Acidification and Eutrophication
NGEA09, 2017
Cecilia Akselsson
Department of Physical Geography and Ecosystem Science
Lund University
Lund University, Deparment of Physical Geography and Ecosystem Science
The environmental objectives of Sweden
Reduced climate impact
A protective ozone layer
Natural acidification only
Zero eutrophication
A safe radiation
environment
Thriving wetlands
A varied agricultural
landscape
A good built environment
A magnificent mountain
landscape
A non-toxic environment
Clean air
Flourishing lakes and streams
A Balanced Marine Environment, Flourishing Coastal
Areas and Archipelagos
Sustainable forests
Good quality groundwater
A rich diversity of plant
and animal life
Lund University, Deparment of Physical Geography and Ecosystem Science
The environmental objectives of Sweden
Reduced climate impact
A protective ozone layer
Natural acidification only
Zero eutrophication
A safe radiation
environment
Thriving wetlands
A varied agricultural
landscape
A good built environment
A magnificent mountain
landscape
A non-toxic environment
Clean air
Flourishing lakes and streams
A Balanced Marine Environment, Flourishing Coastal
Areas and Archipelagos
Sustainable forests
Good quality groundwater
A rich diversity of plant
and animal life
Lund University, Deparment of Physical Geography and Ecosystem Science
Acidification
– how does it connect to land surface processes?
Photo: Jonas Åkerman
Photo: Cecilia Akselsson
Photo: Cecilia Akselsson
Weathering! Depends on parent material which
depends on geomorphological processes
Lund University, Deparment of Physical Geography and Ecosystem Science
atmosphere
precipitation
evaporation
greenhouse effect
temperature
shortwave
radiation
wildfires
greenhouse gases,
aerosols
longwave
radiation
air pollution
CO2 emission
ecosystem
services
cloud formation
primary production
decomposition
evapotranspiration biosphere litter
nutrient
runoff
uptake
weathering
hydrosphere
drainage
lithosphere
groundwater
Lund University, Deparment of Physical Geography and Ecosystem Science
(Borrowed from B. Smith)
Disposition: Acidification
-Acidification processes – atmospheric deposition
-Present situation and trends
-Acidification processes – forestry
-Other processes affecting acidification (focus: weathering)
-Acidification in relation to land surface processes in Sweden
-Critical loads and critical harvesting –going from
science to policies
Lund University, Deparment of Physical Geography and Ecosystem Science
Acidification processes – atmospheric deposition
Lund University, Deparment of Physical Geography and Ecosystem Science
Acidification processes – atmospheric deposition
Nitrogen
Sulphur
Lund University, Deparment of Physical Geography and Ecosystem Science
Sulphur deposition
Main source of S: Combustion of coal and oil.
Also industries, ships, etc.
S + O2 ↔ SO2
SO2 + O2 ↔ 2 SO3
SO3 + H2O ↔ 2 H+ + SO42-
Lund University, Deparment of Physical Geography and Ecosystem Science
Oxidized nitrogen (NOx) deposition
Main source of NOx: Traffic
N2 + O2 ↔ 2 NO
2 NO + O2 ↔ 2 NO2
2 NO2 + H2O ↔ HNO2 + H+ + NO3-
Lund University, Deparment of Physical Geography and Ecosystem Science
Reduced nitrogen (NH3) deposition
Main source of NH3: Fertilizers
NH3 + H2O ↔ NH4+ + OHNH4+ + 2 O2 ↔ 2 H+ + NO3- + H2O
Lund University, Deparment of Physical Geography and Ecosystem Science
Acidification of soil and water
Acid water from soil surface
Ions transported down in the
profile and to surface water
(Från www.capensis.se)
Lund University, Deparment of Physical Geography and Ecosystem Science
Acidification of soil and water
Before
acidification
Base cations
Large
exchangeable pool
During
acidification
Acidified
condition
Decreasing pool
Small
pool
During
recovery
Incr.
