Astrid Berg - Academia.edu (original) (raw)

Papers by Astrid Berg

Research paper thumbnail of Children's emergent mechanistic reasoning in chemistry: A case study about early primary students’ reasoning about the phenomenon of thermal expansion of air

Chemistry Education Research and Practice

The importance of introducing students to mechanistic reasoning (MR) early in their schooling is ... more The importance of introducing students to mechanistic reasoning (MR) early in their schooling is emphasised in research. The goal of this case study was to contribute with knowledge on how...

Research paper thumbnail of Vilket kemiinnehåll görs tillgängligt i finlandssvenska och svenska klassrum? Kemitexter som redskap för naturvetenskapligt lärande

Resultatdialog 2010 Aktuell Forskning Om Utbildning Och Larande, 2010

Vilket kemiinnehall gors tillgangligt i finlandssvenska och svenska klassrum? : kemitexter som re... more Vilket kemiinnehall gors tillgangligt i finlandssvenska och svenska klassrum? : kemitexter som redskap for naturvetenskapligt larande

Research paper thumbnail of Learning to “see” chemical reactions in classroom laboratory activities

Science Education, 2013

The issue of this article is what chemistry specific seeing is made available for students to dev... more The issue of this article is what chemistry specific seeing is made available for students to develop during laboratory activities. Using a sociocultural perspective seeing is understood as a culturally developed ability - what is possible for us to see depends on what tools we master in a specific practice. Language is considered to be the most powerful mediating tool. In this study, we analyse what chemistry specific seeing is mediated to students during a session of experiments. As an analytical tool we use a dual-pronged model: general – specific aspects and macro level – sub-micro level. The results indicate that the “seeing” that is mediated to the students tends to involve only specific aspects at macro level. During the review of the experiments the specific aspects on sub-micro level were given little attention, but with no clear reference to the observations the students did during the practical work. Consequently, the students were given little guidance towards a scientif...

Research paper thumbnail of Med filmen som redskap - ett projekt med syfte att utveckla den naturvetenskapliga laborationen

Venue

När studenterna får tid att resonera kring de naturvetenskapliga fenomen de observerar i laborati... more När studenterna får tid att resonera kring de naturvetenskapliga fenomen de observerar i laborationerna med sin lärare kan de lättare utveckla sitt eget naturvetenskapliga ”seende”. Att laborationerna filmades underlättade en gemensam diskussion vid ett senare tillfälle. Det var några av slutsatserna av ett projekt på Grundlärarprogrammet.

Research paper thumbnail of The response of soil weathering to climate change

Research paper thumbnail of Anorthite Surface Speciation and Weathering Reactivity in Bicarbonate Solutions at 25°C

Carbon Dioxide Chemistry, 1994

ABSTRACT We studied the kinetics of anorthite dissolution in bicarbonate solutions under constant... more ABSTRACT We studied the kinetics of anorthite dissolution in bicarbonate solutions under constant pCO 2 at 25° using laboratory flow-through reactors. Anorthite weathering is accelerated in the presence of bicarbonate at near-neutral pH. Formation of reactive surface Al-carbonate complexes can explain increased aluminium release rates. Silicon release was faster than Al release. This non-stochiometric dissolution can result in formation of a Si-depleted reactive surface layer. Silicon release is apparently diffusion-controlled through this reactive layer as demonstrated by a square root dependence of dissolution rate with time. We estimate the time it takes for the reactive layer to reach constant thickness, and thereby stoichiometric dissolution of anorthite, to be on the order of a few years. The results of this study suggest that dissolved inorganic carbon species, which are dominant anions in many natural waters, can contribute to weathering reactions at near-neutral pH regions. If silicate weathering is kinetically controlled in natural systems, laboratory studies should focus on the rate of release for the slowest dissolving mineral component, as this will better approximate weathering rates over longer time scales.

Research paper thumbnail of Process-based modeling of silicate mineral weathering responses to increasing atmospheric CO 2 and climate change

