Accumulation of heavy metals and bacteriological indicators in spinach irrigated with further treated secondary wastewater

Abstract

Shortage of water for agriculture has resulted in the need to explore the use of wastewater for irrigation, however this can pose a health problem to the people emanating from the produced food as a result of the accumulation of pollutants. The purpose of this research was to investigate the accumulation of some heavy metals and bacteriological indicators in the different parts of spinach vegetable irrigated with secondary wastewater effluent treated through a pilot filtration system. There was a variation of heavy metals accumulation in the roots, stem and leafy parts of the vegetable. Bioaccumulation factors of some metals were greater than 1 in the roots and stems but not in the leaves. Three heavy metals being copper, iron and zinc revealed high translocation factors in the stems than leaves; whereas arsenic, chromium, nickel, manganese and lead had high translocation factors in the leaves than stems. Health index coefficients in the stem during the first, second and third months were 2.33, 0.18 and 3.57 respectively, and corresponding values in the leaves were 0.68, 0.09 and 6.75 if consumed by adults. The health index values greater than 1 in children were 2.68 in the stem during the first month and then 4.1 and 7.76 in the stem and leaves during the third month for spinach consumed by children. There was no bacteriological indicators detected in the aboveground parts of the vegetable. To conclude, irrigation of vegetables should be practiced using secondary treated wastewater and monitoring over time intervals in order to safe guard human health.