ling diffuse soil contamination from agricul
Jan 12, 2016
Modeling diffuse soil contamination from agriculture.
SUMMARY:SUMMARY:•Soil contamination, as defined Soil contamination, as defined in the Soil Thematic Strategy.in the Soil Thematic Strategy.
•Local soil contamination and Local soil contamination and Diffuse soil contaminationDiffuse soil contamination
•Modeling Tools of Diffuse soil Modeling Tools of Diffuse soil contamination.contamination.
•SWAT DescriptionSWAT Description
•SWAT application, two casesSWAT application, two cases
•Leaching Modeling. Pesticide Leaching Modeling. Pesticide soil contamination. soil contamination.
•PRZM and PEARL descriptionPRZM and PEARL description
•PRZM and PEARL applicationPRZM and PEARL application
•ConclusionConclusion
introduction
Soil contamination, as defined in the Soil Thematic
Strategy.
introduction
The introduction of contaminants in the soil may result in The introduction of contaminants in the soil may result in
damage to or loss of some or several functions of soils and damage to or loss of some or several functions of soils and
possible cross contamination of water. The occurrence of possible cross contamination of water. The occurrence of
contaminants in soils above certain levels entails multiple contaminants in soils above certain levels entails multiple
negative consequences for the food chain and thus for negative consequences for the food chain and thus for
human health, and for all types of ecosystems and other human health, and for all types of ecosystems and other
natural resources. natural resources.
Local and Diffuse Soil contamination, Sources.introduction
Local (or point source) contamination is generally Local (or point source) contamination is generally associated with mining, industrial facilities, waste associated with mining, industrial facilities, waste landfills and other facilities both in operation and landfills and other facilities both in operation and after closure.after closure.These activities can pose risks to both soil and These activities can pose risks to both soil and water.water.
Local Soil contamination, Sources.Local Soil contamination, Sources.
Diffuse pollution is generally associated with atmospheric deposition, certain farming practices and inadequate waste and wastewater recycling and treatment.
Diffuse Soil contamination, Sources.Diffuse Soil contamination, Sources.
Diffuse Soil contamination, Sources.
introduction
•Atmospheric deposition is due to emissions from industry, traffic and Atmospheric deposition is due to emissions from industry, traffic and agriculture. Deposition of airborne pollutants releases into soils acidifying agriculture. Deposition of airborne pollutants releases into soils acidifying contaminants (e.g. SO2, NOx), heavy metals (e.g. cadmium, lead arsenic, contaminants (e.g. SO2, NOx), heavy metals (e.g. cadmium, lead arsenic, mercury), and several organic compounds (e.g. dioxins, PCBs, PAHs).mercury), and several organic compounds (e.g. dioxins, PCBs, PAHs).
•Production systems where a balance between farm inputs and outputs is Production systems where a balance between farm inputs and outputs is not achieved in relation to soil and land availability, leads to nutrient not achieved in relation to soil and land availability, leads to nutrient imbalances in soil, which frequently result in the contamination of ground- imbalances in soil, which frequently result in the contamination of ground- and surface water.and surface water.
•Pesticides are toxic compounds deliberately released into the Pesticides are toxic compounds deliberately released into the environment to fight plant pests and diseases. They can accumulate in the environment to fight plant pests and diseases. They can accumulate in the soil, leach to the groundwater and evaporate into the air from which soil, leach to the groundwater and evaporate into the air from which further deposition onto soil can take place.They also may affect soil further deposition onto soil can take place.They also may affect soil biodiversity and enter the food chain.biodiversity and enter the food chain.
•With regard to waste, sewage sludge, the final product of the treatment With regard to waste, sewage sludge, the final product of the treatment of wastewater, is also raising concern. A whole range of pollutants, such of wastewater, is also raising concern. A whole range of pollutants, such as heavy metals and poorly biodegradable trace organic compounds, as heavy metals and poorly biodegradable trace organic compounds, potentially contaminates it what can result in an increase of the soil potentially contaminates it what can result in an increase of the soil concentrations of these compounds.concentrations of these compounds.
