Title
Cadmium isotope fractionation in the soil-cacao systems of Ecuador: A pilot field study
Date Issued
01 January 2019
Access level
open access
Resource Type
journal article
Author(s)
Moore R.E.T.
Rehkämper M.
Schreck E.
Lefeuvre G.
Kreissig K.
Coles B.J.
Maurice L.
Publisher(s)
Royal Society of Chemistry
Abstract
The often high Cd concentrations of cacao beans are a serious concern for producers in Latin America due to the implementation of stricter Cd limits for cocoa products by the European Union in 2019. This is the first investigation to employ coupled Cd isotope and concentration measurements to study soil-cacao systems. Analyses were carried out for 29 samples of soils, soil amendments and cacao tree organs from organic farms in Ecuador that harvest three distinct cacao cultivars. The majority of soils from 0-80 cm depth have very similar δ114/110Cd of about -0.1‰ to 0‰. Two 0-5 cm topsoils, however, have high Cd concentrations coupled with heavy Cd isotope compositions of δ114/110Cd ≈ 0.2%, possibly indicating Cd additions from the tree litter used as organic fertilizer. Whilst cacao leaves, pods and beans are ubiquitously enriched in Cd relative to soils there are distinct Cd isotope signatures. The leaves and pods are isotopically heavier than the soils, with similar Δ114/110Cdleaf-soil values of 0.22 ± 0.07‰ to 0.41 ± 0.09‰. In contrast, the data reveal differences in Δ114/110Cdbean-leaf that may be linked to distinct cacao cultivars. In detail, Δ114/110Cdbean-leaf values of -0.34‰ to -0.40‰ were obtained for Nacional cacao from two farms, whilst CCN-51 hybrid cacao from a third farm showed no fractionation within error (-0.08 ± 0.13‰). As such, further work to investigate whether Cd isotopes are indeed useful for tracing sources of Cd enrichments in soils and to inform genetic efforts to reduce the Cd burden of cocoa is indicated.
Start page
34011
End page
34022
Volume
9
Issue
58
Language
English
OCDE Knowledge area
Protección y nutrición de las plantas
Scopus EID
2-s2.0-85074450697
Source
RSC Advances
ISSN of the container
20462069
Sponsor(s)
This study was funded by the Olga Triballat Institute, the French Cooperative Ethiquable and by the Isotopes Axe of the Observatoire Midi-Pyrénées (OMP-Toulouse). The analytical work in the UK was supported by STFC-GCRF funding to MR. Rémi Freydier from the Platform AETE-ISO, OSU OREME at the Montpellier University is thanked for the Q-ICP-MS measurements. We are grateful to Nicolas Eberhart from Ethiquable for his help with sample collection in Esmeraldas and the cacao farmers for their support in the eld, especially to Belia Vaca and Galo Rodriguez. The critical but constructive comments by four reviewers of an earlier manuscript version and two referees of the current text were immensely helpful in craing a signi-cantly improved article.
Sources of information:
Directorio de Producción Científica
Scopus