Spatial and temporal distribution of pesticide air concentrations in Canadian agricultural regions

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Atmospheric Environment 40 (2006) 4339–4351 www.elsevier.com/locate/atmosenv

Spatial and temporal distribution of pesticide air concentrations in Canadian agricultural regions Yuan Yaoa, Ludovic Tudurib, Tom Harnera,, Pierrette Blancharda, Don Waitec, Laurier Poissantd, Clair Murphye, Wayne Belzerf, Fabien Aulagnierd, Yi-Fan Lia, Ed Sverkog a Science and Technology Branch, Environment Canada, 4905 Dufferin St., Toronto, ON, Canada M3H 5T4 Laboratoire de PhysicoToxicochimie des Syste`mes Naturels, Equipe Pe´rigourdine de Chimie Applique´e, Site universitaire, 24019 Pe´rigueux cedex, France c Environmental Conservation Branch, 2365 Albert Street, Park Plaza, Regina, SK, Canada S4P 4K1 d Science and Technology Branch, 105 rue McGill, 7e e´tage (Youville), Montreal, QC, Canada H2Y 2E7 e Environmental Protection Branch, 97 Queen Street, Charlottetown, PEI, Canada C1A 4A9 f Environmental Conservation Branch, 201-401 Burrard St., Vancouver, BC, Canada V6C 3S5 g National Laboratory for Environmental Testing, 867 Lakeshore Road, Burlington, ON, Canada L7R 4A6

b

Received 24 January 2006; accepted 24 March 2006

Abstract The Canadian Pesticide Air Sampling Campaign was initiated in 2003 to assess atmospheric levels of pesticides, especially currently used pesticides (CUPs) in agricultural regions across Canada. In the first campaign during the spring to summer of 2003, over 40 pesticides were detected. The spatial and temporal distribution of pesticides in the Canadian atmosphere was shown to reflect the pesticide usage in each region. Several herbicides including triallate, bromoxynil, MCPA, 2,4-D, dicamba, trifluralin and ethalfluralin were detected at highest levels at Bratt’s Lake, SK in the prairie region. Strong relationships between air concentrations and dry depositions were observed at this site. Although no application occurred in the Canadian Prairies in 2003, high air concentrations of lindane (g-hexachlorocyclohexane) were still observed at Bratt’s Lake and Hafford, SK. Two fungicides (chlorothalonil and metalaxyl) and two insecticides (endosulfan and carbofuran) were measured at highest levels at Kensington, PEI. Maximum concentrations of chlorpyrifos and metolachlor were found at St. Anicet, QC. The southern Ontario site, Egbert showed highest concentration of alachlor. Malathion was detected at the highest level at the west coast site, Abbotsford, BC. In case of legacy chlorinated insecticides, high concentrations of DDT, DDE and dieldrin were detected in British Columbia while a-HCH and HCB were found to be fairly uniform across the country. Chlordane was detected in Ontario, Que´bec and Prince Edward Island. This study demonstrates that the sources for the observed atmospheric occurrence of pesticides include local current pesticide application, volatilization of pesticide residues from soil and atmospheric transport. In many instances, these data represent the first measurements for certain pesticides in a given part of Canada. Crown Copyright r 2006 Published by Elsevier Ltd. All rights reserved. Keywords: Pesticides; Currently used pesticides; Canadian atmosphere; Spatial and temporal distribution; Atmospheric transport

Corresponding author.

E-mail address: [email protected] (T. Harner). 1352-2310/$ - see front matter Crown Copyright r 2006 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.atmosenv.2006.03.039

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1. Introduction Pesticides are chemicals that are used to control pest species and remove unwanted plants. Historically, organochlorine pesticides (OCPs) have been the most widely used insecticides. However, many of them are persistent organic pollutants (POPs) due to their high toxicity, stability, bioaccumulation and long-range transport (LRT) potential. Since the ban of most OCPs in the 1970s, the use of other types of pesticides such as organophosphate pesticides (OPPs), triazine, acetanilide and phenoxyacid herbicides has increased dramatically worldwide. In Canada, there are over 7000 pesticide products and over 500 active ingredients (a.i.) are registered for use, primarily (ca. 91%) for agriculture. The total Canadian agricultural usage was 41684 t measured by a.i. in 1988 (Brimble et al., 2005). Pesticides can enter the atmosphere through spray drift, post-application volatilization, and wind erosion of treated soil. Once in the air, these compounds can be redistributed, degraded, transported, and returned to the earth’s surface via wet and dry deposition (Wania and Mackay, 1996; Muir et al., 2004). Currently, there are only limited data on the presence, distribution and fate of currently used pesticides (CUPs) in the Canadian atmosphere (Tuduri et al., 2006a, b). Some measurements of air concentration and precipitation have been made for g-hexachlorocyclohexane (g-HCH), endosulfan and atrazine at selected sites in the Great Lakes basin under the Integrated Atmospheric Deposition Network (IADN) (Hoff et al., 1996; Blanchard et al., 2000). Rawn et al. (1999) studied the temporal trends of 4 herbicides in air and precipitation in southern Manitoba (MB). In Saskatchewan (SK), approximately 10 herbicides plus g-HCH were regularly monitored in air, wet and dry depositions during application seasons by Waite et al. for several years (Waite et al., 2002, 2004, 2005). In Que´bec (Que.), atmospheric concentrations of gHCH were investigated (Poissant and Koprivnjak, 1996; Garmouma and Poissant, 2004; Aulagnier and Poissant, 2005). In British Columbia (BC), Belzer et al. (1998) detected several CUPs in air at Agassiz and Abbotsford. For Prince Edward Island (PEI), White et al. (2000) reported the occurrence of chlorothalonil and metalaxyl in air from potato growing areas. Recently, Harner et al. (2004, 2005) and Motelay-Massei et al. (2005) reported g-HCH and endosulfan atmospheric distribution in the city of Toronto, ON and the Fraser Valley, BC.

