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Pesticide uses and transfers in urbanised catchments
Chemosphere 55 (2004) 905–913 www.elsevier.com/locate/chemosphere
Pesticide uses and transfers in urbanised catchments Helene Blanchoud a
a,*
, Frederic Farrugia b, Jean Marie Mouchel
b
Laboratoire Hydrologie et Environnement, EPHE, UMR Sisyphe, UPMC, 4 place Jussieu, Tour 46/56, 4eme etage, BC 122, 75252 Paris cedex 05, France b Centre d’Enseignement et de Recherche Eau Ville Environnement ENPC, 6-8 av. Blaise Pascal, Cite Descartes, Champs sur Marne, 77455 Marne la Vallee cedex 2, France Received 3 February 2003; received in revised form 17 November 2003; accepted 27 November 2003
Abstract An investigation on herbicide uses in two semi-urban catchments was performed simultaneously with sampling campaigns at six stations inside both watersheds from April to July 1998. Urban uses of herbicides exceeded agricultural uses, and transfer coefficients were also higher in urban areas. Therefore, the most used product in urban areas (diuron) was by far the most contaminating product. Householders accounted for 30% of all uses. The highest measured diuron concentration in water surface was 8.7 lg l1 due to its use on impervious surfaces. Compared to EEC standards for drinking water production (0.1 lg l1 ), it is clear that suburban uses of herbicides may severely endanger drinking water production from river water. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Urban; Householder; Herbicide; Diuron; Runoff; France; Paris suburbs
1. Introduction Pesticides are mostly used for agriculture. Numerous authors have evaluated their transport from agricultural land to the atmosphere (Majewski et al., 1990; Kubiac et al., 1995), to groundwater (Pothuluri et al., 1990; Adams and Thurman, 1991; Burkart and Kolpin, 1993) and into rivers (Squillace and Thurman, 1992; Thurman et al., 1994; Dubernet, 1996; Lafrance et al., 1997). The contamination patterns in rivers have been described throughout the year (Dupas et al., 1995; Gruessner and Watzin, 1995; Tisseau et al., 1998; Clark and Goolsby, 2000). However a few studies only have demonstrated stream contamination due to urban uses (Hirai and Tomokuni, 1989; CORPEN, 1996; Kimbrough and Litke, 1996; Gerecke et al., 2002). On a regional scale,
*
Corresponding author. Fax: +33-0144275125. E-mail address: [email protected] (H. Blanchoud).
urban uses are generally too low to be significant, but local impact might be of some importance because of several combined factors such as the imperviousness of urban surfaces and the lack of awareness of urban users with regard to toxic risks and optimal application rates. Private uses in particular are poorly known although pesticides have been detected in urban wastewaters (Nitschke and Schussler, 1998). To compare pesticide contamination from urban and agricultural areas, Gerecke et al. (2002) studied pesticide contamination in wastewater treatment plants (WWTPs) and evaluated the percentage due to improper operation by farmers. However, amounts of pesticides used in urban areas were not estimated. In order to evaluate transfer coefficients in urban areas, it is essential to assess urban uses of pesticides. As outdoor herbicides account for 85% of pesticides used (Braman et al., 1997) in urban areas, we decided to focus our study on herbicides. Inquiries were carried out in two suburban catchments near Paris: the Morbras river and the Reveillon river. Multiple information was collected
0045-6535/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2003.11.061
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about applied amounts of herbicides as well as treatment procedures (e.g.: material used for treatment, type of surface treated, application rates. . .). Then, the herbicide concentration was measured in both rivers from April 7th to July 15th 1998 in order to assess the transfer of herbicides to the receiving water with reference to their application rates (Farrugia et al., 1998). The major aim of this study is to assess whether urban uses can be a significant risk for surface water quality in urbanised areas, particularly where water intakes for drinking water production may require high quality standards.
2. Material and methods 2.1. Study sites Two half urbanised watersheds were selected: the Morbras and the Reveillon rivers. Their catchment areas (55 and 99 km2 respectively) enabled to extensive investigation of most herbicide uses inside the catchments but were also large enough to provide a representative combination of land uses. Both catchments are situated in the south-eastern part of the Paris conurbation (Fig. 1). Like most suburban rivers around Paris, their watersheds show an urbanisation gradient, from mostly forested areas and partly agricultural areas over the plateaux in the upstream part of the catchments to agricultural and more densely urbanised areas nearer to Paris. The sewer system is generally separated and the washed out fraction of pesticides used outdoor will reach surface waters through the urban runoff drainage network. Inside each catchment, three sampling stations were defined to cover the urbanisation gradient (Table 1).
2.2. Investigations of herbicide uses Urban users were identified as municipal technical services of cities (24), local road maintenance units (5), railway companies (2), recreation and hospital parks managers (6), private castles owners (6), golf courses managers (5), national forest organisation (2) and householders. For most identified users, we could evaluate the amounts of herbicides they purchased and used during the three years preceding our study (1996–1998). Furthermore, detailed information about the application process was obtained, especially concerning the application periods, applied amounts and types of urban soil treated (e.g.: ground, grass, sand, gravel, asphalt, pavement. . .). Extrapolation for each herbicide and for each municipality inside the catchments was made on the basis of land use areas (e.g.: roads, cemeteries, parks. . ..) computed from the regional Geographical Information System (GIS) available for Ile de France (IAURIF, 1994). The inquiry about pesticide purchased by householders was carried out in large garden centres. Additional information was collected by interviews of householders at home to get complementary information about herbicide uses. To assess different standards of life, investigations were made in three residential districts with different average garden areas. Their identification was made according to the regional GIS: continuous houses (garden size about 20 m2 ), individual sister houses (garden size about 80 m2 ) and individual non-sister houses (garden size above 150 m2 ). A hundred inquiries were realised in each district to get a relevant sample. All information was geographically extrapolated to the municipality scale.
Fig. 1. Map of the experimental catchments: Morbras (north) and Reveillon (south). Figure shows the positions of selected sampling stations defining subcatchments (not drawn). Map based on the GIS built by IAURIF (IAURIF, 1994).
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Table 1 Land use and yearly estimated uses of herbicides for each subcatchment in kg, sodium chlorate excluded Subcatchment
Inhab./km2
% Agric.
% Urban
Agric.
Urban
Morbras Morbras Morbras Morbras
1255.5 1681.5 2698.0 1555.3
33 15 7 55
17.6 32.2 2.0 19.9
31.7 53.2 65.0 45.0
681 542 6 1229
337 100 24 462
679 506 180 1365
476.7 862.8 1319.1 955.6
19 43 36 99
46.2 19.2 15.7 23.2
16.9 28.4 36.5 29.1
1126 915 627 2669
150 421 568 1139
37 466 526 1029
1171.1
153
22.0
34.8
3898
1601
2394
Reveillon Reveillon Reveillon Reveillon
upstream (1) median (2) downstream (3) (total) upstream (1) median (2) downstream (3) (total)
Total
Area (km2 )
Land use
Herbicide uses (kg) Houses
Subcatchments are indicated in parenthesis. Herbicides used by farmers (Agric.), maintenance organisation (Urban) and householders (Houses) are detailed.
Agricultural inputs were included for comparison. They were established after consulting an expert from a local agricultural organisation. Application rates and areas occupied by major types of cultures were combined to compute inputs. 2.3. Sampling Weekly integrated water samples were collected continuously with automated samplers. Typically, one sample of about 20 ml was collected every hour during base flow periods, and the sampling rate was automatically increased threefold for higher river discharges. Fully flow proportional sampling is of course theoretically better to compute fluxes but also has disadvantages: (i) good discharge data must be available locally in real time to drive the sampler, which was not the case at all stations, and (ii) since the total water volume over the sampling period cannot be predicted, too small as well as too large samples may practically be lost. Water sampling was conducted from April 7th to July 15th 1998, the period in the year when most products are usually applied. S-triazines and phenoxy acetic acids were analysed during the whole period and diuron and neburon from May 26th to July 15th 1998. Due to field limitations, refrigerated samplers could not be used. To improve sample conservation 50 ml of methylene chloride (CH2 Cl2 ) was added to the empty glass bottles before sampling, under a thin layer of water to prevent solvent volatilisation. Conservation tests were made with natural river water without any pesticide addition: river sample were simply kept during one week inside the sampling bottles with 50 ml CH2 Cl2 . 2.4. Laboratory analyses Weekly samples were collected in 10 l glass bottles at the six sampling sites and then each glass bottle was
divided in three separated 1 l subsamples. They were sent to the laboratory for pesticide analysis. Each subsample was analysed using a different method to detect the herbicides of interest in this study. Analytical procedure was previously described (Legrand et al., 1991). S-triazines (atrazine, simazine, terbuthylazine, and degradation products of atrazine: deethylatrazine–– DEA––and deisopropylatrazine––DIA) and isoproturon were extracted three times with methylene chloride, concentrated and prepared for GC/MS analysis. Twenty-five replicates were carried out at concentrations between 20 and 500 ng l1 . Recoveries ranged from 42 ± 2% (DIA) to 99.5 ± 7.5% (isoproturon). Quantification limits (QL) were 0.02 lg l1 for triazines except DIA and 0.05 lg l1 for isoproturon and DIA. Phenoxy acetic acids (2,4-D, 2,4-DB, mecoprop and 2,4-MCPA) were transformed by methylation and prepared like the triazines for GC/MS analysis (QL 0.02 lg l1 , mean recovery 77.5 ± 4%). Phenylureas (diuron and neburon) except isoproturon were prepared for SPE (solid phase extraction) and analysed by HPLC with UV detection (QL 0.02 lg l1 , recovery 92 ± 8%). The addition of small amounts of CH2 Cl2 as conservative did not decrease the efficiency of SPE.
