A review of currently used pesticides (CUPs) in Canadian air and precipitation. Part 2: Regional information and perspectives

A review of currently used pesticides (CUPs) in Canadian air and precipitation. Part 2: Regional information and perspectives

ARTICLE IN PRESS Atmospheric Environment 40 (2006) 1579–1589 www.elsevier.com/locate/atmosenv A review of currently used pesticides (CUPs) in Canadi...

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ARTICLE IN PRESS

Atmospheric Environment 40 (2006) 1579–1589 www.elsevier.com/locate/atmosenv

A review of currently used pesticides (CUPs) in Canadian air and precipitation. Part 2: Regional information and perspectives Ludovic Tuduria, Tom Harnerb,, Pierrette Blanchardb, Yi-Fan Lib, Laurier Poissantc, Don T. Waited, Clair Murphye, Wayne Belzerf E´quipe Pe´rigourdine de Chimie Applique´e, Laboratoire de Physico-toxicochimie des syste`mes naturels, Universite´ Bordeaux I, BP 1043, 24001 Pe´rigueux cedex, France b Science and Technology Branch, Environment Canada, 4905 Dufferin Street, Toronto, Ont., Canada, M3H 5T4 c Processus atmosphe´riques des toxiques, Service me´te´orologique du Canada, Environnement Canada, 105 rue McGill, Montre´al, Que´., Canada, H2Y 2E7 d Environment Canada; 300-2365 Albert Street, Regina, Sask., Canada, S4P 4K1 e Environment Canada, Room 202, 97 Queen Street, Charlottetown, PEI, Canada, C1A 4A9 f Environment Canada, 201-401 Burrard Street, Vancouver, BC, Canada, V6C 3S5 a

Received 27 July 2005; received in revised form 23 October 2005; accepted 9 November 2005

Abstract This paper, and its companion (that dealt with lindane and endosulfan) review available data on the presence of currently used pesticides (CUPs) in air and precipitation in Canada, since the late 1980s. Pesticides usage/sales are also given when available. Data from local studies/initiatives, region-wide monitoring networks and remote locations are compiled to summarize atmospheric levels of different CUP classes (e.g. acid herbicides, organophosphates, ‘‘new’’ organochlorines, triazines, etc.) and how this varies among regions and with time. Based on this information, and other parameters not specific to Canada, knowledge gaps are identified and ideas for further research work are proposed. r 2005 Elsevier Ltd. All rights reserved. Keywords: Pesticides; Atmosphere; Precipitation; Deposition; Canada; Pesticides sales

1. Introduction It is now accepted that following application pesticides can enter the atmospheric compartment and travel many kilometers. This is not only true for the older and more persistent pesticides (e.g. lindane, chlordane, DDTs), but also for newer, current-use pesticides (CUPs). For example, Corresponding author. Tel.: +1 416 739 4837; fax:+1 416 739 5708. E-mail address: [email protected] (T. Harner).

1352-2310/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.atmosenv.2005.11.020

dacthal, chlorothalonil, chlorpyrifos, metolachlor, terbufos and trifluralin have been detected in Arctic environmental samples (air, fog, water, snow) by Rice and Cherniak, (1997), and Garbarino et al. (2002). Other studies have identified the ability of some of these compounds to undergo short-range atmospheric transport (Muir et al., 2004) to ecologically sensitive regions such as the Chesapeake Bay and the Sierra Nevada mountains (LeNoir et al., 1999; McConnell et al., 1997; Harman-Fetcho et al., 2000, Thurman and Cromwell , 2000). Contrary to the more persistent

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2. British Columbia (BC) and Pacific region In 1999, 8102 tonnes of pesticides active ingredients were sold in BC, excluding most domestic labels (Verrin et al., 2004); 86.5% of these pesticides were anti-microbial chemicals (wood preservatives and anti-sapstain chemicals), 4.9% insecticides and 3.3% of herbicides. 86.3% of the reportable pesticides (reportable pesticides in BC are products that have a restricted or commercial use label, including pesticides used for agriculture and industrial applications) were sold in the lower mainland and the southern interior, where most of the population resides (Census 1996). In the Yukon, ‘‘small quantities’’ (Government of Yukon, 2003) of pesticides are sold. This includes diazinon, chloropyrifos, borax, allethrin, pyrethrins and Bacillus thuringiensis (BT). Herbicides primarily used include glyphosate, 2,4-D, mecoprop and dicamba. Wood preservatives that are distributed as ready-to-use paint on formulations include creosote, zinc naphthenate, and copper naphthenate. Less than 2% (i.e. 12,370 ha) of the Yukon is suitable for agriculture (Hill et al., 2002a, b).

