Dr. OYEM HECTOR HENRY
Publication Title Effects of Chemicals and Plastics on the Environment: A Review
Publication Type journal
Publisher Faculty of Computing, University of Delta, Agbor.
Paper Link https://focjournal.unidel.edu.ng/1
Publication Authors Omoruyi, C.I., Oyem, I.M., Oyem, H. H. & Obukohwo I.
Year Published 2004-05-01
Abstract The United Nations’ Sustainable Development Goals (SDGs) of the human population states that good health
and well-being as well as building sustainable cities and communities are essential aspects of man’s
survival here on earth. This paper attempts to review the effects of chemicals, and plastics in our
contemporary environment and the innovative solutions for their safe disposal. Indiscriminate use of
chemicals, dumping of untreated domestic and industrial wastes in landfills and water bodies, burning of
refuse all contribute to the problem. It brings to focus the various means by which these pollutants get into
our environment, even unknowingly and ways by which this environmental menace can be minimized. Their
presence in our environment, particularly in the developing and under developed world has over the years
become a ticking time bomb with recourse to human health. Many debilitating human conditions such as
cancers and neurological disorders have been traced to the effects of these pollutants. Public enlightenment
on the dangers of these pollutants amongst others is advocated in this work.
Publication Title Borates-stabilized silver nanoclusters: Post-synthesis ligand exchange reaction with cysteine
Publication Type journal
Publisher BIU Journal of Basic and Applied Sciences
Publication Authors Oyem, H. H. and Oyem, I. M
Year Published 2024-09-15
Abstract The lability of the inorganic capping ligands on silver nanoclusters (Ag NCs) formed by the microemulsion method was studied in an exchange reaction with cysteine amino acid in aqueous conditions. The essence was to study the feasibility of this exchange reaction in vivo systems with similar biomolecules especially in the field of medicine and drug delivery systems mimicking antigens–antibody reactions in immunology and immunochemistry. Ag NCs were synthesized in microemulsion droplets. Transmission electron microscope (TEM) shows the formation of these Ag nanocrystals on a holey carbon grid. The crystals were approximately 2 nm in average size, generally spherical and monodispersed. Fourier transform infrared spectroscopy (FT-IR) was used to monitor the reaction by observing the disappearance and significant changes in the vibrational frequencies between the inorganic ligand-stabilized Ag NCs which served as the control, and the new Ag(cysteine) complex. The FT-IR result confirmed the formation of the Ag(cysteine) molecule with the binding site seemingly on the nitrogen atom of the amine group of the cysteine molecule. The resulting new compound was considered to be a zwitterion with a carboxylate ion end group which is prone to switching into a resonance hybrid structure with the delocalization of the electron charge of the carboxylate group. Electrospray ionization mass spectrometer (ESI-MS) data confirmed the molecular mass and formula of the new Ag(cysteine) complex and the successful ligand exchange reaction.
Publication Title Barium, Calcium and Sodium, Cyanide, Phosphate and Sulphate Contents of Groundwater in Some Ika Communities of Delta State, Nigeria
Publication Type journal
Publisher Journal of Geoscience and Environment Protection
Paper Link http://www.scirp.org/journal/gep
Publication Authors Hector H. Oyem, Ifeanyi M. Oyem, Esther N. Obiwulu
Year Published 2017-08-03
Abstract Barium, calcium, sodium, cyanide, phosphate and sulphate and contents of
groundwater in Boji-Boji (BB) area and suburbs of Ika land, Delta State, Nigeria
were studied. Groundwater is the predominant source of water for inhabitants
of these communities without any form of treatment. 55 borehole water
sites spread within these five sample sub-areas. The metal ions were analyzed
using Solar Unicam flame Atomic Absorption Spectrophotometer. Sulphate,
phosphate, and cyanide contents were determined by colorimetric method.
Results indicate the presence of sodium, calcium, sulphate, and phosphate.
However, barium and cyanide were below detection limit. Secondly, there was
a relatively higher proportion of calcium and sulphate than sodium and
phosphate in its aquifer. Thirdly, a mean ratio value of 0.018 and 0.158 was
observed for the ratios of Na+/Ca2+ and 3 2
4 4 PO ? / SO ? respectively. Fourthly,
sodium showed good correlation with all the other parameters. Finally, nearly
all the studied parameters have concentrations below the maximum contaminant
levels of the World Health Organization (WHO), invariably inferring
that the water is wholesome with respect to the analytes. However, concern
still remains from a health point of view on the sodium concentrations in
many sample areas.
