# Exploratory Survey of Geochemical Aspects of Underground Water in Ehime Mbano Area Se Nigeria Onunkwo -A, Uzoije A.P Abstract-The exploratory survey of geochemical aspects of underground water resource in Ehime Mbano area of Imo State South-eastern Nigeria has been carried out. Since the creation of Ehime Mbano Local government area in 2001, there is the need for sub surface water quality assessment since the surface water has been polluted due to population explosion. The study was carried out by acquiring geologic and topographic maps of the area for easy identification of sample population areas, and to identify geological boundaries. Spring outcrops, landuse elements, especially waste dump sites and agricultural projects were visited and examined. A total of 6 water samples, 2 from springs and 4 from boreholes were collected randomly and analysed. Analysis was carried out using atomic absorption spectroscopy for major cations. Heavy metal analysis was undertaken using spectrophotometer, potassium was determined using flame photometer method, concentration of total iron (Fe2+) was determined calorimetrically using spekker absorption meter, while total dissolved solids (TDS) was determined using glass fiber filter. Turbimetric method was used to assess turbidity. Physical parameters like ph and dissolved oxygen were measured insitu in the field with appropriate standard meters. The result of geochemical survey shows that the water has high turbidity, high iron, slightly acidic, soft , portable and suitable for domestic, industrial and irrigation purposes. Above all the water has no bacteria presence, no heavy metals also no laxative effect. The average pollutional index of 2.50 indicates a slight pollution though Ezeoke Nsu area (NE) is highly polluted. Remediation to the problems of slight water pollution is proposed. the sub surface water resource, since the new trend of urbanization calls for industrial establishments and portable water. # I. Introduction Rock types, their weathered products and precipitation from rainfall contribute greatly to the chemistry and pollutional trend of surface and ground water (Wilson, 1981). Man's activities such as dumping of refuse, agricultural practices and animal dung also determine the pollution of surface and ground water (Horton, 1995). Groundwater pollution may also be caused by the disposal of solid or liquid wastes in pits, abandoned boreholes or even stream channels and landfills. Others are poorly constructed or designed septic tanks, sewage disposal systems (Ellis, 1988). Chemicals such as lead, arsenic and radioactive minerals derived from chemical waste disposal sites of factories and mining industries also contribute possible pollutants. The introduction of contaminant or pollutant into an aquifer system starts with the infiltration of the pollutant through a water medium induced by precipitation. Ground water pollution may be a point or diffuse source (Todd, 1959). Point source of groundwater pollution may result from the location of a disposal pits, ponds or lagoons, mines or industrial wastes, disposal points, direct into an unconfined aquifer system. Diffused groundwater pollution source are more complicated and hence difficult to identify and remediate since it is difficult to locate the origin and areas of impact of the contamination ( Raymond , 1979). The aim of the study is to examine the ground water contamination level in Ehime Mbano area of Imo state, south-eastern Nigeria. Water related diseases from subsurface has been reported in the past. Feachem et al. 1998 reported high incidence of waterrelated diseases in thickly populated settlements with their sources traced to wells. Also Palmer and Holman (1997), observed that chemical pollutants such as heavy metals which constituted cancer and other related illnesses was traced to the underlying ground water from poorly managed waste source in a Delhi city of India. In the strength of these, the assessment of the ground water quality of the study are becomes imperative following the unprecedented population explosion occasioned by the movement of the people to the suburbs due to government policy. The physiography is dominated by a segment of Northern , South eastern trending Okigwe regional escarpment which stands at elevation of between 61m and 122m above sea level ( Alfred 1992). Vegetation in the area is tropical rain forest which is prevalent in the Southern states of Nigeria ( Oguntoyimbo, 1987). Due to great demand of land in the area coupled with other human activities