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1.
Atmospheric nitrogen species (NH4-N and (NO3+NO2)-N) were determined in weekly samples of atmospheric bulk deposition (dry plus wet), collected in France at seven sites over the course of a year. Rural, semi-rural and industrialised-urban sites were chosen in the Seine river watershed from the Seine estuary to upstream from Paris. Mean NH4-N concentrations varied from 0.7 to 1.7 mg L-1. Mean (NO3+NO2)-N concentrations were approximately 0.5 mg L-1 for all sites except Paris (0.7 mg L-1), which has a local impact on the fallout contamination from urban emissions. The relation between concentration and rainfall amount obeys a power law, in the form of y = ax b. When the nitrogen sources are very local, this relationship turns into a dilution law. Annual atmospheric nitrogen deposition (NH4-N+(NO3+NO2)-N) was calculated and varied from 7.8 kg ha-1 yr-1 in the neighbourhood of a rural town to 17.3 kg ha-1 yr-1 in a very industrialised harbour. 58% of the atmospheric nitrogen deposition occurred during ‘spring + summer’ period. The total nitrogen atmospheric input to the Seine estuary, via direct deposition + indirect input via the watershed, was estimated to about 5% of the total nitrogen load within the Seine river basin.  相似文献   

2.
This paper presents the simultaneous measurement of atmospheric concentration of gaseous NH3, SO2 and NO2, and particulate NH 4 + released from the mining activities of coal-mine area, Tirap colliery, Margherita (Assam). Gas samples were collected by impinger method and were analyzed colorimetrically. The vapor-phase concentration of NH3, SO2, and NO2 range between 4.7?C40.03, 1.47?C6.14, and 1.92?C2.40???g/m3. The NH 4 + concentration in PM10 and PM2.5 ranges between 0.02?C0.07 and 0.008?C0.03???g/m3, respectively. Moderately high concentrations of NH3 and SO2 on the first day were due to the coal-burning activity near the sampling site, while the low concentration of NO2 is due to less vehicle density near the sampling point. All the observed concentrations are below than those reported for the urban areas and the prescribed limit fixed by National Ambient Air Quality Standard, India. Study indicates that ammonia is the major neutralizing agent for sulfate and nitrate ions present in the particulate matter during mining activities.  相似文献   

3.
We examined the influence of various urea granule sizes (< 2, 7.0, 9.9 and 12.7 mm) applied into a silt loam soil (experiment 1) and soil types (sandy, silt and clay loam) treated with the largest granule (experiment 2) on gaseous N loss (except N2) at field capacity. The prilled urea (PU) was mixed into the soil whereas the urea granules were point-placed at a 5.0-cm depth. For experiment 1, N2O emission was enhanced with increasing granule size, ranging from 0.17–0.50% of the added N during the 45-day incubation period. In the case of experiment 2, the sandy loam soil (0.59%) behaved similarly with the silt loam (0.53%) but both showed remarkably lower emissions than were found for the clay loam soil (2.61%). Both nitrification and N2O emissions were delayed by several days with increasing granule size, and the latter was influenced by mineral N, soil water and pH. By contrast, the NH3 volatilization decreased with increasing granule size, implying the inhibition of urease activity by urea concentration gradients. Considering both experimental results, the NH3 loss was highest for the PU-treated (1.73%) and the larger granules regardless of soil type did not emit more than 0.27% of the added N over 22 days, possibly because the high concentrations of either mineral N or NH4 + in the soil surface layer (0–2.5 cm) and the high H+ buffering capacity might regulate the NH3 emission. Similar to the pattern of NH3 loss, NOx emission was noticeably higher for the PU-treated soil (0.97%) than for the larger granule sizes (0.09–0.29%), which were the highest for the sandy and clay loam soils. Positional differences in the concentration of mineral N and nitrification also influenced the NOx emission. As such, total NH3 loss was proportional to total NOx emission, indicating similar influence of soil and environmental conditions on both. Pooled total N2O, NH3 and NOx emission data suggest that the PU-treated soil could induce greater gaseous N loss over larger urea granules, largely in the form of NH3 and NOx emissions, whereas a similar increase with the largest granule size was mainly due to the total N2O flux.  相似文献   

