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1.
Critical acid loads for Dutch forests were derived using a multi-layer steady-state model that includes canopy interactions, nutrient cycling, mineral weathering and N transformations. Values were calculated for combinations of 12 tree species and 23 soil types for a 10×10 km grid. Critical acid loads thus derived increased with decreasing soil depth. Nearly 90% of the values varied approximately between 1500 and 4000 molc ha?1 yr?1 at 10 cm soil depth and between 750 and 2000 molc ha?1 yr?1 at the bottom of the rootzone. Separate critical loads calculated for N and S at the bottom of the rootzone varied between approximately 300 and 1000 molc ha?1 yr?1 for N and between 150 and 1250 molc ha?1 yr?1 for S. Using deposition data of 1990, a median reduction of the deposition by approximately 75% was calculated to achieve the critical loads at the bottom of the rootzone. The overall uncertainty in this value was estimated to be about 10%, although it can be much larger for specific soil types such as clay and peat soils. For N a larger reduction deposition percentage was calculated than for S, especially for coniferous forests with a high present N input. 相似文献
2.
W. De Vries 《Water, air, and soil pollution》1993,68(3-4):399-434
Atmospheric deposition of N and S on terrestrial and aquatic ecosystems causes effects induced by eutrophication and acidification. Effects of eutrophication include forest damage, NO3 pollution of groundwater and vegetation changes in forests, heathlands and surface waters due to an excess of N. Effects of acidification include forest damage, groundwater pollution, and loss of fish populations due to Al mobilization. Critical loads (deposition levels) for N and S on terrestrial and aquatic ecosystems in the Netherlands related to these effects have been derived by empirical data and steady-state acidification models. Critical loads of N generally vary between 500 and 1500 mol c ha?1 yr?1 for forests, heathlands and surface waters and between 1500 and 3600 for phreatic groundwaters. Critical loads of total acid (S and N) vary between 300 to 500 mol c ha?1 yr?1 for phreatic groundwaters and surface waters and between 1100 to 1700 mol ha?1 yr?1 for forests. On the basis of the various critical loads a deposition target for total acid of 1400 mol c ha?1 yr?1 has been set in the Netherlands from which the N input should be less than 1000 mol c ha?1 yr?1. This level, to be reached in the year 2010, implies an emission reduction of 80–90% in SO2, NO x and NH3 in the Netherlands and of about 30% in neighboring countries compared to 1980 emissions. 相似文献
3.
W. De Vries 《Water, air, and soil pollution》1988,42(1-2):221-239
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 molc 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 molc ha?1 yr?1. The current average deposition in the Netherlands is 4900 molc ha?1 yr?1. 相似文献
4.
The steady-state model PROFILE was used to perform Monte Carlo simulations of critical loads of acidity and exceedances of forest soils for 128 sites in the province of Scania, southern Sweden. Statistical tests showed that 100 sites had normal distributed critical loads and exceedances and that the variance of these parameters was statistically equal for all sites. Pooled estimates of the standard deviation was 0.19 and 0.31 kmolc ha?1 yr?1 for the critical loads and exceedances, respectively. Introduction of uncertainties, expressed as confidence intervals, in the cumulative distribution function for critical loads showed that overlaps between percentiles were substantial. The 5%-ile was systematically equal to the 57%-ile using a 67% confidence interval and equal to the 87%-ile when a 95% confidence level was chosen. The overlaps of percentiles cause a reduction of acidic deposition according to the mean value of the 5%-ile to protect only 68% of the ecosystem area with an 84% probability and not a guaranteed protection of 95% as if uncertainties did not exist. Thus, uncertainties make it possible to advocate reductions to levels of deposition below the 5%-tile of critical loads. 相似文献
5.
