Variations in oxygen and some related pollution parameters in some streams in ITU Area of Nigeria

ＩｎｔｒｏｄｕｃｔｉｏｎＰｈｙｓｉｃａｌａｎｄｃｈｅｍｉｃａｌｐｒｏｐｅｒｔｉｅｓａｒｅｏｆｇｒｅａｔｓｉｇｎｉｆｉｃａｎｃｅｔｏｔｈｅｗｏｒｋｉｎｇｏｆａｎｙａｑｕａｔｉｃｅｃｏｓｙｓｔｅｍ.Ｉｎｍｏｓｔｃａｓｅｓ,ｔｈｅｃｈｅｍｉｃａｌｐｒｏｐｅｒ...     

Soil N balance as affected by soybean maturity class in the Guinea savanna of Nigeria

Legume–cereal rotation may reduce the fertilizer requirement of the cereal crop and we hypothesize that the benefit depends on the maturity class of the soybean. Field trials were therefore conducted in 1995 in four Guinea savanna sites to monitor the effect of soybean (Glycine max (L.) Merrill) cultivation on the N balance of the soil. In trial 1, an early (TGx1485-1D) and a late (TGx1670-1F) soybean were grown to maturity along with a maize (Zea mays L.) reference plot. In trial 2, six varieties of soybean (early: TGx1485-1D, TGx1805-2E and TGx1681-3F; medium: TGx1809-12E and TGx923-2E; late: TGx1670-1F) were grown to maturity along with a reference maize plot. The total nitrogen (N) content, aboveground N₂ fixed, and N remaining in the stover were higher in the medium and the late varieties than in early varieties. Also, the early varieties had higher nitrogen harvest indices (81–84%) than medium and late varieties (74–79%). From the N balance calculation, it was found that medium and late maturing soybean resulted in an addition of 4.2 kg N ha⁻¹ to the soil, whereas the early maturing varieties resulted in depletion of the soil N reserve by 5.6 kg N ha⁻¹ (P<0.05). On average, among the medium and late varieties, late maturing TGx923-2E resulted in an addition of 9.5 kg N ha⁻¹ to the soil. When the stover was not returned to the field, early soybean resulted in more negative N balance than the medium and late soybean (P<0.05). Therefore, planting an early variety of soybean for one season resulted in net depletion of soil N, even when the soybean residues were returned to the soil and N₂ fixed in the roots and N in the fallen leaf litter were included in the N balance calculations. Contrary to this, planting medium and late soybean for one season resulted in an addition of N to the soil. Therefore, medium and late soybean should be used as a preceding crop in legume–cereal rotation, if possible, to minimize or avoid depletion of soil N by early varieties of soybean.     

Assessment of Iodine Deficiency and Goitre Incidence in Parts of Yewa Area of Ogun State, Southwestern Nigeria

This study was carried out to determine the occurrence, prevalence and contributing factors to the incidence of goitre in Yewa north local government area of Ogun state, southwestern Nigeria. To achieve these objectives, soil, water, and cassava tubers were collected from four villages – Igbogila, Egua, Sawonjo and Imoto and from Lagos (about 250 m to the ocean) as a reference location, in order to determine their iodine concentrations. The results of the analyses indicated a soil mean iodine range of 2.1–5.8 μg g⁻¹; a cassava mean iodine value of 2.3–3.5 μg g⁻¹ and a drinking water mean iodine value of generally <1.0 μg L⁻¹ in all the four villages. These values of iodine in soil and water of the four villages are considered low when compared with the soil iodine value of 7.4 μg g⁻¹ and water iodine value of 6.1 μg L⁻¹ obtained from Lagos. The limestone unit of the study area remains an inhibiting factor in the bioavailability of the iodine because of its alkalinity. Statistical analysis has shown that there was significant difference between iodine concentration in the soils and the drinking water, and a correlation between the soil iodine and organic matter content at p < 0.05. The correlation between soil iodine and granulometric fractions occurred at p < 0.01. Potential goitrogens in the commonly consumed cassava products might also have contributed to the prevalence of goitre in the study area. Both the females and the adults (i.e., less mobile groups) were found to be vulnerable to goitre development in these villages.     

Morphometric relationships and reproductive maturation of the mudskipper,Periophthalmus barbarus from subsistence catches in the mangrove swamps of IMO estuary,Nigeria

ＩｎｔｒｏｄｕｃｔｉｏｎＮｉｇｅｒｉａｎｍａｎｇｒｏｖｅｓｗａｍｐｓｈａｖｅｇｒｅａｔｆｉｓｈｅｒｉｅｓｐｏｔｅｎｔｉａｌｓａｎｄｍｕｃｈｉｓｓｔｉｌｌｎｅｅｄｅｄｔｏｐｒｅｓｅｒｖｅｔｈｅｅｃｏｓｙｓｔｅｍｉｎｖｉｅｗｏｆｔｈｅｐｏｔｅｎｔｐｒｅｖａｌｅｎｃｅａｎｄａｇｇｒｅｓｓｉｖｅｒｅｐｌａｃｅｍｅｎｔｏｆｔｈｅｍａｎｇｒｏｖｅ (Ｒｈｉｚｏｐｈｏｒａ)ｂｙｔｈｅｅｘｏｔｉｃｎｉｐａｐａｌｍｓ (Ｎｙｐａ) (Ｍｏｓｅｓ,1 985;Ｗｉｌｃｏｘ ,1 985;Ｋｉｎｇ ,1 997) .Ａｍｏｎｇｔｈｅｃｏｍｍｏｎｆａ…     

Restoration of stream ecosystem integrity in Akwa Ibom State, Nigeria

１ＩｎｔｒｏｄｕｃｔｉｏｎＮａｔｕｒｅｉｎｉｔｓｂｅｎｅｖｏｌｅｎｃｅｐｒｏｄｕｃｅｄｃｏｍｐｌｅｘａｎｄｉｎｔｅｒｅｌａｔｅｄｅｎｖｉｒｏｎｍｅｎｔａｌｓｙｓｔｅｍｓ，ｂｏｔｈｂｉｏｔｉｃａｎｄａｂｉｏｔｉｃ，ｗｈｏｓｅｆｕｎｃｔｉｏｎｉｎｇｉｓｃ...     

