Comparing Agricultural and Urban Nutrient Loads to Coastal ... · Nunes and Ferreira: Agricultural...
Transcript of Comparing Agricultural and Urban Nutrient Loads to Coastal ... · Nunes and Ferreira: Agricultural...
Comparing Agricultural and Urban Nutrient Loads to Coastal Systems
João Pedro NUNES, João Gomes FERREIRAUniversity of Aveiro, Portugal
NOVA University of Lisbon, PortugalLongline Environment, UK
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
Nutrient loads and aquaculture• Aquaculture and nutrients: an ambivalent relation
− Nutrients support primary production and food, but…− Excessive loads can cause eutrophication
• Nutrient management has focused on wastewater− Point sources: easy to locate, measure and control
• Agricultural sources are more difficult to manage− Variable in space, depend on weather− Difficult to measure and to identify sources− Difficult to design control measures
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
Objectives of this work• Compare nutrient loads to coastal systems from wastewater and agriculture…− Recent evolution− Spatio‐temporal patterns− Sources and potential impacts
• … for two coastal systems with important aquaculture sites− Lough Foyle, UK− Ria Formosa, Portugal
Lough Foyle
Ria Formosa
Lough Foyle
Ria Formosa
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
Study systemsLough Foyle• Oceanic climate• Aquaculture: mussels and native oysters (bottom culture)
• Trophic status:− High nutrient loads, mostly N− Few eutrophication symptoms: shellfish filtration (?) and P limitation (?)
Ria Formosa• Mediterranean climate• Aquaculture: clams (traditional) and mussels (offshore, developing)
• Trophic status:− High nutrient loads− Few eutrophication symptoms due to strong water exchange…
− … but occasional water quality issues and macroalgae blooms
Lough Foyle
Ria Formosa
051015202530
0
50
100
150
1 2 3 4 5 6 7 8 9 101112
Tempe
rature (ºC)
Rainfall (m
m)
Month
Ria Formosa (Faro)
051015202530
0
50
100
150
1 2 3 4 5 6 7 8 9 101112
Tempe
rature (ºC)
Rainfall (m
m)
Month
Lough Foyle (Malin Head)
Lough Foyle: Loughs Agency 2012: Lough Foyle Status ReportRia Formosa: Ferreira et al. 2013: FORWARD project report
Rainfall
Temperature
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
Lough Foyle watershed• Area: 3709 Km2
• Wastewater discharge: 210,000 inhabitants
• Landuse:− Pasture: 54%− Rangelands: 43%− Croplands, urban: 3%
Lough Foyle
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
Ria Formosa Watershed• Area: 745 Km2
• Wastewater discharge: 300,000 inhabitants
• Landuse:− Croplands – intensive orchards: 18%− Croplands – rainfed orchards: 29%− Rangelands: 48%− Other crops, urban, pasture: 5%
• Contaminated coastal aquifer
Ria Formosa
Faro
Tavira
Olhão
Ria Formosa
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
Research framework• Large‐scale aquaculture assessment projects in both systems− Linking catchments to coasts− Linking management agencies and research institutes
− Tool: complex modelling framework
Wastewater, agriculture and stream network
Coastal ecosystems and aquaculture
Coastal water circulation
Water
Nutrients
EASE: Enhanced SMILE for Lough Foyle
Lough Foyle Ria Formosa
Framework for Ria Formosa water quality, aquaculture & resource development
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
Wastewater nutrient loads• Point‐sources:
− Measured, easy to quantify− Relatively constant along the year
• Recent trends:− Improved wastewater treatment by adding nutrient removal
− Ria Formosa: increase in population served by treatment plants
• Wastewater treatment close to maximum
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
Lough Foyle Ria Formosa
Popu
latio
n served
Before 2000 After 2010
02468
101214
Untreated
Before 200
0
After 2
010
Before 200
0
After 2
010
Lough Foyle Ria Formosa
N lo
ads (g/pe
rson
.dy)
0
100
200
300
400
500
600
700
Lough Foyle Ria Formosa
Nitrog
en (ton
/yr)
Before 2000 After 2010
0
20
40
60
80
100
120
140
Lough Foyle Ria Formosa
Phosph
orus (ton
/yr)
Before 2000 After 2010
Nitrogen load (per inhabitant)
Population served
Total N loads Total P loads
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
