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1.
The contributions of cation exchange and mineral weathering to the neutralization of acidity in the Jingahata watershed in central Japan were estimated through a laboratory weathering experiment and runoff chemistry measurements. The laboratory experiment was conducted in a stirred-flow reactor for a whole soil sample collected from the C horizon in the watershed. The concentration ratios of base cations (Ca2+, Mg2+, K+ and Na+) to Si (BC/Si) released during the steady-state stage of the laboratory experiment were in good agreement with the ratios of the net flux of base cations to the flux of Si in the streamwater (BC N ET/Si L).This result suggests that the acidity in the watershed is neutralized primarily by mineral weathering without causing a net loss of base cations from exchange sites. The alkalinity/acidity balance estimated for the watershed shows that the total weathering rate of base cations is approximately 3.26 keq ha?1 yr?1. Weathering of plagioclase (An41) contributes 83% of the total weathering rate. The dominant acidity source is CO2 released within the soil horizons, accounting for roughly 85% of the total acidity flux (3.20 keq ha?1 yr?1). This high internal production of acidity suppresses the relative importance of atmospheric acidity inputs (0.3 keq ha?1 yr?1).  相似文献   

2.
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   

3.
Deposition of non-seasalt base cations (Ca2+ + Mg2++ K+) in South Korea was mapped for 1994 to 1997 on a 11 × 14 km grid using the so-called inferential modeling technique. It is found that the annual mean wet deposition of non-seasalt base cations is about 290 eq ha-1 yr-1 with a maximum of 470 eq ha-1 yr-1 and a minimum of 120 eq ha-1 yr-1 while the annual mean dry deposition is about 130 eq ha-1 yr-1 with a maximum of 240 eq ha-1 yr-1 and a minimum 70 eq ha-1 yr-1. Theannual mean total deposition of non-seasalt Ca2+ + Mg2+ + K+ is found to be about 420 eq ha-1 yr-1 with the predominant range of 400 eq ha-1 yr-1 to 550 eq ha-1 yr-1 thatoccupies more than 45% of total deposition of non-seasalt base cations and dry deposition constitutes on average30% of the total base cation deposition. About 30% of the annualtotal deposition of sulfur is found counteracted by depositionof non-seasalt base cations over South Korea.  相似文献   

4.
The proton budget for a Japanese cedar (Cryptomeria japonica) forest in Gunma Prefecture, Japan, was studied by estimating biogeochemical fluxes. The proton budgets were estimated for three individual compartments of the ecosystem: vegetation canopy, and the upper (O horizon + 0–10 cm) and lower (10–100 cm) soil layers. The dominant proton sources in the compartments were atmospheric deposition (1.2 kmol ha?1 yr?1), nitrification (5.1 kmol, ha?1 yr?1) and base-cation uptake by vegetation (8.0 kmol, ha?1 yr?1) respectively. These proton sources were neutralized almost completely within the individual compartments mainly by base-cation release from the canopy or the soil. The sum of internal proton sources was five times as large as that of external ones. Nitrogen input from the atmosphere was 2.2 kmol ha?1 yr?1, whereas its output from the lower soil layer was 3.9 kmol ha?1 yr?1, indicating that a net loss of nitrogen occurred in the ecosystem. However, this did not cause the acidification of soil leachates because of a sufficient release rate of base cations from the soil.  相似文献   

5.
Ion mass and H+ budgets were calculated for three pristine forested catchments using bulk deposition, throughfall and runoff data. The catchments have different soil and forest type characteristics. A forest canopy filtering factor for each catchment was estimated for base cations, H+, Cl? and SO 4 2? by taking into account the specific filtering abilities of different stands based on the throughfall quality and the distribution of forest types. Output fluxes from the catchments were calculated from the quality and quantity of the runoff water. Deposition, weathering, ion exchange, retention and biological accumulation processes were taken into account to calculate catchment H+ budgets, and the ratio between external (anthropogenic) and internal H+ sources. In general, output exceeded input for Na+, K+, Ca2+, Mg2+, HCO 3 ? (if present) and A? (organic anions), whereas retention was observed in the case of H+, NH 4 + , NO 3 ? and SO 4 2? . The range in the annual input of H+ was 22.8–26.3 meq m?2 yr?1, and in the annual output, 0.3–3.9 meq m?2 yr?1. Compared with some forested sites located in high acid deposition areas in southern Scandinavia, Scotland and Canada, the catchments receive rather moderate loads of acidic deposition. The consumption of H+ was dominated by base cation exchange plus weathering reactions (41–79 %), and by the retention of SO 4 2? (17–49 %). The maximum net retention of SO 4 2? was 87% in the HietajÄrvi 2 catchment, having the highest proportion of peatlands. Nitrogen transformations played a rather minor role in the H+ budgets. The ratio between external and internal H+ sources (excluding net base cation uptake by forests) varied between 0.74 and 2.62, depending on catchment characteristics and acidic deposition loads. The impact of the acidic deposition was most evident for the southern Valkeakotinen catchment, where the anthropogenic acidification has been documented also by palaeolimnological methods.  相似文献   