Hans J. M. van Grinsven Bart G. Wesselink Manfred Schroeder Nico van Breemen 《植物养料与土壤学杂志》1991,154(3):181-188
Solute budgets and nitrogen use were quantified in two 400 m2 forested lysimeters in St. Arnold, Nordrhein-Westfalen. The lysimeters are covered by a mixture of oak-beech and Weymouth pine, respectively. The average bulk deposition between May 1985 and May 1987 of NH, SO and NO3 was 1.1, 1.7, and 0.4 kmolc ha?1 yr?1 in the deciduous stand and 2.1, 2.1, and 0.8 kmolc ha?1 yr?1 in the coniferous stand. The input of N is almost completely retained in the deciduous stand. In the coniferous stand about 30% of this N-input is leached as NO3. Due to N-transformations, total proton turnover is 4.4 kmolc ha?1 yr?1 in the coniferous stand and only 2.5 kmolc ha?1 yr?1 in the deciduous stand. Ca-mobilization is the major acid buffering process in both lysimeters. Only the deciduous stand was limed in 1980 (90 kmolc/ha). Mobilization of Al is only relevant down to a soil depth of 30 cm. Below a 30 cm depth, Al is immobilized. The amounts of exchangeable and silicate-bound Ca in the soil underlying the coniferous stand are very small, but no evidence was found for explanation of the observed high Ca-mobilization by artificial Ca-sources. 相似文献
6.
7.
Lei Duan Shaodong Xie Zhongping Zhou Xuemei Ye Jiming Hao 《Water, air, and soil pollution》2001,130(1-4):1199-1204
Critical loads of nutrient and acidifying nitrogen, as well as of sulphur and acidity, were derived for various ecosystems in China using the steady state mass balance (SSMB) equations. The weathering rates of major soils necessary for applying SSMB were calculated through the PROFILE model on the basis of mineralogical data from experimental analysis. The growth uptakes of nitrogen and base cations were also derived by multiplying the annual increases in biomass with the element contents of the vegetation. Using a geographical information system (GIS), 1°(latitude)×1°(longitude) critical load maps of China with different percentiles were compiled. Results indicate that low critical loads of S (< 0.5 keq·ha?1·a?1) occurred predominately in southwest and northeast China, and the critical loads of southeast China were intermediate and in the range of 0.5~1.0 keq·ha?1·a?1. In addition, the critical loads of N were very low for desert ecosystems in northwest China and high for agricultural ecosystems in east China. Among the ecosystems with intermediate critical load of N, coniferous forests may be more sensitive to N deposition than broad-leaf forests and temperate steppes. 相似文献
8.
Critical loads for nitrogen deposition on forest ecosystems 总被引:2,自引:0,他引:2
E. - D. Schulze W. De Vries M. Hauhs K. Rosén L. Rasmussen C. -O. Tamm J. Nilsson 《Water, air, and soil pollution》1989,48(3-4):451-456
Critical loads for N deposition are derived from an ecosystem's anion and cation balance assuming that the processes determining ecosystem stability are soil acidification and nitrate leaching. Depending on the deposition of S, the parent soil material, and the site quality critical N deposition rates will range between 20 to 200 mmol m?2 yr?1 (3 to 14 kg ha?1 yr?1) on silicate soils and reach 20 to 390 mmol m?2 yr?1 (3 to 48 kg ha?1) on calcareous soils. 相似文献
9.
Calculating critical loads of acid deposition with PROFILE — A steady-state soil chemistry model 总被引:1,自引:0,他引:1
A steady state soil chemistry model was used to calculate the critical load of acidity for forest soils and surface waters at Lake GÄrdsjön in S.W. Sweden. The critical load of all acid precursors (potential acidity) for the forest soil is 1.64 kmolc ha?1 yr?1, and 1.225 kmolc ha?1 yr?1 for surface waters. For the most sensitive receptor, the critical load is exceeded by 1.0 kmolc ha?1 yr?1, and a 80% reduction in S deposition is required, if N deposition remains unchanged. The critical load is largely affected by the present immobilization of N in the terrestrial ecosystem which is higher than the base cation uptake. The model, PROFILE, is based on mass balance calculations for the different soil layers. From measurable soil properties, PROFILE reproduces the present stream water composition as well as present soil solution chemistry. The model calculates the weathering rate from independent geophysical properties such as soil texture and mineral composition. 相似文献
10.
