SUMMARY
In this study, eight sites within Smaquli Dam in Erbil province were selected for water quality assessment. Water samples were collected monthly from September 2021 to June 2022. Results of physical and chemical parameters indicated that: Air and surface water temperature were changed from (4 to 35 ℃) and (5 to 37 ℃) respectively, turbidity values of studied sites were ranged between (1.40 and 23.00 NTU), site 1 tended to have higher turbidity. Whereas the higher level was observed during January. The values of electrical conductivity and total dissolved solids fluctuated between (544 to 811 μS.cm-1) and (274 to 406 mg.l-1) respectively. The pH value of studied sites was found to lie in the alkaline side, ranging from (7.60 to 8.50). However, total alkalinity, total acidity and total hardness ranged between (130 and 312 mg. CaCO3.l-1), (10 and 44 mg. CaCO3.l-1) and (164 and 284 mg. CaCO3.l-1) respectively.
On the other hand, calcium concentrations in studied area were dominated by magnesium concentrations during the period of study, the results of sodium and potassium ranged between (10.76 and 62.97 mg.l-1) and (2.27 and 8.76 mg.l-1) respectively. The minimum level of chloride was (12.996 mg.l-1) at site 3, while the maximum value was (37.988 mg.l-1) at site 7, Sulphate ranged from (57.04 to 150.23 mg.l-1). Sodium adsorption ratio (SAR) values ranged from (0.28 to 1.97 meq.l-1), that means studied water samples were suitable for irrigation purposes.
The concentration of nitrate, nitrite and reactive phosphorus ranged from (5.783 to 21.683 mg.l-1), (0.04 to 1.62 mg.l-1) and (0.15 to 2.15 mg.l-1) respectively. The quantitative data for the phytoplankton calculated at the studied sites showed spatial variation in total numbers, the maximum value was (22292.851 cell.l-1) recorded at site 5; the minimum value was (112.024 cell.l-1) at site 1, diatoms were the most dominant group of phytoplankton in studied sites. Chlorophyll a concentration in studied sites changed from (0.01 to 9.18 mg.m-3). Dissolved oxygen and Biochemical Oxygen Demand for five days ranged between (6.7-12.7 mg.l-1) and (0.9-6.3 mg.l-1).
On the other hand, heavy metals such as: zinc, iron, manganese, lead, cadmium, copper, cobalt, nickel and chromium were determined in water and sediment. In water, the results of heavy metals concentration showed that the zinc (Zn) value ranged from below detection limit (BDL) to 0.002 mg.l-1, Fe concentration ranged from (BDL to 4.104 mg.l-1). The values of manganese (Mn), cadmium (Cd), copper (Cu), cobalt (Co) and nickel (Ni) ranged from (non-detected (ND) to 0.085 mg.l-1), (ND to 0.003 mg.l-1), (BDL to 0.009 mg.l-1), (0.005 to 0.013 mg.l-1) and (BDL to 0.067 mg.l-1). In this investigation the values of lead (Pb) and chromium (Cr) in all studied sites were below detection limit (BDL) it means that less than 0.001. All heavy metals were not exceeded the maximum permissible levels based on the WHO and safe for drinking purposes.
Moreover, results of present study indicated that the total concentration of heavy metals in sediment samples decreases as (Fe>Mn>Ni>Cr>Zn> Cu> Pb>Cd>Co). In the present investigation, Fe was the highest in sediment sample, ranging between (2654.23 and 2692.69 mg.kg-1). Cobalt (Co) was non-detected in sediment sample.
The water quality index (WQI) was determined for drinking purposes based on the most important fifteen physical and chemical parameters, including; pH, electrical conductivity, turbidity, dissolved oxygen, biochemical oxygen demand, total alkalinity, total hardness, calcium and magnesium ions, sodium, potassium, chloride, nitrite, nitrate and sulphate. The results indicated that the water of the Smaquli Dam, with its inlet and outlet, is suitable for drinking after traditional treatment. (DWQI) of all sites, ranging from (68.11 to 83.93). This indicates good water quality for drinking purpose.
The value of irrigation water quality index ranged from (74.205-75.288), the results indicated that the studied water samples of all sites were “Good” classes for irrigation purposes.
Finally, ten parameters including: pH, turbidity, TDS, DO, total hardness, nitrate, iron, lead, manganese and zinc were determined to evaluate Smaquli Dam water quality for fish farming based on standard limits for each parameter. The results for all parameters of all locations were within the permissible standard limit for fish farming except total hardness parameter.