The sediment-water distribution coefficient, K d, is one of the most important parameters in radionuclide assessment models. In this study, we determined K ds of stable iodine (I) in estuarine and coastal regions. We studied 16 estuarine and coastal regions of Japan and obtained I data on water and sediments. Data on salinity, pH, dissolved organic carbon and dissolved oxygen in water, and organic carbon (OC) in sediments were also obtained as estuarine variables. Determined K ds of I in the Sagami River estuary decreased along the salinity gradient (salinity range, 0.1-33.8), indicating that salinity is one of the important factors controlling the K d values; however, when the K d values were compared among all the estuaries, the difference between minimum and maximum K d values varied by about two orders of magnitude in a narrow salinity range of 30.0-34.4. A significant correlation between K d value and OC content in sediments was observed in all the stations with a salinity of ≥30 except for stations in the Ishikari and Onga River estuaries. The exceptions are probably due to different sources of the sediments, which are explained by the results of relatively low I/OC ratios in sediments in those two estuaries, compared to the other estuaries. Thus, OC in sediments as well as salinity may be responsible for the variation of K ds of I in the estuarine and coastal regions.
- Estuarine and coastal regions
- Organic carbon in sediments
- Stable iodine as an analog to radioactive iodine
ASJC Scopus subject areas
- Environmental Science(all)
- Management, Monitoring, Policy and Law