INVESTIGATIONS OF SOME HEAVY METALS OF GROUNDWATER AQUIFER OF WADI EL NATROUN AREA IN EGYPT

Heavy metal (Cu, Zn, Mn, F, Cr, Ni, Cd, and Pb) concentrations of Wadi El Natrun aquifer were investigated. The determination of trace metals (Cu, Zn, Fe, Mn, and Pb) has been performed in order to study environmental pathways. Evaluation of Groundwater of the Pliocene Aquifer for Drinking Purposes According to International standards for the quality of drinking water The Samples that are away from the saline lakes are acceptable water for drinking but the samples which are close to the saline lakes permissible water for drinking.

The Fresh water is mainly concentrated in the central-eastern part The chloride (Cl-) and sulfate (SO42-) ions acquire the higher concentrations of the anions, while sodium (Na+), calcium (Ca2+) and magnesium (Mg2+) acquire the higher concentrations of the cations. The concentrations of the major ions are higher than the maximum standard limits, according to the World Health Organization (WHO, 1996).
The hydrochemical composition reflects the Na-HCO3 water type for the Quaternary aquifer, indicating recent meteoric water. Another major water type (Na-Cl) is recorded in the high salinity areas of northern and western parts. (A. M. Sharaky, 2007).
At Wadi El Natrun the available water resources include surface water (Rosetta branch and its irrigation channels) and relatively shallow groundwater that is mainly recharged from the surface water. Groundwater is the main source for domestic, industrial and agriculture use in the western Nile Delta region (Dawoud et al., 2005).
The present study focuses on:-1. Hydrochemical characterizations of the groundwater. 2. Chemical analysis of pollutants and determination of their source.

Evaluation of the groundwater suitability for different purposes
The recent studies including RIGW and IWACO (1991) indicate that the main recharge source for the groundwater in Wadi El Farigh and Wadi El Natrun was recent to old Nile water as well as some contributions from Western Desert Palaeowater There are several factors capable of impinging on groundwater quality not only the natural factors such as the lithology of the aquifer, the quality of recharge water and the type of interaction between water and aquifer, but also the human activities. Thus, there is a need to regularly evaluate groundwater quality for improving water management (Mahmood et al., 2011).
Location and climate of the study area:-Wadi El-Natrun, with its alkaline lakes, is an elongated depression about 90 Km North West of Cairo between latitudes 30° 15` north and longitude 30° 30` east ( Fig. 1&2). Its average length is 60 Km and average width about is 10 Km. The bottom of the Wadi is 23 m below sea-level and 38 m below the water level of the Rosetta branch of the Nile (Abdel Malek et al 1963).v The climate is characterized by a long hot summer and a short warm winter, low rainfall and high evaporation.
The northern slopes and depression edge; covers the area between the northeastern El Tahrir gravelly plain and depression floor. The northern slope is rather gentle and is distinguished into a number of steps or benches which correspond to the equivalent lithological variation. The surface of this slope is either degraded or covered with down wash deposits consisting of rock debris flinty pebbles. The slope surface is dissected by a number of short shallow runnels all directed towards the central depression area (Gomaa 1995).
The northern depression edge is structurally controlled and extended parallel to the general trend of the depression. This edge is structurally controlled and extended parallel to the general trend of the depression. This edge, rising about 80 m above the depression floor, is capped by weather resistant porcellaneous and cherty limestones. Underlying these limestones, there is a succession of soft gypsiferous sandy clay and sands intercalated with chalky and flinty limestones bands (Gomaa 1995).
The southern slopes; this slope is characterized by a rolling surface sloping in the northward direction from the southern El Mekhimien edge to Wadi El Natrun depression for a distance of about 45 km. Structurally, this slope is associated with the northern flank of the southern Wade El-Farigh anticline, hence, it is a homoclinal slope. Such slope is underlain by sands and sandstones belonging to the Miocene and Early Pliocene and is almost covered by a thin gravel mantle. This slope is dissected by a number of oriented wadies which are all directed towards the depression floor of Wadi El Natrun ( Gomaa 1995).
The depression floor; comprising the areas occupied by the present salt lakes and marshy lands, as well as the series of disconnected deep patches dominated by aeolian sand deposits. This configuration reflects the existing geological structures, noticed on the surface or detected in the subsurface (Gomaa, 1995).

