The Lysimeter Concept - American Chemical Society

Chapter 19

Comprehensive Tracer Studies on the Environmental Behavior of Pesticides: The Lysimeter Concept

Downloaded by UNIV MASSACHUSETTS AMHERST on September 28, 2012 | http://pubs.acs.org Publication Date: September 10, 1998 | doi: 10.1021/bk-1998-0699.ch019

Effects and Exposure Assessment Michael Klein, Werner Klein, Harald Knoche, and Werner Kördel Fraunhofer-Institute for Enviromental Chemistry and Ecotoxicology, Auf dem Aberg 1, D-57392 Schmallenberg, Germany Lysimeters using appropriate sizes and methodology has substantial poten tial to improve risk assessment. This potential for futural improvement of the basis for risk assessment includes, in addition to the assessment of the fate of pesticides in soils and groundwater contamination, comprehensive studies for efffects on flora, fauna and mesofauna as well as effects in the aquifer. Major use of lysimeters at present practically is limited to fate and leaching investigations. In the fate assessments mostly concentrations are considered, but the loading concept - with respect to critical loads - may be a complementary alternative. Practical use of lysimeters in pesticides re gistration basically is following a realistic worst case scenario concept. Generic sets of scenarios considering data statistics and experimental un certainties would provide improved bases for comprehensive risk assess ments and for variations in time at one site, as well as for variations in time and space for regions. In the following, examples are given for other uses of lysimeters. The examples include one concerning accumulation in soil from multiple appli cations, one on lysimeter toxicity testing to improve the information on the ecotoxicological potential of residues in soil and examples on indirect use of lysimeter data for the estimation of exposure in different regions (sensi tivity of regions for pesticides leaching).

Lysimeters and Exposure/Effects Assessment Practical use of lysimeters in pesticides registration usually follows a scenario con cept (realistic worst case) and therefore is not targeted to a exposure/effects assess ment in a probabilistic sense (1, 2, 3). In addition, the broad potential of lysimeters for investigating a wide array of fate and also effects parameters is not regularly used. Lysimeters provide an excellent tool to elaborate information on the long-term 246

©1998 American Chemical Society

In The Lysimeter Concept; Führ, F., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1998.


247 accumulation of residues in soil including non-extractable residues, they provide a tool to assess the partitioning of residues in soil including the partitioning between biota and the soil matrix, they are feasible to elaborate information on effects on soil fauna, they may be used for plant uptake and plant metabolism studies to give just some examples. For all these questions the influence of soils and climates are reflec ted in the results. Consequently, they may be used for comprehensive exposure/ef fects assessment for specific sites additionally. As a result of the realistic worst case concept there may be more sensitive areas which are not included in the realistic worst case, and there are less sensitive regions for which the scenario provides an overestimation of risks.

Accumulation of Residues in Soil The accumulation of residues in soil measured upon repeated applications in field plots and in lysimeters. As there is no dilution by horizontal movement in lysimeters as occurring in field plots, the measurement of the long-term accumulation by lysi meters provides again a more realistic information for the maximum accumulation. Figure 1 gives an example for this build up of soil residues over five years. The ex periments were performed according to the BBA-Guideline. Despite some accumu lation observed during the first three years, the conditions in the last two years were such, that the residues almost reached the level after the first year of application. Although the study was done over five years only it indicates, that for the herbicide under investigation there is low long-term continous accumulation (4). The observations are different for the formation of non-extractable residues (non extractable radioactivity after solvent and subsequent sodium hydroxide extraction). As can be seen from Figure 2, there is a continuous build-up of non-extractable residues during the experimental period for the same pesticide as investigated above and a steady state is not reached after 4 applications. For an assessment of the build up of non-extractable residues in soil information on the identity of the measured radioactivity would be needed.