Publication Title Silver nanoclusters prepared in water-in-oil emulsions
Publication Type journal
Publisher IOP Publishers
Paper Link https://doi.org/10.1088/2632-959X/acb83a
Publication Authors Hector H Oyem , Andrew Houlton and Benjamin R. Horrocks
Year Published 2023-02-15
Abstract Stable silver clusters can be prepared by a simple electroless reduction reaction taking place in waterin-
oil emulsions. An emulsion containing AgNO3 in the water droplets was mixed with a similar
emulsion containing aqueous NaBH4 droplets. The droplet diameter, based on Rayleigh scattering,
was 41 nmand the mean number of Ag+ ions in each droplet varied from 2.0 to 21.7 as the
concentration increased from 90 ?Mto 1mMAgNO3. The low number of Ag+ ions in each droplet
inhibits the growth of large nanoparticles and these emulsions do not show the large plasmon band
observed for Ag nanoparticles obtained by the analogous reaction in bulk solution at the same Ag+
concentrations. Atomic force microscopy provides evidence of small Ag nanoclusters and a much
lower number of larger nanoparticles. Electrospray mass spectrometry suggests that the clusters are
mainly Ag4 species coordinated to water andBH4
?. The Ag nanocluster-containing emulsions are
fluorescent and show an emission band with a peak wavelength of 427 nmand a Stokes shift of 81 nm
from the first peak at 346 nmin the excitation spectrum. The intensity of fluorescence decreased as the
[Ag(I)] increased and our most fluorescent samples were prepared from 90 ?MAgNO3 because at
higher concentrations more Ag nanoparticles are formed. DFT calculations on Agn clusters indicated
that Ag4 species favour a planar rhombic geometry even in the presence of coordinating water
molecules orBH4
?. However calculations of vertical excitation energies for Ag4 species do not match
the experimental excitation spectra and this suggests the fluorescence arises from bright AgNCs of
different nuclearity present at lower abundance in the mixture of species produced by the emulsion
reaction. Calculated excitation energies for Ag6 give the best fit to the available data.
Publication Title Temperature, pH, Electrical Conductivity, Total Dissolved Solids and Chemical Oxygen Demand of Groundwater
Publication Type journal
Publisher Academic Journals Inc.
Publication Authors Oyem, H. H., Oyem, I. M., and Ezeweali, D.
Year Published 2014-02-01
Abstract Temperature, pH, conductivity, total dissolved solids and chemical oxygen demand in ground water of Agbor/Owa town and immediate suburbs were studied. Groundwater is the predominant source of water by inhabitants of these communities without any treatment. However, the quality of this water source is not immediately known; therefore, there is the question of its safety.
Temperature readings were taken on site using mercury in glass thermometer, pH and conductance readings of the samples were quickly determined by Corning pH meter model 430, and DDS 307 conductivity meter, TDS and COD by APHA standard methods respectively.
Analyses reveal that temperature, pH, conductivity, and TDS range of 27.0 – 28.1°C, pH was 6.10 – 6.97, conductivity 8.25 – 14.46 µS/cm, TDS 4.13 – 7.22 mg/L, and COD 46.80 – 93.60 mg/L. Correlational matrix showed temp. correlated very positively with EC and TDS, and to a lesser extent with COD. Other positive correlates were between: EC with Temp & TDS; TDS also showed very strong correlation with Temp & EC. The mean values recorded for all studied parameters were 27.7°C, 6.81, 11.08 µS/cm, 5.53mg/L, and 62.72 mg/L for temperature, pH, EC, TDS, and COD respectively. These suggest that the groundwater is of rather good quality with values quite below and within the guideline values of WHO, USEPA, and Nigerian water safety standards.
Publication Title Monitoring the Free Fatty Acid Level of Crude Palm Oil Stored under Light of Different Wavelengths
Publication Type journal
Publisher Academic Journals Inc.
Publication Authors Oyem, H. Henry
Year Published 2011-08-01
Abstract The effect of light of different colours (wavelength) on the Free Fatty Acid (FFA) value of stored crude palm oil is hereby reported. Equal portions of the palm oil samples were stored in an environment of red, blue and green lights, respectively for a period of 21 days. Aliquots were taken from each of these samples at two days interval for analysis. And the FFA values obtained plotted against the number of days of storage. Results obtained indicate that the FFA values of the oil increased with storage time. Also and more revealing is the fact that the FFA values of the samples did not follow any established order, especially as related to the spectrum of light.
Publication Title Microbial and Physicochemical Qualities of Septic Tank Wastewater: An Evaluation.
Publication Type journal
Publisher East African Journal of Health and Science
Paper Link eajhs.eanso.org
Publication Authors Ifeanyi Mirian Oyem, Hector Henry Oyem & Emmanuel Esosa Imarhiagbe,
Year Published 2021-11-10
Abstract The physicochemical and microbial qualities of septic tank effluent samples
from households within the study area were evaluated. Three replicate
samples from Locations A, B, and C representing Agbor, Benin City, and
Sapele regions of Delta and Edo States, Nigeria were collected from both
the inlet tank (raw sewage) and the outlet chamber (semi-treated sewage)
for physicochemical and microbiological analyses using standard methods.
