Evaluation of precipitation samplers for assessing atmospheric fluxes of trace organic contaminants

Chemosphere, Voi.23, No.3, Printed in Great Britain

pp 343-361,

1991

0045-6535/91 $3.00 + 0.00 Pergamnn Press plc

EVALUATION OF PFIECIPrrATION SAMPLERS FOR kSSESSlNG ATMOSPHERIC FLUXES OF TRACE ORGANIC CONTAMINANTS

Thomas P. Fmnz, ~

J. Eisenmich* and Mmy B. Swanson

Gray Freslmatw Biological Inmltute and Department of Civil and Mineral Enginearlng unh,emty of M ~ m o t a

Minneapolis, MN 55488

ABSTRACT

Four automated, wet-only integrating p r e c i p ~ umpters were deployed at a site 50 km north of MlmleapoIIs, MN In 1988 to assess the ability of each to collect and Isolate selected s e m t - v o ~ organic chemicals In rldn. The fr.ur samplers were evaluated on the basis of raiofall cogection efficiency, mechlnk:al ~ Ind aloillty to provide precise measures of c o n c a n t r ~ and fltw.es. Rainsamplea were anldyzed lot a ~ 79 ¢ : o m p o ~ indudklg 17 PAHIk 38 PC8 conganers ancl a sulte of 9 chlorlnated pesticldes and banzerms. The esmOem pedormed about equdly In mln and corn-

pound c ~ t ~ 0 n e ~ . l e ~ y snhough mechank~ problems are not u n l o ~ a m o n ~ samplmL ~ ssmplm m ' ~ b l ~ organic compound ratwak~ onthe coaectionsurge and/or a a m ~ g t r m a v u ~ g 98% o f t ~ PAH and 4O% of toW PCBg Although not a pcobtem in a ~ total ¢onosnl~Zlkms and I h / x ~ this phanomanon makes the ~ of organic compound speclatlon and of atmosphedc removal processes in integrated rain samples problematic. INTRODUCTION

The atmosphere Is now recognized as an Important contributor of anthropoganic organic compounds to oceanic (Bldlernan and Olney, 1974; Atlas and Glare, 1981, 1985; Tanabe eta/., 1983) and to freshwater e c o ~

(Murphy snd

Rzeszutko, 1977; Strachen and Huneault, 1979; Eisenrelch eta/., 1981; Murphy, 1984; Strachan, 1985; Eisanmich, 1987; McVest'y and Hltes, 1988; Strachen and Elsenreich, 1988; Swackhamer eta/., 1988; Chen and Perkins, 1988; Eltzer and Hltes, 1989). The Laurentlan Great Lakes are recognlzed as being particulady susceptible to atmospheric Inputs of organic contaminants because they am near and downwind of major industrial/urban centers, have large surface ames and surface area to basin area ratios, and have long water residence times (Eisenmich eta/., 1981). Eatimates of wet and dry depositlon, especially for contaminants such as I ~ e d

b i p h ~ s (PCBs) and polycydic aromatic hydroosd0ons (IN-Is)

using input - output budgets show that the upper lakes (Superior, Michigan and Huron) receive the maJodty of total Inputs from the a t r n o ~

(Strachen and Eisenreich, 1988). Lakes Erie and Ontario receive a lower but s i ~

percentage of

their total Input from amme43hedcdeposition. The organic contamirmnts am removed from the atmosphere and deposited on water by wat d e ~ two c o n s t ~

dryde~

(rain, snow), dry psrtlde ~

,

and vapor slxmrptlon at the alr-water intedaos. The latt~

m a t best dllflcuIt to Infer frorn environmental measurements and mod~s (e.g., LISs, 1983;

Mackay et a/., 1988; Baker and Eisanmich, 1990). A vadaty of p r e ( ~

samplers have been designed to estlimate wet deposltiort of atmospheric Inorganic and

organic chemicals. These samplers are of three general types: bulk samplers that collect both wet and dry d e ~

343

344

weUdry mm~ers that heve the capacity to coilact born wat and dry inputs Nperately, end w a t ~ tlvely collect precipitation whle e0(dudingdry inputs. Bulk~ performance in I ~

~

~

~

and wet-only samplers have been ewluated for their

organic chemlcels in precipitation (Galloway and Likens, 1976, 1976; Chen a'a/., 1984). The bulk

collectors are susceptible to contamination by dry d e ~

and do not accurately A___~,~___concenlraUon8in rain If left

unattended In the field for extended periods of time. However, precipitation inputs may be properly lulmlom~l using watonly integrating or event samplers of various designs (e.g., see Slmchen and Huneault, 1984; Pankaw efa/., 1984; Chen and Perkins, 1989)employing either in situ compound isolation on solid adsorbents or bulk water ex~ctJo~ The Ob~X~Ne of this study was to evaluate four precipitation samplers co4oc~ed at a site 50 km north of Minnmpolis, MN. It Is anticipated that precipifaticn samplers will be deployed in an evolving U.S. EPA precipitation network in the Great Lak~ region for periods of about two weeks and mu~ be capable of unattended operation. The wnplem are ov~uated =nd compared on the basis of their ability to efflcisndy collect rainbll, e0o'dbitmechanical reliability, demonstrate good operatlonel charaotedstlcsand provide precise measuresof wst-only Inputs of selected organic contaminants. Crlterla for preelonatlon Collector# Cdteris to consider in constructing, modifying or selecting preciplt~lon samplers for assessingatmcephedc Inputs of trace contaminents have been summarized by Elsenrelch eta/., (1980), Strachen and Hunasult (19e4), Penkow eta/., (1984) and Murphy (1987). Ideally, a preclpltstlon collector for assessing organic inputs from the a t n ~

on an

integrating basis should have the following charaoterlstics: 1. 2. 3. 4.

Collects wet-only preclpltatlofl (i.e., rain and snow). Collector ~ large surface area (0.2to 1.0 m2). Collection/storage surface should be non-contaminating,non-adsorbing and made of stakle~mateel, aluminum, or other Inert sul=aa._~__. Collector hes a fa~ ~ l n g and t ~ covedng mechanism.

5.

Collactor should be suitable for tmattended operation over periods two to four weeks.

6. 7. 8.

~or wffi re(luke access to electrlcel power. Inltkl stages of rain events must he co#ected. Collector should be v~;-~tlle such that organic compounds dlffedng in concentmtk)n, physk:W/chemtcel propertkMand speclatlon in rain may be efficlenlfy collected and Isolated.