Effects of Contamination in Soil As mentioned, lysimeters of the size discussed here have not been used so far for effects assessments of pesticides. Small size undisturbed soil columns occasionally, named lysimeters, are, however, a standard tool for the assessment of effects, especially on nutrient cycling. A study is ongoing in this Institute to investigate the feasibility of using outdoor lysimeters for effects endpoints. Figure 3 gives a com parison of a study on some biological endpoints in planted outdoor lysimeters as compared to large (1,8 m ) closed laboratory reactors. The large laboratory reactors are included in the study as a fully controlled alternative. The experiments presented in Figure 3 are controls only without application of a pesticide, and changes in the 3


248 Concentration of a herbicide a.i. in the 0 - 20 cm soil layer upon repeated applications


[mg/kg]

A89

S90

A90

S91

A91

S92

A92

S93

A93

S94

A94

1 .application -f-2.application ^.application « ^ . a p p l i c a t i o n (mean values of two lysimeters)

=autumn, s=spring

A

Figure 1 : Concentration of a Herbicide A.I. in the 0 - 20 cm Soil Layer Upon Repeated Applications. Radioactivity in soil after solvent and NaOH extraction, 0 - 20 cm soil layer [mg/kg] 0,10

0,08

0,06

0,04

0,02

0,00 A89

S90

A90

S91

A91

S92

A92

S93

A93

S94

A94

• 1 .application -H2.application -e-3.application » 4.application (mean values of two lysimeters)

A=autumn, S=spring

Figure 2: Non-extractable Radioactivity in Soil after Solvent and NaOH Extraction, 0-20 cm Soil Layer.


249

Biological parameters determined in lysimeters and closed laboratory reactors Borstel-Scenario, Compost amendment 8 kg/m from household waste 2


incorporated in 20-cm soil layer

Outdoor, plants

-4-

-+microbial

microbial

soil algae

nematodes

biomass

nitrification

chlorophyl

[numbers/g]

[mg N 0 2 -

[mg/g]

[mgC/100 g] measured by SIR

N/(100g*5h)]

I

m May

1996 • Sep. 1996

Laboratory

microbial

microbial

nematodes

biomass

nitrification

[numbers/g]

[mg C/100 g]

[mg N 0 2 -

measured by SIR

N/(100g*5h)]

3May 1996 D A u g . 1996 g N o v . 1996 ElFeb. 1997

Figure 3: Biological Parameters Determined in Lysimeters and Laboratory Reactors - Both not treated with Chemicals.


250


biological response in the course of time therefore represent the depletion of the carbon source or nutrients, respectively (4). Figure 4 shows the results for effects in parallel lysimeter studies using the conta mination of composts as a stressor. Nitrification is a sensitive acute parameter whereas the others do not show significant effects. There are studies ongoing with pentachlorophenol, pyrene and di-ethyl-hexyl-phthalate. In order to investigate the long-term effects, these investigations are continued over an experimental time of 3 years (4). There is at present much effort in many research groups to develop biological test batteries representing relevant endpoints in soils and waters. The emphasis for these ecotoxicological test batteries is on the development of in-vitro tests. These include also mode of action specific endpoints. The state of the art has recently been criti cally evaluated and summarized (5). Using this test battery will provide an important complementary tool for risk assessment of pesticides in soil. In order to avoid different handling of "samples" and assure identical exposure in the biological tests of the battery, lysimeters provide the optimum of investigation methodology. They are also the optimum tool for the validation of in-vitro tests with respect to eco logical relevance.

