中国近海生态环境变化的同位素示踪研究

同位素在确定物质来源、指示生物地球化学循环路径、定量生物地球化学过程速率等方面具有独特的优势，本文以近海生态环境变化研究中常用的稳定同位素（13C、15N、18O）和放射性核素（14C、234Th、232Th、230Th、228Th、210Po、210Pb、137Cs、226Ra、228Ra、224Ra、223Ra）为对象，介绍它们在揭示海洋有机质来源、食物网结构、水体缺氧机制、氮循环过程、颗粒动力学、海底地下水输入、有机地球化学过程、沉积年代学等方面的应用，侧重于总结我国近海生态环境研究中同位素示踪取得的进展。伴随着我国经济的发展，近百年来我国近海生态环境也发生了明显的变化，基于同位素示踪揭示的近海富营养化和沉积环境的演变规律表明，我国近海生态环境自20世纪50年代起经历持续的变化，特别是在过去20~30年时间里，近海生态环境的变化尤为剧烈，反映出人类活动是我国近海生态环境变化的主要驱动力。未来需要通过发展新的同位素技术及拓展更广泛的应用，围绕近海海洋生态环境变化的突出问题，重点揭示近海生态环境变化的响应特征、变化速率和作用机制，从而系统地掌握近海生态环境的时空变化规律。

The eco-environmental changes in China coastal seas elucidated from isotope tracers

Isotopes are unique in determining the source of material, indicating the path of biogeochemical cycle, and quantifying the rate of biogeochemical processes in marine environments. In this paper, stable isotopes (¹³C, ¹⁵N, ¹⁸O) and radionuclides (¹⁴C, ²³⁴Th, ²³²Th, ²³⁰Th, ²²⁸Th, ²¹⁰Po, ²¹⁰Pb, ¹³⁷Cs, ²²⁶Ra, ²²⁸Ra, ²²⁴Ra, ²²³Ra) commonly used in coastal eco-environmental studies were targeted to reveal the source of marine organic matter, structure of food web, mechanism of coastal hypoxia, nitrogen cyclic processes, particle dynamics, submarine groundwater input, organic geochemical processes, sedimentary chronology, etc. We focused on summarizing recent progresses of their applications in the study of China coastal seas. With the start and development of economy, the eco-environments of China coastal seas have undergone significant changes in the past one hundred years. The evolution of eutrophication and sedimentary dynamics revealed by isotopes indicated that the eco-environment of China coastal seas has experienced persistent changes since the 1950s. Especially in the past 20-30 years, the changes have been dramatic, reflecting that human activities are the main driving force for the changes. In the future, it is need to study the response characteristics, variation rates and mechanisms of coastal eco-environmental changes through the development of new isotope techniques and their widely applications. In this way, we will be able to systematically grasp the temporal and spatial changes of the coastal ecosystem.