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Simazine, metribuzine and nitratesin ground water of agricultural areasof PortugalM.J. Cerejeira a , E. Silva a , S. Batista a , A. Trancoso b ,M.S.L. Centeno c & A. Silva‐Fernandes a

a Instituto Superior de Agronomia , Technical University ofLisbon, DPPF , Secfão de Protecfäo Integrada, Tapada daAjuda, Lisboa Codex, 1399, Portugalb Laboratório de Análises Ambientais e de Controlo daQualidade , Instituto Nacional de Engenharia e TecnologiaIndustrial , Azinhaga dos Lameiros à Estrada do Paço doLumiar, Lisboa Codex, 1699, Portugalc Direcção Regional de Agricultura do Ribatejo e Oeste ,R. Joaquim Pedro Monteiro, 8, Vila Franca de Xira, 2600,PortugalPublished online: 19 Sep 2008.

To cite this article: M.J. Cerejeira , E. Silva , S. Batista , A. Trancoso , M.S.L. Centeno& A. Silva‐Fernandes (2000) Simazine, metribuzine and nitrates in ground water ofagricultural areas of Portugal, Toxicological & Environmental Chemistry, 75:3-4, 245-253, DOI:10.1080/02772240009358908

To link to this article: http://dx.doi.org/10.1080/02772240009358908

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Toxicological and Environmental Chemistry, Vol. 75, pp. 245-253 © 2000 OPA (Overseas Publishers Association) N.V.Reprints available directly from the publisher Published by license underPhotocopying permitted by license only the Gordon and Breach Science

Publishers imprint.Printed in Malaysia.

SIMAZINE, METRIBUZINE AND NITRATESIN GROUND WATER OF AGRICULTURAL

AREAS OF PORTUGAL

M.J. CEREJEIRAa,*, E. SILVAa, S. BATISTAa, A. TRANCOSOb,M.S.L. CENTENOc and A. SILVA-FERNANDESa

aInstituto Superior de Agronomia (Technical University of Lisbon) DPPF,Secfão de Protecfäo Integrada, Tapada da Ajuda, 1399 Lisboa Codex, Portugal;

bInstituto Nacional de Engenharia e Tecnologia Industrial, Laboratório de AnálisesAmbientais e de Controlo da Qualidade, Azinhaga dos Lameiros à Estrada do Paço

do Lumiar, 1699 Lisboa Codex, Portugal; cDirecção Regional de Agricultura doRibatejo e Oeste, R. Joaquim Pedro Monteiro, 8, 2600 Vila Franca de Xira, Portugal

From 1996 to 1998, residues of simazine, metribuzine and nitrates in ground water (irrigationand drinking) were monitored in wells of the main vineyard, apple and pear orchards, potato andtomato growing areas of "Ribatejo e Oeste", an important agricultural region of Portugal.

Of a total of 214 samples collected in nine different areas, simazine was the most frequentlydetected herbicide. It was measured in 96 water samples (44.9%) and reached a maximum con-centration of 0.43 µg/L. Metribuzine was found in 15.4% of the samples with a maximumconcentration of 1.45 ug/L. Levels of metribuzine and simazine above 0.1 ug/L were found res-pectively in 4.7% and 6.1% of the total number of analysed samples. Only residues of simazinewere detected in ground water for human consumption.

Nitrates were also analysed and levels above the maximum concentration of 50 mg/L werefound in some areas, reaching a maximum concentration value of 276mg/L.

Keywords: Simazine; metribuzine; nitrates; ground water contamination

INTRODUCTION

Pesticide pollution of ground water is the result of the agricultural practices,the properties of the substance, its behaviour in the soil environment, thecharacteristics of aquifers and their vulnerability [1].

* Corresponding author.

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246 M.J. CEREJEIRA et al.

More or less systematic monitoring have been planned all over the worldsince the early 1980s, showing the extent of the problem and helping tounderstand many factors regulating the leaching capability of pesticides andthe vulnerability of ground water resources [2].

Herbicides are found to be the main type of pesticides responsible forground water contamination. This particular behaviour of herbicides can beeasily explained by taking in account several aspects related to their uses andproperties compared with other types of widely used pesticides (e.g., insec-ticides and fungicides). In the last years there has been an increase of herbi-cides use in Portugal, 40% of their market being absorbed by vineyard,horticultural crops and apple orchards [3].

