Impact Of Acid Deposition Research Articles

Impacts of acid deposition and lake browning on long-term organic carbon storage in Canadian northern forest lakes

Impacts of acid deposition and lake browning on long-term organic carbon storage in Canadian northern forest lakes

Exploring the acid neutralizing effect in rainwater collected at a tropical urban area: Central Valley, Costa Rica

We report on the chemical and the carbon isotopic composition of dissolved inorganic carbon (DIC) of rainwater collected between May and October 2020 in the Central Valley, Costa Rica. Precipitation samples were collected daily (N = 55) and analyzed for major ions, DIC, and δ13CDIC. Significant correlation (p < 0.05) between main acidic (SO42− and NO3−) and major alkaline (Ca2+ and NH4+) species confirmed a very effective acid neutralization effect in rainwater (average pH: 5.90 ± 0.74). Significant temporal variations (p < 0.05) of δ13CDIC indicated the contribution of carbonate salts in rainwater from May to October but also CO2 dissolution at the beginning of the wet season (May), probably due to increased CO2 emissions from soil degassing. Temporal changes of Ca2+ neutralization factors followed the observed changes in δ13CDIC, which confirmed the high buffer capacity of precipitation in our study. HYSPLIT analysis also revealed long-range contributions of pedogenetic carbonates (e.g., Saharan dust) responsible for the acid neutralization capacity of rainwater (e.g., from July to September). Principal component analysis showed that four main factors explain 65% of the variance are: i) acid neutralization processes (Ca2+ neutralization factor), ii) marine salts (Cl−, Na+), iii) fossil fuels (SO42−, NO3−), and iv) agriculture/fertilizers (NO3−, NH4+, K+). Our study demonstrated that a combined approach of chemical, isotope, and statistical analysis techniques can help unravel the mechanism of acid neutralization of rainwater in tropical urban areas. This information has strong implications for future studies related with the impact of acid deposition on ecosystem functioning, water quality, and infrastructure degradation.

Disentangling the responses of dissolved organic carbon and nitrogen concentrations to overlapping drivers in a northeastern United States forested watershed

The concurrent reduction in acid deposition and increase in precipitation impact stream solute dynamics in complex ways that make predictions of future water quality difficult. To understand how changes in acid deposition and precipitation have influenced dissolved organic carbon (DOC) and nitrogen (N) loading to streams, we investigated trends from 1991 to 2018 in stream concentrations (DOC, ~3,800 measurements), dissolved organic nitrogen (DON, ~1,160 measurements), and dissolved inorganic N (DIN, ~2,130 measurements) in a forested watershed in Vermont, USA. Our analysis included concentration-discharge (C-Q) relationships and Seasonal Mann-Kendall tests on long-term, flow-adjusted concentrations. To understand whether hydrologic flushing and changes in acid deposition influenced long-term patterns by liberating DOC and dissolved N from watershed soils, we measured their concentrations in the leachate of 108 topsoil cores of 5 cm diameter that we flushed with solutions simulating high and low acid deposition during four different seasons. Our results indicate that DOC and DON often co-varied in both the long-term stream dataset and the soil core experiment. Additionally, leachate from winter soil cores produced especially high concentrations of all three solutes. This seasonal signal was consistent with C-Q relation showing that organic materials (e.g., DOC and DON), which accumulate during winter, are flushed into streams during spring snowmelt. Acid deposition had opposite effects on DOC and DON compared to DIN in the soil core experiment. Low acid deposition solutions, which mimic present day precipitation, produced the highest DOC and DON leachate concentrations. Conversely, high acid deposition solutions generally produced the highest DIN leachate concentrations. These results are consistent with the increasing trend in stream DOC concentrations and generally decreasing trend in stream DIN we observed in the long-term data. These results suggest that the impact of acid deposition on the liberation of soil carbon (C) and N differed for DOC and DON vs. DIN, and these impacts were reflected in long-term stream chemistry patterns. As watersheds continue to recover from acid deposition, stream C:N ratios will likely continue to increase, with important consequences for stream metabolism and biogeochemical processes.

Diatom blooms and associated vegetation shifts in a subarctic peatland: responses to distant volcanic eruptions?

