title: Contributions of humic substances to the dissolved organic carbon pool in wetlands from different climates.
abstract: Wetlands are an important source of DOM. However, the quantity and quality of wetlands' DOM from various climatic regions have not been studied comprehensively. The relationship between the concentrations of DOM (DOC), humic substances (HS) and non-humic substances (NHS) in wetland associated sloughs, streams and rivers, in cool temperate (Hokkaido, Japan), sub-tropical (Florida, USA), and tropical (Sarawak, Malaysia) regions was investigated. The DOC ranged from 1.0 to 15.6 mg CL(-1) in Hokkaido, 6.0-24.4 mg CL(-1) in Florida, and 18.9-75.3 mg CL(-1) in Sarawak, respectively. The relationship between DOC and HS concentrations for the whole sample set was regressed to a primary function with y-intercept of zero (P<0.005) and a slope value of 0.841. A similar correlation was observed between DOC and NHS concentrations, with a smaller slope value of 0.159. However, the correlation coefficient of the latter was much larger when the data was regressed to a logarithmic curve. These observations suggest the presence of a general tendency that the increased DOC in the river waters was mainly due to the increased supply of HS from wetland soils, whereas the rate of the increase in the NHS supply has an upper limit which may be controlled by primary productivity.
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan. akiraw@agr.nagoya-u.ac.jp
authors.forename: Akira
authors.initials: A
authors.lastname: Watanabe
authors.forename: Kunio
authors.initials: K
authors.lastname: Moroi
authors.forename: Hiromu
authors.initials: H
authors.lastname: Sato
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Tsutsuki
authors.forename: Nagamitsu
authors.initials: N
authors.lastname: Maie
authors.forename: Lulie
authors.initials: L
authors.lastname: Melling
authors.forename: Rudolf
authors.initials: R
authors.lastname: Jaffé
mesh_terms: D002244:Carbon / Q000737:chemistry*; D002980:Climate; D006812:Humic Substances; D012995:Solubility; D053833:Wetlands
chemical_list: D006812:Humic Substances; D002244:Carbon