Spatial Distribution of Heavy Metals in the Soil of Different Area at Right Bank in Mosul City, Northern Iraq, Part 1

Abstract


Introduction
Pollution is an environmental phenomenon that has been given a great attention from Governments all over the world since the second half of the twentieth century, when it is considered as one of the most pressing environmental problems that had taken serious environmental and economic dimensions.Among the many pollutants, soil pollution with heavy metals has been given a great attention due to its toxic nature as one of the most dangerous types of pollution (Wang et al., 2019;Adimala, 2020).As a long-term exposure to high levels of heavy metals, various environmental and health risks may occur.Although there is no specific definition of heavy metals, they can be defined as a group of natural elements that have a specific weight greater than (5.0) g/cm 3 (Duffus, 2002;Obodia et al., 2011).
Heavy elements are characterized by being non-degradable and non-decayed with time, so increasing their concentrations beyond the permissible limit will cause harmful and toxic effects on the environment in general and living organisms in particular (Huang et al., 2020).Although some heavy elements are necessary for life when they are in low concentrations, such as iron, copper, zinc and selenium, they become toxic when they are present in concentrations higher than their natural limits in the soil (Barbes et al., 2020).
The total concentration of heavy metals in soils varies greatly according to the diversity of pollution sources (Alloway, 1990); and to the atmosphere through its pollution by suspended particles contributing to deterioration of the soil quality (Barbulescu and Postolache, 2021)).Heavy metal pollution is accompanied by changes in some physical and chemical properties of the soil and thus leads to a disruption of the biological balance of the elements (Alloway, 1990;Aydinalp and Marinova, 2003).Because of sedimentation and absorption processes in the soil, toxicity occurs, for example, with the elements zinc (Zn), copper (Cu), and nickel (Ni), while the toxicity occurs with the elements lead (Pb), cobalt (Co), arsenic (As), and cadmium (Cd) under very special conditions.Then it moves to the food chain (Singh, 2005).Heavy metals may be present in the soil as a result of natural rock weathering or as part of the potential for pollution resulting from human, agricultural and industrial activities (Batwa-Ismail et al., 2021;Kafle et al., 2022).
The potential toxicity of plants and their entry of those heavy metals mentioned above into the food chain represents a chemical hazard because of their impact on human health, especially the occurrence of bioaccumulation (Barbieri et al., 2015;Huang et al., 2020).Sources of heavy elements in the environment include the earth's crust and the biosphere (ground and surface water), marine environment, burning of fossil fuels (coal, oil and natural gas), mining operations, and the intervention of some elements in the production of agricultural pesticides such as lead (Rinklebe and Shaheen, 2017;Vedenov et al., 1996).It is also noticed that the increase in the content of heavy metals in the soil is not only in areas with industrial activity, but also in areas far from industrial centers due to long-range transport in the atmosphere (Saur and Juste, 1994;Steinner and Njastad, 1995).
Correspondingly, military operations played a role in the pollution process during 2014-2017 in Nineveh Governorate and the city of Mosul in particular.The war resulted in the release of many pollutants into the environment through the fall of thousands of tons of bombs, missiles and remnants of weapons and ammunition, which led to huge or great losses not only for human beings but also for the environment as it affected negatively on the ecosystem causing an increase in the concentrations of heavy metals in the air, water and soil, which may have short or long-term effects (Campagna et al., 2017;Rodríguez-Seijo et al., 2016).Military activities usually lead to an increase of many heavy elements, including lead, cadmium, chromium, nickel, and zinc in the soil (Skalny et al., 2021).
The current study aims to identify the characteristics of the spatial distribution of some heavy metals (As, Cd, Cr, Ni, Pb, and Zn) contaminated with soil, and then assessing the levels of pollution with these heavy metals using pollution criteria: Geoaccumulation Index (I geo ), Enrichment Factor (EF), Contamination Factor (CF) for soils on the right bank of the city of Mosul, and identifying their potential sources.