Rock Ouimet Paul A. Arp Shaun A. Watmough Julian Aherne Ian DeMerchant 《Water, air, and soil pollution》2006,172(1-4):57-66
Critical loads of acidity were estimated for upland forests in Eastern Canada using the steady-state Simple Mass Balance (SMB) Model. A consistent methodology was applied to the entire region, although critical loads were estimated separately for the Atlantic provinces (New Brunswick, Nova Scotia, Prince Edward Island and Newfoundland), Quebec and Ontario using different data sources. In this project, critical load estimates and steady-state exceedance values did not include the effect of forest fire and forest harvesting, which could have a considerable impact on critical loads in Eastern Canada. The observed soil pH – base saturation relationship for forest soils indicated that the constants used into the calculation of alkalinity leaching should be set to 10 (M/M) for the molar Bc/Al ratio in soil leachate and 109 (mol L?1)2 for the gibbsite dissolution constant. The area-weighted median critical load for each province varied between 519 (Quebec) and 2063 eq ha?1 y?1 (Prince Edward Island), with a median critical load value for Eastern Canada of 559 eq ha?1 y?1. It is estimated that approximately 52% of the mapped area is exceeded in terms of acidity according to the 1994–1998 average total (wet + dry) atmospheric deposition. Greatest exceedances occurred in Ontario and Quebec and in the south of Nova Scotia, due to low critical loads and high loads of acid deposition. 相似文献
11.
The applicability of critical load (CL) methodology for thedetermination of natural terrestrial ecosystem sensitivity to sulfur acidity loading in South Korea was investigated.The sulfur critical load values, CLmaxS, were calculated for the terrestrial ecosystems of South Korea using the steady-state mass balance approach. The corresponding mapping of CLmaxS was carried out on the scale of 11 × 14 km grid cells. The estimated CLmaxS values depend on the low rate of soil chemical base cation weathering (mainly, 200–400 eq ha-1 yr-1), relativelylow base cation depositions (mainly less than 450 eq ha-1 yr-1) and base cation uptake (predominantly 300–400 eq ha-1 yr-1), and in significant degree on high valuesof acid neutralizing capacity. The latter in turn is connectedwith relatively high values of surface runoff (maximum 9000 m3 ha-1 yr-1). It has been shown that about 75%of CLmaxS values are in the range of 1000–2000 eq ha-1 yr-1 and about 15% are relatively low values(<1000 eq ha-1 yr-1). About 10% of ecosystems haveCL values more than 2000 eq ha-1 yr-1. The sensitiveand very sensitive ecosystems occur in the southeastern part of the country whereas the sustainable ecosystems are wide spread in the northeastern part. In accordance with sulfur critical load and sulfur deposition patterns, in 1994–1997 the CLmaxS values were found to be exceeded in about 40% of total number of Korean ecosystems, mainly in the southeastern part of the country. The average yearly valuesof exceedances varied from 176 to 3100 eq ha-1 yr-1. 相似文献
12.
Vegetation Type Affects the Relationship Between Soil Carbon to Nitrogen Ratio and Nitrogen Leaching
E. C. Rowe C. D. Evans B. A. Emmett B. Reynolds R. C. Helliwell M. C. Coull C. J. Curtis 《Water, air, and soil pollution》2006,177(1-4):335-347
Nitrate leaching occurs when the soil's nitrogen immobilisation and plant uptake capacity has been saturated. Several widely-used models of nitrogen saturation incorporate a breakthrough function in which N begins to be leached at C/N values below an upper threshold, and is completely leached at C/N values below a lower threshold. In a survey of deciduous and coniferous woodland, acid grassland and heathland sites for which both C/N and nitrate flux measurements were available, deciduous woodland and acid grassland typically had lower C/N ratios, and began leaching nitrate at a lower C/N ratio, than coniferous woodland and heathland. Least-square fits of nitrate breakthrough functions gave upper thresholds (no nitrate leaching) of 27 mol C mol?1 N for deciduous woodland and acid grassland and 50 mol C mol?1 N for coniferous woodland and heathland. Upper thresholds were similar, at 24 and 51 mol C mol?1 N, respectively, for total inorganic N (NH4 + NO3) leaching flux as a proportion of total inorganic N influx. In conifer plantations, stand maturity had a large effect, suggesting that a breakthrough function is unsuitable for modelling systems that are in disequilibrium. However, there was sufficient evidence to suggest that using different breakthrough C/N thresholds for different groups of vegetation would improve predictions of N saturation and leaching at both plot and catchment scales. The difference may be related to the reactivity of soil carbon; soils with a large proportion of recalcitrant carbon are likely to begin leaching nitrate at a higher C/N value than soils with more labile carbon. 相似文献
13.
