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Evidence of currently-used pesticides in air, ice, fog, seawater and surface microlayer in the Bering and Chukchi seas
Pergamon 0025-326X(95)00216-2
Marine PoNulion Bulletin, Vol. 32, No. 5, pp. 4W419, 1996 Published by Elsevier Science Ltd Printed in Great Britain. All rights reserved 0025-326X/96 S15.00 +O.OO
Evidence of Currently-Used Pesticides in Air, Ice, Fog, Seawater and Surface Microlayer in the Bering and Chukchi Seas SERGEY M. CHERNYAK, CLIFFORD P. RICE and LAURA L. MCCONNELL US Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705, USA
Investigation of currently-used pesticides (triazines, acetanilides, organophosphates and organochlorines) was carried out in the Bering and Chukchi marine ecosystems in the summer of 1993. Chlorpyrifos and trace levels of endosulphan were the most frequently identified contaminants in seawater, chlorpyrifos and atrazine were found in marine ice, and chlorothalonil and trifluralin were found in surface microlayer samples. Concentrations of chlorpyrifos were highest (170 ng 1-l) in marine ice and higher in seawater (19-67 ng 1-l) at locations which were closest to the ice edge. Endosulphan was found as a widely distributed currently used pesticide in the polar atmosphere. The greatest concentration of any one single agrochemical was trifluralin (1.15 pg 1-i) in a Bristol Bay surface microlayer sample. Arctic marine fog was sampled and for the tirst time, several currently-used pesticides (chlorpyrifos, tritluralin, metolachlor, chlorothalonil, terbufos and endosulphan) were detected at concentrations several times higher than in adjacent waters or ice. Published by Elsevier Science Ltd
Certain classes of pesticides (triazines, acetanilides, organophosphates) are heavily used in agriculture in northern countries. Their use has been increasing steadily since the late 1970s (USDA, 1991). These compounds were designed to be less stable than organochlorine pesticides. Theoretically they should not accumulate in the environment and should have only minor effects on local ecosystems. However, special features of Arctic environments, e.g. low temperatures and low solar radiation, slow down the normal dissipative and destructive processes which protect less vulnerable areas. It is therefore important to carry out investigations of the distribution and behaviour of currently-used pesticides in remote Arctic areas. There is already considerable evidence of worldwide distribution of several persistent chlorinated organic compounds. Explanations for their occurrence even in remote and pristine environments have now advanced to the level of accepted theory, (e.g. Wania & Mackay, 1993). Replacement chemicals have reduced persistence 410
and lower environmental mobility than chlorinated pesticides. With these changes, the assumption has been that Man does not have to be as vigilant in monitoring long range dispersal of the new class of chemicals. The sampling phase of this study was carried out as part of the Russian/American co-operation in environmental studies, the BERPAC project, a detailed investigation of ecological conditions of the Bering and Chukchi Seas and adjacent Pacific ocean (Nagel, 1992). An important goal of this long-term project (more than 15 years) is to monitor the health of the World’s oceans. Searching for new pollutants is a key component of the mission. The BERPAC programme is a part of the Joint Bilateral Activity Project between the US and Russia which was started in 1976, Comprehensive Analysis of Marine Ecosystems and Ecological Problems of the World Ocean. The specific objective of this study was to extend our search for currently-used pesticides in intensive agricultural areas, e.g. the Chesapeake Bay area, to the more remote Bering and Chukchi Arctic ecosystems. Protocols which were already in place for our Chesapeake Bay study (McConnell et al., 1995) were applied in this programme. Furthermore, since fog and ice frequently occur in this area, specific sampling was carried out in order to collect and analyse for currentlyused pesticides in these matrices.
Methods The fourth joint BERPAC expedition consisted of 63 oceanographic stations composed of transects and six polygons. The expedition took place from 1 August to 18 September 1993. A subset of samples were collected for analyses of currently-used pesticides in the following strata: seawater (two replicates) at nine stations (designated W-l to 9 in Figs 1 and 2); air while underway (A-l to 5), marine fog while underway (F-l to 7), microlayer at 11 stations (SML-1 to 1 l), and ice along the permanent ice edge. For water and air sample collection it was our objective to achieve the best geographic coverage as possible, however, collection of
Volume 32/Number 5/May 1996
SIN
168E
172 E
176E
180
176W
172W
168W
164W
Fig. 1 Sampling sites in the Bering Sea during joint Russian/American BERPAC expedition. Sample types are represented as follows: W = water sampling locations; F = fog sampling locations; A = air sampling locations; and SML = surface microlayer sampling sites.
ice, microlayer and fog samples were only possible when meteorological conditions allowed. Specific analyses were carried out for the following pesticides: trifluralin, chlorothalonil, chlorpyrifos, endosulphan, fenvalerate, terbufos, diazinon, malathion, methyl parathion, butylate, vernolate, simazine, atrazine, alachlor, metolachlor and cyanazine (Fig. 3). Sub-surface water samples from 0.5 to 1 m depth and 76-l 18 1 in volume were collected using a submersible pump. Suspended solids were removed using a Westphalia continuous-flow centrifuge (Thomas & Frank, 1983) and the water was extracted using methylene chloride in a Goulden continuous liquidliquid extractor (Foster et al., 1991). Based on extensive recovery experiments with these pesticides (Anthony, 1993; Foreman et al., 1993), we were confident that the recoveries should exceed 75%. Laboratory recoveries were greater than 90% for all compounds. Octachloronaphthalene and 1,3,5-tribromo benzene were added to samples as surrogate spikes prior to extraction. Each sample extract contained approximately 300 ml of methylene chloride. In the laboratory, extracts were flash evaporated to reduce their volumes further to approximately 10 ml, and then concentrated under a stream of nitrogen to 1.0 ml. Next, sample extracts were fractionated by normal phase HPLC (Seiber et al., 1990) using Partisil-10 (Beckman@ HPLC column) and a gradient of 100% hexane to 100% methyl tributyl ether.
The fractionated extracts were evaporated to 1 ml under a stream of dry nitrogen, 1 ml of isooctane was added and the extracts were concentrated to a final volume of 0.2 ml. All analyses were conducted using a Hewlett Packard Model 5989A GC/MS in selected ion-monitoring mode. The chlorinated compounds, trifluralin, chlorpyrifos, chlorothalonil, endosulphan I and II, and fenvalerate I and II, were determined using electron capture negative chemical ionization (NCI) detection methods. Gas chromatographic conditions were as fo’llows: column J&W DB-5, 30 m x 0.25 mm i.d. x 0.25 pm thickness; column flow 1.2 ml min-’ helium; injector 250°C; interface 280°C; temperature programme 90°C for 1 min, programmed to 120°C at 20°C min-‘, then 2°C min-’ to 2OO”C, followed by 20°C min- ’ to 280°C with a 10 min hold. The source was operated at 2.0 Torr methane and lOO-150°C. The other currently-used pesticides, vernolate, butylate, atrazine, simazine, methyl parathion, malathion, diazinon, terbufos, alachlor and metolachlor were analysed using the electron impact ionization mode (EI). Gas chromatographic conditions were as follows: injector 250°C; interface 280°C; programme started at 9@-150°C at 15°C min-‘, then to 250°C at 6°C min-‘, then to 280°C at 22°C min-‘. The source temperature was 225°C. All injections were made in splitless mode with a 1 min hold before opening the purge valve. 411
Marine
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Pollution
Bulletin
74N
SML-9
I
Wrangel
Island - 72N
W-6
A-4 start ISML-IO
&a SML-8
\
-
‘64N
I 16OW
I 175w
I
170w
I
165W
Fig. 2 Sampling sites in the Chukchi Sea during joint Russian/ American BERPAC expedition. Sample types are represented as follows: W = water sampling locations; F=fog sampling locations; A = air sampling locations; and SML = surface microlayer sampling sites.
Initial determinations were carried out using selected ion monitoring and quality matching routines which included two or more additional ions (Table 1). Structural verification was carried out by selecting additional ions and confirming their spectra by requiring proper ratios of at least four ions for each analyte. Full scan spectra were generated for final confirmations. Water samples were duplicated on two occasions; variations were < 10% for all analytes. Recovery tests for water sample surrogates averaged 50.8 +7.8% for tribromobenzene and 56.7 + 5.8% for octachloronaphthalene excluding one outlier of > 120% recovery. While these recoveries are somewhat low, they are within the range of values observed by others using these surrogates with the Goulden method (W. Strachan, pers. comm.); results were not corrected to adjust for these recoveries. Air samples were collected by passing 27OCL-4400 m3 of air through a glass fibre filter followed by two 412
polyurethane foam plugs. These were extracted and prepared using Soxhlet procedures with petroleum ether for 12-15 h (Billings & Bidleman, 1983). Recoveries of >65% for all of the reported analytes were established using spike recovery tests carried out in our Chesapeake Bay study. One-third of the extract volumes were concentrated and fractionated as described earlier. During the transit from Wrangel Island to Bering Strait a dichotomous air sampler (Glotfelty et al., 1986) was also operated while fog water was being collected. These data allowed gaseous phase levels of pesticides to be determined for calculation of air to fog partitioning. Approximately equal portions of ice (about 0.5 m3) were removed from five locations around the perimeter and one centrally located on the ice flow (Fig. 2). The ice chunks were allowed to melt at room temperature in a loosely closed water cooler. The melted ice (17.1 1) was stored in cleaned and baked 4 1 amber solvent bottles with mercuric chloride added as a preservative. It was then filtered through a glass fibre filter and passed
Volume
32/Number
S/May
1996
H3 CH 2 CHNRNANHCH(CH& Atrazine Butylate
Trifluralin Chlorothalonil
c,AN~o-~oc2H5\ c”‘\ /fT\ II OWS
0-P
CHfH
0 I
O'Wj
I,:
S
Chlorpyrifos
OC2HS H
s
N
f
Diazinon
ii
Endosulphan
I & II
Cl
cH30\~+cH,~~-oc,H
NAN
CH,O
/
I
c2H5mANANH-CH2-EN Malathion ~H2-i--oc2H5 0 CH3
Cyanazine
CIH,~
NH&H5
Alachlor
3 C2H50\b s 'AH50
CfJ, CH r---.+---c-c&
0
/
CHz--CHz-CH,
II
CHz-CH2-CH,-S-C-N
/
\
W
Terbufos
CH2-CH2-CH,
Vemolate
Fig. 3 Chemical
structures
for pesticides
selected
for
analysis
in this
project.
