自然和人类活动作用下月湖沉积物有机质来源及其演变

潟湖海湾可以保存环境演化和人类活动的良好记录，碳氮元素含量及同位素特征可用来有效地反演这些演化。对位于山东半岛的月湖柱状样和沿岸表层样总有机碳、总氮、稳定碳氮同位素的分析表明，陆源物质对月湖沉积物和有机质的贡献很小，其沉积物中有机质的主要来源是维管植物大叶藻和各种海洋藻类。在2002年前大约140 a的沉积历史中，大叶藻对沉积物有机质的贡献比例呈上升趋势，其中在约1930年和1980年有两次明显的上升，前者可能因为种群的快速繁育，后者则可能是1979年口门筑坝后由于湾内环境恶化，大叶藻开始大量死亡的表现。月湖海洋藻类的有机碳埋藏通量在沉积记录中保持相对稳定，而大叶藻则增加了一倍，但两者都有一定程度的波动。研究结果表明自然环境演变（如沙嘴生长、口门缩小）和人类活动（如筑坝、修筑虾池）对月湖生态环境及有机碳埋藏的影响在沉积物中有清晰的记录。

The influences of natural and human activities on sources and evolution of organic matter in the Yuehu Lagoon sediments

Information of environmental changes and human activities can be preserved in lagoon sediments potentially, and reconstructed through the analyses of concentration and isotopic composition of carbon and nitrogen in organic matter. The Yuehu Lagoon, located in the Rongcheng Bay at the eastern tip of Shandong Peninsula, is a small lagoon-tidal inlet system. Our work on a sediment core in the lagoon and 18 near-shore surface sediment samples indicates that the organic matter in the lagoon sediments is mainly sourced from eelgrass （Zostera marina） and marine algae, with negligible terrestrial input. The results of carbon, nitrogen element and isotope analyses show that the contribution of eelgrass kept increasing in the past ~140 years before 2002, especially in two periods of around 1930 and near 1980. The former increasing might be resulted from the prosperity of eelgrass;the latter was probably caused by the massive death of eelgrass after the dam construction near the lagoon mouth in 1979 that deteriorated the lagoon environment significantly. Compared with the relatively stable organic carbon burial flux of marine algae, that of eelgrass increased about two-fold, but both had some fluctuations. Therefore, the influences of natural evolution （e.g., the growth of sandspit） and human activities （e.g., the dam construction） on ecological environment and organic carbon burial are clearly recorded in the sediments of Yuehu Lagoon.