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1.
Ullmar Nordén 《Water, air, and soil pollution》1991,60(3-4):209-230
The influence of tree species and soil properties on throughfall fluxes were studied for 5 tree species, growing on initially identical soil. In three mixed deciduous forests with different soil properties, throughfall fluxes of 11 elements were measured during 2 yr for 100 to 150 yr old individuals of Fagus sylvatica L., Quercus robur L., Carpinus betulus L., Tilia cordata Mill. and Acer platanoides L.. Throughfall : precipitation flux ratios were: PO4 3? (11 to 37), K+ (7 to 22), Mn2+ (5 to 14), Mg2+ (3 to 9), Ca2+ (3 to 5), Cl? (1.9 to 2.6), Na+ (1.1 to 2.2), NH4 + (1.5 to 2), SO4 2? (1.5 to 2.1), NO3 ? (0.7 to 1.3) and H+ (0.1 to 0.5). The annual input of S to the soil by throughfall was for Fagus 22 to 29, Quercus 25 to 37, Carpinus 20 to 25, Tilia 24 and Acer 29 kg ha?1. The annual input of N to the soil by throughfall was for Fagus 20 to 29, Quercus 14 to 22, Carpinus 15 to 22, Tilia 22 and Acer 20 kg ha?1. Throughfall fluxes of Na+ and Cl? differed between species, depending on different canopy filtering capacity of sea aerosol, and were greatest for Fagus and Quercus. Throughfall of Ca2+, Mg2+ and K+ were characterized by increased flux from poor to rich sites, with the greatest soil effect on Carpinus, and by a high leaching part, which increased in the same manner. Manganese throughfall showed especially soil effects, characterized of decreased flux from poor to rich sites, but also species effects, of which Carpinus had the greatest flux. pH in throughfall showed a pronounced seasonal variation with pH 6 to 6.5 for Fagus in the foliated season and pH 4.0 to 4.3 in the defoliated season. Carpinus and especially Quercus had lower pH at the poor site, but the differences decreased at the richer sites. The calculated annual acid input to the trees was 4 to 12 times greater than the H+ flux measured as pH in throughfall. An inorganic anion deficit in throughfall, probably due to the presence of organic anions, was proportional to K+, Ca2+ and Mg2+. 相似文献
2.
J. N. Cape L. J. Sheppard J. Binnie P. Arkle C. Woods 《Water, air, and soil pollution》1995,85(4):2247-2252
The estimation of the dry deposition of sulphur dioxide to forests is confounded by the possibility of co-deposition of SO2 with NH3 on leaf surfaces. A sector of Scots pine forest was selectively fumigated with NH3 to give average concentrations up to 15 ppbV (nL L–1) above ambient, in order to test the hypothesis that increased air concentrations of NH3 would enhance the dry deposition of SO2, and the consequent amounts of SO4
2– measured in throughfall below the forest canopy. Ammonia gas, generated by evaporation of concentrated aqueous solution, was released above the canopy in proportion to wind speed when the wind direction was between south and west. Concentrations of NH3 at canopy height were measured using passive diffusion tubes; throughfall was preserved with thymol and measured weekly. Meteorological data and SO2 concentrations were recorded continuously, to permit the estimation of dry deposition input. Deposition of NH4
+ in throughfall over 8 months was increased by up to 40 meq m–2 relative to control sites upwind of the NH3 release point, with largest values closest to the release point. Deposition of SO4
2– in throughfall was also enhanced in the fumigated area, by up to 20 meq m–2, even though average ambient SO2 concentrations were 2.3 ppbV. The results are discussed in terms of the factors controlling SO2 deposition on forest surfaces, the development of appropriate deposition models, and their relevance to using throughfall as an estimate of total S deposition. 相似文献
3.
De Schrijver A. Van Hoydonck G. Nachtergale L. De Keersmaeker L. Mussche S. Lust N. 《Water, air, and soil pollution》2000,122(1-2):77-91
In a forest in Flanders (Belgium), situated in a region of intensive livestock production, comparable stands of Corsican pine and silver birch were studied for (1) NH4 + and NO3 - concentrations in throughfall water and soil solution and (2) depositions and leaching of NH4 + and NO3 - to groundwater. In each stand, throughfall collectors and porous cup lysimeters at three depths (0.1m, 0.5m and 1m) were installed in three replicated sets. Throughfall concentrations of ammonium and nitrate were significantly different for both species as well as soil solution concentrations of nitrate at all depths. Under pine, nitrate concentrations of the soil solution at 1m depth clearly exceeded the Belgian critical level for drinking water (50 mg.1-1). Under birch, this level was only sporadically exceeded. During the sampling period, the depositions of NH4 +-N and NO3 --N reached respectively 21.6 kg/ha and 6.3 kg/ha under birch and 81.3 and 15.2 kg/ha under Corsican pine. Nitrate-N leaching under silver birch amounted 25.4 kg/ha whereas 56.4 kg/ha was measured under Corsican pine. 相似文献
4.