Study Area
Geographically, the city of Mosul, the center of Nineveh Governorate in the northern part of Iraq is located between longitudes (43o 02' 59.65'') and (43o 13' 57.89'') E, and latitudes (36o 17' 23.86'') and (36o 25' 45.04'') N. The city of Mosul is located on both banks of the Tigris River (the right and left banks) (Fig. 1).In this research, the right bank has been studied.
Geologically, Mosul city lies within the simple folds zone, which is characterized by a large number of geological structures.As these folds are extended in two main directions, the first northwest-southeast parallel to the Zagros belt in most of the northeastern parts of Iraq, and the second direction is east-west parallel to the Taurus belt (Bolton, 1958).
According to the tectonic setting, Mosul city is located within the foothill zone in an unstable shelf of the Nubia-Arabian Platform (Buday and Jassim, 1987;Jassim and Buday, 2006b).No anticline or syncline folds are observed on the right side of the city, which indicates that the layers in the Fatha Formation are horizontal or semi-horizontal (Adeeb, 1988).Due to the impact of the main fault in the Mosul -Hammam al-Alil, which caused the rise of the right side of Mosul, and created a sharp difference in the topography of the city, the right side rises between 230-280 meters above sea level.The aforementioned fault and its extension had eroded most of the upper part of the Fatha Formation on the right side of the city.
Based on the stratigraphic aspect, the more significant part of the right side of Mosul city is covered by soil whose source is referred to the Fatha Formation (Middle Miocene), which is exposed within small exposures close to the Tigris River (Buday, 1980).The Fatha Formation represents the more significant part of the right side of the city, whose lower member is exposed there, while the upper member of it is exposed on the left side of the city, with a thickness of 81.5 meters, and the lower member is below the surface with a thickness of up to 38 meters.The main fault of Mosul -Hammam al-Alil caused the raising of the right side of the city of Mosul.The Fatha Formation deposits are spread in most areas of the right side of the city, and they are classified lithologically within the fault escarpment on the right side (Adeeb, 1988), and they represent the lower part of the divisions (Al-Jumaily, 1977;Hagopian, 1977;Munir, 1977;Sissakian, 1978).The southeastern part of the city is characterized by the presence of sediments of the flood plain, which occupies large areas of flat lands of Al-Duassa, Al-Nabi Sheet, Al-Tayaran, the eastern and western Danadan, and parts of the city center, as well as Hawi Alkaneesa area to the north.
The Fatha Formation consists of salt rocks (gypsum, anhydrite, and limestone) with a succession of clastic rocks (claystone, siltstones, and finally marl rocks) (Buday, 1980).About the soils on the right side, they are generally represented by all the superficial deposits resulting from the disintegration and weathering of rocky materials that are transported away by rivers or winds.The soil of the right side of the city is characterized by the presence of iron oxides and thickness variation from one place to another (Buday, 1980).

Sample Collection
The current study stages are three: The first one is the stage of the field work (sample collection) carried out during December 2021-March 2020.The random system soil sampling locations are selected after survey and field observations, as well as reviewing maps and satellite images of Mosul City.70 samples covering the right bank of the city were collected, and a geographical positioning device (GPS) is used to determine the locations given in Table1 and Fig. 2. The Auger machine is used to collect soil samples at depths of (0-30 cm) preserved in plastic bags and classified.
The second stage includes the preparation of the samples in the laboratory to conduct chemical analyses.Stones and plant residues were removed, and then dried in an electric oven at a temperature of 50°C for approximately 24 hours.The samples were ground in a ceramic grinder to avoid contamination, then sieved with a 75-micron sieve to achieve homogeneity, and then placed in sealed labeled plastic bags for analysis.
In the third stage, measurements of the acidity (pH) and electrical conductivity (EC) carried out using the electrical conductivity meter and the pH electrode method following Mclean (1982) in the Earth Sciences Laboratory.Determination of organic matter (OM) content has been carried out in the central laboratory of the College of Agriculture and Forestry at the University of Mosul following the method of Walkey (1947).Determination of the heavy metals (Arsenic (As); Cadmium (Cd); Chromium (Cr); Nickel (Ni); Lead (Pb), and Zinc (Zn)) in soil samples has been accomplished using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) technique at the Australian Laboratory Services (ALS) in Spain.

