Studying the specific characteristics of the water of some wells in the city of Tikrit

for the period from December 2016 to March 2017 where its ages ranged from 6 to 27 years and the depths between 90 120 m and are all used to irrigate crops and for washing. Some physical and chemical properties were also studied, temperature which ranged between 22-23.6 C° and electrical conductivity which ranged between1742.5-3002.5 microsimens / cm and the total alkaline which ranged between 53-193 mg / L, as well as many other properties total hardness, calcium and magnesium hardness, pH, sodium and potassium ions. The results proved that the well waters were hard and ranged between 1055.71257.48 mg / L.


1-Introduction
The study of underground water is of important consideration since it is used for purposes of development, irrigation, agriculture, and in many urban and industrial fields.Therefore, the estimation of underground water in an accurate and correct manner with the study of underground water properties has become of important consideration for its development, organization and protection to ensure its continued availability as a natural source of water [1,2].The mineral content of the underground water varies according to the geological nature of the area through which the water passes through and stabilizes.In general, the majority of the underground water has a high salt content, so that the water is hard, and this water hardness decreases with the decrease of salts [3].In addition, the salts transferred to the underground waters by washing and filtration processes and the tremendous development of agricultural and animal fields with the establishment of industrial and population complexes near the wells as well as the use of chemical fertilizers and waste water are considered a source for underground water pollution and deterioration of its quality, which poses a health hazard to consumers of water wells [4,5].The quality of underground water varies according to geographical location, well depth, climatic and seasonal changes and solubility, through contact with rocks and waters, resulting in an increase in the concentration of water soluble substances [6].and which increase continuously by being exposed to materials and elements in the ground layers [7].Thus, improving underground water quality and making it conform to the standards of drinking water has become important with the increase of population and the increasing of different needs for freshwater by improving the physical and chemical properties of water [8].In the study of the physical and chemical properties of underground water in the district of Sharqat, it was found that the water of some wells in the study area was very hard [9].It was also noted that the water of some wells in the city of Samarra was very hard and the positive and negative ions were uneven due to different sources of nutrition [10].The underground waters in the city of Tikrit and its suburbs were found to be pH-neutral and medium to slightly high electrical conductivity with high water hardness [11].
The research was aimed at studying some physical and chemical properties of ten wells in the city of Tikrit.

2-Materials and Methods
Five wells were studied in the city of Tikrit, in an open area that extended from Tikrit University in the north to Tikrit Teaching Hospital in the south and from the Tigris River in the east to Baghdad Road in the west.Water samples were collected from wells for the period from December 2016 to March 2017, and once a month.The wells were numbered from 1-5 according to

1-Physical Properties 1-1 Water Temperature
The water temperature of the study wells are shown in Table (1).[17][4][18].in the study of the quality of wells in Kirkuk governorate.The results of the statistical analysis according to the test of variance analysis of water temperature showed that there were significant temporal differences and no significant spatial differences between the study wells at a significant level (p≤ 0.05), as shown in Table (2).The reason for the discrepancy in the current study may be due to the region's climate variability during the months of the year and the difference in the sampling time [19].

1-2 E.C. Electrical Conductivity
The results of the study in Table (3) indicate that the average values of the electrical conductivity ranged from 2425-3002.5 microsimens / cm in wells 1 and 2 respectively.The lowest value was 2390 microsimens / cm in February 2017 in well 2 and the highest value was 3080 microsimens / cm in the month of February 2016 in the well 1.These results were similar to those by [20]. in her study of underground water quality assessment in the Musayyib project area and its validity for irrigation ranging from 3210-1555 μm/ cm in wells 5 and 1, respectively.This difference in the values of electrical conductivity in the studied wells may be due to the difference in the geological formations between the regions.The characteristics of the natural water depends on the type of rocks and the soil that are in contact with it, the time period of the contact process and the distance between the wells [21].The processes of washing with rainwater also washes away salts from neighboring lands [22].The results of the statistical analysis according to the Duncan mean test showed significant spatial differences with no significant temporal differences at a significant level (p≤0.05) between the study wells as shown in the table below.[4] where the soluble salt concentration values ranged between 707.8-1205.5 mg/L, respectively.This was also lower than the results by [23].recording 5416 mg / l respectively.The results of the statistical analysis using the Duncan test showed significant spatial and temporal differences at a significant level (P≤0.05).The increase in dissolved solids may be due to the increase of some ions such as sulfur ions as shown in Table 17.This is what [24].observed as that it is all dissolved solids in ionized and non-ionized solution and dissolved gases.

