Predicting sulphate adsorption/desorption in forest soils: Evaluation of an extended Freundlich equation

Gustafsson, Jon Petter; Akram, Muhammad; Tiberg, Charlotta

doi:10.1016/j.chemosphere.2014.05.067

Cited by 48 publications

(30 citation statements)

References 24 publications

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“…Results section), a second model (B) was introduced, which also considered Al−H exchange. To consider the organic anion charge from dissolved organic carbon (DOC), the triprotic acid model of Hruška et al (2003) was used. Further, Eq.…”

Section: The Models -Brief Description and Initializationmentioning

confidence: 99%

Aluminium and base cation chemistry in dynamic acidification models – need for a reappraisal?

Gustafsson

Belyazid

McGivney

et al. 2018

SOIL

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Abstract. Long-term simulations of the water composition in acid forest soils require that accurate descriptions of aluminium and base cation chemistry are used. Both weathering rates and soil nutrient availability depend on the concentrations of Al3+, of H+, and of base cations (Ca2+, Mg2+, Na+, and K+) . Assessments of the acidification status and base cation availability will depend on the model being used. Here we review in what ways different dynamic soil chemistry models describe the processes governing aluminium and base cation concentrations in the soil water. Furthermore, scenario simulations with the HD-MINTEQ model are used to illustrate the difference between model approaches. The results show that all investigated models provide the same type of response to changes in input water chemistry. Still, for base cations we show that the differences in the magnitude of the response may be considerable depending on whether a cation-exchange equation (Gaines–Thomas, Gapon) or an organic complexation model is used. The former approach, which is used in many currently used models (e.g. MAGIC, ForSAFE), causes stronger pH buffering over a relatively narrow pH range, as compared to state-of-the-art models relying on more advanced descriptions in which organic complexation is important (CHUM, HD-MINTEQ). As for aluminium, a “fixed” gibbsite constant, as used in MAGIC, SMART/VSD, and ForSAFE, leads to slightly more pH buffering than in the more advanced models that consider both organic complexation and Al(OH)3(s) precipitation, but in this case the effect is small. We conclude that the descriptions of acid–base chemistry and base cation binding in models such as MAGIC, SMART/VSD, and ForSAFE are only likely to work satisfactorily in a narrow pH range. If the pH varies greatly over time, the use of modern organic complexation models is preferred over cation-exchange equations.

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Section: The Models -Brief Description and Initializationmentioning

confidence: 99%

Aluminium and base cation chemistry in dynamic acidification models – need for a reappraisal?

Gustafsson

Belyazid

McGivney

et al. 2018

SOIL

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“…The model assumes that the equilibria for ferrihydrite and Al(OH)3 provide the upper limit for the solubility of Fe 3+ and Al 3+ in mineral soil horizons. Further, it uses an extended Freundlich model to simulate SO4 adsorption (Gustafsson et al, 2015). HD-MINTEQ does not simulate N chemistry; instead dissolved NH4 + and NO3 -in the different horizons are given as input data.…”

Section: Hd-minteqmentioning

confidence: 99%

“…The extent of sulfate adsorption in the B1 horizon of Kindla was assumed to be strongly sorbing ("strong" in Table 1), similar to that of another Podzol in the same area of Sweden (Gustafsson et al, 15 2015). The other two soils from south-western Sweden were assumed to have less (Table 1) sulfate adsorption in agreement with other soils from this area (Karltun, 1995); the relevant Freundlich parameters were taken from the Tärnsjö soil of Gustafsson et al (2015). The mineral soil horizons were assumed to be in equilibrium with ferrihydrite, whereas Fe(III) was assumed to be negligible in the O horizons.…”

Section: Model Setupmentioning

confidence: 99%

Assessing the impact of acid rain and forest harvest intensity with the HD-MINTEQ model – Soil chemistry of three Swedish conifer sites from 1880 to 2080