To our knowledge, there has been only one long term study that investigated pesticides in the atmosphere of BC, dating from 1996 (Belzer et al., 1998). In all, 57 chemicals were investigated at two sampling sites (Agassiz and Abbotsford) in the Fraser Valley, from February 1996 until March 1997. The overall weekly averaged concentrations peaked in mid-June to mid-July at both sites, even though an early peak of 2,4-D was particularly high at the end of February in Agassiz (15.7 ng m 3). Most of the pesticides were detected in the weekly average air samples immediately after they were applied. Atrazine concentrations peaked at 14.5 ng m 3 in Agassiz during 18–25 June, and were detected until the end of July (1.9 ng m 3). Malathion was also detected at this site from mid-June (3.4 ng m 3) until the end of July (1.7 ng m 3). In Abbotsford, diazinon, a highly toxic chemical identified as a high-priority pesticide by Verrin et al. (2004), was detected as early as the end of February (72 pg m 3) until mid-October 3 (253 pg m ), with a peak concentration in midJune of 42.7 ng m 3. Chlorpyrifos was quantified from early July (303 pg m 3) until the end of October (753 pg m 3), with a maximum of 1.5 ng m 3 at the end of September. A wide peak application pattern was observed for Captan, a chlorinated sulfenimide fungicide. Its uses include a pre-planting soil fungicide, a pre-harvest protective treatment, particularly for foliage and fruits, and a post-harvest dip for fruits and vegetables (http://www.inchem.org). In 1999 27.5 tonnes were sold (Enkon Environmental Limited, 2001). Captan was first detected in early April (263 pg m 3), peaked in mid-July (6.5 ng m 3) and then decreased to 253 pg m 3 in mid-October, as shown in Fig. 1. Dichlorvos, an organophosphate insecticide, was detected throughout the year. It was first detected at 8

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pesticides, biomagnification is not the major problem, even though this has been shown to occur (e.g. as shown by the detection of organophosphates (OPs) in several aquatic organisms from the Mediterranean Sea (Barcelo et al., 1990)). Because they are relatively soluble in water and their toxicity is not specific to a target pest, OPs can enter the aquatic environment and potentially harm vertebrate and non-vertebrate animals (Tse et al., 2004). Atmospheric data for these CUPs are relatively sparse in the literature. To strengthen our knowledge of these chemicals and their behaviour in the environment, an air surveillance program was initiated in 2003 in Canada. This network, referred to as Canadian Atmospheric Network for Current Use Pesticides (CANCUP) is providing new information on CUPs in the Canadian atmosphere and precipitation (Tuduri et al., 2004). As a starting point, a two-part review of the available literature on CUPs in air and precipitation in Canada was performed over the period 1980 to present. Whereas part 1 was focused on endosulfans and lindane, which are widely investigated in Canada, part 2 deals with other CUPs on a region-by-region basis. Knowledge gaps are identified and ideas for future research work are highlighted.

concentration (ngxm )

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dichlorvos captan

6

4

2

0 0

30

60

90

120

150 180 210 Days, year 1996

240

270

300

330

360

Fig. 1. Dichlorvos and Captan concentrations in air at Abbotsford during 1996.

