No abstract

Although, many heavy metals are necessary in small amounts for the normal development of the biological cycles, most of them become toxic at high concentrations. The major sources of heavy metal pollution in urban areas of Nigeria are anthropogenic, while contamination from natural sources predominates in the rural areas. The study examined heavy metal status of boreholes in Calabar South, Cross River of Nigeria. Four functional boreholes in the area were sampled. Result showed that the concentrations of iron (Fe), zinc (Zn) and Manganese (Mn) were within WHO maximum permissible limit with mean values of 0.065ml-1 g, 0.015mgl-1 and 0.002mgl-1 respectively. The proportion of copper (Cu), chromium (Cr) and lead (Pb) in the sampled boreholes was zero, indicating the absence of these metals in the sampled boreholes. The absolutely low levels of heavy metal contents across the sampled boreholes showed they were not polluted and as such suitable for human consumption. The low content also revealed that boreholes in the area were located far away from dumpsites; soak away pits, automobile shops and other forms of heavy metal contaminants. In order to maintain quality status of boreholes in the area, routine monitoring and assessment of boreholes mostly the indiscriminate sinking of boreholes in the area by sanitary inspection officers was suggested.

No abstract

The study evaluated the influence of vegetation characteristics on nutrient loss in vegetation fallows in a part of the rainforest belt in Agoi-Ekpo, Cross River State. Participatory method was used to identify fallows of 3-year and abandoned farmland. In each identified fallow category, 10 plots for vegetation estimation was established, while two runoff plots of 10m x 4m was constructed and used for nutrient loss estimation. Data was gathered during the cropping season of March to November, 2012. Results showed that on the 3-year fallow only basal cover was retained by the model and significantly explained Ca loss (R 2 = 0.627, F = 3.655, p<0.01), Mg loss (R 2 = 0.57.2, F = 3.271, p<0.05) and potassium loss (R 2 =0.527, F = 2.980, p<0.05). On the abandoned farmland, the model retained only crown cover and it significantly explained OC loss (R 2 = 0.591, F = 3.402, p<0.01), TN (R 2 = 0.599, F = 3.456, p<0.01), Ca (R 2 = 0.674, F = 4.067, p<0.01), Mg (R 2 = 0.796, F = 5.75, p<0.01) and K (R 2 = 0.823, F = 6.090, p<0.01). The study showed that more nutrient element losses were recorded in the abandoned farmland. The study suggests that trees and shrubs should not be completely cut down on farmlands facilitate rapid vegetation restoration during land abandonment.

The paper evaluated the effects of industrial activities on the structure and floristic pattern of woody tree/shrub species in the Calabar Port Authority. Three plots of 0.16 ha were employed to collect vegetation parameters (structure and floristic) from vegetation adjoining highly impacted site (HIS) and of less impacted site (LIS). Shannon-Wiener's index showed that vegetation in the LIS was more diverse and heterogeneous than vegetation in the HIS with species diversity index of 2.29 and 2.26 respectively; whereas, the index of evenness revealed what tree/shrub species encountered at the HIS (0.53) were fairly equally abundant compared to tree/shrub species in the LIS (0.44). Vegetation in the LIS was richer at both spatial scale and taxonomic level than vegetation in the HIS, as a result of the favourable edaphic conditions and absence of toxic substances that facilitated vegetation growth. Therefore, to preserve the threatened diversity of available tree/shrub species in the area, government was encouraged to enact laws to stop the destruction and transformation of remaining hectare of vegetation into industrial and residential estates.