Global Biogeochemical Cycles, 2009

A mathematical model describes silicate mineral weathering processes in modern soils located in t... more A mathematical model describes silicate mineral weathering processes in modern soils located in the boreal coniferous region of northern Europe. The process model results demonstrate a stabilizing biological feedback mechanism between atmospheric CO 2 levels and silicate weathering rates as is generally postulated for atmospheric evolution. The process model feedback response agrees within a factor of 2 of that calculated by a weathering feedback function of the type generally employed in global geochemical carbon cycle models of the Earth's Phanerozoic CO 2 history. Sensitivity analysis of parameter values in the process model provides insight into the key mechanisms that influence the strength of the biological feedback to weathering. First, the process model accounts for the alkalinity released by weathering, whereby its acceleration stabilizes pH at values that are higher than expected. Although the process model yields faster weathering with increasing temperature, because of activation energy effects on mineral dissolution kinetics at warmer temperature, the mineral dissolution rate laws utilized in the process model also result in lower dissolution rates at higher pH values. Hence, as dissolution rates increase under warmer conditions, more alkalinity is released by the weathering reaction, helping maintain higher pH values thus stabilizing the weathering rate. Second, the process model yields a relatively low sensitivity of soil pH to increasing plant productivity. This is due to more rapid decomposition of dissolved organic carbon (DOC) under warmer conditions. Because DOC fluxes strongly influence the soil water proton balance and pH, this increased decomposition rate dampens the feedback between productivity and weathering. The process model is most sensitive to parameters reflecting soil structure; depth, porosity, and water content. This suggests that the role of biota to influence these characteristics of the weathering profile is as important, if not more important, than the role of biota to influence mineral dissolution rates through changes in soil water chemistry. This process-modeling approach to quantify the biological weathering feedback to atmospheric CO 2 demonstrates the potential for a far more mechanistic description of weathering feedback in simulations of the global geochemical carbon cycle.

Research paper thumbnail of Carbon dioxide mediated dissolution of Ca-feldspar: implications for silicate weathering

Chemical Geology, 2000

... The white-colored separate was immersed briefly in distilled water to eliminate the greatest ... more ... The white-colored separate was immersed briefly in distilled water to eliminate the greatest part of any fine dust remaining from the grinding procedure, then rinsed three times in succession with sonification in ethanol for 3–5 min each time, and with decanting and replacement ...

Research paper thumbnail of Carbon dioxide mediated dissolution of Ca-feldspar: implications for silicate weathering

Chemical Geology, 2000

... The white-colored separate was immersed briefly in distilled water to eliminate the greatest ... more ... The white-colored separate was immersed briefly in distilled water to eliminate the greatest part of any fine dust remaining from the grinding procedure, then rinsed three times in succession with sonification in ethanol for 3–5 min each time, and with decanting and replacement ...

Research paper thumbnail of Process‐based modeling of silicate mineral weathering responses to increasing atmospheric CO2 and climate change

A mathematical model describes silicate mineral weathering processes in modern soils located in t... more A mathematical model describes silicate mineral weathering processes in modern soils located in the boreal coniferous region of northern Europe. The process model results demonstrate a stabilizing biological feedback mechanism between atmospheric CO 2 levels and silicate weathering rates as is generally postulated for atmospheric evolution. The process model feedback response agrees within a factor of 2 of that calculated by a weathering feedback function of the type generally employed in global geochemical carbon cycle models of the Earth's Phanerozoic CO 2 history. Sensitivity analysis of parameter values in the process model provides insight into the key mechanisms that influence the strength of the biological feedback to weathering. First, the process model accounts for the alkalinity released by weathering, whereby its acceleration stabilizes pH at values that are higher than expected. Although the process model yields faster weathering with increasing temperature, because of activation energy effects on mineral dissolution kinetics at warmer temperature, the mineral dissolution rate laws utilized in the process model also result in lower dissolution rates at higher pH values. Hence, as dissolution rates increase under warmer conditions, more alkalinity is released by the weathering reaction, helping maintain higher pH values thus stabilizing the weathering rate. Second, the process model yields a relatively low sensitivity of soil pH to increasing plant productivity. This is due to more rapid decomposition of dissolved organic carbon (DOC) under warmer conditions. Because DOC fluxes strongly influence the soil water proton balance and pH, this increased decomposition rate dampens the feedback between productivity and weathering. The process model is most sensitive to parameters reflecting soil structure; depth, porosity, and water content. This suggests that the role of biota to influence these characteristics of the weathering profile is as important, if not more important, than the role of biota to influence mineral dissolution rates through changes in soil water chemistry. This process-modeling approach to quantify the biological weathering feedback to atmospheric CO 2 demonstrates the potential for a far more mechanistic description of weathering feedback in simulations of the global geochemical carbon cycle.

Research paper thumbnail of Observationer i kemiklassrummet - att lära sig se kemiska reaktioner

I flera jamforande internationella studier hamnar de finska eleverna i toppen. Hur bedrivs kemiun... more I flera jamforande internationella studier hamnar de finska eleverna i toppen. Hur bedrivs kemiundervisningen i finlandssvenska klassrum? Rapporten bestar av sex kapitel dar forfattarna bl.a. tar u ...

