Developing optimal abatement strategies for the effects of sulphur and nitrogen deposition at European scale

Integrated Assessment Models were successfully used to provide input to the negotiations for the Oslo Protocol on Further Reductions of Sulphur Emissions, finalized within the United Nations Economic Commission for Europe Convention on Long-range Transboundary Air Pollution in Oslo in June 1994. The techniques developed within this framework will be extended now to the simultaneous analysis of sulphur and nitrogen deposition. In addition to acidification, atmospheric deposition of nitrogen contributes to eutrophication of certain ecosystems, through a nutrient effect, and originates from the long-range transport of emissions of both oxidised and reduced nitrogen (NO_x and NH₃). Modelling reductions in nitrogen deposition thus introduces a need to establish multi-pollutant multi-effect modelling techniques. This paper investigates the development of a model set up to examine reductions of these pollutants in an economically and environmentally efficient manner. The control of nitrogen deposition encompasses action across several economic sectors, particularly the power, transport and agricultural sectors. Combining sulphur and nitrogen deposition limits on a European scale will require a flexible modelling approach and the issues governing possible approaches are presented.     

Do UK crops and grassland require greater inputs of sulphur fertilizer in response to recent and forecast reductions in sulphur emissions and deposition?

UK emissions of sulphur dioxide decreased by 94% between 1970 and 2010 and are projected to decrease by another 50% by 2020 as coal fired power stations are decommissioned. We used the Community Multiscale Air Quality model to create maps of sulphur (S) deposition to assess the impact of these forecast decreases in S emissions on net S deposition to crops in England and Wales. Currently, average S deposition, net of S leaching, varies little between the UK regions, being greatest in Yorkshire and Humberside (Y&H), at ca. 5–6 kg/ha S, and least in Wales, at ca. 3–4 kg/ha S. However, even in Y&H S deposition is no more than 25% of S uptake by cereals and only ca. 10% of S uptake by oilseed rape (OSR). By 2020, net S deposition is predicted to decrease by between 30 and 60% and will be no more than 15% of S uptake by cereal crops and <10% of S uptake by OSR. We conclude that, with the exception of a few localities, net S deposition is currently making only a minor contribution to crop S requirements and this small contribution will continue to decline. We recommend S be applied at the rates currently advised, as either mineral fertilizer or livestock manures (or a combination of both), to all crops and grass grown on sandy soils or in areas of >375‐mm overwinter rainfall. The need for S fertilizer appears to be greatest for grass swards cut more than once.     

Energy use,emissions, and air pollution reduction strategies in Asia

In contrast to Europe and North America, air pollution in Asia is increasing rapidly, resulting in both local air quality problems and higher acidic depositions. In 1989, an east-west group of scientists initiated a multi-institutional research project on Acid Rain and Emissions Reduction in Asia, funded for the past two years by the World Bank and the Asian Development Bank. Phase I, covering 23 countries of Asia, focussed on the development of PC-based software called the Regional Air Pollution INformation and Simulation Model (RAINS-ASIA). A 94-region Regional Energy Scenario Generator was developed to create alternative energy/emission scenarios through the year 2020. A long-range atmospheric transport model was developed to calculate dispersion and deposition of sulfur, based upon emissions from area and large point sources, on a one-degree grid of Asia. The resulting impacts of acidic deposition on a variety of vegetation types were analyzed using the critical loads approach to test different emissions management strategies, including both energy conservation measures and sulfur abatement technologies.     

Meteorological variability of the wet and dry deposition of sulphur and nitrogen compounds over the baltic sea

The dry and wet deposition of N and S compounds to the Baltic Sea Basin were assessed using daily concentration measurements of air and precipitation concentrations, and actual meteorological data on precipitation, daily wind speed and wind direction, as well as the buoyant fluxes at the air- sea interface. The data cover the period 1980–86. Both concentrations and deposition levels show distinct south-north gradients and strong seasonal variability. Dry deposition is an important contribution in the case of S (25 to 80%) but is less significant for the N compounds (10 to 30%). The contribution of particles to dry deposition is negligible for S, equivalent to the gaseous contribution for oxidized N and about 10 to 20% for reduced nitrogen compounds. The obtained total annual deposition of about 1.4 to 1.8 g(S) m^?2 for the S compounds, and 1 g(N) m^?2 for the N compounds are comparable with, but on the upper side of, previous empirical and model estimates.     

