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Ecotoxicological information

Toxicity to aquatic plants other than algae

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Administrative data

Endpoint:
toxicity to aquatic plants other than algae
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1991 - 1993
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Peer reviewed techincal publication that meets basic scientific principles. The study did not follow a standard procedure, boron additions were discontinuous, and exposures were not well characterized.

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1995

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Reeds were planted in pots and different boron concentrations have been added to the water. Experiments were conducted over two growing seasons and in pots with and without gravel substrates. No standard procedure existed for this type of study. Boron was added to water used to make up losses in the pots, so it was added on an irregular schedule. Boron content of water and plants was measured.
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent

Sampling and analysis

Analytical monitoring:
yes

Test solutions

Vehicle:
no

Test organisms

Test organisms (species):
other: Phragmites australis
Details on test organisms:
TEST ORGANISM
- Common name: Reed
- Source: On 0.08.1991 Phragmites australis plants, which were taken from a naturally occurring reed bed near Jena, together with rootballs and attached moist soil substrate (in all about 6.5 kg/vessel) were inserted into plastic vessels without outlets (height 25 cm, inner diameter 20 cm, volume 7,850 cm³; in spring 1993 transferred to larger 10 litre containing plastic buckets, and addition of 1 kg soil/vessel with 0.83 ppm B).
To standardise the different moisture levels of the substrate, distille water was added to the vessels to a level of 20 cm. In this way the substrate became fully sturated with water and a 3 cm additional water level was achieved. From the top of the water level there remained 2 cm free space to the top of the vessel.
Four weeks after the vessels were set up, they received only 0.2 g/vessel as NH4NO3. Since the plants with attached soil balls were placed into the vessels and the plants first had to adjust to the new growth conditions, no further nutrients were added during 1991.
The quantities of water consumed from time to time were supplemented by distilled water during the 1992 and 1993 experiments and at given time intervals with the corresponding nutrient solutions and/or the anticipated supplemental doses of boron.
The variously developed reed stalks during 1991 were cut off at the end of the vegetation period without any evaluation, and the plants for the experimental start in 1992 were moved under cover over winter.
In the developmental stage of the reeds during the 1992 growth period, the vessels from 13.05.92 (first dose) up to 21.09.92 (last dose) received the following doses of nutrients :
-12 N-doses as NH4NO3, respectively Ca(NO3)2, in all 5.26 g N/vessel
-5 P-doses as KH2PO4, in all 1.205 g P/vessel
-5 K-doses in the form of KH2PO4 and KCl, in all 2.01 K/vessel
-5 Mg-doses as MgSO4.7H2O, in all 1.602 g/Mg/vessel
and
-2 mincronutrient doses (Mo, Cu, Fe, Mn, Zn) as the customary A-Z-micronutrient-hydroponic solution of the Institute for Plant Nutrition, Jena

In the follow-up experimental year 1993, in which the experimental (plants) were cropped and the yields determined in September, all vessels during the period from 26.03.93 (first dose) up to 28.07.93 (last dose) received the following doses of fertiliser :

-8 N-doses as NH4NO3, respectively Ca(NO3)2, in all 3.8 g N/vessel
-4 P-doses as KH2PO4, in all 1.30 g P/vessel
-5 K-doses in the form of KH2PO4 and KCl, in all 2.38 K/vessel
-5 Mg-doses as MgSO4.7H2O, in all 1.30 g/Mg/vessel
and
-2 mincronutrient doses (Mo, Cu, Fe, Mn, Zn) as the customary A-Z-micronutrient-hydroponic solution of the Institute for Plant Nutrition, Jena

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
16 wk

Test conditions

Nominal and measured concentrations:
Nominal concentrations : 0, 0.5, 1.0, 2.0, 4.0, 8.0, 16.0, 32.0
Details on test conditions:
In this first experiment, the B-fertilisation variants were set up from "without B-addition" = 0 to 16 mg B/L with 4 vessels per variant. B, in form of boric acid, was added together with the make-up water. It must be mentioned that the "0-variant" depended on the state of the soil substrate, which must have contained very small amounts of B. During the year 1991 the boron-variants received B-doses only on 07.08, and on 13.09. Starting on 05.02.1992 and until 13.10., dependent upon the analytically determined B-residual content of the liquid phase in the vessel, 13 boron doses were added at intervals of about 4 weeks to start with and later at one to two weeks. Because of the rapid uptake of boron by the reeds during 1993, the intervals of the 23 additions between 31.03. to 26.08.1993 were reduced to 6 - 7 days, in order to avoid too rapid a drop of the original B-concentration.
At the end of the vegetation period in 1992 in October and already at the end of September 1993 the shoots of the plants were harvested and the following points ascertained,
-number of stalks per vessel:
-average height of growth of plants per vessel
-yield of dry substance of the stalks and leaves;
-after the end of the 1993 experiment the dry substance weight of the roots of a few vessels, because of the difficulty of making an exact determination on roots.

Results and discussion

Effect concentrations
Duration:
16 wk
Dose descriptor:
NOEC
Effect conc.:
4 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Basis for effect:
growth rate

Applicant's summary and conclusion