Controlling parameters for microbial m pesticide degradation in subsurface and aquifers

Transcription

1 Controlling parameters for microbial m pesticide degradation in subsurface and aquifers Hans-Jørgen Albrechtsen Liselotte Clausen, Philip G. Pedersen, Lars Toräng, Nina Tuxen, Niels Nyholm, Poul L. Bjerg, Gry S. Janniche, Ellinor Lindberg, Christophe Mouvet Warwick, 28 March 2006 DTU / hja@er.dtu.dk Background Pesticides and degradation products are detected in an increasing number of aquifers all over the world, including Europe Aquifer environments differ in many ways from topsoil Low concentrations of the pesticides EU guideline: 0.1 µg/l Low content of organic matter effect on sorption Low microbial numbers, densities and activities Considering hydraulic residence times in aquifers of years, half-lives of e.g. 10 years would still be relevant AIM: Identify controlling parameters to be considered, when predicting the fate of pesticides in subsurface and aquifers 1

2 PEGASE Pesticides in European Groundwaters : detailed study of representative Aquifers and Simulation of possible Evolution EU s 5 th Framework Programme, key action water Sampling in Switzerland BRGM (Orléans, France) FZJ (Jülich, Germany) Alterra (Wageningen, Holland) SLU (Uppsala, Sweden) UKBH Sampling (Copenhagen, in Denmark Denmark) EPFL (Lausanne, Switzerland) LTHE (Grenoble, France) CCBF (Perugia, Italy) WRc (Medmenham, England) C3ED (Versailles, France) DTU (Lyngby, Denmark) Pesticides and aquifers Aquifers: Key pesticides: Cl N NHCH2CH3 Cl N NH2 Havdrup N N NHCH(CH 3) 2 Atrazine N N NHCH(CH3)2 Deethylatrazine Krauthausen Cl CH3 OCHCO 2H (CH3)2CH NHCON(CH 3) 2 CH 3 Brévilles Martigny MCPP CH3 CH2OCH2CH3 N COCH 2Cl CH2CH3 Acetochlor Isoproturon Isoproturon 2

3 C2, m 70 cm DTU 3 cm 2 cm 2 cm 12 cm 7 cm 6 cm 2 cm 10 cm 5 cm Calcaire brun, fin, lité (mudstone); bioturbations (terriers) remplies de sédiments blancs Niveau très fossilifère, poreux. Type Packstone Calcaire fin beige, recristallisé sur les plans de fracturation, parfois poreux, souvent complètement cimenté Delicate handling of sediment samples 3

4 Degradation: Unsaturated zone Purpose: Mineralization of pesticides in depth profiles Methods: Set up: 33 g dry sediment, ml water (natural water content) 0.5 ml 14 C-labelled pesticide added. Initial concentration 10 µg/kg Measurements: 14 CO 2 trapped in 2 ml 0.5 M sodium hydroxide Brévilles: Sediment C1, unsaturated mbs 4

5 Brévilles: Unsaturated zone 14 CO2 (% of initial 14 C) Well C1, topsoil MCPP Isoproturon Acetochlor Atrazine Dea Days Brévilles: Unsaturated zone 5

6 Brévilles: Unsaturated zone, C2 Concentration 6

7 Degradation of 2,4-D aerobic, aquifer sediment, 10 C % 14 C remaining Concentration (µg/l) Change axis scale Toräng et al., 2003, ES&T IS IMPORTANT Concentration Kinetics may shift depending of concentration (µg/l) Thresholds: Above: faster, growth based Below: slower, non-growth based Implications: Degradation experiments to estimate rates should be carried out at relevant (low) concentrations Results from top soil cannot be transferred to subsurface Results from contaminated sites (higher concentrations) cannot be transferred to non-contaminated aquifers (lower concentrations) 7

8 Exposure How much over time? Field injection experiment Aquifer Unconfined Aerobic Injection Natural gradient Continuous injection for 216 days 40 µg/l of MCPP and dichlorprop Sampling At least every second week Broholm et al., 2001, WWR 8

9 Tuxen et al., 2002, ES&T Tuxen et al., 2002, ES&T 9

10 de Lipthay et al. (2003), AEM, 69, de Lipthay et al. (2003), AEM, 69,

11 de Lipthay et al. (2003), AEM, 69, ,4-D, specific degraders ( 14 C-MPN) Total bacterial counts (AODC-staining) Biomass (cells/g) Total bacteria 2,4-D degraders 2,4-D Concentration ( µg/l) Toräng et al., 2003, ES&T 11

12 Degradation of 2,4-D Specific and total bacteria Unpolluted aquifer Initial conc. 0 µg/l 1 µg/l 100 µg/l (=0.45 µm) Toräng et al., 2003, ES&T (Shown on the previous slide) Degradation of 2,4-D Specific and total bacteria Weakly pre-exposed exposed aquifer Initial conc. 0 µg/l 1 µg/l 100 µg/l (=0.45 µm) Toräng et al., 2003, ES&T 12