ABSTRACTWe test the hypothesis that rich occurrences of diatoms observed at transitions between major peat units representing different vegetation communities in a peat sequence from subarctic northern Sweden reflect responses to acid deposition from the Samalas AD 1257 and Laki AD 1783/1784 eruptions. We observe sudden changes in the mire ecosystem and thereby in the trophic status and biogeochemical cycling of the peatland. Both the eruptions are known to have been associated with significant acid deposition events and climatic anomalies, as recorded in polar ice cores. To test the hypothesis, new chronological analyses and age modelling were applied to existing biogeochemical and biological records from the peat sequence. This approach yielded modelled age ranges of AD 1239–1284 (1σ)/AD 1210–1303 (2σ) (median: AD 1260) and AD 1674–1795 (1σ)/AD 1665–1875 (2σ) (median AD 1743), respectively, for the stratigraphic transitions. Hence, the modelled age ranges bracket the ages of the eruptions in question and the hypothesis could therefore not be rejected. Impacts of acid deposition from the eruptions are assumed to have caused instant acidification, vegetation damage, increased nutrient cycling and blooms of opportunistic epiphytic diatoms. In addition, cooling may have contributed to vegetation changes through permafrost inception, frost heave and thereby altered hydrological conditions.

The Impact of Acid Dep osition on China’s Three Gorges Reservoir

The Impact of Acid Dep osition on China’s Three Gorges Reservoir

Impacts of acid deposition, ozone exposure and weather conditions on forest ecosystems in Europe: an overview

In 1994, a “Pan-European Programme for Intensive and Continuous Monitoring of Forest Ecosystems” started to contribute to a better understanding of the impact of air pollution, climate change and natural stress factors on forest ecosystems. The programme today counts approximately 760 permanent observation plots including near 500 plots with data on both air quality and forest ecosystem impacts. This paper first presents impacts of air pollution and climate on forests ecosystems as reported in the literature on the basis of laboratory and field research. Next, results from monitoring studies, both at a European wide scale and related national studies, are presented in terms of trends and geographic variations in nitrogen and sulphur deposition and ozone concentrations and the impacts of those changes in interaction with weather conditions on (i) water and element budgets and nutrient-acidity status, (ii) forest crown condition, (iii) forest growth and carbon sequestration and (iv) species diversity of the ground vegetation. The empirical, field based forest responses to the various drivers are evaluated in view of available knowledge. Analyses of large scale monitoring data sets show significant effects of atmospheric deposition on nutrient-acidity status in terms of elevated nitrogen and sulphur or sulphate concentrations in forest foliage and soil solution and related soil acidification in terms of elevated aluminium and/or base cation leaching from the forest ecosystem. Relationships of air pollution with crown condition, however, appear to be weak and limited in time and space, while climatic factors appear to be more important drivers. Regarding forest growth, monitoring results indicate a clear fertilization effect of N deposition on European forests but the field evidence for impacts of ambient ozone exposure on tree growth is less clear.

Impact of Acid Deposition on the Main Nutrients of Subtropical Forest Soil

Acid deposition has been a serious environmental issue in southern China.Based on plotted simulated acid rain,the impact of acid deposition on the dynamics of main elements of subtropical forest soils,including exchangeable K+,Na+,Ca2+,Mg2+,and Al3+,along with their relationship to the soil pH value was investigated.The results showed that the soil pH values(4.2) increased with the soil depths.Significant negative correlation was found between soil pH value and soil exchangeable cations,except for K+and Na+in pine coniferous forest soil.The soil element contents of the three different forest types had the similar order Al3+H+Ca2+Mg2+K+,Na+,with the surface soil layers having the highest element contents.The soil Al3+ mobilization occurred in mixed forest and monsoon evergreen broad-leaved forest ecosystems.The maximum concentration of K+and Mg2+were 0.74 mmol kg-1and 0.79 mmol kg-1respectively,suggesting a possible scarcity of these elements in subtropical forest soil.

