Tricarbonyl(methylcyclopentadienyl)manganese

Biodegradation in water and sediment: simulation tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: sediment simulation testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Not mentioned

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Methodology similar to OECD 308 with sufficient information presented to assess reliability.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 308 (Aerobic and Anaerobic Transformation in Aquatic Sediment Systems)

Deviations:

yes

Remarks:

Aerobic transformation not tested.

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Not applicable

Radiolabelling:

no

Oxygen conditions:

anaerobic

Inoculum or test system:

natural sediment

Details on source and properties of surface water:

Not applicable

Details on source and properties of sediment:

Sediment samples were obtained from a slow-moving stream (Beaver Dam Creek) located near Athens, Georgia.
For more data, please refer to Table 1.

Details on inoculum:

no data

Duration of test (contact time):

ca. 60 d

Initial conc.:

1 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

test mat. analysis

Details on study design:

Anaerobic reduction: Reduction kinetics were studied using batch methods in anaerobic sediment-water mixture or an aquifer solids-water mixture. Reaction vessels used were 16 x 125 mm borosilicate screw-cap culture tubes sealed with alumnium foil-faced butyl septa. Dry aquifer solids were gently mixed with aqeous mmt solutions of various concentrations at weight ratios of 1:0.8, 1:1 and 1:1.2. Redox potential were monitored with Eh measurements. Reaction mixture vessels were sealed and stored in the dark at 25 ± 2°C.

Test performance:

There appeared to be no reaction of mmt in the Beaver Dam bottom sediment after 60 d; no products were observed by GC-MS, and the small loss of mmt was noted to potentially be from experimental error.

Compartment:

other: water / sediment, material (mass) balance

Remarks on result:

other: Not determined.

Remarks on result:

other: Not determined

Compartment:

sediment

Remarks on result:

other: No half-life was calculated since no biodegradation was observed during the 60 day experimental period.

Transformation products:

no

Details on transformation products:

No degradation products were observed by GC-MS.

Evaporation of parent compound:

not measured

Volatile metabolites:

no

Residues:

no

Details on results:

No biodegradation was observed within the test duration of 60 days.

Validity criteria fulfilled:

not specified

Conclusions:

mmt can be persistent in natural aquatic environments, like sediments, in the absence of light. No (bio)degradation of mmt occurred during the 60 d exposure period.

Executive summary:

The study performed was similar to an OECD 308 guideline study. In order to determine anaerobic (bio)degradation of mmt in sediments, samples were collected from a slow-moving stream, Beaver Dam Creek. The sediment samples were exposed to 1 mg/L mmt (1 ppm) for 60 days with the test performed in the dark to prevent photolysis. At the end of the 60 days test period no (bio)degradation was observed, and the calculation of mmt's half-life was not possible. .

Based on the findings, it was determined thsat mmt can be persistent in natural aquatic environments, like sediments, in the absence of light.

Additional information

The half-life of mmt was not determined due to the absence of biodegradation during the 60 day exposure period.