The chemical family of triazines comprise some of the herbicides mostcommonly used, like atrazine on maize, simazine on vineyard and orchardsand also metribuzine on tomato and potato. From these, simazine andatrazine have been the most used in Portugal. They are soluble in waterand are quite stable in soil. Because of their importance in agriculture andenvironmental concern their presence in water have been monitored world-wide [2,4]. In Portugal, several studies showed that atrazine, as well asnitrates, are affecting ground water quality, used for irrigation and drinkingpurposes, in maize areas of "Ribatejo e Oeste" [5-8]. In order to assess theextent of the problem with other triazines, simazine and metribuzine werechosen to be studied in areas where they are applied, due to the scarce data onthe exposition of ground water to these molecules in Portugal [9,10] and to itsfrequent detection in ground water of other countries [2,4,11-23].

In this paper results from studies, carried out from 1996 to 1998, toevaluate the contamination of ground water with simazine, metribuzineand nitrates in vineyard, orchards and horticultural areas of the "Ribatejo eOeste" Region, as well as the dynamic of those herbicides in ground water arepresented.

MATERIALS AND METHODS

Study Area

The study was conducted in "Ribatejo e Oeste" Region, an extensive agri-cultural area of different crops. Vineyard is the most important crop in termsof occupied area, grown in 74.102 ha, followed by 30.538 ha of maize,21.109 ha of apple and pear orchards, 14.000 ha of sunflower, 13.932 ha ofpotato, 13.250 ha of tomato (for industry), and other crops [24].

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SIMAZINE, METRIBUZINE AND NITRATES IN GROUND WATER 247

The study area falls mainly in "Tejo-Sado" hydrographie basin, with aground water reservoir of 102.12 km3. The sedimentary formations that occurin the terminal part of the hydrographie basins of the "Tejo" and "Sado" riversare from the Palaeogene to Recent period. The Cenozoic formations con-sist mainly of limestone, sandstone, suite, argilite and marl, whereas therecent formations consist of sandy and sandy-argillaceous material ofalluvial origin.

Previous information on the use of metribuzine and simazine was obtainedby direct inquiry to farmers. Metribuzine was one of the most used pesticidesin tomato and potato crops, while vineyards, apple and pear orchards wereprimarily treated with simazine. Metribuzine usage on tomato was mainlyapplied in spring and summer, whereas the peak seasonal usage on potato wasin winter and early spring. Frequently orchards and vineyards are treated withsimazine at the beginning of the growing season. Rates of herbicide appli-cation were within those recommended on the labels.

Water Sampling and Chemical Analysis

During 1996-1998, 83 samples of water for human consumption and 131irrigation water samples were collected. Sampling occurred in each well oncein 1996 and three to four times in 1997 and 1998. The wells to be sampled wereselected from nine agriculture areas of "Ribatejo e Oeste": "Alto Oeste","Baixo Oeste", "Baixo Sorraia", "Grande Lisboa", "Lezíria do Tejo", "Núcleode Santarém", "Médio Tejo", "Núcleo de Abrantes", "Península de Setúbal"and "Núcleo do Montijo".

The selection criteria included the importance of vineyard, orchards andhorticultural crops in these areas, the use of simazine and metribuzine andthe hydrogeology. From each well three pumped water samples of 1L werecollected every time and kept cool in dry ice until reaching the laboratory.

From 1996 until 1998, 99 drinking water samples and 162 irrigation watersamples were collected for nitrate analysis in the same area. In every samplingdate a 500 mL pumped water sample was collected in each well and kept coolin dry ice until being delivered at the laboratory.

Residues of simazine and metribuzine were extracted with dichloro-methane. Detection was carried out using a Varían Star 3400 gas Chromato-graph, equipped with a N/P detector, using a HP-1 column, 15 m x 0.53 mm.Recovery of simazine and metribuzine were, respectively, 82% and 90% andthe detection limits were 0.014 and 0.008 ug/L for each herbicide. Thedetermination limit was 0.05 jig/L for both. The results were confirmed byGC-MS. Total nitrate value was determined by potenciometry.

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248 M.J. CEREJEIRA et al.

RESULTS AND DISCUSSION

Simazine was the most frequently detected herbicide, which was found in44.9% of the total analysed samples. However, only in "Alto Oeste", "BaixoOeste", "Lezíria do Tejo" and "Núcleo de Abrantes" areas residues of sima-zine were detected in water for human consumption, 0.43 ug/L being thehighest value found (Tables I and II).