Dilution and the Elusive Baseline

Knowledge of baseline conditions is critical for evaluating quantitatively the effect of human activities on environmental conditions, such as the impact of acid deposition. Efforts to restore ecosystems to prior, "pristine" condition require restoration targets, often based on some presumed or unknown baseline condition. Here, we show that rapid and relentless dilution of surface water chemistry is occurring in the White Mountains of New Hampshire, following decades of acid deposition. Extrapolating measured linear trends using a unique data set of up to 47 years, suggest that both precipitation and streamwater chemistry (r(2) >0.84 since 1985) in the Hubbard Brook Experimental Forest (HBEF) will approximate demineralized water within one to three decades. Because such dilute chemistry is unrealistic for surface waters, theoretical baseline compositions have been calculated for precipitation and streamwater: electrical conductivity of 3 and 5 μS/cm, base cation concentrations of 7 and 39 μeq/liter, acid-neutralizing capacity values of <1 and 14 μeq/liter, respectively; and pH 5.5 for both. Significantly large and rapid dilution of surface waters to values even more dilute than proposed for Pre-Industrial Revolution (PIR) conditions has important ecological, biogeochemical and water resource management implications, such as for the success of early reproductive stages of aquatic organisms.

Impacts of acid deposition at Plastic Lake: forecasting chemical recovery using a Bayesian calibration and uncertainty propagation approach

Given the importance of models in the development of environmental polices it is necessary to assess the uncertainty introduced by model parameterisation and its impact on predictions. In the current study, an uncertainty framework designed to perform automated calibrations and developed for use with the Model of Acidification of Groundwater in Catchments (MAGIC) was applied to Plastic Lake, a long-term study site in Southern Ontario, Canada. The primary objectives were to investigate the chemical response of soil and surface water at Plastic Lake to proposed acid (sulfur and nitrogen) emissions and assess the use of the framework at a regional level. Despite the relatively high amount of uncertainty associated with many of the model parameters, calibration resulted in relatively narrow parameter convergence. The importance of time-series stream data was clearly evident, with uncertainty decreasing with more observation years. The forecast improvements in stream Acid Neutralizing Capacity at Plastic Lake from–40 μeq/L in 1988 to 14 μeq/L in 2060 had 5 and 95% confidence bounds of–3 and 29 μeq/L, respectively. Despite the limited availability of soil chemical data in Ontario, the approach applied at Plastic Lake is viable on a regional basis given the abundance of water chemistry data.

Application of the simplified biogeochemical process (SIMPLB) model to determine the impact of acidic deposition on a Japanese cedar forest soil

The simplified biogeochemical process model (SIMPLB model) for determination of the impact of acidic deposition was applied to a Japanese cedar forest at Mt. Myougi in Gunma Pref. in central Japan. This dynamic model characterizes the biogeochemical processes of net nutrient cycling as the reduction ratio, K(RED), which is the ratio of the return by mineralization of litterfall to the root uptake of nutrients. The SIMPLB model estimates these biogeochemical processes from the nitrate concentration of the soil solution, without it being necessary to measure other biogeochemical parameters. About 1 year of observed data and values simulated by the model on the basis of soil data measured at the application site were compared to evaluate the SIMPLB model. The results showed that the SIMPLB model can use the yearly average K(RED) value for the long-term prediction of soil acidification. At the study site, the forest trees are about 38 years old, and the soil, an Andosol, is a black soil common in Japan. The SIMPLB model predicted soil chemistry changes until 2035 according to a deposition scenario.

The impact of acid deposition and forest harvesting on lakes and their forested catchments in south central Ontario: a critical loads approach

Abstract. The impact of acid deposition and tree harvesting on three lakes and their representative sub-catchments in the Muskoka-Haliburton region of south-central Ontario was assessed using a critical loads approach. As nitrogen dynamics in forest soils are complex and poorly understood, for simplicity and to allow comparison among lakes and their catchments, CLs (A) for both lakes and forest soils were calculated assuming that nitrate leaching from catchments will not change over time (i.e. a best case scenario). In addition, because soils in the region are shallow, base cation weathering rates for the representative sub-catchments were calculated for the entire soil profile and these estimates were also used to calculate critical loads for the lakes. These results were compared with critical loads obtained by the Steady State Water Chemistry (SSWC) model. Using the SSWC model, critical loads for lakes were between 7 and 19 meq m-2yr-1 higher than those obtained from soil measurements. Lakes and forests are much more sensitive to acid deposition if forests are harvested, but two acid-sensitive lakes had much lower critical loads than their respective forested sub-catchments implying that acceptable acid deposition levels should be dictated by the most acid-sensitive lakes in the region. Under conditions that assume harvesting, the CL (A) is exceeded at two of the three lakes and five of the six sub-catchments assessed in this study. However, sulphate export from catchments greatly exceeds input in bulk deposition and, to prevent lakes from falling below the critical chemical limit, sulphate inputs to lakes must be reduced by between 37% and 92% if forests are harvested. Similarly, sulphate leaching from forested catchments that are harvested must be reduced by between 16 and 79% to prevent the ANC of water draining the rooting zone from falling below 0 μeq l-1. These calculations assume that extremely low calcium leaching losses (9–27 μeq l-1) from forest soils can be maintained without any decrease in forest productivity. Calcium concentrations in the three lakes have decreased by between ∼10 and 25% over the past 20 years and calculations assume that calcium concentrations in lakes can fall to around 30% of their current values without any harmful effects on biota. Both these assumptions require urgent investigation. Keywords: acid deposition, calcium, critical loads, forests, harvesting, lakes