EXPERIMENTAL Site Del~rintion The precipitation samplers were deployed at the Cedar Creek Natural History Area (CCNHA) In __A~___-central Minnesota about 50 km north-northwast of Mlnnaspofls, MN. The area consists of 5460 acres of ahendoced agricultural fields, uplands, wetlands and lakes. The samplers were located on the wastem edge on a fiat, grassy field flanked by wooded areas to the north, east and south wlth private agriculturalland to the west. The samplers were deployed on two wooden decks about 0.6 m above the ground and allgned parallel to the prevallingwind direction (westerly) wlth the funnels upwind and about 2 m apart. Two four-inch raln geugu were located on dlagonelly-oppoelteends of the platform at the same height as the cogector funnels. Samoler Del~rintion All preclpltatlon samplers used In this study am integrating, wet-only preclpltatlon collectors wlth specific characteristlce as given in Table 1. Three of the precipltaticn ump4ers were constructed by M.I.C. Co. (Thomhill, Ontario) and Indlvklually modlfled In their mode of organics IsolaUon,type of collection surface, enclosure of the sample compatment for ell-weather adaptation and In-line filtration. The other organic rain sampler was oonstruot~l by ,~-~,~,'-,om Metrics (Bushnell, FL) end modiflad for In-s/tu Isolation of organic compounds in rain uelng XAD-2 reeln ceflddgel.

345

TABLE 1.

Chem~Idetice of ~ o n

Parameter

~mlder~ Solvent MIC

(SM)

Collection Sudeca surface area (sq. cm)

Resin MIC

(RM)

Rlter MIC

Resin Aerochem

(FM)

(RA)

2060

2060

2060

814

stainless sted square

Teflon

Teflon

square

square

stalnlesa steel circular

Collection Efficiency (ave. %)

90.4

92.2

95.8

88.7

Mode of Organics Isolation

solvent extraction

XAD-2 resin

XAD-2 resin

XAD-2 resin

Reservoir

no

yes

no

yes

Filter

no

no

yes

no

Weather SultabHlty

aH-wsather

warm only

warm only

warm only

Collection Capacity

8L

20 L

20 L

20 L

Surlaca material Shape

The basic MIC samplers have been described by Strachan and Hunuult (1984) and modified as described in Table 1. The MIC collectors have square funnels and a cover constructed of stainless steel with a collection surface area of 0.21 m3. With the cover dosed, sampler dimensions are: 1.2 m high X 1.0 m long X 0.5 m wide. A stainless steel screen covers the horizontel surface next to the funnel to reduce rain splash Into the funnol. A moisture sansor c o n s i s ~ of two facas at 20" from the hodzontel is held byan arm slightly above and 0.5 m to the side of the sampler. One MIC sampler was modified to include compound isolation by passive solvent extraction (SM) (Chen and Perkins, 1989). The SM sampler has a stainlass-stasl funnel surface with heating cable attached to the undendde of the funnel for all-wsather collection. Precipitation flows from the funnel through 1/4 In. Talon tubing to the bottom of a 4-L amber bottle. The bottle bottom is covered with 200 mL dichloromathene (DCM), about 3-4 cm, through which raIn r~__~ps_ and orgenics ere collected. An overflow 4-L 10cttleis coonected by a sclenold-valve rasuIting In a collsction capacity of 8 L In this design, rain In e~xcessof 8 L over a two-wask padod is not collscted. The resin MIC sampler (RM) has a Teflon-coated funnel surface with a collection area of 0.21 m2. A twoJitm glass rasenlolr covered with aluminum foil to minimize photolysia is located directly below the funnel and followed by a Teflon cartridge containing XAD-2 resin (Figure 1). The Teflon cartridge is made of 0.5 cm thick Teflon pipe, 15 cm long with an Inside diameter of 1.5 cm. Stalnlass-steel fittings are located on sach end of the cartridge and glass wool placed at either end holds the resin 10~lce. Row through the resin cartridge by glavRy is about 40 mL/min necessitating the glaas reservoir to reduce atmospheric exposure of water in the funnel. Water from the cartridge flows into a 20 L plastic carboy to monitor the volume of 01tinpPo¢~qT~xd.

346

e~m

p

P ~ m m m m mmmm,

1.1rfl SCHEMATICOF RESINMIC (RM) ~JAIq.B:I (AFTER8TRACHANANO I.IJNEAI.LT,1984).

Tho filter MIC sampler (FM) also has a Tellon-coated funnel sudace with a collection a r ~ of 021 m2. Tho FM sampler is similar in operation and design to the RM coL,~__~except an in-line filter is ImmdlKI Jut above the rmCn carUtdge. The liter w u a 47 mm GelrnanAE gkmsfllxetitwheld in a Necom TeAonliter auembly. Tho Aerochem Metrics sampler (RA) is an a~__~J_, wet-only p r o ~

collector modified to hive gl Tldlon-

coated, circular surface of 0.08 m2 sudace area. Tho ump(er was modified for in-s//u compound isolalion by I 1 ~ of a g~assreservoir and Tenon-cartridgeconlaining XAD-2adsorbent main similar to the d e ~

of ~

RM ~ .

1"heRA

collector 18constructed of 0.4 cm thick aluminum and hal dimensions 1.3 m high X 0.4 m wtdo X 0.9 m long. Tho k l o r g ~ verldon ofthb umpler Is commonly LL__~_In U.S. acid mln Addltlonaldetaismgardingdesign detai~lredeocdbed In Elmnretch eta/. (1987). The FM m m p M r m o n l o e n t o the project by Dr. Msds Luc~ of the Ontario Mlnlmw af the EnvlrommmL The ,~AIc~Ikctor wM on loan to the ~

by

Mr. C.H. Chan o( EnvironmentalCanada. Preclp#ationwas collected In periods ranging from5 to30 dayl depending on rainfall amount a l ~ tors are deeigned to operate for a two.week pedod. The amount of l x ~

Ihe collec-

at the CCNHA aite w u rmmmm¢l by two

4-Inch rain gaug~and recozled to the nem~;O.011R Any mmdingwJer In ~m~pkwfunn~s or ~

morvoimw~

passed through the cartridge using an in-line pedaaRic pump. Tho volume of water passed through the I ~ collected in tho cwboys w u m~__~_,mdand ultlmamty compared to the lheoretk:~ rain voltmwl ~

and

on rain gauge

mmmreme~. The procedum for reldaclngtheremcartrtdgew~slndarforaUthreerminmmmm Thecamidgev,~ disconnected, capped, labeled 8nd w r ~

In Al-foN. The funmd mJ,rfikcewas drwed w#h 200 mL of amivont(__w~_._.,~neor

methanol)which was collected in 250 mL glass 10oldiesand arm'yzed S e l ~ was flushed wRh 250 mL of MHII-Qwater and the m

~

for about one-half the i~udy. The umpler

cartridge insta~¢l. The ~

canddge ~

wenod by

poudng 250 mL MB-Q water Into the collector funnel The 8M lw,pler bottles were changed In a sirnklr manner. The 4-L amber glau bo~m conlmlng me m

~d

DCM were disconne(:tod and capped, and the funnel wm ~'.-,~,dwith solvonL Then the mmlder w u Ikmhll with MB.Q water, the r e ~

boales aUachedand the systemwetted with 250 mL of MIIII.Qwater.

