Hypothesises Of Acidification Of Surface Waters Flashcards
Natural long-term acidification:
Basic cations are returned to the soil by
Leaching from leaves and natural decomp. The net effect is a gain of hydrogen ions in soil solution.
Natural long-term acidification:
Surface waters in upland areas acidify
Naturally over long periods of time due to changes in catchment soils and vegetation.
Natural long-term acidification:
Organic acids are
Released by decomp of plants, these dissociate and release hydrogen ions.
Natural long-term acidification:
This hypothesises predicts that a slow rate of
Acidification has taken place over the past 10’000 years since the retreat of the last ice sheets.
Changes in land use:
Recent acidification of lakes and streams has taken place as a
Result in changes in catchment management and land use over the last century.
Changes in land use:
Heathland regeneration - Acidification is due to the decline of upland agriculture.
A decrease in farming upland leads to a decrease in grazing pressure and a decline in the regular burning of upland grazing pasture.
Changes in land use:
Heathland regeneration - The result of this is a decline of grassland communities and the
Regeneration of heathland vegetation, which would increase the amount of acid organic material in the soil and release H+ ions into surface waters.
Changes in land use:
Afforestation - Over the last 80 years there has been an extensive program of
Conifer afforestation in the UK uplands. Streams in afforestation catchments have higher sulfate values and lower pH values.
Changes in land use:
Afforestation - Conifer afforestation is responsible for surface water acidification by:
- Acid production by oxidation of
Anaerobic soils or peats following ploughing for planting trees.
Changes in land use:
Afforestation - Conifer afforestation is responsible for surface water acidification by:
- Loss of
Base cations from soil from the uptake by trees.
Changes in land use:
Afforestation - Conifer afforestation is responsible for surface water acidification by:
- Accumulation of
Acid humus in soil from the forests.
Acid deposition: Acidification of surface waters has occurred in the last
150 years as a result of acid deposition, mainly from anthropogenic emissions of sulfur dioxide.
Acid deposition:
This took place following the increase in
Fossil fuel burning and industrial emissions during the industrial revolution.
The 3 hypothesises that were proposed to explain the observed acidification of surface waters:
- Natural long-term acidification
- Changes in land use
- Acid deposition
