Tungsten Bioaccessibility and Environmental Availability in Tungsten-Spiked Agricultural Soils

Tungsten is an essential element for many cutting-edge industries. Its use is increasing, so much that it has become a “critical element”. With the increase in the use of tungsten, a possible increase in its presence in environmental matrices including soil is expected. In this research, we assessed the environmental availability and bioaccessibility of W in relation to soil properties. Four representative Mediterranean soils, collected in Italy, were spiked with tungsten and incubated for 12 months. In the spiked soils, the environmental availability of the element was determined by the Wenzel sequential extractions. The bioaccessibility was determined by the UBM (BARGE) method in both the gastric and intestinal phases. The findings indicated that the environmental availability is largely influenced by soil properties such as pH and organic matter, while a lower influence was discovered for bioaccessibility, particularly for the gastric phase. These differences could be ascribed to the characteristics of the extractants utilized in the various tests, in particular the pH values. These results could be a valuable reference to integrate with studies on really and not spiked contaminated soils, for the improvement of risk assessments and the development of strategies for remediating soils polluted with tungsten.