Assessment of heavy metals, pH and EC in effluent run-off, river and adjacent soil around a floriculture industry in Holeta, Wadera district, Ethiopia

Heavy metal contents from effluent run-off, neighboring Holeta River, and adjacent soils around floriculture greenhouses in Holeta town, Ethiopia were determined using Atomic Absorption Spectrophotometer (AAS) to assess their potentialities as pollutants. Samples were taken from four sites for the effluent, two river bank locations and two soil locations about 10 meters apart. The evaluated metals were Cu, Fe, Ni, Mn, Cr, Zn, Cd, Co, and Ag. The pH, EC, TDS, DO were determined in the effluent, river and soil samples while particle size and total carbon contents were determined in the soil sample. Results showed that levels of heavy metals were higher in the soil sample than in the effluent and river samples. The metal concentrations ranged from 5.6-1309 mg/kg in soil, 0.31-3.43 mg/L in the river sample and 0.09-0.93 mg/L in the effluent. Highest concentration of Fe (1309 mg/kg), Ni (132 mg/kg), Mn (129 mg/kg), Cu (78 mg/kg), Cd (28.5 mg/kg), Co (5.6 mg/kg) and Zn (0.52 mg/kg) were recorded for the soil samples. These values were above permissible levels for agricultural soils. The findings reveal that the effluent and river samples contained low levels of heavy metals, but the high heavy metal concentrations in the soil could seriously influence soil characteristics by contaminating the soil. Since scanty information is available on the impact of floriculture effluent on agricultural soil in this region, the result of this work could provide baseline data for future monitoring of pollution from the floriculture enterprisesKey words: Heavy metals, AAS, contamination, floriculture and effluents

Size Induced Structural and Magnetic Properties of Nanostructured Cobalt Ferrites Synthesized by Co-precipitation Technique

Cobalt ferrite (CoFe2O4), a well-known hard magnetic material high frequency applications and high-density recording media. Due to their good chemical and thermal stability, high permeability, high electrical resistivity, high saturation magnetization and coercivity etc. they found wide technological applications. Size dependent properties of CoFe2O4 include catalytic properties, electrochemical properties, magnetic properties and optical properties. Thermally induced changes in nanocrystalline CoFe2O4spinel ferrites were synthesized by co-precipitation technique. Unlike other techniques, co-precipitation is reported to be the most economical and successful technique for synthesizing ultrafine CoFe2O4powders having narrow particle size distribution. Their structural and magnetic properties were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) measurements. The average crystallite size of CoFe2O4was observed to increase from 23 to 65 nm as the annealing temperature was increased from 300 to 900°C. The lattice parameters were observed to increase due to increase in the crystallite size. The activation energy (E) of nanostructured CoFe2O4 was observed to be 11.6 kJ/mol. The annealing temperature has a prominent effect on the nanocrystallite growth. The saturation magnetization, coercivity and remanence were observed to increase with increasing crystalite size. In our future work, we plan to synthesize nanocrystalline CoFe2O4 using different techniques in order to understand the role of synthesis techniques on the structural and magnetic properties