Dimanganese trioxide

Other distribution data

Administrative data

Endpoint:

other distribution data

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Data source

Reference

Reference Type:

review article or handbook

Title:

Unnamed

Year:

2004

Materials and methods

Test guideline

Qualifier:

no guideline followed

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Manganese

EC Number:

231-105-1

EC Name:

Manganese

Cas Number:

7439-96-5

Molecular formula:

Mn

IUPAC Name:

manganese

Results and discussion

Any other information on results incl. tables

Soil particulate matter containing manganese can be transported in air. The fate and transport of manganese in air are largely determined by the size and density of the particles and by wind speed and direction. Although manganese can react with sulfur dioxide and nitrogen dioxide, the occurrence of such reactions in the atmosphere has not been demonstrated.

Manganese-containing particles are removed from the atmosphere mainly by gravitational settling or by rain.

A complex series of oxidation/precipitation and adsorption reactions occur when Mn(II) is present in aerobic environments, which eventually renders the manganese biologically unavailable as insoluble manganese dioxide. The time required for oxidation and precipitation of manganese ranges from days in natural waters to years in synthetic waters.

The Mn(II) ion is more soluble than Mn(IV), therefore, manganese will tend to become more bioavailable with decreasing pH and redox potential. The presence of chlorides, nitrates and sulfates can increase manganese solubility and thus increase aqueous mobility and uptake by plants.

Manganese is often transported in rivers adsorbed to suspended sediments. The tendency of soluble manganese compounds to adsorb to soils and sediments can be highly variable, depending mainly on the cation exchange capacity and the organic composition of the soil. Release from sediment to water occurs by diffusion processes because of a steep Mn(II) concentration gradient across the sediment pore water and bottom water interface.

In soils, manganese solubility is determined by two major variables: pH and redox potential. Water-soluble manganese in soils is directly proportional to pH, with oxidation state being another major determinant of manganese solubility. The lower oxidation state, Mn(II), predominates in reducing conditions, resulting in higher concentrations of dissolved manganese in flooded soils or other reducing situations. The oxidation state of manganese in soils and sediments can be altered by microbial activity. While microorganisms are believed to play an important role in the cycling of manganese in aquatic environments, specific microbial groups indigenous to these systems have not been well characterized.