1
Large scale outdoor wind tunnel experiments to investigate the volatilisation and short range
transport of Lindane
Institute for AgroEcology-IFA Fent, G., Kubiak, R.
Fate and transport in air
Outline:
• Background and motivation
• Test system presentation
• Results
• Summary and “Take Home Messages”
2
LRT SRT
0-100% emission?
DT50 air?
Non-target pesticide contamination via dry/wet deposition ?
How to measure volatilization of pesticides?
Laboratory Field
Artifical
surfaces
Plant
surfaces
Surface area
up to 1 m²
Surface area
few cm²
Surface area
up to 10000 m²
3
How to measure volatilization of pesticides?
Reproducibility
Transferability
Validity
Reality
How to fill the test system gap between Lab and Field?
Nearly realistic outdoor conditions, but more reproducible boundary
conditions in order to identify factors influencing volatilization of pesticides
at field scale
Semi-outdoor wind tunnel
4
Semi- outdoor wind tunnel bridging Lab to Field?
Adjustable wind speed yes no
Constant wind direction yes no
Air flow / atmospheric stability laminar/artificial chaos
Outdoor temperature/humidity fluctuation yes yes
Natural daylight yes (80%) yes
Natural plant canopy yes yes
Application according GAP yes yes
Duration application 30 sec > 5 min
Wash-off by rainfall no yes
Photo degradation no yes
Field studies to assess the volatilisationbehaviour of pesticides can provide
• e.g. the order of magnitude of volatilisation under the specifictest conditions
• but suitable only to a limited extent to investigate influencingfactors under field conditions
Snapshot-results
5
Outline:
• Background and motivation
• Test system presentation
• Results
• Summary and “Take Home Messages”
The Test System - Wind tunnel
Steady-going adjustable wind speed in one direction
100 m² crop covered plot (25 x 4 m) under outdoor conditions
Equilibration air flow (5 m)
Sampling area 25 mTarget area 25 m
6
The wind engine
• 26 synchron running axial flow fans (40 kW)
• Wind speed from 0.1 bis 5.0 m-s
Applications to winter wheat
BBCH Code 51-69, > 90 % interception, LAI up to 8
7
Applications to sugar beet
BBCH Code 39, > 90 % interception, LAI up to 4
Lindane as Test Substance. Why?
• well known pesticide with high volatilization potential (90% within 24 h from plants)
• was investigated both, at laboratory and field scale
• easily to extract from Tenax tubes, simple detection and quantification via GC-ECD
• temperature dependency was demonstrated in lab-studies (46 to 80% / 15 vs. 23°C)
• stable in the environment (no competitive processes like photo degradation)
• Due to the high volatilization potential (about 90% within 24 h from plants) of Lindane, it can be used in the wind tunnel test system as an internal standard for the classification of pesticides with unknown emission behavior
8
Sampling area sampling design
-25 0 1 3 5 10 15 20 25 m
0
1
2
3
m
Treated crop
Sampling area sampling design
9
Sampling intervals and analytical methods
Analytical method: GC-ECD
Time dependent sampling scheme:
1, 3, 6, 12 and 24 h after application
Experimental set up and basic parameters
• 15 Wind tunnel experiments with an application rate corresponding to 200 g/ha lindane
• All applications according GAP to crops (WW and SB) with > 90% spray interception
• 9 applications to SB and 6 applications to WW
• 11 experiments with wind speed 2 m/sec and 4 experiments with 4 m/sec
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Results within the scope of the experimental design
• Wind tunnel characteristics
• Volatilization of Lindane
• Influence of temperature and crop
• Influence of wind speed
• Time dependent volatilization behaviour
Whether conditions field vs. wind tunnel
Air Temperature Wind Tunnel Versus Outside
10
12
14
16
18
20
22
24
0 4 8 12 16 20 24
Hours after Treatment
[°C
]
Wind Tunnel: Mean = 14.8 °C
Outside Wind Tunnel: Mean = 14.4 °C
Air Humidity Wind Tunnel Versus Outside
40
50
60
70
80
90
100
0 4 8 12 16 20 24
Hours after Treatment
[% re
lativ
e]
Wind Tunnel: Mean = 82.1%
Outside Wind Tunnel: Mean = 86.8%
Windspeed Wind Tunnel Versus Outside
0
2
4
6
8
0 4 8 12 16 20 24
Hours after Treatment
[m/s
ec]
Wind Tunnel: Mean = 2.1 m/s
Outside Wind Tunnel: Mean = 3.2 m/s
Theoretical outdoor wind profile and tunnel profile, incoming flow 2 m/s
0.0
0.5
1.0
1.5
2.0
2.5
0.0 0.5 1.0 1.5 2.0
z [m]
u [m
/s] y = 1
y = 0y = -1theor.