347

The m~tor drlv~ rakl 8ormonl randl i ~ner me(:tlBnk~ pwt8 ot I c h Imnpklr were exlllMed Jot w~lr ~

~-

n * ~ ~quJmW~ or pen n m l ~ e m e ~ were rrmde,., nmuir,d. ~ M ~ I ~ M mmeme~, NI g l m m

~ d Tellon or ~

wmr, acetone, h , ~ solv,m ~ ,

~

4~bo~

IImn~ were d i n e d wth eoap ,rod womr, rimmd wth w i r e wler, MBI.Q

end dried m 110"C. The XAD-2 mein w ~ c l i M d by m~umul/4e-hour ,Memlme wire me

m

h ~

~1 aoM~m m

DCM, h~ene, ,,:.¢on. end m,mmoi, m.n r m d .nd .wmd i~ l I . O

F~k~

i

~ ~

0mc~ u l u m i ~ N t~ m 8 e k ~ ~ d A m ~ w n 0udc~ ~cl JWcmm

Figure 2 deplcts the rumple prepemU~ and ardylk~l schem ruled In this ~udy. A 10di'8ummiy wll m provkkmd

lwe bu~ detd8 Kel,o~mmiInEiw~mld~ ~ . and d 1

~

M ~

0~.

M mampkmeeJrwJmawJmwmm mpka:lwlh I

.

~

recovery anslytlm pdor to mtrlu:tlon. Tho 8M lampklo o¢lnildningDCM m

a 5-1.sepermmy fu~ui with aciditJonai[X?,~. The XAD-2retainemdflltm m

~

Mlux m ~ l c t N In

In a So~I'~ llppmmm lot 24 houm

each with methanol and DCM. The ~lvents were cxxnl~nedancl bock.exmlct~l wire w t e r to remove m~hlm~ Imd vmter.

If floid rirmm of the funnel were no( emWyzeduperat~yo they were lldded hem to the DCM ~

~

were dded

over 8 r d ~ r o u 8 Nse~24, c o n c e n m e ~ to 8_~_~ S mL in a ~

appmmJ8 where DCM w m e ~ m g o c l to

hi~ane, and ~

wm q~iit with 25% o( the vollumodedioMsd

to 2 mL under 8 gende ~rmm ol purikid Ns. The ~

~ an~ym ~ P~e~'Y~ ~

hydrocarbons ( P ~ ) emdme remeJn~ to cr~or~md h y d r o ~ . ~

FIGURE 2.

AnRIvtteml

prneed.rl.

I :-I

"" memo Gc ! m m -so { 21 m laUBC

II~,1,., |

I

I

I=

stt.u~--...~ .,,h i..m-

+ .~--,.~

s'~ mm~* M e

I

amkuml

I

(C~).

348

The extract was cleaned and fractionated for CH analysis on a Flodd column (13 g; 80-100 mesh; 1.25% deactivated) and aluted with 60 mL hexane (PCBs; Mlrax; p,p'-DDE) and 50 mL of 10% (v/v) dlethy~ther Ii1 Ilex:Brle. The fractions were concentrated to about 5 mL ualng a Kuderna-Danishapl:matus and to 1 mL under a gemfa Smlsm of p u d h d N2. The PAH stib;~-tion was analyzed without ftather cleanup by Isotope dlutlon high resolution glmm caplMry gas chromatography - mass salectlve detection (GC-MSD). The samples, blanks and stsndards were spiked with an internal standard mixture of 5 dsutedum-labeled PAl-ls (ds-naphthalene; d

t

~

:

dt~mzo[1]anthnmene; d~-

benzo[alpymne; d12-benzo[1]pcrylene) corresponding to five different setectlva Ion monbxing (SIM) groups.

This

procedure Is similar to that used by McVesty and Hites (1958). The spiked e~racts were concentrated to 200 uL Lining purified N~. and analyzed using a HP 5890 GC with a HP 5970 MSD and HP 5997B comptdmwcrkatmloR Tbe Mmclwd used to calculate individuel response ratios was a mixture of 16 PAHs to which benzo[3]pyrene was added. PCBs and other CHs analyzed by the Internal standard method were spiked with 2 , 3 , 5 , ~

and

2,2',3,4,5,6"-hexacNorobipher~, extracts concentrated to 100 uL and analyzed on a HP 5840A GC with a °aNI electron capture detector. The analyses for PAlls and all CH$ were pedonned using a 5% cross-linked p h ~ h ~

~

giess

capillary column of dimensions 25 m length, 0.31 mm i.d., and 0.52 um film thickness (HP 1g091B). Detailed chromatographic conditions may be found in Eisenrelch et al. (lg87). PCBs were identified and quandfled using the procedure of Capel et al. (1985) and the internal standard technique with response factors. Total PCB concentrations were calculated as the sum of 38 congeners of greatest weight fraction in Arodor 1242, 1254 and 1260. Chlodneted benzenes were identli~d and quantified using the external standard method. The analytical procedure was characterized as to detection Iknits of the salected 14 compounds, procedural blanks, recovery of compounds spiked into the resin or exlracts, the recovery of surrogate compounds spiked into each semple and the ability of XAD-2 resins to recover compounds of Interest. Working detection llmlts based on an 8 L sample were: PAHs, 0.01 - 1.3 ng/L; PCBs, 0.001 - 0.03 ng/L for individual congeners and 0.04 to 0.54 ng/L for total PCBs; 0.005 0.07 ng/L for chlorinated pesticldasi 0.001 - 0.5 ng/L for chlodr~__,~_benzeue¢ Blank concentrations In the XAD-2 resins based on an average 8-L rain volume were: PAHs, 0.1 - 1.7 ng/L; PCBs, 0.501 - 0.2 ng/L for individual congeners and 0.2 0.7 ng/L for total PCBs; chlorinated pesticides, 0.001 - 0.4 ng/L; chlorinated benzem)s, 0.01 - 1.9 ng/L In general, blank values were less then 10% of measured sample values. The XAD-2 resins exhibited very high ~

bfanks

prohibiting quantification. The SM sampler generally exhibited much smaller' blanks. Laboratory studies of PAH snd PCB spiked Into XAD-2 resin cartridges yielded 70 to 95% recoveries. Recovery of procedumJ spikes were generally about 70% for all compounds tested. RESULTS AND DISCUSSION Rain Colfaction Efficfancv lind Field Performance The ability of precipitation sempfara to efficiently collect rain under environmental conditions is crocial to determining accurate concentrations and fluxes. The samplers were deployed in the flald on 8 Msy, 1986 and the last rain sample collected on 13 October, 1986. The total rainfall measured with the two rain gauges averaged 55.1 cm with less than 2% difference between gauges. A continuous recording rain gauge located within 50 rn of the sampling platform showed cumulative rainfall of 55 cm over the same period. The collection efficiency of each sampler was detlmnined by comparison to the theoretical collecticn efficiency based on the duplicate rain gauges ~

on the sempUng platform.

