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Environmental fate & pathways

Biodegradation in soil

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Reference
Endpoint:
biodegradation in soil: simulation testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1992
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
Sludge was applied by subsurface injection into 3 farms in West Sussex, UK, and samples collected over 105 days. Samples were then analyzed to determine the amount of test substance present.
GLP compliance:
no
Test type:
laboratory
Oxygen conditions:
not specified
Soil classification:
not specified
Details on soil characteristics:
SOIL COLLECTION AND STORAGE
- Geographic location: 3 farms in West Sussex, UK, collected over 105 days
- Collection procedures: Collected using a 200 mm screw auger, each field sampled 25 times
- Sampling depth (cm): 20
- Storage conditions: samples were used immediately after collection
- Soil preparation (e.g., 2 mm sieved; air dried etc.): dried, ground with mortar and pestle, then passed through a 1 mm sieve

Duration:
4 h
Parameter followed for biodegradation estimation:
test mat. analysis
Details on experimental conditions:
- Sludge was applied to the first field on May 19, 1989. The sludge was a 50/50 mixture of ray and anaerobically digested sludge. Sludge was applied to Field B on July 11, 1989 with raw sludge. Fields A and C had no history of sludge applications. Field B had sludge applied two years prior. Sludge was applied to Field C on August 30, 1989. Samples from Field A were collected 21 and 103 days after application, and from Field B after 56 days. Samples were collected from Field C on days 10, 22, and 55 after application. Sludge was applied by subsurface injection.
% Degr.:
98
Parameter:
test mat. analysis
Sampling time:
103 d
Key result
DT50:
15.3 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: Temperature not given
Transformation products:
not specified
Evaporation of parent compound:
not specified
Volatile metabolites:
not specified
Residues:
not specified
Details on results:
- The initial concentration of the test substance in Field B was 1.05 µg/g soil. After 56 days, the concentration was 0.15 µg/g soil. Field A had an initial test substance concentration of 1.19 µg/g soil, and removal of the substance was 98% after 103 days. Field C had an initial concentration of approx. 2.2 µg/g soil, which fell to approximately 0.2 µg/g soil after 55 days, with a half-life of 15.3 days. Due to dry weather, sampling of Fields B and A was limited, and half-lifes could not be calculated for those fields.
Conclusions:
The test substance was 98% removed from soils, with a half-life of 15.3 days.
Executive summary:

The purpose of this study was to determine the half-life of the test substance in soil that is treated with sludge. Sludge was applied by subsurface injection into 3 farms in West Sussex, UK, and samples collected over 105 days. Analysis of samples taken over time showed a 98% removal rate for the test substance. The half-life of the test substance was determined to be 15.3 days in sludge treated soils.

Description of key information

The half-life of the substance in soil that was treated with sludge was examined, and the half-life was determined to be 15.3 days.

Key value for chemical safety assessment

Half-life in soil:
15.3 d

Additional information

The half-life of the substance in soil that was treated with sludge was examined. Sludge was applied by subsurface injection into the soil of three farms in the UK, and samples were collected for analysis over 105 days. Results indicate that there was a 98% removal rate of the substance from the soil.

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