Bull. Environm. Contain. Toxicol. 23,196-202 (1979)

Comparison of Dry and Wet Surfaces for Collecting Organochlorine Dry Deposition E J. Christensen1, C. E. Olney 2, and T. F. Bidleman1. IDepartment of Chemistry and Belle W. Baruch Institute for Marine Biology and Coastal Research, University of South Carolina, Columbia, S.C. 29208 and 2Department of Food Science and Technology, Nutrition and Dietetics, University of Rhode Island, Kingston, R.I. 02881

Aerial transport appears responsible for the global dispersion of PCB and chlorinated pesticides (NAS 1978), and on a local scale atmospheric input by rain or p a r t i c l e deposition has been shown to contribute s i g n i f i c a n t l y to the p o l l u t a n t budgets of Lake Michigan (MURPHY & RZESUTKO 1977) and the Southern California Bight (YOUNG et al. 1976, McCLURE 1976). Collection techniques for organochlorines (OC) deposited by p a r t i c l e s e t t l i n g and turbulent impaction (dry deposition or "dry f a l l o u t " ) vary widely. Silicone o i l coated nylon screens (SODERGREN 1972), mineral o i l sprayed glass plates (McCLURE & LaGRANGE 1977, YOUNGet al. 1976), and even glass plates cooled with dry ice to minimize r e v o l a t i l i z a t i o n (HEESEN & JOHNSON 1976) have been used to retain a e r i a l l y deposited OC. Our i n t e n t was to develop a method that would mimic as closely as possible the c o l l e c t i o n characteristics Qf a water surface, since we were interested in measuring OC f a l l o u t in the coastal zone and the open ocean. Screens can trap p a r t i c l e s by f i l t r a t i o n as well as impaction, and we f e l t that a hydrophobic surface l i k e o i l might scavenge OC vapors as well as p a r t i c l e s . We therefore compared the f a l l o u t c o l l e c t i o n c h a r a c t e r i s t i c s of several hydrophilic surfaces (water, ethylene glycol-water, glycerin-water) with those of a dry pan. MATERIALS AND METHODS Measurements of OC f a l l o u t were made at Kingston, Rhode Island, a small u n i v e r s i t y community located about 60 km from the nearest major c i t y (Providence, RI) and in Columbia, South Carolina, a metropolitan area with a population of 380,000. Fallout stations were located on rooftops on the University of Rhode Island (URI) and University of South Carolina (USC) campuses, about 15-30 m above ground. Several d i f f e r e n t surfaces were evaluated for f a l l o u t c o l l e c t i o n . At URI, f l a t bottomed glass dishes 0.074 sq. m area and 4.5 cm deep were used dry or f i l l e d to a depth of I-2 cm with 20% ethylene glycolwater. Collections at USC were made with 64 x 46 x 2 cm deep aluminum pans (area = 0.29 sq. m) used dry, f i l l e d to about 1 cm with water, or sprayed with a l i g h t coat of 50% glycerin-water (using an a l l - g l a s s TLC atomizer). Dry and wet surface c o l l e c t i o n pans were

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0007-4861/79/0023-0196 $01.40 9 1979 Springer-Verlag New York Inc.

to

T.F.

