Pesticide Drift and Quantification from Air and Ground Applications to

13 Pesticide Drift and Quantification from Air and Ground Applications to a Single Orchard Site

Downloaded by UNIV OF ROCHESTER on June 11, 2018 | https://pubs.acs.org Publication Date: February 25, 1985 | doi: 10.1021/bk-1985-0273.ch013

G . B. MACCOLLOM, W . W.

CURRIER,

and G. L. BAUMANN

Vermont Agricultural Experiment Station, University of Vermont, Burlington, VT 05405

Eight applications of carbaryl and/or captan were made by air and ground equipment to an orchard site over a 2-year period. Two climatic parameters were used; calm conditions with temperature inversion, and wind v e l o c i t i e s of 3 to 10 KPH with no inversion. Regardless of atmospheric stability, in the presence of an inversion, carbaryl deposits from air application were found at 500 m downwind, and at 300 m in absence of an inversion. Ground application gave deposits no further than 150 m downwind during inversion, and no detectable deposits at 50 m in absence of inversion. Captan applied by air gave detectable deposits 150 m downwind, with an inversion present, whereas ground application resulted in deposits at only 50 m downwind. Percent of total pesticide attributable to drift from both air and gound application is relatively small. In quantification studies deposition was measured from total foliage, bark, fruit, orchard floor, and off-target areas as well as from volatilization. The d r i f t and deposition of pesticide particulates outside of target a r e a s i s a c o n c e r n of b o t h the p u b l i c and regulatory agencies. S t u d i e s by C u r r i e r e_t_ a_l_ (3) i n d i c a t e d d r i f t r e s i d u e s from a e r i a l l y a p p l i e d c a r b a r y l were g r e a t e r d u r i n g a temperature inversion. These f i n d i n g s were c o n s i s t e n t with the results of A k e s s o n and Y a t e s (I) u s i n g a i r applied sprays on a l f a l f a and by M a c C o l l o m et^ a_l_ (40 u s i n g a i r a p p l i e d dusts on orchards. That a i r a p p l i c a t i o n is a greater contributor to d r i f t has been implied by numerous investigators. A report by the Council on Environmental Q u a l i t y e n t i t l e d "Environmental Trends" anonymous (2) states that two t h i r d s o f the i n s e c t i c i d e s used in agriculture are applied by a i r c r a f t , but only 25 to 50% reaches the crop, implying that a large amount is lost through d r i f t . In the N o r t h e a s t , a s u b s t a n t i a l amount of orchard acreage is t r e a t e d by a i r . This technique has d i s t i n c t advantages over ground

0097-6156/85/0273-0189$06.00/0 © 1985 A m e r i c a n C h e m i c a l Society

Honeycutt et al.; Dermal Exposure Related to Pesticide Use ACS Symposium Series; American Chemical Society: Washington, DC, 1985.


190

DERMAL EXPOSURE RELATED TO PESTICIDE USE

equipment d u r i n g wet weather as reported by Mac Co Horn (2). Ware e t a 1 (6) i n d i c a t e d t h a t ground a i r b l a s t a p p l i c a t i o n s on a l f a l f a r e s u l t e d i n g r e a t e r d r i f t d e p o s i t s than s i m i l a r a i r a p p l i c a t i o n . The a p p l i c a b i l i t y of these studies, conducted on a low g r o w i n g crop on f l a t t e r r a i n , to sloping orchard terrain with trees growing from 5 to 9 m in height is unknown. S t u d i e s were i n i t i a t e d i n 1980 to determine d r i f t differences between a i r and ground a p p l i c a t i o n s , using one orchard location. Two c l i m a t i c p a r a m e t e r s were used, the presence and absence of a temperature inversion at the time of application. In 1980, as shown i n T a b l e I , f i v e a p p l i c a t i o n s of a carbaryl/captan mixture, were made and i n 1981, three applications of captan. The selection of c a r b a r y l and captan was based on the need for exposure studies due to the u n c e r t a i n r e g i s t r a t i o n status of the pesticides at the time of the studies.

