Assessment of Heavy Metals in Waste-Water Irrigated Lettuce in Ghana: The Case of Tamale Municipality

Maxwell Anim Gyampo,Michael Kumi,Apori Ntiforo

doi:10.5539/jsd.v5n11p93

Abstract

An assessment of some heavy metals concentrations in lettuce in irrigated with waste water in Tamale Metropolis in Ghana has been carried out. Analysis of water and lettuce samples revealed that the mean concentrations of Fe, Mn, Cu, Zn, Cd and Pb in lettuce were 0.436, 0.345, 0.068, 0.017, 0.04 and 0.038 mg/L and 0.167, 0.163, 0.104, 0.127, 0.142 respectively. With exception of Mn and Cd, the concentrations of heavy metals in the irrigation water, irrigated soils and irrigated lettuce, were within the FAO recommended levels. The mean concentrations of nutrients (NO3-N, SO4 and PO4-P) in the wastewater-irrigated lettuce, and well water-irrigated lettuce were 15.36, 0.88, 0.28 and 19.09, 1.117, 0.0573 respectively. Though, heavy metals concentrations in the lettuce were low, regular monitoring are required to prevent heavy metal accumulation with their attendant health implications in the consuming public.

Highlights

As demand for fresh water intensifies, the use of municipal or industrial waste water in agricultural sector is frequently being seen as a common practice in many parts of the world (Ensink et al, 2002; Sharma et al, 2007)
The mean concentrations of the heavy metals (Fe, Mn, Cu, Zn, Cd and Pb) irrigated with irrigation water sources including in the lettuce were recorded as 0.010 to 1.604 mg/l, 0.188 to 0.607 mg/l, 0.037 to 0.100 mg/l, 0.005 to 0.054 mg/l, 0.028 to 0.063 mg/l and 0.010 to 0.020 mg/l respectively (Table 4)
The results indicate that concentrations of nitrate, sulphate and phosphate were detected in the lettuce samples

Summary

Introduction

As demand for fresh water intensifies, the use of municipal or industrial waste water in agricultural sector is frequently being seen as a common practice in many parts of the world (Ensink et al, 2002; Sharma et al, 2007). Previous studies in urban and peri-urban areas in Ghana had revealed that most surface water bodies used for irrigation may be heavily polluted and not suitable for crop irrigation These irrigation waters are considered to contain hazardous chemicals, high levels of salts, harmful pathogens, decomposed human waste and a lot of other contaminants (Mensah et al, 2001; Cornish et al, 1999). For consumption by inhabitants are produced from urban and peri-urban farms These farms are generally sited along waste-water drains, near earth-dams with small reservoirs and broken-down sewers or near dug-outs (This situation is due to the fact that there is no perennial stream within the metropolis but rather, a few seasonal ones which are replenished during the rainy season and dry up in the prolonged dry season (IWMI, 2005). This situation is exacerbated by the occurrence of very low groundwater table within the municipality due to underlying consolidated neo-proterozoic Voltaian sedimentary formation, which is considered to be one of the least in terms of groundwater potential in Ghana (Gyau-Boakye & Dapaah-Siakwan, 2000)

Methods

Results

Conclusion