Results of the physicochemical analyses showed that pH values ranged
from 6.5 – 7.7 across locations and in both the raw and semi-treated
samples. Electrical conductivity (EC), Total suspended solid (TSS) and
BOD was significantly higher (p>0.05) in the raw sewage (RS) than in the
semi-treated (SS), while DO was higher (p>0.05) in the SS in all three
locations sampled. Microbial analysis shows that total heterotrophic
bacteria (THB) was highest in the RS in two locations. Microbial isolates
from wastewater samples included Staphylococcus aureus, Proteus
mirabilis, Escherichia coli, Pseudomonas aeruginosa, and Aspergillus
niger. DO was low at an average of 3.20 and 3.73 mg/L in both chambers
of the septic tank. Average BOD5 of 59.4 and 42.8 mg/L and COD average
of 206.8 and 153.2 mg/L were reported for the RS and SS chambers. 0.3
was the value of the ratio of BOD5/COD for the RS and SS in the study.
This infers that biodegradation was slow and inefficient in the septic tank
system, and that modification of the design is recommended to increase
retention time in the RS chamber
Publication Title Solar energy revolution and Energy Crisis in Nigeria.
Publication Type journal
Publisher The Nigerian Journal of Energy and Environmental Economics, 1(1): 52-60.
Publication Authors Oyem, H. H., Obiwulu, E. N. O., and Oyem, I. M.
Year Published 2008-08-08
Abstract This paper examined solar energy and its possible use as an alternative source of energy in
contemporary Nigeria. It looked at the sun as the source of solar energy. The inherent nuclear reaction
that goes on in the core of the sun was briefly discussed. A case for the availability and generation of
solar energy was also made. The peculiarity of Nigeria’s geographic location vis-à-vis the availability of
steady solar radiation was considered. An incisive interest was given to the impact of the energy crisis
on small and medium-scale enterprises (SMEs), a major driving force of the economies of many nations.
The effort was also made to look at the solar energy revolution and the issue of alternative energy
supply. Benefits of solar energy technology as a tool for kick-starting the economy and ameliorating the
effects of global oil politics cum prices, and dwindling oil supplies.
Publication Title Comparative Analysis of the Storage Chemistry of Groundnut and Palm oil.
Publication Type journal
Publisher Journal of the Chemical Society of Nigeria
Paper Link https://doi.org/10.46602/jcsn.v49i3.979
Publication Authors 1. Oyem, H. H. and Oyem, I. M.
Year Published 2024-06-30
Abstract Storage chemistry of palm oil and groundnut oil samples were studied for their quality over the course of storage time and their impact on quality and health. Palm oil and groundnut oil samples were subjected to different moisture contents (water concentration) for some time. The acid values (AVs), free fatty acid (FFA) values, peroxide (P.O) vales, and iodine values (IVs) were determined using standard methods of the American Society of Oil Chemistry monitored during this period. Results indicate that AVs, FFA, and IVs increase with moisture content. Secondly, the AVs, FFA, and IVs of palm oil are higher than those of groundnut oil. Thirdly, the AVs, FFA, and IVs are directly dependent on the moisture content of the oils and increase correspondingly with an increase in water content. Generally, palm oil was found to be more susceptible to spoilage during storage and more affected by lipid oxidation. It is recommended that a threshold limit aw of ? 0.21 for moisture content be the standard for stored edible oils. Consumers should avoid storing and eating palm oil stored for a long period.
Publication Title Effect of Water Activity on the free fatty acid value of Crude Palm oil during storage
Publication Type journal
Publisher International Journal of Tropical Agriculture and Food Systems, 4(3): 278 – 280.
Publication Authors H. H. Oyem
Year Published 2010-10-10
Abstract The influence of water activity on the storage quality of palm oil was examined. Equal portions of palm oil were put in three different water activity media for a period of 21 days at room temperature. A fourth sample representing the control was placed by the window in the laboratory. Aliquots were withdrawn at an interval of two days and the free fatty acid (FFA) value was determined in duplicates using standard methods of fats and oil analysis. Results showed that the rate of hydrolysis generally increased with an increase in aw values. In addition, the FFA values of the oil steadily increased with storage time.
Publication Title The Effect of Water activity on the Peroxide value of stored crude palm oil.
Publication Type journal
Publisher International Journal of Chemistry,.
Publication Authors Oyem, H. H.
Year Published 2010-10-10
Abstract The role of water activity (aw) on the peroxide value of stored crude palm oil is presented. Portions of the palm oil samples were stored in three different desiccators with varying AW values of 0.23, 0.33, and 0.75 respectively for a period of 21 days at ambient temperature. Another sample was left by the window outside the desiccators as a control. From these samples, aliquots were taken for P.O. determination every other day in duplicates at a 95 % confidence limit. Results indicate that P.O. values though generally increased with time but that the rate of autoxidation decreased with increasing aw levels.
