TITLE:
Evaluation of Pollution Sources of Zinc in Tokyo Bay Based on Zinc Isotope Ratio in Sediment Core
AUTHORS:
Masahiro Sakata, Shohei Okuizumi, Asami Suzuki Mashio, Takeshi Ohno, Shuhei Sakata
KEYWORDS:
Zinc, Pollution Sources, Sediment Core, Zinc Isotope Ratio, Tokyo Bay
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.7 No.8,
August
19,
2019
ABSTRACT: This study evaluated the sources of Zn pollution in
Tokyo Bay, Japan, on the basis of δ66Zn
in a sediment core. The Zn concentration in sediments in the 1980s-2000s was
considerably higher than the background concentration, suggesting that there
remain important sources of Zn in the bay. The δ66Zn (+0.51‰) of anthropogenic Zn estimated in the core
was significantly higher than those (approximately –0.1‰ - +0.2‰) of treated
water from sewage treatment plants and vehicle-related sources. A large number
of electroplating plants are located in Tokyo areas. It is assumed that Zn in
effluents from electroplating operations is isotopically heavier owing to a
negative isotopic effect on Zn electroplating. This tends to support the
hypothesis that river bottom sediments, which were contaminated with Zn in the
untreated effluents from electroplating plants in the past, are the principal
sources of anthropogenic Zn in Tokyo Bay in the 1980s-2000s.