Research paper thumbnail of Representational challenges in animated chemistry: Self-generated animations as a means to encourage students’ reflections on sub-micro processes in laboratory exercises

Chemistry Education Research and Practice

A central aspect of learning chemistry is learning to relate observations of phenomena to models ... more A central aspect of learning chemistry is learning to relate observations of phenomena to models of the sub-microscopic level of matter, and hence being able to explain the observable. However,...

Research paper thumbnail of Kemiinnehåll i undervisningen för nybörjare. En studie av hur ämnesinnehållet får konkurrera med målet att få eleverna intresserade av naturvetenskap

NorDiNa, 2007

This study describes the dilemma of making science interesting on the one hand, and to introduce ... more This study describes the dilemma of making science interesting on the one hand, and to introduce students into a scientific teaching practise on the other in a laboratory based teaching practise. The study was conducted in a grade four class in Swedish ...

Research paper thumbnail of Lärobok och kemipraktik

Research paper thumbnail of Learning to “see” chemical reactions in classroom laboratory activities

Research paper thumbnail of Jämförelse mellan svenska och finlandssvenskaelevers prestationer i ett för- och eftertest

Research paper thumbnail of Observationer i kemiklassrummet – en studie om att lära sig se kemiska reaktioner : en studie om att lära sig se kemiska reaktioner

Research paper thumbnail of Kemiinnehåll i undervisningen för nybörjare. En studie av hur ämnesinnehållet får konkurrera med målet att få eleverna intresserade av naturvetenskap

Nordina Nordic Studies in Science Education, 2007

Laborationsbaserad undervisning framställs som ett sätt att introducera naturvetenskap samt väcka... more Laborationsbaserad undervisning framställs som ett sätt att introducera naturvetenskap samt väcka elevers intresse för ämnet . Detta kan ses mot bakgrund av att elevers attityder till, och intresse för, naturvetenskap uppfattas som något som formas tidigt (se t.ex.

Research paper thumbnail of Observationer i kemiklassrummet - att lära sig se kemiska reaktioner

Research paper thumbnail of Vilket kemiinnehåll görs tillgängligt i finlandssvenska och svenska klassrum? Kemitexter som redskap för naturvetenskapligt lärande

Resultatdialog 2010 Aktuell Forskning Om Utbildning Och Larande, 2010

Research paper thumbnail of Children's emergent mechanistic reasoning in chemistry: A case study about early primary students’ reasoning about the phenomenon of thermal expansion of air

Chemistry Education Research and Practice

The importance of introducing students to mechanistic reasoning (MR) early in their schooling is ... more The importance of introducing students to mechanistic reasoning (MR) early in their schooling is emphasised in research. The goal of this case study was to contribute with knowledge on how...

Research paper thumbnail of Vilket kemiinnehåll görs tillgängligt i finlandssvenska och svenska klassrum? Kemitexter som redskap för naturvetenskapligt lärande

Resultatdialog 2010 Aktuell Forskning Om Utbildning Och Larande, 2010

Vilket kemiinnehall gors tillgangligt i finlandssvenska och svenska klassrum? : kemitexter som re... more Vilket kemiinnehall gors tillgangligt i finlandssvenska och svenska klassrum? : kemitexter som redskap for naturvetenskapligt larande

Research paper thumbnail of Learning to “see” chemical reactions in classroom laboratory activities

Science Education, 2013

The issue of this article is what chemistry specific seeing is made available for students to dev... more The issue of this article is what chemistry specific seeing is made available for students to develop during laboratory activities. Using a sociocultural perspective seeing is understood as a culturally developed ability - what is possible for us to see depends on what tools we master in a specific practice. Language is considered to be the most powerful mediating tool. In this study, we analyse what chemistry specific seeing is mediated to students during a session of experiments. As an analytical tool we use a dual-pronged model: general – specific aspects and macro level – sub-micro level. The results indicate that the “seeing” that is mediated to the students tends to involve only specific aspects at macro level. During the review of the experiments the specific aspects on sub-micro level were given little attention, but with no clear reference to the observations the students did during the practical work. Consequently, the students were given little guidance towards a scientif...

Research paper thumbnail of Med filmen som redskap - ett projekt med syfte att utveckla den naturvetenskapliga laborationen

Venue

När studenterna får tid att resonera kring de naturvetenskapliga fenomen de observerar i laborati... more När studenterna får tid att resonera kring de naturvetenskapliga fenomen de observerar i laborationerna med sin lärare kan de lättare utveckla sitt eget naturvetenskapliga ”seende”. Att laborationerna filmades underlättade en gemensam diskussion vid ett senare tillfälle. Det var några av slutsatserna av ett projekt på Grundlärarprogrammet.