Publication Title Spatial Analysis of Heavy metals in septic tank sewage: A material balance approach.
Publication Type journal
Publisher Caliphate Journal of Science and Technology; Caliphate Journal of Science and Technology
Paper Link https://dx.doi.org/10.4314/cajost.v5i2.14.
Publication Authors Oyem, H. H. and Oyem, I. M.
Year Published 2023-04-19
Abstract Heavy metals get to humans through food, water, air, and industrial activities.
They arrive at septic tanks through the excretory products of man and
undergo anaerobic bioremediation. Effluent and sludge sewage in both
chambers of the tank contains various amounts of trace metals. The research
analyses the spatial distribution of heavy metals in the effluent and sludge
components of the septic tank during bioremediation. Effluent and sludge
samples were randomly collected from three study locations in southern
Nigeria, and composite samples were made for each of these study locations.
Nine trace metals were analysed using standard methods by the American
Public Health Association (APHA) for water and wastewater examination. Fe,
Mn, Zn, Cu, and Cr were the most abundant. Effluent heavy metals
concentrations were higher in the inlet chamber. There were strong positive
correlation (r = 0.90, 0.99, and 0.99) between the effluent and sludge
samples. P-values obtained from the ANOVA at a 0.05 significance level
confirmed the correlation values. Multivariate charts and regression analysis
gave R2
-values in the range of 0.3045 – 0.3724 in the study with a mean value
of 0.33. In conclusion, the effluent and sludge samples were strongly
correlated and all the metal types analysed were also present in the sludge in
similar proportions. The sludge contained significant levels of trace metals
with dire implications for the environment.
Publication Title Molecular characterisation of bacteria strains of septic tank sewage samples from related sites in Delta and Edo States of Nigeria using 16S rRNA denaturing gradient gel electrophoresis (DGGE)
Publication Type journal
Publisher Academic journals
Paper Link http://www.academicjournals.org/AJEST
Publication Authors Oyem, I. M.1 * and Oyem, H. H. and Atuanya, E. I.
Year Published 2020-04-30
Abstract The molecular characterization of raw septic tank sewage in the region under study was evaluated
using 16S rRNA denaturing gradient gel electrophoresis (DGGE). Raw effluent samples from three
septic tanks in the Delta and Edo States region of Nigeria was collected between November 2018 and
January 2019 for testing. A composite sample was formed from the three samples collected. The raw
sewage sample was sequenced for genomic DNA using Norgen DNA extraction kit to determine the
microorganisms present in raw sewage sample. Gene sequence analysis revealed the presence of
Methanococcus methanococcus 288171278, Deferribacteres bacterium 291088137, Flavobacteria
bacterium 308271278, Bacteroides dorei 671713918, Clostridium difficile 115249003, Kuenenia
stuttgartiensis 91203347, Methanosarcina bankeri 827396966, Methanococcus maripaludis 4505076 and
Methanobacterium formicicum 693274837, and Desulfitobacterium dichloroeliminans 430782295. The
phylogram of the different isolates shows that methane producing bacteria were 7 out of the 13 bacteria
isolated; representing 53.8% of the total species occurrence in the sample.
Publication Title Heavy Metals pH-Mediated Microbial-Remediation in Septic Tank Effluents
Publication Type journal
Publisher European Centre for Research Training and Development
Paper Link www.eajournals.org
Publication Authors Hector Henry Oyem and Ifeanyi Mirian Oyem
Year Published 2022-03-15
Abstract This paper studied the role of pH in the microbial remediation of heavy metals
in septic tank effluents from three sample locations in the south-south region of Nigeria. The
region is famous for agriculture, industrial and auto-mechanic activities leading to the uptake
and bioaccumulation of heavy metal contaminants through the food chain. Heavy metals
concentrations, pH, and microbial analysis in effluent samples, were determined using
standard methods. The material balance approach (see Supplementary Information) was
adopted to account for analytes remediation and speciation in the system according to the Law
of Conservation of Mass (Matter). The pH of the study area ranged from 6.5 to 7.7. The pH
conditions in location A was alkaline, while locations B and C were slightly acidic. Iron was
the most abundant metal with a concentration range of 0.01 to 0 9.41 mg/L. The order of
magnitude of heavy metals in the septic tanks in the study area is Fe > Pb > Cr > Zn > Cd >
Mn > Cu > Ni > V. Metal removal mechanism followed the metal-microbes adsorption and
precipitation processes dictated by the in situ pH of the system. Total heterotrophic bacteria
were the most dominant in the septic tanks. A removal coefficient of ? 0.33 (i.e, 0 < x ? 0.33
(where x ? 0)) was considered optimum. The percentage metal ion removal was inversely
proportional to the removal coefficient and vice versa. Acidic conditions favoured the
sequestration of more heavy metals from the effluent and the attainment of the 67.0 % and 0.33
removal efficiency thresholds. Finally, the heavy metals concentrations were indicative of
bioaccumulation. Secondly, the pH conditions are not ideal enough to cause the efficient
remediation of heavy metals from effluents. Further treatment of the sludge component before
disposal is seriously advocated.