The Potential Leaching Behaviour of Pesticides in different Soil-ClimateRegions of Germany Since regional soil and climate properties are important in the control of the leaching processes, they are important to predict the fate of chemicals in soil. Relevant processes in soil are simulated e.g. in the model P E L M O (6, 7). For the elucidation of regional differences in Germany, an estimation of infiltrating water was carried out for a total of 22 areas. The scenarios were based on a combination of the 12 most important soil regions in Germany (Figure 5), as defined by the German Federal Institute for Geosciences and Natural Resources (8, 9), and 9 climate areas re presented by a meteorological station (Table 1, daily data for 30 years are available for each station) to estimate the infiltrating water for all scenarios. The data for one soil region in each case represent a typical average scenario based on a weighted computation of several predominant soil profiles. The spatial inhomogeneity of soil structures and soil types are not further considered. For each of the above mentioned soil regions the detailed profile data for the spatially mostly spread soil types are used to compute an average "synthetic" profile as basis for the modelling of pesticide leaching with P E L M O . The soil properties of each surface layer in all regions are listed in Table 2.


Biological parameters determined in lysimeters (experimental conditions as given in Figure 3)


Compost contamination (mg/kg) PCP:0,33; D E H P : 0,52; Pyrene: 1,44

Control, uncontaminated compost

microbial

microbial

soil algae

nematodes

biomass

nitrification

chlorophyl

[numbers/g]

[mg N 0 2 -

[mg/g]

[mg C/100 g] measured by SIR

N/(100g*5h)] | ^ M a y 1996 D S e p . 19961

Contaminated compost i

4

0

+

microbial

microbial

soil algae

nematodes

biomass

nitrification

chlorophyl

[numbers/g]

[mg N 0 2 -

[mg/g]

[mg C/100 g] measured by SIR

N/(100g*5h)]

^ M a y 1996 D S e p . 1996

Figure 4: Effects of Compost Contamination on Soil Biota.



252

Soil Regions in Germany Coastal Region Extensive Food Plains Juvenile Moraine Region Ancient Moraine Region Surface Gravel and Tertiary Downs of the Foothills of the Alps Loess/Sandloess Region Mountainous Region with a Change of non Metamorphic Sedimentary Rock and Loess Mountainous Region with non Metamorphic Calcareous Rock Mountainous Region with non Metamorphic Sedimentary Sand-, Silt- and Clay Marl Rock Mountainous Region with Magmatic and Metamorphic Rock Mountainous Region with Clay and Silt Slate Alps Source: BGR. Reproduced with permission from ref. 8. Copyright 1995 Hartwich et al.

Figure 5: The Most Important Soil Regions in Germany.


253 Table 1: Climate Regions of Germany Representative Site


No. Climate Area 1

North Sea coast, Baltic Sea coast of Schleswig-Holstein

Schleswig

2

Baltic Sea coast of Mecklenburg- Vorpommern

Teterow

3

North German lowlands western part, Lower Rhine area

Hamburg

4

North German lowlands eastern part

Berlin

5

Climate in rain shadow of the mountainous areas, eastern part

Magdeburg

6

Climate in rain shadow of the mountainous areas, western part

Frankfurt

7

Northern low mountain range areas

Bad Marienberg

8

Southern low mountain range areas

Nuernberg

9

Alps, higher locations of Black Forest and southern part of Bavarian Forest

Oberstdorf

Table 2: Soil Parameters for the "Synthetic" Surface Layer of All Soil Regions Area

Depth [cm]

Sand

Silt

Clay

OC

OM

[%]

[%]

[%]

[%]

[%]

FC [Vol%]

PWP [Vol%]

