Concentration of Antifouling Biocides and Heavy Metals in Sediment Core Samples in the Northern Part of Hiroshima Bay
1N.Tsunemasa, 2H.Harino, 3H.Yamazaki and 4H.Okamura

1.Hiroshima City Institute of Public Health, 2.Kobe College, 3.Kinki Univ., 4. Kobe Univ..
(tunemasa-n@city.hiroshima.jp)

1. Introduction
Organotin (Ot) compounds that were used for many years as antifouling biocides on ships, marine structuresand fishing nets became a problem due to toxicity and accumulation characteristics. From 1997 in Japan, theproduction of paints that contain TBT compounds was prohibited, and so since then alternative to Ot
antifoulants have been used. In September 2008, Ot compounds were prohibited from being used worldwide.
In this research, the Ot alternatives to Ot antifoulants Diuron,Sea-Nine211, Irgarol 1051 and the latter’s
degradation product M1 were investigared in 5 sediment core samples of the northen part of Hiroshima Bay.
The Ot compounds were also investegated to compare the Ot alternative antifoulants. In addition, the heavy
metals (Pb, Cu, Zn, Fe, Mn) and the chronology were measured to better understand what happens after they
have accumulated on the sea floor.

3. Results and Discussion
In the present study, Sea-Nine 211, Diuron, Irgarol 1051 and M1 were detected in the sediment core samples
from Hiroshima Bay.The concentration of antifouling biocides in sediment core samples was much higher than
the sea floor sample’s concentration. Especially, the survey point ➄ sample which had the highest
concentration.
Organotin compounds (TBT and TPT) were only investigated at survey point ➄. TBT and TPT were detectedfrom 48 to 1400µg/kg and from 78 to 550 µg/kg respectively.
Sample No.

Depth(cm)Sedimentation(year)

１０－３

2004.7

２３－６

2003.5

３６－９

2002.3

４９－１２

2001.2５

１２－１５

2000.1６

１５－１９

1998.5

７

１９－２３

1996.8

８２３－２７

1995.1

９２７－３１

1993.2１０

３１－３５

1990.7

１１３５－３９

1985.5

１２３９－４３

1980.4１３４３－４６

1975.8depth(cm)depth(cm)
005

5

10

10

M1
15
2. Materials and Methods
15
Irgarol
20
20
2.1 Sampling Description
TBT
Diuron25
25
TPT
Sea-nine
30
30
At points ① and ② in the fishery harbour there were a lot more leisure boats than commercial fishing boats
3535
anchored. In point ③ of the fishery harbour, the ratio of commercial fishing boats to leisure boats is about the40404545same. The environmental standard point ④ was located in a recess of Hiroshima Bay. Point ⑤ was located in(µg/kg・dry)
5050(µg/kg･dry）the entrance to the dock and it was the point where the concentration of the organotin compounds had been
0100
200
300
0500
1000
1500
2000
high previously.
Fig.2 The analytical result of survey point ➄ on anifouling biocides
2.2 SamplingIn the present study, Pb, Cu, Zn, Fe and Mn were detected in sediment core samples from Hiroshima Bay. TheIn the sea area, the sediment from the sea floor was collected with the sediment core sampler, and sliced into analytical result of survey point ➂ and ➄ was shown in Fig. 3.
3-5 cm thick sections, and stored at -20 centigrade until analysis.

Survey point ➂depth(cm)depth(cm)
00

②
①

④

③⑤2.3 Chemicals
The investigated materials were Diuron, Sea-Nine211, Irgarol 1051and M1, that were all thought to be
popularly used in Japan. Stracture of antifouling compounds are shown in Fig. 1.
ClClClOS

Sea-Nine 211

N C8H17-nClO
CH3NHCN
CH3Diuron

SCH3NCH3H3C C HN
CH3

Fig.1Structers of the alternative Ot compounds

NN

Irgarol
CH2
NH CNCH2

2.4 Chronology
The 210Pb chronology was applied to the cores using the model of Matsumoto (1975), in which core depth iscorrected for the sediment compaction (Yasuhara and Yamazaki ,2005). We also employed a geochronology
137
based upon fallout of the fission product Cs from the stratosphere, where it was introduced by nuclear
weapons testing. The 137Cs profile was corrected for decay (half life, 30yr) during the time between themeasurement and the sediment deposition, only for the period after ca.1950 because the 137Cs should
theoretically not be detected before then. A 137Cs maxima (1963 fallout maximum) corroborates 210Pb ages.

Survey point ➄510

5
Mn

10Zn
Cu

15

Pb

20

15
20

Mn

2530Zｎ
Cu

35

Pb

40
45(mg/kg.dry)

2501000

2000

3000

4000（mg/kg・dry)

5005001000

1500

Fig.3 The analytical result of survey point ➂ and ➄ on heavy metals
4.Conclusion
In comparison with the sea floor sediment sample, the concentration of antifouling biocides in the sedimentcore samples was much higher than the sea floor sediment sample. Especially at survey point ➄ (the entrance tothe dock), where high concentration was detected. The beginning of the accumulation of the antifoulingbiocides coincided with the beginning of the self-control regulation on the organotin compounds. It was clearthat the antifouling biocides did not shift in the sediment in the same way that the heavy metals did.
Acknowledgments
This work was partly supported by a Grant-in-Aid for Scientific Research (Monbukagakusyo B20310019) and the Mitsui & Co., Ltd. Environmental
Fund (2007).
ReferenceMatsumoto E. 210Pb geochronology of sediments from Lake Shinji. Geochemical Journal 9, 1975, 167-172.
Moriwaki Y and Yamazaki H. The impact of 150 years of anthropogenic pollution on the shallow marine ostracode fauna, Osaka Bay, Japan. Marine
Micropaleontology, 2005, 55, 63-74.