ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF ENFORCEMENT
EPA -330/2-77- 014
HURBICIDE	USU
SUPERIOR	AND	CHIPPEWA
MINNESOTA
(JULY
NATIONAL ENFORCEMENT INVESTIGATIONS CENTER
DENVER, COLORADO
and
REGION V - CHICAGO
rtO S7*.
OCTOBER 1977

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ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF ENFORCEMENT
EPA-330/2-77-014
HERBICIDE USE OBSERVATIONS
SUPERIOR AND CHIPPEWA NATIONAL FORESTS
MINNESOTA
(July 1977)
October 1977
National Enforcement Investigation Center - Denver
and
Region V - Chicago

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CONTENTS
I INTRODUCTION		1
II SUMMARY AND CONCLUSIONS				3
General 		3
Specific		3
III DESCRIPTION OF STUDY AREA		5
IV USE OBSERVATIONS		6
Pre-application 		6
Application 		8
Post-application 		9
V SAMPLING DEVICES AND METHODS 		13
TABLES
1	Results of Spray Drift and Environmental Sampling. Superior
National Forest, Minnesota
2	VMD> Deposition Density and Drift Distances. SuDerior National
Forest, Minnesota
3	Results of Spray Drift and Environmental Sampling. Chippewa
National Forest, Minnesota
4	VMD> Deposition Density and Drift Distances, Chippewa National
Forest
FIGURES
1	Sampling Stations, Superior National Forest
2	Sampling Stations, Chippewa National Forest

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HERBICIDE USE OBSERVATIONS
SUPERIOR AND CHIPPEWA NATIONAL FORESTS, MINNESOTA
JULY 1977
I. INTRODUCTION
Silviculture includes the practice of controlling forest establishment,
composition and growth. It is a continuous management process that begins
when mature timber is harvested and the site is prepared for a new crop
of trees. Depending on many factors, a forester often uses pesticides
to prepare an area for reforestation. Herbicides are widely used to control
undesirable plant species and weeds in reforestation areas.
To delineate the actual and potential environmental damage caused by
the aerial application of 2,4-D on forest areas, the EPA National
Enforcement Investigations Center (NEIC) and Region V conducted an
herbicide use observation study. This study was conducted in the Superior
and Chippewa National Forests in Northern Minnesota, from July 12 through
15, 1977. The objectives of the study were as follows:
1.	Determine that applications of 2,4-D were performed
consistent with Federal Insecticide, Fungicide and Rodenticide
Act (FIFRA) regulations and appropriate state codes.
2.	Determine that applications of 2,4-D were performed consistent
with U. S. Forest Service Environmental Analysis Reports (EAR)
and Environmental Impact Statement (EIS) recommendations.
3.	Determine the extent and environmental effects of herbicide
movement from target areas onto non-target areas.
The study determined residue levels of 2,4-D in ambient air, vegetation,
soil and water. Various types of spray droplet cards and high-volume air

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2
sampling devices were used to characterize spray drift. While storage
and mixing of the material were not observed, on-site handling and loading
operations were.

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II. SUMMARY AND CONCLUSIONS
3
General
In July 1977, the NEIC and Region V conducted a four-day study in two
Northern Minnesota national forests to monitor the aerial application of
2,4-D used to control undesirable plant species. On-site observations,
combined with the use of various monitoring techniques, enabled the EPA
to determine user compliance with label instructions and to evaluate
both beneficial and harmful effects associated with the treatment program.
Technologically it is impossible to aerially spray with "no drift - no
contamination", therefore, the forest sprayings observed by EPA were
evaluated to determine lasting or other major adverse impacts on the
envi ronment.
On-site observations revealed that the applicator used a registered
chemical herbicide consistent with Federal regulations.
Environmental sampling showed the use of 2,4-D resulted in contamination
of non-target forest land (340 yg/gm) and waterways (1.4 yg/1).
The most valuable techniques used to document the practices and
environmental effects of the aerial applications were on-site evaluations by
trained observers and analyses of spray-drift cards, air, water and soil to
determine drift and 2,4-D residues at the study sites.
Specific
1.	Pre-application sampling revealed no 2,4-D contamination of either
of the two national forest study sites.
2.	Possible human health hazards were observed during on-site loading
operations. Workers handling the herbicides wore no safety apparel.

