Record of lead pollution in sediments of the Tokyo Bay, Japan.

Lead isotope ratios in Tokyo Bay sediments and their implications in the lead consumption of Japanese industries.

“…These values are considered to be approximately the accumulation level of non-artificial lead on the basis of the concentra tion profiles in Fig. 2 and Hirao et al (1983a). The lead accumulation rate is enhanced gradual ly as shown in Fig.…”

“…to be a powerful tool for identifying lead from different origins in a system, which would not be eluci dated by measuring the concentration. Murozu mi et al (1982) used this technique for study ing the contribution of anthropogenic lead to the ecosystems of the Hidaka and Tarumae mountains, Hokkaido, Japan and estimated that the lead burden in the ecosystem increased twice as high as the natural level by introduction of Heavy metal pollutions in Tokyo Bay sedi ments and water have been studied by several workers (Matsumoto and Yokota, 1977;Kitano et al, 1980;Hirao et al, 1983aHirao et al, , 1983bHirao et al, , 1984. Even though there may be many factors which control the increase in pollution, these works unanimously pointed out that the pollution has started in the early part of the twentieth cen tury, accelerated since 1950 revealing the maxi mum level in about 1970, and has been decreas ing thereafter.…”

“…The lead accumulation rate in Bay sediments (Hirao et al , 1983a) and the lead concentration in seawater (Hirao et al, 1983b) showed that about 90% of the lead introduced into the Tokyo Bay by air, river and so on deposited in the Bay, and the annual lead accumulation in the Tokyo Bay was estimated to be about 71 tons in 1980. The result of 210Pb measurements for more than 50 cores in the Bay by Matsumo to (1983) suggested that the sedimentation rates were fairly high in the north western part, 0.5g/ cm?y, and became gradually lower toward the southern part where they reached practically zero.…”