عنوان مقاله [English]
World population growth, quick process of industrialization and wide utilization of fertilizers cause the intensive and extensive intrance of pollutants specially nitrogen compounds in rivers and other aquatic environments increasingly. Un-ionized ammonia is one of the mineral nitrogen components that is very harmful for the aquatic organisms specially fish. In this study the trend of un-ionized ammonia pollution was investigated in Kor river during 9 months of the years 1384 and 1385 (2005 and 2006). The results showed that concentration of un-ionized ammonia vigorously increase (16-230 time of the background concentration) immediately downstream of the petrochemical plant and then decrease gently downstream of the Kor river during the course of the study. The results of the study also showed that the amount of un-ionized ammonia after the petrochemical plant increased to 0.2 to 1.4 mg/L is harmful for aquatic life due to concentrations higher than the standard values of short periods (0.05-0.35 mg/L) and long periods (0.01-0.02 mg/L).Therefore after petrochemical plant, we could not trace any aquatic life. The results of our research showed that the main point source of excreation of un-ionized ammonia is the petrochemical factory of Shiraz and other pollutants are additive. Among parameters that affecting the concentration of Un-ionized ammonia, the water pH was the most influence and the chlorine concentration was less effective.