Search for collections on Wintec Research Archive

Source-tracking cadmium in New Zealand agricultural soils: a stable isotope approach


There is a more recent version of this item available.
[thumbnail of conference proceeding with my name and abstract highlighted on page 53] PDF (conference proceeding with my name and abstract highlighted on page 53)
NZSSS_2018_Handbook_Abstract proceedings.pdf - Supplemental Material

Download (10MB)


Cadmium (Cd) is a toxic heavy metal, which is accumulated by plants and animals and therefore enters the human food chain. In New Zealand (NZ), where Cd mainly originates from the application of phosphate fertilisers, stable isotopes can be used to trace the fate of Cd in soils and potentially the wider environment due to the limited number of sources in this setting. Prior to 1997, extraneous Cd added to soils in P fertilisers was essentially limited to a single source, the small pacific island of Nauru. Analysis of Cd isotope ratios (ɛ114/110Cd) in Nauru rock phosphate, pre-1997 superphosphate fertilisers, and Canterbury (Lismore Stony Silt Loam) topsoils (Winchmore Research Farm) has demonstrated their close similarity with respect to ɛ114/110Cd.
We report a consistent ɛ114/110Cd signature in fertiliser-derived Cd throughout the latter twentieth century. This finding is useful because it allows the application of mixing models to determine the proportions of fertiliser-derived Cd in the wider environment. We believe this approach has good potential because we also found the ɛ114/110Cd in fertilisers to be distinct from unfertilised Canterbury subsoils. In our analysis of the Winchmore topsoil series (1949-2015), the ɛ114/110Cd remained quite
constant following the change from Nauru to other rock
phosphate sources in 1997, despite a corresponding
shift in fertiliser ɛ114/110Cd at this time.
We can conclude that to the present day, the Cd in topsoil at Winchmore still mainly originates from historical phosphate fertilisers. One implication of this finding is that the current applications of P fertiliser are not resulting in further Cd accumulation. We aim to continue our research into Cd fate, mobility and transformations in the NZ environment by applying Cd isotopes in soils and aquatic environments across the country.

Item Type: Paper presented at a conference, workshop or other event, and published in the proceedings
Uncontrolled Keywords: cadmium, isotope, phosphate fertiliser
Subjects: Q Science > Q Science (General)
Divisions: Schools > Centre for Science and Primary Industries
Depositing User: Maddie Zadeh
Date Deposited: 12 Dec 2018 04:14
Last Modified: 21 Jul 2023 07:46

Available Versions of this Item

Actions (login required)

View Item
View Item