Metilox Fate Meinecke Sevilla V6 - Umweltbundesamt · 50 :19 h calculated by ... which had been...
1
Fig. 4: Absorbance spectrum of Metilox (green) and light spectrum of the pond illumination (water surface) with and without additional UV A/B-fluorescent tubes (red, black, resp.). Wave length classifi- cation acc. DIN 5031 T7) (below) ® ® l Metilox hydrolyses rapidly under semi-natural conditions.The hydrolysis rate is in the range of the laboratory study (Tab.1). l Metilox and Metilox acid were not persistent at room temperature. l Negligible concentrations of Metilox + Metilox acid were detected in sediment and macrophytes (<0,5 % of initial concentration). l Low concentrations of Metilox occurred in periphyton (<2% of initial concentration). l Besides Metilox acid most probably further smaller, polar metabolites were formed, but not quantified for the mesocosm systems until now. l Under additional UV-light the dissipation of Metilox acid in water was accelerated. l The calculated k (Fig. 5) is higher in comparison to the photodeg laboratory test result, if converted to natural sunlight irradiation. l The mathematical model describes the measured data very well (Fig 6). l Metilox behaved like a water soluble substance. Thus, the model can be simplified accordingly Fig.5 (red marked). ® ® ® ® ® ® ® Experimental and modeled degradation ® and distribution of Metilox in pond mesocosm a a a a b c Meinecke. S. , Feibicke, M. , Mailahn, W. , Berghahn, R. , Hennecke, D. , Focks, A. Introduction Materials & Methods Pond design Size: length 690 x width 325 x height 250 cm 3 Water volume: 20-21 m Artificial light: mean 13,000 lx, in one pond additional UV-fluorescent tubes (see Fig. 2) Ground: sand covered with natural fine sediment Macrophytes: e.g. Myriophyllum verticillatum, Potamogeton nodosus Identified and assumed PBT (Persistent, Bioaccumulative, and Toxic) substances are in general highly lipo- philic and may rapidly adsorp at organic particels and surface areas in aquatic systems. Hence, only a very small part of the corresponding chemical is dissolved in the water phase. Moreover, a sub-group of PBTs is instable in water due to abiotic hydrolysis and photodegradation as demonstrated in laboratory standard tests. Metilox® (methyl 3-(3,5-di-tert.-butyl 4 hydroxyphenyl) propionic acid) seems a suitable model sub- stance of this sub-group. Metilox® is a synthesis intermediate, but by now it is also used as an antioxidant in plastics and oils. Metilox® is poorly soluble, has been classified by the manufacturer as persistent and was therefore temporarily suspected to be a PBT-candidate. However, it hydrolyses in water to 3-(3,5-di- tert-butyl-4-hydroxyphenyl) propionic acid (Metilox® acid) and probably undergoes photodegradation in the air (DT :19 h calculated by AOPWIN). 50 The crucial question arises whether the adsorption at particles may slow down or hinder the abiotic degra- dation under semi-natural conditions. For that reason, fate of Metilox® was investigated in large pond mesocosm systems with and without particle-bound application and with and without UV-light. The kinetic rate constants were calculated using a mathematical fate model, which had been designed for typical PB-substances (see also Poster TU 162). These rates were then compared to rate constants of photodegradation and hydrolysis data, which had been generated in laboratory studies of the IME. Results Fig. 8: Fate of Metilox and metabolites in the whole system (water, sediment, biofilm, and macrophytes) ® Fig. 3: Application: Liquid dosing of solved Metilox (above), dosing of suspensed Metilox (below) ® ® Literature: [1] PBT-Working Group des ECB: http://ecb.jrc.ec.europa.eu/DOCUMENTS/PBT_EVALUATON/PBT_sum065_CAS_6386-38-5.pdf [2] OECD SIDS: Metilox 2001 UNIEP Publications http://www.inchem.org/documents/sids/sids/Metilox.pdf Fig. 2: Scheme of the artificial lighting and macrophyte planting (UV A/B tubes only in selected ponds) Fig. 5: Scheme of the fate model used for the calculation of kinetic rate constants. The red marked flows are the main processes of dissi- pation of Metilox® Discussion l No influence of mode of application on hydrolysis of Metilox was found. l In comparison to the laboratory results no inhibiton of direct photolysis by particles could be observed. However, the inhibition may have been superimposed by other