Soil cadmium uptake by cocoa in Honduras
Cadmium (Cd) is a trace metal without essential biological functions that is toxic to plants, animals and humans at low concentrations. It occurs naturally in soils, but inputs from anthropogenic sources have increased soil Cd contents worldwide. Cadmium uptake by cocoa (Theobroma cacao L.) has recently attracted attention, after the European Union (EU) decided to bring into force values for maximum Cd concentrations in cocoa products that would be exceeded by current products of various provenances from Latin America. In order to identify factors governing Cd uptake by cocoa, we carried out a survey on 55 cocoa farms in Honduras in which we determined Cd concentrations in cocoa leaves, pod husks and beans and analysed their relationships to a variety of surrounding soil and site factors. Averaging 2.6±0.4 mgkg−1, the concentrations of Cdwere higher in the leaves than in the beans. With an average of 1.1±0.2 mg kg−1, the bean Cd concentrations still exceeded the proposed EU limit, however. The bean Cd showed large differences between geological substrates, even though regional variations in ‘total’ soil Cd were comparably small and the average concentration was in the range of uncontaminated soils (0.25±0.02 mgkg−1). Aswe found no influence of fertilizer application or vicinity to industrial sites, we conclude that the differences in soil Cd between sites were due to natural variation. Of all factors included here, DGT-available soil Cd was the best predictor of bean Cd (R2 = 0.5). When DGT was not considered, bean Cd was best predicted by ‘total’ soil Cd, pH and geology. The highest bean Cd concentrations were found on alluvial substrates.
| Main Authors: | , , , , , , |
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| Format: | Texto biblioteca |
| Language: | 00 |
| Published: |
Zurich, Switzerland Elsevier
2017
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| Subjects: | Cadmium, Theobroma cacao, Soil, |
| Online Access: | https://drive.google.com/drive/folders/10P5Vjf7t4KHFXHNrljVY2vsahsYGX-Th?usp=sharing |
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| Summary: | Cadmium (Cd) is a trace metal without essential biological functions that is toxic to plants, animals and humans
at low concentrations. It occurs naturally in soils, but inputs from anthropogenic sources have increased soil Cd
contents worldwide. Cadmium uptake by cocoa (Theobroma cacao L.) has recently attracted attention, after the
European Union (EU) decided to bring into force values for maximum Cd concentrations in cocoa products
that would be exceeded by current products of various provenances from Latin America. In order to identify factors
governing Cd uptake by cocoa, we carried out a survey on 55 cocoa farms in Honduras in which we determined
Cd concentrations in cocoa leaves, pod husks and beans and analysed their relationships to a variety of
surrounding soil and site factors. Averaging 2.6±0.4 mgkg−1, the concentrations of Cdwere higher in the leaves
than in the beans. With an average of 1.1±0.2 mg kg−1, the bean Cd concentrations still exceeded the proposed
EU limit, however. The bean Cd showed large differences between geological substrates, even though regional
variations in ‘total’ soil Cd were comparably small and the average concentration was in the range of uncontaminated
soils (0.25±0.02 mgkg−1). Aswe found no influence of fertilizer application or vicinity to industrial sites,
we conclude that the differences in soil Cd between sites were due to natural variation. Of all factors included
here, DGT-available soil Cd was the best predictor of bean Cd (R2 = 0.5). When DGT was not considered, bean
Cd was best predicted by ‘total’ soil Cd, pH and geology. The highest bean Cd concentrations were found on alluvial
substrates. |
|---|