Concentrations of Nitrogen and Sulfur Species in Gas and Rainwater from Six Sites in Indonesia

Gas mixing ratios of SO₂, NO₂ and HNO₃ and nitrate and sulfate concentrations in rainwater have beenmeasured at six sites in Indonesia. The sites, Jakarta, Serang,Cilegon, Merak and Bogor, in Java, and Bukit Koto Tabang inSumatra, provide a range of pollution regimes in Indonesia.Jakarta and Bogor are heavily polluted sites in Java, whereasBukit Koto Tabang is a clean air station in a relativelyunpopulated area on the west coast of equatorial Sumatra. At thesesites rainwater was collected daily and gas samples weeklyduring 1996. The other three sites Serang, Cilegon and Merakrepresent smaller regional towns in west Java. At these sitesrainwater samples were collected weekly from June 1991 untilJune 1992.The results show that Jakarta has the highest volume-weightedmean sulfate concentrations in rainwater while the lowest weremeasured at Bukit Koto Tabang. Volume-weighted mean nitrateconcentration was about 24 μeq L^-1 at Jakarta and Bogor,significantly higher than the 0.8 μeq L^-1 measured atBukit Koto Tabang.Sulfur dioxide mixing ratios ranged from 4–7 ppbv in Jakarta toan average of 1.3 ppbv at Bukit Koto Tabang. Nitrogen dioxidemixing ratio was highest in Jakarta averaging 28 ppbv comparedwith the background mixing ratio of 1.2 ppbv at Bukit KotoTabang. Using dry deposition velocities estimated during aseparate study in the similar conditions of Malaysia enabled drydeposition estimates of SO₂, HNO₃ and NO₂.Results of estimated total acidic S and N deposition (wet anddry) were greater than 250 meq m^-2 yr^-1 at the Jakartaand Bogor sites compared with about 23 meq m^-2 yr^-1 atBukit Koto Tabang. At Jakarta and Bogor dry deposition accountedfor more than 50% of the total deposition estimates compared with about 20% at Bukit Koto Tabang. Such deposition rates arehigh when compared to critical loads estimated for Indonesia bythe RAINS-Asia model. In this model, critical loads in western Java and equatorial western Sumatra fall into one of twoclasses: 50–100 and 20–50 meq m^-2 yr^-1. Thus acidic deposition flux at Jakarta and Bogor wasfound to be above the predicted critical loads even for the moreacid insensitive soils.     

Nitrous and Nitric Acid Measurements Inside and Outside of Clouds at Mt. Brocken

A measurement method for the continuous and in situ analysis of atmospheric concentration of HNO₂ and HNO₃ inside and outside of clouds has successfully been established. The approach for a wet effluent diffusion denuder (parallel plate design) was adopted and performed quasi on-line with an ion chromatography unit. The air flow through the denuder was 10 1/min and at 15 minutes of preconcentration we are able to record atmospheric concentrations of 15 ng/m³ of HNO₂ and HNO₃, respectively. Field measurements using the denuder system were done at the Mt. Brocken summit (1142 m a.s.l., Harz Mountains, Germany) in 1998 and 1999. During day-time and under clear conditions maximum values of HNO₃ up to 7000 ng/m³ were observed. Measurements performed during cloud events assess first time our expectation that the comparatively very great specific droplet surface in clouds is a place for a heterogeneous HNO₂ formation, after nocturnal accumulation up to 320 ng/m³ were found. Strong positive correlation between HNO₂ concentrations and those of NO₂ were obtained during and after cloud events to assess the origin of the observed nitrous acid. The HNO₂/NO₂ ratio reached 10% under humid conditions. The observed surface to volume ratios in investigated clouds were between 0.4 and 0.7. In dependence on the cloud water pH nitrite concentrations between 5–300 µg/l (1–30 ng/m³ air) were observed.     

