Total Hardness Values Research Articles

ASSESSMENT OF GREY WATER DISPOSAL AND DIFFERENT TREATMENT OPTIONS FOR DOMIZ CAMP IN DUHOK CITY

The objectives of this study are to characterize the grey water from Domiz refugee camp, to evaluate the impacts of grey water on the properties of soil, and to suggest different treatment options. Grey water produced in this camp is about 1380 m3/d. The average grey water generation was estimated about 42 L/c.d. Grey water and soil samples were collected from stream channel at three different places. The results show concentrated grey water because of the water consumption was low inside the camp. Average Chemical Oxygen Demand (COD), Total Dissolved Solids (TDS), Total hardness, Calcium, Magnesium, Sodium, Potassium, Chloride, Sulfate, Nitrate, and phosphate values for the most polluted point were 1700, 1096, 540, 127, 65, 151, 29, 153, 232, 31 and 17 mg/L respectively. Impact of grey water on the properties of soil shows that Sodium Adsorption Ratio (SAR) values of soil samples increased compared to the control sample. Different treatment options were discussed for reusing the produced grey water. Because of the high level of TDS, availability of land, and low cost, construction wetland (CW) was selected as best option.

Importance of Rocks and Their Weathering Products on Groundwater Quality in Central-East Cameroon

The present work highlights the influence of lithology on water quality in Méiganga and its surroundings. The main geological formations in this region include gneiss, granite and amphibolite. The soils developed on these rocks are of ABC type, which are acidic to slightly acidic. Electrical conductivity (EC), organic matter, total nitrogen, nitrate-nitrogen, sulfate, chloride, phosphorus and exchangeable base values were low to very low in the soil samples. Groundwater samples were investigated for their physicochemical characteristics. The wide ranges of EC values (15.1–436 µS/cm) and total dissolved solids (9–249 mg/L) revealed the heterogeneous distribution of hydrochemical processes within the groundwater of the area. The relative abundance of major dissolved species (mg/L) was Ca2+ > Na+ > Mg2+ > K+ for cations and HCO3− >> NO3− > Cl− > SO42− for anions. All the groundwater samples were soft, with total hardness values (2.54–136.65 mg/L) below the maximum permissible limits of the World Health Organization (WHO) guideline. The majority of water samples (67%) were classified as mixed CaMg-HCO3 type. Alkaline earth metal contents dominated those of alkali metals in 66.66% of samples. Thus, for the studied groundwater, Mg2+ and Ca2+ ion adsorption by clay minerals was almost nonexistent; this implies their release into the solution, which accounts for their high concentrations compared to alkali metals. Ion geochemistry revealed that water-rock interactions (silicate weathering) and ion exchange processes regulated the groundwater chemistry. One water sample points towards the evaporation domain of this diagram, indicating that groundwater probably does not originate from a deeper system. Kaolinite is the most stable secondary phase in the waters in the study area, in accordance with the geochemical process of monosiallitization, which predominated in the humid tropical zone.

Determination of water quality index and suitability of water bodies in Robertsganj, Sonbhadra district, Uttar Pradesh, India

Water, the elixir of life, is a prime natural resource, a basic human need, and a precious national asset. The quality of drinking water is a powerful environmental determinant of health. The main causes of deterioration in water quality are lack of unprotected water sites, high anthropogenic activities, direct discharge of industrial effluents and its geological structure. The present study was focused on the Water Quality Index (WQI) of ground water in Robertsganj (district head quarter of Sonbhadra), Uttar Pradesh. WQI is a useful tool for quick estimation of quality of any water resource. Water samples from five sampling stations were randomly collected from hand pump, well, tap water and water tank and analysed for physico-chemical parameters. The pH, total dissolved solids (TDS), electrical conductivity, total alkalinity, total hardness, Ca, Mg, Na, K, Cl, and SO4 were analysed for the different water samples. Except for electrical conductivity, TDS, total hardness and Ca value were high; none of the parameters exceeded the permissible values for water quality assessment as prescribed by the Bureau of Indian Standards (BIS). This study demonstrates that in general the groundwater quality status of Robertsganj ranged from good to unsuitable and only sample 1 is fit and sample 2, 3, 4 are poor and sample 5 is unfit for human consumption based on all the ten parameters of water quality index.