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Abbotsford during the second week of February (1.0 ng m 3), then in almost all air samples from the 1 yr program at similar concentrations (0.2–2 ng m 3, Fig. 1) with concentrations peaking in July at 6.6 ng m 3. Dichlorvos was also detected in Agassiz, at higher peak concentrations (10.7 ng m 3) but no clear trend was observed. This insecticide has a higher vapor pressure than most other organophosphates (2.1 Pa at 25 1C, versus 0.012 Pa for diazinon, Tomlin, (2000)) and is also formulated into insecticidal strips which are used in insect traps. This could explain its lack of a clear peak post-application. Dichlorvos is also a decomposition product of another pesticide, naled (Hall et al., 1997). Compared to air data, fewer pesticides were detected in precipitation—seven at Agassiz and six at Abbotsford. Captan and 2,4-D showed the highest concentrations and deposition rates at these two sites, followed by dichlorvos and diazinon. 3. Prairies In the Prairies, pesticides sales data are only available for Alberta. This is a significant gap since more pesticides are used in the prairies (Alberta, Saskatchewan and Manitoba) than in any other region of Canada (Statistics Canada). The major use is agricultural and is dominated by herbicides (North/South Consultants, 2003). During the late 80 s, 20,000 tonnes of herbicides per year were used in these three provinces and, approximately, half of that for Saskatchewan (personal communication). More recent figures for Alberta showed that phosphonic+phosphinic acids (glyphosate, glufosinate) and phenoxy acids (2,4-D, MCPA) represented 29.9% and 18.7% of the total pesticides sales (9300.5 tonnes) in 1998 (Byrtus, 2000). The most widely used herbicides in Saskatchewan were (in decreasing order)—ethalfluralin, glyphosate, MCPA, 2,4-D and bromoxynil (North/South Consultants, 2003). In Manitoba, highest use was for glyphosate, followed by MCPA, bromoxynil, 2,4-D and ethalfluralin. The Manitoba Crop Insurance Company estimated total use of priority herbicides in Manitoba at 1747 tonnes in 2001. It is not surprising that most of the reported atmospheric data for the prairies are for herbicides. Much of the older data are reported in a text on the environmental chemistry of herbicides (Grover and Cessna, 1991) that deals mainly with studies in Saskatchewan, a major use area (Grover et al., 1986; Grover et al., 1976). The results are also summarized in a

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second book (Dosman and Cockcraft, 1989). These data will not be presented here. The fate of pesticide mixtures applied to crops was also investigated in Saskatchewan in the mid-1980s (Grover et al., 1988, 1994). 3.1. Air concentrations Air concentrations of CUPs in Alberta were investigated in 1999 at four sampling sites that were chosen according to geography and pesticide sales data (Kumar, 2001). Later, Hill et al. (2001) used some of these same sites during a study of CUPs in precipitation (see Section 3.2). Triallate and trifluralin were the two most detected pesticides at the four sites. At Lethbridge, the closest site to agricultural activities, trifluralin was detected from April until November, with concentrations ranging from 10 to 70 pg m 3. Ethalfluralin was detected from April until October, with a peak concentration of 810 pg m 3. Acid herbicides (2,4-D, bromoxynil, MCPA and dicamba) were detected sporadically at all four sites (Table 1). Pentachlorophenol was also detected during all sampling seasons, with a peak for pentachlorophenol at the most remote site (Lundbreck) during September at 2.82 ng m 3. Insecticides (malathion, chlorpyrifos, diazinon and endosulfan) were detected intermittently with concentrations in the range 20–780 pg m 3. South of Regina, Saskatchewan, in 1989 and 1990, 2,4-D reached 3.9 and 3.6 ng m 3 at the end of June (Waite et al., 2002a). This peak was followed by a progressive decrease and, at the end of August, 2,4-D was no longer detected. Triallate peaked in May at 60.0 ng m 3 in 1989 and 22.8 ng m 3 in 1990, and was still detected in September. Dicamba peaked at 3.7 ng m 3 in midJune, 1989, and at 700 pg m 3 in 1990. Even though it was applied in the vicinity of the sampling site, MCPA was detected only once in mid-June 1989, below 500 pg m 3, and not detected at all in 1990 (Waite et al., 2004). For bromoxynil, concentrations were also higher in 1989 (peak concentration of 4.2 ng m 3 in mid-June) compared with 1990 (600–700 pg m 3 in mid-June). Trifluralin did not show peak concentrations corresponding to application, but levels were also higher in 1989 than in 1990. In 1994, Regina, 2,4-D and dicamba concentrations during the agricultural season were lower than observed previously, with values in the range 72–390 and 28–105 pg m 3 (Waite et al., 2002b).

