aniekan edet | University of Calabar, Calabar, Nigeria. (original) (raw)

Papers by aniekan edet

Increasing agriculture, industrial and urban growth have resulted in the rapid and an haphazard d... more Increasing agriculture, industrial and urban growth have resulted in the rapid and an haphazard development of groundwater resources through indiscriminate abstraction in the Cross River State (CRS), Nigeria. This has resulted in stress on groundwater, especially in areas with complicated geologic formations where reliable data are lacking. This paper focuses on understanding the hydrogeological characteristics of the different aquifers using an integrated approach. The methods applied are hydrogeological surveys together with interpretation of geological, geoelectrical and hydrochemical data. The results reveal six hydrogeological zones (HZs): HZs 1 (igneous and metamorphic rocks), 2 (sandstone and siltstone), 3 (massive, baked and fractured shale), 4 (sand, gravel, silt and clay), 5 (carbonate rocks) and 6 (basic intrusive rocks). Estimates of groundwater reserves indicate that the HZ 1 has the largest reservoir of stored fresh groundwater, estimated at 332,637.00 × 10 6 m 3 , while the highest yield is estimated to be 1085.53 m 3 /d from HZ 4. Groundwater chemistry showed that Na + and Ca 2+ dominated the cations, while Cl − and HCO 3 − dominated the anions. In general, major chemistry of the water is controlled by atmospheric input, weathering of silicate, carbonate minerals and ion exchange. In terms of drinking and irrigation quality, the groundwater showed low values of total dissolved solids, pH, hardness, dissolved oxygen and NO 3 − at few locations, while more than 50% of the samples have excellent quality for irrigation use. However, higher values were recorded in HZ 2, due to occurrence of brackish water.

Hydrogeology Journal, Dec 17, 2004

Photogeological, geoelectrical, and drill-hole data were used to determine the hydrogeological co... more Photogeological, geoelectrical, and drill-hole data were used to determine the hydrogeological conditions of the regolith layer mantling the Precambrian rocks in the northern Obudu plateau of southern Nigeria. The regolith thickness is 3.8–89.5 m (mean 38 m). Water for domestic purposes is extracted by dug wells -1 m/d and for transmissivity, 3.8×10-1 m2/d. The regolith wells have a high specific capacity, 40–270 m3/d/m and a

Journal of Hydrologic Engineering, Nov 1, 2009

... A cation exchange reaction can be represented by Eq. (2) ()where represents an ion exchange s... more ... A cation exchange reaction can be represented by Eq. (2) ()where represents an ion exchange site occupied by either two monovalent or one divalent cation. ... Dumping of crude oil directly into the environment. ... Solid waste dumped into the swamps.

Environmental geology, Sep 1, 2001

A 6-month study spanning the rainy and dry seasons was conducted on Odukpani Junction springs (Ni... more A 6-month study spanning the rainy and dry seasons was conducted on Odukpani Junction springs (Nigeria) to assess the variation in discharge and physico-chemical parameters. The study also evaluated the impact of geology and indiscriminate disposal of wastes on spring water quality. The results indicate a poor correlation between discharge (Q) and amount of rainfall (R). This is attributed to the distance of the meteorological station and the sampled localities, thus eliminating micro rainfall data. However, Q increased with an increase in R. The variation of ions with time was not large; however, concentrations were higher during the rainy season in most cases. Three major chemical facies (Ca±HCO 3 , Ca±SO 4 , K±HCO 3) identi®ed show major relationship with lithology. Multiple regression equations have been developed to predict the total dissolved solids (TDS), electrical conductivity (EC) and discharge (Q). The level of nitrate is high (9±43 mg/l) compared with the World Health Organisation (WHO) limits of 10.0 mg/l. This is attributed to the indiscriminate dumping of domestic, human and animal wastes. Other parameters determined are within the limits acceptable for potable water by the Nigerian Federal Environmental Protection Agency (NFEPA) and WHO.

Environmental Earth Sciences, Dec 16, 2011

Surface water samples were collected at 15 sampling sites in the southeastern Japan Sea along the... more Surface water samples were collected at 15 sampling sites in the southeastern Japan Sea along the Japanese Archipelago for analysis of polycyclic aromatic hydrocarbons (PAHs). Water samples were fractionated by filtration through a glass fiber membrane (pore size 0.5 µm) and analyzed by high-performance liquid chromatography with fluorescence detection. Thirteen PAHs having 3 to 6 rings were found in the dissolved phase (DP) and 12 were found in the particulate phase (PP). The total (DP PP) PAH concentration ranged from 6.83 to 13.81 ng/L with the mean standard deviation (S.D.) concentration of 9.36 1.92 ng/L. The mean S.D. PAH concentration in the DP and PP was 5.99 1.80 and 3.38 0.65 ng/L, respectively. Three-ring PAHs predominated in the DP, while the proportion of 4-ring PAHs was higher in the PP. The mean total PAH concentration in the southeastern Japan Sea was higher than the concentration in the northwestern Japan Sea (8.5 ng/L). The Tsushima Current, which originates from the East China Sea with higher PAH concentration, is considered to be responsible for this higher concentration.

