Geochemical Fingerprinting - Application of Geochemical Tracers to Fluvial Sediment - page 42

present time, standardized procedures that can be used on a routine basis for geo-
chemical fingerprinting are generally lacking (Mukundan et al. 2012 ). Particular
aspects of the approach that require some form of guidance and/or standardization
are many, including the number of samples required for source area character-
ization and the methods used to collect them, the type of river sediments that
should be sampled and analyzed to assess sediment source contributions for a
given timeframe, the approach(es) that should be used to alleviate the problems
of hydraulic sorting and other processes that modify the sediment as it is dis-
persed through the system, the quantitative approach that should be followed
to define the most discriminating fingerprints, the nature of the mixing mod-
els to be utilized, and the methods through which uncertainty in the modeling
results can be characterized and assessed, to mentioned just a few. While it can be
argued that such procedures should be developed by the agency(ies) that intend on
using the approach, the transformation of fingerprinting methods from research
to management tool will require significant input from the scientific commu-
nity.
3. Geochemical fingerprinting of diffuse sources at the catchment scale has yet to
be completely accepted by the scientific community .
The results from geochemical fingerprint studies conducted on diffuse pollu-
tion sources continues to be met with skepticism by some highly-respected
geomorphologists and other environmental scientists. A primary issue for some
is the inability of the conventional mixing models to quantitatively assess the
uncertainty of the generated results. Recent refinements in the models to reduce,
assess, and quantify the uncertainty in their results is likely to alleviate much of
this concern in the future. For other scientists, the concern rests on the assumptions
that form the foundation for inverse modeling. For example, in many instances
geochemical fingerprinting documents the ultimate source of the sediment, but
not necessarily the most recent source as the sediment may have been eroded
and transported intermittently along the drainage network before being sampled.
Additional studies will need to be performed to assess the degree to which the
assumptions inherent in fingerprinting are met.
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