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Table 1 Air concentrations for selected herbicides in the Prairies Sampling site

AB

Year

Lundbreck Lacombe Lethbridge

South Regina Regina Bratt’s Lake Hafford Waskesiu

MB

South Tobacco Creek

Ref

2,4-D

Dicamba

Bromoxynil

Triallate

10 100

60 50

80 180 300

1100 1070 1070

200

740

4200 700

60000 22800

1400 1340 1530 500

5070 5460 200 80

1999

Vegreville SK

Air concentration (pg m 3)

360 1989 1990 1994 2002 2002 2002 2002

3900 3600 390 520 1260 2730 190

1996

3500

In a more recent study, Waite et al. (2005) studied spatial variations of selected herbicides on a threesite, 500 km transect that included two agricultural sites—Bratt’s Lake, located 35 km southwest of Regina and Hafford to the North—and a background site at Waskesiu, 500 km North of Regina and 50 km North of farmlands. Metolachlor, alachlor, and atrazine, seldom applied in the prairies, were detected at low concentrations in 10–18% of the samples collected between May and July of 2002, pointing to atmospheric transport from the US. Ethalfluralin was also sporadically detected. Lower concentrations of all herbicides were detected at Waskesiu. Peak concentrations of 2,4-D, bromoxynil, MCPA and dicamba were measured during the week of July 3 at Bratt’s Lake, Regina and Hafford. At Hafford, concentrations were respectively 2.73, 1.53, 1.88 and 0.17 ng m 3 for these compounds. Triallate peaked at 5.46 ng m 3 in mid-June at Bratt’s Lake, and the authors suggested that there were sources of triallate in the southern part of Saskatchewan. They calculated that maximum loadings in the prairies atmosphere, represented by a hemi-ellipsoid of radii 300 km (North–South direction) and 700 km (East– West direction) and 1 km height. Loadings were 75 kg for trifluralin in the week of 5th June, and 541 kg for 2,4-D in the week of 3rd July. Some acid herbicides were also investigated in South Tobacco Creek, Manitoba during 1993–1996.

3700 700 105 1120 560 170 120

Kumar, 2001

Waite et al., 2002a, 2004 Waite et al, 2002b

2520

Waite et al., 2005

Rawn et al., 1999a

Once again, maximum concentrations occurred during periods of local use (Rawn et al., 1999a). During the first 3 yr of the study, 2,4-D, MCPA, bromoxynil and dichlorprop concentrations were below 350 pg m 3. In 1996, MCPA peaked at 13.1 ng m 3, 2,4-D at 3.5 ng m 3, to fall a few days later below 100 pg m 3. Bromoxynil was the most frequently detected herbicide in the samples from year to year. Highest concentrations occurred in 1996, peaking at 2.52 ng m 3. A neutral herbicide, atrazine was also investigated in 1995 (Rawn et al., 1998). It was first detected mid-April, peaked midJune at about 300 pg m 3, and was detected until the end of October. The insecticide dacthal was identified throughout the sampling periods in 1994, 1995 and 1996 (Rawn and Muir, 1999) even though it was not used in this area (o20–300 pg m 3). In contrast, chlorpyrifos was identified only when local application occurred, at much higher concentrations (10–103 ng m 3). 3.2. Deposition A study of herbicides in Alberta rainfall was initiated in 1999 and 2000 by Hill et al. (2001, 2002) at 17 locations, representing remote areas, cities and the vicinity of application sites. After collecting samples on a precipitation event basis from April to late September, they detected the highest amounts (in order) for 2,4-D, MCPA, bromoxynil, and