A Comparison of Loch Chemistry from 1955 and 1999 in the Cairngorms, N.E. Scotland

The Cairngorms in north-east Scotland is remote from pollutant sources although it currently receives ca. 10 kg ha1 yr1 S and ca. 11 kg ha1 yr1 N deposition from the atmosphere.In 1955, 15 lochs (lakes) at a range of altitudes were sampled and analysed for major ion concentrations. A new survey of these and an additional 23 lochs and their catchment soils was conducted in 1999 to determine the impact of acid deposition, and the changes in loch chemistry since the 1955 survey. The bedrock geology of this region has a strong influence on the loch chemistry. Surface waters were generally more acidic in high altitude areas due to predominantly poorly buffered, thin alpine soils developed on granitic parent material (mean acid neutralising capacity (ANC) for 23 lochs = 30 μeq L1). At lower altitudes where the geology is dominated by Dalradian metamorphic rocks surface waters are comparatively base rich and have higher ANC (mean ANC for 15 lochs = 157 μeq L1). Surface water nitrate concentrations show a negative relationship with soil C:N status, in that higher nitrate only occurs at low soil C:N ratios. A comparison of data for 1955 and 1999 shows that sulphate concentrations are significantly lower (67.8 and 47.5 μeq L1, respectively), and pH has improved (pH 5.6 and 5.9) in response to decreased S deposition since the mid 1970s. However, mean nitrate concentrations were found to increase from 2.48 μ>eq L1 in 1955 to 5.65 μeq L1 in 1999. Differences in the sampling and laboratory methods from 1955 and 1999 are acknowledged in the interpretation of data.

The Importance of Calcium Deposition in Assessing Impacts of Acid Deposition in China

The extensive use of coal as an energy carrier in China has led to high deposition of sulfur in a large part of the country. In the southern part of China large areas receive acid deposition, while in the northern part of the country the acidity of the emissions is neutralized by alkaline dust from the desert areas. In this paper we demonstrate the importance of knowing the sources and deposition patterns of base cations when assessing the effects of changes in sulfur emissions. Regional-scale data of both sulfur and calcium deposition from modeling and monitoring are combined in order to demonstrate how the acidity of deposition in China has changed historically and may change in the future. The importance of base cation deposition is also demonstrated using the dynamic acidification model MAGIC with input data from an intensive monitoring site outside Guiyang. It is not known what fraction of the deposited base cations is of natural origin and anthropogenic origin, respectively. The relative source strength varies greatly between regions. Future effects of emission changes are highly dependent on the relative reduction in sulfur and base cation emissions.

Soil Acidification in Loess and Clay Soils in The Netherlands

To assess the impact of acid deposition on forested loess and clay soils in the Netherlands, changes in base saturation and soil solution concentrations were simulated with the dynamic soil acidification model ReSAM for 38 loess soils and 16 clay soils. The selected locations represent the range in geographical position and diversity in parent material occurring in forested loess and clay soils in the Netherlands. Two deposition scenarios were used for the period 1992-2050: a business as usual scenario (BAU) and a scenario in which deposition was reduced according to present Dutch policy plans (MV-3). A comparison of simulated and measured soil solution concentrations and base saturation in 1992/1993 showed that the model simulated concentrations and base saturation in the loess soils quite good. However, the model tended to overestimate acidification in the top (0-10 cm) of the clay soils. Despite the reasonable agreement between measured and simulated data some uncertainty in the validity of the model predictions remains because time trends to validate the model were not available. The model predicted a small but ongoing acidification during the BAU scenario in the loess soils as indicated by a decline in median base saturation and pH in the topsoil in 2050. Present policy plans (MV-3) lead to a slight recovery of the base saturation in 2050 and a decline in Al concentrations. In the clay soils a strong decline in base saturation is simulated in the topsoil, whereas an increase in base saturation is predicted for the subsoil.