Environmental geology, May 12, 1998

A baseline study involving analyses of surface and subsurface water samples from the Akpabuyo are... more A baseline study involving analyses of surface and subsurface water samples from the Akpabuyo area was carried out in order to assess their suitability for drinking, domestic and agricultural purposes. Study results show that the waters are acidic (3.41^pH^6.28), soft (hardness 2.09-10.68 mg/l as CaCO 3), fresh (conductivity ~1400 ms/cm) and characterised by low sodium adsorption ratio, SAR (0.08-0.59). In addition, the mean values of the major cations (Ca 2c , Mg 2c , Na c , K c) and anions (SO 4 2P , Cl P , HCO 3 P) are all within the World Health Organisation (WHO) standards. Taking all this into consideration (except pH), the waters may be regarded as excellent for drinking, domestic and agricultural purposes. On the basis of regression equations, the major cations (K, Na, Ca, Mg) correlate well with conductivity. Finally, results also show that four chemical facies are delineated. These include Ca-Cl, Na-Cl, Ca-SO 4 and Ca-HCO 3 .

GeoJournal, 2002

Abstract Two documented methods, Contamination index (C d) and the Heavy metal potential index (H... more Abstract Two documented methods, Contamination index (C d) and the Heavy metal potential index (HPI) were evaluated for their suitability for contamination monitoring of surface water in parts of southeastern Nigeria. Results show that despite the significant correlation between the data generated from these indices, the final classification gave two extreme results. Thus a third model (Heavy metal evaluation index, HEI) was developed to accommodate this deficiency. The HEI values show significant correlation with C d and ...

Global Journal of Pure and Applied Sciences, Apr 1, 2001

Engineering Geology, Jul 1, 1996

The Obudu dam is being built across Abeb river in Obudu area of the Cross River State (Nigeria). ... more The Obudu dam is being built across Abeb river in Obudu area of the Cross River State (Nigeria). The earthfill dam will be approximately 18 m high with a crest length of 385 m. The dam site is located within part of the Obudu crystalline basement plateau which is a region of low seismicity. The terrain is smoothly undulating and low lying and was known to be composed of unclassified basement and decomposed bedrock (overburden). The present study was carried out to assess the suitability of the chosen dam axis based on the determination of the nature and geotechnical characteristics of the overburden and bedrock. The investigation included geophysical surveys, bearing capacity tests (cone penetrometer and standard penetration), classification and grain size distribution as well as tests for compaction, consolidation and compressive strength. The results show that the bedrock is heterogeneous, including gneisses sillimanite, biotite and granite types), dolerite, quartzite and pegmatite with an overall moderate strength (about 76.04 MN m-2 average) and fair rock mass rating (RMR). The bedrock along the dam axis is apparently lacking in major fractures which could lead to short circuiting of the future impoundment. The overburden (soil) comprises silt (MH, ML), silty clay (CL) and silty sand (SM) with a combined thickness of about 2-20 m, increasing away from the valley floor towards the shoulders. Generally the overburden is of suitable compressive strength (150-300 KN m-2), low to medium plasticity and swelling potential and low permeability (up to 1.41 × 10-7 ms-1) which would ensure a tight reservoir. The material settlement is expected to be small and slow. Accordingly, excavation of up to 5 m, decreasing towards the valley shoulders has been suggested to expose the recommended bearing medium: fresh/competent bedrock and overburden in the valley floor and flanks, respectively. While a detailed investigation of burrow areas was not part of the present study, a few potential sites in the dam axis and reservoir areas have been suggested based on the evaluation of material properties.

$Research paper thumbnail of Hydrogeochemistry of a fractured aquifer in the Ogoja/Obudu area of SE Nigeria$

Hydrogeology (International Association of Hydrogeologists), Sep 23, 2008

... brine deposits in parts of the SA (Ekwere & Ukpong, 1994; Tijani etal., 1996; Tijani, 200... more ... brine deposits in parts of the SA (Ekwere & Ukpong, 1994; Tijani etal., 1996; Tijani, 2004). Page 407. 396 Applied groundwater studies in Africa Figure 2. Contour map of TDS (mg/l) in groundwater. The BOD varied from 0.02 to 12.4 mg/l and 0.09 to 2.50 mg/l for the BA and SA. ...