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dicamba. They were, respectively, detected in 68.1%, 32,7% 40.2% and 50.6% of the 251 collected samples in 2000. 2,4-D levels were the highest in Southern Alberta (total of 315 mg m 2 during the 1999 sampling season in Champion, with a peak of 149 mg m 2 in 2000 at Tempest), while in Central Alberta it was MCPA (total of 171 mg m 2 and peak of 149 mg m 2 in 2000 at Three Hills). Total dicamba deposition was slightly higher in Lethbridge (10–11 mg m 2) than in remote areas (5.2–9.5 mg m 2) and higher than in Central Alberta (4.7–8.6 mg m 2) in 1999. During May–August 2001, Hill et al. (2003) extended their sampling program to locations in Saskatchewan (Regina, Swift Current and Southey, southern part) and Manitoba (Minnedosa, southwestern part). Once again, for Alberta but also Saskatchewan and Manitoba, 2,4-D, bromoxynil, MCPA and dicamba comprised the majority of sample detections (Hill et al., 2003). Total seasonal deposition for 2,4-D was highest in Tempest (213 mg m 2) followed by Regina (141 mg m 2). Bromoxynil was higher in Regina and Swift Current (44 and 31 mg m 2) than in Tempest (25 mg m 2). In general, total deposition (four herbicides mentioned earlier) during the sampling season was highest in Tempest, followed by Regina and Swift Lake and then Minnedosa. Some other deposition studies have been launched in the prairies, especially in Saskatchewan. Results from those studies are highlighted in Table 2. Using a different precipitation sampler allowing distinct determination of dry and wet deposition (Cessna et al., 2000), Waite et al. (1995) calculated similar total deposition for 2,4-D in Regina during the agricultural season, i.e. from 38.6 mg m 2 in 1986 to 137.4 mg m 2 in 1985. On the contrary, bromoxynil deposition determined by Waite et al. in 1984–1987 (9.0–23.4 mg m 2) in Regina was lower than the value reported by Hill et al. (see above) for Regina. For dicamba, however, values were similar (2.0–21.9 mg m 2 in 1984–1987 versus 3–15 mg m 2 in 2000–2001). In 1989 (Waite et al, 2002a, 2004), near Regina, seasonal total deposition was 100.3 mg m 2 for 2,4-D, 16.4 mg m 2 for dicamba, 10.8 mg m 2 for bromoxynil and 23.8 mg m 2 for MCPA. Peak deposition rates occurred for all the above herbicides in mid-June, while higher deposition rates occurred in late May for triallate (Waite et al., 1995, 2002a). Later, Waite et al. (1999) developed a new precipitation collector able to separate wet deposi-

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tion from dry deposition. Total dry deposition rates during the sampling season were 17.3 and 4.6 mg m 2, respectively, for 2,4-D and dicamba in Regina, 1994 (Waite et al., 2002b). In 2003, 9 yr later, similar seasonal deposition was determined at Bratt’s Lake (Tuduri et al., 2004). In their final technical report, Hill et al. (2001) pointed out that dry deposition (dust) contributed little to the overall bulk (wet+dry) deposition rates. They also compared their precipitation collector results with a more conventional automated wetonly precipitation sampler. Deposition rates obtained from their sampler were on average nine times higher than the conventional one, suggesting that the delay period in the automated opening of the cover does not capture the deposition pulse of herbicides that are associated with the initial rainfall. This confounds the interpretation and comparison of results from studies using different types of precipitation samplers. Using such an automated precipitation sampler, Rawn et al. (1999a) reported seasonal deposition rates of about 5.8–21.2 mg m 2 for bromoxynil and 1.4–32.0 mg m 2 for 2,4-D in a small agricultural watershed in southern Manitoba during 1993–1996. Higher levels of 2,4-D, bromoxynil and MCPA in the creek water coincided with high deposition rates in 1994 and 1996 (Rawn et al., 1999b). Nevertheless, these rates for agricultural areas are below values published by Hill et al. (2003) (Alberta and Saskatchewan) and Waite et al. (2002a, 2004) (Saskatchewan) using a different precipitation sampler (see text above and Table 2). However, these rates are in the same range of values published by Hill et al. (2003) for a different Manitoba site in the same area (21 mg m 2 for bromoxynil and 68 mg m 2 for 2,4-D in 2001). Atrazine deposition through medium- or longrange transport was also studied in this southern Manitoba watershed (Rawn et al., 1998). Although it was not used in the area for 5 yr, the total seasonal wet deposition values were 17.2 mg m 2 in 1994 and 1.3 mg m 2 in 1995, representing 90% and 43% of the total atmospheric loading to the watershed. Dacthal, another herbicide which was not used in the area, had seasonal wet deposition of 0.4–3.8 mg m 2 during 1994–1996 (Rawn and Muir, 1999). Chlorpyrifos, an in-use insecticide, showed wet deposition of 45 mg m 2 in 1994 and 1.9–2.4 mg m 2 in 1995–1996. Estimated dry depositions were considered minor for these two pesticides. Loading results for these three pesticides are detailed in Rawn et al. (1998) and Rawn and Muir (1999).

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Table 2 Deposition rates for selected ‘‘acid’’ herbicides in the Prairies Sampling site

SK

AB

MB

Regina

Year

Deposition

Seasonal deposition rate (mg m 2)

Ref.

