Aluminium fractionation using cation exchange: comparison of results obtained after fractionation in the field and in the laboratory

Abstract

Dissolved aluminium was fractionated in the field and the laboratory using a cation-exchange method. Although absolute differences between results obtained from field and laboratory fractionations were generally small, relative differences, expressed as the ratio between labile aluminium determined after laboratory fractionation (Al_ll) and that obtained after field fractionation (Al_lf) could be large. The differences found were not statistically significant, although this may simply reflect the spread in the results. Al_ll/Al_lf had no apparent relationship with the temperature difference between the field and the lab. Although some significant correlations were found between Al_ll/Al_lf and H⁺, no significant correlations were found with the equivalent relative difference in {H⁺} between the lab and the field; nor was any significant correlation found with dissolved organic carbon.

Keywords:

• Aluminium
• Fractionation
• Cation exchange
• Natural waters

Acknowledgements

The Norwegian Forest Research Institute financed this work, together with the Norwegian Ministries of Agriculture and the Environment through the Norwegian Monitoring Programme for Forest Damage. We would like to thank UNESCO for providing a fellowship for Defne Çakın to visit Norway. The staff of the analytical laboratories of the Norwegian Forest Research Institute and the Norwegian Centre for Soil and Environmental Research carried out the ICP and DOC analyses. Three anonymous referees are thanked for their comments on the manuscript.