Physicochemical Assessment of Ground Water Qualities of some areas of Imphal East District of Manipur during Post-Monsoon-5th Phase

Fifteen ground water samples (represented by S-1 to S-15) were collected from different locations of Imphal East district of Manipur during post-monsoon of 2014. They were analyzed for physico-chemical parameters like temperature, pH, TDS (total dissolved solids), electrical conductivity (EC), total alkalinity (TA) (and hence CO32- and HCO3-), total hardness (TH), Ca2+, Mg2+, Na+, K+ and Cl−. Only ground waters represented by S-14 (of Achanbigei Makha Leikai) and S-15 (of Achanbigei Mayai Leikai) are found to be fit for drinking purpose from physico-chemical analysis point of view. However, ground waters represented by S-1 to S-13 may also be used for drinking purpose in absence of alternate sources and further it is necessary to treat them so as to keep high values of total alkalinity (for S-1 to S-13) and total hardness value for S-3 within acceptable limit (200 mg/L) of BIS standard for drinking water. All the fifteen ground waters are fit for other domestic purposes also. Besides these, all the fifteen ground waters (S-1 to S-15) are fit for irrigation purpose also.

English

The Central-African country of Chad, located in the Sahel-Sahara zone, faces diverse shortages of portable water. The only reliable source of water available for drinking, domestic and agricultural use in the Dababa Division is groundwater. Conventional hydro-geochemical and isotopic methodology, coupled with piezometric data, allowed investigators to identify the numerous process affecting not only water quality, but also aided them to assess its suitability for different uses. The types of groundwater encountered indicated the presence of Ca-Mg-HCO3, Na-HCO3, Cl-SO4 and Na-Ca-SO4 in descending order of abundance. The data presented in this investigation shows three processes influenced the groundwater quality; these are the alteration of silicate minerals by dissolved CO2, the cationic exchange and the evaporation phenomenon, in particular, in the piezometric depression. Additionally, to these findings, this article discussed the anthropogenic processes involved, whose effects are evident in many samples with nitrate concentrations above the WHO standards. Generally, the groundwater in the study area show signs of human contamination. Recent studies also indicate the development of cardiovascular diseases among the population of this area which are directly linked to the low total hardness (TH) values, or general softness, of the water. The groundwater in Dababa is, however, usable for agricultural and other domestic needs. Based on the calculation of Na‰ and the sodium adsorption ratio, the sampled waters are suitable for irrigation. Key words: Groundwater, World Health Organization (WHO), hydrogeochemistry, isotope, Dababa, Chad.

A method for determining and exploring the distribution of organic matters and hardness salts in natural waters

A question regarding how organic matters in water are associated with hardness salts hasn’t been completely studied. For partially clarifying this question, a water fractional separation and investigation method has been recommended. The experiments carried out by the recommended method showed that the dynamics of the distribution of total hardness and permanganate oxidation values in the fractions of frozen and melted water samples coincided completely based on which it has been concluded that organic matters in natural waters are associated with hardness salts and always distributed in this form. All these findings are useful information for the deep study of macro- and microelements in water.

Assessment of the quality of groundwater for drinking purposes in the Upper West and Northern regions of Ghana.

