JpGU-AGU Joint Meeting 2017

Presentation information

[EE] Poster

A (Atmospheric and Hydrospheric Sciences) » A-HW Hydrology & Water Environment

[A-HW32] [EE] Biodiversity, nutrients and other materials in ecosystems from headwaters to coasts

Sat. May 20, 2017 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL7)

[AHW32-P16] Characteristic of oxygen isotope ratio of phosphate in endmember of Lake Biwa

*Guangzhe Jin1, Mitsuyo Saito2, Shin-ichi Onodera1, Takuya Ishida3, Noboru Okuda3, Rong Yi4, Syuhei Ban4, Yusuke Tomozawa1 (1.Graduate School of Integrated Arts and Science,Hiroshima University, 2.Graduate school of environmental and life science.Okayama University, 3.Research Institute for Humanity and Nature, 4.University of Shiga Prefecture)

Keywords:nutrient, phosphate oxygen isotope, sediment

Lake eutrophication control and nutrient management are important to build up a sustainable safety water resources. Despite the nutrient discharge through rivers, Nutrient transport through sediment and lacustrine groundwater discharge could be an important internal nutrient resource. This research aims to clarify the dynamics of nutrient cycle in lake bed sediment, groundwater and overlying water using nutrient and phosphate oxygen isotope end-member analysis.
. We collected water and sediment samples from Lake Biwa during several field work in 2016. Sediment samples from 5m 10m and 20m depth were collected in Lake Biwa along the transactions from the east bank to central lake. Surface, bottom water samples as well as river water and groundwater were also collected simultaneously. Major nutrient, oxygen isotope, and phosphate oxygen isotope were also analyzed.
Results show the high P concentration in sediment pore water, ranging from 50-230 times of lake water. Indicates sediment recycled phosphorus would be an important resource contributing to lake nutrient cycle as Lake Biwa is considered as phosphorus limitation environment. High radon concentration in pore water at 5m and 20m proved the existence of deep LGD and shallow LGD. Oxygen isotope ratio of phosphate indicates shallow LGD may refer to recharged river water and groundwater near the eastern bank, while the much lower ratio in deep pore water may refer to other groundwater resources.