Research paper thumbnail of The response of soil weathering to climate change

Research paper thumbnail of Anorthite Surface Speciation and Weathering Reactivity in Bicarbonate Solutions at 25°C

Carbon Dioxide Chemistry, 1994

ABSTRACT We studied the kinetics of anorthite dissolution in bicarbonate solutions under constant... more ABSTRACT We studied the kinetics of anorthite dissolution in bicarbonate solutions under constant pCO 2 at 25° using laboratory flow-through reactors. Anorthite weathering is accelerated in the presence of bicarbonate at near-neutral pH. Formation of reactive surface Al-carbonate complexes can explain increased aluminium release rates. Silicon release was faster than Al release. This non-stochiometric dissolution can result in formation of a Si-depleted reactive surface layer. Silicon release is apparently diffusion-controlled through this reactive layer as demonstrated by a square root dependence of dissolution rate with time. We estimate the time it takes for the reactive layer to reach constant thickness, and thereby stoichiometric dissolution of anorthite, to be on the order of a few years. The results of this study suggest that dissolved inorganic carbon species, which are dominant anions in many natural waters, can contribute to weathering reactions at near-neutral pH regions. If silicate weathering is kinetically controlled in natural systems, laboratory studies should focus on the rate of release for the slowest dissolving mineral component, as this will better approximate weathering rates over longer time scales.

Research paper thumbnail of Process-based modeling of silicate mineral weathering responses to increasing atmospheric CO 2 and climate change

Global Biogeochemical Cycles, 2009

A mathematical model describes silicate mineral weathering processes in modern soils located in t... more A mathematical model describes silicate mineral weathering processes in modern soils located in the boreal coniferous region of northern Europe. The process model results demonstrate a stabilizing biological feedback mechanism between atmospheric CO 2 levels and silicate weathering rates as is generally postulated for atmospheric evolution. The process model feedback response agrees within a factor of 2 of that calculated by a weathering feedback function of the type generally employed in global geochemical carbon cycle models of the Earth's Phanerozoic CO 2 history. Sensitivity analysis of parameter values in the process model provides insight into the key mechanisms that influence the strength of the biological feedback to weathering. First, the process model accounts for the alkalinity released by weathering, whereby its acceleration stabilizes pH at values that are higher than expected. Although the process model yields faster weathering with increasing temperature, because of activation energy effects on mineral dissolution kinetics at warmer temperature, the mineral dissolution rate laws utilized in the process model also result in lower dissolution rates at higher pH values. Hence, as dissolution rates increase under warmer conditions, more alkalinity is released by the weathering reaction, helping maintain higher pH values thus stabilizing the weathering rate. Second, the process model yields a relatively low sensitivity of soil pH to increasing plant productivity. This is due to more rapid decomposition of dissolved organic carbon (DOC) under warmer conditions. Because DOC fluxes strongly influence the soil water proton balance and pH, this increased decomposition rate dampens the feedback between productivity and weathering. The process model is most sensitive to parameters reflecting soil structure; depth, porosity, and water content. This suggests that the role of biota to influence these characteristics of the weathering profile is as important, if not more important, than the role of biota to influence mineral dissolution rates through changes in soil water chemistry. This process-modeling approach to quantify the biological weathering feedback to atmospheric CO 2 demonstrates the potential for a far more mechanistic description of weathering feedback in simulations of the global geochemical carbon cycle.

Research paper thumbnail of Carbon dioxide mediated dissolution of Ca-feldspar: implications for silicate weathering

Chemical Geology, 2000

... The white-colored separate was immersed briefly in distilled water to eliminate the greatest ... more ... The white-colored separate was immersed briefly in distilled water to eliminate the greatest part of any fine dust remaining from the grinding procedure, then rinsed three times in succession with sonification in ethanol for 3–5 min each time, and with decanting and replacement ...

Research paper thumbnail of Carbon dioxide mediated dissolution of Ca-feldspar: implications for silicate weathering

Chemical Geology, 2000

... The white-colored separate was immersed briefly in distilled water to eliminate the greatest ... more ... The white-colored separate was immersed briefly in distilled water to eliminate the greatest part of any fine dust remaining from the grinding procedure, then rinsed three times in succession with sonification in ethanol for 3–5 min each time, and with decanting and replacement ...