The Canadian Pesticide Air Sampling Campaign (CPASC) is a 3-year program that was initiated in 2003. It consists of two subprojects: (1) The Canadian Atmospheric Network for Currently Used Pesticides (CANCUP) and (2) An intensive field study in the Canadian Prairies (Prairie Study). The objectives of this project are to (a) provide information on atmospheric levels of CUPs across Canada, (b) better understand spatial and temporal trends of pesticides in air, (c) assess their long-range atmospheric transport potential and transboundary flow, and (d) further identify future pesticide issues regarding environmental processes research, risk assessment, and policy making. In this paper, the results from the 2003 air sampling campaign are discussed. 2. Methodology 2.1. Sample collection Sampling was undertaken at eight sampling sites located in agricultural and receptor regions across Canada (Fig. 1, Table 1). Air samples were collected weekly using PS-1 high volume samplers (Tisch Environmental, Inc., Village of Cleves, OH) situated at approximately 1–3 m above ground level at a flow rate of about 250 L min
1 (ca. 2500 m3 sample volume). Particles were trapped on glass fiber filters (102 mm diameter; Pall Life Sciences, Ann Arbor, MI) and gaseous compounds were collected with cartridges containing 10 g of XAD-2 resin (Supelpak 2, Supelco, Bellefonte, PA) sandwiched between polyurethane foam (PUF) plugs (75 mm  37 mm, Supelco). At Bratt’s Lake, air samples were collected at 1-, 10- and 30-m heights with PS-1 samplers. In addition, dry atmospheric deposits were collected at 1-m height using a Waite–Banner sampler (Waite et al., 1999). This sampling system releases water-soluble pesticides from particles into water first and then traps them by passing the water through an XAD-2 resin column. All samples were stored at about 4 1C and in the dark until extraction. One field blank was collected at each site. 2.2. Sample analysis The method for extraction of the high-volume and dry deposition samples has been described previously (Waite et al., 2005). Briefly, after adding 2,4-D-d5 as a surrogate standard, PUF/XAD/filter samples were Soxhlet extracted with acetone for

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Fig. 1. Sampling sites and agricultural regions across Canada.

Table 1 Description of the sampling sites and periods Sampling site

Latitude 0

Longitude 0

Kensington, PEI St. Anicet, QC

46125 N 451070 N

63137 W 741170 W

Baie St. Francois, QC Egbert, ON

461050 N

721560 W

441140 N

791470 W

Bratt0 s Lake, SK

501160 N

1041420 W

Hafford, SK

521430 N

1071210 W

Waskesiu, SK

531550 N

1071210 W

Abbotsford, BC

491 010 N

1221 200 W

12 h while XAD-2 columns were extracted by back flushing with acetone. The extracts were concentrated and solvent exchanged to hexane followed by gas chromatography/mass spectrometry analysis. The analysis was divided into phases 1 and 2. Under phase 1, 50% of the each weekly sample extract was analyzed for 11 target pesticides (primarily herbicides) by the Environment Canada (EC) Environmental Protection laboratory (EPL). The extracts were analyzed using a gas chromato-

Description

Sampling period

Heart of potato growing country. Rural and agricultural area (corn, pasture land). Wetland covered with mixed vegetation. Receptor site. Rural and suburban area, surrounded by fields and mixed forest. Rural and intensive agricultural area (cereals) with few trees. Agricultural area (cereals, oilseeds) with trees. Unseeded fields located adjacent to this site. In a national park, densely treed. No crops within 50 km of the site. Receptor site. Fraser Valley, pig and chicken farms and berry crops.

22 July–26 August 2003 22 July–19 August 2003 22 July–19 August 2003 22 July–19 August 2003

12 May–13 August 2003 12 May–13 August 2003

12 May–13 August 2003

22 July–19 August 2003

graph (GC: 6890, Agilent Technologies, Palo Alto, CA)/mass selective detector (MSD: 5973, Agilent) system. A DB-5MS (30 m length  0.25 mm i.d., 0.25 mm film thickness) column was used and the temperature program started at 80 1C for 1 min, 20 1C min
1–140 1C, hold for 6 min, 2 1C min
1– 180 1C, hold for 1 min, then 10 1C min
1–300 1C and hold for 5 min. A sample cleanup with Florisil column was conducted when necessary. Under phase 2, the remaining 50% portion from each

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weekly sample was pooled into a monthly composite. This was split and sent to the EC National Laboratory for Environmental Testing (NLET) and EC Environmental Quality Laboratory (EQL) for a wide range analysis. NLET performed sample cleanup with silica gel (for OCPs and OPPs) and Florisil (for neutral herbicides) columns, and applied GC/electron capture detector (ECD) for OCP and GC/MSD for OPP and neutral herbicide (NH) determinations. DB-5 columns (same as above) were utilized for quantification and the following temperature programs were used: for OCPs: 80 1C for 2 min, 4 1C min
1–260 1C and hold for 8 min; for OPPs: 80 1C for 2 min, 10 1C min
1–160 1C, 3 1C min
1–265 1C, then 50 1C min
1–285 1C and hold for 5 min; for NHs: 80 1C for 2 min, 6 1C min
1–275 1C and hold for 8 min. At EQL, a GC 6890/MSD 5973 system fitted with a HP-5MS (30 m  0.25 mm, 0.25 mm film thickness) was employed. The temperature program initiated at 105 1C for 3 min, 3 1C min
1–150 1C, 15 1C min
1–250 1C, hold for 15 min, 10 1C min
1–280 1C, hold for 2.33 min, then 10 1C min
1–300 1C and hold for 5 min. Average surrogate recovery was 123% (n ¼ 97, SD ¼ 31%). Levels of selected pesticides in the field blanks were less than 4% of sample amounts with the exception of dieldrin at 8%. No recovery or blank correction was applied to the results.

3. Results and discussion 3.1. Prairie study The Prairies are the most extensive agricultural zone with highest pesticide usage in Canada (Fig. 1). The southern parts of Alberta (AB, SK and MB are responsible for over half of the total pesticide use in the country (Waite et al., 2002). As the largest pesticide user nationwide, SK is responsible for approximately 36% of all pesticide sales each year (Brimble et al., 2005), of which most are herbicides. In 2003, samples were collected at Bratt’s Lake, Hafford, and Waskesiu from 12 May to 13 August (Table 1). Most of the 11 target pesticides were detected in air samples with highest frequencies of detections for triallate (97%), bromoxynil (95%), MCPA (94%), 2,4-D (90%), dicamba (90%), and gHCH (83%) (Table 2). These observations are consistent with previous air and water studies (Waite et al., 2005; Donald et al., 2001).

