HYDROCHEMICAL CHARACTERISTICS AND WATER QUALITY ASSESSMENT IN ABU-ZAABAL AREA, EASTERN NILE DELTA, EGYPT

Objective: The study presents simple tools for water resources quality classification based on its chemical compositions in Abu Zaabal area, eastern Nile Delta, Egypt and assess the water quality for different uses.
Methods: 31 water samples were collected from different water resources in the study area and analyzed for physicochemical parameters. Hydrochemical relations, contour maps and statistical methods were used to estimate the contamination indices and evaluate the water resources for different purposes.
Results: 83.3% of groundwater samples is fresh water and 16.7% are brackish water. 85.7% of surface water samples are fresh and 14.3% is saline. 92% of groundwater samples and 71.5% of surface water samples are very hard water. According to HPI values, 8% of the quaternary groundwater samples are good, 4% are poor, 4% are very poor and 84% of the samples are unsuitable. All groundwater samples and 71% of surface water samples are contaminated with respect to ammonia.
Conclusion: Higher concentrations of TDS and heavy metal may be due to the clay nature of the soil, the marine sediments in the aquifer matrix together with the dissolution and leaching of minerals from agricultural, anthropogenic and industrial activities. The groundwater in the polluted zones is considered unsuitable for human drinking.


INTRODUCTION
Surface and Groundwater have an associated hydrological relationship affected by different factors related to geological; hydrological and climatic conditions where these factors control the circumstances of groundwater movement in shallow aquifers as well as the quantity of water can be gained or lost from the aquifer and river [1].
Due to industrial and agricultural activities, large amounts of untreated urban, industrial wastewater and rural household waste discharge into the Nile River, canals or agricultural drain, which become an easy dumping site for all types of wastes [2]. Ismailia Canal is the most distal downstream of the principal Nile River. And the water contains all the toxins that are discharged into the Nile. The Ismailia Canal has many pollution sources which potentially affect and deteriorate the canal's water quality [3]. Heavy metals are considered to be a serious pollution of aquatic ecosystems due to their environmental persistence and toxicity effects on living organisms [4]. In the aquatic environment, trace elements are partitioned between different environmental components (water, suspended solids, sediments and biota [5]. Water resources chemistry is due to long-term interaction between the water systems and the surrounding environment, which can indicate the water formation and migration [6,7].
The objective of this present study is to highlight the chemical compositions of different water resources in Abu Zaabal area, Eastern Nile Delta, Egypt. Assess the water quality for different uses.
The study area lies in the eastern portion of the River Nile delta in Qalyoubiya governorate, northeast Cairo city bounded by longitudes 31.320 and 31.440 E and latitudes 30.240 and 30.320 N, ( fig. 1) occupies about 20 km2. The study area is bounded by Cairo ring road from the North, Belbis city from the south, Shebin El Qanater city from the west and Cairo-Belbeis desert road from the east. Abu Zaabal is considered as a plain area with an average elevation of 27 m above the mean sea level [8]. The area under investigation is characterized by cultivating lands surrounded by urban localities, The urban area is served by freshwater pipelines coming from a Mostorod water station is situated in the northern part of the study area as well as many shallow-private wells have been drilled for water extraction.
Geologically The Pleistocene and Holocene quaternary deposits cover most of the study area; the Basaltic rocks belonging to an Upper Oligocene age are exposed at Abu Zaabal area, while the Pliocene and Miocene sediments outcrops at the eastern part of Ismailia canal. The Holocene Nile silt and clay cover the majority of the study area with different thickness varies from 0 to 20 m, the sand dune unites belongs to the Holocene age found in the eastern part of the study area.
The hydrological conditions and the groundwater aquifers of the eastern portion of the Nile delta were discussed by many authors [9][10][11][12][13].
The surface water infrastructure in the study area consists of a network of the surface water system (Ismailia canal, Belbies drain and Shebin El Qanater drain). The surface water systems are passing through Holocene deposits (Nile silt and clay deposits) and the Pleistocene sediments after the disappearance of the Holocene deposits. The contaminated liquids are directly discharged into canals, drain and on the land surface. The Pleistocene aquifer is influenced by the contaminated water infiltrates due to the small thickness of the clay cap.
The Quaternary aquifers are discriminated into the upper unit (Holocene aquitard) and the lower one (the Pleistocene aquifer) [11, 13 and 14]. The Pleistocene aquifer is overlain by the Holocene unit and underlain by the Pliocene clay in the majority of the area. Around Abu Zaabal Quarries, it is underlain by Miocene sediments or the Oligocene Basaltic sheet. The Holocene aquifer is composed of the Nile silt and clay, with thickness ranges between 0 m at the eastern portions of 20 m at the southwestern part of the study area. The Pleistocene aquifer consists of sand and gravel with clay lenses with thickness ranges between 0 to nearly 50 m, while at the northwestern part of the investigated area, they may reach 200 m. The groundwater movements in the Pleistocene aquifer are mainly due north and northwest reflected that Ismailia canal is the main recharging source as the surface water level in the canal is higher than the groundwater level. Besides, the recharges from irrigation canals and return flow after irrigation. Septic tanks and sewer systems are considered a local source of recharge. The main discharge of the Pleistocene aquifer takes place artificially through pumping wells used for irrigation and domestic uses.

