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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

Administrative data

Endpoint:
biodegradation in water and sediment: simulation testing, other
Type of information:
experimental study
Adequacy of study:
key study
Study period:
November 21, 2005 - Sept 5, 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
2006
Report Date:
2006
Reference Type:
other: Amendment No 1 to Study report GAB-011/7-92
Title:
Unnamed
Year:
2011
Report Date:
2011

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 308 (Aerobic and Anaerobic Transformation in Aquatic Sediment Systems)
GLP compliance:
yes (incl. certificate)
Remarks:
Statement of GLP compliance from Fraunhofer Institute for Molecular Biology and Applied Ecology

Test material

Reference
Name:
Unnamed
Type:
Constituent
Radiolabelling:
yes

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
natural water / sediment
Details on source and properties of surface water:
Two sediment systems from a river and a pond including sediment and natural water were collected and were equilibrated in incubation flasks for 15 – 19 days at 20 °C ± 2 °C in the dark.
Details on source and properties of sediment:
The sediment with the “fine texture” was sampled from a pond (“Heiminghausen”) located close to the testing facility. The sediment with the “coarse texture” was collected from the creek “Wenne” which is also located close to the testing facility.
The water/sediment systems collected from a creek and a pond were set up in cylindrical glass vessels and were equilibrated under laboratory conditions (20 °C ± 2 °C, in the dark) for 15 days (creek) and 19 days (pond) before application.
Duration of test (contact time):
ca. 120 d
Initial test substance concentration
Initial conc.:
1 908 µg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
radiochem. meas.
Reference substance
Reference substance:
other: Di(5-Propyl-benzo[1,3]dioxole)methane

Results and discussion

Half-life of parent compound / 50% disappearance time (DT50)open allclose all
Compartment:
water
DT50:
27 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: test system : pond
Compartment:
sediment
DT50:
165 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: test system : creek
Compartment:
sediment
DT50:
81 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: test system : pond
Compartment:
sediment
DT50:
36 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: test system : creek
Compartment:
entire system
DT50:
55 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: test system : pond
Compartment:
entire system
DT50:
54 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: test system : creek
Transformation products:
not specified
Details on results:
DT90: Water phase Pond: 91
DT90: Water phase Creek : 549

DT90 Sediment: Pond :269
DT90 Sediment creek: 121

DT50 value of PBO in the total system calculated by the computer program ModelMaker was 54.5 days
As individual processes the DT50 values were calculated to 67 days in the compartment water and 54 days in the compartment sediment (geom. mean of pond and creek system).
Results with reference substance:
Results valid

Any other information on results incl. tables

A total radioactivity balance and the distribution of radioactivity in every incubation flask was established at each sampling day. The following results were obtained.

• Total mean recoveries ranged between 90.1 and 97.8 % of initially applied radioactivity (ITR).

• Only trace amounts of volatile metabolites with low molecular weight and with basic character (never exceeding 0.6 % ITR as sum) were produced during the aerobic soil degradation of PBO in the water/sediment systems.

• Radioactivity trapped in 1 N NaOH indicated the production of 14CO2 and therefore mineralization of the test item during the incubation time of 120 days. The mineralization rate depended on the water/sediment system used for aerobic degradation of PBO. In the creek sediment system a relatively low mineralization rate was determined in the extent of 1.9 % ITR. A higher amounts (6.6 % ITR) of radioactivity detected in the sodium hydroxide traps were found during degradation in the pond sediment system.

After treatment during the first three days of incubation the radioactivity recovered in the water phase was high, amounting to a maximum of 92.7 % of the applied radioactivity for the pond system and 89.1 % for the creek system. During the further incubation, the total radioactivity in water rapidly decreased, whilst that in sediment increased. At the end of incubation the amounts of radioactivity remaining in the water were 16.5 % ITR for the pond system and 39.5 % ITR in the creek system.

• The radioactivity extractable from sediment increased rapidly during the first 14 days of incubation. Thereafter it remained relatively constant at a value of around 50 % in the pond system or decreased slightly in the creek system after a maximum value of 33.7 % ITR (62 days) to 30.8 % ITR. The amount of non-extractable radioactivity (NER) generally increased with increasing incubation time. After 120 days of incubation, the NER amounted to 24.2 % ITR in the pond system and 20.8 % ITR in the creek system.

• Parent compound PBO detected in the water phase decreased nearly continuously with increasing incubation time down to values of 0.1 % ITR in the pond system and 0.7 % in the creek system at 120 days after application. This decrease was compensated by an increase of PBO in the sediment extract. At the end of experiments 23.7 % ITR in the pond system and 17.2 % ITR in the creek system were identified as PBO. However, the amount of PBO in the entire system decreased with increasing incubation to endpoints of 23.8 % ITR in the pond and 17.9 % in the creek system, respectively.

• One main metabolite (M2) was detected. This metabolite amounted up to 21.4 % ITR (entire system) during the incubation of the pond system. In the entire creek system metabolite M2 correspond to a maximum value of 40.7 % ITR (100 days), which decreased to 36.1 % ITR at the end of experiment. Further metabolites were M1, which amounted to 7.6 % in the entire pond system and 4.4 % ITR in the entire creek system, and EN 1-93/3 which was detected in amounts of 6.1 % ITR in the total pond system and 5.5 % ITR in the entire creek system, respectively. Metabolite EN 1-101/4 was detected only in minor extent never exceeding 4.4 % ITR (in the entire system). Metabolites M1 and M2 are described below.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
Criteria OECD Guideline 308
Conclusions:
DT50:
Water phase Pond:27d,; Creek :165d
Sediment: Pond :81d; Creek:36d
Entire System Pond: 55d; Creek: 54d

DT90:
Water phase Pond:91d; Creek : 549d
Sediment Pond :269d; Creek: 121d
Entire system Pond: 182; Creek 179d