Dicopper chloride trihydroxide

Toxicity to terrestrial plants

Administrative data

Endpoint:

toxicity to terrestrial plants

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Already evaluated by the Competent Authorities for Biocides and Existing Substance Regulations.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

publication

Title:

Comparison of soil solution speciation and diffusive gradients in thin-films measurement as an indicator of copper bioavailability to plants

Author:

Zhao F-J, C.P. Rooney, H. Zhang and S.P. McGrath

Year:

2006

Bibliographic source:

Environ Toxicol Chem., Vol. 25, No. 3, pp. 733-742, 2006

Materials and methods

Principles of method if other than guideline:

This study was designed to determine wheter the variation in toxicity effect concentrations (tomato and barley) can be explained by the solubility or speciation of Cu in soil solutions or the diffusive gradients in thinfilms (DGT) measurement.

Test material

Test material information

Constituent 1

Reference substance name:

CuCl2

IUPAC Name:

CuCl2

Test organisms

1

Species:

Hordeum vulgare

Plant group:

Monocotyledonae (monocots)

2

Species:

Lycopersicon esculentum

Plant group:

Dicotyledonae (dicots)

Study design

Study type:

laboratory study

Results and discussion

Effect concentrations

Dose descriptor:

other: see summary

Remarks on result:

other: see summary

Applicant's summary and conclusion

Conclusions:

plant bioavailability of Cu in soil depends on Cu speciation, interactions with protective ions (H+) and the resupply from the solid phase. DGT measurement provides a useful indicator of Cu bioavailability in soil.

Executive summary:

The toxicity effect concentrations of total added Cu derived from barley root elongation and tomato growth assays varied widely among 18 European soils. Zhao et al (2006) investigated whether this variation could be explained by the solubility or speciation of Cu in soil solutions or the diffusive gradients in thinfilms (DGT) measurement. Solubility and Cu speciation varied greatly among the soils tested. However, the EC10 and EC50 of soil solution Cu or free Cu²+ activity varied even more widely than those based on the total added Cu, indicating that solubility or soil solution speciation alone could not explain intersoil variation in Cu toxicity. Estimated EC10 and EC50 of free Cu²+ activity correlated closely and negatively with soil pH, indicating a protective effect of H+, which is consistent with the biotic ligand model concept. The DGT measurement was found to narrow the intersoil variation in EC50 considerably and to be a better predictor of plant Cu concentrations than either soil solution Cu or free Cu²+ activity. The authors conclude that plant bioavailability of Cu in soil depends on Cu speciation, interactions with protective ions (H+) and the resupply from the solid phase, and conclude that the DGT measurement provides a useful indicator of Cu bioavailability in soil.