Table 2 lists the rain collection efficioncies of the SM, RM, FM and RA rain collectors. Excluding the ~___~ when various malfunctions occurred, the average rain collection efficiency was about 95%. Including anomolous ~

collection

349

e t : i e n c t u wem~reduced to 8090% depending on the mmpler. The RA sampler ~ ~ ~ ' = o r .

Orce r e l ~

mdy P r O m

rain coilection emclend~ went from e3% to 1 0 1 % o f ~ .

with Is

TIt~blngood

agreement w=h repoc~d Aerochem Maric r~n ¢ d k m t ~ emdenc~ of eO-~% (Chart eta/., ~m4; Graham et #.. tees; Wiley et a/., 1 ~ ) .

Large devtWions from 100% collection effk;kmcy for MI iMuxtplers~

nuts on vo~ting anne vandalism and evaporation of water when Row t h ~

from blown fi__m~=__,~ - ~ c l

the nmin ~ p

m

~ .

When rains

exceeded 3.8 cm over a two week collection period, excess rain (>8 L) from the SM Mmlder was not colected and therefore, was not measured. This may be easily remedied by adding a 20-L carboy as a collection device. TABLE 2.

Rain Sampler Collection Efficiency (%) Rain CoUe~or FM

Collectlon Efficiency

SM

RM

RA

Overall Average

90

9~

89

82

Excluding Malflmct~s

94

96

96

96

Standard Deviation

10

10

6

14

Table 3 lists the mechanical and operational problems obunted In these four samplers and likely to occur In any set of wet-only, integrating rain oollectors. The MIC samplers suIfi,-i~ from mechanical weekneu ruuItlng occalk)naly In the sampler cover not opening. The rnechanlsm of opening and doidng the cover Is not designed to sustain the generated torque. Thlscan be remedied bystrengthen~lhemecilank~armsand connectio~ to the drtve motor. Theolhermaln problem was water standing in the RM and the Fld samplers as a result of IMuggedfittings, filters and/or carlddge. This can be remedied by incorporating active or passive pumplng into the flow stream such as has been done for some samplers (e.g., Pankow et al., 1984) TABLE 3.

C: F: O: R: S: X: ?:

Mechanical and Operation Probleml Encountered During Reid Evaluation.

Date

SM

RM

FM

133 163 174 182 190 195 2O3 212 223 237 255 265 286

0 C 0

F,C

F F

RA

?

C R 0 0

cover open on ardval standing water In funnel overNowof collection bottles standing water In reservolr mobtum een=x malfunctlon blown fum carboy empty, cause unknown

R R

F

S

F F X F F,C,X R,C

R R R

350

The RA rain ¢~llector w ~ the r n ~ meol~nk~y ro#~le umpler evaluated. The ¢oun~-Imlimced cover prevented the stndn thet ¢ontdbuted to the MIC malkmc,o~ D

i

~

of tho P~ indude a n d ~

ineem#lvo rain

saneor (i.e., slow) and the small funnd collection arm. Cheneta/. (lg84) also nofed that the Aerochem Melltc's er,,-,~3,-was slow to re~ocmdsapeolaNyto light p r e o l ~ .

The collection of smaller volumes and therefore i s ~ c c x ~

mm~ cen

d _ecm~___detectabi#y. The sampling train of the RA sampler was similar to the RM sampler, and occasional plugging of the water flow train was encountered. Samoler Evaluation Based on AnaMical Data

Volume-WeightedMean Concentrations The amity of the four rain samplers to collect trace organic contaminants In rainfall was ~

for fourteen

compounds typical of compound classes and a range of phyldcel/chemicel propertk~ Table 4 preeenll the volume-

weightedmean ~ r a t i o ~

(VWM) of the fourteencompoundscoaectedand analyzed,and the propsgmd wror (one

standard deviation) associated with each.

Volume-welghted averaging minimizes the effect of smell ~

concentrations associated with these small rains skew an arltfwnetl¢ mean to values not truly r

e

~

concentration that is estimated to occur on an annual basis. The VWM concentration was calculated as: VWMI = MIj/Vj ==(Cll x Vj)/Vj (6) where VWMj is the volume-weighted mean concentration of compound I, MIj is the mass of compound I in the jth rain intental, V is the volume of the jth rain interval and Ctj isthe concentration of compound i in each jth rain interval The propagated errors listed were calc.lated according to the method outlined by Shoemaker eta/. (1974). TABLE 4.

Volume-WeigMed Mean Concentrations for Fourteen Organic Compounds in WM-Only - 1986 (nn/L)

Samp~r Compound

SM

RM

FM

RA

Phenanthrene

8.6_+2.1

15.4_+3.8

8.8_+2.2

11.2_+2.8

Chrysene

6.1 _+1.1

6.5_+1.2

5.1 _+0.9

5.6_+1.0

Benzo[a]pyrene

1.4_+0.4

3.3_+1.0

2.9_+0.9

3.5_+1.1

Benzo[ghl] perylene

2.2_+1.0

1.9¢0.9

1.4_+0.7

1.5_+0.7

Total PAlls

53.9

60.5

44.4

54.2

1,2.4-Trichlorobenzene

11.7-+1.2

4.1 _+0.4

10.7_+1.1

10.7_+1.1

Hexachlorobenzene

0.44_+0.05

0.19_+0.02

0.12_+0.02

0.52_+0.07

p,p'-DDE

0.73_+0.31

1.14_+0.46

0,25_+0.10

1.32_+0.55

Total PCBs

2.6_+0.6

2.3_+0.5

2,7+0.6

2.8-+0.6

Congener 31

0.16_+0.03

0.12_+0.02

0.19_+0,04

0.13_+0.03

Congener 70

0.16_+0.05

0.09 + 0.03

0.09_+0.03

0.14_+0.04

Congener 110

0.15_+0.04

0.11 _+0.03

0.09_+0.02

0.11 +0.03

0.05+0.02

0.06_+0.02

0.09_+0.03

0.04_+0.01

0.024_+0.035

0.031 _+0.006

0.07+0.02

0.08+0.02

138

Congener 180

High

of the overall

351

T ~ foummn c~mpound, dmwr,n U,~ phys~cJlmmnt~ Wopenm. ,m,cWUon,n Um ~

(v,,l~rl~

dlxtffoutlon) and concmnlmtlonin raln. Total PAH V'~Id valuta nmoehom 44t0 61 n o / q . . d q ~