The effects of acid nitrogen and acid sulphur deposition on CH4 oxidation in a forest soil: a laboratory study

Sieved soil and soil core experiments were performed to determine the potential sensitivity of forest soil CH₄ oxidation to oxidised N, reduced N and oxidised S atmospheric deposition. Ammonium sulphate was used to simulate reduced N deposition, HNO₃ oxidised N deposition and H₂SO₄ oxidised S deposition. The effects of NH₄⁺, NO₃⁻, SO₄²⁻ and H⁺ on soil CH₄ flux were shown to be governed by the associated counter-anion or cation of the investigated ions. Ammonium sulphate, at concentrations greater than those that would be experienced in polluted throughfall, showed a low potential to cause inhibition of CH₄ oxidation. In contrast, HNO₃ strongly inhibited net CH₄ oxidation in sieved soils and also in soil cores. In addition, soil CO₂ production was inhibited and the organic and mineral soil horizons acidified in HNO₃ treated soil cores. This suggested that the HNO₃ effect on CH₄ flux might be indirectly mediated through aluminium toxicity. Sulphuric acid only inhibited CH₄ oxidation when added at pH 1. At concentrations more representative of heavily polluted throughfall, H₂SO₄ had no effect on soil CH₄ flux or CO₂ production from soil cores, even after 210 days of repeated addition. In contrast to HNO₃ additions, acidification of the soil was not marked and was only significant for the mineral soil. The findings suggest that the response of forest soil CH₄ oxidation to atmospheric acid deposition is strongly dependent on the form of acid deposition.     

Are enchytraeid worms (Oligochaeta) sensitive indicators of ammonia-N impacts on an ombrotrophic bog?

Enchytraeid worms (Oligochaeta) are the dominant mesofauna in wet acidic habitats. They have key roles in biogeochemical cycling, and can be used as biological indicators. Here we report the response of these worms to in situ ammonia-N (NH₃-N) deposition on an ombrotrophic bog. Three years of NH₃-N fumigation from an automated release system has created a gradient of NH₃-N concentrations downwind of the release pipe ranging from 83 μg m⁻³ (near source) to 4.5 μg m⁻³ NH₃-N (60 m from release pipe); the ambient NH₃-N concentration is 0.56 μg m⁻³ NH₃-N. Peat pH and mineral N content have increased near the ammonia release pipe. We hypothesised that enhanced N deposition at the site would have improved litter quality and thus, enchytraeid distribution would be increased along the transect compared to ambient. However, neither litter quality nor enchytraeid abundance and diversity were affected by NH₃-N despite increases in peat pH and mineral N. This suggests that three years of ammonia fumigation was not enough time for plant matter exposed to ammonia to become incorporated into the peat litter layer. Enchytraeids appear not to be sensitive indicators of NH₃ fumigation because there was no effect below-ground of peat chemistry on litter quality.     

Simulation of Dry Deposition Rates of Acidic Pollutants—An Assessment of Deposition Pathways in Hiroshima, Japan

A eulerian grid photochemical transport and dispersion model was used to simulate the dry deposition rates of nitrogen (as HNO₃) and sulfur (as SO₂) in Hiroshima, west Japan. Seasonal patterns of predicted dry deposition fluxes reveal that HNO₃ is most prevalent at more remote locations while SO₂ is deposited near to and slightly downwind from the major emission sources. The predicted dry deposition rates of HNO₃ and SO₂ were compared to the values measured at Mt. Gokurakuji (located in Hatsukaichi) and in Hiroshima City. The simulation results show that the model under-predicted (about 44% and 80%, respectively) both nitrogen and sulfur deposition rates at Mt. Gokurakuji and in Hiroshima City, indicating that the acid deposition in Hiroshima prefecture is possibly affected by long-range transboundary transport of acidic pollutants. Comparison of wet to dry deposition ratios (4.5 and 8.7 for nitrogen and 4.6 and 7.0 for sulfur) from the two observation sites above indicates that wet deposition maybe the most important acid deposition pathway in Hiroshima, Japan.     