Sampling procedures
Thirty-one water samples were collected from different water resources (24 samples from groundwater wells and 7 samples represents surface water systems) in August 2019; Surface water samples were collected using an autosampler and polyvinyl chloride Van Dorn bottle

Field measurements
The location (longitudes and latitudes) of the water points was recorded using global positioning system (GPS) model etrex 10 (Germany).
Water samples were collected in a 1000 ml clean polyethylene bottle which was used for major ions measurements, whereas a 50 ml clean polyethylene bottles was acidified with concentrated HNO3 to pH<2 for heavy metals detections. E. C and pH were measured in situ using portable meters (AD 310 and 3510, Jenway, UK).
Heavy metals and trace components (Al, B, Cd, Co, Cr, Cu, Fe, Pb, Mn, Mo, Ni, Sr, V and Zn) were detected by plasma optical emission mass spectrometer (ICP) (POEMSIII, thermo Jarrell elemental company USA), using 1000 mg/l (Merck) Stock solution for standard preparation. The water quality parameters were estimated to evaluate the water resources in the study area (tables 2, 3).

Physicochemical parameters of water resources
The physical and chemical analyses of water samples in Abu Zaabal area are summarized in (tables 4, 5).

Hydrogen ion concentration (pH)
The pH value reflects the acidic or alkaline material present in the water. The decrease of pH less than 7 reflects an increase in hydrogen ion concentration. Where the increase in pH more than 7 is reflects an increase in the hydroxyl ion. In the study area, the pH values range from 7.8 to 8.6 and from 8.0 to 8.7 for the ground and surface water, respectively, which indicates that the water resources in the study area are generally alkaline in nature. TDS = (Ca 2+ +Mg 2+ +Na + +K + +CO3 -+(HCO3 -/2)+SO4 2-+Cl -) [20] Total hardness (TH) TH = (Ca+Mg) ˣ 50 [21] Heavy metal pollution index (HPI) HPI= (∑ Wi× Qi)/∑ Wi (1) Wi is the unit weightage of the heavy metal (i), n is the number of heavy metals, Qi is the sub-index of the heavy metal. Wi= K Si (2) K is the proportionality constant; Si is the standard permissible limit of the heavy metal. Where, S1, S2, S3, and Si represent standards for different heavy metals in the groundwater samples. Qi= 100 (4) Vi is the monitored value of the i parameter in mg/l, HPI is classified into five classes, excellent (0-25), good , poor (51-75), very poor (76-100) and unsuitable (100). [22,23] Quality parameters Formula adopted Reference/source Nitrate pollution index (NPI) NPI = − Where Cs: The analytical concentration of nitrate. HAV: The threshold value of anthropogenic source (human affected value) taken as 20 mg/l. The water quality according to NPI values was classified into five types: clean (unpolluted)(NPI<0), light pollution (0<NPI<1), moderate pollution (1<NPI<2), significant pollution (2<NPI<3), very significant pollution (NPI>3). [24] Drinking water quality index (DWQI) The relative weight (Wi) is computed from the following equation: where Wi is the relative weight wi is the weight of each parameter n is the number of parameters qi= (Ci/Si) × 100 where qi is the quality rating Ci is the concentration of each chemical parameter in each water sample in milligrams per liter Si is the Egyptian drinking water standard for each chemical parameter in milligrams per liter according to the guidelines of the (Egyptian Higher Committee, 2007; WHO, 2011). For computing the WQI, the SI is first determined for each chemical parameter, which is then used to determine the WQI as per the following equation SIi =Wi × qi WQI =SIi where SIi is the sub-index of ith parameter qi is the rating based on the concentration of ith parameter n is the number of parameters The standard is the standard of the water quality parameter. The water samples were classified according to WQI rate as excellent, good, poor, very poor and unfit for human consumption (table 4). [25] Sodium Adsorption Ratio (SAR) SAR = Na Residual Sodium Carbonate (RSC) Sodium percentage (Na%) %Na = [(Na + +K + )/(Na++K + +Ca 2+ +Mg 2+ )] X 100 [28] Magnesium ratio (MAR) % Balance error (%E) %E = [(∑cation-anion)/(∑ cation+anion)] x 100 [20]