2-2 Total Hardness
The results of the present study in Table ( 6) showed that the total hardness rates ranged between 1078.3-1242.21mg/L in the water of wells 3 and 4, respectively.The lowest concentration of total hardness was 846 mg/ L in January 2017 in wells 2, 4 and 5 and the highest value was 1,636.2mg /L in February 2017 in well 5.The results of the current study were lower than the results of the study by [25].
as the total hardness averages ranged between (1420-1990) mg/ L, and higher than those by [27].where the total hardness values ranged from 150 to 382 mg /L.The results of Duncan's statistical analysis showed no significant spatial differences with significant temporal differences at a significant level (P≤0.05).It is most likely that the values of hardness in well water at this level are likely to appear in the geological formations in the areas where these wells are abundant with calcium limestone and calcium sulphate, which are important sources of water scarcity [26].

2-3 Calcium Hardness
The results of the current study in Table (7) showed that the values of calcium hardness ranged between 468.9-569.26mg/ L in wells 1 and 4 respectively, and the lowest concentration of calcium hardness was 424.8 mg/ L in February in well 1 and the highest concentration 628.26 Mg/ L in March in well 4.The results of the present study were lower than those by [25].Study where the values of calcium hardness ranged between (1089-1542) mg/ L, while they were close to the results of the study by [17].for well water as the values of the hardness of calcium ranged between (390-699) mg/L.The results of the statistical analysis using the Duncan test showed that there were significant temporal and spatial differences of calcium concentration at a significant level (p≤0.05).
Calcium ions are mainly due to the geological nature of the areas in which the water passes.Calcium accounts for 30.23% of sedimentary rocks [28].

2-4 Magnesium Hardness
The results of the current study in Table (8) showed that the concentration averages of magnesium hardness ranged between 414.55 -505.29 mg / L in wells 2 and 4, respectively.The lowest value of magnesium concentration was 184.46 mg/ L in January in well 4 and the highest 972 mg/ L in December in well 4.The results of the present study were higher than the results by [25].where the concentration averages of magnesium hardness ranged between 331-571 mg/ L. The results of the statistical analysis using the Duncan test showed that there were significant temporal differences with no significant spatial differences as shown in  Table (9) shows that the results of the current study of the total alkilinity are close to the results by [25].The rates ranged between (53.6-124.2) mg / L. And lower than the results by [17].The total alkilinity values ranged from 208-540 mg / L. The results of the statistical analysis according to the the Duncan mean test clarified that there were no significant temporal differences with significant spatial differences at a significant level (p≤0.05).noted that the total base values may be due to the nature of the geological formations of the study area [23].

2-7 Potassium Ions
The results of the present study showed in Table (11) that the average potassium ions were 2.4-4.1 mg / L in wells 2,3 and 5.The lowest recorded value of potassium ions was 2.1 mg/L in well 2 during December and well 4 during March and the highest was 4.5 mg/ L in well 5 during January.The results of the present study were lower than those by [27].
The lowest value of potassium ions was 0.001 mg / L and the highest value was 1.214 mg / L, where it was lower than the study by [31].with the lowest value of potassium 8.81 mg / l, while the highest value was 12.34 mg / L. The results of the statistical analysis according to the Duncan mean test were the absence of significant temporal differences with significant spatial differences at a significant level (p≤ 0.05).The appearance of potassium in these concentrations is due to the geological nature of the region [29].

Table ( 2): Monthly changes of water temperature during the study period (C°) Date Well 1 Well 2 Well 3 Well 4 Well 5 Average
respectively, therefore, in the current study, these waters were classified in the average as warm waters due to a temperature exceeding 18 ° C and the lowest temperature recorded as 18 ° C in wells 2 and 3 respectively in December 2016 while the highest temperature recorded was 26.5 at the well 2 in March 2017.The temperature of underground water depends on the depth of the layer carrying it, its geographic latitude and the source of this water[16].The results are similar to those reached by

Table ( 3) :Electrical conductivity of water wells during the study period (microsimens / cm)
The results of the current study inTable (4)show that soluble salt concentrations ranged from 1621.82 to 2037.92 mg/L in wells 2 and 1, respectively, and the lowest value was 1492.99 mg/L in March in well 2 and the highest value was 2149.27mg/L in December in well 1.The results were higher than the results by