摘要
通过对日本大沼湖沉积物样品总有机碳含量(TOC)及其稳定同位素、总氮含量(TN)和C/N值的测定,结合沉积岩芯火山灰和^(14)C年代,分析了大沼湖沉积物中有机质的来源,探讨了沉积物有机碳同位素的主要影响因素。结果表明:大沼湖沉积物中有机质主要来源于自生藻类,受陆源输入的影响较小;沉积物δ^(13)C值指示了夏季温度的变化。过去400年来,大沼湖地区存在1660~1730年和1780~1860年两个明显的冷期,与邻近地区冰芯、树轮和湖泊沉积物记录的冷期基本一致,分别对应于Maunder和Dalton太阳黑子极小期。
Lacustrine sediments have high-resolution regional environmental information on lake and its surrounding catchments.Therefore they are of great use for reconstructing past climate fluctuations,understanding lakecatchment processes.Lake Onuma,located in Hokkaido,is a dammed lake formed by volcanic eruption of Mt.Komagatake in 1640,enables its deposits record the climatic and environmental change sensitively.A 392cm long sediment core （ON12C） was retrieved from the northeastern basin of Lake Onuma in 2012 at a water depth of 11.7m （42°00′9.3″N,140°41′31.7″E） using a piston core sampler.The sediment core was sliced at 2.5cm intervals.The data of total organic carbon （TOC） content and its stable isotope （δ13C）,total nitrogen content and the total organic carbon and nitrogen （C/N） ratio of sediments were measured to reconstruct the environmental change of Lake Onuma,Japan.The chronological model is based on the volcanic tephra ages and the AMS14C age of plant remnants.In the Late Holocene,four major plinian eruptions have occurred in Mt.Komagatake since 1640 and been recorded in the stratigraphy,namely Ko-d in 1640A.D.,Ko-c2 in 1694A.D.,Ko-c1 in 1856 A.D.and Ko-a in 1929A.D.,respectively.Combining with the data of AMS 14C,the Ko-d,Ko-c1,and Ko-a were observed in the core sediments.Therefore,we will discuss the environmental change in Lake Onuma from 1640A.D.based on the 120 samples in the upper 301cm sediments,the average resolution is about 1.0～6.5 years.The origin of organic matter was established using C/N ratio and δ13C.Regression of TOC verses TN in samples from the core ON12C showed a strong linear relationship,with a negative intercept near zero.This shows that nitrogen is present in predominantly organic form and that inorganic nitrogen is negligible.This analytical approach yields C/N ratios that faithfully represent organic matter origins.δ13C of atmospheric CO2 has been declining in the past 200 years as an effect of the accelerating release of CO2 with low 13C content by
出处
《第四纪研究》
CAS
CSCD
北大核心
2014年第6期1306-1313,共8页
Quaternary Sciences
基金
中日韩国际合作项目(批准号:2011DFA21240)
中国科学院/国际外专局创新团队国际合作伙伴计划项目(批准号:KZZD-EW-TZ-08)共同资助
关键词
碳氮比值
有机碳同位素
沉积物
古气候环境
日本大沼湖
C/N ratio
stable carbon isotope
lacustrine sediments
paleoclimate
Lake Onuma of Japan
