**Author details**

*Trace Metals in the Environment - New Approaches and Recent Advances*

further studies in these elements as they are intimately related to MJD.

tuting a public health problem [112].

the same bioavailability.

intake.

**4. Conclusions**

through the years but MJD still reaches its highest worldwide value (1:239), consti-

In 2004, Purdey [105] established a common abnormal hallmark of high manganese (Mn)/low magnesium (Mg) status and suggested that this aberrant mineral ratio inactivates the Mn/Mg catalyzed endonuclease-1 enzyme. The high Mn/low Mg rate observed in all volcanic regions of São Miguel Island reinforces the need for

These studies evidence that the Azores archipelago presents itself as an ideal scenario for the study of TE availability and possible health effects. However, the total TE concentration in soil is a relatively weak measure of their bioavailability. Given that the bioavailability depends on specific soil characteristics, such as organic matter content and pH, similar concentrations of TEs in different soils may not have

The assessment of TE bioavailability is fundamental, as the bioavailable fraction of trace elements is the fraction most likely to harm plants and animals. Consequently, the impact of TEs on soil and the surrounding environment cannot be predicted by measuring the total concentration of elements *per se*, since only the soluble and mobile fraction has the potential to leach or to be taken up by plants and enter the food chain [113]. Future studies should consider the assessment of the bioavailable part of the TEs in volcanic environments, to define remediation strategies in order to prevent health problems associated with TE depletion or excessive

The assessment of the concentrations of TE in the soil is very important, not only for environmental purposes but also to help solve problems associated with human health and plant toxicity. Trace elements' profiles in soil result essentially from the weathering of geologic parent materials since their concentrations are

Given the volcanic origin of the Azorean soils, the natural enrichment of some elements, such as manganese, and an uneven and reduced distribution of others, such as cobalt and iodine, can contribute to the development of health problems in plants, animals, and humans. Due to the natural enrichment of some chemical elements in volcanic soils, resulting from the volcanic activity, which cannot be controlled, a very tight control of the possible sources of anthropogenic contamination is crucial to prevent the occurrence of toxic levels that prejudice plants, animals, and human's health. Regardless of substantial progress in the study of soil TEs, the application of critical exposure concentrations and the associated health risks are yet scarce and not fully clarified. Although the data obtained for the Azorean soils pinpoints to possible toxicity of manganese and deficiency of cobalt in some areas, more thorough studies, such as the ones developed for iodine, are required. Only with further information, focusing primarily on the bioavailability and bioaccessibility of the trace elements, it will be possible to adequately predict the health risks of exposure to soil TEs, which is particularly relevant in the areas where the

directly linked to the parent material based on their immobile nature.

environmental risk is greater, such as the volcanic environments.

**112**

Diana Paula Silva Linhares1 \*, Patrícia Ventura Garcia2,3 and Armindo dos Santos Rodrigues1,2

1 Institute of Volcanology and Risks Assessment (IVAR), University of the Azores, Ponta Delgada, Portugal

2 Faculty of Sciences and Technology, University of the Azores, Ponta Delgada, Portugal

3 Centre for Ecology, Evolution and Environmental Changes (cE3c), and Azorean Biodiversity Group, University of the Azores, Ponta Delgada, Portugal

\*Address all correspondence to: diana.ps.linhares@uac.pt

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
