We report the vertical and horizontal distributions of inorganic iodine (iodide and iodate) and their related species (bromide nitrate and nitrite) in the Seto Inland Sea, which is a semi-enclosed coastal sea area of western Japan. In this study, ion chromatography with ultraviolet detection was employed to determine the iodide, iodate, bromide nitrate, and nitrite levels simultaneously in a single run. Iodide was higher at inshore sites than at offshore sites. Vertical profiles showed that iodide increased in the bottom layer of inshore sites of Osaka Bay and Hiroshima Bay, but were low in the bottom layer of the Kii Channel, the main channel connecting Osaka Bay with the Pacific Ocean. Iodates were low in the low-salinity inshore surface, but were high in the bottom layer of the Kii Channel. The riverine flux of iodine to the coastal marine environment was negligible. The vertical profiles of total inorganic iodine (iodide + iodate) looked uniform; however, plots of total inorganic iodine versus salinity demonstrated a net loss of total inorganic iodine in the low-salinity inshore surface. The iodine distributions in the Seto Inland Sea could be explained by three-end-member mixing, with one member being non-iodine river water, another high-salinity and high-iodate water of the open ocean, and the final high-iodide and low-iodate inland water with a salinity of around 32–33.

中文翻译：

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日本濑户内海的碘化物和碘化物分布

我们报告了濑户内海（日本西部半封闭的沿海海域）中无机碘（碘化物和碘酸盐）及其相关物种（硝酸溴化物和亚硝酸盐）的垂直和水平分布。在这项研究中，采用紫外检测的离子色谱法可在一次运行中同时测定碘离子，碘酸根，硝酸溴根和亚硝酸根水平。沿海地区的碘化物含量高于海上地区。垂直剖面表明，碘化物在大阪湾和广岛湾沿岸海域的底层增加，但在连接大阪湾与太平洋的主要通道纪河道的底层低。在低盐度近海表层，碘含量低，但在基伊海峡的底层，碘含量高。碘向沿海海洋环境的河流通量微不足道。总无机碘（碘化物+碘酸盐）的垂直分布看起来很均匀。然而，总无机碘与盐度的关系图表明，低盐度近海表层的总无机碘净损失。濑户内海的碘分布可以通过三端混合来解释，其中一个是非碘河水，另一个是高盐度和高碘的公海水，最后是高碘和高碘。盐度约为32-33的低碘酸盐内陆水。