pool
Naturvårdsverket report 5028
Lund University, Deparment of Physical Geography and Ecosystem Science
Effects of acidification
-Low pH and high concentrations of toxic aluminium
-Negative effects on fish and other water living organisms
-Risk of negative effects on vegetation
-Increased leaching of nutrients important for trees
(e.g. Mg and K) which can lead to nutrient imbalance
-Increased leaching of heavy metals (e.g Cd and Pb)
Lund University, Deparment of Physical Geography and Ecosystem Science
Present situation and trends
Photo: Cecilia Akselsson
Lund University, Deparment of Physical Geography and Ecosystem Science
What does the environmental objective say?
“It is not possible to reach the environmental
objective to 2020 with the decided or planned
measures. The development is positive.
Lund University, Deparment of Physical Geography and Ecosystem Science
Acidification status today
- 10% of Swedish lakes and 20% of the forest soils
are assessed as acidified.
- In SW Sweden 50% of the lakes and forest soils are
assessed as acidified.
- 200 million SEK are spent on lake liming every year
- Measurements and modelling indicate slow recovery
Lund University, Deparment of Physical Geography and Ecosystem Science
Sulphur deposition in Småland 1880-2000
Critical load
Naturvårdsverket report 5028
Lund University, Deparment of Physical Geography and Ecosystem Science
Reductions of emissions in Europe
Percentage change
Sulphur dioxide
IVL, 2015: Krondroppsnätet 1985-2015
Lund University, Deparment of Physical Geography and Ecosystem Science
Sulphur deposition trends
(Based on data from the SWETHRO network. Modified from Pihl Karlsson et al, 2011, Env. Poll.)
Lund University, Deparment of Physical Geography and Ecosystem Science
Nitrogen deposition trends
(Västra Torup, Skåne)
20
15
kg/ha
10
5
0
1985 1990 1995 2000 2005 2010
(Based on data from the SWETHRO network, IVL)
Lund University, Deparment of Physical Geography and Ecosystem Science
Antropogenically acidified lakes
Lakes (> 1 ha) in different effect classes in the year
2010, based on there modelled pH decrease since
before insustrialization
(Filip Moldan, IVL, www.ivl.se/magiclibrary)
Lund University, Deparment of Physical Geography and Ecosystem Science
Acidification in soil
% soil in the
2 highest acidification classes
From soil inventory,
Johan Stendahl, SLU
Lund University, Deparment of Physical Geography and Ecosystem Science
Acidification processes - forestry
Lund University, Deparment of Physical Geography and Ecosystem Science
Acidification processed forestry
H+
H+
Ca2+
H+
H+
Mg2+
K+
H+
Lund University, Deparment of Physical Geography and Ecosystem Science
Acidificaton processes - forestry
Reported slash removal
Actual slash removal
Removal in thinnings
Reported stump removal
Wood ash recycling
(Swedish forest agency)
Lund University, Deparment of Physical Geography and Ecosystem Science
Other processes affecting acidification (focus: weathering)
atmospheric
deposition
cation exchange
sulphur
adsorption
nutrient
uptake
nitrification
chemical weathering
Naturvårdsverket report 5028
Lund University, Deparment of Physical Geography and Ecosystem Science
The role of weathering
Acid rain removes base cations and acidifies…
…and biomass harvesting too.
Chemical weathering leads to release of
base cations and counteracts acidity.
