Environmental Engineering Reference
In-Depth Information
CHAPTER 6
A Framework for a Mercury Monitoring
and Assessment Program
Synthesis and Future Research
ROBERT P. MASON
Morel et al., 1998). This transport, transformation, and bio-
accumulation make the control and management of Hg a
complex problem.
The importance of the atmosphere in the local, regional,
and global redistribution of Hg is well known, and anthro-
pogenic release of Hg into the atmosphere since indus-
trialization has increased the global pool of Hg about
threefold, on average, and to a higher extent in some loca-
tions, such as the eastern United States (Mason and Sheu,
2002; Lindberg et al., 2007; Selin et al., 2008; Pirrone and
Mason, 2009). Evidence of long-term changes in the atmo-
spheric Hg burden are recorded in a number of proxies, and
the extent of change can be determined using a variety of
methods, such as the analysis of lake sediments, ice cores,
and peat deposits (Engstrom and Swain, 1997; Lamborg
et al., 2002a; Barbante et al., 2004; Krabbenhoft et al., 2007).
Such increases in the global atmospheric pool should also
be refl ected in the atmospheric Hg concentration, but this
has been diffi cult to demonstrate given that the extent
to which measurement is possible is still limited (Slemr
et al., 2003; Lindberg et al., 2007) and the historical
record of accurate measurement is relatively short (
POLICY AND MANAGEMENT REQUIREMENTS
MODELING REQUIREMENTS
A MERCURY MONITORING FRAMEWORK
THE NETWORK DESIGN
PROPOSED INDICATORS
CONCLUDING REMARKS
Mercury (Hg), especially in its more toxic and bio-
accumulative form as methylmercury (MeHg), is an impor-
tant environmental health concern (Clarkson, 1994; Wolfe
et al., 1998; Wiener et al., 2003; Pirrone and Mahaffey, 2005;
Mergler et al., 2007). Therefore, in recent years there has been
a global effort to limit its input to the atmosphere, especially
from anthropogenic sources. Many regulations limiting Hg
emissions from specifi c sources in developing countries, and
elsewhere, are already in place, mandated, or likely to hap-
pen in the future (USEPA, 1997, 2008; UNEP, 2009). As these
regulations are implemented, there is a crucial need to docu-
ment the impact of their changes on human and ecosystem
health in order to assess the effectiveness of regulation and
the need for further controls (Mason et al., 2005; Harris et
al., 2007a; USEPA, 2008). There are advisories against the
overconsumption of fi sh with elevated MeHg from many
water bodies in the United States and other countries,
because it is documented that elevated intake of MeHg can
cause neurologic damage (Clarkson, 1994; Mahaffey, 1998).
Mercury is emitted into the biosphere, either via emission
to the atmosphere or to other regions (water or land), from
both natural and anthropogenic sources and is effectively
transported, primarily as inorganic Hg, from its source to
remote locations where it is converted and bio-accumulated
as MeHg into aquatic food chains (Mason and Sheu, 2002;
20
years, typically) (Ebinghaus et al, 2009). Given the con-
founding effect of climate variability and other factors
on atmospheric Hg concentration and distribution, it has
been diffi cult to derive a multidecade regional or global
trend based on the current situation, since data collection
is spatially and temporally uncoordinated (Mason et al.,
2005; Lindberg et al., 2007; Ebinghaus and Banic, 2009;
Keeler et al., 2009).
In addition, increases in Hg emissions in some regions
of the world are being offset by decreases in emissions in
other regions (Pacyna et al., 2006; Selin et al., 2008; Pirrone
et al., 2009, 2010), and given the relatively long atmo-
spheric residence time of Hg (0.5-1 year) (Lamborg et al.,
2002b), emissions in one region of the world can impact Hg