2,4-D

Dicamba

Bromoxynil

MCPA

78.8 137.4 38.6 118.2 100.3 40.2 17.3 93 141

21.9 19.0 6.2 2.0 16.4 1.3 4.6 15 3

23.4 9.4 9.0 10.4 10.8 4.3

23.8 5.8

70 44

99 46

1984 1985 1986 1987 1989 1990 1994 2000 2001

Bulk

Bratt’s Lake

2002 2003

Dry Dry

21.7 20.4

9.7 15.6

20.6 9.1

25.5 68.4

Waite et al., 2005 Tuduri et al., 2004

Swift Current

2000 2001

Bulk

129 90

74 21

52 31

47 33

Hill et al., 2002, 2003

Champion

1999 2000

Bulk

315 300

27 47

38 59

13 58

Three hills

1999 2000

Bulk

61 85

8.6 5.5

45 87

65 171

Lethbridge

1999 2000

Bulk

82-93 101-109

10-11 6.8-6.9

13-20 22-25

10 33-40

Tempest

1999 2000 2001

Bulk

139 261 213

16 32 6

28 65 23

18 71 49

Minnedosa

2001

Bulk

68

12

21

70

Hill et al., 2003

South Tobacco Creek

1993 1994 1995 1996

Wet

1.4 6.8 32.0 20.5

11.1 21.2 20.3 5.8

1.9 50.3 45.2 36.0

Rawn et al., 1999a

Bulk Dry Bulk

4. Saint Lawrence plains–Great Lakes basin In Ontario, pesticide use has been reduced by 52% since 1983, to remain at 4200 tonnes in 2003 (AGcare, 2004). In 2000, 3398 tonnes of pesticides were sold in Quebec, a 9.5% decrease from 1992 (Gorse, 2004). Of the sales, 77.9% were used for agricultural purposes. 53.9% of these sales were herbicides. Sales are not reported by active ingredient in Quebec, like in Alberta, but by chemical group, class of pesticides and type of use. Ten pesticides comprised 48.5% of sales in 2000. In Ontario, a few studies have dealt with CUPs in the atmospheric compartment. From April 1991 until September 1992, Hall et al. (1993) sampled monthly precipitation at 17 locations around the Great Lakes. Averaged concentrations across all

Waite et al., 1995

Waite et al, 2002a, 2004 Waite et al., 2002b Hill et al., 2003

sites showed that atrazine was detected from April to September in 1992. Peak concentrations were 250 ng L 1 in June 1991 and 445 ng L 1 in May 1992. Background concentrations for metolachlor were 50 ng L 1. It peaked in May 1991 at 322 ng L 1, and 244 ng L 1 the following year. Concentrations of atrazine in precipitation in a more remote site (experimental lakes area, ELA) in 1995 were in the range 0.9–18.4 ng L 1, higher levels being detected during the application season. The maximum air concentration was 90 pg m 3. A 5 d back-trajectory analysis showed a probable influence from use regions to the South (Rawn et al., 1998). This is in agreement with the higher concentrations (o100–40 000 ng L 1) in Iowa reported by Nations and Hallberg (1992). On Isle Royale National park (Lake Superior, US–Canada

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border), atrazine was detected (the triazine herbicide cyanazine as well) from mid-May until mid-July in 1992–1994, at typical concentrations of 0.1–0.5 mg L 1 (Thurman and Cromwell, 2000). When rainfall amounts were less than 1 mm, concentrations were higher and reached 1.8 mg L 1. Air parcel back trajectory analysis also demonstrated that atrazine was transported from the midwestern corn belt (Minnesota, Iowa and Wisconsin). Goolsby et al. (1997) calculated that the annual wet deposition of atrazine in 1990 and 1991 ranged from 3640 kg in Lake Michigan to 470 kg in Lake Ontario. This can be compared with yearly precipitation loadings of 2600 kg over 1991–1994 calculated by Schottler and Eisenreich (1997), and 1040 kg in 1994–1995 for Lake Michigan calculated by Miller et al. (2000). Atrazine has also been adopted as a pilot study compound, to be monitored at the three IADN sampling sites in Ontario. Fig. 2 show the seasonal cycle of this compound, from January 1996 until December 1999 in Egbert, near a corn cultivation area. A clear peak is seen each year during May–June (e.g., 2160 pg m 3 on May 1997). For comparison, the concentration profile for lindane is also shown in Fig. 2. Atrazine usage in Ontario has remained fairly constant between 1993 and 1998 at about 574 tonnes yr–1. In 2003, 499 tonnes were used, mostly on corn. In Quebec, 332.7 tonnes of triazines and tetrazines were used in 2000, down from 542.5 tonnes in 1992. Its use was recently banned in several European countries (http:// www.pesticideinfo.org). Chlorothalonil and dacthal, two chlorinated pesticides, were investigated in air and precipitation 600