Ex: 3 KAlSi3O8 + 2H+ +12 H2O →
KAl3Si3O10 (OH)2 + 6 H4SiO4 + 2 K+
Lund University, Deparment of Physical Geography and Ecosystem Science
Weathering – the most important process
counteracting acidification
(From Hess, 2013)
Lund University, Deparment of Physical Geography and Ecosystem Science
Joints – where the weathering begins
(From Hess, 2013)
Lund University, Deparment of Physical Geography and Ecosystem Science
Different types of weathering
Mechanical weathering: Breaking of rock material without
any chemical changes
Chemical weathering: Decomposition of rock by the the
chemical alteration of the material
Biological weathering (one of the definitions):
The impact of vegetation and fungi on weathering of mineral
soils, e.g. through altering the chemical conditions in the soils
(closely connected to chemical weathering)
Lund University, Deparment of Physical Geography and Ecosystem Science
Important weathering processes
consuming H+
-Hydrolysis (Reaction with H2O)
-Carbonation (Reaction with CO2)
-Strong acids (Reaction with H+)
-Reaction with organic acids
Lund University, Deparment of Physical Geography and Ecosystem Science
Hydrolysis
Reaction with water, example olivine:
Mg2SiO4 + 4 H+ + 4 OH - ⇌ 2 Mg 2+ + 4 OH - + H4SiO4
Carbonation
Reaction with carbonic acid, example calcium carbonate:
CO2 + H 2O → H 2CO3
H 2CO3 + CaCO3 → Ca(HCO3)2
Strong acids
Reaction with strong acids, example K-feldspar
3 KAlSi3O8 + 2H+ +12 H2O → KAl3Si3O10 (OH)2 + 6 H4SiO4 + 2 K+
Lund University, Deparment of Physical Geography and Ecosystem Science
Important factors affecting chemical weathering rates
-Presence of weathering agents (H2O, H+, CO2, organic acids)
-Hardness and composition
-Total surface area
-Temperature and precipitation
Lund University, Deparment of Physical Geography and Ecosystem Science
Weathering rates with the PROFILE model
Weathering rates of BC
are calculated as
the sum of reactions
between minerals and:
-H+
-water
-CO2
-Organic ligands
fH
fH2O
fOH
fCO2
fR
Lund University, Deparment of Physical Geography and Ecosystem Science
Weathering modelling – The PROFILE model
minerals reactions
Field rate = ∑
i
∑ Rate
j
•A
ij
• f(moisture) •g
ij
Lund University, Deparment of Physical Geography and Ecosystem Science
(T)
ij
Weathering modelling - The PROFILE model
Lund University, Deparment of Physical Geography and Ecosystem Science
Acidification in the perspective of
Swedish rocks, soils and landforms
Photo: Jonas Åkerman
Photo: Cecilia Akselsson
Photo: Cecilia Akselsson
Lund University, Deparment of Physical Geography and Ecosystem Science
Acidification in the perspective of
Swedish rocks, soils and landforms
(From Hess, 2013)
(From Hess, 2013)
(Photo: Jonas Åkerman)
www.sgu.se
Lund University, Deparment of Physical Geography and Ecosystem Science
Acidification in the perspective of
Swedish rocks, soils and landforms
(Photo: Cecilia Akselsson)
(From Hess, 2013)
(Photo: Jonas Åkerman)
Lund University, Deparment of Physical Geography and Ecosystem Science
Acidification in the perspective of
Swedish rocks, soils and landforms
(http://www-markinfo.slu.se/)
(soil map from SGU)
Lund University, Deparment of Physical Geography and Ecosystem Science
(http://www-markinfo.slu.se/)
Critical loads and critical harvesting –
going from science to policies
Lund University, Deparment of Physical Geography and Ecosystem Science
Critical loads – how much deposition can
the soil/water take wihout harmful effects?
CL (S+N) = BC dep + BC weath + N uptake + N imm. – BC uptake – Alk leach
Exceedance = Sdep + N dep – CL (S+N)
Lund University, Deparment of Physical Geography and Ecosystem Science
Critical loads – how much deposition can
the soil/water take wihout harmful effects?
1990
now
Lund University, Deparment of Physical Geography and Ecosystem Science
(Modelled by Filip Moldan, IVL)
New proposed concept. Critical harvesting – how much
Biomass can we harvest without harmful effects?