6.
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   

7.
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   

8.
Information on atmospheric inputs, water chemistry and hydrology were combined to evaluate elemental mass balances and assess temporal changes in elemental transport from 1983 through 1992 for the Arbutus Lake watershed. This watershed is located within a northern hardwood ecosystem at the Huntington Forest within the central Adirondack Mountains of New York (USA). Changes in water chemistry, including increasing NO3 ? concentrations (1.1 μmol c , L?1 yr-1), have been detected during this study period. Starting in 1991 hydrological flow has been measured from Arbutus Lake and these measurements were compared with predicted flow using the BROOK2 hydrological simulation model. The model adequately (r2=0.79) simulated flow from this catchment and was used to estimate drainage for earlier periods when direct hydrological measurements were not available. Modeled drainage water losses coupled with estimates of wet and dry atmospheric deposition were used to calculate solute budgets. Export of SO4 2? (831 mol c ha?1 yr?1) from the greater Arbutus Lake watershed exceeded estimates of atmospheric deposition in an adjacent hardwood stand suggesting an additional source of S. These large drainage losses of SO4 2? also contributed to the drainage fluxes of basic cations (Ca2+, Mg2+, K+ and Na+). Most of the atmospheric inputs of inorganic N were retained (average of 74% of wet precipitation and 85% total deposition) in the watershed. There were differences among years (56 to 228 mol ha?1 yr?1) in drainage water losses of N with greatest losses occurring during a warm, wet period (1989–1991).  相似文献   

9.
Monthly fluxes of sulphate (SO4 2-) and base cations(Ca2+, Mg2+, K+) were studied from 1993 to 1996 as precipitation passed through forest vegetation and surfacesoil layers in an area receiving low and declining levels of atmospheric sulphate pollution. The canopy was dominated by mature Norway spruce (Picea abies Karsten) and the soilwas a podzol developed on glacial till material. The mean annual bulk deposition of SO4 2- collected in the open was 136 molc ha-1 and that of Ca2+, Mg2+ and K+ was 44, 11 and 25 molc ha-1, respectively. The annual total throughfall deposition of SO4 2- was 318 molc ha-1 and that of Ca2+, Mg2+ and K+ was 151, 64 and 181 molcha-1, respectively. Sulphate was the dominant anion accompanying the base cations leached from the canopy. More than half (58%) of the annual total throughfall deposition ofSO4 2- was retained by the O-horizon and only 15% leached from below the B-horizon. The annual leaching of Ca2+, Mg2+ and K+ from below the B-horizon was14, 25 and 9% of the annual total throughfall deposition, respectively. The transport of base cations through the soil was predominantely countered by SO4 2- anions.  相似文献   

10.
The contribution of atmospheric acids to cation leaching from a podzolic soil under mature maple-birch forest in central Ontario was examined during 1983. The movement of base cations was associated largely with NO3 ?, SO4 2? and organic acid anions in surface soil horizons, with SO4 2? and NO3 ? below the effective rooting zone, and SO4 2? and HCO3 ? in streamflow. Mineral soil horizons could adsorb little additional SO4 2? or associated cations at current soil solution SO4 2? concentrations. Therefore it is concluded that the soil in situ lacks a strong affinity for SO4 2?. Current annual inputs to the forest of SO4 2? and NO3 ? in bulk precipitation (26.4 and 18.2 kg ha?1, equivalent to 8.8 kg S and 4.1 kg N ha?1 , respectively) contributed significantly to cation leaching from the soil. In order to maintain exchangeable cations in soil at current levels, a rate of weathering yielding 29.6, 5.0, 4.4 and 2.2 kg ha?1 yr?1 of Ca2+, Na+, Mg2+ and K+, respectively, would be required.  相似文献   

