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1.
Longitudinal and temporal variations in water chemistry were measured in several low-order, high-elevation streams in the Great Smoky Mountains to evaluate the processes responsible for the acid-base chemistry. The streams ranged in average base flow ANC from ?30 to 28 μeq L?1 and in pH from 4.54 to 6.40. Low-ANC streams had lower base cation concentrations and higher acid anion concentrations than did the high-ANC streams. NO3 ? and SO4 2? were the dominant acid anions. NO3 ? was derived from a combination of high leaching of nitrogen from old-growth forests and from high rates of atmospheric deposition. Streamwater SO4 2? was attributed to atmospheric deposition and an internal bedrock source of sulfur (pyrite). Although dissolved Al concentrations increased with decreasing pH in the study streams, the concentrations of inorganic monomeric Al did not follow the pattern expected from equilibrium with aluminum trihydroxide or aluminum silicate phases. During storm events, pH and ANC declined by as much as 0.5 units and 15 μeq L?1, respectively, at the downstream sites. The causes of the episodic acidification were increases in SO4 2? and DOC.  相似文献   

2.
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   

3.
A large data base on inland lakes in the Upper Great Lakes Region (UGLR) was used to evaluate assumptions and relationships of empirical acidification models. Improved methods to calculate background alkalinity and background SO4 2? are reported; SO4 2? enrichment factors indicate that terrestrial SO4 2? sources and watershed or lake sinks must be considered for site-specific background SO4 2? estimates. Significant relationships were found between lake acidification estimated as change in SO4 2? and precipitation acidity but not between changes in lake alkalinity and precipitation acidity in this lightly impacted region.  相似文献   

4.
Discharge to concentration relationships for eight streams studied by the U.S. Geological Survey (USGS) as part of the U.S. Environmental Protection Agency's (U.S. EPA) Long-Term Monitoring Project (1983–89) indicate acidification of some streams by H2SO4 and HNO3 in atmospheric deposition and by organic acids in soils. Concentrations of major ions in precipitation were similar to those reported at other sites in the northeastern United States. Average concentrations of SO4 2? and NO3 ? were similar among streams, but base cation concentrations differed widely, and these differences paralleled the differences in acid neutralizing capacity (ANC). Baseflow ANC is not a reliable predictor of stream acidity at high flow; some streams with high baseflow ANC (>150 Μeq L?1) declined to near zero ANC at high flow, and one stream with low baseflow ANC (<50 Μeq L?1) did not approach zero ANC as flow increased. Episodic decreases in ANC and pH during peak flows were associated with increased concentrations of NO3 ? and dissolved organic carbon (DOC). Aluminum concentrations exceeding 300 Μg L?1 were observed during peak flows in headwater streams of the Neversink River and Rondout Creek. Seasonal Kendall Tau tests for temporal trends indicate that SO4 2? concentrations in streamwater generally decreased and NO3 ? concentrations increased during the period 1983–1989. Combined acid anion concentrations (SO4 2? + NO3 ?) were generally unchanged throughout the period of record, indicating both that the status of these streams with respect to acidic deposition is unchanged, and that NO3 ? is gradually replacing SO4 2? as the dominant acid anion in the Catskill streams.  相似文献   

5.
Fresh snowfall was collected on the surface of 8 lakes across a 350 km west-east transect from northeastern New York state to the coast of Maine after a single storm. In addition, every snowfall event during the winter of 1993 was collected on a single lake near the center of the transect. Across the transect, midwestern sources appear to dominate Pb and Cd concentrations, while Sb appears to be derived from midwestern sources as well as local and/or industrial East Coast sources. In all samples, the highest Na, Cl and Mg concentrations reflect a marine influence, but at some transect sites roadspray aerosol appears to contribute to Na and Cl concentrations. The regional pattern of Ca, K, Mn and Sr concentrations and Mn/Sr ratios indicate that woodsmoke may be an important winter source of these elements at some sites. In all samples, H+ is strongly correlated with NO3 ? (R2 = 0.97) and mean NO3 ?/SO4 2? molar ratios of 6.4 for transect samples, and 4.7 for temporal samples, are higher than mean NO3 ?/SO4 2? reported for other precipitation studies in the same region. The contribution of NO3 ? to the snowpack greatly exceeds that of SO4 2?, and may be a major source of acidity in aquatic ecosystems during snowmelt.  相似文献   