on Uml~X'. xnd

~.I=OSsranged from 2.3 to 2.8 noIO "r~ propaomsd wrom vadsd wth ,~n~=,oundand occumzsdOmmmly In tlm nmgs of 10to30%. Tho pdmsry q,____,~tJonaddressed by this data set is whelhor VWId coromerution8 of eech of the Irouftaon compound8 obmrved Inthe SM, RM, P"M and RA samplm'8worn 81gnlflcanl~ dlfforent. A reiMlld ~___m~t~1___llwltgthsr llny 81gn~

dMeroncos could be attributed to c h a r a c t o ~ of the rain 8anlpier8 and/or c o ~ . ~ _ _ ~ The I p l ~

to answer those questions was to calculate the VWM c o n ~

and 8 8 s o c ~

~

~'-,oion

ononk I : ~

uNd

to eslJmatothe la~er were uncerlalnUes Inthe meaurement d mln vokJme, delermlned mmmm of IndNklml compoundx

and l:)rec~n of armb/U~ nmssurenmms, Figure 3 pnmm~ mo VWM concentratlons and pro~gamd errors (ono standard de~aJon k~r plmwmrene, chrysene,benzo[a]pymneand benzo[ghq p e ~ i ~ t h e S M , RM, F M s n d R A s ~ VWM conc~-~i/allonso v ~

exhil~ing no slgnircant diffenmcm. The orlly excol~on 18benzo[ll]pymn~ In Iho ~M I l m l ~

exhib#blg a VWM value about 50% of t h o u observed for the other s m l q ~ coml0m~d to the otlt~x Is the mode o~c o ~

The pdmmy d l l ~

Imol~tion;th@SM mmpllr ~ n ~

the fl~id wher~s th@others emp4oyXAD-2 ruin a d ~ . DCM In a b a t c h mode.

In genend,theen~rbem~rme in t h l 8M lanq31er

~__r~_ 10~tch~

~

~

~

It is OikMyth~ pe~iculM~ B(a]P Is not efficlenily e04mctedby

The SM has a stainlesHteel sudace (as d o n the RA sandier) which did not e0dVbita vddely

different VWM concenuation. Neither lost rain volume nor occurrence of benzo[a]pyrene explain the d i ~

since sub.

stantlaJvadatk~ were n~ ot)wcved for other cornpounds.

plmnm 20.

10

tt+t 0

e.

o

umm

¢ o o ¢ o

~

mmm

M

B~o(g~,l)peyluo

nenzo(n)PFone

0

S

W

2,.1

tt O'

a FIGURE&

m

m

RA

|

|

~ (VWM)CONOENn~TION8N~IOmOP,~AIED ~ R~I.EINFFI~PITATIONFORTHESM,I~t, FMANOFIAS.~Iq.B~S.

m

RA (ONESrNcNI) OL~AllON)FORFOUR

352

Figure 4 p m m ~ the VWM concemratio~ and mmc~med ~-o-;~.-~_~ =ram for a group of CI-I= including 1,2,4trlchlorobenzena ('rCB), haKachlorobenzene (HCS), p,pt-DDE, two ~

congeners having 4 and 5 ~

and

Again the VWM ccmcemrations were not edgniflcantlydilfamnt. Excaptio~ to this rule are TCB in the RM sample, p,l:YDOE in the FM sampler and HCB for which VWM concenlrations stratify into two groups differing in concentration by il factor of about 3. The RM and FM emmpiersoccasionally hed standing water in the furmei or esmpllng train due to a beckup in the resin column. This may have resulted in enhanced Ioeses by volatifization. The Iowvalues of RM and P~I compared tothe SMand RA samplers maybe dueto the clogging problem noted above. L__n~s__to thecoilector sudaca cannot givathe same results since the surface was rinsed and the dnse = r m l ~ w#h the resin. The RM and FM samptem both hava Teiton surfacas which may in some cases cause problems with sorption. C o ~ s pressures might be expected to exhibit more severe s o r ~

having lower aqueoue ~

problems; they ~

and vapor

do nOL

These results are consistent with the hypothesis that the ~1, RM, FM and RA samplers am equally capable of provUing comparable concareration data expresesd es VWMS` We =¢,9e~.__thet ~ between samplers may he mostly due to rain water being ~

dWermcm in the VWMs

in the funnel rather than in the rain ~ .

problem is restricted to the resin samplers. Future samplers employing adsorbent cartridges ~

This

be equipped with ilmall

In-tlne peristaltio pumps linked to the funnel covadng mechardsmor acltvated by allow or votume sensor. VWM concentrations were calculated for all PAlls and PCBs analyzed in 1986 rain. Figure 5e=shows a compedson between the VWMs of 16 PAHs for the samplers with XAD-2 resins es the mode of compound isolation. "ntere is gansrMy less than a 20% ditfarence between the VWMs of thesa sampienL The biggest difference In VWMs occurs for phe~nlhrene for which the RM, FM and RA samplers give concentrations of 15.3, 8.8 and 11.4 ng/i., respectively. Dil~rences are not attdbuted to the relative concentrations of PAll in rain or physical/chemical properties of the compounds, Figure 510shows a comparison of the VWM of the total sample population and the values extdbited for the SM sampler. The agreement in all cases is very good with the resin-based samplers providing on average 5 - 10% higher VWM conce,~t~tions compered to the SM sampler. Figure 6 compares the VWM concentrations of 30 PCB congeners ranging from 2 to 8 chlodmm in the samplers employing only the XAD-2 cartridges. In general, the FM and RA samplers exhibit an equal number of highest VWMs and the RM sampler the highest number of low VWMS` This suggests that the RM sampler is less effective than the other resin samplers in isolating PCB congeners from rain. The mason for this behavior is not dear. Although there are 50 to 100% differences in VWMs of Individual PCB congeners across all resin samplem, the values of total PCBs are not signiticanUy different. The lower collection efficiency of PCB congeners for the RM sampler compared to the FM sampler may he due to passage of some fins particles through the resin cartridge alone (RM) w(th Increased retention by the filter/resin combination.

An alternate explanation may be the Inherent uncertainty in quentlfying trace concentrations of PCB

congeners. A direct comparison between the VWMs of Indlviduel PCB congeners for the SM and all samplers shows differences ranging between 20 to 50%. NI rain samplers show a predominance of 2 through 5 chlorinated species. This pattem is similar to that observed In air and water samples coUected on Lake Superior in t986 (Baker and EIsenreich, 1990). ANALYSIS OF VARIANCE The results presented thus far suggest that the organic compound collection efficiency for the four samplers is no( significantly different in assessing annual concentrations and flukes. However, It does not account for variations in compound collection efficiency in the same rain pedods` To test whether event-to-event variations in compound concentration show a statiMJcaJlysignificant difference in a samplers' ability to coUect organic compounds in rain, a one-way ANOVA

353

1,2,4.TCD

nCB

IS ,-

O.TS ]

10

t

++

+ L

0.5

O.H

!

t

su ¢1

m

m

suture.