especially over grazing, the rain forest has been replaced by some economic crops such as oil palm forest. # II. Materials and Method The soil of the area is loamy with scattered pebbles (Gorrel, 1990). Thick vegetative covers has prevented soil erosion , however, erosion is prominent in the areas where road cuts, forest clearing and over cropping have opened up the soil to erosion elements # b) Data Collection Data was acquired from field work, laboratory investigations and libraries. Topographic and geologic maps on a scale of 1: 250,000 was obtained from Nigeria geological survey department, Enugu. Spring out crops, geological boundaries landuse especially waste dump sites were visited and examined. A total of 6 water samples were collected for organic and inorganic analysis Analysis was carried out using Atomic absorption spectroscopy for Ca 2+ , Na + , Mn 2+ , Cl -, Pb, Cd, Zn and Cu were analyzed with the aid of spectrophotometer while K+ was determined using flame photometer method. pH was measured with standard pH meter while the concentrations of total Iron (Fe) were determined calorimetrically using Spekker absorption meter. Total dissolved solids (TDS) was determined using glass fiber filter. The concentrations of Ca 2+ , Mg 2+ and Na + in milli equivalent / litre were used to obtain sodium absorption ratio (SAR).Turbidimetric method was used to assess turbidity. Physical parameters like pH and dissolved oxygen were measured insitu in the field with the appropriate standard meters. While anions like HCO 3 were estimated by titrimetric method. All details of analytical procedures are reported in Omidiran (2000). Clean plastic containers were used to contain the water samples. They were rinsed several times with the same water samples to be analyzed , then covered with air tight cork and carefully labeled and sent to the laboratory for analysis, within 24 hours of collection. The parameters analyzed are Temperature, dissolved oxygen, turbidity, conductivity, total dissolved solid iron (Fe 2+ ) Calcium (Ca 2+ ) Chloride (Cl -), bicarbonates (HCO3 -), total hardness and Sodium (Na + ) etc. Coliform count was analyzed as to estimate possible bacteria presence. Physical parameters such as oxygen, pH , conductivity and temperature were measured insitu in the field. # III. RESULTS AND DISCUSSION The result of water analysis of the 6 water samples compared with WHO (1984) The result of biochemical analysis is shown in table 4. It shows the examination of the total coliform count that indicates absence or presence of bacteria in water (Martin 1977). The result of the organic analysis of the ground water samples of table 4 indicates that there were no faecal coliform found in the water samples, therefore no pathogens in the water. On the whole, the high values of turbidity may be due to sediments from erosion and algae growth, urban runoff and flooding as a result of climatic change (Offodile 1988). The high level of iron (Fe2+) could be as a result of corrosion of steel pipes (Barnes and Clarke 1980). The possible effect of high iron are red or yellow strining of laundry and house hold fixtures (Palme et al 1997). The possible health effects are high concentration of iron stored in the pancreas, livers, spleen (Oteze 1991). High concentration of iron in the body can cause liver and lung problems (Offodile, 1987). From the piper plot, the ground water in Ehime Mbano and environs is portable and of calcium bicarbonate type (CaH Co3) The comparison of chemical analysis of Ehime Mbano subsurface water with American water works association standard (1991) for industrial water is shown in table 5 With reference to table 5, the groundwater in the area should be treated for iron before they are used for some industries eg. Laundry. In employing the pollutional index scale of Horton (1995), it is possible to calculate the pollution index of the area as to assess the extent of pollution. The Horton scale is shown in fig 4 . Unity value of (1) indicates a tolerable standard, but above this value (1) the water is polluted and below this (1) the water is not polluted. The pollutional index is calculated using the formular propounded by Horton (1995) (Horton 1995) The pollutional index of 3.336 within Nsu area (S1) shows that Ezeoke Nsu axis is the most polluted in Ehime Mbano NE area. The suitability of water for domestic purposes is based on total hardness, total dissolved solids (TDS) and portability (Davis and Dewest, 1996). The average value 8.86mg/l for total hardness and 14.3mg/l for TDS indicates that