The Wadi El Natrun, Depression:-
The Wadi El Natrun, depression represents a marked land feature in the area. It exhibits various morphological features that reflect the local geologic and topographic settings. The depression exists at the western extreme of the old alluvial plain. It represents a huge, oval, double plunging anticlinal structure that is bounded by normal faults and trends in a NW-SE direction. According to ( El Fayoumy, 1964 andSanad, 1973), three local geomorphic provinces were distinguished within direction. According to ( El Fayoumy, 1964 andSanad, 1973), three local geomorphic provinces were distinguished within Wadi El Natrun area, they are: the main depression with salty lakes, El Ralat Depression and Dier Makaryous (Beni Salama) Depression rich in natural soda or natrun, thenardite and halite. In addition, variable wind blew barriers of sand influence the subdivision of lakes. The number of Lakes present at any time is therefore variable (Taher, 1999).

Material and Methods:-Sampling and analysis:-
Groundwater samples were collected from 25 water wells and seven principle salt lakes at Wadi El Natrun area (Fig. 1). The wells have depths varying from 25.0 to 120 m. Each well has a standard galvanized iron pipe that was enforced vertically into the ground. The groundwater samples were collected in two-liter polyethylene bottles during 2013. They were chemically analyzed in order to determine the trace elements; the chemical analyses were carried out in the Ministry of Health -Central Health laboratories.
The concentrations of trace elements (Fe, Mn, Zn, Pb, Cd, Cr, Cu, Ni) were performed using atomic absorption flame spectrometric technique (GBC 908 AA) with lower detection limits ranging from 0.001 to 0.1 mg/L All samples were analyzed with a PerkinElmer Optima 8300® ICP-OES equipped with an ESI prepFAST™ Auto-Dilution System with an ESI SC-2 DX Autosampler.

Results and Discussion:-
Trace elements cause growth reduction due to toxicity, According to the National Academy of Science (1972), the maximum concentration for some trace elements in permanent irrigation of all soils, iron 5 ppm, manganese 0.2 ppm copper 0.2 ppm, lead 5 ppm and zinc 2 ppm. Comparing the obtained results (Table 19) with these values, we can deduce the following: The toxic metal concentrations (Pb, Fe, Cu, Cd, and Mn) in Miocene groundwater are elevated in the southwestern part of Wadi Farigh (El Kashouty 2004), which includes the south eastern part of Wadi El Natrun The Pleistocene groundwater flow is from the northern, eastern, and southeastern regions toward the depression. Therefore, the depression receives groundwater inflow from the Miocene and Pleistocene aquifers along with these toxic heavy metals. Part of these toxic metals is dissolved, some are suspended, and the rest (most) are precipitated to be included in the Pliocene aquifer sediments. In some cases, the inflow of groundwater with these toxic metals and anthropogenic activity into Pliocene aquifer increases the metal concentrations (Abdo and Sayed 2009), Particle chemistry, mineralogy, and pollution input control the heavy metal composition of the Pliocene aquifer sediments. The Wadi El Natrun is covered by intense agricultural activity. In addition, it receives pollution from domestic sewage, septic tanks, and fertilizers. Since the evaporation rate is high and the lakes lie in closed basins without outlet, the water in the lakes has a high salt concentration and is susceptible to the shallow aquifers in the depression.   All the selected samples show lead and zinc concentration below the maximum recommended limits Fig(8,9):. Samples No. 4,9,19,29 show that manganese ion concentration are higher than the maximum recommended limits Fig(6):.
From the previous mentioned data and when the groundwater is used for irrigation purpose in the study area, the element Mn, must be taken into consideration in case of sensitive crops. Iron contaminant is most probably produced from iron oxides that occur in the Pleistocene sediments Fig(10):.
The other trace elements (Ni, Cd, Cr and Cu) are most probably attributed to secondary minerals in the aquifer rocks Fig (3,4,5,7):.  (Tables 2& 3) TDS in drinking water originate from natural sources, sewage, urban run-off, and industrial wastewater. Reliable data on possible health effects associated with the ingestion of TDS in drinking-water are not available and no health-based guideline value is proposed (WHO, 1993). However, the presence of high levels of TDS in drinkingwater may be objectionable to consumers (WHO, 1993).