3.1.1. Herbicides Triallate: Triallate is used for pre-emergent control of grass weeds in field and pulse crops. In Canada, it is the 6th most used pesticide with an annual sales/use of 708 t a.i. (excluding the provinces of SK and QC for which no pesticide sales/use data are available) (Brimble et al., 2005). In this study, triallate was the most frequently detected herbicide and was detected at highest level among the 11 target pesticides in the Prairies. This may be partly attributed to its higher vapor pressure compared to others (Smith et al., 1997). Fig. 2(a) shows the temporal trends of triallate air concentrations with altitude and dry deposition during the 3month period. The air concentrations of triallate at 3 different heights showed similar time trends. Generally, air concentrations of triallate were highest at 1-m and decreased with elevation to 30-m. This decrease with elevation suggests an important contribution of local sources of triallate at ground level rather than sources associated with long-range transport (LRT) (Waite et al., 2005). Concentrations of triallate were variable at the 3 prairie sites (Fig. 3(a)) and were likely influenced by local applications. MCPA, 2,4-D, bromoxynil and dicamba: MCPA, 2,4-D, bromoxynil and dicamba are widely applied and ranked as the 3rd, 4th, 10th and 15th most used pesticides nationwide (1,540, 1,491, 544 and 356 t a.i. y
1, respectively) (Brimble et al., 2005). These chemicals were frequently detected in air samples collected at the three prairie sites. Good correlations between air concentration trends and dry deposition trends were observed for these herbicides (Fig. 2(b–e)). The peak air concentrations for these pesticides were observed from the 5th to 7th weeks during the study period when these postemergent herbicides are typically applied on the Prairies (Waite et al., 2005). In general, air concentrations of 2,4-D, bromoxynil and dicamba were similar at all three heights suggesting similar contributions from both local and long-distance transport. MCPA concentrations at all heights were generally similar, except the 5th week in which the concentration at 1-m height was almost an order of magnitude higher than those at 10- and 30-m. This reflects local use which was confirmed by the land owner. Similar time trends of air concentrations of these compounds were observed at the three sites (Fig. 3(b–e)), suggesting atmospheric transport of these pesticides within the Canadian Prairies.

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Table 2 Concentrations of currently used pesticides in air and dry deposition samples collected under the Prairie Study during the spring and summer of 2003a Analyte

Bratt0 s Lake

Hafford

Waskesiu

Air sample (1-m) Air sample (10-m) Air sample (30-m) Dry deposition Air sample (1-m) Air sample (1-m)

g-HCH

Max Ave Min Triallate Max Ave Min MCPA Max Ave Min 2,4-D Max Ave Min Bromoxynil Max Ave Min Dicamba Max Ave Min Trifluralin Max Ave Min Ethalfluralin Max Ave Min Atrazine Max Ave Min Alachlor Max Ave Min Metolachlor Max Ave Min

(pg m
3)

(pg m
3)

(pg m
3)

(ng m
2 d
1)

(pg m
3)

(pg m
3)

479 171 68.8 15 300 2880 402 4960 513 9.5 897 219 28.6 791 185 8.6 615 184 19.0 811 170 ND 453 115 ND 19.9 4.3 ND ND ND ND ND ND ND

327 182 80.9 3640 1500 286 952 223 15.5 1090 331 38.0 761 199 12.1 626 187 25.8 503 272 ND 620 209 ND 41.2 9.0 ND ND ND ND 10.6 ND ND

932 233 ND 9460 1550 54.8 876 191 10.6 1460 331 47.8 722 203 12.1 372 145 21.2 816 388 63.7 889 308 ND 53.1 8.7 ND 15.9 ND ND 10.9 ND ND

0.18 0.07 ND 6.63 1.71 0.15 7.20 1.00 0.03 0.84 0.30 0.01 0.61 0.14 ND 0.88 0.22 0.01 0.18 0.08 0.01 0.43 0.15 ND 0.03 ND ND 0.01 ND ND ND ND ND

244 141 ND 2190 318 46.8 342 82.0 15.4 492 117 ND 804 144 ND 261 39.6 5.2 734 70.6 ND 327 27.2 ND ND ND ND ND ND ND ND ND ND

220 68.5 ND 155 52.2 ND 160 32.8 ND 240 58.7 ND 256 49.1 ND 35.0 10.1 ND 24.8 5.0 ND ND ND ND ND ND ND 4.9 ND ND ND ND ND

a The method detection limits (MDLs) based on a sample volume of 2500 m3 and an extract volume of 1 mL for all analytes are 4 pg m
3, except ethalfluralin (20 pg m
3).

Trifluralin and ethalfluralin: Like triallate, trifluralin and ethalfluralin are pre-emergence neutral herbicides. They are among the top 20 most used pesticides in Canada (317 and 598 t a.i. y
1, respectively) (Brimble et al., 2005). Trifluralin and ethalfluralin were detected less frequently (68% and 49%) than triallate. This may be related to their lower vapor pressures compared to that of triallate (Smith et al., 1997). Smith et al. (1997) reported a total of 21%, 18% and 14% of applied triallate, trifluralin and ethalfluralin volatilizing from soil over a 24-day period under prairie conditions in

spring. Another explanation could be linked to the photosensitivity of dinitroaniline herbicides. In contrast to photostable triallate (Majewski et al., 1993), trifluralin vapor can undergo rapid photochemical conversion to a dealkylated product with a half-life of approximately 20 min under midday summer sunlight conditions (Woodrow et al., 1978). Atrazine, metolachlor and alachlor: Atrazine is a selective triazine herbicide. Although atrazine and related active triazines are commonly used in Canada (577 t a.i. y
1), it is seldom applied in the Prairies. The same is true for metolachlor, which is

