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Environmental fate & pathways

Biodegradation in soil

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Description of key information

In tests on biological degradation in soil and compost, Tributyl-O-acetylcitrate was found to be readily biodegradable.

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Additional information

From several test results on mineralization in soil and compost, acetyl tributyl citrate can be classified as readily biodegradable in these substrates. The reduced degradation in one test with compost can probably be attributed to deficiencies in the applied method.

In a test on biodegradation in soil according to EPA OPPTS 835.3300 tributyl-O-acetylcitrate was found to be readily biodegradable. Decay rates decreased as a function of substrate concentration. However, ATBC is considered to be readily biodegradable at concentrations <3.2 mg C/g soil, based on >60% ThCO2, observed within a 10- to 14-day window following the lag phase.

In a non-specific method (UML-7645) for measuring substance depletion in soil, mineralization of the test substance by day 52 reached approximately 128, 125, 90 and 83% (based on ThCO2) for the 40, 80, 160 and 300 mg C-treatments, respectively.

In a Respirometry test in ‘static’ compost biometer system, ATBC was found to be readily biodegradable. At the higher test concentration (10.8 mg C/g soil), conversion of substrate-C into CO2 exceeded 50% (based on ThCO2) in about two weeks and 60% ThCO2 in about three weeks. At the lower test concentration (1.90 mg C/g soil), conversion of substrate-C into CO2 exceeded 60% ThCO2within about four days following the lag period.

In a test on ultimate biodegradation in actively aerated compost, mineralization of the test substance reached 37% (based on ThCO2 in 45 days. Microbial degradation of the test substance in the compost was, in part, retarded at the very high substrate loading used in this test. Further, problems with the aeration system were reported, particularly in the last two weeks of the test. Despite randomization in bioreactor placement, the reduced air supply due to NaOH crystal formation in the air distribution manifold became more significant along the manifold and throughout the exposure period, potentially influencing the results achieved during this study.