y = ‐3E‐05x + 2.28R² = 0.0154
0
0.5
1
1.5
2
2.5
3
3.5
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100
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601
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601
/200
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/200
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/200
901
/201
001
/201
101
/201
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/201
301
/201
4
Nitrates (m
g N/L)
Stream
flow (m
3 /s)
Streamflow Nitrate concentration Linear (Nitrate concentration)y = ‐8E‐06x + 0.4324
R² = 0.0038
00.20.40.60.811.21.41.61.8
020406080
100120140160
01/199
0
01/199
1
01/199
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01/199
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01/199
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01/199
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01/199
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01/199
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01/200
0
01/200
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01/200
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01/200
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01/200
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01/200
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01/200
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Nitrates (m
g N/L)
Stream
flow (m
3 /s)
Streamflow Nitrate concentration Linear (Nitrate concentration)
Agriculture nutrient loads• Diffuse sources:
− Difficult to measure, quantify and assign to sources
• Trends difficult to assess:− Monthly measurements do not capture peak flows
− High temporal variability
• What was the impact of fertilizer control measures?
Lough Foyle (Mourne)
Ria Formosa (Alportel)
Nitrate Action Plan
1994 2014
1990 2008
No streamflow data
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
y = ‐3E‐05x + 2.28R² = 0.0154
0
0.5
1
1.5
2
2.5
3
3.5
0
100
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01/199
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501
/199
601
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801
/199
901
/200
001
/200
101
/200
201
/200
301
/200
401
/200
501
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601
/200
701
/200
801
/200
901
/201
001
/201
101
/201
201
/201
301
/201
4
Nitrates (m
g N/L)
Stream
flow (m
3 /s)
Streamflow Nitrate concentration Linear (Nitrate concentration)y = ‐8E‐06x + 0.4324
R² = 0.0038
00.20.40.60.811.21.41.61.8
020406080
100120140160
01/199
0
01/199
1
01/199
2
01/199
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01/199
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01/199
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01/199
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01/199
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01/199
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01/199
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01/200
0
01/200
1
01/200
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01/200
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01/200
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01/200
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01/200
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01/200
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01/200
8
Nitrates (m
g N/L)
Stream
flow (m
3 /s)
Streamflow Nitrate concentration Linear (Nitrate concentration)
0
0.5
1
1.5
2
2.5
3
3.5
050
100150200250300350400
01/201
302
/201
303
/201
304
/201
305
/201
306
/201
307
/201
308
/201
309
/201
310
/201
311
/201
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/201
3
Nitrates (m
g N/L)
Stream
flow (m
3 /s)
Streamflow Nitrate concentration
0
1
2
3
4
5
6
01020304050607080
10/200
511
/200
512
/200
501
/200
602
/200
603
/200
604
/200
605
/200
606
/200
607
/200
608
/200
609
/200
6
Nitrates (m
g N/L)
Stream
flow (m
3 /s)
Streamflow Nitrate ‐ official Nitrate ‐ storm
Agriculture nutrient loads• Diffuse sources:
− Difficult to measure, quantify and assign to sources
• Trends difficult to assess:− Monthly measurements do not capture peak flows
− High temporal variability
• What was the impact of fertilizer control measures?
