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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:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Study period:
2015 or prior
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Justification for type of information:
Read across is based on the category approach. Please refer to attached category document.

Data source

Reference
Reference Type:
publication
Title:
Biodegradation screening of chemicals in an artificial matrix simulating the water-sediment interface
Author:
E Baginska, A HaiB, K Kummerer
Year:
2015
Bibliographic source:
Chemosphere 119: 1240-1246

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 308 (Aerobic and Anaerobic Transformation in Aquatic Sediment Systems)
Principles of method if other than guideline:
This word was based on OECD guideline 308. Increased reproducibility was achieved by creating an artificial and standardized medium, based on the existing OECD guidelines OECD 302C, 301D, and 218.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Specific details on test material used for the study:
Purchased from Carl Roth, Germany
Radiolabelling:
no

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
artificial sediment
Details on source and properties of sediment:
Artificial sediment (OECD guideline 218 (OECD, 2004)) was composed of kaolin clay (5% dry weight), quartz sand (grain size 0.8–0.2 mm; 92% dry weight), sphagnum moss peat (2% dry weight), and calcium carbonate (<0.1% dry weight).
Details on inoculum:
Inoculum (OECD guideline 302C (OECD, 1981)) prepared from mixed sources of surface water and sediment as well as effluent from sewage treatment plant. Since the low bacterial density was suspected in WST the mineral medium composition, which contained of mineral salts, trace elements, and growth factors, was based on the OECD guideline 301D (OECD, 1992)) where low bacterial density is used.
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
64.22 mg/L
Based on:
test mat.
Initial conc.:
32 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
other: Pressure change in closed vessel
Details on study design:
Each of the series were placed in glass bottles (1 L) equipped with two septum sealed bottle nozzles . Aniline and test compound concentration in all series was 40 mg/L expressed as theoretical oxygen demand (ThOD). All assays were incubated in the dark at 20 degrees C in closed vessels. Test duration was 28 d. The water phase in the bottles was stirred to improve water exchange between water and sediment phase but not vigorously to avoid disturbance of the sediment. Water to sediment ratio was 1:5. During the experiment pressure change inside the vessels are measured by pressure sensors using OxiTop system (WTW Weilheim, Germany).
Reference substanceopen allclose all
Reference substance:
aniline
Remarks:
4, 10, 20, 40 mg/l; 99.96 mg/l
Reference substance:
diethylene glycol
Remarks:
80.28 mg/l
Reference substance:
other: sodium acetate
Remarks:
20.16 mg/l

Results and discussion

Test performance:
Aniline in all four concentrations achieved similar
rates and levels of biodegradation; 64 ± 17%; 80 ± 4%; 62 ± 10%;
68 ± 84% for 40, 20, 10, and 4 mg L1 respectively (Supplementary
material Fig. S1). With increasing concentration, the measurement
was more stable and clear biodegradation curves were observed.
With the exception of the highest concentration, the lower the concentration the higher the standard deviation was observed. Best values in regards to standard deviation were obtained at a test concentration of 20 mg/l aniline which corresponds to a ThOD of 48.2 mg/l. Optimum test substance concentration was therefore decided to be 40 mg/l in terms of ThOD.
% Degradation
% Degr.:
77
Parameter:
other: based on pressure development from CO2
Sampling time:
28 d

Applicant's summary and conclusion

Conclusions:
The WST provides testing conditions (presence of water–sediment interface) that are more complex than those in standardized screening tests, where only biodegradation performed by bacteria suspended in water phase is taken into account. Under the conditions in this study, 77 and 78% degradation of 64.22 and 32 mg/l DEG, respectively, was observed in 28 days, with lag times of 4 and 5 days.