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4
At a minimum, those individuals should have been wearing long-sleeved
shirts and rubber gloves.
3.	In the Superior and Chippewa National Forests no visible drift was ob-
served beyond the spray sites. However, factors observed that con-
tributed to overspray and contamination of the surrounding area were:
(a)	difficulty in delineating the physical boundaries of the area be-
cause insufficient numbers of balloons were used to mark the site, and
(b)	the aircraft pilot flew along the short axis of the area; if he had
flown along the long axis of the site he would have used existing bal-
loons more effectively. Drift contamination of the surrounding areas
was kept to a minimum: maximum drift distance in the Superior Forest
was about 6 meters, and in the Chippewa Forest about 100 meters.
4.	Observations and analyses by NEIC and Region V personnel after che
forests were treated revealed that an application rate of eight gallons
per acre of 2,4-D provided extensive coverage of plant surfaces, thus
insuring good plant kill. Chemical data from the Superior Forest
showed that less than 1% of the herbicide penetrated the forest
canopy and reached the ground.
5.	Laboratory analyses revealed a spray-droplet Volume Median Diameter
(VI1D) exceeding 1,000 microns for both forests. Such large-sized
droplets considerably reduce the propensity for drift, as well as
reducing drift to an average distance of less than 3.5 meters.
6.	On-site observations and residue analyses for 2,4-D in air, water and
soil and on high volume air sampler filters and Kromecote cards,
coupled with spray-drift evaluations were valuable techniques for
monitoring the use of 2,4-D.

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III. DESCRIPTION OF STUDY AREA
5
Superior and Chippewa National Forests, located in the Arrowhead
region of Northern Minnesota, are two primary multiple-use forests in the
Midwest. Timber production and recreation are among the major uses of
these forests.
Two sites were selected for the observation study: (1) Superior
National Forest, Gunflint District, about 25 miles north (T63N, R1E, Sections
7 and 18 and T63N, R1W, Sections 12 and 13) of Grand Marais, Minnesota.
The 81-acre spray area is characterized by heavy timber and brush growth,
with the spray site being dominated by juvenile aspen and brush. Private
land borders the north edge of the spray area. (2) Chippewa National
Forest, Marcell District, about 40 miles north (T149N, R25W, Sections 7,
8, 17, 18) of Grand Rapids, Minnesota. The 36-acre spray site is a well
defined stand of juvenile aspen surrounded by a mixture of mature trees.
Heliports close to the spray sites were used to facilitate the loading
of the spray material (the site in the Chippewa National Forest was part
of a spray area).
Sixteen sampling stations were established in the Superior National
Forest (Figure 1) and 29 sampling stations were located in the Chippewa
National Forest (Figure 2). These sampling sites were situated around the
spray area in such a manner that any spray drift or other environmental
effect could be evaluated. Stations were located both on and off the spray
sites and near adjacent v/aterways. Air, vegetation, soil and water were
collected at selected times and locations within this sampling network.
Samples were analyzed to determine the fate of 2,4-D sprayed on the areas
to control undesirable plant species.
*Esteron 99 Concentrate. Dow Chemical Co., EPA registration No. 464-201-AA.

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PRIVATE LAND
POND
NOT TO SCALE
Figure 1. Sampling Stations, Superior National Forest, Minnesota
Spray Site G-5, July 1977

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Figure 2. Sampling Stations,
Spray Site
\
\
NOT TO SCALE
Chippewa National Forest, Minnesota
M-8, July 1977

