Japan Geoscience Union Meeting 2019

Presentation information

[E] Poster

B (Biogeosciences ) » B-CG Complex & General

[B-CG06] Earth and Planetary Science Frontiers for Life and Global Environment

Tue. May 28, 2019 3:30 PM - 5:00 PM Poster Hall (International Exhibition Hall8, Makuhari Messe)

convener:Yoshinori Takano(Japan Agency for Marine-Earth Science and Technology (JAMSTEC)), Yohey Suzuki(Graduate School of Science, The University of Tokyo), Shingo Kato(RIKEN), Keisuke Fukushi(Institute of Nature & Environmental Technology, Kanazawa University)

[BCG06-P01] Dynamisms and characteristics of dissolved organic matter (DOM) in deep aquifer: A scope for deep biosphere

*Atsushi Urai1,2, Yoshinori Takano2, Naohiko Ohkouchi2 (1.Department of Science and Technology, Graduate School of Medicine, Science and Technology, Shinshu University, 2.Department of Biogeochemistry, Japan Agency for Marine-Earth Science and Technology)

Keywords:HMW-DOM, sterol, carbon and hydrogen isotopic compositions, deep aquifer, methanogenesis

Dissolved organic matter (DOM) is generally derived from multiple sources and affected by complicated transformation and degradation reactions. In a general geochemical description of marine environments, high-molecular-weight DOM (HMW-DOM; >1 kDa) particularly represents a unique organic carbon pool, which is accompanied by considerable difference in the molecular and stable isotopic compositions from other organic components such as particulate organic matter (POM) and low-molecular-weight DOM (LMW-DOM; <1 kDa) (e.g., Benner et al., 1997).

To date, formation of DOM fraction and potential microbial interaction in deep aquifer have been particularly poorly understood on the context of prokaryotic ecology. We investigated the molecular composition of DOM fraction including LMW and HMW by an improved method (Urai et al., 2018). The filtered samples are tentatively defined by conventional size scales; macromolecular scale (100 mm >> 40 mm), POM (40 mm >> 0.6 mm), HMW-DOM(0.6 mm>>1kDa), and total-DOM (<0.6 mm). We also have a validation to distinguish the molecular signature between phototrophic primary producers (i.e., fossil molecules) and presently living benthic prokaryotes (i.e., modern molecules; cf. biological methanogenesis, Kaneko et al., 2014). We report a preliminary result of the feasibility study and discuss a perspective from the view of deep biosphere.

Benner et al. Abundance, size distribution, and stable carbon and nitrogen isotopic compositions of marine organic matter isolated by tangential-flow ultrafiltration. Marine Chemistry 57, 243-263 (1997).

Kaneko et al. Quantitative analysis of coenzyme F430 in environmental samples: a new diagnostic tool for methanogenesis and anaerobic methane oxidation. Analytical Chemistry 86, 3633-3638 (2014).

Urai et al. Algal-derived 24-ethylcholesta-5, 22-dien-3β-ol (stigmasterol) is frequently found in high-molecular-weight dissolved organic matter (HMW-DOM) during summer in freshwater and brackish lakes. Geochemical Journal 52, e15-e20 (2018).