processes (e.g. indirect photolysis) and may be differ with the trophic status of the corresponding surface water. l Abiotic degradation of Metilox may be a relevant process in the environment. l Only low concentrations of Metilox and Metilox acid were detected in sediment and biota. l Further metabolites have to be quantified. ® ® ® ® l In contrast to the literature, Metilox was degradable in this study. l Mathematical kinetic models may provide useful indications for kinetic processes in fate studies even without the use of radiolabelling (no full mass balance feasible). Fig. 6: Results of the model calculations (lines) and experimental data; pond with UV-light and particle-bound application of Metilox a Federal Environment Agency (UBA), email: [email protected] b Fraunhofer Institute Molecular Biology and Applied Ecology (IME) c Institute of Environmental Systems Research University of Osnabrück (USF) Metilox & light spectra ® Application ® ® Liquid Application: 1 pond (marked as: -Celite), initial concentration 25 μg/L; Metilox solved in ethanol/acetonitrile as solubilizer Particle-bound application: 2 ponds (marked as: +Celite), initial concentration 25 μg/L and control; Metilox 250 mg/750 g on inorganic carrier Celite 512 (diatomaceous earth), suspended in 200 L water. Fig. 1: Indoor pond with UV-lamps (indicated by blue reflexion), pond shown without dust protection Tab. 1: Results of the mesocosm and laboratory studies in comparison (DT = DT of Metilox and Metilox -Acid in water, sediment 50 system 50 and biota relative to the start concentration); * DT calculated for 50 annual mean natural sunlight irradiation ® ® Thanks to: ® CIBA Chemicals for abandoning of Metilox , my colleagues D. Graßmann, S. Heller, C. Kohls, S. Loth, N. Mühlenberg, T. Ottenströer, R. Schmiediche, I. Schmiedling for technical support and B. Alscher, B. Katona, S. Rust, D. Schnee for GC-MS analysis OH O O High pressure water pump Pressure- manometer Flat Jet (stainless steel) Adjustable injector (stainless steel) Laboratory bottle Glas tube (Duran) Tube (stainless steel) Spray gun Water tank (drinking water with tracer) High pressure water pump Pressure- manometer Flat Jet (stainless steel) Adjustable injector (stainless steel) Tube (stainless steel) Spray gun Stainless steel water tank with stirring motor (drinking water, anorganic tracer, Celite/ substance-mixture) Myriophyllum HQI-D 2000W HQI-D 400W UV-B 40W UV-A 36W 2 x Biolux 58W 2 x Biolux 58W UV-B 40W UV-A 36W Analysis Analysis by GC-MS(SIM) after solid phase extraction (ENV) and derivatisation (PFB-Br). Fate model 1,7 d System 8 d Pond 4, 11°C +Celite, - UV System 38 d OECD Hydrolysis System OECD Photodeg. System Pond 3, 21°C +Celite, +UV Pond 2, 21°C +Celite, -UV Pond 1, 21°C -Celite, -UV DT 50Hydrolysis 1,3 d 1,1 d DT 50Photodeg. - - - - 9,7 d DT 50System 2,1 d 14 d 16 d Pond 4, 11°C +Celite, -UV OECD 111 25°C,Hydrolysis OECD 316 Photodeg. 1,7 d 5,5 d 2,9 d (pH 9) 8,2 d 38 d - 15,2 d 2,7 d 77 d * M1 Sink Water (Volatisation, Metabolites) M1 Water (Metilox® acid in water) P Sink Water (Volatisation, Metabolites) P Water (Metilox ® in Water) M1 Sediment (Metilox ® acid in sediment and biota) P Sediment (Metilox ® in sediment and biota) M1 Sink Sediment (NER, Mineralisation, Metabolites) P Sink Sediment (NER, Mineralisation, Metabolites) k8 + kPhotodeg. k1 (here: Hydrolysis) k6 (Sorption) k5 (Desorption) k3 (Desorption) k2 (Sorption) k7 ~ 0 k4 k7 k9 Degradation Degradation System 250 300 350 400 450 500 0 2 4 6 8 10 12 14 0.0 0.1 0.2 0.3 0.4 0.5 Spectral irradiance [μW * cm -2 * nm -1 ] Wavelength [nm] Pond -UV Pond +UV Metilox 2 mg/L Metilox acid 2 mg/L UV-B UV-A Absorbance 0 20 40 60 80 100 120 0 10 20 30 40 50 60 70 80 Water Metilox ModelMaker Metilox acid ModelMaker Quota in water relative to total input [%] Days after application 0 20 40 60 80 100 120 0.0 0.2 0.4 0.6 0.8 1.0 Sediment Metilox ModelMaker Metilox acid ModelMaker Quota in sediment relative to total input [%] Days after application 0 20 40 60 80 100 120 0 25 50 75 100 -Celite, -UV 21°C SFO +Celite, -UV 21°C SFO 95 % CL +Celite, +UV 21°C SFO +Celite, -UV 11°C SFO Metilox + Metilox acid relative to start mass [%] Days after application Simulationsanlage FSA Fließ- und Stillgewässer-
Transcript of Metilox Fate Meinecke Sevilla V6 - Umweltbundesamt · 50 :19 h calculated by ... which had been...
