Japan Geoscience Union Meeting 2015

Presentation information

International Session (Oral)

Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS03] Exploring the role of soil in earth science: ecological/biogeochemical linkage and beyond

Wed. May 27, 2015 11:00 AM - 12:45 PM 104 (1F)

Convener:*Rota Wagai(National Institute for Agro-Environmental Sciences, Carbon & Nutrient Cycling Division), Kosaki Takashi(Tokyo Metropolitan University), Chair:Rota Wagai(National Institute for Agro-Environmental Sciences, Carbon & Nutrient Cycling Division)

12:27 PM - 12:30 PM

[MIS03-P07] Effects of microorganisms and minerals on size distribution of organic matter adsorbed to soil

3-min talk in an oral session

*Satoru HOBARA1, Yuki HASEGAWA2, Kyouhei FUJITA1, Takayuki SATOU3, Akio IMAI3, Hiroshi OGAWA4, Akihide ITO5, Noriharu AE1 (1.Rakuno Gakuen University, 2.Hokkaido University, 3.National Institute for Environmental Sciences, 4.University of Tokyo, 5.Azabu University)

Keywords:Soil microorganisms, Soil minerals, Soil carbon, Organic matter adsorption, Molecular weight distribution

Sorption of organic matter to soil is a key mechanism for carbon sequestration in terrestrial ecosystems. However, little is understood on how adsorptive organic matter is formed during decomposition process. In this presentation, we show changes in size distribution of adsorptive organic matter in soil during decomposition, and influences of microorganisms and minerals on the changes. We conducted an incubation experiment, in which leaves of three species were separately incubated in low-carbon-content soil, and size distribution of extractable organic matter from the soil was analyzed using HPLC attaching a size-exclusion column (HPSEC). Molecular weight of extratable organic matter distributed mainly in two ranges, about 100kDa-200kDa and about 0.5kDa-20kDa (based on proteins molecular weight) for all plant species. The width of these ranges changed to narrower with decomposition process. This change in molecular weight distribution (MWD) was observed when cycloheximide was added to soil, but not observed when chloramphenicol was added, suggesting bacterial influence on the MWD change during decomposition. In order to clarify influence of minerals on the typical two ranges, metal concentration was measured using ICP/MS for fractionated, eluted solution from HPSEC. The MWD of iron was closely related to that of organic carbon. These results suggest an importance of bacteria and iron for size distribution of adsorptive organic matter in decaying litter.