413
Marine Pollution Bulletin TABLE 1 Selected GC-MS parameters for identification of currently-used pesticides. Compound NC1 Trifluralin Chlorothalonil Chlorpyrifos Endosulphan I Endosulphan II Fenvalerate I Fenvalerate II EI
Butylate Vernolate Simazine Atrazine Terbufos Diazinon Malathion Alachlor Methyl parathion Metolachlor Cyanazine
Retention time (tin)
Major ion
Conf. ion No. I*
Tol. +%t
Cod ion No. 2*
Tol. k%t
Cod ion No. 37
Tol. *%t
17.75 22.12 30.60 36.33 41.51 49.55 49.82
335 266 313 237 231 211 211
336 264 315 239 410 213 213
16+20 SO+20 70+20 7Ok20 26520 40+20 40+20
305 230 214 406 406
20+20 SO+20 20+20 60+20 SO+20
242 242
50+20 70+20
7.75 7.98 12.21 12.35 12.78 12.96 15.62 14.59 14.55 15.74 15.94
146 128 201 200 231 179 127 160 109 162 225
156 161 186 215 153 304’ 173 188 263 238 212
100 f 20 15k20 6Ok20 54+20 19+20 40+20 63+20 96k20 38+20 38+20 80f40
217 203 173 173 173 139 125 231 125
30+20 15+20 47520 28+20 50+20 89+20 79f20 28+20 61+20
174
55+20
203 217 214
30+20 20+20 go+20
269
10+20
*Conf. ion = contlrmation ion. tTo1. = tolerance for acceptance of confirmation ion.
through a C-18 extraction column (10 g). The adsorbed pesticides were eluted from the C-18 column with 30 ml of isopropanol : cyclohexane (1: 1; modified from Foreman et al., 1993). These extracts were also fractionated as described earlier. Recovery of the 13 pesticides from water by this method averaged between 79% for methyl parathion and 94% for atrazine. Surface microlayer samples of 4-8 1 were collected using a stainless steel mesh screen (Garrett, 1965). To avoid contamination from the ship, these samples were collected from a small boat at least 500 m from the ship. The samples were preserved with mercuric chloride and extracted using methylene chloride (- 250 ml methylene chloride: 1000 ml sample). Method tests using this technique produced > 80% recoveries. Fog samples were collected on stations using dynamic fog collectors modified (inlet velocity reduced from 9 to between 4 and 7 m s-‘) f rom the basic design described by &homburg et al. (1991) and, during transit, using a passive collector. This passive collector was constructed from teflon threads wrapped over a metal frame. The teflon thread spacing was -3-5 mm between the wrappings on a frame 1.5 x 1.5 m in size. The fog impacted this collector due to the forward motion of the ship and the droplets were directed into the collection bottle using an aluminum foil trough. These aqueous samples were extracted using methylene chloride as discussed earlier. To avoid ship contamination, air and fog samples were collected from the bow and only while the ship was facing into the wind. Surface water samples were obtained from the forward and windward side of the ship, and microlayer samples were collected from a small boat which was always positioned upwind of the ship and at least 500 m away. The engine was always turned off during microlayer collections. Prior to their use the screens were cleaned and wrapped in aluminium foil during transport to the collection sites. 414
Blanks included distilled water rinses of empty sample containers for ice,.surface microlayer and fog samples. Blanks for air consisted of unused PUF plugs. These were processed and analysed as real field samples. No detectable amounts were found in any of these samples. For water, laboratory blanks were prepared and analysed which also showed no evidence of any of the compounds investigated. Standards were all obtained from US EPA Research Triangle Park, North Carolina repository or from certified suppliers. Minimum detection limits are listed in Table 2 and are based on determination of the typical electronic signal in standard field samples.
Results Water
Only a few currently-used pesticides were found in the pristine Bering and Chukchi sea ecosystem and the concentrations, as expected, were very low. Chlorpyrifos was identified in six of the nine water samples, and traces of endosulphan I were also frequently identified (Table 3). Maximum concentrations of chlorpyrifos in these water samples were found in northern and western parts of the areas investigated (W-7 and S), which correspond to those regions where ice melt occurs. Samples obtained at greater distances from the ice contained lower chlorpyrifos concentrations, reaching non-detectable levels in the central Bering Sea. Chlorothalonil was identified at only one sampling location (W-6) in the eastern part of the Chukchi Sea. Fenvalerate and endosulphan II were identified in a few samples, the highest concentrations (40 and 100 pg l-i, respectively) were measured in the Gulf of Anadyr (W-3). Local run-off could be one explanation for these values and we feel that they should be considered tentatively until more sampling and analytical investigation can be carried out. Furthermore, confirmation ions
Volume 3YNumbe.r S/May 1996 TABLE
2
Detection limits of currently-used pesticides in field samples.* Seawater (Pg 1-3
Melted ice (Pi? 1-3
Trifluralin Chlorothalonil Chlorpyrifos Endosulphan I Endosulphan II Fenvalerate I Fenvalerate II
0.5 0.3 0.8 2.0 12 8 11
2 1.5 3.5 9.0 52 36 50
10 7 16 40 230 160 220
100 100 200 500 3100 2200 3000
0.02 0.01 0.03 0.06 0.35 0.25 0.33
Butylate Vemolate Simazine Atrazine Terbufos Diazinon Malathion Alachlor Methyl parathion Metolachlor Cyanazine
4.0 3.0 10 9.0 4.0 6.0 12 7 6.0 2.0 25
18 14 45 40 17 25 53 30 26 9.0 114
80 60 200 180 80 115 240 135 120 40 520
1100 800 2700 2400 1000 1500 3200 1800 1600 600 6900
0.12 0.09 0.3 0.27 0.12 0.18 0.36 0.21 0.18 0.06 0.75
Compound
Surface microlayer (Pg 1-‘)t
Fog water (Pg 1-‘)t
Air (Pg mv3)t
NC1
EI
*Detection limits calculated using 3a x blank values (Glaser ef al., 1981). TDetection limits based on the following volumes which differed for each matrix, i.e. seawater 80 1;melt ice 18 1; microlayer 4 1; fogwater 0.3 1 and air 2700 m3.
were not present in proportions necessary to fully confirm their presence and reports of endosulphan II are rather rare, especially at remote locations and at such high concentrations. In addition, these high values were not accompanied with high concentrations of these compounds in adjacent compartments. Surface microlayer Of the 11 microlayer samples only two, Bristol Bay and the station near Cape Hope, contained measurable concentrations of the currently-used pesticides chlorothalonil and trifluralin. Relative to other matrices, these concentrations were rather high, i.e. in excess of 100 pg 1-i. Explanations for the relatively high concentrations at these locations could be that they were near-shore and where periods of fog were observed. Recent passage of fog over the water surface may have left behind certain chemicals contained in the fog; as is discussed in following sections, both chlorothalonil and trifluralin were observed in fog.
This investigation in the Bering and Chukchi Seas constitutes the first ever collection and analyses of marine arctic fog for pesticides. Fog water of varying amounts was collected in different areas of this polar and sub-polar region and found to be an efficient scrubber of currently-used pesticides (several orders of magnitude higher than surface water and ice) during the period of our investigations (Table 4). The compositions of currently-used pesticides in fog water and seawater are different. For several of these samples (stations I-4) only small volumes of fog were obtained, therefore, the analytical uncertainty is higher for these data than the Chukchi Sea fog samples (stations 5-7). The most abundant pesticides in fog were chlorothalonil and metolachlor, both of which were absent in seawater and ice. Of all the compartments which were sampled, metolachlor and terbufos were found only in fog water at maximum concentrations of 147 and 12 ng I-‘, respectively.
Arctic ice One integrated ice sample was collected from a 100 m2 iceflow which had recently separated from the ice edge. Total organic carbon concentration was high (230 mg 1-l) and a great amount of particulate matter was observed. Chlorpyrifos (170 pg 1-i) and atrazine (400 pg 1-i) were observed at levels above detection limits (Table 3). As finding these pesticides in this sample was unexpected, special care was taken to verify their presence. Both electron impact and negative chemical ion detection were used to confirm the spectra of these compounds. Fenvalerate and simazine were tentatively identified by retention time matches to their major mass spectral ions, however, confirmation ions were not present in proportions necessary to fully confirm their presence.