Lough Foyle (Mourne)
Ria Formosa (Alportel)
Storm measurements : Stigter et al., 2006
2013
2005/06
Nitrate Action Plan
1994 2014
1990 2008
No streamflow data
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
Nutrients and aquifers• Lough Foyle: impermeable geology− Delays part of nutrient loads: spread during several months
• Ria Formosa: coastal aquifer− Permeable and already contaminated
− Flows under the coastal system: only part resurfaces
− Delays part of nutrient loads: spread during years/decades
COASTAL SYSTEM
LANDSCAPE
AQUIFER
Fertilization
WWtW WWtW
Stream network
PercolationEspecially N
WWtW: WasteWatertreatment Works
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
COASTAL SYSTEM
LANDSCAPE
AQUIFER
Fertilization
WWtW WWtW
Stream network
?Sediments
OCEAN
PercolationEspecially N
Nutrients and aquifers• Lough Foyle: impermeable geology− Delays part of nutrient loads: spread during several months
• Ria Formosa: coastal aquifer− Permeable and already contaminated
− Flows under the coastal system: only part resurfaces
− Delays part of nutrient loads: spread during years/decades
WWtW: WasteWatertreatment Works
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
Nutrient load assessment strategy• Calculate daily loads and assess sources:
− Wastewater: direct measurements− Agricultural loads: hydrological model SWAT− Aquifer loads (Ria Formosa): measurements on the Ria Formosa sediment bed
Lough Foyle→ 11 WWtW→ SWAT: 330 landscape units in 29 streams→ Representative year: 2014
Ria Formosa→ 7 WWtW→ SWAT: 331 landscape units
in 50 streams→ Representative year:
10.2007 to 09.2008
WWtW: WasteWatertreatment Works
Sediment measurements:
Leote et al., 2008
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
SWAT: Soil and Water Assessment Tool
Stream
CLIMATEHUMAN
MANAGEMENT
Plantgrowth
Hydrology
Nutrientcycling
Water and nutrientexport
LAND PHASE(for each landscape unit)
ROUTING PHASE
Water and nutrient in‐stream processes
Lake andreservoirprocesses
WATERSHED OUTPUT
Wastewater discharges
daily Δt
Landscape unit: unique combination of stream location, land cover, soil type and slope
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
Calibration & validation• Measurements do not capture the major peaks, especially in Ria Formosa
− Streamflow: good model performance− Nutrients: model not easy to evaluate; best available estimate
0
100
200
300
400
500
600
01/200
404
/200
407
/200
410
/200
401
/200
504
/200
507
/200
510
/200
501
/200
604
/200
607
/200
610
/200
601
/200
704
/200
707
/200
710
/200
701
/200
804
/200
807
/200
810
/200
801
/200
904
/200
907
/200
910
/200
901
/201
004
/201
007
/201
010
/201
001
/201
104
/201
107
/201
110
/201
101
/201
204
/201
207
/201
210
/201
201
/201
304
/201
307
/201
310
/201
301
/201
404
/201
407
/201
410
/201
4
Stream
flow (m
3 /s)
Measured Simulated
0
10
20
30
40
50
60
01/200
404
/200
407
/200
410
/200
401
/200
504
/200
507
/200
510
/200
501
/200
604
/200
607
/200
610
/200
601
/200
704
/200
707
/200
710
/200
701
/200
804
/200
807
/200
810
/200
801
/200
904
/200
907
/200
910
/200
901
/201
004
/201
007
/201
010
/201
001
/201
104
/201
107
/201
110
/201
101
/201
204
/201
207
/201
210
/201
201
/201
304
/201
307
/201
310
/201
301
/201
404
/201
407
/201
410
/201
4
Nitrate (ton
N)