4.
N2O emissions from soils treated with NH4+-N under aerobic conditions in the laboratory were 3- to 4-fold higher than those from controls (no extra N added) or when NO3?-N was added. Although the emission of N2O-N in these field and laboratory experiments represented only 0.1–0.8% of the applied fertilizer NH4+-N and are therefore not significant from an agronomic standpoint, these studies have conclusively demonstrated that the oxidation of applied ammoniacal fertilizers (nitrification) could contribute significantly to the stratospheric N2O pool.Like N-serve, acetylene was shown to be a potent inhibitor of nitrification as it stopped the oxidation of NH4+-N to (NO3+-N + NO2?)-N and hence reduced the evolution of N2O from nitrification within 60 min after its addition.Although high amounts of NO3?-N were present, the rate of denitrification was very low from soils with moisture up to 60% saturation. The further increase in the degree of saturation resulted in several-fold increase of denitrification which eventually became the predominant mechanism of gaseous N losses under anaerobic conditions.  相似文献   

5.
Suspended particulate matter (SPM) and PM2.5 in the urban and suburban atmosphere of the Kanto Plain of Japan, which includes the Tokyo metropolitan area, during the period 22–26 July 2002 were characterized. Samples of SPM and PM2.5 were collected by low-volume samplers at 6-h intervals at Suginami, Saitama, and Kisai. At all the sites, the major components of SPM and PM2.5 were organic carbon (OC), elemental carbon (EC), and sulfate. The ion balance, the size distributions of the ionic species, and the high correlation between SO4 2? and NH4 + indicated that the main chemical form of sulfate was (NH4)2SO4. The OC/EC ratios were larger in the daytime than in the nighttime. The correlation coefficients of OC, OC/EC, and SO4 2? with ozone concentrations at inland sites (Saitama, Kisai) were higher than those at the coastal site (Suginami). Bound water and hydrogen and oxygen atoms associated with OC, the amounts of which were estimated with a mass closure model, contributed substantially to the total particle mass. The chemical characteristics of the particles indicated that two mechanisms led to high concentrations of SPM and PM2.5: (i) an active photochemical process produced high concentrations of OC and sulfate, leading to a high concentration of (NH4)2SO4 in the particles and to production of secondary organic aerosols; (ii) stable meteorological conditions resulted in accumulation of primary particles, mainly emitted from vehicle exhaust, resulting in high concentrations of OC and EC.  相似文献   

6.
Gas and aerosol measurements were performed at 3 ground based measuring sites at Mt. Rigi in central Switzerland during 2 winter seasons. Both NH3 and NH4 + show a strong vertical concentration gradient between the top station (1620 masl) and the bottom station (430 masl). High concentrations of NH3 with values up to 29 ppbv, were found at the bottom station. HNO3 concentrations were usually below 1 ppbv, with lower values at the bottom station than at the top station that presumably reflect particulate NH4NO3 formation due to high NH3 concentrations at the lower site. No vertical concentration gradient was found for SO2. Simple models have been used to estimate below-cloud scavenging of gaseous NH3 and particulate NH4 + by rain between two sites with a vertical separation of 600 m. The calculations used measurements from three case studies. Below-cloud scavenging of NH3 by rain was found to be more important than below-cloud NH4 + scavenging. From 58 to 88 % of the increase of [NH4 +] in precipitation between the two sampling sites was calculated to result from gas scavenging. Both observations and scavenging calculations were in relatively good agreement for three events. Observations from the present study and tests using different aerosol and raindrop diameters in the calculations point to the importance of using real data in below-cloud scavenging studies considering the relative importance of aerosol and gas scavenging.  相似文献   