Total dissolved solids (TDS)
The water salinity of groundwater ranges of 243 mg/l to 3390 mg/l and in surface water of 240 mg/l to 5600 mg/l, as shown in ( fig. 2). 83.3% of groundwater samples are fresh water and 16.7% are brackish water. 85.7% from surface water samples are fresh and 14.3% is saline. Higher concentrations of TDS may be credited to the impact of evaporation and the marine sediments in the aquifer matrix together with the dissolution and leaching of minerals from agricultural, anthropogenic and industrial activities [32,33].

Total hardness
The total hardness (TH) is caused primarily by the presence of cations such as calcium and magnesium and anions such as carbonate, bicarbonate, chloride and sulfate in water. The total hardness values of groundwater samples range from 150 mg/l to 1300 mg/l reflected that 8% of these samples are hard and 92% are very hard water. The total hardness values in surface water range from 140 mg/l to 1480 mg/l reflected that 28.5% of samples are hard and 71.5% are very hard.

Soluble anions
Bicarbonate ion (HCO3 -) source is from the dissolution of carbonate rocks (dolomite, limestone, magnesites etc.). HCO3 is mainly formed due to the action of CO2 from the atmosphere and that released from organic decomposition [34,35]. Bicarbonate concentration in groundwater of the Quaternary (Pleistocene) aquifer varies from 138 mg/l to 520 mg/l and in surface water from 134 mg/l to 420 mg/l. The bicarbonate distribution in groundwater indicates that high content and the presence of local variations advocates the existence of local pollution sources. The distribution of bicarbonate salts increased from west to east. This direction may be due to the recharge of the quaternary aquifer from the Ismailia canal ( fig. 3. a).
Sulfate ion (SO4 2-) is naturally formed due to rock weathering, input from volcanoes and biochemical process [36]. The oxidation and decomposition of substances containing sulfur (fossil fuels and dissolution of sulfur-bearing minerals such as gypsum and pyrite) and anthropogenic activities are other sources of SO4 ions [35]. The sulfate content in groundwater of the Quaternary aquifer varies from 23.1 mg/l to 780 mg/l and from 28.9 mg/l to 1080 mg/l in surface water. The groundwater distribution of sulfate indicates the presence of local zones of high concentrations at Abu Zaabal, reflecting that the effect of the saline pond from the west and the influence of the sulfate fertilizers in the new reclaimed land in the east ( fig. 3. b).
The Clion form in nature is usually of chlorine salts (CaCl2, MgCl2 and NaCl). The main source is due to the leaching and dissolution of sedimentary rocks; common evaporates minerals and saline deposits. Industrial, municipal wastes and irrigated agricultural activities are other main sources of chloride salts [37]. The chloride content varies from 32 mg/l to 970 mg/l in the quaternary groundwater samples and from 35 mg/l to 1750 mg/l in surface water. The chloride content distribution in groundwater shows the presence of local zones of high concentrations at Abu Zaabal. The local variations in the chloride concentrations are attributed to local recharge from the saline ponds in the study area; this also confirms the existence of local pollution sources ( fig. 3. c).