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IV. USE OBSERVATIONS
6
PRE-APPLICATION
On July 13, 1977, prior to the aerial application of the herbicide
2,4-D, environmental samples were collected from the Superior National
Forest study site to establish background levels. Soil and water samples
from the spray site contained no detectable 2,4-D residues (Table 1).
The same type of samples were collected from the Chippewa National
Forest on July 15, 1977,- a few hours prior to the aerial treatment of
that site. No detectable herbicide residues were found (Table 3).
Prior to the aerial application in both forests, sampling devices to
monitor spray drift were placed around the study sites. These devices
included: high-volume air samplers and spray-droplet cards (Kromecote
cards, Thermofax paper and Linograph paper). Each device is described in
the Methods section of this report.
Meteorological data including wind direction, velocity, air temperature
and humidity were collected. These factors were used to evaluate the
influence of atmospheric conditions on the movement of 2,4-D beyond the
target sites.
At neither forest site was the EPA able to observe the mixing
operations. This operation was conducted at points removed from the spray
areas, with the mix being transported to the spray sites by tank trucks.
Loading operations were performed on site. The vehicle containing the
mix (a 1035 liter tank mounted on a flat-bed truck) was moved onto the
heliport where closed seal couplings were used to attach a heavy gauge

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7
flexible hose between the mix tank and the helicopter spray tank. Approxi-
mately 360 liters of the mix were pumped through the flexible hose into
the aircraft spray tank. A tight seal was maintained throughout the loading
operation and no visible leakage occurred. When the hose was disconnected
a plastic bucket was used to capture the small (approximately 50 ml) volume
of mix that remained in the line. This mix was manually added to the spray
tank.
In cooperation with the Forest Service, a fluorescent dye (Rhodamine
WT) was added to each helicopter load of mix at a concentration of about
2,000 yg/l. The dye was used: (1) to enhance visible observations of
drift, and (2) to enhance the spots on spray-drop cards.
Prior to loading the helicopter in the Chippewa National Forest, an
EPA Pesticides Inspector collected a sample of the mixed material. Later
chemical analysis showed that both the mix and the formulated material
conformed to label specifications (5.24% 2,4-D acid PGBEE1). A similar
sample collected in the Superior National Forest showed extremely low
(0.8% acid PGBEE) 2,4-D levels in the mixed material. Subsequent investi-
gation showed that this sample was collected from the tank truck after it
had sat overnight and the 2,4-D and water had separated. Chemical analysis
of the sprayed material confirmed that the material was properly mixed when
sprayed.
During the loading operation personnel of both the applicator and the
Forest Service wore no safety clothing. Although no Federal requirements
exist for safety clothing to be worn when working with 2,4-D, data are
available to indicate exposure to 2,4-D may be hazardous.2
1	Propylene glycolbutyl ether ester
2	Morgan, D.P. 1976. Recognition and Management of Pesticide Poisonings.
U.S. EPA Report Mo. EPA-540/9-011. Washington, D. C. 56 pp.

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8
The EPA observation team wore safety clothing consisting of an approved
canister-type respirator, face shields, hats, long-sleeved coveralls and
rubber gloves.
APPLICATION
On July 13, 1977, between 8:30 a.m. and 10:30 a.m., 2,4-D was applied to
the Superior National Forest study site. Warm and sunny weather prevailed
during the application. Air temperature was about 65°F, humidity was 65%
and the wind from the northwest at 1.6 Kms/hr, increasing to 8 Kms/hr.
The spray aircraft, a Bell Jet Ranger 206-B helicopter, was equipped
with a Micro-Foil boom using .03 cm nozzles set in rows of three on the boom
segments, thus providing 180 nozzles per six-inch segment. Rate of appli-
cation of the 2,4-D mix was nominally 7.5 liters/hectare with an active
ingredient of 0.56 Kg/hectare.
While the EPA team did not observe visible drift beyond the spray site,
several conditions were observed that contributed to contamination of the
surrounding area: (1) the spray site was not a distinct entity. Some
difficulty was encountered in delineating the physical boundaries because
balloon markers used to mark the site were insufficient in numbers to allow
the helicopter pilot to delineate the site; thus areas outside the zone,
including a portion of privately owned land, were 2,4-D treated and, (2) it
appeared that, with the configuration of the spray site, the pilot should have
changed his spray swaths from a north-south direction to an east-west
direction. This change would have put the spray swaths on a more direct
line with the marking balloons, along the long axis of the spray zone.