7.
Aerodynamically designed surrogate surfaces were used to determine the relative importance of gaseous (SO2, HNO3, NH3) and particulate species (SO4 2?, NO3 ?, NH4 +, Ca2+) in the dry deposition flux. For 11 sampling periods, we measured the deposition fluxes, ambient gaseous concentrations, size distributions of atmospheric aerosols and some meteorological parameters in Uji. The dry deposition of the gas to a nearly perfect sink was calculated by subtracting the greased surface flux from the total deposition flux to both the greased and reagent impregnated (or water) surface. It was found that the gas phase deposition contributed significantly more (60–93%) than the particulate phase to overall deposition of sulfur and nitrogen compounds. The dry deposition velocities of the species were also calculated using the deposition fluxes and the measured ambient concentrations. Comparisons were made between the measured and modeled particulate deposition flux.  相似文献   

8.
The temporal and vertical distributions of four N species, N03 ?, NO2 ?, total ammonia (T-NH3), and free ammonia (NH3), are documented for Onondaga Lake, an urban, polluted, hypereutrophic, dimictic, lake that receives a very high load of T-NH3. Nitrate and NO2 ? were lost rapidly from the hypolimnion, and T-NH3 accumulated to high concentrations (maximum > 10 mgN L?1), after the onset of anoxia, consistent with the lake's high level of productivity. The concentrations of T-NH3, NH3 and N03 ? that were maintained in the epilimnion (average concentrations at a depth of 1 m of 2.81, 0.16 and 0.91 mgN L?1, respectively), and concentrations of N02 ? that developed in the epilimnion (maximum of 0.48 mgN L?1), were high in comparison to levels reported in the literature. These elevated concentrations are largely a result of the extremely high loads of T-NH3, and its precursors, received by the lake. Water quality problems in the lake related to the prevailing high concentrations of N species include potential toxicity effects and severe lake-wide oxygen depletion during fall turnover.  相似文献   

9.
This paper describes a computational system developed for the compilation of an anthropogenic emission inventory of gaseous pollutants for Greece. The inventory was developed using a geographical information system integrated with SQL programming language to provide high temporal gridded emission fields for CO, NO2, NO, SO2, NH3 and 23 non-methane volatile organic compounds (NMVOCs) species for the reference year 2003. Activity and statistical data from national sources were used for the quantification of emissions from the road transport, the other mobile sources and machinery sectors and from range activities using top-down or bottom-up methodologies. Annual emission data from existing national and European emission databases were also used. The emission data were spatially and temporally disaggregated using source-specific spatiotemporal indicators. On national scale, the road transport sector produces about 60% of the annual CO and NMVOC total emissions, with gasoline vehicles being the main CO and NMVOC emissions source. The road transport is responsible for approximately half of the higher alkanes and for more than half of the ethene and toluene emissions. The maritime sector accounts for about 40% of the annual total NOx emissions, most of which are emitted by the international shipping subsector, whilst SO2 is emitted mainly by the energy sector. The evaluation of the emissions inventory suggests that it provides a good representation of the amounts of gaseous pollutants emitted on national scale and a good characterisation of the relative composition of CO and NOx emission in the large urban centres.  相似文献   

10.
Maize (Zea mays L. cv. Anjou 256) seedlings were grown hydroponically for 10 d in a split‐root system (3mM N; pH 5.5) under either a homogeneous supply (HS) or a simultaneous, but spatially separated supply (SS) of NH4 + andNO3 ‐. Treatments comprised three NH4 +:NO3 ‐ ratios (1:4, 1:1, 4:1). Shoot dry matter and various root traits (dry matter, number of laterals, length of main axes, total root length and total root surface area) were determined. For all NH4 +:NO3 ‐ ratios, shoot dry matter, root dry matter, total root length, and root surface area, were greater under HS than under SS. Under both SS and HS, increasing NH4 +:NO3 ‐ ratios resulted in decreased shoot and root dry matter production, but did not alter the shoot:root dry matter ratio. Under SS, root dry matter, root length, and root surface area was greater on the NO3 ‐‐fertilized side than on the NH4 + ‐fertilized side. The allocation of root dry matter, root length, and root surface area to the NH4 + or NO3 ‐ compartments was unaffected by changes in the NH4 +:NO3 ‐ ratio. Enhanced NH4 + nutrition has detrimental effects on top growth, but roots are apparently unable to avoid excessive NH4 + uptake by proliferating in zones where NO3 ‐ is the only form of N.  相似文献   

