Iodide in the ocean:distribution and impact on iodine flux and ozone loss

在过去的五年里，该团队领导的研究表明，碘化物与海面臭氧的反应在控制对流层的化学成分方面发挥着重要作用。这一过程直接控制着O3在海洋中的沉积，也是大气中活性碘的主要来源，从而导致对流层O3的大量流失。臭氧浓度会受到直接影响，但通过大气氧化剂的变化，甲烷和气溶胶也会发生间接变化，从而对气候、空气质量和粮食安全产生潜在影响。这可能是对流层O3和氧化剂的地球化学负反馈，因为它取决于大气O3和海洋碘化物浓度，将随着时间的推移而变化。碘也是人体必需的营养素。碘从海洋进入大气层，随后沉积在陆地上，这是海洋碘进入陆地食物链的一个途径，释放到海洋中的碘放射性同位素可能会扩散。这些碘的海洋-大气过程目前正被纳入化学传输模型，但关键的不确定性仍然存在。人们对海洋碘的分布知之甚少，但很可能由于海洋环流、生物生产力和海洋脱氧的变化而发生变化。该提案汇集了海洋和大气科学家，以解决海洋碘通量和相关臭氧汇的不确定性。具体而言，它的目的是量化的主要控制海面碘分布和改善参数化的海-空碘通量和臭氧沉积。这将通过实验室实验、实地测量以及海洋和大气建模相结合来实现。

Over the last five years, research led by this team has made it apparent that the reaction of iodide with ozone at the sea surface plays an important role in controlling the chemical composition of the troposphere. This process directly controls the deposition of O3 to the oceans and is the dominant source of reactive iodine to the atmosphere, which leads to significant loss of tropospheric O3. Ozone concentrations are directly impacted but through changes to the atmospheric oxidants, indirect changes also occur to methane and aerosols leading to potential ramifications on climate, air quality and food security. This is likely a biogeochemical negative feedback for tropospheric O3 and oxidants, which, since it is dependent on both atmospheric O3 and ocean iodide concentrations, will have changed over time. Iodine is also an essential human nutrient. The transport of iodine from the oceans to the atmosphere and subsequent deposition over land is a pathway by which marine iodine may enter the terrestrial food chain, and iodine radioisotopes released to the sea may be dispersed. These iodine ocean-atmosphere processes are now being incorporated into chemical transport models but critical uncertainties remain. The marine iodide distribution is poorly understood, yet it is likely that it will be subject to change as a result of changes in ocean circulation, biological productivity and ocean deoxygenation. This proposal brings together marine and atmospheric scientists in order to address uncertainties in the marine iodine flux and associated ozone sink. Specifically, it aims to quantify the dominant controls on the sea surface iodide distribution and improve parameterisation of the sea-to-air iodine flux and of ozone deposition. This will be achieved through a combination of laboratory experiments, field measurements and ocean and atmospheric modelling.