Measured Simulated
00.51
1.52
2.53
3.54
4.55
01/200
404
/200
407
/200
410
/200
401
/200
504
/200
507
/200
510
/200
501
/200
604
/200
607
/200
610
/200
601
/200
704
/200
707
/200
710
/200
701
/200
804
/200
807
/200
810
/200
801
/200
904
/200
907
/200
910
/200
901
/201
004
/201
007
/201
010
/201
001
/201
104
/201
107
/201
110
/201
101
/201
204
/201
207
/201
210
/201
201
/201
304
/201
307
/201
310
/201
301
/201
404
/201
407
/201
410
/201
4
Phosph
ate (ton
P)
Measured Simulated
020406080
100120140160
10/200
1
12/200
1
04/200
2
07/200
2
10/200
2
01/200
3
04/200
3
07/200
3
10/200
3
01/200
4
04/200
4
07/200
4
10/200
4
01/200
5
04/200
5
07/200
5
10/200
5
01/200
6
04/200
6
07/200
6
10/200
6
01/200
7
04/200
7
07/200
7
10/200
7
01/200
8
04/200
8
07/200
8
Stream
flow (m
3 /s)
Measured Simulated
00.51
1.52
2.53
3.54
4.55
10/200
1
12/200
1
04/200
2
07/200
2
10/200
2
01/200
3
04/200
3
07/200
3
10/200
3
01/200
4
04/200
4
07/200
4
10/200
4
01/200
5
04/200
5
07/200
5
10/200
5
01/200
6
04/200
6
07/200
6
10/200
6
01/200
7
04/200
7
07/200
7
10/200
7
01/200
8
04/200
8
07/200
8
Nitrate (ton
N)
Measured Simulated
00.20.40.60.81
1.21.41.61.82
10/200
1
12/200
1
04/200
2
07/200
2
10/200
2
01/200
3
04/200
3
07/200
3
10/200
3
01/200
4
04/200
4
07/200
4
10/200
4
01/200
5
04/200
5
07/200
5
10/200
5
01/200
6
04/200
6
07/200
6
10/200
6
01/200
7
04/200
7
07/200
7
10/200
7
01/200
8
04/200
8
07/200
8
Phosph
ate (ton
P)
Measured Simulated
Lough Foyle (Mourne) Ria Formosa (Alportel)
Stream
flow
Nitrate
Phosph
ate
Stream
flow
Nitrate
Phosph
ate
2004 2014 2001 2008
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
0
100
200
300
400
500
600
01/200
404
/200
407
/200
410
/200
401
/200
504
/200
507
/200
510
/200
501
/200
604
/200
607
/200
610
/200
601
/200
704
/200
707
/200
710
/200
701
/200
804
/200
807
/200
810
/200
801
/200
904
/200
907
/200
910
/200
901
/201
004
/201
007
/201
010
/201
001
/201
104
/201
107
/201
110
/201
101
/201
204
/201
207
/201
210
/201
201
/201
304
/201
307
/201
310
/201
301
/201
404
/201
407
/201
410
/201
4
Stream
flow (m
3 /s)
Measured Simulated
020406080
100120140160
10/200
1
12/200
1
04/200
2
07/200
2
10/200
2
01/200
3
04/200
3
07/200
3
10/200
3
01/200
4
04/200
4
07/200
4
10/200
4
01/200
5
04/200
5
07/200
5
10/200
5
01/200
6
04/200
6
07/200
6
10/200
6
01/200
7
04/200
7
07/200
7
10/200
7
01/200
8
04/200
8
07/200
8
Stream
flow (m
3 /s)
Measured Simulated
00.51
1.52
2.53
3.54
4.55
10/200
511
/200
512
/200
501
/200
602
/200
603
/200
604
/200
605
/200
606
/200
607
/200
608
/200
609
/200
6
Nitrate (ton
N)
Measured Simulated
Calibration & validation• Measurements do not capture the major peaks, especially in Ria Formosa
− Streamflow: good model performance− Nutrients: model not easy to evaluate; best available estimate
Lough Foyle (Mourne)
Stream
flow
Stream
flow
0
0.1
0.2
0.3
0.4
0.5
0.6
10/200
511
/200
512
/200
501
/200
602
/200
603
/200
604
/200
605
/200
606
/200
607
/200
608
/200
609
/200
6
Phosph
ate (ton
P)
Measured Simulated
Nitrate Phosphate
Ria Formosa (Alportel)
00.20.40.60.81
1.21.41.61.82
01/201
302
/201
303
/201
304
/201
305
/201
306
/201
307
/201
308
/201
309
/201
310
/201
311
/201
312
/201
3
Phosph
ate (ton
P)
Measured Simulated
0
10
20
30
40
50
60
01/201
302
/201
303
/201
304
/201
305
/201
306
/201
307
/201
308
/201