11.
The soil acidification model SAFE was modified to calculate historical changes in geochemistry and runoff since the last glaciation ended at the Lake Gårdsjön F1 catchment 12 000 B.P. Changes in runoff pH and ANC, soil weathering rate, soil mineralogy, soil texture and base saturation was also calculated. The changes in mineralogy compared favorable to data. Modeled historic weathering rates were slightly higher than data suggest, while present weathering rate was somewhat to low, 37 mmolc m?2 yr?1. The weathering rate was very high immediately after the last glaciation, and decreased as the smaller particles were consumed by weathering. The calculated runoff pH follows the pattern of the paleo-inferred pH. SAFE suggests a natural depletion of base cations in the C-layer.  相似文献   

12.
Ecosystems in Finnish Lapland are threatened by heavy metal pollution and acid deposition derived from emissions of Cu-Ni smelters in Kola Peninsula and to varying extent to pollution from southern Fennoscandian and Central European sources. Extensive chemical analyses of small lake waters collected in Finnish Lapland have demonstrated that a significant number of lakes are acidified (ANC < 0μcq/l) or their buffering capacity is critical (ANC = 0–50μe/l). The relative abundance of mafic, ultramafic and carbonate rock components in the catchment were the chief factors controlling ANC and the main base cation (Ca2+, Mg2+) concentrations of lake waters. Both humic and clearwater lakes with low buffering capacity (ANC < 50μeq/l) were mainly located in the catchment areas identified as sensitive to acidification on the basis of low content of base cations (Ca2+ +Mg2+ +K+ < 500 meq/kg) in till. The ratio of the catchment area to the lake area was distinctly smaller for acidic lakes than for the well-buffered lakes, indicating the importance of catchment processes in determining the ANC and main base cations. The high sulphur concentrations (median 60μeq/1) of acidic lakes in northeastern Lapland, near the Finnish-Norwegian border, were strongly correlated with the highest deposition of sulphur derived from smelters of Kola Peninsula. The anomalously high concentrations of sulphur of well-buffered lakes in the western part of Lapland were due to sulphide minerals of soil and bedrock. The acidity of humic lakes in southern Lapland was in large part due to the organic acidity derived from peatlands.  相似文献   

13.
SO4 2?, NO3 ? and H+ depositions are estimated in the Brazilian territory based on the existing rainfall chemical data and on annual rainfall distribution over the whole territory. Local and regional depositions are estimated. Rainfall chemical data over the Braziliian territory shows that the average pH values are usually low (between 4.0 and 5.5). These values are observed in the tropical Amazon forest as well as in urban areas. However, the rainwater acidity in the tropical forests are due to organic acids naturally produced by the vegetation while in urban areas the acidity is mainly due to acidic anion deposition (NO3 ? and SO4 2?). In some Amazonian areas, the average input values through rainfall for NO3 ? is about 0.06 keq.ha.yr?1 and for SO4 2? is between 0.23 and 0.54 keq.ha?1.yr?1. On the other hand, in some urban centers, such as São Paulo, values of .072 keq.ha?1.yr?1 for NO3 ? and 1.16 keq.ha?1.yr?1 of SO4 2? are found and in sites where sulfate sources (coal mining) are present, as for the area of Florianópolis, values as high as 5.59 keq.ha?1.yr?1 for SO4 2? are found.  相似文献   