J. -P. Hettelingh M. Posch P. A. M. De Smet R. J. Downing 《Water, air, and soil pollution》1995,85(4):2381-2388
Critical loads have been used in the revision of the Sulphur Protocol of the Convention on Long Range Transboundary Air Pollution (LRTAP) of the United Nations Economic Commission for Europe (UN/ECE). Critical loads, i.e. maximum allowable depositions which do not increase the probability of damage to forest soils and surface waters, have been computed and mapped for Europe by means of the Steady-state Mass Balance Method, using national data and, if national data were unavailable, using a European database. Results show that areas with low critical loads are located mostly in northern and central Europe. The reduction of the excess of sulfur (S) deposition over critical loads was a starting point for negotiations leading to the Oslo Protocol on Further Reduction of Sulphur Emissions (the “Second Sulphur Protocol”). The new protocol protects about 81%, 86% and 90% of the ecosystems' area in 2000, 2005 and 2010, respectively. In addition, the total European area in which sulphur deposition exceeds critical loads by more than 500 eq ha?1 yr?1 will be reduced from about 19% in 1980 to practically zero in 2010. Besides these results, a methodology is presented which allows the combined assessment of the acidifying effects of S and N as well as the eutrophying effects of N deposition on ecosystems (so-called critical load functions and the protection isolines derived from them). This methodology is well suited to integrate ecosystem sensitivities into future negotiations on the reductions of nitrogen (N) compounds, taking into account present or anticipated S emissions. 相似文献
14.
The sink of CO2 and the C budget of forest biomes of the Former Soviet Union (FSU) were assessed with two distinct methods: (1) ecosystem/ecoregional, and (2) forest statistical data. The ecosystem/ecoregional method was based on the integration of ecoregions (defined with a GIS analysis of several maps) with soil/vegetation C data bases. The forest statistical approach was based on data on growing stock, annual increment of timber, and FSU yield tables. Applying the ecosystem/ecoregional method, the area of forest biomes in the FSU was estimated at 1426.1 Mha (106 ha); forest ecosystems comprised 799.9 Mha, non-forest ecosystems and arable land comprised 506.1 and 119.9 Mha, respectively. The FSU forested area was 28% of the global area of closed forests. Forest phytomass (i.e., live plant mass), mortmass (i.e., coarse woody debris), total forest plant mass, and net increment in vegetation (NIV) were estimated at 57.9 t C ha?1, 15.5 t C ha?1, 73.4 t C ha?1, and 1.0 t C ha?1 yr?1, respectively. The 799.9 Mha area of forest ecosystems calculated in the ecosystem/ecoregional method was close to the 814.2 Mha reported in the FSU forest statistical data. Based on forest statistical data forest phytomass was estimated at 62.7 t C ha?1, mortmass at 37.6 t C ha?1; thus the total forest plant mass C pool was 100.3 t C ha?1. The NIV was estimated at 1.1 t C ha?1 yr?1. These estimates compared well with the estimates for phytomass, total forest plant mass, and NIV obtained from the ecosystem/ecoregional method. Mortmass estimated from the forest statistical data method exceeded the estimate based on the ecosystem/ecoregional method by a factor of 2.4. The ecosystem/ecoregional method allowed the estimation of litter, soil organic matter, NPP (net primary productivity), foliage formation, total and stable soil organic matter accumulation, and peat accumulation (13.9 t C ha?1, 125.0 t C ha?1, 3.1 t C ha?1 yr?1, 1.4 t C ha?1 yr?1, 0.11, and 0.056 t C ha?1 yr?1, respectively). Based on an average value of NEP (net ecosystem productivity) from the two methods, and following a consideration of anthropogenic influences, FSU forests were estimated to be a net sink of approximately 0.5 Gt C yr?1 of atmospheric C. 相似文献
15.