McGivney¹,

Belyazid²,

Zetterberg³

et al. 2018

Preprint

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Abstract. Forest soils are susceptible to anthropogenic acidification. In the past, acid rain was a major contributor to soil acidification, but now that atmospheric levels of S have dramatically declined, concern has shifted towards biomass-induced 20 acidification, i.e., decreasing soil solution pH due to tree growth and harvesting events that permanently remove base cations (BC) from forest stands. We use a novel dynamic model, HD-MINTEQ, to investigate the long-term impacts of two theoretical future harvesting scenarios in the year 2020, a conventional harvest (CH, which removes stems only) and a whole-tree harvest (WTH, which removes 100% of the above-ground biomass except for stumps), on soil chemistry and weathering rates at three different Swedish forest sites (Aneboda, Gårdsjön, and Kindla). Furthermore, acidification following the harvesting events is 25 compared to the historical acidification that took place during the 20 th century due to acid rain. Our results indicate that historical acidification due to acid rain had a larger impact on pore water chemistry and mineral weathering than tree growth and CH or WTH events, at least if nitrification remained at a low level. However, compared to a no-harvest scenario (NH), WTH and CH significantly impacted soil chemistry and weathering rates. Directly after a harvesting event (CH or WTH), the soil solution pH sharply increased for 5 to 10 years before slowly declining over the remainder of the simulation (until year 2Even though the pH values in the WTH and CH scenario decreased with time as compared to NH, they did not drop to the levels observed around the peak of historic acidification (1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990), indicating that the pH decrease due to tree growth and harvesting would be less impactful than that of historic atmospheric acidification. Weathering rates differed across locations and soil layers in response to historic acidification, but at several sites and layers, annual weathering rates decreased in tandem with decreasing pH, which is likely due to Al 3+ weathering brakes. Weathering rates after the harvesting scenarios in 2020 5 generally increased although the dynamics were quite different depending on the site and soil layer.

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“…HD-MINTEQ employs the Stockholm Humic Model (Gustafsson, 2001) to estimate the binding of base cations and aluminium to the soil solid phase. SO4 adsorption is considered using the extended Freundlich equation of Gustafsson et al (2015). Nitrogen chemistry is not explicitly simulated, instead the user supplies the concentration of dissolved NO3…”

Section: Aluminium and Base Cations In Chum-am And In Hd-minteqmentioning

confidence: 99%

“…• SO4 adsorption was considered using the Freundlich-based model of Gustafsson et al (2015). As no SO4 adsorption data were available for this soil, it was assumed that 'some' adsorption occurred in the B horizons, using the parameter values 20 for the Tärnsjö Bs soil studied by Gustafsson et al (2015).…”

mentioning

confidence: 99%

Aluminium and base cation chemistry in dynamic acidification models – need for a reappraisal?

Gustafsson¹,

Belyazid²,

McGivney³

et al. 2018

Preprint

Self Cite

View full text Add to dashboard Cite

Abstract. Long-term simulations of the water composition in acid forest soils require that accurate descriptions of aluminium and base cation chemistry are used. Both weathering rates and soil nutrient availability depend on the concentrations of Al 3+ ,of H+, and of base cations (Ca 2+ , Mg 2+ , Na + and K + ). Consequently, assessments of the acidification status and base cation 15 availability will depend on the model being used. Here we review in what ways different dynamic soil chemistry models describe the processes governing aluminium and base cation concentrations in the soil water. Furthermore, scenario simulations with the HD-MINTEQ are used to illustrate the difference between model approaches. The results show that all investigated models provide the same type of response to changes in input water chemistry. Still, for base cations we show that the differences in the magnitude of the response may be considerable depending on whether a cation-exchange equation 20 (Gaines-Thomas, Gapon) or an organic complexation model is used. The former approach, which is used in many currently used models (e.g. MAGIC, ForSAFE), causes stronger pH-buffering over a relatively narrow pH range, as compared to stateof-the-art models relying on more advanced descriptions in which organic complexation is important (CHUM, HD-MINTEQ).As for aluminium, a fixed gibbsite constant, as used in MAGIC and ForSAFE, leads to slightly more pH-buffering than in the more advanced models that consider both organic complexation and Al(OH)3(s) precipitation, but in this case the effect is 25 small. We conclude that the descriptions of acid-base chemistry and base cation binding in models such as MAGIC and ForSAFE are only likely to work satisfactorily in a narrow pH range. If the pH varies greatly over time, the use of modern organic complexation models is preferred over cation exchange equations.

show abstract

Predicting sulphate adsorption/desorption in forest soils: Evaluation of an extended Freundlich equation

Cited by 48 publications

References 24 publications

Aluminium and base cation chemistry in dynamic acidification models – need for a reappraisal?

Aluminium and base cation chemistry in dynamic acidification models – need for a reappraisal?

Assessing the impact of acid rain and forest harvest intensity with the HD-MINTEQ model – Soil chemistry of three Swedish conifer sites from 1880 to 2080

Aluminium and base cation chemistry in dynamic acidification models – need for a reappraisal?

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