3500 atrazine lindane

500

2500 400 2000 300 1500 200

lindane (pgxm-3)

atrazine (pgxm-3)

3000

1000 100

500

0 8 8 7 9 7 9 9 7 9 7 9 9 7 7 8 8 8 8 99 99 99 99 99 99 99 99 99 99 99 99 99 99 99 99 99 99 /1 3/1 5/1 7/1 9/1 1/1 1/1 3/1 5/1 7/1 9/1 1/1 1/1 3/1 5/1 7/1 9/1 1/1 1 /0 /0 /0 /0 /0 /1 /0 /0 /0 /0 /0 /1 /0 /0 /0 /0 /0 /1 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04

0

date

Fig. 2. Atrazine and lindane concentrations in air at Egbert, January 1997 to December 1999.

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samples from different US IADN sampling sites, during 1995–1996 (James and Hites, 1999). Dacthal was identified at concentrations at 20–50 pg m 3 in air and 0.4–7 ng L 1 in precipitation. Chlorothalonil was only detected in air samples at 30–100 pg m 3. These two pesticides were also investigated at the three Ontarian IADN sampling sites, and some preliminary results for year 1997 were given by Blanchard et al. (2004). Chlorothalonil peaked at 730 pg m 3 in August, 1997 at Point Petre. Dacthal was detected more often at Burnt Island than Point Petre, but concentrations peaked at 130 pg m 3 in Point Petre and 15 pg m 3 at Burnt Island. This is well below 5.2 ng m 3 quantified by Tuduri et al. (2004) as a monthly average at Egbert, Ontario and 3.0 ng m 3 at Saint Anicet, Quebec, in July 2003. 5. Atlantic region A review on pesticide use (sales), research and monitoring in Nova Scotia, New Brunswick and Prince Edward Island was recently released (Cantox Environmental, 2003). In Nova Scotia, the greatest sales (2000–2002) were attributed to glyphosate (agriculture, forestry and lawncare) which far exceeded some acid herbicides (2,4-D, mecoprop and dicamba) followed by fungicides Captan, metalaxyl and insecticides carbaryl and azinphosmethyl. No sales volumes were available. New Brunswick reported that 583 tonnes of pesticides were sold in 2001, a 42.7% increase from 1999 (408 tonnes). The biggest increase was for fungicides (374 tonnes,+70%, chlorothalonil and mancozeb representing 84.8% of the fungicides sales) and insecticides. In PEI, 786 tonnes of pesticides were sold. Chlorothalonil and mancozeb accounted for 76.2% of all pesticides sales. Between 1993 and 2001, insecticides sales decreased by 59.7%, due to the adoption of integrated pest management techniques. Sales of fungicides increased by 59.6%, due to an increase in potato production, a crop which is known to be highly dependant on fungicides, and an increase in preventive applications to combat blights. In the 1980s–1990s, a network of precipitation sampling stations was set up across Nova Scotia, New Brunswick, Prince Edward Island and Newfoundland. Preliminary results were recently presented (Brun and Le´ger, 2001), and a more detailed report should follow. Apart from a- and g-HCH, chlorothalonil was the most detected pesticide, reported in 41.1% of samples. Pentachlorophenol

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A review of available information on CUPs in the air and precipitation of Canada since 1980 has led to several insights and identified priority areas for further study:

(2) For CUPs that are detected, it is not always clear if their abundance in air and precipitation is associated with local use and/or LRAT and, perhaps, transboundary transport from other source regions. More effort is needed to better distinguish chemicals based on their point of origin. Again, this will help to make better regulator and policy decisions regarding CUPs. There is an incentive to accelerate the addition of more CUPs (for which methods exist) to the target lists of the two predominant air networks in Canada—IADN and NCP. Further, it would be beneficial to coordinate the interpretation of results from these networks with information from source regions—for instance, data obtained through CANCUP (Tuduri et al., 2004). Together, this would yield more insightful information regarding the persistence and LRAT of CUPs. CUPs are now (e.g. dicofol), and will continue to be added as POP candidates for the inclusion on international agreements (such as the Stockholm Convention under the United Nations Environment Program (UNEP)) that regulate chemicals. Canada and other member countries have a responsibility to produce useful data for the evaluation of these candidate POPs. (3) Pesticides sales information is not readily available from each province. This is especially a concern for Saskatchewan, the largest user of commercial pesticides. This information is needed to interpret air surveillance data on a region-by-region basis. A first step in the right direction is a report recently prepared by Environment Canada, where data from each region are compared (Brimble et al., 2005). The report highlights data gaps and suggests improvements on how pesticide use and sales information is made available.