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8

8

12000

Air sample 30m Dry deposition

9000

4

6000 2 3000 0

800 0.30 400

Sampling date, 2003

Air sample 10m Air sample 30m

600

0.40 400 0.20

200

/0 5 21 -21 /0 /05 5 28 -28 /0 /05 5 04 -04 /0 /06 6 11 -11 /0 /06 6 18 -18 /0 /06 625 25 /0 /06 6 02 -02 /0 /07 7 09 -09 /0 /07 7 16 -16 /0 /07 7 23 -23 /0 /07 7 30 -30 /0 /07 7 06 -06 /0 /08 813 /0 8

0.00

12

12

(d) 1.00

Sampling date, 2003 1000

Air sample 1m

0.80

Air sample 30m Dry deposition

0.60

400 0.40 200

0.20

0

Air concentration (pg m-3)

Air sample 10m

Dry deposition (ng m-2 d-1)

Air concentration (pg m-3)

Air sample 1m 600

Air sample 30m

0.15

Dry deposition

600

0.10 400 0.05 200

0.00

0 /0 5 21 -21 /0 /05 5 28 -28 /0 /05 5 04 -04 /0 /06 6 11 -11 /0 /06 6 18 -18 /0 /06 6 25 -25 /0 /06 602 02 /0 /07 7 09 -09 /0 /07 7 16 -16 /0 /07 723 2 3 /0 /07 7 30 -30 /0 /07 7 06 -06 /0 /08 813 /0 8

/0 5 21 -21 /0 /05 5 28 -28 /0 /05 504 0 4 /0 /06 6 11 -11 /0 /06 6 18 -18 /0 /06 6 25 - 2 5 /0 /06 60 2 02 /0 /07 7 09 -09 /0 /07 7 16 -16 /0 /07 7 23 - 2 3 /0 /07 73 0 30 /0 /07 7 06 -06 /0 /08 813 /0 8

Sampling date, 2003

0.20

Air sample 10m

800

0.00

12

12

(e)

0.60

Dry deposition

0

Sampling date, 2003 800

0.80

800

0.00

/0 5 21 -21 /0 /05 5 28 -28 /0 /05 5 04 -04 /0 /06 611 11 /0 /06 6 18 -18 /0 /06 6 25 -25 /0 /06 602 02 /0 /07 7 09 -09 /0 /07 7 16 -16 /0 /07 7 23 -23 /0 /07 730 30 /0 /07 7 06 -06 /0 /08 813 /0 8

0

0

12 /0 5 21 -21 /0 /05 5 28 -28 /0 /05 5 04 -04 /0 /06 6 11 -11 /0 /06 6 18 -18 /0 /06 6 25 -25 /0 / 0 6 602 02 /0 /07 7 09 -09 /0 /07 7 16 -16 /0 /07 7 23 -23 /0 / 0 7 730 30 /0 /07 7 06 -06 /0 /08 813 /0 8

0.60

Air concentration (pg m-3)

Air sample 30m Dry deposition

-1

-3

2

Air sample 1m Dry deposition (ng m-2 d-1)

Air concentration (pg m-3)

2000

1000

0.90

Air sample 10m 1200

(c)

4

(b) Air sample 1m

6

Dry deposition

0

Sampling date, 2003 1600

Air sample 30m

4000

0

12 /0 5 21 -21 /0 /05 5 28 -28 /0 /05 5 04 -04 /0 / 0 6 611 11 /0 /06 6 18 -18 /0 /06 6 25 -25 /0 / 0 6 602 02 /0 /07 7 09 -09 /0 /07 716 16 /0 /07 7 23 -23 /0 / 0 7 730 30 /0 /07 7 06 -06 /0 /08 813 /0 8

(a)

Air sample 10m

-2

6

Air concentration (pg m )

Air sample 10m

Dry deposition (ng m-2 d-1)

Air concentration (pg m-3)

15000

Dry deposition (ng m d )

Air sample 1m

Air sample 1m

Dry deposition (pg m-2 d-1)

18000

Dry deposition (ng m-2 d-1)

4344

(f)

Sampling date, 2003

Fig. 2. Time trends of CUP concentrations in air and dry deposition at Bratt’s Lake during May–August 2003: (a) triallate, (b) MCPA, (c) 2,4-D, (d) bromoxynil, (e) dicamba, and (f) g-HCH.

usually applied to crops before plants emerge from the soil. Alachlor which works by interfering with protein production and root elongation is not registered for use in Canada. These three compounds were detected very infrequently at the three sites and at low concentrations (Table 2). Their occurrence is probably indicative to LRT from the United States, where these pesticides are widely utilized in corn cultivation (Waite et al., 2005).

3.1.2. Insecticides g-HCH: Although the technical HCH formulation containing five isomers (a-: 60–70%, b-: 5–12%, g-: 10–12%, d-: 6–10%, and e-: 3–4%) was banned in many countries during the 1970s, lindane consisting of at least 99% g-HCH was continued to be used in Canada until 2004. Lindane was mainly used as a seed treatment on canola in the Canadian Prairies. Approximately 455 and 510 t

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)

(

15000 12000

Bratt's Lake (→) 9000

1000 6000 500

3000

3000 2000 1000

12

/0 21 5-2 /0 1/0 28 5-2 5 /0 8/0 04 5-0 5 /0 4/0 11 6-1 6 /0 1/0 18 6-1 6 /0 8/0 25 6-2 6 /0 5/0 02 6-0 6 /0 2/0 09 7-0 7 /0 9/0 16 7-1 7 /0 6/0 23 7-2 7 /0 3/0 30 7-3 7 /0 0/0 06 7-0 7 /0 6/0 8- 8 13 /0 8

0

900

Sampling date, 2003

8-

13

/0

8

7

8 /0 06

706

/0

7

/0 30

7-

/0 30

7

/0 23

7-

/0

/0

23

7

/0 16

7/0

16

7

/0 09

709

6

/0 02

6-

/0 02

6

/0 25

6-

/0

/0

25

6 /0

6-

18

/0

6

/0 11 11

6-

/0

Sampling date, 2003

300

700 )

