“estimated total nitrogen deposition and rainwater composition measured ... · pdf...
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EH ConradiePh.D student
“Estimated total nitrogen deposition and rainwater composition measured in the Kruger National Park”
March 2011
Outline
• Project motivation and objectives
• Current measurements
• Importance of nitrogen deposition
• Results– Gaseous measurements (monthly)– Aerosols (monthly)– Rainwater analyses (monthly)– Total deposition (monthly)– Rainwater (annual) compared to other sites
• Conclusions
Project motivation and objectives
• KNP project title: “Long-term spatial and temporal deposition of biogeochemically important trace species over southern Africa (DEBIT S)”
• DEBITS began in 1990 – originally an IGAC task entit led “Composition and Acidity of Asian Precipitation” (CAAP)
• Changed to DEBITS in 1994 when African (IDAF) and S outh American (LBA) networks joined the initiative
• The program is driven by scientific questions relat ed to global atmospheric chemistry
• DEBITS SA was developed to monitor deposition and p otential long-term impact of important trace species emitted in southern Africa
• Atmospheric deposition can either be a source of to xic substances, or a source of nutrients for the ecosystem.
• Biomass burning, land use changes and industrial ac tivities lead to important emissions. Emissions may result in adverse effects on vegetation/water/soil systems.
Project motivation and objectives
• To determine the regional scale atmospheric budgets of key pollutant species
• To measure the long term atmospheric removal rates through dry and wet deposition of biogeochemical important trace specie s
• To provide data for an integrated scientific assess ment of atmospheric C, S and N cycles at regional scale
• To provide data on deposition that can be related t o impact studies, with special focus on N and other key species and their impacts on ecosystems and hydrology
Current measurements
Passive gas sampling (month) for SO2, NO2, NH3, HNO3 and O3
• Gas concentrations
pH, Conductivity, Inorganic and Organic major ions(Cl- , NO3
- , SO4 2-, HCO3
- , CO3 2-, Na+ , NH4
+, K+, Mg 2+ , Ca 2+, HCOOH, CH3COOH, C2H5COOH)
Wet-only sampling (events), preservation by a biocide or by freezing US EPA quality criteria + annual analytical laboratory performance (WMO)
• Chemical composition of precipitation
Monthly sampling – PM2.5 and PM10
Inorganic and organic major ions(Cl-, NO3
-, SO4 2-, HCO3
-, CO3 2-, Na+, NH4
+, K+, Mg 2+, Ca2+, HCOOH, CH3COOH, C2H5COOH)
Particulate carbon (TC, OC and BC)
• Chemical composition of aerosols
Importance of nitrogen deposition
• Negative effects of nitrogen deposition include aci dification (acid rain), eutrophication (algal blooms) and soil leach ing
• The atmosphere is a critical environment for the ni trogen cycle (cascade effect)
• Nitrogen deposition is essential to the function of terrestrial ecosystems – therefore essential in regulating the g lobal carbon cycle
• Direct toxicity from wet deposition of N is rare, w hile dry deposition of NH3 can damage plants (specifically the stomata)
• Literature results show that atmospheric nitrogen f ixing ability may vary with age of plants and soil nutrient condition s (S.M. Jacobs et al., 2007)
Results: Gaseous measurements (monthly)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
Dep
ositi
on (
kg N
/ ha
/ m
onth
) (H
NO
3va
lues
on
seco
ndar
y ax
is)
Monthly concentrations at Skukuza for 2009
NH3 NO2 HNO3 2 per. Mov. Avg. (HNO3)
Results: Gaseous measurements (monthly)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
Dep
ositi
on (
kg N
/ ha
/ m
onth
) (H
NO
3va
lues
on
seco
ndar
y ax
is)
Monthly concentrations at Skukuza for 2009
NH3 NO2 HNO3 2 per. Mov. Avg. (NH3)
Results: Gaseous measurements (monthly)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
Dep
ositi
on (
kg N
/ ha
/ m
onth
) (H
NO
3va
lues
on
seco
ndar
y ax
is)
Monthly concentrations at Skukuza for 2009
NH3 NO2 HNO3 2 per. Mov. Avg. (NO2)
Results: Aerosol measurements (monthly)
0.000
0.020
0.040
0.060
0.080
0.100
0.120
0.140
Dep
ositi
on v
alue
s (k
g N
/ ha
/ m
onth
)
Skukuza particulate nitrogen (max values)
PM 2.5 NO3- PM 2.5 NH4+ PM 10 NO3- PM 10 NH4+
Results: Rainwater analyses
0
10
20
30
40
50
60
70
80
90
Rai
n ga
uge
read
ing
(mm
)
Skukuza rainfall measured by SAWS
Results: Rainwater analyses (monthly)
0
0.05
0.1
0.15
0.2
0.25
0.3
Dep
ositi
on v
alue
s (
Kg
N /
ha /
mon
th)
Skukuza wet deposition
N in NH4+ N in NO3-
Results: Total deposition (monthly)
0.000
0.200
0.400
0.600
0.800
1.000
1.200
Dep
ositi
on v
alue
s (k
g N
/ ha
/ m
onth
)
Monthly total N deposition
Gaseous Particulate Raiwater Total
Results: Rainwater (annual) compared to other sites
Skukuza 2009 Vaal Pukke 2009 Amersfoort 2009 Louis Trichardt 2009
Wet Deposition Wet Deposition Wet Deposition Wet Depos ition
Ions kg.ha-1.yr-1 kg.ha-1.yr-1 kg.ha-1.yr-1 kg.ha-1.yr- 1
pH 4.75 4.44 4.33 4.61
H+ 0.142 0.465 0.390 0.193
Na+ 1.715 0.724 3.747 1.663
NH4+ 1.243 5.192 2.951 1.089
(N in NH4+) 0.965 4.029 2.290 0.845
K+ 0.683 0.728 1.166 0.203
Ca2+ 0.409 3.399 1.202 0.425
Mg2+ 0.209 0.628 0.258 0.217
NO3- 4.602 11.647 9.520 3.043
(N in NO3-) 1.039 2.630 2.150 0.687
Cl- 3.149 1.737 6.449 2.926
SO42- 5.585 29.195 22.214 4.890
(S in SO42-) 1.861 9.725 7.400 1.629
HCOO- 0.999 4.172 1.679 2.235
CH3COO- 0.032 0.453 0.438 0.086
Nr of events 39 76 51 26
Total rainfall (mm) 604.50 857.50 708.00 840.00
Closing comments
• Monthly total nitrogen deposition ranges between a minimum of 0.151 kg N / ha / month at the end of the dry season, to a maximum value of 0.968 kg N / ha / month at the beginning of summer (during wet season)
• Gasous deposition and wet deposition contributes th e most to the total annual nitrogen deposition, while particulate s are significantly less.
• Total nitrogen deposition in the KNP was calculated to be around 5.343 kg N / ha / yr for 2009
• Rainwater comparisons showed that total wet nitroge n deposition are highest in the Vaal Triangle, followed by the Highv eld, Skukuza and Louis Trichardt
Acknowledgements