Effects of drilling fluids on marine bacteria from a Nigerian offshore oilfield

Two marine bacterial isolates from drill mud cuttings obtained from Agbara oilfield,Staphylococcus sp. andBacillus sp., were cultured aerobically in the presence of varying concentrations (0, 25, 50, and 75 μg/ml) of drilling fluids to determine the effects of concentration of toxicants on their growth. With the exception of Clairsol, Enviromul, and Baroid mineral oil, which had little or no effect, the exponential growth ofBacillus sp. was depressed by all other test chemicals. Additionally, all test chemicals except Clairsol had no effect on lag phase of growth ofBacillus sp. WithStaphylococcus sp. the depressive effect on the exponential phase of growth was shown by almost all test chemicals. There was enhancement of both growth rate and generation times ofStaphylococcus sp. and decrease of those ofBacillus sp. with increasing concentrations of drilling fluids. These results show that while some drilling fluids may be stimulatory or depressive to bacterial growth, others may be without effect.     

Nutrient requirements for the growth of waterleaf (Talinum triangulare) in Uyo metropolis, Nigeria

The all-season vegetable known as waterleaf (Talinum triangulare) is extensively grown in Nigeria's metropolistan market gardens. This paper examines the soil compositions of some of the cultivation areas for this crop to determine the impacts of its very intensive repetitive cultivation. In general, the regular application of organic manures and mineral fertilizers has maintained the fertility status of the market garden soils. Multiple regression analysis indicated that base saturation, available phosphorus and organic matter were the most significant determinants to variations in crop production.     

Assessing corporate–community involvement strategies in the Nigerian oil industry: An empirical analysis

The desire of oil companies operating in the Niger Delta to secure their social license to operate, and address their community development obligations, has led in recent years to the adoption of corporate social responsibility (CSR) policies and strategies. Drawing on quantitative and qualitative data collected in host communities within the Niger Delta in Nigeria, the paper compares the effectiveness of two different corporate–community involvement strategies. The evidence suggests that while the corporate–community foundation model has certain advantages over the in-house community investment model, both approaches suffer from a common shortcoming that limits the impact of oil companies’ efforts on community development in their host communities. The paper concludes by exploring the implications of the research findings for corporate–community involvement in the Nigerian oil industry.     

A study of heavy metal pollution of Asa River, Ilorin. nigeria; trace metal monitoring and geochemistry

Chemical and mineralogical characterization of sediments collected from seven different locations along Asa River in Ilorin, Nigeria have been carried out. The total concentration of Mn, Cr, Fe, Zn and Cu were monitored using Total Reflection X-ray Fluorescence (TXRF). The range of concentration of these metals were: Mn (179.9–469.4, Fe (1998.4–4420.4) Cr (3.0–11.3), Zn (26.6–147.6), Cu (1.9-13.3) mg kg⁻¹. The mineralogical composition was determined using X-ray diffraction (XRD) method and this was complemented with the Infrared Spectroscopy. It was found that the sediments of Asa River had predominantly quartz, and goethite was present in five of the seven locations. Chromite (FeCr₃O₄) and pyrite (FeS) were also identified at some locations along the River. Higher enrichment factors were calculated for Zn, Cr, Mn, and Fe in the sediment indicating anthropogenic source of contamination. Pyrite was prominent at a location receiving effluent from a detergent industry and near a refuse dumpsite.     

Metal Pollution Assessment of Surface Sediments Along a New Gas Pipeline in the Niger Delta (Nigeria)

Chromium, nickel, copper, zinc and cadmium were determined in sediments of the Niger Delta (Nigeria) in order to discriminate between natural metal sources and anthropogenic ones. Surface sediments were collected at seven sites along a new gas pipeline near Port Harcourt, between the New Calabar River and the Bonny River towards Bonny town. Chemical characterisation is obtained by hydrofluoric–nitric acid digestion procedure, providing the ‘total’ (‘residual’) metal contents. Information about the anthropogenic metal fraction was obtained by cold diluted hydrochloric acid extraction procedure. This ‘labile’ acid soluble fraction of metals, perhaps due to relatively recent inputs in the sediments, constitutes the fraction more likely to be available to marine organisms, and furnishes a first evaluation of the possible toxicity of sediments of this sensitive ecosystem. Zinc appears to be the most available of all the heavy metals: its ‘labile’ fraction attains 40–50% of the ‘total’ zinc in sediment. Sites near Port Harcourt city are the most contaminated. All the examined metals are one order of magnitude below the respective values proposed as a limit for toxicity and are comparable with those observed by other authors in similar Niger Delta areas. Some anomalous data found near Port Harcourt city suggest that zinc and cadmium are the metals that require further monitoring. Their anthropogenic source could be derived from urban and industrial sewage.