Spatial variability of early season nitrogen availability indicators in corn

Abstract

The pre‐sidedress nitrate test (PSNT), a soil test used to refine sidedress fertilizer nitrogen (N) recommendations in corn (Zea mays L.), has shown great potential to reduce the excessive use of N fertilizer in corn production systems in the Northeast. The research reported in this paper evaluated the application of the PSNT to site‐specific management by investigating the spatial variability of several early season soil and plant indicators of N availability in a uniformly managed 16‐ha no‐till corn production field. The spatial variation in PSNT nitrate concentrations, total organic carbon (C) and N in the soil, and corn biomass yield and N content at the fifth leaf development stage were characterized from 189 samples taken during the 1994 growing season on a triangular grid with a 30 m minimum separation distance. There were no significant correlations found between any of the variables studied. All the variables studied were normally distributed with the exception of total organic C and biomass yield, both of which approximated a log‐normal distribution. Geostatistical analysis revealed significant spatial variation and spherical semivariogram models were developed for each variable. Results suggest that the average minimum grid size used in this study (30 m) may not have been adequate for an accurate estimation of nugget semivariance in total soil C and N and corn tissue N concentration. Plant indicators exhibited landscape features influencing biomass production and N uptake that were not revealed by the soil variables studied. These results illustrate the potential utility of integrating soil and plant productivity indicators to identify and address limitations to crop production using site‐specific management.     

基于BP神经网络插值的土壤全氮空间变异

大尺度土壤养分空间变异研究可以为土壤改良分区治理提供基础数据。寻求合适的取样数和插值方法是进行土壤养分空间变异研究的关键。以安徽省舒城县为例,共取得0～20cm土壤表层样品523个,土壤全氮的空间变异由BP神经网络插值方法在不同取样数条件下获得,通过与克里格插值法进行比较得出:样本数在100个时,神经网络插值的预测吻合度(G)比克里格插值高7.75%,均方根误差(RMSE)低0.1,总体精度优于克里格;样本数大于200时,神经网络插值和克里格插值精度基本相同,随着采样数量增加,两种方法的插值精度也在提高,并逐步趋于平稳。在大尺度土壤养分空间变异研究中,在小样本情况下,神经网络插值具有优势。     

Deposition of sulphur and nitrogen compounds in Croatia

Since precipitation is an efficient scavenger of pollutants, concentrations of major ions in precipitation reflect changes in chemistry of the atmosphere and in the subsequent exposure of various ecosystems to deposition. The National Atmospheric Precipitation Chemistry programme was initiated in 1978 and operated by Meteorological and Hydrological Service of Croatia to provide needed information on geographical patterns and temporal trends in precipitation chemistry in Croatia. To accomplish this, a network of about 20 stations, settled in different geographical regions, operates on a daily basis for 15 years now. Some monitoring stations are site- and study- specific; others are included in long-term, regional, or European monitoring networks (EMEP, GAW, MEDPOL, GEMS). The purpose of this work was to summarise existing data from the whole network for the period 1981–1992 and to compare data from measurements with EMEP model calculations of acid deposition. Results presented here show that annual average concentration and deposition values at remote sites agree reasonably well compared to modelled ones.     

Spatial variability of total soil carbon and nitrogen stocks for some reclaimed minesoils of southeastern Ohio

Reclamation of drastically disturbed minesoils and subsequent planting of trees and/or grasses can result in a rapid build‐up of carbon (C) in the soil. However, the amount of C sequestered in reclaimed minesoils may vary with the amount of time since reclamation. In this study, we assessed total carbon (TC) and total nitrogen (TN) concentrations for reclaimed minesoils located in northeastern Ohio and characterized by distinct reclamation age chronosequences. Reclaimed minesoils studied were R78G, reclaimed in 1978 and immediately seeded to grass; R82GT, reclaimed in 1982 and immediately seeded to grass and trees were planted 5 years later; and R87G, reclaimed in 1987 and immediately seeded to grass. An unmined site, UMG, was also included as a reference. Our objectives were to evaluate the variability with respect to mean and the spatial variability of pH, bulk density (ρ_b), TC and TN concentrations, and stocks in each reclaimed minesoil. Thirty soil samples were collected at each of the 0–15, 15–30, and 30–50 cm depth. The coefficient of variation (CV) for ρ_b was least, <15 per cent at each site and depth. For TN concentration and stock, CV was moderate, 15–35 per cent, in each field except the UMG where it was high, >35 per cent at 0–15, and 15–30 cm depths. For TC concentration and stocks, CV was high, >35 per cent, across all minesoils and generally increased with depth. The C/N ratio followed the same tend as TC and TN stocks and ranged from 40 per cent to 123 per cent across minesoils. Geostatistical analysis also showed an increase in sample variance with increasing amount of time since reclamation for most soil properties under investigation. Sample variance for TC concentration and stocks also increased with depth in reclaimed minesoils. However, no definite relationship emerged between amount of time since reclamation and the spatial dependence of TC and TN concentrations and stocks. Overall this study showed that reclamation of drastically disturbed minesoils increased the soil C concentration and stocks and reclamation by initially seeding to grasses followed by planting trees was the best management option for speedy accretion of soil C and soil quality enhancement. Copyright © 2007 John Wiley & Sons, Ltd.     