Publication Title Binding of Ag(I) ions to DNA nucleobases: A mechanistic study
Publication Type journal
Publisher University of Nigeria, Nsukka
Publication Authors Hector H. Oyem
Year Published 2022-12-02
Abstract A mechanistic approach to the reaction between Ag(1) ions and DNA nucleobases was
proposed in this study with 1H, and 31P NMR analytical tools to back up the mechanisms. The
proposed reaction mechanisms is based on the stability of the resulting products and the
lowering of the free energy occasioned by the delocalization of electrons and the extent and
spread of charge(s) on the nucleobases upon Ag(1) addition. Solutions of DNA nucleobases
were treated with silver nitrate solution in a ratio of 1:2 in aqueous medium and reduced by
equivalent portions of sodium borohydride. Similarly, for the NMR analyses, the same protocol
was repeated using deuterium oxide solution as the reaction medium. Spectra obtained were
used to support the proposed reaction mechanisms for the binding characteristics of Ag(1) ions
on DNA bases. Results support the assumption that Ag(1) ions bonded to DNA bases at the
AN3 AN7, CN3, GN7 positions with the electrophilic attack centred on the lone pair electrons
on these nitrogen atoms. Consequently, the resulting electron delocalization and spread of
charge(s) caused significant deshielding of the AH8, CH6, GH8 and the CH1’ (ribose sugar)
protons. The carbonyl oxygen atom was not the favoured binding site of Ag(1) ions as was
illustrated with thymine molecule; as 1H NMR spectra did not support this assumption.
Similarly, 31P NMR spectra showed that Ag(1) ions did not bind with the nucleobases at the
phosphate oxygen atoms. Whereas, prominent emission bands were observed after reduction
of the Ag+
-DNA nucleobases with NaBH4, weak emission band was recorded after the
reduction of Ag(I)-thymine complex. It was concluded that Ag(I) ions bonded with thymine,
albeit weakly, because the TN3 is saturated. In all, delocalization of electrons and spread of
charges led to a more profound deshielding effect on cytosine.
Publication Title Plasmoelectronic-Based Ultrasensitive Assay of Tumor Suppressor microRNAs Directly in Patient Plasma: Design of Highly Specific Early Cancer Diagnostic Technology
Publication Type journal
Publisher ACS Publications
Paper Link DOI: 10.1021/acs.analchem.8b03768
Publication Authors Thakshila Liyanage, Adrianna N. Masterson, Hector H. Oyem, Hristos Kaimakliotis, Hang Nguyen, and Rajesh Sardar
Year Published 2019-01-04
Abstract It is becoming understood that microRNAs hold great
promise for noninvasive liquid biopsies for screening for different types of
cancer, but current state-of-the-art RT-PCR and microarray techniques
have sensitivity limitations that currently restrict their use. Herein, we
report a new transduction mechanism involving delocalization of photoexcited conduction electrons wave function of gold triangular nanoprism
(Au TNP) in the presence of -ssDNA/microRNA duplexes. This
plasmoelectronic effect increases the electronic dimension of Au TNPs
and substantially affects their localized surface plasmon resonance (LSPR)
properties that together allow us to achieve a sensitivity for microRNA
assay as low as 140 zeptomolar concentrations for our nanoplasmonic
sensors. We show that the position of a single base-pair mismatch in the
-ssDNA/microRNA duplex dramatically alters the LSPR properties and
detection sensitivity. The unprecedentedly high sensitivity of nanoplasmonic sensors has allowed us to assay four different
microRNAs (microRNA-10b, -182, -143, and -145) from bladder cancer patient plasma (50 ?L/sample). For the first time, we
demonstrate the utility of a label-free, nanoplasmonic sensor in quantification of tumor suppressor microRNAs, the level of
tumor suppressor microRNAs goes down in a cancer patient as compared to normal healthy individuals, in metastatic and
nonmetastatic bladder cancer patient plasma. Our statistical analysis of patient samples unequivocally suggests that the tumor
suppressor microRNAs are more specific biomarkers (p-value of <0.0001) than oncogenic microRNAs for differentiation
between metastatic and nonmetastatic bladder cancer, and nonmetastatic cancer from healthy individuals. This work
demonstrating the electron wave functions delocalization dependent ultrasensitive LSPR properties of noble metal nanoparticles
has a great potential for fabrication of miniaturized and extremely powerful sensors to investigate microRNA properties in other
cancers (for example breast, lung, and pancreatic) through liquid biopsy
Publication Title COMPARING STUDENTS PERFORMANCE IN CHEMISTRY THEORY AND PRACTICAL PAPERS: IMPLICATION FOR TECHNOLOGICAL DEVELOPMENT
Publication Type journal
Publisher African Journal of Educational Research and Administration
Publication Authors Oyem, Hector Henry
Year Published 2012-11-12
Abstract This paper investigated the performance of students in practical examination and
compared them with performances in theory. Science students from the school of sciences
in the College of Education, Agbor make up the sample population. From these, three
departments of Biology/Chemistry, Physics/Chemistry, and Integrated Science double
major were selected. The research subjects were pooled from these subject combinations
according to class size. Academic Board verified results for three successive academic
sessions of 2004/2005, 2005/2006 and 2006/2007 constitute the study data. Two
hypotheses were postulated. The students’t-test was the statistical method of analysis.