Metribuzine was detected in 15.4% of the total samples, particularly in"Baixo Sorraia", "Lezíria do Tejo", "Núcleo de Santarém", "Península deSetúbal" and "Núcleo do Montijo" areas. It was only detected in irrigationwater, with a maximum concentration value of 1.45 ug/L, found in "BaixoSorraia" area (Tables I and II).

Metribuzine and simazine exceeded the value of 0.1 ug/L, respectively, in4.7% and 6.1% of the total samples collected. Metribuzine, applied both in

TABLE I Residue levels of metribuzine and simazine detected in drinking and irrigationground water samples collected in the main agricultural areas of "Ribatejo e Oeste" Region,during 1996-1998

Agricultural area

"Alto Oeste"

"Baixo Oeste"

"Baixo Sorraia"

"Grande Lisboa"

"Lezíria do Tejo"

"Núcleo de Santarém"

"Núcleo de Abrantes"

"Peninsula de Setúbal"

"Núcleo do Montijo"

Type of watersamples

Irrigation waterDrinking water

Irrigation waterDrinking water

Irrigation water

Drinking waterIrrigation waterDrinking waterIrrigation water

Drinking water

Irrigation water

Drinking waterIrrigation waterDrinking water

Irrigation waterDrinking waterIrrigation water

Drinking water

Frequency ofdetection

Metribuzine

0/30/8

0/20/18

13/44

0/60/30/3

4/21

0/30

3/10

0/20/20/6

1/120/6

12/34

0/4

Simazine

0/38/8

0/213/18

21/44

0/60/30/38/21

19/30

2/1Ö

0/21/23/6

1/120/6

20/34

0/4

Range (and mean)*(Ug/L)

Metribuzine

< D L—

< D L< D L

< 0.05-1.45(0.32)< D L< D L< D L

< 0.05-0.08(0.08)<0.05

0.07-0.67(0.37)< D L<DL< D L

<0.05<DL

< 0.05-0.11(0.09)< D L

Simazine

< D L0.07-0.43

(0.25)< D L

< 0.05-0.13(0.08)

< 0.05-0.11(0.07)< D L< D L< D L<0.05

< 0.05-0.08(0.06)

< 0.05-0.10(0.10)< D L<0.05

< 0.05-0.05(0.05)<0.05< D L

< 0.05-0.15(0.08)< D L

•Range (and mean of the quantified residues). < DL - below detection limit.

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SIMAZINE, METRIBUZINE AND NITRATES IN GROUND WATER 249

TABLE II Frequency of metribuzine and simazine residue levels detected in irrigation anddrinking ground water samples collected in the main agricultural areas of "Ribatejo e Oeste"Region, during 1996-1998

Level

> 0.1 ug/L

< 0.1 ug/L

Pesticide

MetribuzineSimazineMetribuzineSimazine

Use/Main crops

Tomato, potatoVineyard, orchardsTomato, potatoVineyard, orchards

Agriculturalarea*

3,6,91,2,3,93,5,8,91,2,3,5,6,7,8,9

Frequency of detection

Total

10/21413/21423/21483/214

Irrigation

10/1315/131

23/13148/131

Drinking

0/838/830/8335/83

•I - "Alto Oeste"; 2 - "Baixo Oeste"; 3 - "Baixo Sorraia"; 4 - "Grande Lisboa"; 5 - "Leziria do Tejo";6 - "Núcleo de Santarém"; 7 - "Núcleo de Abrantes"; 8 - "Península de Setúbal"; 9 - "Núcleo do Montijo".

tomato and potato, was present at levels above 0.1 ng/L in irrigation waterof "Baixo Sorraia", "Núcleo de Santarém" and "Núcleo do Montijo" agri-cultural areas (Table II). However, only simazine was found in drinkingwater, reaching values above the legal limit of 0.1 ug/L, particularly in "Oeste"Region (Table I). This herbicide was detected also above 0.1 ug/L in irriga-tion water samples of "Baixo Sorraia" and "Núcleo do Montijo" agriculturalareas (Tables I and II).

The frequency of occurrence of these chemicals in ground water seems to bedirectly related to their use. Vineyards are widespread in "Ribatejo e Oeste"while potato and tomato are grown mainly in some areas of this region.Simazine residues in ground water are, therefore, to be expected more com-monly than those of metribuzine, with a more restricted use in the study area.On the other hand, contamination is strongly related to soil characteristicsthat influence vulnerability to pesticide leaching, particularly due to irrigationpractices.

