抄録
The Nogawa river, which is a tributary of the Tama river in Tokyo, runs through a residential district. Stormwater runoff of petroleum hydrocarbons, such as linear aliphatic hydrocarbons and polycyclic aromatic hydrocarbons, was estimated from the viewpoint of atmosphere-land hydrosphere, roughly and based on mass-balance.
It seemed that the hydrocarbons in the river water at normal water levels were originated from 70-97% of gray water and those at high water levels were from 92-99% of runoff water. In petroleum hydrocarbons which influented to the river basin by storm water, 100% of linear aliphatic hydrocarbons with carbon numbers from 11 to 21 and 64% of those with carbon numbers from 21 to 30 were seemed to be originated from automobiles emissions.
On the contrary, 75% of polycyclic aromatic hydrocarbons were seemed to be originated from atmosphere, such as fossil fuels under incomplete combustion.
At high water level, the runoff loads of petroleum hydrocarbons in the Nogawa river was estimated to be 7.5-8.2% of all runoff in the land of the basin.
