and domestic heating system emissions. These measurements were compared with other studies in Spain and Europe. Also, the long path averaged DOAS measurements were compared with in situ observations made in Ciudad Real, from 23rd August 2000 to 25th September 2000, using a mobile air pollution control station. All gas concentrations reported in this paper are below the WHO guidelines and the different thresholds introduced by the European Environmental Legislation.  相似文献   

17.
The solubility and stability of calcium arsenates at 25 °C was determined by both precipitation and dissolution experiments. Ca3(AsO4)2? 3H2O(c), Ca3(AsO4)2? 21/4H2O(c), Ca5(AsO4)3(OH)(c) and Ca4(OH)2(AsO4)2? 4H2O(c) were identified in our experiment over a wide range of pH and for Ca/As molar ratios between 1.25 and 4.0. The solids precipitated at pH = 3 ～ 7 and Ca/As = 1.5 were phase-pure and well-crystallized Ca3(AsO4)2? xH2O(c) and had relatively larger grain size than those formed at pH > 7. Based on the analytical results and using the computer program PHREEQC, the solubility products for Ca3(AsO4)2? 3H2O(c), Ca3(AsO4)2? 21/4H2O(c), Ca5(AsO4)3(OH)(c) and Ca4(OH)2(AsO4)2? 4H2O(c) were calculated as K sp of 10? 21.14(10? 20.01 ～ 10? 22.02), 10? 21.40(10? 20.08 ～ 10? 21.98), 10? 40.12(10? 37.53 ～ 10? 42.72) and 10? 27.49(10? 26.10 ～ 10? 28.91), respectively. Correspondingly, the free energies of forming (Δ G f o ) of these calcium arsenates were calculated to be ?3787.87 kJ/mol, ?3611.50 kJ/mol, ?5096.47 kJ/mol and ?4928.86 kJ/mol.  相似文献   

18.
Nitrous oxide emission (N2O) from applied fertilizer across the different agricultural landscapes especially those of rainfed area is extremely variable (both spatially and temporally), thus posing the greatest challenge to researchers, modelers, and policy makers to accurately predict N2O emissions. Nitrous oxide emissions from a rainfed, maize-planted, black soil (Udic Mollisols) were monitored in the Harbin State Key Agroecological Experimental Station (Harbin, Heilongjiang Province, China). The four treatments were: a bare soil amended with no N (C0) or with 225?kg?N ha?1 (CN), and maize (Zea mays L.)-planted soils fertilized with no N (P0) or with 225?kg?N ha?1 (PN). Nitrous oxide emissions significantly (P?<?0.05) increased from 141?±?5?g N2O-N?ha?1 (C0) to 570?±?33?g N2O-N?ha?1 (CN) in unplanted soil, and from 209?±?29?g N2O-N?ha?1 (P0) to 884?±?45?g N2O-N?ha?1 (PN) in planted soil. Approximately 75?% of N2O emissions were from fertilizer N applied and the emission factor (EF) of applied fertilizer N as N2O in unplanted and planted soils was 0.19 and 0.30?%, respectively. The presence of maize crop significantly (P?<?0.05) increased the N2O emission by 55?% in the N-fertilized soil but not in the N-unfertilized soil. There was a significant (P?<?0.05) interaction effect of fertilization?×?maize on N2O emissions. Nitrous oxide fluxes were significantly affected by soil moisture and soil temperature (P?<?0.05), with the temperature sensitivity of 1.73–2.24, which together explained 62–76?% of seasonal variation in N2O fluxes. Our results demonstrated that N2O emissions from rainfed arable black soils in Northeast China primarily depended on the application of fertilizer N; however, the EF of fertilizer N as N2O was low, probably due to low precipitation and soil moisture.  相似文献   

19.
The efficiency of the photocatalytic degradation of the herbicide quinmerac in aqueous TiO2 suspensions was examined as a function of the type of light source, TiO2 loading, pH, temperature, electron acceptors, and hydroxyl radical (?OH) scavenger. The optimum loading of catalyst was found to be 0.25?mg?mL?1 under UV light at pH?7.2, with the apparent activation energy of the reaction being 13.7?kJ?mol?1. In the first stage of the reaction, the photocatalytic degradation of quinmerac (50???M) followed approximately a pseudo-first order kinetics. The most efficient electron acceptor appeared to be H2O2 along with molecular oxygen. By studying the effect of ethanol as an ?OH scavenger, it was shown that the heterogeneous catalysis takes place mainly via ?OH. The results also showed that the disappearance of quinmerac led to the formation of a number of organic intermediates and ionic byproducts, whereas its complete mineralization occurred in about 120?min. The reaction intermediates (7-chloro-3-methylquinoline-5,8-dione, three isomeric phenols hydroxy-7-chloro-3-methylquinoline-8-carboxylic acids, and 7-chloro-3-(hydroxymethyl)quinoline-8-carboxylic acid) were identified and the kinetics of their appearance/disappearance was followed by LC?CESI?CMS/MS. Tentative photodegradation pathways were proposed and discussed. The study also encompassed the effect of quality of natural water on the rate of removal of quinmerac.  相似文献   

20.
The N2O-flux from an acid soil in the field (limed to pH 5.4) was calculated from measurements of N2O in the gas flow through a soil cover. The N2O-flux showed a seasonal variation and was also influenced by the presence of growing plants. The addition of liquid manure (slurry) resulted in N2O-fluxes of up to 23g N ha?1 day?1 during the spring, in contrast to a maximum of 5 g N ha?1 day?1 from soil supplied with KNO3 or from unfertilized soil. The mean N2O-turnover rate in the 0–30 cm soil layer was 5 times per day. Laboratory incubations in the presence and absence of acetylene suggest that no N2 was formed in association with N2O. The number of N-gas producing bacteria was increased by addition of slurry but not by addition of KNO3. The denitrifying activity increased in the same order. Three groups of nitrate-reducing bacteria producing N-gas were isolated: dominantly N2-formers, for example P. fluorescens, dominantly N2O-formers, mainly Pseudomonas spp, and dominantly NO2?-formers, mainly Bacillus spp.  相似文献   

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