Appraisal of Heavy Metal Concentrations in Edible Vegetable Abelmoschus esculentus (Lady finger) Grown in Soil Irrigated with Domestic Sewage Water in Sargodha, Pakistan PDF

Keywords

Heavy metals, Wastewater, Abelmoschus esculentus, Maximum permissible limits.

Abstract

Agricultural use of sewage water usually have a positive effect on the yield of vegetable crops. However, sewage water that contains heavy metals can transfer these elements to soils and plants. An investigation has been carried out to evaluate the contamination levels with metals such as chromium (Cr), manganese (Mn), iron (Fe), molybdenum (Mo), lead (Pb) and cadmium (Cd) in soil, and their subsequent accumulation in Abelmoschus esculentus (Lady finger) at two sites in vicinity of District Sargodha, Pakistan. The concentration of heavy metal in the soil at site-I for Cr, Mn, Fe, Mo, Pb and Cd was 0.35, 21.14, 26.63, 10.40,22.18 and 12.97 mg/kg and at site-II was 0.23, 21.18, 26.40, 10.15, 20.28 and 14.48 mg/kg, respectively. The metal concentration at site-I was higher than site-II except for Cd. The magnitude of contamination in vegetable (Abelmoschus esculentus) at the two sites was higher than in the soil. The level of heavy metal (mg/kg dry wt.) in the vegetable at site-I was (in mg/kg) 14.50 for Cr, 54.79 for Mn, 45.24 for Fe, 13.47 for Mo, 1.72 for Pb and 0.24 for Cd and at site-II was 12.26 for Cr, 47.15 for Mn, 49.95 for Fe, 8.92 for Mo, 1.68 for Pb and 0.19 for Cd. Transfer factors in the range of 0.013-52.17mg/kg were obtained, with Cr having the highest transfer factors of 52.17 and 41.42 at site-I and site-II mg/kg, respectively. The pollution load index was 0.04 for Cr, 0.97 for Mn, 0.88 for Fe, 0.43 for Mo, 2.72 for Pb and 1.49 for Cd at site-I and 0.025 for Cr, 0.98 for Mn, 0.87 for Fe, 0.29 for Mo, 2.49 for Pb and 9.72 for Cd at site-II, respectively. Considering the eating habit of inhabitants, the estimated intake rates of heavy metals from consumption of Abelmoschus esculentus in mg day−1 at site-I was Cr (0.05), Mn (7.68), Fe (0.37), Mo (8.55) , Pb (2.82), Cd (1.36) and at site- II, Cr (0.04), Mn (6.61), Fe (0.41), Mo (5.69) , Pb (2.76), Cd (1.10). The daily ingestion of Mn, Mo, Pb and Cd was beyond the oral reference dose hence, the consumption of Abelmoschus esculentus is not considered to be safe for the people living in the sampling area. Thus, although the practice of growing vegetables using wastewater for irrigation is aimed at producing socio-economic benefits, it is not safe and may not be sustainable in the long, as well as in the short term. Due to increased consumption of vegetables by urban communities, it is important to treat industrial effluents which are significant sources of heavy metals and phyto-extract excess metals from polluted environments to reduce health risks.