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1.
To evaluate ecosystem response to changing atmospheric deposition, element budgets were established over the period from 1973 to 1991 for a Norway Spruce (Picea abies (L.) Karst.) site. Budgets for Na+, Cl?, Ca2+, Mg2+, N, S and H+ were based on total deposition and seepage water fluxes. The deposition of Ca2+, Mg2+, particularly, of S and H+ decreased with time, while calculated N deposition remained constant at a high level. The decrease in Ca2+ deposition led to a reduction of Ca2+ fluxes with seepage water. The decrease of Mg2+ deposition did not have an effect on the output fluxes of Mg2+. The reversibility of soil and seepage water acidification by reduced S deposition was delayed by the release of previously accumulated soil SO 4 2? . The highest NO 3 ? fluxes were observed during the period of 1986 to 1988; NO 3 ? fluxes in general demonstrated a considerable annual and periodic variation. Total N accumulation in the ecosystem amounted to nearly 590 kg ha?1 yr?1 during the observation period. The major sink of N in the spruce site is the aggrading humus layer. The results emphasize the need for measurements over several years to make conclusions regarding the function of ecosystems in response to atmospheric deposition.  相似文献   

2.
A water quality survey has been performed on selected lakes and streams in southwest China. The purpose of the study was to measure the concentrations of acidic deposition and surface water chemistry in a region of severe air pollution, forest decline, and relatively sensitive geology to acidic deposition. We show that, although there are some high elevation lakes of low acid neutralizing capacity (ANC<150μeq L?1, acidification of lakes has not occurred in southwest China due to production of base cations in soil and dry deposition of dust that serves to neutralize acidic deposition. Water chemistry is buffered by high base cation concentrations (Ca2+, Mg2+, Na+, and K+ greater than 300μeq L?1, and pH values are always greater than 6.5.  相似文献   

3.
Precipitation, soils and soil water in a forested catchment in western Poland have been studied during the period 1992 – 96 (see also Vogt et al., this conf.). The S-deposition in the area during the study period was 2 – 3g S m?2 yr?1. In spite of decreasing anthropogenic emissions the S-deposition in the area did not change much during the study period mainly because the first years were exceptionally dry. However, the S-deposition was considerably higher during the previous decade. Based on soil water sulphate concentration, pH, acid neutralising capacity and the ratio of Al3+/(Ca2+ + Mg2+), there is apparently an amelioration in the conditions. A study using inter alia principal component analysis, indicates that this improvement is mainly due to more precipitation in the later part of the study period. Variations in precipitation amount have a pronounced effect on the soil-water chemistry, which makes it difficult to establish trends caused by changes in anthropogenic deposition. Long time series are therefore necessary to establish recovery due to reduced S-emissions.  相似文献   

4.
Rain water at two forested sites in Guangzhou (south China) show high concentrations of SO4 2?, NO3 ? and Ca2+ and display a remarkable seasonal variation, with acid rain being more important during the spring and summer than during the autumn and winter. The amount of acid rain represents about 95% of total precipitation. The sources of pollutants from which acid rain developed includes both locally derived and long-middle distance transferred atmosphere pollutants. The seasonal variation in precipitation chemistry was largely related to the increasing neutralizing capacity of base cations in rainwater in winter. Soil acidification is highlighted by high H+ and Al3+ concentrations in soil solutions. The variation in elemental concentration in soil solution was related to nitrification (H+, NH4 + and NO3 ?) and cation exchange reaction (H+, Al3+) in soil. The negative effect of soil acidification is partly dampened by substantial deposition of base cations (Ca2+, Mg2+ and K+) in this area.  相似文献   

