ALFERROCK

Additional information on environmental fate and behaviour

Administrative data

Endpoint:

additional information on environmental fate and behaviour

Type of information:

other: information from textbook

Adequacy of study:

supporting study

Study period:

not applicable (textbook)

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: information from textbook

Data source

Reference

Reference Type:

review article or handbook

Title:

Scheffer/Schachtschabel - Lehrbuch der Bodenkunde

Author:

Scheffer F., Schachtschabel P.

Year:

2002

Bibliographic source:

Spektrum Akademischer Verlag GmbH

Applicant's summary and conclusion

Conclusions:

Natural background concentrations of dissloved aluminium in soil pore water vary with soil pH.

Executive summary:

Aluminium is a component of clay minerals which are decomposed at soil pH values below 5, resulting in an increase of dissolved Al³⁺in soil pore water. Thus, dissolved aluminium is permanently present in soil pore water, varying with pH.

The natural background concentration of Al³⁺in soil pore water – as well as the distribution of Al³⁺between solid matrix and soil pore water – is dependent on soil composition, i.e.:

·       Concentration of humic substances: complexation of Al³⁺;

·       Cation exchange capacity of the soils: influences the extent to which cations can be adsorbed.

·       Clay mineral content: adsorption of Al³⁺on the surface of clay minerals leading to the displacement of nutrient minerals from the soil matrix; intercalation of Al³⁺in intermediate layers of clay minerals accompanied with a reduction of the cation exchange capacity of the soils.

·       pH: below pH 5 Al(III) is present as Al³⁺. At neutral pH values Al forms poorly soluble crystalline/solid phases.