Modelling impacts of atmospheric deposition, nutrient cycling and soil weathering on the sustainability of nine forest ecosystems

To assess the impact of acid deposition on the long-term sustainability of nine oak, pine and spruce stands on sandy to loamy sandy parent material in Sweden, Denmark and The Netherlands, a dynamic soil acidification model (ReSAM) was applied. Two deposition scenarios for the period 1990–2090 were used: a business as usual scenario (BAU) and a restrictive critical load scenario (CL). The BAU scenario leads to a strong decrease in both Al concentrations and pH in the topsoil of the Dutch and the Danish sites due to a decrease in the amount of amorphous Al compounds. The decline in pH leads to an enhanced release of base cations by silicate weathering. Despite the ongoing acidification, base saturation increases during the simulation period, due to both the increase in base cation weathering and an increased input from mineralization with the ageing of the tree stands. No change in Al concentration is predicted for northern Sweden as deposition levels are below critical loads. Soil chemistry at the recently replanted Swedish sites is dominated by changes in N cycling instead of by deposition. The CL scenario leads, especially after 2010, to a stronger decline in Al concentration compared with the BAU scenario, which is mainly caused by a reduction of the acid input. Up to 2010, a considerable acid input to the soil system is maintained as N supply is larger than the consumption of N by the trees. Despite the reduction of the deposition of S and N to critical loads, the readily available cation pools are still declining on the Danish and Dutch sites in 2090. It is concluded that deposition levels above critical loads lead to exhaustion of the pool of amorphous Al compounds and a decline in pH. Base saturation does not decline due to an increase in mineralization with stand age and an increase in weathering rate due to the decline in pH.

Determination of mineral surface area in relation to the calculation of weathering rates

The release of base cations by the weathering of soil minerals provides the primary buffer against the detrimental impact of acid deposition on the soil. The rate of release of base cations will be governed by mineral composition and the exposed surface area of mineral grains. In theory it is possible to calculate the surface area of a mixture of grains on the basis of particle size and geometry. An alternative is the use of correlations. It has been suggested (Sverdrup et al. 1990, Nordic Council of Ministers 98) that mineral surface area can be related to soil particle size distribution via a simple empirical equation. This contribution compares the surface areas of soils as calculated by geometric equations and Sverdrup's equation with actual BET measurements. The equations tested do not appear to be applicable to the soils used in the current work. Modified versions of the equation suggested by Sverdrup, applied to subsets of our data, based on sites and soil types, yield better results for the soils used in the current work. Statistically significant improved fits are obtained when soil mineralogy as well as soil texture is taken into account.

The prediction and management of water quality in a relatively unpolluted major Scottish catchment: current issues and experimental approaches

The potential impacts of diffuse pollution from atmospheric deposition and land use on the water quantity and quality of the river Dee in N.E. Scotland are currently being assessed. The importance of headwater regions for supplying a large proportion of catchment runoff with water of a high quality is clearly demonstrated. However, the quality of this water is threatened by the impact of acid deposition in a number of sub-catchments. In some of the more agriculturally developed lowland sub-catchments, there are increasing levels of nitrogen runoff. The catchment attributes, together with hydrochemical data, are being considered in terms of an ongoing research programme established to predict the impact of future environmental and land-use change scenarios.