Nitrogen Deposition and Nitrate Leaching at Forest Edges Exposed to High Ammonia Emissions in Southern Bavaria 总被引：1，自引：0，他引：1
The atmospheric deposition of air pollutants was studied by means of monitoring canopy throughfall at six forest stands. The investigation was carried out in Norway spruce (Picea abies L. Karst.) forests in Southern Bavaria with high ambient ammonia concentrations due to either adjacent intensive agriculture or poultry housing. Five monitoring plots transected the forest edges and forest interior from the edge, at 50, 150, about 400 m and about 800m to the interior. Additionally, nutrient concentration in soil solution was sampled with suction cups at each plot, and C/N ratio of the humus layer was also determined. The variation of ambient ammonia concentration between three of the six investigated sites was estimated using diffusive samplers. In order to compare the effects of atmospheric deposition on European beech (Fagus sylvatica L.) and Norway spruce additional monitoring plotswere installed under each of these species in a mixed beech and spruce stand. Bulk deposition and soil water samples were analysed for major ions (NO3 -, NH4 +, SO4 2-, Cl-, Na+, K+, Mg2+, Ca2+M).The results show a substantial increase of deposition towards the forest edges for all ions. This so called 'edge effect' continued in most cases until a distance from 50 to 150 m from edge. For both ambient ammonia concentrations and nitrogen deposition, it can be concluded that increased dry deposition is the main reason for the edge effect. Over 76% of the nitrogen ratios in throughfall deposition between the edge and 50 m distance into the spruce forest exceed 1.0. Except for potassium, beech generally showed lower ratios than spruce.Due to high nitrogen deposition the forest floor, C/N ratios were lower at stand edges when compared to their interior. In contrast to the increase of nitrogen deposition at the edge, nitrate export below the main rooting zone was lower at the edge. Nitrate export was generally lower under beech than spruce. Nitrogen budgets of some plots were negative, indicating a reduction of total ecosystem nitrogen stock.The results show that forest edges, especially in areas with high air pollution, receive much more atmospheric deposition than the interior parts of closed forest stands. As many deposition studies in forests were conducted at field stations in the central parts of forests the estimated deposition for the whole forest may be underestimated. This may be important to consider in geo-statistical studies and models aiming to estimate spatial critical deposition values, especially with an increasing fragmentation of the forest cover. 相似文献
5.
During one year, dry and wet deposition onto thirty forest stands is studied by sampling throughfall and bulk precipitation. Nine measurement sites are situated in Douglas fir (Pseudotsuga menziesii Mirb. Franco) stands, ten in Scotch pine (Pinus sylvestris L.) and eleven in Oak (Quercus robur L.) stands. Because the stands are situated in each other's proximity (i.e. within a radius of approximately 1.4 km) it is assumed that they experience an approximately equal air pollution load. For the acidifying compounds SO4 2?, NO3 ? and NH4 + spatial variability in wet deposition was small within the area studied. Dry deposition, as estimated by net throughfall, displayed a much higher spatial variability. Significant differences existed between tree species and growing seasons. Douglas fir mostly displayed the highest, Oak the lowest and Scotch pine intermediate values for net throughfall fluxes of acidifying compounds. The annual net throughfall fluxes for nitrogen compounds were significantly higher for the coniferous tree species than the broadleaved tree species. For SO4 2?, however, Oak showed a relatively high throughfall flux during the summer. By comparing the temporal pattern of net throughfall fluxes between the three tree species it was concluded that considerable canopy leaching occurred for SO4 2?, Mg+, PO4 3?, HCO3 ? and K+ in Oak stands during the sprouting of leaves in spring. From surface wash experiments in the laboratory it is concluded that canopy leaching of these ions may also be enhanced when Oak leaves are infected by Oak mildew, a fungal disease caused by the fungus Microshaera aliphilitoides. 相似文献
6.