5.
Bulk precipitation, throughfall, and soil water chemistry were studied from November 1983 to November 1984 at two ridge-top Appalachian deciduous forest sites to isolate causes of differing episodic stream acidification. The Fork Mountain site in West Virginia, which exhibited little episodic stream acidification, had lower deposition of H+ and SO inf4 sup2? and greater reductions of H+ in the water circulating through the forest canopy, forest floor, and mineral soil than the Peavine Hill site in Pennsylvania. Greater neutralization at Fork Mountain was linked to higher Ca and Mg carbonate contents in the sandstone and shale soil parent materials. Fork Mountain had greater amounts of exchangeable bases in the organic and mineral soil horizons. Neither site appeared to be accumulating SO inf4 sup2? in the soil, with Peavine Hill losing 56% more than was received in bulk deposition. Anions in soil leachate at Fork Mountain were largely balanced by Ca2+ and Mg2+, while at the Peavine Hill site A1" was the dominant cation. Results suggest that the typically-low carbonate content of sandstone and shale soil parent materials commonly found in Appalachian forests may be a key parameter controlling soil and stream acidification. Data for the one-year period also suggest bulk deposition of H+ was 63% greater at Peavine Hill than Fork Mountain.  相似文献   

6.
In SW China, acid deposition has been associated with forest damage such as defoliation and mortality due to serious soil acidification. These effects may be exacerbated by ongoing climate change. Understanding the integrated effects of climate change and acid deposition on soil chemistry of forest ecosystems is the key to alleviate forest damage and recover forest health. In particular, the long‐term development of integrated effects is unclear and, thus, prevents setting up cost‐effective controls of atmospheric deposition for improved forest‐health management. We employed the Nutrient Cycling Model (NuCM) to predict the changes of soil chemistry in a Masson pine (Pinus massoniana) forest at Tie‐Shan‐Ping (nearby Chongqing, the biggest city in SW China) under two scenarios of climate change and five scenarios of atmospheric deposition. Field‐monitoring data were used to calibrate and validate the NuCM model. It is shown that the maintaining of current acid deposition both in its quantity and composition would not enhance soil acidification although it would take further 20 years to reach a steady state with higher SO$ _4^{2-} $ and Ca2+ concentrations in soil solution. This simulated trend is in contradiction to the decrease of soil pH observed in field during last several decades. The possible reason of this may be the obviously elevated deposition of Ca2+, which may help to raise the pH of soil solution but occurred only in recent several years following the rapid increase of local construction industry. However, this enhanced Ca2+ input may not be maintained for long time. A decreased S input would lead to some positive effects on soil chemistry such as the increase of soil base saturation. A high N deposition has implicated the forest ecosystem to be saturated with N, and increased N input will further aggravate soil acidification and nutrient imbalances. The future climate change projected by IPCC, i.e., the increase of temperature and rainfall may slightly enhance the negative effect of increased N input. The integrated effect of climate change and N‐deposition increase may counteract the positive effects of decreased S input to a considerable degree. This supports the need for a rigorous implementation of new technology to decrease the emission of both S and N.  相似文献   

7.
Virgin fir trees have been dying on Mt. Oyama, which is located in the southwestern part of Kanto Plain, although the frequency of death seems to be reducing recently. We report elevational patterns of acid deposition in precipitation and throughfall under fir and cedar canopies and nitrogen saturation in the forest ecosystem on Mt. Oyama. The deposition fluxes of major inorganic ions in precipitation were nearly constant regardless of elevation except for hydrogen and ammonium ions, whereas the deposition fluxes of all major inorganic ions in throughfall among cedar increased. The 5-year average of annual nitrate deposition in precipitation from 1994 to 1998 showed 19.3 – 23.5 kg ha?1 yr?1 (annual inorganic total N deposition: 9.6 – 10.7 kgN ha?1 yr?1) at four sites ranging in elevation from 500 to 1252 m, whereas the deposition in both cedar and fir throughfall was over 6 times greater than that in precipitation. The average soil surface nitrate concentration in 1998 was 140 µg g?1 (the range: 21.1 – 429 µg g?1, n=80) and the 7-year average of nitrate concentration in stream water from 1992 to 1998 was 4.81 mg L?1 (the range: 2.38 – 20.6 mg L?1, n=317). Our results indicate that nitrogen saturation is occurring in the forest ecosystem because of high N deposition, probably via acid fog, on Mt. Oyama.  相似文献   