Air Endosulphan II was detected in several air samples at concentrations ranging from 0.7 to 1 pg m-‘, and atrazine at 1.1 pg m3 was found in only one sample which was collected near the Alaskan peninsula; in all cases the concentrations were near the detection limit of the method. No other pesticides from the analyte list were detected in these samples. As the total air collected was -3000 m3 (which was necessary to collect toxaphenes), some breakthrough of these currentlyused pesticides may have occurred. Recovery studies in our laboratory using this sampling system have verified breakthrough problems at air volumes in excess of 1000 m3. Endosulphan I was also suspected to be present in nearly every sample, however, interference from ion masses similar to those which are characteristic for 415
Marine
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Bulletin
endosulphan were present in the ion chromatograms (likely from a-chlordane). Independent analyses of these air samples using GC and MS (Bidleman, Atmospheric Environmental Service, Downsview, Ontario) confirmed the presence of endosulphan I.
Discussion Highest concentrations of currently-used pesticides in this ecosystem were observed in sea ice and fog. Longrange atmospheric transport has been shown to be an important process for transport of organic contaminants to Arctic regions (Pacyna, 1995). Deposition and incorporation of pesticides into the ice surface from atmospheric sources is a likely scenario. While not all the compounds observed in ice and surface water were found in the air collected, transport and deposition of these compounds may have occurred during peak use periods for temperate agricultural areas (late spring and early summer). Low temperatures and low intensity solar radiation may severely decrease hydrolysis and photolysis reaction rates and therefore increase environmental half lives. Fog (from temperate locations) has been shown by other researchers to accumulate pesticides to levels much higher than expected, however, only a few actual reports of pesticides in fog water have been published (Glotfelty et al., 1987, 1990; Schomburg et al., 1991; Seiber et al., 1993). These collections were all made at locations near agricultural areas. Several collections in California in the mid to late 1980s indicate that organophosphates are common in fog. Some representative concentrations for intense agricultural areas are as follows: diazinon, chlorpyrifos, parathion and malathion ranging from 0.3-76, 0.3-14, 5-91 and 0.14-8.7 ug l-‘, respectively, during major fog events in January (Glotfelty et al., 1987, 1990; Seiber et al., 1993) and in coastal fog in September (Schomburg et al., 1991). Similar but lower concentrations of pesticides were measured in fog collected away from intense agriculture (Schomburg et al., 1991). Herbicides were measured in fog in Beltsville, Maryland; atrazine, simazine, alachlor and metolachlor were found at concentrations ranging from 0.045 to 1.96 I-18 I-’ in the spring of 1987. Herbicides were also identified in fog in California (January sampling) with atrazine and simazine at concentrations ranging from 0.27 to 0.7 and 0.1 to 1.2 ug l-‘, respectively (Glotfelty et al., 1987). There are no reports of pesticides detected in fog collected from remote locations or in fog collected over oceanic water. There are several possibilities for enrichment of organic chemicals in fog. Fog has been shown to have extensive surface areas for scavenging gas and particle phase contaminants from the air (Hoff et al., 1993). Some researchers have also suggested that the particulate matter and/or unusually high dissolved organic carbon content in fogs may account for this enrichment (Glotfelty et al., 1987). One possible mechanism that may be functioning uniquely in arctic environments is that as warm air moves over ice surfaces, sublimation may occur creating fog or mist which acts as a trap for airborne pesticides. In addition, because of the 416
Volume
32/Number S/May 1996 TABLE 4 Concentrations (ng 1-i) of currently-used pesticides in fog condensates. F-l
Pesticide Chorpyrifos Chlorothalonil Endosulphan I Metolachlor Terbufos Trifluralin
F-2 GEOSECS Meteorol. Station
Bristol Bay 4.0 17 wt 51 <3.1
F-3
F-4
F-5
F-6
Southern Bering
Gulf of Anadyr
Diamede Islands
Wrangel Island
F-l Siberian Coast Chukchi
<0.9 8 <2.2 <2.7 <4.5
<2.0 11 < 5.0 <6.0
1 13 < 1.5 147 <3.0 <0.3
5 4 <1.5 < 1.8 < 3.0 <0.3
1 4 <0.5 2 12
<4.0* 17
(‘5)
(2)
*This value is based on the detection limit which is both compound and volume dependent. tparentheses indicate some uncertainty in these data as they were detected at less than twice the detection limits.
Concentrations (pg m-‘)
Atrazine Endosulphan II
TABLE 5 of currently-used pesticides in atmospheric samples.
A-l Alaska Peninsula
A-2 Central Bering
A-3 Gulf of Anadyr
A-4 Siberian Coastline Chukchi
A-5 Eastern Bering
1.1 co.27
<0.29* 1.0
<0.31 0.70
<0.30 (0.W
<0.21 (0.5)
*This value is based on the detection limit which is both compound and volume dependent. tparenthesis indicate some uncertainty to these data as they were detected at less than twice the detection limits.
hydrological and meteorological conditions in these ecosystems, long periods of ice cover and frequent fogs in summer periods, destruction of easily hydrolyzed pesticides is reduced. This could cause a build-up in these compartments causing continuous impacting of these ecosystems. During the long ice-cover period, pesticides reaching this region could accumulate at the ice surface either directly or as dry fall and snow accumulation. In this frozen condition the compounds would be stable in comparison with their behaviour in a dissolved state. The relatively high measured values for atrazine and chlorpyrifos in the ice sample support this theory. Both atrazine and chlorpyrifos have been observed to degrade in aqueous solution in normal temperate conditions. Aquatic hydrolysis is one process which may lead to this degradation. Hydrolysis half-lives in marine water are about 50 days for chlorpyrifos and 200 days for atrazine (Howard, 1991). Atrazine is also subject to photolytic and biological decomposition removal processes. During melt periods these accumulated pesticides are released into adjacent marine waters where biological spring is beginning. Therefore, there is a high potential for ecological damage from these compounds. Our observation of the distribution of these compounds in seawater appears to reflect their chemical properties. Chlorpyrifos decreased rapidly when moving away from the ice fields, suggesting rapid hydrolysis. Atrazine was not found in any of the water samples, indicating that it also dissipates rapidly by dilution and hydrolysis and perhaps also by other processes such as photolysis, biological decomposition and particle sorption and deposition. The occurrence of atrazine and chlorpyrifos in the Arctic ice can be postulated on the basis of both the high usage of these compounds and their unusual
physical chemical properties. Atrazine was the most highly used pesticide in the US at 29 x lo6 kg active ingredient (AI) yr -’ in 1989, and chlorpyrifos was one of the most heavily-used insecticide in the US at 5 x IO6 kg AI yr-’ (Gianessi, 1992). Accurate data for worldwide use of these pesticides are not readily available, but similar practices are likely and could therefore significantly add to these totals. The occurrence of these pesticides in the Arctic ice is most probably due to long-range atmospheric transport, however, some local sources are possible (Bleicher et al., 1980; USEPA, 1986). One could postulate that along with North America, north-eastern Russia, Japan and northern China could contribute these pesticides to this Arctic region, however, accurate production and use data are lacking at this time. The Henry’s law constant (HLC) for chlorpyrifos is relatively high, allowing it to be readily released into the gas phase after application to agricultural fields. Atrazine, while having a much lower HLC than chlorpyrifos, still appears to be released into the atmosphere since it has been detected in Great Lakes water samples (Schottler et al., 1994) as well as in atmospheric precipitation at several locations throughout the world (Glotfelty et al., 1990 (eastern US); Kreuger & Staffas, 1994 (Sweden); Siebers et al., 1994 (northern Germany). Furthermore, recent findings have reported gaseous concentrations of both atrazine and chlorpyrifos in air samples from the Chesapeake Bay area (McConnell et al., 1994). It is important to note that the build-up of these chemicals in cold remote regions like the Bering and Chukchi Seas ecosystems are probably related to air/water gas exchange processes. Henry’s law constant is a numerical measure of volatile release and gas phase deposition of pesticides. A major variable controlling this constant 417
Marine Pollution Bulletin
