Selenium (Se) enrichments or deficiency in maize (Zea mays L.), one of the world’s most important staple foods and livestock feeds, can significantly affect many people’s diets, as Se is essential though harmful in excess. In particular, Se-rich maize seems to have been one of the factors that led to an outbreak of selenosis in the 1980s in Naore Valley in Ziyang County, China. Thus, this region’s geological and pedological enrichment offers some insight into the behavior of Se in naturally Se-rich crops. This study examined total Se and Se species in the grains, leaves, stalks, and roots of 11 maize plant samples, Se fractions of soils around the rhizosphere, and representative parent rock materials from Naore Valley. The results showed that total Se concentrations in the collected samples were observed in descending order of soil > leaf > root > grain > stalk. The predominant Se species detected in maize plants was SeMet. Inorganic Se forms, mainly Se(VI), decreased from root to grain, and were possibly assimilated into organic forms. Se(IV) was barely present. The natural increases of Se concentration in soils mainly affected leaf and root dry-weight biomasses of maize. In addition, Se distribution in soils markedly correlated with the weathered Se-rich bedrocks. The analyzed soils had lower Se bioavailability than rocks, with Se accumulated predominantly as recalcitrant residual Se. Thus, the maize plants grown in these natural Se-rich soils may uptake Se mainly from the oxidation and leaching of the remaining organic-sulfide-bound Se fractions. A viewpoint shift from natural Se-rich soils as menaces to possibilities for growing Se-rich agricultural products is also discussed in this study.

The application of mineralogy in archeology has been growing in interest in particular in relation to establishing the origin of the clays used in the elaboration of ancient ceramic artifacts. The mineralogy did not show a clear relationship with the colors expressed by the pottery system defined by the archaeologists; that is, independent of the color of the slip, each group has the same mineralogical components. Fourteen Pre-Hispanic pottery sherds from the Mesa de Los Santos region (Colombia) were selected for mineralogical characterization by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The objective of the work was to contribute to the knowledge of the production technology and elucidate a possible regional origin of these ceramics. The observed mineralogical phases were plagiocalse, quartz, potassium fledspar, clay minerals, micas, carbonate minerals, and iron oxides. Firing temperatures are in the ranges 600-800°C for almost all the analyzed samples.

A set of selected fragments of pre-Hispanic pottery sherds that were excavated from the Mesa de Los Santos region's archaeological site (Colombia) were investigated by different analytical techniques and principal component and hierarchical cluster analyses. This study is very useful to understand more about the raw materials (and provenance) for ancient pottery production and their manufacturing technology. In addition to establish stratigraphic and anthropological relationships, the pottery sherds were analyzed to determine their mineralogical and chemical composition, as well as their structural characteristics using X-ray powder diffraction, wavelength dispersive X-ray fluorescence, scanning electron microscopy, and attenuated total reflectance Fourier transform infrared spectroscopy. The results indicated that the pre-Hispanic pottery sherds were manufactured using poor carbonates and iron oxide-bearing clays with no significant changes in the technology of manufacture, firing the pastes at the proper temperatures or selecting and processing the raw materials to fulfill their use. The manufacture of pre-Hispanic pottery was probably carried out using local raw materials, compatible with the regional geological context, and the archaeometric study reveals that the pre-Hispanic cultures who lived in this region hardly had access to trade of raw materials.

Maize (Zea mays) is one of the most important staple food and primary source of livestock feed in the world. As the consumption of maize grown on the selenium-enriched soils of Naore Valley is one of the apparent causes of selenosis in the area, this work collected and analyzed total Se, Se fractions, and Se species distributions in maize plant samples, including grains, leaves, stalks, roots, rhizosphere soils, and the most representative parent rock materials from Naore Valley, Ziyang County, China. The Se distribution in soils markedly correlated with the weathered Se-enriched bedrocks, but most of the Se in the analyzed soils is enclosed as recalcitrant residual Se and organic-sulfide bound Se. In contrast, Se in rocks had a comparatively higher bioavailability and is bounded mainly to organic matter and sulfides minerals, with very few of the Se enclosed in the residual fraction. Maize plants might take a large amount of Se from the organic-sulfide bound Se fraction in the Se-rich soils, the weathered products from bedrocks or plant litters. Total Se concentrations in the collected samples were observed in descending order soil>leaf>root>grain>stalk. The predominant Se species detected in maize plants was SeMet. Se inorganic forms, mainly Se(VI), decreased from root to grain and were possibly assimilated into organic forms. Se (IV) was barely present. The natural increases in Se concentration affected mainly leaf and root dry-weight biomass as they are the organs that coped with the highest Se accumulation. This paper offers an insight into the uptake, accumulation, and distribution of Se forms in natural Se-rich maize crops and an opportunity for shifting Se-rich soils from menaces to valuable resources for growing Se-rich agricultural products.