Interactions between the Encelia leaf beetle and its host plant, Encelia farinosa: The influence of acidic fog on insect growth and plant chemistry

The impact of acidic deposition on interactions between the plant Encelia farinosa and the herbivorous beetle Trirhabda geminata (Chrysomelidae) was determined under greenhouse conditions. Acidic fogs (pH 2.75) did not significantly affect the overall foliar concentrations of water or soluble protein as compared with control fogs (pH 5.6). Nonetheless, E. farinosa foliage was altered by exposure to three 3-h acidic fogs such that growth and biomass gain by T. geminata increased by more than 30% as compared to beetles feeding on control-fogged plants. Thus, previous indications that changes in soluble proteins or water content were responsible for increased biomass gain and growth of T. geminata cannot be substantiated by this study. Additionally, changes in the plant defensive chemistry were not responsible for increased herbivore growth, as farinosin, encecalin, and euparin foliar concentrations did not vary significantly between fog treatments. Significant increases in CO 2 assimilation rates of E. farinosa exposed to acidic fogs were documented at 3, 7, and 21 days following treatment, suggesting that carbohydrate-based products of increased plant metabolism may have played a role (e.g. soluble carbohydrates). However, the key factors responsible for increasing herbivore performance on acidic-fogged E. farinosa remain largely unknown.

Effects of rhizobium, arbuscular mycorrhizal fungi and anion content of simulated rain on subterranean clover

An experiment was conducted to determine the extent to which rhizobia, mycorrhizal fungi, and anions in simulated rain affect plant growth response to acid deposition. Germinating subterranean clover seeds were planted in steam-pasteurized soil in pots and inoculated with Rhizobium leguminosarum, Glomus intraradices, Glomus etunicatum, R. leguminosarum + G. intraradices, R. leguminosarum + G. etunicatum, or no microbial symbionts. Beginning 3 weeks later, plants and the soil surface were exposed to simulated rain in a greenhouse on 3 days week −1 for 12 weeks. Rain solutions were deionized water amended with background ions only (pH 5.0) or also adjusted to pH 3.0 with HNO 3 only, H 2SO 4 only, or a 50/50 mixture of the two acids. Glomus intraradices colonized plant roots poorly, and G. intraradices-inoculated plants responded like nonmycorrhizal plants to rhizobia and rain treatments. Variation in plant biomass attributable to different rain formulations was strongest for G. etunicatum-inoculated plants, and the effect of rain formulation differed with respect to nodulation by rhizobia. The smallest plants at the end of the experiment were noninoculated plants exposed to rains (0.38 g mean dry weight total for 3 plants pot −1). Among nonnodulated plants infected by G. etunicatum, those exposed to HNO 3 rain were largest, followed by plants exposed to HNO 3 + H 2SO 4, pH 5.0, and H 2SO 4 rain, in that order. Among plants inoculated with both R. leguminosarum + G. etunicatum, however, the greatest biomass occurred with pH 5.0 rains, resulting in the largest plants in the study (1.00 g/3 plants). Treatment-related variation among root and shoot biomass data reflected those for whole-plant biomass. Based on quantification of biomass and N concentrations in shoot and root tissues, total N content of plants inoculated with G. etunicatum alone and exposed to the HNO 3 + H 2SO 4 rains was approximately the same as plants inoculated with R. leguminosarum + G. entunicatum and exposed to pH 5 rains. Thus, the acid-mixture rains and rhizobia under no acid deposition provided approximately equal amounts of N in biomass. The significant interactions among rain formulation and the symbiotic status of the plants suggest that conclusions concerning the impact of acid deposition on plants in the environment cannot be considered reliable because most experiments on which such assessments are based have not tested confounding influences of microorganisms and precipitation characteristics.

A palaeolimnological assessment of the impact of acid deposition on surface waters in North-West Scotland, a region of high sea-salt inputs

Recent critical loads assessments suggest that sensitive surface waters in the north-west of Scotland have acidified, whereas earlier surveys indicate little chemical or biological evidence of acidification. It has been suggested that regionally high sea-salt inputs are affecting either critical loads calculations or the susceptibility of surface waters to acidification. We use palaeolimnological techniques to test the hypothesis that the critical load exceedances in north-west Scotland are real. Pre-industrial and present day loch-water pH are inferred from diatom assemblages in sediment cores from 21 lochs in order to estimate recent pH change. The results indicate consistent post-1800 declines in loch-water pH, although the magnitude of this decline is small (<0.4 pH unit) and in most cases within the error of the technique. It is concluded that although slight acidification might have taken place, this has not been of sufficient magnitude to significantly effect most biological communities (e.g. higher plants, invertebrates and fish).