is temperature. Data to better describe the temperature dependence of HLCs for currently-used pesticides are presently being developed (Rice et al., 1994). Endosulphan was present in many water samples at trace levels and was also detected in fog and air. Endosulphan is used at rather low levels in the US (5 x 10’ kg AI yr-‘; Gianessi, 1992) however, there is evidence of its extensive usage throughout the world, particularly in cotton-growing countries (Gopal & Mukherjee, 1993; Peterson & Batley, 1993). During the last 10 years it was the most common replacement for many of the now banned and more persistent chlorinated pesticides and, therefore, it is not surprising that it was measured at low levels in many of the sample extracts. Arctic researchers have reported its presence in snowpack (0.24-2 ng mw3; Barrie et al., 1992) and air (3.7-4.1 pg rnw3; Bidleman et al., 1995). The concentrations reported here appear to reflect more of a background level rather than suggesting any local contamination sources. Chlorothalonil, a major fungicide (1.8 x lo6 kg AI -I; Gianessi, 1992) was detected in surface microv layer and water at one station near the Alaskan coast, East Chukchi, and in surface microlayer in Bristol Bay (no sub-surface water collected). The fungicide was also found in every fog sample collected. The water solubility of chlorothalonil is high (0.6 mg 1-i) which favours retention in fog. The presence of chlorothalonil in the eastern Chukchi Sea microlayer (200 pg 1-l; subsurface 18 pg 1-i) may have resulted from fog to microlayer exchange during a previous fog episode in this area. This argument also suggests that the fog sampled in the western Chukchi Sea may have previously come from the eastern part of the sea. Trifluralin was also found in many samples collected from the Bering and Chukchi Seas. It is a commonly used herbicide (12.3 x lo6 kg AI yr-‘; Gianessi, 1992) and therefore its occurrence in this region should not be unexpected. Trifluralin is relatively volatile (HLC= 11.5) but it is also very photodegradable and not likely to persist for long periods of time in water. Other researchers have reported the presence of trifluralin in northern air and other Arctic samples (Hoff et al., 1992; Barrie, 1994). The high levels of the herbicide metolachlor (22.5 x lo6 kg AI yr-‘; Gianessi, 1992) measured in fog samples were unexpected. It is believed that these occurred from possible local contamination sources, particularly as metolachlor was not found in any of the other sampled compartments. The solubility of metolachlor is very high (530 mg 1-l) and thus should favour dissolution in fog. Terbufos, a common insecticide (4.6 x lo6 kg AI yr-‘; Gianessi, 1992) was found in one sample of fog. Like metolachlor it has a high water solubility (15 mg l-i), however, the source for both of these pesticides in this remote region needs to be investigated further. Historical data for Alaska show that pesticides such as chlorpyrifos, chlorothalonil, atrazine and diazinon were used in the state both in agriculture and for military purposes (Bleicher et al., 1980; US EPA, 1986) however, the quantities used appear to be very small. 418
There were few pesticides measured in air. Endosulphan was found in four of the five samples which suggests it may be a component of global background air. Atrazine was found in one sample which was collected along the Alaskan Peninsula. Its occurrence here could be explained by the local use of atrazine for agriculture in this region, since samples were taken during the active planting season for this area. At some of the locations the measured compounds could be considered to have possible detrimental impacts on the biota. Johnson & Finley (1980) list toxicities of several pesticides to aquatic organisms, specifically chlorpyrifos (Gummurus lucustris, 0.07-0.17 PLg1-l 96-h LC&) and trifluralin (Rainbow trout, 2662 IQ 1-l 96-h L&a). These concentrations approach the highest values measured in this study. Unique to this region are extreme cold conditions over much of the year which could be responsible for the high accumulations that were observed, especially in Arctic ice. Global fractionation and cold condensation of low volatility compounds in colder climatic zones have been described by Wania & Mackay (1993) and these processes could account for unexpected build-up of these chemicals in the Chukchi and Bering ecosystems. Another feature which is unique to this Arctic region is the dramatic seasonal cycle for atmospheric particulate matter. Long-term data confirm that aerosol concentrations are significantly lower during summer (July-September) and reach maximum levels in January and February, with a dramatic drop at the beginning of summer (Barrie et al., 1992). In the northern hemisphere, major releases of currently-used pesticides occur during the months of April-June and, therefore, the high early-spring particulate phases typical in the Arctic might act as important condensation surfaces for pesticides as they are transported northward through the air (Wania & Mackay, 1993). Presently, there are no data on currently-used pesticides to verify these hypotheses. The current study was an attempt to provide this information.
Conclusion This is the first published investigation describing currently-used pesticides in Bering and Chukchi marine ecosystems. Now there is clear evidence that the following currently-used agrochemicals are present in many of the compartments sampled: chlorpyrifos, atrazine, endosulphan, trifluralin and chlorothalonil. Many unusual features of this environment, i.e. extreme cold, high winter atmospheric particulate episodes and high summer-season biological productivities, lead to unusual transport and cycling of these compounds relative to more temperate regions. There is a possibility that these chemicals may be causing ecological damage in these vulnerable regions. It is realized that this preliminary investigation needs to be further developed, including many more measurements over the entire spring-summer period when these pesticides are applied in the northern hemisphere. Also, the list of monitored pesticides should be changed, for example, it would be important to consider pesticides
Volume 32/Number S/May 1996
which are not only used in North America but also in neighbouring countries, such as Japan, far-eastern Russia and northern China. Atmospheric back-trajectory analyses from the Bering and Chukchi regions could also be utilized to better clarify the sources of these pesticides. The authors especially wish to thank Peter McRoy for encouraging our interest in measuring currently-used pesticides in marine arctic fog. They also acknowledge the assistance of William Strachan in the collection and sharing of his large volume water samples, Terry F. Bidleman and Liisa Jantunen for the collection and sharing their high volume air samples, and thank Lisa Ross for the use of her fog collectors. They would especially like to thank the US Fish and Wildlife Service and The Institute of the Global Climate and Ecology (Russian Hydromet Federal Service) for organizing and sponsoring this BERPAC expedition, and Captain Anatoly L. Akimov for organizing the work on board the RV Okean. They also thank Derek Muir for his excellent reviews during the preparation of this manuscript, and the journal reviewers for their care and attention to detail. Anthony, D. H. J. (1993). Application of the Goulden large sample extraction technique in sampling ‘ditiicult’ environmental aqueous matrices. American Chemical Society-Division of Environmental Chemistry, Meeting,
Preprints Denver,
of Papers
Presented
at the 205th
ACS National
CO, Vol. 33, pp. 408411. American Chemical Society, Washington, DC. Barrie, L. A. (1994). Northern contaminants air monitoring. Synopsis of Research Conducted under the 1993194 Northern Contaminants Program (Environmental Studies No. 72; J. L. Murray & R.
G. Shearer, eds), pp. 20-27. Minister of Indian Affairs and Northern Development, Ottawa, Canada. Barrie, L. A., Gregor, D., Hargrave, B., Lake, R., Muir, D., Shearer, R., Tracey, B. & Bidleman, T. (1992). Arctic contaminants: sources, occurrence and pathways. Sci. Tot. Environ. 122, 1’74. Bidleman, T. F., Falconer, R. L. & Walla, M. D. (1995). Toxaphene and other organochlorine compounds in air and water at Resolute Bay, N.W.T., Canada. Sci. Tot. Environ. 160/161, 55-63. Billinas. - , W. N. & Bidleman. T. F. (1983). Hieh volume collection of chlorinated hydrocarbons’in urban air using three solid adsorbents. Atmos.
Environ.
17, 383-391.
Bleicher, D. P., Scorup, P. C. & Mitchell, W. W. (1980). Pesticide Use in Alaska, 1978. Agricultural Experiment Station, Fairbanks, Alaska, 40 pp. Foreman, W. T., Foster, G. D. & Gates, P. M. (1993). Isolation of multiple classes of pesticides from water samples using commercial lo-gram C-18 solid phase extraction cartridges. American Chemical Society-Division of Environmental Chemistry, Presented at the 205th ACS National Meeting,
Preprints of Papers Denver, CO, Vol. 33,
pp. 436439. American Chemical Society, Washington, DC. Foreman, W. T., Gates, P. M. & Foster, G. D. (1993). Performance of the Goulden large sample extractor for preconcentration of pesticides in surface-water samples in the Yakima River basin, Washington. American Chemical Society-Division of Environmental Chemistry, Meeting,
Preprints of Papers Denver, CO, Vol.
Presented
at the 205th
33, pp. 415417.
ACS
National
American Chemical
Society, Washington, DC. Foster, G. D., Foreman, W. T. & Gates, P. M. (1991). Performance of the Goulden large-sample extractor in multiclass pesticide isolation and preconcentration from stream water. J. Agric. Food Chem. 39, 1618-1622. Garrett, W. G. (1965). Collection of slick-forming material from the sea surface. Limnol. Oceanogr. 10, 602605. Gianessi, L. P. (1992). US Pesticide Use Trends 1966-1989, Resources for the Future. Washington DC. Glaser, J. A., Foerst, D. L., McKee, G. D., Quave, S. A. Jr Budde, W. L. (1981). Trace analyses for wastewater. Environ. Sci. Technol. 15, 14261435. Glotfelty, D. E., Seiber, J. N. & Liljedahl, L. A. (1986). Pesticides and other- organics in fog. Pro; 1986 EP&AP?A Symp. on Measurement of Toxic Air Pollutants, pp. 168-175. US EPA/Air Pollution Control Association. Glotfelty, D. E., Seib-er, J. N. & Liljedahl, L. A. (1987). Pesticides in fog. Nature 325, 602-605. Glotfelty, D. E., Majewski, M. S. & Seiber, J. N. (1990). Distribution of several organophosphorous insecticides and their oxygen
analogues in a foggy atmosphere. Environ. Sci. Technol. 24, 353357. Gopal, M. & Mukhejee, I. (1993). Determination of residues of endosulfan and endosulfan sulfate on eggplant, mustard and chickpea.
Pestic.
Sci. 37, 67-72.