6.
The seasonal patterns of flow and the concentrations of color, Mg, Ca, H+, Na, Cl, organic anions, SO4, and Gran alkalinity are examined for five streams or rivers in Kejimkujik National Park (Lower Mersey River, Atkins Brook, Grafton Brook, Pebbleloggitch Brook, and Beaverskin Brook). These range in organic color and acidity from very darkwater Atkins Brook (average 191 Hazen units, pH 4.2) to clearwater Beaverskin Brook (5 Hazen units, pH 5.5). In general, most dissolved substances are present in a relatively large concentration during the high-flow period of winter-spring (most notably color, Mg, H+, Ca, Na, organic anions, and SO4). In contrast, Gran alkalinity generally occurs in its highest concentration during the lowflow period. These observations suggest that during the high-flow period, substances are “flushed” from the terrestrial watersheds of these rivers and streams.  相似文献   

7.
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   

8.
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9.
伴随阴离子对马铃薯种植冲击土中钾素固持与淋溶的影响   总被引：1，自引：0，他引：1  
V. SHARMA  K. N. SHARMA 《土壤圈》2013,23(4):464-471
A column study was carried out to assess the influence of accompanying anions on potassium (K) leaching at potato growing sites with different soil textures (sandy loam and clay loam) in northwestern India. Potassium was applied in the top 15 cm layer of soil column at 30 and 60 mg K kg-1 through different sources having different accompanying anions (Cl-, SO42-, NO3- and H2PO4-). Maximum K was retained in the top 0--15 cm layer with a sharp decrease in K content occurring in 15--30 cm layer of the soil column. The trend was similar for both levels of applied K as well as frequency of leaching and soil type. The decrease of K content in soil column after four leaching events was maximum in case of Khanaura sandy loam, while only minor decrease was observed in Hundowal clay loam when K was applied at 60 mg K kg-1, indicating higher potential of clay rich soil to adsorb K. In general, the K leaching in presence of the accompanying anions followed the order of SO42- ≤ H2PO42- < NO3- = Cl-. Highest 1 mol L-1 CH3COONH4-extractable K was retained when K was applied along with SO42- and H2PO4- anions, and the least was retained when accompanying anion was Cl-1. The influence of anions was more pronounced in the light textured soil and at high amounts of K application. Higher levels of K application resulted in higher losses of K, especially in sandy loam soil as observed from the leachate concentration. Among the different K sources, the maximum amount of K leaching was noticed in the soil column amended with KCl. After four leachings, the maximum amount of K leached out was 6.40 mg L-1 in Hundowal clay loam and 9.29 mg L-1 in Khanaura sandy loam at 60 mg K kg-1 of soil application through KCl. These concentrations were lower than the recommended guideline of the World Health Organisation (12.00 mg L-1).  相似文献   

10.
Five wetlands, each 6 m wide and 30 m long and containing 30 cm of an organic substrate (Sphagnum peat to which limestone and fertilizer were surface-applied on a quarterly basis, Sphagnum peat, sawdust, straw/manure, spent mushroom compost), were exposed to controlled inputs of acid coal mine drainage (AMD; pH 2.89, soluble Fe, Mn, and SO4 2? concentrations of 119, 19, and 3132 mg L?1, respectively) at a mean flow rate of 8513 L da?1 for 111 weeks, beginning in July of 1989. All wetlands were net sources, rather than sinks, for base cations (Ca2+, Mg2+, Na+, K+). The Sphagnum peat wetland was the least effective in treating the AMD, retaining 35% of the soluble Fe influx, but not retaining substantial H+, soluble Mn, soluble Al, SO4 2?, or acidity. The straw/manure and mushroom compost wetlands were the most effective in treating the AMD, retaining 53 and 67% of the H+ influx, 80 and 78% of the soluble Fe influx, 7 and 20% of the soluble Mn influx, 54 and 53% of the soluble Al influx, 15 and 11% of the SO4 2? influx, and 57 and 63% of the acidity influx. For these two wetlands especially, treatment effectiveness was substantially diminished during the cold winter months of January through March. Moreover, from March through July of the final year of the study, treatment effectiveness was minimal with outflow pH and concentrations of soluble Fe, Mn, Al, SO4 2? and acidity that were similar to inflow values. Decreases in treatment effectiveness over time appeared to be related to a decrease in the ability to counter the substantial acid load entering the wetlands in the AMD. Lime or limestone dissolution and bacterial dissimilatory sulfate reduction may have contributed substantially to pH improvement and acidity consumption in the straw/manure and mushroom compost wetlands, but after 2 years the cumulative input of acidity apparently had overwhelmed biotic and abiotic alkalinity generating mechanisms, as reflected in a progressive decrease in both substrate pH and abiotic acid neutralization capacity (ANC) over time, especially in the surface substrates. Also over time, effluent H+ and acidity concentrations became more like influent and H+ and acidity concentrations. Although samples of wetland interstitial water were not collected for chemical analysis, as substrate pH and ANC decreased and as influent and effluent water chemistry became more similar, it is likely that wetland interstitial water became progressively more acidic, potentially inhibiting bacterial processes that could contribute to effective treatment, favoring dissolution rather than formation of insoluble metal precipitates, and thereby contributing to the eventual failure of the wetlands to effectively treat the AMD. In general, when constructed wetlands are used to treat particularly acidic (pH<4) AMD, if abiotic and biotic alkalinity generation cannot balance the influent acid load, long-term effective treatment will not be achieved.  相似文献   

