Bioaccessible arsenic in soil of thermal areas of Viterbo, Central Italy: implications for human health risk

V Rimondi,D Medas,S Fornasaro,P Costagliola,T Catelani,M Paolieri,G Morelli,P Lattanzi

doi:10.1007/s10653-021-00914-1

Abstract

Thermal waters near the city of Viterbo (Central Italy) are known to show high As contents (up to 600 µg/l). Travertine is precipitated by these waters, forming extended plateau. In this study, we determine the As content, speciation and bioaccessibility in soil and travertine samples collected near a recreational area highly frequented by local inhabitants and tourists to investigate the risk of As exposure through accidental ingestion of soil particles. (Pseudo)total contents in the studied soils range from 17 to 528 mg/kg, being higher in soil developed on a travertine substrate (197 ± 127 mg/kg) than on volcanic rocks (37 ± 13 mg/kg). In travertines, most As is bound to the carbonatic fraction, whereas in soil the semimetal is mostly associated with the oxide and residual fractions. Accordingly, bioaccessibility (defined here by the simplified bioaccessibility extraction test, SBET; Oomen et al., 2002.) is maximum (up to 139 mg/kg) for soil developed on a travertine substrate, indicating a control of calcite dissolution on As bioaccessibility. On the other hand, risk analysis suggests a moderate carcinogenic risk associated with accidental soil ingestion, while dermal contact is negligible. By contrast, ingestion of thermal water implies a higher carcinogenic and systemic health risk.

Highlights

Arsenic (As) contamination of drinking water, air, food and beverages is a major global health issue, affecting more than 300 million people worldwide (Quansah et al, 2015)
Semi-quantitative estimates by X-ray diffraction (XRD) indicate that Bullicame soils are composed almost exclusively of calcite ([ 90 wt%) with minor quartz and k-feldspar; calcite is minor at Piscine Carletti and in the agricultural areas, where silicate minerals dominate
Sample VT7s shows an intermediate behavior between fossil and new-forming travertines, with the highest As concentration extracted from are observed in the carbonatic step (ACARB) (35 mg/kg), but displaying higher As concentrations from steps AOX to AAR compared to new-forming travertines

Summary

Introduction

Arsenic (As) contamination of drinking water, air, food and beverages is a major global health issue, affecting more than 300 million people worldwide (Quansah et al, 2015). As spreads in the environment as a consequence of changing redox conditions, which trigger As mobilization from adsorbing mineral phases. This is especially testified in floodplains and/or rice paddy fields, which commonly undergo flooding/non-flooding conditions during their agricultural seasons (e.g., Kim et al, 2021). As indicated by the EuroGeoSurveys database (Salminen et al, 2005), As is unevenly distributed among topsoils of European countries, displaying significant enrichment in southern Europe (Italy, France and Spain) with respect to Scandinavia (10.5–2.3 mg/kg, respectively), reflecting the soil finer nature and the long weathering history (Reimann et al, 2009). The As enrichment in soils is considered one of the causes of the higher incidence of dementia in some European countries, among others Italy, France and Spain (Dani, 2010)

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