SAE C A W

1

22.58

27.47

51.50

21.03

3.05

4.37

38.26

15.66

1

3

2

17.37

23.44

59.15

17.40

2.77

4.60

41.15

14.44

2

4

3

37.21

68.85

19.61

11.54

1.31

2.29

30.75

12.28

2

4

4

29.93

76.10

16.53

7.37

1.75

2.90

26.54

8.90

2

4

5

25.00

25.86

59.49

14.65

1.91

2.94

39.45

16.73

3

3

6

42.47

11.56

71.90

16.54

1.21

2.16

39.20

14.85

3

3

7

28.25

20.17

51.64

28.19

3.14

4.82

44.04

21.94

2

3

8

20.86

17.40

51.28

31.32

5.01

7.94

47.01

23.88

2

4

9

20.77

40.71

34.44

24.85

3.02

4.18

40.99

19.04

1

4

10 - 14.00

38.11

44.25

17.65

3.96

5.90

41.03

14.90

2

4

11

12.77

35.84

47.63

16.53

3.26

4.73

40.70

15.60

2

4

12

18.40

38.88

31.26

29.86

3.45

6.22

43.49

22.74

2

2-3

SAE = Susceptibility for Erosion (1 = low; 2 = middle; 3 = high; 4 = very high; CAW = Conductivity for Water (1 = very low; 2 = low; 3 = middle; 4 = middle to high; 5 = high; OC = Organic Carbon; OM = Organic Matter, FC = Field Capacity, PWP = Permanent Wilting Point (8)

The combination of 9 climate regions and 12 soil regions in Germany is the basis for establishing 22 leaching scenarios with different soil and/or climate characteristics each (Figure 6). The realistic worst case region used for modelling and outdoor lysi meter studies for the registration and admission of pesticides in Germany ("BorstelScenario") is similar to region No. 10, "Ancient Moraine Region (N.P.)". The amounts of leachates compiled in Table 3 were computed (program P E L M O , version 2.01) (6) based on these scenarios and for a period of 20 years. Simulations were carried out in parallel with three fictitious crop-protection products differing



254

Leaching Regions in Germany Coastal Region Ifl

Flood Plains (N.P.)

ω

Flood Plains (E.P.)

• R L"*

Flood Plains (W.P.)

1

(N.P.: Northern Part) (E.P.: Eastern Part) (W.P.: Western Part) (S.P.: Southern Part) (NE.P.: North Eastern Pert) (SE.P.: South Eastern Part)

(SBj Flood Plains (S.P.) fT^j Juvenile Moraine Region (N.P.) [gj

Juvenile Moraine Region (NE.P.)

[7]

Juvenile Moraine Region (SE.P.)

[7]

Juvenile Moraine Region (S.P.)

ζΤ\ Ancient Moraine Region (N.P.) Ancient Moraine Region (E.P.) |j§|

Ancient Moraine Region (S.P.)

£3

Surface Gravel of the Alps Loess-and Sandioess Region (N.P.) Loess-and Sandioess Region (S.P.)

p i Mountainous Region with a Change I—J of non Metamorphic Sedimentary Rock

Ξ

Mountainous Region with non Metamorphie Sedimentary Rock

•

Mountainous Region with Sedimentary sand-, sut-, Clay- and Man Rock (N.P.) Mountainous Region with Sedimentary Sand-, 3Ht-, Clay- and Marl Rock (S.P.) Mountainous Region with Magmatic and Metam orphie Rock

"

e §gj

Ξ

Mountainous Region with Clay and Silt Slate A,

P

S

Figure 6: Leaching Scenarios in Germany.


,

255 with respect to sorption and biodégradation in soil (sorption coefficient related to organic carbon (Ko ): 60 ml/g, disappearance time for 50 % (DT ): 15 d; K Q : 150, D T 100 and K Q : 400, D T 150). The crop selected for the simulation was winter wheat, the rate of application was 1.0 kg/ha annually applied in May. The con centrations of the three substances to be expected in the leachates annually are compiled in Table 3. The table elucidates possible regional differences concerning the leaching of organic substances in soil and consequently indicates simultaneously the potential risks for groundwater contaminations in the different regions. Clarification on whether the selected scenarios are sufficiently representative for Germany or not needs further investigations. C


50

C

50

C

50

Table 3: Calculated Groundwater Formation Rates and Average A.I. Concentrations Cone, of a.i. in μg/L in Leachate No.

Scenario

Amount of Leachate [L/m ]

a.i. with KOC 60; DT50 15

2

a.i. with KOC 150; DT50 100

a.i. with KOC 400 DT50 150

1

Coastal Region

195

< 0.000005

0.00054

< 0.000005

2

Flood Plains (N.P.)

