Stable ‘Non-Traditional’ Isotopes - Application of Geochemical Tracers to Fluvial Sediment - page 114

Chapter 5
Stable 'Non-Traditional' Isotopes

Abstract Recent advances in analytical capabilities, particularly the MC-ICP-MS,
have allowed for a precise determination of a wide range of stable isotopes in geo-
logical and biological materials that could not be assessed prior to the 1990s. As a
result, research into the use of these 'non-traditional' isotopes (or 'non-CHONS') as
tracers of both elemental sources and biogeochemical processes has been increasing
at an exponential rate. While their utilization as a tracer of contaminated sediments
in the near surface environment is often complicated by multiple physical and bio-
logical fractionation processes, there is increasing evidence to suggest that they may
be effectively used as tracers in aquatic environments. In this chapter, we examine
the potential use of four stable metal isotopes (Zn, Cd, Cu, and Hg) that appear
on the basis of the limited studies conducted to date to have the potential to track
sediment-associated trace metals in rivers.

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Keywords Zn isotopes Cd isotopes Cu isotopes Hg isotopes Non-traditional

sediment tracers

5.1 Introduction

In addition to the radiogenic isotopes examined in the previous chapter, significant
attention has been given to various stable isotopes for elucidating Earth surface
processes, particularly the isotopes of H, C, N, O, S, and Si. The isotopes of C and O
have been particularlywell investigated and utilized; in fact, more than 10,000 papers,
abstracts, and thesis have been published on C and O isotopic variations alone since
the first measurements weremade in the 1930s, themajority to investigate surface and
near-surface biogeochemical processes (Baskaran 2011 ). Study of the remaining sta-
ble isotopes (e.g., those of the transition and post-transition elements) was hampered
before the 1990s by an inability to precisely measure their abundance in geologi-
cal and biological materials. However, recent advances in analytical instrumentation
(including the development of the MC-ICP-MS) have resulted in a dramatic increase
in their potential application as environmental tracers (see Baskaran 2011 for a brief
history of instrumental development). These isotopes are now frequently referred to
as the 'non-traditional' isotopes.