ABSTRACT
This research aims to study the seasonal variation in water quality parameters of Euphrates River at Najaf Province in Iraq during winter and summer seasons by using statistical test. Six water quality parameters were measured during the period from 2007 to 2012 in January and July. These parameters were hydrogen power (pH), electrical conductivity (EC), total dissolved solids (TDS), magnesium (Mg+2), chlorides (Cl–), and sulfates (SO4-2). Paired t-test was used six times to estimate the equality and inequality of the six water quality parameters in January and July. It was noticed that the values of water quality parameters in July were greater than their values in January for more parameters at significant (0.01) except for EC, where the test accept the equality hypotheses. This means that the water quality of the Euphrates River in Najaf Province became worse in summer than in winter for most parameters.