3. Results and discussion 3.1. Investigation of pesticide uses Because of the relatively small catchment size (24 municipalities plus few parks owners and road/railway management units), personalized contacts with technical staff could be made. More than 60% return rate was obtained and results can reasonably be extrapolated. Active ingredients used by technical services are applied to treat all kinds of urban soils, but roads and pathways
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are generally predominant. As roads are not always represented in the GIS because their width is smaller than the minimal GIS resolution of 25 m, another representative land cover had to be used for extrapolation. Among the various land cover items proposed by the regional GIS (IAURIF, 1994), housing areas were better correlated with pesticide uses by municipalities. A detailed examination of more precise maps in selected areas of both Morbras and Reveillon catchments showed that road and street areas could be estimated to 20% of the total housing areas. Most municipalities, gave detailed information about application for major uses. Average application rates on the more consuming urban land uses were found to be 900 g ha1 for roads and streets, 4000 g ha1 for cemeteries and 500–800 g ha1 for parks and sports yards. However very high variations were found for all types of land uses in the 16 cities which accepted to answer the inquiry. Regression of herbicide application rates versus land uses allowed the extrapolation to the eight cities which did not answer the questionnaire and the total herbicide input to the six subcatchments in the Morbras and Reveillon watersheds could be computed. Due to the large areas they occupy, roads receive more than half of all herbicides spread by technical services. Application rates on railway tracks were expressed as a function of track length. Considering that railways have two tracks, an application rate of 6 kg km1 is obtained for each track. Schweinsberg et al. (1999) calculated 8–10 t ha1 applied by the German railway company in 1990, which is more than 1000 times higher than we observed in France with a railway width estimated to be 20 m (about 3 kg ha1 ). Sixty four active ingredients were identified in urban areas, the most used herbicides were diuron (15%), aminotriazole (12%), chlortiamidine (11%), glyphosate (5%), sulfosate (5%), bromacile (4%), 2,4-D (3%), neburon (3%) and 2,4-MCPA (3%). Diuron, aminotriazole and glyphosate were used as total herbicides and mecoprop, dichlorprop, 2,4-MCPA, 2,4-D and oxadiazon were mostly used for sport grounds, golf courses, yards, parks and other ornamental gardens. Braman et al. (1997) found a quite different percentage of each active ingredient for urban uses within Atlanta (United States) because their enquiries only focused on landscape maintenance firms, who used preferentially selective herbicides. They also found large amounts of pendimethalin (41%), which is commonly used for market gardening in France. No diuron and aminotriazole were used in their study, showing differences between the countries. Inquiries about householders were carried out in large garden centres. On the whole, sodium chlorate is the major herbicide used by householders (80%). This particular product was excluded from further analysis because its chemistry, toxicity and application rates are highly different from all other xenobiotic and organic
substances used as herbicides. Other main herbicides used were diuron (22%), aminotriazole (15%), dichlorprop (11%), glyphosate (7%), mecoprop (6%) and 2,4MCPA (5%). Inquiries realised in each district did not allow identification of substances applied by householders, which generally cannot remember the pesticides they bought. However, the percentage of householders who do not use any herbicide nor pesticide in the garden could be estimated at 50%. This percentage is in agreement with other work (Davis et al., 1992; Templeton et al., 1998). Furthermore, Templeton et al. (1998) indicated that 41% of all householders in the United States applied at least one type of outdoor pesticide at least once in 1990. Accordingly, results obtained in garden centres were extrapolated to half householders living inside the Morbras and Reveillon watersheds, leading to a total use of 11.4 t yr1 , about 80% of which is sodium chlorate. In the Morbras and Reveillon catchments, the 12 most utilised herbicides for agricultural uses were isoproturon (27%), mecoprop (7.3%), aclonifen (6.4%), atrazine (5.8%), pyridate (5.7%), trifluraline (5.6%), metamitrone (5.0%), tebutame (4.8%), bifenox (4.4%), chloridazone (3.7%), fluoroxypyr (3.3%) and linuron (2.5%). Herbicides used for agriculture and for urban use were very different due to EEC regulations, which forbid several herbicides like atrazine for non-agricultural use. Simazine has also been banned for urban uses since 1998 but private users can employ the rest of their stock. Since our study was conducted in 1998, several other pesticides have been added to the banned list. Mecoprop was the only product significantly spread on both urban and agricultural areas. Indeed, maintenance of roads, yards and pavements needs total herbicides and brushwood killers, while farmers generally prefer selective substances in order to focus on specific weeds and to protect crops. Among the products we could analyse, isoproturon and atrazine were the best signatures for agricultural uses while diuron and 2,4-MCPA should be efficient tracers of urban uses. Aminotriazole and glyphosate were still extremely difficult to analyse because of their polar nature and the poor yield of commonly used extraction techniques. Total inputs of all herbicides inside each subcatchment are summarized in Table 1. They were estimated at about 8 t yr1 , 50% of which were due to non-agricultural uses. It must be acknowledged that agricultural uses of pesticides also include many other products than herbicides such as fungicides and insecticides, raising the total pesticides budget up to 8.3 t yr1 for agriculture only. In contrast, herbicides represented more than 90% of all pesticides spread by urban users, householders excluded, that is about 1.6 t yr1 inside the studied area. Given the list of products distributed by garden centres, it seems that householders also use large amounts of other pesticides, but a budget could not be derived from
H. Blanchoud et al. / Chemosphere 55 (2004) 905–913
our inquiry. About 2.4 t yr1 herbicides could be applied in both watersheds by householders but this result needs to be confirmed. The urbanisation gradient is well defined in the Morbras catchment, but agricultural land use shows a maximum in the median part of the river course because of large forested area upstream (Table 1). Land use data show a more regularly spread gradient in the Reveillon catchment which is mainly agricultural upstream with increasing urbanisation downstream. Householder uses were dominant in the Morbras catchment with a higher population density. For both watersheds, urban plus householder inputs were equivalent to those of agricultural, which was much different from what was obtained from previous regional studies (CORPEN, 1996) but has to be related to the strong urbanisation of the selected catchments. The average application rates on both catchments were 1.158 kg ha1 for agricultural areas and 0.75 kg ha1 for urban areas. 3.2. Contamination of Morbras and Reveillon waters Weekly integrated samples showed a significant contamination of Morbras and Reveillon waters (Table 2). Diuron, the most used product in urban areas, was always detected in both agricultural (invaded by urban patches) and urban areas. Neburon, another urban herbicide was detected downstream only in the Reveillon catchment and at all station in the more uniformly urbanised Morbras catchment. Among agricultural herbicides, atrazine was nearly always detected, in spite of the strong decrease of maize production in these areas during the last years. Indeed, atrazine was still detected in most streams in the regions due to its occurrence in
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rainwater (Chevreuil et al., 1996; Blanchoud et al., 2002) and persistence in groundwater. By-products of atrazine are also detected everywhere. Mecoprop is an herbicide used in both agricultural and urban areas. It is also possible that construction materials release mecoprop (R,S-Mecoprop). Bucheli et al. (1998) evaluated the annual washout rate to 2.4 mg m2 (about 0.1&) of the total Preventol B2 (included in some bituminous layers) and concentrations of mecoprop in roof runoffs can increase to 500 lg l1 . 3.3. Herbicide fluxes 3.3.1. Morbras Fig. 2 gives weekly fluxes for the Morbras river. Diuron was measured only since May 19th which explains the higher fluxes of urban herbicides from this date on. The maximum flux of agricultural herbicides occurred when discharge was higher. The inquiry revealed that 35% of agricultural inputs was applied in April. Most of the measured herbicide flux was due to atrazine and its metabolites. The load roughly doubled from the headwater to the downstream sampling point in the same ratio as the discharge did. In April, from 21st to 28th, the flux increased at the downstream station, due to an increase of 2,4-D, 2,4-MCPA, mecoprop and atrazine. An exceptional event occurred from May 12th to 19th with an intense simazine flux at the downstream station only. Since simazine was banned in 1997 for urban users and as no users were identified in this part of the catchment, an accidental release probably occurred. It is important to mention that such a single event may significantly modify the herbicide flux pattern. Gerecke
Table 2 Products detected in the Morbras and Reveillon rivers Substances
Number of samples in each site
Morbras
Isoproturon Atrazine DIA DEA Terbuthylazine
14 14 14 14 14
35 100 42 100 14
23 92 42 92 38
Simazine Mecoprop
14 10
100 90
Diuron Neburon 2,4-D 2,4-MCPA
7 9 10 10
100 22 90 70
% of detection upstream
Reveillon % of detection downstream
>0.1 lg l1 downstream
>0.1 lg l1 downstream
% of detection upstream
% of detection downstream
22% 81% 0% 51% 7%
38 100 31 100 8
14 100 50 100 21
4% 30% 0% 59% 0%
85 80
37% 60%
77 80
100 80
33% 19%
100 67 62 42
100% 45% 20% 10%
100 0 60 70
100 38 80 80
100% 38% 19% 22%
Active ingredients are classified from agricultural (up) to urban (down) uses. Mecoprop and simazine are used in both agricultural and urban areas (the European guideline for drinking water is 0.1 lg l1 ).