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9
On July 15, 1977, the 2,4-D treatment of the Chippewa National Forest
site was conducted between 7:30 p.m. to 9:00 p.m. Conditions were similar
to the previous application, with warm, sunny weather, and light breezes
(<8 Kms/hr). The type helicopter and spray rig used for this 2,4-D
application was identical to that used in the Superior National Forest.
The EPA observation team reported no unusual conditions or events
during the course of the application, but noted that the pilot was conserv-
ative in that he stopped spraying before reaching the boundary of the target
forest area. This site also was treated at 7.5 liters/hectare with an
active ingredient of 0.56 Kg/hectare.
POST-APPLICATION
As noted earlier, the EPA did not observe the mixing operation. Sub-
sequent conversations with U. S. Forest Service personnel revealed that all
containers v/ere triple-rinsed, with the rinse water being added to the
spray tanks. Empty drums were transported to a Class I dump (a site
especially designed for the disposal of highly toxic or environmentally
damaging compounds or containers). The used containers were crushed and
buried in compliance with all pertinent FIFRA regulations.
Superior National Forest
Following the completion of the 2,4-D application, the EPA observation
team entered the study site (treated forest and surrounding area) to retrieve
spray-droplet cards and the high-volume air samplers. Water, soil and
vegetation samples were also collected.
Results of drift deposit analyses for residues on spray-cards (Kromecote,
Thermofax and Linograph), high-volume air sampler filters, water soil and
vegetation are presented in Table 1.

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TABLE 1. RESULTS OF SPRAY DRIFT AND ENVIRONMENTAL SAMPLING
SUPERIOR NATIONAL FOREST, MINNESOTA
July 1977
Station
Type

13
Water

13
Water

13
Soil

13
Soil

11
Soil


Vegetation
5
Hi-vol filter
15
Hi-vol filter
1*
Kromecote
card
2*
Kromecote
card
3*
Kromecote
card
4*
Kromecote
card
5*
Kromecote
card
6
Kromecote
card
7
Kromecote
card
8
Kromecote
card
9
Kromecote
card
10*
Kromecote
card
11
Kromecote
card
12
Kromecote
card
15*
Kromecote
card
16*
Kromecote
card
17*
Kromecote
card
Time
Concentration
Pre**
N.D.*** *
Post***
lU'yg/l
Pre
N.D.
Post
0.02 yg/gm
Post
1.7 yg/g
Post
340 ^g/g
Post
1,300 ug
Post
21 yg
Post
1.4 yg
Post
160 ug
Post
N.D.
Post
22 yg
Post
2.0 vjg
Post
110 yg
Post
380 yg
Post
N.D.
Post
66 yg
Post
140 yg
Post
150 yg
Post
390 yg
Post
0.2 yg
Post
26 yg
Post
67 yg
* Off-site locations
** Pre-application
*** Post-application
**** None detected

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TABLE 2. VMD, DEPOSITION DENSITY AMD DRIFT DISTANCE
SUPERIOR NATIONAL FOREST, MINNESOTA
JULY 1977
Calculated
Deposition Density Drift Distance
Station	VMD (y)	(Drops/cm2)		(ft)***
1*
1,415
11.3
2
2*
1,038
8.5
11
3*
N.A.**
N.A.
N.A.
4*
648
4.8
19.5
5*
N.A.
N.A.
N.A.
6
748
4.0
16
7
1,288
14.7
9
8
N.A.
N.A.
N.A.
9
1,123
8.4
10
10*
983
6.0
11
11
998
7.6
11
12
1,349
9.4
3.5
13
N.A.
N.A.
N.A.
14*
N.A.
N.A.
N.A.
15*
N.A.
N.A.
N.A.
16*
692
0.79
18
* Off-site locations
** Mot applicable
*** Based on 5 mph wind and 20 ft fall