Hoff, J. T., Mackay, D., Gillham, R. & Shiu, W. Y. (1993). Partitioning of organic chemicals at the air-water interface in enviromnental systems. Environ. Sci. Tebhnol. 27, 2174-2180. Hoff, R. M., Muir, D. C. G. & Grit& N. P. (1992). Annual cycle of polychlorinated biphenyls and organohalogen pesticides in air in Southern Ontario. 1. Air concentration data. Environ. Sci. Technol. 26, 266275. Howard, P. H. (ed.) (1991). Handbook of Environmental Fate and Exposure Data for Organic Chemicals, Vol. III, p. 684. Lewis Publishers Inc., Chelsea, MI. Johnson, W. W. & Finley, M. T. (1980). Handbook of Acute Toxicity of Chemicals to Fish and Aquatic Invertebrates. US Department of the Interior, Fish and Wildlife Service, Resource Publication 137, Washington, DC. Kreuger, J. & Stalfas, A. (1994). Pesticides in Swedish precipitation. Eighth IUPAC of Abstracts,
International
fluxes. istry,
IUPAC
Congress
of Pesticide
Chemistry,
Book
Vol. 2, p. 612. American Chemical Society, Washington, DC. McConnell, L. L., Rice, C. P., Johnson, W. E., Chernyak, S. M. & Harman, J. A. (1994). Concentrations of current-use pesticides in the air and water of Chesapeake Bay: estimates of deposition Eighth
International
Vol. II, p. 617. American
Congress
of Pesticide
Chem-
Chemical Society, Washington,
DC. McConell, L. L., Nelson, E., Rice, C. P., Harman, J. 14., Baker, J. E., Johnson, W. E. & Chemyak, S. M. (1995). Pesticides in Chesapeake Bay; Atmosphere and Surface Waters. Clean Wuter-Clean Environment 2lst Century, Vol. 1, pp. 129-132. Working Group on Water Quality, US Department of Agriculture, St. Joseph, MI. Nagel, P. (ed.). (1992). Results of the third joint US-USSR Bering & Chukchi Seas Expedition (BERPACj-Smnmer 1988. United States Department of the Interior/Fish and Wildlife Service, Washington, D.C. Pacyna, J. M. (1995). The origin of Arctic air pollutants: lessons learned and future research. fci. Tot. Environ. &O/161, 39-53. Peterson, S. M. t Batlev. G. E. (1993). The fate of endosulfan in aquatic ecosystems. E&on. PO&t. Si, 143-152. Rice, C. P., Chemyak, S. M. & McConnell, L. L. (1994). Measurement of pesticide Henry’s law constants in field samples. Eighth IUPAC International Congress of Pesticide Chemistry, Vol. II, p. 621. American Chemical Society, Washington, DC. Schomburg, C. J., Glotfelty, D. E. & Seiber, J. N. (1991). Pesticide occurrence and distribution in fog collected near Monetery, California. Environ. Sci. Technol25, 155-160. Schottler, S. P., Eisenreich, S. J. & Capel, P. D. (1994). Atrazine, ala&or, and cyanazine in a large agricultural river system. Envir. Sci. Technol. 28, 1079-1089. Seiber, J. N., Glotfelty, D. T., Lucas, A. D., McChesney, M. M., Sagebiel, J. C. & Wehner, T. A. (1990). A multiresidue method by high performance liquid chromatography-based fractionation and gas chromatographic determination of trace levels of pesticides in air and water. Arch. Environ. Contam. Toxicol. 19, 583-592. Seiber, J. N., Wilson, B. W. & McChesney, M. M. (1993). Air and fog deposition residues of four organophosphate insecticides used on dormant orchards in the San Joaquin Valley, California. Environ. Sci. Technol.
27, 2236-2243.
Siebers, J., Got&child, D. & Nolting, H. G. (1994). Pesticides in precipitation in Northern Germany. Eiphth IUPAC International ?on&ess of Pesticide Chemistry, Bdok 07 Abstracts, Vol. 2, p. 618. American Chemical Society, Washington, DC. Thomas, R. L. & Frank, R. (1983). PCBs in sediment and fluvial suspended solids in the Great Lakes. In Physical Behavior of PCBs in the Great L.&es (S. Mackay, S. Patterson, M. 6. Eisenreich, eds.) pp. 245-267. Ann Arbor Science, Ann Arbor, Michigan. USDA (1991) Aaricultural Chemical Usaae. 1990 Field Croo Summary. &ri&tural Statistics Service, Washington, DC. 1 US EPA (1986). Alaska Pesticides Profile, EPA 910/9-86-139, p. 57. Environmental Protection Agency, Operations Office, Anchorage, AK. Wania, F. & Mackay, D. (1993). Global fractionation and cold condensation of low volatility organochlorine compounds in polar regions. Ambio, 22, l&18. Welch, H. E., Muir, D. C. G., Billeck, B. N., Lockhart, L. W., Brunskill, G. J., Kling, H. J., Olson, M. P. & Lemoine, R. M. (1991). Brown Snow: a long-range transport event in the Canadian Arctic. Environ. Sci. Technol. 25, 280-286.
419
Marine PoNulion Bulletin, Vol. 32, No. 5, pp. 4W419, 1996 Published by Elsevier Science Ltd Printed in Great Britain. All rights reserved 0025-326X/96 S15.00 +O.OO
Evidence of Currently-Used Pesticides in Air, Ice, Fog, Seawater and Surface Microlayer in the Bering and Chukchi Seas SERGEY M. CHERNYAK, CLIFFORD P. RICE and LAURA L. MCCONNELL US Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705, USA
Investigation of currently-used pesticides (triazines, acetanilides, organophosphates and organochlorines) was carried out in the Bering and Chukchi marine ecosystems in the summer of 1993. Chlorpyrifos and trace levels of endosulphan were the most frequently identified contaminants in seawater, chlorpyrifos and atrazine were found in marine ice, and chlorothalonil and trifluralin were found in surface microlayer samples. Concentrations of chlorpyrifos were highest (170 ng 1-l) in marine ice and higher in seawater (19-67 ng 1-l) at locations which were closest to the ice edge. Endosulphan was found as a widely distributed currently used pesticide in the polar atmosphere. The greatest concentration of any one single agrochemical was trifluralin (1.15 pg 1-i) in a Bristol Bay surface microlayer sample. Arctic marine fog was sampled and for the tirst time, several currently-used pesticides (chlorpyrifos, tritluralin, metolachlor, chlorothalonil, terbufos and endosulphan) were detected at concentrations several times higher than in adjacent waters or ice. Published by Elsevier Science Ltd
Certain classes of pesticides (triazines, acetanilides, organophosphates) are heavily used in agriculture in northern countries. Their use has been increasing steadily since the late 1970s (USDA, 1991). These compounds were designed to be less stable than organochlorine pesticides. Theoretically they should not accumulate in the environment and should have only minor effects on local ecosystems. However, special features of Arctic environments, e.g. low temperatures and low solar radiation, slow down the normal dissipative and destructive processes which protect less vulnerable areas. It is therefore important to carry out investigations of the distribution and behaviour of currently-used pesticides in remote Arctic areas. There is already considerable evidence of worldwide distribution of several persistent chlorinated organic compounds. Explanations for their occurrence even in remote and pristine environments have now advanced to the level of accepted theory, (e.g. Wania & Mackay, 1993). Replacement chemicals have reduced persistence 410
and lower environmental mobility than chlorinated pesticides. With these changes, the assumption has been that Man does not have to be as vigilant in monitoring long range dispersal of the new class of chemicals. The sampling phase of this study was carried out as part of the Russian/American co-operation in environmental studies, the BERPAC project, a detailed investigation of ecological conditions of the Bering and Chukchi Seas and adjacent Pacific ocean (Nagel, 1992). An important goal of this long-term project (more than 15 years) is to monitor the health of the World’s oceans. Searching for new pollutants is a key component of the mission. The BERPAC programme is a part of the Joint Bilateral Activity Project between the US and Russia which was started in 1976, Comprehensive Analysis of Marine Ecosystems and Ecological Problems of the World Ocean. The specific objective of this study was to extend our search for currently-used pesticides in intensive agricultural areas, e.g. the Chesapeake Bay area, to the more remote Bering and Chukchi Arctic ecosystems. Protocols which were already in place for our Chesapeake Bay study (McConnell et al., 1995) were applied in this programme. Furthermore, since fog and ice frequently occur in this area, specific sampling was carried out in order to collect and analyse for currentlyused pesticides in these matrices.
Methods The fourth joint BERPAC expedition consisted of 63 oceanographic stations composed of transects and six polygons. The expedition took place from 1 August to 18 September 1993. A subset of samples were collected for analyses of currently-used pesticides in the following strata: seawater (two replicates) at nine stations (designated W-l to 9 in Figs 1 and 2); air while underway (A-l to 5), marine fog while underway (F-l to 7), microlayer at 11 stations (SML-1 to 1 l), and ice along the permanent ice edge. For water and air sample collection it was our objective to achieve the best geographic coverage as possible, however, collection of
Volume 32/Number 5/May 1996
SIN
168E
172 E
176E
180
176W
172W
168W
164W
Fig. 1 Sampling sites in the Bering Sea during joint Russian/American BERPAC expedition. Sample types are represented as follows: W = water sampling locations; F = fog sampling locations; A = air sampling locations; and SML = surface microlayer sampling sites.
ice, microlayer and fog samples were only possible when meteorological conditions allowed. Specific analyses were carried out for the following pesticides: trifluralin, chlorothalonil, chlorpyrifos, endosulphan, fenvalerate, terbufos, diazinon, malathion, methyl parathion, butylate, vernolate, simazine, atrazine, alachlor, metolachlor and cyanazine (Fig. 3). Sub-surface water samples from 0.5 to 1 m depth and 76-l 18 1 in volume were collected using a submersible pump. Suspended solids were removed using a Westphalia continuous-flow centrifuge (Thomas & Frank, 1983) and the water was extracted using methylene chloride in a Goulden continuous liquidliquid extractor (Foster et al., 1991). Based on extensive recovery experiments with these pesticides (Anthony, 1993; Foreman et al., 1993), we were confident that the recoveries should exceed 75%. Laboratory recoveries were greater than 90% for all compounds. Octachloronaphthalene and 1,3,5-tribromo benzene were added to samples as surrogate spikes prior to extraction. Each sample extract contained approximately 300 ml of methylene chloride. In the laboratory, extracts were flash evaporated to reduce their volumes further to approximately 10 ml, and then concentrated under a stream of nitrogen to 1.0 ml. Next, sample extracts were fractionated by normal phase HPLC (Seiber et al., 1990) using Partisil-10 (Beckman@ HPLC column) and a gradient of 100% hexane to 100% methyl tributyl ether.
