摘要
在气候变化和人类活动日益增强的背景下,河口近海碳源汇途径的变化对区域乃至全球碳循环有着深刻的影响。本研究对南海北部河口-近岸-陆架海区3根沉积物柱状样顶部沉积记录约2000年的样品进行了有机碳(TOC)和总氮(TN)含量与稳定同位素组成等地球化学指标的分析。结果显示,南海北部沉积物TOC含量在过去2000年表现出稳步增加的趋势。根据稳定碳同位素(δ^(13)C)和TOC/TN比值构建的蒙特卡洛模拟估算,发现不同海区沉积有机碳的来源存在差异,其中陆源有机碳在近岸区贡献最高,河口区次之,南海北部陆坡贡献最小。在时间尺度上,陆坡区TOC来源在过去2000年维持稳定,而河口近岸区中海源有机碳比例不断增加,特别是河口区海源有机碳在过去1000年快速增加,同时与TN的变化存在显著的正相关关系,反映了人类活动持续输入的陆源营养盐促进了海洋初级生产力的升高;另一方面,河口区陆源有机碳的减少主要归因于华南地区减弱的东亚夏季风和人类活动与沿海地区大规模的围垦活动等。不同于河口近岸海区,南海北部陆坡沉积物有机碳埋藏的增加主要与东亚冬季风增强对营养盐供应和初级生产力的调控密切关联。整体而言,人类活动和气候变化共同控制着近2000年南海北部沉积物有机碳埋藏的演变过程。
In the context of global climate change and human activities,the variation of organic carbon sources and sinks in estuarine and coastal oceans has an enormous effect on the regional and global carbon cycle.The paleoceanographic and paleoclimate information contained in sediments from the northern South China Sea(NSCS)have been investigated intensively over the last three decades.However,high-resolution records of sedimentary organic carbon(OC)in coastal estuaries and shelf are lack during the last 2000 years,which has seen a progressive intensification of human activities.In this study,we analyzed the content and isotopic composition of organic carbon and total nitrogen for the top sections of three well-dated,high-resolution sediment cores recovered from the northern South China Sea,including core WS(21°59.62'N,113°43.22'E;water depth 20.5m;1923cm in length and spans the past 5100 years for the upper 649cm)offshore from the Pearl River Estuary,core YJ(21°31.44'N,112°8.08'E;water depth 20.5m;839cm in length and spans the past 7500 years for the upper 610cm)from the coastal area of western Guangdong,and core NH07(19°59.46'N,115°57.48'E;water depth 1240m;300cm in length and spans the past 16100 years)from the northern South China Sea,in order to study the evolution of OC burial,and to explore the possible sources and causes of OC variations over the past 2millennial.The results showed that the total sedimentary OC in coastal oceans of the NSCS have significantly increased during the last 2000 years.In addition,a comprehensive four-end-member Monte Carlo simulation based onδ^(13)C and C/N of bulk OC was used to calculate the relative contributions of OC derived from vascular C3 plant,terrestrial soil,river and marine phytoplankton.Results showed that the contribution of marine phytoplankton-derived OC increased significantly over the past 1000 years,which was corroborated by variation in TN.This interval also saw a weakened summer monsoon but an increase in the population of Guangdong Province.Therefore,it is inferred that an increase in terrestrial N and subsequent marine OC inputs were stimulated by a growing human population and the expansion of agricultural and mining practices.Different from the estuarine and coastal marine environments,an increased sedimentary OC burial in the slope of the northern South China Sea over the past 2000 years may be related to the enhanced nutrient supply and primary production,which is in turn controlled by the East Asian Winter Monsoon via regulation of the upper water structure and aerosol deposition.Generally,both the enhanced human activity and natural climate change are responsible for the variations in sedimentary OC burial in the northern South China Sea during the past 2000 years.
作者
石雪松
叶丰
王利伟
黄超
韦刚健
曾提
SHI Xuesong;YE Feng;WANG Liwei;HUANG Chao;WEI Gangjian;ZENG Ti(State Key Laboratory of Isotope Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong;University of Chinese Academy of Sciences,Beijing 100049;College of Ocean and Meteorology,Guangdong Ocean University,Zhanjiang 524088,Guangdong)
出处
《第四纪研究》
CAS
CSCD
北大核心
2023年第2期439-447,共9页
Quaternary Sciences
基金
南方海洋科学与工程广东省实验室(广州)人才团队引进重大专项项目(批准号:GML2019ZD0308)
国家自然科学基金项目(批准号:41991325、42073074和42001078)
中国科学院青年创新促进会项目(批准号:2019346)
广州市科技计划项目(批准号:201904010431)共同资助。
关键词
有机碳埋藏
沉积记录
南海北部
近2000年
OC burial
sediment records
northern South China Sea
the last 2000 years
