JpGU-AGU Joint Meeting 2017

講演情報

[EE]Eveningポスター発表

セッション記号 A (大気水圏科学) » A-HW 水文・陸水・地下水学・水環境

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

2017年5月20日(土) 17:15 〜 18:30 ポスター会場 (国際展示場 7ホール)

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

*金 广哲1齋藤 光代2小野寺 真一1石田 卓也3奥田 昇3易 容4伴 修平4友澤 裕介1 (1.広島大学 総合科学研究科、2.岡山大学 環境生命科学研究科 、3.総合地球環境学研究所、4.公立大学法人滋賀県立大学)

キーワード: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.