.A

p,p'-DDE 13

¢

=o

c0.~r~ 23,4',S-Teb-~B

0,1

¢ 0

0 ¢

0

u | t>

w

nu m nA

Congem-110 233,4',S-PemCB L!

wmm

~

Total PCDs

tt+t summ

FIGURE4.

l

0.1

~

umm

VOLUME-WEIGHTEDMEAN (VWM) C(~ICENTRATION8AND PROPAGATEDElad~OR8(ONE STANDARDDEVtA'r1ON)FOR SiX ~ T S D ~ I N PRECIPITATIONFORTHESM, RM, FMN~)PASAMPLERS. (1,2,4-TCB,, 1,2,4-

TmC~OROeENm~HOB-H E X X G H L ~ .

354

~'°1

I

I

12~

8

.RM ,A, ERA

4

m

-16 t.

•

"o~

¢ e

-

l

12

O

o c O

o

All Samplers

(B)

[] SM

8

4

~E 0

~=

~

~

= -m- = = - =~ -O

~

~ m

RGURE 5,

COMPARISON OF VOLUME-WEIGHTEDMEAN (VWIvl) CONCENTRATIONSFOR 17 PAHS BETWEEN THE CA) RM, FM AND RA SAMPLERSAND (B) THE SM AND ALL SAMPLERSWITH PROPAGATEDERRORSSHOWN FOR ALL ~ VWM. [PAHS LISTED IN ORDER: ACENAPHTHYLENE (ACY); ACENAPHTHENE (ACE); FLUORENE (FIR); PHENANTHRENE (PHEN); ANTHRACENE (ANT); FLUORANTHENE (FLN); PYRENE (PYR); BENZO(A)ANTHRACENE (BAA); CHRYSENE (CHR); BENZO(B)FLUORANTHENE (BBF); BENZO(K)FLUORANTHENE (BKF); BENZO(3)PYRENE (BEP); BENZG(A)PYRENE (BAP); BENZO(G,H,I)PERYLENE(BGHIP)].

355

0.3

-1 /

•

RM

/

•

FM

0.2

o ~, ,F-

FIGURE6.

Olin

,~ t'~ ~1'

ql'

p , , i,~, ~

ODO)

,

'P" ' l "

¢~

~'

aD

I¢1

CO

COMPARISONOFVOLUME-WEIGHTEDMEAN( V ~ CONCENTRA~ FOR30 PCBSCONGBCB:~USTB},MC~,ROINGTO IUPACNUMBERBEI1NEENTHERM,FMANDRA~I~MPLERS.

comparison of compound behavkx was performed. Event-to-event variations in PAl-I, PCB and other CH cG,-,~,,,i,~ons can be found In Eisenretcheta/. (1987) and are the source of a separm manuscript (Ebemetch eta/., in ~ ) . A one-way ANOVA compadson of the fourteen selected compounds was conducted to te~t the null hyp01hem that them is no difference be~:.'.c.--tsampler behavior based on the event-to-event ~ transformedda~a are ~ e d

The ANOVA caiculJom on log

In Tal01e5. The mean square In cokJmn 1 represemthe vadance between mmldemand

the mean square of column 3 designmd "reaJduai" r e W e m ~ the variance v ~

mmplers. The F value of column 5

reweaems the ratio of the variance of the sampk) moons to the variance o# all sample. The last column prmmms the resultsof theANOVAwithrNpect tothe null hypothes~ ff the calculated Fvaluelsleuthanthe'cdticar FvallJm (2.23 for 90% conlk:lence; 3 degrmm of freedom In means; 40 to 50 degre~ o# freedom in samples; F = 2.84 for g6% conlklence), then there is a greeter variation between samples than between samptem. The last column In Table 5 Indicam thst the behavior o# phenantt,'ene, benzo[a]pyrene and PCB congeners 138 and 180 suggest a statistically signilk:am difference in the four samplers. For phenanthrene, thedilfemnceisallributed to v a d a l k ~ in the SM umtpler. The dNMten~ in collec. tion behavior o( PCB congenem is attributed to variations in the RA mmpler. In general, thNe daR ~ hypolhem that there is no or Iltlle slgnllk:ant difference in the organic compound collection ~

~ ~

the null 14 ~

compoundeamong the samplers, Where diffwenc~are signBcant, no consistent pattern emerg~ lmg*J~,~g Irtalytical

356

cauess may be re~,~,onelbiefor some of the obesrved veriatlon. The RA sempisr hes a colleclion sudaca Imm appmMmataly 30% less than lhe MIC samplers. C o ~ ,

less mess of the compound is avalisbie for esch esmple p o t ~

Increadng the uncertainty of these meuurements. TABLE 5.

Fleidts of ANOVA Comparleon Among oil 8amplem for 14 Se._",~_-_-d_Compoundl Listed In Tlmble4 UMno Leo.nonnsllzed Conce,-,~,~-;;ons.

Compound

Mean Square Main Effect (Sampler) (a)

Dngmes o( Freedom

Mean ,Square Degrees of Residual(b) Freedom

"F: Value (c)

Dlfemnce among Sampler=?(d)

Phen Chr B(a)P B(ghi)P Total PAHs HCB p,p'-DDE Congener #31 Congener #70 Congener #110 Congener #138 Congener #180 Total PCBs 1,2,4-TCB

0.905 1,236 6.983 0.730 0.323 0.955 3.199 0.260 1.603 0.854 0.959 4.158 0.262 4.132

3 3 3 3 3 3 3 3 3 3 3 3 3 3

0.274 2.415 1.185 0.588 1.527 1.127 1.882 0.759 0.742 0.528 0.315 0.539 0.381 2.857

3.307 0.512 5.895 1.241 0.614 0.847 1.700 0.342 2.159 1.617 3.049 7.708 0.728 1.446

yes no yes no no no no no no no yes yes no no

39 39 39 39 39 38 38 45 46 46 43 42 46 46

Notes:

(.)

(b) (c) (d)

Mcan Nuare represents the varisnce between sempkw merina | n d equals (VIi'. 0)2 + 4(Vor. 1)2, where (Vii'. 1)2 is the vadanns between samplor~ Mean squem residual r e ~ the variance within all samples = (Ver. 0)2. The "F" vafue Is the ratio of the variance between the lampler means and the varisnce within d oomples. For a 90% confidence Interval, the cdtical "F" value - 2.23, while at the 95% confidence level, the cltUcal '1=" value - 2.84 "rhe null hypotheMs Is that there is no difference among the Immpiors (Le. (Vat. 1)2 - 0), vdldch IS Inae if the calculated "F" value < the Orltical "F" value. This suggests that there is greater ~ ~ the mmpiss than between the rain samplers. If the calculated "F" value • the ¢dtical "F" value, the null hypothesis is reje~_._=dand there is a significant difference among the samplers.