161

< 0.000005

< 0.000005

< 0.000005

3

Flood Plains (E.P.)

57

< 0.000005

< 0.000005

< 0.000005

4

Flood Plains (W.P.)

54

< 0.000005

< 0.000005

< 0.000005

5

Flood Plains (S.P.)

61

< 0.000005

< 0.000005

< 0.000005

6

Juvenile Moraine Region (N.P.)

605

0.03129

11.62044

1.64035

7

Juvenile Moraine Region (NE.P.)

114

< 0.000005

0.79648

0.00005

8

Juvenile Moraine Region (SE.P.)

95

0.00002

3.08048

0.00991

9

Juvenile Moraine Region (S.P.)

78

0.00016

6.92819

0.06533

10

Ancient Moraine Region (N.P.)

243

0.00112

7.37429

0.34718

11

Ancient Moraine Region (E.P.)

10

0.00003

2.79243

0.00215

12

Ancient Moraine Region (S.P.)

82

0.00024

6.08815

0.01365

13

Surface Gravel of the Alps

63

0.00006

2.75308

0.02432

14

Loess and Sandloess Region (N.P.)

57

< 0.000005

< 0.000005

< 0.000005

15

Loess and Sandloess Region (S.P.)

61

< 0.000005

< 0.000005

< 0.000005

16

Mountainous Region with a change of non Metamorphic Sedimentary Rock and Loess

771

0.00002

0.51131

0.00733

17

Mountainous Region with non Metamorphic Sedimentary Rock Mountainous Region with Sedimentary Sand-, Silt-, Clay-and Marl Rock (N.P.) Mountainous Region with Sedimentary Sand-, Silt-, Clay- and Mari Rock (S.P.) Mountainous Region with Magmatic and Metamorphic Rock

86

< 0.000005

0.00001

< 0.000005

771

0.00012

1.37950

0.05274

65

< 0.000005

0.04585

0.00001

771

0.04056

5.37909

0.84802

18 19 20 21

Mountainous Region with Clay and Silt Slate

771

0.05069

8.48578

1.73385

22

Alps

1332

0.05439

6.97027

1.35115


256 The calculated results for the "Borstel-Scenario" which is used in the registration and admission procedure for pesticides in Germany are given in Table 4.

Table 4 : Groundwater Formation Rates and Average A.I. Concentrations for the "Borstel-Scenario"


Scenario

Amount of Leachate [L/m ] 2

Soil: Borstel / Climate: Hamburg

292

Cone, of a.i. in in Leachate a.i. with a.i. with a.i. with KOC 400 KOC 150; KOC 60; DT50 150 DT50 100 DT50 15 7.914

0.001

0.393

The results of the "Borstel-Scenario" are coincident with the results of leaching region No. 10, "Ancient Moraine Region (N.P.)", although the soil data for Borstel were derived from an existing site near Hannover and not averaged from soil maps. Figure 7 shows the spatial relationship between concentrations in leachates and leaching regions for a substance with a Koc of 150 and a D T of 100. 5 0

Compared to the "Borstel-Scenario" higher concentrations of the a.i. in the leachate are partly simulated for leaching region No. 21, "Mountainous region with clay and silt slate", No. 22 "Alps" and No. 20 "Mountainous region with Magmatic and Meta morphic Rock" (e.g. for the a.i. with KQC 400 and D T 150). This can be explained by very high amounts of precipitation. Concerning intensive agricultural use with intensively treated crops like winter wheat these regions are of minor interest due to their altitude and slope. However, the soil characteristics of soil region No. 3, "Juvenile Moraine region" indicate a lower sorption capacity for organic compounds compared to the "Borstel" soil, because the content of organic carbon is lower in all layers. In connection with a higher amount of precipitation (Hamburg 770 mm/year and Schleswig 880 mm/year) in leaching region No. 6, "Juvenile Moraine Region (N.P.)" the concentrations of all substances analysed are distinctly higher than in the "Borstel-Scenario". This leaching region therefore may be considered as a worst case region in Germany for the leaching of pesticides. 50