Findings from the analysis were displayed in tables and figures in the form of bar charts.
Results obtained indicate a higher performance in practical papers especially in years 1
and 2. This seeming pattern changed abruptly in year 3 (final year) with students scoring
higher in theory than in practical papers. Values of t-observed were 99 per cent of the
times lower than the t-critical.
Publication Title Iron, manganese, cadmium, chromium, zinc and arsenic groundwater contents of Agbor and Owa communities of Nigeria
Publication Type journal
Publisher Springer Nature
Paper Link DOI 10.1186/s40064-015-0867-0
Publication Authors Hector Henry Oyem, Ifeanyi Mirian Oyem and Amii Isaac Usese
Year Published 2015-03-15
Abstract Iron, manganese, zinc, cadmium, and chromium heavy metals and arsenic contents of groundwater in area and
surrounding environment, of Ika land in the Delta state, Nigeria was studied. Groundwater without any treatment is
the predominant source of drinking water by inhabitants of these communities. However, the quality of this water
source is not immediately known, raising questions of its safety.
Results of a regional composite of groundwater obtained, shows high iron (27%) and zinc (36%) contents in Boji-Boji
Agbor area, manganese (31%) was highest in Boji-Boji Owa. Alihame recorded the lowest value of zinc (8%), while
manganese was lowest in Agbor Obi area (12%). Arsenic, cadmium, and chromium were below detection limit in
all the sample sites. Correlational matrix analysis revealed no significant relationships between metal types studied.
Analyses of chronic daily dose intake (CDI), and hazard index were all very low. A hazard index of 0.01 was obtained.
One-way ANOVA show significant statistical difference in the mean concentrations of the heavy metals for the different
sample sites, which indicate that different sites contribute differently to the mean concentrations of the groundwater in
the study area.
Four conclusions are drawn from this study. Indications are that the heavy metals present in the Nigerian aquifer are
very much below the maximum concentration levels and guideline values of national and WHO standards. Secondly,
there is a heavier load of these metals in the city centre than in the suburbs; with Boji-Boji area Agbor/Owa urban areas
accounting for 27 and 20 percent of load respectively. Thirdly, the below detection limit results for some of the metal
ions and the very low concentrations of those detected are pointers to the absence of industrial activities and mining.
Finally, the groundwater in the study area is considered to be generally safe with respect to the contaminants studied
and results posted for the composite samples. Inhabitants are therefore under no illusion of immediate or remote
health challenges with regards to the heavy metals analyzed. More individual sampling, however, is recommended.
Publication Title Quality assessment of harvested rainwater in Agbor, Delta State.
Publication Type journal
Publisher Journal of Science anf Technology Research.
Publication Authors Akpofure, R., Okokoyo, P., Oyem, H. H., and Ikhifa, G. O.
Year Published 2005-11-10
Abstract Physico-chemical characteristics of harvested rainwater in Agbor, Delta State were studied. A collection of samples was obtained at ten (10) randomly selected harvested rainwater storage facilities. Samples were analyzed for pH, turbidity (NTU), DO (mg/L), TDS (mg/L),NO3- (mg/L), SO42- (mg/L), Fe (mg/L), and Zn (mg/L). Concentrations of TDS (1576-1872 mg/L), No3- (19.30-23.10 mg/L) and turbidity (41-52 NTU) where above WHO permissible limits for safe driking water. The results demonstrated that harvested rainwater requires a treatment technology to improve the quality.
Publication Title Environmental effect of exposing peeled and cut pineapple fruit by fruit vendors.
Publication Type journal
Publisher Nigerian Journal of Food Science and Technology.