Assumptions:
The N leached as NO3-N is acidifying, the N leached
as NH4-N is counteracting acidification, no other effects of N.
Alk leach crit = 0 (no leaching of acidity)
Crit BCharv = BCweath + BCdep - Sdep - Cldep + NH4-Nleach – NO3-Nleach
Exceedance = BCharv - Crit BCharv
Lund University, Deparment of Physical Geography and Ecosystem Science
Exceedande of critical biomass harvesting (spruce)
Stem
harv.
Stem+
branch
harv.
Lund University, Deparment of Physical Geography and Ecosystem Science
The environmental objectives of Sweden
Reduced climate impact
Natural acidification only
A safe radiation
environment
Zero eutrophication
A safe radiation
environment
Thriving wetlands
A varied agricultural
landscape
A good built environment
A magnificent mountain
landscape
A non-toxic environment
Clean air
Flourishing lakes and streams
A Balanced Marine Environment, Flourishing Coastal
Areas and Archipelagos
Sustainable forests
Good quality groundwater
A rich diversity of plant
and animal life
Lund University, Deparment of Physical Geography and Ecosystem Science
Eutrophication
– how does it connect to land surface processes?
Photo: Tette Alström
Photo: Cecilia Akselsson
Transport through erosion and runoff!
Depends on soils and runoff patterns.
Lund University, Deparment of Physical Geography and Ecosystem Science
Disposition: Eutrophication
-Eutrophication processes
-N and P sources
-Present situation and trends
-N and P leaching from agricultural land
Lund University, Deparment of Physical Geography and Ecosystem Science
Eutrophication processes
N and P addition
Increased production
of algae and plankton
Increased release
of N and P
Increased sed. of
org. material
Hypoxia and
poisonous sulphides
Death of benthic organisms and fish
Lund University, Deparment of Physical Geography and Ecosystem Science
N and P sources
Lund University, Deparment of Physical Geography and Ecosystem Science
N and P sources
(From Brandt et al., 2008; NV Report 5815)
Lund University, Deparment of Physical Geography and Ecosystem Science
N and P sources
P
N
(www.vattenmyndigheterna.se)
Lund University, Deparment of Physical Geography and Ecosystem Science
Present situation and trends
Lund University, Deparment of Physical Geography and Ecosystem Science
What does the environmental objective say?
“It is not possible to reach the environmental
objective to 2020 with the decided or planned
measures. No clear direction for the development of
the environment can be seen.”
Lund University, Deparment of Physical Geography and Ecosystem Science
Indicator: Addition of nitrogen to the coast
(www.miljomal.nu)
Lund University, Deparment of Physical Geography and Ecosystem Science
Indicator: Addition of phosphorous to the coast
(www.miljomal.nu)
Lund University, Deparment of Physical Geography and Ecosystem Science
N and P leaching from agricultural land
(Photo: Tette Alström)
Lund University, Deparment of Physical Geography and Ecosystem Science
N and P leaching from agricultural land
Processes
N–
dissolved in
water
P – bound to
soil particles
and eroded
N
P
P
N
N
Erosion
Transport
Processes
(Borrowed from Karin Larsson)
Lund University, Deparment of Physical Geography and Ecosystem Science
N and P leaching from agricultural land
Can we reduce it?
N
P: Protective zones,
sedimentation dams
N
P
P
N
N
N: Dams, wetlands,
meandring watercourses
(Borrowed from Karin Larsson)
Lund University, Deparment of Physical Geography and Ecosystem Science
N and P leaching from agricultural land
Important factors
Landuse and topography
Texture (P)
Photo: Tette Alström
Bolder: > 200 mm
Stone: 6-200 mm
Gravel: 2-60 mm
Sand: 0.06-2 mm
Silt: 0.002-0.06 mm
Clay: < 0.002 mm
Hydrology
(From Hess, 2013)
Lund University, Deparment of Physical Geography and Ecosystem Science