Analysis of deforestation pattern in the Niger Delta region of Nigeria

This study examines deforestation in a part of the Niger Delta region of Nigeria between 1987 and 2013 using remote sensing data and geographic information systems. The results indicate an increasing rate of deforestation, an increasing rate of water body loss and a decreasing rate of exposed surface/settlement increase. The results also show that the rate at which cropland/secondary vegetation is increasing is above average while sandbar is increasing below average. The implications of these changes include environmental degradation resulting from loss of biodiversity and loss of forest goods and services. These losses can also affect the social and economic conditions of local people. The study recommends that policies and strategies targeted at slowing down the rate of forest loss and degradation should be pursued.     

Seasonal variation of nitrate-N in surface and ground-waters of South Western Nigeria: a preliminary survey

Two surveys of nitrate-N concentrations in surface and ground water in Ogun and parts of Lagos and Oyo States of south-western Nigeria were undertaken between October 1997 and December 1998, and between July 2000 and May 2001 (covering both dry and rainy seasons). The study was conducted to ascertain the extent of nitrate-N pollution of the surface/ground water in some parts of the three states. Seventy-two water points (33 rivers/streams, 21 wells and 18 boreholes) were sampled three times during each of the two seasons. Nitrate-N was detected in all the river/stream samples analysed with concentrations ranging from 0.5 to 15.3 mg/l and 1.0 to 7.7 mg/l during the rainy and dry seasons, respectively (average value 2.7 and 2.4 mg/l for rainy and dry season, respectively). 98.5% of the rivers/streams sampling points contained nitrate-N in amounts equal to or less than 10 mg/l. 88.1% of wells and 97.2% of boreholes had a nitrate-N content less than 5 mg/l. Nitrate-N concentrations in the sampled wells ranged from 1.4 to 7.4 mg/l and 1.1 to 6.0 mg/l during the rainy and dry seasons, respectively (average value 2.6 and 2.2 mg/l, respectively). The sampled boreholes had a lower nitrate-N concentration ranging from 0.1 to 5.2 mg/l and from below the detection limit to 5.0 mg/l during the rainy and dry seasons, respectively (average value 1.8 and 1.6 mg/l, respectively). Nitrate-N concentrations in boreholes were below detection limit in 22% of the samples. Generally, for most of the sampling points, nitrate-N concentrations were slightly higher during the rainy season compared with the dry season. The present results indicated that nitrate-N concentrations in all the water points (except one) were below the World Health Organization (WHO) maximum acceptable limit in potable waters (10 mg/l). Therefore, contamination of the surface and ground water of the study area is not indicated. This study provides background data against which future changes in nitrate-N concentrations of surface and ground waters in the study area can be measured.     

Distribution of heavy metals in soil and accumulation in plants at an agricultural area of Umudike,Nigeria

This study assessed the distribution of heavy metals in soil and their subsequent accumulation in plants at a site at Umudike, Nigeria, that had been contaminated by agrochemicals. Soil and plant samples were analysed for zinc (Zn), chromium (Cr) and cadmium (Cd). The highest concentrations of Zn (251.50 mg/kg) and Cd (61.33 mg/kg) were obtained at a soil depth of 0–10 cm. The highest concentrations of Zn (16.52 mg/kg), Cd (27.12 mg/kg) and Cr (164.07 mg/kg) were accumulated by Baphia nitida. The levels of Cd, Cr and Zn in soil were 27.97–61.33, 24.97–45.43 and 148.57–251.50 mg/kg, and their concentrations in B. nitida were 16.18–27.13, 97.99–164.07 and 0.10–16.52 mg/kg, respectively. There were significant correlations between Cd and Cr and Cd and Zn in soil, as well as between Cd and Cr in plants. The concentration of Cd in soil reflected a state of pollution relative to Dutch criteria for soil and the FAO/WHO Codex Alimentarius Commission.     

Comparative study of the age and location dependence of some heavy metals in human hair from two Nigerian cities

The concentration of some heavy metals (lead, zinc and copper) were determined in the scalp hair of children (1–15 year) and active adults (16–40 year) in two Nigerian cities. The levels of zinc were found to be higher in children than in the adult population. There was a significant difference (P?=?0.05) between the two age groups. The levels of copper were all within the same range for the two age groups and independent of location. The levels of lead were generally higher in adults than in children. However, there was no significant difference (P?=?0.05) in the average concentrations of lead between the children and adult populations of the two cities. The regression analysis indicated a strong correlation (r?=?0.86) between zinc and copper.     

