Assessment of heavy metals in vegetables irrigated with Awash River in selected farms around Adama town, Ethiopia

Abstract

A study was conducted at Melka Hida and Wonji Gefersa farms where Awash River was used for cultivation of vegetable crops to assess heavy metal contamination of vegetables. To what extent these vegetables are contaminated is not known. Three leafy vegetable samples, namely, cabbage (Brassica oleracea Linn.), lettuce (Lactuca sativa) and spinach (Spinacea oleracea) from Melka Hida and Wonji Gefersa farms were examined for heavy metal (Cd, Cr and Pb) contamination using atomic absorption spectroscopy. The results indicate that the heavy metals in vegetables of Melka Hida farm were higher than those of the vegetables in Wonji Gefersa farm. In all the samples analyzed, the concentration of Pb and Cd was more than the maximum limit and their levels varied from 0.31 to 0.65 and 0.21 to 0.40 mg/kg, respectively. However, the level of chromium was generally within the normal range in cabbage (0.85 and 0.29 mg/kg) and spinach (1.30 and 1.06 mg/kg) from Melka Hida and Wonji Gefersa farms, respectively, except in lettuce from Melka Hida farm, 2.4 mg/kg. The high levels of these heavy metals place the consumers of these vegetables grown within the study area at health risk with time unless an urgent step is taken by relevant agencies to address this issue.

Heavy Metals in Soil and Vegetables Irrigated with Ex- Tin Mining Ponds Water in Barkin - Ladi Local Government Area Plateau State, Nigeria

“…Cabbage: The mean concentration of heavy metals in the studied cultivated cabbage irrigated with tin mining pond water was found to be Pb (0.164±0.03), Cu (0.065±0.01), Cd (0.01±0.00), Zn (0.18 ±0.02), Cr (0.11±0.01), Fe (1.49±0.07), Mn (0.17±0.01) and As (0.03±0.01) mg/Kg. The concentration of metals in cabbage irrigated with tin mining pond water is lower compared to the reported literature of 0.22±0.2 mg/Kg and 6.25±1.2 mg/Kg 1.61±0.2 [56], [58], [59] mg/Kg). Similar studies conducted show order of concentration of the heavy metals in is: Fe > Mn > Pb > Zn > Cr > Cu ˃ As ˃ Cd [29].…”

Wastewater-irrigated urban vegetable farming in Ethiopia: A review on their potential contamination and health effects

“…Asano et al (2007) reported that a large amount of freshwater is diverted to domestic, commercial and industrial sectors, which generate greater volumes of wastewater. However, there is lack of investment capacity worldwide for construction and operation of adequate treatment facilities which threatens the quality of surface water, soils and groundwater to which wastewater is discharged (Girmaye, 2014).…”

“…World Bank (2007)estimated that one-quarter of the households in Addis Ababa lack any form of sanitation facility and reported that as a consequence of this they use open spaces, shrubs and river banks to relieve themselves. Girmaye (2014) stated that, among the major rivers in Ethiopia, Awash river flows from central highlands through Ethiopia's major industrial and agro-industrial belt, taking in a whole burden of all types of raw effluent stands as one of the Ethiopian river streams in urban areas of developed rivers. Most of the existing industries and major towns within the upper watershed have no treatment plants for the discharge of their wastes and are seriously polluting the watercourse.…”

“…In Mekelle city, urban vegetable producers were using irrigation water from wastewater generated from hotels, hospital and slaughterhouse (Tomass & Kidane, 2012). Girmaye (2014) conducted a study to assess the level of some heavy metal contaminates on vegetables such as lettuce, spinach and cabbage irrigated with Awash river water in Melka Hida and Wonji Gefersa farms in Adama town. The result indicated that cadmium and lead concentration in all vegetables was found above the tolerable limit of 0.2 and 0.3 mg/kg dry weight.…”

“…Despite the great importance of the urban and peri-urban vegetable production in Ethiopia, as informal agriculture as a food source for the urban community and as income generation means for the poor dwellers, it is subject to numerous constraints and is causing high health risks (Delesa, 2017). Heavy metals such as cadmium, copper, lead, chromium and mercury are important environmental pollutants, particularly in areas irrigated with wastewater (Girmaye, 2014). According to Dmello (2000) and Sharma et al (2006), contamination of vegetables with heavy metals and pesticides poses a threat to consumers.…”