摘要
【目的】红树林是重要的滨海“蓝碳”生态系统,具有强大的碳汇功能,对全球碳循环有深远的影响。【方法】以沿浦湾红树林为研究区域,采集柱状沉积物,通过^(210)Pb定年技术建立高分辨年代地层框架,分析沉积物沉积质量埋藏速率(SAR)、有机碳埋藏通量(OCAR)及有机碳潜在来源。【结果】红树林的沉积速率约为2.2 cm/a。沉积物以粉砂和黏土为主,粒径随深度变化基本稳定,且过剩^(210)Pb活度与深度之间具有较好的相关性,表明沉积环境较为稳定。沉积物SAR值介于52.03~233.61 g/(cm^(2)·a),OCAR值介于112.78~473.97 g/(m^(2)·a),较高的SAR有利于有机碳的沉积与埋藏。【结论】研究区沉积物有机碳为海陆混合来源,其中红树凋落物平均贡献率为59.44%,悬浮有机颗粒(POM)为25.91%。故红树林面积和POM的输送量是影响沉积物有机碳埋藏的重要因素。同时,极端天气、自然灾害、水利工程等因素进一步促进有机碳来源变化的复杂性。
[Objective]Mangroves are an important coastal blue carbon ecosystem,with a strong carbon sink func⁃tion that has a profound impact on the global carbon cycle.In recent years,the sources and burial characteristics of organic carbon in mangrove wetland sediments have become a hot topic at home and abroad.However,there are few studies on the sources and biogeochemical cycles of organic carbon in mangrove wetland sediments at high latitudes.[Methods]A high-resolution ^(210)Pb chronostratigraphic framework was established in the Yanpu Bay mangrove research area using the 1.5 m deep column sediment collected from the mangrove as a carrier.The sediment accumulation rate(SAR),organic carbon accumulation rate(OCAR),potential sources of organic carbon,and their contribu⁃tion rates were analyzed according to the characteristics of the total organic carbon content(TOC),carbon to nitrogen ratio(C/N),median particle size(D50)and stable isotopes of carbon and nitrogen(δ^(13)C,δ^(15)N)[.Results]The sedi⁃mentation rate of mangrove sediments along Yanpu Bay is approximately 2.2cm/a,and a continuous sedimentary se⁃quence of almost 70 years has been obtained.The particle size components are mainly silt and clay components.The proportion of different components of particle size and D50 remained unchanged with depth,and the activity of excess ^(210)Pb was closely related to depth,indicating that the sedimentary environment was relatively stable.The average con⁃tent of TOC is 1.63%,while the average content of TN is 0.10%.There was a significant positive correlation between TOC and TN(R^(2)=0.23809),and a significant negative correlation between TOC andδ^(13)C(R^(2)=0.47269),indicating that the sources of organic carbon and nitrogen in sediments were consistent,and carbon sources with lowerδ^(13)C values were the main contributors to organic carbon in sediments.According to the vertical trend of TOC content,SAR and OCAR,the sedimentary record of organic carbon can be divided into three stages:the first stage is from 1955 to 1982,the second stage is from 1982 to 2014,and the third stage is from 2014 to 2021.The SAR values ranged from 52.03 to 233.61 g/(cm^(2)·a),with an average value of 177.68 g/(cm^(2)·a),OCAR values ranged from 112.78 to 473.97 g/(m^(2)·a),with an average value of 286.65 g/(m^(2)·a).TOC and OCAR showed no significant correla⁃tion(R^(2)=0.09578),while SAR and OCAR showed a significant positive correlation(R^(2)=0.45766).SAR of mangrove sediments may be an important factor that affects the burial of organic carbon in sediments.According to the dis⁃tribution range ofδ^(13)C,δ^(15)N and C/N values of mangrove columnar sediments,it is preliminarily concluded that the deposition of terrigenous organic matter is mainly contributed by terrigenous plants,C3 plants and organic matter in lost soil.Marine organic matter deposition is mainly caused by aquatic plants,marine phytoplankton and suspended organic particles brought by seawater perfusion.Among them,the contribution rate of mangrove litter was the highest(59.44%),followed by the average contribution rate of POM(25.91%),and the contribution rate of SOM and phyto⁃plankton was relatively small.The contribution rate of POM is the largest,which is mainly affected by downstream seawater injection and the upstream runoff.The water conservancy facilities are the main limiting factor of the contri⁃bution rate of POM.Mangrove area and POM delivery are important factors that affect the burial of organic carbon burial in sediments[.Conclusions]Mangrove sediment organic carbon in Yanpu Bay is a mixed source of marine and land,and the sources of organic carbon and nitrogen in the sediment are consistent.Mangrove plant litter is the main contributor to organic carbon in sediments.Extreme weather,natural disasters,and water conservancy projects increase the complexity of sediment organic carbon sources.The sediment mass burial rate is the main factor affecting the organic carbon burial flux of mangrove sediments along Yanpu Bay.The sediment mass burial rate is mainly affected by extreme weather such as typhoon,and the use of upstream sluices and estuarine sluices also has a signifi⁃cant influence on it.Through reconstruction of the organic carbon burial records of mangrove sediments in Yanpu Bay,it is found that the burial of organic carbon in mangrove sediments is greatly affected by extreme weather and water conservancy projects,forming a phased deposition process.
作者
李滨
水柏年
于洋
吕聪聪
李雪丽
上官明珠
魏珍
胡成业
LI Bin;SHUI BoNian;YU Yang;LÜCongCong;LI XueLi;SHANGGUAN MingZhu;WEI Zhen;HU ChengYe(School of Fishery,Zhejiang Ocean University,Zhoushan,Zhejiang 316022,China)
出处
《沉积学报》
北大核心
2025年第6期2004-2014,共11页
Acta Sedimentologica Sinica
基金
国家自然科学基金项目(42306188)
浙江省自然科学基金项目(LQ21C030006)
浙江省属高校基本科研业务费(2021J003)
浙江省大学生科技创新活动计划(2022R411A004)
国家级大学生创新创业训练计划(202310340058)。
关键词
有机碳
稳定同位素
沉积记录
特征与来源
沿浦湾
organic carbon
stable isotopes
sedimentary records
characteristics and sources
Yanpu Bay