Dry deposition to snow in an urban area

Ambient particle and gas concentrations, wet deposition and dry deposition were measured in Warren, MI between December 18, 1983 and April 6, 1984. Dry deposition was measured to various surfaces in a cutoff bucket, including a snow surface, a snow/water surface during melting and a deionized water surface. Dry deposition velocities were calculated for various species from the ratio of the dry flux to the ambient concentrations. The dry deposition velocities measured to a snow surface were 0.082 cm s^?1 SO₂ 2.0 for HNO₃, 0.083 for NH₄ ⁺, 2.0 for Ca⁺⁺ and 4.3 for Cl^?. The values were not significantly different for a snow/water surface during melting compared to a snow surface. However, higher values of 0.69 cm s^?1 for SO₂, 6.2 for HNO₃, 0.33 for NH₄ ⁺, and 4.2 for Ca⁺⁺ were found to a deionized water surface in the spring. These higher values could be due to the higher air temperature, the pH of the liquid or to increased atmospheric mixing during this period.     

Simultaneous Determination of Gas and Particle Dry Deposition onto Conditioned Surrogate Surfaces

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.     

Estimation of Dry Deposition by Using a Filter Pack Method at Chunchon, Korea

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.     

A Case Study on Estimation of Dry Deposition of Sulfur and Nitrogen Compounds by Inferential Method

In order to estimate dry deposition, deposition velocity calculation and concentration measurement were carried out in Niigata, Japan. Deposition velocities of SO₂ and HNO₃ for some surfaces such as coniferous forest, deciduous forest, agricultural land, and water were calculated taking into account diurnal variations of meteorological elements using routine meteorological data. Deposition velocities of fine and coarse aerosols were also estimated respectively. Concentrations of SO₂, HNO₃, sulfate and nitrate in fine and coarse aerosols respectively were measured from July to December in 1998 using filter pack and denuder methods. The results indicate that HNO₃ dry deposition for the high aerodynamic roughness surfaces such as forests is quite large. It is suggested that sulfate and nitrate aerosols depositions as well as the gases depositions should be taken into account to estimate dry deposition of sulfur and nitrogen compounds. It is also indicated that dry depositions of sulfur and nitrogen compounds are unable to ignore compared with their wet depositions.     

Chemical Composition of Air, Soil and Vegetation in Forests of the Silesian Beskid Moutains, Poland

For the first time concentrations of trace nitrogenous (N) air pollutants, gaseous nitric acid (HNO₃), nitrous acid (HNO₂), ammonia (NH₃), and fine particulate nitrate (NO₃) and ammonium (NH₄), were measured in the montane forests of southern Poland. Determinations were performed in two forest locations of the Silesian Beskid Mountains in the western range of the Carpathian Mountains, and in an industrial/urban location in Karowice, Poland. The measurements performed in summer 1997 with honeycomb denuder/filter pack systems showed elevated concentrations of the studied pollutants. These findings agree with the low carbon/nitrogen (C/N) ratios and the results of ¹⁵N analyses of soil and moss samples. High concentrations of N air pollutants help to explain previously determined high levels of NO₃ and NH4 deposition to Norway spruce (Picea abies Karst.) canopies in these mountains. Ambient concentrations of sulfur dioxide (SO2) and ozone (O3) were elevated and potentially phytotoxic. Deficiencies of phosphorus (P) and magnesium (Mg) in Norway spruce foliage were found while concentrations of other nutrients were normal.     

The generation of aerosols by binary homogeneous nucleation

The rates of nucleation of liquid aerosols from the gaseous mixtures H₂SO₄ + H₂O and HNO₃ + H₂O at 25°C for various relative humidities (10 to 100%) and various activities of acid vapor are calculated using the Flood-Neumann-Döring-Reiss-Doyle theory of binary homogeneous nucleation. The activities of acid vapor needed for nucleation are 25 to 300 times smaller for H₂SO₄ + H₂O than for HNO₃ + H₂O. This is due to the much larger free energy of mixing in the liquid phase for H₂SO₄ + H₂O. Conversion from activities to actual pressures leads to concentrations of HNO₃ which are much too high to be found under normal atmospheric conditions. On the other hand, the concentrations of H₂SO₄ vapor needed to nucleate droplets in the H₂SO₄ + H₂O system are in the range 4(10^?5) to 1.3 (10^?2) ppm, a concentration which can result from photo-oxidation of SO₂ in the atmosphere. Calculations are made of the growth curves for H₂SO₄ + H₂O droplets (radius vs composition) at various relative humidities from the critical size radius up to a 1000 Å radius, corresponding to nuclei large enough to serve as condensation centers for heterogeneous nucleation. The limitations of binary homogeneous nucleation theory at extremely low concentrations of one of the components are discussed and it is shown that this theory becomes inapplicable if the actual vapor pressure of one component is below 10^?6 torr.     