H. Blanchoud et al. / Chemosphere 55 (2004) 905–913 4000
4000
3000
3000
Flow (l.s -1)
0
1000
1000
500
250
250
0
0 1000
DOWNSTREAM
Load (g)
250 7
5 07/1
0
07/0
06/3
06/2
3
0 9
7
5 07/1
07/0
3
0
06/2
06/3
9 05/2 6 06/0 2 06/0 9 06/1 6
05/1
5
2 05/1
05/0
04/1 4 04/2 1 04/2 8
0
DOWNSTREAM
500
4 04/2 1 04/2 8
250
04/1
500
1415
750
6
750
06/0
1000
06/1
500
UPSTREAM
750
2 05/1 9 05/2 6 06/0 2
750
Load (g)
Load (g)
UPSTREAM
Load (g)
1000
0
5
1000
2000
05/1
2000
05/0
Flow (l.s-1)
910
Fig. 2. Mean flow (l s1 ) and weekly load (g) of agricultural (black: isoproturon, chlorotoluron, atrazine, DEA, DIA, terbuthylazine), both agricultural and urban (hatching grey/ white: mecoprop, simazine) and urban (white: diuron, neburon, 2,4-D, 2,4-DB, 2,4-MCPA) herbicides at upstream and downstream stations of the Morbras river and. Note that diuron (urban herbicide) were analysed only since May 19th.
Fig. 3. Mean flow (l s1 ) and weekly load (g) of agricultural (black: isoproturon, chlorotoluron, atrazine, DEA, DIA, terbuthylazine), both agricultural and urban (hatching grey/ white: mecoprop, simazine) and urban (white: diuron, neburon, 2,4-D, 2,4-DB, 2,4-MCPA) herbicides at upstream and downstream stations of the Reveillon river. Note that diuron (urban herbicide) were analysed only since May 19th.
et al. (2002) demonstrated the importance of such events in water contamination. Contamination due to diuron was very high as the weekly flux could reach 930 g, i.e. twice the total contamination by all other analysed substances. This herbicide which is only used for urban treatment in these catchments was the main source of pollution for the Morbras. Nitschke and Schussler (1998) also found that diuron was by far the most concentrated herbicide in an urban WWTP influent in Germany. Comparing agricultural and urban areas in the USA, Kimbrough and Litke (1996) also found large differences in the set of herbicides detected at the outlet of urban or rural catchments, but they did not analyse diuron. As a result, the dominance of this active ingredient in urban uses cannot be stated for the United States.
measured, while only a small rain event occurred. It is most likely due to treatments occurring in late May which was a dry and sunny period, and diuron transport by runoff resulted in strong peak concentration after the first rain following the application. Excess application in some areas may also have contributed to this exceptional data compared to other results obtained in the Reveillon river.
3.3.2. Reveillon In the Reveillon river, fluxes were similar to the Morbras profile (Fig. 3). The most important agricultural flux occurred in April, but for Reveillon, differences between upstream and downstream were more significant. The amount of total herbicides monitored downstream was 5.2 times higher than upstream when flow was only 4 times higher. Diuron increased considerably from upstream to downstream. From June 9th to 16th, an exceptional flux of 1281 g (1415 g total urban herbicides) of diuron was
3.3.3. Comparison between the two catchments Significant differences in the behaviour of herbicides were observed in the Morbras and Reveillon catchments despite similar land use and the vicinity of both catchments. Indeed in the Reveillon, loads increased faster upstream to downstream. However, higher quantities of diuron (the herbicide preferentially dedicated to urban catchments) were found in the Morbras. This can be related to a more urbanised land use inside the Morbras catchment. While in Morbras catchment, other urban herbicides were detected at all sampling stations, diuron occurrence was linked mainly to the downstream site of Reveillon watershed, with its urban characterised subcatchment. The contamination of both rivers was highly related to the degree of urbanisation of their catchments. 3.4. Transfer rates The estimation of transfer coefficients from our data set requires some approximation since the sampling
H. Blanchoud et al. / Chemosphere 55 (2004) 905–913
covers an important but limited period of the year, while the inquiry provided information on applications on a yearly basis with only indications about application dates. A first strategy would be to focus on the period where concentration data have been obtained to compute a localised transfer coefficient for this period only. However, the real herbicides application during this period can hardly be defined, and because of delays due to storage in various compartments (soils, groundwater) such a limited balance would probably lack several important transfer processes. Accordingly we preferred to work with yearly budgets. This time scale is adapted to the available information about spread quantities, and river discharges are also available for complete one year period. The problem to solve is to define a representative concentration (C ) to compute the herbicide flux (FH ) as FH ¼ C FW , where FW is the known water flux. When concentration and discharge data are uncorrelated, the representative concentration C is the average concentration. When concentration and discharge data are correlated C becomes higher (positive correlation) or lower (negative correlation) than the average. Representative quantiles have been used to compute yearly fluxes from limited concentrations data sets (Meybeck et al., in press), for a highly discharge correlated concentration such as that of suspended solids, the representative quantile was found to be 75% for larger catchments and up to 90% for very small catchments (few km2 ) where the correlation is higher. The influence of high peak discharges, mostly due to surface on herbicide concentrations in rivers was investigated by measuring diuron and atrazine during a single rain event from 7th to 8th of June 1998 on the downstream station of the Morbras catchment (Fig. 4). Instantaneous samples were taken. Diuron concentra-
10
450 400
250 1 200
Flow (l.s-1)
300
-1
pesticide conc. (µg.l )
350
150 100 50
7
/0
06
0.1 7 :0 21
0
7
/0
06
8
/0
06
: 01
1998
43
19
55
31
: 23
8
/0
06
: 04
8
/0
06
: 06
Fig. 4. Log concentrations (lg l1 ) of atrazine (r) and diuron (d) and flow (l s1 ) during a single rain event at the downstream station of the Morbras river.