BackgroundUnderground water is an important natural resource serving as a reliable source of drinking water for many people worldwide, especially in developing countries. Underground water quality needs to be given a primary research and quality control attention due to possible contamination. This study was therefore designed to determine the physico-chemical and bacteriological quality of borehole water in the Upper West and Northern regions of Ghana.MethodsThe study was conducted in seven districts in Ghana (including six in the Upper West region and one in the Northern region). The bacterial load of the water samples was determined using standard microbiological methods. Physico-chemical properties including pH, total alkalinity, temperature, turbidity, true colour, total dissolved solids (TDS), electrical conductivity, total hardness, calcium hardness, magnesium hardness, total iron, calcium ion, magnesium ion, chloride ion, fluoride ion, aluminium ion, arsenic, ammonium ions, nitrate and nitrite concentrations were determined. The values obtained were compared with the World Health Organization (WHO) standards for drinking water.ResultsThe recorded pH, total alkalinity and temperature ranges were 6.14–7.50, 48–240 mg/l and 28.8–32.8 °C, respectively. Furthermore, the mean concentrations of iron, calcium, magnesium, chloride, fluoride, aluminium, arsenic, ammonium, nitrate and nitrite were 0.06, 22.11, 29.84, 13.97, 0.00, 0.00, 0.00, 0.01, 2.09 and 0.26 mg/l, respectively. Turbidity, true colour, TDS and electrical conductivity of the water samples ranged from 0.13 to 105 NTU, 5 to 130 HU, 80.1 to 524 mg/l and 131 to 873 µS/cm, respectively. In addition, the mean total hardness value was found to be 178.07 mg/l whereas calcium hardness and magnesium hardness respectively were 55.28 and 122.79 mg/l. Only 14% of the water samples tested positive for faecal coliforms.ConclusionThe study revealed that only a few of the values for the bacteriological and physico-chemical parameters of the water samples were above the tolerable limits recommended by the WHO. This calls for regular monitoring and purification of boreholes to ensure good water quality.

Asurvey on fluoride, nitrate, iron, manganese and total hardness in drinking water of Fereydoonkenar city during 2008-2013

The purpose of present study was to evaluate fluoride, nitrate, iron, manganese and total hardness in drinking water of wells and reservoirs in Fereidonkenar, Mazandaran, Northern Iran and compare the results with national and international standards. This cross-sectional descriptive study was carried out on data during five years from the spring of 2008 until the autumn of 2013. Studies were performed on 430 samples in the different seasons and years taken from water and wastewater company (WWC). The results showed that the average fluoride, nitrate, iron, manganese, total hardness concentrations obtained were 0.42, 10.2, 0.136, 0.03, 382.28 mg/l, respectively. The analysis showed a negative correlation between nitrate and fluoride, iron and manganese and a positive correlation with the hardness. The mean fluoride concentration was less than the standard. Total hardness value was more than recommend standard. Nitrate was below 50 mg/l, in accordance with national and international standards. The amount of iron and manganese in drinking water were acceptable. So, except for low fluoride and high total hardness, there was no any problem in other investigated parameters.

Physical and Chemical Properties Study on the Groundwater in Tuz District

The present study is carried out to detect some quality properties of groundwater at Tuz,. The results showed that air temperature noted minimum at ranged between (8-35)C° , and The recorded temperatures of ground water values range between (18-25)C°, Turbidity values for all wells water at the study area ranged (0.00-29.88)NTU, It is obtained that wells near-off the mountain chain Nafed dag increase of electric conductivity comparative ranged between (734-6890)µs/cm. Groundwater in the study area was Brackish dependence to the total dissolved salts ranged (20-5860)mg/l . The pH values ranging between (4.15-8.91) . It was noted that the values of the dissolved oxygen are few and almost non-existent in some cases it ranged between (0.8 -0.30)mg/l. Analysis of biological oxygen demand refers to wells water (very clean) levels involving (0.00 -0.15)mg/l. Reason of groundwater very hardness ranging values of total hardness , calcium and magnesium hardness between (300-2440) mg/l , (160-1400)mg/l and (44-1580)mg/l respectively. The total alkalinity ranged between (74-600)mg/l , The chloride ions in ground water of the studied within the permissible limits for watering of animals and irrigation of plants, with values range (0.00-349.89)mg/l . Sulphates range between (134.5-3326)mg/l .Sodium values for all wells water at the study area ranged (112.35 -495.59)mg/l. Potassium values for all wells water at the study area ranged (1.158-51.036)mg/l. As for plant nutrients , ranged between the values of silica (9.688-25.981)mg/l.The concentration of active nitrite ions ranged between (0.000 –1.212) µg NO-NO2/L .As the values of phosphate , ranged between (0.26-0.399) µg P-PO4/L during the study period.

