Survey of heavy metals in sediments of Kolo creek in the Niger Delta, Nigeria

Concentrations of Fe, Pb, Cr, Ni and V were measured in sediments taken from eight (8) sampling stations along a section of Kolo creek which traverses an oil flow station and a point in Epie creek which receive effluent discharges from human and industrial activities. The study was conducted in four seasons (Dry, Late Dry, Rainy and Late Rainy Seasons). Vanadium was less than 0.001 mg/Kg in all the samples analysed. Fe, Pd, Cr and Ni had annual means of 5109.85, 1.60, 14.22 and 10.18 mg/Kg respectively. One way ANOVA at 95% confidence limit showed no significant difference in the nine (9) sampling stations. However, there was significant difference in the four (4) seasons that the study was conducted. Cluster analysis of the data further classified the four seasons into two groups. Geoaccumulation indices showed that the Creek is not polluted by Pb, Cr and Ni, however, it is highly polluted with Fe. The highest positive correlation was between Pb and Cr while the highest negative correlation was between Fe and Ni. Compared to DPR intervention values, Kolo creek is free from pollution by Pb, Cr and Ni.Key words: Heavy metals, sediment, Kolo creek, cluster analysis, geoaccumulation index

The possible role of local air pollution in climate change in West Africa

The climate of West Africa is characterized by a sensitive monsoon system that is associated with marked natural precipitation variability. This region has been and is projected to be subject to substantial global and regional-scale changes including greenhouse-gas-induced warming and sea-level rise, land-use and land-cover change, and substantial biomass burning. We argue that more attention should be paid to rapidly increasing air pollution over the explosively growing cities of West Africa, as experiences from other regions suggest that this can alter regional climate through the influences of aerosols on clouds and radiation, and will also affect human health and food security. We need better observations and models to quantify the magnitude and characteristics of these impacts

Seasonal Dynamics of Soil Organic Matter and Total Nitrogen in soils under different land uses in Owerri Southeastern Nigeria

The study investigated seasonal dynamics of soil organic matter and total nitrogen in soils affected by different land use types in Owerri, Southeastern Nigeria. A total of 72 soil samples were randomly collected at two monthly intervals in the dry season (October/November, December/January and February/March) and rainy season (April/May, June/July and August/September) at 0-20 cm depth in all the studied land uses, namely soils under continuous cassava cultivation (CCS), pineapple orchard soil (POS), bush fallow (FS) and bare fallow (BF.) . Collected soil samples were air dried, passed through 2mm sieve and were analysed using standard methods. The experiment was factorially arranged in randomized complete block design (RCBD), with three factors namely, season, month and landuse. The treatments were replicated three times. Generated soil data were analysed using analysis of variance (ANOVA) and significant means were separated using least significant difference (LSD) at 5% probability. Results showed that soil organic matter and total nitrogen were significantly higher (P<0.05) in the dry season especially between January and April compared to the rainy season where the least was found around June/July in all the studied land uses, although in all cases, their variability was minimal, ranging from 30.49% in (CCS) to 47.68% in bare fallow. Significant positive correlation (P < 0.05) was found between soil organic matter (SOM) and total nitrogen (r2= 0.966 CCS; 0.935 FS, 0.626 POS, and 0.796 BF), and negative correlation with CN ratio (r2=0.917 CCS; 0.729 FS, 0.3 POS; 0.347 BF), respectively, bulk density (r2 = 0.63) only in FS. Similarly significant negative correlations (P< 0.05) were also found between TN and CN ratio (r2 =0.865 CCS, 0.716 FS, 0.796 POS and 0.328 BF).Keywords. Tropical soil, seasonal variability, total nitrogen, organic matter, land use, Southeasthern Nigeria