309
/201
310
/201
311
/201
312
/201
3
Nitrate (ton
N)
Measured Simulated
Nitrate Phosphate
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
51%48%
1%Area
72%
25%
3% 0%
Total Nitrogen
WWtW
Cropland
Rangeland
Pasture61%
33%
6%
0%
Total Phosphorus
WWtW
Cropland
Rangeland
Pasture
Nutrient budgets & sources• Agriculture loads dominate in Lough Foyle:− large watershed, no aquifer losses− high N mobilization
• N/P ratio:− Redfield Ratio (mass): N/P = 7.2− Lough Foyle: N/P = 19.8− Ria Formosa: N/P = 5.6
3%
43%54%
Area2%
7%
20%
71%
Total Nitrogen
WWtW
Cropland
Rangeland
Pasture
17%
7%
39%
37%
Total Phosphorus
WWtW
Cropland
Rangeland
Pasture
Lough Foyle
Ria Formosa
System Nitrogen PhosphorusAgriculture per area (kg/ha.yr)
Lough Foyle 21.9 0.9
Ria Formosa 2.8 0.7
Aquifer: 7%Stream: 21% Aquifer: 3%
Stream: 36%
N = 8 332 ton/yr P = 421 ton/yr
N = 642 ton/yr P = 115 ton/yr
3709 Km2
745 Km2
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
• Loads concentrated in Autumn and Winter:− N: regular baseflow(groundwater) + stormflow peaks
− P: stormflow peaks
• Seasonality:− Autumn/Winter:dominated by watershed and N
− Summer: dominated by wastewater, N&P equilibrium
Lough Foyle: time patterns
0
20
40
60
80
1000
50
100
150
200
01/201
4
02/201
4
03/201
4
04/201
4
05/201
4
06/201
4
07/201
4
08/201
4
09/201
4
10/201
4
11/201
4
12/201
4
Rainfall (m
m)
Total N
(ton
N/d
y)
WWtW Watershed Rainfall
0
20
40
60
80
1000
5
10
15
20
01/201
4
02/201
4
03/201
4
04/201
4
05/201
4
06/201
4
07/201
4
08/201
4
09/201
4
10/201
4
11/201
4
12/201
4
Rainfall (m
m)
Total P
(ton
P/d
y)
WWtW Watershed Rainfall
0
20
40
60
80
1000%
20%
40%
60%
80%
100%
01/201
4
02/201
4
03/201
4
04/201
4
05/201
4
06/201
4
07/201
4
08/201
4
09/201
4
10/201
4
11/201
4
12/201
4
Rainfall (m
m)
WWtW
fractio
n
Rainfall Total N Total P
0
20
40
60
80
100020406080
100120140160180
01/201
4
02/201
4
03/201
4
04/201
4
05/201
4
06/201
4
07/201
4
08/201
4
09/201
4
10/201
4
11/201
4
12/201
4
Rainfall (m
m)
N/P
ratio
Rainfall N/P Foyle Redfield ratio
Rainfall Total N Total P
Lough Foyle
• Agricultural loads cause:seasonality, irregularity and N dominance
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
0
50
100
150
2000
10
20
30
40
50
10/200
7
11/200
7
12/200
7
01/200
8
02/200
8
03/200
8
04/200
8
05/200
8
06/200
8
07/200
8
08/200
8
09/200
8
Rainfall (m
m)
Total N
(ton
N/d
y)WWtW Aquifer Watershed Rainfall
0
50
100
150
2000
5
10
15
20
10/200
7
11/200
7
12/200
7
01/200
8
02/200
8
03/200
8
04/200
8
05/200
8
06/200
8
07/200
8
08/200
8
09/200
8
Rainfall (m
m)
Total P
(ton
P/d
y)
WWtW Aquifer Watershed Rainfall
0
50
100
150
2000%
20%
40%
60%
80%
100%
10/200
7
11/200
7
12/200
7
01/200
8
02/200
8
03/200
8
04/200
8
05/200
8
06/200
8
07/200
8
08/200
8
09/200
8
Rainfall (m
m)
WWtW
fractio
n
Rainfall Total N Total P
0
50
100
150
20005
10152025303540
10/200
7
11/200
7
12/200
7
01/200
8
02/200
8
03/200
8
04/200
8
05/200
8
06/200
8
07/200
8
08/200
8
09/200
8
Rainfall (m
m)
N/P
ratio
Rainfall N/P R Formosa Redfield ratio
• Relatively regular loads, with irregular stormflow peaks
• Small seasonality:− Autumn to Spring:dominated by wastewater
− … except for a few days dominated by watershed stormflow
− Summer: dominated by wastewater
Ria Formosa: time patterns
• Agricultural loads cause:high irregularity (with small seasonality)