Implementing optimal sulphur abatement strategies in Europe

Acid rain causes greater environmental damage than would occur if countries act cooperatively. Based on new estimates of sulphur abatement cost functions and taking into consideration the political changes in Europe due to the dissaggregation of the USSR and the unification of Germany, this paper reviews and compares a number of alternative available economic instruments which, if adopted, may encourage implementation of sulphur abatement strategies.     

Spatial variability of nitrous oxide emissions in an unmanaged old‐growth beech forest

Nitrous oxide (N₂O) is a high‐impact greenhouse gas. Due to the scarcity of unmanaged forests in Central Europe, its long‐term natural background emission level is not entirely clear. We measured soil N₂O emissions in an unmanaged, old‐growth beech forest in the Hainich National Park, Germany, at 15 plots over a 1‐year period. The average annual measured N₂O flux rate was (0.49 ± 0.44) kg N ha^–1 y^–1. The N₂O emissions showed background‐emission patterns with two N₂O peaks. A correlation analysis shows that the distance between plots (up to 380 m) does not control flux correlations. Comparison of measured data with annual N₂O flux rates obtained from a standard model (Forest‐DNDC) without site‐specific recalibration reveals that the model overestimates the actual measured N₂O flux rates mainly in spring. Temporal variability of measured N₂O flux was better depicted by the model at plots with high soil organic C (SOC) content. Modeled N₂O flux rates were increased during freezing only when SOC was > 0.06 kg C kg^–1. The results indicate that the natural background of N₂O emissions may be lower than assumed by most approaches.     

环秦岭区域植烟土壤养分状况及其与烟叶品质的关系

  目的  研究云贵高原地区烟田土壤肥力评价的尺度效应,为精准施肥和不同层级土壤管理决策提供科学依据。  方法  贵州省六盘水市钟山、水城和盘州3个烟区分别采集了100、180和220个典型烟田的耕层（0 ~ 20 cm）土样,选取pH、有机质（OM）、碱解氮（AN）、有效磷（AP）、速效钾（AK）、交换性镁（Mg^{2 +} ）、水溶性氯（Cl⁻）、有效硼（B）和有效锌（Zn）9个肥力指标,分别基于市域（L,500个样点）尺度和烟区尺度（S,3个烟区各自样点）,利用主成分分析法确定了各肥力指标的权重,采用加权和法计算了烟田土壤综合肥力指标（Integrated Fertility Index,IFI）,采用简单克里格插值法形成了IFI空间分布图。  结果  ①土壤肥力指标受烟区、环境变量（海拔、年均气温和降雨量）、土壤类型和成土母质的影响。不同尺度计算出的土壤肥力指标权重之间存在明显差异,土壤肥力指标权重的相对差异随样点数量的增加而升高。②L和S尺度下,3个烟区IFI均值大于0.5。钟山和盘州L尺度的IFI显著高于S尺度（P < 0.05）,水城无显著差异。在IFI较高级别以下（< 0.6）范围内,3个烟区L尺度下的烟田数量均少于S尺度。③不同尺度下IFI的空间分布格局差异在不同烟区表现不同,相较于L尺度,S尺度下钟山东北部高值区（0.8 ~ 1）减少,西北部及东南部低值区（0 ~ 0.4）增加。水城和盘州分布格局较相似,水城S尺度下的图斑更为破碎,盘州S尺度下中值区（0.4 ~ 0.6）面积增加。④样点数量和密度影响着烟区L和S尺度下IFI的图斑数量差异,样点越多,越适合采用L尺度进行评价。  结论  云贵高原烟田土壤肥力评价过程存在明显的尺度效应,进行土壤肥力评价应考虑空间尺度,明确土壤肥力空间分异,服务于精准施肥和土壤改良。     

