| Popis: |
Objective Urban and peri-urban agriculture is being promoted as a sector of livelihood and economic activities in many parts of the world including Ethiopia. Mekelle city is one of the Ethiopian cities suitable for urban and peri-urban agriculture for cultivating leafy vegetables using wastewater. The consumption of unprocessed and processed leafy vegetables is also very high in the city. However, the quality of the produces has been of a great public health concern. Thus, this study was aimed to investigate the quality of wastewaters in Hadnet district of Mekelle used to irrigate lettuce, spinach and cauliflower and the safety of the vegetables in terms of accumulation heavy metals. Result Wastewater samples collected from four experimental sites in the district were found to have higher concentrations in 4 (i.e., Cd, Cr, Cu, and Mn) of the 10 heavy metals tested than the permissible limit estbalished by the FAO (1985). Interestingly, spring water samples collected from another district called Kallamino, designated as comparison site, also have higher concenterations in 4 (i.e., Al, As, Cd, and Cu) of the 10 heavy metals tested. But the leafy vegetables grown in the least contaminated experimental site was found to have higher concentrations in 6 or 7 of the 10 heavy metals tested. Vegetables grown in the comparison site were nearly clean. The lettuce and spnach had elevated concentration of As and Al, respectively. While the fast growing lettuce has higher accumulation of the heavy metals, the slow growing cauliflower had lower accumulation. Such elevated accumulaion of heavy metals in these vegetables could be due to the presence of higher soil contamination and enahnced bioaccumulation capacity of the plants. Conclusion The wastewater used to irrigate vegetable farms in Hadnet district of Mekelle is not safe enough. More importantly, the soils of the farms might have accumulated far more amount of heavy metals. The lettuce, spinach and cauliflower cultivated there are highly contaminated. Thus, the use of wastewater for irrigating urban and peri-urban farms need to be regulated, the suitability of the soils of the farms need to be examined, and consumers of these leafy vegetables need be cautious. |