11.
We investigated the expansion of NO3 ?-contaminated groundwater in the Sichuan Basin, China. Nitrogen concentrations and isotopic ratios of NH4 + and NO3 ? were analyzed in groundwater and rain collected from four areas in this basin in order to evaluate the sources of nitrogen pollution. NH4 + in rain, for which δ15N values are strongly negative to slightly positive ?13.4 to + 2.3‰, appears to originate from fertilizers and excretory waste. NO3 ? in rain (δ15N: ?10.2 to ?4.4‰) was attributed to NO x from automobile exhaust gas. In the studied area, well water sampled from farmyards was found to have the highest δ15NNO3 (average: +9.7 ± 4.7‰), indicating contamination by domestic sewage as animal excrement. The lowest δ15NNO3 (?0.2 ± 3.7‰), found in spring water, indicates that the studied groundwater samples are widely affected by air contaminants (mainly as nitrogen oxides) resulted from fuel combustions. The δ15NNO3 (+3.7 ± 2.1‰) values of well water from farmland are between these levels, suggesting that NO3 ? contamination results primarily from cultivation using nitrogen fertilizers, although the contribution from animal excrement cannot be excluded. These results demonstrate that the studied groundwater is widely polluted by locally derived nitrogen sources.  相似文献   

12.
Nitrification inhibitors areuseful for reducing fertilizer related environmentalpollution. Use of such nitrification inhibitors as,benzotriazole, o-nitrophenol, m-nitroaniline anddicyandiamide has effectively regulated nitrification in acitronella (Cymbopogon winterianus Jowitt.) fieldfertilized with urea. At 450 kg N ha-1 yr-1, there wassubstantially higher accumulation of NH+ 4-N in thesoil. Proper placement (5 cm below soil surface) offertilizers have minimized NH3 emissions even fromnitrification inhibitor treated urea plots. Thus, thenitrification inhibitors can potentially reduceenvironmental pollution connected to NO- 3 in soilwhile maintaining low NH3 gas emissions, if thefertilizer is properly placed.  相似文献   

13.
For elucidating the atmospheric deposition contribution of dissolved organic nitrogen (DON) to the total dissolved nitrogen (TDN) deposition rate, dissolved inorganic nitrogen (DIN: NH4 + + NO3 –) and DON deposition rates were annually and monthly estimated during 4 and half-yr monitoring period in an experimental multi-farm under intensive agricultural activities of N fertilizer use and animal husbandry in Central Japan. Annual NH4 +, DON and NO3 – deposition rates in bulk and wet deposition data accounted for 48%, 32% and 20% of TDN deposition, respectively, which indicated that this area is strongly affected by the intensive agricultural activities. The DIN and DON deposition rates were respectively estimated at 21.6 and 10.1 kg N ha?1 yr?1, which ranked high in a worldwide regional data set. Consequently, this area has been exposed to a large amount of N deposition including DON with N fertilizer input. The difference between bulk and wet deposition rates (NH4 + and DON) is one of important factors controlling the N deposition in this area. Monthly DON deposition showed positive correlations with DIN and NH4 + deposition rates, respectively, with a significant linear regression curve. The linear regression curve of our monthly data (n = 127) indicates the same trend as the worldwide annual data set (n = 31).  相似文献   

14.
Amann  M.  Johansson  M.  Lükewille  A.  Schöpp  W.  Apsimon  H.  Warren  R.  Gonzales  T.  Tarrason  L.  Tsyro  S. 《Water, air, and soil pollution》2001,130(1-4):223-228
Exposure to fine particles in the ambient air is recognized as a significant threat to human health. Two pathways contribute to the particle burden in the atmosphere: Fine particles originate from primary emissions, and secondary organic and inorganic particles are formed from the gas phase from the emissions of 'conventional' pollutants such as SO2, NOx, VOC and NH3. Both types of particulate matter can be transported over long distances in the atmosphere. An integrated assessment model for particulate matter developed at IIASA addresses the relative importance of the different types of particulates, distinguishing primary and secondary particles and two size fractions. The model projects these emissions into the future and seeks cost-effective strategies for reducing health risks to population. The model integrates the control of primary emissions of fine particles with strategies to reduce the precursor emissions for the secondary aerosols. Preliminary results addressing the PM2.5 fraction of both primary and secondary particulate matter indicate that in Europe the exposure to particulates will be significantly reduced as a side effect of the emission controls for conventional air pollutants (SO2, NOx, NH3).  相似文献   