14.
To develop phosphorus-based agronomic application rates of phytase-diet, bisulfate-amended Delmarva poultry litter in conservation tillage systems, nutrient release dynamics of the organic fertilizer under local weather conditions were investigated. Delmarva poultry litter was placed in polyvinyl chloride columns to a depth of 5 cm and weathered in the field for 570 days. Leachate from the columns was collected and measured for concentrations of various nutrients. Cumulative release of the nutrients as a function of weathering time was modeled, and the nutrient supply capacity was determined. Poultry litter leachate contained high contents of dissolved organic carbon (15–31,500 mg L?1), nitrogen (N 5–7,070 mg L?1), phosphorus (P 5–230 mg L?1), potassium (K+ 2–7,140 mg L?1), and other nutrients. Release of most nutrients occurred principally in the first 100 days, but for P and calcium (Ca2+), it would last for years. The release kinetics of N followed a logarithm equation, while P and K demonstrated a sigmoidal logistic pattern. The nutrient supply capacity of surface-applied Delmarva poultry litter was predicted at 10.9 kg N Mg?1, 6.5 kg P Mg?1, 34.7 kg K+ Mg?1, 5.4 kg Ca2+ Mg?1, and 14.0 kg SO 4 2? Mg?1. The results suggest that Delmarva poultry litter should be applied to conservation tillage systems at 6.6 Mg ha?1 that would furnish 25 kg P ha?1 and 63 kg N ha?1 to seasonal crops. In repeated annual applications, the rate should be reduced to 5.2 Mg ha?1, with supplemental N fertilization to meet crop N requirements.  相似文献   

15.
The present study was conducted in tropical Sal forest ecosystem of the Doon valley in the Indian Himalayas to assess the critical load of sulfur and nitrogen and their exceedances. The observed pattern of throughfall ionic composition in the study are Ca2+>K+>Mg2+>Cl?>?HCO3?>?Na+>NO 3 ? >?SO 3 2? ???NH 4 + >F?. The sum of cation studied is 412.29 ??eq l?1 and that of anions is 196.98 ??eq l?1, showing cation excess of 215.31 ??eq l?1. The cations, namely Ca2+, Mg2+, K+, Na+, and NH 4 + , made a contribution of about 67% of the total ion strength, where as anion comprising of SO 4 2? , Cl?, NO 3 ? , and HCO 3 ? contributed 33%. The chief acidic components were Cl?C (12%) and HCO 3 ? (8%), while the presence of SO 4 2? (5%) and NO 3 ? (6%), respectively. Percentage contribution of bole to total aboveground biomass was ??72.38% in comparison to 2.24?C2.93% of leaf biomass, 10.34?C10.96% of branch biomass and 13.21?C17.07% of bark biomass. There was high and significant variation (P?<?0.001) in the total aboveground biomass produced at different sites. The aboveground net primary productivity (ANPP) in these sites ranged between 2.09 and 9.22 t ha?1 year?1. The base cations and nitrogen immobilization was found to be maximum in bole. The net annual uptake of the base cations varied from 306.85 to 1,311.46 eq ha?1 year?1 and of nitrogen from 68.27 to 263.51 eq ha?1 year?1. The critical appraisal of soil showed that cation exchange capacity lied between 18.37 and 10.30 Cmol (p+) kg?1. The base saturation percentage of soil was as high as 82.43% in Senkot, whereas in Kalusidh it was just 44.28%. The local temperature corrected base cation weathering rates based on soil mineralogy, parent material class, and texture class varied from 484.15 to 627.25 eq ha?1 year?1, showing a weak potentiality of the system to buffer any incoming acidity and thus providing restricted acid neutralizing capacity to keep the ecosystem stable under increased future deposition scenarios in near future. The appreciable BS of the soil indicates the presence of intense nutrient phytorecycling forces within this climate and atmospheric deposition in replenishing base cations in the soil, which includes intrinsic soil-forming processes, i.e., weathering. The highest value of critical load for acidity was 2,896.50 eq ha?1 year?1 and the lowest was 2,792.45 eq ha?1 year?1. The calculated value of the minimum critical loads for nitrogen varied from 69.77 to 265.01 eq ha?1 year?1, whereas the maximum nitrogen critical load ranged between 2,992.63 and 4,394.45 eq ha?1 year?1. The minimum and the maximum critical loads of sulfur ranged between 2,130.49 and 3,261.64 eq ha?1 year?1 and 2,250.58 and 3,381.73 eq ha?1 year?1, respectively. The values of exceedance of sulfur and nitrogen were negative, implying that in the current scenario Sal forests of the Doon valley are well protected from acidification.  相似文献   