T a b l e I.

Date 7/17/80 7/24/80 7/31/80 8/7/80 8/12/80 7/1/81 7/15/81 8/10/81

A i r and Ground A p p l i c a t i o n Meteorological Conditions,

Equipment WV Used KPH Air 4.8/9.7 Air 1.6/2.5 Ground 1.6/3.2 Ground 3.2/6.4 Air 3.2/12.9 Air 1.6/3.1 Ground 1.6/4.8 Ground 3.2/4.8

WD

%RH

S calm S S Ν Calm NW S

80 68 60 50 68 90 44 75

Summary w i t h P r e v a i l i n g C o r n w a l l , VT

Pesticide Used carbaryl/captan carbaryl/captan carbaryl/captan carbaryl/captan carbaryl/captan captan captan captan

Temperature Inversion NO(+0.1°C) Yes(-3.6°C) Yes(-1.7°C) N0(+2.0°C) NO DIFFERENCE YES(-0.6°C) NO(+1.0°C) YES(-2.1°C)

Temp measured at 9.75 m and 2.45 m above ground level at time of application difference (T9.75 -T 2/45) given in ( ).

Material and Methods S i t e and A p p l i c a t i o n P r o c e d u r e s . The o r c h a r d s i t e and a i r a p p l i c a t i o n equipment were the same as described by Currier (1982). In 1980, ground a p p l i c a t i o n s were made with an Ag-Tech low volume a i r b l a s t sprayer, calibrated to deliver 187 1/ha, and in 1981, with a K i n k e l d e r low volume a i r blast sprayer calibrated to deliver 94.6 1/ha. F r o m p r e v i o u s s t u d i e s of M a c C o l l o m et^ al_ (5) and C u r r i e r (3^) i t was known t h a t the a i r application gave a median d r o p l e t s i z e d i a m e t e r of 100 t o 150 urn. Estimation of p a r t i c l e s i z e , as measured on water sensitive paper, for ground equipment was 75 to 110 pm. A p p l i c a t i o n rates for captan 80W in both years was 3.12(AI) Kg/ha, and for carbaryl 80S, 2.24(AI) kg/ha. D r i f t d e p o s i t i o n s a m p l e r s consisted of 15 cm diameter p e t r i d i s h e s h o l d i n g a pre-cleaned f i l m of teflon FEP. Three deposition s a m p l e r s were p l a c e d at each f i e l d sampling location in order to r e c e i v e i m p i n g i n g spray components and any subsequent f a l l o u t from our s p r a y o p e r a t i o n . The deposition samplers were located at 50, 150 , 300 and 500m r a d i a n s (N, NE, E, SE, S, SW, W, NW) from the orchard. P r e v i o u s work by C u r r i e r e_t^ al_ (3^) had shown that


13.

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Pesticide Drift and Quantification