911
tion increased rapidly with flow (from 3.2 to 7.6 lg l1 in 1 h) whereas atrazine variations were slow and weak (from 0.12 to 0.18 lg l1 in 3 h). The faster response recorded for diuron agrees with both its origin from more impervious surfaces and from the more downstream urbanised area in the catchment. After high discharge, diuron concentration remained still high (8.7 lg l1 ) whereas atrazine reached the maximum concentration after the peak flow. One can conclude that for this single event, the correlation between concentration and discharge data was poor. On a longer time scale, the comparison of weekly integrated concentration data with weekly discharges also shows a very poor correlation which suggests that the C concentration should be inside the 25–75% concentration quantiles. Finally, we take into account the fact that herbicide exports are most generally recorded during spreading season and that our sampling period focused on that same season, we consider that the quantile range 25–50% provides a reasonable range for C . Of course, only a much more detailed sampling strategy would be needed to improve this guess, which was outside the scope of this study. Flux estimates using the 25% and 50% quantiles are presented in Fig. 5 and compared to inputs. DEA fluxes were added to atrazine exports to produce two transfer coefficients for atrazine, with and without metabolite. DIA was not added because of its possible degradation from both atrazine and simazine. Transfer rates for agricultural substances of this study are in good agreement with export coefficients found in other studies: 1–4% according to Clark and Goolsby (2000) after a literature review. Transfer rates computed from median concentrations for agricultural substances (isoproturon, atrazine + desethylatrazine and mecoprop) varied from 0.13% to 2.4% in the Morbras catchment, and from 0.1% to 2.3% in the Reveillon catchment, whereas those for urban substances as diuron and neburon were in the range from 0.8% to 6.7% (Fig. 5). Urban phenoxy acetic acids (2,4-D and 2,4MCPA) had lower transfer coefficients (0.3–2.1%). These herbicides are also used on lawn and this could result in increased adsorption on organic mater and better infiltration through soil. An exceptionally high transfer coefficient for simazine (29.7%) in the Morbras catchment is due to the exceptional release measured at the outlet as mentioned previously, but not accounted for in the inputs estimation. These results are in agreement with uses of active ingredients. Agricultural herbicide losses were similar to those found in numerous studies. Diuron was generally employed on hard surfaces like roads, cemeteries and railway tracks, where very high losses have been reported, such as 45.1% losses when a storm event occurred after application on hard surfaces (Revitt et al., 2002). The integrated transfer coefficient we obtained for diuron
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H. Blanchoud et al. / Chemosphere 55 (2004) 905–913 INPUTS (kg,yr-1) 1
10
100
1000
100
Morbras
OUTPUTS (kg,yr-1)
DIURON
10
DEA + ATRAZINE ATRAZINE
1
SIMAZINE MECOPROP
NEBURON
ISOPROTURON 2,4 D
2,4 MCPA
0.1 INPUTS (kg,yr -1 ) 1
10
100
1000
100
Réveillon
OUTPUTS (kg,yr-1)
DIURON
10 DEA + ATRAZINE
ATRAZINE 2,4 MCPA
1
NEBURON
MECOPROP
2,4 D
ISOPROTURON SIMAZINE
.
0.1
Fig. 5. Estimated yearly inputs and outputs of some herbicides in the Morbras (top) and Reveillon (bottom) catchments. Vertical bars show the export estimates based on medians and first quartiles.
was much lower than the very high value proposed by Revitt et al. for a single event but higher than coefficient obtained for atrazine (6.4% and 6.7% using the 50% quantile estimate), which is most likely due to its use on impervious surfaces. The diuron transfer coefficient might have been somehow underestimated in this study compared to the other herbicides because diuron was only analysed since May 19th, i.e. probably after the major application period as revealed by the inquiry. Furthermore, transfer coefficients would be dependent on rainfall events, a longer rainfall event can result in higher loss (Shepherd and Heather, 1999). In 1998, mean annual discharge was about two times less than between
1999 and 2001. Pesticide losses could also be higher for these years and could show inter-annual variability.
4. Conclusion In the Morbras and Reveillon catchments, total inputs of herbicides were estimated at about 8 t yr1 , about 50% of which were due to non-agricultural uses. Substances used for agriculture were different from those used in urban areas, except mecoprop. Diuron was the most widely used urban herbicide and also exhibited the highest transfer coefficients once an accidental release of
H. Blanchoud et al. / Chemosphere 55 (2004) 905–913
simazine was excluded. Although mainly agricultural, the Reveillon catchment was also contaminated by urban pollutants, but mostly downstream. In these suburban catchments, herbicides used in urban areas strongly dominated because of larger application on hard surfaces. In order to preserve river water quality, it is important to promote practices entailing the use of less active ingredients in urban areas. Householders in particular could reduce their consumption. The effective runoff caused by various application strategies on a set of urban soils should be studied in detail in order to propose more environmentally friendly practices, like a more adapted choice of active ingredients or better spraying practices, including non-use of herbicides in some situations.
Acknowledgements We thank the CIRSEE for sample analysis. The Valde-Marne council funded this work and greatly helped for its practical realisation. Special thanks to F. Bailly, J. Dore, M.F. Letertre and F. Sevenier.
References Adams, C.D., Thurman, E.M., 1991. Environ. Qual. 20, 540– 547. Blanchoud, H., Garban, B., Ollivon, D., Chevreuil, M., 2002. Chemosphere 47, 1025–1031. Braman, S.K., Oetting, R.D., Florkowski, W., 1997. J. Entomol. Sci. 32 (4), 403–411. Bucheli, T.D., M€ uller, S.R., Voegelin, A., Schwarzenbach, R.P., 1998. Environ. Sci. Technol. 32 (22), 3465–3471. Burkart, M.R., Kolpin, D.W., 1993. J. Environ. Qual. 22 (4), 646–656. Chevreuil, M., Garmouma, M., Teil, M.J., Chesterikoff, A., 1996. Sci. Total Environ. 182, 25–37. Clark, G.M., Goolsby, D.A., 2000. Sci. Total Environ. 248, 101–113. CORPEN, 1996. Qualite des eaux et produits phytosanitaires, propositions pour une demarche de diagnostic. Ministere de l’Environnement, Paris, France. Davis, J.R., Brownson, R.C., Garcia, R., 1992. Arch. Environ. Contam. Toxicol. 22, 260–266.
913
Dubernet, J.F., 1996. Procedings XXVIe congres du Groupe Francßais des Pesticides: Processus de transfert des produits phytosanitaires et modelisation dans les bassins versants, pp. 191–198. Dupas, S., Scribe, P., Etcheber, H., Saliot, A., 1995. Int. J. Environ. Anal. Chem. 58, 397–409. Farrugia, F., Guivarc’h, H., Mouchel, J.M., Dore, J., Bailly, F., 1998. Report. Conseil General du Val-de-Marne, Creteil, France. Gerecke, A.C., Sch€arer, M., Singer, H.P., M€ uller, S.R., Schwarzenbach, R.P., S€agesser, M., Ochsenbein, U., Popow, G., 2002. Chemosphere 48, 307–315. Gruessner, B., Watzin, M.C., 1995. Environ. Sci. Technol. 29 (11), 2806–2813. Hirai, Y., Tomokuni, K., 1989. Bull. Environ. Contam. Toxicol. 42, 589–594. IAURIF, 1994. Le mode d’occupation des sols de l’Ile de France, contenu et mode d’emploi. Institut d’Amenagement et d’Urbanisme de la Region Ile de France, 64 p. Kimbrough, R.A., Litke, D.W., 1996. Environ. Sci. Technol. 30 (3), 908–916. Kubiac, R., Muller, T., Maurer, T., Eichhorn, K.W., 1995. Int. J. Environ. Anal. Chem. 38, 349–358. Lafrance, P., Banton, O., Gagne, P., 1997. Rev. Sci. l’Eau 10 (4), 439–459. Legrand, M.F., Costentin, E., Bruchet, A., 1991. Environ. Technol. 12, 985–996. Majewski, M.S., Glotfelty, D.E., Paw, U.K.T., Seiber, J.N., 1990. Environ. Sci. Technol. 24 (10), 1490–1497. Meybeck, M., Laroche, L., D€ urr, H.H., Syvitski, J.P.M. Global Planet. Change, in press. Nitschke, L., Schussler, W., 1998. Chemosphere 36, 35–41. Pothuluri, J.V., Moorman, T.B., Obenhuber, D.C., Wauchope, R.D., 1990. J. Environ. Qual. 19 (3), 525–530. Revitt, D.M., Ellis, J.B., Llewellyn, N.R., 2002. Urban Water 4, 13–19. Schweinsberg, F., Abke, W., Rieth, K., Rohmann, U., ZulleiSeibert, N., 1999. Toxicol. Lett. 107, 201–205. Shepherd, A.J., Heather, A.I.J., 1999. The 1999 Brighton Conference––Weeds, pp. 669–674. Squillace, Thurman, E.M., 1992. Environ. Sci. Technol. 26 (3), 538–545. Templeton, S.R., Zilberman, D., Yoo, S.J., 1998. Environ. Sci. Technol. 32, 416A–423A. Thurman, E.M., Meyer, M.T., Mills, M.S., Zimmerman, L.R., Perry, C.A., Goolsby, D.A., 1994. Environ. Sci. Technol. 28 (13), 2267–2277. Tisseau, M.A., Fauchon, N., Vandevelde, T., 1998. TSM L’eau, septembre, pp. 54–59.