8.
A model for tree base cation uptake has been developed, dependent on the soil solution concentration of Al3+, divalent base cations such as Ca2+, Mg2+ and H+ ions, modelled with a Mikaelis-Menten type of expression based on the molar BC∶Al ratio, where BC is the sum of the divalent non-toxic base cations Ca2+ and Mg2+. The expression has the form of counteracting adsorption isoterms for BC and Al to the tree root. The effect of toxic levels of Hg and Pb is incorporated into the model, using root adsorption as the mechanism, and parameterization against experimental data. The expression is modified with an expression accounting for the effect of heavy metal toxicity and soil water content. The dependence of the uptake rate on soil moisture content can be shown to have the form of a Freundlich adsorption isotherm for water. The available data indicate an activation energy of 47 kJ?1 mol for base cation uptake to trees. Data from the literature was used to estimate the rate coefficients and ion selectivity coefficients for typical coniferous and decideous trees in Sweden and Germany. The model indicates that Ca2+ and Mg2+ is effective in mitigating Al3+ toxicity to tree roots, and that increasing the Ca2++Mg2+ soil solution concentration has a promotive effect on base cation uptake. Above a certain limit base cation uptake becomes independent of the solution base cation concentration. This is consistent with field observations, and may be developed to become a tool for assessing the impact of soil chemistry changes on forest growth rate and health status. Field data from the Swedish Forest Survey indicate that uptake depend on the square root of the soil solution base cation availability originating from weathering and deposition input, which is consistent with the BC∶Al expression of the model.  相似文献   

9.
A model deciduous forest soil (Schaffenaker loamy sand) was treated for 8 mo in the greenhouse in 25 cm reconstructed columns with simulated throughfall at pH 6.0 or 4.0, and SO4 2? levels of 12.8 or 24.8 mg L?1. Red oak seedlings grown in the microcosms showed no growth or foliar element response to the treatments. Sulfate loading had a greater impact on soil and leachate chemistry than pH. Higher available soil P in the A, horizon was associated with the pH 6.0 and high SO4 2?2 treatment combination. High SO4 2? loading also reduced exchangeable K+ in the A1?. Other soil horizons were unaffected by either treatment. Leachate chemistry was not significantly altered by througfall pH, but significantly greater export of Na+, Ca2+, Mg2+, Al3+, and NO3 ?, and lower SO4 2? loss, occurred with low SO4 ? input. Comparatively half as much NO3 ? loss was associated with high SO4 2? deposition. The high rate of NO3 ? leaching appeared responsible for greater equivalent mass loss of cations from the low SO4 2? treatment. Leachate removal of SO4 2? approximated input after 8 mo. The capacity of this soil to adsorb SO4 2? appeared relatively limited in the absence of normal element cycling. The sulfate component of simulated deciduous forest throughfall was shown to have a potentially greater impact than pH on ion leaching from forest soil. Additional consideration of the role of SO2? 4 deposition, in the context of throughfall rather than incident precipitation, is warranted in studies of acidic deposition effects on internal forest soil processes.  相似文献   

10.
During the period from 25 May 1991 to 30 May 1992 the atmospheric concentrations and depositions of oxides of sulfur were continuously measured in a suburban masson pine forest which is currently experiencing severe dieback, in Chongqing, China. The annual mean concentrations of SO2 and particulate SO4 2? were 220 μ g/m3 (77 ppbv) and 32 μ g/m3 respectively. The atmospheric concentrations of these sulfur compounds were high in late autumn and winter. The annual wet and dry depositions of sulfur to the forest as measured by throughfall and stemflow were 93.1 and 46.6 kgSha?1a?1 respectively. These depositions are among the highest level ever reported in the world. Althogh the cause of the dieback of the masson pine trees has not been unequivocally determined, it is probable that the direct impact of SO2 is more likely the cause than acid deposition.  相似文献   