Assessment of Metal Contamination
To assess the soil contamination with heavy metals, three parameters are calculated: Geoaccumulation Index (Igeo), Enrichment Factor (EF), Contamination Factor (CF).Due to the lack of data set for the urban soil analysis on the right bank of the city of Mosul, it is relied on the abundance of these elements in the Earth's crust (average crust) according to Mason (1958).

Geoaccumulation Index (Igeo)
To find out the extent of heavy elements-enriched soil, Muller (1969) suggested using the coefficient (Igeo) to calculate the extent of soil contamination with heavy metals, applying the following equation: log2 [Cn/(1.5 * )]=Igeo. (1) where Cn represents the concentration of the heavy element in the current study samples, and Bn represents the concentration of the heavy element in the Background, represented by the average crust given by Mason (1958), and 1.5 represents a constant factor.It is used for the purpose of reducing the possible variations and changes of heavy elements that are exposed to natural and human influences (Muller, 1969: Kowalska et al., 2018).Muller (1969) classified the values of this coefficient into seven categories as shown in Table 2.  Moderately contaminated 2 > Igeo > 3 Moderately to heavily contaminated 3 > Igeo > 4 Heavily contaminated 4 > Igeo > 5 Heavily to Extremely contaminated Igeo ≥ 5 Extremely contaminated

Enrichment Factor (EF)
The enrichment factor (EF) is used to determine the relative content of heavy metals in the soil compared to the background rocks.It is also used as an indicator to distinguish between the sources of these elements in the soil, whether they are of natural origin or from human and industrial activities (Zhao et al., 2015;Kumar et al., 2017); in addition to assessing the state of environmental pollution (Feng et al., 2004).The following equation is used to calculate (EF) following Sinex and Helz (1981) and Barbieri et al. (2015): where (Cn/Fe) samples represent the ratio of the concentration of heavy metals/the concentration of iron in the soil of the study area.(Bn/Fe) background represents the ratio of the heavy element concentration in the reference rocks/the iron concentration in the reference rocks.
Iron, which is one of the proved elements, and its value is used as a reference in the earth's crust amongst other elements such as (Sc, Mn, Al, Ti, Fe) (Sinex and Helz, 1981) because it is one of the geochemical elements that are characterized by their abundance in the ecosystem (Chandrasekaran et al., 2015).If the value of EF < 1, this indicates that the heavy elements are coming from the source rocks or through natural weathering processes, while If EF > 1, this means that heavy metals are produced by human or industrial activities (Jiang et al., 2019;Zhang and Liu, 2002).There are five classes of enrichment plants that were suggested by Mmolawa et al. (2011) and Barbieri et al. (2015) as shown in Table 3. Extremely high enrichment

Contamination Factor (CF)
The contamination factor (CF) is one of the indicators that show the impact of human inputs causing soil pollution (Ahmed et al., 2016).The contamination factor is used to show the level of soil pollution with heavy metals (Hakanson, 1980) through the following equation: where (Cn)sample represents the concentration of the heavy element in the soil, (Bn)background represents the concentration of the heavy element in the earth's crust (Mason, 1958).The contamination factor (CF) was classified into four categories by Hakanson (1980) (Table 4).

Geochemical Maps
The geochemical map is an important tool to investigate the spatial distribution patterns of heavy metals in the soil, which usually helps in determining the high and low concentrations of these elements (Admialla, 2020;Jiang et al., 2019;Wang et al., 2017).The spatial distribution maps of the elements (As, Cd, Cr, Ni, Pb, Zn) in the soil are drawn for the right bank of Mosul City using Arc GIS program and IDWI method as shown in Fig. 3.