Pesticide uses and transfers in urbanised catchments Helene Blanchoud a
a,*
, Frederic Farrugia b, Jean Marie Mouchel
b
Laboratoire Hydrologie et Environnement, EPHE, UMR Sisyphe, UPMC, 4 place Jussieu, Tour 46/56, 4eme etage, BC 122, 75252 Paris cedex 05, France b Centre d’Enseignement et de Recherche Eau Ville Environnement ENPC, 6-8 av. Blaise Pascal, Cite Descartes, Champs sur Marne, 77455 Marne la Vallee cedex 2, France Received 3 February 2003; received in revised form 17 November 2003; accepted 27 November 2003
Abstract An investigation on herbicide uses in two semi-urban catchments was performed simultaneously with sampling campaigns at six stations inside both watersheds from April to July 1998. Urban uses of herbicides exceeded agricultural uses, and transfer coefficients were also higher in urban areas. Therefore, the most used product in urban areas (diuron) was by far the most contaminating product. Householders accounted for 30% of all uses. The highest measured diuron concentration in water surface was 8.7 lg l1 due to its use on impervious surfaces. Compared to EEC standards for drinking water production (0.1 lg l1 ), it is clear that suburban uses of herbicides may severely endanger drinking water production from river water. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Urban; Householder; Herbicide; Diuron; Runoff; France; Paris suburbs
1. Introduction Pesticides are mostly used for agriculture. Numerous authors have evaluated their transport from agricultural land to the atmosphere (Majewski et al., 1990; Kubiac et al., 1995), to groundwater (Pothuluri et al., 1990; Adams and Thurman, 1991; Burkart and Kolpin, 1993) and into rivers (Squillace and Thurman, 1992; Thurman et al., 1994; Dubernet, 1996; Lafrance et al., 1997). The contamination patterns in rivers have been described throughout the year (Dupas et al., 1995; Gruessner and Watzin, 1995; Tisseau et al., 1998; Clark and Goolsby, 2000). However a few studies only have demonstrated stream contamination due to urban uses (Hirai and Tomokuni, 1989; CORPEN, 1996; Kimbrough and Litke, 1996; Gerecke et al., 2002). On a regional scale,
*
Corresponding author. Fax: +33-0144275125. E-mail address: [email protected] (H. Blanchoud).
urban uses are generally too low to be significant, but local impact might be of some importance because of several combined factors such as the imperviousness of urban surfaces and the lack of awareness of urban users with regard to toxic risks and optimal application rates. Private uses in particular are poorly known although pesticides have been detected in urban wastewaters (Nitschke and Schussler, 1998). To compare pesticide contamination from urban and agricultural areas, Gerecke et al. (2002) studied pesticide contamination in wastewater treatment plants (WWTPs) and evaluated the percentage due to improper operation by farmers. However, amounts of pesticides used in urban areas were not estimated. In order to evaluate transfer coefficients in urban areas, it is essential to assess urban uses of pesticides. As outdoor herbicides account for 85% of pesticides used (Braman et al., 1997) in urban areas, we decided to focus our study on herbicides. Inquiries were carried out in two suburban catchments near Paris: the Morbras river and the Reveillon river. Multiple information was collected
0045-6535/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2003.11.061
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about applied amounts of herbicides as well as treatment procedures (e.g.: material used for treatment, type of surface treated, application rates. . .). Then, the herbicide concentration was measured in both rivers from April 7th to July 15th 1998 in order to assess the transfer of herbicides to the receiving water with reference to their application rates (Farrugia et al., 1998). The major aim of this study is to assess whether urban uses can be a significant risk for surface water quality in urbanised areas, particularly where water intakes for drinking water production may require high quality standards.
2. Material and methods 2.1. Study sites Two half urbanised watersheds were selected: the Morbras and the Reveillon rivers. Their catchment areas (55 and 99 km2 respectively) enabled to extensive investigation of most herbicide uses inside the catchments but were also large enough to provide a representative combination of land uses. Both catchments are situated in the south-eastern part of the Paris conurbation (Fig. 1). Like most suburban rivers around Paris, their watersheds show an urbanisation gradient, from mostly forested areas and partly agricultural areas over the plateaux in the upstream part of the catchments to agricultural and more densely urbanised areas nearer to Paris. The sewer system is generally separated and the washed out fraction of pesticides used outdoor will reach surface waters through the urban runoff drainage network. Inside each catchment, three sampling stations were defined to cover the urbanisation gradient (Table 1).
2.2. Investigations of herbicide uses Urban users were identified as municipal technical services of cities (24), local road maintenance units (5), railway companies (2), recreation and hospital parks managers (6), private castles owners (6), golf courses managers (5), national forest organisation (2) and householders. For most identified users, we could evaluate the amounts of herbicides they purchased and used during the three years preceding our study (1996–1998). Furthermore, detailed information about the application process was obtained, especially concerning the application periods, applied amounts and types of urban soil treated (e.g.: ground, grass, sand, gravel, asphalt, pavement. . .). Extrapolation for each herbicide and for each municipality inside the catchments was made on the basis of land use areas (e.g.: roads, cemeteries, parks. . ..) computed from the regional Geographical Information System (GIS) available for Ile de France (IAURIF, 1994). The inquiry about pesticide purchased by householders was carried out in large garden centres. Additional information was collected by interviews of householders at home to get complementary information about herbicide uses. To assess different standards of life, investigations were made in three residential districts with different average garden areas. Their identification was made according to the regional GIS: continuous houses (garden size about 20 m2 ), individual sister houses (garden size about 80 m2 ) and individual non-sister houses (garden size above 150 m2 ). A hundred inquiries were realised in each district to get a relevant sample. All information was geographically extrapolated to the municipality scale.
Fig. 1. Map of the experimental catchments: Morbras (north) and Reveillon (south). Figure shows the positions of selected sampling stations defining subcatchments (not drawn). Map based on the GIS built by IAURIF (IAURIF, 1994).
H. Blanchoud et al. / Chemosphere 55 (2004) 905–913
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Table 1 Land use and yearly estimated uses of herbicides for each subcatchment in kg, sodium chlorate excluded Subcatchment
Inhab./km2
% Agric.
% Urban
Agric.
Urban
Morbras Morbras Morbras Morbras
1255.5 1681.5 2698.0 1555.3
33 15 7 55
17.6 32.2 2.0 19.9
31.7 53.2 65.0 45.0
681 542 6 1229
337 100 24 462
679 506 180 1365
476.7 862.8 1319.1 955.6
19 43 36 99
46.2 19.2 15.7 23.2
16.9 28.4 36.5 29.1
1126 915 627 2669
150 421 568 1139
37 466 526 1029
1171.1
153
22.0
34.8
3898
1601
2394
Reveillon Reveillon Reveillon Reveillon
upstream (1) median (2) downstream (3) (total) upstream (1) median (2) downstream (3) (total)
Total
Area (km2 )
Land use
Herbicide uses (kg) Houses
Subcatchments are indicated in parenthesis. Herbicides used by farmers (Agric.), maintenance organisation (Urban) and householders (Houses) are detailed.
Agricultural inputs were included for comparison. They were established after consulting an expert from a local agricultural organisation. Application rates and areas occupied by major types of cultures were combined to compute inputs. 2.3. Sampling Weekly integrated water samples were collected continuously with automated samplers. Typically, one sample of about 20 ml was collected every hour during base flow periods, and the sampling rate was automatically increased threefold for higher river discharges. Fully flow proportional sampling is of course theoretically better to compute fluxes but also has disadvantages: (i) good discharge data must be available locally in real time to drive the sampler, which was not the case at all stations, and (ii) since the total water volume over the sampling period cannot be predicted, too small as well as too large samples may practically be lost. Water sampling was conducted from April 7th to July 15th 1998, the period in the year when most products are usually applied. S-triazines and phenoxy acetic acids were analysed during the whole period and diuron and neburon from May 26th to July 15th 1998. Due to field limitations, refrigerated samplers could not be used. To improve sample conservation 50 ml of methylene chloride (CH2 Cl2 ) was added to the empty glass bottles before sampling, under a thin layer of water to prevent solvent volatilisation. Conservation tests were made with natural river water without any pesticide addition: river sample were simply kept during one week inside the sampling bottles with 50 ml CH2 Cl2 . 2.4. Laboratory analyses Weekly samples were collected in 10 l glass bottles at the six sampling sites and then each glass bottle was
divided in three separated 1 l subsamples. They were sent to the laboratory for pesticide analysis. Each subsample was analysed using a different method to detect the herbicides of interest in this study. Analytical procedure was previously described (Legrand et al., 1991). S-triazines (atrazine, simazine, terbuthylazine, and degradation products of atrazine: deethylatrazine–– DEA––and deisopropylatrazine––DIA) and isoproturon were extracted three times with methylene chloride, concentrated and prepared for GC/MS analysis. Twenty-five replicates were carried out at concentrations between 20 and 500 ng l1 . Recoveries ranged from 42 ± 2% (DIA) to 99.5 ± 7.5% (isoproturon). Quantification limits (QL) were 0.02 lg l1 for triazines except DIA and 0.05 lg l1 for isoproturon and DIA. Phenoxy acetic acids (2,4-D, 2,4-DB, mecoprop and 2,4-MCPA) were transformed by methylation and prepared like the triazines for GC/MS analysis (QL 0.02 lg l1 , mean recovery 77.5 ± 4%). Phenylureas (diuron and neburon) except isoproturon were prepared for SPE (solid phase extraction) and analysed by HPLC with UV detection (QL 0.02 lg l1 , recovery 92 ± 8%). The addition of small amounts of CH2 Cl2 as conservative did not decrease the efficiency of SPE.