Research paper thumbnail of Process‐based modeling of silicate mineral weathering responses to increasing atmospheric CO2 and climate change

A mathematical model describes silicate mineral weathering processes in modern soils located in t... more A mathematical model describes silicate mineral weathering processes in modern soils located in the boreal coniferous region of northern Europe. The process model results demonstrate a stabilizing biological feedback mechanism between atmospheric CO 2 levels and silicate weathering rates as is generally postulated for atmospheric evolution. The process model feedback response agrees within a factor of 2 of that calculated by a weathering feedback function of the type generally employed in global geochemical carbon cycle models of the Earth's Phanerozoic CO 2 history. Sensitivity analysis of parameter values in the process model provides insight into the key mechanisms that influence the strength of the biological feedback to weathering. First, the process model accounts for the alkalinity released by weathering, whereby its acceleration stabilizes pH at values that are higher than expected. Although the process model yields faster weathering with increasing temperature, because of activation energy effects on mineral dissolution kinetics at warmer temperature, the mineral dissolution rate laws utilized in the process model also result in lower dissolution rates at higher pH values. Hence, as dissolution rates increase under warmer conditions, more alkalinity is released by the weathering reaction, helping maintain higher pH values thus stabilizing the weathering rate. Second, the process model yields a relatively low sensitivity of soil pH to increasing plant productivity. This is due to more rapid decomposition of dissolved organic carbon (DOC) under warmer conditions. Because DOC fluxes strongly influence the soil water proton balance and pH, this increased decomposition rate dampens the feedback between productivity and weathering. The process model is most sensitive to parameters reflecting soil structure; depth, porosity, and water content. This suggests that the role of biota to influence these characteristics of the weathering profile is as important, if not more important, than the role of biota to influence mineral dissolution rates through changes in soil water chemistry. This process-modeling approach to quantify the biological weathering feedback to atmospheric CO 2 demonstrates the potential for a far more mechanistic description of weathering feedback in simulations of the global geochemical carbon cycle.

Research paper thumbnail of Observationer i kemiklassrummet - att lära sig se kemiska reaktioner

I flera jamforande internationella studier hamnar de finska eleverna i toppen. Hur bedrivs kemiun... more I flera jamforande internationella studier hamnar de finska eleverna i toppen. Hur bedrivs kemiundervisningen i finlandssvenska klassrum? Rapporten bestar av sex kapitel dar forfattarna bl.a. tar u ...

Research paper thumbnail of Representational challenges in animated chemistry: Self-generated animations as a means to encourage students’ reflections on sub-micro processes in laboratory exercises

Chemistry Education Research and Practice

A central aspect of learning chemistry is learning to relate observations of phenomena to models ... more A central aspect of learning chemistry is learning to relate observations of phenomena to models of the sub-microscopic level of matter, and hence being able to explain the observable. However,...

Research paper thumbnail of Kemiinnehåll i undervisningen för nybörjare. En studie av hur ämnesinnehållet får konkurrera med målet att få eleverna intresserade av naturvetenskap

NorDiNa, 2007

This study describes the dilemma of making science interesting on the one hand, and to introduce ... more This study describes the dilemma of making science interesting on the one hand, and to introduce students into a scientific teaching practise on the other in a laboratory based teaching practise. The study was conducted in a grade four class in Swedish ...

Research paper thumbnail of Lärobok och kemipraktik

Research paper thumbnail of Learning to “see” chemical reactions in classroom laboratory activities

Research paper thumbnail of Jämförelse mellan svenska och finlandssvenskaelevers prestationer i ett för- och eftertest

Research paper thumbnail of Observationer i kemiklassrummet – en studie om att lära sig se kemiska reaktioner : en studie om att lära sig se kemiska reaktioner

Research paper thumbnail of Kemiinnehåll i undervisningen för nybörjare. En studie av hur ämnesinnehållet får konkurrera med målet att få eleverna intresserade av naturvetenskap

Nordina Nordic Studies in Science Education, 2007

Laborationsbaserad undervisning framställs som ett sätt att introducera naturvetenskap samt väcka... more Laborationsbaserad undervisning framställs som ett sätt att introducera naturvetenskap samt väcka elevers intresse för ämnet . Detta kan ses mot bakgrund av att elevers attityder till, och intresse för, naturvetenskap uppfattas som något som formas tidigt (se t.ex.

Research paper thumbnail of Observationer i kemiklassrummet - att lära sig se kemiska reaktioner

Research paper thumbnail of Vilket kemiinnehåll görs tillgängligt i finlandssvenska och svenska klassrum? Kemitexter som redskap för naturvetenskapligt lärande

Resultatdialog 2010 Aktuell Forskning Om Utbildning Och Larande, 2010