Diffuse Soil contamination, Sources.
introduction
Production systems where a balance between farm Production systems where a balance between farm inputs and outputs is not achieved in relation to soil inputs and outputs is not achieved in relation to soil and land availability, leads to nutrient imbalances in and land availability, leads to nutrient imbalances in soil, which frequently result in the contamination of soil, which frequently result in the contamination of ground- and surface water.ground- and surface water.
Modeling the fate of contaminants requires an understanding of the soil-water-air continuum. The modeling tool should be able to simulated
physical, chemical and biological processes occurring in these different compartments.
The modelling approach ...
AIR
SOIL
GROUNDWATER
RIVER
Atmospheric depositionN fixation
Fertilizer applications
Surface and subsurface runoffN
Leaching
Point discharges
Plants consumption
Plants consumption
Simulation of soil processes: organic matter turnover, crop growth, nitrogen uptake, water infiltration, evaporation from crop and soil
surface, nitrification, denitrification, interception of precipitation and emissions to the atmosphere.
Atmospheric emissions
NITRIFICATION/ DENITRIFICATIO
NSTORAGE
• Vertical flow in the unsaturated zone links the soil processes to the 2-D overland flow and to the 3-D groundwater flow.
Estimation of loads at representative sites, aggregation at landscape scale, and upscaling to regions .
Calculation of the impacts of the agricultural sector under selected land use scenarios.
… a nested approach
• A fully distributed physically based model representing variations in catchment characteristics and driving variables by a network of uniform grids or sub-basins.
• Scenario analyses (socio-economic, climate, environmental) to improve resource management and provide information that will aid for the sustainable management of the watershed.
• Impact assessment of waste management strategies, tourism, urban areas, mining activities, land use changes.
An Observational Network of European Watersheds
Modeling of Diffuse soil contamination.
Modeling tools
Modeling Tools: able to considering processes Modeling Tools: able to considering processes occurring in the soil-water-air compartments in the occurring in the soil-water-air compartments in the studied area, mainly used for Nitrogen and studied area, mainly used for Nitrogen and Phosphorus modeling.Phosphorus modeling.
•SWAT (Soil Water Assessment Tool, Blackland SWAT (Soil Water Assessment Tool, Blackland Research Centre, Texas US-Arnold et al., 1992)Research Centre, Texas US-Arnold et al., 1992)
SWAT description
mainswat
characteristics
basin-scalecontinuous timedaily time stepphysically basedcomputationally efficientlong-term simulationswater, sediments, nutrients, pesticides
Hydrologymodel
SWAT description
Physical model SWAThydrology
evapo
precipitation
surfacerunoff
lateralflow
infiltration
transpiration
Physical model
Surface runoff
use of SCS curve number method to estimate surface runoff
SWAThydrology
Evapotranspiration
Three methods included in SWATPenman-MonteithHargreavesPriestley-Taylor
ET is evaluated from soils and plants as well
Snow melt
melting if the second soil layer temperature exceeds 0 C and proportional to the snow pack temperature
Physical model Soil moduleSWAT
Water that enters the soil may move along one of several differentpathways. The water may be removed from the soil by plant uptake or
evaporation. It can percolate past the bottom of the soil profile and ultimatelybecome aquifer recharge. A final option is that water may move laterally in the
profile and contribute to streamflow. Of these different pathways, plant uptake ofwater removes the majority of water that enters the soil profile.
SWAT considers:
•Soil StructureSoil Structure•PercolationPercolation
•Lateral FlowLateral Flow
SWAThydrology
physical model
Soil StructureSoil Structure
Swat considers three phases in the soil:solid, liquid and gas.