Evaluation of natural radioactivity in soil, sediment and water samples of Niger Delta (Biseni) flood plain lakes, Nigeria

This paper presents the findings of a baseline study undertaken to evaluate the natural radioactivity levels in soil, sediment and water samples in four flood plain lakes of the Niger Delta using a hyper pure germanium (HPGe) detector. The activity profile of radionuclides shows low activity across the study area. The mean activity level of the natural radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K is 20 ± 3, 20 ± 3 and 180 ± 50 Bq kg⁻¹, respectively. These values are well within values reported elsewhere in the country and in other countries with similar environments. The study also examined some radiation hazard indices. The mean values obtained are, 76 ± 14 Bq kg⁻¹, 30 ± 5.5 ηGy h⁻¹, 37 ± 6.8 μSv y⁻¹, 0.17 and 0.23 for Radium Equivalent Activity (Ra_eq), Absorbed Dose Rates (D), Annual Effective Dose Rates (E_ff Dose), External Hazard Index (H_ex) and Internal Hazard Index (H_in) respectively. All the health hazard indices are well below their recommended limits. The soil and sediments from the study area provide no excessive exposures for inhabitants and can be used as construction materials without posing any significant radiological threat to the population. The water is radiologically safe for domestic and industrial use. The paper recommends further studies to estimate internal and external doses from other suspected radiological sources to the population of the Biseni kingdom.     

Responses to natural and man-made hazards in Borno, Northeast Nigeria

This is a study of the responses of the people of eastern Borno to the twin hazards of drought and of an irrigation project stranded by the recent low level of Lake Chad. The environmental awareness of the people has been much influenced by access to information, particularly radio. There was a perceptual dissonance; drought is discerned as a natural act of God, but lake recession is seen as man-made. There is also a gap between responses perceived as appropriate and actual responses consequent on the constraints imposed by the process of modernization, notably the introduction of the South Chad Irrigation Project (SOP). Traditional response mechanisms involving the norm of reciprocity, the use of community resources, agricultural adaptations and sharing have become relatively insignificant in Borno. These are being replaced by emigration, lake floor cultivation and household diversification     

Physico-chemical indices of breeding sites of Simulium damnosum in the lower Cross River Basin, Nigeria

IntroductionBlackflies (Simulium spp.) act as the vectors ofOnchocerca volvulus, the causative agent of humanonchocerciasis. Blackflies are found mostly in areas with fastflowing water such as rivers and streams, with rocky bedsproviding…     

A review of the effects of gas flaring on the Niger Delta environment

SUMMARY

This paper is a review of studies on the impact of gas flaring on the Niger Delta environment. The Niger Delta region of Nigeria has suffered all forms of pollution and degradation arising from oil and natural gas exploitation. These include a decrease in agricultural yield, depression in flowering and fruiting in Okro and palm trees, deformities in children, liver damage and skin problems, increasing concentrations of airborne pollutants, acidification of soils and rainwater, corrosion of metal roofs and significant increases in concentrations of sulphates, nitrates and dissolved solids, with associated socio-economic problems.

In spite of decree 99, which bans unauthorized flaring, over 75% of the gas produced is still being flared. The paper observes that empirical studies on the impact of gas flaring on the physical, chemical, soil, biological, atmospheric and social environment have not been adequately documented. It concludes that there is urgent need for scientific study and analysis of the effect of gas flaring on the different environmental compartments in the Niger Delta, as this is a necessary ingredient for achieving the dream of sustainable mineral exploitation in the region.     

Genotoxicity and mutagenicity of electronic waste leachates using animal bioassays

Human exposure to electronic waste (e-waste) is increasing, especially in developing nations. This has potential short and chronic adverse health risks. Information is currently scarce on potential genotoxicity of e-waste leachate. In this study, the potential mutagenic and genotoxic effects of leachates from e-waste dumpsites at two electronic markets in Lagos, Nigeria, were investigated. The assays utilized were: bone marrow micronucleus (MN) and chromosome aberration (CA), spermatogonia CA, sperm morphology, and sperm count in mice. Experiments were carried out at concentrations of 1%, 5%, 10%, 25%, and 50% (v/v; leachate: distilled water) of leachate samples. MN analysis showed a concentration-dependent induction of micronucleated polychromatic erythrocytes (MNPCE) across the treatment groups. In the CA tests (bone marrow and spermatogonia), there was concentration-dependent significant reduction in mitotic index and induction of different types of CA. Assessment of sperm shape showed a significant increase in sperm abnormalities with significant decrease in mean sperm count in treated groups. Heavy metals analyzed in the tested samples are believed to contribute significantly to the observed genetic damage. This indicates that e-waste contains potential genotoxic agents; and constitutes a genetic risk in exposed human population.     

Concentrations of selected metals in chicken eggs from commercial farms in Southern Nigeria

This work presents the results of the determination of concentrations of the trace metals Ni, Zn, Mn, Pb, Cd, Cr, Co, Cu, and Fe in eggs from farms in Southern Nigeria. The mean concentrations (µg?g^?1 fresh weight) ranged from 0.6 to 1.2 for Ni, 3.1 to 8.9 for Zn, 0.45 to 0.65 for Mn, 0.4 to 1.2 for Pb, <0.09 to 0.3 for Cr, 0.1 to 0.3 for Cd, 0.26 to 0.34 for Co, 0.9 to 1.2 for Cu and 19.5 to 24.0 for Fe. The concentrations and estimated dietary intakes of these metals were below the respective statutory limits. The Target Hazard Quotient (THQ) values for the individual metals in all zones are less than 1, i.e., within safe levels. The combined THQ values for the different zones were greater than 1but less than 2, with a significant contribution of cobalt.