the water belongs to fresh and soft class. (Hem 1970, Carrol, 1962). The water therefore has no laxative effects (Oteze, 1991). The ground water in the area is slightly acidic (6.90). Acid level in water is an indication that there will be more of reduction than oxidation. ( Raymond 1979). This implies dissolution of metals leading to high TDS and consequent destruction of metal pipes. High pH causes bitter taste, while water, using appliances become encrusted (Hem, 1970). A comparison of the chemical result of the 6 water samples to American water works association (1991) shows that iron (fe2+) is 0.1 -1.0 mg/l, mn2+ (20 -250mg/l ), total hardness as Caco3 (0 -250mg/l, pH (6.5 -8.3), chlorides (20 -250mg/l) and TDS 50 -1500mg/l). This indicates that ground water in the study area is suitable for use in most industries. From the organic analysis carried out, there were no bacteria presence in water. Thus the water can be consumed without fear of water borne diseases. # IV. CONCLUSION AND RECOMMENDATION In conclusion, the exploratory survey of the geochemical aspects of underground water in Ehime Mbano shows that the water has high turbidity, high iron, slightly acidic soft and suitable for domestic, industrial and irrigation purposes. Above all the water has no laxative effect and no bacterial presence (hence no water borne diseases). Pollutional index of Horton indicates slight pollution. The pollutional index of 3.336 within Ezeoke Nsu shows that the NE section of Ehime Mbano is most polluted. To solve the minor problems of water standard, in the area, high turbidity can be solved by distillation and filtration. Problems of High iron can be solved by aeration, while the pH can be elevated slightly using alkaline fertilizer. Borehole owners should be encouraged to test their water periodically. Water chemistry examination should be carried out seasonally, since groundwater is subject to surface geological changes (Offodile, 1987). Government should standardize the activities of various water agencies and drilling companies and ensure strict compliance to specified methods of water borehole construction. Water treatment facilities should be made available and accessible to the public. There should be good public orientation and awareness programme, enlightening the masses on the importance of portable water quality standards as well as the adverse effects of contaminated water. 1![Fig. 1: Topographical Map of the Study Area Global Journal of Research in Engineering](image-2.png "Fig. 1 :") ![(Stephen 2004). The presence of Benin Formation is a contributory factor to soil erosion especially where they are exposed unprotected by vegetation ( Onunkwo -Akunne and Ahiarakwem 2001). Ehime Mbano and environs falls within Anambra -Imo sedimentary basin of South-eastern Nigeria and is underlain by Benin Formation (-miocene -recent) (youngest) Ameki Formation (Eocene) and Imo Shale Formation (Paleocene) and oldest in the area fig 2 and table 1.The major aquiferous formation is Benin Formation( Parkinson, 1970).](image-3.png "") ![fig3, the water plots within a calcium and bicarbonate type and also plots on the left side of the diamond shape of the pipers plot indicating a fresh water. Cation and anion relation in milliequivalent per metre shows that the basic cation constituents are in the following order Ca 2 + >Mg 2 +>Na 2 + + K+. For the anion values the relation holds as Hco 3 >cl-+ No 3 ->So4 2 -. This indicates the dominance of calcium and bicarbonate, giving rise to CaHCO3 water.](image-4.png "") 3![Fig. 3 Piper's Trilinear plot (1944)](image-5.png "Fig. 3") -7° 14 E to 7° 21E Fig I . The drainage pattern isa) Description of Study Area Ehime Mbano is located within Anambra / Imo sedimentary basin of South-eastern Nigeria. It is bounded by latitude 5° 37N to 5 °46 N and longitudedendritic typical of sedimentary rock with uniform resistance and homogenous geology (Dever and James, 1985). The area has a tropical climate and experience two air masses, equatorial maritime air masses , associated with rain bearing South-NeogeneRecentMarine deltaic deposits; alluviumMiocene-PieostoceneBenin FormationOligocene ? -MioceneOgwashi-Asaba FormationLedianNot representedBartonianPossibly upper part of Ameki FormationPaleogeneLutetianAmeki FormationYpresianPossibly lower most part ofAmeki FormationNankasandPaleoceneImo ShaleUpper Cretaceous DanianNsukka FormationMaestrichtianAjalli SandstoneMamu FormationCampanianEnuguShaleNkporo shaleConiacian-SantonianAwgu ShaleTuronianEze-Aku ShaleCenomanianOdukpani FormationLower