Physicochemical Parameters
The main physicochemical properties that are determined for the surface soils in Mosul City include the acidity function (pH), electrical conductivity (EC) and organic matter content (OM) as shown in Table 5.The pH function is an important factor that can be used to estimate the transport of elements, including heavy metals, in the soil; and it can be used to measure the level of toxicity and soil contamination (Sintorini et al., 2021).The range of the pH determined for the right side of Mosul City is (7.1-8.3) with an average of (7.56).It is noticed that the values of the pH are between neutral to weakly basic.Due to the narrow range of the acidity (pH) in the studied samples, so this criterion has a limited importance on the distribution of heavy metals, which largely determines their mobility due to the neutral semi-alkaline environment (Manta et al., 2002).In general, the movement of heavy metals decreases with the increase in the pH of the solution (Sintorini et al., 2021), meaning that the absorption of minerals in the soil increases with the increase in the acidity.
The electrical conductivity values for the soils of the right side of the city of Mosul range between (494-109 µs/cm) with a rate of (270.77µs/cm).Increasing the salt concentration in the soil usually leads to an increase in the electrical conductivity (Doerge et al., 1999); in addition to the presence of some ions in the soil, which leads to a change in the value of the electrical conductivity of the soil (Seifi et al., 2010).
The content of organic matter (OM) is one of the important characteristics that can play a role in determining the quality, stability, color and ability of soil to store water, so the properties of soil change with the changing its organic matter content.The organic matter in the soil consists of decomposed plant and animal residues, animals and soil microbes, and it is affected by the presence of humus and humic substances.Thus, the availability of these components reduces the movement of heavy elements in the soil (Bradl, 2004).Soil organic matter retains heavy elements through three mechanisms: complexation, adsorption and ion exchange (Rieuwerts et al., 1998).The content of organic matter in the soils of the right bank of the city of Mosul range between (6.19-2.41)with a rate of (4.5%); this is due to the nature of the waste thrown on the ground in addition to wastewater as a result of the high population density, which contributes to an increase in the content of organic matter.

Spatial Distribution of Soil ' s Heavy Metals
The results of heavy metal concentrations (As, Cd, Cr, Ni, Pb, Zn) in the soils of the right bank of Mosul City and the average crust are shown in Table 6 with the minimum, maximum, and average concentrations, in addition to the standard deviations (SD), and the coefficient of variation (CV).Sample R2 (Khatunya) is excluded from the calculations due to its high abnormal content of heavy elements.The following is a description of these elements:

Arsenic (As)
The concentration of arsenic in the soils of the right bank of Mosul City ranges between (5.24-9.75 ppm) with a rate of (6.50 ppm), which is 100% higher in all samples of the current study than its average in the earth's crust (Average Crust), which is (1.8 ppm) according to Mason (1958) and as shown in Fig. 4A.The oxidation states of the element are (As (III) and As (V) ).Arsenic (III) is present in anaerobic environments in the form of (AsO 3 ) 3-, while as As (V) is present in aerobic environments absorbing many arsenic compounds in the form of (AsO4) 3-.It is firmly rooted in soil and migrates only a few distances in groundwater and surface water (Jia et al., 2013;Niazi et al., 2018b).
The enrichment of the soil with this element in the study area can be attributed to the increase in the pH, which reached about 8.3 and this is consistent with what was mentioned by Vandana et al. (2011).Agricultural activities may be an important source of increasing the element (As) as its contents are high in pesticides and phosphate fertilizers (Dehghani et al., 2017;Hu et al., 2017).In addition, the role of military operations after firing many munitions, including rifle fire cannot be neglected because arsenic is one of the elements that enter into the production of ammunition and weapons (Lidija et al., 2018;Skalny et al., 2021).

