浒苔碳汇功能评估及其扩增途径

Estimation of carbon sequestration by Ulva prolifera and potential ways to increase the carbon sink

中文关键词: 浒苔  固碳特点  碳汇评估  碳汇扩增途径

英文关键词: Ulva prolifera  Carbon fixing characteristics  Carbon sink assessment  Pathways to increase carbon sink

中文摘要:

      浒苔(Ulva prolifera)不仅是绿潮暴发的主要生物种类，也是海洋中重要的碳汇生物。浒苔生长速度快、繁殖方式多样、抗逆能力强，能够在短时间内形成大规模生物量，本文在此基础上评述了中国近海浒苔生物在生长和漂移过程中的固碳特点：浒苔具有独特的高pH诱导HCO3–利用机制，可提高HCO3–的吸收效率，并促进漂浮浒苔对空气中CO2的吸收，同时，C4固碳途径增强了漂浮浒苔在高光辐射时的碳固定效率，这种多样化的碳吸收和碳固定模式，使漂浮浒苔光合固碳能力增强，漂浮状态下可以快速积累生物量。以上特点使得浒苔的固碳效率显著高于主要养殖藻类，如海带、裙带菜和紫菜等。2007年以来，黄海海域连续15年暴发世界上最大规模浒苔绿潮，最大分布面积年均在3万km2以上，最大覆盖面积年均超过500 km2，浒苔生物量年均在150万t以上，据此估算，2008―2020年净碳汇量为2.5~27.5万t，年均超过7.8万t，高于主要养殖藻类，如江蓠、紫菜和裙带菜的年均固碳量，仅次于海带的年均固碳量。浒苔巨大的生物量和强大的碳固定能力使其成为一个潜在的、不可忽视的海洋碳汇和碳储途径，建议浒苔绿潮暴发时，进一步加强浒苔打捞力度和资源化利用程度，实现碳利用和去富营养化的双赢，推动浒苔碳汇产业早日加入碳市场，使其成为一个新的低碳经济增长点。

英文摘要:

      Ulva prolifera is the main species in green tides and also an important marine carbon sink organism. It is characterized by fast growth, diverse reproductive modes, and strong resistance to stress. It can form a large-scale biomass in a short time. We review the carbon fixation features in the growth and drift of U. prolifera. It possesses a unique high pH induced HCO3– assimilation mechanism, which can promote CO2 absorption from the air by floating U. prolifera. Moreover, it utilizes the Hatch-Slack Cycle (C4) to enhance carbon fixation rate under high light irradiation conditions. The diverse carbon assimilation and sequestration mechanisms enhance photosynthetic carbon sequestration ability and help the quick accumulation of floating algal biomass. These abilities make the carbon sequestrating efficiency of U. prolifera significantly higher than that of Saccharina japonica, Undaria pinnatifida, and Porphyra haitanensis. Since 2007, the largest green tide in the world occurred in the Yellow Sea and persisted over 15 years. The average annual distribution area of U. prolifera was greater than 30 000 square kilometers, with an average annual coverage area in excess of 500 square kilometers. The average annual outbreak of U. prolifera had a biomass greater than 1.5 million tons. The net carbon sequestration from 2008 to 2020 was estimated to be 25 000~275 000 tons, averaging over 78 000 tons. This figure is higher than that of Gracilaria, P. haitanensis, and U. pinnatifida, and only second to that of S. japonica. The great biomass and strong carbon sequestration ability of U. prolifera has made it a potential new and important marine carbon sink and carbon storage pathway. We suggest strengthening the salvage and resource utilization of U. prolifera. This approach is a win-win situation for carbon utilization and eutrophication removal. These measures will promote the green tide U. prolifera carbon sink in joining the carbon market as soon as possible, to become a new low-carbon economic resource.