naa a22 4500 510737978 CHVBK 20180411083017.0 cr unu---uuuuu 180411e20130901xx s 000 0 eng 10.1007/s11284-013-1047-8 doi (NATIONALLICENCE)springer-10.1007/s11284-013-1047-8 Fluvial transport of carbon along the river-to-ocean continuum and its potential impacts on a brackish water food web in the Iwaki River watershed, northern Japan [Elektronische Daten] [Tomoya Iwata, Takao Suzuki, Hiroyuki Togashi, Naoto Koiwa, Hideaki Shibata, Jotaro Urabe] Riverine transport of dissolved inorganic carbon (DIC) from land to the ocean is an important carbon flux that influences the carbon budget at the watershed scale. However, the dynamics of DIC in an entire river network has remained unknown, especially in mountainous Japanese watersheds. We examined the effects of watershed land use and geology on the transports of inorganic carbon as well as weathered silica (Si) and calcium (Ca) in the Iwaki River system where agricultural and residential areas have developed in the middle and lower parts of the watershed. The concentration and stable carbon isotope ratios (δ13C) of DIC showed the longitudinal increase of 13C-depleted inorganic carbon along the river. As a result, most streams and rivers were supersaturated in dissolved CO2 that will eventually be emitted to the atmosphere. The possible origin of 13C-depleted carbon is CO2 derived from the decomposition of organic matter in agricultural and urban landscapes, as well as from in-stream respiration. In addition, agricultural and urban areas, respectively, exported the large amount of dissolved Si and Ca to the rivers, suggesting that CO2 increased by respiration accelerates the chemical weathering of silicate and carbonate materials in soils, river sediments, and/or urban infrastructure. Furthermore, riverine bicarbonate flux is likely to enter shell carbonates of Corbicula japonica, an aragonitic bivalve, in the downstream brackish lake (Lake Jusan). These results revealed that the flux of DIC from the human-dominated watersheds is a key to understanding the carbon dynamics and food-web structure along the land-to-river-to-ocean continuum. The Ecological Society of Japan, 2013 Brackish water food web nationallicence Chemical weathering nationallicence Dissolved inorganic carbon nationallicence Land use nationallicence Stable and radioactive carbon isotopes nationallicence Iwata Tomoya Faculty of Life and Environmental Sciences, University of Yamanashi, 400-8511, Kofu, Japan aut Suzuki Takao Graduate School of Life Science, Tohoku University, 980-8578, Sendai, Japan aut Togashi Hiroyuki Graduate School of Life Science, Tohoku University, 980-8578, Sendai, Japan aut Koiwa Naoto Faculty of Education, Hirosaki University, 036-8560, Hirosaki, Japan aut Shibata Hideaki Field Science Center for Northern Biosphere, Hokkaido University, 060-0809, Sapporo, Japan aut Urabe Jotaro Graduate School of Life Science, Tohoku University, 980-8578, Sendai, Japan aut Ecological Research Springer Japan 28/5(2013-09-01), 703-716 0912-3814 28:5<703 2013 28 11284 https://doi.org/10.1007/s11284-013-1047-8 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11284-013-1047-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Iwata Tomoya Faculty of Life and Environmental Sciences, University of Yamanashi, 400-8511, Kofu, Japan aut NATIONALLICENCE 700 1- Suzuki Takao Graduate School of Life Science, Tohoku University, 980-8578, Sendai, Japan aut NATIONALLICENCE 700 1- Togashi Hiroyuki Graduate School of Life Science, Tohoku University, 980-8578, Sendai, Japan aut NATIONALLICENCE 700 1- Koiwa Naoto Faculty of Education, Hirosaki University, 036-8560, Hirosaki, Japan aut NATIONALLICENCE 700 1- Shibata Hideaki Field Science Center for Northern Biosphere, Hokkaido University, 060-0809, Sapporo, Japan aut NATIONALLICENCE 700 1- Urabe Jotaro Graduate School of Life Science, Tohoku University, 980-8578, Sendai, Japan aut NATIONALLICENCE 773 0- Ecological Research Springer Japan 28/5(2013-09-01), 703-716 0912-3814 28:5<703 2013 28 11284 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer