A New Threat to the Stratospheric Ozone Layer from Anthropogenic Very Short-lived Halocarbons

平流层的臭氧层保护地球免受太阳大部分有害的紫外线辐射。人为排放长寿命氯氟化碳造成的臭氧损耗是过去几十年的主要环境问题之一。在1987年《蒙特利尔议定书》之后，氟氯化碳的排放量已大幅减少，因此，预计臭氧层将在今后几十年逐步恢复。另一方面，由于新技术的发展，海洋极短寿命卤化烃（VSLH）也有可能破坏臭氧，预计会增加。特别是船舶压载水的氧化水处理和不断增加的宏观藻类养殖影响了海洋生物地球化学系统，并被怀疑大大增加了VSLH的产生和排放。除了对臭氧层的破坏作用外，来自海洋的人为VSLH还将影响大气的辐射强迫和氧化能力，即大气最终清除包括污染物在内的许多微量气体的能力。人们只是逐渐认识到，极低辐射辐射即将增加，这是对辐射强迫和臭氧恢复的一种新的人为威胁，因此，适当评估有关这类物质释放的计划中的人为活动是高度优先的。这项建议的目的是评估目前和未来的人为VSLH排放，它们对大气化学和物理的多方面影响，特别是它们延长平流层臭氧消耗的潜力。第一步，将编制一份全球海洋排放人为VSLH清单。第二步，基于高分辨率大气化学传输模型，将对海洋排放后大气中人为VSLH的命运进行量化。这就需要发展海岸线解析模拟系统，最终可以用来参数化全球气候模式中的关键过程。在第三步中，将评估人为VSLH对臭氧化学、全球氧化能力和辐射收支的总体作用，并确定可能的气候反馈机制。这项研究将以多方面的方式进行，包括综合现有数据、现场测量、海洋环流、生物地球化学、大气化学运输和全球气候模型。这项跨学科研究建议将能够回答一个新出现的问题，即海洋和海洋环境中的人为活动是否会对平流层臭氧层的恢复构成新的威胁。这种大气风险评估具有重大的社会意义，并将为决策者规划未来人类活动提供至关重要的信息。

The stratospheric ozone layer protects the Earth from most of the sun's harmful ultraviolet radiation. The depletion of ozone in response to anthropogenic emissions of long-lived chlorofluorocarbons (CFCs) has been one of the major environmental issues of the last decades. Emissions of CFCs have been strongly reduced following the Montreal Protocol of 1987 and as a consequence a gradual recovery of the ozone layer over the next decades is expected. Marine Very Short-Lived Halocarbons (VSLH), which also have the potential to destroy ozone, are, on the other hand, expected to increase due to new technologies. In particular, oxidative water treatment of ship ballast water and increasing macro algae farming impact the marine biogeochemical systems and are suspected to drastically enhance the production and emissions of VSLH. In addition to their damaging effect on the ozone layer, anthropogenic VSLH from the oceans will also impact the radiative forcing and the oxidizing capacity of the atmosphere, i.e. the capacity of the atmosphere to ultimately remove many trace gases, including pollutants. There is only an emerging awareness of the impending increase of VSLH which represents a new, human-made threat to radiative forcing and ozone recovery and it is of high priority to properly assess planed anthropogenic activities regarding the release of such substances. This proposal aims to assess current and future emissions of anthropogenic VSLH, their multisided impact on atmospheric chemistry and physics, and in particular their potential to prolong stratospheric ozone depletion. In a first step, a global inventory of oceanic emissions of anthropogenic VSLH will be developed. In a second step, the fate of anthropogenic VSLH in the atmosphere after their emissions from the ocean will be quantified based on high resolution atmospheric chemistry-transport modelling. This requires the development of coast line-resolving modelling systems which can eventually be used to parameterize the key processes in global climate models. In a third step, the overall role of anthropogenic VSLH for ozone chemistry, global oxidizing capacities and the radiation budget will be assessed and possible climate feedback mechanisms will be identified. The research will be undertaken in a multifaceted way comprising the synthesis of existing data, in-situ measurements, ocean circulation-, biogeochemical-, atmospheric chemistry transport- and global climate modelling. The interdisciplinary research proposal will enable the answer to the emerging question if anthropogenic activities in marine and oceanic environments will pose a new threat to the stratospheric ozone layer recovery. Such an atmospheric risk assessment is of large societal relevance and will provide information that is essential for decision makers to plan future human activities.