Fig. 4: Absorbance spectrum of Metilox (green) and light spectrum of the pond illumination (water surface) with and without additional UV A/B-fluorescent tubes (red, black, resp.). Wave length classifi-cation acc. DIN 5031 T7) (below)
®
®l Metilox hydrolyses rapidly under semi-natural conditions.The hydrolysis
rate is in the range of the laboratory study (Tab.1).
l Metilox and Metilox acid were not persistent at room temperature.
l Negligible concentrations of Metilox + Metilox acid were detected in
sediment and macrophytes (<0,5 % of initial concentration).
l Low concentrations of Metilox occurred in periphyton (<2% of initial
concentration).
l Besides Metilox acid most probably further smaller, polar metabolites
were formed, but not quantified for the mesocosm systems until now.
l Under additional UV-light the dissipation of Metilox acid in water was
accelerated.
l The calculated k (Fig. 5) is higher in comparison to the photodeg
laboratory test result, if converted to natural sunlight irradiation.
l The mathematical model describes the measured data very well (Fig 6).
l Metilox behaved like a water soluble substance. Thus, the model can
be simplified accordingly Fig.5 (red marked).
® ®
® ®
®
®
®
Experimental and modeled degradation ®
and distribution of Metilox in pond mesocosm a a a a b c
Meinecke. S. , Feibicke, M. , Mailahn, W. , Berghahn, R. , Hennecke, D. , Focks, A.
Introduction
Materials & MethodsPond designSize: length 690 x width 325 x height 250 cm
3Water volume: 20-21 m
Artificial light: mean 13,000 lx, in one pond additional
UV-fluorescent tubes (see Fig. 2)
Ground: sand covered with natural fine sediment
Macrophytes: e.g. Myriophyllum verticillatum,
Potamogeton nodosus
Identified and assumed PBT (Persistent, Bioaccumulative, and Toxic) substances are in general highly lipo-philic and may rapidly adsorp at organic particels and surface areas in aquatic systems. Hence, only a very small part of the corresponding chemical is dissolved in the water phase. Moreover, a sub-group of PBTs is instable in water due to abiotic hydrolysis and photodegradation as demonstrated in laboratory standard tests. Metilox® (methyl 3-(3,5-di-tert.-butyl 4 hydroxyphenyl) propionic acid) seems a suitable model sub-stance of this sub-group. Metilox® is a synthesis intermediate, but by now it is also used as an antioxidant in plastics and oils. Metilox® is poorly soluble, has been classified by the manufacturer as persistent and was therefore temporarily suspected to be a PBT-candidate. However, it hydrolyses in water to 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid (Metilox® acid) and probably undergoes photodegradation in the air (DT :19 h calculated by AOPWIN). 50
The crucial question arises whether the adsorption at particles may slow down or hinder the abiotic degra-dation under semi-natural conditions. For that reason, fate of Metilox® was investigated in large pond mesocosm systems with and without particle-bound application and with and without UV-light. The kinetic rate constants were calculated using a mathematical fate model, which had been designed for typical PB-substances (see also Poster TU 162). These rates were then compared to rate constants of photodegradation and hydrolysis data, which had been generated in laboratory studies of the IME.
Results
Fig. 8: Fate of Metilox and metabolites in the whole system (water, sediment, biofilm, and macrophytes)
®
Fig. 3: Application: Liquid dosing of solved Metilox (above), dosing of suspensed Metilox (below)
®
®
Literature: [1] PBT-Working Group des ECB:
http://ecb.jrc.ec.europa.eu/DOCUMENTS/PBT_EVALUATON/PBT_sum065_CAS_6386-38-5.pdf[2] OECD SIDS: Metilox 2001 UNIEP Publications
http://www.inchem.org/documents/sids/sids/Metilox.pdf
Fig. 2: Scheme of the artificial lighting and macrophyte planting (UV A/B tubes only in selected ponds)
Fig. 5: Scheme of the fate model used for the calculation of kinetic rate constants. The red marked flows are the main processes of dissi-
pation of Metilox®
Discussion l No influence of mode of application on hydrolysis of Metilox was found.
l In comparison to the laboratory results no inhibiton of direct photolysis
by particles could be observed. However, the inhibition may have been
superimposed by other processes (e.g. indirect photolysis) and may be
differ with the trophic status of the corresponding surface water.
l Abiotic degradation of Metilox may be a relevant process in the
environment.
l Only low concentrations of Metilox and Metilox acid were detected in
sediment and biota.
l Further metabolites have to be quantified.
®
®
® ®
l In contrast to the literature, Metilox was degradable in this study.
l Mathematical kinetic models may provide useful indications for kinetic
processes in fate studies even without the use of radiolabelling (no full
mass balance feasible).