The solid phase consists of minerals and/or organic matter that forms the matrix or skeleton.Between the
solid particles, soil pores are formed that hold the liquid and gas phases. The soil solution may saturate the soil completely or partially. Swat calculates the balance in every layer and once (..and if ) this layer
reach the saturation moves the water to the next one.Soil Name: s1Db Soil Hydrologic Group: C Maximum rooting depth(m) : 900.00 Porosity fraction from which anions are excluded: 1.000 Crack volume potential of soil: 0.000 Texture 1 : LFS-LFS-S Depth [mm]: 300.00 600.00 900.00 Bulk Density Moist [g/cc]: 1.46 1.46 1.41 Ave. AW Incl. Rock Frag : 0.17 0.28 0.35 Ksat. (est.) [mm/hr]: 1.00 2.40 200.00 Organic Carbon [weight %]: 1.50 0.86 0.52 Clay [weight %]: 22.00 5.00 3.00 Silt [weight %]: 59.00 76.00 7.00 Sand [weight %]: 19.00 19.00 90.00 Rock Fragments [vol. %]: 0.00 0.00 0.00 Soil Albedo (Moist) : 0.06 0.06 0.06 Erosion K : 0 .23 0.23 0.23 Salinity (EC, Form 5) : 1.00 0.00 0.00
SWAThydrology
Percolation
physical model
percolationpercolationPercolation is calculated for each soil layer in the profile. Percolation is calculated for each soil layer in the profile. Water is allowed to percolate if the water content exceeds Water is allowed to percolate if the water content exceeds the field capacity water content for that layer. When the soil the field capacity water content for that layer. When the soil layer is frozen, no water flow out of the layer is calculated. layer is frozen, no water flow out of the layer is calculated. The volume of water available for percolation in the soil The volume of water available for percolation in the soil layer is calculated:layer is calculated:
SW ly excess= FC ly – sSW ly if FC ly SW ly excess= FC ly – sSW ly if FC ly > > SW ly SW ly SW ly excessSW ly excess = 0 , = = 0 , = excess ly if FC ly excess ly if FC ly < or = < or = SW lySW ly
wherewhere SWly,excess SWly,excess is the drainable volume of water in the is the drainable volume of water in the soil layer on a given day (mm H2O), soil layer on a given day (mm H2O), SWly SWly is the water is the water content of the soil layer on a given day (mm H2O) and content of the soil layer on a given day (mm H2O) and FCly FCly is the water content of the soil layer at field capacity (mm is the water content of the soil layer at field capacity (mm H2O).H2O).
SWAThydrology
physical model
Lateral FlowLateral FlowLateral flow will be significant in areas with soils Lateral flow will be significant in areas with soils having high hydraulichaving high hydraulicconductivities in surface layers and an impermeable conductivities in surface layers and an impermeable or semipermeable layer at a shallow depth. In such a or semipermeable layer at a shallow depth. In such a system, rainfall will percolate vertically until it system, rainfall will percolate vertically until it encounters the impermeable layer. The water then encounters the impermeable layer. The water then ponds above the impermeable layer forming a ponds above the impermeable layer forming a saturated zone of water, i.e. a perched water table. saturated zone of water, i.e. a perched water table. This saturated zone is the source of water for lateral This saturated zone is the source of water for lateral subsurface flow.subsurface flow. lateralflow
Physical modelweather
SWAT
driving variables• precipitation• temperature
• solar radiation• wind speed
• relative humidity
daily measurements
Monthly measurements
In case of missed values, a weather generator is included in the code
Physical model
sedimentsswat
sediment yield
MUSLE: Modified Universal Soil Loss Equation(USDA, Williams et al. 1977)
Physical model
crop growthswat
heatunits
leaf areaindex
solar radiation energyinterception
cropparameter
biomassproduction
harvestindex
cropyield
Physical model
nutrientsswat
NITROGEN model in SWAT
Residue
NO3Active organic N
Stable organic N
Plant uptakeharvest
Inorganic fertilizer
Mineralization
Decay
Mineralization
Denitr
ifica
ti
onOrganic fertilizer
Physical model
nutrientsswat
PHOSPHORUS model in SWAT
Residue
Dissolved labile P
Sediment-bound labile P
Lumped Active/Stable
organic P
Plant uptake
harv
est
Inorganic fertilizer
MineralizationOrganic fertilizer
Sediment-bound fixed P
Minera
lizatio
n
OUSE Catchment (UK)
BURANA PO di VOLANO Catchment (IT)
TWO EXAMPLES DEVELOPED USING SWAT COUPLED WITH GIS (ArcInfo and ArcView, ESRI)
MAIN ISSUES OF THE MODEL APPLICATIONS
Allowing the quantification of the total load of pollutant affecting a watershed. This model should
be used to understand how the soil quality and water quantity/quality are affected by agricultural
activities.