G. Nakos 《Soil biology & biochemistry》1977,9(6):423-426
Laboratory incubation experiments with and without added urea or NH4NO3 were performed on humus from stands of beech (Fagus silvatica) grown on soils from limestone, schists, flysch and peridotites and on humus from oak (Quercus conferta) stands on soils from limestone and schists.Beech and oak humus from stands grown on soils from limestone and flysch showed considerable nitrification with a concurrent high mobilization rate of the nutrient elements Ca, Mg and K, especially in the presence of increasing urea concentrations, but no net humus N mineralization was observed. Beech humus from stands grown on soils from schists and peridotites showed no nitrification and increasing concentrations of added urea did not modify their inability to nitrify. Non-nitrifying types of humus showed considerable ammonification but their Ca, Mg and K mobilization rates were about one-tenth those observed in nitrifying humus and were inversely correlated with urea concentrations.Exchangeable Al3+ and extractable Mn were present in high concentrations in the underlying inorganic soils in all cases where nitrification was absent from the overlying humus but addition of 500 parts Al3+ and 1000 parts Mn/106 separately or in combination to a nitrifying humus failed to inhibit nitrification.An interpretation of these findings is attempted with reference to the possibility of absence of nitrification in climax vegetations and the preference of certain forest species for NH+4 or NO?3. 相似文献
7.
Jan Willem Erisman 《Water, air, and soil pollution》1993,71(1-2):81-99
In this study of acid depositions to Netherlands forests, measurements of acidifying components in throughfall were compared to estimates derived using the inferential method. Throughfall measurements were corrected for sea salt and other neutral salt deposition as well as for dry deposition of gases and aerosols to open sampler funnels. Corrected throughfall values for SO4, NH4 and total potential acid agreed better than uncorrected with inference estimates; corrections had almost no effect on NO3 values. Although corrected SO4 throughfall values are well correlated (0.82) with inference estimates, they are almost twice as high. For NO3 and NH4 correlation is poor; NO3 throughfall values are about half as high as inference estimates, NH4 inference estimates were higher or lower than corrected throughfall values. There was reasonable agreement between total potential acid deposition values from the two methods. 相似文献
8.
氮肥对镉在土壤-芥菜系统中迁移转化的影响 总被引：6，自引：0，他引：6
以芥菜为研究对象, 采用盆栽试验, 探讨了不同用量的5种氮肥对污染农田土壤中镉(Cd)在土壤–根系–地上部迁移累积的影响。结果表明: 5种氮肥均促进了芥菜根系对Cd的吸收, 且根系Cd含量随施氮量的增加而增加; 但根系吸收转运Cd的能力随氮肥施用量的增加呈先降后增的变化趋势。在≤200 mg(N)·kg-1(土)的施氮水平下, CO(NH2)2和Ca(NO3)2处理能显著降低芥菜地上部Cd含量, 降低幅度分别为13%~29%和24%~30%。在施氮量相同的条件下, NH4Cl和(NH4)2SO4显著降低了土壤pH, 增加了土壤DTPA-Cd含量, 促进了芥菜对Cd的吸收。本试验条件下, 200 mg(N)·kg-1(土)的CO(NH2)2在增加芥菜产量和降低芥菜地上部Cd含量等方面优于其他氮肥处理。 相似文献
9.
Masaaki Chiwa Tomotaka Uemura Kyoichi Otsuki Hiroshi Sakugawa 《Water, air, and soil pollution》2012,223(8):5473-5481
Nitrogenous air pollutants including nitrogen dioxide (NO2), nitric acid (HNO3), nitrate (NO 3 ? ), ammonia (NH3), ammonium (NH 4 + ), and nitrous acid (HONO) were characterized at an urban forested (UF) site in Hiroshima and at a suburban forested (SF) site in Fukuoka, western Japan, using an annular denuder system for 1?year from May 2006 to May 2007 to compare the concentrations and chemical species of atmospheric nitrogenous pollutants between UF and SF sites. The proximity of the urban area was reflected in higher NO2 concentrations at the UF site than at the SF site. NO2 was more oxidized at the SF site because it is farther from an urban area than the UF site, which was reflected in higher concentrations of HNO3 at the SF site than the UF site. HNO3 and acidic sulfate is neutralized by NH3, existing as ammonium nitrate (NH4NO3) and ammonium sulfate [(NH4)2SO4] at the UF site. At the SF site, acidic sulfate is neutralized by NH3, existing as (NH4)2SO4, but NH4NO3, had scarcely formed at the SF site. A much higher HONO concentration was observed at the UF site than at the SF site, especially in winter and spring at night, which could be explained by higher NO2 concentrations at the UF site because of its proximity to an urban area and stagnant meteorological conditions. Atmospheric HONO determination was critical in evaluating the possibility of damage to trees in UF areas. 相似文献
10.