191


s a m p l i n g at 300 m was i n s u f f i c i e n t to completely define d r i f t parameters. The s a m p l e r s were placed on one meter stands, just above ground c o v e r , and l e f t uncovered for the duration of the e x p e r i m e n t , about three hours. At the conclusion of the experiment d i s h e s were covered and held at -4°C to await analysis. Storage of t h e s e samples w i t h known standard deposits show l i t t l e v a r i a t i o n over a 12 week period. M e t e o r o l o g i c a l Measurements. Detailed meteorological data were t a k e n during each study and during a i r sampling procedures 24H after application. T h i s information consisted of: wind d i r e c t i o n , wind v e l o c i t y , temperature at 9.75 m and at 2.45 m, R.H. , and barometric pressure. Ambient t e m p e r a t u r e s were measured in the orchard by s h i e l d e d t h e r m i s t o r s placed at 9.75 m and 2.45 m above the ground. H i g h e r t e m p e r a t u r e s at the 9.75 m l e v e l i n d i c a t e d meso-scale temperature inversions. A sensitive hot wire anemometer was used at 6.1 m to measure wind v e l o c i t y . A Thornthwaite Assoc. instrument i n d i c a t e d wind i n d i c a t e d wind d i r e c t i o n s . A summary of the prevailing meteorological conditions i s shown i n Table I. A n a l y t i c a l Methods. In 1980 where carbaryl/captan were applied i n c o m b i n a t i o n , a simultaneous quantitative analysis for the mixture was d e v e l o p e d using a Water's system (model M-45 pump, 6K injector and Model 450 v a r i a b l e wavelength detector) high pressure l i q u i d chromatograph system and Hewlett-Packard 3380-A integrator. A 25 cm C^g pBondapak ( W a t e r s ) column e l u t e d w i t h 1.3 ml/min of 70% a c e t o n i t r i l e : 30% Yi^O and w i t h the detector set at 205 nm gave good s e p a r a t i o n and detection of the carbaryl/captan mixture. The e l u t i o n of the carbaryl i n 3.15 min gave a .01 ng detection l i m i t . The e l u t i o n of c a p t a n i n 3.96 min gave a 5-10 ng detection l i m i t . S t u d i e s i n 1981 where o n l y captan was applied u t i l i z e d the same procedure. R e c o v e r y of d e p o s i t s on the teflon discs were made by washing the d i s c in 70% a c e t o n i t r i l e for 30 min. During the course of these s t u d i e s , a t o t a l of 395 carbaryl analyses, and 519 captan analyses were made. Pesticide Quantification T r e e d e p o s i t s . R e c o v e r y of d e p o s i t s from the components for f r u i t , f o l i a g e , and b a r k were estimated by exposure of 5 χ 10 cm s t r i p s of teflon f i l m placed in tree canopy to mimic tree surfaces. Two s e t s of f o u r t e f l o n f i l m s attached to .95cm diameter wooden dowels were placed i n the tops, and at shoulder height i n the trees. The dowels were mounted 30.5cm into the canopy on the N, E, S, and W s i d e s of the tree. This procedure was followed for two of the captan a p p l i c a t i o n s , one by a i r on 7/1/81, and the other by ground on 7/15/81. One tree was sampled i n the center of the orchard for each application. . . . 3 V o l a t i l i z a t i o n sampling. One m of a i r was drawn t h r o u g h M i l l i p o r e f i l t e r s (type glass depth A/E) for impingement of airborne p a r t i c u l a t e s g r e a t e r than 2 m i c r o n s i n d i a m e t e r . Smaller p a r t i c u l a t e s i n the a i r were then drawn through a C Sep-pak lft