Cadmium (Cd)
The concentration of cadmium element Cd in the soils of the right bank of Mosul City ranges between 0.13-0.67ppm with a rate of 0.23 ppm which is 58.3% higher than the average in the earth's crust (0.2 ppm) for the total samples in the current study according to Mason (1958) as shown in Figure (4B).Cadmium is in the form of a divalent ion Cd (II) , which is present in the form of cadmium carbonate as a main type in some types of soils, while it may be present in the form of cadmium sulfide in other types of soils, but in small quantities (Bi et al., 2006;Rinklebe and Shaheen, 2014).The reason for the increase in Cd is related to the increase in traffic density and thus the increased friction of car tires with the ground and the combustion of fuel derivatives containing some heavy elements, including cadmium, as well as the large spread of commercial electricity generators, batteries and electrical panels, as well as the accumulation and burning of piles of civil waste containing plastic materials, which leading to the emission of suspended particles containing vehicles cadmium (Meharg, 2016;Saeed et al., 2017).
The use of some phosphate fertilizers leads to addition of cadmium to the soil (Raven et al., 1998).The recent military operations and the accompanying heavy metals for weapons and ammunition used have a significant role in increasing the concentration of cadmium, as it usually appears with lead in the smelting and production of ammunition (Rodríguez-Seijo et al., 2016;Lidija et al., 2018).In addition, the high concentrations of Cd are due to the containment of oil derivatives such as gasoline, kerosene and diesel oil, which is emitted when burning these derivatives, as well as welding materials known as solders (Boutron and Wolff, 1989) as in the R2 sample, which has a concentration of Cd (3.09 m), where near to the sampling area, there is a repair shop for oil heaters.

Chromium (Cr)
The concentration of chromium in the soils of the right bank of Mosul City ranges between 59.40-135.50ppm with a rate of 95.32 ppm which is 44.29% higher than the average in the earth's crust (100 ppm) for the total samples in the current study according to Mason (1958) and as shown in Fig. C4 The oxidation states of chromium are (Cr (III) and Cr (VI) ).Cr (VI) represents the most common form of chromium found in contaminated soil, as its absorption decreases with the increase of pH.While Cr (III) is present in the soil when the pH value is <4, where its absorption increases with the increase in the pH ( Pendias and Pendias, 2001).Cr (VI) is more toxic and more mobile than Cr (III) , and chromium mobility depends on soil absorption properties including organic matter content (Alloway, 2013;Rinklebe et al., 2016c;Shahid et al., 2017).Chromium values are affected by human, industrial and agricultural activities such as fertilizer use, coal combustion and sewage sludge (Al-Jumaily, 2009;Chen and Lu, 2018).The emitted gases and fumes enhance the release of chromium and then deposition on the surface of the soil.In addition to the remnants of weapons and explosives thrown in the last war on the city, that contain high levels of chromium (Skalny et al., 2021), which had the greatest role in increasing this element in the soil of the study area.

Nickel (Ni)
The concentration of nickel in soil samples of the right bank of Mosul City ranges between 87.8-202.0ppm with a rate of 149.09 ppm which is 100% higher in all samples of the current study than its average in the earth's crust (Average Crust) which is 75 ppm, according to Mason (1958) and as shown in Fig. D4 Nickel can exist in several oxidation states from +I to +IV, but only the oxidation states of nickel (I, II,III) are stable over a wide range of acidic and reducing conditions found in soil environments.In soils with pH 6, nickel is present in the form of the binary nickel ion Ni (II) and becomes more mobile and often seeps into groundwater (Alloway, 2013;Rinklebe and Shaheen, 2017;Tchounwou et al., 2012).The high concentrations of Ni are related to the impact of sewage, household waste, and commercial activities, as well as the proximity of many samples to heavy traffic (Celestin & Bemard, 2015;Papazotos et al., 2016;Long et al., 2018), and fossil fuel combustion and agricultural activities and phosphate fertilizers have a significant effect on the increase in nickel concentration (Pendias & Mukherjee, 2007;Montgomery, 2011).Nickel is released into the air by electric power plants and garbage incinerators and settles on the ground (in the soil) due to sedimentation processes (Nazzal et al., 2021).As well as the remnants resulted from the missiles, bombs and various weapons that were thrown in the last war (Rodríguez-Seijo et al., 2016;Skalny et al., 2021).

