Environmental Engineering Reference
In-Depth Information
CHAPTER 4
Use of Stable Isotopes in Mercury Research
HOLGER HINTELMANN
Mercury, with an average atomic weight of 200.59
0.02,
has seven stable isotopes and numerous radioactive isotopes.
The representative abundance percentages (De Laeter et al.,
2003) of the individual isotopes are
196
Hg (0.15
A BRIEF HISTORY OF MERCURY ISOTOPE RATIO
MEASUREMENTS
Measurement of Mercury Isotopes by Mass Spectrometry
Sample Introduction
Gold Trap Amalgamation and Preconcentration
Direct Injection of Gaseous Elemental Mercury
Continuous-Flow Cold-Vapor Generation
Gas Chromatography
Sample Preconcentration Strategies
0.01),
198
Hg (9.97
0.20),
199
Hg (16.87
0.22),
200
Hg (23.10
0.19),
201
Hg (13.18
0.09),
202
Hg (29.86
0.26), and
204
Hg
(6.87
0.15). The provided uncertainties are rather large,
presumably caused either by measurement uncertainties
or as a result of actual variations in natural isotope abun-
dance. All radiogenic Hg isotopes, including
197
Hg (t
1/2
NOMENCLATURE OF MERCURY ISOTOPE
FRACTIONATION
Mass Bias Correction
64.14 hours) and
203
Hg (t
1/2
46.612 days) (Korea Atomic
Energy Research Institute, 2000), do not occur naturally,
and are not subject of this chapter.
THEORY OF MERCURY ISOTOPE FRACTIONATION
Delta Notation
Precision of the Analytical Measurement
A Brief History of Mercury Isotope Ratio
Measurements
MERCURY ISOTOPE DATA OF NATURAL SAMPLES
Sediments
Ores
Meteorites
Coal
Water
Air
Aquatic Food Web Samples
The measurement of isotope fractionation was originally
established for studying biogeochemical pathways of light
elements (H, C, N, O, and S). More recently, this concept was
extended to almost the entire periodic table and applied to
many fi elds, including geology and environmental, planetary,
and earth sciences. Mercury is one of the heaviest stable ele-
ments and has an intriguing isotope system. Its chemical-
physical properties, a relatively large mass range (m/z
196 -
204), high elemental volatility, multiple redox states, and the
ability to form covalent bonds provide many opportunities to
fractionate isotopes. Unlike lead, there is no radiogenic source
of Hg, and any isotopic variation would clearly be the result
of fractionation processes. Early investigations deliberately
generated rather large Hg isotope fractionations in laboratory
experiments (Brönsted and von Hevesy, 1920). However, ana-
lytical limitations hampered progress in observing naturally
occurring smaller deviations (Nier, 1950). First reports regard-
ing natural variations were obtained by gas-source isotope
MERCURY ISOTOPE SYSTEMATICS AND PROCESSES
CAUSING MERCURY ISOTOPE FRACTIONATION
Reduction Processes
Evaporation and Volatilization
Methylation
BINDING OF MONOMETHYLMERCURY
TO PROTEINS
Source Tracking
FUTURE DIRECTIONS
