类脂生物标志物重建近150年来东海陆架区DH5-1站位浮游植物生态结构及陆源输入的变化

Applications of Lipid Biomarkers for Reconstructing Changes of Phytoplankton Ecological Structure and Terrestrial Input in Core DH5-1 from the Shelf of the East China Sea During the Last 150 Years

类脂生物标志物法已被广泛应用于古海洋环境研究,但是在东海利用类脂生物标志物法重建浮游植物生产力、群落结构以及陆源输入的研究还很缺乏。本文选取东海陆架区的DH5-1岩芯进行类脂生物标志物分析,利用各种类脂生物标志物的沉积通量及相对比例重建了东海陆架区近150a来浮游植物生产力和群落结构以及陆源输入的变化。结果表明:(1)DH5-1站位的浮游植物生产力在过去80年呈上升趋势,群落结构在过去近百年有甲藻比例升高,硅藻比例降低的趋势,而颗石藻比例在低值范围波动;(2)用于指示生活污水污染的两种指标(粪醇含量,粪醇/(粪醇+二氢胆固醇)比值)的值都很低,表明近150a来此站位基本未受人类生活污水污染;(3)陆源高等植物输入在1970年前是增加的,1970年后输入减少,陆源有机质指标TMBR指示近150a来陆源输入相对海源是减少的。DH5-1站位生产力的提高可能与长江冲淡水营养盐的增加和东亚冬季风的增强有关,群落结构的改变可能与近年来冲淡水的Si/N降低有关,研究区域40年来陆源有机质相对比例的减少主要与人类建坝活动增强有关。

Lipid biomarkers have been widely used to reconstruct marine paleoenvironment changes. However, there are few biomarker records of phytoplankton productivity, community structure and ter- restrial input from the East China Sea. In this study, mass accumulation rate of biomarkers and their rati- os in core DHS-1 from the shelf of the East China Sea are applied for the reconstruction of the changes of phytoplankton productivity, community structure and terrestrial input during the last 150 years. The re- sults show- （1,） phytoplankton productivity increased over the last 80 years in DH5-1 and community structure changed over the last 100 years with increased contribution of dinoflagellates, decreased contri- bution of diatoms and limited contribution of coccolithpores. （2） low content of coprostanol and low value of coprostanol/（coprostanolq-cholestanol） ratio indicate that the sfudy area was not contaminated by sewage over the last 150 years. （3） terrestrial plant input increased before 1970s and then reduced and the TMBR index shows reduced terrestrial organic matter （TOM） contribution relative to marine organic mat ter （MOM） contribution. It is suggested that increased nutrient concentration of Changjiang Diluted Wa- ter （CDW） and strengthened East Asia Winter Monsoon caused higher productivity. The changes of com- munity structure were related to the decreased ratio of Si/N in CDW. The decreased ratio of TOM to MOM in recent 40 years was related to strengthened human activities such as construction of numerous reservoirs and dams.