Measurement of total acid deposition into spruce and beech forests in Northrhine-Westfalia During one year the deposition of H+, NH4+, Al3+, Fe3+ and the acidity (BNC8,2) in bulk precipitation and throughfall of spruce and beech stands was measured in Northrhine-Westfalia. It is shown that the calculation of acid deposition as the sum of the H+-equivalents of (H+ + NH4+ + Al3+ + Fe3+ + Mn2+) underestimates total deposition of acidity. A simple and useful alternative is the calculation of H+-equivalents from (BNC8,2 + 0.9 NH4+ + Mn2+). 相似文献
11.
Rainfall, stemflow, and throughfall were collected from 1996 to 1999 at two types of forest sites: (1) forests near the traffic roads and urban areas and (2) forests away from the urban areas at Mt. Gokurakuji, Hiroshima, western Japan in order to estimatethe effects of anthropogenic activities on atmospheric deposition. Rainfall deposition for major ions showed small differences between the sites. The NO3 - and SO4 2-concentrations in stemflow were higher at the urban-facing slope than at the mountain-facing slope. Throughfall deposition of NO3 - and SO4 2- was also higher at urban-facing slopes. Net throughfall (NTF) deposition (throughfall minus rainfall) of NO3 - and SO4 2- accounted for 77 and50% of the total throughfall deposition on urban-facing slopes, respectively, while it accounted for 44 and 23% on themountain-facing slopes, respectively. These results indicated a higher contribution from dry deposition on urban-facing slopes compared to mountain-facing slopes. Atmospheric N (NO3 - +NH4 +) deposition from throughfall was estimated to be around 17–26 kg N ha-1 yr-1 on urban-facing slopes, which was greater than the threshold of N deposition that could cause nitrogen leaching in Europe and the United States. The highload of atmospheric N deposition may be one of the factors bringing about the decline of pine forests on urban-facing slopesof Mt. Gokurakuji. 相似文献
12.
The atmospheric deposition of air pollutants at a forest edge was studied by means of monitoring canopy throughfall at the edge and at five different parallel lines in the forest behind the edge. The investigation was carried out at a pine forest on the Swedish west coast. Throughfall and bulk deposition samples were analyzed for volume, SO 4 2? , NO 3 ? , Cl?, NH 4 + , Na+, K+, Mg2+, Ca2+, and for pH. The results show that the throughfall flow at the edge was increased substantially for most ions. The ratios in throughfall flows between the edge and the line 50 m into the forest were for SO 4 2? , 1.5, NO 3 ? 2.9, NH 4 + 2.7, and Na+ 3.1. Since this effect is not only valid for forest edges but also for hillsides, hilltops, and edges between stands of different age, etc., there might be substantial areas which get much larger total deposition than the normally considered closed forest. 相似文献
13.
Tsuyoshi Yamada Shuichiro Yoshinaga Kazuhito Morisada Keizo Hirai 《Water, air, and soil pollution》2001,130(1-4):1115-1120
To assess the influence of acidic deposition on the forest ecosystem, it is necessary to evaluate the gross amount of acidic deposition. In this paper, we discuss the variation of sulfate (SO4 2?) and nitrate (NO3 ?) loads as well as related concentration from 1991 to 1999 in the Hinoki (Chamaecyparis obtusa) plantation in Kochi, southwest Japan. The annual precipitation varied significantly from 1,700 to 3,900 mm during the study period. The annual sulfate concentration of rainfall was about 15 µmol L?1, including about 80% non sea salt sulfate, while the annual nitrate concentration of rainfall was increased. The sulfate and nitrate concentrations of the through fall and the nitrate concentration of the stem flow were equal to or slightly higher than those of rainfall. However, the sulfate concentration of the stem flow was higher than that of rainfall, 21 to 55 µmol L?1. The sulfate and nitrate loads of rainfall were measured to be 27 to 46 and 14 to 43 mmol m?2 y?1, respectively. The sulfate and nitrate loads of the through fall were the same or slightly higher than those of rainfall. In contrast, the sulfate and nitrate loads of the stem flow were less than those of rainfall. Combined sulfate loads of the through fall and the stem flow reached about 1.5 times that of the sulfate load of rainfall. 相似文献
14.
