Assessing the Quality Change of Some Parameters of Karun River Water at a Four -Year Interval

Abstract

Surface water resources, especially rivers, are at risk more than other sources for the reason of many uses. This study aims to examine some quality parameters of Karun river water in the Gotovand spatial range to Ahwaz during the years of 2010-2013.The data investigated in this study were obtained from the annual mean biochemical parameters measurements at nine sampling stations at the Water Affairs Administration of Khouzestan province. To this end, it is used of post-test LSD test so as to investigate the process of river water quality changes. The results of the study shows that there was no significant difference in chemical oxygen demand (COD) among stations, but the mean dissolved oxygen (DO) and biochemical oxidation demand (BOD5) were significantly different between stations. It is observed that the highest average DO at station1 (Gotovand) at a rate of 17.7 milligrams per liter and the highest average at station 9 (Gorgor - Band-e-Ghir) at 4.39 milligrams per liter. Also, there is no significant difference of the average amount of dissolved oxygen (DO), but there is a decreasing process of average value BOD5 while increasing the average amount COD from 11.8 mg/L in 2010 to 20.2 mg/L in 2013 so that it indicates an increase in the chemical contamination of river water. The study of microbiological properties (total and excremental coli-forms) did not show any significant difference during the studied years, but among the contaminated stations the most contaminated stations were the stations No.5 (Gorgor-Shoshtar) and No. 15 (Ahwaz Fifth- bridge) with comparison to other stations. It indicates that there is the population density in these areas, as urban wastewater enters the river without any treatment. Considering that industrial and agricultural wastewaters are affecting factors for quality parameters, suggested that these wastewaters be allowed to drain into the river after proper treatment.