Bidleman

exposed side by side for equal i n t e r v a l s ranging from 22-116 h. The contents of a c o l l e c t o r were transferred to a 3.8-L brown glass jug with the aid of d i s t i l l e d water and dichloromethane or acetone rinsings. In the case of dry or glycerin-water sprayed pans, the surfaces were repeatedly scraped with a piece of teflon between rinsings to ensure q u a n t i t a t i v e transfer of deposited material to the jug. Pesticide q u a l i t y dichloromethane (200 mL) was added, and the jug was rolled for several hours on a j a r mill to e x t r a c t the OC. The dichloromethane was separated from the aqueous layer, f i l t e r e d through glass wool, and concentrated to 5-10 mL on a flash evaporator. The e x t r a c t was transferred to a Kuderna-Danish concentrator apparatus and the dichloromethane was removed by r e f l u x i n g with hexane and evaporating to I-2 mL. The e x t r a c t was cleaned up by alumina column chromatography (4 g a c t i v i t y grade I I I , 20 mL petroleum ether eluate) and the OC were separated into several fractions on a s i l i c i c acid column p r i o r to GC analysis (BIDLEMAN et al. 1978). Analyses were carried out by electron capture gas chromatography using two of the following columns: 1.5% SP-2250/I.95% SP-2401; 4% SE-30/6% SP-2401; 3% 0V-225. All columns were glass, 0.4 cm i . d . x 180 cm long, and were operated isothermally at 180-200~ under 50-70 mL/min nitrogen flow. The peaks i d e n t i f i e d as PCB, DDT, and chlordane were unaffected by 7% fuming s u l f u r i c acid treatment. DDT and cis-chlordane were confirmed for a number of samples by dehydrochlorination with alcoholic KOH to DDE and 3-chlorochlordene (trans-chlordane does not readily convert under these conditions, ~HAU & COCHRANE 1969). Aqueous solutions used to f i l l or spray f a l l o u t collectors were pre-extracted with dichloromethane to remove organic contaminants. Traces of the dichloromethane were removed from the solutions before use by heating on a hot plate or steam bath. Woelm neutral alumina and Mallinckrodt lO0-mesh s i l i c i c acid were used for column chromatographic cleaup and f r a c t i o n a t i o n . Analytical standards of PCB and pesticides were obtained from the U.S. Environmental Protection Agency Pesticide Repository, Research Triangle Park, North Carolina. RESULTS AND DISCUSSION The r e l a t i v e quantities of OC f a l l o u t retained by pans sprayed or f i l l e d with l i q u i d to the amounts found in a dry pan are given in Table 1 for the individual experiments at URI and USC. In almost every case the e f f i c i e n c y of the wet surfaces was higher over a I-5 day sampling period. On the average, the wet pans retained 1.5 - 3 times more OC f a l l o u t than the dry pans, while the differences between the water, ethylene glycol-water, or glycerin-water surfaces were small (Fig. I ) . Our results thus d i f f e r from those of McCLURE & LaGRANGE (1977), who reported that uncoated glass plates were "only s l i g h t l y less e f f i c i e n t " than oiled plates.

197

RI (1974-75)

2.

Io

W G-W

24

-__

2.5 1.6

1.0 1 .I

1.3 1.2

2.2 3.4

3.5 1.3

1.6 1.3

2.6 3.8

0,4 0.6

1 o3 1.7 1.6 4~ 2.5

1.8 1,8

1.0 2.9

1,0 0.5

. .

2.9 0.8

2,3 2.5

1.0 1.0

------

. .

. .

. .

Surfaces:

W and EG-W = pans f i l l e d w i t h d i s t i l l e d w a t e r and 20% e t h y l e n e g l y c o l - w a t e r ; G-W = pans sprayed w i t h 50% g l y c e r i n - w a t e r . cis- + trans-chlordane

W G-W

1.3 1.4

W G-W

48

48

---

W G-W

3.0 3.3

W G-W

27

0.6 0.7

W G-W

-3~ --3.1

Ch]ordane 2

1.7 --

1.I 1.9

6.3 5.4

2.1 1.5

5.6 6.6

0,5 0.4

1.9 2.4 2.8 2~ 2.0

p, p ' -DDT

Relative Fallout Collected (Dry Pan = 1 . 0 )

o f Dry and Wet Surfaces

Arocl o r 1254

Efficiencies

Arocl o r 10l 6

--, --

(1976-77)

EG-W EG-W EG-W EG-W EG-W

Surface I

Collection

W G-W

45

116

72

Columbia, SC

45 55 25 22 48

Exposure t i me, hours

Kingston,

Comparative F a l l o u t

TABLE I

4,0-

t

3,0-I!

>,.

IiT, .I. ~;

0

--I ,--I

??:J ,:.

2.0

I,.i. I.g

7U,.I

1.0

: .:....,

T.::-); ..,,...,,

.,-,,.,,

AROCLOR 1016

Fig. I:

CHLORDANE

AROCLOR 1254

Average values for the r e l a t i v e quantities of CHC f a l l o u t retained by wet vs. dry surfaces. Vertical lines represent standard deviations of the means.

w a t e r - f i l l e d pan

I

ethylene glycol-water f i l l e d pan

II~S~i!I~S.~::..~i~i'i:~ii'I

glycerin-water sprayed pan

199

J

DDT

518-10/75

"

Io 2.

"

G-W

G-W

Dry

Dry

Dry

Dry

Surface 2

cis- + trans-chlordane G-z~= 5 0 % g - ~ e r i n - w a t e r spray

5/9-11/77

4/8-11/77

2/18-19/74

"

Columbia, SC

2/14-16/74

2/12-14/74

Kingston, RI

"

Dates

Location

0~ 0.29 0~

0.29 0.29 0.29

0~ 0,074 0.140

0~ 0~

0.074 0.074

0~ 0.074

Area, m2