3. Results and discussion 3.1. Investigation of pesticide uses Because of the relatively small catchment size (24 municipalities plus few parks owners and road/railway management units), personalized contacts with technical staff could be made. More than 60% return rate was obtained and results can reasonably be extrapolated. Active ingredients used by technical services are applied to treat all kinds of urban soils, but roads and pathways
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are generally predominant. As roads are not always represented in the GIS because their width is smaller than the minimal GIS resolution of 25 m, another representative land cover had to be used for extrapolation. Among the various land cover items proposed by the regional GIS (IAURIF, 1994), housing areas were better correlated with pesticide uses by municipalities. A detailed examination of more precise maps in selected areas of both Morbras and Reveillon catchments showed that road and street areas could be estimated to 20% of the total housing areas. Most municipalities, gave detailed information about application for major uses. Average application rates on the more consuming urban land uses were found to be 900 g ha1 for roads and streets, 4000 g ha1 for cemeteries and 500–800 g ha1 for parks and sports yards. However very high variations were found for all types of land uses in the 16 cities which accepted to answer the inquiry. Regression of herbicide application rates versus land uses allowed the extrapolation to the eight cities which did not answer the questionnaire and the total herbicide input to the six subcatchments in the Morbras and Reveillon watersheds could be computed. Due to the large areas they occupy, roads receive more than half of all herbicides spread by technical services. Application rates on railway tracks were expressed as a function of track length. Considering that railways have two tracks, an application rate of 6 kg km1 is obtained for each track. Schweinsberg et al. (1999) calculated 8–10 t ha1 applied by the German railway company in 1990, which is more than 1000 times higher than we observed in France with a railway width estimated to be 20 m (about 3 kg ha1 ). Sixty four active ingredients were identified in urban areas, the most used herbicides were diuron (15%), aminotriazole (12%), chlortiamidine (11%), glyphosate (5%), sulfosate (5%), bromacile (4%), 2,4-D (3%), neburon (3%) and 2,4-MCPA (3%). Diuron, aminotriazole and glyphosate were used as total herbicides and mecoprop, dichlorprop, 2,4-MCPA, 2,4-D and oxadiazon were mostly used for sport grounds, golf courses, yards, parks and other ornamental gardens. Braman et al. (1997) found a quite different percentage of each active ingredient for urban uses within Atlanta (United States) because their enquiries only focused on landscape maintenance firms, who used preferentially selective herbicides. They also found large amounts of pendimethalin (41%), which is commonly used for market gardening in France. No diuron and aminotriazole were used in their study, showing differences between the countries. Inquiries about householders were carried out in large garden centres. On the whole, sodium chlorate is the major herbicide used by householders (80%). This particular product was excluded from further analysis because its chemistry, toxicity and application rates are highly different from all other xenobiotic and organic
substances used as herbicides. Other main herbicides used were diuron (22%), aminotriazole (15%), dichlorprop (11%), glyphosate (7%), mecoprop (6%) and 2,4MCPA (5%). Inquiries realised in each district did not allow identification of substances applied by householders, which generally cannot remember the pesticides they bought. However, the percentage of householders who do not use any herbicide nor pesticide in the garden could be estimated at 50%. This percentage is in agreement with other work (Davis et al., 1992; Templeton et al., 1998). Furthermore, Templeton et al. (1998) indicated that 41% of all householders in the United States applied at least one type of outdoor pesticide at least once in 1990. Accordingly, results obtained in garden centres were extrapolated to half householders living inside the Morbras and Reveillon watersheds, leading to a total use of 11.4 t yr1 , about 80% of which is sodium chlorate. In the Morbras and Reveillon catchments, the 12 most utilised herbicides for agricultural uses were isoproturon (27%), mecoprop (7.3%), aclonifen (6.4%), atrazine (5.8%), pyridate (5.7%), trifluraline (5.6%), metamitrone (5.0%), tebutame (4.8%), bifenox (4.4%), chloridazone (3.7%), fluoroxypyr (3.3%) and linuron (2.5%). Herbicides used for agriculture and for urban use were very different due to EEC regulations, which forbid several herbicides like atrazine for non-agricultural use. Simazine has also been banned for urban uses since 1998 but private users can employ the rest of their stock. Since our study was conducted in 1998, several other pesticides have been added to the banned list. Mecoprop was the only product significantly spread on both urban and agricultural areas. Indeed, maintenance of roads, yards and pavements needs total herbicides and brushwood killers, while farmers generally prefer selective substances in order to focus on specific weeds and to protect crops. Among the products we could analyse, isoproturon and atrazine were the best signatures for agricultural uses while diuron and 2,4-MCPA should be efficient tracers of urban uses. Aminotriazole and glyphosate were still extremely difficult to analyse because of their polar nature and the poor yield of commonly used extraction techniques. Total inputs of all herbicides inside each subcatchment are summarized in Table 1. They were estimated at about 8 t yr1 , 50% of which were due to non-agricultural uses. It must be acknowledged that agricultural uses of pesticides also include many other products than herbicides such as fungicides and insecticides, raising the total pesticides budget up to 8.3 t yr1 for agriculture only. In contrast, herbicides represented more than 90% of all pesticides spread by urban users, householders excluded, that is about 1.6 t yr1 inside the studied area. Given the list of products distributed by garden centres, it seems that householders also use large amounts of other pesticides, but a budget could not be derived from
H. Blanchoud et al. / Chemosphere 55 (2004) 905–913
our inquiry. About 2.4 t yr1 herbicides could be applied in both watersheds by householders but this result needs to be confirmed. The urbanisation gradient is well defined in the Morbras catchment, but agricultural land use shows a maximum in the median part of the river course because of large forested area upstream (Table 1). Land use data show a more regularly spread gradient in the Reveillon catchment which is mainly agricultural upstream with increasing urbanisation downstream. Householder uses were dominant in the Morbras catchment with a higher population density. For both watersheds, urban plus householder inputs were equivalent to those of agricultural, which was much different from what was obtained from previous regional studies (CORPEN, 1996) but has to be related to the strong urbanisation of the selected catchments. The average application rates on both catchments were 1.158 kg ha1 for agricultural areas and 0.75 kg ha1 for urban areas. 3.2. Contamination of Morbras and Reveillon waters Weekly integrated samples showed a significant contamination of Morbras and Reveillon waters (Table 2). Diuron, the most used product in urban areas, was always detected in both agricultural (invaded by urban patches) and urban areas. Neburon, another urban herbicide was detected downstream only in the Reveillon catchment and at all station in the more uniformly urbanised Morbras catchment. Among agricultural herbicides, atrazine was nearly always detected, in spite of the strong decrease of maize production in these areas during the last years. Indeed, atrazine was still detected in most streams in the regions due to its occurrence in
909
rainwater (Chevreuil et al., 1996; Blanchoud et al., 2002) and persistence in groundwater. By-products of atrazine are also detected everywhere. Mecoprop is an herbicide used in both agricultural and urban areas. It is also possible that construction materials release mecoprop (R,S-Mecoprop). Bucheli et al. (1998) evaluated the annual washout rate to 2.4 mg m2 (about 0.1&) of the total Preventol B2 (included in some bituminous layers) and concentrations of mecoprop in roof runoffs can increase to 500 lg l1 . 3.3. Herbicide fluxes 3.3.1. Morbras Fig. 2 gives weekly fluxes for the Morbras river. Diuron was measured only since May 19th which explains the higher fluxes of urban herbicides from this date on. The maximum flux of agricultural herbicides occurred when discharge was higher. The inquiry revealed that 35% of agricultural inputs was applied in April. Most of the measured herbicide flux was due to atrazine and its metabolites. The load roughly doubled from the headwater to the downstream sampling point in the same ratio as the discharge did. In April, from 21st to 28th, the flux increased at the downstream station, due to an increase of 2,4-D, 2,4-MCPA, mecoprop and atrazine. An exceptional event occurred from May 12th to 19th with an intense simazine flux at the downstream station only. Since simazine was banned in 1997 for urban users and as no users were identified in this part of the catchment, an accidental release probably occurred. It is important to mention that such a single event may significantly modify the herbicide flux pattern. Gerecke
Table 2 Products detected in the Morbras and Reveillon rivers Substances
Number of samples in each site
Morbras
Isoproturon Atrazine DIA DEA Terbuthylazine
14 14 14 14 14
35 100 42 100 14
23 92 42 92 38
Simazine Mecoprop
14 10
100 90
Diuron Neburon 2,4-D 2,4-MCPA
7 9 10 10
100 22 90 70
% of detection upstream
Reveillon % of detection downstream
>0.1 lg l1 downstream
>0.1 lg l1 downstream
% of detection upstream
% of detection downstream
22% 81% 0% 51% 7%
38 100 31 100 8
14 100 50 100 21
4% 30% 0% 59% 0%
85 80
37% 60%
77 80
100 80
33% 19%
100 67 62 42
100% 45% 20% 10%
100 0 60 70
100 38 80 80
100% 38% 19% 22%
Active ingredients are classified from agricultural (up) to urban (down) uses. Mecoprop and simazine are used in both agricultural and urban areas (the European guideline for drinking water is 0.1 lg l1 ).