11.
Seasonal fluctuation of concentration and flux of major inorganic ions in throughfall, stem flow, snowpack and soil solution was investigated at a natural cool temperature mixed forest in Hokkaido, northern Japan, in order to clarify the effect of snowmelt on the solute dynamics in the forest soil in snow-dominated region. Na+, Ca2+, Mg2+, Cl? and SO4 2? concentrations in soil solution showed a large fluctuation in the snowmelt period. The percentage of output of these elements from soil during the snowmelt period in the annual output was as follows. Mg2+: 51%, Na+ and Cl?: 59 and 60%, SO4 2?: 65%, Ca2+: 77%. Our results indicated that the snowmelt event was very important to quantify the annual elemental budgets in this region. Although the leaching of base cation from the soil was larger than that of inputs and accumulation into the vegetation, annual decreasing rate of acid neutralization capacity (ANC(s)) from the soil was mostly affected by the base cation accumulation into the vegetation, related that the base cations weathering accompanied with bicarbonate was slow due to the acidic and weathered soil in the studied site. It is suggested that the weakly acidic soil which has low ANC(s) in snow-dominated region will be relatively sensitive to the future increase of acidic deposition.  相似文献   

12.
The maximum critical load of sulfur and its exceedance by the sulfur deposition of 1994–1997 were mapped for South Korea with a spatial resolution of 11 × 14 km using the steady-state mass balance method. The Korean soil and geological maps were used as basis for the estimations of the critical alkalinity leaching and the weathering rate of base cations. The normalized difference vegetation index data obtained from the Advanced Very High Resolution Radiometer (AVHRR) together with the observed primary productivity of plants were used for the estimation of the critical uptake of base cations. Wet deposition of the non-sea-salt base cations was derived from measured base cation concentrations in precipitation, precipitation rate and air concentration of total suspended particulate while dry deposition of base cations was estimated using the inferential technique using scavenging ratios. The predominant ranges of base cation weathering, uptake and deposition were estimated to be of 200 – 600 eq ha?1 yr?1, 200 – 400 eq ha?1 yr?1 and 400 – 600 eq ha?1 yr?1, respectively. Critical alkalinity leaching was mainly in the range of 1000 – 2000 eq ha?1 yr?1 due to relatively high value of precipitation runoff. Exceedance of sulfur critical load was found at 40 % of the ecosystems considered mainly in the southeastern part of Korea, and about 60 % of Korea ecosystems were sustainable against sulfur acidity loadings.  相似文献   

13.
In Chongqing City, the rapid growth of the economy has accompanied an increase of sulfur dioxide emissions from coal combustion, bringing about an expansion of acid rain affected areas and acidification of soil. Recently, we reported that coal-biomass briquettes so-called bio-briquettes (BB), which are produced from pulverized raw coal, biomass, and a sulfur fixation agent (Ca (OH)2) under 3 to 5 tons cm?2 pressure, have high sulfur-fixation efficiency. The BB ash contains nutritive substances such as Ca and Mg, and has a large acid-neutralizing capacity. Thus, in order to improve the acid soil in the Chongqing area, we analyzed the chemical composition of the original acid soil and the ash-amended soil, and investigated their leaching characteristics under simulated acid rain (SAR). It was found that plants and crops in Chongqing area would be injured if the present acid rain continues. We carried out a SAR leaching experiment and studeid the potential toxic effects of leachate from soil containing added ash. The results indicated that the contents of most toxic elements, with the sole exception of chromium, were below the environment standard for irrigation water. Because the BB ash was highly alkaline, the leaching aluminum (Al) species would be hydroxide rather than free Al3+ ion.  相似文献   

