Mercury (Hg) is a top-priority contaminant at a global scale due to its high toxicity, mobility, and persistence in the environment. It was observed that remobilization of Hg polluted soils and sediments represents the main source of Hg release in mining areas. The Monte Amiata Mining District (MAMD, Southern Tuscany) represented the 3rd largest Hg producer worldwide (Nannoni et al., 2022). Previous works studied Hg dispersion into fluvial ecosystem from the MAMD through the Paglia River catchment (SE sector of the MAMD) and to the Mediterranean Sea, proving that this mining area is a persistent source of pollution and that the Paglia River has a low resilience to Hg pollution (Rimondi et al., 2019; Fornasaro et al., 2022a, Fornasaro et al., 2022b). The contribution of the Fiora River basin (S sector of the MAMD) to the dispersion of Hg-polluted sediments and its temporal variability is presented here. The Fiora River originates on the S flank of Mount Amiata and flows for 80 km towards the Mediterranean Sea. Fifty-one stream sediment samples were collected in 2022: a) 15 samples were taken along the main course of the Fiora River, b) 27 on the secondary creeks draining abandoned mining areas, and c) 9 samples along the Fiora River tributaries that do not drain the mining areas. The total Hg content (Hgt) of the samples were compared with the data obtained in 1985 by the RIMIN company (E.N.I. Group) in the Tuscan section of the river catchment. The 2022 sampling also included the downstream part of the Fiora River down to the outlet in the Latium region. Hgt varied between 0.4 and 3300 mg/kg, with mean and median values of 111.1 and 3.7 mg/kg, respectively. The RIMIN data in the same sites showed a wider range of Hgt (0.5-6450 mg/kg), a higher mean value (592 mg/kg) and a median (3.8 mg/kg) similar to that of the 2022 sampling campaign. Both samplings showed that Hgt frequently exceeded the Italian law limit for residential, public green and agricultural soil (1 mg/kg) and the highest Hgt values were found in the NE part of the catchment, i.e., along the tributaries that drain the Abetina-Solforate (AS) mining site (up to 3300 mg/kg in 2022). Between 1985 and 2022, Hgt decreased in the AS area and along the secondary tributaries that drain the other former mines. The samples collected in the non-mining areas showed Hgt ranging from 0.4 to 3.5 mg/ kg. Sediments along the main course of the Fiora River showed Hgt above 1 mg/kg, with most of the highest values (30-39 mg/kg) in the downstream segment, close to the outflow in the Mediterranean Sea. This study demonstrates that a) the Fiora River gives a significant contribution to the transport of Hg towards the sea, and b) this river catchment has a low resilience to Hg pollution, similarly to the Paglia River, since the contamination did not decrease significantly in the last 40 years. Fornasaro S., Morelli G., Rimondi V., Fagotti C., Friani R., Lattanzi P. & Costagliola P. (2022a) - Mercury distribution around the Siele Hg mine (Mt. Amiata district, Italy) twenty years after reclamation: Spatial and temporal variability in soil, stream sediments, and air. J. Geochem. Explor., 232, 106886. Fornasaro S., Morelli G., Rimondi V., Fagotti C., Friani R., Lattanzi P. & Costagliola P. (2022b) - The extensive mercury contamination in soil and legacy sediments of the Paglia River basin (Tuscany, Italy): interplay between Hg-mining waste discharge along rivers, 1960s economic boom, and ongoing climate change. J. Soils Sediments, 22(2), 656-671. Nannoni A., Meloni F., Benvenuti M., Cabassi J., Ciani F., Costagliola P., Fornasaro S., Lattanzi P., Lazzaroni M., Nisi B., Morelli G., Rimondi V. & Vaselli O. (2022) - Environmental impact of past Hg mining activities in the Monte Amiata district, Italy: A summary of recent studies. AIMS Geosci., 8(4), 525-551. Rimondi V., Costagliola P., Lattanzi P., Morelli G., Cara G., Cencetti C., Fagotti C., Fredduzzi A., Marchetti G., Sconocchia A. & Torricelli S. (2019) - A 200 km-long mercury contamination of the Paglia and Tiber floodplain: Monitoring results and implications for environmental management. Environ. Pollut., 255, 113191.
