Nutrient dynamics in a large river estimated by in situ spiralling metric measurements

2015 Fiscal Year Final Research Report

• Project/Area Number: 25650141
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Ecology/Environment
• Research Institution: University of Yamanashi
• Principal Investigator: IWATA Tomoya 山梨大学, 総合研究部, 准教授 (50362075)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: スパイラルメトリクス / 大河川 / 栄養塩 / ドリフト法 / 硝化

Outline of Final Research Achievements

To estimate nutrient spiralling metrics in a large river, we monitored the longitudinal profiles of inorganic nutrient concentrations in the mainstem of Fuji River by tracking a specific water parcel directly along the river course. The in situ tracking of a water parcel revealed that the areal uptake rates of NH4 and PO4 were much higher than those reported in previous studies. Moreover, negative fluxes of both NO2 and NO3 from riverbeds were observed. However, nutrient removal efficiency, expressed as uptake velocity (vf) and uptake length (Sw), of NH4 and PO4 did not differ from or was even low relative to previous findings, as a result of the high nutrient concentration and high water velocity in the Fuji River. The results suggest that anthropogenic nutrients are propagated through fast-flowing river corridors in a short period of time and eventually highly influential on distant downstream ecosystems.

Free Research Field

水域生態学