Precipitation and streamwater chemistry in the Katsura Fudo-yatsu experimental watershed in the Kanto region, 2001 - 2014

Abstract

Precipitation and stream water chemistry were monitored between 2001 and 2014 in the Katsura Fudo-yatsu experimental watershed in Ibaraki prefecture, Japan. In the monitoring period, the annual fluxes of non sea-salt SO₄^2- and inorganic N ions by precipitation tended to decrease. Annual mean concentration of stream water SO₄^2- was almost constant in the period 2001-2011, increased after forest thinning operations conducted in 2012 and 2013. Annual mean concentration of stream water NO₃- t ended to decrease before the thinning operations, and turned to increase after the operations. Similar increasing pattern after the thinning operations was observed in the concentrations of Ca²⁺ and K⁺. Stream water Si concentration exhibited very small fluctuation and tended to increase gently.