Nutrient Salts (N,P) and Coliform Group in Minor Rivers from Flourishing Area of Tea Production

The purpose of this study was to estimate water pollution in minor rivers of a densely inhabited district (DID). The watershed of the rivers studied is a flourishing area for tea production in Kakegawa, Shizuoka, Japan. The quality of river water was observed from Apr. 2001 to Feb. 2007. The results are as follows. The pH values of the rivers ranged from 7.1 to 9.8, because phytoplankton performs photosynthesis. Seasonal changes in BOD and Org-N concentration were particularly pronounced in winter and low in summer, with periodical changes. The net effluent loadings by the basic unit method for T-N and T-P were 605.6 t · y-1, and 65.70 t · y-1, respectively. It is estimated that the majority of the T-N and T-P loads came from domestic wastewater loads in DID.