RETENTION BY COLLECTION SURFACE Before in s/tu extraction, the rain comes Into contact with the funnel and downstream parts of the esmpllng train.

The funnels have coatings of either stainless stesl (SM and RA samplers) or Teflon (RM and FM sempisnl). The umlpling train consists of Teflon tubing and glass bottles (SM), gises reservoirs under the funnel followed by Tallon c e r ~ holding the XAD-2 resin (RM and RA) or an In-line Nter holder and resin cartridge both made of Teflon (FM). A I ~ particle and vapor scavenging result in organic compounds in rainfall being In either the d~__..Jz~dphase or sseocismd wlh particles. The pertides may become attached to the collection sudace by alectrostatJcforces, and the dimolvad apedes may be edsorbed tothe esmpiing train. To evaluate this phenomenon, cdlection fur~als and sempiing train were rinsed with acetone or methanol following removal of the resin cartfldge Or SM bottles. For sempkm cogected In the flr~ half of the 1986 field season, funnel dnses were analyzed separately from the resin cartridge or bulk rain (SM). For the ~

of

the fiald season, funnel dnses were combined with the resin or SM semple extract. Suq~alngly, a slgnlflcam If not domlnent fractlon of the total esmple mess occurred In the funnel dnses k

~

of the sempisr and Orgentccompound. Figem 7 pmesnts a plot of the pernentage of total semple mess In the dine for the

357

fourteen selected compounds and four samplers. Table 6 Weunts the n~en percentage of totul rumple mmm o ~

In

the ~rm ~r ( : U m of compoundsanahrz~. TABLE (L

I ~ e

of Compound M l # In Fumwl

Sampler

PAl-Is

SM

26

RM

27

FM

24

RA

28

NI Samplers

26

PCB Congeners

Sum PCSs

Cl-Pesticides

Q-Benzen~

8-63

26

17

25

22-72

62

21

32

12-47

28

20

19

13-77

37

15

31

23-55

4O

18

28

The PAl-ls exhlblt a constant fractlon of total sample mass, 26%, Inthe funnel rlnse whereas PCBs eKhlbl wkldy varylng amountL The Cl-pestlckles and Q-benzenes also showa rdath~ly constant fraction ofthektolal sample massto be In the dnse fmctlo~ In all cases, a large percentage of the tolal sample mass occurs In the dnse Indepecdent of sampler, composition of funnel surface and spec~c compound. The RM sampler shows PC8 congenem to be hlghly concentmted in the rinse of Its sample train. The RM sampler has a Tellon collection sudace and a 2 Lglmm remnmk Inthe sample train. The FM mmpier is needy Identical except t has no glass ~ r .

By this c o n ~ ,

the funnel appmm to

comdbute on averageabout 50% of the total mas~,in the rinse and the glare reservoirthe r e ~ PAl-Is In the RM sampler ranges from 10 to 50% and is I n d e ~

~.

The mmnlkm ~

of whether the compound may be dimolved (e.g.,

phenanthrene)or pank:dme (B[a]P). The pattern of mention Is more pronounced for the PCSs. The data Indk~__,,t h t needy all PCB congeners are retained to some e0(temwith sorne a p ~

100% retention In the funnel and glass

reservoir. The morn highly chlorinated congenem (Le. 180) seem to contribute moretothe man In the rlmmthan thele~m chlorinated congeners (I,e.30). The probtems associated with the retention of organic compounds In the funnel and sampUngtrain can be solved by carefully dnsing the sudaces with the a p p ~

wetting sotvent. Thew rinses may then be ~

wlh the m

extract to yidd a precise assessment (~ the concentraUon. However,the probtem does have signilk~nt ~

with

respect to quantlfljlng atmospheric removal processes. Since It is ImpoaJble to determine elther the sl)ecbltlon of the organic compound In the collected raln or the form of the compound In the a l m ~ ,

lltUeInfomtatlon may be ~ c t e d

on the mechanismwith which particulateand vapor species are removed by rain using Integrating samplers. EFFICIENCYOF THE SOLVENT SM SAMPLER The solvent MIC (SM) sampler Isolates organic compounds In mln using passive solvent e~ractlon. The SM sampler has a T~lon tube runnlng from the funnel to the botlom of a samp,ng bottle. The tube extends Into a 200 mL layer of DCM which sentes to Isolate the organic compoundL The e f l k ~

o~ this procedure was t_~t___~J_by ~

the

contents of the firm bottle and the reserve bottle and analyzing them separatelyfor two rain periods during the lge6 field seeson. In general, the high molecular weight PAl-Is I

I

on p~lJcles (Bidleman and Foreman, lgl~) were effec-

tivetylsolated bytheflrst botUe. Alesser portlonofthelowMWPAHswem e f f ~ i s o l a t e d ordm of 20 to 80% of the PC8 congenerswere retained In the second boule w#h the lower ~

bytheflrst boak). Onthe ~

~

~

~

In the first bo~o. Since DCM Is soluble to the extent of 1.5% in water, some of the o~gaNc compounds m~/have been solublbed and beentmnepo~ed intothe second botUe. Indrctency of e0(m~tlonby~mple ~_,~,~___geofme rain through the

358

DCM layar Is slso a llksh/eau~. A solution to t~s Woblem Is to I~We a mb~r In the ~ the ~

el the Irm belllL ~

~

~rmor. A Ixrge¢water smrsge system is xlso needed.

W el m

n" e~

60

i m

W W m

•

40

s.

mRM m.w m RA

0

20 Q L_

>

<

0 m

FIGURE7.

-P

c.I

(..I

o

PEFICENTAGEOF 148ELECTEDPAH8ANOCHLORINAI"ED~ INTHE~ FUNSEFORTHE8M, RM,FM ANORASAMPLERS.COMPOUN08N:IETHOSEUSTEDINTABLE4 EXCLUDINGTOTALPAHSANOTOTALFxT,~TsS.

SEPARATION OF PARTICULATE AND DISSOLVED SPECIES The FM sampler is equipped with a Telk)n-c(mmd colk~c~n sudace and an indine filter ~

~

~ a

Teflon cartridge containing XAD-2 resin. Thefilter Is used toseperale the i:~liculaW fromthe dludvud q=eci~to prevum resin dogging, enhance collection of particulate organic species and to Wovide data on atlno~ohe~ remoqd As slated earlier, the collection funnel retains a signi~ant poctlon of the total sample mass of needy all o0mpoundu among all sampCers. Since both d.___ls~'ed,and particulale qxckm seem to be retldned to variable degreeL it Ix unllmly ~

~ ~

of a filter Is effective at 8pecbWng rain organic compounds in the configuraIion employed In this study. The avum~ percentage of total comp~.~__,ndmass in the sample which was ~

by the glass fibre liter was: P/U-le, 30%; PC8

congener¢ 9-67; ?PC8¢ 2mh; chlorinated peu~,ide¢ 18%; chlodnat~ benzene~ 27%. One advantage of the filter Is to separate dtmt pedicab from the rain which might dog the rmin camtdge. The major dbadvxmage of the ~ W In a gravity flow syutem b clogglng of the filter~

flow,and becklng water Intothe reservolr~

~ .

