Wastewater Induced Manganese Toxicity Bioavailability In Spinach (Spinacia Oleracea)

The different types of sewage sludge generated from different urban sources are commonly used for irrigation in agriculture and contain heavy metals (as manganese, cadmium, lead and zinc). This sewage water is mostly used for vegetable production in peri-urban areas and is a source of heavy metals. Therefore, this study was conducted to evaluate the effects of wastewater with different toxicity levels of manganese (Mn) on growth and bio-availability of Mn in spinach The sewage water with two levels of Mn was applied exogenously as i) 150 mg L-1 sewage water (moderately toxic), ii) 350 mg L-1 sewage water (toxic level) and no Mn as control; (only sewage water). Two cuttings of spinach were taken after 45 and 90 days of germination. There was significant accumulation of Mn in leaves. The maximum concentration of Mn (11.13 and 12.67 mg L-1) was recorded with 350 mg L-1 Mn in sewage water at both cuttings, respectively Minimum number of leaves with decrease of 43 and 25% were recorded with Mn 350 mg L-1 (toxic) and 150 mg L-1 (moderate) respectively. Plant biomass and dry weight showed negative behavior in second cutting as compared to first. The results showed that long-term application of Mn contaminated wastewater decreases the growth rate and yield of spinach by increasing its accumulation in leaves up to toxic levels. In conclusion, the application of sewage water to vegetables (especially spinach) should be avoided to prevent human life from health disorders. (C) 2019 Friends Science Publishers