Chemical fractionation of metals in core sediments of Orogodo River,southern Nigeria

Sequential chemical extraction of metals (Cu, Ni, Mn, Fe, Pb, Cr, and Zn) from core sediments of the Orogodo River was carried out with a view of providing information on the phase distribution of these metals with respect to depths and seasons. The results indicate that copper was speciated into organic matter/sulfide, Fe–Mn oxides, and residual forms at 0–5?cm depth while at deeper sections copper was predominantly in the residual form. Nickel was speciated mainly into Fe–Mn oxides and residual forms. The average of lead in various particulate phases of the sediment are 0–100% for residual; 0–8% for carbonate; 0–16.2% for exchangeable; 0–10% for organic matter/sulfide form and 22–56% for Fe–Mn oxides bound metals. Manganese was speciated into exchangeable (10–36%) and Fe–Mn oxides bound (10–48%) at the surface layers of 0–20?cm depths and predominantly in the residual form in deeper sections implying partitioning into trioctahydral clay and/or well-defined crystalline oxides. Iron was predominantly in the Fe–Mn oxides and residual fractions, less than 8% in the organic fraction, and 24.4–37.3% in the exchangeable and carbonates fractions at the surface. The percentage contributions of iron in the exchangeable and carbonate fractions decreased to 3.2% at 55–60?cm depth. The amount of chromium in the exchangeable fraction ranged from 0% to 7% for exchangeable; 0–26.5% for organic matter/sulfide bound; 3.8–17.9% for Fe–Mn oxides; and 46.8–100% for residual fraction. The mobility factors of the metals indicated that these metals were relatively mobile at top sections as compared with deeper sections. The overall picture of metal mobility and availability indicates potential contamination risk by Fe, Zn, Mn, and Pb in the Orogodo River sediment system.     

Impacts of Debris-Flow Deposits on Hydrogeochemical Processes and the Development of Dryland Salinity in the Cross-River Catchment, SE, Nigeria

This research focuses on the effect of debris-flow on thevarious hydrogeochemical processes occurring at Cross-River as aresult of disposal of industrial and household wastes as well as sewage into the river. It also focuses on development anddetermination of the saline nature of the rivers dry land.The study is carried out by a survey at different depths of theriver for water and soil samples analysis.The results show that concentrations of cations and anionsreasonably high and uniform except for nitrates which is quitehigh due to agricultural activities occurring in the study areas.Also Mg and SO₄ ions are high due to reactions within thecolluvium include ion exchange of calcium for sodium in basalclays; dissolution of sodium chloride from dust – derived saltparticles in the clay-rich colluvium reactions.The Electrical conductive shows that Cross-River containsdissolved solids. Soil analysis indicates the presence of K, Ca,Mg, and Cl. pH values were also deducted from soil samples (6.30–6.45).     

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.     

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.     

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

ＩｎｔｒｏｄｕｃｔｉｏｎＰｈｙｓｉｃａｌａｎｄｃｈｅｍｉｃａｌｐｒｏｐｅｒｔｉｅｓａｒｅｏｆｇｒｅａｔｓｉｇｎｉｆｉｃａｎｃｅｔｏｔｈｅｗｏｒｋｉｎｇｏｆａｎｙａｑｕａｔｉｃｅｃｏｓｙｓｔｅｍ.Ｉｎｍｏｓｔｃａｓｅｓ,ｔｈｅｃｈｅｍｉｃａｌｐｒｏｐｅｒ...     

Restoration of stream ecosystem integrity in Akwa Ibom State, Nigeria

１ＩｎｔｒｏｄｕｃｔｉｏｎＮａｔｕｒｅｉｎｉｔｓｂｅｎｅｖｏｌｅｎｃｅｐｒｏｄｕｃｅｄｃｏｍｐｌｅｘａｎｄｉｎｔｅｒｅｌａｔｅｄｅｎｖｉｒｏｎｍｅｎｔａｌｓｙｓｔｅｍｓ，ｂｏｔｈｂｉｏｔｉｃａｎｄａｂｉｏｔｉｃ，ｗｈｏｓｅｆｕｎｃｔｉｏｎｉｎｇｉｓｃ...     

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…     

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.     

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.