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Environmental fate & pathways

Henry's Law constant

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Administrative data

Endpoint:
Henry's law constant
Type of information:
other: EU Risk Assessment
Adequacy of study:
other information
Reliability:
other: EU Risk Assessment
Rationale for reliability incl. deficiencies:
other: No reliability is given as this is a summary entry for the EU RAR.

Data source

Referenceopen allclose all

Reference Type:
secondary source
Title:
Unnamed
Year:
2003
Reference Type:
publication
Title:
Temperature dependence of Henrys Law constants for selected chlorobenzenes, polychlorinated biphenyls and polycyclic aromatic hydrocarbons.
Author:
ten Hulscher TEM, van der Velde LE, Bruggeman WA
Year:
1992
Bibliographic source:
Environ. Toxicol. Chem., 11, 1595-1603.
Reference Type:
publication
Title:
Desorption of chlorinated hydrocarbons from spiked and anthropogenically contaminated sediments.
Author:
Oliver BG
Year:
1985
Bibliographic source:
Chemosphere, 14(8), 1087-1106.
Reference Type:
publication
Title:
Air-water partitioning coefficients of organics in dilute aqueous solutions.
Author:
Ashworth RA, Howe GB, Mullins ME, Rogers TN
Year:
1988
Bibliographic source:
J. Haz. Mater. 18, 25-36.
Reference Type:
publication
Title:
Estimation programs interface for Microsoft Windows 3.1. By Meylan W, Howard P.
Author:
EPIWIN
Year:
1995
Bibliographic source:
Syracuse Research Corporation, Syracuse, NY
Reference Type:
publication
Title:
The effects of organic environmental chemicals on the growth of the alga Scenedesmus subspicatus: A contribution to environmental biology.
Author:
Geyer H, Scheunert I, Korte F
Year:
1985
Bibliographic source:
Chemosphere, 14 (9), 1355-1369.
Reference Type:
study report
Title:
Unnamed
Year:
1986
Reference Type:
publication
Title:
Biodegradation of 1,2,3- and 1,2,4-trichlorobenzene in soil and in liquid enrichment culture.
Author:
Marinucci AC and Bartha R
Year:
1979
Bibliographic source:
Appl. Environ. Microbiol., 38(5), 811-817.

Materials and methods

Principles of method if other than guideline:
EU Risk Assessment
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent

Results and discussion

Any other information on results incl. tables

EU Risk Assessment (2003):

Conclusion on volatility

The volatilisation of 1,2,4-TCB in clean water may be high but will be reduced in natural surface water according to the depth of the water body, possible stratification or turbulence of the water body and to the content of dissolved organic carbon (DOC) and particulate organic carbon (POC). The volatilisation is slow from soil and sludge because adsorption to organic carbon takes place.

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Volatility

Volatilisation from surface water is estimated by means of 1,2,4-TCBs Henrys Law constant (H). Using a vapour pressure of 36 Pa at 20°C and a water solubility of 36 mg/l, the estimated Henry's Law constant would be 181 Pa*m3/mol which indicates that volatilisation from shallow waters and after accidental spillage to water may take place.

 

A more reliable value may be obtained by measuring H directly by direct measurement of concentrations in the gas phase and the water phase in a system at equilibrium. Using a gas-purge technique, a water concentration of 10µg/l and GC determination, ten Hulscher et al. (1992) measured the dimensionless Henrys Law constant (Kair-water) to 0.041 equivalent to a H of 101 Pa.m3/mol for 1,2,4-TCB. The measurements were carried out in a buffer solution at pH 6.4 which may have changed the solubility of 1,2,4 -TCB. Other measured values ofH at 20ºC were 122 Pa.m3/mol(Kair-water 0.050) and 185 Pa.m3/mol (Kair-water 0.076) (Oliver, 1985; Ashworth et al., 1988, respectively).

 

QSAR estimation of Henry's Law constant by the bond contribution method resulted in a H estimated to be 2.19*10-3 atm.m3/mol (290 Pa.m3/mol) (EPIWIN, 1995).

 

The volatilisation rate in an aqueous solution has been observed to be 6.5 hour/m depth at 20°C (Geyer et al., 1985). The volatility from an aqueous solution was studied using the water sampling method. The initial concentration was 10.7 mg/l and the half-life was estimated to be 22 minutes at 20°C using 14C-labelled substance (Korte and Freitag, 1986). These studies confirm that volatilisation takes place but the results are not in a form that can be used quantitatively in this risk assessment.

 

The volatilisation from soil is reduced at increasing content of organic matter due to adsorption. In soil incubated with 1,2,4-TCB at the concentration 50 ppm, the amount of volatile substances recovered from the test systems was 4 to 18% of the initial concentration from soil with high organic matter and 20 to 40% at low organic matter (Marinucci and Bartha, 1979).

Applicant's summary and conclusion