Concentrations of Cd, Hg, Pb, Cr, Fe, Co, Ni, Cu, Zn, Mo and As were determined in soils and leaves of plants from refuse dumpsites and background soils in two cities, a municipality and a rural community in Ghana, using a ThermoFinnigan Element 2 high resolution inductively coupled plasma mass spectrometric (HR-ICP-MS) instrument. The refuse dump soils were classified between 'Uncontaminated to Moderate' and 'Strongly Contaminated'. Pollution levels for Cd (Igeo = 2.06–2.40) and Zn (Igeo = 2.95–3.36) were higher than of the other metals. The refuse dump soil from the rural community was the least polluted with the metals. Fe and Ni loads in plants from the refuse dump soils in the cities and the municipality were beyond the normal ranges of 40–500 µg/g (Fe) and 0.02–5.00 µg/g (Ni). Transfer ratios for Cd, Hg, Cu, Zn and Pb and Fe of plants from the background soils were higher than those from the refuse dump soils, which might be due to the higher levels of organic matter, pH, phosphate, Ca and Mg in the refuse dump soils.

In the face of climate change, quantification of the emission of nitrous oxide from soils in relation to sufficient N availability for crop uptake has assumed much significance. This study used the 15 N stable isotope technique, under controlled laboratory conditions, to quantify the interactive effect on and relative contributions of the component species to N 2 O emission and mineral N dynamics in a tropical luvisol incorporated with different rates of cowpea-maize residue mixtures. The results show that increasing the maize residue proportion in the mixture significantly decreases N 2 O emission compared to the sole cowpea incorporation but increases mineral N concentration compared to sole maize residue incorporation. It is concluded that mixing low C:N ratio cowpea residue with high C:N ratio maize residue has potential for N management in tropical legume-cereal intercropping systems with the view to minimizing N 2 O emission while making N available for crop uptake.

The concentrations of eight trace elements, Cadmium (Cd), lead (Pb), iron (Fe), zinc (Zn), manganese (Mn), copper (Cu), mercury (Hg) and arsenic(As) in sediment and water were assessed in four artisanal and small-scale mining(ASM) localities in the Amansie West District (6°282 N 1°532 W) of Ghana along two river courses from May 2011 to July 2011. Triplicate water and sediment samples were randomly taken at five different points at each of the localities and the elements determined using Atomic Absorption Spectrophotometer (AAS ). Using the Geoaccumulation Index( I geo ) assessment, the sediments were found to be polluted to different degrees with Cu (Uncontaminated to moderately contaminated/Moderately contaminated), Hg (Uncontaminated to moderately contaminated/Moderately contaminated) and As (Moderately contaminated/Moderately to strongly contaminated). The Enrichment Factor (EF) indicated human influence -artisanal mining activities on the sediment concentration of Cd and Pb for all the localities and only some of the localities for the rest of the trace elements. The elements are major sediment pollutants ( EF > 2) in one or more of the localities. The I geo and EF gave diverse status of the sediment qualities of the localities. Cd, Pb, Hg and As water concentrations in the four artisanal mining localities were all found to be above the WHO maximum acceptable of levels for drinking water. Inhabitants in the mining localities face the risk of getting various diseases by drinking the waters contaminated with the trace elements.

A study was conducted in pots on the field to assess the effect of different quantities of poultry manure (PM), cattle manure (CM) and pig manure (PG) on the release of available phosphorus from Togo rock phosphate (RP) and lettuce growth. There were eleven (11) treatments which were: Control (soil only); 2.5g RP; 2.5g CM; 2.5gRP + 2.5g CM; 2.5gRP + 5gCM; 2.5gPM; 2.5gRP + 2.5gPM; 2.5gRP + 5gPM; 2.5gPG; 2.5gRP + 2.5gPG; 2.5gRP + 5gPG, applied per kg soil, using the Completely Randomized Design (CRD) with three replications. Available phosphorus and other parameters were assessed using standard methods. Results were statistically analyzed using the the GenStat (11 th Edition) statistical software package. The amount and type of animal manure in the amendment affected the amount of the available P released. The addition of 2.5g manure to 2.5g RP in a kg of soil significantly (P<0.05) increased available P by 4 to 7 times over the sole 2.5g RP/kg soil treatment. Doubling the amount of manure in the amendment (5g manure + 2.5g RP) almost doubled the amount of P released, with the poultry manure combinations being more significant. The amount of available P in the soil positively related to the plant height (R 2 =63), leaf area (R 2 =0.55), dry weight (R 2 =0.73) and the percentage P in the leaf (R 2 =0.88) of lettuce. The PM at 2.5gRP + 5gPM recorded the highest significant (P<0.05) values. The study has provided further basis for manure selection and quantities to be used in enhancing the release of P from rock phosphate. However, investigations need to be continued using nuclear techniques.

A laboratory microcosm incubation was conducted to study the influence of mixed cowpea-maize residues on N2O emission and N mineralization in a tropical acrisol. The soils were incorporated with different ratios of cowpea:maize mixtures on weight basis: 100:0, 75:25, 50:50, 25:75 and 0:100, and a control treatment in which there was no residue incorporation. The results show that N2O and CO2 emissions were higher in the sole cowpea treatment (100:0) than the sole maize treatment (0:100) and the control. However, cowpea-maize residue mixtures increased the proportion of N lost as N2O compared to the sole treatments. This interactive effect was highest in the 75:25 treatment. The 50:50 treatment showed moderate N2O emission compared to the 100:0, 75:25 and 25:75 treatments but with corresponding steady N mineralization and appreciable mineral N concentration. It is concluded that mixing cowpea-maize residues might increase the proportion of N lost as N2O in a tropical acrisol. However, compared to the other residue mixture treatments, mixing cowpea-maize residues in equal proportions on weight basis might offer a path to reducing N2O emissions while maintaining a steady N mineralization without risking good N supply in acrisols. The study therefore offers potential for mitigating greenhouse gas emissions while maintaining soil fertility in tropical acrisols. However, further studies under both laboratory and field conditions will be required to verify and validate this claim

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Airborne lead levels were assessed in nine workshops, three each from battery, electronic repair, and welding sources within the Kumasi Metropolis in Ghana. Samples were collected at 0, 2.5, and 5.0 m away from the emission source at the workshops during working hours and another at 5.0 m during break hours. Airborne lead particulates were collected and analyzed using the filter membrane technique and flame atomic absorption spectrophotometry, respectively. There were significant differences (p < or = 0.05) among the air lead levels from the workshops. Workshop 3b produced the highest significant values of air lead concentrations of 2,820.31 +/- 53.89, 2,406.74 +/- 71.87, 754.55 +/- 72.52, and 549.01 +/- 67.30 microg/m(3) at distances of 0, 2.5, 5.0, and 5.0 m (break-time measurement), respectively, while workshop 1w significantly produced the lowest air lead concentration values of 261.06 +/- 21.60, 190.92 +/- 36.90, 86.43 +/- 16.26, and 61.05 +/- 3.88 microg/m(3) at distances of 0, 2.5, 5.0, and 5.0 m (break-time measurement), respectively. The air lead levels reduced with distance from emission source at the workshops. At all the distances of measurement at working hours, the airborne lead levels were higher than the World Health Organization standard of 50 microg/m(3) and exceeded the threshold limit values of 100 to 150 microg/m(3) recommended in most jurisdictions. Workers and people in the immediate environs were exposed to air lead levels that were too high by most international standards, thus posing a serious threat to their health.

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