Soluble cations
Calcium plays an important role in the health of water bodies which reduces the toxicity of s chemical compounds in natural water [38]. The removal of Ca 2+ ion from the water resources is due to an ionexchange or calcite (CaCO3 2-) precipitation. Calcite precipitation occurs when CO2 content is low, causing the chemical reaction process in the reverse direction [35]. The calcium content in groundwater of the Quaternary aquifer varies from 32.8 mg/l to 392 mg/l and from 32.8 mg/l to 384 mg/l in the surface water samples. The calcium distribution in groundwater confirms the presence of local zones of high concentrations that occurred at Abu Zaabal ( fig. 4. a). Hardness of water is attributed to the presence of calcium and magnesium ions; the water in the study area varied from hard to very hard.
A magnesium source water resources is due to chemical weathering and dissolution of dolomite, marls and other rocks [39]. Magnesium content in the Quaternary aquifer samples varies from 13.92 mg/l to 114 mg/l and from 11.5 mg/l to 124.8 mg/l in surface water. The magnesium distribution in groundwater shows the presence of local zones of high concentrations, but the magnesium contents are still below the excessive limits for drinking ( fig. 4. b).
A sodium source in the water resources is due to weathering of Na bearing minerals/rocks (halite, feldspar and montmorillonite), cation-exchange process (displacement from absorbing complex of rocks and soils by Ca and Mg), and anthropogenic activities (pollution from industrial effluent, domestic sewage, and agricultural activities). Sodium content in groundwater of the Quaternary (Pleistocene) aquifer varies from 18 mg/l to 442.9 mg/l and from 20 mg/l to 1265 mg/l in surface water. The distribution of sodium ions in the study area reflects local variations may be attributed to local recharge from the saline ponds in the study area. The groundwater in the polluted zones is considered unsuitable for drinking ( fig. 4. c). Potassium is slightly less common than sodium in igneous rocks, but more abundant in all sedimentary rocks. In igneous rocks, potassium is present as feldspars (orthoclase and microcline (KAlSi3O3)), wherein sediments it is present in clay minerals. Potassium is slightly less common than sodium in igneous rocks, but more abundant in all sedimentary rocks. In igneous rocks, potassium is present as feldspres (orthoclase and microcline (KAlSi3O3)), wherein sediments it is present in clay minerals. The concentration of potassium in natural water is generally less than 10 mg/l as much as 100 mg/l in hot springs and about 25000 mg/l in brines.

Minor, trace and heavy metals
Nitrate concentrations in the groundwater samples ranges between 12 mg/l to 42 mg/l and from 8 mg/l to 75 mg/l in the surface water samples. Nitrite concentration in the groundwater samples ranged between 0.05 mg/l to 0.51 mg/l and from 0.01 mg/l to 0.61 mg/l in the surface water samples. Ammonia concentration in the groundwater samples ranges between 0.5 mg/l to 3.7 mg/l and from 0.1 mg/l to 8 mg/l in the surface water samples. From the previous data, the groundwater samples are contaminated with ammonia. This shows that groundwater samples is mixed with sewage and the presence of Escherichia coli bacteria from bacteriological analysis of some groundwater samples proved that.

Nitrate pollution index
The source of nitrate in the groundwater is classified to nonpoint sources such as intensive agricultural activities and point sources such as irrigation of land by sewage effluents [40]. The surface water samples in the Abu Zaabal area are classified according to NPI values as follows: 43 % of the samples are cleaned (unpolluted), 14% are light-polluted, 14% of the samples are moderately polluted and 28% are significant pollution. Where the groundwater samples are 33% of samples are clean (unpolluted), 63% are samples are light polluted and 4% of the samples are moderate polluted table 6. The distribution of the NPI values presented that the majority of the study area located under light-polluted zone may be due to the influence of agricultural activities (nitrification of synthetic fertilizers and soil organic nitrogen). Where is the moderate pollution is located close to Bilbeis drain reflected the influence of groundwater recharge from the drain ( fig. 5).

