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Additional ecotoxological information

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Administrative data

Endpoint:
additional ecotoxicological information
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
June 2005, 2007 and 2008
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Field study of water body exposure to aluminium chloride, generally outside of the scope of standard regulatory assessment methods but useful supporting evidence of the impact of large scale exposure of ecosystems to aluminium salts

Data source

Reference
Reference Type:
publication
Title:
Seven years from the first application of polyaluminium chloride in the Czech republic - effects on thytoplankton communities in three water bodies
Author:
Jancula D, Marsalek B
Year:
2012
Bibliographic source:
Chemistry and Ecology 28 (6) pp 535-544

Materials and methods

Principles of method if other than guideline:
Field studies further to treatment of Czech waterbodies to reduce algae populations below the local hygiene limit
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
other: solution
Details on test material:
no data

Results and discussion

Any other information on results incl. tables

All the lakes had pHs of approxiamtely 8 and were stable over the study period (approximately one month for each year the water bodies were treated). Temperatures varied from 20 to 30°C and oxygen concentrations from 60 to 110%.

Machovo lake, 2005. Immediately after treatment Chla concentration decreased from 33 -36 µg/L to 11 -14 µg/L over the whole lake. the assembalge composition remained unchanged. Cyanobacteria was limited thereafter due to being outcompeted by green algae thanks to certain cliamtic coinditions and nutrient availability. Most zooplankton (90%) decreased after treatment returning to their original levels six weeks after treatment.

Small lagoon of the Nové Mlyny reservoir, 2006: Chla between 7 -9 µg/L dominated by the Cyanobacterium, Aphanizmenon gracile. Concentrations of Chla dropped to 4 -5µg/L immediately after treatment but returned to 9 µg/L 3 days later increasing over the Summer. No dissolved microcystins were found in the water.

The lagoon was retreated in 2007: Chla was 5.9 µg/L. Cyanobacteria Chla concentration reduced by approximately 70% while diatoms and cryptophaetae decresaed by 28%. This was considered to be due to the smaller cell size of the cyanobacter which would be expected to be removed more efficiently than the other species. Recovery of total algae occurred within 2 weeks of treatment.

The lagoon was retreated in 2008: The chla concentration was approximately 9 µg/L. Total algae decreased to 4.3 µg/L. Phytoplankton recovered within one month.

Plumlov reservoir, 2007: The chla concentration decreased from 12.4 to 4.7 µg/L. One week later Chla levels reached 31.4 µg/L. Aquatic invertebrate levels decreased by 91% on the third day after application. Cladocera was the most sensitive zooplankton family and started to increase again after one week.

Likely explanations for the impact on invertebrates (notably cladocerans) is provided: clogging of filtering apparatus by the particles of test substance and subsequent lack of food because of coagulation of phytoplankton and capture of organisms into the floccules. The authors state that toxicity of the aluminium is considered an unlikely cause of organism number reduction but cannot be neglected. The authors also state that while they did not directly monitor fish populations during their work, they never observed fish mortality either during or after application.

In the case of this study the lack of long term effects as testified to by the relatively rapid recoveries of the ecosystem in each case suggest that concentrations of aluminium reduce below levels that may cause physical or toxic effects to phyto- or zooplankton within a few days (at most), at least at the pHs of these water bodies, which were all around 8.

Applicant's summary and conclusion

Executive summary:

Three sites received single treatments with PAX-18 to reduce algal blooms for public hygiene purposes by injecting the substance directly below the surface of the water bodies to obtain final concentrations of 3.45 mgAl/L (Machovo lake, 2005), 6.5 and 5.0 mgAl/L (small lagoon of the Nové Mlyny reservoir, 2006 and 2007 respectively and 2008) and 6 mgAl/L (Plumlov reservoir, 2007). The pH, temperature and oxygen and Chlorophyll a concentrations were measured in situ. Zooplankton was sampled. Data were statistically analysed using ANOVA and Dunnett's tests.

All the lakes had pHs of approxiamtely 8 and were stable over the study period (approximately one month for each year the water bodies were treated). Temperatures varied from 20 to 30°C and oxygenc oncentrations from 60 to 110%.

Machovo lake, 2005. Immediately after treatment Chla concentratiion decreased from 33 -36 µg/L to 11 -14 µg/L over the whole lake. the assembalge composition remained unchanged. Cyanobacteria was limited thereafter due to being outcompeted by green algae thanks to certain climatic coinditions and nutrient availability. Most zooplankton (90%) decreased after treatment returning to their original levels six weeks after treatment.

Small lagoon of the Nové Mlyny reservoir, 2006: Chla between 7 -9 µg/L dominated by the Cyanobacterium Aphanizmenon gracile. Concentrations of Chla dropped to 4 -5µg/L immediately after treatment but returned to 9 µg/L 3 days later increasing over the Summer. No dissolved microcystins were found in the water.

The lagoon was retreated in 2007: Chlawas 5.9 µg/L. Cyanobacteria Chla concentration reduced by approximately 70% while diatoms and cryptophaetae decresaed by 28%. This was considered to be due to the smaller cell size of the cyanobacter which would be expected to be removed more efficiently than the other species. Recovery of total algae occurred within 2 weeks of treatment.

The lagoon was retreated in 2008: The chla concentration was approximately 9 µg/L. Total algae decreased to 4.3 µg/L. Phytoplankton recovered within one month.

Plumlov reservoir, 2007: The chla concentration decreased from 12.4 to 4.7 µg/L. One week later Chla levels reached 31.4 µg/L. Aquatic invertebrate levels decreased by 91% on the third day after application. Cladocera was the most sensitive zooplankton family and started to increase again after one week.

Likely explanations for the impact on invertebrates (notably cladocerans) is provided: clogging of filtering apparatus by the particles of test substance and subsequent lack of food because of coagulation of phytoplankton and capture of organisms into the floccules. The authors state that toxicity of the aluminium is considered an unlikely cause of organism number reduction but cannot be neglected. The authors also state that while they did not directly monitor fish populations during their work, they never observed fish mortality either during or after application.

In the case of this study the lack of long term effects as testified to by the relatively rapid recoveries of the ecosystem in each case suggest that initially significant concentrations of aluminium reduce below levels that may cause physical or toxic effects to phyto- or zooplankton within a few days (at most), at least at the pHs of these water bodies, which were all around 8.