Simultaneous exposure of forest trees to pollutants and climatic stress

This paper describes a facility designed to simultaneously generate complex climatic and pollutant conditions for research into the effects of climate and air pollution on plants. The system, commissioned in 1985, consists of a set of 4 environmental chambers which are each equipped with four identical subchambers. These 4 subchambers are subjected to identical climatic conditions, but are equipped with independent gas supplies. The chambers are designed to operate within a temperature range of -20 to +40° C at a relative humidity of 20 to 95 % with an illumination system providing high light intensities at a spectrum very close to sunlight. A computer controlled fumigation system allows the injection of various gases singly and in combination at concentrations between 0.005 to l,000 ppm (SO₂, NO_x, O₃, CO₂, PAN).     

Effect of acid modification of biochar on nutrient availability and maize growth in a calcareous soil

The nutritional quality of acid‐modified poultry manure biochar is unclear, so a better understanding of its properties and agronomic potential is needed. The biochar was modified with phosphoric acid (H₃PO₄) and nitric acid (HNO₃) and a combination of the two, before and after pyrolysis. After characterization of biochar samples and determination of total and water‐soluble mineral element concentrations, biochars were applied to a calcareous soil at a rate of 0.5% (w/w) to find out their effects on the mineral nutrition and growth of maize. Treatment with H₃PO₄+ HNO₃ enriches the biochar with phosphate, nitro groups and nitrate. The experimental results suggested that biochar modified with HNO₃ and/or HNO₃+H₃PO₄ after pyrolysis increased the water‐soluble phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu) and manganese (Mn) concentrations and increased plant‐available nutrients and plant growth by positively affecting the absorption of plant nutrients. The highest plant dry weight was obtained from biochar post‐treated with HNO₃+H₃PO_4, and this was followed by HNO₃‐ and H₃PO₄‐modified biochars. Premodification with HNO₃+H₃PO4 also significantly increased plant dry weights. The results of this study revealed that poultry manure biochar modified with HNO₃ and H₃PO₄ can be used effectively in calcareous soil for the improvement of plant mineral nutrition.     

Comparison of three wet digestion methods for the determination of plant sulphur by inductively coupled plasma atomic emission spectroscopy (ICP‐AES)

Abstract

Increased incidence of sulphur (S) deficiency in crops has led to a greater need for S determination in plant tissues. Among the methods available for measurement of S, inductively coupled plasma atomic emission spectrometry (ICP‐AES) has been proved to be accurate and rapid. This paper compares digestion with HNO₃‐HClO₄, fuming HNO₃‐KNO₃ and alkaline NaOBr prior to the S measurement by ICP‐AES. Both HNO₃‐HClO₄ and fuming HNO₃‐KNO₃ were found to give satisfactory results for five certified plant materials, with high accuracy and precision. The HNO₃‐HClO₄ method involved a rigid temperature control, with slow ramp rates and a final temperature (190°C) lower than the boiling point of HClO₄, to minimise the possibility of gaseous losses of S. Both methods can also be used for the simultaneous determination of phosphorus (P), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn), and additionally potassium (K) with HNO₃‐HClO₄. In contrast, the alkaline NaOBr method was less suitable as a digestion procedure for S measurement by ICP‐AES, because it involved a large dilution factor and produced high blank values.     