Lead (Pb)
The concentration of lead element in the soil samples of the right bank of Mosul City ranges between 6.69-244 ppm with a rate of 26.13 ppm which is 37.14% higher than the total models in the current study than its average in the earth's crust (13 ppm) according to Mason (1958) and as shown in Fig. 4E.The pH plays an important role in the solubility and precipitation of lead in the soil.At a pH between 8-6 it works to accumulate lead in the soil (ATSDR, 1995).In the current study, the pH ranges between 7.6-8.3with a rate of 7.92 and this may accumulate lead in soil samples, as it usually remains attached to the outer surface of soil particles and remains stable in the upper centimeters of the soil.
The organic matter also has a role in preventing the transition of lead over long distances, so it accumulates in the soil and remains for a long time due to absorption by the organic matter (Kabatapendias and Mukherjee, 2007); and therefore, the high concentrations of lead reflect the state of pollution to which the soil has been exposed.The most stable form of lead in soil is lead (II).Lead sulfide (PbS) is the most stable solid form in soil formed under reducing conditions (Wuana and Okieimen, 2011).Soil contamination with lead is directly related to traffic density.Vehicle exhaust is one of the most important sources of lead contamination of soil in urban areas (Heil, 1999).Industrial activity, in turn, has also an impact on increasing the concentration of lead (Adimalla et al., 2019;Saljnikov et al., 2019).Moreover, the human activities such as incineration of civil waste releases the dust falling on the ground, in addition to construction and traffic emissions, which are the general sources of lead pollution in the soils of the study area.(Nazzal et al., 2021;Gao and Wang, 2018).Lead is used in the production of all types of ammunition and in the manufacture of projectiles (Wallace, 2008;Skalny et al., 2021).
All of these parameters contribute to increase the concentration of lead in the soil.As for the R61 sample from Danadan area, a residential area, the reason for the increase in the Igeo value of lead is due to human activities, including sewage, household waste, shop activities, and gaseous emissions resulting from electric power plants, in addition to emissions of vehicle exhausts.As for the R67 sample from Ghazlani camp, its Igeo reaches 33.646 which is categorized within (heavily contaminated) due to the previously used as a headquarters for military training and shooting ranges, where many weapons and ammunition were used, so many heavy elements can be found at high concentrations.In the R2 sample (Khatuniyah), the Igeo reached 4.507 which is within heavily to extremely contaminated and this increase is attributed to the same reasons mentioned in the previous paragraphs.Finally, Igeo for zinc (Zn) in the soil samples are between 1.29 -1.97 with a rate of 0.28.These values indicate that the geo-accumulation index (Igeo) for zinc is within the (uncontaminated to moderately contaminated) category according to the classification of Muller (1969), except for some samples such as R13 (Mayasa) and R38 (Industry 3), with (Igeo) equals to 1.55, 1.97 respectively, that are categorized within (moderately contaminated) owing to the same previous reasons.It has been found that the soil of the study area in general is uncontaminated to moderately contaminated with heavy elements, and this is due to the lack of industrial facilities in most areas of the city and thus the lack of pollution.Areas with high Igeo values (heavily contaminated) indicate the presence of many sources represented by anthropogenic activities (such as fumes emitted from burning solid wastes, emissions of vehicle exhausts and generators of electricity, contribution of liquid waste of the industrial areas in urban, irrigation, sewage, fertilizers and pesticides, which in turn led to soil pollution with heavy elements, in addition to the remnants of the military operations to liberate the city.