Hermann Hafner Joachim Bley Andr Bationo Peter Martin Horst Marschner 《植物养料与土壤学杂志》1993,156(2):169-176
On acid sandy soils of Niger (West Africa) fertilizer N recovery by pearl millet (Pennisetum glaucum L.) is often more than 100 per cent in years with normal or above average rainfall. Biological nitrogen fixation (BNF) by N2-fixing bacteria may contribute to the N supply in pearl millet cropping systems. For a long-term field experiment comprising treatments with and without mineral fertilizer (F) and with and without crop residue application (CR) a N balance sheet was calculated over a period of six years (1983-1988). After six years of successive millet cropping total N uptake (36-77 kg N ha?1 yr?1) was distinctly higher than the amount of fertilizer N applied (30 kg N ha?1 yr?1). The atmospheric input of NH4-N and NO3-N in the rainwater was about 2 kg N ha?1 yr?1, 70 % in the form of NH4-N. Gaseous NH3 losses from urea (broadcast, incorporated) were estimated from other experiments to amount to 36 % of the fertilizer N applied. Nitrogen losses by leaching (15 to > 25 kg N ha?1 yr?1) were dependent on the treatment and on the quantity and distribution of single rainfall events (>50 mm). Decline in total soil N content (0-60 cm) ranged from 15 to 48 kg N ha?1 yr?1. The long-term N balance (1983-1988) indicated an annual net gain between 6 (+CR-F) and 13 (+CR+F) kg N ha?1 yr?1. For the control (-CR-F) the long-term N balance was negative (10 kg N ha?1 yr?1). In the treatment with crop residues only, the N balance was mainly determined by leaching losses, whereas in treatments with mineral fertilizer application the N balance depended primarily on N removal by the millet crop. The annual net gain in the N balance increased from 7 kg ha?1 with mineral fertilizer to 13 kg ha?1 in the combination mineral fertilizer plus crop residues. In both the rhizosphere and the bulk soil (0-15 cm), between 9 and 45% of the total bacterial population were N2-fixing (diazotrophic) bacteria. The increased N gain upon crop residue application was positively correlated with an increase in the number of diazotrophic and total bacteria. The data on bacterial numbers suggest that the gain of N in the longterm N balance is most likely due to an N input by biological nitrogen fixation. In addition, evidence exists from related studies that the proliferation of diazotrophs and total bacteria in the rhizosphere due to crop residue application stimulated root growth of pearl millet, and thus improved the phosphorus (P) acquisition in the P deficient soil. 相似文献
16.
Cappellato Rosanna Peters Norman E. Meyers Tilden P. 《Water, air, and soil pollution》1998,103(1-4):151-171
Atmospheric deposition and above-ground cycling of sulfur (S) were evaluated in adjacent deciduous and coniferous forests at the Panola Mountain Research Watershed (PMRW), Georgia, U.S.A. Total atmospheric S deposition (wet plus dry) was 12.9 and 12.7 kg ha-1 yr-1 for the deciduous and coniferous forests, respectively, from October 1987 through November 1989. Dry deposition contributes more than 40% to the total atmospheric S deposition, and SO2 is the major source (~55%) of total dry S deposition. Dry deposition to these canopies is similar to regional estimates suggesting that 60-km proximity to emission sources does not noticeably impact dry deposition at PMRW. Below-canopy S fluxes (throughfall plus stemflow) in each forest are 37% higher annually in the deciduous forest than in the coniferous forest. An excess in below-canopy S flux in the deciduous forest is attributed to leaching and higher dry deposition than in the coniferous forest. Total S deposition to the forest floor by throughfall, stemflow and litterfall was 2.4 and 2.8 times higher in the deciduous and coniferous forests, respectively, than annual S growth requirement for foliage and wood. Although S deposition exceeds growth requirement, more than 95% of the total atmospheric S deposition was retained by the watershed in 1988 and 1989. The S retention at PMRW is primarily due to SO4 2- adsorption by iron oxides and hydroxides in watershed soils. The S content in white oak and loblolly pine boles have increased more than 200% in the last 20 yr, possibly reflecting increases in emissions. 相似文献
17.
