Assessment of nutrient contamination in surface water, case study of Ain Zada Dam (North-East of Algeria)

In order to evaluate the impact of potential pollutions on the water quality in the watershed of the upstream of wadi Boussellem (North-east of Algeria), the evolution of the chemical composition of waters of the Ain Zada dam was studied over a period of ten years. Using a linear model of trends method, have been detected and quantified for the substances that are connected with the fertilizers and domestic effluents. An increasing concentration is observed for most of these substances. The increase of 88% in COD, 66% in BOD 5 and the decrease of 4.3% in pH, suggests a degradation of O.M 85% by microorganisms. This degradation was accompanied by a decrease of 2% of O 2dis content. The large increases of E.C 76%, NH 4 290% and NO 2 100%, are related to a marked increase in fertilizers applications and the denitrification of NO 3 where latters declined by 77%. These increases are related also to the large amount of human and animal organic materials and industrial waste dumped.