15.
Solution pH, temperature, nitrate (NO3 ‐)/yammonium (NH4 +) ratios, and inhibitors effects on the NO3 ‐ and NH4 + uptake rates of coffee (Coffea arabica L.) roots were investigated in short‐term solution culture. At intermediate pH values (4.25 to 5.75) typical of coffee soils, NH4 + and NO3 ‐ uptake rates were similar and nearly independent of pH. Nitrate uptake varied more with temperature than did ammonium. Nitrate uptake increased from 0.05 to 1.01 μmol g‐1 FWh‐1 between 4 and 16°C, and increased three‐fold between 16 to 22°C. Between 4 to 22°C, NH4 + uptake rate increased more gradually from 1.00 to 3.25 μmol g‐1 FW h‐1. In the 22–40°C temperature range, NH4 + and NO3 ‐ uptake rates were similar (averaging 3.65 and 3.56 umol g‐1 FW h‐1, respectively). At concentrations ranging from 0.5 to 3 mM, NO3 ‐ did not influence NH4 + uptake rate. However, NO3 ‐ uptake was significantly reduced when NH4 + was present at 3 mM concentration. Most importantly, total uptake (NO3 ‐+NH4 +) at any NO3 ‐/NH4 + ratio was higher than that of plants fed solely with either NH4 + or NO4 ‐. Anaerobic conditions reduced NO3 ‐ and NH4 + uptake rate by 50 and 30%, respectively, whereas dinitrophenol almost completely inhibited both NH4 + and NO3 ‐ uptake. These results suggest that Arabica coffee is well adapted to acidic soil conditions and can utilize the seasonally prevalent forms of inorganic N. These observations can help optimizing coffee N nutrition by recommending cultural practices maintaining roots in the temperature range optimum for both NH4 + and NO3 ‐ uptake, and by advising N fertilization resulting in a balanced soil inorganic N availability.  相似文献   

16.
In the tropics,frequent nitrogen(N)fertilization of grazing areas can potentially increase nitrous oxide(N2O)emissions.The application of nitrification inhibitors has been reported as an effective management practice for potentially reducing N loss from the soil-plant system and improving N use efficiency(NUE).The aim of this study was to determine the effect of the co-application of nitrapyrin(a nitrification inhibitor,NI)and urea in a tropical Andosol on the behavior of N and the emissions of N2O from autotrophic and heterotrophic nitrification.A greenhouse experiment was performed using a soil(pH 5.9,organic matter content 78 g kg-1,and N 5.6 g kg-1)sown with Cynodon nlemfuensis at 60%water-filled pore space to quantify total N2O emissions,N2O derived from fertilizer,soil ammonium(NH4+)and nitrate(NO3-),and NUE.The study included treatments that received deionized water only(control,NI).No significant differences were observed in soil NH4+content between the UR and UR+NI treatments,probably because of soil mineralization and NO3-produced by heterotrophic nitrification,which is not effectively inhibited by nitrapyrin.After 56 d,N2O emissions in UR(0.51±0.12 mg N2O-N concluded that the soil organic N mineralization and heterotrophic nitrification are the main processes of NH4+and NO3-production.Additionally,it was found that N2O emissions were partially a consequence of the direct oxidation of the soil's organic N via heterotrophic nitrification coupled to denitrification.Finally,the results suggest that nitrapyrin would likely exert significant mitigation on N2O emissions only if a substantial N surplus exists in soils with high organic matter content.  相似文献   

17.

