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

10

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”

18

Institute for AgroEcology-IFA Fent, G., Kubiak, R.

Fate and transport in air

Thank you for your attention !