The fractionated extracts were evaporated to 1 ml under a stream of dry nitrogen, 1 ml of isooctane was added and the extracts were concentrated to a final volume of 0.2 ml. All analyses were conducted using a Hewlett Packard Model 5989A GC/MS in selected ion-monitoring mode. The chlorinated compounds, trifluralin, chlorpyrifos, chlorothalonil, endosulphan I and II, and fenvalerate I and II, were determined using electron capture negative chemical ionization (NCI) detection methods. Gas chromatographic conditions were as fo’llows: column J&W DB-5, 30 m x 0.25 mm i.d. x 0.25 pm thickness; column flow 1.2 ml min-’ helium; injector 250°C; interface 280°C; temperature programme 90°C for 1 min, programmed to 120°C at 20°C min-‘, then 2°C min-’ to 2OO”C, followed by 20°C min- ’ to 280°C with a 10 min hold. The source was operated at 2.0 Torr methane and lOO-150°C. The other currently-used pesticides, vernolate, butylate, atrazine, simazine, methyl parathion, malathion, diazinon, terbufos, alachlor and metolachlor were analysed using the electron impact ionization mode (EI). Gas chromatographic conditions were as follows: injector 250°C; interface 280°C; programme started at 9@-150°C at 15°C min-‘, then to 250°C at 6°C min-‘, then to 280°C at 22°C min-‘. The source temperature was 225°C. All injections were made in splitless mode with a 1 min hold before opening the purge valve. 411
Marine
-
Pollution
Bulletin
74N
SML-9
I
Wrangel
Island - 72N
W-6
A-4 start ISML-IO
&a SML-8
\
-
‘64N
I 16OW
I 175w
I
170w
I
165W
Fig. 2 Sampling sites in the Chukchi Sea during joint Russian/ American BERPAC expedition. Sample types are represented as follows: W = water sampling locations; F=fog sampling locations; A = air sampling locations; and SML = surface microlayer sampling sites.
Initial determinations were carried out using selected ion monitoring and quality matching routines which included two or more additional ions (Table 1). Structural verification was carried out by selecting additional ions and confirming their spectra by requiring proper ratios of at least four ions for each analyte. Full scan spectra were generated for final confirmations. Water samples were duplicated on two occasions; variations were < 10% for all analytes. Recovery tests for water sample surrogates averaged 50.8 +7.8% for tribromobenzene and 56.7 + 5.8% for octachloronaphthalene excluding one outlier of > 120% recovery. While these recoveries are somewhat low, they are within the range of values observed by others using these surrogates with the Goulden method (W. Strachan, pers. comm.); results were not corrected to adjust for these recoveries. Air samples were collected by passing 27OCL-4400 m3 of air through a glass fibre filter followed by two 412
polyurethane foam plugs. These were extracted and prepared using Soxhlet procedures with petroleum ether for 12-15 h (Billings & Bidleman, 1983). Recoveries of >65% for all of the reported analytes were established using spike recovery tests carried out in our Chesapeake Bay study. One-third of the extract volumes were concentrated and fractionated as described earlier. During the transit from Wrangel Island to Bering Strait a dichotomous air sampler (Glotfelty et al., 1986) was also operated while fog water was being collected. These data allowed gaseous phase levels of pesticides to be determined for calculation of air to fog partitioning. Approximately equal portions of ice (about 0.5 m3) were removed from five locations around the perimeter and one centrally located on the ice flow (Fig. 2). The ice chunks were allowed to melt at room temperature in a loosely closed water cooler. The melted ice (17.1 1) was stored in cleaned and baked 4 1 amber solvent bottles with mercuric chloride added as a preservative. It was then filtered through a glass fibre filter and passed
Volume
32/Number
S/May
1996
H3 CH 2 CHNRNANHCH(CH& Atrazine Butylate
Trifluralin Chlorothalonil
c,AN~o-~oc2H5\ c”‘\ /fT\ II OWS
0-P
CHfH
0 I
O'Wj
I,:
S
Chlorpyrifos
OC2HS H
s
N
f
Diazinon
ii
Endosulphan
I & II
Cl
cH30\~+cH,~~-oc,H
NAN
CH,O
/
I
c2H5mANANH-CH2-EN Malathion ~H2-i--oc2H5 0 CH3
Cyanazine
CIH,~
NH&H5
Alachlor
3 C2H50\b s 'AH50
CfJ, CH r---.+---c-c&
0
/
CHz--CHz-CH,
II
CHz-CH2-CH,-S-C-N
/
\
W
Terbufos
CH2-CH2-CH,
Vemolate
Fig. 3 Chemical
structures
for pesticides
selected
for
analysis
in this
project.
413
Marine Pollution Bulletin TABLE 1 Selected GC-MS parameters for identification of currently-used pesticides. Compound NC1 Trifluralin Chlorothalonil Chlorpyrifos Endosulphan I Endosulphan II Fenvalerate I Fenvalerate II EI
Butylate Vernolate Simazine Atrazine Terbufos Diazinon Malathion Alachlor Methyl parathion Metolachlor Cyanazine
Retention time (tin)
Major ion
Conf. ion No. I*
Tol. +%t
Cod ion No. 2*
Tol. k%t
Cod ion No. 37
Tol. *%t
17.75 22.12 30.60 36.33 41.51 49.55 49.82
335 266 313 237 231 211 211
336 264 315 239 410 213 213
16+20 SO+20 70+20 7Ok20 26520 40+20 40+20
305 230 214 406 406
20+20 SO+20 20+20 60+20 SO+20
242 242
50+20 70+20
7.75 7.98 12.21 12.35 12.78 12.96 15.62 14.59 14.55 15.74 15.94
146 128 201 200 231 179 127 160 109 162 225
156 161 186 215 153 304’ 173 188 263 238 212
100 f 20 15k20 6Ok20 54+20 19+20 40+20 63+20 96k20 38+20 38+20 80f40
217 203 173 173 173 139 125 231 125
30+20 15+20 47520 28+20 50+20 89+20 79f20 28+20 61+20
174
55+20
203 217 214
30+20 20+20 go+20
269
10+20
*Conf. ion = contlrmation ion. tTo1. = tolerance for acceptance of confirmation ion.
through a C-18 extraction column (10 g). The adsorbed pesticides were eluted from the C-18 column with 30 ml of isopropanol : cyclohexane (1: 1; modified from Foreman et al., 1993). These extracts were also fractionated as described earlier. Recovery of the 13 pesticides from water by this method averaged between 79% for methyl parathion and 94% for atrazine. Surface microlayer samples of 4-8 1 were collected using a stainless steel mesh screen (Garrett, 1965). To avoid contamination from the ship, these samples were collected from a small boat at least 500 m from the ship. The samples were preserved with mercuric chloride and extracted using methylene chloride (- 250 ml methylene chloride: 1000 ml sample). Method tests using this technique produced > 80% recoveries. Fog samples were collected on stations using dynamic fog collectors modified (inlet velocity reduced from 9 to between 4 and 7 m s-‘) f rom the basic design described by &homburg et al. (1991) and, during transit, using a passive collector. This passive collector was constructed from teflon threads wrapped over a metal frame. The teflon thread spacing was -3-5 mm between the wrappings on a frame 1.5 x 1.5 m in size. The fog impacted this collector due to the forward motion of the ship and the droplets were directed into the collection bottle using an aluminum foil trough. These aqueous samples were extracted using methylene chloride as discussed earlier. To avoid ship contamination, air and fog samples were collected from the bow and only while the ship was facing into the wind. Surface water samples were obtained from the forward and windward side of the ship, and microlayer samples were collected from a small boat which was always positioned upwind of the ship and at least 500 m away. The engine was always turned off during microlayer collections. Prior to their use the screens were cleaned and wrapped in aluminium foil during transport to the collection sites. 414
Blanks included distilled water rinses of empty sample containers for ice,.surface microlayer and fog samples. Blanks for air consisted of unused PUF plugs. These were processed and analysed as real field samples. No detectable amounts were found in any of these samples. For water, laboratory blanks were prepared and analysed which also showed no evidence of any of the compounds investigated. Standards were all obtained from US EPA Research Triangle Park, North Carolina repository or from certified suppliers. Minimum detection limits are listed in Table 2 and are based on determination of the typical electronic signal in standard field samples.