16.
The effects of artificial precipitation with different pH levels on soil chemical properties and element flux were studied in a lysimeter experiment. Cambic Arenosol (Typic Udipsamment) in monolith lysimeters was treated for 6 1/2 yr with 125 mm yr?1 artificial rain in addition to natural precipitation. Artificial acid rain was produced from groundwater with H2SO4 added. pH levels of 6.1, 4 and 3 were used. ‘Rain’ acidity was buffered, mainly due to cation exchange with Ca2+ and Mg2+, which were increasingly leached due to the acid input. The H+ retention was not accompanied by a similar increase in the output of Al ions, but a slight increase in the leaching of Al ions was observed in the most acidic treatment. The net flux of SO4 2? from the lysimeters increased with increasing input of H2SO4, but in the most acidified lysimeters significant sorption of SO4 2? was observed. The sorption was, however, most likely a concentration effect. The ‘long-term’ acidification effects on soil were mainly seen in the upper O and Ah-horizons, where an impoverishment of exchangeable Ca2+ and Mg2+ was observed. An increased proportion of Al ions on exchange sites in the organic layer was observed in the pH 3-treated soil. By means of budget calculations the annual release of base cations due to weathering was estimated to be between 33 and 77 mmolc m?2.  相似文献   

17.
Abstract

Assessing base cation [calcium (Ca2+), magnesium (Mg2+), potassium (K+)] fluxes is necessary for determining ecosystem stability. This study was conducted in the Osinovka River catchment located on the Khamar‐Daban Ridge, South Baikal, which is characterized by high precipitation (more than 1700 mm per annum). The contributions of different ecosystem components such as atmospheric deposition, soil exchange pool, minerals, vegetation, surface water, and groundwater into the total base cations flux were evaluated, combining the strontium isotope approach and budget study. Results show the leading role of atmosphere in ecosystem supply with base cations. The atmosphere contributes 48% of total base cations flux, and its contributions to plant‐available nutrition pools of both organic and mineral horizons are equal to 50%. This makes the vitality of vegetation, to a great extent, dependent on the stability of atmospheric chemistry.  相似文献   

18.
This paper describes the effect of treating a nutrient-poor forest soil in monolith lysimeters with H2SO 4, pH 3.0, for 4.75 yr. The lysimeters were instrumented with porous cup probes to distinguish processes occurring in each soil horizon. In the A horizon base cation exchange and sulphate absorption were the principal proton- consuming processes whereas lower down the profile Al3+ dissolution from hydrous oxides dominated. Acid treatment thus reduced the amount of amorphous Al in the lower horizons, but exchangeable Al was unaffected. Sulphate absorbtion was positively correlated with the distribution of Al hydrous oxides. High rates of nitrification reduced the differences between acid and control monoliths, but acid treatment significantly reduced soil pH down to 75 cm and reduced the levels of exchangeable base cations in the litter and A horizons. Acid treatment increased the leaching rates of base cations and Al. Consideration of the total base cation content shows that acid treatment increased the rate of weathering by 0.7–1.4 k eq ha?1 yr?1. The results should be useful in modelling more realistic rates of acid input to similar soils.  相似文献   

19.
The Laflamme Lake Watershed Area is located in a sensitive region on the Canadian Shield and is subjected to wet atmospheric loading between 17 and 25 kg ha?1 yr?1. From 1981 to 1988, the level and fluctuations of the atmospheric deposition of acidifying substances has led to various responses in the water chemistry of headwater lakes in the area. The general trend in atmospheric inputs is a gradual increase of acidifying substances from 1981 to 1985 followed by a 2 yr decrease then a return to previous values. In the two lakes with almost no alkalinity acidification has occured throughout the 1983 to 1988 period. In the four lakes with slightly higher alkalinity values, a reversal in acidification is seen when atmospheric loading decreased in 1986. Along with the interannual trends, seasonal variability to acidification occurs with sensitivity of surface waters being highest during spring melt. Sensitivity to acidification can also be altered by watershed processes and in the Laflamme Lake Watershed, soil processes are effective in altering the acidity of precipitation before it reached the lake. In this watershed, wet atmospheric inputs of H+ and NO3 ? are larger than surface water outputs while the reverse occurs for Ca2+, Mg2+, Na+, K+, Cl? and SO4 2?.  相似文献   

20.
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   

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