Publication Authors H.H Oyem, I.M Oyem, N.S Nwaefiene
Year Published 2010-09-21
Abstract A fairly ripe pine apple fruit was peeled and cut into five portions of approximate sizes, wrapped in transparent plastic films, and exposed for 8 hours in a tray at a height of about six feet from the ground. 30 g portion was taken from the first sample at zero hour (the control) and analyzed for sugar content using spectrophotometer and density bottle methods; and for peroxide value (PO). These were repeated every two hour interval until the 8th hour for the 2nd, 3rd, 4th, and 5th exposed samples respectively. Results indicate that the sugar content decreased with exposure time. The highest sugar concentration was recorded for the zero hours (control _ unexposed sample). A peroxide value of 40 meq/kg was obtained at the zero hour before dropping steadily to 5 meq/kg at the 4th hour (midpoint of exposure time) and then rising suddenly to 150meq/kg at the 8th hour of exposure. The conclusion from the findings suggests that exposure of fruits to the environment affects food quality.
Publication Title An investigation into groundwater contamination in Agbor and Owa communities in Nigeria.
Publication Type journal
Publisher : Sacha & Diamond Publishers, England, UK.
Publication Authors 12. Oyem, I. M., Oyem, H. H., Oyem, M. N., Usese, A. I., Ezenweali, D., and Obiwuli, E. N. O
Year Published 2015-02-15
Abstract Groundwater is the predominant source of water in Ika land without any treatment with questions on its safety. Fifty borehole water sites were sampled and divided into five sample areas. Nitrate contents were determined by colorimetric method and chloride by titration with silver nitrate solution (APHA standard method 4500-Cl-B). From the results obtained, chloride values were consistently low in all the sampled areas. Secondly, very low nitrate values were similarly recorded in the sample areas. Thirdly, a mean value of NO 3-/Cl-ratio of 0.003 was observed, an indication of groundwater geochemical evolution. However, both the chloride and nitrate contents of the groundwater fell very far below international guideline values. Microbial analyses reveal that all but one sampled area posted negative results for the presence of E.coli, Salmonella spp. was not detected. It is obvious that the groundwater quality is wholesome with regard to the parameters here analyzed. However, personal hygiene is advised.
Publication Title Changes in peroxide value of stored crude palm oil at different wavelengths of light
Publication Type journal
Publisher Internat. Jour. of Physical Sciences
Publication Authors Hector H. Oyem
Year Published 2010-07-18
Abstract The effect of light of different colours on the peroxide value (P.O.) of crude stored palm oil is reported. Palm oil samples were stored in three identical compartments of 35 x 50 x 40 cm dimensions under 40 W blue, green, and red electric bulbs for a 21-day period at ambient temperature. A control sample was placed by the wind in the laboratory under the influence of sunlight. Aliquots were taken every two days and the P.O values were determined using standard methods for fat and oils analysis. Results indicate that the P.O values of all the samples generally increased with storage. The samples under the blue and red light had the highest peaks on the graph followed by the sample under the green light environment. It was concluded that all the oil samples interacted with light and that such interactions involved certain (selected) discrete amount of light energy.
Publication Title Interaction of Edible Vegetable oils with Visible Light: Implications for Food Quality
Publication Type journal
Publisher Dutse Journal of Pure and Applied Sciences (DUJOPAS)
Paper Link https://dx.doi.org/10.4314/dujopas.v10i3b.33
Publication Authors Hector Henry Oyem* and Ifeanyi Mirian Oyem
Year Published 2024-11-01
Abstract The practice of exposing edible vegetable oils to light and the effect on food quality was the focus of this study. Palm and groundnut oil were studied under the influence of different wavelengths of light corresponding to red, blue, and green light for about a period of one month during which the acid values, free fatty acid values, peroxide values, and iodine values were monitored. Results indicated that both acid values and free fatty acid values of the two oil types increased directly with light in the order of red > blue > green light respectively. Second, light had barely little effect on the peroxide values of the two oils during the storage period. Third, the light had a weak effect on the iodine values of the two oil types studied. Fourth, groundnut oil was safer for consumption than palm oil after a long period of exposure to light. It was concluded that indiscriminately exposing these oils to light affected their quality as it led to increased hydrolysis of triglycerides. It was recommended that oils should be packaged in amber containers to limit the absorption of incident light.
Publication Title Safe Utilization of Heavy Metals Polluted Soil for Food Production.
Publication Type journal
Publisher Nigerian Journal of Agriculture and Agricultural Technology
Publication Authors Oyem, H. H., and Oyem, I.M.
Year Published 2024-06-29
Abstract The safe utilization of globally decreasing arable land polluted with heavy metals from increasing industrial activities was reviewed. Global industrialization and commercialization has caused soil to be inundated with various deleterious heavy metals with the attendant health implications to the sustainable development of man in the global environment. This paper considered the sources (both anthropogenic and geogenic) of these heavy metals in soil to understand the dynamism of the soil heavy metal pollution. It considers the temperate and tropical soil types and appropriately described the contamination patterns and the relevant soil-specific ways of alleviating and making the limited available land conducive for agriculture. It highlights the equilibrium dynamics between soil (rock) surface, heavy metals lability, soil solution, and the various strategies to sequester the labile heavy metals component of the soil solution which is the cardinal proportion that is bio-available for uptake by plants. It concluded by proffering smart-farming strategies based on the adaption of soil chemistry and soil microbiology principles for farming with particular reference to heavy metals-contaminated soils which can mitigate the accumulation of these heavy metals at toxic levels in the food chain.
