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2012 Fiscal Year Final Research Report

Carbon sink potential of eutrophic lake sediments: a reconstruction of the potntial in lakes Nakaumi and Shinji during the last about four hundred years

Research Project

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Project/Area Number 22540470
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Geology
Research InstitutionShimane University

Principal Investigator

SAMPEI Yoshikazu  島根大学, 総合理工学研究科, 教授 (00226086)

Project Period (FY) 2010 – 2012
Keywords汽水域 / 有機物濃度 / 有機炭素埋積速度 / 二酸化炭素 / 硫化水素 / カーボンシンク / 中海 / 宍道湖
Research Abstract

Carbon sink potential of eutrophic lake sediments from lakes Nakaumi and Shinji was studied for recent and several hundred years environments using surface sediments and sediment cores.TOC (total organic carbon) contents of southern and central L. Nakaumi showed high sapropelic about 3.6~4.0% in the 1cm surface sediments. These values are constant from AD1997. TOC contents of all samples from L. Shinji showed also sapropelic and high about 3.5~4.3% except for eastern part. These TOC values in L. Shinji are not changed during the last 5 years. According to the result of C/N ratio (7-9) and py-GC-MS, origin of organic matter in both lakes is supposed to be predominant phyto-plankton. Sediment cores showed low TOC contents about 1% between AD1800 and 1900 in both L. Nakaumi and Shinji and TOC contents drastically increased from 1% to 4% after AD1900. Analysis of AD2003 data by our preliminary research indicates that TOC contents over 3.5% of surface sediments have a good positive correlat … More ion with H2S (ppm), showing an equation: H2S (ppm) = 13.9 * TOC (%) - 52.1 (TOC>3.5%). Atmospheric CO2 concentration on the northeastern Nakaumi was low about 360 ppm in average (April to May, 2013), which could depend on spring blooming of phyto-plankton. Impressive difference of the CO2 concentration between daytime and nighttime was up to 80 ppm. Average OCARs in the surface sediments of L. Nakaumi and Shinji are 7.0 mgC/cm2/y and 4.0 mgC/cm2/y,respectively based on the sedimentation rate reported by Kanai et al., (1998, 2002). As a result, L. Nakaumi and Shinji have a potential carbon sink of about 6,000 tonC/y and 3,200 tonC/y, respectively. Low OCARs of the cored sediments with low TOC about 1% in L. Nakaumi during 50-25 cm (1770-1890) and TOC about 0.7% in L. Shinji during 30-20cm (1830-1890), i.e. Little Ice Age, suggested 2,000 tonC/y and 1,300 tonC/y, respectively. These low values during cool climate are about one - third of the present potential. These brackish lakes are characterized as a quick response carbon sink for climate change. Less

  • Research Products

    (1 results)

All 2013

All Journal Article (1 results) (of which Peer Reviewed: 1 results)

  • [Journal Article] Hydrogen sulfide and organic carbon at the sediment-water interface in coastal brackish Lake Nakaumi2013

    • Author(s)
      Sakai, S., Nakaya, M., Sampei, Y., Dettman, D.L. and Takayasu, K
    • Journal Title

      SW Japan. Environmental Earth Sciences

      Volume: Vol.68 Pages: 1999-2006

    • DOI

      DOI:10.1007/s12665-012-1887-5

    • Peer Reviewed

URL: 

Published: 2014-08-29  

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