(1) Numerous CUPs have been identified in the Canadian atmosphere, especially during periods of application. However, data are not available for all the pesticides that are used (e.g. dicofol) and this is mainly attributed to the lack of appropriate analytical techniques and/or standards. Related to this problem is the lack of information on particle–gas partitioning of CUPs (Clymo et al., 2005). The absence of this information reduces our ability to assess the environmental fate of CUPs and to make informed decisions regarding the regulation of these chemicals.

In addition to these knowledge gaps, which are not limited to Canada, there are other socioeconomic issues related to pesticide use. Several provinces in Canada are engaged in reducing the risk of human exposure to the West Nile virus, transmitted by mosquitoes. Use of organophosphates (malathion, chlorpyrifos) or other chemical families (methoprene) to control mosquito population increases during high risk season but virtually no data are publicly available on air concentrations and/or potential human exposure during intense spraying periods. Some alternatives techniques

and atrazine were detected in 25.4% and 18.8% of the samples, respectively. Median monthly average wet deposition rates were 0.44 and 0.54 mg m 2 for atrazine and chlorothalonil. The latter seemed to exhibit two annual maxima, one in July–August, and the other in December–January. The authors suggested that LRAT could be responsible for this maximum in winter. During the summer of 1998, three high-intensity agricultural areas and one control site were monitored in PEI (White et al., 2000). Chlorothalonil was present in 100% of the samples, followed by metalaxyl (32%) and metribuzin (27%). Maximum chlorothalonil concentrations were in the 45–458 ng m 3 range at all three agricultural sites, and 3.9 ng m 3 at the control site. Metribuzin and aendosulfan were the only other investigated pesticides also quantified at the control site (1.11 and 0.99 ng m 3). Higher concentrations of pesticides were detected in the afternoons and the evenings, as compared to nights and mornings. Chlorothalonil concentration during spraying was inversely correlated with wind speed, while no relationship between concentrations and wind speed were found in the post-spray period (Ernst et al., 2004). Concentrations during spraying reached as high as 13.7 mg m 3, based on a short sampling time (15 min. to 2.5 h). White et al. (2000) suggested that chlorothalonil was constantly elevated in ambient air during the summer season on PEI. Tuduri et al. (2004) reported a monthly average of 11.9 ng m 3 in summer 2003 at Kensington. 6. Perspectives

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(Bacillus thuringiensis or BT products) have also been used, but the relative use of each management technique in unknown. The planting of genetically modified (GM) crops like herbicide tolerant canola, soybean or BT corn has altered integrated pest management practises. This change is thought to be responsible for the sales increases of glyphosate, the active ingredient of Roundup, a popular pesticide used worldwide (Agcare, 2004). The exact impact of GM crops on pesticides use is difficult to assess, as conflicting results have been published for different areas in the world, and for different points in time (for example, Benbrook, 2003; Pray et al., 2001). Our knowledge of domestic/urban uses of pesticides (e.g. lawns, gardens, golf courses) and how these sources contribute to air burdens and human and ecosystem exposure and risk is weak. For example, in Quebec, according to current data, sales of domestic pesticides rose by almost 600% between the end of the 1970s and the start of the 1990s, and by 60% between 1992 and 1996 (Onil, 2001). Finally, it is hoped that these knowledge gaps and concerns will be addressed in the near future. Ideally, this work will involve a collaborative and multidisciplinary approach, and include networks of ‘pesticide researchers’ (toxicologists, soil/water/atmospheric scientists and modellers) across academia, government and industry. Acknowledgements Funding was provided through Environment Canada’s Pesticide Science Fund. Hayley Hung (Northern Contaminants Program), Nick Alexandrou and Ken Brice (Integrated Atmospheric Deposition Network) and Frank Wania (University of Toronto) are greatly acknowledged for sharing their data.

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