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Ecotoxicological information

Toxicity to soil microorganisms

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Administrative data

Endpoint:
toxicity to soil microorganisms
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Not GLP standard study, but field study well described

Data source

Reference
Reference Type:
publication
Title:
Long-term effects of different inorganic pollutants on nitrogen transformations in a sandy cambisol.
Author:
Wilke BM.
Year:
1989
Bibliographic source:
Biology and Fertility of Soils 7: 254-258.

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Long term effects of vanadium on N-mineralisation and nitrification studied in a sandy cambisol, in a field study after 8 or 9 years following contamination.
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
not specified
Details on test material:
no detail given

Sampling and analysis

Analytical monitoring:
yes

Test substrate

Vehicle:
not specified
Details on preparation and application of test substrate:
APPLICATION OF TEST SUBSTANCE TO SOIL
In 1975 the soil was placed in concrete frames of 1 × 1 × 1 m (1 m3). The underlying material was a layer of peat (about 15 cm thick).

All compounds were mixed with the A horizon in one to three additions, depending on the amount added, in 1975 and 1976. All treatments were carried out fourfold in two concentrations, 16 controls remaining untreated. In the following years tomatoes, potatos, beans, rye, wheat, barley, and rape seed were grown on the plot. Weeds were removed occasionally. The soil was dug up twice a year in spring and autumn.

Test organisms

Test organisms (inoculum):
soil

Study design

Remarks:
8-9 years

Test conditions

Test temperature:
field study
Organic carbon content (% dry weight):
1.2%
Nitrogen content (% dry weight):
0.08%
Details on test conditions:
TEST SYSTEM
- Testing facility:
The A horizon (0-25 cm) of a sandy cambisol from a field trial of the Biologische Bundesanstalt (Berlin-West) was used. It contained 9°70 clay, 12°/0 silt, 79070 sand, 1.2°/0 organic C, 0.080/0 total N and had a pH (CaC12) of 6.0. The cation exchange capacity was 10.3 mEq/100 g.

All treatments were carried out fourfold in two concentrations, 16 controls remaining untreated.

- Depth of sampling: 0-25 cm
- Soil texture; sand
- % sand: 79
- % silt: 12
- % clay: 9
- Soil taxonomic classification: sandy cambisol
- pH (in water): 6.0
- Cation exchange capacity (mmol/kg): 10.3 mEq/100g

EFFECT PARAMETERS MEASURED:
- soil content in vanadium
- N mineralisation; 3 ml deionized water was added to a 10-g sample of field-moist soil in a 100-ml Erlenmeyer flask and incubated at 25 °C. After 28 days mineralised NH4+ and NO3- were extracted with 50 ml of 1 M K2SO 4 and measured photometrically as described by Beck (1983). All experiments were carried out with six replicates. Two replicates were frozen at the beginning of the incubation to determine initial NH4+ and NO3-.tio
- inhibition of mineralisation
- nitrification: determined according to Beck (1976). Ten grams of soil were saturated with 3 ml distilled water in 100-ml flasks and 1 ml of a 1% (NH4)2SO 4 solution was added as the NH4+ source. The flasks were stoppered and incubated at 25 °C.
After 21 days mineralised NH4+ and nitrified NO3- were determined as described above. Nitrification was expressed as the percentage of mineralised NH4+.
Nominal and measured concentrations:
100 mg/kg for V+
400 mg/kg for V2+
Reference substance (positive control):
no

Results and discussion

Effect concentrationsopen allclose all
Dose descriptor:
NOEC
Effect conc.:
400 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
V2+
Basis for effect:
other: amount of nitrogen (NH4+ and NO3-) mineralised
Remarks on result:
other: measurements after 8-9 years application of test substance
Dose descriptor:
NOEC
Effect conc.:
100 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
V+
Basis for effect:
nitrate formation rate
Remarks:
nitrification as a percentage of mineralized NH4+
Remarks on result:
other: measurements after 8-9 years application of test substance
Dose descriptor:
other: LOEC
Effect conc.:
400 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
V2+
Basis for effect:
nitrate formation rate
Remarks:
nitrification as a percentage of mineralized NH4+
Remarks on result:
other: measurements after 8-9 years application of test substance
Details on results:
The results of these long-term experiments are in contrast to most results of short-term laboratory studies. As N mineralisation in the laboratory was negatively affected by most pollutants tested, it must be assumed that nitrifying bacteria became adapted to these compounds in the field, over a longer period of time.
Concerning nitrification, vanadium failed to inhibit it, but 400 mg V/kg added to soil stimulate nitrification with 20% more than in the control soil.

Applicant's summary and conclusion

Validity criteria fulfilled:
not applicable
Executive summary:

Long term effects of vanadium on N-mineralisation and nitrification were studied in a sandy cambisol, in a field study after 8 or 9 years following contamination.

As N mineralisation in the laboratory was negatively affected by most pollutants tested, it must be assumed that nitrifying bacteria became adapted to these compounds in the field, over a longer period of time.

Concerning nitrification, vanadium failed to inhibit it, but 400 mg V/kg added to soil stimulate nitrification with 20% more than in the control soil.

The effect values deducted were;

V2+ NOEC= 400 mg/kg added for N-mineralisation

V+ NOEC= 100 mg/kg added for nitrification

V2+ LOEC= 400 mg/kg added for nitrification (stimulation)