Carbono, nitrógeno y fósforo en la parte baja del río Ebro y en los canales de riego del Delta

Abstract

C, N and P in the lower part of the river Ebro and in the irrigation channels of the Ebro Delta. Nutrient dynamics (dissolved and particulate C, N and P) in the river water (last 60 km) and in the channels that irrigate the Ebro delta were estudied during 1986 and 1987. In the river, when discharge is lower than 300 ma s-', a salt water underflow appears. This produces high organic accumulation in the bottom layers and, as a result, there are very low dissolved oxygen content and high phosphorous and ammonia contents in the bottom water. The consumption of nutrient and oxygen is high in the irrigation channels. The oxidized forms of nutrients decrease in concentration and the reduced forms increase at the mouth of the channels.