Results Water
Only a few currently-used pesticides were found in the pristine Bering and Chukchi sea ecosystem and the concentrations, as expected, were very low. Chlorpyrifos was identified in six of the nine water samples, and traces of endosulphan I were also frequently identified (Table 3). Maximum concentrations of chlorpyrifos in these water samples were found in northern and western parts of the areas investigated (W-7 and S), which correspond to those regions where ice melt occurs. Samples obtained at greater distances from the ice contained lower chlorpyrifos concentrations, reaching non-detectable levels in the central Bering Sea. Chlorothalonil was identified at only one sampling location (W-6) in the eastern part of the Chukchi Sea. Fenvalerate and endosulphan II were identified in a few samples, the highest concentrations (40 and 100 pg l-i, respectively) were measured in the Gulf of Anadyr (W-3). Local run-off could be one explanation for these values and we feel that they should be considered tentatively until more sampling and analytical investigation can be carried out. Furthermore, confirmation ions
Volume 3YNumbe.r S/May 1996 TABLE
2
Detection limits of currently-used pesticides in field samples.* Seawater (Pg 1-3
Melted ice (Pi? 1-3
Trifluralin Chlorothalonil Chlorpyrifos Endosulphan I Endosulphan II Fenvalerate I Fenvalerate II
0.5 0.3 0.8 2.0 12 8 11
2 1.5 3.5 9.0 52 36 50
10 7 16 40 230 160 220
100 100 200 500 3100 2200 3000
0.02 0.01 0.03 0.06 0.35 0.25 0.33
Butylate Vemolate Simazine Atrazine Terbufos Diazinon Malathion Alachlor Methyl parathion Metolachlor Cyanazine
4.0 3.0 10 9.0 4.0 6.0 12 7 6.0 2.0 25
18 14 45 40 17 25 53 30 26 9.0 114
80 60 200 180 80 115 240 135 120 40 520
1100 800 2700 2400 1000 1500 3200 1800 1600 600 6900
0.12 0.09 0.3 0.27 0.12 0.18 0.36 0.21 0.18 0.06 0.75
Compound
Surface microlayer (Pg 1-‘)t
Fog water (Pg 1-‘)t
Air (Pg mv3)t
NC1
EI
*Detection limits calculated using 3a x blank values (Glaser ef al., 1981). TDetection limits based on the following volumes which differed for each matrix, i.e. seawater 80 1;melt ice 18 1; microlayer 4 1; fogwater 0.3 1 and air 2700 m3.
were not present in proportions necessary to fully confirm their presence and reports of endosulphan II are rather rare, especially at remote locations and at such high concentrations. In addition, these high values were not accompanied with high concentrations of these compounds in adjacent compartments. Surface microlayer Of the 11 microlayer samples only two, Bristol Bay and the station near Cape Hope, contained measurable concentrations of the currently-used pesticides chlorothalonil and trifluralin. Relative to other matrices, these concentrations were rather high, i.e. in excess of 100 pg 1-i. Explanations for the relatively high concentrations at these locations could be that they were near-shore and where periods of fog were observed. Recent passage of fog over the water surface may have left behind certain chemicals contained in the fog; as is discussed in following sections, both chlorothalonil and trifluralin were observed in fog.
This investigation in the Bering and Chukchi Seas constitutes the first ever collection and analyses of marine arctic fog for pesticides. Fog water of varying amounts was collected in different areas of this polar and sub-polar region and found to be an efficient scrubber of currently-used pesticides (several orders of magnitude higher than surface water and ice) during the period of our investigations (Table 4). The compositions of currently-used pesticides in fog water and seawater are different. For several of these samples (stations I-4) only small volumes of fog were obtained, therefore, the analytical uncertainty is higher for these data than the Chukchi Sea fog samples (stations 5-7). The most abundant pesticides in fog were chlorothalonil and metolachlor, both of which were absent in seawater and ice. Of all the compartments which were sampled, metolachlor and terbufos were found only in fog water at maximum concentrations of 147 and 12 ng I-‘, respectively.
Arctic ice One integrated ice sample was collected from a 100 m2 iceflow which had recently separated from the ice edge. Total organic carbon concentration was high (230 mg 1-l) and a great amount of particulate matter was observed. Chlorpyrifos (170 pg 1-i) and atrazine (400 pg 1-i) were observed at levels above detection limits (Table 3). As finding these pesticides in this sample was unexpected, special care was taken to verify their presence. Both electron impact and negative chemical ion detection were used to confirm the spectra of these compounds. Fenvalerate and simazine were tentatively identified by retention time matches to their major mass spectral ions, however, confirmation ions were not present in proportions necessary to fully confirm their presence.
Air Endosulphan II was detected in several air samples at concentrations ranging from 0.7 to 1 pg m-‘, and atrazine at 1.1 pg m3 was found in only one sample which was collected near the Alaskan peninsula; in all cases the concentrations were near the detection limit of the method. No other pesticides from the analyte list were detected in these samples. As the total air collected was -3000 m3 (which was necessary to collect toxaphenes), some breakthrough of these currentlyused pesticides may have occurred. Recovery studies in our laboratory using this sampling system have verified breakthrough problems at air volumes in excess of 1000 m3. Endosulphan I was also suspected to be present in nearly every sample, however, interference from ion masses similar to those which are characteristic for 415
Marine
Pollution
Bulletin
endosulphan were present in the ion chromatograms (likely from a-chlordane). Independent analyses of these air samples using GC and MS (Bidleman, Atmospheric Environmental Service, Downsview, Ontario) confirmed the presence of endosulphan I.
Discussion Highest concentrations of currently-used pesticides in this ecosystem were observed in sea ice and fog. Longrange atmospheric transport has been shown to be an important process for transport of organic contaminants to Arctic regions (Pacyna, 1995). Deposition and incorporation of pesticides into the ice surface from atmospheric sources is a likely scenario. While not all the compounds observed in ice and surface water were found in the air collected, transport and deposition of these compounds may have occurred during peak use periods for temperate agricultural areas (late spring and early summer). Low temperatures and low intensity solar radiation may severely decrease hydrolysis and photolysis reaction rates and therefore increase environmental half lives. Fog (from temperate locations) has been shown by other researchers to accumulate pesticides to levels much higher than expected, however, only a few actual reports of pesticides in fog water have been published (Glotfelty et al., 1987, 1990; Schomburg et al., 1991; Seiber et al., 1993). These collections were all made at locations near agricultural areas. Several collections in California in the mid to late 1980s indicate that organophosphates are common in fog. Some representative concentrations for intense agricultural areas are as follows: diazinon, chlorpyrifos, parathion and malathion ranging from 0.3-76, 0.3-14, 5-91 and 0.14-8.7 ug l-‘, respectively, during major fog events in January (Glotfelty et al., 1987, 1990; Seiber et al., 1993) and in coastal fog in September (Schomburg et al., 1991). Similar but lower concentrations of pesticides were measured in fog collected away from intense agriculture (Schomburg et al., 1991). Herbicides were measured in fog in Beltsville, Maryland; atrazine, simazine, alachlor and metolachlor were found at concentrations ranging from 0.045 to 1.96 I-18 I-’ in the spring of 1987. Herbicides were also identified in fog in California (January sampling) with atrazine and simazine at concentrations ranging from 0.27 to 0.7 and 0.1 to 1.2 ug l-‘, respectively (Glotfelty et al., 1987). There are no reports of pesticides detected in fog collected from remote locations or in fog collected over oceanic water. There are several possibilities for enrichment of organic chemicals in fog. Fog has been shown to have extensive surface areas for scavenging gas and particle phase contaminants from the air (Hoff et al., 1993). Some researchers have also suggested that the particulate matter and/or unusually high dissolved organic carbon content in fogs may account for this enrichment (Glotfelty et al., 1987). One possible mechanism that may be functioning uniquely in arctic environments is that as warm air moves over ice surfaces, sublimation may occur creating fog or mist which acts as a trap for airborne pesticides. In addition, because of the 416
Volume
32/Number S/May 1996 TABLE 4 Concentrations (ng 1-i) of currently-used pesticides in fog condensates. F-l
Pesticide Chorpyrifos Chlorothalonil Endosulphan I Metolachlor Terbufos Trifluralin
F-2 GEOSECS Meteorol. Station
Bristol Bay 4.0 17 wt 51 <3.1
F-3
F-4
F-5
F-6
Southern Bering
Gulf of Anadyr
Diamede Islands
Wrangel Island
F-l Siberian Coast Chukchi
<0.9 8 <2.2 <2.7 <4.5
<2.0 11 < 5.0 <6.0
1 13 < 1.5 147 <3.0 <0.3
5 4 <1.5 < 1.8 < 3.0 <0.3
1 4 <0.5 2 12
<4.0* 17
(‘5)
(2)
*This value is based on the detection limit which is both compound and volume dependent. tparentheses indicate some uncertainty in these data as they were detected at less than twice the detection limits.
Concentrations (pg m-‘)
Atrazine Endosulphan II
TABLE 5 of currently-used pesticides in atmospheric samples.