Towards the development of a reactive filter from green resource for groundwater defluoridation

In order to develop a low cost reactive filter from a green biogenic resource, the shell of a Gastropod (GS) was calcined at different temperatures and the defluoridation efficiencies of the raw and calcined GS were evaluated in a batch process. The highest defluoridation efficiency was obtained with the GS calcined at 1000°C (i.e. TGS1000). The time–concentration profiles of the defluoridation process were described by the pseudo-second order kinetic equation and the Temkin equilibrium isotherm equation gave the best description of the defluoridation process in synthetic feed water and groundwater (GW) system. The determination of the effects of hydrochemistry on the defluoridation efficiency of the TGS1000 showed that variations in pH value, organic load and ionic strength had no visible influence on the magnitude and trend. Amongst the array of interfering ionic species studied, only carbonate exhibited negative impact on the defluoridation efficiency. Experimental evidences revealed that the underlying mechanisms of the defluoridation process were diverse (ionic bond formation, electrostatic attraction, ion exchange and occlusion into Ca(OH)2 framework) and not straitlaced. Groundwater (GW) defluoridation, using TGS1000, showed that the residual F− in the defluoridated water increased with initial F− concentration. The value of the monolayer Langmuir sorption capacity was lower in the GW system (qm=6.17mg/g) than in the synthetic feed water system (qm=19.84mg/g). The values of pH, electrical conductivity, Ca2+ concentrations, total hardness values were higher in the defluoridated water relative to the raw GW samples. The Mg2+ concentrations were below the detection limit and nitrate concentrations were appreciably attenuated in the treated water samples.

Hydrogeochemical characterization and quality assessment of groundwater in parts of Southern Gangetic Plain

A comprehensive assessment of groundwater is carried out in parts of the Southern Gangetic Plain to identify the hydrogeochemical processes influencing groundwater geochemistry and to ascertain the suitability of groundwater for drinking and irrigational uses. Results of detailed chemical analysis reveal that groundwater of the study area is slightly acidic (pH values from 6.2 to 7.37) during post-monsoon, with dominant concentrations of Na+ and Ca2+ cations and HCO3− and Cl− anions. Groundwater chemistry is largely controlled by rock-weathering and ion-exchange processes with secondary contribution from anthropogenic sources. In particular, values of EC, total hardness and concentrations of Na+ and HCO3− exceed the prescribed limits of Indian and WHO water quality standards. Suitability of groundwater for irrigation purposes are evaluated on the basis of sodium adsorption ratio, sodium percent (%Na+), magnesium hazard, residual sodium carbonate and Kelley’s index. In this regard, nearly 40–50 % of the groundwater in the study area is found to be of excellent to good quality. In addition, principal component analysis, performed to identify the dominant geochemical processes, shows that the first three components are together account for 80.84 and 78.85 % of the total variance in the dataset for post-monsoon and pre-monsoon periods, respectively. This analysis also reveals key contributions from hydrogeochemical processes like mineral dissolution, silicate and carbonate weathering alongside anthropogenic activities like leaching of fertilizers from agricultural lands.