Publication Title Nanoparticles Synthesis Protocol: A Case of Syntax and Semantics?
Publication Type journal
Publisher Ambrose Alli University Journal of Physical & Applied Sciences
Publication Authors Oyem, H. H.
Year Published 2024-05-20
Abstract Synthesis of metal nanoparticles (MNPs) with DNA template has been approached in two synthetic
ways by researchers with some uncertainties about the appropriate conventional method to prepare
DNA-templated MNPs. In this exercise effort was made to review these two synthetic approaches and
determine which method produced the better approach in relation to results of this study. MNPs were
prepared by first attaching metal ion in this case Ag (I) ions from silver nitrate (AgNO ) aqueous 3
solution to Calf thymus DNA (Ct-DNA) and then reducing with sodium borohydride (NaBH ) 4
aqueous solution. And another method requires reducing Ag (I) ions with NaBH before adding Ct- 4
DNA. UV-vis results showed that there were no differences in the ABS results of the control (AgNPs)
sample from the sample formed by first reducing the metal ion with the reducing agent before adding
the DNA template labeled as AgNP/Ct-DNA. Secondly, the DLS results show the same similarity
again between the control AgNPs sample and the analyte AgNPs/Ct-DNA. Results were in support of
first attaching the metal ions to DNA molecule before the reduction step. It was concluded that the
synthesis of MNPs with DNA was step-sensitive and therefore an obvious case of syntax and not
semantics.
Publication Title Metal Nanoclusters for Fluorescence Imaging
Publication Type journal
Publisher Benin Journal of Physical Sciences
Paper Link www.bjps.org.ng
Publication Authors Hector H. OYEM
Year Published 2024-07-08
Abstract The importance of metal nanoclusters (MNCs) and their remarkable opto-physical properties as inorganic fluorescent quantum dots for bio-imaging and applications in medical diagnosis were studied. Their significance as good replacements for oftentimes, less-effective organic analogues was demonstrated. Silver and copper nanoclusters were prepared by reducing their metal ions with sodium borohydride in aqueous solutions. Atomic force microscopy results showed that silver and copper nanoclusters with an average size of approximately 1.40 nm were synthesized from their salts. The presence of these MNCs was confirmed by confocal microscopy which also illustrated their luminescent and photostability properties. Fluorescence spectroscopy results showed that these samples possessed emissions at 435 and 617 nm for the AgNCs, and at 636 nm for the CuNCs excited at 315 and 255 nm respectively. Electrospray ionization mass spectrometer confirmed the presence of species with a metal core of Ag4 and Cu7 having a molecular mass of 529 and 559. Cyclic voltammetry data confirmed the presence of Ag (I) ions and Ag (0) in the sample solution. XPS similarly confirmed the elemental presence of these metals. Fluorescent quantum yield was ?70 % which is remarkable for quantum dots. It was recommended that MNCs can present better effects as fluorescent probes for both bio-imaging and medical diagnosis.
Publication Title Adoptive decolorization of dynes in aqueous solution using magnetic sweet potato (Ipomoea batatas L.) peel waste.
Publication Type journal
Publisher RSC Sustainability
Paper Link https://doi.org/10.1039/D35U00410D
Publication Authors Diagboya, P. N., Odagwe, A., Oyem, H. H., Omoruyi, C., and Osabohien, E.
Year Published 2024-03-06
Abstract Valorizing domestic biomass waste for contaminated water treatment may be an effective way to achieve the sustainable development goal of attaining clean water for all. Hence, sweet potato peel (SPP) waste was valorized by magnetizing the pretreated SPP adsorbent to prepare the magnetized adsorbent (MSP) which was employed for methylene blue (MB) sorption. The MSP exhibited enhanced cation exchange capacity (11%) and MB sorption greater than 100% of either of the starting pristine materials. Sorption equilibrium was fast (20 min), and the adsorbent was effective over a wide pH (3–9) and temperature range (15–35 °C). The observed sorption capacity of the MSP for MB was 14.3 mg g?1 and this is better than those of most biomass-based adsorbents reported in the literature. The composite exhibited good reusability with ?70% efficiency after 5 cycles. The MB sorption mechanism was a rather complex process involving electrostatic interaction, multi-layer adsorption, and pore-filling. Notwithstanding the enhanced sorption capacity, the ease of magnetic separation of the MSP adsorbent from water post-adsorption, its stability, and reusability are the major merits of this adsorbent. These facts make the MSP composite an appealing cost-effective choice for treating MB-contaminated water.
Valorizing domestic biomass waste for contaminated water treatment may be an effective way to achieve the sustainable development goal of attaining clean water for all.