Efficacy of nitrogen oxides and hydrocarbons emissions controls in ozone attainment strategies as predicted by the Urban Airshed Model

The primary object of this paper is to provide a preliminary assessment of the effectiveness of NO _x vs Volatile Organic Compounds (VOC) emissions control options in improving O₃ air quality over the New York metropolitan area. To this end, we have applied the Urban Airshed Model (UAM) with the Carbon Bond IV (CB-IV) chemical mechanism utilizing the results of the Regional Oxidant Model (ROM) for the specification of initial/boundary concentrations and wind fields to the UAM. After examining the sensitivity of the predicted O₃ concentrations to initial/boundary conditions and biogenic emissions, we have evaluated the impact of various hypothetical emissions reduction options on O₃ air quality. Nested ROM/UAM simulations with an across-the-board reduction of 75% in the NO _x and VOC emissions from sources located within the New York metropolitan area indicate that the option of VOC-only control is superior to the NO _x -only control in reducing not only peak O₃ levels over the entire modeling domain but also population exposure to unhealthy O₃ levels. The model predicts that the combined 75% NO _x and VOC control option also reduces the peak O₃ concentration, but the improvement in O₃ air quality is less than that predicted for the 75% VOC-only control strategy. Additional modeling analyses with different mix and levels of emissions control and meteorological conditions are needed to confirm these preliminary findings.     

Critical deposition levels for nitrogen and sulphur on dutch forest ecosystems

Critical loads for N and S on Dutch forest ecosystems have been derived in relation to effects induced by eutrophication and acidification, such as changes in forest vegetation, nutrient imbalances, increased susceptibility to diseases, nitrate leaching, and Al toxicity. The criteria that have been used are N contents in needles, nitrate concentrations in groundwater (drinking water), and NH₄/K ratios, Ca/Al ratios, and Al concentrations in the soil solution. Assuming an equal contribution of N and S, all effects seem to be prevented at a total deposition level below 600 mol_c ha^?1 yr^?1 due to N uptake by stemwood and acid neutralization by base cation weathering. The most serious effects will probably be prevented at total deposition levels between 1500 and 2000 mol_c ha^?1 yr^?1. The current average deposition in the Netherlands is 4900 mol_c ha^?1 yr^?1.     

Agricultural nitrogen balance and water quality in the UK

Abstract. Nutrient balance calculations have been advocated as indicators of the risk of nitrate loss from agricultural land. To explore this concept, a spatially distributed UK agricultural nitrogen balance was derived using annually updated statistics. The mean UK N surplus for 1995 was 115 kg N ha^–1, made up of 51 kg ha^–1for arable land, 140 kg ha^–1 for agricultural grassland (excluding rough grazing) and an additional 14 kg N ha^–1for agricultural land from pig and poultry units. Nitrogen surpluses were greater in lowland grassland (mainly in western, wetter areas) than in arable areas. However nitrate concentrations in rivers were generally greater in arable areas. The relationship between N balance and nitrate leaching was very different for grassland and arable systems, and was also sensitive to climate, level of inputs and management practices. Nitrogen surplus was therefore weakly or even negatively correlated with river nitrate concentrations or loads. A positive correlation was found only where the comparison was restricted to grassland-dominated catchments. Nitrogen surplus calculations identified areas of very high livestock densities, which would be associated with increased risk of pollution. However their use in isolation as indicators of N leaching, or of progress towards mitigation, could be misleading especially if comparing areas differing in land use, climate or soil type.     

黄土高原水蚀风蚀交错带小流域土壤矿质氮空间变异性

为探明小流域土壤养分特性空间变异规律及其与环境因子的关系,以非均匀取样方法测定了黄土高原水蚀风蚀交错带小流域土壤表层（0～10、10～20、20～40 cm）的硝态氮和铵态氮,采用经典统计和地统计学方法分析了其空间分布特征及变异结构。结果表明：土地利用空间配置成混合利用结构拦截和减少径流侵蚀,形成了土壤矿质氮坡面斑块镶嵌格局。小流域内硝态氮和铵态氮呈中等的空间变异和自相关性,其变异性由土壤系统内部因素包括土壤质地、矿物、成土过程、地形特征和人类活动造成的外部因素包括施肥和耕作等共同控制。建立了土壤矿质氮多元回归预测模型,各回归模型的自变量不同,表明不同土层硝态氮和铵态氮的变异受不同环境因子控制。分析认为合理配置土地利用形成斑块状结构和增加养分投入可以改善研究区土壤质量。     