Global Journal of Geological Sciences, Oct 13, 2004

Journal of Applied Geophysics, Mar 1, 1997

A combined analysis of lineament length density from radar imagery and surface resistivity data i... more A combined analysis of lineament length density from radar imagery and surface resistivity data is used to assess the hydrogeological conditions in the Oban massif, Nigeria. The results show that the data guided the qualitative and quantitative estimation of some aquifer parameters. These include resistivity of the water bearing formations (280-740 R m), thickness (5-140 m), limited hydraulic conductivity (8.53-13.18 m/day) and transmissivity (410.65-725.88 m*/day) data. In addition, the lineament length density for the area ranged between less than 0.2 to slightly more than 0.4. Site evaluation for the location of productive boreholes/wells using a groundwater potential index (GWPI) indicates that areas with a GWPI of greater than 35 are consistent with relatively high yield.

$Research paper thumbnail of Hydrogeologic and hydrochemical framework of the shallow regolith aquifer, southern Oban massif (Nigeria) Cadre hydrogѐologique et hydrogѐochimique d'un aqufѐre de socle fracturѐ altѐrѐ, massif du sud de l'Oban (Nigѐria)$

Geoelectrical and hydrogeological data were used to delineate and characterize the regolith aquif... more Geoelectrical and hydrogeological data were used to delineate and characterize the regolith aquifers in a hardrock area (Oban massif, Nigeria). Groundwater chemistry in the area is controlled by silicate weathering and ion exchange. The water in the area is good for domestic and irrigation applications. The study also includes management issues for the area.

Bulletin of Engineering Geology and the Environment, Apr 1, 1990

The point toad testing machine has been used to establish certain strength relationships obtained... more The point toad testing machine has been used to establish certain strength relationships obtained from the results of tests carried out on irregular lump specimens of some Nigerian limestones. The parameters used in the derivations of the relationships include the point load strength index (Is), shape factor (L/D), specimen thickness and the reduction ratio. The methods of rock classification by Deere and Miller and that proposed by Turk and Dearman have been slightly modified for the purpose of rock classification in the field Based on the intact strength and Rock Mass Rating, the rock mass quality of some limestones from Southern Nigeria have been estimated. R~sume L'essai de rrsistance au fendage sous charge ponctuelle a et6 utilis6 pour tester la rrsistance d'echantillons irreguliers de calcaires nigerians. Les param~tres utilis~s incluent l'indice de resistance au fendage sous charge ponctuelle Is, le coefficient de forme (L/D) 1'rpaisseur de l'echantillon et le coefficient de rrduction. Pour la classification des roches sur le terrain, les mrthodes proposees par Deere et Miller et celles proposres par Turk et Dearman ont 6te 16g~rement modifires..

Journal de physique, May 1, 2003

Groundwater samples from 33 locations within the Coastal Plain Sands aquifer of Calabar (Nigeria)... more Groundwater samples from 33 locations within the Coastal Plain Sands aquifer of Calabar (Nigeria) were collected and analysed for 43 trace elements by means of ICP-MS. The aim of this study is to determine the natural background levels of trace elements as a guide for future pollution monitoring of the aquifer. Secondly, this article focuses on the pollution vulnerability of the coastal plain sand aquifer. Statistical methods have been used to determine the source(s) of these elements. Results show that the area is characterised by four types of groundwater, including: Na-HCO 3 , Na-HCO 3-Cl, Na-Cl and Ca-Na-HCO 3-Cl. Secondly, all the elements considered are below normal averages. In addition, the Spearman correlation shows significant correlation especially among the lanthanide group of elements (p<0.0001). Factors analyses indicate mainly two groups of elements. The first group being due to the natural geochemical process (weathering/leaching of the basement lithology; characteristics of the elements) and the second is due to tidal flushing of the estuary. This indicates that the source of the trace element in the aquifer is due to a geogenic process and not anthropogenic. Thus, the present data set will serve as a reference source for pollution monitoring in the area.