Conclusion So far the potential of the lysimeter methodology for the general or site specific ex posure/effects assessment is only used to a very limited extend. The examples given indicate possibilities for expansions of practical use resulting in reliable improve ments of these assessments. As regards the prediction of the sensitivity of regions from lysimeter data sets and Geographical Information Systems, a differentiation is possible. At present, this can only be comparatively used prior to further validation. Applications of the



257

Calculated Concentrations of a.i. in Leachate in pg/l

E3

0-0,0001 pg/l

0

> 0,0001 -0,001 Mg/I > 0,001

-0,01 Mg/I

>o,oi -0,1 Mg/i > 0,1 -0,5pg/l Β

>0,5-1,0μ9/Ι

[3

>1,0-2,0Mg/l > 2,0 -5,0 Mg/I

•

> 5,0-10,0 Mg/I > 10,0-20,0 Mg/I

Date of Application: May, 1 Crop: WlnterWheat a.i.: KOC: 150; DT50:100

Figure 7: Calculated Average Concentrations in Leachates (a.i. 1^:150 and D T : 100). 50


258 "régionalisation" may be to identify regions for monitoring and also to cross-check for assumptions within current assessment systems.

Acknowledgement


Information on which this paper is based upon was elaborated within projects funded by Umweltbundesamt, Berlin and Deutsche Bundesstiftung Umwelt, Osnabriick.

Literature Cited 1. Approaches to a Harmonization of Environmental Assessment of Plant Protection Products for Authorization Purposes - The Political, Administrative and Scientific-Technical Issues-: Report: International Workshop, Schmallenberg, 1997, ISBN 3-8167-4616-0 . 2. Environmental Risk Assessment and Regulatory Decisions (Risk Mitigation Measures): Evaluation of a Questionnaire to OECD Member Countries: Resultingfromthe International Workshop on Approaches to a Harmonization of Environmental Assessment of Plant Protection Products for Authorization Purposes - The Political, Administrative and Scientific-Technical Issues-, 1997, ISBN-3-8167-4614-4. 3. Thematic maps for regional ecotoxicological risk assessment of pesticides: Herrchen, M., Klein, M. and P. Lepper, Sci. Total Environ., 1995, Vol. 171 (1-3), 281-287. 4. Klöppel, H., Hund, K., Personal communication. 5. Alternative Testing Methodologies in Risk Assessment, SGOMSEC 13, Environmental Health Perspectives, in press. 6. PELMO 2.01 Benutzerhandbuch: Klein, M., Fraunhofer-Institut, Schmallenberg, 1995. 7. Validation of the pesticide leaching model PELMO using lysimeter studies performed for registration: Klein, M., Müller, M., Dust, M., Görlitz, G., Gottesbüren, B., Hassink, J., Kloskowski, R., Kubiak, R., Resseler, H., Schäfer, H., Stein, B. and H. Vereecken, Chemosphere, in press 1997. 8. Bodenübersichtskarte der Bundesrepublik Deutschland 1:1000000: Hartwich, R., Behrens, J., Eckelmann, W., Haase, G., Richter, Α., Roeschmann, G. and R. Schmidt. Karte mit Erläuterungen, Textlegende und Leitprofilen. Bundesanstalt für Geowissenschaften und Rohstoffe. Hannover, 1995. Bodenkarte der Bundesrepublik Deutschland 1 : 1000000: Roeschmann, G., Legende und Erläuterungen. Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), Hannover, 1986. 9. Bodenkundliche Kartieranleitung: ARBEITSGRUPPE BODENKUNDE, Hannover, 3. Auflage, 1982.


The Lysimeter Concept - American Chemical Society

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