Models application
Examples: OUSE Catchment (UK) Soil Map
OUSE Land Use: (%)
•FRSE 2.25•PAST 27.02•RANGE 32.88•WWHT 29.10•URBAN 8.75
Examples: OUSE Catchment (UK)Landuse Map
OUSE HYDROLOGY
0
20
40
60
80
100
120
140
160
180
gen-86 gen-87 gen-88 gen-89 gen-90
OU
TFLO
W (cm
/s)
mesurated NEW SETUP
OUSE WATERSHED MONTHLY TIME STEP OUSE WATERSHED MONTHLY TIME STEP SIMULATION(30 years simulation): FLOW OUT [mSIMULATION(30 years simulation): FLOW OUT [m33/s] and /s] and
LINEAR CORRELATIONLINEAR CORRELATION
OUSE HYDROLOGY, STATISTICAL ANALYSIS
R2 = 0.9239
0
50
100
150
200
0 20 40 60 80 100 120 140 160 180 200
OU
TFL
OW
/cm
/s)
NEW SETUP Linear (NEW SETUP)
0.00E+00
2.00E+05
4.00E+05
6.00E+05
8.00E+05
1.00E+06
1.20E+06
1.40E+06
1.60E+06
1.80E+06
2.00E+06
Jan-87 Jan-88 Jan-89 Jan-90
TO
TAL N
ITR
OG
EN
(Kg)
mesurated NEW SETUP
OUSE WATERSHED MONTHLY TIME STEP SIMULATION(30 years simulation): TOTAL
NITROGEN [Kg]
LANDUSE SCENARIO: COMPARISON BETWEEN N EXCESS AND N PLANT UPTAKE WITH TWO DIFFERENT APPLICATION RATE OF ORGANIC NITROGEN IN THE OUSE WATERSHED
LANDUSE SCENARIO: COMPARISON BETWEEN NO3 TO RIVER AND NO3 LEACHING WITH TWO DIFFERENT APPLICATION RATE OF ORGANIC NITROGEN IN THE OUSE WATERSHED
210 Kg/haORGANIC NITROGEN
170 Kg/haORGANIC NITROGEN
AVERAGE ANNUAL CHANGE:-6.34 %
Examples: Burana Po di Volano (IT)
Examples: Burana Po di Volano(IT)
Scenario attuale
Scenario I
Scenario II
Present scenario
Scenario I
Scenario IIGCM Scenario
CGCM1 e HadCM2
year 2050 Usi non a seminativo
0-67-1213-1819-2425-3031-3637-4243-4849-5455-6061-6667-7273-7879-8485-90
Influence of Climate Change on Nitrogen Influence of Climate Change on Nitrogen Percolation from Soils to GroundwaterPercolation from Soils to Groundwater
Burana-Po di Volano watershed
NO3 leaching (Kg/ha)
Leaching Models: applied to determine the Leaching Models: applied to determine the quantity of Pesticide leaching thought the soil quantity of Pesticide leaching thought the soil profile reaching the shallow aquifer.profile reaching the shallow aquifer.
•PRZM2: Pesticide Root Zone Model, PRZM2: Pesticide Root Zone Model, Environmental Protection Agency, US - Carsel et Environmental Protection Agency, US - Carsel et al. 1984.al. 1984.
