Vertical distribution of sediment phosphorus in Lake Hachirogata related to the effect of land reclamation on phosphorus accumulation. Issue 4 (16th February 2016)

• Record Type: Journal Article
• Authors: Jin, G.; Onodera, S.; Saito, M.; Maruyama, Y.; Hayakawa, A.; Sato, T.; Ota, Y.; Aritomi, D.
• Is Part Of: Environmental technology. Volume 37:Issue 4(2016)
• Page Start: 486
• Page End: 494
• Publication Date: 2016-02-16
• Subjects: sediment -- phosphorus fractionation -- land reclamation -- agriculture -- coastal lake; Environmental engineering -- Periodicals; Environmental protection -- Periodicals; 628.05
• DOI: 10.1080/09593330.2015.1117043
• Languages: English
• ISSNs: 0959-3330

Abstract

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.