14.
A total of 51 lakes in southern Quebec, Canada, were sampled between 1985 and 1993 to study changes in water chemistry following reductions in SO2 emissions (main precursor of acid precipitation). Time series analysis of precipitation chemistry revealed significant reductions in concentrations and deposition of SO4 2- from 1981 to 1992 in southern Quebec as well as reductions in concentrations and deposition of base cations (Ca2+, Mg2+), NO3 - and H+ in the western section of the study area. Reductions in atmospheric inputs of SO4 2- have resulted in decreased lakewater SO4 2- concentrations in the majority of the lakes in our study, although only a small fraction (9 of 37 lakes used in the temporal analysis) have improved significantly in terms of acidity status (pH, acid neutralizing capacity – ANC). The main response of the lakes to decreased SO4 2- is a decrease in base cations (Ca2++Mg2+), which was observed in 17 of 37 lakes. Seventeen lakes also showed significant increases in dissolved organic carbon (DOC) over the period of study. The resulting increases in organic acidity as well as the decrease in base cations could both play a role in delaying the recovery of our lakes.  相似文献   

15.
Year-to-year variation in acidic deposition within a mature sugar maple-dominated forest and in leaching of ions from the associated podzolic soil were examined at the Turkey Lakes Watershed between 1981 and 1986. Below-canopy inputs to the soil of SO4 2? and NO3 ? in throughfall averaged 640 and 295 eq. ha?1 yr?1; the corresponding ranges were 493–917 and 261–443 eq. ha?1 yr?1. The contribution of atmospheric deposition to SO4 2? NO3 ? and Ca2+ leaching decreased over the six years. During the study period, the mean annual volume-weighted NO3 ? concentration decreased in throughfall and forest-floor percolate and increased in the mineral-soil solution collected below the effective rooting zone. A substantial shift in the balance between SO4 2? and NO3 ?leaching from the mineral soil was observed; leaching of SO4 2?decreased and NO3 ? leaching increased with time. Leaching of Ca2+ and Mg2+ from the soil was increased as a result of excess NO3 ? production in the soil. The calculated output of NO3 ? from the soil, which averaged 1505 eq. ha?1 yr?1, considerably exceeded the atmospheric deposition of NO3 ?, whereas SO4 2? outputs were only moderately greater than inputs.  相似文献   

16.
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   

17.
ABSTRACT

Soil salinity is a major abiotic factor limiting crop production but an amendment with synthetic zeolite may mitigate effects of salinity stress on plants. The objective of the study was to determine the effects of zeolite on soil properties and growth of barley irrigated with diluted seawater. Barley was raised on a sand dune soil treated with calcium type zeolite at the rate of 1 and 5% and irrigated every alternate day with seawater diluted to electrical conductivity (EC) levels of 3 and 16 dS m?1. Irrigation with 16 dS m?1 saline water significantly suppressed plant height by 25%, leaf area by 44% and dry weight by 60%. However, a substantial increase in plant biomass of salt stressed barley was observed in zeolite-amended treatments. The application of zeolite also enhanced water and salt holding capacity of soil. Post-harvest soil analysis showed high concentrations of calcium (Ca2 +), magnesium (Mg2 +), sodium (Na+), and potassium (K+) due to saline water especially in the upper soil layer but concentrations were lower in soils treated with zeolite. Zeolite application at 5% increased Ca2 + concentration in salt stressed plants; concentrations of trace elements were also increased by 19% for iron (Fe2 +) and 10% for manganese (Mn2 +). The overall results indicated that soil amendment with zeolite could effectively ameliorate salinity stress and improve nutrient balance in a sandy soil.  相似文献   

18.
Prescribed fires are likely to re-emit atmospherically deposited mercury (Hg), and comparison of soil Hg storage in areas affected by prescribed fire to that in similar unburned areas may provide cross-validating estimates of atmospheric Hg deposition. Prescribed fires are common in the southeastern United States (US), a region of relatively high Hg deposition compared to the rest of the US, and are thus a potentially significant source of re-emitted atmospheric Hg. Accordingly, Hg was determined in soil layers of a prescribed fire experiment in a Florida longleaf pine forest. The Hg deficit in the annually burned forest floor relative to the forest floor unburned for 46 years (0.180 g ha?1?yr?1) agreed to within 5% of an independent estimate of Hg deposition for this site based on a regional monitoring network and computer model (0.171 g ha?1 yr?1). Consideration of other potential inputs and outputs of Hg suggested that atmospheric deposition was the primary input of Hg to the site. If extrapolated, these results suggest that prescribed fires in the southeastern US mainly re-emit atmospherically deposited Hg and that this re-emission is less than 1% of total US anthropogenic emissions. However, emissions at other sites may vary due to the possible presence of Hg in underlying geological strata and differences in fire regime and levels of atmospheric Hg deposition.  相似文献   