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Surface water collected from a small temporary pond at Station 13
prior to application contained no detectable amounts of 2,4-D, while a
post-application level of 1.4 yg/1 was found. At this same station, soil
residue levels ranged from non-detectable (pre-application) to 0.02 yg/gm
(post-application). Elsewhere on the spray site soil levels of 1.7 pg/g
were recorded (Station 11), with composite samples of vegetation showing
340 pg/g of 2,4-D.
There was a difference in residue levels between the soil and vegetation
samples. The vegetative cover was dense enough to capture virtually all
the 2,4-D, thus insuring good control of undesirable plant species and
helping to avoid ground and possibly groundwater contamination.
Kromecote card data show varying amounts of residues at the site
(Table 1) with, as would be expected, the center portions of the spray
area having the higher amounts.
Data from the high-volume air samplers and Kromecote cards show some
areas of concern. At Stations 2, 5, 15 and 16 on the north side of the area
and Station 10 on the south side, all off the target zone, 2,4-D was
found (Table 1). These residue levels (140 to 160 ug) indicate direct
overspray rather than drift, and are sufficient to cause plant damage.
It is apparent that insufficient numbers of balloon markers were used to
outline the target area, thus allowing the overspray to occur.
The VMD* of the 2,4-D spray ranged from 648 microns to 1,415 microns,
with an average of 1,028 microns (Table 2). The maximum "calculated drift
*VHD - Volume median diameter: that value which divides the droplet diameter
into two equal parts, one-half above and one-half below the median or 50%
calculative point.

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distance" was about 6 meters, therefore, drift contamination of surrounding
areas was kept to a minimum.
Chippewa National Forest
As with the Superior National Forest, members of the EPA team retrieved
sampling devices and collected post-application environmental samples following
completion of spraying activities.
Table 3 summarizes the results of environmental and spray-card sampling.
No detectable amounts of 2,4-D were found in water samples from Station 25,
a pond, located about 60 meters southwest of the spray area. No detectable
2,4-D residues were found in the soil at Station 1, but at Stations 5 and
10 post-application levels of 0.49 yg/g and 3.6 yg/gm, respectively, were
recorded. Filters from the high-volume air samplers had from 18 yg to
2,100 ug (with the latter value coming from a unit that was sprayed directly).
The Kromecote cards showed the variation normally expected, ranging from
detection limits (0.2 yg) to 110 yg. Minor amounts of spray drift were
recorded at stations bordering the spray site. For unexplained reasons, the
areas around Stations 13A and 15 (both on the target site) received no 2,4-D
treatment.
It will be noted that VMD falls into two basic categories, a VMD of
<500 microns and >1,250 microns (Table 4). The smaller droplets occurred
around the periphery of the treated area, with the larger droplets being
found on the target site. The data indicate the spray zone borders were
affected by both overspray and minor drift, some of which possessed the
potential to contaminate the immediately surrounding area (i.e., 57 micron
drops at Station 23 could drift 102 meters). Existing data do not allow
a further interpretation of this point to be made.

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TABLE 3. RESULTS OF SPRAY DRIFT AND ENVIRONMENTAL SAMPLING
CHIPPEWA NATIONAL FOREST, MINNESOTA
JULY 1977
Station
Type
Time
Concentration
25*
Water
Pre* *
N.D.****
25*
Water
Post***
N.D.
1*
Soil
Pre
N.D.
1*
Soil
Post
N.D.
5
Soil
Pre
N.D.
5
Soi 1
Post
0.49 yg/g
10
Soil
Pre
N.D.
10
Soil
Post
3.6 yg/g
1*
Hi-vol filter
Post
18 yg
9*
Hi-vol filter
Post
2,100 yg
21*
Hi-vol filter
Post
56 yg
16
Hi-vol filter
Post
150 yg
1*
Kromecote
Post
N.D.
2*
Kromecote
Post
N.D.
3
Kromecote
Post
25 yg
4*
Kromecote
Post
0.2 yg
5
Kromecote
Post
62 yg
6*
Kromecote
Post
0.2 yg
7
Kromecote
Post
19 yg
8*
Kromecote
Post
N.D.
9*
Kromecote
Post
49 yg
10
Kromecote
Post
38 yg
12*
Kromecote
Post
N.D.
13*
Kromecote
Post
0.3 yg
13A
Kromecote
Post
N.D.
14
Kromecote
Post
110 yg
14A*
Kromecote
Post
0.6 yg
15
Kromecote
Post
N.D.
16
Kromecote
Post
0.7 yg
17
Kromecote
Post
39 yg
17A
Kromecote
Post
61 yg
18*
Kromecote
Post
1.4 yg
19*
Kromecote
Post
N.D.
20*
Kromecote
Post
N.D.
21 *
Kromecote
Post
0.5 yg
23*
Kromecote
Post
0.2 yg
24
Kromecote
Post
2.8 yg
25*
Kromecote
Post
N.D.
26
Kromecote
Post
12 yg
27 *
Kromecote
Post
0.2 yg
28
Kromecote
Post
33 yg
29
Kromecote
Post
70 yg
* Off-site locations
** Pre-application
*** Post-application
**** None detected