From a literature review of pesticides in ground water carried out by Funariand collaborators [2] a large data set is available for simazine and metribuzine.For simazine, maximum values detected in the different data sets range from0.08 to 35 ug/L. Metribuzine has been detected, especially in USA, at differentlevels reaching 940 ng/L. Other authors reported simazine and metribuzinein shallow ground water of the US in 18.0% and 3.1% of the sites [4]. Inareas of almond and vineyard land use, in the San Joaquín Valley, California,simazine was one of the most frequently detected pesticides in ground waterof both areas [20]. This herbicide was also detected in other countries of theAmerican Continent [21-23] and in Europe [11-18].

During the study period we observed a variation of simazine andmetribuzine residue levels in ground water collected in different sites. Thisdynamic points out the influence of some factors that affect pesticide occur-rence in this environmental compartment, such as agricultural management

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250 M.J. CEREJEIRA et al.

30-07-1996 05-06-1997 24-07-1997 02-10-1997 21-04-1998 21-05-1998 09-07-1998 01-09-1998

Sampling date

FIGURE 1 Simazine concentration in ground water samples collected from a fountainlocated in a vineyard and pear orchard area, during 1996-1998.

0.02

06-08-1996 28-05-1997 02-07-1997 29-07-1997 2.1-09-1997 15-04-1998 02-06-1998 02-07-1998 03-09-1998

Sampling date

FIGURE 2 Metribuzine concentration in ground water samples collected from an irrigationwell located in a tomato and potato area, during 1996-1988.

practices (irrigation systems, timings of chemical applications, tillagesystems) [6,7].

An example of dynamic of simazine is presented in Figure 1, concerningresults obtained in a vineyard and pear orchard area. In this case levelsof simazine varied during the sampling period with peaks in July 1996 andJuly/September 1998.

Concentration levels of metribuzine found in irrigation ground water col-lected during 1996-1998 period in a well located in a tomato and potatoarea are shown, as another example, in Figure 2. The higher values ofmetribuzine in late May 1997 and early June 1998 coincided with the peak ofseasonal usage of this herbicide on tomato and with the beginning of irriga-tion practice. In the study area, irrigation rates are higher in June/July, duringhorticultural production, particularly tomato, leading normally to higherloading of pesticides in the underlying aquifers.

Concerning nitrate levels it was found that values exceeding the maximumadmissible concentration established by legislation in drinking water [25]occurred in five agricultural areas of "Ribatejo e Oeste" (Figure 3). Nitrateconcentration results above the maximum recommendable concentrationvalue for irrigation water (50mg/L NOJ) occurred in most areas, with a

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SIMAZINE, METRIBUZINE AND NITRATES IN GROUND WATER 251

Drinking water Irrigation water

S Alto Oeste

D Baixo Oeste

Baixo Sorraia

E2 Grande Lisboa

B Leziria do Tejo

IH Núcleo de Santaréro

ES Núcleo de Abrantcs

0 Península de Setúbal

E3 Núcleo do Montijo

FIGURE 3 Number of samples with nitrates levels above 50mg/L NO3 collected indrinking and irrigation ground water of the studied agricultural areas.

maximum concentration value of 276mg/L registered in "Grande Lisboa"area. These results are most likely due to N-fertilizers and cattle effluents asin the case of "Oeste" area.

Drinking and irrigation ground water contamination by nitrates has beenpointed out in other studies performed in Portugal [6,7,9,26,27].

CONCLUSIONS

The results obtained in this study show that simazine and metribuzine reachground water due to their leaching potential, agricultural practices and thehydrogeological vulnerability of some areas.

Simazine and metribuzine were detected in 44.9% and 15.4% of 214samples, respectively. Both herbicides were found at concentrations above0.1 ug/L, respectively, in 4.7% and 6.1 % of the total samples. However, onlysimazine was detected in the drinking water samples.

Nitrates were found in samples at levels above the maximum concentrationadmissible value (50mg/L NOp in almost all the studied agricultural areas.

A more rational use of such compounds is warranted particularly inagricultural areas with vulnerable soil conditions and high recharge to theaquifers.

A cknowledgements

This work was supported financially by the "Instituto Nacional de Inves-tigaçâo Agraria" (INIA) (Research Project PAMAF-IED No. 4024). Theauthors wish to thank "Direcçào Gérai do Ambiente" (DGA), and particu-larly Eng.a Paula Viana, for the collaboration in laboratory work.

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