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|Title: ||Metal chemistry and bioavailability in a biosolids-amended forest soil following conversion of the land for agricultural usage|
|Author: ||McLaren, Ronald G.|
Clucas, L. M.
|Date: ||2008 |
|Publisher: ||New Zealand Trace Elements Group|
|Citation: ||McLaren, R. G., Clucas, L. M., (2008). Metal chemistry and bioavailability in a biosolids-amended forest soil following conversion of the land for agricultural usage. New Zealand Trace Elements Group Conference 2008, University of Waikato, Hamilton, 13-15 Feb 2008|
|Item Type: ||Conference Contribution - Full Conference Paper|
|Abstract: ||Application of biosolids to forests as a method of disposal is currently being used by authorities
around the world, including New Zealand.
This practice can lead to a build up of metals (from the biosolids) within the forest litter layer.
However, as long as the land remains under forest, the chance of these metals entering the
human food chain is low. This may cease to be the case if the forest is cleared for conversion
of the land back for agriculture.
This study, using incubation and plant growth techniques, examines the fate of metals in a
Pinus radiata plantation forest treated with metal-spiked biosolids, following simulated
conversion of the land back for agricultural use. Mixing of the biosolids-treated forest litter into
the underlying mineral soil resulted in high concentrations of metals (Cu, Ni and Zn) in easily
extractable forms, and there was also very little change in these concentrations during a
subsequent 2-year incubation of the samples. Soil solution concentrations of the metals were
also enhanced substantially by the various original biosolids treatments.
Chemical speciation of the soil solutions using WHAM 6 showed that whereas solution Cu was
dominated by organic complexes, most Ni and Zn was present at Ni²⁺ and Zn²⁺, with generally
less than 5% of these elements present as organic complexes. Addition of lime to the soils
substantially decreased both readily extractable and soil solution metal concentrations,
however, even in their unlimed state there were no adverse effects due to the metals on plant
growth as determined in a wheat germination and seedling growth test. Nevertheless, metal
concentrations in the wheat seedlings were increased by the various original biosolids
Plant metal concentrations showed strong correlations with either soil solution metal ion
activities, or effective soil solution concentrations as determined by diffusive gradients in thin
films (DGT). The results from this study are discussed in relation to the possible consequences
of growing agricultural crops on land converted from forest soils that have previously received
applications of biosolids.|
|Persistent URL (URI): ||http://hdl.handle.net/10182/4404|
|Rights: ||Copyright © The Authors.|
|Appears in Collections:||Department of Soil and Physical Sciences|
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