Physicochemical analysis of ground water qualities of some areas of Imphal East and Senapati districts of Manipur during pre-monsoon

Fifteen ground water samples (−1 to S-15) were collected from 14 hand pumps and 1 dug well of Imphal Easting pre-monsoon period (May) of 2016. They were analyzed for various mperature, PH, TDS (total dissolved solids), electrical conductivity (EC), total hardness (TH), Ca2+, Mg2+, Na+ and Cl–. Only S-9 (dug well of Fifteen ground water samples (S-1 to S-15) were collected from 14 hand pumps and 1 dug well of Imphal East and Senapati Districts of Manipur during pre-monsoon period (May) of 2016. They were analyzed for various physicochemical parameters such as temperature, PH, TDS (total dissolved solids), electrical conductivity (EC), total alkalinity (TA), CO32-, HCO3−, total hardness (TH), Ca2+, Mg2+, Na+ and Cl−. Only S-9 (dug well of OkshuMayaiLeikai) of Imphal East District is perfectly found to be fit for drinking purpose from physicochemical analysis point of view. However, other remaining ground waters (S-1 to S-8 and S-10 to S-15) may also be used for drinking purpose in absence of alternate sources. In case of S-1 to S-8 and S-10 to S-15, some suitable treatments are necessary so as to keep corresponding values of total alkalinity, total hardness and Mg2+ below their corresponding acceptable limits of BIS standard for drinking water. All the ground waters (S-1 to S-15) are also fit for other domestic and irrigation purposes.

Salinity intrusion and groundwater quality in a coastal megacity - Lagos, Nigeria

This study assessed the seasonal variation in the groundwater quality and extent of saline intrusion in a Nigerian coastal megacity, Lagos. Sampling points were grouped into four zones: Lagoon water, and ground waters from zone 1 (< 5 km from Lagoon), zone 2 (5-10 km from Lagoon) and zone 3 (10 km and above from Lagoon), respectively. Water samples (rainy and dry season) were collected from all the sampling points and analysed for electrical conductivity, salinity, total hardness and other selected physico-chemical parameters. Electrical conductivity and salinity values in samples from all the sampling points over the two seasons were within the World Health Organization (WHO) and Standards Organisation of Nigeria (SON) recommended limits. The total hardness values determined in the two seasons (rainy vs. dry) for zone 1, zone 2 and zone 3 were (443.3 ± 14.9 vs. 566.7 ± 22.9) mg L&minus;1, (96.3 ± 23.6 vs. 110.0 ± 28.3) mg L&minus;1 and (53.0 ± 10.5 vs. 63.3 ± 14.7) mg L&minus;1 respectively. The water was hard in zone 1 over the two seasons but other parameters in zones 1, 2 and 3 met the recommended limits for potable water.

Salinity intrusion and groundwater quality in a coastal megacity - Lagos, Nigeria

This study assessed the seasonal variation in the groundwater quality and extent of saline intrusion in a Nigerian coastal megacity, Lagos. Sampling points were grouped into four zones: Lagoon water, and ground waters from zone 1 (< 5 km from Lagoon), zone 2 (5-10 km from Lagoon) and zone 3 (10 km and above from Lagoon), respectively. Water samples (rainy and dry season) were collected from all the sampling points and analysed for electrical conductivity, salinity, total hardness and other selected physico-chemical parameters. Electrical conductivity and salinity values in samples from all the sampling points over the two seasons were within the World Health Organization (WHO) and Standards Organisation of Nigeria (SON) recommended limits. The total hardness values determined in the two seasons (rainy vs. dry) for zone 1, zone 2 and zone 3 were (443.3 ± 14.9 vs. 566.7 ± 22.9) mg L−1, (96.3 ± 23.6 vs. 110.0 ± 28.3) mg L−1 and (53.0 ± 10.5 vs. 63.3 ± 14.7) mg L−1 respectively. The water was hard in zone 1 over the two seasons but other parameters in zones 1, 2 and 3 met the recommended limits for potable water.