$Research paper thumbnail of Investigation of hydrogeological conditions of a fractured shale aquifer in Yala Area (SE Nigeria) characterized by saline groundwater$

Applied Water Science, Jul 5, 2022

Geological, hydrogeological and geophysical investigations were carried out in Yala Area (SE Nige... more Geological, hydrogeological and geophysical investigations were carried out in Yala Area (SE Nigeria) to delineate potential zones for future groundwater development. The area is underlain by Turonian fractured shale rock intruded by basaltic rocks and saline water. High lineament density (> 30 km −1) recorded in the north suggest high permeable zone, compared with low lineament density (< 10 km −1) in the south and east. Geophysical results reveal four types of aquifers: an upper weathered, fractured shale aquifer with mean resistivity and thickness in the range 27-40 Ω m and 20-28 m and a lower fractured shale aquifer with mean resistivity in the range 28.5 to 36.0 Ω m and unresolved thickness; fractured saline shale aquifer with mean resistivity and thickness of 21 Ω m and 50 m; fractured silty shale aquifer with mean resistivity and thickness of 54.4 Ω m and 10 m and basaltic intrusive fractured shale aquifer with mean resistivity and thickness of 135.6 Ω m and 6 m. A broad range of aquifer parameters were obtained from resistivity data and pumping test. Groundwater quality on the mean indicated alkaline and good fresh water for drinking and irrigation use with minor level of salinization. Concentration of dissolved ions in the area are enhanced through weathering and ion exchange. On the basis of these data, the potential zones for groundwater harnessing have been delineated in Yala Area.

Environmental Nanotechnology, Monitoring and Management, May 1, 2015

In the present investigation, the concentration of heavy metals (As, Ba, Fe, Hg, Mn, Ni, Pb, Zn) ... more In the present investigation, the concentration of heavy metals (As, Ba, Fe, Hg, Mn, Ni, Pb, Zn) in pond and stream water samples near abandoned barite mines have been studied. The main objective of study was to appraise the degree of contamination and human risk assessment due to barite mining. Results showed that the average concentrations of Fe, Hg and Pb were above the required standard. This indicates anthropogenic inputs from barite mining activities. The mean concentrations of Ba, Hg, Mn, Ni, Pb and Zn were higher in pond water compared to stream water. Contamination index and Nemerow pollution index indicated contamination at some mine sites, while human health risk assessment indicated unacceptable risk (hazard index (HI) values > 1) for non-carcinogenic adverse health effect. The cancer risk of being exposed to Arsenic by drinking water from these sources did not exceed the acceptable risk of 1:10,000 for regulatory purposes.

International Journal of Energy and Water Resources

Groundwater chemistry and quality in poorly organized inland and coastal towns, southern Nigeria ... more Groundwater chemistry and quality in poorly organized inland and coastal towns, southern Nigeria were investigated. The aim was to study the hydrochemical regime and evaluate the present quality status including human health risk. Hence, seventy- two groundwater samples were collected during wet and dry seasons and analyzed for physicochemical, heavy metals and microbiological parameters and heavy metals using standard methods. The data showed that pH (3.3–7.9), dissolved oxygen, DO (0.5–14.0 mg/L), iron (0.0–7.7 mg/L), manganese (0.0–0.07 mg/L), total heterotrophic bacteria, THB (1–1851 cfu/ml) and total coliform, TC (0.78–75 cfu per 100 ml) in most of the samples exceeded the WHO permissible limits. Bivariate plots and multivariate statistics showed the main hydrochemical process in the area are rock predominance source, silicate weathering and ion exchange. Moreover, seawater influence predominates in the coastal town, while anthropogenic activity predominates in the inland town. In terms of the drinking water quality, groundwater pollution index (GWPI) classified the pollution level of groundwater as insignificant to very high. However, the groundwater samples are suitable for irrigation application. The non-carcinogenic hazard index (HI) for adults in the dry (1.65–62.23 mg/kg/day) and wet (1.02–54.54 mg/ kg/day) seasons, and for children during the dry (2.24–84.14 mg/kg/day) and wet (1.38–73.73 mg/kg/day) seasons indicated children are susceptible to contaminated groundwater relative to the adults through oral ingestion pathway. As recommendation, groundwater abstraction points should be sited away from waste dump sites, while the dump sites should be properly designed and regularly maintained for protection and sustainability of the resource.

Waterborne diseases are major public health concerns worldwide, not only for the morbidity and mo... more Waterborne diseases are major public health concerns worldwide, not only for the morbidity and mortality they cause, but also for the huge cost of their prevention and treatment. These diseases are directly related to environmental deterioration and pollution, to which water is easily vulnerable. Assessment and water quality monitoring for microbial indicators in domestic water sources are key factors in preventing these health concerns. This study investigated the microbial indicators in groundwater around a major municipal waste dumpsite in Calabar metropolis in southeastern Nigeria. Twenty-nine (29) groundwater and seven (7) surface water samples were collected around the dumpsite across wet and dry seasons. The samples were analyzed for some indicator bacteria. The results show that the average counts for total bacteria were 5155 Cfu/100ml, total coliform bacteria 76 Cfu/100ml, total salmonella/shigella 56 Cfu/100ml, and total feacal coliform 53 Cfu/100ml in the dry season. In t...