海洋负排放技术及“人工灰尘”耦合技术概念

Ocean Negative Carbon Technology and the Concept of“Artificial Dust”

随着全球气候危机的加剧,实现碳中和的任务变得更为紧迫。中国政府承诺在2060年实现碳中和,除了加快能源转型、减少化石燃料消耗外,还需大力发展负排放技术以抵消社会生产生活中难以避免的碳排放。海洋作为地球上最大的活跃碳库,具有巨大的储碳潜力。围绕海洋负排放的研发方兴未艾,其主要技术路径包括渔业碳汇、陆海统筹、地质封存、人工上升流、增强风化以及铁施肥等。其中,增强风化和铁施肥等技术都涉及人为投加外源物质到海洋,理论上可通过对投加组分和方式的复合优化,实现多技术路径的耦合,进一步提升海洋固碳和储碳的效率。基于此提出了“人工灰尘”这一潜在的耦合技术路径。“人工灰尘”以提高海洋储碳量(而非初级生产力)为技术目标。拟通过改良铁施肥所用材料及投加方式提高其作用时效,并实现对藻类种群结构的调整,促进更难降解的、更易下沉的藻类生长。此外,在藻类死亡和降解高峰时段,再次投加硅酸盐岩/矿物粉末为主体的二级“人工灰尘”,基于增强风化原理提升海水碱度,同时利用矿物溶解释放的钙和镁等离子促进有机碳团聚沉降,促进其在沉积物中的埋藏。“人工灰尘”这一耦合技术概念的提出可为今后海洋负排放的理论研究提供更广阔的思路。

The intensification of the global climate crisis has heightened the urgency of achieving carbon neutrality.The Chinese government aims to achieve carbon neutrality by the year 2060.To achieve this goal,in addition to accelerating energy transformation and reducing fossil fuel consumption,we also need to develop“negative carbon technologies”to offset the unavoidable carbon emissions in social production and life.The ocean has immense potential for carbon storage,as it is the largest active carbon sink on Earth.The research and development of“negative carbon technology”in the ocean is on the rise.Its primary technical paths include blue carbon management,geological storage,artificial upwelling,enhanced weathering,and iron fertilization.Theoretically,the coupling of multiple technical paths can be realized through the compound optimization of the components and methods of addition,as enhanced weathering and fertilization of iron involve the artificial addition of exogenous substances to the ocean;thus,the efficiency of ocean carbon sequestration and carbon storage can be further improved.In this paper,we refer to this potentially composite technique as“artificial dust”.The ultimate purpose of“artificial dust”is to increase the production of recalcitrant organic carbon(rather than primary productivity),accelerate the deposition and burial of organic carbon,and increase seawater alkalinity.It is intended to adjust the algal population structure and promote the growth of algae that are more difficult to degrade by improving iron fertilization materials and dosing methods.Further,in the peak season of algae death and degradation,the second-level“artificial dust”primarily composed of silicate rock/mineral powder is added.This promotes the aggregation and deposition of organic carbon,accelerates the fixation of inorganic dust produced by algal mineralization based on enhanced weathering theory,and reduces the re-release of CO_(2)from seawater.The technical concept of“artificial dust”provides a broader insight for future theoretical research on marine“negative carbon technology.”