The chemical forms of copper, lead, manganese and zinc in soils around five selected municipal waste dumpsites in Asaba metropolis, Delta State, Nigeria, were studied, using the Ma and Rao six-step sequential chemical extraction procedure, with a view to providing information on the bioavailability and mobility of the metals in the soil matrix. The results showed that lead and manganese were speciated into residual fractions with averages of 60.32 and 82.24% respectively, while copper and zinc were associated with organic and Fe -Mn oxide fractions respectively with respective averages of 47.91 and 63.21%. The residual fraction also contained relatively high percentages of copper (33.18%) and zinc (20.81%). Relatively very low levels of the metals were found in the water soluble, exchangeable and carbonate fractions. The mobility factors of all the metals in all the soil profiles were generally low ranging from 1.97 to 39.99 indicating generally low availability as well as mobility. Lead and manganese associated with the residual fraction were strongly bound to soil matrix and were not bioavailable since they were occluded within the crystal lattice layer of silicates and well crystallised oxide minerals. Our results show that the metals do not pose any environmental risk or hazard. However, the soils stand the risk of being contaminated by copper and zinc since metals associated with organic and Fe -Mn oxide fractions could be bioavailable and mobilisable when the soil conditions such as pH and redox potentials change.

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Chitosan, a naturally occurring biopolymer extracted from prawn heads was used in the treatment of crump rubber processing effluent for safe disposal into the environment. The triplicate analyses of the effluent samples obtained by composite sampling method indicated high levels of pollution which violated the permissible limits of environmental discharge standards; with a low DO of 0.63mg/L, BOD, 312.00±1.32mg/L and COD, 1069.58±2.42mg/L (mean±SD) respectively. Chitosan was analyzed according to standard procedures; it showed good coagulative potentials from the elemental analysis and a degree of deacetylation of 76.5%. The crump rubber processing effluent was treated with chitosan and Iron (III) Chloride respectively by coagulation and flocculation method and the results obtained via the physico-chemical characterization of the treated effluent showed that the use of chitosan as a coagulant compared favourably with Iron (III) Chloride after treatment. DO levels increased from 0.63mg/L to 3.90 mg/L. There were also remarkable reduction in the Turbidity, Biochemical Oxygen Demand (BOD) and the Chemical Oxygen Demand (COD) levels of the treated samples by over 80% respectively and 70% reduction in the nutrient levels. The efficacy of chitosan in comparison with Iron (III) Chloride suggests that it can be used as a replacement for synthetic coagulants based on its availability and environmental friendliness.

This study focuses on the post effect of flooding on soil quality parameters in agricultural farmlands in Nigeria. Soil samples were collected from farmland in Alihame Agbor, Ika South local government area of Delta state, Okwei in Asaba, Oshimil South local government area of Delta state and fegge in Onitsha South local government area of Anambra state. Farmlands in Asaba and Onitsha were used for the post flooding study, while farmland in Agbor served as control since it was not affected by flooding. Soil physicochemical parameters such as pH, electrical conductivity, total organic carbon, total organic matter, total nitrogen, total phosphorus, cation exchange capacity, moisture content and metals (Cd, Pb, Cu, Mn, Ni and K) which were used as index for assessing the effect of flooding on soil quality were analyzed using standard methods. Significant effect of flooding was observed on soil properties on the flood affected farmlands when compared to the control farmland, which was statistically justified at 95% confidence limit (p ≤ 0.05). There were considerable decreases ranging from 4% to 53% at p ≤ 0.05 in the values of pH, total organic carbon, total organic matter, total nitrogen, total phosphorus and cation exchange capacity on the flood affected farmlands when compared to the control farmland; except for electrical conductivity where an increase of 54% and 92% at the flood affected farmlands in Asaba and Onitsha respectively was observed when compared to the control. Higher moisture contents were also recorded of up to about 17% and 45% at the flood affected farmlands in Asaba and Onitsha respectively, when compared to the control. Reduced concentrations ranging from 25% to 49% of essential micronutrients such as Mn, Ni and K were observed on the flood affected farmlands, reflecting the negative impact of the flood. Undesirable effect of the flood was also observed in the flood affected farmlands when compared to the control farmland as increased concentrations ranging from 18% to 114% of Cd, Pb, and Cu, were recorded. The findings of this study revealed significant impacts of the resulting flood on soil quality of the affected farmlands with major attendant effect of the flood felt on farmland in Asaba. As a consequence, measures should be put in place by government and concerned agencies to avoid future flooding of farmlands so as not to further expose the natural quality of these farmlands to the degradative and devastating effect of such flooding.