CHANGES OF SUBSTANCES DERIVED FROM DOMESTIC SEWAGE IN YAMATOGAWA RIVER BASIN

Abstract

Seasonal Concentrations of BOD, NH₄⁺-N and interfacial active agent derived from domestic sewage were high in winter and low in summer. The concentrations decreased with an increase in water temperature. Generally, river water contains organic compounds and Cl^- derived from domestic sewage and Cl^- was quite stable in rivers. As the ratios of BOD/Cl^- and NH₄⁺-N/Cl^- decreased down the stream and changed seasonally, organic compounds were thought to be decomposed during flow. NO₃^--N/Cl^- which organic compounds were finally decomposed into, also decreased down the stream and were high in winter and low in summer. NO₃^--N was thought to be used for photosynthesis because pH, DO values and chlorophyll concentration of the Yamato river increased with temperature and decrease of NO₃^--N concentration.