13 Degradation of 2,4-D Specific and total bacteria Highly pre-exposed exposed aquifer Initial conc. 0 µg/l 1 µg/l 100 µg/l (=0.45 µm) Toräng et al., 2003, ES&T Redox conditions 13

14 Effect of oxygen Havdrup,, MCPP 1, ,8 0.8 Havdrup (Ha-A) Anaerobic MCPP C/C 0 0, , , , Days Effect of oxygen Havdrup,, MCPP Havdrup (Ha-A) Anaerobic 1, ,8 0.8 MCPP C/C 0 0, , , , Havdrup (Ha-D) Anaerobic 1.0 1, , ,6 0, , , Days 14

15 Effect of oxygen Havdrup,, MCPP MCPP C/C 0 Havdrup (Ha-A) Anaerobic 1, , , , , , , , ,6 0, ,2 0.2 Havdrup (Ha-D) Anaerobic Days Havdrup (Ha-A) +Oxygen 1, , , , , , Havdrup (Ha-D) +Oxygen 1.0 1, , , ,4 0, ,0 0, Effects of oxygen concentration on degradation Tuxen et al., 2006, GWMR 15

16 Purpose: Determine (K d ) parameters for modelling purposes Investigate sorption ranges within and between aquifers Investigate the interactions between sorption and degradation Methods: Batch experiments: 5 ml water. 5 g sediment. 10 C. Concentrations: 50 µg/l Equilibrium time: 7 days (MCPP, acetochlor), 14 days (atrazine, deethylatrazine, isoproturon) Measurements: 14 C-pesticide and 14 CO 2 Sorption Sorption coefficients (K( d = C s /C eq ) 5.0 MCPP 4.5 Deethylatrazine 4.0 Atrazine 3.5 Isoproturon Acetochlor TOC: % 1.0 Ma ~0.5% BV BV BV BV BV BV KR-A KR-B Ma-A Ma-B (Ha-A) (Ha-B) Acetochlor Isoproturon Atrazine Deethylatrazine MCPP Anaerobic 16

17 Spatial variation Small scale variation Degradation: MCPP Brévilles mbs. (Pz 1) 1, MCPP C/C0 0,8 0,6 0,4 0,2 0, Days

18 Phenoxy acids Significant plume of phenoxy acids MCPP MCPP Tuxen et al., 2005 Degradation across the fringe Variables Oxygen Phenoxy acid conc. Specific biomass Tuxen et al.,

19 Quantification of tfda, tfdb and tfdc in 50 aquifer sediment samples level (m) tfda tfdc specific degraders (MPN) tfda: /g sediment in 3 samples (tfda 100% match with R. eutropha JMP134 tfda) tfdc: 10 2 /g sediment in same 3 samples tfdb: below detection limit => tfda,c presence, but generally not correlated with MPN #/g sediment Lindberg et al., 2006 Controlling parameters in subsurface Concentration influences kinetics even at very low concentrations (µg/l) Exposure (µg/l) increases degradation Spatial variation (cm) is not always just stochastic Search for controlling parameters: Redox, concentration Degradation may leave a footprint or a trace in the microbial population Tfd-genes Composition of microbial populations 19

20 Funding thanks to Nnn PEGASE 20

21 Tuxen et al., 2002, ES&T Brévilles Altitude NGF (m) Coupe géologique n PZ6 120 SPRING Station hydrométrique 100 PZ7 Source des Brévilles 80 le 14/05/03 Niveau piézométrique le 20/02/01 Discontinuous clay layer Water table Coupe géologique n 3 PZ1 140 Coupe géologique n 2 PZ2 PZ3 120 PZ8 et PZ7 PZ Distance (m) BRGM 21

22 Effect of exposure Tuxen et al., 2002, ES&T Detection of pesticides in water supply wells in Denmark Detection of pesticides in water supply wells in Denmark > 0.1 µg/l µg/l 0 50 km (GEUS, 2003) 22

23 Pesticides in groundwater, USA Investigation period: Pesticides present in 54% of the 1034 sites sampled in both agricultural (56%) and urban (47%) settings 39 pesticides detected of the 46 examined Top 5: Atrazine (38%) - 18% > 0.1 µg/l Deethylatrazine (34%) metabolite Simazine (18%) Metolachlor (15%) Prometon (14%) urban area Sites with pesticides: 73% 2 pesticides (25% 4) Kolpin et al., 1998, ES&T Danish aquifer sediments concentration after 1 year incubation P.G. Pedersen, Thesis 23

24 Zone of degradation at fringe? Sediment core 5 cm pieces 50 microcosms Tuxen et al., 2005 Microcosm studies Oxygen control 14 C-labelled MCPP Evolved 14 CO 2 Tuxen et al.,