250

Hafford

)

200

Bratt's Lake (→)

(

600 500 400

150 300 100

200

50

100

500

300 200 100 0 /0 521 21/ 0 /0 5- 5 28 28/ 0 /0 5- 5 04 04/ 0 /0 6- 6 11 11/ 0 /0 6- 6 18 18/ 0 /0 6- 6 25 25/ 0 /0 6- 6 02 02/ 0 /0 7- 7 09 09/ 0 /0 7- 7 16 16/ 0 /0 7- 7 23 23/ 0 /0 7- 7 30 30/ 0 /0 7- 7 06 06/ 0 /0 8- 8 13 /0 8

12

12

Sampling date, 2003

Waskesiu Hafford Bratts Lake

(f)

400

0

/0 21 5-2 /0 1/0 28 5-2 5 /0 8/0 04 5-0 5 /0 4/0 11 6-1 6 /0 1/0 18 6-1 6 /0 8/0 25 6-2 6 /0 5/0 02 6-0 6 /0 2/0 09 7-0 7 /0 9/0 16 7-1 7 /0 6/0 23 7-2 7 /0 3/0 30 7-3 7 /0 0/0 06 7-0 7 /0 6/0 8- 8 13 /0 8

0

600 Air concentration (pgm-3)

Waskesiu (

Air concentration (pg m-3)

Air concentration (pg m-3)

/0

28

5-

28

/0

5 12

21

/0

5-

21

/0

2 /0 1/0 5 5 28 -28 /0 /0 5- 5 04 04 /0 /0 6 6 11 -11 /0 /0 6- 6 18 18 /0 /0 6 6 25 -25 /0 /0 6- 6 02 02 /0 /0 7 7 09 -09 /0 /0 7- 7 16 16 /0 /0 7 7 23 -23 /0 /0 7 7 30 -30 /0 /0 7- 7 06 06 /0 /0 8- 8 13 /0 8

5/0 12

5

0

0

/0

0

04

200

100

300

04

400

200

Bratt's Lake

5-

300

Hafford

/0

600

Waskesiu

600

21

)

(d)

Air concentration (pg m-3)

(

800

Air concentration (pg m-3)

)

Bratt's Lake (→)

(e)

4000

0

12

Air concentration (pg m-3)

Hafford 400

5000

Sampling date, 2003

Waskesiu (

500

)

(

100

1000

(c)

Hafford

Bratt's Lake (→)

Sampling date, 2003 600

)

200

0

/0 21 5-2 /0 1/0 28 5-2 5 /0 8/0 04 5-0 5 /0 4/0 11 6-1 6 /0 1/0 18 6-1 6 /0 8/0 25 6-2 6 /0 5/0 02 6-0 6 /0 2/0 09 7-0 7 /0 9/0 16 7-1 7 /0 6/0 23 7-2 7 /0 3/0 30 7-3 7 /0 0/0 06 7-0 7 /0 6/0 8- 8 13 /0 8

0

300

Waskesiu (

Air concentration (pg m-3)

)

Hafford

6000

(b)

18

1500

Waskesiu (

Air concentration (pg m-3)

2000

400

18000

(a)

Air concentration (pg m-3)

Air concentration (pg m-3)

2500

4345

Sampling date, 2003

Fig. 3. Time trends of CUP air concentrations (1-m height) at Bratt’s Lake, Hafford and Waskesiu sites during May–August 2003: (a) triallate, (b) MCPA, (c) 2,4-D, (d) bromoxynil, (e) dicamba, and (f) g-HCH. Arrows in parentheses indicate the corresponding axes (left or right).

of lindane were applied in 1997 and 1998, respectively (Waite et al., 2001). Lindane sale in Canada was discontinued on 31 December 2002 by registrants and at the end of 2003 by retailers. In the Prairies, lindane usage was reduced to one-half its usual amount in 2002 and no application occurred in 2003. Nevertheless, lindane was still found constantly at Bratt’s Lake (Fig. 2(f)) and detected

from most samples collected at Hafford and Waskesiu during the sampling period. According to Waite et al. (2001), the g-HCH air concentrations at Bratt’s Lake peaked early June in 1997 (16 100 pg m
3) and late May in 1998 (7400 pg m
3), respectively. Compared to these data, the observed maximum atmospheric concentration of 479 pg m
3 at Bratt’s Lake (1-m height) was quite low,

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Table 3 Concentrations (pg m
3) of pesticides in pooled air samples collected under CANCUP during the summer of 2003 Analyte

Chlorothalonil Metalaxyl a-Endosulfan b-Endosulfan Carbofuran Chlorpyrifos Malathion Atrazine Dicamba Trifluralin Ethalfluralin Metolachlor Alachlor g-HCH a-HCH p,p0 -DDT o,p0 -DDT p,p0 -DDE o,p0 -DDE HCB TC CC Dieldrin a

Abbotsford

Egbert

St. Anicet

Baie St. Francois

Kensington

22 July–19 August 2003

22 July–19 August 2003

29 July–19 August 2003

29 July–19 August 2003

22 July–26 August 2003

NA NA 488 159 NA 281 2510 51.1 ND 6.2 ND ND 71.8 23.0 32.4 72.6 93.0 ND 66.6 80.6 ND ND 71.6

5200 ND 717 162 ND 378 28.3 ND 7.6 91.1 ND 129 665 17.5 45.7 17.4 29.2 28.9 0.7 50.7 6.7 6.4 36.3

3030 ND 625 116 ND 768 76.3 45.5 72.6 36.0 ND 480 190 92.2 ND ND ND 13.7 ND 74.1 10.1 ND ND

1860 ND 221 39.6 ND 742 ND 15.5 7.2 38.2 ND 111 31.0 35.7 27.2 9.8 3.8 10.3 ND 56.5 9.6 7.2 15.7

11900 496 5710 1960 1800 107 ND 14.5 ND 11.4 70.9 97.9 ND 10.4 47.9 ND 10.4 11.3 ND 51.9 1.3 2.3 7.2

MDLa

Analysis lab

40 40 0.1 0.4 40 0.1 0.5 4.0 4.0 4.0 20 9.5 4.0 0.1 0.1 0.5 0.3 0.5 0.1 0.3 0.1 0.1 0.1

