title: Vertical distribution of sediment phosphorus in Lake Hachirogata related to the effect of land reclamation on phosphorus accumulation.
abstract: The focus of this work is the change in sediment properties and chemical characteristics that occur after land reclamation projects. The results indicate a higher sedimentation rate in Lake Hachirogata after reclamation, with the rate increasing with proximity to the agricultural zone. In the west-side water samples, higher levels of dissolved total nitrogen and dissolved total phosphorus (DTP) were found in both surface and bottom waters. The increase in P (39-80%) was generally greater than that for N (12-16%), regarding the nutrient supply from reclaimed farmland in the western part of the lake. In the eastern part of the lake, the pore-water Cl-profile showed a decreasing vertical gradient in the sediment core. This indicates desalination of the lake water after construction of a sluice gate in 1961. In the western sediment-core sample, a uniform Cl-profile indicates the mixing of lake water and pore water after reclamation. Considering the sedimentation of P in the last 100 years, there is a trend of increasing accumulation of P and P-activities after the reclamation project. This appears to be an impact from change in the lake environment as a result of increased agricultural nutrients, desalination, and residence. A large amount of mobile phosphorus (42-72% of TP in the western core sample) trapped in sediment increases the risk of phosphorus release and intensification of algal blooms. High sediment phosphorus and phosphorus mobility should be considered a source of pollution in the coastal environment.
authors.affiliation: a Graduate School of Integrated Arts and Sciences, Hiroshima University , C611, 1-7-1, Kagamiyama, Higashi-Hiroshima , Japan.
authors.forename: G
authors.initials: G
authors.lastname: Jin
authors.affiliation: a Graduate School of Integrated Arts and Sciences, Hiroshima University , C611, 1-7-1, Kagamiyama, Higashi-Hiroshima , Japan.
authors.forename: S
authors.initials: S
authors.lastname: Onodera
authors.affiliation: b Graduate School of Environmental and life Science, Okayama University , 3-1-1 Tsushima-naka, Kita-ku, Okayama-shi , Japan.
authors.forename: M
authors.initials: M
authors.lastname: Saito
authors.affiliation: a Graduate School of Integrated Arts and Sciences, Hiroshima University , C611, 1-7-1, Kagamiyama, Higashi-Hiroshima , Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Maruyama
authors.affiliation: c Department of Biological Environment , Akita Prefectural University , 241-438 Kaidobata Nishi, Nakano, Shimoshinjo , Akita-shi , Japan.
authors.forename: A
authors.initials: A
authors.lastname: Hayakawa
authors.affiliation: a Graduate School of Integrated Arts and Sciences, Hiroshima University , C611, 1-7-1, Kagamiyama, Higashi-Hiroshima , Japan.
authors.forename: T
authors.initials: T
authors.lastname: Sato
authors.affiliation: d Atmosphere and Ocean Research Institute, the University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa , Chiba Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ota
authors.affiliation: a Graduate School of Integrated Arts and Sciences, Hiroshima University , C611, 1-7-1, Kagamiyama, Higashi-Hiroshima , Japan.
authors.forename: D
authors.initials: D
authors.lastname: Aritomi
keywords: agriculture; coastal lake; land reclamation; phosphorus fractionation; sediment