Study of water quality in the distribution network of the centralized water supply system in the city of Lviv

The problem of water quality change in the distribution network of the centralized water supply system in the city of Lviv is considered, and some results of our research in this area are presented. The main purpose of the research is identifying the main factors of water quality change in the distribution network of the city. During the research, collection, analysis and synthesis of data on technological parameters of the distribution network were carried out, and the data of the analysis of eight water samples taken from residents in different districts of the city of Lviv were used. The results suggest that the increase in total hardness and alkalinity of water is caused by mixing of water from different water intakes in the distribution network; water oxidability growth - by probable accidents with entry of organic pollutants into the pipeline; increase in the concentration of total iron - by corrosion of long-life and great-length sites of the distribution network; reduction of free residual chlorine - by its spending on oxidation of chemicals contained in water and elimination of pathogenic microorganisms of biofilms on the inner walls of pipes. In some water samples, an excess of requirements of physiological full value of the mineral composition of drinking water by total hardness and probable value of solids, due to their increased values in the source water was observed. However, the values of water quality indices in the studied sites do not exceed the norms applicable to drinking water. To prevent the deterioration of the drinking water quality, and, therefore, the health of residents, the introduction of modern systems of monitoring and modeling of water quality change in the distribution network is recommended.

Comparative analysis of seasonal variations in physico-chemical parameters from Girna, Ozarkhed, Chankapur and Gangapur reservoirs in Nasik district.(M.S.)

The seasonal physico-chemical parameters like temperature, pH, total alkalinity, dissolved oxygen, total hardness, chlorides, salinity and electrical conductivity were determined seasonally from Girna, Ozarkhed, Chankapur and Gangapur reservoirs of Nasik district. Results of the present study indicated that the mean values of temperature, pH and total alkalinity were highest in summer season and lowest in winter season, mean values of dissolved oxygen was highest in winter season and lowest in summer season. The mean values of total hardness, salinity, chloride and electrical conductivity were highest during summer season and lowest during monsoon, in surface water sampled from four studied reservoirs. Thus result clearly indicated that the surface water of Girna reservoir was more polluted than other three reservoirs, while surface water of Gangapur reservoir was less polluted than other three studied reservoirs.

Assessment of physicochemical characteristics of Ganga Canal water quality in Uttarakhand

Assessment of physicochemical parameters of Ganga Canal water was carried out during 2012–2013 at Haridwar (Uttarakhand) with two different sites, i.e., Bhimgoda Barrage (site 1—control site) and Bahadrabad (site 2—contaminated site), where canal water flows with loads of pollution from highly commercial and industrial areas. During investigation, maximum turbidity (287.72 ± 56.28 JTU), total solids (1167.60 ± 303.90 mg l−1), free CO2 (1.88 ± 0.22 mg l−1), total hardness (60.14 ± 1.13 mg l−1), pH (7.1 ± 0.13), nitrate (0.048 ± 0.010), nitrite (0.019 ± 0.001), biochemical oxygen demand (2.866 ± 1.098), chemical oxygen demand (6.8 ± 2.61) and phosphate (0.087 ± 0.015), while minimum velocity (1.71 ± 0.19 ms−1), transparency (0.12 ± 0.08 m) and dissolved oxygen (7.95 ± 0.44 mg l−1) were recorded in monsoon season at site 2 in comparison with site 1. The mean values of these parameters were compared with WHO and ISI standards and found significant differences (p < 0.05) in the mean values of turbidity, total solids, pH, dissolved oxygen, free CO2 and total hardness with sampling sites. The turbidity of both the sites 1 and 2 was recorded above the permissible limit. Turbidity of site 2 is much higher than of site 1, so it is counted as more polluted. The values of the studied parameters were more during monsoon season and summer season at site 2 as compared to site 1. The results indicated that most of the physicochemical parameters from Ganga Canal system were within or at periphery in comparison with permissible limit of ISI and WHO for drinking water and therefore may be suitable for domestic purposes, but it requires perceptible consideration due to intense changes in climate and increase in pollution.