EQL EQL NLET NLET EQL NLET NLET EPL EPL EPL EPL NLET EPL NLET NLET NLET NLET NLET NLET NLET NLET NLET NLET

The MDLs are based on a sample volume of 2500 m3 and an extract volume of 1 mL.

indicating the significant decrease in lindane air concentration after the cessation of its application. In addition, lindane concentrations at the three sites show similar time trends (Fig. 3(f)) suggesting that air burdens are related to volatilization of residual lindane in the soil from previous applications and its regional atmospheric transportation. Ma et al. (2003) indicated that the atmospheric loading of gHCH to the Great Lakes system was mostly attributed to applications of lindane in the Prairies. 3.2. CANCUP Sampling under CANCUP in 2003 occurred late in the summer. Results will therefore not reflect the potential concentrations of pesticides that are used early in the growing season. Nevertheless, under phase 2 analysis, 27 CUPs were detected in air samples. The results reflected the characteristics of pesticide use in each region. Nationally, 77% of pesticide sales are herbicides while fungicides and insecticides only represent 9% and 8% of pesticide

sales in 2003 (Brimble et al., 2005). Nevertheless, fungicides and insecticides, such as chlorothalonil, endosulfan, malathion and carbofuran, were detected at high levels. Table 3 summarizes monthly average results from CANCUP. 3.2.1. Fungicides Chlorothalonil and metalaxyl: Chlorothalonil is a broad-spectrum fungicide acting on the enzyme systems in fungi. In Canada, it is one of the top 20 most used pesticides (265 t a.i. y
1) (Brimble et al., 2005). Metalaxyl is a systemic fungicide used for potatoes, sugar beets, and other crops. Chlorothalonil was detected from air samples collected in ON, QC and PEI (Fig. 4(a)). The monthly average air levels ranged from 1860 to 11900 pg m
3. These data are much higher than those reported by James and Hites (1999) around the Great Lakes (30–100 pg m
3). The highest air concentration was observed at Kensington, which was higher than those of other pesticides. This observation is consistent with the importance of potato production

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4347

Fig. 4. Monthly average concentrations of pesticides in air across Canada during July–August 2003: (a) chlorothalonil, (b) endosulfan, malathion and chlorpyrifos, (c) g-HCH, trifluralin, dicamba and atrazine, (d) alachlor and metolachlor, (e) DDT, DDE and dieldrin, (f) a-HCH, HCB and chlordane. White stars represent no available data for the target pesticides.

and the pesticide use pattern on the Island. Although herbicide usage in Canada generally far exceeds that of either fungicides or insecticides, the majority (82%) of pesticides used in PEI are fungicides led by mancozeb and chlorothalonil. From 1999 to 2002, the amount of chlorothalonil sold in PEI has been on the order of 50 t a.i. y
1 (Brimble et al., 2005). There is increasing evidence that chlorothalonil is a relatively persistent compound in air and can be atmospherically transported significant distances from its use area (White et al., 2000). In the case of metalaxyl, it was only detected at Kensington (496 pg m
3). PEI has the

highest metalaxyl-M (consisting of a minimum of 97% of the R-enantiomer) sales/use of 20 t a.i. y
1 nationwide (Brimble et al., 2005). Previously, White et al. measured an average metalaxyl concentration at 400 pg m
3 at Kensington (White et al., 2000). 3.2.2. Insecticides Endosulfan: Endosulfan is a chlorinated insecticide. It has been widely used for protection of vegetables, fruits and grains since mid 1950s. Technical endosulfan contains two isomers, aendosulfan and b-endosulfan, in approximately a 7:3 ratio (ca. 2.3). Endosulfan was detected from air

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samples at all CANCUP sites, in which the maximum monthly average concentration was found at Kensington (a-: 5 710 pg m
3, b-: 1960 pg m
3) (Fig. 4(b)). The observed ratio of the two isomer concentrations is 2.9 (close to 2.3). Considering the high levels of a- and b-endosulfans in air coupled with their composition that matches the technical mixture, spraying was likely conducted during the sampling period. These results agree well with previous observations showing mean air concentrations of 6300 and 1600 pg m
3 for a- and b-endosulfans at Kensington in 1998–1999 (White et al., 2000). A similar a/b ratio (3.1) was observed at Abbotsford. For the other three sites, the observed a/b ratios were quite higher (4.4
5.6). This might be attributed to the fact that bendosulfan is less stable and converts to a-isomer in the environment after application (Schmidt et al., 1997, 2001), thus increasing the a/b ratio. The observed endosulfan concentrations at St. Anicet (a-: 625 pg m
3, b-: 116 pg m
3) were higher than those at Baie St. Francois (a-: 221 pg m
3, b-: 40 pg m
3), while their a/b ratios were almost the same (5.4 and 5.5). As St. Anicet is an agricultural source area and Baie St. Francois is a nonagricultural area close to St. Anicet, the observed endosulfan at Baie St. Francois may result from regional atmospheric transport from St. Anicet. At Egbert, the measured air concentrations of a- and bendosulfans were 717 and 162 pg m
3, respectively. These values are somewhat lower than peak concentrations measured at this site by IADN between 1997 and 2004 (IADN, 2002). The obtained a-endosulfan value is consistent with that (817 pg m
3) measured during the summer of 2000 by Harner et al. (2004). Carbofuran, chlorpyrifos and malathion: Carbofuran is a broad-spectrum carbamate insecticide. It is used against soil and foliar pests of field, fruit, and vegetable crops. This compound was only found at Kensington with a high air concentration of 1800 pg m
3. Again, this observation coincides well with its usage pattern for PEI. It has the highest carbofuran sales/use quantity (4.5 t a.i. y
1) among all investigated provinces (Brimble et al., 2005). While originally used to kill mosquitoes, chlorpyrifos is now widely used for crop production. As can be seen from Fig. 4(b), chlorpyrifos was found in air across Canada in the range of 107
768 pg m
3 with highest concentrations at St. Anicet and Baie St. Francois. Malathion is used for the control of sucking and chewing insects on fruits and vegetables. It was detected in air samples in BC, ON and

