Propiophenone

Biodegradation in water and sediment: simulation tests

Administrative data

Endpoint:

biodegradation in water and sediment: simulation testing, other

Remarks:

groundwater

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

Comparison of Occurrence and Rates of Chemical Biodegradation in Natural Waters.

Author:

VaishnavD. D. and Babeu L.

Year:

1987

Bibliographic source:

Bull. Environ. Contam. Toxicol. (1987) 39:237-244

Materials and methods

Principles of method if other than guideline:

The experiment was conducted to measure and compare the degradation of organic chemical in ground, Lester river and Superior harbor waters by autochthonous micro-organisms. Biodegradation in each water was separately measured by the BOD technique (APHA 1980).

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

1-phenylethanone

IUPAC Name:

1-phenylethanone

Radiolabelling:

no

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

natural water: freshwater

Details on source and properties of surface water:

- Details on collection:
Ground water (GW) was sampled at the tap of a 42 m submersible-pump well located about 12 km north of Lake Superior, located in southern St. Louis County, MN. Prior to sampling, approximately 20 l of the water were voided.
River water (RW) was collected by surface (upper 15 cm) sampling from the Lester River, located in southern St. Louis County, MN.
Superior harbor water (HW) was sampled (upper 15 cm) at a station located about 0.5 km northeast of Barker's Island in the main navigation channel of Superior Bay, Superior, WI.
- Sampling period: all water samples were procured between May-July, 1985, during periods of similar meteorological conditions.
- Storage conditions: each water was filtered by gravity flow through 1-cm-thick cotton layer. Aeration was started within 1 h of sampling and continued for about 24 h, at which time the water was used in biodegradation tests.
- Storage length: 24 hours.
- Waters analysis: microbiological and physicochemical analyses of the waters were made using unfiltered and filtered samples, respectively. The latter were done in triplicate by standard methods (APHA 1980) and included pH, conductivity, nephelometric turbidity, total, dissolved and suspended solids, alkalinity, hardness, nitrite/ nitrate, ammonia, and orthophosphate.

Details on inoculum:

- Colonies: the agar plates with ground water sample produced seven types of morphologically distinct colonies and those with the river water sample produced six types of distinct colonies. Similarly, the bacterial concentration in harbor water was distributed among five types of morphologically diverse colonies.
- Biomass concentration used in test: standard plate counts on nutrient agar showed that bacterial concentrations in ground, river and harbor waters were 55, 420 and 310 cells/ml, respectively.

Duration of test (contact time):

20 d

Initial test substance concentration

Initial conc.:

0 - 3.2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Volume of test solution/treatment: a test chemical was added into 20 ml of water contained in a 300-ml BOD bottle. The bottles were filled to capacity with the same water, sealed and incubated.
- Test temperature: 21 ± 3 °C
- Test concentrations: 0.0, 0.8, 1.6 and 3.2 µl/l. Test concentrations used were below the chemical water solubility.

TEST SYSTEM
- Number of culture flasks/concentration: 2 bottles per concentration.
- Measuring equipment: Dissolved oxygen (DO) concentrations were determined using a YSI 54 oxygen meter equipped with a self-stirring probe. The DO concentrations in randomly selected bottles were measured by the azide modification of the iodometric method (APHA 1980).

SAMPLING
- Sampling frequency: Dissolved Oxygen (DO) concentrations at 0, 5, 10, 14 or 15, and 20 days of incubation were determined.

CONTROL AND BLANK SYSTEM
Controls to assess the water quality were included.

EVALUATION
Test BOD values showing unadjusted DO depletions of at least 2 mg/l and residual DO of at least 1 mg/l were acceptable. These values were adjusted for the water blank and then used for calculating the mean BODs from duplicate tests .
The latter were transformed to mmol BOD/mmol chemical for each applicable concentration and subsequently used for computing the percents of theoretical (Th) BOD.The mean BOD values obtained at two different concentrations were also compared to determine the order (n) of chemical biodegradation process.

Results and discussion

% Degradation

Remarks on result:

not measured/tested

Half-life of parent compound / 50% disappearance time (DT50)

Half-life of parent compound / 50% disappearance time (DT50) 1

Compartment:

natural water: freshwater

DT50:

32 d

Type:

(pseudo-)first order (= half-life)

Remarks on result:

other: ground water (rate constant 0.022)

Half-life of parent compound / 50% disappearance time (DT50) 2

Compartment:

natural water: freshwater

DT50:

8 d

Type:

(pseudo-)first order (= half-life)

Remarks on result:

other: Lester River (rate constant: 0.083)

Half-life of parent compound / 50% disappearance time (DT50) 3

Compartment:

natural water: freshwater

DT50:

4 d

Type:

(pseudo-)first order (= half-life)

Remarks on result:

other: Superior harbor (rate constant: 0.155)

Transformation products:

not measured

Details on results:

Test item biodegraded in all three waters, however the % ThBODs varied among the water types. It was found that test item followed first-order kinetics and thus, chemical half-lives were estimated from the first-order biodegradation rate constants.Variations among chemical biodegradation rates in natural waters can arise from the differences in physicochemical and/or microbial composition of waters.

Chemical half-live was the shortest in the harbor water, followed by the river and ground waters. Increased chemical biodegradation rates in the harbor water could have been due to the water fertility and/ or the presence of microorganisms that were pre-exposed to test or similar chemicals. The latter was possible because trace levels of organic acids, aldehydes, ketones, amines, esters, alcohols, phenols, polychlorinated biphenyls, and polynuclear aromatic hydrocarbons have been detected in the harbor water and sediment samples.

Applicant's summary and conclusion

Conclusions:

The test item is biodegradable (first-order biodegradation rate).

Executive summary:

The experiment was conducted to measure and compare the degradation of organic chemical in ground, Lester river and Superior harbor waters by autochthonous micro-organisms. Biodegradation in each water was separately measured by the BOD technique (APHA 1980).

Test item biodegraded in all three waters, however the % ThBODs varied among the water types. It was found that test item followed first-order kinetics and thus, chemical half-lives were estimated from the first-order biodegradation rate constants.

Variations among chemical biodegradation rates in natural waters can arise from the differences in physicochemical and/or microbial composition of waters. Chemical half-live was the shortest in the harbor water, followed by the river and ground waters. Increased chemical biodegradation rates in the harbor water could have been due to the water fertility and/ or the presence of microorganisms that were pre-exposed to test or similar chemicals. The latter was possible because trace levels of organic acids, aldehydes, ketones, amines, esters, alcohols, phenols, polychlorinated biphenyls, and polynuclear aromatic hydrocarbons have been detected in the harbor water and sediment samples.

Conclusion

The test item is biodegradable (first-order biodegradation rate).