The migration and extractability of the Cu were studied by determining total Cu and DTPA extractable Cu in the different depth zones of the soil columns (Figs 2 and 3).
These results show that the application of these six fertilisers cannot be considered an environmental risk to the soil, since the predicted no effect concentration (PNEC) of Cu in soils in the European Union (EU), estimated in the EU Risk Assessment, ranges from 20 to 200 mg Cu [kg.
However, the extractable Cu in this zone (from 0 to 10 cm) decreased with time.
Applications of Cu-GL, Cu-G-GL, Cu-ORG and CuOXYCL resulted in accumulations of extractable Cu in the soil surface layer (Fig.
The partitioning of Cu in the soil was approximately as follows: (1) 5% in WS + EX, (2) 50% in SOR, (3) 15% in MnOX, (4) 10% in OM, (5) 5% in OX, and (6)15% in RES.
These decreases were due to both the redistribution of Cu in the soil profile (0-60 cm) and to losses of Cu due to leaching.
A mass balance was performed to evaluate the percentages of recovered Cu in this column experiment, considering the initial soil Cu plus the added Cu content and the Cu that remained in the soil and that was leached.
This behaviour could, at least in part, have been due to the fact that the roots of graminaceous species are able to take up Cu in its cationic form and as Cu-chelate (Marschner 1995).
The potential availability of Cu in the soil was determined by the DTPA method at triticale harvest (see Fig.
At this time the concentration of Cu in the column leachate was approximately 0.
Using the non-ideal competitive adsorption model to describe Cu-proton DOC interactions, those researchers found that Cu-DOC complexes comprised >99% of aqueous Cu in effluent from their soil columns.
This suggests that the solid/solution partitioning behaviour of Cu in the A horizon of Podosols from eastern Australia (which generally exhibit low levels of fine mineral sorbent phases) may be estimated based on the abundance of soil organic C.
The present study indicates that the formation and fate of Cu-DOC complexes play a central role in the geochemical behaviour of Cu in soils and is therefore an area requiring further research.
2005, this issue) showed that interactions with DOC can substantially influence the solid/solution partitioning behaviour of Cu in soil.
Given the relatively low concentration of fine aluminosilicate and oxide minerals, sorption of Cu in the study soil may be largely due to interaction with solid-phase organic matter.