This study was conducted on the river Tigris between Albo-Sayf and Hammam Al-Aleel, on four positions stretching along the river for eight months started from November 2010 to June 2011. The study concluded measurement of some biological factors. The results showed that the dissolved oxygen value ranged between (2.63-813) mg/L, the minimum value was recorded at station of Albo-Sayf at downstream Mosul city at November while maximum value recorded on station 4 Hamam Al-Aleel at April. The range value of biological oxygen demand (BOD 5) ranged between (1.93-17.2) mg/L the minimum value recorded at station 2 Jamasa village at June while the maximum value recorded at station 1 Albo-Sayf at April. While the research showed that the value of nitrate ranged between (0.40-1.59) mg/L the minimum value was at station 3 Lazaga village at June While the maximum value at station 1 Albo-Sayf at April. The value of orthophosphate ranged (0.21-1.25)mg/L the minimum value at station 2 Jamasa village while the maximum value at station 1 Albo-Sayf at April. Although the value of Sulfate range (74-114) mg/L the minimum value at station 1 Albo-Sayf at April , while the maximum value at station 4 Hammam Al-Aleel where there are many water sulfur springs at this station.

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In the current research, water samples were collected from selected sites in the Tigris River. The water samples were collected monthly started from September 2017 to January 2018.The results demonstrate that the total average values of radon activity level for the 5 months for site 1, site 2, site 3 and site 4 were 36.6, 28.5, 46.2 and 37.2 Bq.m−3, respectively. The average radon concentration value of the four sites during the 5 months was 37.1 Bq.m−3. Dissolved radon concentrations for the study samples were also calculated and their average values were 1.242, 0.930, 1.510 and 0.930 Bq.L−1 for site 1, site 2, site 3 and site 4, respectively. The overall average calculated radon surface exhalation rate for the water samples was 0.363 Bq.m−2.h−1. Annual effective doses due to water consumption for adults, children and babies were also calculated. The obtained values of radon concentrations in the study water samples were found to be lower than the maximum permissible concentrations in water as recommended by the US Environmental Protection Agency (EPA). Also, the results reveal that the radon activity level has its lowest value during November but that there are no considerable variations with different times of the year.