Assessment of Heavy Metal Accumulation in Lactuca sativa and Amaranthus caudatus Irrigated with Effluent from Gusau Water Treatment Plant, Zamfara State, Nigeria

Heavy metal pollution poses significant environmental and health challenges globally, especially in developing countries where untreated industrial effluents are commonly used for irrigation. This study assesses the heavy metal accumulation in Lactuca sativa (lettuce) and Amaranthus caudatus (amaranth) irrigated with effluent from the Gusau Water Treatment Plant, Zamfara State, Nigeria. Effluents and associated agricultural soils were analyzed for physicochemical properties (pH, temperature, electrical conductivity, total dissolved solids) and concentrations of key heavy metals (Cu, Cr, Fe, Pb) using standard methods. Vegetative tissues of lettuce and amaranth were similarly assessed for heavy metal content. Physicochemical analysis revealed variations across sites, with electrical conductivity (EC) at some sites exceeding WHO limits for irrigation, potentially impacting soil and crop health. Heavy metal analysis indicated significant differences in chromium (Cr) concentrations among effluent, soil, and vegetables, while copper (Cu) and lead (Pb) levels remained consistent but low. Iron (Fe) concentrations, though higher, remained within tolerable limits for plant nutrients. Findings suggest that while the effluent supports vegetable cultivation, it poses risks of heavy metal accumulation, with Cr presenting the greatest concern. Regular monitoring and treatment of irrigation effluents are recommended to mitigate risks to human health and the environment.