Nitrogen balance and water quality fluctuations during a flood in a fen located at lakefront of Kasumigaura

Abstract

Myoginohana fen is the largest reed fen located at lakefront of Kasumigaura. We revealed that water exchanges between the river and the fen play an important role in nutrient balance in the fen. Water levels and meteorological observations were measured to clarify water budget in the fen, and we observed nitrogen concentrations of inflow and outflow in a flood event. River water with high inorganic nitrogen flowed to the inside during water level rising, and then turning in drawdown, surface water containing organic nitrogen and no NO₃ flowed out to the river. 49% of all the nitrogen inflows to the fen were caused by the floods, and the quantity of nitrogen removal as carrying out of the plant bodies and atmosphere release was estimated at 19.8 kg/ha.