Specifics and Temporal Changes in Air Pollution in Areas Affected by Emissions from Oil Shale Industry, Estonia

Atmospheric air pollution levels and long-term effects on the environment caused by simultaneous presence of SO₂ and oil shale alkaline fly ash during the last five decades (since 1950) were investigated. The annual critical value of SO₂ for forest (20 µg m^?3) was surpassed in 1% (～35 km²) of the study area where the load was 30–40 µg m^?3. No effect of long-term SO₂ concentrations of up to 10–11 µg m^?3 (0.5-h max up to 270 µg m^?3) and simultaneous fly ash loads of up to 95 µg m^?3 (1000 µg m^?3) on the growth and needle longevity of Pinus sylvestris was established. The yearly deposition (average load up to 20–100 kg S ha^?1) was alkaline rather than acidic due to an elevated base cation deposition in 1960–1989. Since 1990, the proportion of SO₂ in the balance of components increased: about 70–85% of the total area was affected while the ratio of annual average concentrations of SO₂ to fly ash was over 1. The limit values of fly ash for Sphagnum mosses and conifers in the presence of SO₂ are recommended.     

山西省太原市旱作农区大气活性氮干湿沉降年度变化特征

鉴于大气氮素沉降对整个生态系统的重要影响,我国近年来陆续开展了不同尺度的大气氮素干、湿沉降的研究,但少有农业区多年连续监测的资料。本研究利用DELTA系统、被动采样器和雨量器在山西省太原市郊区阳曲县河村旱作农业区进行了4年的监测试验,观测大气氮素干、湿沉降的时间变异。结果表明:2011年4月—2015年3月,河村4年大气活性氮NH_3、HNO_3、NO_2、颗粒态NO_3~-(pNO_3~-)、颗粒态NH_4~+(pNH_4~+)平均沉降量分别为4.50 kg(N)·hm~(-2)·a~(-1)、3.54 kg(N)·hm~(-2)·a~(-1)、2.56 kg(N)·hm~(-2)·a~(-1)、1.62 kg(N)·hm~(-2)·a~(-1)、2.75 kg(N)·hm~(-2)·a~(-1),大气氮素干沉降总量为12.38~18.95 kg(N)·hm~(-2)·a~(-1),以2011年的氮干沉降量最高,2014年的最低。2011年4月—2015年3月各月氮干沉降量与氨气沉降量之间存在显著正相关,相关系数在0.809 8~0.937 1,由此可知,该地区活性氮沉降主要受农业氨气排放的影响。河村4年雨水中NO_3~-、NH_4~+平均浓度分别为3.20 mg(N)·L~(-1)和2.43 mg(N)·L~(-1),大气氮素湿沉降11.67~41.31 kg(N)·hm~(-2)·a~(-1)。年度间氮素湿沉降存在很大差异,以2012年氮素年湿沉降量最高,2014年最低,每年大气氮素湿沉降占氮总沉降量的份额超过50%。此外,4年湿沉降中不仅NO_3~--N和NH_4~+-N之间、且二者与降雨量也呈显著线性或二次相关关系,说明降雨量对NO_3~--N和NH_4~+-N的湿沉降影响较大。本研究表明太原市旱作农区不同年份间氮素湿沉降比干沉降差异更大,且总沉降数量较高。虽然是旱作区,该地区氮素干沉降略低于湿沉降。研究结果为该地区农田氮肥施用和氮素循环监测提供了理论依据。     

Extractability of major and trace elements from agricultural soils using chemical extraction methods: Application for phytoavailability assessment

Abstract

To assess soil-to-plant transfer of various elements more precisely, the concentrations of the elements extracted from soil samples using eight chemical solutions were compared with the results of a pot cultivation experiment of komatsuna (Brassica rapa L. var. perviridis) or buckwheat (Fagopyrum esculentum M.) using the soils. From agricultural fields in Aomori, Japan, 16 soil samples were collected. Elements in the samples were extracted using acids (1 mol L^?1 HNO₃, 0.1 mol L^?1 HNO₃, 0.01 mol L^?1 HNO₃), chelating agents (0.05 mol L^?1 EDTA), neutral salt solutions (1 mol L^?1 NH₄OAc, 1 mol L^?1 NH₄NO₃, 0.01 mol L^?1 CaCl₂) and pure water. The 28 elements in the extracted solutions and plant samples were determined. The extractability of many metals was higher in 1 mol L^?1 HNO₃, 0.1 mol L^?1 HNO₃ and the 0.05 mol L^?1 EDTA solutions than in the other extractants. Higher extractability using the NH₄OAc solution than the NH₄NO₃ solution was observed for some elements, in particular U. Extractability by pure water was not always lowest among these methods, probably because of dispersion of colloidal substances in the extracted solution. The pot cultivation experiment showed that the concentrations in soil and in the extracted fraction using 1 mol L^?1 HNO₃, 0.1 mol L^?1 HNO₃ or the EDTA solution did not correlate with the concentration in plant samples for most elements. Plant uptake of Zn, Y and La by komatsuna correlated well with their concentrations in extracts with neutral salt solutions or 0.01 mol L^?1 HNO₃. Concentrations of Al, Cu and Cd in buckwheat were also correlated with the concentrations in the extracts.     

