摘要
巨型"树荫种"硅藻在成层化大洋中通过"秋季倾泻"勃发模式向深部大洋输出的有机碳通量等于甚至超过"春季勃发"硅藻,其在第四纪全球气候转型、大洋碳储库演变中的重要地位最近才予以重视.作为大洋碳循环系统的重要参数,生产力无疑成为探索这一作用的有效窗口.以东菲律宾海的Ethmodiscus rex硅藻席(LDM,laminated diatom mats)岩心WPD-03为材料,以opal、TOC、bio-Ba等生源组分数据为基础,运用前人建立的各种生产力经验公式,试图估算LGM(last glacial maximum)热带西太平洋LDM的古生产力状况.结果显示,LDM沉积期初级生产力、有机碳雨率和埋藏生产力估算合理,平均分别为248.42g·m-2·a-1、61.93g·m-2·a-1和5.27g·m-2·a-1.估计的初级生产力与代表高生产力的世界大洋各上涌海区可比,纠正了成层化大洋生产力低下的传统观点,支持巨型"树荫种"硅藻对大洋有机碳生产与输出的充分贡献.然而,估算的输出生产力明显不合理,表明利用基于真光层建立的生产力模型评估次表层水中的巨型"树荫种"硅藻时应格外谨慎,加强了区别对待"深部"生产力和"表层"生产力的重要性.LGM热带西太平洋LDM的高生产力状况与风尘硅输入的E.rex勃发条件以及还原的沉积环境相一致.
The organic carbon flux to deep ocean, dominated by the bloom of giant ＂shade flora＂ diatoms via ＂fall dump＂ in stratified ocean, could rival or even exceed that of ＂spring bloom＂ diatoms. The giant ＂shade flora＂ diatoms played a significant role in the global climate transition and ocean carbon reservoir change in the Quaternary, which could be exploited by the paleo- productivity, one of most important factors in the ocean carbon cycle systems. We tried to estimate the paleoproductivity of laminated Ethmodiscus rex diatom mats （LDM） from tropical West Pacific during the Last Glacial Maximum （LGM）, based on the data of opal, total organic carbon and biogenic barium from Core WPD-03 located in the eastern Philippine Sea. Primary productivity, organic carbon rain rates, burial productivity during the LDM deposition were estimated to average 248. 42 g · m-2 · a-1 , 61.93 g · m-2 · a-1 and 5.27 g · m-2 · a-1 , respectively, of which the primary productivity is comparable to those of some modern continent-margin upwelling zones. correcting low primary productivity with a largely stratified ocean and supporting substantial contribution of giant ＂shade flora＂ diatoms to the production and export of organic carbon in the world ocean. However, the unreasonable estimations for the export productivity by the empirical formulas in base of photic zone suggest that a caution must be taken to assess the ＂deep＂ productivity represented by giant ＂shade flora＂ diatoms, which should be distinguishable from classic ＂surface＂ productivity characterized by common diatoms. The high levels of productivity of LDM were consistent with the blooming conditions of dust silicon inputs and reducing depositional environments.
出处
《地球科学（中国地质大学学报）》
EI
CAS
CSCD
北大核心
2013年第1期25-32,共8页
Earth Science-Journal of China University of Geosciences
基金
中国科学院海洋地质与环境重点实验室开放基金资助项目(No.MGE2011KG03)
国家重点基础研究发展计划"973"项目(No.2007CB815903)
国家自然科学基金项目(Nos.41230959
41106042
40776031
41006032)
