南海琼东上升流区过去1 900年海洋生产力记录

A 1 900-year record of marine productivity in the upwelling area of east continental shelf of Hainan Island, South China Sea

  • 摘要: 对南海琼东陆架上升流区一根45 cm海洋沉积柱样进行了年龄和地球化学元素分析,并利用生物源Ba(Babio)重建了研究区过去1 900年的海洋生产力记录。结果表明海洋生产力在过去的1 900年中变化明显,在中世纪暖期时生产力相对较高,而在气候相对凉爽的小冰期时生产力相对低。海洋生产力在过去100多年增加迅速(当前Babio约为210 μg/g),达到过去1 900年以来的最高水平。通过与气候环境记录对比,发现琼东上升流区海洋生产力受东亚夏季风影响显著,并与温度变化之间存在一定的关联。在气候温暖期,东亚夏季风强度增加,引起沿岸上升流增强,使得海洋生产力提高。在全球变暖背景下,人为因素导致的气候变化可能会对该地区海洋生产力造成影响。

     

    Abstract: A 45 cm long sediment core was collected from the upwelling area of the east continental shelf of Hainan Island, South China Sea. Via chronological and geochemical analyses, marine productivity (in terms of Babio) over the past 1 900 years was reconstructed for the study area. The results show that the marine productivity changed significantly over the past 1 900 years, with relatively high productivity during the Medieval Warm Period (MWP), but relatively low productivity during the Little Ice Age (LIA). Marine productivity has increased rapidly over the last century (currently Babio is about 210 μg/g), reaching its highest level over the past 1 900 years. By comparison with the climatic and environmental records, it was found that the marine productivity in the upwelling area was highly affected by the East Asian summer monsoon and also displayed some kind of correlation with temperature. In a warm climate, the intensity of the East Asian summer monsoon enhanced, resulting in an increase in coastal upwelling, which led to increase in marine productivity. Solar activity may also impact on the marine productivity of the upwelling area by affecting climate and intensity of the East Asian monsoon. In the context of global warming, human-induced climate change may impose some effects on marine productivity as well in the study area.

     

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