Geochemistry: Exploration, Environment, Analysis; May 2002; v. 2; no. 2;
p. 111-119; DOI: 10.1144/1467-787302-014
© 2002 Geological Society of London
Mercury in surface waters of three mine-dominated river systems: Idrija River, Slovenia; Carson River, Nevada; and Madeira River, Brazilian Amazon
J. C. Bonzongo1,
W. B. Lyons2,
M. E. Hines3,
J. J. Warwick1,
J. Faganeli4,
M. Horvat5,
P. J. Lechler6 and
J. R. Miller7
1 Department
of Environmental Engineering Sciences, P.O. Box 116450, University of
Florida, Gainesville, FL 32611-6540,
USA (e-mail:
BONZONGO{at}UFL.EDU)
2 Byrd
Polar Research Center, Ohio State University, Columbus, OH
43210-1002, USA
3 Department
of Biological Sciences, University of Alaska, Anchorage, AK
77000, USA
4 Marine
Biological Station, Fornace 41, Piran,
Slovenia
5 Department of
Environmental Science, Institute Jozef Stefan, Jamova 39,
Ljubljana,
Slovenia
6 University of
Nevada, Reno, NV 89557,
USA
7 Western Carolina
University, Cullowhee, NC 28723,
USA
This
paper investigates the aqueous geochemistry of mercury (Hg) in three
aquatic systems impacted by either past or present mining activities.
The Idrija River in Slovenia flows near the Idrija mercury mine, the
second largest mercury mine in the world, with continuous mining and
smelting activities for five centuries. During this period, it has been
estimated that over 30 000 tonnes of Hg have been released into
the mine's surrounding environment, due to inefficient smelting
technologies and Hg left behind in mine tailings within the river
basin. In contrast to cinnabar mining in the Idrija River Basin, the
Carson River in Nevada and the Madeira River in the Brazilian Amazon
are impacted by metallic mercury (Hg0) used
in the amalgamation process to extract gold (Au) and/or silver (Ag)
from crude ores and fine alluvial materials. The Carson River Basin was
the site of intensive Au- and Ag-mining for over 50 years in the late
1800s and early 1900s, resulting in an estimated 7000 tonnes of Hg lost
to the river and its watershed. The Madeira River is a site of ongoing
use of Hg0 in Au-prospecting. This study
reports on the level and speciation of Hg, as well as factors
controlling levels of methyl-Hg using aqueous data. Surface water
samples collected along longitudinal transects upstream of
well-identified point sources of Hg, except for the Madeira River, to
river deltas were analysed for Hg and geochemical parameters of
interest. Samples from Idrija and Carson rivers show clear evidence of
contamination, with Hg levels up to several hundreds of
ng l1 downstream from main
point sources. Unlike Idrija and the Carson rivers, water samples
collected from the Madeira River exhibited much lower Hg levels
(9.51 ng l1 on average,
n = 16). Measured physiochemical parameters are
used to determine the fate of Hg in these three river
systems.
KEYWORDS: mining, gold, mercury, methylmercury, Idrija
River (Slovenia), Carson River (Nevada), Madeira
River (Brazilian
Amazon)
Copyright © 2009 by Geological Society of London