Purpose  

The oxidation of ammonium (NH4+) to nitrate (NO3−) in the soil is an important biogeochemical process, which has major environmental implications as it can contribute to NO3− leaching and nitrous oxide (N2O) emissions. Nitrification inhibitors have been used to slow down this process to reduce NO3− leaching and N2O emissions from agricultural land. The objective of this study was to determine the effectiveness of a liquid formulation of 3,4-Dimethylpyrazole phosphate (DMPP) compared with a dicyandiamide (DCD) solution in inhibiting the growth of ammonium-oxidizing bacteria (AOB) and ammonium oxidizing archaea (AOA) and slowing down the rate of NH4+ oxidation in soil.  相似文献   

18.
Equations are derived for the reactions NH4+ → NO2? → NO3? in a column of inert particulate material containing Nitrosomonas and Nitrobacter and through which a solution is flowing with constant flow rate. The equations are solved analytically for two different assumptions about the growth rates of the nitrifying organisms. The effects of factors such as diffusion, ion exchange and fixation of nutrients by nitrifiers are neglected. The work generalizes a paper of McLaren and corrects a second by the same author.  相似文献   

19.
Agricultural systems that receive high amounts of inorganic nitrogen (N) fertilizer in the form of either ammonium (NH4+), nitrate (NO3−) or a combination thereof are expected to differ in soil N transformation rates and fates of NH4+ and NO3−. Using 15N tracer techniques this study examines how crop plants and soil microbes vary in their ability to take up and compete for fertilizer N on a short time scale (hours to days). Single plants of barley (Hordeum vulgare L. cv. Morex) were grown on two agricultural soils in microcosms which received either NH4+, NO3− or NH4NO3. Within each fertilizer treatment traces of 15NH4+ and 15NO3− were added separately. During 8 days of fertilization the fate of fertilizer 15N into plants, microbial biomass and inorganic soil N pools as well as changes in gross N transformation rates were investigated. One week after fertilization 45-80% of initially applied 15N was recovered in crop plants compared to only 1-10% in soil microbes, proving that plants were the strongest competitors for fertilizer N. In terms of N uptake soil microbes out-competed plants only during the first 4 h of N application independent of soil and fertilizer N form. Within one day microbial N uptake declined substantially, probably due to carbon limitation. In both soils, plants and soil microbes took up more NO3− than NH4+ independent of initially applied N form. Surprisingly, no inhibitory effect of NH4+ on the uptake and assimilation of nitrate in both, plants and microbes, was observed, probably because fast nitrification rates led to a swift depletion of the ammonium pool. Compared to plant and microbial NH4+ uptake rates, gross nitrification rates were 3-75-fold higher, indicating that nitrifiers were the strongest competitors for NH4+ in both soils. The rapid conversion of NH4+ to NO3− and preferential use of NO3− by soil microbes suggest that in agricultural systems with high inorganic N fertilizer inputs the soil microbial community could adapt to high concentrations of NO3− and shift towards enhanced reliance on NO3− for their N supply.  相似文献   

20.
The short-term effects of excessive NH4+-N on selected characteristics of soil unaffected (low annual N inputs) and affected (high annual N inputs) by cattle were investigated under laboratory conditions. The major hypothesis tested was that above a theoretical upper limit of NH4+ concentration, an excess of NH4+-N does not further increase NO3− formation rate in the soil, but only supports accumulation of NO2−-N and gaseous losses of N as N2O. Soils were amended with 10 to 500 μg NH4+-N g−1 soil. In both soils, addition of NH4+-N increased production of NO3−-N until some limit. This limit was higher in cattle-affected soil than in unaffected soil. Production of N2O increased in the whole range of amendments in both soils. At the highest level of NH4+-N addition, NO2−-N accumulated in cattle-affected soil while NO3−-N production decreased in cattle-unaffected soil. Despite being statistically significant, observed effects of high NH4+-N addition were relatively weak. Uptake of mineral N, stimulated by glucose amendment, decreased the mineral N content in both soils, but it also greatly increased production of N2O.  相似文献   

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