Lee D. S. Dollard G. J. Derwent R. G. Pepler S. 《Water, air, and soil pollution》1999,113(1-4):175-202
Measurements of sulphur dioxide, ozone, ammonia, and soluble inorganic components of the atmospheric aerosol were made at a site in central southern England. Ammonia, ozone, and nitrate aerosol in winter were shown to exhibit significant diurnal variation. Ozone showed a typical diurnal variability, the magnitude of which was dependent upon wind speed. The lower night-time ozone concentrations at lower wind speeds were attributed to depletion inside nocturnal boundary layers by dry deposition. Ammonia, in contrast, showed a different behaviour, whereby the diurnal cycle was more pronounced at higher wind speeds, indicating that the cycle was unlikely to be the result of dry deposition at night. Ammonia concentrations showed a temperature dependence and the diurnal cycle of ammonia at this site appears to be the result of a temperature-driven emission signal. Of the total reduced nitrogen, NHx (NHx = NH3 + NH4 + aerosol), the phase was dominant and it is likely that more than 60% of the boundary layer NHx is in this phase. The loss term of ammonia by reaction with acid sulphate aerosol is likely to be greater than that by dry deposition on a UK scale. Nitrate aerosol showed a positive correlation with sodium aerosol, once the effect of mutual correlations with sulphate and ammonium were removed. This correlation effect, in combination with evidence of a marine-oriented directional dependence of nitrate aerosol, and negative non sea-salt chloride aerosol from the same ‘marine’ sector, shows the potential importance of the formation of sodium nitrate aerosol from reaction of dinitrogen pentoxide, or possibly nitric acid or nitrogen dioxide with sodium chloride aerosol. It is likely that this provides the major route of nitrate into rain, not the scavenging of nitric acid vapour. Aerosol sulphate, nitrate, and ammonium have been measured at Harwell since 1954. Sulphate aerosol increased up until 1976 and has declined subsequently. Nitrate aerosol has increased over the whole period, whereas ammonium aerosol follows a similar pattern to that of sulphate, but with an equivocal direction of trend after 1976. Sulphate, nitrate and ammonium aerosol all show a similar statistically significant seasonality. A historical inventory of ammonia emissions shows a clear correlation with ammonium aerosol. 相似文献
15.
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
16.
Michael A. Nicodemus Francis K. Salifu Douglass F. Jacobs 《Journal of plant nutrition》2013,36(11):1917-1936
ABSTRACT Black walnut (Juglans nigra L.) half-sib 1+0 seedlings were exponentially fertilized with ammonium (NH4 +) as ammonium sulfate [(NH4)2SO4], nitrate (NO3 ?) as sodium nitrate (NaNO3), or a mixed nitrogen (N) source as ammonium nitrate (NH4NO3) at the rate of 0, 800, or 1600 mg N plant?1 and grown for three months. One month following the final fertilization, N concentration, growth, and photosynthetic characteristics were assessed. Compared with unfertilized seedlings, N addition increased plant component N content, chlorophyll content, and photosynthetic gas exchange. Net photosynthesis ranged from 2.45 to 4.84 μmol m?2 s?1 for lower leaves but varied from 5.95 to 9.06 μmol m?2 s?1 for upper leaves. Plants responded more favorably to NH4NO3 than sole NH4 + or NO3 ? fertilizers. These results suggest that N fertilization can be used to promote net photosynthesis as well as increase N storage in black walnut seedlings. The NH4NO3 appears to be the preferred N source to promote black walnut growth and physiology. 相似文献
17.
The effects of enhanced (NH4)2SO4 (NS) deposition on Norway spruce (Picea abies [L.] Karst) fine root biomass, vitality and chemistry were investigated using root-free in-growth cores reproducing native organic and mineral soil horizons. The cores were covered and watered every 2 weeks with native throughfall or throughfall supplemented with NS to increase deposition by 75 kg ha-1 a-1 NH4 +-N (86 kg ha-1 a-1 SO42--S). The in-growth cores were sampled after 19 months and assessed for root biomass, necromass, length, tip number, tip vitality and fine root chemistry. Root biomass and fine root aluminium (Al) concentration were negatively correlated, but NS deposition had no effect on root growth or root tip vitality. NS deposition caused increased fine root nitrogen (N) concentrations in the organic horizon and increased Calcium (Ca) concentrations in the mineral horizon. Fine root biomass was higher in the organic horizon, where fine root Al and potassium (K) concentrations were lower and Ca concentrations higher than in the mineral horizon. Results highlighted the importance of soil stratification on fine root growth and chemical composition. 相似文献
18.
