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Natural arsenic contamination in waters from the Pesariis village, NE Italy
Language
English
Status
Published
JCR Journal
JCR Journal
Title of the book
Issue/vol(year)
/62(2011)
ISSN
1866-6280
Electronic ISSN
1866-6299
Publisher
Springer Berlin Heidelberg
Pages (printed)
481–491
Issued date
2011
Keywords
Abstract
High arsenic (As) concentrations, [900 lg/L,
were measured in Ca–Mg–SO4 waters from springs and
drainages in the village of Pesariis in the Carnic Alps (NE
Italy). Oxidation of the outcropping arsenian marcasite ore
deposits of the area is proposed as the mechanism for As
release into oxygenated waters during runoff. Nevertheless,
the limited extension of the ore deposit and the relatively
low As content of the mineralization suggest that sulfide
weathering might not be the only process responsible for
the highest As concentration in groundwaters. An additional
mechanism involves As adsorption onto ferric iron
particulate during oxidation, the drawdown in reducing
environment at depth during water infiltration, and the
release of ferrous iron and sorbed arsenic to the water
columns by reductive dissolution of hydrous ferric oxides
(HFO). This yields the observed Fe–As correlation. Newly
formed HFO precipitates when groundwaters discharge to
aerated conditions, leading to the removal of As, which
strongly partitions into the iron-rich sediments, adsorbed
onto the surface of amorphous Fe2O3 xH2O. The calculated
and measured As concentration in sediments exceeds 10%
by weight. Furthermore, geochemical and isotopic data
indicate that the As-rich reservoir partly mixes with
shallower aquifers, commonly tapped for drinking supply,
representing a natural hazard for inhabitants.
were measured in Ca–Mg–SO4 waters from springs and
drainages in the village of Pesariis in the Carnic Alps (NE
Italy). Oxidation of the outcropping arsenian marcasite ore
deposits of the area is proposed as the mechanism for As
release into oxygenated waters during runoff. Nevertheless,
the limited extension of the ore deposit and the relatively
low As content of the mineralization suggest that sulfide
weathering might not be the only process responsible for
the highest As concentration in groundwaters. An additional
mechanism involves As adsorption onto ferric iron
particulate during oxidation, the drawdown in reducing
environment at depth during water infiltration, and the
release of ferrous iron and sorbed arsenic to the water
columns by reductive dissolution of hydrous ferric oxides
(HFO). This yields the observed Fe–As correlation. Newly
formed HFO precipitates when groundwaters discharge to
aerated conditions, leading to the removal of As, which
strongly partitions into the iron-rich sediments, adsorbed
onto the surface of amorphous Fe2O3 xH2O. The calculated
and measured As concentration in sediments exceeds 10%
by weight. Furthermore, geochemical and isotopic data
indicate that the As-rich reservoir partly mixes with
shallower aquifers, commonly tapped for drinking supply,
representing a natural hazard for inhabitants.
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article
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