Reaction with iodide (I⁻) at the sea surface is an important sink for atmospheric ozone, and causes sea-air emission of reactive iodine which in turn drives further ozone destruction. To incorporate this process into chemical transport models, improved understanding of the factors controlling marine iodine speciation, and especially sea-surface iodide concentrations, is needed. The oxidation of I⁻ to iodate (IO₃⁻) is the main sink for oceanic I⁻, but the mechanism for this remains unknown. We demonstrate for the first time that marine nitrifying bacteria mediate I⁻ oxidation to IO₃⁻. A significant increase in IO₃⁻ concentrations compared to media-only controls was observed in cultures of the ammonia-oxidising bacteria Nitrosomonas sp. (Nm51) and Nitrosoccocus oceani (Nc10) supplied with 9–10 mM I⁻, indicating I⁻ oxidation to IO₃⁻. Cell-normalised production rates were 15.69 (±4.71) fmol IO₃⁻ cell⁻¹ d⁻¹ for Nitrosomonas sp., and 11.96 (±6.96) fmol IO₃⁻ cell⁻¹ d⁻¹ for Nitrosococcus oceani, and molar ratios of iodate-to-nitrite production were 9.2 ± 4.1 and 1.88 ± 0.91 respectively. Preliminary experiments on nitrite-oxidising bacteria showed no evidence of I⁻ to IO₃⁻ oxidation. If the link between ammonia and I⁻ oxidation observed here is representative, our ocean iodine cycling model predicts that future changes in marine nitrification could alter global sea surface I⁻ fields with potential implications for atmospheric chemistry and air quality.

在海面与碘化物 (I ^- ) 的反应是大气臭氧的重要汇，并导致活性碘的海气排放，进而进一步推动臭氧的破坏。要将这一过程纳入化学传输模型，需要更好地了解控制海洋碘形态的因素，尤其是海表碘浓度。I ^-氧化为碘酸盐（IO ₃ ^-）是海洋I ^-的主要汇，但其机制尚不清楚。我们首次证明海洋硝化细菌介导 I ^-氧化为 IO ₃ ^-。IO ₃显着增加^-在氨氧化细菌Nitrosomonas sp 的培养物中观察到与仅培养基对照相比的浓度。(Nm51) 和Nitrosoccocus Oceani (Nc10) 提供 9–10 mM I ^-，表明 I ^-氧化为 IO ₃ ^-。细胞归一化的生产速率分别为15.69（±4.71）飞摩尔IO ₃ ^-细胞^-1 d ^-1为亚硝化单胞菌属，和11.96（±6.96）飞摩尔IO。₃ ^-细胞^-1 d ^-1为亚硝化oceani和碘酸盐与亚硝酸盐的摩尔比分别为 9.2 ± 4.1 和 1.88 ± 0.91 。对亚硝酸盐氧化细菌的初步实验显示没有证据表明 I ^-到 IO ₃ ^-氧化。如果此处观察到的氨和 I ^-氧化之间的联系具有代表性，那么我们的海洋碘循环模型预测，未来海洋硝化作用的变化可能会改变全球海面 I ^-场，从而对大气化学和空气质量产生潜在影响。