Mercury transport in stream sediments from a former mining area to the sea: the case of the Fiora River basin, Southern Tuscany, Italy
Fornasaro S.Secondo
;
2023-01-01
Abstract
Mercury (Hg) is a top-priority contaminant at a global scale due to its high toxicity, mobility, and persistence in the environment. It was observed that remobilization of Hg polluted soils and sediments represents the main source of Hg release in mining areas. The Monte Amiata Mining District (MAMD, Southern Tuscany) represented the 3rd largest Hg producer worldwide (Nannoni et al., 2022). Previous works studied Hg dispersion into fluvial ecosystem from the MAMD through the Paglia River catchment (SE sector of the MAMD) and to the Mediterranean Sea, proving that this mining area is a persistent source of pollution and that the Paglia River has a low resilience to Hg pollution (Rimondi et al., 2019; Fornasaro et al., 2022a, Fornasaro et al., 2022b). The contribution of the Fiora River basin (S sector of the MAMD) to the dispersion of Hg-polluted sediments and its temporal variability is presented here. The Fiora River originates on the S flank of Mount Amiata and flows for 80 km towards the Mediterranean Sea. Fifty-one stream sediment samples were collected in 2022: a) 15 samples were taken along the main course of the Fiora River, b) 27 on the secondary creeks draining abandoned mining areas, and c) 9 samples along the Fiora River tributaries that do not drain the mining areas. The total Hg content (Hgt) of the samples were compared with the data obtained in 1985 by the RIMIN company (E.N.I. Group) in the Tuscan section of the river catchment. The 2022 sampling also included the downstream part of the Fiora River down to the outlet in the Latium region. Hgt varied between 0.4 and 3300 mg/kg, with mean and median values of 111.1 and 3.7 mg/kg, respectively. The RIMIN data in the same sites showed a wider range of Hgt (0.5-6450 mg/kg), a higher mean value (592 mg/kg) and a median (3.8 mg/kg) similar to that of the 2022 sampling campaign. Both samplings showed that Hgt frequently exceeded the Italian law limit for residential, public green and agricultural soil (1 mg/kg) and the highest Hgt values were found in the NE part of the catchment, i.e., along the tributaries that drain the Abetina-Solforate (AS) mining site (up to 3300 mg/kg in 2022). Between 1985 and 2022, Hgt decreased in the AS area and along the secondary tributaries that drain the other former mines. The samples collected in the non-mining areas showed Hgt ranging from 0.4 to 3.5 mg/ kg. Sediments along the main course of the Fiora River showed Hgt above 1 mg/kg, with most of the highest values (30-39 mg/kg) in the downstream segment, close to the outflow in the Mediterranean Sea. This study demonstrates that a) the Fiora River gives a significant contribution to the transport of Hg towards the sea, and b) this river catchment has a low resilience to Hg pollution, similarly to the Paglia River, since the contamination did not decrease significantly in the last 40 years. Fornasaro S., Morelli G., Rimondi V., Fagotti C., Friani R., Lattanzi P. & Costagliola P. (2022a) - Mercury distribution around the Siele Hg mine (Mt. Amiata district, Italy) twenty years after reclamation: Spatial and temporal variability in soil, stream sediments, and air. J. Geochem. Explor., 232, 106886. Fornasaro S., Morelli G., Rimondi V., Fagotti C., Friani R., Lattanzi P. & Costagliola P. (2022b) - The extensive mercury contamination in soil and legacy sediments of the Paglia River basin (Tuscany, Italy): interplay between Hg-mining waste discharge along rivers, 1960s economic boom, and ongoing climate change. J. Soils Sediments, 22(2), 656-671. Nannoni A., Meloni F., Benvenuti M., Cabassi J., Ciani F., Costagliola P., Fornasaro S., Lattanzi P., Lazzaroni M., Nisi B., Morelli G., Rimondi V. & Vaselli O. (2022) - Environmental impact of past Hg mining activities in the Monte Amiata district, Italy: A summary of recent studies. AIMS Geosci., 8(4), 525-551. Rimondi V., Costagliola P., Lattanzi P., Morelli G., Cara G., Cencetti C., Fagotti C., Fredduzzi A., Marchetti G., Sconocchia A. & Torricelli S. (2019) - A 200 km-long mercury contamination of the Paglia and Tiber floodplain: Monitoring results and implications for environmental management. Environ. Pollut., 255, 113191.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