19.
Solute fluxes to the ground in open plots and under the forest canopy of different species were investigated in a number of long-term ecosystem studies in West Germany. From the canopy flux balance, rates of interception deposition and canopy/deposition interactions were assessed. Chemically, both open precipitation and throughfall are dilute solutions of H2SO4 and HNO3 and their salts. For the sites investigated, mean pH in bulk precipitation ranged from 4.1 to 4.6, and in throughfall from 3.4 to 4.7. The increase in acidity after canopy passage at most sites indicates considerable interception deposition of strong acids to the forest stands, exceeding the rate of H+ buffering in the canopy. Evidence for buffering processes can be directly deduced from the fact that on sites with high soil alkalinity and high foliage base status, throughfall pH is usually higher than precipitation pH. Furthermore, the same idea can be concluded from changes in solution composition after canopy passage: the H+/SO inf4 sup2? ratio is decreasing at most sites, while alkali earth cations from exchange processes occur in throughfall (Ca2+/SO inf4 sup2? ratio increases). Solution composition and element flux data are presented for each of the sites, and the regional, orographical and site specific (species composition, ecosystem state) differentiations are discussed. A method for the assessment of total deposition and of canopy interactions such as H+-buffering and cation leaching is described, and results of calculations are shown. From these calculations it is concluded that forest ecosystems in Germany receive mean H+ loads of ca. 1 to 4 keq H+ · ha?1 · a?1 from atmospheric deposition. Acidity deposition rates seem to be related to a few key factors such as regional characteristics and ecosystem characteristics.  相似文献   

20.
ABSTRACT

The feasibility of split (soil + foliar) applications of nitrogen (N) and phosphorus (P) and addition of a small quantity of sulfur (S) in the spray was tested for improving performance of rapeseed-mustard genotypes in a factorial randomized field experiment. Three genotypes (two erucic acid free, viz. Brassica napus L. cv. ‘Hyola PAC – 401’ and Brassica juncea L. Czern. and Coss. cv. ‘TERI (0E) M 21-Swarna’, and one best performing high yielding Brassica juncea L. cv. ‘Rohini’ as a check) were grown with four soil (B) plus foliar (F) applications of N, P, and S with uniform basal 30 kg potassium (K) ha? 1 (K30), viz. (i) the optimum soil-applied treatment supplemented with the spray of deionized water (BN90P30 + Fw) comprising control, (ii) BN70P30 + F N20, (iii) BN70P28 + FN20P2, and (iv) BN70P28 + FN20P2S2. Soil Plus foliar application of nutrients, particularly BN70P28 + FN20P2S2, improved their performance with respect to growth characteristics (shoot length plant? 1, leaf number plant? 1, area leaf? 1, leaf area index, fresh weight plant? 1, and dry weight plant? 1), physico-biochemical parameters (net photosynthetic rate, stomatal conductance, carboxylation efficiency, water use efficiency, carbonic anhydrase activity, leaf NPK content, and N use efficiency), yield attributes (pod number plant? 1, seed number pod? 1, 1000-seed weight, seed yield ha? 1, oil content, and oil yield ha? 1), and fatty acid composition in oil of these genotypes. The cultivar ‘Hyola PAC-401’ performed best particularly with BN70P28 + FN20P2S2. The improvement in the response of genotypes to the split application of nutrients may be attributed to their ready availability through foliar application.  相似文献   

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