Enrichment Factor (EF)
Calculation of the enrichment factor (EF) for the heavy metals in the samples under study from the right bank of the city of Mosul as shown in Table 7 and Fig. 5b shows that the enrichment factor (EF) for arsenic (As) ranges between 4.63-10.37with a rate of 6.51.The results indicate that the enrichment factor (EF) for arsenic (As) is categorized within the (moderate enrichment-significant enrichment).Cadmium (Cd) has an enrichment factor (EF) ranges between (1.16-5.15)with a rate of (2.10), this indicates that its enrichment factor (EF) is categorized within the (moderate enrichment).Chromium (Cr) enrichment factor (EF) ranges between 1.30-2.30with a rate of 1.67 indicating that it is categorized within the (deficiency to minimal enrichment -moderate enrichment).
Nickel (Ni) enrichment factor (EF) ranges between 2.29-4.43 with a rate of 3.48.It is categorized within the moderate enrichment.The results of the enrichment factor of lead indicate a large variance ranging between 0.99-41.34with a rate of 3.79 which is categorized within the deficiency to minimal enrichmentmoderate enrichment except for the samples R2 (Khatoniya) and R61 (Al-Danadan), which have enrichment factors 38.462 and 29.244 respectively, and categorized within the (very high enrichment).This very high enrichment for R2 and R61 samples are due to the same reasons mentioned for the Igeo.R67 sample (Moasker Ghizlani 2) has (41.34) enrichment factor which indicates an (extremely high enrichment) for the same reasons mentioned for the Igeo.
Zink (Zn) enrichment factor (EF) ranges between 1.33-8.96with a rate of 2.42 which is categorized within the deficiency to minimal -moderate enrichment except for the samples R13 (Al-Mayasa), R30 (Al-Araibi), and R38 (Sinaa 3) whose enrichment factors are (7.359, 5.659, 8.956) respectively, indicating the (significant enrichment).The reason for the increase is due to the same reasons aforementioned, such as the R30 model in Al-Araibi area as a residential area, the reason for the increase in the value of EF is due to the intensive human activities, including sewage, household waste, commercial activities, and gaseous emissions resulting from electric power plants.Sample R2 (Khatoniya), whose enrichment factor (62.560) is categorized within the (extremely high enrichment).
It is clear that the EF values for heavy elements determined in this study are greater than one, meaning that pollution was resulted from human activities such as transportation, electrical generators, industrial waste, mining operations, the use of chemical fertilizers, pesticides and industrial waste (Adimalla, 2020;Adimalla et al., 2019).As well as the impact of remnants of the last war resulting from missiles, bombs, and ammunition during the military operations, which regarded as the most polluted soil samples with heavy metals.

Contamination Factor (CF)
Calculation of the enrichment factor (EF) for the heavy metals under study on the right bank of the city of Mosul as in Table 7 and Fig. 5C shows that the contamination factor (CF) for arsenic (As) ranges between 2.91_5.42 with a rate of 3.61 for cadmium (Cd) ranges between 0.66_3.37 with a rate of 1.17 for chromium (Cr) ranges between 0.60_1.36with a rate of 0.96 for nickel (Ni) ranges between 1.17_2.69with a rate of 1.99 for lead (Pb) ranges between 0.51_18.77with a rate of 2.01 and for zinc (Zn) ranges between 0.61-5.86 with a rate of 1.37.

Fig. 2 .
Fig. 2. Location map of soil samples in the studied area.

Fig. 4 .
Fig. 4. Heavy metals in the soil samples in the right bank

Fig. 5 .
Fig. 5. Minimum and maximum values of (A) geoaccumulation index (Igeo), (B) enrichment factor (EF) and (C) contamination factor (CF) of soil heavy metal from Right bank in the study area

Table 5 .
pH, EC and OM results of soil samples on the right bank of Mosul City

Table 6 .
Heavy metal concentration (in ppm) of soil samples on the Right bank of Mosul City

Table 7 .
Minimum, maximum and mean values of Igeo, EF and CF factors of soil heavy metals