Mercury fluxes from the abandoned Monte Amiata mining district in the Paglia and Tiber river catchments, Central Italy: preliminary estimates

<p>Mercury dispersion in the Paglia and Tiber river catchments (Central Italy) from the abandoned Monte Amiata mining district has long been documented (Rimondi et al., 2019, and references therein). However, there are comparatively fewer data on fluxes of the metal across the basin to the Tyrrhenian sea. The only published estimates (Rimondi et al., 2014) refer to the first 40 km of the Paglia River between Abbadia San Salvatore and Allerona Scalo. They reported highly variable total (dissolved + suspended particulate) Hg loads, up to 34 g/day, strongly depending on river discharge. We report here unpublished data from a sampling campaign of September 2014 (Millacci, 2016), that included three samples along the Tiber river. The data refer to low flow conditions at the end of the dry season. As expected, loads progressively increase with discharge from 1-5 g/day near the source of the Paglia river to about 100 g/day in the city of Rome. There is an anomalous value of 220 g/day just south of the Alviano dam (near Orvieto): a possible explanation is a release of Hg-rich sediments from the dam during maintenance operations.</p><p>Millacci G. (2016) – Unpublished thesis (Laurea magistrale) in Geological sciences, Università di Firenze</p><p>Rimondi V., et al. (2014) – Environmental Science and Pollution Research, 21:5575–5585</p><p>Rimondi V., et al. (2019) - Environmental Pollution 255, 113191</p>