H. Blanchoud et al. / Chemosphere 55 (2004) 905–913 4000
4000
3000
3000
Flow (l.s -1)
0
1000
1000
500
250
250
0
0 1000
DOWNSTREAM
Load (g)
250 7
5 07/1
0
07/0
06/3
06/2
3
0 9
7
5 07/1
07/0
3
0
06/2
06/3
9 05/2 6 06/0 2 06/0 9 06/1 6
05/1
5
2 05/1
05/0
04/1 4 04/2 1 04/2 8
0
DOWNSTREAM
500
4 04/2 1 04/2 8
250
04/1
500
1415
750
6
750
06/0
1000
06/1
500
UPSTREAM
750
2 05/1 9 05/2 6 06/0 2
750
Load (g)
Load (g)
UPSTREAM
Load (g)
1000
0
5
1000
2000
05/1
2000
05/0
Flow (l.s-1)
910
Fig. 2. Mean flow (l s1 ) and weekly load (g) of agricultural (black: isoproturon, chlorotoluron, atrazine, DEA, DIA, terbuthylazine), both agricultural and urban (hatching grey/ white: mecoprop, simazine) and urban (white: diuron, neburon, 2,4-D, 2,4-DB, 2,4-MCPA) herbicides at upstream and downstream stations of the Morbras river and. Note that diuron (urban herbicide) were analysed only since May 19th.
Fig. 3. Mean flow (l s1 ) and weekly load (g) of agricultural (black: isoproturon, chlorotoluron, atrazine, DEA, DIA, terbuthylazine), both agricultural and urban (hatching grey/ white: mecoprop, simazine) and urban (white: diuron, neburon, 2,4-D, 2,4-DB, 2,4-MCPA) herbicides at upstream and downstream stations of the Reveillon river. Note that diuron (urban herbicide) were analysed only since May 19th.
et al. (2002) demonstrated the importance of such events in water contamination. Contamination due to diuron was very high as the weekly flux could reach 930 g, i.e. twice the total contamination by all other analysed substances. This herbicide which is only used for urban treatment in these catchments was the main source of pollution for the Morbras. Nitschke and Schussler (1998) also found that diuron was by far the most concentrated herbicide in an urban WWTP influent in Germany. Comparing agricultural and urban areas in the USA, Kimbrough and Litke (1996) also found large differences in the set of herbicides detected at the outlet of urban or rural catchments, but they did not analyse diuron. As a result, the dominance of this active ingredient in urban uses cannot be stated for the United States.
measured, while only a small rain event occurred. It is most likely due to treatments occurring in late May which was a dry and sunny period, and diuron transport by runoff resulted in strong peak concentration after the first rain following the application. Excess application in some areas may also have contributed to this exceptional data compared to other results obtained in the Reveillon river.
3.3.2. Reveillon In the Reveillon river, fluxes were similar to the Morbras profile (Fig. 3). The most important agricultural flux occurred in April, but for Reveillon, differences between upstream and downstream were more significant. The amount of total herbicides monitored downstream was 5.2 times higher than upstream when flow was only 4 times higher. Diuron increased considerably from upstream to downstream. From June 9th to 16th, an exceptional flux of 1281 g (1415 g total urban herbicides) of diuron was
3.3.3. Comparison between the two catchments Significant differences in the behaviour of herbicides were observed in the Morbras and Reveillon catchments despite similar land use and the vicinity of both catchments. Indeed in the Reveillon, loads increased faster upstream to downstream. However, higher quantities of diuron (the herbicide preferentially dedicated to urban catchments) were found in the Morbras. This can be related to a more urbanised land use inside the Morbras catchment. While in Morbras catchment, other urban herbicides were detected at all sampling stations, diuron occurrence was linked mainly to the downstream site of Reveillon watershed, with its urban characterised subcatchment. The contamination of both rivers was highly related to the degree of urbanisation of their catchments. 3.4. Transfer rates The estimation of transfer coefficients from our data set requires some approximation since the sampling
H. Blanchoud et al. / Chemosphere 55 (2004) 905–913
covers an important but limited period of the year, while the inquiry provided information on applications on a yearly basis with only indications about application dates. A first strategy would be to focus on the period where concentration data have been obtained to compute a localised transfer coefficient for this period only. However, the real herbicides application during this period can hardly be defined, and because of delays due to storage in various compartments (soils, groundwater) such a limited balance would probably lack several important transfer processes. Accordingly we preferred to work with yearly budgets. This time scale is adapted to the available information about spread quantities, and river discharges are also available for complete one year period. The problem to solve is to define a representative concentration (C ) to compute the herbicide flux (FH ) as FH ¼ C FW , where FW is the known water flux. When concentration and discharge data are uncorrelated, the representative concentration C is the average concentration. When concentration and discharge data are correlated C becomes higher (positive correlation) or lower (negative correlation) than the average. Representative quantiles have been used to compute yearly fluxes from limited concentrations data sets (Meybeck et al., in press), for a highly discharge correlated concentration such as that of suspended solids, the representative quantile was found to be 75% for larger catchments and up to 90% for very small catchments (few km2 ) where the correlation is higher. The influence of high peak discharges, mostly due to surface on herbicide concentrations in rivers was investigated by measuring diuron and atrazine during a single rain event from 7th to 8th of June 1998 on the downstream station of the Morbras catchment (Fig. 4). Instantaneous samples were taken. Diuron concentra-
10
450 400
250 1 200
Flow (l.s-1)
300
-1
pesticide conc. (µg.l )
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150 100 50
7
/0
06
0.1 7 :0 21
0
7
/0
06
8
/0
06
: 01
1998
43
19
55
31
: 23
8
/0
06
: 04
8
/0
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: 06
Fig. 4. Log concentrations (lg l1 ) of atrazine (r) and diuron (d) and flow (l s1 ) during a single rain event at the downstream station of the Morbras river.