192



( W a t e r s ) f o r r e t e n t i o n as well as any v o l a t i l i z e d portion i n the atmosphere. The a i r sampling Sep-Pak f i l t e r devices were placed 4.9 meters in the a i r , at 3 locations, one at the orchard and two at p r e d e t e r m i n e d d i s t a n c e s downwind. Due to equipment needed, this p o r t i o n of the study was limited to 3 sampling s i t e s ^ Total volume of atmosphere above the orchard was determined in m using length, and w i d t h of area treated by 9.75 m, the height at which inversion, i f present, was measured. Tree Modeling. Work was i n i t i a t e d i n 1983 based in part on a t e c h n i q u e by Dr. L. A. Hull of the Pennsylvania State University, B i g l e r v i l l e Laboratory (1982 personal communication), to model the t r e e s at the site of application studies conducted in 1980 and 1981. U s i n g the c u l t i v a r Mcintosh, 10 trees were measured for height and w i d t h w i t h i n £he s i t e . U s i n g a paraboloid of revolution, where volume = i i i b a (b= i w i d t h , a= height) the t o t a l tree volume i n m was determined. A h o l l o w cone i n t r e e c e n t e r , devoid of f o l i a g e , was measured, volume determined and substracted from t o t a l . Ten 2.83 χ 10 cm samples (1 f t ) were c o l l e c t e d throughout the t r e e , and l e a v e s counted and measured for t o t a l area i n cm , using a L I - C O R model 3100 a r e a meter. This permitted a d e t e r m i n a t i o n ^ of t o t a l f o l i a r surface/tree. At the same time the 2.83 χ 10 cm l e a f samples were c o l l e c t e d , a l l f r u i t within the sample were also c o l l e c t e d , and surface area ascertained. T o t a l b a r k surface of 3 Mcintosh trees was determined from 1983 s t u d i e s , by measuring length and circumference of trunk, branches, and t w i g s .5 cm diameter were measured with calipers and a tape measure. Total bark/tree surface area was determined by g e o m e t r i c a l f o r m u l a f o r a frustum. Both bark, foliage and leaf s u r f a c e d e t e r m i n a t i o n s were made within 10 days of application to minimize growth e f f e c t s . O r c h a r d f l o o r and off target d r i f t deposits. The total deposit on the o r c h a r d f l o o r was d e t e r m i n e d by deposition on teflon discs w i t h i n 15 cm d i a m e t e r p e t r i d i s h e s . S i m i l a r l y , o f f - target d e p o s i t i o n , as p r e v i o u s l y d e s c r i b e d , was determined by the same technique. Total deposition off-target was ascertained by assigning known v a l u e s to off-target areas. The values assigned to each area were the a v e r a g e of the amounts i n pg/cm found at the near edge and at the most distant point of the area. The sampling distances of 50, 150, 300 and 500m were used to delineate the areas in either rectangular or triangular blocks. Discussion The a b i l i t y to conduct f i e l d research dependent on similar climatic c o n d i t i o n s p r e v a i l i n g o v e r a prescribed time frame is extremely difficult. We d e s i r e d a p p l i c a t i o n s be made under 2 climatic p a r a m e t e r s , the p r e s e n c e and absence of a temperature inversion. Our p r e m i s e was t h a t the absence of a temperature inversion was g e n e r a l l y a s s o c i a t e d with wind v e l o c i t i e s of 5 to 10 KPH r e s u l t i n g i n a t m o s p h e r i c turbulence. Hence, airborne particulates would be expected to mix into the atmosphere giving lesser amounts detectable o f f - t a r g e t . Presence of an inversion was generally associated with



13.

MACCOLLOM ET AL.


193

s l i g h t winds (< 4 KPH) with reduced off-target carry and deposition of airborne particulates i n proximity to the target area. D e s p i t e c a r e f u l a t t e n t i o n to weather forecasts, never were we a b l e t o d u p l i c a t e weather patterns exactly. On several occasions, a f t e r a day's p r e p a r a t i o n , a s h i f t i n wind d i r e c t i o n or a sudden shower negated a l l our e f f o r t s . In 1980, f i v e a p p l i c a t i o n s of a carbaryl/captan mixture were u s e d , two by ground and t h r e e by a i r , as indicated i n Table I. A n a l y s e s of off-target depositions showed that carbaryl consistently d r i f t e d f u r t h e r than captan when applied by a i r (Figure 1). One would e x p e c t t h a t the d r i f t i n g p a r t i c u l a t e s would have both p e s t i c i d e s p r e s e n t , and t h a t l e v e l s o f each would be detected wherever d r i f t occurred. This unexpected result cannot be readily a t t r i b u t e d t o s e n s i t i v i t y of the analyses since a l l samples were w e l l above the s e n s i t i v i t y limits (10 ng for captan and 0.01 ng for carbaryl). The vapor pressure of captan i s appreciably lower than t h a t of c a r b a r y l and i f v o l a t i l i z a t i o n from d r i f t i n g minute p a r t i c u l a t e s was a factor, captan should have been found i n greater quantities than carbaryl. The p r e s e n c e o f a t e m p e r a t u r e i n v e r s i o n at the time o f a p p l i c a t i o n r e s u l t e d i n off-target deposition at greater distances and/or i n greater amounts than those found from applications made i n absence of a t e m p e r a t u r e i n v e r s i o n . Comparison of two a i r a p p l i c a t i o n s of carbaryl/captan (Figure l ) show that regardless of wind or a t m o s p h e r i c s t a b i l i t y carbaryl deposits were found at 500 m o f f - t a r g e t downwind during an inversion with deposits 20 times (5.38 pg p l a t e S E - r a d i a n ) t h o s e o f d e p o s i t s (.25 p g / p l a t e Ε-radian) at 300 m i n the absence of an inversion. A s i m i l a r a i r a p p l i c a t i o n made i n absence of an inversion r e s u l t e d i n c a r b a r y l d e p o s i t s (2.29 pg S-radian) at a maximum of 300 m and off-target downwind. In no instances was captan deposits d e t e c t e d with the carbaryl deposits found at the furthest off-target sites. Comparison o f two ground carbaryl/captan applications, (Figure 2) showed t h a t i n absence of an inversion no off-target deposits were s e e n , whereas the application during an inversion resulted i n maximum o f f - t a r g e t downwind d e p o s i t s o f b o t h c a p t a n (.62 pg N-radian) and carbaryl (.58 pg N-radian) at 150 m downwind. In 1981 3 a p p l i c a t i o n s of captan were used, 2 by ground, and 1 by a i r . Comparison o f ground a p p l i c a t i o n s ( F i g u r e 3) showed o f f - t a r g e t downwind deposits with detectable levels found at 300 m (4.28 pg S E - r a d i a n ) i n absence o f an i n v e r s i o n , and (12.95 pg N E - r a d i a n ) a t 50 m i n presence of an inversion. A i r application ( F i g u r e 3) d u r i n g an inversion showed no detectable levels beyond 150 m. In 1981 a i r samples showed detectable levels of captan i n a l l samples c o l l e c t e d 4.9 m above the orchard edge, and that levels persisted for at least 30 minutes following application (Table I I ) .