Fig. 6: Results of the model calculations (lines) and experimental data; pond with UV-light and particle-bound application of Metilox
a Federal Environment Agency (UBA), email: [email protected] b Fraunhofer Institute Molecular Biology and Applied Ecology (IME)c Institute of Environmental Systems Research University of Osnabrück (USF)
Metilox & light spectra®
Application
®
®
Liquid Application: 1 pond (marked as: -Celite), initial concentration 25 µg/L;
Metilox solved in ethanol/acetonitrile as solubilizerParticle-bound application:2 ponds (marked as: +Celite), initial concentration 25 µg/L
and control; Metilox 250 mg/750 g on inorganic carrier
Celite 512 (diatomaceous earth), suspended in 200 L water.
Fig. 1: Indoor pond with UV-lamps (indicated by blue reflexion), pond shown without dust protection
Tab. 1: Results of the mesocosm and laboratory studies in comparison
(DT = DT of Metilox and Metilox -Acid in water, sediment 50 system 50
and biota relative to the start concentration); * DT calculated for 50
annual mean natural sunlight irradiation
® ®
Thanks to: ®
CIBA Chemicals for abandoning of Metilox , my colleagues D. Graßmann, S. Heller, C.
Kohls, S. Loth, N. Mühlenberg, T. Ottenströer, R. Schmiediche, I. Schmiedling for
technical support and B. Alscher, B. Katona, S. Rust, D. Schnee for GC-MS analysis
OH
O O
High pressurewater pump
Pressure-manometer
Flat Jet(stainless steel)
Adjustableinjector(stainless steel)
Laboratory bottle
Glas tube(Duran)
Tube (stainless steel)
Spray gun
Water tank(drinking water
with tracer)
High pressurewater pump
Pressure-manometer
Flat Jet(stainless steel)
Adjustableinjector(stainless steel)
Tube (stainless steel)
Spray gun
Stainless steel water tankwith stirring motor(drinking water,
anorganic tracer, Celite/ substance-mixture)
Myriophyllum
HQI-D 2000W
HQI-D 400W
UV-B 40WUV-A 36W
2 x Biolux 58W 2 x Biolux 58W
UV-B 40WUV-A 36W
AnalysisAnalysis by GC-MS(SIM) after solid phase extraction (ENV) and
derivatisation (PFB-Br).
Fate model
1,7 d System 8 d
Pond 4, 11°C+Celite, - UV
System 38 d
OECD Hydrolysis
System
OECD Photodeg.
System
Pond 3, 21°C+Celite, +UV
Pond 2, 21°C+Celite, -UV
Pond 1, 21°C-Celite, -UV
DT50Hydrolysis
1,3 d
1,1 d
DT50Photodeg.
-
-
-
-
9,7 d
DT50System
2,1 d
14 d
16 d
Pond 4, 11°C+Celite, -UV
OECD 111 25°C,Hydrolysis
OECD 316Photodeg.
1,7 d
5,5 d
2,9 d (pH 9)
8,2 d
38 d
-
15,2 d
2,7 d77 d *
M1 Sink Water(Volatisation, Metabolites)
M1 Water(Metilox® acid in
water)
P Sink Water(Volatisation, Metabolites)
P Water(Metilox ® in
Water)
M1 Sediment (Metilox ® acid in
sediment and biota)
P Sediment (Metilox ® in
sediment and biota)
M1 Sink Sediment(NER, Mineralisation,
Metabolites)
P Sink Sediment(NER, Mineralisation,
Metabolites)
k8 + kPhotodeg.
k1 (here: Hydrolysis)
k6 (Sorption) k5 (Desorption) k3 (Desorption)k2 (Sorption)
k7 ~ 0
k4k7
k9
Degradation
Degradation
System
250 300 350 400 450 5000
2
4
6
8
10
12
14
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0.1
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Spec
tral
irra
dia
nce
[µW
*cm
-2
*nm
-1
]
Wavelength [nm]
Pond -UV Pond +UV Metilox 2 mg/L Metilox acid 2 mg/L
UV-B UV-A
Abso
rban
ce
0 20 40 60 80 100 1200
10
20
30
40
50
60
70
80 Water
Metilox ModelMaker Metilox acid ModelMaker
Quota
inw
ater
rela
tive
toto
tali
nput[%
]
Days after application
0 20 40 60 80 100 1200.0
0.2
0.4
0.6
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1.0 Sediment
Metilox ModelMaker Metilox acid ModelMaker
Quota
inse
dim
entre
lative
toto
talin
put[%
]
Days after application0 20 40 60 80 100 120
0
25
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100
-Celite, -UV 21°C SFO +Celite, -UV 21°C SFO
95 % CL +Celite, +UV 21°C SFO +Celite, -UV 11°C SFO
Met
ilox
+M
etilo
xac
idre
lative
tost
artm
ass
[%]
Days after application
Simulationsanlage
FSA
Fließ- und Stillgewässer-