CretaceousAlbianUnnamed Formations"Asu RiverAbakaliki ShaleGroup" 2 2April 2011Volume XI Issue IV Version IParameters Sodium (Na + ) Potassium (K + ) pH (at 29°CS1 1.83 3.30 7.20S2 1.64 0.80 BH 1 3.41 1.11 7.01 6.80BH 2 0.82 2.13 6.90BH 3 0.54 0.71 1.05 BH 4 Average WHO (2004) < 200 2.01 0.94 2.15 < 50 6.80 6.70 6.90 6.50-8.50 S2 Umualumaku LEGEND S1 Umuofor Ezeoke Nsu Stream/SpringTDS28.56 21.03 7.4012.54 9.03 7.45 14.3<1000Stream/SpringCalcium (Ca 2+ ) Magnesium (Mg 2+ ) 6.41 9.64 Total Hardness 16.05 12.01 5.03 8.02 3.68 3.99 1.35 Chloride (Cl -) 4.05 5.10 3.01 Conductivity (ms) 26.80 24.40 5.01 Phospahte (PO 4 2-) 7.70 6.34 2.13 Iron ( Fe 2+ ) 0.019 0.080 0.480 0.210 0.060 0.36 0.20 2. 73 4.81 5.03 5.65 1.68 2.82 3.00 3.21 4.41 7.63 8.03 8.86 2.42 3.60 2.81 3.50 12.40 7.03 6.62 13.7 2.00 1.64 1.90 3.62 Carbonates 16.41 14.00 8.01 6.33 8.14 6.82 9.95 Turbidity (NTU) 23.40 21.41 15.01 15.63 14.50 15.04 17.5 Nitrates (NO 3 -) 1.26 1.34 1.20 1.11 0.39 1.21 1.09 Sulphate ( SO 4 2-) 3.61 2.93 2.10 1.40 1.63 2.00 2.28 The average pH value of the six water samples is 6.90 which indicates a slightly acidic condition. The average value of total dissolved solids (TDS) is 14.33. The principal constituents of TDS are chloride, sulphate , calcium, magnesium and bicarbonate. Sodium content was used to classify water quality for irrigation purpose because of its reaction with soil to reduce the permeability (Etu Efeotor, 1981). Thus, the relation sodium was employed to determine the suitability of the water <50.00 BH1 Umualumaku Alaili Borehole <50.00 <250.0 BH2 Umuakanusi , Borehole <5.0 BH3 Umueze I Borehole <2000 <10.0 BH3 Umueze I Bore hole <0.30 <250.00 *BH 4 Umelekezala Borehole < 5 < 5.00 < 250.0 for irrigation purpose. According to Etu Efeotor 1981, water class based on SAR is classed as 0-10-excellent, 10-18-Good, 18-26 fair while > 26 is poor. Using equation 1, the SAR for components derived from table 3 for S 1 , S 2 , BH 1 , BH 2 , BH 3 and BH 4 are 0.1121, 0.1181, 0.09, .07, 0.964 and .0484 respectively indicating that the water is excellent for agricultural purposes ( Etu-Global Journal of Research in Engineeringabsorption ratioSAR =Na +( meq/L????..(1)( Ca 2+ + Mg 2+ ) ½ 3CATIONSComponentConcAtomicChargeEquivConc% ofCationsMg/lWeight?Mass (EM)Mg/lComponentCa 2+5.6540.08220.40.281943.56Mg 2+3.2124.31212.156.264140.81Na +0.0622.98122.989.04617.12K +2.1539.10139.102.05508.51Total0.647100ANIONSHco 3 -9.9561.02161.02.1658No 3 -1.0962.0162.0.0176So 4 2 -2.2896.06248.03.0475Cl -3.5035.45135.5.0981Total.3296100.002 3 4April 2011Volume XI Issue IV Version IGlobal Journal of Research in EngineeringSampleTotalDilutionOrganismFaecalFaecalE.colicl. WelchiHetertropiccoliformstereotocountcountplate countcountcocciiS 19510 29.5 x 10 2----S 28010 28.0 x 10 2----BH 17510 27.5 x 10 2----BH 21810 21.8 x 10 2----BH 32410 22.4 x 10 2----BH 42510 22.5 x 10 2---- 5ParametersAverage value of sample analyzed AWWA (1991) accepted standardTdS14.350-1, 500mg/lToral hardness8.660-250mg/lIron (Fe+)0.200.1-1.0mg/lPH6.906.5-8.3Chlorides3.5020-250mg/lManganese-0-0.5mg/l 6April 2011Volume XI Issue IV Version ICritical or Tolerable unity (1)Fig 4: Horton scale (1995)Global Journal of Research in EngineeringParameter mg/l pH at 29 0 C Turbidity (NTU)-3Ai 7.20 23.40 -2 Not polluted-11Wij 6.5-8.5 5.0 234 PollutedAi/Wij 0.960 4.680Conductivity (MS)26.801000.268TDS28.565000.057Iron (Fe+)0.0190.30.063Calcium Ca 2+9.64750.129Magnesium mg 2+6.41<300.214Potassium (K + )3.302000.017Sulphate (So4 2-)3.612500.014Phosphate (Po4 2-)7.70--Nitrate (No 3 -)1.26100.126Chloride (Co 3 2-)16.41Total Ai/Wij0.5953Total parameter6.584 Exploratory Survey of Geochemical Aspects of Underground Water in Ehime Mbano Area Se Nigeria ©2011 Global Journals Inc. (US) Exploratory Survey of Geochemical Aspects of Underground Water in Ehime Mbano Area Se Nigeria ©2011 Global Journals Inc. (US) Exploratory Survey of Geochemical Aspects of Underground Water in Ehime Mbano Area Se Nigeria ©2011 Global Journals Inc. (US) Exploratory Survey of Geochemical Aspects of Underground Water in Ehime Mbano Area Se Nigeria ©2011 Global Journals Inc. (US) Exploratory Survey of Geochemical Aspects of Underground Water in Ehime Mbano Area Se Nigeria ©2011 Global Journals Inc. (US) Exploratory Survey of Geochemical Aspects of Underground Water in Ehime Mbano Area Se Nigeria ©2011 Global Journals Inc. (US) Exploratory Survey of Geochemical Aspects of Underground Water in Ehime Mbano Area Se Nigeria ©2011 Global Journals Inc. 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