52
Peter Stille and Graham Shields
The Pb isotopic analyses imply that only the uppermost centimeters of the soil are
strongly enriched in industrial lead. Although the work from Auh et al. showed
the way, not only to source detection for contaminating heavy metals but also to
the reconstruction of heavy metal circulation in the biosphere, it was not until the
eighties that the Pb isotope method came to be used in environmental research.
The strengths of the Pb isotope systems in demonstrating atmospheric Pb
contamination and differentiating various sources of contamination are clear in the
work of Sturges and Barrie (1987), in which it was shown that the industrial lead
used in Canada and in the USA comes from very different sources.
(~
LAKE ONTARI O _ ~ ~
"~90'~
Rochester
LAKE E ~ B u f l a t o l
~ t a n d
78"W
(~
LA KE O N ~
,L-r.
9 .--,::.:.3
Hami tton ~
I~ocl "~s tt,.r
LAKE E O ~ J B u t f a l
0
]Fig. 4.5. (A) Distribution of Pb concentrations (pmol kg" l) and (B) 206pb/207pb ratios in
surface waters from the great lakes (Lake Ontario, Lake Erie). (Flegal et al. 1989)