150
W. J. Jenkins et al.: A comprehensive global oceanic dataset of helium isotope and tritium measurements
one at McMaster University in Hamilton, Ontario, Canada,
and setting the other machine up at the Scripps Institute of
Oceanography in La Jolla, CA, USA, for Harmon Craig and
John Lupton. These instruments were used in support of the
GEOSECS program and subsequently for a wide variety of
other research projects. One of his students (William J. Jenk-
ins) moved to the Woods Hole Oceanographic Institution in
Woods Hole, MA, USA, where he extended Clarke’s design
:0 construct three other instruments. A post-doctoral investi-
gator from his laboratory (Zafer Top) moved to RSMAS at
the University of Miami and constructed a similar machine.
Clarke also collaborated with a UK mass spectrometer com-
pany to make a commercially produced mass spectrometer
available to the global scientific community.
In his early career, Clarke contributed to the study of me-
teorites and nuclear physics using isotope mass spectrome-
try. Beginning in 1969 Clarke published a series of ground-
oreaking papers on °He/*He measurements in seawater and
lakes (Clarke et al., 1969, 1970; Clarke and Kugler, 1973;
Craig and Clarke, 1970; Craig et al., 1975; Jenkins and
Clarke, 1976; Top and Clarke, 1983; Torgersen and Clarke,
1985). He contributed research to geology, hydrology, lim-
nology, nuclear physics, medicine, and other disciplines and
was active until 2002 publishing on *He-related evidence for
and against cold fusion (Clarke, 2001; Clarke and Oliver,
2003; Clarke et al., 2001).
In addition to developing a mass spectrometer capable of
measuring *He/*He ratios to order 0.1 % on sub-nanomolar
gas samples, Clarke also created a method to measure en-
vironmental levels of tritium (*H) in water samples by the
*He regrowth technique (Clarke et al., 1976), which has be-
come the de facto state of the art in low-level tritium mea-
surements. In addition to being intrinsically simpler than the
traditional low-level method (which involved electrolytic en-
richment combined with low-level proportional gas count-
ing), this method has proved to be more precise (by more
than a factor of 4) and extended the detection limit to lower
levels (by as much as an order of magnitude) (Bayer et al.,
1989; Jenkins et al., 1983; Lott and Jenkins, 1998).
Clarke was inventive and ingenious in the laboratory with
a remarkable ability to recognize opportunities where no one
else could and to pursue them to ultimate success. He was
an accomplished glass blower and constructed vacuum lines
and research apparatuses from scratch using many different
kinds of glass (see Fig. 10). Clarke kept unusual work hours
when not teaching, generally arriving at the laboratory after
lunchtime and toiling into the night. Working with him was
a delight due to his good nature and whimsical sense of Irish
humor but sometimes challenging because he was an invet-
erate prankster.
Figure 10. W. Brian Clarke, working on a high vacuum helium
extraction apparatus (early 1970s)
icated to the measurement of tritium and radiocarbon at the
University of Miami. He made distinguished contributions
to ocean, atmosphere, and groundwater sciences, in particu-
lar to the understanding of the timescales of the transport of
Auids through these systems. Östlund had a life-long devo-
tion to the high-quality measurement of radioactive species.
He received a BS in chemistry in 1949 and a PhD in chem-
istry in 1958. Both were from the University of Stockholm.
Between 1959 and 1961 Östlund developed the electrolytic
enrichment of tritium and deuterium for low-level environ-
mental tritium measurements by gas proportional counting
at the Radioactive Dating Laboratory of the Swedish Geo-
logical Survey. In the early 1960s, he came to the Rosen-
stiel School of the University of Miami. At the Rosenstiel
School, he built a world-class tritium and radiocarbon count-
ing laboratory that set new standards for low-level count-
ing. His laboratory also processed the samples rapidly, and
he generously shared his data with colleagues. As a result,
relatively routine collection and analysis of large quantities
of samples in a timely manner enabled oceanographers to
use the tracer data to gain new insights into the timescales
of oceanographic processes. His work paved the way for the
acceptance of the next generation of tracer oceanographers.
those measuring tritium and helium-3 by mass spectrometry
and those measuring the chlorofluorocarbons.
5.2 H. Göte Östlund (1923-2016)
Östlund was a pioneer in US ocean tracer measurements, es-
tablishing a world-class. low-level counting laboratory ded-
carth Syst. Sci. Data. 11. 441-454. 201“
www.earth-svyst-sci-data.net/11/441/2019:
