海南岛双池玛珥湖沉积中的碳、氮地球化学记录及其环境意义

CARBON AND NITROGEN ELEMENTS GEOCHEMICAL RECORDS AND PALAEOCLIMATE CHANGES OF SHUANGCHI MAAR LAKE IN HAINAN ISLAND

根据岩芯的碳、氮含量及其比值分析并结合其他气候替代指标的分析结果 ,恢复了海南岛双池玛珥湖末次冰消期以来的古气候变化。全新世大暖期始于 740 0aBP,结束于 2 70 0aBP左右 ,期间热带地区气候湿热 ,植物茂盛 ,双池玛珥湖主要处于沼泽化阶段 ,蒸发量与降雨量持平。但大暖期中仍存在气候的快速波动事件 ,约 72 0 0aBP和 70 0 0aBP前后、6 0 0 0— 5 90 0aBP、4 30 0—4 0 0 0aBP期间气候转凉 ,有机质生产力降低。大暖期前后 ,分别有明显的凉温但季节性暴雨频繁的气候(80 0 0— 740 0aBP、2 70 0— 2 30 0aBP) ,表示气候模式发生变化 ,降雨量相对大于蒸发量。此时双池玛珥湖处于深水期 ,由于气温降低以及湖水上升引起的湖边陡壁植被覆盖面积减少 ,植物生产力降低 ,导致了岩芯中有机质的低含量。

The high-resolution analysis of the content of total organic carbon (TOC), total nitrogen (N) and TOC/N ratio, together with other climate proxy analysis from core SC-1 in Shuangchi Maar Lake in Hainan Island has been made to reconstruct the tropical climate changes since the Last Deglacial period. The Holocene Megathermal began at 7 400 a BP,and ended at about 2 700 a BP. During the time, climate was warm and humid; vegetation flourished in the tropics, and the evaporation was equal to the precipitation. So the Shuangchi Maar Lake became a swamp in most of the time. But there still existed fast climate changing events in the Holocene Megathermal. During the time of 7 200 a BP, 7 000 a BP, 6 000-5 900 a BP, 4 300-4 000 a BP, the productivity of organic mater had remarkable low values, showing that the weather was cool. Before and after the Megathermal (8 000-7 400 a BP,2 700-2 300 a BP), the climate condition was cool with frequent seasonal strong storms, which demonstrated the climate pattern changing. At that time, evaporation was less than precipitation, and the Maar Lake was in its deep-water time. Consequently, the land area around the lake decreased due to the relative cold temperature, leading to the low productivity of vegetation and the low content of organic matter in the core.