Pesticide transfer in the unsaturated zone : sorption and degradation porcesses in geological stratum

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Pesticide transfer in the unsaturated zone : sorption and degradation porcesses in geological stratum

Hélène Blanchoud, Enrique Barriuso, Valerie Bergheaud, Céline Schott, Julien Tournebize, Laurine Nicola, Gaëlle Tallec, Anniet M. Laverman, Florence

Habets

To cite this version:

Hélène Blanchoud, Enrique Barriuso, Valerie Bergheaud, Céline Schott, Julien Tournebize, et al..

Pesticide transfer in the unsaturated zone : sorption and degradation porcesses in geological stratum.

XIV Symposium in Pesticide Chemistry, Università Cattolica del Sacro Cuore. ITA., 2011, Piacenza, Italy. n.p. �hal-02748776�

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PESTICIDE TRANSFER IN THE UNSATURATED ZONE: SORPTION AND DEGRADATION

PROCESSES EXPERIMENTATION

Hélène BLANCHOUD* & Enrique BARRIUSO*, Valérie BERGHEAUD, Céline SCHOTT, Julien TOURNEBIZE, Laurine NICOLA, Gaëlle TALLEC, Anniet LAVERMAN, Medhi ZERARKA, Céline Roose-Amsaleg & Florence HABETS

*Co-first authors : helene.blanchoud@upmc.fr & barriuso@grignon.inra.fr

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Introduction

• Models need to describe transfer processes of pesticides in all compartments

• Lots of studies in soils, water

• The unsaturated zone considered as passive transfer

• However, unknown stock of pesticides in catchments

Need to better describe the unsaturated zone : Sorption processes of pesticides

Degradation processes

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The Orgeval catchment

The PIREN Seine Program:

3 sites for pesticides studies

103 km²

Hydrological equipment since 1962 Mainly agricole

81% culture 18% forest 1% urban area The Orgeval catchment

for the soil-groundwater- river system studies

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• New studies: The Phyt’Oracle Project (CNRS funding)

• Pesticide uses description and crop studies

• Core sample until groundwater (FIRE 3020 funding)

• Long term observation of contamination of groundwater and river by pesticides

• Modeling chain developpment : The Eaudyssée Platform

Z1

Z2

Z3

Z4

Z5

Z6 Z7

Nappe de Brie Nappe de Champigny

Z1

Z2

Z3

Z4

Z5

Z6 Z7

Nappe de Brie Nappe de Champigny

The Orgeval catchment

EC2Co

Phyt’Oracle

EC2Co

Phyt’Oracle

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• Core samples over 40m depth in 2008

• Layer characteristics

• Measure of adsorption

• Measure of degradation kinetics :

mineralisation and by products formation

• Bacterial community profiling (second core sampling in 2011)

Description of pesticide behaviour in the

unsaturated zone

Data collection for modeling and comparison with the unsaturated zone

Sampling procedure

• Sorption and degradation in soils (2009)

• Monthly pesticide contamination in river and piezometers (since 2008)

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Materials and method

• Adsorption procedure

• ¹⁴C U-ring labelled atrazine and isoproturon (only isoproturon for surface soils)

• Triplicate10ml water (with 2mg pesticide) to 2g of dried soils (about 10mg/kg)

• 24h shaking (dark and room temperature)

• Centrifugation (10 min.)

• Surnatant sample for radioactivity measure (compteur Tri-Carb 2100TR Packard)

• Degradation procedure

• C¹⁴U-ring labelled atrazine and isoproturon (only isoproturon for surface soils)

• Triplicate 10g of dried soils for each pesticide and each date of incubation

• Add 1ml water containing about 11mg/L of each pesticide

• Put in a 500ml hermetic jar with 1 beaker of water (humidity control) and 1 with 3 ml of NaOH 2N (¹⁴CO₂capture) in dark at 28°C during incubation times: 7, 14, 28 & 70 days

• Triplicates sacrified for each incubation date and extracted 1 time with water containing CaCl₂10^-2mole/L and 3 times with methanol for radioactivity measure (compteur Tri- Carb 2100TR Packard) and residues analyses (HPLC: diode array detector, Waters)

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Materials and method

• Bacterial community profiling by PCR (Polymerase Chain Reaction)

• Samples were collected in another core sampled in 2011

• DNA extrations were done in duplicate, consequently 2 profiles of each depth

• PCR with 16S RDNA targeting primers (3 different trials to get enough PCR product)

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Adsorption in each layer (16 samples) Degradation until 70 days (5 samples)

Layers composition

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0,0%

0,5%

1,0%

1,5%

2,0%

2,5%

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5

Teneur en carbone organique (en %)

Kd (en l/kg)

Adsorption de l'isoproturon

Unsaturated zone Surface

Kd

%OC

Results : Isoproturon Sorption

Low % of organic carbon in the unsaturated zone (ZNS) Same Kd for isoproturon in soils and the unsaturated zone

Depth Number of field

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Low mineralisation after 70 days :

1% for atrazine, 3% for isoproturon in upper layers, Less than 0,5% in deeper layers

Results : Mineralisation rate

In the unsaturated zone :

0,0 0,5 1,0 1,5 2,0 2,5 3,0

0 20 40 60 80

Quantité minéralisées en % de l'apport initial

temps d'incubation en jours Minéralisation d' l'atrazine

1,6 12,50 21,30 29,60 37,25

Minéralisation de l'isoproturon

0,0 0,5 1,0 1,5 2,0 2,5 3,0

0 20 40 60 80

tem ps d'incubation en jour

Quantité minéralisée en % de l'apport initial 1,6

12,50 21,30 29,60 37,25

Isoproturon Atrazine

Incubation (days) Incubation (days)