359

SUMMARY The a l n ~ q ~

is recognized u an I m ~

con~

of orglnic ( : o n t m

to o ~

and I m

environments. In the caw of the LaurentlanGrmt LId(es, It h u been o l / n l t e d lhlt a l n ~ 3 ~ l ~ d e l ~ • ~x~tart U not d o m l w t fracSon of tow k ~ t s of many c h m i c m (Stratum and S~enretch, ~ .

rq~ollnls ~

The o t ~

ofth~

project were to pedorm a field Inter-comparison of four Integratlng, w~-only pmclpblk)n sampkn In an ~ their ability to elflclenlly collect rain and selected organic c

~

The mmpters were e v ~

~

and c o m p l l ~ on

the baals of their ablllty to efficlendy collect rain, exhA)Itmechwdcal rellabllty, demontra~ a d e ~

operJon~ charac-

t__e~__ _ lind Ixovide ixecise mmmxes of wet-only Inpullk The mm~tem dllm'ld In c o l ~

ram, type of c o l ~

tion sudace, mode of organic compound ~

and o

difference between the four sampters w u m e c l ~ equallywall In a u ~

~

~

_

su~

We found lhal Ihe mo~ slgnincwt

relblblllly and o 1 ~

c h a r ~

The i i I I n l p ~ i

~

organic concentrations in rain.

During the 1986field season,wet-only I X ~

mmplem cohered ~

30 days (average 14 days). Sampleswere analyzedfor about 79 c c l n p ~

Integrated over pedodl of 5 days to

Including 17 PAl-Is, 38 PC8 C O l ~

ind I!

suite of CHs. Fourteen of these compounds selected on the basis of dilfedng physical/chemical p r o p w l ~ and __~3~___.'rence In rsln were ~__-~_ _ lw the basis for the I n t e r c o m p ~ . The four samplers captured fmrn 82% to 90% of the rain gauge precipitation. When pedods of sampler malfunctlonlngwere removed, all mmplers coUectedat about g6% e R ~ .

The slmpie crltedan applled to the qum0on

of whe~er samplers pe~ormed dlfferen~y was whether propagated error 10amoverlapped for VWM coneentrll~k)~ for individual compounds for different saml:lers. With few exceptions, there was limb or no signilk:ant d i m four samplers based on VWMs. A one-way ANOVA compedson of ~ e 14 compounds w u c o n d ~

between the to te~ the nuU

hypotheslsthat there Is no difference between sarnpler behavlor bued on event-to-ever~varlatlonL W#hbweae~XlonL these datll support the null h

~

One characteristic exhibited by all compounds and all m n n ~ coi~

is the reWntion of organic ~

surface and/or sampling trab. For e~smpte, an ~erage of 28% of the PAH and 40% of the tolal I ~

rain samples occurred in the sdvent rinse of the funnel. Although not a prol=iem In ~ fluxes, this phenomenon makes the d e t e m ~

on the nims in

total c o r ~

of compound speclation in rain and of a t n ~ o ~ h ~ removal

pro~em~k:us~g~ . , t ~ g ra~ ~n~erL The~0y-sk~opera~k)n perm~edcom~ar~O~m~ervw~t~ty. These data suggest that the expected uncertalnty in atmoephedc loading estlmates of trace organic sul~;-,,~,,~s may be no better than about 20%. ACKNOWLEDGEMENTS This researchwm funded by the Great Lakes National Program Office of the U.S. EnvironmentalProt__~__Agency under Grant No. R005840-01. We acknowledge and ~

the laboratory a s ~

of Rob I - ~

intellectual stimulation of conversations with Joel Baker, Mad( Sandllom, Judy Pedinger and Noel Urban. We ~ Mr. C.H. Chart (Environmental Canada) and Dr. Marls Lucis (Ont~io ~

and the thank

of the Environment)for the loan of modlned

MIC samplers. The guldance and cooperation of Wayne Wlllford, Peter Wlse and Ed ~3apper~i~ (U.8. EPA) Is

appreciated. REFERENCES Aim, E. and Glmn, C.S. (1981) Globel transport of organlc pollulan~: ambient concentratlons In the remote marine atmosphere. Sc/ence, 211:163-165.

360

Atlas, E. and Giant, C.S. (1985) Sea-air exchange of high molecular weight synthetic organic conqxxmdL In The ~ Ab~ P,_~

~

in ~

of

Cvdk~ (edited by P. Bumt-Menard). NATO ASI Si,~,~ #185, D. Reidel

C,~: Dordred¢ 296-329.

Baker, J.E. and Ekmmek:h,S.J. (1990) ConcentrationandtlkJxesofp~icmomatichydrocerboneand pofychlodmj~d___ blph~sacroestheair-water Intedace of Lake Superkx. F_mdron.Sci. Tech. 24".342-352. Bidlernan, T.F. and Olnay, C.E. (1974) Chlorinated hydrocarbons In the Sargesso See a t m o ~

and water. Sc/ence

183"517-518. Sidlernan, T.F. and Foreman, W.T. (1987) Vapor-pertidepanl~ofseml-volatle o r g a n i c c o ~ Fates of Aotmt~ Pollutants (edited by R.A. Hites and S.J. ~ ) .

I n . ~

Adv. Chent Ser. #216, Amedcen

Soc~ty: WaMlington, DC, 27-56. Car)el, P.D., Rapaport, R.A., Eisenreich, S.J. and Looney, B.B. (1965) PCBQ: C o m ~ e d and congeners In environmental esmples. C h e m ~

quantBnation of total

1¢439-450.

Chen, C.H. and Peddns, L (1989) Monitoring of trace organic contaminants In a t m o ~

~

.

J. Great Lakes

Res., 1S:405-475. Elsenrelch, S.J., Looney, B.B. and Thomton, J.D. (1980) Assessment of airborne organic conmminanm In #m Greet Lakes ecosystem. Science Advisory Board, I m ~ i

Joint Commission, Windsor, Ontario, 150 pp.

Eimnmich, S.J., Looney, B.B. and Thornton, J.D. (1981) Airborne organic contaminants In the Great Lakes ecceyfem. Environ. $ci. Tech., 16:30-38.

Eiesnretch, S.J., Franz, T.P. and Swanson, M.B. (1987) Field i n t e r c o ~

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wet

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