Bischoff Joseph M. Bukaveckas Paul Mitchell Myron J. Hurd T. 《Water, air, and soil pollution》2001,128(1-2):97-114
Pools and fluxes of N in wetland vegetation and soils were compared with an adjacent upland site to assess the relative importance of wetland versus upland landscapes in watershedN-retention in the Adirondack Mountains of New York (U.S.A.).The majority of N storage occurred in forest soils and wetlandpeat deposits (96 and 99% of total N in upland forests andwetlands, respectively). Annual N-uptake (49 kg N ha-1yr-1) was greater for wetland vegetation than that ofupland vegetation (30 kg N ha-1 yr-1). In the wetlandthe supply of N from mineralization (36 kg N ha-1yr-1) was less than N-uptake; in contrast, upland Nmineralization (76 kg N ha-1 yr-1) exceeded Nvegetation uptake. Annual N-storage in peat was small due to low peat accretion rates. Wetlands acted as a sink for N andstored a disproportionally high fraction (15%) of catchment Nin relation to their relatively small surface area (~4%)within the catchment. 相似文献
18.
Noreen Poor Curtis Pollman Paul Tate Mubeena Begum Melissa Evans Scott Campbell 《Water, air, and soil pollution》2006,170(1-4):267-283
We estimated the total inorganic fluxes of nitrogen (N), sulfur (S), chloride (Cl?, sodium (Na+, calcium (Ca2+, magnesium (Mg2+, potassium (K+ and hydronium (H+. The resistance deposition algorithm that is programmed as part of the CALMET/CALPUFF modeling system was used to generate spatially-distributed deposition velocities, which were then combined with measurements of urban and rural concentrations of gas and particle species to obtain dry deposition rates. Wet deposition rates for each species were determined from rainfall concentrations and amounts available from the National Acid Deposition Program (NADP) monitoring network databases. The estimated total inorganic nitrogen deposition to the Tampa Bay watershed (excluding Tampa Bay) was 17 kg-N ha?1 yr?1 or 9,700 metric tons yr?1, and the ratio of dry to wet deposition rates was ~2.3 for inorganic nitrogen. The largest contributors to the total N flux were ammonia (NH3 and nitrogen oxides (NO x at 4.6 kg-N ha?1 yr?1 and 5.1 kg-N ha?1 yr?1, respectively. Averaged wet deposition rates were 2.3 and 2.7 kg-N ha?1 yr?1 for NH4 + and NO3 ?, respectively. 相似文献
19.
One of the major threats to the structure and the functioning of natural and semi-natural ecosystems is the recent increase in air-borne nitrogen pollution (NHy and NOx). Ecological effects of increased N supply are reviewed with respect to changes in vegetation and fauna in terrestrial and aquatic natural and semi-natural ecosystems. Observed and validated changes using data of field surveys, experimental studies or, of dynamic ecosystem models (the empirical approach), are used as an indication for the impacts of N deposition. Based upon these data N critical loads are set with an indication of the reliability. Critical loads are given within a range per ecosystem, because of spatial differences in ecosystems. The following groups of ecosystems have been treated: softwater lakes, wetlands & bogs, species-rich grasslands, heathlands and forests. In this paper the effects of N deposition on softwater lakes have been discussed in detail and a summary of the N critical loads for all groups of ecosystems is presented. The nitrogen critical load for the most sensitive ecosystems (softwater lakes, ombrotrophic bogs) is between 5–10 kg N ha–1 yr–1, whereas a more average value for the range of studied ecosystems is 15–20 kg N ha–1 yr–1. Finally, major gaps in knowledge with respect to N critical loads are identified. 相似文献
20.
The essential parameters needed for the calculation of critical load of sulfur, CL(S), are base cation weathering rate, base cation uptake, acid neutralizing capacity leaching and base cation deposition. These parameters are estimated and mapped for the most area of terrestrial ecosystems of Thailand using data of national data soil survey. The values of CL(S) range from <200 to 2,225 eq.ha?1yr?1 and about 70% of terrestrial ecosystems are characterized by low values (<200 eq.ha?yr?1). These CL values reflect the sensitivity of Thai ecosystems to sulfur deposition. 相似文献