Comprehensive pilot-scale investigation of seawater nanofiltration softening by increasing permeate recovery with recirculation

Two commercial nanofiltration (NF) modules and one tight ultrafiltration module (with molecular weight cut-off of 20 kDa) were assembled to two integrated membrane systems to investigate comprehensively the NF efficiency of seawater softening. The effect of increasing NF permeate recovery (RNF) by recirculation and dosage of chemicals on the observed and the real NF separation performance, concentration polarization extent was evaluated. The results showed that under both HCl acid and antiscalant dosage condition (termed as Scheme II), the superior softening performances with 87.7–93.5% of the observed and 88.5–93.9% of the real total hardness removals were achieved at constant inlet cross-flow velocity of 0.05 m s−1, pressure of 2.02–2.67 MPa, temperature of 21–22°C, and NF retentate recycle ratio (Rr) of 1.69–37.16. The Ca2+, Mg2+, and SO42- ionic concentrations and the total hardness value in NF permeate with RNF at 65%, and NF permeate flux at 6.24 L m–2 h–1 in Scheme II were only around 176, 84, 45, and 798 mg L−1, which was much lower than that in typical SWRO feed streams, and indicated that NF90-4040 (termed as NF1) membrane under chemicals dosage yielded a relatively high efficiency of seawater softening.

Corrosion inhibition of st37 steel in geothermal fluid by Quercus robur and pomegranate peels extracts

Plant extracts have become important as an environmentally acceptable, readily available and renewable source of wide range of inhibitors. Tannins, a class of natural, non-toxic and biodegradable polyphenolic compounds, extracted from plant sources are already used as corrosion inhibitors in aqueous media. This study investigates the inhibiting effect of Quercus robur and pomegranate peels extracts on st37 steel corrosion in geothermal fluid using the Tafel polarization method. It was found that the extracts act as good corrosion inhibitors for geothermal fluid. 250 ppm of Quercus robur oak extract was seen to have 90% corrosion inhibition efficiency. The values of pH, potential, conductivity, total hardness and Ca2+ hardness, dissolved solid substance (TDS) and salinity of geothermal fluid were analyzed before and after the addition of extract into it. According to these analyses, increasing pH level more than 5 indicates that corrosion constructive aggressive ions (H+) decrease. Furthermore the decrease of conductivity values as a result of the decrease of inhibitor concentration shows that corrosion slows down. Ryznar and Langelier Indexes are calculated for AF11 well, reinjection and collected pools. The values of indexes show that geothermal fluid is corrosive and scale properties.

Application of geoelectrical and chemical methods for groundwater assessment in Isheri-North, Ogun state, Nigeria

Geoelectrical investigation and chemical analyses were carried out at Isheri North area of Ogun State in order to assess the groundwater quality at shallow depth and its deep potential zone for groundwater development. The study area has been selected for investigation due to infiltration of the polluted Ogun River. Forty-three (43) Schlumberger Vertical Electrical Soundings (VES) and chemical analyses of water samples from one hand dug well and two shallow boreholes in the study area were carried out. Four to five geoelectric layers which correspond to top soil, clayey sand, sandy clay, clay and sand were delineated. The longitudinal conductance values (0.02 - 0.106mhos) of the topsoil in the area reveal its poor to weak protective capacity, thus exposing the underlying clayey sand to contamination as reflected from its resistivity values ranging from 4.8-15.1m. This low resistivity zone at shallow depth (3 – 26m), occasioned by infiltration, was further ascertained by high values of conductivity, turbidity, total hardness, TDS, Cl, Fe, and Mn ions in the analyzed water samples taken at depth ranges from 9 – 16m. The results of the analyzed water samples from this shallow zone are beyond international standards for drinking water. The underlying clay resistivity values ranged between 1.9 - 6.1m and thickness varied from 50.8 - 100.5m. This acts as the seal for the underlying aquifer (sand layer). The resistivity of the sand layer varied from 91.7-159m with a depth interval of 101.7-109.4m and 73.4-82.3m in VES 1 and VES 14 respectively. This constitutes the deep aquifer units in the study area. The longitudinal conductance values of the overburden above the profound aquifer units varied between 10.5-33.0 mhos and are indicative of very good to excellent protective capacity rating. Thus, the underlying deep aquifer units are well protected from being contaminated.Keywords: Electrical Resistivity, Groundwater, Aquifer, Geoelectric Section