11
00.20.40.60.811.21.41.6
z [m]
2.0-2.5
1.5-2.0
1.0-1.5
0.5-1.0
0.0-0.5
-2 -1 0 1 200.20.40.60.811.21.4
z [m]
4.0-5.0
3.0-4.0
2.0-3.0
1.0-2.0
0.0-1.0
[m s-1]
2-dimensional wind profile (cross-section in the mid of the wind tunnel)
2 m/sec
4 m/sec
2-dimensional wind profile (cross-section along the wind tunnel)
0
1
1
2
2
3
0 5 10 15 20 25 30 35 40 45 50
Downwind distance from the fan unit [m]
Win
d sp
eed
[m s-
1]
0.3 m height0.6 m height1 m height1.6 m height
Winter wheat 0.8 m height
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Unit Mean Min MaxAir temperatur °C 14.0 4.4 24.5Air humidity % 72.5 50.4 88.9Leaf wetness timeafter application
h 2.1 0.45 5.63
Total solar energy kW/m² 70.5 13.1 134.8
Range of climatic conditions24-h mean values (n = 15)
Cumulative Lindane (24 h) trapped by Tenax at 30 cm measuring line
0
5
10
15
20
25
30
35
40
45
sb_I_
02
sb_II
_02
sb_II
I_02
ww_I_03
ww_II_0
3
ww_III_0
3
ww_IV_0
3
ww_V_0
3
ww_VI_0
3
sb_I_
03
sb_II
_03
sb_II
I_03
sb_IV
_03
sb_V
_03
sb_V
I_03
[µg
tota
l afte
r 24
h]
o
Mean
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Pesticide X (Pa 3.6 . 10-4) volatilization in relation to the Lindane (Pa 5.6 . 10-3) volatilization (internal standard)
0
5
10
15
20
25
30
35
40
ww_I_03 ww_II_03 ww_IV_03 sb_I_03 sb_II_03
Am
ount
of s
ubst
ance
trap
ped
by T
enax
[µg]
:
Relative height distribution of volatilized Lindane
0
10
20
30
40
50
60
70
80
90
ww_I_03
ww_II_0
3
ww_III_0
3
ww_IV_0
3
ww_V_0
3
ww_VI_0
3
sb_I_0
3
sb_II_
03
sb_III
_03
sb_IV
_03
sb_V_0
3
sb_VI_0
3
Rel
ativ
e di
strib
utio
n of
Lin
dane
in th
e ai
r [%
]
300 cm height; mean 8.8%160 cm height; mean 28.0%30 cm height; mean 63.2%
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Spatial distribution of volatilised Lindane
0
20
40
60
80
100
120
140
160
180
200
0 2 4 6 8 10 12 14 16 18 20
Downwind distance from treated field [m]
Rel
ativ
e sp
atia
l Lin
dane
dis
tribu
tion
[%]Height [cm]
30160300
Treated crop
Temperature dependency of Lindane volatilisation
0
10
20
30
40
50
60
70
80
90
4 6 8 10 12 14 16 18 20 22 24
Mean air temperature [°C]
Tota
l Lin
dane
trap
ped
30
cm H
eigh
t [µg
in 2
4 h]
.
Sugar beet at 2 m/sec
(linear R² = 0.1053; n=7)
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Temperature and crop dependency of Lindanevolatilisation (independent t-tests at 95%-level)
Non-significantSugar beet (n=3)
2 m/sec16.3 °C
Non-significant
Sugar beet (n=4)2 m/sec6.8 °C
Winter wheat (n=3)2 m/sec16.2 °C
Sugar beet (n=3)2 m/sec14.9 °C
Wind speed dependency of Lindane volatilisation
0,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
1,6
1,8
2,0
WW I vs. WW II WW III vs. WW IV SB I vs. SB II SB III vs. SB IV
Fact
or
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Time dependent volatilisation behaviour of LindaneMean ( n = 15) relative decrease of volatilisation rate
y = 100e-0,1243x
R2 = 0,9578
-10
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10 12 14 16 18 20 22 24Time after application [h]
Rel
ativ
e va
riatio
n of
Lin
dane
em
issio
n in
rela
tion
to th
e 1
st-ho
ur e
miss
ion
[%]
Time dependent volatilisation behaviour of Lindanein comparison to pesticide X
0
0,2
0,4
0,6
0,8
1
1,2
Pestici
de X
Lindan
e
Pest
icid
e X
tim
e w
eigh
ted
emis
sion
[µg
m-3]
:
0
2
4
6
8
10
12
14
16
18
20
Lind
ane
time
wei
ghte
d em
issi
on [µ
g m-3
] .
0-1 HAT1-3 HAT3-6 HAT6-12 HAT12-24 HAT
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Time dependent volatilisation behaviour of Lindaneas a function of crop
0
10
20
30
40
50
60
70
80
90
100
Sugar beet (n=9) Winter wheat (n=6)Rel
ativ
e de
crea
se o
f Lin
dane
em
issi
on in
rela
tion
to 1
-h e
mis
sion
0-1 HAT1-3 HAT3-6 HAT6-12 HAT12-24 HAT
• An semi outdoor wind tunnel test system was described filling the gab between laboratory- and field volatilisation studies
• Volatilisation potential of pesticides with unknown emission behaviour can be classified by simultaneously applied Lindane as internal standard
• Short range dispersion of volatilized Lindane downwind from the edge of the field was characterized
• Volatilisation of Lindane was no function of temperature (range 6° - 18 ° C)
• Duplication of wind speed from 2 m/sec to 4 m/sec increased Lindanevolatilisation by a mean factor of about 1.4
• With few exceptions the maximum volatilisation rates were observed within the 1st hour after application and significantly decreased in the following to about 10% in the 12-24 h period in relation to the 1st-hour rate
• Amount of volatilization was not crop specific but emission as a function of time after treatment was crop and pesticide specific
Summary and “Take Home Messages”
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Institute for AgroEcology-IFA Fent, G., Kubiak, R.
Fate and transport in air
Thank you for your attention !