Six-year monitoring study of Cs discharge from headwater catchments after the Fukushima Dai-ichi Nuclear Power Plant accident.

Since headwater catchments are the source areas of Cs for downstream river systems, Cs discharge from headwater areas needs to be evaluated. Dissolved form (Dissolved), coarse organic matter (Org), and suspended sediments (SS) were sampled and Cs concentrations were measured from June 2011 to November 2016 in four headwater catchments in Yamakiya District, located 35 km northwest of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP). The data up to September 2013 (2.