% of 14 CO2accordingto initial radioactivity % of 14 CO2accordingto initial radioactivity

Depth Depth

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0 10 20 30 40

0 10 20 30 40 50 60 70

Quantités minéralisées en % de l'apport initial

Temps d'incubation en jours

Minéralisation de l'isoproturon dans les sols différents sols de surface

parcelle 34 parcelle 35 parcelle 36 parcelle 38 parcelle 39 parcelle 43 parcelle 66 Minéralisation de l'isoproturon

0,0 0,5 1,0 1,5 2,0 2,5 3,0

0 20 40 60 80

tem ps d'incubation en jour

Quantité minéralisée en % de l'apport initial 1,6

12,50 21,30 29,60 37,25

Isoproturon in Unsaturated zone

Incubation (days) Incubation (days)

% of 14 CO2accordingto initial radioactivity % of 14 CO2accordingto initial radioactivity

Isoproturon in soils

Results : Mineralisation rate

Low mineralisation in the unsaturated zonecompared with soils Soil mineralisation between 15 and 30% of initial quantities

Comparison between the unsaturated zone and soil surface :

Depth

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Not extractible

Extracted with méthanol Extracted with water Minéralized

No change of the disponibility during incubation

Residues are mainly extracted with water

No bound residues in the unsaturated zone

Results: Disponibility of residues

0 20 40 60 80 100

Depth (m) Atrazine residues

70 days 28 days

14 days 7 days

% of initial radioactivity

0 20 40 60 80 100

Depth (m)

Isoproturon residues

14 days 28 days 70 days

7 days

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Results: Disponibility of residues

Not extractible

Extracted with méthanol Extracted with water Minéralized

Larger bound residues in soils

Extracted residues decrease from 7 to 28 days in soils

0 20 40 60 80 100

Depth (m)

Isoproturon residues in the unsaturated zone

7 days

0 20 40 60 80 100

34 35 36 38 39 43 66 34 35 36 38 39 43 66 34 35 36 38 39 43 66 34 35 36 38 39 43 66

number of field

Isoproturon residues in soil surface

7 days 14 days 28 days 70 days

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Mainly the active substances, mainly in deeper layers

More by-products in the upper layer

Results: Identification of extracted residues

0 20 40 60 80 100

en % de la quantité de 14C-atrazine initiale

Depth (m)

OHA OHDEA OHDIA ATRA DEA DIE DEDIA

Atrazine residues

28 days

0 20 40 60 80 100

Depth (m)

IPU

Monodéméthyl-IPU didéméthyl-IPU ND

ND

Isoproturon residues

28 days

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Results: Identification of extracted residues

Larger quantities of bound residues and mineralisation

More by-products in surface soils

0 20 40 60 80 100

Depth (m)

IPU

ND

Isoproturon residues in unsaturated zone

28 days

0 10 20 30 40 50 60 70 80 90 100

Number of f ield

Isoproturon residues in surface soils

Isopropylanyline IPU

ND ND 28 days

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15 cm 30 cm

80 cm 170 cm 560 cm 630 cm

780 cm 840 cm

M M

 High bacterial diversity in the top layers: 15 and 30 cm depth

 Highly variable bacterial community structure at 80 cm, very different from the upper layers

 Deeper layers containing less DNA ; difficult to obtain PCR products

 At deeper depth a less

diverse bacterial community structure

 Further analysis of the profiles to be done (image analysis of the profiles)

Results : Bacterial community profiling

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Depth (m) DT50 atrazine DT50 isoproturon

1,6 127 26

12,50 57 12

21,30 106 74

29,60 219 220

37,25 186 259

Surface Soils DT50 isoproturon

Meanof fields ‐ 4‐6 days

Discussion: experimental data

• Adsorption : low OC in the unsaturated zone but adsorption occurs

• This adsorption is reversible

• Degradation: faster in upper than in lower layers related to bacterial activity, but low compared with surface soils

Unsaturated

zone Kd Atrazine (mL/kg) Kocatrazine Kdisoproturon

(mL/kg) Koc isoproturon

Min‐max 0.1 – 13.8 44 – 4200 1.0 – 3.1 180 ‐3475

Mean 1.64 1480 1.61 2050

Surface soils Kdisoproturon

(mL/kg) Koc isoproturon

Min‐max 1.2 – 2.7 9.4 – 12.8

Mean 1.80 11.1

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• Transfer of pesticides in the unsaturated zone (Atrazine and Isoproturon)

• Only few mineralisation in deepest zones: < 0,5%, due to low bacterial activity

• Disponibility of the active substance: extractible with water: 40%

after 70 days of incubation

• Processes for modeling the unsaturated zone

• Adsorption-desorption processes can be considered in the unsaturated zone

• Kd is a better descriptor of sorption than Koc in the unsaturated zone

• Adsorption is mainly reversible

• Mineralisation can be neglected (for atrazine and isoproturon)

• Next step : modeling approach (cf poster) Conclusion

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Pesticide transfer in the unsaturated zone : sorption and degradation porcesses in geological stratum

Introduction

The Orgeval catchment

The Orgeval catchment

Sampling procedure

Materials and method

Materials and method

Layers composition

Results : Isoproturon Sorption

Results : Mineralisation rate

Results : Mineralisation rate

Results: Disponibility of residues

Results: Disponibility of residues

Results : Bacterial community profiling

Thank you for your attention!