Dry and Wet Deposition of Nitrogen Emitted in Buenos Aires City to Waters of de la Plata River

Dry and wet deposition of atmospheric nitrogen species (NO₂ and HNO₃) coming from nitrogen oxides emissions in Buenos Aires city to surface waters of de la Plata River were estimated. Atmospheric dispersion models DAUMOD-RD (v.2) and CALPUFF were applied to area and point sources, respectively. These models were run considering 1 year of hourly meteorological data. Emission information included a typical diurnal variation of area source emissions. Annual atmospheric nitrogen (N–NO₂?+?N–HNO₃) deposition to 1,763 km² of the river was 35,600 kg-N year^?1. Dry deposition processes accounted for 89% of this value. The small contribution of wet deposition was a consequence of the very few cases (5%) of rain events during offshore wind conditions. Monthly dry deposition to 1,763 km² of the river varied from 1,628 kg-N month^?1 in February to 3,799 kg-N month^?1 in December, following the monthly occurrence of offshore winds. Monthly wet deposition varied from 1 kg-N month^?1 in June to 1,162 kg-N month^?1 in February. These results came from the combination of favorable conditions for formation of HNO₃ and the occurrence of precipitation during offshore wind situations. Spatial distribution of annual atmospheric N deposition showed a strong coastal gradient. Deposition values reached a maximum of 137.1 kg-N km^?2 year^?1 near the shoreline, which was reduced to the half at 4 km from the coast.     

Atmospheric Deposition of Acidifying Components to a Japanese Cedar Forest

One-year field measurements were conducted in a Japanese cedar (Cryptomeria japonica) forest, located in Gunma Prefecture, Japan. On the basis of the meteorological and atmospheric concentration data, the dry deposition of SO₂, HNO₃, NO₂ and HCl was estimated using the inferential method. The annual dry deposition of H⁺ was estimated at 721 eq ha^?1yr^?1, which was 40% larger than the measured annual wet deposition of H⁺ (514 eq ha^?1yr^?1). Therefore, dry deposition is an important pathway for the atmospheric input of H⁺ to the forest in the study site. The contribution of each gas to the dry deposition of H⁺ was as follows: SO₂, 25%; HNO₃, 32%; NO₂, 10%; and HCl, 33%. The extremely high contribution of HCl appeared to be caused by the high emission intensity of HCl due to waste incineration in the site region. The differences between estimated deposition and throughfall and stemflow measurements indicated that about 80% of the total deposition of H⁺ was taken up by the canopy.     

The dry deposition of gaseous and participate nitrogen compounds to a spruce stand

The dry deposition of particle-bound NH₄ ⁺ and NO₃ ^– and of gaseous NH₃ and HNO₃ to a 45 year old Norway Spruce forest was determined by the inferential method. Deposition velocities were calculated from meteorological data and plant morphology by a multi-layer model which combines the transfer of the trace substances within the canopy and their absorption probabilities due to a variety of deposition mechanisms. For gaseous deposition the same mathematical concept was adopted as for particles. That means that this approach is an alternative to the common concept of resistance analogy. The mean deposition velocities found were 0.47 cm s^–1 for NH₄ ⁺ and 1.85 cm s^–1 for NO₃ ^–. While these values are in the range found in other studies, the mean deposition velocities for the gases were quite large. For NH₃ 13 cm s^–1 were found and for HNO₃ 11 cm s^–1. It is suggested that the absorption of these gases on the plant surfaces is not as effective as assumed in the model.