Spatial variability of surface peat properties and carbon emissions in a tropical peatland oil palm monoculture during a dry season

The expansion of oil palm monocultures into globally important Southeast Asian tropical peatlands has caused severe environmental damage. Despite much of the current focus of environmental impacts being directed at industrial scale plantations, over half of oil palm land-use cover in Southeast Asia is from smallholder plantations. We differentiated a first generation smallholder oil palm monoculture into 8 different sampling zones, and further divided the 8 sampling zones into oil palm root influenced (Proximal) and reduced root influence (Distal) areas, to assess how peat properties regulate in situ carbon dioxide (CO₂) and methane (CH₄) fluxes. We found that all the physico-chemical properties and nutrient concentrations except sulphur varied significantly among sampling zones. All physico-chemical properties except electrical conductivity, and all nutrient content except nitrogen and potassium varied significantly between Proximal and Distal areas. Mean CO₂ fluxes (ranged between 382 and 1191 mg m⁻² h⁻¹) varied significantly among sampling zones, and between Proximal and Distal areas, with notably high emissions in Dead Wood and Path zones, and consistently higher emissions in Proximal areas compared to Distal areas within almost all the zones. CH₄ fluxes (ranged between −32 and 243 µg m⁻² h⁻¹) did not significantly vary between Proximal and Distal areas, however significantly varied amongst sampling zones. CH₄ flux was notably high in Canal Edge and Understorey Ferns zones, and negative in Dead Wood zone. The results demonstrate the high heterogeneity of peat properties within oil palm monoculture, strengthening the need for intensive sampling to characterize a land use in the tropical peatlands.     

Spatial variability of selected carbon,nitrogen, and phosphorus parameters on acid and calcareous rangeland soils

Abstract

The magnitude of C, N, and P seasonal or long‐term variability in rangelands is difficult to assess because of intrinsic soil heterogeneity even in seemingly uniform areas. A need exists, therefore, to determine the minimum number of samples necessary so significant changes in C, N and P can be assessed where minimal confounding from soil types and vegetation exist. To achieve this end, laboratory and field studies of selected C, N, and P parameters were conducted to compare variability among six transect lines, radiating from a central point. Samples were taken along each transect line every 3 m to a distance of 15 m. Parameters measured were: total organic C (OC), total Kjeldahl N (TKN), NH₄‐N, NO₃‐N, NaHCO₃‐extractable inorganic P (NaHP), and total organic P (TPo). Two rangeland soils, a moderately acid Ascalon sandy loam, and a calcareous Haverson loam, were sampled at two depths to assess spatial differences. Results indicated that under the experimental conditions, OC, TKN and TPo would require at least 9, 6, and 10 replications, respectively, for 95% confidence limit for an allowable error of 10%. The smaller available mineral pools were much more variable than the total pools, and could require as many as 20 to 30 samples.     

Techniques and strategies for the reduction of ammonia emission from agriculture

Agricultural production systems are recognised as a major source of atmospheric ammonia (NH₃). When deposited, the NH₃ may contribute to eutrophication of oligotrophic ecosystems and to acidification. Techniques for the reduction of ammonia emission are mainly focused on reducing the NH₃ emitting area exposed to the air, reducing the NH₃ or ammonium (NH ₄ ⁺ ) concentration in solution or reducing the exchange of air above the emitting surface. In this paper we present the techniques and changes in farming practice which may reduce NH₃ emission. Due to interactions between different sources on a farm, reduction in NH₃ emission from individual parts of the livestock production system cannot simply be added to give the net reduction in emission from the total system. Thus a whole farm system approach is needed for devising control strategies for reducing NH₃ emission.     

Sensitivity of forest-floor mosses in boreal forests to nitrogen and sulphur deposition

The response of forest-floor mosses to deposition of nitrogen (N) and sulphur (S) was examined in field conditions in a 60-year-old Norway spruce (Picea abies Karst.) stand in southern Finland. The experimental plots received nitrogen (25 kg N ha^–1) and sulphur (30 kg S ha^–1) as ammonium sulphate once a year for 4 years.The dominant moss species on the site were Pleurozium schreberi (Mitt.) and Dicranum polysetum (Sw.). The biomass of the dominant moss species was decreased significantly by N and S deposition during the study period. Due to the addition of N and S, the biomass of Pleurozium schreberi was decreased by 60% and the biomass of Dicranum polysetum by 78%.