QC (Fig. 4b), with highest level at Abbotsford (2510 pg m
3). Sales/use of malathion in BC (4.7 t a.i. y
1) is greater than in any other investigated province (Brimble et al., 2005). The high concentration observed at Abbotsford is likely related to its application on berry fields in the region. g-HCH: g-HCH was detected at all CANCUP sites and ranged from 10 to 92 pg m
3, in which the highest level was observed at St. Anicet (Fig. 4(c)); prairie sites concentrations are added for comparison. During 1993
1995, Garmouma and Poissant (2004) investigated the g-HCH air concentrations along the St. Lawrence River in QC and the mean level in St. Anicet ranged from 71 to 131 pg m
3. The main lindane source in QC was its usage as corn seed dressing. Poissant and Koprivnjak (1996) estimated that about 4 t of lindane was used for corn seeding in the province. During the CANCUP study, a-HCH air concentrations were also measured. The obtained a-HCH/g-HCH ratios were 1.4, 2.6, o0.1, 0.8 and 4.6 for Abbotsford, Egbert, St. Anicet, Baie St. Francois and Kensington, respectively. These ratios are lower than technical HCH formulation (5–7), indicating fresh inputs of g-HCH. Concentrations of g-HCH at Bratt’s Lake (171 pg m
3) and Hafford (141 pg m
3) in the Prairies were higher than for any of the CANCUP sites, even though no application occurred there in 2003. This indicates that residual lindane remaining in prairie agricultural land continued to be an important source. 3.2.3. Herbicides Atrazine and dicamba: Atrazine was only detected in a few air samples. The observed monthly average concentrations were relatively low (ND–51 pg m
3) in which the highest level was found at Abbotsford (Fig. 4(c)). Long-term air monitoring data from IADN have shown a spring maximum linked to its application in the Great Lakes basin (IADN, 2002). As mentioned previously, the 2003 CANCUP air sampling began after the spring growing season. Considering the fact that atrazine is generally applied to soil before emergence, but is also sometimes applied to the foliage after emergence, our results are thought to reflect some postemergence applications. Although it is commonly used across the country, dicamba was only detected at QC and ON sites. The observed monthly average air concentrations ranged from 7.2 to 73 pg m
3. These results are lower than that measured at Bratt’s Lake (184 pg m
3) (Fig. 4(c)). Current

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pesticide sales/use data are not available in SK, but Waite et al. (2004) reported around 4400 t of herbicides including bromoxynil, dicamba, diclofop, MCPA and trifluralin were used in SK in 1990. Donald et al. (1999) estimated that dicamba use represented about 6% of total herbicide use in SK in 1996. Based on the assumption that the similar quantities of herbicides and relative use percentage of dicamba occurred in 2003, the annual dicamba usage in SK is estimated to be 264 t. This value is greater than in any other province (Brimble et al., 2005), supporting the observation mentioned above. Trifluralin and ethalfluralin: Trifluralin was detected in air across the country in the range of 6.2
91 pg m
3. These levels are lower than that observed at Bratt’s Lake (170 pg m
3) (Fig. 4(c)). Using the same approach described earlier for dicamba, the trifluralin use in SK is estimated to be 132 t a.i. y
1 based on a relative use percentage of 3% (Donald et al., 1999). This annual usage is approximately 8 times larger than in ON (17 t a.i. y
1). Ethalfluralin was only found at Kensington under CANCUP and the observed air concentration (71 pg m
3) is also lower than that measured at Bratt’s Lake (115 pg m
3). Ethalfluralin is widely used in the Prairies (AB: 452 t a.i. y
1 and MB: 144 t a.i. y
1) (Brimble et al., 2005). Metolachlor and alachlor: Metolachlor was detected in air samples collected in QC, ON and PEI, in which the highest monthly average concentration was found at St. Anicet (480 pg m
3) (Fig. 4(d)). Alachlor is not used in Canada but is used in the United States (Muir et al., 2004) with an annual usage of 6–9 million pounds (2700–4050 t) a.i. in 2001 (Kiely et al. 2004). Alachlor was detected in air samples collected at all sites except Kensington. The monthly average concentrations ranged from 31 to 665 pg m
3. Highest levels were measured at Egbert (Fig. 4(d)) where air concentrations varied greatly from week to week. For instance, alochlor concentrations were 80–178 pg m
3 during 22 July–5 August and then increased sharply to 1230 pg m
3 during 5–12 August and remained at the same level in the following week. These phenomena are probably related to episodic LRT. Muir et al. (2004) previously studied the LRT potential of alachlor and found it in remote mid-latitude and Arctic lakes with mean concentrations of 0.91 and 0.02 ng L
1, respectively. 3.2.4. Legacy OCPs Although the present project focuses on CUPs in the atmosphere, banned OCPs were also investi-