• PEARL: Pesticide Emission Assessment at PEARL: Pesticide Emission Assessment at Regional and Local Scales by Alterra Green World Regional and Local Scales by Alterra Green World Research.Research.
Modeling of Diffuse soil contamination.
Modeling tools
TREVIGLIO Catchment (IT)
EUROPEAN SCALE
TWO EXAMPLES DEVELOPED USING PRZM and PEARL coupled with ARCVIEW GIS
Models application
MAIN ISSUES OF THE MODEL APPLICATIONS
Models are run at field and regional scale to be tested (PRZM, PELMO) then the necessary information are collected at European level and run with a model like PEARL (able to work with big database) to estimate the persistence of selected substances at European scale.
PRZM2 is a one-dimensional, dynamic, PRZM2 is a one-dimensional, dynamic, compartmental model that can be used to compartmental model that can be used to simulate chemical movement in unsaturated simulate chemical movement in unsaturated soil systems within and immediately below soil systems within and immediately below the plant root zone. It has two major the plant root zone. It has two major components:components:
•hydrologyhydrology
•chemical transport. chemical transport.
The model was specifically designed to The model was specifically designed to provide loading to selected media, including provide loading to selected media, including air, water, groundwater. PRZM2 runs on air, water, groundwater. PRZM2 runs on daily time step. PRZM2 is extensively used daily time step. PRZM2 is extensively used from the U.S. Environmental Protection from the U.S. Environmental Protection Agency to simulate the transport of field-Agency to simulate the transport of field-applied pesticides in the crop root zone.applied pesticides in the crop root zone.
Examples: TREVIGLIO catchment (IT)
Modeling of Diffuse soil Modeling of Diffuse soil contamination.contamination.Regional scaleRegional scale
Examples: TREVIGLIO catchment(IT)
Concentration limits applied for classification of the Maps.
Soil Vulnerability to Pesticide Leaching Concentration (µg/l)
Very Low Vulnerability < 0.001
Low Vulnerability 0.001 – 0.01
Medium - Low Vulnerability 0.01 – 0.1
Medium - High Vulnerability 0.1 – 1
High Vulnerability 1 – 10
Very High Vulnerability > 10
Alachlor (app. Rate 2.0 Kg/ha)
Atrazine (app. Rate 1.5 Kg/ha)
Use a process based model supported by the FOCUS working group that includes all major processes involved with pesticide transformation and fate. For instance, we are currently using the PEARL model which is used to evaluate the leaching of pesticides to the groundwater in support to the European and Dutch pesticide registration procedures.
Ponding
Soil water fluxes
Seepage
Satu
rate
d zo
neUn
satu
rate
d zo
ne
Heat flow
Transpiration
Water uptake
Lateral dischargeto ditches / drains
SWAP
Leaching
Volatilization
Pesticideuptake
Dissipation
Washoff
ConvectionDispersionDiffusion
Transformation
Solid/liquid/gaspartitioning
PEARL
December 14 1990
Bentazone concentration (mgl-1)
0.0 0.1 0.2 0.3 0.4 0.5 0.6
De
pth
(cm
)
0
20
40
60
80
100
120
140
measuredpredicted
Bentazone soil concentration 22 and 278 days after application of 0.8 kg/ha of bentazone on field
under winter wheat (NL)
Deliverable: map of pesticides persistence in the top layer, in the root zone, and leaching below the root
zoneCollect the necessary information at European level and run the PEARL model to estimate the persistence of selected
substances
CONCLUSION:
• These kind of modeling tool could be useful to analyze and simulate the water contamination in a
medium-big scale watershed.
•They are able to determine soil limitations (topography, rooting depth, chemical fertility, organic
carbon) of European soils (using harmonised European soil information system).
• It is also possible to derive crop suitability zones and compare the capability maps with land use maps.
•Useful to make some general conclusion about the effect of the global climate change could be done.LIMITATIONS:
•The calibration of the model is time-consuming and it would need more efficient tools
•The quality of the model simulation depends on the quality of the data available.