Heavy metal pollution index (HPI)
The Heavy metal pollution index (HPI) for water resources in the study area was calculated based on the concentration of Al, Cu, Cd, Fe, Pb, Mn, Mo and Ni use the permissible limits according to WHO, 2011. HPI of surface water samples ranged between 31.8 and 993.2 reflected wide variation in the surface water resources in the study area (  . 6) reflects the increasing of the HPI values in the majority of the study area may be due to wider sources of pollution.   The evaluation of the water resources for drinking purposes according to quality parameters can be estimated water quality index values (WQI). The water quality index in this study is calculated according to 8 parameters (TDS, HCO3, Cl, SO4, NO3, Ca, Mg, and Na) has been assigned a weight (wi) according to its relative importance in the overall quality of water for drinking purposes table 3 [25]. The results of the drinking water quality index (DWQI) reflected that 57% of surface water samples are excellent, 28.5% are good and 14.% of samples tapping to Belbis drain are very poor for drinking purposes (table 6 and table 8). The evaluation of the groundwater samples is classified as: 50% of the groundwater samples are excellent, 29% are good, 13% are poor and 8% are very poor. The distribution of drinking water quality index values for the groundwater samples in Abu Zaabal ( fig. 7) area reflected the effect of the Belbis drain on the groundwater quality.   Water unsuitable for drinking purposes

The evaluation of water resources for irrigation purposes
The suitability of water for irrigation is determined by its mineral constituents and the type of the plant and soil to be irrigated. Water quality used for irrigation is well recognized as an important factor in the productivity of crops. The suitability of water for irrigation is determined not only by the total amount of salt present but also by the kind of salt. Different chemical factors affecting the suitability of water for irrigation and its effect on crop production and soil quality. Among these are: -Salinity hazard (EC)-total soluble salt content -Sodium hazard (SAR) -Sodium percentage (Na %): -Magnesium ratio (MR) -Residual sodium carbonate (RSC)

Salinity hazard (EC)
Based on the EC, irrigation water can be classified into four categories [42] as shown in table 9.

Sodium adsorption ratio (SAR)
Continued use of water having a high SAR leads to a breakdown in the physical structure of the soil. The sodium replaces calcium and magnesium sorbed on clay minerals and causes dispersion of soil particles. This dispersion results in the breakdown of soil aggregates and causes cementation of the soil under drying conditions as well as preventing infiltration of rainwater. Classification of irrigation water based on SAR values is shown in table 10.
Based on this classification, it should be noted that all samples are classified as class S1 except samples 8S and 15G are classified S2

Sodium percentage (Na %)
The groundwater samples are suitable for irrigation in 33.3% of samples and 42.8% of surface water samples according to Na% values. 50% and 28.6% from groundwater samples and surface water samples, respectively, were Permissible. 8.3% and 28.6% from groundwater samples and surface water samples, respectively, were doubtful. 8.3% and zero% from groundwater samples and surface water samples, respectively, were unsuitable (table 11).

Magnesium ratio (MR)
Calcium and magnesium maintain equilibrium in most waters, in equilibrium. Mg 2+ in the waters will adversely affect crop yield; magnesium impact on irrigated water is expressed as magnesium ratio (MR) (MR>50% is suitable for irrigation and MR<50% is unsuitable).
M. R values reflected that 45.8% of investigating groundwater samples are unsuitable for irrigation table 6.

Residual sodium carbonate (RSC)
An excess of sodium bicarbonate and carbonate is considered to be detrimental to the physical properties of soils as it causes dissolution of organic matter in the soil, which in turn leaves a black stain on the soil surface on drying; this excess amount is denoted by Residual Sodium Carbonate (RSC).
All samples (ground and surface) is good for irrigation table 6. (R. S. C>2.5 meq/l is unsuitable for irrigation, RSC values from 1.25 to 2.5