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TABLE 4. VMD, DEPOSITION DENSITY AND DRIFT DISTANCES
CHIPPEWA NATIONAL FOREST, MINNESOTA
JULY 1977
Calculated
Deposition Density Drift Distance
Station	VM.D (u)	(Drops/cm2)		(ft)***
1*
N.A.**
N.A.
N.A.
2
N.A.
N.A.
N.A.
3
1,379
5.2
7.5
4
286
0.38
98
5
1,443
6.5
8
6*
243
0.28
100
7
1,264
4.3
7
8*
N.A.
N.A.
N.A.
9*
1,386
4.6
6.5
10
1,996
3.3
4.5
12*
N.A.
N.A.
N.A.
13*
N.A.
N.A.
N.A.
13A
N.A.
N.A.
N.A.
14
2,001
9.5
4.5
14A*
205
0.38
69
15
N.A.
N.A.
N.A.
16
2,294
0.38
4
17
1,420
5.9
7.8
17A
2,035
4.7
4.3
18*
2,592
0.45
2.3
19*
N.A.
N.A.
N.A.
20*
N.A.
N.A.
N.A.
21* .
551
0.07
2.5
23*
57
0.02
335
24
N.A.
N.A.
N.A.
25*
N.A.
N.A.
N.A.
26
1,417
2.3
7.8
27*
N.A.
N.A.
N.A.
28
1,445
5.4
8
29
1,952
5.7
4.2
* Off-site locations
** Not applicable
*** Based on 5 mph wind and 20 ft fall

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12
To summarize, on-site observations revealed that both National Forests
were aerially treated with 2,4-D in a manner consistent with Federal
regulations. Sampling showed that non-target forest land and waterways
were contaminated by overspray or minor drift. The most valuable techniques
used to document the practices and environmental effects of the aerial
application were on-site evaluations by trained observers, VMD analyses
of spray drift cards, and chemical analyses of soil and vegetation to
determine drift and 2,4-D residues at the study site.

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13
V. SAMPLING DEVICES AND METHODS
High-Volume Air Samplers
This system uses a fiberglass filter 20 x 25.4 cm, on which airborne
particles and spray are trapped. Approximately 1 m^/min (35 ft^/min)
of air was drawn through the filter. The system was operated for three
hours at each station. A total of 105 m3 of air passed through each filter.
The filters were removed, stored in plastic bags and returned to the
laboratory.
The filters were extracted by submersion in a Pyrex dish containing
250 ml of water adjusted with sulfuric acid to a pH of 1.5. The water
extract was further treated by extracting the 2,4-D, in acid form, with
an organic solvent. The 2,4-D acid was esterfied with borontrifluoride
in methanol and the resulting methyl ester analyzed by electron capture
gas chromatography.
Spray Droplet Cards
Spray card clusters were constructed by stapling Linograph 480 paper,
Thermofax 209 copy, type 640 paper and Kromecote cards onto 12-inch square
poster board bases. The clusters were placed around and on the spray sites
atop one-meter upright wooden platforms and attached by elastic bands.
All cards were highly sensitive to the 2,4-D material. Visual images
were enhanced by the addition of the fluorescent dye (Rhodamine WT).
Linograph 480 and Thermofax 209 copy type 640 cards were sent to a
contracting agency for analysis of the spray drop impingement. The analytical
technique used a Quantimet Image Analyzing Computer, provided data on VMD

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and deposition density. However, this optical scanner cannot distinguish
between spray drops and imperfections in the spray card paper, dust, dirt,
etc., thus some cards had unreasonably high values reported. Realizing
these limitations and comparing the values with chemically analyzed cards,
some values were set aside and labeled "Not Applicable" in Tables 2 and 4.
Kromecote cards were chemically analyzed for 2,4-D residues. Treatment
of these cards was the same as for the high-volume air sampler filters.

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