A-l Alaska Peninsula
A-2 Central Bering
A-3 Gulf of Anadyr
A-4 Siberian Coastline Chukchi
A-5 Eastern Bering
1.1 co.27
<0.29* 1.0
<0.31 0.70
<0.30 (0.W
<0.21 (0.5)
*This value is based on the detection limit which is both compound and volume dependent. tparenthesis indicate some uncertainty to these data as they were detected at less than twice the detection limits.
hydrological and meteorological conditions in these ecosystems, long periods of ice cover and frequent fogs in summer periods, destruction of easily hydrolyzed pesticides is reduced. This could cause a build-up in these compartments causing continuous impacting of these ecosystems. During the long ice-cover period, pesticides reaching this region could accumulate at the ice surface either directly or as dry fall and snow accumulation. In this frozen condition the compounds would be stable in comparison with their behaviour in a dissolved state. The relatively high measured values for atrazine and chlorpyrifos in the ice sample support this theory. Both atrazine and chlorpyrifos have been observed to degrade in aqueous solution in normal temperate conditions. Aquatic hydrolysis is one process which may lead to this degradation. Hydrolysis half-lives in marine water are about 50 days for chlorpyrifos and 200 days for atrazine (Howard, 1991). Atrazine is also subject to photolytic and biological decomposition removal processes. During melt periods these accumulated pesticides are released into adjacent marine waters where biological spring is beginning. Therefore, there is a high potential for ecological damage from these compounds. Our observation of the distribution of these compounds in seawater appears to reflect their chemical properties. Chlorpyrifos decreased rapidly when moving away from the ice fields, suggesting rapid hydrolysis. Atrazine was not found in any of the water samples, indicating that it also dissipates rapidly by dilution and hydrolysis and perhaps also by other processes such as photolysis, biological decomposition and particle sorption and deposition. The occurrence of atrazine and chlorpyrifos in the Arctic ice can be postulated on the basis of both the high usage of these compounds and their unusual
physical chemical properties. Atrazine was the most highly used pesticide in the US at 29 x lo6 kg active ingredient (AI) yr -’ in 1989, and chlorpyrifos was one of the most heavily-used insecticide in the US at 5 x IO6 kg AI yr-’ (Gianessi, 1992). Accurate data for worldwide use of these pesticides are not readily available, but similar practices are likely and could therefore significantly add to these totals. The occurrence of these pesticides in the Arctic ice is most probably due to long-range atmospheric transport, however, some local sources are possible (Bleicher et al., 1980; USEPA, 1986). One could postulate that along with North America, north-eastern Russia, Japan and northern China could contribute these pesticides to this Arctic region, however, accurate production and use data are lacking at this time. The Henry’s law constant (HLC) for chlorpyrifos is relatively high, allowing it to be readily released into the gas phase after application to agricultural fields. Atrazine, while having a much lower HLC than chlorpyrifos, still appears to be released into the atmosphere since it has been detected in Great Lakes water samples (Schottler et al., 1994) as well as in atmospheric precipitation at several locations throughout the world (Glotfelty et al., 1990 (eastern US); Kreuger & Staffas, 1994 (Sweden); Siebers et al., 1994 (northern Germany). Furthermore, recent findings have reported gaseous concentrations of both atrazine and chlorpyrifos in air samples from the Chesapeake Bay area (McConnell et al., 1994). It is important to note that the build-up of these chemicals in cold remote regions like the Bering and Chukchi Seas ecosystems are probably related to air/water gas exchange processes. Henry’s law constant is a numerical measure of volatile release and gas phase deposition of pesticides. A major variable controlling this constant 417
Marine Pollution Bulletin
is temperature. Data to better describe the temperature dependence of HLCs for currently-used pesticides are presently being developed (Rice et al., 1994). Endosulphan was present in many water samples at trace levels and was also detected in fog and air. Endosulphan is used at rather low levels in the US (5 x 10’ kg AI yr-‘; Gianessi, 1992) however, there is evidence of its extensive usage throughout the world, particularly in cotton-growing countries (Gopal & Mukherjee, 1993; Peterson & Batley, 1993). During the last 10 years it was the most common replacement for many of the now banned and more persistent chlorinated pesticides and, therefore, it is not surprising that it was measured at low levels in many of the sample extracts. Arctic researchers have reported its presence in snowpack (0.24-2 ng mw3; Barrie et al., 1992) and air (3.7-4.1 pg rnw3; Bidleman et al., 1995). The concentrations reported here appear to reflect more of a background level rather than suggesting any local contamination sources. Chlorothalonil, a major fungicide (1.8 x lo6 kg AI -I; Gianessi, 1992) was detected in surface microv layer and water at one station near the Alaskan coast, East Chukchi, and in surface microlayer in Bristol Bay (no sub-surface water collected). The fungicide was also found in every fog sample collected. The water solubility of chlorothalonil is high (0.6 mg 1-i) which favours retention in fog. The presence of chlorothalonil in the eastern Chukchi Sea microlayer (200 pg 1-l; subsurface 18 pg 1-i) may have resulted from fog to microlayer exchange during a previous fog episode in this area. This argument also suggests that the fog sampled in the western Chukchi Sea may have previously come from the eastern part of the sea. Trifluralin was also found in many samples collected from the Bering and Chukchi Seas. It is a commonly used herbicide (12.3 x lo6 kg AI yr-‘; Gianessi, 1992) and therefore its occurrence in this region should not be unexpected. Trifluralin is relatively volatile (HLC= 11.5) but it is also very photodegradable and not likely to persist for long periods of time in water. Other researchers have reported the presence of trifluralin in northern air and other Arctic samples (Hoff et al., 1992; Barrie, 1994). The high levels of the herbicide metolachlor (22.5 x lo6 kg AI yr-‘; Gianessi, 1992) measured in fog samples were unexpected. It is believed that these occurred from possible local contamination sources, particularly as metolachlor was not found in any of the other sampled compartments. The solubility of metolachlor is very high (530 mg 1-l) and thus should favour dissolution in fog. Terbufos, a common insecticide (4.6 x lo6 kg AI yr-‘; Gianessi, 1992) was found in one sample of fog. Like metolachlor it has a high water solubility (15 mg l-i), however, the source for both of these pesticides in this remote region needs to be investigated further. Historical data for Alaska show that pesticides such as chlorpyrifos, chlorothalonil, atrazine and diazinon were used in the state both in agriculture and for military purposes (Bleicher et al., 1980; US EPA, 1986) however, the quantities used appear to be very small. 418
There were few pesticides measured in air. Endosulphan was found in four of the five samples which suggests it may be a component of global background air. Atrazine was found in one sample which was collected along the Alaskan Peninsula. Its occurrence here could be explained by the local use of atrazine for agriculture in this region, since samples were taken during the active planting season for this area. At some of the locations the measured compounds could be considered to have possible detrimental impacts on the biota. Johnson & Finley (1980) list toxicities of several pesticides to aquatic organisms, specifically chlorpyrifos (Gummurus lucustris, 0.07-0.17 PLg1-l 96-h LC&) and trifluralin (Rainbow trout, 2662 IQ 1-l 96-h L&a). These concentrations approach the highest values measured in this study. Unique to this region are extreme cold conditions over much of the year which could be responsible for the high accumulations that were observed, especially in Arctic ice. Global fractionation and cold condensation of low volatility compounds in colder climatic zones have been described by Wania & Mackay (1993) and these processes could account for unexpected build-up of these chemicals in the Chukchi and Bering ecosystems. Another feature which is unique to this Arctic region is the dramatic seasonal cycle for atmospheric particulate matter. Long-term data confirm that aerosol concentrations are significantly lower during summer (July-September) and reach maximum levels in January and February, with a dramatic drop at the beginning of summer (Barrie et al., 1992). In the northern hemisphere, major releases of currently-used pesticides occur during the months of April-June and, therefore, the high early-spring particulate phases typical in the Arctic might act as important condensation surfaces for pesticides as they are transported northward through the air (Wania & Mackay, 1993). Presently, there are no data on currently-used pesticides to verify these hypotheses. The current study was an attempt to provide this information.
Conclusion This is the first published investigation describing currently-used pesticides in Bering and Chukchi marine ecosystems. Now there is clear evidence that the following currently-used agrochemicals are present in many of the compartments sampled: chlorpyrifos, atrazine, endosulphan, trifluralin and chlorothalonil. Many unusual features of this environment, i.e. extreme cold, high winter atmospheric particulate episodes and high summer-season biological productivities, lead to unusual transport and cycling of these compounds relative to more temperate regions. There is a possibility that these chemicals may be causing ecological damage in these vulnerable regions. It is realized that this preliminary investigation needs to be further developed, including many more measurements over the entire spring-summer period when these pesticides are applied in the northern hemisphere. Also, the list of monitored pesticides should be changed, for example, it would be important to consider pesticides
Volume 32/Number S/May 1996
which are not only used in North America but also in neighbouring countries, such as Japan, far-eastern Russia and northern China. Atmospheric back-trajectory analyses from the Bering and Chukchi regions could also be utilized to better clarify the sources of these pesticides. The authors especially wish to thank Peter McRoy for encouraging our interest in measuring currently-used pesticides in marine arctic fog. They also acknowledge the assistance of William Strachan in the collection and sharing of his large volume water samples, Terry F. Bidleman and Liisa Jantunen for the collection and sharing their high volume air samples, and thank Lisa Ross for the use of her fog collectors. They would especially like to thank the US Fish and Wildlife Service and The Institute of the Global Climate and Ecology (Russian Hydromet Federal Service) for organizing and sponsoring this BERPAC expedition, and Captain Anatoly L. Akimov for organizing the work on board the RV Okean. They also thank Derek Muir for his excellent reviews during the preparation of this manuscript, and the journal reviewers for their care and attention to detail. Anthony, D. H. J. (1993). Application of the Goulden large sample extraction technique in sampling ‘ditiicult’ environmental aqueous matrices. American Chemical Society-Division of Environmental Chemistry, Meeting,
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