4349

gated for CANCUP samples. DDT, HCB, chlordane, dieldrin, and a-HCH were found with no detection of heptachlor, aldrin, endrin, and mirex. The results are presented in Table 3. DDT and DDE: Due to its negative effect on the ecosystem, DDT, one of the first OC insecticides, was banned in the United States in 1972 and Canada in 1973. Technical DDT consists of p,p0 DDT and o,p0 -DDT in a ratio of approximately 6.7. In the environment, DDT isomers are converted to DDE and DDD, the p,p0 -DDT/p,p0 -DDE ratio can used as an indicator for determining the ‘‘age’’ of DDT (o1: aged DDT; 41: fresh inputs) (Harner et al., 2004). DDT and DDE were found in air at almost all sites with no detection of DDD (Fig. 4(e)). The SDDT (p,p0 -DDT+o,p0 -DDT) and SDDE (p,p0 -DDE+o,p0 -DDE) ranged from ND to 166 and from 10 to 67 pg m
3, respectively. The highest concentrations of SDDT and SDDE were measured at Abbotsford. For the other four sites, the p,p0 -DDT/p,p0 -DDE ratios were less than 1, suggesting that DDT residues had been degrading for a long time in these regions. Compared to previously reported SDDT and SDDE levels at Egbert (93 and 305 pg m
3 in July–October 2000) (Harner et al., 2004), our results (47 and 30 pg m
3) were lower. Dieldrin: Dieldrin was widely used on crops like corn and cotton. The United States deregistered this chemical in 1987 and now it is banned from use throughout North America. The occurrence of dieldrin in the atmosphere is due to revolatilization from previous use of dieldrin and/or aldrin, which converts to dieldrin in the environment. This compound was found at most sites in the range of 7.2
72 pg m
3, in which the highest level was observed at Abbotsford (Fig. 4(e)). Our observation (36 pg m
3) at Egbert is approximately half that (76 pg m
3) reported by Harner et al. (2004) at the same site during the summer to fall of 2000. HCB: Although the use of HCB as fungicide was banned in the United States, Canada and some European countries in 1970s, it is still present as an impurity in some pesticides. Additionally, this compound can be formed during combustion processes. HCB was detected in all air samples (Fig. 4(f)) and was uniformly distributed with concentrations ranging from 51 to 81 pg m
3. Meijer et al. (2003) reported a mean ambient air concentration of 58 pg m
3 for HCB in the summer of 2000 at a soybean field in southern ON.

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Chlordane: Technical chlordane consists of transchlordane (TC) and cis-chlordane (CC) in a ratio of about 1.3, mixed with many related chemicals. It was used on crops like corns and citrus and on home lawns and gardens. In North America, although use of chlordane was phased out in the United States and Canada by 1995, Mexico continued usage until 2003. TC and CC were detected in air at ON, QC and PEI sites in the range of 1.3
10 and ND
7.2 pg m
3, respectively (Fig. 4(f)). TC and CC air levels (pg m
3) of 8.2 and 11 were reported in an agricultural region in southern ON in 2000 (Meijer et al., 2003). In the environment, TC degrades more quickly than CC resulting in a TC/CC ratio less than 1. The TC/CC ratio observed at Kensington was 0.6, indicating aged chlordane. For the Egbert site, the obtained TC/CC ratio was 1.1, indicating that air concentration pattern is similar to the technical grade. In addition, this value is similar to those previously reported for air samples collected at urban sites in Toronto (Harner et al., 2004). Relatively ‘‘recent’’ use of chlordane on lawns and house foundations in Toronto, a major city about 75 km to the south may be a source to this region. a-HCH: a-HCH was detected at all sites except St. Anicet, with air concentrations ranging from 27 to 48 pg m
3 (Fig. 4(f)). The presence in the atmosphere is related to its revolatilization and environmental persistence. Buehler and Hites (2002) calculated a half-life of approximately 4 y for aHCH in the air near the Great Lakes. Bidleman et al. (1995) pointed out a significant decline of aHCH in the arctic atmosphere during 1979
1993. The IADN monitoring program also shows a clear decrease in a-HCH air concentration since 1991 (Buehler and Hites, 2002). Compared to previous aHCH air data at Egbert (62 pg m
3) (Harner et al., 2004), our observation for the site (46 pg m
3) is lower, further supporting the a-HCH gas-phase decreasing trend mentioned above. 4. Conclusions The 1st year of the CPASC revealed the spatial and temporal trends of CUPs in the Canadian atmosphere during the spring to summer of 2003. Results for individual pesticides generally agree with their use patterns in the investigated regions. For older pesticides that were detected, air burdens in Canada are attributed to volatilization of residues associated with historic use and/or atmospheric

transport from other source regions. The measurements obtained here represent a first step in characterizing the atmospheric distribution and fate of CUPs across Canada. Air sampling efforts under CPASC in subsequent years will be coordinated to capture events of peak pesticide usage in each region. Additional sites will be included and the target pesticide list will be expanded according to analytical capabilities. Future work will assess longrange atmospheric transport issues associated with CUPs and legacy OCPs. First, as it relates to transboundary inputs from sources in the United States and elsewhere. Secondly, in relation to sources within Canada and how these impact receptor regions and relate to levels in other environmental media—water, soil and biota. Acknowledgements This work was supported by the EC Pesticide Science Fund (PSF). We are also grateful to Jim Sproull, Art Cook, Renata Bailey, Frank Froude, Helena Dryfhout-Clark, Martin Pilote, Conrad Beauvais, Chris Marvin, Christine Garron, Young Ryu, Phil Fellin, and Henrik Li for their assistance with sample collection and analysis. References Aulagnier, F., Poissant, L., 2005. Some pesticides occurrence in air and precipitation in Que´bec, Canada. Environmental Science and Technology 39, 2960–2967. Belzer, W., Evans, C., Poon, A., 1998. Environment Canada. Atmospheric concentrations of agricultural chemicals in the lower Fraser Valley. Fraser River Action Plan. DOE FRAP 1997-31. Bidleman, T.F., Jantunen, L.M., Falconer, R.L., Barrie, L.A., 1995. Decline of hexachlorocyclohexane in the arctic atmosphere and reversal of air–sea gas exchange. Geophysical Research Letters 22, 219–222. Blanchard, P., Audette, C.V., Hulting, M.L., Basu, H., Brice, K.A., Chan, C.H., Dryfhout-Clark, H., Froude, F., Hites, R.A., Neilson, M., 2000. Environment Canada—US EPA. Atmospheric deposition of toxic substances to the Great Lakes: IADN results through 2000. http://www.msc.ec.gc.ca/ IADN; www.epa.gov/glnpo/monitoring/air/iadn/iadn.html. Brimble, S., Bacchus, P., Caux, P.-Y., 2005. Environment Canada. Pesticide utilization in Canada: a compilation of current sales and use data. Report for the Environment Canada Pesticide Program Coordinating Committee. Buehler, S.S., Hites, R.A., 2002. The great lakes’ integrated atmospheric deposition network. Environmental Science and Technology 36, 354A–359A. Donald, D.B., Syrgiannis, J., Hunter, F., Weiss, G., 1999. Agricultural pesticides threaten the ecological integrity of northern prairie wetlands. Science of the Total Environment 231, 173–181.

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