11.
There is a declining gradient of wet SO4 deposition from south to north in Nova Scotia with the highest values being in the south, along with a localized increase around the Halifax metropolitan area, due to local SO4 emission. Edaphic conditions such as drainage from soils containing gypsum or drainage on disturbed rocks containing pyrite, provide additional SO4 to surface waters.Acidity is usually absent in the former (pH > 7.0) and very high in the latter (as low as pH 3.6). By contrast peaty, organic drainages release water low in SO4 during the growing season but they release high amounts of organic anions (A?), consequently, these waters maintain decreased pH values, usually < 4.5. A study of over 80 wetlands and lakes during the ice free period in Nova Scotia showed that sea salt corrected SO4 concentrations range from 45 ueq L?1 in the south end of the province, ～30 ueq L?1 in the Kejimkujik area and < 17 ueq L?1 in the northern areas with values > 85 ueq L?1 in the Halifax area, reflecting the atmospheric deposition pattern of SO4 The SO4 concentrations may be > 2000 ueq L?1 in drainages containing gypsum, > 700 ueq L?1 in drainages over pyrite bearing socks but < 20 ueq/L?1 in streams draining bogs. The SO4 concentrations change considerably during the non-growing season when the ground is saturated with water or frozen, and the runoff is high (snow and rain often alternate in winter). Under such conditions SO4 concentration drops in the two former cases and increases in bog drainages, accompanied with a considerable drop in (A?) concentrations. Care should be taken when interpreting SO4 concentrations in surface waters in Nova Scotia with respect to atmospheric SO4 deposition.  相似文献   

12.
Methods for quantifying the influence of different ions on depressions in ANC, based on those used by Molot et al. (1989), have been employed on streams in the Adirondack and Catskill Mountains of New York. Streams were intensively monitored during the Episodic Response Project of the US EPA Baseflow values were determined for each variable, and for each low-ANC sample the proportion of ANC depression (relative to baseflow) contributed by each ion was calculated, In the Catskill streams Ca2+ dilution and NO3 – increases were major causes of ANC depression; SO4 2– dilution and Al mobilisation increased ANC. In the Adirondack streams Ca2+ and Na+ dilution, and NO3 – and SO4 2– increases, all contributed to ANC depressions. Inter-stream differences in results were linked to differences in stream acidity; in both regions Ca2+ dilution dominated ANC depressions in circumneutral streams, whereas NO3 – increases were dominant in acidic streams. Organic anions contributed more to ANC depressions in acidic streams. Al buffering, was negligible in circumneutral streams, but more than halved ANC depressions in the most acidic stream. Individual base cation behaviour differed widely, suggesting that caution should be used when treating them as a uniform group.  相似文献   

13.
The relation between soil acidification and element cycling   总被引：2，自引：0，他引：2  
Controversy about the contribution of acidic deposition to soil acidification partly arises from different concepts of soil acidification. Differentiating between actual and potential soil acidification has proved to be appropriate for properly identifying and quantifying the natural and anthropogenic sources of protons. Actual soil acidification is primarily manifested by leaching of cations from the soil, regulated by the mobility of major anions. Leaching of HCO3 ? and RCOO? occurs naturally whereas leaching of NO3 ? and SO4 2? is mainly caused by land use in agricultural soils and by acidic deposition in forest soils. Potential soil acidification is primarily due to accumulation of atmospherically derived N and S. This potential acid threat is partly realized by mineralization processes after the removal of vegetation.  相似文献   

