Seasonal variation of some contamination indicators in Euphrates river water in Al- Nasiriyah city

This study was aimed to evaluated the bacterial contamination of the Euphrates river flowing through the city of Nasiriyah , the study was included done some bacteriological tests on river water, and the samples were collected from three stations , included three indicators , total coliform (TC) bacteria , Fecal coliform (FC) and Fecal Streptococci (FS). The sampling performed monthly for monitoring of water river in 2016 , it was expressed seasonally , It was appeared that TC , FC and FS was registered higher rates for all stations in autumn in range (2900-4400) (2000- 3500), (11000 - 14000) cell / 100 ml respectively and the smallest rates was in summer season in ranged between (1500- 2600), (1800- 2200) and (3000 - 4200) cell / 100 ml respectively . The second station was appeared higher numbers of all indicators bacteria for all seasons in range (2600-4400), (2200-3500)and (1400-9200) cell / 100 ml respectively ,while The first station was registered smallest numbers of them for all seasons in ranges (1500-2900), (1500-2000)and (3000 - 13000) cell/ 100 ml respectively . According to parameters of water quality Interpretation and Standards of European Communities, 1989 and Environmental Protection Agency ,2001 , all numbers of TC were less the numbers of A1 category(˂5000 cell / 100ml ), FC bacteria were more than numbers of A1 (˃1000 cell / 100ml ) and less than numbers of A2 group (˂5000 cell / 100ml ) . In regarded of FS , they were larger than numbers of A2 group(˃2000 cell / 100ml) and larger than numbers of A3 group (˃10,000 cell / 100 ml ).The results of the study were found when studying the source of fecal contamination by using the proportion of FC to FS , all proportions to all stations in all seasons were less than 0.7,this indicate to contamination source was animal feces , except in station number 1 in spring the ratio was 1.88 which indicate to mixed contamination .