194


24 July 1980 Inversion


1000 H

0

50

150

300

500

Sampling sites / Meters downwind from orchard

12 August 1980 No inversion

1000 Φ

« α ^ o>

100 10

3 1 0

50

150

300

500

Sampling sites / Meters downwind from orchard F i g u r e 1. C a r b a r y l (broken l i n e ) / c a p t a n ( s o l i d l i n e ) a p p l i c a t i o n s by f i x e d wing a i r c r a f t i n presence and absence of a temperature inversion.



MACCOLLOM ET AL.

Ground application 31 July 1980


Inversion

0

50

150

300

500


7 August 1980 No inversion

0

50

150

300

500


F i g u r e 2. C a r b a r y l / c a p t a n a p p l i c a t i o n s by ground equipment p r e s e n c e and absence o f a temperature i n v e r s i o n .


in


196

Ground application


Captan 1000 Φ

S

^ o>

100 10

3 1 0

50

150

300

500


Air application Captan 1000 Φ

%

100 -

Q. ^ σ>

10 -

3 1 0

50

150

300

500


F i g u r e 3. Comparison o f t h r e e c a p t a n a p p l i c a t i o n s , two by ground i n p r e s e n c e and absence of a temperature i n v e r s i o n , and one by a i r w i t h an i n v e r s i o n p r e s e n t . Key: c a r b a r y l , broken l i n e ; and captan, s o l i d l i n e .


13.

MACCOLLOM ET AL.


T a b l e I I . Atmospheric

Type Application Air Ground Ground

Date 7/1/81 7/15/81 8/10/81

197

3

L e v e l s of Captan (ug/nr ) above Orchard Downwind* Edge 1981

Before ND** ND ND

During 50.62 11.21 3.03

30 Min After 52.36 16.65 3.66

24 Hrs. After ND ND ND

60 Min After Ng Τ 7.80


* A t m o s p h e r i c samples a l s o taken @ .5 and 1.0 Km downwind at same time i n t e r v a l s with no detectable levels on 7/15 and 8/10 and only trace amounts on 7/1/81. ND = Not detected, Τ = Trace

From t h e s e s t u d i e s i t i s apparent that more d r i f t occurs from air a p p l i c a t i o n than ground e q u i p m e n t . The p r e s e n c e o f a t e m p e r a t u r e inversion at the time of application usually results i n g r e a t e r off-target downwind deposition (regardless of slopes of

Pesticide Drift and Quantification from Air and Ground Applications to

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