14.
The effect of different anions on the balance of heavy metal cations in the soil-solution system has been assessed under model laboratory conditions. It has been found that the uptake of the Cu, Zn, and Pb cations by an ordinary chernozem from solutions of different salts is accompanied by the displacement of the exchangeable cations to the solution in the following order: Ca2+ > Mg2+ > Na+ > K+. The sum of the displaced exchangeable cations in most cases exceeds the amount of the adsorbed heavy metal cations. According to the effect of the anions on the displacing capacity of the metal cations, the following series are formed: for copper, SO 4 2? ? Cl? > OAc? > NO 3 ? ; for lead, Cl? ? NO 3 ? > OAc?; and, for zinc, SO 4 2? ? Cl? ? OAc? > NO 3 ? .  相似文献   

15.
LAPAN has measured rain acidity in Bandung, the location is Cipedes since 1985, with average pH in 1985 was 6.25. The pH condition 1985–1999 as follow: The monthly average of pH in period 1985–1992 was >5.6: in the middle of 1996–1997 it had big variation and than decrease until now. The monthly average of pH in 1997 until now was <5.6. The pH has decreasing trend, the reason was increasing fuel combustion for transportation and household because the area around the observation was change from rural to be transportation and settlement area. The rain acidity comparison in Cipedes (rural site), Cicahuem (busy site), and Tanjungsari (remote site) hold in 1986–1987, the result was Tanjungsari the remote site had the lowest pH. It's suggested the reason was sulphur compound from Kamojang crater and air pollution from industrial area in south-east of Bandung were blown by the wind through this place. The influence of air pollution to acid rain was studied by measurement NO3 ? and SO4 2? in 5 places around Bandung, the results were: North of Bandung had the lowest NO3 ? concentration because the traffics were low: but had the highest SO4 2? concentration; it's caused by emission of sulphur compounds from Tangkuban Perahu Montain. South of Bandung had the highest NO3 ? concentration because the traffics were crowded and a lot of industries around it. In general Bandung had SO4 2? concentration higher than NO3 ? concentration, it's suggested due to the influence of sulphur compound from Tangkuban Perahu Montain. The observation rain acidity in Ciater at Tangkuban Perahu Montain started in 1996, the result in period 1996–1998 as follow: The pH had decreasing trend, it's due to the traffic near this observation increase, so the air pollution around this area increase, it will influence the rain acidity. The maximum monthly average of ph was 6.78 and minimum was 4.63, the pH monthly average generally < 6. In El NINO year 1997, the monthly average of pH in April and December were > 6.5.  相似文献   

16.
Bayesian regularized back-propagation neural network (BRBPNN) was developed for trend analysis, acidity and chemical composition of precipitation in North Carolina using precipitation chemistry data in NADP. This study included two BRBPNN application problems: (i) the relationship between precipitation acidity (pH) and other ions (NH4 +, NO3 ?, SO4 2?, Ca2+, Mg2+, K+, Cl? and Na+) was performed by BRBPNN and the achieved optimal network structure was 8-15-1. Then the relative importance index, obtained through the sum of square weights between each input neuron and the hidden layer of BRBPNN(8-15-1), indicated that the ions' contribution to the acidity declined in the order of NH4 + > SO4 2? > NO3 ?; and (ii) investigations were also carried out using BRBPNN with respect to temporal variation of monthly mean NH4 +, SO4 2? and NO3 ? concentrations and their optimal architectures for the 1990–2003 data were 4-6-1, 4-6-1 and 4-4-1, respectively. All the estimated results of the optimal BRBPNNs showed that the relationship between the acidity and other ions or that between NH4 +, SO4 2?, NO3 ? concentrations with regard to precipitation amount and time variable was obviously nonlinear, since in contrast to multiple linear regression (MLR), BRBPNN was clearly better with less error in prediction and of higher correlation coefficients. Meanwhile, results also exhibited that BRBPNN was of automated regularization parameter selection capability and may ensure the excellent fitting and robustness. Thus, this study laid the foundation for the application of BRBPNN in the analysis of acid precipitation.  相似文献   

