Modelling the effects of acid deposition: refinements, adjustments and inclusion of nitrogen dynamics in the MAGIC model

Cosby, B. J.; Ferrier, Robert C.; Jenkins, Alan; Wright, Richard F.

doi:10.5194/hess-5-499-2001

Cited by 247 publications

(201 citation statements)

References 82 publications

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“…MAGIC is a dynamic model that uses mass balances and chemical equilibria to estimate element fluxes for different landscape units (recharge areas, discharge areas, streams, and lakes) and different soil horizons (organic and mineral soil) over time (Cosby et al 2001). Given the variability in catchment characteristics, it is possible to arrange compartments in the model to resemble a specific catchment.…”

Section: Methodsmentioning

confidence: 99%

“…The exact mathematical formulation of the model can be found elsewhere (Cosby et al 1985a, b;Cosby et al 2001). The parameterization and execution of MAGIC requires a large amount of data and ancillary assumptions, which have varying degrees of uncertainty.…”

Section: Methodsmentioning

confidence: 99%

“…For all the aqueous phases, the chemical equilibria can allow for the presence of a triprotic organic acid ) and Al binding as described by Cosby et al (2001). The Al binding constants in this study were calibrated against an existing triprotic analog model assuming different acid analogs but the same relative binding of Al as a function of pH.…”

Section: Soil Physical and Chemical Parametersmentioning

confidence: 99%

“…While this ''weathering feedback'' is implemented in the MAGIC model (Cosby et al 2001), it is not used when calculating the acidity status of surface waters (F. Moldan IVL pers. com.).…”

Section: Calculated Changes In Bc Pools and Bc Release Ratesmentioning

confidence: 99%

“…Assuming equilibrium with gibbsite when running MAGIC at sites with high organic acidity in combination with a natural low pH (such as may be encountered in many headwater forest streams and mires) would lead to significant systematic errors if a secondary phase is not actually present. Cosby et al (2001) have commented that the solubility product constant may be implemented in the MAGIC model as an aggregated value of both ion exchange and solubility. Wright and Cosby (2003) have remarked that the choice of solubility product constant of the Al(OH) 3 phase has a significant effect on runoff chemistry.…”

Section: The Effect Of Modeled Aluminum Fluxes On Surface Water Ph Anmentioning

confidence: 99%

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Assessment of Uncertainty in Long-Term Mass Balances for Acidification Assessments: A MAGIC Model Exercise

Köhler¹,

Zetterberg

Bishop³

et al. 2011

AMBIO

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Long-term (1860-2010) catchment mass balance calculations rely on models and assumptions which are sources of uncertainty in acidification assessments. In this article, we report on an application of MAGIC to model acidification at the four Swedish IM forested catchments that have been subject to differing degrees of acidification stress. Uncertainties in the modeled mass balances were mainly associated with the deposition scenario and assumptions about sulfate adsorption and soil mass. Estimated base cation (BC) release rates (weathering) varied in a relatively narrow range of 47-62 or 42-47 meq m -2 year -1 , depending on assumptions made about soil cation exchange capacity and base saturation. By varying aluminum solubility or introducing a dynamic weathering feedback that allowed BC release to increase at more acidic pHs, a systematic effect on predicted changes in acid neutralizing capacity (DANC ca. 10-41 leq l -1 ) and pH (ca. DpH = 0.1-0.6) at all sites was observed. More robust projections of future changes in pH and ANC are dependent on reducing uncertainties in BC release rates, the timing, and extent of natural acidification through BC uptake by plants, temporal changes in soil element pools, and fluxes of Al between compartments.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Soil Physical and Chemical Parametersmentioning

confidence: 99%

“…While this ''weathering feedback'' is implemented in the MAGIC model (Cosby et al 2001), it is not used when calculating the acidity status of surface waters (F. Moldan IVL pers. com.).…”

Section: Calculated Changes In Bc Pools and Bc Release Ratesmentioning

confidence: 99%

Section: The Effect Of Modeled Aluminum Fluxes On Surface Water Ph Anmentioning

confidence: 99%

See 3 more Smart Citations

Assessment of Uncertainty in Long-Term Mass Balances for Acidification Assessments: A MAGIC Model Exercise

Köhler¹,

Zetterberg

Bishop³

et al. 2011

AMBIO

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Acidic Deposition: Sources and Effects

Driscoll

Fallon‐Lambert²,

Chen

2005

Encyclopedia of Hydrological Sciences

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Acidic deposition delivers acids and acidifying compounds to the Earth's surface, which are then transported through soil, vegetation, and surface waters and, in turn, set off a cascade of adverse ecological effects. Acidic deposition has altered forest soil by accelerating the leaching of available base cations, enhancing the accumulation of sulfur and nitrogen, and increasing the concentration of dissolved inorganic aluminum in soil waters. Soils that are compromised by acidic deposition are less able to neutralize additional amounts of acidic deposition, and provide poorer growing conditions for plants. Acidic deposition has impaired the surface water quality by lowering pH, decreasing acid‐neutralizing capacity ( ANC ), and increasing concentrations of dissolved inorganic aluminum. These changes have reduced the species diversity and abundance of aquatic life. Regulatory controls initiated in Europe and North America over the last three decades have decreased emissions of sulfur dioxide and to a lesser extent nitrogen oxides. Emission reductions have resulted in widespread decreases in concentrations of sulfate in surface waters, with some waters showing an increase in ANC. Given the loss of acid‐neutralizing base cations and the accumulation of sulfur and nitrogen in soil, many ecosystems have become more sensitive to additional acidic deposition and recovery will likely be delayed. Long‐term research shows that deeper emissions cuts will lead to greater and faster recovery from acidic deposition in impacted regions.

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