Effects of diverse irrigation with wastewater in soil and plants: assessing the risk of metal to the animal food chain

In District Jhang, farmers use municipal wastewater to irrigate fodder crops as an alternative source to the deficient availability of fresh water. Therefore, the present study selected the three irrigation sources in District Jhang (canal water, ground water and municipal wastewater) to study the iron (Fe) concentration in the soil, fodder crops and ultimately their transfer into the animal body. Analysed Fe concentration varied as 16.40–27.53 mg/kg in soil samples, 19.72–30.34 mg/kg in fodder crops and 2.49–5.11 mg/kg in animals. Analysed Fe concentration in soil was higher on the wastewater irrigation site while canal water-irrigated fodder crop Zea mays exhibit the higher Fe concentration. In animal samples, higher Fe concentration was observed in the cow blood (4.09 mg/l), cow hairs (3.39 mg/kg) and cow faeces (5.11 mg/kg). Results of pollution load index (0.288–0.484 mg/kg) and enrichment factor (0.112–0.197 mg/kg) indicated that Fe concentration was minimally dispersed and enriched in these sites. Health risk and daily intake values were observed between the 0.029–0.059 and 0.042–0.084 mg/kg/day. Bio-concentration factor (0.834–1.47 mg/kg) for Fe which was greater than 1 explains that Fe contamination was transferred from the soil to fodder tissues and may raise health issues in the grazing animals if they are continuously exposed to these contaminated forages. Wastewater irrigation in study area has increased the Fe content in soil–plant environment that is a risking factor for animal and human health. Hence, this study recommended that wastewater should be treated prior to their irrigation on agricultural lands.