| One of the significant sources of nutrients in the agricultural areas are diffuse sources. In case of eutrophication process, the important role play the ration of N and P. This relation is the most important in the lakes and reservoirs, however when reservoir is quite small and have only one inflow the N:P ratio in a river, can give some information on occurrence of eutrophication in reservoir. This kind of situation can be seen in a small lowland agricultural catchment in a central Poland. Small “Staw Górny” reservoir (capacity circa 250 000 qubic meter) has one inflow (Zagożdżonka river). Since two year, the investigations on N:P ratio has been carried on in a chosen points in the Zagożdżonka river. Based on total phosphorus and nitrogen concentration the N:P ratio has been determined during different seasons. Depend on season and sampling point N:P ratio varied from 20:1 till 1:154. |