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，海面上的碘与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。这一过程直接控制了臭氧向海洋的沉积，是大气中活性碘的主要来源，从而导致对流层臭氧的显著损失。臭氧浓度受到直接影响，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。这可能是对流层臭氧和氧化剂的生物地球化学负反馈，因为它依赖于大气臭氧和海洋碘的浓度，将随着时间的推移而改变。碘也是人体必需的营养物质。碘从海洋向大气的运输和随后在陆地上的沉积是海洋碘可能进入陆地食物链的一条途径，释放到海洋中的碘放射性同位素可能被分散。这些碘海洋-大气过程现在正在被纳入化学运输模型，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，但由于海洋环流、生物生产力和海洋除氧作用的变化，它很可能会发生变化。这项建议将海洋和大气科学家聚集在一起，以解决海洋碘通量和相关臭氧汇中的不确定性。具体地说，它的目的是量化海面碘分布的主要控制因素，并改进海-气碘通量和臭氧沉积的参数化。这将通过结合实验室实验、实地测量以及海洋和大气模型来实现。

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.