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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: not according to GLP, enough details provided to establish reliability
Justification for type of information:
For Weight-of-Evidence Justification please refer to justification documentation in IUCLID Chapter 13.
Cross-reference
Reason / purpose for cross-reference:
assessment report
Remarks:
Justification for Weight-of-Evidence approach

Data source

Referenceopen allclose all

Reference Type:
publication
Title:
Tolerance of estuarine benthic diatoms to high concentrations of ammonia, nitrite ion, nitrate ion and orthophosphate
Author:
Admiraal W.
Year:
1977
Bibliographic source:
Marine Biology 43:307-315
Reference Type:
publication
Title:
OECD SIDS Nitrates Category
Author:
OECD
Year:
2007
Bibliographic source:
SIDS Initial Assessment Report For SIAM 25 , Helsinki, Finland, 16-20 October, 2007 - Nitrates Category

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Ten cultures of benthic diatoms were isolated from field samples from Eems Dollard Estuary (The Netherlands). The growth rate was determined as % chlorophyll a in diatoms grown in an artificial sea water medium containing increasing amounts of potassium nitrate. The test substance concentration was controlled using an auto-analyzer. The salinity of the test medium was kept constant at 15 or 37% depending on the algal strain tested. The climate room was maintained at 12ºC, with a quantum irradiance of 85 NE.m-2.sec-1 (4000 lux) from extra cool-white fluorescent tubes and a light period of 16 hours/day. In addition, the pH of the medium increased with a maximum of 0.4 after 24 hours incubation, most likely due to photosynthesis.
GLP compliance:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Potassium nitrate
EC Number:
231-818-8
EC Name:
Potassium nitrate
Cas Number:
7757-79-1
Molecular formula:
HNO3.K
IUPAC Name:
potassium nitrate
Details on test material:
- Name of test material (as cited in study report): potassium nitrate
purity: not indicated

Sampling and analysis

Analytical monitoring:
yes

Test organisms

Test organisms (species):
other: several benthic diatoms; see results
Details on test organisms:
TEST ORGANISM
- Strain: benthic diatoms
- Source (laboratory, culture collection): isolated from field samples from Eems Dollard Estuary (The Netherlands).
-

Study design

Test type:
not specified
Water media type:
saltwater
Total exposure duration:
10 d

Test conditions

Test temperature:
The climate room was maintained at 12ºC.
Salinity:
The salinity of the test medium was kept constant at 15 or 37% depending on the algal strain tested.
Nominal and measured concentrations:
0.1 - 16.9 mmol/L
Details on test conditions:
OTHER TEST CONDITIONS
- Adjustment of pH: the pH of the medium increased with a maximum of 0.4 after 24 hours incubation, most likely due to photosynthesis.
- Photoperiod: quantum irradiance of 85 NE.m-2.sec-1 (4000 lux) from extra cool-white fluorescent tubes and a light period of 16 hours/day.
- Salinity (for marine algae): The salinity of the test medium was kept constant at 15 or 37% depending on the algal strain tested.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Chlorophyll measurement: the growth rate was determined as % chlorophyll a

Results and discussion

Effect concentrations
Key result
Duration:
10 d
Dose descriptor:
EC50
Effect conc.:
> 1 700 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
Most of the species (8 out of 10 tested, e.g. Navicula arenaria, Nitzschia dubiformis etc.) grew well at nitrate concentrations up to 16.9 mmol/L (=1.7 g/L). Nitrate was only clearly inhibitory to Nitzschia dubiformis and Amphiprora c.f. paludosa only at the highest test concentration.

Any other information on results incl. tables

Relative rates (as % chlorophyll a) were:

                                                           Nitrate concentration (mmol/L)

           Species                                    0.1       0.68     3.38     6.75     16.9     

           Navicula arenaria                  80        95        100      107      94

           Nitzschia c.f. dissipata            84        94        100      83        67

           Nitzschia dubiformis               67        84        100      100      34

           Nitzschia closterium                54        65        65        85        100

           Amphiprora c.f. paludosa       71        89        86        100      39

           Stauroneis constricta              52        92        98        102      100

           Navicula cryptocephala          61        82        73        100      84

           Navicula salinarum                 65        73        89        100      86

           Gyrosigma spencerii               76        100      100      91        70

           Nitzschia sigma                       92        75        100      98        58

Applicant's summary and conclusion

Conclusions:
Most of the species grew well at nitrate concentrations up to 16.9 mmol/L (=1.7 g/L). Nitrate was clearly inhibitory to Nitzschia dubiformis and Amphiprora c.f. paludosa only at the highest test concentration.

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