1. National Institute for Agro- Environmental Sciences, Japan Nobuyasu SEIKE Temporal Trend of POPs Residue in Japanese Agricultural Soils

2. Agricultural soils (paddy and upland) periodically collected from all over Japan since 1960s are preserved in the National Institute for Agro-Environmental Sciences (NIAES). Air-dried and sieved (<2 mm) soils were preserved in polyethylene bottles at room temperature. Preserved Soils (15 sites) Sampling Sites Dioxins and Dioxin-like PCBs 7 sites Organochlorine Pesticides 15 sites

3. ● Temporal changes of dioxins and dioxin-like PCBs concentrations associated with their sources in paddy soils TopicsTopics ● Temporal changes of organochlrine pesticides concentrations in paddy soils ● In order to provide the factors for the decline of POPs in soils, half-lives for the disappearance of POPs in paddy soils were calculated.

4. Dioxins (PCDD/Fs) (x + y = 1~ 8) PCDDs PCDFs

5. Temporal Change of PCDD/Fs Conc. in Japanese Paddy Soils Temporal Change of PCDD/Fs Conc. in Japanese Paddy Soils Sampling Year Max. Mean Min. *Ministry of Environment and Ministry of Agriculture, Forestry, and Fisheries (2001) pg-TEQ g -1 -dry PCDD/Fs concentrations ware increased drastically during the 1960s, began decreasing in the 1970s gradually.

6. OCDD Conc. 1368/1379- TeCDD Conc. Year PCP CNP Emission of PCDD/Fs, and OCDD 1,3,6,8-TeCDD Concentration Emission of PCDD/Fs, and OCDD 1,3,6,8-TeCDD Concentration Rapid increasing of PCDD/Fs concentrations are due to use of PCP and CNP

7. PCA Plot Site 2 PCDD/Fs produced from combustion processes was thought to be the major source before PCP was used The PCDD/F profiles in the paddy soils changed significantly after using PCP and CNP in the 1960s and the 1970s There were few significant changes in the PCDD/Fs profiles. Namely, another important PCDD/Fs source have not existed since 1980s.

8. Quantitative Source Identification by CMB* *developed by Kashiwagi (2002) J. Appl. Statist. ~1960 (before PCP use): originated from combustion processes early-1960s ~ mid-1960s: PCP end-1960s ~ : PCP and CNP (exceed 95%)

9. Mass Balance of PCDD/Fs in Japanese Paddy Fields (1958-2000) Mass Balance of PCDD/Fs in Japanese Paddy Fields (1958-2000) Cumulative Input Cumulative Input Disappearance from Paddy Field Half-lives: 17.6 yr *Runoff : 2% / yr *Masunaga et al. ES&T (2001) *Ministry of Environment and Ministry of Agriculture, Forestry, and Fisheries Nationwide Survey* （ 1999- 2002 ）

10. Dioxin-Like PCBs non-ortho PCBs mono-ortho PCBs 12 Congeners Known major source - Commercial PCBs (Kanechlors) - Combustion Processes 50 ×10 6 kg Total PCBs use in Japan banned at 1974

11. Year pg-TEQ g -1 -dry Max. Mean Min. Temporal Trend of Dioxin-like PCBs Concentrations in Paddy Soils Temporal Trend of Dioxin-like PCBs Concentrations in Paddy Soils Dioxin-like PCBs concentrations were considerably lower than PCDD/Fs. Year pg-TEQ g -1 -dry PCDD/Fs Dioxin-like PCBs Dioxin-like PCBs concentrations are decreased during 1970s, and then, began to increasing gradually.

12. ΣPentaCBs The ratio of #126 to ΣPentaCBs have been increased since 1970s The Ratio of #126 to Σ PentaCBs = Dioxin-like PCBs originated from combustion processes have been increasing gradually

13. Organochlorine Pesticides (OCPs) Aldrin 2.5×10 6 kg 2.5×10 6 kgDieldrin 0.7×10 6 kg 0.7×10 6 kg Endrin 1.5×10 6 kg 1.5×10 6 kg Chlordanes 0.2×10 6 kg 0.2×10 6 kg 17 ×10 6 kg for domestic pest control 17 ×10 6 kg for domestic pest control DDTs 23 ×10 6 kg 23 ×10 6 kg HCHs 280 ×10 6 kg Heptachlors 1.5×10 6 kg 1.5×10 6 kg HCB Not Registered Not Registered Mirex Usage in Japan (A.I base) Compounds Banned Year 1971 1971 1975 1975 1975 1975 1968 1986

14. DDTs HCHs Drins Chlordanes HCB HPCLs Mirex Temporal Change of OCPs Conc. in Japanese Paddy Soils Temporal Change of OCPs Conc. in Japanese Paddy Soils Temporal changes in OCPs concentrations in paddy soils reflected the use of pesticides.

15. Temporal Change of OCs Conc. in Human Breast Milk from Osaka, Japan Temporal Change of OCs Conc. in Human Breast Milk from Osaka, Japan

16. Half-lives in Paddy Soils

17. Kow vs Half-lives

18. Correlations between Half-lives and

19. Concluding Remarks It is, therefore, expected that further POPs contamination on agricultural soil will not occur, and POPs concentrations in agricultural soil as well as air, water and biota, will decrease gradually. It is, therefore, expected that further POPs contamination on agricultural soil will not occur, and POPs concentrations in agricultural soil as well as air, water and biota, will decrease gradually. ● In Japan, use of OCPs was already banned in the early 1970s. ● PCP and CNP was also banned in the 1990s. ● The content of PCDD/Fs is checked at the agricultural chemicals registration ● The emission gas controls on waste incinerators and improvements of incineration facilities have been imposed since end of 1990s by the Japanese government

20. Acknowledgments This work was supported in part by a Grant-in-aid (Hazardous Chemicals and Environmental Research) from the Ministry of Agriculture, Forestry and Fisheries and the Ministry of Environment, Japan, respectively. I thank Dr Otani, T. and Dr Eun, H. National Institute for Agro-Environmental Sciences, for useful discussions.