17.
Acidic groundwaters and soils in Halland County (Hailands län), southwest Sweden, have been investigated with respect to conditions of soluble aluminium (Al) and sulphate (SO4 2?. Basic Al-sulphate, Fe-oxide, Al-oxide, Al-hydroxide and clay minerals, are discussed and evaluated in their roles for governing Al and SO4 2? in the groundwaters. Based on this investigation, it is suggested that Al3+ solubility is controlled by amorphous Al-hydroxide. The SO4 2? in the groundwaters will depend primarily on the H2SO4 input. The H2SO4 load enhances soil mineral weathering which enhances the production of Fe-oxides, i.e. anion exchange surface sites, to which groundwater SO4 2? attain adsorption equilibra. The factors that control solubility of Al and SO4 2? are both influenced by the acidity in the soil catenas which in the area largely depend on the H2SO4 input. Clay minerals such as illite, smectites, halloysite, and variable composition Al-silicates do not exert strong control on Al in the groundwaters investigated.  相似文献   

18.
This study reports the evaluation of chemical composition of a Black Vistula and White Vistula streams’ waters taking into consideration both geological conditions of the stream’s catchment area and different water’ level related to seasonal variations in particular catchment ecosystem (high stage: beginning of the vegetation period; medium stage: vegetation period; low stage: final time of vegetation period). The complex data matrix (744 observations), obtained by the determination of major inorganic analytes (Cl?, NO3 ?, SO4 2?, NH4 +, Na+, K+, Ca2+, Mg2+) in water samples by ion chromatography was treated by linear discriminant analysis and non-parametrical testing. In case of both streams obtained results indicate presence of two discriminant functions (DFs). The data variance explained by DFs is as follows: Black Vistula stream—first DF: 93.5%, second DF: 6.5%; White Vistula stream—first DF: 66.3%, second DF: 33.7%. In case of Black Vistula stream first DF allows distinction of medium, high and low waterstage related samples while second DF between high/low and medium water stage related samples. In case of White Vistula stream first DF allowed to distinguish between medium/high and low water stage related samples while second DF between medium and high water level samples. In case of both streams, the most informative DFs were related to geological conditions of investigated catchments (contents of Cl?, Na+, K+, Mg2+, Ca2+, SO4 2?), while the second to nutrient biocycle (mainly NH4 + and NO3 ?) related to slope’s exposition and inclination.  相似文献   

19.
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   

20.
The Rhode River estuarine/watershed system is a tributary of Chesapeake Bay located on the inner Atlantic Coastal Plain. Its soils are fine sandy loams. Bulk precipitation pH in the spring season declined from 4.95 in 1974 to 3.82 in 1981 and was 4.03 in 1985. The changes in pH of a forested primary stream were more related to changes in bulk precipitation pH than were the changes in pH of agricultural streams, reflecting the importance of other major terrestrial sources of acidity on agricultural systems. Surges in acidity and dissolved total Al concentration in primary (first order) streams reached extremes of pH 3.2 and 300 μg Al L?1. Higher order streams were observed to have surges in acidity with pH minima below 5.0. Surges in acidity ocurred during accelerated groundwater percolation following storm events and did not coincide with surface runoff or snowmelt. One of the reasons why groundwater is more acidic than surface runoff is that the vegetation exchanges H30 + for alkaline cations in the soil and translocates these ions to the vegetational canopy. When it rains, subsequently, H30+ in the precipitation displace some of these alkaline cations from the canopy. The end result is that overland flow during storms is enriched in alkaline cations, while groundwater is enriched in H30+. Although the source of dissolved Al is dissolution of clay minerals with atomic ratios of Al to silicate of 1:l, 1:2, or 1:3, this ratio in stream water rapidly declined to 1:1200 due to loss of Al. On average, forest drainage was the most acidic, the highest in dissolved Al, and the lowest in Ca. Surges in acidity were most severe from pastureland, and next most severe from cropland. Total fluoride concentrations were high relative to Al from all three land uses. Rhode River spawning runs of Perca flavescens declined drastically from the early 1970s to essentially zero since 1981. Larval bioassays of acidity indicate negligible toxicity to Hyla crucifer, significant toxicity to Perca flavescens and drastic effects on Morone saxatilis at pH 5.0.  相似文献   

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