Effects of nitrogen fertilizer on the acidification of two typical acid soils in South China 总被引：4，自引：0，他引：4
Jian Zhou Fang Xia Xingmei Liu Yan He Jianming Xu Philip C. Brookes 《Journal of Soils and Sediments》2014,14(2):415-422
Purpose
A laboratory incubation under constant temperature and humidity was conducted to estimate the impacts of nitrogen (N) fertilizers on the acidification of two acid soils (Plinthudult and Paleudalfs) in south China.Materials and methods
The experiment had three treatments, i.e., control (CK), addition of urea (U), and addition of ammonium sulfate (AS). We measured soil pH, nitrate (NO3 ?), ammonium (NH4 +), exchangeable hydrogen ion (H+), and aluminum ion (Al3+) concentrations at various intervals during the 90 days of incubation. Soil buffering capacity (pHBC) was also measured at the end of the experiment.Results and discussion
The application of N fertilizers resulted in soil acidification. The U treatment caused greater acidification of the Plinthudult soil than the AS treatment, while there were no differences between U and AS treatments on the acidification of the Paleudalfs. At the end of the trial, the pHBC of Plinthudult in AS treatment was greater than that in CK and U treatments, which may be due to the buffering system of NH4 + and NH4OH. However, the pHBC of Paleudalfs was unchanged between treatments. The dynamics of exchangeable H+ and Al3+ corresponded to that of soil pH. Correlation analysis showed that both soil exchangeable H+ and soil exchangeable Al3+ were significantly related to soil pH.Conclusions
Application of urea and ammonium sulfate caused acidification in both soils and increased soil exchangeable Al3+ and H+ concentrations in the Paleudalfs. The application of urea increased exchangeable Al3+, and ammonium sulfate increased pHBC in the Plinthudult. 相似文献19.
Liu Na Zhang Li Meng Xiangxiang Neelam Ara Yang Jinghua 《Journal of plant nutrition》2014,37(11):1859-1872
Nitrogen is taken up by most plant species in the form of nitrate and ammonium. The objective of this study was to investigate the effect of different nitrogen forms on the growth of watermelon seedlings. Plants were grown in hydroponic culture with five nitrate (NO3?)/ammonium (NH4+) ratios (100/0, 75/25, 50/50, 25/75, 0/100). When the proportion of NH4+ was increased, the leaf number, leaf area, shoot height, net photosynthesis, biomass, and root growth were significantly decreased. Higher concentrations of nitrogen (N) and phosphorus (P) were observed when plants were supplied with mixed NO3? and NH4+ compared to NO3? or NH4+ alone, whereas the concentrations of potassium (K), calcium (Ca), and magnesium (Mg) were decreased with increasing NH4+. The microelements concentrations were generally increased with more NH4+ added. In addition, plants fed with higher NO3?/NH4+ ratios resulted in more minerals accumulation. 相似文献
20.
R. Lavrinenko 《Water, air, and soil pollution》1995,85(4):2149-2154
The paper presents results of a stoichiometric calculation of a nitrogen (N) compounds in precipitation of World Meteorological Organization's Global Atmosphere Watch (WMO GAW) stations. Long-term trends of ammonium sulphate ((NH4)2SO4) and ammonium nitrate (NH4NO3) contents i the North-West of Russia as well as in Byelorussia, Scandinavia, Western and Eastern Europe during the periods of 1958–1990 and 1972–1985 were investigated. A relatively, steady annual trend for the mean NH4NO3 concentrations was found typical of pure regions (5–15μeq* 1?1). The concentrations in industrial regions are from 4 to 5 times higher than the background close to natural. The analysis of the trend for (NH4)2SO4 content in precipitation shows a wide range of a variations of mean annual concentrations with an explicit tendency to their significant decrease in some European regions in the mid-eighties. Nitric acid (HNO3) has not been discovered in precipitation from the European WMO GAW stations while calculations based on the US data revealed its remarkable content and tendency to its increase. Nitric acid and ammonium sulphate are not contained in precipitation over ocean, ammonium nitrate is present in insignificant amounts. 相似文献