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range of fractionation processes will alter its isotopic composition in undecipherable
ways (Table 5.1 ) (Foucher et al. 2013 ). The analysis by Sonke et al. ( 2010 ) suggests
that Hg isotopes may behave conservatively in some sedimentary environments, and
may therefore serve as a potential a tracer of Hg provenance, transport processes,
loading histories, and biogeochemical processes in river systems. Although the use
of Hg isotopes as a tracer of Hg source(s) is clearly complicated, other studies
(e.g., Donovan et al. 2013 ; Foucher et al. 2013 ; Yin et al. 2013 ) have supported the
conclusions of Sonke et al. ( 2010 ) that Hg has significant potential as a tracer of
contaminated sediment.
5.5 Summary and Management Implications
Advances in analytical chemistry, particularly the advent of the MC-ICP-MS, have
created the possibility that a wide range of non-traditional stable isotopes (non-
CHONS) can potentially be used as environmental tracers. In riverine sedimentary
environments, recent studies have shown that Cd, Cu, Hg, and Zn may hold particu-
lar promise. In contrast to Pb, differences in the isotopic composition of geological
and anthropogenic materials are due to physical and chemical isotopic fractionation
processes. As a result, these isotopes allow for a linkage between trace metal con-
centrations and specific industrial processes used during a given time period at a
single source location. In addition, some isotopic systems (e.g., Cu which is redox
sensitivity) may be used to gain insights into biogeochemical cycling within river
systems. The use of these non-CHONS, however, is complicated by the potential
for isotopic fractionation during contaminant dispersal and/or following deposition.
Fractionation may be particularly problematic for redox sensitive elements (e.g.,
Cu) because significant abiotic or biotic fractionation may be associated with redox
reactions that occur as the sediments are dispersed through the drainage network or
following deposition. Such alterations, the degree to which will depend on the phys-
iochemical conditions of the site, may (1) inhibit the use of these non-traditional
isotopes as effective tracers, and (2) require that detailed information regarding the
cycling of the utilized isotopes within the studied site be collected for their effective
use.
Non-CHONS will likely be used only in a supportive role in environmental foren-
sic investigations in the near future, at least until their effectiveness as tracers of con-
taminated particles have been more fully demonstrated and the processes that control
the nature and magnitude of isotopic fraction more completely understood. The use
of the non-CHONS will likely be driven by the desire to trace specific contaminants,
or to compliment data derived from other isotopic tracers. Bigalk et al. ( 2010a ), for
example, used a combination of Cu and Zn isotopes to determine the source and
dispersal of Cu and Zn in soils adjacent to a Cu smelter in Slovakia. They found the
ʴ
65 Cu values varied little in organic rich surface soils and smelter wastes (e.g., slag,
sludge, and ash). Cu isotopes, then, provided ineffective as a tracer of Cu/Zn source.
However, significant variations in
65 Cu values occurred with depth in the soils,
ʴ
 
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