人类活动对山东半岛典型海湾生态系统环境的影响及其碳储效应

Anthropogenic activities especially urbanization have caused the deteriorations of China’s bay ecosystem environments over the last 50 years, and best indicated by the frequent occurrence of harmful algal bloom caused by eutrophification. Such ecosystem environment changes have also altered the carbon cycles, and carbon storage has been listed as one of the key parameters in the Ocean Health Index. Thus, it is important to estimate the carbon storage potential of bay sediments, but this region is not well studied. Key questions remain to be addressed include (1) how ecosystem changes have affected sediment carbon storage in bay sediments? (2) how to estimate the influence of anthropogenic activities on bay sediment carbon storage over the last 50 years? This project will focus on three typical bays of the Shandong Peninsula, the Jiaozhou Bay, the Laizhou Bay and the Sishili Bay. By combining field studies, laboratory measurements, synthesis of historical and published data and core reconstruction, we will obtain records for terrestrial inputs of nutrients and organic matter, ecosystem paramers of productivity-community structure and dissolved oxygen, and carbon storage for these bays. Our study will enable us to better decipher the forcing of urbanization on bay ecosystem environments, and to estimate effect of such changes on carbon storage. We aim to establish a new index to evaluate the potential of carbon storage for these bays, which would provide the basis for formulating policies to improve bay environments.

人类活动尤其是城市化在过去几十年加剧了我国海湾生态系统环境的恶化，其中富营养化所导致的有害藻华频发是最重要体现。海洋碳储（Carbon Storage）功能成为评估海洋健康的主要指标之一，而生态系统环境变化也响应了海湾碳循环。沉积有机质埋藏是海湾碳储的主要机制但研究不深入。此研究的科学问题首先是如何评估生态系统环境变化对海湾沉积碳储的影响，第二是如何量化过去50年人类活动对碳储的影响。本项目选择山东半岛胶州湾、莱州湾、四十里湾为研究区域，通过海湾及周围调查与科考、整理和同化已经累积和发表的资料、并结合沉积记录重建，获得陆源物质（营养盐、有机质等）输入、海湾生态系统环境（生产力、群落结构、溶解氧等）、有机质埋藏量等参数的演变记录；厘清人类活动对典型海湾生态系统环境的影响，评估人类活动和生态环境变化对沉积有机质埋藏效率的响应，并建立评估海湾碳储功能新指标，为制定改善海湾生态环境政策提供依据。

本项目聚焦人类活动对山东半岛胶州湾、莱州湾、四十里湾生态环境演变和碳储的影响，通过海湾周围现场调查及多个航次的海湾科考、实验室分析测定、并结合沉积记录重建，估算了海湾的沉积有机碳来源及碳储量，量化了人类活动的影响，并评估了其碳储意义；研究了海湾厌氧氨氧化活动的来源、分布特征及影响因素，探究了富营养化等人类活动对海湾生态环境变化的影响；给出了三个研究海域人类活动土地利用变化模式计算方法，构建了城市化进程作用下海湾与人类活动强度指数模型，定量评估了近四十年来三个海湾人类活动强度的变化，并结合营养盐输入来源，提出城市环境保护政策的实施近二十年来在近海环境恢复中的关键作用。主要结论和新认识如下：.（1）胶州湾大沽河来人类活动源对沉积有机碳贡献高达78%，胶州湾内古老化石有机质来源贡献为29%-41%。.（2）莱州湾沉积（0-20 cm）有机碳储量平均值为20.6 t/ha，低于我国大多数省市的土壤有机碳储量；莱州湾海洋健康指数（OHI）中碳储（carbon storage）得分为37，低于我国平均水平（51），同时远低于世界平均水平（75）。.（3）胶州湾沉积物中的厌氧氨氧化生物标志物梯烷脂主要来自于夏季水体颗粒物的沉降；莱州湾厌氧氨氧化活动的强度受南部沿岸河流输入的影响。.（4）基于模式计算，1984-2020期间，胶州湾人类活动指数从60增长至140，莱州湾和四十里湾流域大约从40增加到60。.项目共发表论文41篇，其中SCI高水平论文27篇，中文核心8篇；多篇第一标注和第二标注的论文发表在Geochimica et Cosmochimica Acta, Paleoceanography，Global and Planetary Change, Ecological Indicators等国际顶尖和权威期刊。培养了多位中青年学术骨干，项目成员肖晓彤于2020年获得国家自然科学基金委优秀青年基金资助。依托项目培养毕业了7位博士研究生，4位硕士研究生。