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tion increased rapidly with flow (from 3.2 to 7.6 lg l1 in 1 h) whereas atrazine variations were slow and weak (from 0.12 to 0.18 lg l1 in 3 h). The faster response recorded for diuron agrees with both its origin from more impervious surfaces and from the more downstream urbanised area in the catchment. After high discharge, diuron concentration remained still high (8.7 lg l1 ) whereas atrazine reached the maximum concentration after the peak flow. One can conclude that for this single event, the correlation between concentration and discharge data was poor. On a longer time scale, the comparison of weekly integrated concentration data with weekly discharges also shows a very poor correlation which suggests that the C concentration should be inside the 25–75% concentration quantiles. Finally, we take into account the fact that herbicide exports are most generally recorded during spreading season and that our sampling period focused on that same season, we consider that the quantile range 25–50% provides a reasonable range for C . Of course, only a much more detailed sampling strategy would be needed to improve this guess, which was outside the scope of this study. Flux estimates using the 25% and 50% quantiles are presented in Fig. 5 and compared to inputs. DEA fluxes were added to atrazine exports to produce two transfer coefficients for atrazine, with and without metabolite. DIA was not added because of its possible degradation from both atrazine and simazine. Transfer rates for agricultural substances of this study are in good agreement with export coefficients found in other studies: 1–4% according to Clark and Goolsby (2000) after a literature review. Transfer rates computed from median concentrations for agricultural substances (isoproturon, atrazine + desethylatrazine and mecoprop) varied from 0.13% to 2.4% in the Morbras catchment, and from 0.1% to 2.3% in the Reveillon catchment, whereas those for urban substances as diuron and neburon were in the range from 0.8% to 6.7% (Fig. 5). Urban phenoxy acetic acids (2,4-D and 2,4MCPA) had lower transfer coefficients (0.3–2.1%). These herbicides are also used on lawn and this could result in increased adsorption on organic mater and better infiltration through soil. An exceptionally high transfer coefficient for simazine (29.7%) in the Morbras catchment is due to the exceptional release measured at the outlet as mentioned previously, but not accounted for in the inputs estimation. These results are in agreement with uses of active ingredients. Agricultural herbicide losses were similar to those found in numerous studies. Diuron was generally employed on hard surfaces like roads, cemeteries and railway tracks, where very high losses have been reported, such as 45.1% losses when a storm event occurred after application on hard surfaces (Revitt et al., 2002). The integrated transfer coefficient we obtained for diuron
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H. Blanchoud et al. / Chemosphere 55 (2004) 905–913 INPUTS (kg,yr-1) 1
10
100
1000
100
Morbras
OUTPUTS (kg,yr-1)
DIURON
10
DEA + ATRAZINE ATRAZINE
1
SIMAZINE MECOPROP
NEBURON
ISOPROTURON 2,4 D
2,4 MCPA
0.1 INPUTS (kg,yr -1 ) 1
10
100
1000
100
Réveillon
OUTPUTS (kg,yr-1)
DIURON
10 DEA + ATRAZINE
ATRAZINE 2,4 MCPA
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NEBURON
MECOPROP
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ISOPROTURON SIMAZINE
.
0.1
Fig. 5. Estimated yearly inputs and outputs of some herbicides in the Morbras (top) and Reveillon (bottom) catchments. Vertical bars show the export estimates based on medians and first quartiles.
was much lower than the very high value proposed by Revitt et al. for a single event but higher than coefficient obtained for atrazine (6.4% and 6.7% using the 50% quantile estimate), which is most likely due to its use on impervious surfaces. The diuron transfer coefficient might have been somehow underestimated in this study compared to the other herbicides because diuron was only analysed since May 19th, i.e. probably after the major application period as revealed by the inquiry. Furthermore, transfer coefficients would be dependent on rainfall events, a longer rainfall event can result in higher loss (Shepherd and Heather, 1999). In 1998, mean annual discharge was about two times less than between
1999 and 2001. Pesticide losses could also be higher for these years and could show inter-annual variability.
4. Conclusion In the Morbras and Reveillon catchments, total inputs of herbicides were estimated at about 8 t yr1 , about 50% of which were due to non-agricultural uses. Substances used for agriculture were different from those used in urban areas, except mecoprop. Diuron was the most widely used urban herbicide and also exhibited the highest transfer coefficients once an accidental release of
H. Blanchoud et al. / Chemosphere 55 (2004) 905–913
simazine was excluded. Although mainly agricultural, the Reveillon catchment was also contaminated by urban pollutants, but mostly downstream. In these suburban catchments, herbicides used in urban areas strongly dominated because of larger application on hard surfaces. In order to preserve river water quality, it is important to promote practices entailing the use of less active ingredients in urban areas. Householders in particular could reduce their consumption. The effective runoff caused by various application strategies on a set of urban soils should be studied in detail in order to propose more environmentally friendly practices, like a more adapted choice of active ingredients or better spraying practices, including non-use of herbicides in some situations.
Acknowledgements We thank the CIRSEE for sample analysis. The Valde-Marne council funded this work and greatly helped for its practical realisation. Special thanks to F. Bailly, J. Dore, M.F. Letertre and F. Sevenier.
References Adams, C.D., Thurman, E.M., 1991. Environ. Qual. 20, 540– 547. Blanchoud, H., Garban, B., Ollivon, D., Chevreuil, M., 2002. Chemosphere 47, 1025–1031. Braman, S.K., Oetting, R.D., Florkowski, W., 1997. J. Entomol. Sci. 32 (4), 403–411. Bucheli, T.D., M€ uller, S.R., Voegelin, A., Schwarzenbach, R.P., 1998. Environ. Sci. Technol. 32 (22), 3465–3471. Burkart, M.R., Kolpin, D.W., 1993. J. Environ. Qual. 22 (4), 646–656. Chevreuil, M., Garmouma, M., Teil, M.J., Chesterikoff, A., 1996. Sci. Total Environ. 182, 25–37. Clark, G.M., Goolsby, D.A., 2000. Sci. Total Environ. 248, 101–113. CORPEN, 1996. Qualite des eaux et produits phytosanitaires, propositions pour une demarche de diagnostic. Ministere de l’Environnement, Paris, France. Davis, J.R., Brownson, R.C., Garcia, R., 1992. Arch. Environ. Contam. Toxicol. 22, 260–266.
913
Dubernet, J.F., 1996. Procedings XXVIe congres du Groupe Francßais des Pesticides: Processus de transfert des produits phytosanitaires et modelisation dans les bassins versants, pp. 191–198. Dupas, S., Scribe, P., Etcheber, H., Saliot, A., 1995. Int. J. Environ. Anal. Chem. 58, 397–409. Farrugia, F., Guivarc’h, H., Mouchel, J.M., Dore, J., Bailly, F., 1998. Report. Conseil General du Val-de-Marne, Creteil, France. Gerecke, A.C., Sch€arer, M., Singer, H.P., M€ uller, S.R., Schwarzenbach, R.P., S€agesser, M., Ochsenbein, U., Popow, G., 2002. Chemosphere 48, 307–315. Gruessner, B., Watzin, M.C., 1995. Environ. Sci. Technol. 29 (11), 2806–2813. Hirai, Y., Tomokuni, K., 1989. Bull. Environ. Contam. Toxicol. 42, 589–594. IAURIF, 1994. Le mode d’occupation des sols de l’Ile de France, contenu et mode d’emploi. Institut d’Amenagement et d’Urbanisme de la Region Ile de France, 64 p. Kimbrough, R.A., Litke, D.W., 1996. Environ. Sci. Technol. 30 (3), 908–916. Kubiac, R., Muller, T., Maurer, T., Eichhorn, K.W., 1995. Int. J. Environ. Anal. Chem. 38, 349–358. Lafrance, P., Banton, O., Gagne, P., 1997. Rev. Sci. l’Eau 10 (4), 439–459. Legrand, M.F., Costentin, E., Bruchet, A., 1991. Environ. Technol. 12, 985–996. Majewski, M.S., Glotfelty, D.E., Paw, U.K.T., Seiber, J.N., 1990. Environ. Sci. Technol. 24 (10), 1490–1497. Meybeck, M., Laroche, L., D€ urr, H.H., Syvitski, J.P.M. Global Planet. Change, in press. Nitschke, L., Schussler, W., 1998. Chemosphere 36, 35–41. Pothuluri, J.V., Moorman, T.B., Obenhuber, D.C., Wauchope, R.D., 1990. J. Environ. Qual. 19 (3), 525–530. Revitt, D.M., Ellis, J.B., Llewellyn, N.R., 2002. Urban Water 4, 13–19. Schweinsberg, F., Abke, W., Rieth, K., Rohmann, U., ZulleiSeibert, N., 1999. Toxicol. Lett. 107, 201–205. Shepherd, A.J., Heather, A.I.J., 1999. The 1999 Brighton Conference––Weeds, pp. 669–674. Squillace, Thurman, E.M., 1992. Environ. Sci. Technol. 26 (3), 538–545. Templeton, S.R., Zilberman, D., Yoo, S.J., 1998. Environ. Sci. Technol. 32, 416A–423A. Thurman, E.M., Meyer, M.T., Mills, M.S., Zimmerman, L.R., Perry, C.A., Goolsby, D.A., 1994. Environ. Sci. Technol. 28 (13), 2267–2277. Tisseau, M.A., Fauchon, N., Vandevelde, T., 1998. TSM L’eau, septembre, pp. 54–59.