Ria Formosa
2007 2008 2007 2008Rainfall Total N Total P
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
Streams (ton N)WWtW (ton N)
0
50
100
150
2000
10
20
30
40
50
10/200
7
11/200
7
12/200
7
01/200
8
02/200
8
03/200
8
04/200
8
05/200
8
06/200
8
07/200
8
08/200
8
09/200
8
Rainfall (m
m)
Total N
(ton
N/d
y)
WWtW Aquifer Watershed Rainfall
Ria Formosa: spatial patterns• Contrast between annual and stormflow loads− annual: mostly western RF – WWtW− stormflow: mostly eastern RF – rivers− more sensitive coastal area due to restricted ocean exchange
• Agricultural loads may cause localized, short‐term problems
Ria Formosa
N: 72%P: 65%
N: 5%P: 9%
N: 23%P: 26%
N: 22%P: 20%
N: 22%P: 30%
N: 56%P: 50%
Annual loads
8 to 12‐Apr‐2008
Nutrient WWtW Watershed Total
Nitrogen 1.6% 30% 8%
Phosphorus 1.6% 44% 19%
Fraction of annual load in 8 to 12‐Apr‐2008
WWtW (ton N) Streams (ton N)
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
Agricultural impactsLough Foyle nutrient loads• Wet climate: strong seasonality + peaks after rainfall
• Wet climate + Pasture:− Abundant water mobilizes N− Vegetation cover: low P exports
• Simple geography: most loads from the estuary of River Foyle
• Simple geology: strong N load seasonality via baseflow
Ria Formosa nutrient loads• Dry climate: loads concentrated in peaks after rainfall
• Dry climate + Orchards:− Less water available to mobilize N− Lower vegetation cover: P exports
• Complex geography: load locations vary with weather
• Complex geology: not all N loads reach the coastal system
Lough Foyle
Ria Formosa
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
Nutrient loads and aquaculture• Aquaculture and nutrients: an ambivalent relation
− Nutrients support primary production and hence food, but…− Excessive loads can limit aquaculture through eutrophication
• Lough Foyle: low impacts despite high N loads; P limitation?
• Ria Formosa: occasional impacts due to agriculture− High loads counteracted by strong exchange with ocean…− … but occasional acute water quality issues: stormflow loads?
• Wastewater control should be supplemented with agricultural nutrient management
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
Agricultural nutrient management• Water Framework Directive quality goals might require load reduction to streams and coastal systems
• Challenges for agricultural nutrient management:− Monitoring: often too infrequent to understand issues− Fertilization control: limited by plant requirements− Agricultural abandonment: negative economic impacts− Long‐term contamination: nutrient stocks remain in soils and groundwater decades after fertilization control
• Innovative solutions: limiting the connectivity between fields and streams through landscape management
http://connecteur.info/
Nunes and Ferreira: Agricultural and Urban Nutrient Loads to Coastal Systems
Conclusions• Agricultural nutrient loads can impact coastal systems
• With wastewater treatment widespread, nutrient management should focus on agriculture− Often as important as wastewater loads− Irregular loads, complex impacts− More challenging to monitor and control
• If farmers (land and sea) understand their watersheds, they can participate on nutrient management decisions